An empirical model for parameters affecting energy consumption in boron removal from boron-containing wastewaters by electrocoagulation.

PubMed

Yilmaz, A Erdem; Boncukcuoğlu, Recep; Kocakerim, M Muhtar

2007-06-01

In this study, it was investigated parameters affecting energy consumption in boron removal from boron containing wastewaters prepared synthetically, via electrocoagulation method. The solution pH, initial boron concentration, dose of supporting electrolyte, current density and temperature of solution were selected as experimental parameters affecting energy consumption. The obtained experimental results showed that boron removal efficiency reached up to 99% under optimum conditions, in which solution pH was 8.0, current density 6.0 mA/cm(2), initial boron concentration 100mg/L and solution temperature 293 K. The current density was an important parameter affecting energy consumption too. High current density applied to electrocoagulation cell increased energy consumption. Increasing solution temperature caused to decrease energy consumption that high temperature decreased potential applied under constant current density. That increasing initial boron concentration and dose of supporting electrolyte caused to increase specific conductivity of solution decreased energy consumption. As a result, it was seen that energy consumption for boron removal via electrocoagulation method could be minimized at optimum conditions. An empirical model was predicted by statistically. Experimentally obtained values were fitted with values predicted from empirical model being as following; [formula in text]. Unfortunately, the conditions obtained for optimum boron removal were not the conditions obtained for minimum energy consumption. It was determined that support electrolyte must be used for increase boron removal and decrease electrical energy consumption.

Optimization of Maillard Reaction in Model System of Glucosamine and Cysteine Using Response Surface Methodology

PubMed Central

Arachchi, Shanika Jeewantha Thewarapperuma; Kim, Ye-Joo; Kim, Dae-Wook; Oh, Sang-Chul; Lee, Yang-Bong

2017-01-01

Sulfur-containing amino acids play important roles in good flavor generation in Maillard reaction of non-enzymatic browning, so aqueous model systems of glucosamine and cysteine were studied to investigate the effects of reaction temperature, initial pH, reaction time, and concentration ratio of glucosamine and cysteine. Response surface methodology was applied to optimize the independent reaction parameters of cysteine and glucosamine in Maillard reaction. Box-Behnken factorial design was used with 30 runs of 16 factorial levels, 8 axial levels and 6 central levels. The degree of Maillard reaction was determined by reading absorption at 425 nm in a spectrophotometer and Hunter’s L, a, and b values. ΔE was consequently set as the fifth response factor. In the statistical analyses, determination coefficients (R2) for their absorbance, Hunter’s L, a, b values, and ΔE were 0.94, 0.79, 0.73, 0.96, and 0.79, respectively, showing that the absorbance and Hunter’s b value were good dependent variables for this model system. The optimum processing parameters were determined to yield glucosamine-cysteine Maillard reaction product with higher absorbance and higher colour change. The optimum estimated absorbance was achieved at the condition of initial pH 8.0, 111°C reaction temperature, 2.47 h reaction time, and 1.30 concentration ratio. The optimum condition for colour change measured by Hunter’s b value was 2.41 h reaction time, 114°C reaction temperature, initial pH 8.3, and 1.26 concentration ratio. These results can provide the basic information for Maillard reaction of aqueous model system between glucosamine and cysteine. PMID:28401086

Optimization of Maillard Reaction in Model System of Glucosamine and Cysteine Using Response Surface Methodology.

PubMed

Arachchi, Shanika Jeewantha Thewarapperuma; Kim, Ye-Joo; Kim, Dae-Wook; Oh, Sang-Chul; Lee, Yang-Bong

2017-03-01

Sulfur-containing amino acids play important roles in good flavor generation in Maillard reaction of non-enzymatic browning, so aqueous model systems of glucosamine and cysteine were studied to investigate the effects of reaction temperature, initial pH, reaction time, and concentration ratio of glucosamine and cysteine. Response surface methodology was applied to optimize the independent reaction parameters of cysteine and glucosamine in Maillard reaction. Box-Behnken factorial design was used with 30 runs of 16 factorial levels, 8 axial levels and 6 central levels. The degree of Maillard reaction was determined by reading absorption at 425 nm in a spectrophotometer and Hunter's L, a, and b values. ΔE was consequently set as the fifth response factor. In the statistical analyses, determination coefficients (R 2 ) for their absorbance, Hunter's L, a, b values, and ΔE were 0.94, 0.79, 0.73, 0.96, and 0.79, respectively, showing that the absorbance and Hunter's b value were good dependent variables for this model system. The optimum processing parameters were determined to yield glucosamine-cysteine Maillard reaction product with higher absorbance and higher colour change. The optimum estimated absorbance was achieved at the condition of initial pH 8.0, 111°C reaction temperature, 2.47 h reaction time, and 1.30 concentration ratio. The optimum condition for colour change measured by Hunter's b value was 2.41 h reaction time, 114°C reaction temperature, initial pH 8.3, and 1.26 concentration ratio. These results can provide the basic information for Maillard reaction of aqueous model system between glucosamine and cysteine.

Highly efficient method towards in situ immobilization of invertase using cryogelation.

PubMed

Olcer, Zehra; Ozmen, Mehmet Murat; Sahin, Zeynep M; Yilmaz, Faruk; Tanriseven, Aziz

2013-12-01

A novel method was developed for the immobilization of Saccharomyces cerevisiae invertase within supermacroporous polyacrylamide cryogel and was used to produce invert sugar. First, the cross-linking of invertase with soluble polyglutaraldehyde (PGA) was carried out prior to immobilization in order to increase the bulkiness of invertase and thus preventing the leakage of the cross-linked enzyme after immobilization by entrapment. And then, in situ immobilization of PGA cross-linked invertase within cryogel synthesis was achieved by free radical polymerization in semi-frozen state. The method resulted in 100 % immobilization and 74 % activity yields. The immobilized invertase retained all the initial activity for 30 days and 30 batch reactions. Immobilization had no effect on optimum temperature and it was 60 °C for both free and immobilized enzyme. However, optimum pH was affected upon immobilization. Optimum pH values for free and immobilized enzyme were 4.5 and 5.0, respectively. The immobilized enzyme was more stable than the free enzyme at high pH and temperatures. The kinetic parameters for free and immobilized invertase were also determined. The newly developed method is simple yet effective and could be used for the immobilization of some other enzymes and microorganisms.

Effect of pH on lead removal from water using tree fern as the sorbent.

PubMed

Ho, Yuh-Shan

2005-07-01

The sorption of lead from water onto an agricultural by-product, tree fern, was examined as a function of pH. The sorption processes were carried out using an agitated and baffled system. Pseudo-second-order kinetic analyses were performed to determine the rate constant of sorption, the equilibrium sorption capacity, and the initial sorption rate. Application of the pseudo-second-order kinetics model produced very high coefficients of determination. Results showed the efficiency of tree fern as a sorbent for lead. The optimum pH for lead removal was between 4 and 7, with pH 4.9 resulting in better lead removal. Ion exchange occurred in the initial reaction period. In addition, a relation between the change in the solution hydrogen ion concentration and equilibrium capacity was developed and is presented.

Strategy for pH control and pH feedback-controlled substrate feeding for high-level production of L-tryptophan by Escherichia coli.

PubMed

Cheng, Li-Kun; Wang, Jian; Xu, Qing-Yang; Zhao, Chun-Guang; Shen, Zhi-Qiang; Xie, Xi-Xian; Chen, Ning

2013-05-01

Optimum production of L-tryptophan by Escherichia coli depends on pH. Here, we established conditions for optimizing the production of L-tryptophan. The optimum pH range was 6.5-7.2, and pH was controlled using a three-stage strategy [pH 6.5 (0-12 h), pH 6.8 (12-24 h), and pH 7.2 (24-38 h)]. Specifically, ammonium hydroxide was used to adjust pH during the initial 24 h, and potassium hydroxide and ammonium hydroxide (1:2, v/v) were used to adjust pH during 24-38 h. Under these conditions, NH4 (+) and K(+) concentrations were kept below the threshold for inhibiting L-tryptophan production. Optimization was also accomplished using ratios (v/v) of glucose to alkali solutions equal to 4:1 (5-24 h) and 6:1 (24-38 h). The concentration of glucose and the pH were controlled by adjusting the pH automatically. Applying a pH-feedback feeding method, the steady-state concentration of glucose was maintained at approximately 0.2 ± 0.02 g/l, and acetic acid accumulated to a concentration of 1.15 ± 0.03 g/l, and the plasmid stability was 98 ± 0.5 %. The final, optimized concentration of L-tryptophan was 43.65 ± 0.29 g/l from 52.43 ± 0.38 g/l dry cell weight.

The use of artificial neural network for modeling the decolourization of acid orange 7 solution of industrial by ozonation process

NASA Astrophysics Data System (ADS)

Fatimah, S.; Wiharto, W.

2017-02-01

Acid Orange 7 (AO7) is one of the synthetic dye in the dyeing process in the textile industry. The use of this dye can produce wastewater which will be endangered if not treated well. Ozonation method is one technique to solve this problem. Ozonation is a waste processing techniques using ozone as an oxidizing agent. Variables used in this research is the ozone concentration, the initial concentration of AO7, temperature, and pH. Based on the experimental result that the optimum value decolourization percentage is 80% when the ozone concentration is 560 mg/L, the initial concentration AO7 is 14 mg/L, the temperature is 390 °C, and pH is 7,6. Decolourization efficiency of experimental results and predictions successfully modelled by the neural network architecture. The data used to construct a neural network architecture quasi newton one step secant as many as 31 data. A comparison between the predicted results of the designed ANN models and experiment was conducted. From the modeling results obtained MAPE value of 0.7763%. From the results of this artificial neural network architecture obtained the optimum value decolourization percentage in 80,64% when the concentration of ozone is 550 mg/L, the initial concentration AO7 is 11 mg/L, the temperature is 41 °C, and the pH is 7.9.

Combination of novel coalescing oil water separator and electrocoagulation technique for treatment of petroleum compound contaminated groundwater.

PubMed

Oladzad, Sepideh; Fallah, Narges; Nasernejad, Bahram

2017-07-01

In the present study a combination of a novel coalescing oil water separator (COWS) and electrocoagulation (EC) technique was used for treatment of petroleum product contaminated groundwater. In the first phase, COWS was used as the primary treatment. Two different types of coalescing media and two levels of flow rates were examined in order to find the optimum conditions. The effluent of COWS was collected in optimum conditions and was treated using an EC process in the second phase of the research. In this phase, preliminary experiments were conducted in order to investigate the effect of EC reaction time and sedimentation time on chemical oxygen demand (COD) removal efficiency. Best conditions for EC reaction time and sedimentation time were obtained to be 5 min and 30 min, respectively. Response surface methodology was applied to evaluate the effect of initial pH, current density and aeration rate on settling velocity (V s ) and effluent COD. The optimum conditions, for achieving maximum values of V s as well as the values of effluent COD, in the range of results were obtained at conditions of 7, 34 mA·cm -2 and 1.5 L·min -1 for initial pH, current density and aeration rate, respectively.

Factors affecting yield and safety of protein production from cassava by Cephalosporium eichhorniae

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mikami, Y.; Gregory, K.F.; Levadoux, W.L.

1982-01-01

The properties of C. eichhorniae 152 (ATCC 38255) affecting protein production from cassava carbohydrate, for use as an animal feed, were studied. This strain is a true thermophile, showing optimum growth at 45-47 degrees, maximum protein yield at 45 degrees, and no growth at 25 degrees. It has an optimum pH of approximately 3.8 and is obligately acidophilic, being unable to sustain growth at pH of more than or equal to 6.0 in a liquid medium, or pH of more than or equal to 7.0 on solid media. The optimum growth conditions of pH 3.8 and 45 degrees were stronglymore » inhibitive to potential contaminants. It rapidly hydrolyzed cassava starch. It did not utilize sucrose, but approximately 16% of the small sucrose component of cassava was chemically hydrolyzed during the process. Growth with cassava meal (50 g/l) was complete in approximately 20 h, yielding 22.5 g/l (dry biomass), containing 41% crude protein (48-50% crude protein in the mycelium) and 31% true protein (7.0 g/l). Resting and germinating spores (10 to the power of 6 - 10 to the power of 8 per animal) injected by various routes into normal and gamma-irradiated 6-week-old mice and 7-day-old chickens failed to initiate infections.« less

Improvement of sludge dewaterability and removal of sludge-borne metals by bioleaching at optimum pH.

PubMed

Liu, Fenwu; Zhou, Lixiang; Zhou, Jun; Song, Xingwei; Wang, Dianzhan

2012-06-30

Bio-acidification caused by bio-oxidation of energy substances during bioleaching is widely known to play an important role in improving sludge-borne metals removal. Here we report that bioleaching also drastically enhances sludge dewaterability in a suitable pH level. To obtain the optimum initial concentrations of energy substances and pH values for sludge dewaterability during bioleaching, bio-oxidation of Fe(2+) and S(0) under co-inoculation with Acidithiobacillus thiooxidans TS6 and Acidothiobacillus ferrooxidans LX5 and their effects on sludge dewaterability and metals removal during sludge bioleaching were investigated. Results indicated that the dosage of energy substances with 2g/L S(0) and 2g/L Fe(2+) could obtain bio-oxidation efficiencies of up to 100% for Fe(2+) and 50% for S(0) and were the optimal dosages for sludge bioleaching. The removal efficiencies of sludge-borne Cu and Cr could reach above 85% and 40%, respectively, and capillary suction time (CST) of bioleached sludge decreased to as low as ∼10s from initial 48.9s for fresh sludge when sludge pH declined to ∼2.4 through bioleaching. These results confirm the potential of bioleaching as a novel method for improving sludge dewaterability as well as removal of metals. Copyright © 2012 Elsevier B.V. All rights reserved.

TiO₂ beads and TiO₂-chitosan beads for urease immobilization.

PubMed

Ispirli Doğaç, Yasemin; Deveci, Ilyas; Teke, Mustafa; Mercimek, Bedrettin

2014-09-01

The aim of the present study is to synthesize TiO2 beads for urease immobilization. Two different strategies were used to immobilize the urease on TiO2 beads. In the first method (A), urease enzyme was immobilized onto TiO2 beads by adsorption and then crosslinking. In the second method (B), TiO2 beads were coated with chitosan-urease mixture. To determine optimum conditions of immobilization, different parameters were investigated. The parameters of optimization were initial enzyme concentration (0.5; 1; 1.5; 2mg/ml), alginate concentration (1; 2; 3%), glutaraldehyde concentration (1; 2; 3% v/v) and chitosan concentration (2; 3; 4 mg/ml). The optimum enzyme concentrations were determined as 1.5mg/ml for A and 1.0mg/ml for B. The other optimum conditions were found 2.0% (w/v) for alginate concentration (both A and B); 3.0mg/ml for chitosan concentration (B) and 2.0% (v/v) for glutaraldehyde concentration (A). The optimum temperature (20-60°C), optimum pH (3.0-10.0), kinetic parameters, thermal stability (4-70°C), pH stability (4.0-9.0), operational stability (0-230 min) and reusability (20 times) were investigated for characterization. The optimum temperatures were 30°C (A), 40°C (B) and 35°C (soluble). The temperature profiles of the immobilized ureases were spread over a large area. The optimum pH values for the soluble urease and immobilized urease prepared by using methods (A) and (B) were found to be 7.5, 7.0, 7.0, respectively. The thermal stabilities of immobilized enzyme sets were studied and they maintained 50% activity at 65°C. However, at this temperature free urease protected only 15% activity. Copyright © 2014 Elsevier B.V. All rights reserved.

Variation in pH optima of hydrolytic enzyme activities in tropical rain forest soils.

PubMed

Turner, Benjamin L

2010-10-01

Extracellular enzymes synthesized by soil microbes play a central role in the biogeochemical cycling of nutrients in the environment. The pH optima of eight hydrolytic enzymes involved in the cycles of carbon, nitrogen, phosphorus, and sulfur, were assessed in a series of tropical forest soils of contrasting pH values from the Republic of Panama. Assays were conducted using 4-methylumbelliferone-linked fluorogenic substrates in modified universal buffer. Optimum pH values differed markedly among enzymes and soils. Enzymes were grouped into three classes based on their pH optima: (i) enzymes with acidic pH optima that were consistent among soils (cellobiohydrolase, β-xylanase, and arylsulfatase), (ii) enzymes with acidic pH optima that varied systematically with soil pH, with the most acidic pH optima in the most acidic soils (α-glucosidase, β-glucosidase, and N-acetyl-β-glucosaminidase), and (iii) enzymes with an optimum pH in either the acid range or the alkaline range depending on soil pH (phosphomonoesterase and phosphodiesterase). The optimum pH values of phosphomonoesterase were consistent among soils, being 4 to 5 for acid phosphomonoesterase and 10 to 11 for alkaline phosphomonoesterase. In contrast, the optimum pH for phosphodiesterase activity varied systematically with soil pH, with the most acidic pH optima (3.0) in the most acidic soils and the most alkaline pH optima (pH 10) in near-neutral soils. Arylsulfatase activity had a very acidic optimum pH in all soils (pH ≤3.0) irrespective of soil pH. The differences in pH optima may be linked to the origins of the enzymes and/or the degree of stabilization on solid surfaces. The results have important implications for the interpretation of hydrolytic enzyme assays using fluorogenic substrates.

Adsorption of malachite green dye from aqueous solution on the bamboo leaf ash

NASA Astrophysics Data System (ADS)

Kuntari, Priwidyanjati, Dessyntha Anggiani

2017-12-01

Bamboo leaf ash has been developed as an adsorbent material for removal malachite green from aqueous solution. Adsorption parameters have studied are contact time and initial pH. The effect of contact time and pH were examined in the batch adsorption processes. The physicochemical characters of bamboo leaf ash were investigated by using X-Ray Diffraction (XRD) and FT-IR spectroscopy. Malachite green concentration was determined by UV-Vis spectrophotometer. FT-IR spectrogram of bamboo leaf ash shows that typical fingerprint of adsorbent material with Si-O-Si or Al-O-Al group. The X-ray diffractograms of bamboo leaf ash show that adsorbent material has a highly amorphous nature. The percentage of adsorption was showed raised with increasing contact time. The optimum removal of malachite green when the initial dye concentration, initial pH, weight of adsorbent and contact time was 20 mg/L, 7, 0.25 g and 75 minutes respectively.

Fuel alcohol biosynthesis by Zymomonas anaerobia: optimization studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kosaric, N.; Ong, S.L.; Duvnjak, Z.

1982-03-01

The optimum operating conditions for growth and ethanol production of Zymomonas anaerobia ATCC 29501 were established. The optimum pH range and temperature were found to be 5.0-6.0 and 35 degrees C, respectively. Based on the results obtained from the temperature optimization study, an Arrhenius-type temperature relationship for the specific growth rate was developed. The growth and ethanol production of this microbe also have been optimized in terms of concentrations of glucose, essential nutrients, and minerals. With optimum medium and operating conditions, an ethanol concentration of 96 g/L was obtained in 23 hours. Both growth and ethanol yield coefficients in dependencemore » on initial glucose concentrations were determined. (Refs. 16).« less

Experimental design data for the biosynthesis of citric acid using Central Composite Design method.

PubMed

Kola, Anand Kishore; Mekala, Mallaiah; Goli, Venkat Reddy

2017-06-01

In the present investigation, we report that statistical design and optimization of significant variables for the microbial production of citric acid from sucrose in presence of filamentous fungi A. niger NCIM 705. Various combinations of experiments were designed with Central Composite Design (CCD) of Response Surface Methodology (RSM) for the production of citric acid as a function of six variables. The variables are; initial sucrose concentration, initial pH of medium, fermentation temperature, incubation time, stirrer rotational speed, and oxygen flow rate. From experimental data, a statistical model for this process has been developed. The optimum conditions reported in the present article are initial concentration of sucrose of 163.6 g/L, initial pH of medium 5.26, stirrer rotational speed of 247.78 rpm, incubation time of 8.18 days, fermentation temperature of 30.06 °C and flow rate of oxygen of 1.35 lpm. Under optimum conditions the predicted maximum citric acid is 86.42 g/L. The experimental validation carried out under the optimal values and reported citric acid to be 82.0 g/L. The model is able to represent the experimental data and the agreement between the model and experimental data is good.

Favouring butyrate production for a new generation biofuel by acidogenic glucose fermentation using cells immobilised on γ-alumina.

PubMed

Syngiridis, Kostas; Bekatorou, Argyro; Kandylis, Panagiotis; Larroche, Christian; Kanellaki, Maria; Koutinas, Athanasios A

2014-06-01

The effect of γ-alumina as a fermentation advancing tool and as carrier for culture immobilisation, regarding VFAs and ethanol production during acidogenic fermentation of glucose, was examined at various process conditions (sugar concentration, pH) and operation modes (continuous with and without effluent recirculation and batch). The results showed that at high initial pH (8.9) the continuous acidogenic fermentation of glucose led to high yields of VFAs and favoured the accumulation of butyric acid. The batch process on the other hand at pH 6.5, favoured the ethanol-type fermentation. The results indicate that in the frame of technology development for new generation biofuels, using γ-alumina as a process advancing tool at optimum process conditions (pH, initial glucose concentration and mode of operation), the produced VFAs profile and ethanol concentration may be manipulated. Copyright © 2014. Published by Elsevier Ltd.

[Extraction and purification technologies of total flavonoids from Aconitum tanguticum].

PubMed

Li, Yan-Rong; Yan, Li-Xin; Feng, Wei-Hong; Li, Chun; Wang, Zhi-Min

2014-04-01

To optimize the extraction and purification technologies of total flavonoids from Aconitum tanguticum whole plant. With the content of total flavonoids as index, the optimum extraction conditions for the concentration, volume of alcohol, extracting time and times were selected by orthogonal optimized; Comparing the adsorption quantity (mg/g) and resolution (%), four kinds of macroporous adsorption resins including D101, AB-8, X-5 and XAD-16 were investigated for the enrichment ability of total flavonoids from Aconitum tanguticum; Concentration and pH value of sample, sampling amount, elution solvent and loading and elution velocity for the optimum adsorption resin were determined. The content of total flavonoids in Aconitum tanguticum was about 4.39%; The optimum extraction technique was 70% alcohol reflux extraction for three times,each time for one hour, the ratio of material and liquid was 1:10 (w/v); The optimum purification technology was: using XAD-16 macroporous resin, the initial concentration of total flavonoids of Aconitum tanguticum was 8 mg/mL, the sampling amount was 112 mg/g dry resin, the pH value was 5, the loading velocity was 3 mL/min, the elution solvent was 70% ethanol and the elution velocity was 5 mL/min. Under the optimum conditions, the average content of total flavonoids was raised from 4.39% to 46.19%. The optimum extraction and purification technologies for total flavonoids of Aconitum tanguticum were suitable for industrial production for its simplicity and responsibility.

Purification and properties of adenosine kinase from rat brain.

PubMed

Yamada, Y; Goto, H; Ogasawara, N

1980-12-04

Adenosine kinase (ATP:adenosine 5'-phosphotransferase, EC 2.7.1.20) has been purified to apparent homogeneity from rat brain by (NH4)2SO4 fractionation, affinity chromatography on AMP-Sepharose 4B, gel filtration with Sephadex G-100, and DE-52 cellulose column chromatography. The yield was 56% of the initial activity with a final specific activity of 7.8 mumol/min per mg protein. The molecular weight was estimated as 38 000 by gel filtration with Sephadex G-100 and 41 000 by acrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS). The enzyme catalyzed the phosphorylation of adenosine, deoxyadenosine, arabinoadenosine, inosine and ribavirin. The activity of deoxyadenosine phosphorylation was 20% that of adenosine phosphorylation. The pH optimum profile was biphasic; a sharp pH optimum at pH 5.5 and a broad pH optimum at pH 7.5-8.5. The Km value for adenosine was 0.2 microM and the maximum activity was observed at 0.5 microM. At higher concentrations of adenosine, the activity was strongly inhibited. The Km value for ATP was 0.02 mM and that for Mg2+ was 0.1 mM. GTP, dGTP, dATP and UTP were also proved to be effective phosphate donors. Co2+ was as effective as Mg2+, and Ca2+, Mn2+ or Ni2+ showed about 50% of the activity for Mg2+. The kinase is quite unstable, but stable in the presence of a high concentration of salt; e.g., 0.15 M KCl.

Fungi immobilization for landfill leachate treatment.

PubMed

Saetang, Jenjira; Babel, Sandhya

2010-01-01

This paper investigated treatment of landfill leachate collected from Nonthaburi landfill site, Thailand, by using immobilized white rot fungi, namely, Trametes versicolor BCC 8725 and Flavodon flavus BCC 17421. Effects of pH and co-substrates were investigated at different contact times. Three types of co-substrates as carbon source used in this study are glucose, corn starch and cassava. Treatment efficiency was evaluated based on color, BOD, and COD removal. Initial BOD and COD were found to be 5,600 and 34,560 mg/L, respectively. The optimum pH was found to be 4, the optimum co-substrate concentration (glucose, corn starch and cassava) was 3 g/L and the optimum contact time was 10 days for both types of fungi. Addition of glucose, corn starch and cassava as co-substrate at optimum conditions could remove 78, 74, and 66% of color, respectively for T. versicolor and 73, 68, and 60%, respectively, for F. flavus. Moreover, for T. versicolor, BOD and COD reduction of 69 and 57%, respectively, could be achieved at optimum conditions when using glucose as a co-substrate. For F. flavus, BOD and COD reduction of 66 and 52%, respectively were obtained when using glucose as a co-substrate. White rot fungi can be considered potentially useful in the treatment of landfill leachate as they can help in removing color, BOD and COD due to their biodegradative abilities.

Enhanced degradation of paracetamol by UV-C supported photo-Fenton process over Fenton oxidation.

PubMed

Manu, B; Mahamood, S

2011-01-01

For the treatment of paracetamol in water, the UV-C Fenton oxidation process and classic Fenton oxidation have been found to be the most effective. Paracetamol reduction and chemical oxygen demand (COD) removal are measured as the objective functions to be maximized. The experimental conditions of the degradation of paracetamol are optimized by the Fenton process. Influent pH 3, initial H(2)O(2) dosage 60 mg/L, [H(2)O(2)]/[Fe(2+)] ratio 60 : 1 are the optimum conditions observed for 20 mg/L initial paracetamol concentration. At the optimum conditions, for 20 mg/L of initial paracetamol concentration, 82% paracetamol reduction and 68% COD removal by Fenton oxidation, and 91% paracetamol reduction and 82% COD removal by UV-C Fenton process are observed in a 120 min reaction time. By HPLC analysis, 100% removal of paracetamol is observed at the above optimum conditions for the Fenton process in 240 min and for the UV-C photo-Fenton process in 120 min. The methods are effective and they may be used in the paracetamol industry.

Electrocoagulation treatment of raw landfill leachate using iron-based electrodes: Effects of process parameters and optimization.

PubMed

Huda, N; Raman, A A A; Bello, M M; Ramesh, S

2017-12-15

The main problem of landfill leachate is its diverse composition comprising many persistent organic pollutants which must be removed before being discharge into the environment. This study investigated the treatment of raw landfill leachate using electrocoagulation process. An electrocoagulation system was designed with iron as both the anode and cathode. The effects of inter-electrode distance, initial pH and electrolyte concentration on colour and COD removals were investigated. All these factors were found to have significant effects on the colour removal. On the other hand, electrolyte concentration was the most significant parameter affecting the COD removal. Numerical optimization was also conducted to obtain the optimum process performance. Under optimum conditions (initial pH: 7.73, inter-electrode distance: 1.16 cm, and electrolyte concentration (NaCl): 2.00 g/L), the process could remove up to 82.7% colour and 45.1% COD. The process can be applied as a pre-treatment for raw leachates before applying other appropriate treatment technologies. Copyright © 2017 Elsevier Ltd. All rights reserved.

Characterization of an Invertase with pH Tolerance and Truncation of Its N-Terminal to Shift Optimum Activity toward Neutral pH

PubMed Central

Wang, Zilong; Lu, Jian; Wei, Yutuo; Huang, Ribo

2013-01-01

Most invertases identified to date have optimal activity at acidic pH, and are intolerant to neutral or alkaline environments. Here, an acid invertase named uninv2 is described. Uninv2 contained 586 amino acids, with a 100 amino acids N-terminal domain, a catalytic domain and a C-terminal domain. With sucrose as the substrate, uninv2 activity was optimal at pH 4.5 and at 45°C. Removal of N-terminal domain of uninv2 has shifted the optimum pH to 6.0 while retaining its optimum temperaure at 45°C. Both uninv2 and the truncated enzyme retained highly stable at neutral pH at 37°C, and they were stable at their optimum pH at 4°C for as long as 30 days. These characteristics make them far superior to invertase from Saccharomyces cerevisiae, which is mostly used as industrial enzyme. PMID:23638032

Characterization of an invertase with pH tolerance and truncation of its N-terminal to shift optimum activity toward neutral pH.

PubMed

Du, Liqin; Pang, Hao; Wang, Zilong; Lu, Jian; Wei, Yutuo; Huang, Ribo

2013-01-01

Most invertases identified to date have optimal activity at acidic pH, and are intolerant to neutral or alkaline environments. Here, an acid invertase named uninv2 is described. Uninv2 contained 586 amino acids, with a 100 amino acids N-terminal domain, a catalytic domain and a C-terminal domain. With sucrose as the substrate, uninv2 activity was optimal at pH 4.5 and at 45°C. Removal of N-terminal domain of uninv2 has shifted the optimum pH to 6.0 while retaining its optimum temperaure at 45°C. Both uninv2 and the truncated enzyme retained highly stable at neutral pH at 37°C, and they were stable at their optimum pH at 4°C for as long as 30 days. These characteristics make them far superior to invertase from Saccharomyces cerevisiae, which is mostly used as industrial enzyme.

Biosorption of toxic lead (II) ions using tomato waste (Solanum lycopersicum) activated by NaOH

NASA Astrophysics Data System (ADS)

Permatasari, Diah; Heraldy, Eddy; Lestari, Witri Wahyu

2016-02-01

This research present to uptake lead (II) ion from aqueous solutions by activated tomato waste. Biosorbent were characterized by applying Fourier Transform Infrared Spectroscopy (FTIR) and Surface Area Analyzer (SAA). The biosorption investigated with parameters including the concentration of NaOH, effects of solution pH, biosorbent dosage, contact time,and initial metal concentration. Experimental data were analyzed in terms of two kinetic model such us the pseudo-first order and pseudo-second order. Langmuir and Freundlich isotherm models were applied todescribe the biosorption process. According to the experiment, the optimum concentration of NaOH was achieved at 0.1 M. The maximum % lead (II) removal was achieved at pH 4 with 94.5%. Optimum biosorbentdosage were found as 0.1 g/25 mL solution while optimum contact time were found at 75 minutes. The results showed that the biosorption processes of Lead (II) followed pseudo-second order kinetics. Langmuir adsorption isotherm was found fit the adsorption data with amaximum capacity of 24.079 mg/g with anadsorption energy of 28.046 kJ/mol.

Factors affecting UV/H2O2 inactivation of Bacillus atrophaeus spores in drinking water.

PubMed

Zhang, Yongji; Zhang, Yiqing; Zhou, Lingling; Tan, Chaoqun

2014-05-05

This study aims at estimating the performance of the Bacillus atrophaeus spores inactivation by the UV treatment with addition of H2O2. The effect of factors affecting the inactivation was investigated, including initial H2O2 dose, UV irradiance, initial cell density, initial solution pH and various inorganic anions. Under the experimental conditions, the B. atrophaeus spores inactivation followed both the modified Hom Model and the Chick's Model. The results revealed that the H2O2 played dual roles in the reactions, while the optimum reduction of 5.88lg was received at 0.5mM H2O2 for 10min. The inactivation effect was affected by the UV irradiance, while better inactivation effect was achieved at higher irradiance. An increase in the initial cell density slowed down the inactivation process. A slight acid condition at pH 5 was considered as the optimal pH value. The inactivation effect within 10min followed the order of pH 5>pH 7>pH 9>pH 3>pH 11. The effects of three added inorganic anions were investigated and compared, including sulfate (SO4(2)(-)), nitrate (NO3(-)) and carbonate (CO3(2)(-)). The sequence of inactivation effect within 10min followed the order of control group>SO4(2)(-)>NO3(-)>CO3(2)(-). Copyright © 2014 Elsevier B.V. All rights reserved.

Statistical Optimization of 1,3-Propanediol (1,3-PD) Production from Crude Glycerol by Considering Four Objectives: 1,3-PD Concentration, Yield, Selectivity, and Productivity.

PubMed

Supaporn, Pansuwan; Yeom, Sung Ho

2018-04-30

This study investigated the biological conversion of crude glycerol generated from a commercial biodiesel production plant as a by-product to 1,3-propanediol (1,3-PD). Statistical analysis was employed to derive a statistical model for the individual and interactive effects of glycerol, (NH 4 ) 2 SO 4 , trace elements, pH, and cultivation time on the four objectives: 1,3-PD concentration, yield, selectivity, and productivity. Optimum conditions for each objective with its maximum value were predicted by statistical optimization, and experiments under the optimum conditions verified the predictions. In addition, by systematic analysis of the values of four objectives, optimum conditions for 1,3-PD concentration (49.8 g/L initial glycerol, 4.0 g/L of (NH 4 ) 2 SO 4 , 2.0 mL/L of trace element, pH 7.5, and 11.2 h of cultivation time) were determined to be the global optimum culture conditions for 1,3-PD production. Under these conditions, we could achieve high 1,3-PD yield (47.4%), 1,3-PD selectivity (88.8%), and 1,3-PD productivity (2.1/g/L/h) as well as high 1,3-PD concentration (23.6 g/L).

[Establishment of optimal conditions at laboratory and pilot plant levels for the preparation of a protein isolated from Lupinus mutabilis].

PubMed

Rodríguez Pacheco, T; Aliaga, T; Schoeneberger, H; Gross, R

1981-12-01

Laboratory conditions were first investigated to determine are optimum processing parameters for the preparation of a protein isolate from the ground, defatted, commercial flakes of Lupinus mutabilis. The extraction variables were: pH (2-10); solvent to lupine ratio (5:1 to 40:1); temperature (28 degrees C - 60 degrees C) and time (10-50 min). The isoelectric point of the lupine protein was found to be pH 4.5 with a protein solubility higher than 80% above pH 8.0. Using 70-100 mesh, ground defatted flakes, and extracting at pH 8.7 for 60 min, a protein isolate was obtained on acidification to pH 4.5 which was 99.8 protein (dry basis), compared to 55.25% protein for the original material. This protein isolate represented 32% of the initial material and 57.6% of the initial nitrogen. When making pilot plant assays we found that the yield of protein isolate decreased to 20.4% of the original material and 36.4% of the initial nitrogen. The protein efficiency ratio for the protein isolate was 2.15 when supplemented with methionine, and had a digestibility of 89.33

Screening and Characterization of Polygalacturonase as Potential Enzyme for Keprok Garut Orange (Citrus nobilis var. chrysocarpa) Juice Clarification

NASA Astrophysics Data System (ADS)

Widowati, E.; Utami, R.; Kalistyatika, K.

2017-11-01

Use of thermostable enzyme from bacilli for industrial application is significant. This research aimed to isolate thermophilic pectinolytic bacteria from orange peel and vegetable waste which produced thermostable polygalacturonase, to investigate the polygalacturonase ability in clarifying keprok Garut orange juice, and to characterize polygalacturonase based on pH optimum, temperature optimum, enzyme stability, enzyme kinetics KM, and Vmax. Obtained, 14 isolates that further selected to 4 best isolates based on highest polygalacturonase activity and keprok Garut orange juice clarification ability. Four selected enzyme isolates were AR 2, AR 4, KK 4, and KK 5 had ability to increase juice transmittance, decrease juice viscosity and also reduce total soluble solid. Furthermore 4 selected isolates were partially purified by ammonium sulphate precipitation and dialysis method. Four partially purified enzymes were known that enzyme character of AR 2 optimum at pH 6; AR 4 optimum at pH 5.5; KK 4 optimum at pH 6; and KK 5 optimum at pH 4.5. Four enzymes were optimum at temperature 60°C thus stable at temperature 50-60°C, this characteristic indicate that enzymes were thermostable. AR 2 showed active activity stable at pH 4-7; AR 4 showed active activity stable at pH 6-7; KK 4 showed active activity stable at pH 4-6; however KK 5 stable at pH 4-5. Enzyme AR 2 and KK 4 was getting inactive at pH 11, thus AR 4 and KK 5 inactive at pH 12. KM value of AR 2, AR 4, KK 4, and KK 5 was 0.0959; 0.0974; 0.0966; and 0.178 mg/ml respectively. Vmax of AR 2, AR 4, KK 4, and KK 5 was 0.0203; 0.0202; 0.0185; and 0.0229 U/ml respectively. Enzyme AR 2 was the most compatible enzyme to be applied in keprok Garut orange juice clarification for it had the lowest KM value.

Removal of Cu(II) from acidic electroplating effluent by biochars generated from crop straws.

PubMed

Tong, Xuejiao; Xu, Renkou

2013-04-01

The removal efficiency of copper (Cu(II)) from an actual acidic electroplating effluent by biochars generated from canola, rice, soybean and peanut straws was investigated. The biochars simultaneously removed Cu(II) from the effluent, mainly through the mechanisms of adsorption and precipitation, and neutralized its acidity. The removal efficiency of Cu(II) by the biochars followed the order: peanut straw char > soybean straw char > canola straw char > rice straw char > a commercial activated carbonaceous material, which is consistent with the alkalinity of the biochars. The pH of the effluent was a key factor determining the removal efficiency of Cu(II) by biochars. Raising the initial pH of the effluent enhanced the removal of Cu(II) from it. The optimum pyrolysis temperature was 400 degrees C for producing biochar from crop straws for acidic wastewater treatment, and the optimum reaction time was 8 hr.

Thermostable saccharogenic amylase produced under submerged fermentation by filamentous fungus Penicillium purpurogenum.

PubMed

Silva, Tony Márcio; de Oliveira, Maurício; Somera, Alexandre Favarin; Jorge, João Atílio; Terenzi, Héctor Francico; de Lourdes T M Polizeli, Maria; Guimarães, Luis Henrique Souza

2011-07-01

The effect of several nutritional and environmental parameters on Penicillium purpurogenum growth and sacharogenic amylase production was analyzed. High enzyme levels (68.2 U mg(-1)) were obtained with Khanna medium at initial pH 6.0, incubated at 30°C for 144 hours. The optimum pH and temperature activities were 5.0 and 65°C, respectively. The enzyme presented a half-life (t50) of 60 min, at 65°C. Only glucose was detected after 24 hours of reaction using soluble starch as substrate.

Enhanced bioelectricity generation of air-cathode buffer-free microbial fuel cells through short-term anolyte pH adjustment.

PubMed

Ren, Yueping; Chen, Jinli; Li, Xiufen; Yang, Na; Wang, Xinhua

2018-04-01

Short-term initial anolyte pH adjustment can relieve the performance deterioration of the single-chamber air-cathode buffer-free microbial fuel cell (BFMFC) caused by anolyte acidification. Adjusting the initial anolyte pH to 9 in 5 running cycles is the optimum strategy. The relative abundance of the electrochemically active Geobacter in the KCl-pH9-MFC anode biofilm increased from 59.01% to 75.13% after the short-term adjustment. The maximum power density (P max ) of the KCl-pH9-MFC was elevated from 316.4mW·m -2 to 511.6mW·m -2 , which was comparable with that of the PBS-MFC. And, after the short-term adjusting, new equilibrium between the anolyte pH and the anode biofilm electrochemical activity has been established in the BFMFC, which ensured the sustainability of the improved bioelectricity generation performance. Copyright © 2017 Elsevier B.V. All rights reserved.

Removal of methyl orange and methylene blue dyes from aqueous solution using lala clam (Orbicularia orbiculata) shell

NASA Astrophysics Data System (ADS)

Eljiedi, Arwa Alseddig Ahmed; Kamari, Azlan

2017-05-01

Textile effluents are considered as potential sources of water pollution because they contain toxic dyes. In the present study, lala clam shell was used as an alternative low-cost adsorbent for the removal of two harmful dyes, namely methyl orange (MO) and methylene blue (MB) from aqueous solution. Batch adsorption studies were carried out by varying experimental parameters such as solution pH, initial concentration and adsorbent dosage. The optimum pH values for MO and MB removal were pH 2.0 and pH 8.0, respectively. At an initial MO and MB concentration of 20 mg/L, the maximum removal percentage of MO and MB were 18.9 % and 81.3 %, respectively. The adsorption equilibrium data were correlated with both Langmuir and Freundlich isotherm models. The biomass adsorbent was characterised using Field Emission Scanning Electron Microscope (FESEM) and Fourier Transform Infrared Spectrometer (FTIR). Results from this study suggest that lala clam shell, a fishery waste, can be beneficial for water treatment.

Boron removal by electrocoagulation and recovery.

PubMed

Isa, Mohamed Hasnain; Ezechi, Ezerie Henry; Ahmed, Zubair; Magram, Saleh Faraj; Kutty, Shamsul Rahman Mohamed

2014-03-15

This work investigated the removal of boron from wastewater and its recovery by electrocoagulation and hydrothermal mineralization methods respectively. The experimental design was developed using Box-Behnken Model. An initial study was performed based on four preselected variables (pH, current density, concentration and time) using synthetic wastewater. Response surface methodology (RSM) was used to evaluate the effect of process variables and their interaction on boron removal. The optimum conditions were obtained as pH 6.3, current density 17.4 mA/cm(2), and time 89 min. At these applied optimum conditions, 99.7% boron removal from an initial concentration of 10.4 mg/L was achieved. The process was effectively optimized by RSM with a desirability value of 1.0. The results showed that boron removal efficiency enhanced with increase in current density and treatment time. Removal efficiency also increased when pH was increased from 4 to 7 and subsequently decreased at pH 10. Adsorption kinetics study revealed that the reaction followed pseudo second order kinetic model; evidenced by high correlation and goodness of fit. Thermodynamics study showed that mechanism of boron adsorption was chemisorption and the reaction was endothermic in nature. Furthermore, the adsorption process was spontaneous as indicated by negative values of the adsorption free energy. Treatment of real produced water using electrocoagulation resulted in 98% boron removal. The hydrothermal mineralization study showed that borate minerals (Inyoite, Takadaite and Nifontovite) can be recovered as recyclable precipitate from electrocoagulation flocs of produced water. Copyright © 2013 Elsevier Ltd. All rights reserved.

Microwave-Hydrothermal Treated Grape Peel as an Efficient Biosorbent for Methylene Blue Removal

PubMed Central

Ma, Lin; Jiang, Chunhai; Lin, Zhenyu; Zou, Zhimin

2018-01-01

Biosorption using agricultural wastes has been proven as a low cost and efficient way for wastewater treatment. Herein, grape peel treated by microwave- and conventional-hydrothermal processes was used as low cost biosorbent to remove methylene blue (MB) from aqueous solutions. The adsorption parameters including the initial pH value, dosage of biosorbents, contact time, and initial MB concentration were investigated to find the optimum adsorption conditions. The biosorbent obtained by microwave-hydrothermal treatment only for 3 min at 180 °C (microwave-hydrothermal treated grape peel, MGP) showed faster kinetics and higher adsorption capability than that produced by a conventional-hydrothermal process (hydrothermal treated grape peel, HGP) with a duration time of 16 h. The maximum adsorption capability of MGP under the optimum conditions (pH = 11, a dosage of 2.50 g/L) as determined with the Langmuir model reached 215.7 mg/g, which was among the best values achieved so far on biosorbents. These results demonstrated that the grape peel treated by a quick microwave-hydrothermal process can be a very promising low cost and efficient biosorbent for organic dye removal from aqueous solutions. PMID:29385041

Amoxicillin degradation from contaminated water by solar photocatalysis using response surface methodology (RSM).

PubMed

Moosavi, Fatemeh Sadat; Tavakoli, Touraj

2016-11-01

In this study, the solar photocatalytic process in a pilot plant with compound parabolic collectors (CPCs) was performed for amoxicillin (AMX) degradation, an antibiotic widely used in the world. The response surface methodology (RSM) based on Box-Behnken statistical experiment design was used to optimize independent variables, namely TiO 2 dosage, antibiotic initial concentration, and initial pH. The results showed that AMX degradation efficiency affected by positive or negative effect of variables and their interactions. The TiO 2 dosage, pH, and interaction between AMX initial concentration and TiO 2 dosage exhibited a synergistic effect, while the linear and quadratic term of AMX initial concentration and pH showed antagonistic effect in the process response. Response surface and contour plots were used to perform process optimization. The optimum conditions found in this regard were TiO 2 dosage = 1.5 g/L, AMX initial concentration = 17 mg/L, and pH = 9.5 for AMX degradation under 240 min solar irradiation. The photocatalytic degradation of AMX after 34.95 kJ UV /L accumulated UV energy per liter of solution was 84.12 % at the solar plant.

Grafting of GMA and some comonomers onto chitosan for controlled release of diclofenac sodium.

PubMed

Sharma, Rajeev Kr; Lalita; Singh, Anirudh P; Chauhan, Ghanshyam S

2014-03-01

In order to develop pH sensitive hydrogels for controlled drug release we have graft copolymerized glycidyl methacrylate (GMA) with comonomers acrylic acid, acrylamide and acrylonitrile, onto chitosan (Ch) by using potassium persulphate (KPS) as free radical initiator in aqueous solution. The optimum percent grafting for GMA was recorded for 1g chitosan at [KPS]=25.00 × 10(-3)mol/L, [GMA]=0.756 × 10(-3)mol/L, reaction temperature=60 °C and reaction time=1h in 20 mL H2O. Binary monomers were grafted for five different concentrations at optimum grafting conditions evaluated for GMA alone onto chitosan. The graft copolymers were characterized by FTIR, XRD, TGA and SEM. The swelling properties of chitosan and graft copolymers were investigated at different pH to define their end uses in sustained release of an anti-inflammatory drug, diclofenac sodium. Percent drug release w.r.t. drug loaded in polymeric sample was studied as function of time in buffer solutions of pH 2.0 and 7.4. In vitro release data was analyzed using Fick's Law. Chitosan grafted with binary monomers, GMA-co-AAm and GMA-co-AN showed very good results for sustained release of drug at 7.4 pH. Copyright © 2014 Elsevier B.V. All rights reserved.

Fractal analysis of polyferric chloride-humic acid (PFC-HA) flocs in different topological spaces.

PubMed

Wang, Yili; Lu, Jia; Baiyu, Du; Shi, Baoyou; Wang, Dongsheng

2009-01-01

The fractal dimensions in different topological spaces of polyferric chloride-humic acid (PFC-HA) flocs, formed in flocculating different kinds of humic acids (HA) water at different initial pH (9.0, 7.0, 5.0) and PFC dosages, were calculated by effective density-maximum diameter, image analysis, and N2 absorption-desorption methods, respectively. The mass fractal dimensions (Df) of PFC-HA flocs were calculated by bi-logarithm relation of effective density with maximum diameter and Logan empirical equation. The Df value was more than 2.0 at initial pH of 7.0, which was 11% and 13% higher than those at pH 9.0 and 5.0, respectively, indicating the most compact flocs formed in flocculated HA water at initial pH of 7.0. The image analysis for those flocs indicates that after flocculating the HA water at initial pH greater than 7.0 with PFC flocculant, the fractal dimensions of D2 (logA vs. logdL) and D3 (logVsphere VS. logdL) of PFC-HA flocs decreased with the increase of PFC dosages, and PFC-HA flocs showed a gradually looser structure. At the optimum dosage of PFC, the D2 (logA vs. logdL) values of the flocs show 14%-43% difference with their corresponding Df, and they even had different tendency with the change of initial pH values. However, the D2 values of the flocs formed at three different initial pH in HA solution had a same tendency with the corresponding Dr. Based on fractal Frenkel-Halsey-Hill (FHH) adsorption and desorption equations, the pore surface fractal dimensions (Ds) for dried powders of PFC-HA flocs formed in HA water with initial pH 9.0 and 7.0 were all close to 2.9421, and the Ds values of flocs formed at initial pH 5.0 were less than 2.3746. It indicated that the pore surface fractal dimensions of PFC-HA flocs dried powder mainly show the irregularity from the mesopore-size distribution and marcopore-size distribution.

Mechanism-based site-directed mutagenesis to shift the optimum pH of the phenylalanine ammonia-lyase from Rhodotorula glutinis JN-1.

PubMed

Zhu, Longbao; Zhou, Li; Cui, Wenjing; Liu, Zhongmei; Zhou, Zhemin

2014-09-01

Phenylalanine ammonia-lyase ( Rg PAL) from Rhodotorula glutinis JN-1 stereoselectively catalyzes the conversion of the l-phenylalanine into trans -cinnamic acid and ammonia, and was used in chiral resolution of dl-phenylalanine to produce the d-phenylalanine under acidic condition. However, the optimum pH of Rg PAL is 9 and the Rg PAL exhibits low catalytic efficiency at acidic side. Therefore, a mutant Rg PAL with a lower optimum pH is expected. Based on catalytic mechanism and structure analysis, we constructed a mutant Rg PAL-Q137E by site-directed mutagenesis, and found that this mutant had an extended optimum pH 7-9 with activity of 1.8-fold higher than that of the wild type at pH 7. As revealed by Friedel-Crafts-type mechanism of Rg PAL, the improvement of the Rg PAL-Q137E might be due to the negative charge of Glu137 which could stabilize the intermediate transition states through electrostatic interaction. The Rg PAL-Q137E mutant was used to resolve the racemic dl-phenylalanine, and the conversion rate and the ee D value of d-phenylalanine using Rg PAL-Q137E at pH 7 were increased by 29% and 48%, and achieved 93% and 86%, respectively. This work provides an effective strategy to shift the optimum pH which is favorable to further applications of Rg PAL.

How gastric lipase, an interfacial enzyme with a Ser-His-Asp catalytic triad, acts optimally at acidic pH.

PubMed

Chahinian, Henri; Snabe, Torben; Attias, Coralie; Fojan, Peter; Petersen, Steffen B; Carrière, Frédéric

2006-01-24

Gastric lipase is active under acidic conditions and shows optimum activity on insoluble triglycerides at pH 4. The present results show that gastric lipase also acts in solution on vinyl butyrate, with an optimum activity above pH 7, which suggests that gastric lipase is able to hydrolyze ester bonds via the classical mechanism of serine hydrolases. These results support previous structural studies in which the catalytic triad of gastric lipase was reported to show no specific features. The optimum activity of gastric lipase shifted toward lower pH values, however, when the vinyl butyrate concentration was greater than the solubility limit. Experiments performed with long-chain triglycerides showed that gastric lipase binds optimally to the oil-water interface at low pH values. To study the effects of the pH on the adsorption step independently from substrate hydrolysis, gastric lipase adsorption on solid hydrophobic surfaces was monitored by total internal reflection fluorescence (TIRF), as well as using a quartz crystal microbalance. Both techniques showed a pH-dependent reversible gastric lipase adsorption process, which was optimum at pH 5 (Kd = 6.5 nM). Lipase adsorption and desorption constants (ka = 147,860 M(-1) s(-1) and kd = 139 x 10(-4) s(-1) at pH 6) were estimated from TIRF experiments. These results indicate that the optimum activity of gastric lipase at acidic pH is only "apparent" and results from the fact that lipase adsorption at lipid-water interfaces is the pH-dependent limiting step in the overall process of insoluble substrate hydrolysis. This specific kinetic feature of interfacial enzymology should be taken into account when studying any soluble enzyme acting on an insoluble substrate.

Effect of cultivating conditions on alpha-galactosidase production by a novel Aspergillus foetidus ZU-G1 strain in solid-state fermentation.

PubMed

Liu, Cai-qin; Chen, Qi-he; Cheng, Qian-jun; Wang, Jin-ling; He, Guo-qing

2007-05-01

The work is intended to achieve optimum culture conditions of alpha-galactosidase production by a mutant strain Aspergillus foetidus ZU-G1 in solid-state fermentation (SSF). Certain fermentation parameters involving moisture content, incubation temperature, cultivation period of seed, inoculum volume, initial pH value, layers of pledget, load size of medium and period of cultivation were investigated separately. The optimal cultivating conditions of alpha-galactosidase production in SSF were 60% initial moisture of medium, 28 degrees C incubation temperature, 18 h cultivation period of seed, 10% inoculum volume, 5.0 approximately 6.0 initial pH of medium, 6 layers of pledget and 10 g dry matter loadage. Under the optimized cultivation conditions, the maximum alpha-galactosidase production was 2 037.51 U/g dry matter near the 144th hour of fermentation.

Effect of cultivating conditions on α-galactosidase production by a novel Aspergillus foetidus ZU-G1 strain in solid-state fermentation

PubMed Central

Liu, Cai-qin; Chen, Qi-he; Cheng, Qian-jun; Wang, Jin-ling; He, Guo-qing

2007-01-01

The work is intended to achieve optimum culture conditions of α-galactosidase production by a mutant strain Aspergillus foetidus ZU-G1 in solid-state fermentation (SSF). Certain fermentation parameters involving moisture content, incubation temperature, cultivation period of seed, inoculum volume, initial pH value, layers of pledget, load size of medium and period of cultivation were investigated separately. The optimal cultivating conditions of α-galactosidase production in SSF were 60% initial moisture of medium, 28 °C incubation temperature, 18 h cultivation period of seed, 10% inoculum volume, 5.0~6.0 initial pH of medium, 6 layers of pledget and 10 g dry matter loadage. Under the optimized cultivation conditions, the maximum α-galactosidase production was 2 037.51 U/g dry matter near the 144th hour of fermentation. PMID:17542067

Influence of Polyvinyl Alcohol (PVA) Addition on Silica Membrane Performance Prepared from Rice Straw

NASA Astrophysics Data System (ADS)

Wahyuningsih, S.; Ramelan, A. H.; Wardoyo, D. T.; Ichsan, S.; Kristiawan, Y. R.

2018-03-01

The utilization and modification of silica from rice straw as the main ingredient of adsorbent has been studied. The aim of this study was to determine the optimum composition of PVA (polyvinyl alcohol): silica to produce adsorbents with excellent pore characteristics, optimum adsorption efficiency and optimum pH for methyl yellow adsorptions. X-Ray Fluorescence (XRF) analysis results showed that straw ash contains 82.12 % of silica (SiO2). SAA (Surface Area Analyzer) analysis showed optimum composition ratio 5:5 of PVA: silica with surface area of 1.503 m2/g. Besides, based on the pore size distribution of PVA: silica (5:5) showed the narrow pore size distribution with the largest pore cumulative volume of 2.8 x 10-3 cc/g. The optimum pH for Methanyl Yellow adsorption is pH 2 with adsorption capacity = 72.1346%.

Optimization of covalent immobilization of pectinase on sodium alginate support.

PubMed

Li, Tuoping; Wang, Na; Li, Suhong; Zhao, Qiancheng; Guo, Mei; Zhang, Cheyun

2007-09-01

Pectinase was immobilized on a sodium alginate support using glutaraldehyde and retained 66% activity. The optimal pH for activity shifted from 3.0 to 3.5 after immobilization; however, the optimum temperature remained unchanged at 40 degrees C. The immobilized enzyme also had a higher thermal stability and reusability than the free enzyme, and retained 80% of initial activity after 11 batch reactions.

Porous silicon powder as an adsorbent of heavy metal (nickel)

NASA Astrophysics Data System (ADS)

Nabil, Marwa; Motaweh, Hussien A.

2018-04-01

New and inexpensive nanoporous silicon (NPS) powder was prepared by alkali chemical etching using sonication technique and was subsequently investigated as an adsorbent in batch systems for the adsorption Ni(II) ions in an aqueous solution. The optimum conditions for the Ni(II) ion adsorption capacity of the NPS powder were studied in detail by varying parameters such as the initial Ni(II) concentration, the solution pH value, the adsorption temperature and contact time. The results indicated that the maximum adsorption capacity and the maximum removal percent of Ni(II) reached 2665.33 mg/g and 82.6%, respectively, at an initial Ni(II) concentration of 100 mg/L, adsorption time of 30 min and no effect of the solution pH and adsorption temperature.

Response surface methodological approach for the decolorization of simulated dye effluent using Aspergillus fumigatus fresenius.

PubMed

Sharma, Praveen; Singh, Lakhvinder; Dilbaghi, Neeraj

2009-01-30

The aim of our research was to study, effect of temperature, pH and initial dye concentration on decolorization of diazo dye Acid Red 151 (AR 151) from simulated dye solution using a fungal isolate Aspergillus fumigatus fresenius have been investigated. The central composite design matrix and response surface methodology (RSM) have been applied to design the experiments to evaluate the interactive effects of three most important operating variables: temperature (25-35 degrees C), pH (4.0-7.0), and initial dye concentration (100-200 mg/L) on the biodegradation of AR 151. The total 20 experiments were conducted in the present study towards the construction of a quadratic model. Very high regression coefficient between the variables and the response (R(2)=0.9934) indicated excellent evaluation of experimental data by second-order polynomial regression model. The RSM indicated that initial dye concentration of 150 mg/L, pH 5.5 and a temperature of 30 degrees C were optimal for maximum % decolorization of AR 151 in simulated dye solution, and 84.8% decolorization of AR 151 was observed at optimum growth conditions.

The decolorization and mineralization of acid orange 6 azo dye in aqueous solution by advanced oxidation processes: a comparative study.

PubMed

Hsing, Hao-Jan; Chiang, Pen-Chi; Chang, E-E; Chen, Mei-Yin

2007-03-06

The comparison of different advanced oxidation processes (AOPs), i.e. ultraviolet (UV)/TiO(2), O(3), O(3)/UV, O(3)/UV/TiO(2), Fenton and electrocoagulation (EC), is of interest to determine the best removal performance for the destruction of the target compound in an Acid Orange 6 (AO6) solution, exploring the most efficient experimental conditions as well; on the other hand, the results may provide baseline information of the combination of different AOPs in treating industrial wastewater. The following conclusions can be drawn: (1) in the effects of individual and combined ozonation and photocatalytic UV irradiation, both O(3)/UV and O(3)/UV/TiO(2) processes exhibit remarkable TOC removal capability that can achieve a 65% removal efficiency at pH 7 and O(3) dose=45mg/L; (2) the optimum pH and ratio of [H(2)O(2)]/[Fe(2+)] found for the Fenton process, are pH 4 and [H(2)O(2)]/[Fe(2+)]=6.58. The optimum [H(2)O(2)] and [Fe(2+)] under the same HF value are 58.82 and 8.93mM, respectively; (3) the optimum applied voltage found in the EC experiment is 80V, and the initial pH will affect the AO6 and TOC removal rates in that acidic conditions may be favorable for a higher removal rate; (4) the AO6 decolorization rate ranking was obtained in the order of O(3)

Cellulase and cell differentiation in Acer pseudoplatanus.

PubMed

Sheldrake, A R

1970-06-01

Homogenates of differentiating xylem and phloem tissue have higher cellulase activities than cambial samples; the highest activity is always found in phloem. Callus tissue, in which no vascular differentiation occurs, contains only low cellulase activity. The results suggest that cellulase is involved in vascular differentiation. Different pH optima of cellulase activity were found: in cambium, xylem and phloem tissue, cellulase activity with an optimum at about pH 5.9 is predominantly membrane-bound; it is sedimentable at 100,000 g and releasable by Triton X-100. The same may be true of activity with an optimum at pH 5.3. Phloem tissue also contains a soluble, cytoplasmic cellulase of high activity at pH 7.1, and xylem tissue contains cytoplasmic cellulase with an optimum at pH 6.5. Low cellulase activity with a pH optimum similar to that of xylem homogenates was found in xylem sap. Cellulase activity in abscission zones increases greatly just before leaf abscission. Abscission zone cellulase has two pH optima, et 5.3 and 5.9; both activities are increased by Triton treatment of homogenates. The possible existence of several different cellulases forming part of a cellulase complex, and the rôle of the enzymes in hydrolysing wall material during cell differentiation are discussed.

Adsorptive removal of Auramine-O: kinetic and equilibrium study.

PubMed

Mall, Indra Deo; Srivastava, Vimal Chandra; Agarwal, Nitin Kumar

2007-05-08

Present study deals with the adsorption of Auramine-O (AO) dye by bagasse fly ash (BFA) and activated carbon-commercial grade (ACC) and laboratory grade (ACL). BFA is a solid waste obtained from the particulate collection equipment attached to the flue gas line of the bagasse fired boilers of cane sugar mills. Batch studies were performed to evaluate the influences of various experimental parameters like initial pH (pH(0)), contact time, adsorbent dose and initial concentration (C(0)) for the removal of AO. Optimum conditions for AO removal were found to be pH(0) approximately 7.0 and equilibrium time approximately 30 min for BFA and approximately 120 min for activated carbons. Optimum BFA, ACC and ACL dosages were found to be 1, 20 and 2g/l, respectively. Adsorption of AO followed pseudo-second order kinetics with the initial sorption rate for adsorption on BFA being the highest followed by those on ACL and ACC. The sorption process was found to be controlled by both film and pore diffusion with film diffusion at the earlier stages followed by pore diffusion at the later stages. Equilibrium isotherms for the adsorption of AO on BFA, ACC and ACL were analyzed by Freundlich, Langmuir, Dubinin-Radushkevich, and Temkin isotherm equations using linear correlation coefficient. Langmuir isotherm gave the best correlation of adsorption for all the adsorbents studied. Thermodynamic study showed that adsorption of AO on ACC (with a more negative Gibbs free energy value) is more favoured. BFA which was used without any pretreatment showed high surface area, pore volume and pore size exhibiting its potential to be used as an adsorbent for the removal of AO.

Experiment, modeling and optimization of liquid phase adsorption of Cu(II) using dried and carbonized biomass of Lyngbya majuscula

NASA Astrophysics Data System (ADS)

Kushwaha, Deepika; Dutta, Susmita

2017-05-01

The present work aims at evaluation of the potential of cyanobacterial biomass to remove Cu(II) from simulated wastewater. Both dried and carbonized forms of Lyngbya majuscula, a cyanobacterial strain, have been used for such purpose. The influences of different experimental parameters viz., initial Cu(II) concentration, solution pH and adsorbent dose have been examined on sorption of Cu(II). Kinetic and equilibrium studies on Cu(II) removal from simulated wastewater have been done using both dried and carbonized biomass individually. Pseudo-second-order model and Langmuir isotherm have been found to fit most satisfactorily to the kinetic and equilibrium data, respectively. Maximum 87.99 and 99.15 % of Cu(II) removal have been achieved with initial Cu(II) concentration of 10 and 25 mg/L for dried and carbonized algae, respectively, at an adsorbent dose of 10 g/L for 20 min of contact time and optimum pH 6. To optimize the removal process, Response Surface Methodology has been employed using both the dried and carbonized biomass. Removal with initial Cu(II) concentration of 20 mg/L, with 0.25 g adsorbent dose in 50 mL solution at pH 6 has been found to be optimum with both the adsorbents. This is the first ever attempt to make a comparative study on Cu(II) removal using both dried algal biomass and its activated carbon. Furthermore, regeneration of matrix was attempted and more than 70% and 80% of the adsorbent has been regenerated successfully in the case of dried and carbonized biomass respectively upto the 3rd cycle of regeneration study.

Synthesis, surface modification and characterisation of biocompatible magnetic iron oxide nanoparticles for biomedical applications.

PubMed

Mahdavi, Mahnaz; Ahmad, Mansor Bin; Haron, Md Jelas; Namvar, Farideh; Nadi, Behzad; Rahman, Mohamad Zaki Ab; Amin, Jamileh

2013-06-27

Superparamagnetic iron oxide nanoparticles (MNPs) with appropriate surface chemistry exhibit many interesting properties that can be exploited in a variety of biomedical applications such as magnetic resonance imaging contrast enhancement, tissue repair, hyperthermia, drug delivery and in cell separation. These applications required that the MNPs such as iron oxide Fe₃O₄ magnetic nanoparticles (Fe₃O₄ MNPs) having high magnetization values and particle size smaller than 100 nm. This paper reports the experimental detail for preparation of monodisperse oleic acid (OA)-coated Fe₃O₄ MNPs by chemical co-precipitation method to determine the optimum pH, initial temperature and stirring speed in order to obtain the MNPs with small particle size and size distribution that is needed for biomedical applications. The obtained nanoparticles were characterized by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray fluorescence spectrometry (EDXRF), thermogravimetric analysis (TGA), X-ray powder diffraction (XRD), and vibrating sample magnetometer (VSM). The results show that the particle size as well as the magnetization of the MNPs was very much dependent on pH, initial temperature of Fe²⁺ and Fe³⁺ solutions and steering speed. The monodisperse Fe₃O₄ MNPs coated with oleic acid with size of 7.8 ± 1.9 nm were successfully prepared at optimum pH 11, initial temperature of 45°C and at stirring rate of 800 rpm. FTIR and XRD data reveal that the oleic acid molecules were adsorbed on the magnetic nanoparticles by chemisorption. Analyses of TEM show the oleic acid provided the Fe₃O₄ particles with better dispersibility. The synthesized Fe₃O₄ nanoparticles exhibited superparamagnetic behavior and the saturation magnetization of the Fe₃O₄ nanoparticles increased with the particle size.

Comparative behaviour of yeast strains for ethanolic fermentation of culled apple juice.

PubMed

Modi, D R; Garg, S K; Johri, B N

1998-07-01

The culled apple juice contained (% w/v): nitrogen, 0.036; total sugars, 11.6 and was of pH 3.9. Saccharomyces cerevisiae NCIM 3284, Pichia kluyeri and Candida krusei produced more ethanol from culled apple juice at its optimum initial pH 4.5, whereas S. cerevisiae NCIM 3316 did so at pH 5.0. An increase in sugar concentration of apple juice from natural 11.6% to 20% exhibited enhanced ethanol production and improved fermentation efficiency of both the S. cerevisiae strains, whereas P. kluyveri and C. krusei produced high ethanol at 11.6% and 16.0% sugar levels, respectively. Urea was stimulatory for ethanol production as well as fermentation efficiency of the yeast strains under study.

Removal of heavy metal from industrial effluents using Baker's yeast

NASA Astrophysics Data System (ADS)

Ferdous, Anika; Maisha, Nuzhat; Sultana, Nayer; Ahmed, Shoeb

2016-07-01

Bioremediation of wastewater containing heavy metals is one of the major challenges in environmental biotechnology. Heavy metals are not degraded and as a result they remain in the ecosystem, and pose serious health hazards as it comes in contact with human due to anthropogenic activities. Biological treatment with various microorganisms has been practiced widely in recent past, however, accessing and maintaining the microorganisms have always been a challenge. Microorganisms like Baker's yeast can be very promising biosorbents as they offer high surface to volume ratio, large availability, rapid kinetics of adsorption and desorption and low cost. The main aim of this study is to evaluate the applicability of the biosorption process using baker's yeast. Here we present an experimental investigation of biosorption of Chromium (Cr) from water using commercial Baker's Yeast. It was envisaged that yeast, dead or alive, would adsorb heavy metals, however, operating parameters could play vital roles in determining the removal efficiency. Parameters, such as incubation time, pH, amount of biosorbent and heavy metal concentration were varied to investigate the impacts of those parameters on removal efficiency. Rate of removal was found to be inversely proportional to the initial Cr (+6) concentrations but the removal rate per unit biomass was a weakly dependent on initial Cr(+6) concentrations. Biosorption process was found to be more efficient at lower pH and it exhibited lower removal with the increase in solution pH. The optimum incubation time was found to be between 6-8 hours and optimum pH for the metal ion solution was 2. The effluents produced in leather industries are the major source of chromium pollution in Bangladesh and this study has presented a very cost effective yet efficient heavy metal removal approach that can be adopted for such kind of wastewater.

Preparation and Antioxidant Activity of Purple Potato Wine

PubMed Central

Zhong-hua, Liu; Jie, Guo

2015-01-01

Purple potatoes were used as raw material to study the purple potato wine production process and antioxidant activity. This paper analyzed different fermentation time, fermentation temperature, yeast inoculum, initial pH, the initial sugar content on alcohol and anthocyanin contents of purple potato wine by single factor experiments and response surface methodology(RSM). The results showed that the optimum fermentation conditions of purple potato wine were as follows: fermentation temperature was 26oC, yeast inoculum was 0.15%, fermentation time was 7 d, initial pH was 3.0 and initial sugar content was 11 %. Under these conditions the alcohol and anthocyanin contents of purple potato wine could reach 10.55%/Vol and 6.42 μg/mL, respectively. The purple potato wine was purple, bright in colour, pleasant fragrance and pure taste. Prepared purple potato wine had the ability of reducing Fe3+ and scavenging superoxide anion radicals, which meant that purple potato wine had certain antioxidant activity. PMID:26998173

In-vitro microbial production of conjugated linoleic acid by probiotic L. plantarum strains: Utilization as a functional starter culture in sucuk fermentation.

PubMed

Özer, Cem O; Kılıç, Birol; Kılıç, Gülden Başyiğit

2016-04-01

Twenty-three probiotic Lactobacillus plantarum strains were screened in-vitro to determine their ability to produce conjugated linoleic acid (CLA). L. plantarum AA1-2 and L. plantarum AB20-961 were identified as potential strains for CLA production. Optimum conditions for these strains to produce high levels of CLA were determined by evaluating the amount of added hydrolyzed sunflower oil (HSO) and initial pH levels in a nutrient medium. The highest CLA production was obtained in medium with pH6.0 and 2% HSO (P<0.05). Those strains were then used as starter culture in sucuk fermentation. Five sucuk treatments included a control (no starter culture), two sucuk groups with L. plantarum AA1-2 at the initial pH of 5.8 or 6.0 and two sucuk groups with L. plantarum AB20-961 at the initial pH of 5.8 or 6.0. Results indicate that L. plantarum AB20-961 produced higher amount of CLA in sucuk at initial pH of 5.8 and 6.0 levels during first 24h of fermentation compared with other groups. CLA isomer concentration decreased in all sucuk groups during the rest of the fermentation period (P<0.05) and remained quite stable during the storage. This study demonstrated that probiotic L. plantarum AB20-961 can be used in sucuk manufacturing without posing any quality problems. Copyright © 2015 Elsevier Ltd. All rights reserved.

Preparation of new nano magnetic material Fe3O4@g-C3N4 and good adsorption performance on uranium ion

NASA Astrophysics Data System (ADS)

Long, Wei; Liu, Huijun; Yan, Xueming; Fu, Li

2018-03-01

A new nano magnetic material Fe3O4@g-C3N4 was prepared by deposition reduction method, which performed good adsorption performance to uranium ion. Characterization results showed that the g-C3N4 particles were wrapped around the nano magnetic Fe3O4 particles, and the textural properties of this material was improved, so the adsorption performance to uranium ion was good. Adsorption experiments of this material demonstrated that the optimum pH value was 10, the optimum mass of adsorbent was 6.5 mg and the optimum adsorption time was 150 min in the initial concentration of 140 mg/L uranium ion solution system, and the maximum adsorption capacity was up to 352.1 mg/g and the maximum adsorption rate was more than 90%.

Biosorption of Nickel from Industrial Wastewater using Zygnema sp.

NASA Astrophysics Data System (ADS)

Sivaprakash, Kanchana; Blessi T. L., Adlin; Madhavan, Jeyanthi

2015-12-01

Contamination of water sources with heavy metals is a very important pollution problem in the current scenario. Biosorption is an effective method for the removal of heavy metal ions from wastewaters. In this study, the removal of Nickel(II) ions from electroplating industrial wastewater using biosorbent prepared from fresh water algal biomass Zygnema was investigated under batch mode. The sorption efficiency of nickel on Zygnema sp. was evaluated as a function of time, pH and sorbent dosage. The Nickel(II) uptake was dependent on initial pH with pH 3 being the optimum value. For 100 mg/L initial Nickel(II) concentration, sorption equilibrium was attained at a contact time of 100 min. The sorbent dosage affected the biosorption efficiency and maximum removal of 76.4 % was obtained at a dosage of 7.5 g/L. From the performance studies, algal biosorbent Zygnema is found to be a valuable material for the removal of Nickel from industrial wastewater and a better substitute for the conventional adsorbents.

Extraction of palm tree cellulose and its functionalization via graft copolymerization.

PubMed

Al-Hoqbani, Abdulmajeed A; Abdel-Halim, E S; Al-Deyab, Salem S

2014-09-01

The work in this paper was planned with the aim of extracting the cellulosic component of palm tree waste and functionalizing this cellulose through graft copolymerization with acrylic acid. The cellulose extraction included hot alkali treatment with aqueous sodium hydroxide to remove the non-cellulosic binding materials. The alkali treatment was followed by an oxidative bleaching using peracid/hydrogen peroxide mixture with the aim of removing the rest of non-cellulosic materials to improve the fiber hydrophilicity and accessibility towards further grafting reaction. Optimum conditions for cellulose extraction are boiling in 5% (W/V) NaOH in a material to liquor ratio of 1:20 for 1 h then bleaching with 60 ml/l bleaching mixture at initial pH value of 6.5 for 30 min. The pH of the bleaching medium is turned to the alkaline range 11 and bleaching continues for extra 30 min. Graft copolymerization reaction was initiated by potassium bromate/thiourea dioxide redox system. Optimum conditions for grafting are 30 mmol of potassium bromate, 30 mmol of thiourea dioxide and 150 g of acrylic acid (each per 100 g of cellulose). The polymerization reaction was carried out for 120 min at 50°C using a material to liquor ratio of 1:20. Copyright © 2014 Elsevier B.V. All rights reserved.

Biosorption of textile dye reactive blue 221 by capia pepper (Capsicum annuum L.) seeds.

PubMed

Gürel, Levent

2017-04-01

Peppers are very important foodstuffs in the world for direct and indirect consumption, so they are extensively used. The seeds of these peppers are waste materials that are disposed of from houses and factories. To evaluate the performance of this biomass in the treatment of wastewaters, a study was conducted to remove a textile dye, reactive blue 221, which is commercially used in textile mills. Raw seed materials were used without any pre-treatment. The effects of contact time, initial concentration of dye, pH and dose of biosorbent were studied to determine the optimum conditions for this biomass on color removal from wastewaters. The optimum pH value for dye biosorption was found to be 2.0. At an initial dye concentration of 217 mg L -1 , treatment efficiency and biosorption capacity were 96.7% and 95.35 mg g -1 , respectively. A maximum biosorption capacity of 142.86 mg g -1 was also obtained. Equilibrium biosorption of dye by capia seeds was well described by the Langmuir isotherm with a correlation coefficient above 99%. The biosorption process was also successfully explained with the pseudo-second order kinetic model. This biomass was found to be effective in terms of textile dye removal from aqueous solutions.

A comprehensive adsorption study and modeling of antibiotics as a pharmaceutical waste by graphene oxide nanosheets.

PubMed

Rostamian, Rahele; Behnejad, Hassan

2018-01-01

The adsorption behavior of tetracycline (TCN), doxycycline (DCN) as the most common antibiotics in veterinary and ciprofloxacin (CPN) onto graphene oxide nanosheets (GOS) in aqueous solution was evaluated. The four factors influencing the adsorption of antibiotics (initial concentration, pH, temperature and contact time) were studied. The results showed that initial pH ∼ 6 to 7 and contact time ∼ 100 - 200min are optimum for each drug. The monolayer adsorption capacity was reduced with the increasing temperature from 25°C to 45°C. Non-linear regressions were carried out in order to define the best fit model for every system. To do this, eight error functions were applied to predict the optimum model. Among various models, Hill and Toth isotherm models represented the equilibrium adsorption data of antibiotics while the kinetic data were well fitted by pseudo second-order (PSO) kinetic model (DCN and TCN) and Elovich (CPN) models. The maximum adsorption capacity (q max ) is found to be in the following order: CPN > DCN > TCN, obtained from sips equation at the same temperature. The GOS shows highest adsorption capacity towards CPN up to 173.4mgg -1 . The study showed that GOS can be removed more efficiently from water solution. Copyright © 2017 Elsevier Inc. All rights reserved.

Degradation kinetics and mechanism of trace nitrobenzene by granular activated carbon enhanced microwave/hydrogen peroxide system.

PubMed

Tan, Dina; Zeng, Honghu; Liu, Jie; Yu, Xiaozhang; Liang, Yanpeng; Lu, Lanjing

2013-07-01

The kinetics of the degradation of trace nitrobenzene (NB) by a granular activated carbon (GAC) enhanced microwave (MW)/hydrogen peroxide (H202) system was studied. Effects of pH, NB initial concentration and tert-butyl alcohol on the removal efficiency were examined. It was found that the reaction rate fits well to first-order reaction kinetics in the MW/GAC/H202 process. Moreover, GAC greatly enhanced the degradation rate of NB in water. Under a given condition (MW power 300 W, H202 dosage 10 mg/L, pH 6.85 and temperature (60 +/- 5)degrees C), the degradation rate of NB was 0.05214 min-1when 4 g/L GAC was added. In general, alkaline pH was better for NB degradation; however, the optimum pH was 8.0 in the tested pH value range of 4.0-12.0. At H202 dosage of 10 mg/L and GAC dosage of 4 g/L, the removal of NB was decreased with increasing initial concentrations of NB, indicating that a low initial concentration was beneficial for the degradation of NB. These results indicated that the MW/GAC/H202 process was effective for trace NB degradation in water. Gas chromatography-mass spectrometry analysis indicated that a hydroxyl radical addition reaction and dehydrogenation reaction enhanced NB degradation.

Biosorption Behavior of Ciprofloxacin onto Enteromorpha prolifera: Isotherm and Kinetic Studies.

PubMed

Wu, Shaoling; Li, Yanhui; Zhao, Xindong; Du, Qiuju; Wang, Zonghua; Xia, Yanzhi; Xia, Linhua

2015-01-01

The studies aimed at the feasibility of using Enteromorpha prolifera for the removal of ciprofloxacin from aqueous solutions. Batch experiments were carried out for the biosorption of ciprofloxacin onto Enteromorpha prolifera. The factors affecting the biosorption process such as the initial concentration, dosage, pH and the contact time were studied. Enteromorpha prolifera exhibited a maximum biosorption capacity of 21.7 mg/g. The pseudo-second-order kinetic model described the ciprofloxacin biosorption process with a good fitting. The optimum pH of ciprofloxacin adsorbed by Enteromorpha prolifera was 10. Biosorption equilibrium studies demonstrated that the biosorption followed Freundlich isotherm model, which implied a heterogeneous biosorption phenomenon.

Ozonation performance of WWTP secondary effluent of antibiotic manufacturing wastewater.

PubMed

Zheng, Shaokui; Cui, Cancan; Liang, Qianjin; Xia, Xinghui; Yang, Fan

2010-11-01

The ozonation performance of wastewater treatment plant secondary effluent of oxytetracycline (OTC) manufacturing wastewater was investigated in terms of ozone dosage and initial pH levels when OTC contributed to a negligible fraction in the chemical oxygen demand (COD) ingredients of the medium-organic-strength wastewater with low biodegradability. A particular emphasis was placed on ammonia, OTC, and residual antibacterial activity (RAA) (evaluated using the objective pathogenic bacterium Staphylococcus aureus). It appears that an ozone dosage of 657 mg L⁻¹ (120 min of reaction) was enough to achieve an OTC abatement of 96%, and COD and biochemical oxygen demand removals of 29% and 33%, respectively, at initial levels of 10.4, 1360, and 300 mg L⁻¹ , respectively. There is a clear correlation between complete OTC depletion and complete RAA disappearance with an increase of ozone dosage. The presence of plentiful non-antibiotic refractory substances influenced the determination of the optimum ozone dosage for biodegradability enhancement and OTC/RAA reduction as well as the ozonation transformation of NH(3). The initial pH adjustment from the original level (pH 9) to pH 11 significantly reduced COD removal while RAA and NH(3) levels were not significantly influenced. Copyright © 2010 Elsevier Ltd. All rights reserved.

Adsorption of Cd(II) Metal Ion on Adsorbent beads from Biomass Saccharomycess cereviceae - Chitosan

NASA Astrophysics Data System (ADS)

Hasri; Mudasir

2018-01-01

The adsorbent beads that was preparation from Saccharomycess cereviceae culture strain FN CC 3012 and shrimp shells waste and its application for adsorption of Cd (II) metal ion has been studied. The study start with combination of Saccharomycess cereviceae biomass to chitosan (Sc-Chi), contact time, pH of solution and initial concentration of cations. Total Cd(II) metal ion adsorbed was calculated from the difference of metal ion concentration before and after adsorption by AAS. The results showed that optimum condition for adsorption of Cd(II) ions by Sc-Chi beads was achieved with solution pH of 4, contact time of 60 minutes and initial concentration adsorption 100mg/L. The hydroxyl (-OH) and amino (-NH2) functional groups were believed to be responsible for the adsorption of Cd(II) ions.

Optimization of γ-aminobutyric acid production by Lactobacillus plantarum Taj-Apis362 from honeybees.

PubMed

Tajabadi, Naser; Ebrahimpour, Afshin; Baradaran, Ali; Rahim, Raha Abdul; Mahyudin, Nor Ainy; Manap, Mohd Yazid Abdul; Bakar, Fatimah Abu; Saari, Nazamid

2015-04-15

Dominant strains of lactic acid bacteria (LAB) isolated from honey bees were evaluated for their γ-aminobutyric acid (GABA)-producing ability. Out of 24 strains, strain Taj-Apis362 showed the highest GABA-producing ability (1.76 mM) in MRS broth containing 50 mM initial glutamic acid cultured for 60 h. Effects of fermentation parameters, including initial glutamic acid level, culture temperature, initial pH and incubation time on GABA production were investigated via a single parameter optimization strategy. The optimal fermentation condition for GABA production was modeled using response surface methodology (RSM). The results showed that the culture temperature was the most significant factor for GABA production. The optimum conditions for maximum GABA production by Lactobacillus plantarum Taj-Apis362 were an initial glutamic acid concentration of 497.97 mM, culture temperature of 36 °C, initial pH of 5.31 and incubation time of 60 h, which produced 7.15 mM of GABA. The value is comparable with the predicted value of 7.21 mM.

Equilibrium and kinetic studies of copper biosorption by dead Ceriporia lacerata biomass isolated from the litter of an invasive plant in China.

PubMed

Li, Xiaona; Li, Airong; Long, Mingzhong; Tian, Xingjun

2015-01-01

Ceriporia lacerata, a strain of white-rot fungus isolated from the litter of an invasive plant (Solidago canadensis) in China, was little known about its properties and utilization. In this work, the copper(II) biosorption characteristics of formaldehyde inactivated C. lacerata biomass were examined as a function of initial pH, initial copper(II) concentration and contact time, and the adsorptive equilibrium and kinetics were simulated, too. The optimum pH was found to be 6.0 at experimental conditions of initial copper(II) concentration 100 mg/L, biomass dose 2 g/L, contact time 12 h, shaking rate 150 r/min and temperature 25°C. Biosorption equilibrium cost about 1 hour at experimental conditions of pH 6.0, initial copper(II) concentration 100 mg/L, C. lacerata dose 2 g/L, shaking rate 150 r/min and temperature 25°C. At optimum pH 6.0, highest copper(II) biosorption amounts were 6.79 and 7.76 mg/g for initial copper(II) concentration of 100 and 200 mg/L, respectively (with other experimental parameters of C. lacerata dose 2 g/L, shaking rate 150 r/min and temperature 25°C). The pseudo second-order adsorptive model gave the best adjustment for copper(II) biosorption kinetics. The equilibrium data fitted very well to both Langmuir and Freundlich adsorptive isotherm models. Without further acid or alkali treatment for improving adsorption properties, formaldehyde inactivated C. lacerata biomass possesses good biosorption characteristics on copper(II) removal from aqueous solutions.

Hydrolyses of alpha-naphthyl acetate, beta-naphthyl acetate, and acetyl-DL-phenylalanine beta-naphthyl ester.

PubMed

Kirkeby, S; Moe, D

1983-01-01

Using simultaneous coupling azo dye techniques kidney enzymes active against alpha-naphthyl acetate, beta-naphthyl acetate, and acetyl-DL-phenylalanine beta-naphthyl ester are characterized. The enzymes show identical distribution in the section. The banding patterns in zymograms are the same after incubation with the different substrates. The enzymes might, however, be separated by difference in pH optimum, initial velocity and sensitivity to inhibitors and activators.

Multi-Response Optimization of Granaticinic Acid Production by Endophytic Streptomyces thermoviolaceus NT1, Using Response Surface Methodology

PubMed Central

Roy, Sudipta; Halder, Suman Kumar; Banerjee, Debdulal

2016-01-01

Streptomyces thermoviolaceus NT1, an endophytic isolate, was studied for optimization of granaticinic acid production. It is an antimicrobial metabolite active against even drug resistant bacteria. Different media, optimum glucose concentration, initial media pH, incubation temperature, incubation period, and inoculum size were among the selected parameters optimized in the one-variable-at-a-time (OVAT) approach, where glucose concentration, pH, and temperature were found to play a critical role in antibiotic production by this strain. Finally, the Box–Behnken experimental design (BBD) was employed with three key factors (selected after OVAT studies) for response surface methodological (RSM) analysis of this optimization study.RSM analysis revealed a multifactorial combination; glucose 0.38%, pH 7.02, and temperature 36.53 °C as the optimum conditions for maximum antimicrobial yield. Experimental verification of model analysis led to 3.30-fold (61.35 mg/L as compared to 18.64 mg/L produced in un-optimized condition) enhanced granaticinic acid production in ISP2 medium with 5% inoculum and a suitable incubation period of 10 days. So, the conjugated optimization study for maximum antibiotic production from Streptomyces thermoviolaceus NT1 was found to result in significantly higher yield, which might be exploited in industrial applications. PMID:28952581

Optimisation of the reaction conditions for the production of cross-linked starch with high resistant starch content.

PubMed

Kahraman, Kevser; Koksel, Hamit; Ng, Perry K W

2015-05-01

The optimum reaction conditions (temperature and pH) for the preparation of cross-linked (CL) corn and wheat starches with maximum resistant starch (RS) content were investigated by using response surface methodology (RSM). According to the preliminary results, five levels were selected for reaction temperature (38-70 °C) and pH (10-12) in the main study. RS contents of the CL corn and wheat starch samples increased with increasing temperature and pH, and pH had a greater influence on RS content than had temperature. The maximum RS content (with a maximum p value of 0.4%) was obtained in wheat starch cross-linked at 38 °C and pH 12. In the case of CL corn starch, the optimum condition was 70 °C and pH 12. CL corn and wheat starch samples were also produced separately under the optimum conditions and their RS contents were 80.4% and 83.9%, respectively. These results were also in agreement with the values predicted by RSM. Copyright © 2014 Elsevier Ltd. All rights reserved.

Treatment of oilfield produced water using Fe/C micro-electrolysis assisted by zero-valent copper and zero-valent aluminium.

PubMed

Zhang, Qi

2015-01-01

In this study, the Fe/Cu/C and Fe/Al/C inner micro-electrolysis systems were used to treat actual oilfield produced water to evaluate the feasibility of the technology. Effects of reaction time, pH value, the dosage of metals and activated carbon, and Fe:C mass ratio on the treatment efficiency of wastewater were studied. The results showed that the optimum conditions were reaction time 120 min, initial solution pH 4.0, Fe dosage 13.3 g/L, activated carbon dosage 6.7 g/L, Cu dosage 2.0 g/L or Al dosage 1.0 g/L. Under the optimum conditions, the removal efficiencies of chemical oxygen demand (COD) were 39.3%, 49.7% and 52.6% in the Fe/C, Fe/Cu/C and Fe/Al/C processes, respectively. Meanwhile, the ratio of five-day biochemical oxygen demand to COD was raised from 0.18 to above 0.35, which created favourable conditions for the subsequent biological treatment. All these led to an easy maintenance and low operational cost.

Influence of cultivating conditions on the alpha-galactosidase biosynthesis from a novel strain of Penicillium sp. in solid-state fermentation.

PubMed

Wang, C L; Li, D F; Lu, W Q; Wang, Y H; Lai, C H

2004-01-01

The work is intended to achieve optimum culture conditions of alpha-galactosidase production by a mutant strain Penicillium sp. in solid-state fermentation (SSF). Certain fermentation parameters involving incubation temperature, moisture content, initial pH value, inoculum and load size of medium, and incubation time were investigated separately. The optimal temperature and moisture level for alpha-galactosidase biosynthesis was found to be 30 degrees C and 50%, respectively. The range of pH 5.5-6.5 was favourable. About 40-50 g of medium in 250-ml flask and inoculum over 1.0 x 10(6) spores were suitable for enzyme production. Seventy-five hours of incubation was enough for maximum alpha-galactosidase production. Substrate as wheat bran supplemented with soyabean meal and beet pulp markedly improved the enzyme yield in trays. Under optimum culture conditions, the alpha-galactosidase activity from Penicillium sp. MAFIC-6 indicated 185.2 U g(-1) in tray of SSF. The process on alpha-galactosidase production in laboratory scale may have a potentiality of scaling-up.

Effect of pH on simultaneous saccharification and isomerization by glucoamylase and glucose isomerase.

PubMed

Mishra, Abha; Debnath Das, Meera

2002-01-01

pH and temperature play critical roles in multistep enzymatic conversions. In such conversions, the optimal pH for individual steps differs greatly. In this article, we describe the production of glucoamylase (from Aspergillus oryzae MTCC152 in solid-state fermentation) and glucose isomerase (from Streptomyces griseus NCIM2020 in submerged fermentation), used in industries for producing high-fructose syrup. Optimum pH for glucoamylase was found to be 5.0. For glucose isomerase, the optimum pH ranged between 7.0 and 8.5, depending on the type of buffer used. Optimum temperature for glucoamylase and glucose isomerase was 50 and 60 degrees C, respectively. When both the enzymatic conversions were performed simultaneously at a compromised pH of 6.5, both the enzymes showed lowered activity. We also studied the kinetics at different pHs, which allows the two-step reaction to take place simultaneously. This was done by separating two steps by a thin layer of urease. Ammonia generated by the hydrolysis of urea consumed the hydrogen ions, thereby allowing optimal activity of glucose isomerase at an acidic pH of 5.0.

Utilization of rice husks modified by organomultiphosphonic acids as low-cost biosorbents for enhanced adsorption of heavy metal ions.

PubMed

Xu, Mingyu; Yin, Ping; Liu, Xiguang; Tang, Qinghua; Qu, Rongjun; Xu, Qiang

2013-12-01

Novel biosorbent materials (RH-2 and RH-3) obtained from agricultural waste materials rice husks (RH-1) were successfully developed through fast and facile esterification reactions with hydroxylethylidenediphosphonic acid and nitrilotrimethylenetriphosphonic acid, respectively. The present paper reported the feasibility of using RH-1, RH-2 and RH-3 for removal of heavy metals from simulated wastewater, the results revealed that the adsorption property of functionalized rice husks with organotriphosphonic acid RH-3 for Au(III) was very excellent, especially for gold ions. The combined effect of initial solution pH, RH-3 dosage and initial Au(III) concentration was investigated using response surface methodology (RSM), the results showed that initial Au(III) concentration exerted stronger influence on Au(III) uptake than initial pH and biomass dosage. The analysis of variance (ANOVA) of the quadratic model demonstrated that the model was highly significant, and under the optimum process conditions, the maximum adsorption capacity could reach 3.25 ± 0.07 mmol/g that is higher than other reported adsorbents. Copyright © 2013 Elsevier Ltd. All rights reserved.

Degradation of alachlor in aqueous solution by using hydrodynamic cavitation.

PubMed

Wang, Xikui; Zhang, Yong

2009-01-15

The degradation of alachlor aqueous solution by using hydrodynamic cavitation was systematically investigated. It was found that alachlor in aqueous solution can be deomposed with swirling jet-induced cavitation. The degradation can be described by a pseudo-first-order kinetics and the degradation rate was found to be 4.90x10(-2)min(-1). The effects of operating parameters such as fluid pressure, solution temperature, initial concentration of alachlor and medium pH on the degradation rates of alachlor were also discussed. The results showed that the degradation rates of alachlor increased with increasing pressure and decreased with increasing initial concentration. An optimum temperature of 40 degrees C existed for the degradation rate of alachlor and the degradation rate was also found to be slightly depend on medium pH. Many degradation products formed during the process, and some of them were qualitatively identified by GC-MS.

Parametric and energy consumption optimization of Basic Red 2 removal by electrocoagulation/egg shell adsorption coupling using response surface methodology in a batch system.

PubMed

de Carvalho, Helder Pereira; Huang, Jiguo; Zhao, Meixia; Liu, Gang; Yang, Xinyu; Dong, Lili; Liu, Xingjuan

2016-01-01

In this study, response surface methodology (RSM) model was applied for optimization of Basic Red 2 (BR2) removal using electrocoagulation/eggshell (ES) coupling process in a batch system. Central composite design was used to evaluate the effects and interactions of process parameters including current density, reaction time, initial pH and ES dosage on the BR2 removal efficiency and energy consumption. The analysis of variance revealed high R(2) values (≥85%) indicating that the predictions of RSM models are adequately applicable for both responses. The optimum conditions when the dye removal efficiency of 93.18% and energy consumption of 0.840 kWh/kg were observed were 11.40 mA/cm(2) current density, 5 min and 3 s reaction time, 6.5 initial pH and 10.91 g/L ES dosage.

Simple Response Surface Methodology: Investigation on Advance Photocatalytic Oxidation of 4-Chlorophenoxyacetic Acid Using UV-Active ZnO Photocatalyst.

PubMed

Lee, Kian Mun; Hamid, Sharifah Bee Abd

2015-01-19

The performance of advance photocatalytic degradation of 4-chlorophenoxyacetic acid (4-CPA) strongly depends on photocatalyst dosage, initial concentration and initial pH. In the present study, a simple response surface methodology (RSM) was applied to investigate the interaction between these three independent factors. Thus, the photocatalytic degradation of 4-CPA in aqueous medium assisted by ultraviolet-active ZnO photocatalyst was systematically investigated. This study aims to determine the optimum processing parameters to maximize 4-CPA degradation. Based on the results obtained, it was found that a maximum of 91% of 4-CPA was successfully degraded under optimal conditions (0.02 g ZnO dosage, 20.00 mg/L of 4-CPA and pH 7.71). All the experimental data showed good agreement with the predicted results obtained from statistical analysis.

Auxin-induced growth of Avena coleoptiles involves two mechanisms with different pH optima

NASA Technical Reports Server (NTRS)

Cleland, R. E.

1992-01-01

Although rapid auxin-induced growth of coleoptile sections can persist for at least 18 hours, acid-induced growth lasts for a much shorter period of time. Three theories have been proposed to explain this difference in persistence. To distinguish between these theories, the pH dependence for auxin-induced growth of oat (Avena sativa L.) coleoptiles has been determined early and late in the elongation process. Coleoptile sections from which the outer epidermis was removed to facilitate buffer entry were incubated, with or without 10 micromolar indoleacetic acid, in 20 millimolar buffers at pH 4.5 to 7.0 to maintain a fixed wall pH. During the first 1 to 2 hours after addition of auxin, elongation occurs by acid-induced extension (i.e. the pH optimum is <5 and the elongation varies inversely with the solution pH). Auxin causes no additional elongation because the buffers prevent further changes in wall pH. After 60 to 90 minutes, a second mechanism of auxin-induced growth, whose pH optimum is 5.5 to 6.0, predominates. It is proposed that rapid growth responses to changes in auxin concentration are mediated by auxin-induced changes in wall pH, whereas the prolonged, steady-state growth rate is controlled by a second, auxin-mediated process whose pH optimum is less acidic.

Production of xylanase from an alkali tolerant Streptomyces sp. 7b under solid-state fermentation, its purification, and characterization.

PubMed

Bajaj, Bijender Kumar; Singh, Narendera Pratap

2010-11-01

Streptomyces sp. 7b showed highest xylanase activity among 41 bacterial isolates screened under submerged fermentation. The organism grew over broad pH (5-11) and temperatures range (25-55 degrees C) and displayed maximum xylanase production on wheat bran (1230 U/g) under solid-state fermentation. Xylanase production was enhanced substantially (76%-77%) by inclusion of trypton (2180 U/g) or beef extract (2170 U/g) and moderately (36%-46%) by yeast extract (1800 U/g) or soybean meal (1670 U/g). Inclusion of readily utilizable sugars such as glucose, maltose, fructose, lactose or xylose in the substrate repressed the xylanase production. The optimum initial pH of the medium for maximum enzyme production was 7 to 8; however, appreciable level of activity was obtained at pH 6 (1,680 U/g) and 9 (1,900 U/g). Most appropriate solid to liquid ratio for maximum xylanase production in solid-state fermentation was found to be 1:2.5. The organism produced a single xylanase of molecular weight of approximately 30 kDa as analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis after purification with ammonium sulfate precipitation, and carboxy methyl sephadex chromatography. The enzyme was purified to the extent of 5.68-fold by salt precipitation and ion-exchange chromatography. Optimum temperature and pH for maximum xylanase activity were 50 degrees C and 6, respectively.

Decolorization of distillery spent wash effluent by electro oxidation (EC and EF) and Fenton processes: A comparative study.

PubMed

David, Charles; Arivazhagan, M; Tuvakara, Fazaludeen

2015-11-01

In this study, laboratory scale experiments were performed to degrade highly concentrated organic matter in the form of color in the distillery spent wash through batch oxidative methods such as electrocoagulation (EC), electrofenton (EF) and Fenton process. The effect of corresponding operating parameters, namely initial pH: 2-10; current intensity: 1-5A; electrolysis time: 0.5-4h; agitation speed: 100-500rpm; inter-electrode distance: 0.5-4cm and Fenton's reagent dosage: 5-40mg/L was employed for optimizing the process of spent wash color removal. The performance of all the three processes was compared and assessed in terms of percentage color removal. For EC, 79% color removal was achieved using iron electrodes arranged with 0.5cm of inter-electrode space and at optimum conditions of pH 7, 5A current intensity, 300rpm agitation speed and in 2h of electrolysis time. In EF, 44% spent wash decolorization was observed using carbon (graphite) electrodes with an optimum conditions of 0.5cm inter-electrode distance, pH 3, 4A current intensity, 20mg/L FeSO4 and agitation speed of 400rpm for 3h of electrolysis time. By Fenton process, 66% decolorization was attained by Fenton process at optimized conditions of pH 3, 40mg/L of Fenton's reagent and at 500rpm of agitation speed for 4h of treatment time. Copyright © 2015 Elsevier Inc. All rights reserved.

Photocatalytic pretreatment of oily wastewater from the restaurant by a vacuum ultraviolet/TiO2 system.

PubMed

Kang, Jian-xiong; Lu, Lu; Zhan, Wei; Li, Bo; Li, Dao-sheng; Ren, Yong-zheng; Liu, Dong-qi

2011-02-15

The present study aims at investigating the performance of a vacuum ultraviolet (VUV, 185 nm) and TiO(2) oxidation system for the pretreatment of oily wastewater from restaurant. The influence of irradiation time, pH, dissolved oxygen (DO), the dosage of TiO(2) and the initial chemical oxygen demand (COD) concentration on COD removal efficiency was ascertained and optimum process conditions for stable and effective operation were determined. Under the optimum conditions of irradiation 10 min, initial COD 3981 mg/L, TiO(2) 150 mg/L, pH 7.0 and flow rate of air 40 L/h, the process of VUV and TiO(2)/VUV achieved removal efficiencies of COD, BOD(5) and oil as 50±3%, 37±2%, 86±3%, and 63±3%, 43±2%, 70±3%, respectively. The biodegradability factor f(B) of the wastewater was determined as 1.56 which indicated that the VUV/TiO(2) process improved the biodegradability of the oily wastewater significantly. Results clearly indicate that VUV/TiO(2) photolysis tends to destruct parts of COD, BOD(5), and ammonia, as well as enhances the biodegradability of the oily wastewater simultaneously. Thus, this technique could be used as a pretreatment step for conventional biological treatment of oily wastewater. Copyright © 2010 Elsevier B.V. All rights reserved.

Alginate-immobilized bentonite clay: adsorption efficacy and reusability for Cu(II) removal from aqueous solution.

PubMed

Tan, Wei Shang; Ting, Adeline Su Yien

2014-05-01

This study evaluated the use of alginate-immobilized bentonite to remove Cu(II) as an alternative to mitigate clogging problems. The adsorption efficacy (under the influence of time, pH and initial Cu(II) concentration) and reusability of immobilized-bentonite (1% w/v bentonite) was tested against plain alginate beads. Results revealed that immobilized bentonite demonstrated significantly higher sorption efficacy compared to plain alginate beads with 114.70 and 94.04 mg Cu(II) adsorbed g(-1) adsorbent, respectively. Both sorbents were comparable in other aspects where sorption equilibrium was achieved within 6 h, with optimum pH between pH 4 and 5 for adsorption, displayed maximum adsorption capacity at initial Cu(II) concentrations of 400 mg l(-1), and demonstrated excellent reusability potential with desorption greater than 90% throughout three consecutive adsorption-desorption cycles. Both sorbents also conformed to Langmuir isotherm and pseudo-second order kinetic model. Immobilized bentonite is therefore recommended for use in water treatments to remove Cu(II) without clogging the system. Copyright © 2013 Elsevier Ltd. All rights reserved.

The Influence of pH on Prokaryotic Cell Size and Temperature

NASA Astrophysics Data System (ADS)

Sundararajan, D.; Gutierrez, F.; Heim, N. A.; Payne, J.

2015-12-01

The pH of a habitat is essential to an organism's growth and success in its environment. Although most organisms maintain a neutral internal pH, their environmental pH can vary greatly. However, little research has been done concerning an organism's environmental pH across a wide range of taxa. We studied pH tolerance in prokaryotes and its relationship with biovolume, taxonomic classification, and ideal temperature. We had three hypotheses: pH and temperature are not correlated; pH tolerance is similar within taxonomic groups; and extremophiles have small cell sizes. To test these hypotheses, we used pH, size, and taxonomic data from The Prokaryotes. We found that the mean optimum external pH was neutral for prokaryotes as a whole and when divided by domain, phylum, and class. Using ANOVA to test for pH within and among group variances, we found that variation of pH in domains, phyla, classes, and families was greater than between them. pH and size did not show much of a correlation, except that the largest and smallest sized prokaryotes had nearly neutral pH. This seems significant because extremophiles need to divert more of their energy from growth to maintain a neutral internal pH. Acidophiles showed a larger range of optimum pH values than alkaliphiles. A similar result was seen with the minimum and maximum pH values of acidophiles and alkaliphiles. While acidophiles were spread out and had some alkaline maximum values, alkaliphiles had smaller ranges, and unlike some acidophiles that had pH minimums close to zero, alkaliphile pH maximums did not go beyond a pH of 12. No statistically significant differences were found between sizes of acidophiles and alkaliphiles. However, optimum temperatures of acidophiles and alkaliphiles did have a statistically significant difference. pH and temperature had a negative correlation. Therefore, pH seems to have a correlation with cell size, temperature, and taxonomy to some extent.

Optimization and performance evaluation for nutrient removal from palm oil mill effluent wastewater using microalgae

NASA Astrophysics Data System (ADS)

Ibrahim, Raheek I.; Wong, Z. H.; Mohammad, A. W.

2015-04-01

Palm oil mill effluent (POME) wastewater was produced in huge amounts in Malaysia, and if it discharged into the environment, it causes a serious problem regarding its high content of nutrients. This study was devoted to POME wastewater treatment with microalgae. The main objective was to find the optimum conditions (retention time, and pH) in the microalgae treatment of POME wastewater considering retention time as a most important parameter in algae treatment, since after the optimum conditions there is a diverse effect of time and pH and so, the process becomes costly. According to our knowledge, there is no existing study optimized the retention time and pH with % removal of nutrients (ammonia nitrogen NH3-N, and orthophosphorous PO43-) for microalgae treatment of POME wastewater. In order to achieve with optimization, a central composite rotatable design with a second order polynomial model was used, regression coefficients and goodness of fit results in removal percentages of nutrients (NH3-N, and PO43-) were estimated.WinQSB technique was used to optimize the surface response objective functionfor the developed model. Also experiments were done to validate the model results.The optimum conditions were found to be 18 day retention time for ammonia nitrogen, and pH of 9.22, while for orthophosphorous, 15 days were indicated as the optimum retention time with a pH value of 9.2.

A study of the parameters affecting the effectiveness of Moringa oleifera in drinking water purification

NASA Astrophysics Data System (ADS)

Pritchard, M.; Craven, T.; Mkandawire, T.; Edmondson, A. S.; O'Neill, J. G.

The powder obtained from the seeds of the Moringa oleifera tree has been shown to be an effective primary coagulant for water treatment. When the seeds are dried, dehusked, crushed and added to water, the powder acts as a coagulant binding colloidal particles and bacteria to form agglomerated particles (flocs), which settle allowing the clarified supernatant to be poured off. Very little research has been undertaken on the parameters affecting the effectiveness of M. oleifera, especially in Malawi, for purification of drinking water and there is a great need for further testing in this area. Conclusive data needs to be compiled to demonstrate the effects of various water parameters have on the efficiency of the seeds. A parametric study was undertaken at Leeds Metropolitan University, UK, with the aim to establish the most appropriate dosing method; the optimum dosage for removal of turbidity; the influence of pH and temperature; together with the shelf life of the M. oleifera seeds. The study revealed that the most suitable dosing method was to mix the powder into a concentrated paste, hence forming a stock suspension. The optimum M. oleifera dose, for turbidity values between 40 and 200 NTU, ranged between 30 and 55 mg/l. With turbidity set at 130 NTU and a M. oleifera dose within the optimum range at 50 mg/l, pH levels were varied between 4 and 9. It was discovered that the coagulant performance was not too sensitive to pH fluctuations when conditions were within the optimum range. The most efficient coagulation, determined by the greatest reduction in turbidity, occurred at pH 6.5. Alkaline conditions were overall more favourable than acidic conditions; pH 9 had an efficiency of 65% of optimum, whilst at pH 5 the efficiency dropped to around 55%. The efficiency further dropped at pH 4, where the powder only produced results of around 10% of optimum conditions. A temperature range of 4-60 °C was studied in this research. Colder waters (<15 °C) were found to hinder the effectiveness of the coagulation process. The higher the temperature the more effective was the coagulation. It was also found that the age of the seeds, up to 18 months, did not have any noticeable effect on dose level and percentage reduction in turbidity, although at 18 months the seeds had a narrower dosing range to produce near-optimum reduction. Seeds aged 24 months showed a significant decline in coagulant efficiency.

Application of principal component analysis for the optimisation of lead(II) biosorption.

PubMed

Wajda, Łukasz; Duda-Chodak, Aleksandra; Tarko, Tomasz; Kamiński, Paweł

2017-10-03

Current study was focused on optimising lead(II) biosorption carried out by living cells of Arthrospira platensis using Principal Component Analysis. Various experimental conditions were considered: initial metal concentration (50 and 100 mg/l), solution pH (4.0, 4.5, 5.0, 5.5) and contact time (10, 20, 30, 40, 50 and 60 min) at constant rotary speed 200 rpm. It was found that when the biomass was separated from experimental solutions by the filtration, almost 50% of initial metal dose was removed by the filter paper. Moreover, pH was the most important parameter influencing examined processes. The Principal Component Analysis indicated that the most optimum conditions for lead(II) biosorption were metal initial concentration 100 mg/l, pH 4.5 and time 60 min. According to the analysis of the first component it might be stated that the lead(II) uptake increases in time. In overall, it was found to be useful for analysing data obtained in biosorption experiments and eliminating insignificant experimental conditions. Experimental data fitted Langmuir and Dubinin-Radushkevich models indicating that physical and chemical absorption take place at the same time. Further studies are necessary to verify how sorption-desorption cycles affect A. platensis cells.

Immobilization and kinetics of catalase on calcium carbonate nanoparticles attached epoxy support.

PubMed

Preety; Hooda, Vinita

2014-01-01

A novel hybrid epoxy/nano CaCO3 composite matrix for catalase immobilization was prepared by polymerizing epoxy resin in the presence of CaCO3 nanoparticles. The hybrid support was characterized using scanning electron microscopy and Fourier transform infrared spectroscopy. Catalase was successfully immobilized onto epoxy/nano CaCO3 support with a conjugation yield of 0.67 ± 0.01 mg/cm(2) and 92.63 ± 0.80 % retention of activity. Optimum pH and optimum temperature of free and immobilized catalases were found to be 7.0 and 35 °C. The value of Km for H2O2 was higher for immobilized enzyme (31.42 mM) than native enzyme (27.73 mM). A decrease in Vmax value from 1,500 to 421.10 μmol (min mg protein)(-1) was observed after immobilization. Thermal and storage stabilities of catalase improved immensely after immobilization. Immobilized enzyme retained three times than the activity of free enzyme when kept at 75 °C for 1 h and the half-life of enzyme increased five times when stored in phosphate buffer (0.01 M, pH 7.0) at 5 °C. The enzyme could be reused 30 times without any significant loss of its initial activity. Desorption of catalase from the hybrid support was minimum at pH 7.0.

Adsorption Effectivity Test of Andisols Clay-Zeolite (ACZ) Composite as Chromium Hexavalent (Cr(VI)) Ion Adsorbent

NASA Astrophysics Data System (ADS)

Pranoto; Masykur, A.; Nugroho, Y. A.

2018-03-01

Adsorption of chromium hexavalent (Cr(VI)) ion in aqueous solution was investigated. This research was purposed to study the influence of the composition of ACZ, temperature activation, and contact time against adsorption capacity of Cr(VI) ion in aqueous solution. Determination of adsorption effectivity using several parameter such as composition variation of ACZ, contact time, pH, activation temperature, and concentration. In this research, andisol clay and zeolite has been activated with NaOH 3 M and 1 M, respectively. Temperature variation used 100, 200, and 400°C. While composition variation ACZ used 0:100, 25:75, 50:50, 75:25, 100:0. The pH variation was used 2 – 6 and concentration variation using 2, 4, 6, 8, 10, and 12 ppm. Characterization in this research used such as UV-Vis, Surface Area Analyzer (SAA) and Acidity Analysis. Result of this research is known that optimum composition of ACZ was 50:50 with calcination temperature 100°C. Optimum adsorption of Cr(VI) at pH 4 with removal percentage 76.10 % with initial concentration 2 ppm and adsorption capacity is 0.16 mg/g. Adsorption isotherm following freundlich isotherm with value Kf = 0.17 mg/g and value n is 0.963. Based on results, ACZ composite can be used as Cr(VI) ion adsorbents in aqueous solutions.

Comparative studies on adsorptive removal of heavy metal ions by biosorbent, bio-char and activated carbon obtained from low cost agro-residue.

PubMed

Kırbıyık, Çisem; Pütün, Ayşe Eren; Pütün, Ersan

2016-01-01

In this study, Fe(III) and Cr(III) metal ion adsorption processes were carried out with three adsorbents in batch experiments and their adsorption performance was compared. These adsorbents were sesame stalk without pretreatment, bio-char derived from thermal decomposition of biomass, and activated carbon which was obtained from chemical activation of biomass. Scanning electron microscopy and Fourier transform-infrared techniques were used for characterization of adsorbents. The optimum conditions for the adsorption process were obtained by observing the influences of solution pH, adsorbent dosage, initial solution concentration, contact time and temperature. The optimum adsorption efficiencies were determined at pH 2.8 and pH 4.0 for Fe(III) and Cr(III) metal ion solutions, respectively. The experimental data were modelled by different isotherm models and the equilibriums were well described by the Langmuir adsorption isotherm model. The pseudo-first-order, pseudo-second-order kinetic, intra-particle diffusion and Elovich models were applied to analyze the kinetic data and to evaluate rate constants. The pseudo-second-order kinetic model gave a better fit than the others. The thermodynamic parameters, such as Gibbs free energy change ΔG°, standard enthalpy change ΔH° and standard entropy change ΔS° were evaluated. The thermodynamic study showed the adsorption was a spontaneous endothermic process.

Biosorption of Cr(VI) in Aqueous Solution using Microorganisms: Comparison of the Use of Rhizopus oryzae, Bacillus firmus, and Trichoderma viride

NASA Astrophysics Data System (ADS)

Safitri, Anna; Mahardini, Putri; Prasetyawan, Sasangka; Roosdiana, Anna

2018-01-01

In this work, the study of biosorption of Cr(VI) from aqueous solution was conducted using Rhizopus oryzae, Bacillus firmus, and Trichoderma viride as microorganisms that can absorb Cr(VI). The research is focused on determination of optimum conditions including pH, the number of R. oryzae, B. firmus, and T. viride (inoculums), and initial concentrations of Cr(VI) used. Optimum pH was obtained at pH 5, 4.5 and 6, for biosorption of Cr(VI) with R. oryzae, B. firmus, and T. viride, respectively, in the capacity of 45.3%, 24.5%, and 90.3%. The highest amount of Cr(VI) adsorbed for biosorption with R. oryzae, B. firmus, and T. viride, were 55.4%, 18.5%, and 74.5%, respectively, using 6-mL inoculums. The equilibrium concentrations achieved for R. oryzae, B. firmus, and T. viride were 60 mg/mL, 40 mg/mL, and 40 mg/mL, with the amount of Cr(VI) adsorbed were 32.4%, 28.2%, and 89.3%, respectively. The adsorption capacity for R. oryzae, B. firmus, and T. viride were 45.3 mg/1×106 colonies, 36.2 mg/1×106 cells, and 77.8 mg/1×106 colonies, respectively. Overall, the biosorbents effectivity order in the biosorption process of Cr(VI) are T. viride > R. oryzae > B. firmus.

Preliminary screening oxidative degradation methyl orange using ozone/ persulfate

NASA Astrophysics Data System (ADS)

Aqilah Razali, Nur; Zulzikrami Azner Abidin, Che; An, Ong Soon; Ridwan, Fahmi Muhammad; Haqi Ibrahim, Abdul; Nasuha Sabri, Siti; Huan Kow, Su

2018-03-01

The present study focusing on the performances of advanced oxidation process by using ozonation method towards Methyl Orange based on the efficiency of colour removal and Chemical Oxygen Demand (COD) removal. Factorial design with response surface methodology (RSM) was used to evaluate the interaction between operational conditions, such as pH, initial concentration, contact time and persulfate dosage to obtain the optimum range conditions using a semi-batch reactor. The range of independent variables investigated were pH (3-11), initial concentration (100-500mg/L), contact time (10-50min) and persulfate dosage (20-100mM) while the response variables were colour removal and COD removal of Methyl Orange. The experimental results and statistical analysis showed all the parameters were significant. Thus, from this findings, optimization of operational conditions that had been suggested from the ozone/persulfate RSM analysis were (pH 3, 100 mg/L, 50min, 60mM) that would be produced 99% Colour Removal and 80% COD Removal and help in promoting an efficient ozonation process. The effect list data that showed the most contributed effects to increase the percentages of colour removal were pH and persulfate dosage whereas the contact time and initial concentration had the highest positive effects on the COD removal. Other than that, the interaction between pH, contact time and persulfate dosage were found to be the most influencing interaction. Therefore the least influencing interaction was interaction between persulfate dosage and pH. In this study, the correlation coefficient value R2 for colour removal and COD removal of Methyl Orange were R2= 0.9976 and R2= 0.9924 which suggested a good fit of the first-order regression model with the experimental data.

Biphasic cultivation strategy to avoid Epo-Fc aggregation and optimize protein expression.

PubMed

Kaisermayer, Christian; Reinhart, David; Gili, Andreas; Chang, Martina; Aberg, Per-Mikael; Castan, Andreas; Kunert, Renate

2016-06-10

In biphasic cultivations, the culture conditions are initially kept at an optimum for rapid cell growth and biomass accumulation. In the second phase, the culture is shifted to conditions ensuring maximum specific protein production and the protein quality required. The influence of specific culture parameters is cell line dependent and their impact on product quality needs to be investigated. In this study, a biphasic cultivation strategy for a Chinese hamster ovary (CHO) cell line expressing an erythropoietin fusion protein (Epo-Fc) was developed. Cultures were run in batch mode and after an initial growth phase, cultivation temperature and pH were shifted. Applying a DoE (Design of Experiments) approach, a fractional factorial design was used to systematically evaluate the influence of cultivation temperature and pH as well as their synergistic effect on cell growth as well as on recombinant protein production and aggregation. All three responses were influenced by the cultivation temperature. Additionally, an interaction between pH and temperature was found to be related to protein aggregation. Compared with the initial standard conditions of 37°C and pH 7.05, a parameter shift to low temperature and acidic pH resulted in a decrease in the aggregate fraction from 75% to less than 1%. Furthermore, the synergistic effect of temperature and pH substantially lowered the cell-specific rates of glucose and glutamine consumption as well as lactate and ammonium production. The optimized culture conditions also led to an increase of the cell-specific rates of recombinant Epo-Fc production, thus resulting in a more economic bioprocess. Copyright © 2016. Published by Elsevier B.V.

Destabilization and Treatment of Emulsified Oils in Wastewaters by Electrocoagulation.

PubMed

Genc, Ayten; Bakirci, Busra

2016-11-01

  In this study, the optimum operating conditions for the treatment of emulsified oils by electrocoagulation were determined depending on droplet stability analysis. Zeta potential measurements were used as the indication of oil droplet charges. In addition, the effects of pH and ionic conductivity on the droplet sizes and surface charges were investigated. The studied emulsified oil droplet sizes were more sensitive to changes in pH rather than salt concentration. The droplets became larger and unstable in alkaline conditions. As the initial pH of wastewaters increased, the oil removal efficiency increased during the electrocoagulation experiments as well. The use of iron or aluminum electrodes resulted in higher removal efficiencies in comparison to stainless steel electrodes. In addition, the energy consumption for aluminum electrodes was much lower than iron electrodes. To obtain 98% oil removal efficiency, distance between the electrodes was recommended to be less than or equal to 1 cm.

Denitrification using a monopolar electrocoagulation/flotation (ECF) process.

PubMed

Emamjomeh, Mohammad M; Sivakumar, Muttucumaru

2009-01-01

Nitrate levels are limited due to health concerns in potable water. Nitrate is a common contaminant in water supplies, and especially prevalent in surface water supplies and shallow wells. Nitrate is a stable and highly soluble ion with low potential for precipitation or adsorption. These properties make it difficult to remove using conventional water treatment methods. A laboratory batch electrocoagulation/flotation (ECF) reactor was designed to investigate the effects of different parameters such as electrolysis time, electrolyte pH, initial nitrate concentration, and current rate on the nitrate removal efficiency. The optimum nitrate removal was observed at a pH range of between 9 and 11. It appeared that the nitrate removal rate was 93% when the initial nitrate concentration and electrolysis time respectively were 100 mg L(-1)-NO(3)(-) and 40 min. The results showed a linear relationship between the electrolysis time for total nitrate removal and the initial nitrate concentration. It is concluded that the electrocoagulation technology for denitrification can be an effective preliminary process when the ammonia byproduct must be effectively removed by the treatment facilities.

Somatic embryogenesis of carrot in hormone-free medium: external pH control over morphogenesis

NASA Technical Reports Server (NTRS)

Smith, D. L.; Krikorian, A. D.

1990-01-01

Cultures of preglobular stage proembryos (PGSPs) were initiated from mechanically wounded mature zygotic embryos of carrot, Daucus carota, on a hormone-free, semisolid medium. These PGSPs have been maintained and multiplied for extended periods without their progression into later embryo stages on the same hormone-free medium containing 1 mM NH4+ as the sole nitrogen source. Sustained maintenance of cultures comprised exclusively of PGSPs was dependent on medium pH throughout the culture period. Best growth and multiplication of PGSP cultures occurred when the pH of unbuffered, hormone-free medium fell from 4.5 to 4 over a 2-week period or when buffered medium was titrated to pH 4. If the hormone-free medium was buffered to sustain a pH at or above 4.5, PGSPs developed into later embryo stages. Maintenance with continuous multiplication of PGSPs occurred equally well on medium containing NH4+ or NH4+ and NO3-, but growth was poor with NO3- alone. Additional observations on the effects of medium components such as various nitrogen sources and levels, sucrose concentration, semisolid supports, type of buffer, borate concentration, activated charcoal, and initial pH that permit optimum maintenance of the PGSPs or foster their continued developmental progression into mature embryos and plantlets are reported. The influence of the pH of the hormone-free medium as a determinant in maintaining cultures as PGSPs or allowing their continued embryonic development are unequivocally demonstrated by gross morphology, scanning electron microscopy, and histological preparations.

Biosorption of Congo Red from aqueous solution onto burned root of Eichhornia crassipes biomass

NASA Astrophysics Data System (ADS)

Roy, Tapas Kumar; Mondal, Naba Kumar

2017-07-01

Biosorption is becoming a promising alternative to replace or supplement the present dye removal processes from dye containing waste water. In this work, adsorption of Congo Red (CR) from aqueous solution on burned root of Eichhornia crassipes ( BREC) biomass was investigated. A series of batch experiments were performed utilizing BREC biomass to remove CR dye from aqueous systems. Under optimized batch conditions, the BREC could remove up to 94.35 % of CR from waste water. The effects of operating parameters such as initial concentration, pH, adsorbent dose and contact time on the adsorption of CR were analyzed using response surface methodology. The proposed quadratic model for central composite design fitted very well to the experimental data. Response surface plots were used to determine the interaction effects of main factors and optimum conditions of the process. The optimum adsorption conditions were found to be initial CR concentration = 5 mg/L-1, pH = 7, adsorbent dose = 0.125 g and contact time = 45 min. The experimental isotherms data were analyzed using Langmuir, Freundlich, Temkin and Dubinin-Radushkevich (D-R) isotherm equations and the results indicated that the Freundlich isotherm showed a better fit for CR adsorption. Thermodynamic parameters were calculated from Van't Hoff plot, confirming that the adsorption process was spontaneous and exothermic. The high CR adsorptive removal ability and regeneration efficiency of this adsorbent suggest its applicability in industrial/household systems and data generated would help in further upscaling of the adsorption process.

Heavy metal removal from waste waters by ion flotation.

PubMed

Polat, H; Erdogan, D

2007-09-05

Flotation studies were carried out to investigate the removal of heavy metals such as copper (II), zinc (II), chromium (III) and silver (I) from waste waters. Various parameters such as pH, collector and frother concentrations and airflow rate were tested to determine the optimum flotation conditions. Sodium dodecyl sulfate and hexadecyltrimethyl ammonium bromide were used as collectors. Ethanol and methyl isobutyl carbinol (MIBC) were used as frothers. Metal removal reached about 74% under optimum conditions at low pH. At basic pH it became as high as 90%, probably due to the contribution from the flotation of metal precipitates.

Improvement of the optimum pH of Aspergillus niger xylanase towards an alkaline pH by site-directed mutagenesis.

PubMed

Li, Fei; Xie, Jingcong; Zhang, Xuesong; Zhao, Linguo

2015-01-01

In an attempt to shift the optimal pH of the xylanase B (XynB) from Aspergillus niger towards alkalinity, target mutation sites were selected by alignment between Aspergillus niger xylanase B and other xylanases that have alkalophilic pH optima that highlight charged residues in the eight-residues-longer loop in the alkalophilic xylanase. Multiple engineered XynB mutants were created by site-directed mutagenesis with substitutions Q164K and Q164K+D117N. The variant XynB-117 had the highest optimum pH (at 5.5), which corresponded to a basic 0.5 pH unit shift when compared with the wild-type enzyme. However, the optimal pH of the XynB- 164 mutation was not changed, similar to the wild type. These results suggest that the residues at positions 164 and 117 in the eight-residues-longer loop and the cleft's edge are important in determining the pH optima of XynB from Aspergillus niger.

Kinetic degradation of guar gum in oilfield wastewater by photo-Fenton process.

PubMed

Wang, Shunwu; Li, Ziwang; Yu, Qinglong

2017-01-01

Guar gum is considered as a main component of oilfield wastewater. This work is intended to optimize the experimental conditions (H 2 O 2 dosage, Fe 2+ dosage, initial concentration of organics, initial pH and temperature) for the maximum oxidative degradation of guar gum by Fenton's reagent. The kinetics of guar gum removal were evaluated by means of the chemical oxygen demand (COD) and the absorbance measurements. The batch experiment results showed that the optimum conditions were: H 2 O 2 dosage, 10,000 mg/L; Fe 2+ dosage, 2,000 mg/L; initial concentration of organics, 413 mg/L; pH, 3 and temperature, 35 °C, under which the COD removal could reach 61.07% and fairly good stability could be obtained. Under the optimum experimental conditions, using UV irradiation to treat the wastewater, the photo-Fenton systems can successfully eliminate COD from guar gum solution. The COD removal always obeyed a pseudo-first-order kinetics and the degradation rate (k app ) was increased by 25.7% in the photo-Fenton process compared to the Fenton process. The photo-Fenton system needed less time and consequently less quantity of H 2 O 2 to obtain the same results as the Fenton process. The photo-Fenton process needs a dose of H 2 O 2 20.46% lower than that used in the Fenton process to remove 79.54% of COD. The cost of the photo/Fenton process amounted to RMB9.43/m 3 , which was lower than that of the classic Fenton process alone (RMB10.58/m 3 ) and the overall water quality of the final effluent could meet the class Ι national wastewater discharge standard for the petrochemical industry of China.

Mode of de-esterification of alkaline and acidic pectin methyl esterases at different pH conditions.

PubMed

Duvetter, Thomas; Fraeye, Ilse; Sila, Daniel N; Verlent, Isabel; Smout, Chantal; Hendrickx, Marc; Van Loey, Ann

2006-10-04

Highly esterified citrus pectin was de-esterified at pH 4.5 and 8.0 by a fungal pectin methyl esterase (PME) that was shown to have an acidic isoelectric pH (pI) and an acidic pH optimum and by a plant PME that was characterized by an alkaline pI and an alkaline pH optimum. Interchain and intrachain de-esterification patterns were studied by digestion of the pectin products with endo-polygalacturonase and subsequent analysis using size exclusion and anion-exchange chromatography. No effect of pH was observed on the de-esterification mode of either of the two enzymes. Acidic, fungal PME converted pectin according to a multiple-chain mechanism, with a limited degree of multiple attack at the intrachain level, both at pH 4.5 and at pH 8.0. A multiple-attack mechanism, with a high degree of multiple attack, was more appropriate to describe the action mode of alkaline, plant PME, both at pH 4.5 and at pH 8.0.

The removal of As(III) and As(V) from aqueous solutions by waste materials.

PubMed

Rahaman, M S; Basu, A; Islam, M R

2008-05-01

The use of different waste materials such as Atlantic Cod fish scale, chicken fat, coconut fibre and charcoal in removing arsenic [As(III) and As(V)] from aqueous solutions was investigated. Initial experimental runs, conducted for both As(III) and As(V) with the aforementioned materials, demonstrated the potential of using Atlantic Cod fish scale in removing both species of arsenic from aqueous streams. Therefore, the biosorbent fish scale was selected for further investigations and various parameters such as residence time, adsorbent dose, initial concentration of adsorbate, grain size of the adsorbent and pH of the bulk phase were studied to establish optimum conditions. The maximum adsorption capacity was observed at pH value 4.0. The equilibrium adsorption data were interpreted by using both Freundlich and Langmuir models. Rapid small-scale column tests (RSSCT) were also performed to determine the breakthrough characteristics of the arsenic species with respect to packed biosorbent columns.

Preparation and biosorption evaluation of Bacillus subtilis/alginate–chitosan microcapsule

PubMed Central

Tong, Ke

2017-01-01

The aim of this study was to assess the effect of alginate–chitosan microcapsule on viability characteristics of Bacillus subtilis and the ability of B. subtilis/alginate–chitosan microcapsule to remove uranium ion from aqueous solution. The effects of particle size, chitosan molecular weight and inoculum density on viability characteristics were studied using alginate–chitosan microcapsule-immobilized B. subtilis experiments. In addition, the effects of pH, immobilized spherule dosage, temperature, initial uranium ion concentration and contact time on removal of uranium ion were studied using batch adsorption experiments. The results showed that alginate–chitosan microcapsule significantly improved the viability characteristics of B. subtilis and that B. subtilis/alginate–chitosan microcapsule strongly promoted uranium ion absorption. Moreover, the optimum values of pH was 6; immobilized spherule dosage was 3.5; temperature was 20°C; initial uranium ion concentration was 150 mg/L; contact time was 3 h of uranium ion absorption and the maximum adsorption capacity of uranium ion was 376.64 mg/g. PMID:28223783

Statistical analysis and isotherm study of uranium biosorption by Padina sp. algae biomass.

PubMed

Khani, Mohammad Hassan

2011-06-01

The application of response surface methodology is presented for optimizing the removal of U ions from aqueous solutions using Padina sp., a brown marine algal biomass. Box-Wilson central composite design was employed to assess individual and interactive effects of the four main parameters (pH and initial uranium concentration in solutions, contact time and temperature) on uranium uptake. Response surface analysis showed that the data were adequately fitted to second-order polynomial model. Analysis of variance showed a high coefficient of determination value (R (2)=0.9746) and satisfactory second-order regression model was derived. The optimum pH and initial uranium concentration in solutions, contact time and temperature were found to be 4.07, 778.48 mg/l, 74.31 min, and 37.47°C, respectively. Maximized uranium uptake was predicted and experimentally validated. The equilibrium data for biosorption of U onto the Padina sp. were well represented by the Langmuir isotherm, giving maximum monolayer adsorption capacity as high as 376.73 mg/g.

Removal of trivalent chromium from aqueous solution using aluminum oxide hydroxide.

PubMed

Bedemo, Agaje; Chandravanshi, Bhagwan Singh; Zewge, Feleke

2016-01-01

Water is second most essential for human being. Contamination of water makes it unsuitable for human consumption. Chromium ion is released to water bodies from various industries having high toxicity which affects the biota life in these waters. In this study aluminum oxide hydroxide was tested for its efficiency to remove trivalent chromium from aqueous solutions through batch mode experiments. Chromium concentrations in aqueous solutions and tannery waste water before and after adsorption experiments were determined using flame atomic absorption spectrometry. The effects of pH, contact time, initial concentration and adsorbent dosage on the adsorption of Cr(III) were studied. The study revealed that more than 99 % removal of Cr(III) was achieved over wide range of initial pH (3-10). The optimum conditions for the removal of Cr(III) were found to be at pH 4-6 with 40 g/L adsorbent dose at 60 min of contact time. The adsorption capacity was assessed using Langmuir and Freundlich isotherms. The equilibrium data at varying adsorbent dose obeyed the two isotherms. The adsorbent was found to be efficient for the removal of Cr(III) from tannery waste effluent.

Carbonic anhydrase from Camelia sinensis (tea) leaves.

PubMed

Demir, Y; Demir, N; Ağar, G

1997-11-01

Carbonic anhydrase (CA) (carbonate hydrolyase; E,C,4.2.1.1) from leaves of mature Camelia sinensis was purified and characterized. The purification level was 53 fold. The optimum temperature for maximal enzyme activity is 50 degrees C. The optimum pH was 6.8 and this pH varied between 6.5 and 7.5. Each enzyme molecule is a hexamer with an M(r) of 169,000 with subunits of M(r) = 28,000.

21 CFR 114.90 - Methodology.

Code of Federal Regulations, 2011 CFR

2011-04-01

... buffer. First standardize the electrodes using a pH 4.0 buffer at or near 25 °C. Standardization control..., the optimum being 25 °C. Any temperature determinations made without meter compensation may affect pH... approximately ±0.01 pH unit and a reproducibility of ±0.005 pH units. (4) General procedure for determining pH...

21 CFR 114.90 - Methodology.

Code of Federal Regulations, 2010 CFR

2010-04-01

... buffer. First standardize the electrodes using a pH 4.0 buffer at or near 25 °C. Standardization control..., the optimum being 25 °C. Any temperature determinations made without meter compensation may affect pH... approximately ±0.01 pH unit and a reproducibility of ±0.005 pH units. (4) General procedure for determining pH...

A critical study on efficiency of different materials for fluoride removal from aqueous media

PubMed Central

2013-01-01

Fluoride is a persistent and non-biodegradable pollutant that accumulates in soil, plants, wildlife and in human beings. Therefore, knowledge of its removal, using best technique with optimum efficiency is needed. The present survey highlights on efficacy of different materials for the removal of fluoride from water. The most important results of extensive studies on various key factors (pH, agitation time, initial fluoride concentration, temperature, particle size, surface area, presence and nature of counter ions and solvent dose) fluctuate fluoride removal capacity of materials are reviewed. PMID:23497619

Xylanase production by a newly isolated Aspergillus niger SS7 in submerged culture.

PubMed

Bakri, Yasser; Al-Jazairi, Manal; Al-Kayat, Ghassan

2008-01-01

Xylanase production by a newly isolated Aspergillus niger SS7 was studied in submerged culture. The optimum initial pH for xylanase production was found to be 7.0. Different agricultural and industrial wastes were evaluated for their ability to induce xylanase production by this isolate. The best xylanase production (293.82 IU/ml) was recorded at 3% (w/v) corn cob hulls after 120 h of incubation. The Aspergillus niger SS7 isolate grown in a simple medium, proved to be a promising microorganism for xylanase production.

Structural insights into the recovery of aldolase activity in N-acetylneuraminic acid lyase by replacement of the catalytically active lysine with γ-thialysine by using a chemical mutagenesis strategy.

PubMed

Timms, Nicole; Windle, Claire L; Polyakova, Anna; Ault, James R; Trinh, Chi H; Pearson, Arwen R; Nelson, Adam; Berry, Alan

2013-03-04

Chemical modification has been used to introduce the unnatural amino acid γ-thialysine in place of the catalytically important Lys165 in the enzyme N-acetylneuraminic acid lyase (NAL). The Staphylococcus aureus nanA gene, encoding NAL, was cloned and expressed in E. coli. The protein, purified in high yield, has all the properties expected of a class I NAL. The S. aureus NAL which contains no natural cysteine residues was subjected to site-directed mutagenesis to introduce a cysteine in place of Lys165 in the enzyme active site. Subsequently chemical mutagenesis completely converted the cysteine into γ-thialysine through dehydroalanine (Dha) as demonstrated by ESI-MS. Initial kinetic characterisation showed that the protein containing γ-thialysine regained 17 % of the wild-type activity. To understand the reason for this lower activity, we solved X-ray crystal structures of the wild-type S. aureus NAL, both in the absence of, and in complex with, pyruvate. We also report the structures of the K165C variant, and the K165-γ-thialysine enzyme in the presence, or absence, of pyruvate. These structures reveal that γ-thialysine in NAL is an excellent structural mimic of lysine. Measurement of the pH-activity profile of the thialysine modified enzyme revealed that its pH optimum is shifted from 7.4 to 6.8. At its optimum pH, the thialysine-containing enzyme showed almost 30 % of the activity of the wild-type enzyme at its pH optimum. The lowered activity and altered pH profile of the unnatural amino acid-containing enzyme can be rationalised by imbalances of the ionisation states of residues within the active site when the pK(a) of the residue at position 165 is perturbed by replacement with γ-thialysine. The results reveal the utility of chemical mutagenesis for the modification of enzyme active sites and the exquisite sensitivity of catalysis to the local structural and electrostatic environment in NAL. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis and adsorption of silica gel modified 3-aminopropyltriethoxysilane (APTS) from corn cobs against Cu(II) in water

NASA Astrophysics Data System (ADS)

Purwanto, Agung; Yusmaniar, Ferdiani, Fatmawati; Damayanti, Rachma

2017-03-01

Silica gel modified APTS was synthesized from silica gel which was obtained from corn cobs via sol-gel process. Silica gel was synthesized from corn cobs and then chemically modified with silane coupling agent which has an amine group (NH2). This process resulting modified silica gel 3-aminopropyltriethoxysilane (APTS). Characterization of silica gel modified APTS by SEM-EDX showed that the size of the particles of silica gel modified APTS was 20µm with mass percentage of individual elements were nitrogen (N) 15.56%, silicon (Si) 50.69% and oxygen (O) 33.75%. In addition, silica gel modified APTS also showed absorption bands of functional groups silanol (Si-OH), siloxane (Si-O-Si), and an aliphatic chain (-CH2-), as well as amine (NH2) from FTIR spectra. Based on the characterization of XRD, silica gel 2θ of 21.094° and 21.32° respectively. It indicated that both material were amorphous. Determination of optimum pH and contact time on adsorption of silica gel 3-aminopropyltriethoxysilane (APTS) against Cu(II). The optimum pH and contact time was measured by using AAS. Optimum pH of adsorption silica gel modified APTS against metal Cu(II) could be obtained at pH 6 while optimum contact time was at 30 minutes, with the process of adsorption metal Cu(II) occured based on the model Freundlich isotherm.

Study the adsorption of sulfates by high cross-linked polystyrene divinylbenzene anion-exchange resin

NASA Astrophysics Data System (ADS)

Fathy, Mahmoud; Moghny, Th. Abdel; Awadallah, Ahmed E.; El-Bellihi, Abdel-Hameed A.-A.

2017-03-01

In response to rising concerns about the effect of sulfate on water quality, human health, and agriculture, many jurisdictions around the world are imposing tighter regulations for sulfate discharge. This is driving the need for environmental compliance in industries like mining, metal processing, pulp and paper, sewage treatment, and chemical manufacturing. The sulfate removal from synthetic water by high cross-linked polystyrene divinylbenzene resin was studied at batch experiments in this study. The effect of pH, contact time, sulfates concentration, and adsorbent dose on the sulfate sequestration was investigated. The optimum conditions were studied on Saline water as a case study. The results showed that with increasing of the absorbent amount; contact time, and pH improve the efficiency of sulfate removal. The maximum sulfates uptake was obtained in pH and contact time 3.0 and 120 min, respectively. Also, with increasing initial concentration of sulfates in water, the efficiency of sulfate removal decreased. The obtained results in this study were matched with Freundlich isotherm and pseudo-second-order kinetic. The maximum adsorption capacity (Qm) and constant rate were found 0.318 (mg/g) and 0.21 (mg/g.min), respectively. This study also showed that in the optimum conditions, the sulfate removal efficiency from Saline water by 0.1 mg/L sulfates was 65.64 %. Eventually, high cross-linked polystyrene divinylbenzene resin is recommended as a suitable and low cost absorbent to sulfate removal from aqueous solutions.

Adsorption of Crystal Violet Dye Using Zeolite A Synthesized From Coal Fly Ash

NASA Astrophysics Data System (ADS)

Jumaeri; Kusumastuti, E.; Santosa, S. J.; Sutarno

2017-02-01

Adsorption of Crystal Violet (CV) dye using zeolite A synthesized from coal fly ash (ZA) has been done. Effect of pH, contact time, and the initial concentration of dye adsorption was studied in this adsorption. Model experimental of adsorption isotherms and adsorption kinetics were also studied. The adsorption is done in a batch reactor at room temperature. A total of 0.01 g of zeolite A was added to the Erlenmeyer flask 50 mL containing 20 mL of the dye solution of Crystal Violet in a variety of conditions of pH, contact time and initial concentration. Furthermore, Erlenmeyer flask and its contents were shaken using an orbital shaker at a speed of 200 rpm. After a specified period of adsorption, the solution was centrifuged for 2 minutes so that the solids separated from the solution. The concentration of the dye after adsorption determined using Genesis-20 Spectrophotometer. The results showed that the Zeolite A synthesized from coal fly ash could be used as an effective adsorbent for Crystal Violet dye. The optimum adsorption occurs at pH 6, and contact time 45 minutes. At the initial concentration of 2 to 6 mg/L, adsorption is reduced from 79 to 62.8%. Crystal Violet dye adsorption in zeolite A fulfilled kinetic model of pseudo-order 2 and model of Freundlich adsorption isotherm.

Preliminary study on biosynthesis and characterization of bacteria cellulose films from coconut water

NASA Astrophysics Data System (ADS)

Indrianingsih, A. W.; Rosyida, V. T.; Jatmiko, T. H.; Prasetyo, D. J.; Poeloengasih, C. D.; Apriyana, W.; Nisa, K.; Nurhayati, S.; Hernawan; Darsih, C.; Pratiwi, D.; Suwanto, A.; Ratih, D.

2017-12-01

Bacterial cellulose produced by Acetobacter xylinum is a unique type of bacterial cellulose. It contains more than 90% of water. A preliminary study had shown that bacterial cellulose films has remarkable mechanical properties. The aim of this study was to investigate the optimum condition such as percentage of carbon source, time of cultivation, and pH to produce bacterial cellulose films from local coconut water, and its characterization on morphology, swelling ability and tensile strength of dried bacterial cellulose. A. xylinum was grown on coconut water culture medium with addition of 3%, 5%, and 7% of sugar, while the cultivation time was vary from 3 days, 5 days and 7 days. pH condition was conducted in pH 3, pH 5 and pH 7. Bacterial cellulose samples were dried using oven with temperature of 100°C until the moisture content reached 4-5%. This study showed that several parameters for optimum condition to produce bacterial cellulose films from local waste of coconut water had been obtained (5% of carbon source; pH 5; and 7 day of incubation period). The electron microscopy also showed that dried bacterial cellulose films had pores covered by fibrils on the surface. Therefore, the present work proposes the optimum formula and condition that can be used based on properties of end product needed.

Treatment and resource recovery from inorganic fluoride-containing waste produced by the pesticide industry.

PubMed

Li, Yang; Zhang, Hua; Zhang, Zhiqi; Shao, Liming; He, Pinjing

2015-05-01

The rapid development of the fluorinated pesticide industry has produced a large amount of fluorine-containing hazardous waste, especially inorganic fluoride-containing waste (IFCW). A two-step process, including extraction and recovery, was developed to recover fluorine as synthetic cryolite from IFCW produced by the pesticide industry. The optimum conditions for extraction were found to be a temperature of 75°C, an initial pH (pHi) of 12, a 4-hr incubation time and a liquid-to-solid ratio of 40mL/g; these conditions resulted in a fluorine extraction ratio of 99.0%. The effects of pH and the F/Al molar ratio on fluorine recovery and the compositional, mineralogical and morphological characteristics of the cryolite products were investigated. Field-emission scanning electron microscopy of recovered precipitates showed changes in morphology with the F/Al molar ratio. Coupling Fourier transform and infrared spectroscopy, X-ray diffraction indicated that the formation of AlF6(3-) was restricted as increasing pH. Both the amount of fluorine recovered and the quality of the cryolite were optimized at initial pH=3 and a F/Al molar ratio 5.75. This study proposed a reliable and environmentally friendly method for the treatment of fluoride-containing wastes, which could be suitable for industrial applications. Copyright © 2015. Published by Elsevier B.V.

Influence of pH on Cr(VI) ions removal from aqueous solutions using carboxymethyl cellulose-based hydrogel as adsorbent

NASA Astrophysics Data System (ADS)

Anah, L.; Astrini, N.

2017-03-01

The major problem in heavy metal pollution is that these metals are not biodegradable and accordingly accumulate in the bodies of living organisms, causing dangerous diseases and serious cell disorder. According to World Health Organization (WHO), the long term exposure of Cr(VI) levels of over 0.1 ppm causes respiratory problems, liver and kidney damage, and carcinogenicity.Due to its easy operation and of various cheap adsorbents development, adsorption has been proved to be efficient and most economically attractive technique and feasible to the removal of toxic heavy metal from wastewater. The study aimed to report the removal of Cr(VI) ions from aqueous solutions through adsorption process using carboxymethyl cellulose-graft-poly(acrylic acid) (CMC-g-PAA) hydrogel as adsorbent.Effect of pH was studied to remove hexavalent chromium.Graft copolymerization of poly(acrylic acid) onto carboxymethyl cellulose was carried out in the presence of benzoyl peroxide redox initiator and methylenbisacrylamide as crosslinker agent. Batch experiments were carried out to investigate the effects ofinitial pH.The adsorption of Cr(VI) ions as a function of pH was conducted in the initial pH range of 1 to 8. The results indicated that acidic pH strongly favored the adsorption. The optimum pH for adsorption of Cr(VI) ranged from 1 to 3, and the maximum uptake of Cr(VI) from the solution was 6.53 mg/g at pH 1 and 30°C. FTIR spectroscopy, SEM analyses were performed on the adsorbent before and after Cr(VI) binding. All analyses confirmed the complexation of Cr(VI) ions on the adsorbent.

Studies on Batch Production of Bacterial Concentrates from Mixed Species Lactic Starters

PubMed Central

Pettersson, H. E.

1975-01-01

Optimum growth conditions for mixed species starter FDs 0172 at constant pH in skim milk, whey, and tryptone medium were investigated. Growth rate and maximum population were optimal at 30 C. pH values between 5.5 and 7.0 did not influence the growth rate and maximum population obtainable. Lactic acid-producing activity declined rapidly after reaching the end of the exponential growth phase. The bacterial balance was found to be influenced by the growth parameters: media, pH, temperature, and neutralizer. Skim milk or whey medium at 25 C, pH 6.5, and neutralized with 20% (vol/vol) NH4OH kept the bacterial balance almost constant throughout the cultivation. Grown in tryptone medium at constant pH, the changes in bacterial balance and other metabolic activities were striking compared to the other two media tested. The effect of lactate as an inhibitor was found to be complex, changing with the growth conditions. Concentrates made from mixed species starters FDs 0172, FD 0570, CH 0170, CHs 0170, and T 27 were comparable to controls when cultivated at the optimum conditions found and thereafter centrifuged. Aroma production, proteolytic activity, and CO2 production did not change significantly compared to controls when cultivated at optimum conditions in skim milk or whey medium. PMID:16350009

Proteolytic Activity at Alkaline pH in Oat Leaves, Isolation of an Aminopeptidase 1

PubMed Central

Casano, Leonardo M.; Desimone, Marcelo; Trippi, Victorio S.

1989-01-01

Proteolytic activity in oat leaf extracts was measured with both azocasein and ribulose bisphosphate carboxylase (Rubisco) as substrates over a wide range of pH (3.0-9.2). With either azocasein or Rubisco activity peaks appeared at pH 4.8, 6.6, and 8.4. An aminopeptidase (AP) which hydrolyzes leucine-nitroanilide was partially purified. Purification consisted of a series of six steps which included ammonium sulfate precipitation, gel filtration, and two ionic exchange chromatographies. The enzyme was purified more than 100-fold. The apparent Km for leucine-nitroanilide is 0.08 millimolar at its pH optimum of 8.4. AP may be a cystein protease since it is inhibited by heavy metals and activated by 2-mercaptoethanol. Isolated chloroplasts were also able to hydrolyze leucine-nitroanilide at a pH optimum of 8.4, indicating that AP could be localized inside the photosynthetic organelles. PMID:16667194

Adsorptive removal of microcystin-LR from surface and wastewater using tyre-based powdered activated carbon: Kinetics and isotherms.

PubMed

Mashile, Phodiso P; Mpupa, Anele; Nomngongo, Philiswa N

2018-04-01

Microcystin LR (MC-LR) is a highly toxic compound and it is known for its adverse health effect on both humans and animals. Due to the ineffectiveness of conventional water treatments methods, for the past decades, researchers have been developing cost-effective ways of removing MC-LR from water bodies. This study reports the application of powdered activated carbon (PAC) obtained from the waste tyre for the removal of MC-LR. The choice of the adsorbent was chosen due to its attractive properties. The prepared tyre-based PAC was found to have the large surface area (1111 m 2  g -1 ). The detection of MC-LR was achieved using high performance liquid chromatography (HPLC) coupled with a PDA detector. The experimental parameters (such as optimum pH, dosage and contact time) affecting the removal of MC-LR using tyre based-powdered activated carbon were optimized using response surface methodology (RSM). Maximum removal of MC-LR was achieved under the following optimum conditions; sample pH 4, carbon dosage concentration 10,000 mg L -1 and contact time of 34 min. Under optimum conditions, kinetic studies and adsorption isotherms reflected better fit for pseudo-second-order rate and Langmuir isotherm model, respectively. The optimized method was applied for the removal of MC-LR in wastewater sample. The effluent and influent sample contained initial concentrations ranging from 0.52 to 8.54 μg L -1 and the removal efficiency was 100%. Copyright © 2018 Elsevier Ltd. All rights reserved.

Stretch-induced, steady-state force enhancement in single skeletal muscle fibers exceeds the isometric force at optimum fiber length.

PubMed

Rassier, Dilson E; Herzog, Walter; Wakeling, Jennifer; Syme, Douglas A

2003-09-01

Stretch-induced force enhancement has been observed in a variety of muscle preparations and on structural levels ranging from single fibers to in vivo human muscles. It is a well-accepted property of skeletal muscle. However, the mechanism causing force enhancement has not been elucidated, although the sarcomere-length non-uniformity theory has received wide support. The purpose of this paper was to re-investigate stretch-induced force enhancement in frog single fibers by testing specific hypotheses arising from the sarcomere-length non-uniformity theory. Single fibers dissected from frog tibialis anterior (TA) and lumbricals (n=12 and 22, respectively) were mounted in an experimental chamber with physiological Ringer's solution (pH=7.5) between a force transducer and a servomotor length controller. The tetantic force-length relationship was determined. Isometric reference forces were determined at optimum length (corresponding to the maximal, active, isometric force), and at the initial and final lengths of the stretch experiments. Stretch experiments were performed on the descending limb of the force-length relationship after maximal tetanic force was reached. Stretches of 2.5-10% (TA) and 5-15% lumbricals of fiber length were performed at 0.1-1.5 fiber lengths/s. The stretch-induced, steady-state, active isometric force was always equal or greater than the purely isometric force at the muscle length from which the stretch was initiated. Moreover, for stretches of 5% fiber length or greater, and initiated near the optimum length of the fiber, the stretch-enhanced active force always exceeded the maximal active isometric force at optimum length. Finally, we observed a stretch-induced enhancement of passive force. We conclude from these results that the sarcomere length non-uniformity theory alone cannot explain the observed force enhancement, and that part of the force enhancement is associated with a passive force that is substantially greater after active compared to passive muscle stretch.

Effect of direct electric current on contaminants removal from the peat water with continuous system

NASA Astrophysics Data System (ADS)

Amri, I.; Azis, A.; Drastinawati

2018-04-01

This research was analysed the essentially of treat peat water using an electric current. Initially, the characterization of peat water was determined including of three parameters they are pH, colour, and conductivity solution exhibited values that exceeded the water standard limit. There are two factors influencing the electric coagulation such as electric current and voltage that were observed in the continous study. The results obtained indicated that the majority of the an electric current were very effective for removing TDS, and pH. The research variable for the voltage from 23,5 to 42,5 volt and the electric current from 2,2 to 4,1. The optimum electric current and voltage was found around 1,5 Ampere and 25 volt, it was exhibited at 4 L/minute. In unit study, continous electric reactor showed that the optimal reduction on the 20 minutes treatment were found pH = 7, 256 ppm. It was meet to the minimum standard government permition.

Assessment of coagulation pretreatment of leachate by response surface methodology.

PubMed

Lessoued, Ridha; Souahi, Fatiha; Castrillon Pelaez, Leonor

2017-11-01

Coagulation-flocculation is a relatively simple technique that can be used successfully for the treatment of old leachate by poly-aluminum chloride (PAC). The main objectives of this study are to design the experiments, build models and optimize the operating parameters, dosage m and pH, using the central composite design and response surface method. Developed for chemical organic matter (COD) and turbidity responses, the quadratic polynomial model is suitable for prediction within the range of simulated variables as it showed that the optimum conditions were m of 5.55 g/L at pH 7.05, with a determination coefficient R² at 99.33%, 99.92% and adjusted R² at 98.85% and 99.86% for both COD and turbidity. We confirm that the initial pH and PAC dosage have significant effects on COD and turbidity removal. The experimental data and model predictions agreed well and the removal efficiency of COD, turbidity, Fe, Pb and Cu reached respectively 61%, 96.4%, 97.1%, 99% and 100%.

Optimisation of medium composition for probiotic biomass production using response surface methodology.

PubMed

Anvari, Masumeh; Khayati, Gholam; Rostami, Shora

2014-02-01

This study was aimed to optimise lactose, inulin and yeast extract concentration and also culture pH for maximising the growth of a probiotic bacterium, Bifidobacterium animalis subsp. lactis in apple juice and to assess the effects of these factors by using response surface methodology. A second-order central composite design was applied to evaluate the effects of these independent variables on growth of the microorganism. A polynomial regression model with cubic and quadratic terms was used for analysis of the experimental data. It was found that the effects involving inulin, yeast extract and pH on growth of the bacterium were significant, and the strongest effect was given by the yeast extract concentration. Estimated optimum conditions of the factors on the bacterial growth are as follows: lactose concentration=9·5 g/l; inulin concentration=38·5 mg/l; yeast extract concentration=9·6 g/l and initial pH=6·2.

Encapsulation and release studies of strawberry polyphenols in biodegradable chitosan nanoformulation.

PubMed

Pulicharla, Rama; Marques, Caroline; Das, Ratul Kumar; Rouissi, Tarek; Brar, Satinder Kaur

2016-07-01

Polyphenols (negative groups) of strawberry extract interacts with positively protonated amino groups of chitosan which helps in maximum encapsulation. This approach can improve the bioavailability and sustained release of phytochemicals having lower bioavailability. The optimum mass ratio of chitosan-tripolyphosphate and polyphenols (PPs) loading was investigated to be 3:1 and 0.5mg/ml of strawberry extract, respectively. Prepared nanoformulation were characterized by UV-vis spectroscopy, Fourier transform infrared spectroscopy and scanning electron microscopy. The formed particles size ranged between 300 and 600nm and polydispersity index (PDI) of≈0.5. The optimized formulation showed encapsulation efficiency of 58.09% at 36.47% of polyphenols loading. Initial burst and continuous release of PPs was observed at pH 7.4 of in vitro release studies. PPs release profile at this pH was found to be non-Fickian analomous diffusion and the release was followed first order kinetics. And at pH 1.4, diffusion-controlled Fickian release of PPs was observed. Copyright © 2016 Elsevier B.V. All rights reserved.

Efficacy and reusability of alginate-immobilized live and heat-inactivated Trichoderma asperellum cells for Cu (II) removal from aqueous solution.

PubMed

Tan, Wei Shang; Ting, Adeline Su Yien

2012-11-01

Cu(II) removal efficacies of alginate-immobilized Trichoderma asperellum using viable and non-viable forms were investigated with respect to time, pH, and initial Cu(II) concentrations. The reusability potential of the biomass was determined based on sorption/desorption tests. Cu(II) biosorption by immobilized heat-inactivated T. asperellum cells was the most efficient, with 134.22mg Cu(II) removed g(-1) adsorbent, compared to immobilized viable cells and plain alginate beads (control) with 105.96 and 94.04mg Cu(II) adsorbed g(-1) adsorbent, respectively. Immobilized non-viable cells achieved equilibrium more rapidly within 4h. For all biosorbents, optimum pH for Cu(II) removal was between pH 4 and 5. Reusability of all biosorbents were similar, with more than 90% Cu(II) desorbed with HCl. These alginate-immobilized cells can be applied to reduce clogging and post-separation process incurred from use of suspended biomass. Copyright © 2012 Elsevier Ltd. All rights reserved.

Factors Affecting Oxidation of Thiosalts by Thiobacilli

PubMed Central

Silver, M.; Dinardo, O.

1981-01-01

The effects of temperature, initial pH, and the concentrations of ammonium, phosphate, and heavy metals on the oxidation of thiosalts by an authentic strain of Thiobacillus thiooxidans (ATCC 8085) and by a mixed culture isolated from a base metal-processing mill effluent pond were studied. The optimum temperature was 30°C and the optimum initial pH was 3.75 for both cultures using thiosulfate and for the mixed culture using tetrathionate. T. thiooxidans ATCC 8085 did not oxidize tetrathionate. For a thiosalt concentration of 2,000 ppm (2,000 mg/liter), maximal rates of destruction occurred at concentrations of ammonium ion above 2 mg/liter and in the presence of 1 mg of phosphate per liter. Under optimal conditions, the rate of thiosulfate oxidation by the pure culture was 55 ± 3 mg/liter per h; the mixed culture oxidized thiosulfate at the rate of 40 ± 1 mg/liter per h and tetrathionate at the rate of 50 ± 2 mg/liter per h. Metal ions caused normal inhibition kinetics in the oxidation of thiosulfate by T. thiooxidans ATCC 8085. Ki values were calculated for cadmium (16 mg/liter), copper (0.46 mg/liter), lead (2 mg/liter), silver (3.1 mg/liter), and zinc (33 mg/liter). Only a slight additive effect was apparent in the presence of all of these metal ions. The mixed culture of thiosalt-oxidizing bacteria was less sensitive to heavy metal inhibition; the order of inhibition of thiosulfate oxidation was Cd < Zn < Pb < Ag < Cu, and that of tetrathionate oxidation was Zn < Cd < Pb < Ag < Cu. PMID:16345785

Production of ethanol and arabitol by Debaryomyces nepalensis: influence of process parameters

PubMed Central

2013-01-01

Debaryomyces nepalensis, osmotolerant yeast isolated from rotten apple, is known to utilize both hexoses and pentoses and produce industrially important metabolites like ethanol, xylitol and arabitol. In the present study, the effect of different growth substrates, trace elements, nitrogen concentration and initial pH on growth and formation of ethanol and arabitol were examined. Optimum conditions for maximizing the product yields were established: glucose as carbon source, an initial pH of 6.0, 6 g/L of ammonium sulphate and addition of micronutrients. Under these best suited conditions, a concentration of 11g/L of arabitol and 19 g/L of ethanol was obtained in shake flask fermentations. The fermentation was scaled up to 2.5 L bioreactor and the influence of aeration, agitation and initial substrate concentration was also determined. Under optimal conditions (150 g/L glucose, 400 rpm and 0.5 vvm) ethanol concentration reached 52 g/L, which corresponds to a yield of 0.34 g/g and volumetric productivity of 0.28 g/L/h, whereas arabitol production reached a maximum of 14 g/L with a yield and volumetric productivity of 0.1 g/g and 0.07 g/L/h respectively. PMID:23659479

Identification of Limiting Factors for the Optimum Growth of Fusarium Oxysporum in Liquid Medium

PubMed Central

Srivastava, Shilpi; Pathak, Neelam; Srivastava, Prachi

2011-01-01

Fusarium oxysporum is a highly ubiquitous species that infects a wide range of hosts causing various diseases such as vascular wilts, yellows, rots, and damping-off. Despite the immense economic significance of this phytopathogen, few workers have reported growth studies in this genus in submerged culture. In the present study, several parameters such as change in media pH, biomass, pattern of substrate utilization, viability of the fungal cells, and protein content were observed over a period of time. The fungal biomass increased at a slow rate for the initial 48 h and thereafter increased at an exponential rate. However, after about 8 days the rapid growth stabilized and the trend became more toward stationary phase. The concentration of glucose in the liquid media decreased rapidly up to the initial 4 days, followed by a slow decrease. The pH of the medium gradually decreased as the fungal growth progressed, the reduction being more pronounced in the initial 48 h. This study would be of immense importance for utilization of F. oxysporum for diverse applications because we can predict the growth pattern in the fungus and modulate its growth for human benefit. PMID:21976815

Formation of glycosidases in batch and continuous culture of Bacteroides fragilis.

PubMed Central

Berg, J O; Nord, C E; Wadström, T

1978-01-01

Nine strains of bacteroides fragilis were cultivated in stirred fermentors and tested for their ability to produce glycosidases. B. fragilis subsp. vulgatus B70 was used for optimizing the production of glycosidases. The highest bacterial yield was obtained in proteose peptone-yeast extract medium. The optimum pH for maximal bacterial yield was 7.0, and the optimum temperature for growth was 37 degrees C. The formation of glycosidases was optimal between pH 6.5 and 7.5, and the optimum temperature for synthesis of glycosidases was between 33 and 37 degrees C. Culture under controlled conditions in fermentors gave more reproducible production of glycosidases than static cultures in bottles. The strain was also grown in continuous culture at a dilution rate of 0.1 liter/h at pH 7.0 and 37 degrees C with a yield of 2.0 mg of dry weight per ml in the complex medium. The formation of glycosidases remained constant during the entire continuous process. PMID:25044

Kinetic and spectroscopic studies of the molybdenum-copper CO dehydrogenase from Oligotropha carboxidovorans.

PubMed

Zhang, Bo; Hemann, Craig F; Hille, Russ

2010-04-23

Carbon monoxide dehydrogenase from the aerobic bacterium Oligotropha carboxidovorans catalyzes the oxidation of CO to CO(2), yielding two electrons and two H(+). The steady-state kinetics of the enzyme exhibit a pH optimum of 7.2 with a k(cat) of 93.3 s(-1) and K(m) of 10.7 microM at 25 degrees C. k(red) for the reductive half-reaction agrees well with k(cat) and exhibits a similar pH optimum, indicating that the rate-limiting step of overall turnover is likely in the reductive half-reaction. No dependence on CO concentration was observed in the rapid reaction kinetics, however, suggesting that CO initially binds rapidly to the enzyme, possibly at the Cu(I) of the active site, prior to undergoing oxidation. A Mo(V) species that exhibits strong coupling to the copper of the active center (I = 3/2) has been characterized by EPR. The signal is further split when [(13)C]CO is used to generate it, demonstrating that substrate (or product) is a component of the signal-giving species. Finally, resonance Raman spectra of CODH reveal the presence of FAD, Fe/S clusters, and a [CuSMoO(2)] coordination in the active site, consistent with earlier x-ray absorption and crystallographic results.

Enhanced production of medicinal polysaccharide by submerged fermentation of Lingzhi or Reishi medicinal mushroom Ganoderma lucidium (W.Curt.:Fr.) P. Karst. Using statistical and evolutionary optimization methods.

PubMed

Baskar, Gurunathan; Sathya, Shree Rajesh K

2011-01-01

Statistical and evolutionary optimization of media composition was employed for the production of medicinal exopolysaccharide (EPS) by Lingzhi or Reishi medicinal mushroom Ganoderma lucidium MTCC 1039 using soya bean meal flour as low-cost substrate. Soya bean meal flour, ammonium chloride, glucose, and pH were identified as the most important variables for EPS yield using the two-level Plackett-Burman design and further optimized using the central composite design (CCD) and the artificial neural network (ANN)-linked genetic algorithm (GA). The high value of coefficient of determination of ANN (R² = 0.982) indicates that the ANN model was more accurate than the second-order polynomial model of CCD (R² = 0.91) for representing the effect of media composition on EPS yield. The predicted optimum media composition using ANN-linked GA was soybean meal flour 2.98%, glucose 3.26%, ammonium chloride 0.25%, and initial pH 7.5 for the maximum predicted EPS yield of 1005.55 mg/L. The experimental EPS yield obtained using the predicted optimum media composition was 1012.36 mg/L, which validates the high degree of accuracy of evolutionary optimization for enhanced production of EPS by submerged fermentation of G. lucidium.

Removal of malachite green dye from aqueous solution using mesoporous silica synthesized from 1-octyl-3-methylimidazolium chloride ionic liquid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ekka, Basanti; Nayak, Soumitra Ranjan; Dash, Priyabrat, E-mail: dashp@nitrkl.ac.in, E-mail: rkpatel@nitrkl.ac.in

2016-04-13

In this research, mesoporous silica was synthesized via a modified sol-gel route using 1-octyl-3-methylimidazolium chloride and was employed to remove malachite green (MG) dye from aqueous solution. Subsequently, this material was characterized and identified by different techniques such as Fourier transform infrared spectroscopy (FT-IR), N{sub 2} adsorption-desorption method, scanning electron microscopy (SEM), and thermosgravimetric analysis (TGA). Unique properties such as high surface area and pore diameter, in addition to highly reactive atoms and presence of various functional groups make the mesoporous silica possible for efficient removal of malachite green (MG). In batch experimental set-up, optimum conditions for quantitative removal ofmore » MG by mesoporous silica was attained by varying different variables such as adsorbent dosage, initial dye concentration, contact time, and pH. Optimum values were set as pH of 8.0, 0.5 g of adsorbent at contact time of 120 min. The adsorption of MG follows the pseudo-second-order rate equation. Equilibrium data fitted well with the Freundlich model at all amount of adsorbent, while maximum adsorption capacity was 5.981 mg g{sup −}1 for 0.5 g mesoporous silica synthesized in IL.« less

Antarctic marine bacterium Pseudoalteromonas sp. KNOUC808 as a source of cold-adapted lactose hydrolyzing enzyme

PubMed Central

Nam, EunSook; Ahn, JongKun

2011-01-01

Psychrophilic bacteria, which grow on lactose as a carbon source, were isolated from Antarctic polar sea water. Among the psychrophilic bacteria isolated, strain KNOUC808 was able to grow on lactose at below 5°C, and showed 0.867 unit of o-nitrophenyl β-D-galactopyranoside(ONPG) hydrolyzing activity at 4°C. The isolate was gram-negative, rod, aerobic, catalase positive and oxidase positive. Optimum growth was done at 20°C, pH 6.8–7.2. The composition of major fatty acids in cell of KNOUC801 was C12:0 (5.48%), C12:0 3OH (9.21%), C16:0 (41.83%), C17:0 ω8 (7.24%) and C18:1 ω7 (7.04%). All these results together suggest that it is affiliated with Pseudoalteromonas genus. The 16S rDNA sequence corroborate the phenotypic tests and the novel strain was designated as Pseudoalteromonas sp. KNOUC808. The optimum temperature and pH for lactose hydrolyzing enzyme was 20°C and 7.8, respectively. The enzyme was stable at 4°C for 7 days, but its activity decreased to about 50% of initial activity at 37°C in 7 days. PMID:24031708

Three RNases in Senescent and Nonsenescent Wheat Leaves 1

PubMed Central

Blank, A.; McKeon, Thomas A.

1991-01-01

We have described three RNases in wheat leaves (Triticum aestivum L. cv Chinese Spring) and developed assays for measuring each RNase individually in crude leaf extracts. We initially used activity staining in sodium dodecyl sulfate-polyacrylamide gels to characterize RNases in extracts of primary and flag leaves. We thus identified acid RNase (EC 3.1.27.1, here designated RNase WLA), and two apparently novel enzymes, designated RNases WLB and WLC. RNase WLB activity displays a distinctive isozyme pattern, a molecular mass of 26 kilodaltons (major species), a broad pH range with an optimum near neutrality, insensitivity to EDTA, and stimulation by moderate concentrations of KCl and by MgCl2. RNase WLC activity exhibits a molecular mass of 27 kilodaltons, a neutral pH optimum, insensitivity to EDTA, and inhibition by KCl, MgCl2, and tri-(hydroxymethyl)aminomethane. Based on distinctive catalytic properties established in gels, we designed conventional solution assays for selective quantitation of each RNase activity. We used the assays to monitor the individual RNases after gel filtration chromatography and native gel electrophoresis of extracts. In accompanying work, we used the assays to monitor RNases WLA, WLB, and WLC, which are present in senescent and nonsenescent leaves, during the course of leaf senescence. ImagesFigure 1Figure 3Figure 4 PMID:16668563

Musa paradisiaca stem juice as a source of peroxidase and ligninperoxidase.

PubMed

Vernwal, S K; Yadav, R S; Yadav, K D

2000-10-01

Musa paradisiaca stem juice has been shown to contain peroxidase activity of the order of 0.1 enzyme unit/ml. The Km values of this peroxidase for the substrates guaiacol and hydrogen peroxide are 2.4 and 0.28 mM respectively. The pH and temperature optima are 4.5 and 62.5 degrees C respectively. Like other peroxidases, it follows double displacement type mechanism. At low pH, Musa paradisiaca stem juice exhibits ligninperoxidase type activity. The pH optimum for ligninperoxidase type activity is 2.0 and the temperature optimum is 24 degrees C. The Km values for veratryl alcohol and n-propanol are 66 and 78 microM respectively.

Preparation and properties of immobilized pectinase onto the amphiphilic PS-b-PAA diblock copolymers.

PubMed

Lei, Zhongli; Bi, Shuxian

2007-01-30

Well-defined amphiphilic block copolymers poly(styrene-b-acrylic acid) (PS-b-PAA) with controlled block length were synthesized using atom transfer radical polymerization (ATRP). Pectinase enzyme was immobilized on the well-defined amphiphilic block copolymers PS-b-PAA. The carboxyl groups on the amphiphilic PS-b-PAA diblock copolymers present a very simple, mild, and time-saving process for enzyme immobilization. Various characteristics of immobilized pectinase such as the pH and temperature stability, thermal stability, and storage stability were valuated. Among them the pH optimum and temperature optimum of free and immobilized pectinase were found to be pH 6.0 and 65 degrees C.

Effect of water activity and pH on growth and toxin production by Clostridium botulinum type G.

PubMed Central

Briozzo, J; de Lagarde, E A; Chirife, J; Parada, J L

1986-01-01

The combined effect of water activity (aw) and pH on growth and toxin production by Clostridium botulinum type G strain 89 was investigated. The minimum aw at which growth and toxin formation occurred was 0.965, for media in which the pH was adjusted with either sodium chloride or sucrose. The minimum pH (at the optimum aw) for growth and toxin production of C. botulinum type G was found to be 5.6. Optimum conditions for toxin activation were a trypsin concentration of 0.1%, a pH of the medium of 6.5, and an incubation for 45 min at 37 degrees C. These data did not show evidence of heat-labile spores, since a heat shock of 75 degrees C for 10 min did not significantly decrease the spore count of strain 89G in media at pH 7.0 or 5.6. It was frequently observed that cells grown at reduced aw or pH experienced severe morphological changes. PMID:3518631

Fast photocatalytic degradation of methylene blue dye using a low-power diode laser.

PubMed

Liu, Xianhua; Yang, Yulou; Shi, Xiaoxuan; Li, Kexun

2015-01-01

This study focused on the application of diode lasers as alternative light sources for the fast photocatalytic degradation of methylene blue. The photocatalytic decomposition of methylene blue in aqueous solution under 443 nm laser light irradiation was found to be technically feasible using Ag/AgCl nanoparticles as photocatalysts. The effects of various experimental parameters, such as irradiation time, light source, catalyst loading, initial dye concentration, pH, and laser energy on decolorization and degradation were investigated. The mineralization of methylene blue was confirmed by chemical oxygen demand analysis. The results demonstrate that the laser-induced photocatalytic process can effectively degrade methylene blue under the optimum conditions (pH 9.63, 4 mg/L MB concentration, and 1.4 g/L Ag/AgCl nanoparticles). Copyright © 2014 Elsevier B.V. All rights reserved.

Removal of copper(II) ions from aqueous solutions by Azolla rongpong: batch and continuous study.

PubMed

Nedumaran, B; Velan, M

2008-01-01

Batch and packed bed continuous biosorption studies were conducted to investigate the kinetics and isotherms of Cu(II) ions on the biomass of blue green alga Azolla rongpong. It is observed that the biosorption capacity of algae depends on initial pH and dosage. The biosorption capacity increases with increasing concentration and follows Freundlich isotherm model well with k and n values 0.06223 and 0.949 respectively. The optimum pH of 3.5 with an algae dosage of 1 g/L was observed. The results indicate that with the advantage of high metal biosorption capacity and recovery of Cu(II) ions, A. rongpong can be used as an efficient and economic biosorbent for the removal and recovery of toxic heavy metals from aqueous wastes even at higher concentration.

Adsorption of hexavalent chromium onto sisal pulp/polypyrrole composites

NASA Astrophysics Data System (ADS)

Tan, Y. Y.; Wei, C.; Gong, Y. Y.; Du, L. L.

2017-02-01

Sisal pulp/polypyrrole composites(SP/PPy) utilized for the removal of hexavalent chromium [Cr(VI)] from wastewater, were prepared via in-situ chemical oxidation polymerization approach. The structure and morphology of the SP/PPy were analyzed by polarizing optical microscopy (POM), field-emission scanning electron microscopy (SEM)), Energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS), the results indicated SP could be efficient dispersion of PPy. The hexavalent chromium adsorption results indicate adsorption capacity of the SP/PPy were dependent on the initial pH, with an optimum pH of 2.0. The sorption kinetic data fitted well to the pseudo-second order model and isotherm data fitted well to the Langmuir isotherm model. The maximum adsorption capacity determined from the Langmuir isotherm is 336.70 mg/g at 25° C.

Medium optimization for the production of recombinant nattokinase by Bacillus subtilis using response surface methodology.

PubMed

Chen, Po Ting; Chiang, Chung-Jen; Chao, Yun-Peng

2007-01-01

Nattokinase is a potent fibrinolytic enzyme with the potential for fighting cardiovascular diseases. Most recently, a new Bacillus subtilis/Escherichia coli (B. subtilis/E. coli) shuttle vector has been developed to achieve stable production of recombinant nattokinase in B. subtilis (Chen; et al. 2007, 23, 808-813). With this developed B. subtilis strain, the design of an optimum but cost-effective medium for high-level production of recombinant nattokinase was attempted by using response surface methodology. On the basis of the Plackett-Burman design, three critical medium components were selected. Subsequently, the optimum combination of selected factors was investigated by the Box-Behnken design. As a result, it gave the predicted maximum production of recombinant nattokinase with 71 500 CU/mL for shake-flask cultures when the concentrations of soybean hydrolysate, potassium phosphate, and calcium chloride in medium were at 6.100, 0.415, and 0.015%, respectively. This was further verified by a duplicated experiment. Moreover, the production scheme based on the optimum medium was scaled up in a fermenter. The batch fermentation of 3 L was carried out by controlling the condition at 37 degrees C and dissolved oxygen reaching 20% of air saturation level while the fermentation pH was initially set at 8.5. Without the need for controlling the broth pH, recombinant nattokinase production with a yield of 77 400 CU/mL (corresponding to 560 mg/L) could be obtained in the culture broth within 24 h. In particular, the recombinant B. subtilis strain was found fully stable at the end of fermentation when grown on the optimum medium. Overall, it indicates the success of this experimental design approach in formulating a simple and cost-effective medium, which provides the developed strain with sufficient nutrient supplements for stable and high-level production of recombinant nattokinase in a fermenter.

Cloning, Overexpression, and Characterization of a Metagenome-Derived Phytase with Optimal Activity at Low pH.

PubMed

Tan, Hao; Wu, Xiang; Xie, Liyuan; Huang, Zhongqian; Gan, Bingcheng; Peng, Weihong

2015-06-01

A phytase gene was identified in a publicly available metagenome derived from subsurface groundwater, which was deduced to encode for a protein of the histidine acid phosphatase (HAP) family. The nucleotide sequence of the phytase gene was chemically synthesized and cloned, in order to further overexpress the phytase in Escherichia coli. Purified protein of the recombinant phytase demonstrated an activity for phytic acid of 298 ± 17 μmol P/min/mg, at the pH optimum of 2.0 with the temperature of 37 °C. Interestingly, the pH optimum of this phytase is much lower in comparison with most HAP phytases known to date. It suggests that the phytase could possess improved adaptability to the low pH condition caused by the gastric acid in livestock and poultry stomachs.

The use of macroalgae (Gracilaria changii) as bio-adsorbent for Copper (II) removal

NASA Astrophysics Data System (ADS)

Lavania-Baloo; Idayu, Nordin; Umar Salihi, Ibrahim; Zainoddin, Jamari

2017-05-01

Biosorption of heavy metals using marine macroalgae biomass can be an effective process and alternative to conventional methods. Activated carbon was developed from macroalgae (Gracilaria changii) and used as adsorbents for the removal of copper (II) from wastewater. Gracilaria changii based activated carbon (GCBAC) was prepared using muffle furnace at a constant temperature of 300 °C for 1 hour. Batch adsorption experiments were conducted to investigate the effets of important parameters such as pH, contact time, initial metal concentration and adsorbent dosage on the removal of Cu (II) from synthetic aqueous solution. Batch adsorption study shows that removal of Cu (II) using GCBAC relied upon pH, contact time, initial metal concentration and GCBAC dosage. The optimum conditions parameters were found to be pH 6.0, time of 60 minutes and GCBAC dosage of 0.3 g, respectively. Adsorption data was described better by Freundlich isotherm model with R2 value of 0.7936. The maximum Cu (II) adsorption capacity of GCBAC was found to be 0.07 mg/g. The experimental adsorption data obtained fitted well into Pseudo-second-order kinetic model, with R2 value near unity. Thus, GCBAC can be used as an effective adsorbent for the removal of Cu (II) from aqueous solution.

Development and Optimization of HPLC Analysis of Metronidazole, Diloxanide, Spiramycin and Cliquinol in Pharmaceutical Dosage Forms Using Experimental Design.

PubMed

Elkhoudary, Mahmoud M; Abdel Salam, Randa A; Hadad, Ghada M

2016-11-01

A new simple, sensitive, rapid and accurate gradient reversed-phase high-performance liquid chromatography with photodiode array detector (RP-HPLC-DAD) was developed and validated for simultaneous analysis of Metronidazole (MNZ), Spiramycin (SPY), Diloxanidefuroate (DIX) and Cliquinol (CLQ) using statistical experimental design. Initially, a resolution V fractional factorial design was used in order to screen five independent factors: the column temperature (°C), pH, phosphate buffer concentration (mM), flow rate (ml/min) and the initial fraction of mobile phase B (%). pH, flow rate and initial fraction of mobile phase B were identified as significant, using analysis of variance. The optimum conditions of separation determined with the aid of central composite design were: (1) initial mobile phase concentration: phosphate buffer/methanol (50/50, v/v), (2) phosphate buffer concentration (50 mM), (3) pH (4.72), (4) column temperature 30°C and (5) mobile phase flow rate (0.8 ml min -1 ). Excellent linearity was observed for all of the standard calibration curves, and the correlation coefficients were above 0.9999. Limits of detection for all of the analyzed compounds ranged between 0.02 and 0.11 μg ml -1 ; limits of quantitation ranged between 0.06 and 0.33 μg ml -1 The proposed method showed good prediction ability. The optimized method was validated according to ICH guidelines. Three commercially available tablets were analyzed showing good % recovery and %RSD. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Total nitrogen and total phosphorus removal from brackish aquaculture wastewater using effective microorganism

NASA Astrophysics Data System (ADS)

Mohamad, K. A.; Mohd, S. Y.; Sarah, R. S.; Mohd, H. Z.; Rasyidah, A.

2017-09-01

Aquaculture is one of dominant food based industry in the world with 8.3% annual growth rate and its development had led to adverse effect on the environment. High nutrient production in form of nitrogenous compound and phosphorus contributed to environmental deterioration such as eutrophication and toxicity to the industry. Usage of Effective Microorganism (EM), one of the biological approaches to remove Total Nitrogen (TN) and Total Phosphorus (TP) in aquaculture pond was proposed. Samples were obtained from the Sea Bass intensive brackish aquaculture wastewater (AW) from fish farm at Juru, Penang and the parameters used to measure the removal of nitrogenous compounds include, pH, EM dosage, shaking, contact time and optimum variable conditions. From the study, for effective contact time, day 6 is the optimum contact time for both TN and TP with 99.74% and 62.78% removal respectively while in terms of optimum pH, the highest TN removal was at pH 7 with 66.89 %. The optimum dosage of EM is 1.5 ml with ratio 1:166 for 81.5 % TN removal was also found appropriate during the experiment. At varied optimum conditions of EM, the removal efficiency of TN and TP were 81.53% and 38.94% respectively while the removal mechanism of TN was highly dependent on the decomposition rate of specific bacteria such as Nitrobacter bacteria, Yeast and Bacillus Subtilis sp. The study has established the efficacy of EM's ability to treat excessive nutrient of TN and TP from AW.

Effect of some operational parameters on the arsenic removal by electrocoagulation using iron electrodes

PubMed Central

2014-01-01

Arsenic contamination of drinking water is a global problem that will likely become more apparent in future years as scientists and engineers measure the true extent of the problem. Arsenic poisoning is preventable though as there are several methods for easily removing even trace amounts of arsenic from drinking water. In the present study, electrocoagulation was evaluated as a treatment technology for arsenic removal from aqueous solutions. The effects of parameters such as initial pH, current density, initial concentration, supporting electrolyte type and stirring speed on removal efficiency were investigated. It has been observed that initial pH was highly effective on the arsenic removal efficiency. The highest removal efficiency was observed at initial pH = 4. The obtained experimental results showed that the efficiency of arsenic removal increased with increasing current density and decreased with increasing arsenic concentration in the solution. Supporting electrolyte had not significant effects on removal, adding supporting electrolyte decreased energy consumption. The effect of stirring speed on removal efficiency was investigated and the best removal efficiency was at the 150 rpm. Under the optimum conditions of initial pH 4, current density of 0.54 mA/cm2, stirring speed of 150 rpm, electrolysis time of 30 minutes, removal was obtained as 99.50%. Energy consumption in the above conditions was calculated as 0.33 kWh/m3. Electrocoagulation with iron electrodes was able to bring down 50 mg/L arsenic concentration to less than 10 μg/L at the end of electrolysis time of 45 minutes with low electrical energy consumption as 0.52 kWh/m3. PMID:24991426

Performance and microbial communities of Mn(II)-based autotrophic denitrification in a Moving Bed Biofilm Reactor (MBBR).

PubMed

Su, Jun Feng; Luo, Xian Xin; Wei, Li; Ma, Fang; Zheng, Sheng Chen; Shao, Si Cheng

2016-07-01

In this study, Mn(II) as electron donor was tested for the effects on denitrification in the MBBR under the conditions of initial nitrate concentration (10mgL(-1), 30mgL(-1), 50mgL(-1)), pH (5, 6, 7) and hydraulic retention time (HRT) (4h, 8h, 12h) which conducted by response surface methodology (RSM), the results demonstrated that the highest nitrate removal efficiency was occurred under the conditions of initial nitrate concentration of 47.64mgL(-1), HRT of 11.96h and pH 5.21. Analysis of SEM and flow cytometry suggested that microorganisms were immobilized on the Yu Long plastic carrier media successfully before the reactor began to operate. Furthermore, high-throughput sequencing was employed to characterize and compare the community compositions and structures of MBBR under the optimum conditions, the results showed that Pseudomonas sp. SZF15 was the dominant contributor for effective removal of nitrate in the MBBR. Copyright © 2016 Elsevier Ltd. All rights reserved.

Adsorption of malachite green from aqueous solution by using novel chitosan ionic liquid beads.

PubMed

Naseeruteen, Faizah; Hamid, Nur Shahirah Abdul; Suah, Faiz Bukhari Mohd; Ngah, Wan Saime Wan; Mehamod, Faizatul Shimal

2018-02-01

Chitosan ionic liquid beads were prepared from chitosan and 1-butyl-3-methylimidazolium based ionic liquids to remove Malachite Green (MG) from aqueous solutions. Batch adsorption experiments were carried out as a function of initial pH, adsorbent dosage, agitation time and initial MG concentration. The optimum conditions were obtained at pH 4.0, 0.008g of adsorbent dosage and 20min of agitation time were utilized in the kinetic and isotherm studies. Three kinetic models were applied to analyze the kinetic data and pseudo-second order was found to be the best fitted model with R 2 >0.999. In order to determine the adsorption capacity, the sorption data were analyzed using the linear form of Langmuir, Freundlich and Temkin equations. The isotherm was best fitted by Langmuir isotherm model. The maximum adsorption capacity (q max ) obtained from Langmuir isotherm for two chitosan beads 1-butyl-3-methylimidazolium acetate A and 1-butyl-3-methylimidazolium B are 8.07mgg -1 and 0.24mgg -1 respectively. Copyright © 2017 Elsevier B.V. All rights reserved.

Aminopyridine modified Spirulina platensis biomass for chromium(VI) adsorption in aqueous solution.

PubMed

Bayramoglu, Gulay; Akbulut, Aydin; Arica, M Yakup

Chemical modification of Spirulina platensis biomass was realized by sequential treatment of algal surface with epichlorohydrin and aminopyridine. Adsorptive properties of Cr(VI) ions on native and aminopyridine modified algal biomass were investigated by varying pH, contact time, ionic strength, initial Cr(VI) concentration, and temperature. FTIR and analytical analysis indicated that carboxyl and amino groups were the major functional groups for Cr(VI) ions adsorption. The optimum adsorption was observed at pH 3.0 for native and modified algal biomasses. The adsorption capacity was found to be 79.6 and 158.7 mg g(-1), for native and modified algal biomasses, respectively. For continuous system studies, the experiments were conducted to study the effect of important design parameters such as flow rate and initial concentration of metal ions, and the maximum sorption capacity was observed at a flow rate of 50 mL h(-1), and Cr(VI) ions concentration 200 mg L(-1) with modified biomass. Experimental data fitted a pseudo-second-order equation. The regeneration performance was observed to be 89.6% and 94.3% for native and modified algal biomass, respectively.

Comparative evaluation of cyanide removal by adsorption, biodegradation, and simultaneous adsorption and biodegradation (SAB) process using Bacillus cereus and almond shell.

PubMed

Dwivedi, Naveen; Balomajumder, Chandrajit; Mondal, Prasenji

2016-07-01

The present study aimed to investigate the removal efficiency of cyanide from contaminated water by adsorption, biodegradation and simultaneous adsorption and biodegradation (SAB) process individually in a batch reactor. Adsorption was achieved by using almond shell granules and biodegradation was conducted with suspended cultures of Bacillus cereus, whereas SAB process was carried out using Bacillus cereus and almond shell in a batch reactor. The effect of agitation time, pH, and initial cyanide concentration on the % removal of cyanide has been discussed. Under experimental conditions, optimum removal was obtained at pH 7 with agitation time of 48 hrs and temperature of 35 degrees C. Cyanide was utilized by bacteria as sole source of nitrogen for growth. The removal efficiencies of cyanide by adsorption, biodegradation, and SAB were found to be 91.38%, 95.87%, and 99.63%, respectively, at initial cyanide concentration of 100 mg l(-1). The removal efficiency of SAB was found to be better as compared to that of biodegradation and adsorption alone.

Biosorption of Cd(II) and Cs(I) from aqueous solution by live and dead cells of Saccharomyces carlsbergensis PTCC 5051.

PubMed

Sayyadi, Shayan; Ahmady-Asbchin, Salman; Kamali, Kasra

2018-02-01

The biosorption characteristics of Cd(II) and Cs(I) using live and dead cells of Saccharomyces carlsbergensis PTCC 5051 as biosorbents have been investigated in the present research. The influence of different experimental parameters such as initial pH (pHi), shaking rate, sorption time and initial metal concentration was evaluated. The optimum pH was obtained as 4 for Cd(II) and 7 for Cs(I). The experimental adsorption data were fitted to the Langmuir linear equation adsorption model. The highest metal uptake values of 0.593 and 0.473 mmol g -1 were calculated for Cd(II) and Cs(I), respectively. The results of Fourier transform infrared analysis suggested the involvement of amine, carboxyl and hydroxyl groups during the biosorption process and also indicated that more functional groups were involved in the biosorption process of live adsorbents, compared with those linked to dead biomass. The results showed that the biomass of S. carlsbergensis PTCC 5051 is a suitable biosorbent for the removal of Cd(II) and Cs(I) from the aqueous solutions.

Investigation of Cr(VI) adsorption onto chemically treated Helianthus annuus: optimization using response surface methodology.

PubMed

Jain, Monika; Garg, V K; Kadirvelu, K

2011-01-01

In the present study, chemically treated Helianthus annuus flowers (SHC) were used to optimize the removal efficiency for Cr(VI) by applying Response Surface Methodological approach. The surface structure of SHC was analyzed by Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-ray Analysis (EDX). Batch mode experiments were also carried out to assess the adsorption equilibrium in aqueous solution. The adsorption capacity (qe) was found to be 7.2 mg/g. The effect of three parameters, that is pH of the solution (2.0-7.0), initial concentration (10-70 mg/L) and adsorbent dose (0.05-0.5 g/100 mL) was studied for the removal of Cr(VI) by SHC. Box-Behnken model was used as an experimental design. The optimum pH, adsorbent dose and initial Cr(VI) concentration were found to be 2.0, 5.0 g/L and 40 mg/L, respectively. Under these conditions, removal efficiency of Cr(VI) was found to be 90.8%. Copyright © 2010 Elsevier Ltd. All rights reserved.

Experimental design for the evaluation of struvite sedimentation obtained from an ammonium concentrated wastewater.

PubMed

Castro, Samuel Rodrigues; Araújo, Mahira Adna Cota; Lange, Liséte Celina

2013-01-01

Chemical precipitation of struvite as a technique of ammonium nitrogen (NH(4)-N) removal from concentrated wastewater has been shown to be an attractive alternative due to its high effectiveness, reaction rate, simplicity, environmental sustainability and, especially, the application potential of the generated solids for the fertilizer industry. The technique of experimental design has been used in order to identify and evaluate the optimum conditions of chemical precipitation reaction applied in a struvite sedimentation study. The preliminary tests were performed using synthetic effluent with a concentration equal to 500.0 mg N L(-1). The stoichiometric ratio Mg:NH(4):PO(4) equal to 1.5:1.0:1.25 and pH equal to 8.5 were taken to be the optimum conditions, where a NH(4)-N removal equal to 98.6% was achieved with only 10-min reaction time. This condition has been used to evaluate the struvite sedimentation from synthetic wastewaters, intending to check the optimum conditions achieved by the experimental design in different initial concentrations, 1,000 and 2,000 mg N L(-1). The results were typical of a good zonal sedimentation and can be used in the scale up the system.

Complexation of sodium caseinate with gum tragacanth: Effect of various species and rheology of coacervates.

PubMed

Ghorbani Gorji, Sara; Ghorbani Gorji, Elham; Mohammadifar, Mohammad Amin; Zargaraan, Azizollaah

2014-06-01

We investigated complex coacervation of sodium caseinate/Astragalus rahensis (A.r) as a function of pH with light scattering, spectrophotometry, and viscosity measurements. Interestingly, sodium caseinate/A.r displayed five structural transitions; pH 7.00 to pH ∼5.40: no interaction occurred, pH ∼5.40 to pH ∼4.80: initiation of the formation of primary soluble complexes, pH ∼4.80 to ∼4.30: formation of interpolymer complexes, pH ∼4.30 to ∼4.02: optimum coacervation and pH ∼4.02 to ∼2.50: suppression of coacervation. In addition, rheological properties of sodium caseinate/A.r coacervates were studied at various pH values. A much higher storage modulus (G') than loss modulus (G″) for all sodium caseinate/A.r coacervates suggests the formation of highly interconnected gel-like network structures with mainly elastic behaviour. Moreover, sodium caseinate/A.r coacervates at all pH values exhibited a shear thinning behaviour across the entire shear rate range investigated. Effects of different species of gum tragacanth on the interactions with sodium caseinate have been scarcely studied. Our study showed that systems containing various species (A.r, soluble fraction of A.r and Astragalus gossypinus (A.g)) had different critical pH values and particle sizes during complex coacervation, which could be due to different ratio of soluble to insoluble fractions and uronic acid content of various species. Copyright © 2014 Elsevier B.V. All rights reserved.

Optimization of the mineralization of a mixture of phenolic pollutants under a ferrioxalate-induced solar photo-Fenton process.

PubMed

Monteagudo, J M; Durán, A; Aguirre, M; San Martín, I

2011-01-15

The mineralization of solutions containing a mixture of three phenolic compounds, gallic, p-coumaric and protocatechuic acids, in a ferrioxalate-induced solar photo-Fenton process was investigated. The reactions were carried out in a pilot plant consisting of a compound parabolic collector (CPC) solar reactor. An optimization study was performed combining a multivariate experimental design and neuronal networks that included the following variables: pH, temperature, solar power, air flow and initial concentrations of H(2)O(2), Fe(II) and oxalic acid. Under optimal conditions, total elimination of the original compounds and 94% TOC removal of the mixture were achieved in 5 and 194 min, respectively. pH and initial concentrations of H(2)O(2) and Fe(II) were the most significant factors affecting the mixture mineralization. The molar correlation between consumed hydrogen peroxide and removed TOC was always between 1 and 3. A detailed analysis of the reaction was presented. The values of the pseudo-first-order mineralization kinetic rate constant, k(TOC), increased as initial Fe(II) and H(2)O(2) concentrations and temperature increased. The optimum pH value also slightly increased with greater Fe(II) and hydrogen peroxide concentrations but decreased when temperature increased. OH and O(2)(-) radicals were the main oxidative intermediate species in the process, although singlet oxygen ((1)O(2)) also played a role in the mineralization reaction. Copyright © 2010 Elsevier B.V. All rights reserved.

Optimization of photocatalytic degradation of methyl blue using silver ion doped titanium dioxide by combination of experimental design and response surface approach.

PubMed

Sahoo, C; Gupta, A K

2012-05-15

Photocatalytic degradation of methyl blue (MYB) was studied using Ag(+) doped TiO(2) under UV irradiation in a batch reactor. Catalytic dose, initial concentration of dye and pH of the reaction mixture were found to influence the degradation process most. The degradation was found to be effective in the range catalytic dose (0.5-1.5g/L), initial dye concentration (25-100ppm) and pH of reaction mixture (5-9). Using the three factors three levels Box-Behnken design of experiment technique 15 sets of experiments were designed considering the effective ranges of the influential parameters. The results of the experiments were fitted to two quadratic polynomial models developed using response surface methodology (RSM), representing functional relationship between the decolorization and mineralization of MYB and the experimental parameters. Design Expert software version 8.0.6.1 was used to optimize the effects of the experimental parameters on the responses. The optimum values of the parameters were dose of Ag(+) doped TiO(2) 0.99g/L, initial concentration of MYB 57.68ppm and pH of reaction mixture 7.76. Under the optimal condition the predicted decolorization and mineralization rate of MYB were 95.97% and 80.33%, respectively. Regression analysis with R(2) values >0.99 showed goodness of fit of the experimental results with predicted values. Copyright © 2012 Elsevier B.V. All rights reserved.

A portable anaerobic microbioreactor reveals optimum growth conditions for the methanogen Methanosaeta concilii.

PubMed

Steinhaus, Benjamin; Garcia, Marcelo L; Shen, Amy Q; Angenent, Largus T

2007-03-01

Conventional studies of the optimum growth conditions for methanogens (methane-producing, obligate anaerobic archaea) are typically conducted with serum bottles or bioreactors. The use of microfluidics to culture methanogens allows direct microscopic observations of the time-integrated response of growth. Here, we developed a microbioreactor (microBR) with approximately 1-microl microchannels to study some optimum growth conditions for the methanogen Methanosaeta concilii. The microBR is contained in an anaerobic chamber specifically designed to place it directly onto an inverted light microscope stage while maintaining a N2-CO2 environment. The methanogen was cultured for months inside microchannels of different widths. Channel width was manipulated to create various fluid velocities, allowing the direct study of the behavior and responses of M. concilii to various shear stresses and revealing an optimum shear level of approximately 20 to 35 microPa. Gradients in a single microchannel were then used to find an optimum pH level of 7.6 and an optimum total NH4-N concentration of less than 1,100 mg/liter (<47 mg/liter as free NH3-N) for M. concilii under conditions of the previously determined ideal shear stress and pH and at a temperature of 35 degrees C.

THE NATURE AND CONTROL OF REACTIONS IN BIOLUMINESCENCE

PubMed Central

Johnson, F. H.; Eyring, H.; Steblay, R.; Chaplin, H.; Huber, C.; Gherardi, G.

1945-01-01

On the basis of available data with regard to the chemical and physical properties of the "substrate" luciferin (LH2) and enzyme, luciferase (A), and of kinetic data derived both from the reaction in extracts of Cypridina, and from the luminescence of intact bacteria, the fundamental reactions involved in the phenomenon of bioluminescence have been schematized. These reactions provide a satisfactory basis for interpreting the known characteristics of the system, as well as the theoretical chemistry with regard to the control of its over-all velocity in relation to various factors. These factors, here studied experimentally wholly with bacteria, Photobacterium phosphoreum in particular, include pH, temperature, pressure, and the drugs sulfanilamide, urethane, and alcohol, separately and in relation to each other. Under steady state conditions of bacterial luminescence, with excess of oxidizable substrate and with oxygen not limiting, the data indicate that the chief effects of these agents center around the pace setting reactions, which may be designated by the equation: A + LH2 → ALH2 following which light emission is assumed proportional to the amount of the excited molecule, AL*. The relation between pH and luminescence intensity varies with (a), the buffer mixture and concentration, (b), the temperature, and (c), the hydrostatic pressure. At an optimum temperature for luminescence of about 22° C. in P. phosphoreum, the effects of increasing or decreasing the hydrogen ion concentration are largely reversible over the range between pH 3.6 and pH 8.8. The relation between luminescence intensity and pH, under the experimental conditions employed, is given by the following equation, in which I 1 represents the maximum intensity, occurring about pH 6.5; I 2 the intensity at any other given pH; K 5 the equilibrium constant between hydrogen ions and the AL-; and K 6 the corresponding constant with respect to hydroxyl ions: See PDF for Equation The value of K 5, as indicated by the data, amounts to 4.84 x 104, while that of K 6 amounts to 4.8 x 105. Beyond the range between approximately pH 3.8 and 8.8, destructive effects of the hydrogen and hydroxyl ions, respectively, were increasingly apparent. By raising the temperature above the optimum, the destructive effects were apparent at all pH, and the intensity of the luminescence diminished logarithmically with time. With respect to pH, the rate of destruction of the light-emitting system at temperatures above the optimum was slowest between pH 6.5 and 7.0, and increased rapidly with more acid or more alkaline reactions of the medium. The reversible effects of slightly acid pH vary with the temperature in the manner of an inhibitor (Type I) that acts independently of the normal, reversible denaturation equilibrium (K 1) of the enzyme. The per cent inhibition caused by a given acid pH in relation to the luminescence intensity at optimum pH, is much greater at low temperatures, and decreases as the temperature is raised towards the optimum temperature. The observed maximum intensity of luminescence is thus shifted to slightly higher temperatures by increase in (H+). The apparent activation energy of luminescence is increased by a decrease in pH. The value of ΔH‡ at pH 5.05 was calculated to be 40,900 calories, in comparison with 20,700 at a pH of 6.92. The difference of 20,200 is taken to represent an estimate of the heat of ionization of ALH in the activation process, and compares roughtly with the 14,000 calories estimated for the same process, by analyzing the data from the point of view of hydrogen ions as an inhibitor. The decreasing temperature coefficient for luminescence in proceeding from low temperatures towards the optimum is accounted for in part by the greater degree of ionization of ALH. At the optimum temperature and acid reactions, pressures up to about 500 atmospheres retard the velocity of the luminescent oxidation. At the same temperature, with decrease in hydrogen ion concentration, the pressure effect is much less, indicating a considerable volume increase in the process of ionization and activation. In the extremely alkaline range, beyond pH 9, luminescence is greatly reduced, as compared with the intensity at neutrality, and under these conditions pressure causes a pronounced increase in intensity, presumably by acting upon the reversible denaturation equilibrium of the protein enzyme, A. Sulfanilamide, in neutral solutions, acts on luminescence in a manner very much resembling that of hydrogen ions at acidities between pH 4.0 and pH 6.5. Like the hydrogen ion equilibrium, the sulfanilamide equilibrium involves a ratio of approximately one inhibitor molecule to one enzyme molecule. The heat of reaction amounts to about 11,600 calories or more in a reversible combination that evidently evolves heat. Like the action of H ions, sulfanilamide causes a slight shifting of maximum luminescence intensity in the direction of higher temperatures, and an increase in the energy of activation. The effect of sulfanilamide on the growth of broth cultures of eight species of luminous bacteria indicates that there is no regular relationship among the different organisms between the concentration of the drug that prevents growth, and that which prevents luminescence in the cells which develop in the presence of sulfanilamide. p-Aminobenzoic acid (PAB) antagonizes the sulfanilamide inhibition of growth in luminous bacteria, and the cultures that develop are luminous. When (PAB) is added to cells from fully developed cultures, it has no effect on luminescence, or causes a slight inhibition, depending on the concentration. With luminescence partly inhibited by sulfanilamide, the addition of PAB has no effect, or has an inhibitory effect which adds to that caused by sulfanilamide. Two different, though possibly related, enzyme systems thus appear to limit growth and luminescence, respectively. The possible mechanism through which both the inhibitions and the antagonism take place is discussed. The irreversible destruction of the luminescent system at temperatures above that of the maximum luminescence, in a medium of favorable pH to which no inhibitors have been added, proceeds logarithmically with time at both normal and increased hydrostatic pressures. Pressure retards the rate of the destruction, and the analysis of the data indicates that a volume increase of roughly 71 cc. per gm. molecule at 32° C. takes place in going from the normal to the activated state in this reaction. At normal pressure, the rate of destruction has a temperature coefficient of approximately 90,000 calories, or about 20,000 calories more than the heat of reaction in the reversible denaturation equilibrium. The data indicate that the equilibrium and the rate process are two distinct reactions. The equation for luminescence intensity, taking into account both the reversible and irreversible phases of the reaction is given below. In the equation b is a proportionality constant; k' the rate constant of the luminescent reaction; A0 the total luciferase; A0i the total initial luciferase at time t equals 0; kn the rate constant for the destruction of the native, active form of the enzyme; kd the rate constant for the destruction of the reversibly denatured, inactive form; t the time; and the other symbols are as indicated above: See PDF for Equation For reasons cited in the text, kn evidently equals kd. Urethane and alcohol, respectively, act in a manner (Type II) that promotes the breaking of the type of bonds broken in both the reversible and irreversible reactions and so promotes the irreversible denaturation. This result is in contrast to the effects of sulfanilamide, which at appropriate concentrations may give rise to the same initial inhibition as that caused by urethane, but remains constant with time. The inhibition caused by urethane and alcohol, respectively, increases as the temperature is raised. As a result, the apparent optimum is shifted to lower temperatures, and the activation energy for the over-all process of luminescence diminishes. An analysis for the approximate heat of reaction in the equilibrium between these drugs and the enzyme, indicates 65,000 calories for urethane, and 37,000 for alcohol. A similar analysis with respect to the effect of hydroxyl ions as the inhibitor gives 60,300 calories. The effects of alcohol and urethane are sensitive to hydrostatic pressure. Moderate inhibitions at optimum temperature and pH, caused by relatively small concentrations of either drug, are completely abolished by pressures of 3,000 to 4,000 pounds per square inch. At optimum temperature and pH, increasing concentrations of alcohol caused the apparent optimum pressure for luminescence to shift markedly in the direction of higher pressures. Analysis of the data with respect to concentration of alcohol at different pressures indicated that the ratio of alcohol to enzyme molecules amounted to approximately 4, at 7,000 pounds, but only about 2.8 at normal pressures. This phenomenon was taken to indicate that more than one equilibrium is established between the alcohol and the protein. A similar interpretation was suggested in connection with the fact that analysis of the relation between concentration of urethane and amount of inhibition at different temperatures also indicated a ratio of urethane to enzyme molecules that increased with temperature in the equilibria involved. Analysis of the data with respect to pressure and the inhibition caused by a given concentration of alcohol at different temperatures indicated that the volume change involved in the combination of alcohol with the enzyme must be very small, while the actual effect of pressure is apparently mediated through the reversible denaturation of the protein enzyme, which is promoted by alcohol, urethane, and drugs of similar type. PMID:19873433

Study of micropart fabrication via 17-4 PH stainless nanopowder injection molding.

PubMed

Tirta, Andy; Prasetyo, Yus; Baek, Eung-Ryul; Choi, Chul-Jin

2011-01-01

Micropart fabrication via 17-4 PH stainless nanopowder injection molding was investigated. The nanopowder was mixed with a binder that was based on wax to produce a feedstock composed of 45% powder and binder (the powder load). Initially, the fit and proper test was done before the micropart was made by making some bars of green samples, which the properties were examined after the sintering process. The examination involved the mechanical properties such as the porosity, hardness, and some of metallurgical aspects, such as the second-phase formation and the final compound after the sintering. The results showed that utilizing 17-4 PH stainless nanopowder is promising for micropart fabrication since it can form a nearly full-density sintered sample with a low porosity and good toughness, and can provide a smooth surface finish. After this, the investigations followed with the injection of the feedstock into the PDMS micromold that was formed by the nickel pattern from the X-Ray LIGA process. The green samples successfully produced a high-aspect-ratio sample with a thickness of up to 1 mm and an aspect ratio of 15 in the microchannel part. Then the green samples were sintered at 1,300 degrees C for 2 h, since from the initial test, they showed optimum parameters with nearly full density, low porosity, and a high degree of hardness. The research shows the excellent results of the application of the 17-4 PH stainless nanopowder to micropart fabrication.

Batch and column studies on biosorption of acid dyes on fresh water macro alga Azolla filiculoides.

PubMed

Padmesh, T V N; Vijayaraghavan, K; Sekaran, G; Velan, M

2005-10-17

The biosorption of Acid red 88 (AR88), Acid green 3 (AG3) and Acid orange 7 (AO7) by deactivated fresh water macro alga Azolla filiculoides was investigated in batch mode. Langmuir and Freundlich adsorption models were used for the mathematical description of the batch biosorption equilibrium data and model constants were evaluated. The adsorption capacity was pH dependent with a maximum value of 109.0 mg/g at pH 7 for AR88, 133.5 mg/g at pH 3 for AG3 and 109.6 mg/g at pH 3 for AO7, respectively, was obtained. The pseudo first and second order kinetic models were also applied to the experimental kinetic data and high correlation coefficients favor pseudo second order model for the present systems. The ability of A. filiculoides to biosorb AG3 in packed column was also investigated. The column experiments were conducted to study the effect of important design parameters such as initial dye concentration (50-100 mg/L), bed height (15-25 cm) and flow rate (5-15 mL/min) to the well-adsorbed dye. At optimum bed height (25 cm), flow rate (5 mL/min) and initial dye concentration (100 mg/L), A. filiculoides exhibited 28.1mg/g for AG3. The Bed Depth Service Time model and the Thomas model were used to analyze the experimental data and the model parameters were evaluated.

Efficient mannitol production by wild-type Lactobacillus reuteri CRL 1101 is attained at constant pH using a simplified culture medium.

PubMed

Ortiz, Maria Eugenia; Raya, Raúl R; Mozzi, Fernanda

2015-10-01

Mannitol is a natural polyol with multiple industrial applications. In this work, mannitol production by Lactobacillus reuteri CRL 1101 was studied at free- and controlled-pH (6.0-4.8) fermentations using a simplified culture medium containing yeast and beef extracts and sugarcane molasses. The activity of mannitol 2-dehydrogenase (MDH), the enzyme responsible for mannitol synthesis, was determined. The effect of the initial biomass concentration was further studied. Mannitol production (41.5 ± 1.1 g/l), volumetric productivity (Q Mtl 1.73 ± 0.05 g/l h), and yield (Y Mtl 105 ± 11 %) were maximum at pH 5.0 after 24 h while the highest MDH activity (1.66 ± 0.09 U/mg protein) was obtained at pH 6.0. No correlation between mannitol production and MDH activity was observed when varying the culture pH. The increase (up to 2000-fold) in the initial biomass concentration did not improve mannitol formation after 24 h although a 2-fold higher amount was produced at 8 h using 1 or 2 g cell dry weight/l comparing to the control (0.001 g cell dry weight/l). Finally, mannitol isolation under optimum fermentation conditions was achieved. The mannitol production obtained in this study is the highest reported so far by a wild-type L. reuteri strain and, more interestingly, using a simplified culture medium.

Pectate hydrolases of parsley (Petroselinum crispum) roots.

PubMed

Flodrová, Dana; Dzúrovä, Mária; Lisková, Desana; Mohand, Fairouz Ait; Mislovicová, Danica; Malovícová, Anna; Voburka, Zdenek; Omelková, Jirina; Stratilová, Eva

2007-01-01

The presence of various enzyme forms with terminal action pattern on pectate was evaluated in a protein mixture obtained from parsley roots. Enzymes found in the soluble fraction of roots (juice) were purified to homogeneity according to SDS-PAGE, partially separated by preparative isoelectric focusing and characterized. Three forms with pH optima 3.6, 4.2 and 4.6 clearly preferred substrates with a lower degree of polymerization (oligogalacturonates) while the form with pH optimum 5.2 was a typical exopolygalacturonase [EC 3. 2.1.67] with relatively fast cleavage of polymeric substrate. The forms with pH optima 3.6, 4.2 and 5.2 were released from the pulp, too. The form from the pulp with pH optimum 4.6 preferred higher oligogalacturonates and was not described in plants previously. The production of individual forms in roots was compared with that produced by root cells cultivated on solid medium and in liquid one.

Preparation and Optimisation of Cross-Linked Enzyme Aggregates Using Native Isolate White Rot Fungi Trametes versicolor and Fomes fomentarius for the Decolourisation of Synthetic Dyes

PubMed Central

Vršanská, Martina; Voběrková, Stanislava; Jiménez Jiménez, Ana María; Strmiska, Vladislav; Adam, Vojtěch

2017-01-01

The key to obtaining an optimum performance of an enzyme is often a question of devising a suitable enzyme and optimisation of conditions for its immobilization. In this study, laccases from the native isolates of white rot fungi Fomes fomentarius and/or Trametes versicolor, obtained from Czech forests, were used. From these, cross-linked enzyme aggregates (CLEA) were prepared and characterised when the experimental conditions were optimized. Based on the optimization steps, saturated ammonium sulphate solution (75 wt.%) was used as the precipitating agent, and different concentrations of glutaraldehyde as a cross-linking agent were investigated. CLEA aggregates formed under the optimal conditions showed higher catalytic efficiency and stabilities (thermal, pH, and storage, against denaturation) as well as high reusability compared to free laccase for both fungal strains. The best concentration of glutaraldehyde seemed to be 50 mM and higher efficiency of cross-linking was observed at a low temperature 4 °C. An insignificant increase in optimum pH for CLEA laccases with respect to free laccases for both fungi was observed. The results show that the optimum temperature for both free laccase and CLEA laccase was 35 °C for T. versicolor and 30 °C for F. fomentarius. The CLEAs retained 80% of their initial activity for Trametes and 74% for Fomes after 70 days of cultivation. Prepared cross-linked enzyme aggregates were also investigated for their decolourisation activity on malachite green, bromothymol blue, and methyl red dyes. Immobilised CLEA laccase from Trametes versicolor showed 95% decolourisation potential and CLEA from Fomes fomentarius demonstrated 90% decolourisation efficiency within 10 h for all dyes used. These results suggest that these CLEAs have promising potential in dye decolourisation. PMID:29295505

Dispersive liquid-liquid microextraction of quinolones in porcine blood: Optimization of extraction procedure and CE separation using experimental design.

PubMed

Vera-Candioti, Luciana; Teglia, Carla M; Cámara, María S

2016-10-01

A dispersive liquid-liquid microextraction procedure was developed to extract nine fluoroquinolones in porcine blood, six of which were quantified using a univariate calibration method. Extraction parameters including type and volume of extraction and dispersive solvent and pH, were optimized using a full factorial and a central composite designs. The optimum extraction parameters were a mixture of 250 μL dichloromethane (extract solvent) and 1250 μL ACN (dispersive solvent) in 500 μL of porcine blood reached to pH 6.80. After shaking and centrifugation, the upper phase was transferred in a glass tube and evaporated under N 2 steam. The residue was resuspended into 50 μL of water-ACN (70:30, v/v) and determined by CE method with DAD, under optimum separation conditions. Consequently, a tenfold enrichment factor can potentially be reached with the pretreatment, taking into account the relationship between initial sample volume and final extract volume. Optimum separation conditions were as follows: BGE solution containing equal amounts of sodium borate (Na 2 B 4 O 7 ) and di-sodium hydrogen phosphate (Na 2 HPO 4 ) with a final concentration of 23 mmol/L containing 0.2% of poly (diallyldimethylammonium chloride) and adjusted to pH 7.80. Separation was performed applying a negative potential of 25 kV, the cartridge was maintained at 25.0°C and the electropherograms were recorded at 275 nm during 4 min. The hydrodynamic injection was performed in the cathode by applying a pressure of 50 mbar for 10 s. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simultaneous removal of SO2 and NOx from flue gas by wet scrubbing using a urea solution.

PubMed

Li, Ge; Wang, Baodong; Xu, Wayne Qiang; Li, Yonglong; Han, Yifan; Sun, Qi

2018-03-27

Nitrogen oxides (NO x ) and sulfur dioxide (SO 2 ) are major air pollutants, so simultaneously removing them from gases emitted during fossil fuel combustion in stationary systems is important. Wet denitrification using urea is used for a wide range of systems. Additives have strong effects on wet denitrification using urea, and different mechanisms are involved and different effects found using different additives. In this study, the effects of different additives, initial urea concentrations, reaction temperatures, initial pH values, gas flow rates, and reaction times on the simultaneous desulfurization and denitrification efficiencies achieved using wet denitrification using urea were studied in single factor experiment. The optimum reaction conditions for desulfurization and denitrification were found. Desulfurization and denitrification efficiencies of 97.5% and 96.3%, respectively, were achieved at a KMnO 4 concentration 5 mmol/L, a reaction temperature of 70°C, initial urea solution pH 8, a urea concentration of 9%, and a gas flow rate of 40 L/h. The concentrations of the desulfurization and denitrification reaction products in the solution were determined. NO x was mainly transformed into N 2 , and the [Formula: see text] and [Formula: see text] concentrations in the solution became very low. The reactions involved in SO 2 and NO x removal using urea were analyzed from the thermodynamic viewpoint. Increasing the temperature was not conducive to the reactions but increased the rate constant, so an optimum temperature was determined. The simultaneous desulfurization and denitrification kinetics were calculated. The urea consumption and [Formula: see text], [Formula: see text], and [Formula: see text] generation reactions were all zero order. The [Formula: see text] generation rate was greater than the [Formula: see text] generation rate. The simultaneous desulfurization and denitrification process and mechanism were studied. The results provide reference data for performing flue gas desulfurization and denitrification in factories.

Comparative Study on Synergetic Degradation of a Reactive Dye Using Different Types of Fly Ash in Combined Adsorption and Photocatalysis

NASA Astrophysics Data System (ADS)

Giri Babu, P. V. S.; Swaminathan, G.

2016-09-01

A comprehensive study was carried out on four different fly ashes used as a catalyst for the degradation of Acid Red 1 using ultraviolet rays. These fly ashes are collected from different thermal power stations located at various places in India and having different chemical compositions. Three fly ashes are from lignite-based thermal power plants, and one is from the coal-based power plant. One fly ash is classified as Class F, two fly ashes are classified as Class C and remaining one is not conforming to ASTM C618 classification. X-Ray Fluorescence analysis was used to identify the chemical composition of fly ashes and SiO2, Al2O3, CaO, Fe2O3 and TiO2 were found to be the major elements present in different proportions. Various analysis were carried out on all the fly ashes like Scanning Electron Microscopy to identify the microphysical properties, Energy Dispersive X-Ray spectroscopy to quantify the elements present in the catalyst and X-Ray Diffraction to identify the catalyst phase analysis. The radical generated during the reaction was identified by Electron paramagnetic resonance spectroscopy. The parameters such as initial pH of the dye solution, catalyst dosage and initial dye concentration which influence the dye degradation efficiency were studied and optimised. In 60 min duration, the dye degradation efficiency at optimum parametric values of pH 2.5, initial dye concentration of 10 mg/L and catalyst dosage of 1.0 g/L using various fly ashes, i.e., Salam Power Plant, Barmer Lignite Power Plant, Kutch Lignite Power Plant and Neyveli Lignite Thermal Power plant (NLTP) were found to be 40, 60, 67 and 95 % respectively. The contribution of adsorption alone was 18 % at the above mentioned optimum parametric values. Among the above four fly ash NLTP fly ashes proved to be most efficient.

Halophilic Bacteria of Lunsu Produce an Array of Industrially Important Enzymes with Salt Tolerant Activity.

PubMed

Gupta, Sonika; Sharma, Parul; Dev, Kamal; Sourirajan, Anuradha

2016-01-01

The halophilic bacterial isolates SS1, SS2, SS3, SS5, and SS8 were characterized for production of industrially important enzymes like amylase, protease, lipase, and glutaminase. Halophilic bacterial isolates SS1 and SS3 exhibited salt dependent extracellular amylase and protease activities. Both the halophilic isolates SS1 and SS3 exhibited maximum amylase and protease activities in the presence of 1.5 and 1.0 M NaCl, respectively, with the optimum pH 8 and temperature 40°C. SS2 showed maximum extracellular protease and lipase activities in the presence of 0.75 M NaCl, at optimum pH of 7, and temperature 37°C. The glutaminase activity of SS3 increased with increase in concentration of NaCl up to 2.5 M. The optimum pH and temperature for L-glutaminase activity of SS3 was 8 and 40°C, respectively. The combined hydrolytic activities of these halophilic bacterial isolates can be used for bioconversion of organic materials to useful products.

Halophilic Bacteria of Lunsu Produce an Array of Industrially Important Enzymes with Salt Tolerant Activity

PubMed Central

Gupta, Sonika; Sharma, Parul; Dev, Kamal; Sourirajan, Anuradha

2016-01-01

The halophilic bacterial isolates SS1, SS2, SS3, SS5, and SS8 were characterized for production of industrially important enzymes like amylase, protease, lipase, and glutaminase. Halophilic bacterial isolates SS1 and SS3 exhibited salt dependent extracellular amylase and protease activities. Both the halophilic isolates SS1 and SS3 exhibited maximum amylase and protease activities in the presence of 1.5 and 1.0 M NaCl, respectively, with the optimum pH 8 and temperature 40°C. SS2 showed maximum extracellular protease and lipase activities in the presence of 0.75 M NaCl, at optimum pH of 7, and temperature 37°C. The glutaminase activity of SS3 increased with increase in concentration of NaCl up to 2.5 M. The optimum pH and temperature for L-glutaminase activity of SS3 was 8 and 40°C, respectively. The combined hydrolytic activities of these halophilic bacterial isolates can be used for bioconversion of organic materials to useful products. PMID:26885394

Degradation of reactive blue 13 using hydrodynamic cavitation: Effect of geometrical parameters and different oxidizing additives.

PubMed

Rajoriya, Sunil; Bargole, Swapnil; Saharan, Virendra Kumar

2017-07-01

Decolorization of reactive blue 13 (RB13), a sulphonated azo dye, was investigated using hydrodynamic cavitation (HC). The aim of research article is to check the influence of geometrical parameters (total flow area, the ratio of throat perimeter to its cross-sectional area, throat shape and size, etc.) and configuration of the cavitating devices on decolorization of RB13 in aqueous solution. For this purpose, eight cavitating devices i.e. Circular and slit venturi, and six orifice plates having different flow area and perimeter were used in the present work. Initially, the effects of various operating parameters such as solution pH, initial dye concentration, operating inlet pressure and cavitation number on the decolorization of RB13 have been investigated, and the optimum operating conditions were found. Kinetic analysis revealed that the decolorization and mineralization of RB13 using HC followed first order reaction kinetics. Almost 47% decolorization of RB13 was achieved using only HC with slit venturi as a cavitating device at an optimum inlet pressure of 0.4MPa and pH of the solution as 2.0. It has been found that in case of orifice plates, higher decolorization rate of 4×10 -3 min -1 was achieved using orifice plate 2 (OP2) which is having higher flow area and perimeter (α=2.28). The effect of process intensifying agents (hydrogen peroxide and ferrous sulphate) and different gaseous additives (oxygen and ozone) on the extent of decolorization of RB13 were also examined. Almost 66% decolorization of RB13 was achieved using HC combined with 2Lmin -1 of oxygen and in combination with ferrous sulphate (1:3). Nearly 91% decolorization was achieved using HC combined with H 2 O 2 at an optimum molar ratio (dye:H 2 O 2 ) of 1:20 while almost complete decolorization was observed in 15min using a combination of HC and ozone at 3gh -1 ozone feed rate. Maximum 72% TOC was removed using HC coupled with 3gh -1 ozone feed rate. Copyright © 2017 Elsevier B.V. All rights reserved.

Water defluoridation by aluminium oxide-manganese oxide composite material.

PubMed

Alemu, Sheta; Mulugeta, Eyobel; Zewge, Feleke; Chandravanshi, Bhagwan Singh

2014-08-01

In this study, aluminium oxide-manganese oxide (AOMO) composite material was synthesized, characterized, and tested for fluoride removal in batch experiments. AOMO was prepared from manganese(II) chloride and aluminium hydroxide. The surface area of AOMO was found to be 30.7m2/g and its specific density was determined as 2.78 g/cm3. Detailed investigation of the adsorbent by inductively coupled plasma-optical emission spectrometry, inductively coupled plasma-mass spectrometry, and ion chromatography (for sulphate only) showed that it is composed of Al, Mn, SO4, and Na as major components and Fe, Si, Ca, and Mg as minor components. Thermogravimetric analysis was used to study the thermal behaviour of AOMO. X-ray diffraction analysis showed that the adsorbent is poorly crystalline. The point of zero charge was determined as 9.54. Batch experiments (by varying the proportion of MnO, adsorbent dose, contact time, initial F concentration, and raw water pH) showed that fluoride removal efficiency ofAOMO varied significantly with percentage of MnO with an optimum value of about I11% of manganese oxide in the adsorbent. The optimum dose of the adsorbent was 4 g/L which corresponds to the equilibrium adsorption capacity of 4.8 mg F-/g. Both the removal efficiency and adsorption capacity showed an increasing trend with an increase in initial fluoride concentration of the water. The pH for optimum fluoride removal was found to be in the range between 5 and 7. The adsorption data were analysed using the Freundlich, Langmuir, and Dubinirn-Radushkevich models. The minimum adsorption capacity obtained from the non-linear Freundlich isotherm model was 4.94 mg F-/g and the maximum capacity from the Langmuir isotherm method was 19.2mg F-/g. The experimental data of fluoride adsorption on AOMO fitted well to the Freundlich isotherm model. Kinetic studies showed that the adsorption is well described by a non-linear pseudo-second-order reaction model with an average rate constant of 3.1 x 10(-2) g/min mg. It is concluded that AOMO is a highly promising adsorbent for the removal of excess fluoride from drinking water.

Purification and DNA-binding properties of RNA polymerase from Bacillus subtilis.

PubMed

Giacomoni, P U

1980-05-01

Four RNA-polymerizing activities having different subunit composition can be purified from uninfected and from SPO1-infected Bacillus subtilis. Lysozyme and sodium deoxycholate are used for lysing the cells. Polymin P is used for precipitating nucleic acids and DEAE-cellulose chromatography allows separation of enzymatic activity from the residual Polymin P. After these common steps, one can purify core + sigma + delta by chromatography on single-stranded DNA-agarose followed by gel filtration while pure core + sigma can be obtained by chromatography on double-stranded DNA cellulose. Core + delta is obtained by high-salt sucrose/glycerol gradient centrifugation. The host enzyme modified by the product of gene 28 of phage SPO1 can be purified from SPO1 infected cells by chromatography on DNA cellulose (or CNA agarose) followed by chromatography on phosphocellulose. The pH and salt dependance of the initial rate of RNA synthesis of core + sigma has been investigated using SPO1 and SPP1 DNA as templates. The optimum pH for the initial rate of transcription is 8.2 at 30 degrees C in 50 mM N,N-bis(2-hydroxyethyl)glycine buffer, and the optimum Na+ concentration is between 0.1 and 0.15 M. The kinetics of formation and of dissociation of non-filterable complexes between SPP1 DNA and core + sigma have been analyzed at different cationic concentrations. The value of the rate constant of dissociation in 0.1 M NaCl at 30 degrees C is kd = 2.16 x 10(-4) S-1. The value of the rate constant of association, under the same conditions, is ka = 5.5 x 10(8) M-1 S-1; this value is compatible with a diffusion-controlled reaction for promoter selection.

[Enzymatic conversion of tetradecanol in heterogenous phase by yeast-alcohol dehydrogenase].

PubMed

Rothe, U; Schöpp, W; Aurich, H

1976-01-01

Alcohol dehydrogenase from yeast converts long-chain primary alcohols not only in the dissolved state, but also at the surface of undissolved particles. Tetradecanol beads with a defined surface can be produced and employed as model substrate. The reaction rate was determined by the proton release accomplished in the reaction. The initial reaction rate depends on the enzyme concentration. The relation is nonlinear (vi = k-[e]0,4); the numerical value of the exponent (n = 0.4) argues in favour of a reaction occurring at the interface. The Lineweaver-Burk plots become linear if the substrate concentrations are based on the molar surface concentrations of the particles. The pH optimum for the reaction at the surface is displaced by 0.25 pH units towards the alkaline region (compared with ethanol as substrate). The activation energy of the reaction with tetradecanol beads as substrate is 30% lower than that for the ethanol oxydation.

Phosphonate removal from discharged circulating cooling water using iron-carbon micro-electrolysis.

PubMed

Zhou, Zhen; Qiao, Weimin; Lin, Yangbo; Shen, Xuelian; Hu, Dalong; Zhang, Jianqiao; Jiang, Lu-Man; Wang, Luochun

2014-01-01

Phosphonate is a commonly used corrosion and scale inhibitor for a circulating cooling water (CCW) system. Its discharge could cause eutrophication of receiving waters. The iron-carbon (Fe/C) micro-electrolysis technology was used to degrade and remove phosphonate from discharged CCW. The influences of initial pH, Fe/C ratio (FCR) and temperature on phosphonate removal were investigated in a series of batch tests and optimized by response surface methodology. The quadratic model of phosphonate removal was obtained with satisfactory degrees of fitness. The optimum conditions with total phosphorus removal efficiency of 95% were obtained at pH 7.0, FCR of 1.25, and temperature of 45 °C. The phosphonate removal mechanisms were also studied. Phosphonate removal occurred predominantly via two consecutive reactive phases: the degradation of phosphonate complexes (Ca-phosphonate) and the precipitation of Fe/C micro-electrolysis products (PO₄(3-), Ca²⁺ and Fe³⁺).

Apiaceae Family Plants as Low-Cost Adsorbents for the Removal of Lead Ion from Water Environment

NASA Astrophysics Data System (ADS)

Boontham, W.; Babel, S.

2017-06-01

Adsorbents prepared from the three selected plants from Apiaceae famaily commonly known as parsley, coriander and culantro were observed to remove lead from aqueous solutions. Batch experiments were conducted to study the effect of dosage, pH, contact time and agitation speed at 10 mg L-1 initial Pb(II) concentration. Results revealed that three selected plants showed high adsorption capacity for removal of lead from aqueous solutions. The maximum biosorption of Pb2+ was found to be more than 97% with 1.0 g/l dosage for all three adsorbents under optimum pH of 3-5. The adsorption equilibrium was established after about 1 hr. The equilibrium adsorption capacity of parsley and coriander were found to fit well with the Langmuir isotherm whereas the Freundlich isotherm was better fit for culantro. The studies showed that the adsorbents can be used for removing lead ions from contaminated waters.

Porous cellulose as promoter of oil production by the oleaginous yeast Lipomyces starkeyi using mixed agroindustrial wastes.

PubMed

Ganatsios, Vassilios; Koutinas, Athanasios A; Bekatorou, Argyro; Panagopoulos, Vassilios; Banat, Ibrahim M; Terpou, Antonia; Kopsahelis, Nikolaos

2017-11-01

Enhanced single cell oil (SCO) production by the oleaginous yeast Lipomyces starkeyi DSM 70296, immobilised on delignified porous cellulose, is reported. Pure glucose media were initially used. The effects of substrate pH and treatment temperature were evaluated, showing that 30°C and pH 5.0 were the optimum conditions for SCO production by the immobilised yeast. The immobilisation technique led to increased lipid accumulation and cell growth by 44% and 8%, respectively, in the glucose media, compared to free cells in suspension. This positive effect was also shown when low concentration mixed agro-industrial waste suspensions were used as substrates, leading to 85% enhanced SCO production in comparison with free cells. Higher fatty acid (HFA) analysis showed that yeast immobilisation led to increased formation of unsaturated HFAs (6%) and reduced saturated HFAs (5%) compared to free cells. Copyright © 2017 Elsevier Ltd. All rights reserved.

Enzymatic hydrolysis and fermentation of dilute acid pretreated cornstalk to biohydrogen

NASA Astrophysics Data System (ADS)

Pan, C. M.; Fan, Y. T.; Hou, H. W.

2010-03-01

The coupling method of acid pretreatment and enzymatic hydrolysis of cornstalk for hydrogen production was investigated in this study. Experimental results showed that temperature, pH and enzyme loading all had an individual significant influence on soluble sugar yield and Ps. The optimum condition for soluble sugar was close to that for Ps. The maximum hydrogen yield from cornstalk by anaerobic mixed microflora was 209.8 ml/g-TVS on the optimum enzymatic hydrolysis condition which was 52 °C of temperature, pH4.8 and 9.4 IU/g of enzyme loading.

Process optimization and analysis of product inhibition kinetics of crude glycerol fermentation for 1,3-Dihydroxyacetone production.

PubMed

Dikshit, Pritam Kumar; Padhi, Susant Kumar; Moholkar, Vijayanand S

2017-11-01

In present study, statistical optimization of biodiesel-derived crude glycerol fermentation to DHA by immobilized G. oxydans cells over polyurethane foam is reported. Effect of DHA (product) inhibition on crude glycerol fermentation was analyzed using conventional biokinetic models and new model that accounts for both substrate and product inhibition. Optimum values of fermentation parameters were: pH=4.7, temperature=31°C, initial substrate concentration=20g/L. At optimum conditions, DHA yield was 89% (17.83g/L). Effect of product inhibition on fermentation was trivial for DHA concentrations ≤30g/L. At higher concentrations (≥50g/L), kinetics and yield of fermentation showed marked reduction with sharp drop in V max and K S values. Inhibition effect was more pronounced for immobilized cells due to restricted transport of fermentation mixture across polyurethane foam. Retention of fermentation mixture in immobilized matrix resulted in higher localized DHA concentration that possibly enhanced inhibition effect. Copyright © 2017 Elsevier Ltd. All rights reserved.

Optimization of the photoelectrocatalytic oxidation of landfill leachate using copper and nitrate co-doped TiO2 (Ti) by response surface methodology

PubMed Central

Zhou, Shaoqi; Feng, Xinbin

2017-01-01

In this paper, a statistically-based experimental design with response surface methodology (RSM) was employed to examine the effects of functional conditions on the photoelectrocatalytic oxidation of landfill leachate using a Cu/N co-doped TiO2 (Ti) electrode. The experimental design method was applied to response surface modeling and the optimization of the operational parameters of the photoelectro-catalytic degradation of landfill leachate using TiO2 as a photo-anode. The variables considered were the initial chemical oxygen demand (COD) concentration, pH and the potential bias. Two dependent parameters were either directly measured or calculated as responses: chemical oxygen demand (COD) removal and total organic carbon (TOC) removal. The results of this investigation reveal that the optimum conditions are an initial pH of 10.0, 4377.98mgL-1 initial COD concentration and 25.0 V of potential bias. The model predictions and the test data were in satisfactory agreement. COD and TOC removals of 67% and 82.5%, respectively, were demonstrated. Under the optimal conditions, GC/MS showed 73 organic micro-pollutants in the raw landfill leachate which included hydrocarbons, aromatic compounds and esters. After the landfill leachate treatment processes, 38 organic micro-pollutants disappeared completely in the photoelectrocatalytic process. PMID:28671943

Degradation of 4-chloro 2-aminophenol using a novel combined process based on hydrodynamic cavitation, UV photolysis and ozone.

PubMed

Barik, Arati J; Gogate, Parag R

2016-05-01

The degradation of 4-chloro 2-aminophenol (4C2AP), an acute toxic organic compound, has been studied using different approaches based on the hydrodynamic cavitation (HC) with orifice plate as cavitating device, photolysis (UV) and ozonation (O3). The dependency of extent of degradation on operating parameters like operating pressure (2-5 bar), initial pH (3-8) and temperature (30-38 °C) have been established initially to maximize the efficacy of hydrodynamic cavitation. Subsequently the degradation has been studied using combined treatment strategies as HC+UV, HC+O3, UV+O3 and HC+UV+O3 at the established optimum parameters of operating temperature as 30 °C, initial pH of 6 and inlet pressure of 4 bar. The maximum extent of degradation as 96.85% and 73.6% reduction in TOC has been obtained using hydrodynamic cavitation in combination with UV photolysis and ozonation under the optimized operating conditions. The degradation products of 4C2AP have been identified using GC-MS. The present work has clearly established the efficacy of combined treatment approach (HC+UV+O3) for the removal of organic pollutant for the first time. Copyright © 2015 Elsevier B.V. All rights reserved.

pH Optimum of Hemagglutinin-Mediated Membrane Fusion Determines Sensitivity of Influenza A Viruses to the Interferon-Induced Antiviral State and IFITMs.

PubMed

Gerlach, Thomas; Hensen, Luca; Matrosovich, Tatyana; Bergmann, Janina; Winkler, Michael; Peteranderl, Christin; Klenk, Hans-Dieter; Weber, Friedemann; Herold, Susanne; Pöhlmann, Stefan; Matrosovich, Mikhail

2017-06-01

The replication and pathogenicity of influenza A viruses (IAVs) critically depend on their ability to tolerate the antiviral interferon (IFN) response. To determine a potential role for the IAV hemagglutinin (HA) in viral sensitivity to IFN, we studied the restriction of IAV infection in IFN-β-treated human epithelial cells by using 2:6 recombinant IAVs that shared six gene segments of A/Puerto Rico/8/1934 virus (PR8) and contained HAs and neuraminidases of representative avian, human, and zoonotic H5N1 and H7N9 viruses. In A549 and Calu-3 cells, viruses displaying a higher pH optimum of HA-mediated membrane fusion, H5N1-PR8 and H7N9-PR8, were less sensitive to the IFN-induced antiviral state than their counterparts with HAs from duck and human viruses, which fused at a lower pH. The association between a high pH optimum of fusion and reduced IFN sensitivity was confirmed by using HA point mutants of A/Hong Kong/1/1968-PR8 that differed solely by their fusion properties. Furthermore, similar effects of the viral fusion pH on IFN sensitivity were observed in experiments with (i) primary human type II alveolar epithelial cells and differentiated cultures of human airway epithelial cells, (ii) nonrecombinant zoonotic and pandemic IAVs, and (iii) preparations of IFN-α and IFN-λ1. A higher pH of membrane fusion and reduced sensitivity to IFN correlated with lower restriction of the viruses in MDCK cells stably expressing the IFN-inducible transmembrane proteins IFITM2 and IFITM3, which are known to inhibit viral fusion. Our results reveal that the pH optimum of HA-driven membrane fusion of IAVs is a determinant of their sensitivity to IFN and IFITM proteins. IMPORTANCE The IFN system constitutes an important innate defense against viral infection. Substantial information is available on how IAVs avoid detection by sensors of the IFN system and disable IFN signaling pathways. Much less is known about the ability of IAVs to tolerate the antiviral activity of IFN-induced cellular proteins. The IFN-induced proteins of the IFITM family block IAV entry into target cells and can restrict viral spread and pathogenicity. Here we show for the first time that the sensitivity of IAVs to the IFN-induced antiviral state and IFITM2 and IFITM3 proteins depends on the pH value at which the viral HA undergoes a conformational transition and mediates membrane fusion. Our data imply that the high pH optimum of membrane fusion typical of zoonotic IAVs of gallinaceous poultry, such as H5N1 and H7N9, may contribute to their enhanced virulence in humans. Copyright © 2017 American Society for Microbiology.

pH Optimum of Hemagglutinin-Mediated Membrane Fusion Determines Sensitivity of Influenza A Viruses to the Interferon-Induced Antiviral State and IFITMs

PubMed Central

Gerlach, Thomas; Hensen, Luca; Matrosovich, Tatyana; Bergmann, Janina; Winkler, Michael; Peteranderl, Christin; Klenk, Hans-Dieter; Herold, Susanne

2017-01-01

ABSTRACT The replication and pathogenicity of influenza A viruses (IAVs) critically depend on their ability to tolerate the antiviral interferon (IFN) response. To determine a potential role for the IAV hemagglutinin (HA) in viral sensitivity to IFN, we studied the restriction of IAV infection in IFN-β-treated human epithelial cells by using 2:6 recombinant IAVs that shared six gene segments of A/Puerto Rico/8/1934 virus (PR8) and contained HAs and neuraminidases of representative avian, human, and zoonotic H5N1 and H7N9 viruses. In A549 and Calu-3 cells, viruses displaying a higher pH optimum of HA-mediated membrane fusion, H5N1-PR8 and H7N9-PR8, were less sensitive to the IFN-induced antiviral state than their counterparts with HAs from duck and human viruses, which fused at a lower pH. The association between a high pH optimum of fusion and reduced IFN sensitivity was confirmed by using HA point mutants of A/Hong Kong/1/1968-PR8 that differed solely by their fusion properties. Furthermore, similar effects of the viral fusion pH on IFN sensitivity were observed in experiments with (i) primary human type II alveolar epithelial cells and differentiated cultures of human airway epithelial cells, (ii) nonrecombinant zoonotic and pandemic IAVs, and (iii) preparations of IFN-α and IFN-λ1. A higher pH of membrane fusion and reduced sensitivity to IFN correlated with lower restriction of the viruses in MDCK cells stably expressing the IFN-inducible transmembrane proteins IFITM2 and IFITM3, which are known to inhibit viral fusion. Our results reveal that the pH optimum of HA-driven membrane fusion of IAVs is a determinant of their sensitivity to IFN and IFITM proteins. IMPORTANCE The IFN system constitutes an important innate defense against viral infection. Substantial information is available on how IAVs avoid detection by sensors of the IFN system and disable IFN signaling pathways. Much less is known about the ability of IAVs to tolerate the antiviral activity of IFN-induced cellular proteins. The IFN-induced proteins of the IFITM family block IAV entry into target cells and can restrict viral spread and pathogenicity. Here we show for the first time that the sensitivity of IAVs to the IFN-induced antiviral state and IFITM2 and IFITM3 proteins depends on the pH value at which the viral HA undergoes a conformational transition and mediates membrane fusion. Our data imply that the high pH optimum of membrane fusion typical of zoonotic IAVs of gallinaceous poultry, such as H5N1 and H7N9, may contribute to their enhanced virulence in humans. PMID:28356532

Determination of optimum process parameters for peroxidase-catalysed treatment of bisphenol A and application to the removal of bisphenol derivatives.

PubMed

Yamada, Kazunori; Ikeda, Naoya; Takano, Yoko; Kashiwada, Ayumi; Matsuda, Kiyomi; Hirata, Mitsuo

2010-03-01

Systematic investigations were carried out to determine the optimum process parameters such as the hydrogen peroxide (H2O2) concentration, concentration and molar mass of poly(ethylene glycol) (PEG) as an additive, pH value, temperature and enzyme dose for treatment of bisphenol A (BPA) with horseradish peroxidase (HRP). The HRP-catalysed treatment of BPA was effectively enhanced by adding PEG, and BPA was completely converted into phenoxy radicals by HRP dose of 0.10 U/cm3. The optimum conditions for HRP-catalysed treatment of BPA at 0.3 mM was determined to be 0.3 mM for H2O2 and 0.10 mg/cm3 for PEG with a molar mass of 1.0 x 10(4) in a pH 6.0 buffer at 30 degrees C. Different kinds of bisphenol derivatives were completely or effectively treated by HRP under the optimum conditions determined for treatment of BPA, although the HRP dose was further increased as necessary for some of them. The aggregation of water-insoluble oligomers generated by the enzymatic radicalization and radical coupling reaction was enhanced by decreasing the pH values to 4.0 with HCl after the enzymatic treatment, and BPA and bisphenol derivatives were removed from aqueous solutions by filtering out the oligomer precipitates.

Modification of Natural Zeolite with Fe(III) and Its Application as Adsorbent Chloride and Carbonate ions

NASA Astrophysics Data System (ADS)

Suhartana; Sukmasari, Emmanuella; Azmiyawati, Choiril

2018-04-01

The aim of the research is to natural zeolite with Fe(III) using anion exchange process to improve the anion exchange capacity. Natural zeolite was activated using HNO3 1 N and then mixed with FeCl3 solution and refluxed followed by oven and calcination at a temperature of 550°C. The influence of Fe(III) to zeolite was characterized by FTIR while presence of Fe in zeolite characterized by AAS. Zeolite and Zeolite-Fe adsorption capacity of chloride and carbonate anions were determined through adsorption test by variation of pH and contact time. In advanced, and then to determining the Fe adsorbed concentration at Zeolite using UV-Vis spectrophotometer. FTIR analysis result showed that the addition of Fe does not affect the zeolite’s structure but change the intensity of the zeolite spectra. The Fe concentration in Zeolite-Fe of 714 mg L-1, indicate that Fe was present in the zeolite. Both Zeolite and Zeolite-Fe adsorbtion results showed that optimum pH of Chloride anion is 2, with adsorption capacity 2,33 x 10-3 gg-1 and optimum contact time is 8 minutes. While Zeolite and Zeolite-Fe adsorbtion results showed that optimum pH of Carbonate anion is 5, with adsorption capacity 5,31 x 10-3 gg-1 and optimum contact time is 8 minutes.

Contemplating the feasibility of vermiculate blended chitosan for heavy metal removal from simulated industrial wastewater

NASA Astrophysics Data System (ADS)

Prakash, N.; Soundarrajan, M.; Arungalai Vendan, S.; Sudha, P. N.; Renganathan, N. G.

2017-12-01

Wastewater contaminated by heavy metals pose great challenges as they are non biodegradable, toxic and carcinogenic to the soil and aquifers. Vermiculite blended with chitosan have been used to remove Cr(VI) and Cd(II) from the industrial wastewater. The results indicate that the vermiculite blended with chitosan adsorb Cr(VI) and Cd(II) from industrial waste water. Batch adsorption experiments were performed as a function of pH 5.0 and 5.5 respectively for chromium and cadmium. The adsorption rate was observed to be 72 and 71 % of chromium and cadmium respectively. The initial optimum contact time for Cr(VI) was 300 min with 59.2 % adsorption and 300 min for Cd(II) with 71.5 % adsorption. Whereas, at 4-6 there is saturation, increasing the solid to liquid ratio for chitosan biopolymers increases the number of active sites available for adsorption. The optimum pH required for maximum adsorption was found to be 5.0 and 5.5 for chromium and cadmium respectively. The experimental equilibrium adsorption data were fitted using Langmuir and Freundlich equations. It was observed that adsorption kinetics of both the metal ions on vermiculite blended chitosan is well be analyzed with pseudo-second-order model. The negative free energy change of adsorption indicates that the process was spontaneous and vermiculite blended chitosan was a favourable adsorbent for both the metals.

Molecular Imprinted Polymer of Methacrylic Acid Functionalised β-Cyclodextrin for Selective Removal of 2,4-Dichlorophenol

PubMed Central

Surikumaran, Hemavathy; Mohamad, Sharifah; Sarih, Norazilawati Muhamad

2014-01-01

This work describes methacrylic acid functionalized β-cyclodextrin (MAA-βCD) as a novel functional monomer in the preparation of molecular imprinted polymer (MIP MAA-βCD) for the selective removal of 2,4-dichlorophenol (2,4-DCP). The polymer was characterized using Fourier Transform Infrared (FTIR) spectroscopy, Brunauer-Emmett-Teller (BET) and Field Emission Scanning Electron Microscopy (FESEM) techniques. The influence of parameters such as solution pH, contact time, temperature and initial concentrations towards removal of 2,4-DCP using MIP MAA-βCD have been evaluated. The imprinted material shows fast kinetics and the optimum pH for removal of 2,4-DCP is pH 7. Compared with the corresponding non-imprinted polymer (NIP MAA-βCD), the MIP MAA-βCD exhibited higher adsorption capacity and outstanding selectivity towards 2,4-DCP. Freundlich isotherm best fitted the adsorption equilibrium data of MIP MAA-βCD and the kinetics followed a pseudo-second-order model. The calculated thermodynamic parameters showed that adsorption of 2,4-DCP was spontaneous and exothermic under the examined conditions. PMID:24727378

Purification and Properties of Acid Stable Xylanases from Aspergillus kawachii.

PubMed

Ito, K; Ogasawara, H; Sugimoto, T; Ishikawa, T

1992-01-01

Five extracellular endo-xylanases were recognized in the culture broth of shochu koji mold (Aspergillus kawachii, IFO 4308), and three major xylanases (XylA, XylB, and XylC) were purified and characterized. The molecular masses of XylA, XylB, and XylC were 35,000, 26,000, and 29,000, and isoelectric points were pH 6.7, 4.4, and 3.5, respectively. Amino acid compositions and other properties were studied and these three xylanases were found to be greatly different in their properties. These three xylanases, XylA, XylB, and XylC, were stable between pH 3-10, 3-10, and 1-9 and the optimum pHs were 5.5, 4.5, and 2.0, respectively. Consequently, these xylanases were acid stable xylanases, especially XylC was an acidophilic xylanase (acid xylanase). These xylanases produced various xylooligosaccharides including xylose from xylan and the main product was xylobiose in all xylanases. The production of acid xylanase (XylC) was enhanced with a low initial pH of the medium.

Application of response surface methodology for optimization of natural organic matter degradation by UV/H2O2 advanced oxidation process

PubMed Central

2014-01-01

Background In this research, the removal of natural organic matter from aqueous solutions using advanced oxidation processes (UV/H2O2) was evaluated. Therefore, the response surface methodology and Box-Behnken design matrix were employed to design the experiments and to determine the optimal conditions. The effects of various parameters such as initial concentration of H2O2 (100–180 mg/L), pH (3–11), time (10–30 min) and initial total organic carbon (TOC) concentration (4–10 mg/L) were studied. Results Analysis of variance (ANOVA), revealed a good agreement between experimental data and proposed quadratic polynomial model (R2 = 0.98). Experimental results showed that with increasing H2O2 concentration, time and decreasing in initial TOC concentration, TOC removal efficiency was increased. Neutral and nearly acidic pH values also improved the TOC removal. Accordingly, the TOC removal efficiency of 78.02% in terms of the independent variables including H2O2 concentration (100 mg/L), pH (6.12), time (22.42 min) and initial TOC concentration (4 mg/L) were optimized. Further confirmation tests under optimal conditions showed a 76.50% of TOC removal and confirmed that the model is accordance with the experiments. In addition TOC removal for natural water based on response surface methodology optimum condition was 62.15%. Conclusions This study showed that response surface methodology based on Box-Behnken method is a useful tool for optimizing the operating parameters for TOC removal using UV/H2O2 process. PMID:24735555

Applying Central Composite Design and Response Surface Methodology to Optimize Growth and Biomass Production of Haemophilus influenzae Type b.

PubMed

Momen, Seyed Bahman; Siadat, Seyed Davar; Akbari, Neda; Ranjbar, Bijan; Khajeh, Khosro

2016-06-01

Haemophilus influenzae type b (Hib) is the leading cause of bacterial meningitis, otitis media, pneumonia, cellulitis, bacteremia, and septic arthritis in infants and young children. The Hib capsule contains the major virulence factor, and is composed of polyribosyl ribitol phosphate (PRP) that can induce immune system response. Vaccines consisting of Hib capsular polysaccharide (PRP) conjugated to a carrier protein are effective in the prevention of the infections. However, due to costly processes in PRP production, these vaccines are too expensive. To enhance biomass, in this research we focused on optimizing Hib growth with respect to physical factors such as pH, temperature, and agitation by using a response surface methodology (RSM). We employed a central composite design (CCD) and a response surface methodology to determine the optimum cultivation conditions for growth and biomass production of H. influenzae type b. The treatment factors investigated were initial pH, agitation, and temperature, using shaking flasks. After Hib cultivation and determination of dry biomass, analysis of experimental data was performed by the RSM-CCD. The model showed that temperature and pH had an interactive effect on Hib biomass production. The dry biomass produced in shaking flasks was about 5470 mg/L, which was under an initial pH of 8.5, at 250 rpm and 35° C. We found CCD and RSM very effective in optimizing Hib culture conditions, and Hib biomass production was greatly influenced by pH and incubation temperature. Therefore, optimization of the growth factors to maximize Hib production can lead to 1) an increase in bacterial biomass and PRP productions, 2) lower vaccine prices, 3) vaccination of more susceptible populations, and 4) lower risk of Hib infections.

Degradation and mineralization of Bisphenol A (BPA) in aqueous solution using advanced oxidation processes: UV/H2O2 and UV/S2O8(2-) oxidation systems.

PubMed

Sharma, Jyoti; Mishra, I M; Kumar, Vineet

2015-06-01

This work reports on the removal and mineralization of an endocrine disrupting chemical, Bisphenol A (BPA) at a concentration of 0.22 mM in aqueous solution using inorganic oxidants (hydrogen peroxide, H2O2 and sodium persulfate, Na2S2O8;S2O8(2-)) under UV irradiation at a wavelength of 254 nm and 40 W power (Io = 1.26 × 10(-6) E s(-1)) at its natural pH and a temperature of 29 ± 3 °C. With an optimum persulfate concentration of 1.26 mM, the UV/S2O8(2-) process resulted in ∼95% BPA removal after 240 min of irradiation. The optimum BPA removal was found to be ∼85% with a H2O2 concentration of 11.76 mM. At higher concentrations, either of the oxidants showed an adverse effect because of the quenching of the hydroxyl or sulfate radicals in the BPA solution. The sulfate-based oxidation process could be used over a wider initial pH range of 3-12, but the hydroxyl radical-based oxidation of BPA should be carried out in the acidic pH range only. The water matrix components (bicarbonate, chloride and humic acid) showed higher scavenging effect in hydroxyl radical-based oxidation than that in the sulfate radical-based oxidation of BPA. UV/S2O8(2-) oxidation system utilized less energy (307 kWh/m(3)) EE/O in comparison to UV/H2O2 system (509 kWh/m(3)) under optimum operating conditions. The cost of UV irradiation far outweighed the cost of the oxidants in the process. However, the total cost of treatment of persulfate-based system was much lower than that of H2O2-based oxidation system. Copyright © 2015 Elsevier Ltd. All rights reserved.

Digestive enzymes of the Californian two-spot octopus, Octopus bimaculoides (Pickford and McConnaughey, 1949).

PubMed

Ibarra-García, Laura Elizabeth; Tovar-Ramírez, Dariel; Rosas, Carlos; Campa-Córdova, Ángel Isidro; Mazón-Suástegui, José Manuel

2018-01-01

Octopus bimaculoides is an important commercially fished species in the California Peninsula with aquaculture potential; however, to date limited information is available regarding its digestive physiology. The objective of this study was focused on biochemically characterizing the main enzymes involved in the digestion of O. bimaculoides. Optimum pH, temperature and thermostability were determined for amylases, lipases, trypsin and chymotrypsin; optimum pH and protease inhibitor effect were assessed for acidic and alkaline proteases, and the effect of divalent ions on trypsin and chymotrypsin activity was evaluated in enzymatic extracts from the digestive (DG) and salivary glands (SG) and crop gastric juices (GJ). High amylase activity was detected in GD and GJ whereas this activity is very low in other cephalopods. Salivary glands had the greatest activity in most of the enzyme groups, showing the importance of this organ in digestion. Optimum pH was different depending on the organ and enzyme analyzed. The optimum pH in DG was 3 showing the predominance of acidic proteases in the digestion process. All enzymes were resistant and stable at high temperatures in contrast with other marine species. Trypsin and chymotrypsin activity were highly incremented with the presence of Mg 2+ , Co 2+ , Cu 2+ and Zn 2+ in some tissues. The inhibitor assay showed the importance of serine proteases, metalloproteases and aspartic proteases in the digestive process of this species. This study is the first in assessing the main digestive enzymes of O. bimaculoides and in remarking the importance of other digestive enzyme groups besides proteases in octopuses. Copyright © 2017 Elsevier Inc. All rights reserved.

Bacterial degradation of polychlorinted biphenyls in sludge from an industrial sewer lagoon

NASA Technical Reports Server (NTRS)

Kim, W. S.; Takacs, A. M.; Kuivinen, D. E.

1983-01-01

A laboratory experiment was conducted to determine if polychlorinated biphenyls (PCB's) found in an industrial sewer sludge can be effectively degraded by mutant bacteria. The aerated sludge was inoculated daily with mutant bacteria in order to augment the existing bacteria with bacteria that were considered to be capable of degrading PCB's. The pH, nitrogen, and phosphorus levels were monitored daily to maintain an optimum growing medium for the bacteria. A gas chromatographic method was used to determine the PCB concentrations of the sludge initially and also throughout the experiment. Results and discussion of the bacterial treatment of polychlorinated biphenyls are presented.

Construction of an amperometric ascorbate biosensor using epoxy resin membrane bound Lagenaria siceraria fruit ascorbate oxidase.

PubMed

Pundir, C S; Chauhan, Nidhi; Jyoti

2011-06-01

Ascorbate oxidase purified from Lagenaria siceraria fruit was immobilized onto epoxy resin "Araldite" membrane with 79.4% retention of initial activity of free enzyme. The biosensor showed optimum response within 15s at pH 5.8 and 35°C, which was directly proportional to ascorbate concentration ranging from 1-100μM. There was a good correlation (R(2) = 0.99) between serum ascorbic acid values by standard enzymic colorimetric method and the present method. The enzyme electrode was used for 200 times without considerable loss of activity during the span of 90 days when stored at 4°C.

Optimising the biogas production from leather fleshing waste by co-digestion with MSW.

PubMed

Shanmugam, P; Horan, N J

2009-09-01

Waste from the leather industry, known as limed leather fleshing (LF), has a low C:N (3.2) and an alkaline pH of 11.4. This is a major disadvantage for anaerobic digestion due to ammonia toxicity for methanogenesis. This study describes co-digestion of LF with biodegradable fraction of municipal solids waste optimised over a range of C:N and pH to minimise ammonia and to maximise biogas yield. The optimum conditions were found with a blend that provided C:N of 15 and pH of 6.5 and the cumulative biogas yield increased from 560 mL using LF fraction alone, to 6518 mL with optimum blend. At higher pH of 8.5, unionised ammonia was high (2473 mg L(-1)) coincided with poor biogas yield (47 m Ld(-1)) that confirms ammonia toxicity. By contrast at a pH of 4.5 the ammonia was minimum (510 mg L(-1)), but high VFA (26,803 mg L(-1)) inhibited the methanogens. Biomass activity measured using ATP correlated well with biogas yield as reported previously.

Enhanced stability and catalytic activity of immobilized α-amylase on modified Fe3O4 nanoparticles for potential application in food industries

NASA Astrophysics Data System (ADS)

Hosseinipour, Seyyedeh Leila; Khiabani, Mahmoud Sowti; Hamishehkar, Hamed; Salehi, Roya

2015-09-01

Enzymes play an essential role in catalyzing various reactions. However, their instability upon repetitive/prolonged use, elevated temperature, acidic or alkaline pH remains an area of concern. α-Amylase, a widely used enzyme in food industries for starch hydrolysis, was covalently immobilized on the surface of two developed matrices, amino-functionalized silica-coated magnetite nanoparticles (AFSMNPs) alone and covered with chitosan. The synthesis steps and characterizations of NPs were examined by FT-IR, VSM, and SEM. Modified nanoparticles with average diameters of 20-80 nm were obtained. Enzyme immobilization efficiencies of 89 and 74 were obtained for AFSMNPs and chitosan-coated AFSMNPs, respectively. The optimum pH obtained was 6.5 and 8.0 for the enzyme immobilized on AFSMNPs and chitosan-coated AFSMNPs, respectively. Optimum temperature for the immobilized enzyme shifted toward higher temperatures. Considerable enhancements in thermal stabilities were observed for the immobilized enzyme at elevated temperatures up to 80 °C. A frequent use experiment demonstrated that the immobilized enzyme retained 74 and 85 % of its original activity even after 20 times of repeated use in AFSMNPs and chitosan-coated AFSMNPs, respectively. Storage stability demonstrated that free enzyme lost its activity completely within 30 days. But, immobilized enzyme on AFSMNPs and chitosan-coated AFSMNPs preserved 65.73 and 78.63 % of its initial activity, respectively, after 80 days of incubation. In conclusion, a substantial improvement in the performance of the immobilized enzyme with reference to the free enzyme was obtained. Furthermore, the relative activities of immobilized enzyme are superior than free enzyme over the broader pH and temperature ranges.

Artificial intelligence and regression analysis for Cd(II) ion biosorption from aqueous solution by Gossypium barbadense waste.

PubMed

Fawzy, Manal; Nasr, Mahmoud; Nagy, Heba; Helmi, Shacker

2018-02-01

In this study, batch biosorption experiments were conducted to determine the removal efficiency of Cd(II) ion from aqueous solutions by Gossypium barbadense waste. The biosorbent was characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) connected with energy dispersive X-ray (EDX). The sorption mechanism was described by complexation/chelation of Cd 2+ with the functional groups of O-H, C=O, -COO-, and C-O, as well as, cation-exchange with Mg 2+ and K + . At initial Cd(II) ion concentration (C o ), 50 mg/L, the adsorption equilibrium of 89.2% was achieved after 15 min under the optimum experimental factors of pH 6.0, biosorbent dosage 10 g/L, and particle diameter 0.125-0.25 mm. Both Langmuir and Freundlich models fitted well to the sorption data, suggesting the co-existence of monolayer coverage along with heterogenous surface biosorption. Artificial neural network (ANN) with a structure of 5-10-1 was performed to predict the Cd(II) ion removal efficiency. The ANN model provided high fit (R 2 0.923) to the experimental data and indicated that C o was the most influential input. A pure-quadratic model was developed to determine the effects of experimental factors on Cd(II) ion removal efficiency, which indicated the limiting nature of pH and biosorbent dosage on Cd(II) adsorption. Based on the regression model (R 2 0.873), the optimum experimental factors were pH 7.61, biosorbent dosage 24.74 g/L, particle size 0.125-0.25 mm, and adsorption time 109.77 min, achieving Cd 2+ removal of almost 100% at C o 50 mg/L.

Low-temperature thermal pre-treatment of municipal wastewater sludge: Process optimization and effects on solubilization and anaerobic degradation.

PubMed

Nazari, Laleh; Yuan, Zhongshun; Santoro, Domenico; Sarathy, Siva; Ho, Dang; Batstone, Damien; Xu, Chunbao Charles; Ray, Madhumita B

2017-04-15

The present study examines the relationship between the degree of solubilization and biodegradability of wastewater sludge in anaerobic digestion as a result of low-temperature thermal pre-treatment. The main effect of thermal pre-treatment is the disintegration of cell membranes and thus solubilization of organic compounds. There is an established correlation between chemical oxygen demand (COD) solubilization and temperature of thermal pre-treatment, but results of thermal pre-treatment in terms of biodegradability are not well understood. Aiming to determine the impact of low temperature treatments on biogas production, the thermal pre-treatment process was first optimized based on an experimental design study on waste activated sludge in batch mode. The optimum temperature, reaction time and pH of the process were determined to be 80 °C, 5 h and pH 10, respectively. All three factors had a strong individual effect (p < 0.001), with a significant interaction effect for temp. pH 2 (p = 0.002). Thermal pre-treatments, carried out on seven different municipal wastewater sludges at the above optimum operating conditions, produced increased COD solubilization of 18.3 ± 7.5% and VSS reduction of 27.7 ± 12.3% compared to the untreated sludges. The solubilization of proteins was significantly higher than carbohydrates. Methane produced in biochemical methane potential (BMP) tests, indicated initial higher rates (p = 0.0013) for the thermally treated samples (k hyd up to 5 times higher), although the ultimate methane yields were not significantly affected by the treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Identification and characterization of yeasts causing chalk mould defects on par-baked bread.

PubMed

Deschuyffeleer, N; Audenaert, K; Samapundo, S; Ameye, S; Eeckhout, M; Devlieghere, F

2011-08-01

Pichia anomala, Hyphopichia burtonii and Saccharomycopsis fibuligera are spoilage yeasts causing chalk mould defects on par-baked breads packaged under modified atmosphere. The first objective of this study was to identify yeasts isolated from spoiled par-baked breads by means of a RAPD protocol and to determine the dominant spoilers amongst identified strains. The second objective was to determine the effects of water activity (a(w)) and pH value on the growth rates and lag phase durations of P. anomala, H. burtonii and S. fibuligera. 95% of the yeasts tested were identified as P. anomala and 5% as S. fibuligera, H. burtonii was not detected. In order to investigate the effect of a(w) and pH the growth of the three yeasts was tested within an a(w) range of 0.88-0.98 and a pH range of 2.8-8.0. P. anomala was able to grow from pH 2.8 to 8 without a clear optimum. S. fibuligera and H. burtonii showed a pH optimum for growth of 5. The optimum water activity for growth was different for the three strains and varied between 0.96 and 0.98. These growth data were further used to develop secondary models that describe the relationship between a(w) and the radial or colony growth rate (g, mm/d) or the lag phase duration (λ, d). The identification of the spoilage organisms and a good understanding of the effects of a(w) and pH on the growth behavior is essential for future development of adequate conservation strategies against chalk mould defects. Copyright © 2011 Elsevier Ltd. All rights reserved.

Effect of complexation conditions on microcapsulation of Lactobacillus acidophilus in xanthan-chitosan polyelectrolyte complex gels.

PubMed

Chen, He; Song, Yajuan; Liu, Nina; Wan, Hongchang; Shu, Guowei; Liao, Na

2015-01-01

Lactobacillus acidophilus has become increasingly popular because of their beneficial effects on health of their host, and are called proboscis. In order to exert beneficial effects for probiotics, they must be able to tolerate the acidic conditions of the stomach environment and the bile in the small intestine. Microencapsulated form has received reasonable attention, since it can protect probiotic organisms against an unfavourable environment, and to allow their release in a viable and metabolically active state in the intestine. The aim of this study was to investigate some factores, such as chitosan solution pH and concentration, xanthan concentration, cell suspension-xanthan ratio, mixed bacteria glue liquid-chitosan ratio, which impacted the process of microencapsulation of L. acidophilus. In this study, L. acidophilus was immobilized with xanthan⁄chitosan gel using extrusion method. The viable counts and encapsulation yield of L. acidophilus encapsulated in different chitosan solution pH (4.5, 5, 5.5 and 6), in different chitosan concentration (0.5%, 0.7%, 0.9% and 1.1%), in different xanthan concentration (0.5%, 0.7%, 0.9% and 1.1%), in different cell suspension-xanthan ratios (1:5, 1:10, 1:15 and 1:20), in different mixed bacteria glue liquid-chitosan ratios (1:3, 1:4, 1:5 and 1:6), have been investigated by single factor experiment method. The optimum conditions of microencapsulated L. acidophilus have been observed. The optimum chitosan solution pH for L. acidophilus was 5.5; the optimum chitosan concentration was 0.9%; the optimum xanthan concentration was 0.7%; the optimum cell suspension-xanthan ratio was 1:10; the optimum mixed bacteria glue liquid-chitosan ratio was 1:3. These results will be helpful to further optimize the process of L. acidophilus microencapsulation, and provide reference for obtaining higher viable counts and entrapped yield of L. acidophilus microcapsules.

Removal of phenol from synthetic wastewater using carbon-mineral composite: Batch mechanisms and composition study

NASA Astrophysics Data System (ADS)

Kamaruddin, Mohamad Anuar; Alrozi, Rasyidah; Aziz, Hamidi Abdul; Han, Tan Yong; Yusoff, Mohd Suffian

2017-09-01

This study investigates the treatability of composite adsorbent made from waste materials and minerals which is widely available in Malaysia. The composite adsorbent was prepared based on wet attrition method which focuses on the determination of optimum dosage of each of raw materials amount by conventional design of experiment work. Zeolite, activated carbon, rice husk and limestone were ground to obtained particle size of 150 µm. 45.94% zeolite, 15.31% limestone, 4.38% activated carbon, 4.38% rice husk carbon and 30% of ordinary Portland cement (OPC). The mixture was mixed together under pre-determined mixing time. About 60% (by weight) of water was added and the mixture paste was allowed to harden for 24 hours and then submersed in water for three days for curing. Batch experimental study was performed on synthetic dissolving a known amount of solid crystal phenol with distilled water into the volumetric flasks. From the batch experimental study, it was revealed that the optimum shaking speed for removal of phenol was 200 rpm. The removal efficiency was 65%. The optimum shaking time for removing phenol was 60 minutes; the percentage achieved was 55%. The removal efficiency increased with the increased of the amount of composite adsorbent. The removal efficiency for optimum adsorbent dosage achieved 86%. Furthermore, the influence of pH solution was studied. The optimum pH for removing phenol was pH 6, with the removal percentage of 95%. The results implies that carbon-mineral based composite adsorbent is promising replacement for commercial adsorbent that provides alternative source for industrial adsorption application in various types of effluent treatment system.

Development of passion fruit juice beverage

NASA Astrophysics Data System (ADS)

Zhu, Xiang-hao; Duan, Zhen-hua; Yang, Yu-xia; Huang, Xin-hui; Xu, Cheng-ling; Huang, Zhi-zhuo

2017-12-01

In this experiment, the whole fruit of passion fruit was used as raw material. The effects of the ratio of material to liquid (RML), the amount of sucrose addition and the pH on the quality of passion fruit juice beverage were investigated by single factor test. And the optimum process conditions of passion fruit juice beverage were determined by orthogonal test. The results show that the optimum process paramenters were as follow: RML was 1:3, pH was 4.0 and sucrose addition was 8%. Under such optimal conditions, the color of passion fruit juice beverage was red, the flavor of passion fruit was rich and it tasted pleasant.

Combined Homogeneous Surface Diffusion Model - Design of experiments approach to optimize dye adsorption considering both equilibrium and kinetic aspects.

PubMed

Muthukkumaran, A; Aravamudan, K

2017-12-15

Adsorption, a popular technique for removing azo dyes from aqueous streams, is influenced by several factors such as pH, initial dye concentration, temperature and adsorbent dosage. Any strategy that seeks to identify optimal conditions involving these factors, should take into account both kinetic and equilibrium aspects since they influence rate and extent of removal by adsorption. Hence rigorous kinetics and accurate equilibrium models are required. In this work, the experimental investigations pertaining to adsorption of acid orange 10 dye (AO10) on activated carbon were carried out using Central Composite Design (CCD) strategy. The significant factors that affected adsorption were identified to be solution temperature, solution pH, adsorbent dosage and initial solution concentration. Thermodynamic analysis showed the endothermic nature of the dye adsorption process. The kinetics of adsorption has been rigorously modeled using the Homogeneous Surface Diffusion Model (HSDM) after incorporating the non-linear Freundlich adsorption isotherm. Optimization was performed for kinetic parameters (color removal time and surface diffusion coefficient) as well as the equilibrium affected response viz. percentage removal. Finally, the optimum conditions predicted were experimentally validated. Copyright © 2017 Elsevier Ltd. All rights reserved.

Removal of hexavalent chromium by using red mud activated with cetyltrimethylammonium bromide.

PubMed

Li, Deliang; Ding, Ying; Li, Lingling; Chang, Zhixian; Rao, Zhengyong; Lu, Ling

2015-01-01

The removal of hexavalent chromium [Cr(VI)] from aqueous solution by using red mud activated with cetyltrimethylammonium bromide (CTAB) was studied. The optimum operation parameters, such as CTAB concentration, pH values, contact time, and initial Cr(VI) concentration, were investigated. The best concentration of CTAB for modifying red mud was found to be 0.50% (mCTAB/VHCl,0.6 mol/L). The lower pH (<2) was found to be much more favourable for the removal of Cr(VI). Red mud activated with CTAB can greatly improve the removal ratio of Cr(VI) as high as four times than that of original red mud. Adsorption equilibrium was reached within 30 min under the initial Cr(VI) concentration of 100 mg L(-1). The isotherm data were analysed using Langmuir and Freundlich models. The adsorption of Cr(VI) on activated red mud fitted well to the Langmuir isotherm model, and the maximum adsorption capacity was estimated as 22.20 mg g(-1) (Cr/red mud). The adsorption process could be well described using the pseudo-second-order model. The result shows that activated red mud is a promising agent for low-cost water treatment.

Lead removal by Spirulina platensis biomass.

PubMed

Al-Homaidan, Ali A; Al-Abbad, Aljawharah F; Al-Hazzani, Amal A; Al-Ghanayem, Abdullah A; Alabdullatif, Jamila A

2016-01-01

In this investigation, we report on the biosorption of Pb (II) from aqueous solutions by the nonliving biomass of the micro-alga (cyanobacterium) Spirulina platensis. Propagation of the micro-alga was carried out in outside oblong raceway ponds. The biomass was cleaned, dried and used for the investigation. The effects of pH, adsorbent dose, temperature, initial concentration of Pb (II), and contact time on the adsorption of lead by the dry biomass were studied. The experiments were carried out in 250 ml conical flasks containing 100 ml of test solutions using an orbital incubator at 150 rpm. Concentrations of the metal before and after the experiments were measured using Atomic Absorption Spectrophotometer. Very high levels of Pb (II) removal (>91%) were obtained. The optimum conditions for maximal adsorption by S. platensis were found to be pH 3; 2 g of adsorbent dose; incubation at 26°C; 100 mg/l of lead initial concentration and 60 minutes of contact time. The experimental data fitted well with Freundlich isotherm equation with R(2) values greater than 0.97. Based on our results, we recommend the utilization of S. platensis biomass for heavy metal removal from aqueous solutions.

Optimization of process variables for decolorization of Disperse Yellow 211 by Bacillus subtilis using Box-Behnken design.

PubMed

Sharma, Praveen; Singh, Lakhvinder; Dilbaghi, Neeraj

2009-05-30

Decolorization of textile azo dye Disperse Yellow 211 (DY 211) was carried out from simulated aqueous solution by bacterial strain Bacillus subtilis. Response surface methodology (RSM), involving Box-Behnken design matrix in three most important operating variables; temperature, pH and initial dye concentration was successfully employed for the study and optimization of decolorization process. The total 17 experiments were conducted in the study towards the construction of a quadratic model. According to analysis of variance (ANOVA) results, the proposed model can be used to navigate the design space. Under optimized conditions the bacterial strain was able to decolorize DY 211 up to 80%. Model indicated that initial dye concentration of 100 mgl(-1), pH 7 and a temperature of 32.5 degrees C were found optimum for maximum % decolorization. Very high regression coefficient between the variables and the response (R(2)=0.9930) indicated excellent evaluation of experimental data by polynomial regression model. The combination of the three variables predicted through RSM was confirmed through confirmatory experiments, hence the bacterial strain holds a great potential for the treatment of colored textile effluents.

Kinetics and Thermodynamics of Reserpine Adsorption onto Strong Acidic Cationic Exchange Fiber

PubMed Central

Guo, Zhanjing; Liu, Xiongmin; Huang, Hongmiao

2015-01-01

The kinetics and thermodynamics of the adsorption process of reserpine adsorbed onto the strong acidic cationic exchange fiber (SACEF) were studied by batch adsorption experiments. The adsorption capacity strongly depended on pH values, and the optimum reserpine adsorption onto the SACEF occurred at pH = 5 of reserpine solution. With the increase of temperature and initial concentration, the adsorption capacity increased. The equilibrium was attained within 20 mins. The adsorption process could be better described by the pseudo-second-order model and the Freundlich isotherm model. The calculated activation energy Ea was 4.35 kJ/mol. And the thermodynamic parameters were: 4.97<ΔH<7.44 kJ/mol, -15.29<ΔG<-11.87 kJ/mol and 41.97<ΔS<47.35 J/mol·K. The thermodynamic parameters demonstrated that the adsorption was an endothermic, spontaneous and feasible process of physisorption within the temperature range between 283 K and 323 K and the initial concentration range between 100 mg/L and 300 mg/L. All the results showed that the SACEF had a good adsorption performance for the adsorption of reserpine from alcoholic solution. PMID:26422265

Nickel(II) biosorption from aqueous solutions by shrimp head biomass.

PubMed

Hernández-Estévez, Alejandro; Cristiani-Urbina, Eliseo

2014-11-01

The present study evaluates the capacity of shrimp (Farfantepenaeus aztecus) head to remove toxic Ni(II) ions from aqueous solutions. Relevant parameters that could affect the biosorption process, such as shrimp head pretreatment, solution pH level, contact time and initial Ni(II) concentration, were studied in batch systems. An increase in Ni(II) biosorption capacity and a reduction in the time required to reach Ni(II) biosorption equilibrium was manifested by shrimp head biomass pretreated by boiling in 0.5 N NaOH for 15 min; this biomass was thereafter denominated APSH. The optimum biosorption level of Ni(II) ions onto APSH was observed at pH 7.0. Biosorption increased significantly with rising initial Ni(II) concentration. In terms of biosorption dynamics, the pseudo-second-order kinetic model described Ni(II) biosorption onto APSH best. The equilibrium data adequately fitted the Langmuir isotherm model within the studied Ni(II) ion concentration range. According to this isotherm model, the maximum Ni(II) biosorption capacity of APSH was 104.22 mg/g. Results indicate that APSH could be used as a low-cost, environmentally friendly, and promising biosorbent with high biosorption capacity to remove Ni(II) from aqueous solutions.

Bioleaching of zinc and manganese from spent Zn-Mn batteries and mechanism exploration.

PubMed

Xin, Baoping; Jiang, Wenfeng; Aslam, Hina; Zhang, Kai; Liu, Changhao; Wang, Renqing; Wang, Yutao

2012-02-01

In this work, bioleaching was used to extract valuable Zn and Mn from spent Zn-Mn batteries. The results showed that 96% of Zn extraction was achieved within 24h regardless of energy source types and bioleaching bacteria species. However, initial pH had a remarkable influence on Zn release, extraction dose sharply decreased from 2200 to 500mg/l when the initial pH value increased from 1.5 to 3.0 or higher. In contrast to Zn, all the tested factors evidently affected Mn extraction; the maximum released dose of 3020mg/l was obtained under the optimum conditions. The acidic dissolution by biogenic H(2)SO(4) by the non-contact mechanism was responsible for Zn extraction, while Mn extraction was owed to both contact/biological and non-contact mechanisms. The combined action of acidic dissolution of soluble Mn(2+) by biogenic H(2)SO(4) and reductive dissolution of insoluble Mn(4+) by Fe(2+) resulted in 60% of Mn extraction, while contact of microbial cells with the spent battery material and incubation for more than 7days was required to achieve the maximum extraction of Mn. Copyright © 2011 Elsevier Ltd. All rights reserved.

Removal of nitrate and sulphate from biologically treated municipal wastewater by electrocoagulation

NASA Astrophysics Data System (ADS)

Sharma, Arun Kumar; Chopra, A. K.

2017-06-01

The present investigation observed the effect of current density ( j), electrocoagulation (EC) time, inter electrode distance, electrode area, initial pH and settling time on the removal of nitrate (NO3 -) and sulphate (SO4 2-) from biologically treated municipal wastewater (BTMW), and optimization of the operating conditions of the EC process. A glass chamber of two-liter volume was used for the experiments with DC power supply using two electrode plates of aluminum (Al-Al). The maximum removal of NO3 - (63.21 %) and SO4 2- (79.98 %) of BTMW was found with the optimum operating conditions: current density: 2.65 A/m2, EC time: 40 min, inter electrode distance: 0.5 cm, electrode area: 160 cm2, initial pH: 7.5 and settling time: 60 min. The EC brought down the concentration of NO3 - within desirable limit of the Bureau of Indian Standard (BIS)/WHO for drinking water. Under optimal operating conditions, the operating cost was found to be 1.01/m3 of water in terms of the electrode consumption (23.71 × 10-5 kg Al/m3) and energy consumption (101.76 kWh/m3).

Fe3O4/SiO2-g-PSStNa polymer nanocomposite microspheres (PNCMs) from a surface-initiated atom transfer radical polymerization (SI-ATRP) approach for pectinase immobilization.

PubMed

Lei, Zhongli; Ren, Na; Li, Yanli; Li, Na; Mu, Bo

2009-02-25

Polymer nanocomposite microspheres (PNCMs) as solid supports can improve the efficiency of immobilized enzymes by reducing diffusional limitation as well as by increasing the surface area per mass unit. In this work, pectinase was immobilized on Fe(3)O(4)/SiO2-g-poly(PSStNa) nanocomposite microspheres by covalent attachment. Biochemical studies showed an improved storage stability of the immobilized pectinase as well as enhanced performance at higher temperatures and over a wider pH range. The immobilized enzyme retained >50% of its initial activity over 30 days, and the optimum temperature and pH also increased to the ranges of 50-60 degrees C and 3.0-4.7, respectively. The kinetics of a model reaction catalyzed by the immobilized pectinase was finally investigated by the Michaelis-Menten equation. The PSStNa support presents a very simple, mild, and time-saving process for enzyme immobilization, and this strategy of immobilizing pectinase also makes use of expensive enzymes economically viable, strengthening repeated use of them as catalysts following their rapid and easy separation with a magnet.

Combined process of electrocoagulation and photocatalytic degradation for the treatment of olive washing wastewater.

PubMed

Ates, Hasan; Dizge, Nadir; Yatmaz, H Cengiz

2017-01-01

In this study, an electrocoagulation reactor (ECR) and photocatalytic reactor (PCR) were tested to understand the performance of combined electrocoagulation and photocatalytic-degradation of olive washing wastewater (OWW). The effects of initial pH (6.0, 6.9, 8.0, 9.0), applied voltage (10.0, 12.5, 15.0 V), and operating time (30, 60, 90, 120 min) were investigated in the electrocoagulation reactor when aluminum electrodes were used as both anode and cathode. The pH, conductivity, color, chemical oxygen demand (COD), and phenol were measured versus time to determine the efficiency of the ECR and PCR process. It was observed that electrocoagulation as a single treatment process supplied the COD removal of 62.5%, color removal of 98.1%, and total phenol removal of 87% at optimum conditions as pH 6.9, applied voltage of 12.5 V, and operating time of 120 min. Moreover, final pH and conductivity were 7.7 and 980 μS/cm, respectively. On the other hand, the effect of semiconductor catalyst type (TiO 2 and ZnO) and loading (1, 2, 3 g/L) were tested using PCR as a stand-alone technique. It was found that photocatalytic degradation as a single treatment process when using 1 g/L ZnO achieved the COD removal of 46%, color removal of 99% with a total phenol removal of 41% at optimum conditions. Final pH and conductivity were 6.2 and 915 μS/cm, respectively. Among semiconductor catalysts, TiO 2 and ZnO performed identical efficiencies for both COD and total phenol removal. Moreover, combination in which electrochemical degradation was employed as a pre-treatment to the photocatalytic degradation process obtained high COD removal of 88% and total phenol, as well as color removal of 100% for the OWW. The electrochemical treatment alone was not effective, but in combination with the photocatalytic process, led to a high-quality effluent. Finally, sludge collected from the electrocoagulation process was characterized by attenuated total reflection Fourier transform infrared and X-ray powder diffraction analyses.

Reuse of acid coagulant-recovered drinking waterworks sludge residual to remove phosphorus from wastewater

NASA Astrophysics Data System (ADS)

Yang, Lan; Wei, Jie; Zhang, Yumei; Wang, Jianli; Wang, Dongtian

2014-06-01

Acid coagulant-recovered drinking waterworks sludge residual (DWSR) is a waste product from drinking waterworks sludge (DWS) treatment with acid for coagulant recovery. In this study, we evaluated DWSR as a potential phosphorus (P) removing material in wastewater treatment by conducting a series of batch and semi-continuous tests. Batch tests were carried out to study the effects of pH, initial concentration, and sludge dose on P removal. Batch test results showed that the P removal efficiency of DWSR was highly dependent on pH. Calcinated DWSR (C-DWSR) performed better in P removal than DWSR due to its higher pH. At an optimum initial pH value of 5-6 and a sludge dose of 10 g/L, the P removal rates of DWSR and DWS decreased from 99% and 93% to 84% and 14%, respectively, and the specific P uptake of DWSR and DWS increased from 0.19 and 0.19 mg P/g to 33.60 and 5.72 mg P/g, respectively, when the initial concentration was increased from 2 to 400 mg/L. The effective minimum sludge doses of DWSR and DWS were 0.5 g/L and 10 g/L, respectively, when the P removal rates of 90% were obtained at an initial concentration of 10 mg/L. Results from semi-continuous test indicated that P removal rates over 99% were quickly achieved for both synthetic and actual wastewater (lake water and domestic sewage). These rates could be maintained over a certain time under a certain operational conditions including sludge dose, feed flow, and initial concentration. The physicochemical properties analysis results showed that the contents of aluminum (Al) and iron (Fe) in DWSR were reduced by 50% and 70%, respectively, compared with DWS. The insoluble Al and Fe hydroxide in DWS converted into soluble Al and Fe in DWSR. Metal leaching test results revealed that little soluble Al and Fe remained in effluent when DWSR was used for P removal. We deduced that chemical precipitation might be the major action for P removal by DWSR and that adsorption played only a marginal role.

Treatment of landfill leachate using a combined stripping, Fenton, SBR, and coagulation process.

PubMed

Guo, Jin-Song; Abbas, Abdulhussain A; Chen, You-Peng; Liu, Zhi-Ping; Fang, Fang; Chen, Peng

2010-06-15

The leachate from Changshengqiao landfill (Chongqing, China) was characterized and submitted to a combined process of air stripping, Fenton, sequencing batch reactor (SBR), and coagulation. Optimum operating conditions for each process were identified. The performance of the treatment was assessed by monitoring the removal of organic matter (COD and BOD(5)) and ammonia nitrogen (NH(3)-N). It has been confirmed that air stripping (at pH 11.0 and aeration time 18h) effectively removed 96.6% of the ammonia. The Fenton process was investigated under optimum conditions (pH 3.0, FeSO(4).7H(2)O of 20 g l(-1) and H(2)O(2) of 20 ml l(-1)), COD removal of up to 60.8% was achieved. Biodegradability (BOD(5)/COD ratio) increased from 0.18 to 0.38. Thereafter the Fenton effluent was mixed with sewage at dilutions to a ratio of 1:3 before it was subjected to the SBR reactor; under the optimum aeration time of 20 h, up to 82.8% BOD(5) removal and 83.1% COD removal were achieved. The optimum coagulant (Fe(2)(SO(4))(3)) was a dosage of 800 mg l(-1) at pH of 5.0, which reduced COD to an amount of 280 mg l(-1). These combined processes were successfully employed and very effectively decreased pollutant loading. Crown Copyright 2010. Published by Elsevier B.V. All rights reserved.

Degradation of dichlorvos using hydrodynamic cavitation based treatment strategies.

PubMed

Joshi, Ravi K; Gogate, Parag R

2012-05-01

The degradation of an aqueous solution of dichlorvos, a commonly used pesticide in India, has been systematically investigated using hydrodynamic cavitation reactor. All the experiments have been carried out using a 20 ppm solution of commercially available dichlorvos. The effect of important operating parameters such as inlet pressure (over a range 3-6 bar), temperature (31 °C, 36 °C and 39 °C) and pH (natural pH = 5.7 and acidic pH = 3) on the extent of degradation has been investigated initially. It has been observed that an optimum value of pressure gives maximum degradation whereas low temperature and pH of 3 are favorable. Intensification studies have been carried out using different additives such as hydrogen peroxide, carbon tetrachloride, and Fenton's reagent. Use of hydrogen peroxide and carbon tetrachloride resulted in the enhancement of the extent of degradation at optimized conditions but significant enhancement was obtained with the combined use of hydrodynamic cavitation and Fenton's chemistry. The maximum extent of degradation as obtained by using a combination of hydrodynamic cavitation and Fenton's chemistry was 91.5% in 1h of treatment time. The present work has conclusively established that hydrodynamic cavitation in combination with Fenton's chemistry can be effectively used for the degradation of dichlorvos. Copyright © 2011 Elsevier B.V. All rights reserved.

Arsenic remediation from drinking water by synthesized nano-alumina dispersed in chitosan-grafted polyacrylamide.

PubMed

Saha, Suparna; Sarkar, Priyabrata

2012-08-15

An arsenic adsorbent comprising alumina nanoparticles dispersed in polymer matrix was developed and its removal potential studied. Alumina nanoparticles were prepared by reverse microemulsion technique and these were immobilized on chitosan grafted polyacrylamide matrix by in situ dispersion. The loading capacity of this new synthesized adsorbent was found to be high (6.56 mg/g). Batch adsorption studies were performed as a function of contact time, initial arsenic concentration, pH and presence of competing anions. The removal was found to be pH dependent, and maximum removal was obtained at pH 7.2 while the equilibrium time was 6h. The equilibrium adsorption data fitted very well with Freundlich isotherm. However, the D-R isotherm studies indicated that chemisorptions might play an important role. This was also confirmed by the FTIR study of the arsenic loaded adsorbent. A mechanism of arsenic sorption by the new polymeric adsorbent has been proposed. The regeneration study of the adsorbent resulted in retention of 94% capacity in the fifth cycle. An optimum pH of 7.2, operation at normal temperature, high adsorption capacity and good recycle potential of this new adsorbent would make it an ideal material for removal of arsenic from drinking water. Copyright © 2012 Elsevier B.V. All rights reserved.

Copper, lead and zinc removal from metal-contaminated wastewater by adsorption onto agricultural wastes.

PubMed

Janyasuthiwong, Suthee; Phiri, Sheila M; Kijjanapanich, Pimluck; Rene, Eldon R; Esposito, Giovanni; Lens, Piet N L

2015-01-01

The use of agricultural wastes (groundnut shell, orange and banana peel, rice husk, coconut husk and Wawa tree saw dust) as potential cost-effective adsorbent for heavy metal removal from wastewater was evaluated. The effect of pH (2.0-6.0), adsorbent dosage (0.6-2.2 g), contact time (10-130 min) and initial concentration (Pb: 5-105 mg/L, Cu and Zn: 2.5-52.7 mg/L) on the metal removal efficiency and uptake capacity were investigated using response surface methodology to optimize the process conditions. Groundnut shell showed a high potential to remove Cu, Pb and Zn from synthetic wastewater. The highest removal efficiencies with groundnut as the adsorbent were 85% at pH 5.0 for Cu and 98% at pH 3.0 for Pb and Zn. The optimum conditions obtained were 2.5 g adsorbent with 40.7 mg/L Cu at pH 4.4 and 64 min contact time, 2.5 g adsorbent with 196.1 mg/L Pb at pH 5.6 and 60 min contact time and 3.1 g adsorbent with 70.2 mg/L Zn at pH 4.3 and 50 min contact time, for Cu, Pb and Zn, respectively. The regeneration of the groundnut shell was possible for a maximum of three cycles using 0.2 M HCl as the desorbing solution without any significant change in the adsorbing efficiency.

Preliminary study on optimization of pH, oxidant and catalyst dose for high COD content: solar parabolic trough collector

PubMed Central

2013-01-01

In the present study, solar photocatalytic oxidation has been investigated through laboratory experiments as an alternative to conventional secondary treatment for the organic content reduction of high COD wastewater. Experiments have been performed on synthetic high COD wastewater for solar photocatalytic oxidation using a parabolic trough reactor. Parameters affecting the oxidation of organics have been investigated. The experimental design followed the sequence of dark adsorption studies of organics, followed by photolytic studies (in absence of catalyst) and finally photocatalytic studies in presence and absence of additional oxidant (H2O2). All the experimental studies have been performed at pH values of 2, 4, 6,8,10 and the initial pH value of the wastewater (normal pH). For photocatalytic studies, TiO2 has been used as a photocatalyst. Optimization of catalyst dose, pH and H2O2 concentration has been done. Maximum reduction of organic content was observed at the normal pH value of the wastewater (pH = 6.8). The reaction rate was significantly enhanced in presence of hydrogen peroxide. The optimum pH other than the Normal was in the alkaline range. Acidic pH was not found to be favourable for organic content reduction. pH was found to be a dominant factor affecting reaction rate even in presence of H2O2 as an additional oxidant. Also, the solar detoxification process was effective in treating a waste with a COD level of more than 7500 mg/L, which is a otherwise a difficult waste to treat. It can therefore be used as a treatment step in the high organic wastewater treatment during the primary stage also as it effectively reduces the COD content by 86%. PMID:23369352

Removal of trivalent and hexavalent chromium by seaweed biosorbent

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kratochvil, D.; Volesky, B.; Pimentel, P.

1998-09-15

Protonated or Ca-form Sargassum seaweed biomass bound up to 40 mg/g of Cr(III) by ion exchange at pH 4. An ion-exchange model assuming that the only species taken up by the biomass was Cr(OH){sup 2+} successfully fitted the experimental biosorption data for Cr(III). The maximum uptake of Cr(VI) by protonated Sargassum biomass at pH 2 was explained by simultaneous anion exchange and Cr(VI) to Cr(III) reduction. At pH <2.0, the reduction of Cr(VI) to Cr(III) dominated the equilibrium behavior of the batch systems, which was explained by the dependence of the reduction potential of HCrO{sub 4}{sup {minus}} ions on themore » pH. At pH >2.0, the removal of Cr(VI) was linked to the depletion of protons in equilibrium batch systems via an anion-exchange reaction. The optimum pH for Cr(VI) removal by sorption lies in the region where the two mechanisms overlap, which for Sargassum biomass is in the vicinity of pH 2. The existence of the optimum pH for the removal of Cr(VI) may be explained by taking into account (a) the desorption of Cr(III) from biomass at low pH and (b) the effect of pH on the reduction potential of Cr(VI) in aqueous solutions. Seventy percent of Cr(VI) bound to the seaweed at pH 2 can be desorbed with 0.2 M H{sub 2}SO{sub 4} via reduction to Cr(III).« less

Production of Pectate Lyase by Penicillium viridicatum RFC3 in Solid-State and Submerged Fermentation.

PubMed

Ferreira, Viviani; da Silva, Roberto; Silva, Dênis; Gomes, Eleni

2010-01-01

Pectate lyase (PL) was produced by the filamentous fungus Penicillium viridicatum RFC3 in solid-state cultures of a mixture of orange bagasse and wheat bran (1 : 1 w/w), or orange bagasse, wheat bran and sugarcane bagasse (1 : 1 : 0.5 w/w), and in a submerged liquid culture with orange bagasse and wheat bran (3%) as the carbon source. PL production was highest (1,500 U mL(-1) or 300 Ug(-1) of substrate) in solid-state fermentation (SSF) on wheat bran and orange bagasse at 96 hours. PL production in submerged fermentation (SmF) was influenced by the initial pH of the medium. With the initial pH adjusted to 4.5, 5.0, and 5.5, the peak activity was observed after 72, 48, and 24 hours of fermentation, respectively, when the pH of the medium reached the value 5.0. PL from SSF and SmF were loaded on Sephadex-G75 columns and six activity peaks were obtained from crude enzyme from SSF and designated PL I, II, III, IV, V, and VI, while five peaks were obtained from crude enzyme from SmF and labeled PL I', II', III', IV', and VII'. Crude enzyme and fraction III from each fermentative process were tested further. The optimum pH for crude PL from either process was 5.5, while that for PL III was 8.0. The maximum activity of enzymes from SSF was observed at 35 degrees C, but crude enzyme was more thermotolerant than PL III, maintaining its maximum activity up to 45 degrees C. Crude enzyme from SmF and PL III' showed thermophilic profiles of activity, with maximum activity at 60 and 55 degrees C, respectively. In the absence of substrate, the crude enzyme from SSF was stable over the pH range 3.0-10.0 and PL III was most stable in the pH range 4.0-7.0. Crude enzyme from SmF retained 70%-80% of its maximum activity in the acid-neutral pH range (4.0-7.0), but PIII showed high stability at alkaline pH (7.5-9.5). PL from SSF was more thermolabile than that from SmF. The latter maintained 60% of its initial activity after 1 h at 55 degrees C. The differing behavior of the enzymes with respect to pH and temperature suggests that they are different isozymes.

Removal of microcystin-LR from drinking water using a bamboo-based charcoal adsorbent modified with chitosan.

PubMed

Zhang, Hangjun; Zhu, Guoying; Jia, Xiuying; Ding, Ying; Zhang, Mi; Gao, Qing; Hu, Ciming; Xu, Shuying

2011-01-01

A new kind of low-cost syntactic adsorbent from bamboo charcoal and chitosan was developed for the removal of microcystin-LR from drinking water. Removal efficiency was higher for the syntactic adsorbent when the amount of bamboo charcoal was increased. The optimum dose ratio of bamboo charcoal to chitosan was 6:4, and the optimum amount was 15 mg/L; equilibrium time was 6 hr. The adsorption isotherm was non-linear and could be simulated by the Freundlich model (R2 = 0.9337). Adsorption efficiency was strongly affected by pH and natural organic matter (NOM). Removal efficiency was 16% higher at pH 3 than at pH 9. Efficiency rate was reduced by 15% with 25 mg/L NOM (UV254 = 0.089 cm(-1)) in drinking water. This study demonstrated that the bamboo charcoal modified with chitosan can effectively remove microcystin-LR from drinking water.

Immobilization of alpha-amylase from Bacillus circulans GRS 313 on coconut fiber.

PubMed

Dey, Gargi; Nagpal, Varima; Banerjee, Rintu

2002-01-01

A simple and inexpensive method for immobilizing alpha-amylase from Bacillus circulans GRS 313 on coconut fiber was developed. The immobilization conditions for highest efficiency were optimized with respect to immobilization pH of 5.5, 30 degrees C, contact time of 4 h, and enzyme to support a ratio of 1:1 containing 0.12 mg/mL of protein. The catalytic properties of the immobilized enzyme were compared with that of the free enzyme. The activity of amylase adsorbed on coconut fiber was 38.7 U/g of fiber at its optimum pH of 5.7 and 48 degrees C, compared with the maximum activity of 40.2 U/mL of free enzyme at the optimum pH of 4.9 and 48 degrees C. The reutilization capacity of the immobilized enzyme was up to three cycles.

Multiple forms of endopeptidase activity from jojoba seeds.

PubMed

Wolf, M J; Storey, R D

1990-01-01

The cotyledons of 27 day post-germination jojoba seedlings (Simmondsia chinensis) contained five distinct endopeptidase activities separable by DEAE Bio-Gel and CM-cellulose ion exchange chromatography. The endopeptidases were purified 108- to 266-fold and their individuality was confirmed by activity-specific assays in native acrylamide gels along with differences in their Mr and catalytic properties. The five endopeptidases, which showed activity on model substrates and protein, were named EP Ia, EP Ib, EP II, EP III and EP IV. EP Ia was a serine proteinase with a pH optimum of ca 8 and Mr of 58,000. EP Ib, II and III were discrete cysteine proteinases showing pH optima of ca 6.8, 6.0 and 5.4 and Mr of 41,000, 47,000 and 35,000 respectively. EP IV was an aspartic acid proteinase with a ca pH optimum of 3.5 and Mr of 33,000.

The mechanism of thorium biosorption by Rhizopus arrhizus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tsezos, M.; Volesky, B.

1982-04-01

Inactive cells of Rhizopus arrhizus have been documented to exhibit a high thorium biosorptive uptake (170 mg/g) from aqueous solutions. The mechanism of thorium sequestering by this biomass type was investigated following the same method as for the uranium biosorption emchanism. The thorium sequestering mechanism appeared somewhat different from that of uranium. Experimental evidence is presented which indicates that, at optimum biosorption pH (4), thorium coordinates with the nitroge of the chitin cell wall network and, in addition, more thorium is adsorbed by the external section of the fungal cell wall. At pH 2 the overall thorium uptake is reduced.more » The kinetic study of thorium biosorption revealed a very rapid rate of uptake. Unlike uranium at optimum solution pH, Fe/sup 2 +/ and Zn/sup 2 +/ did not interfere significantly with the thorium biosorptive uptake capacity of R. arrhizus.« less

Decontamination of unsymmetrical dimethylhydrazine waste water by hydrodynamic cavitation-induced advanced Fenton process.

PubMed

Torabi Angaji, Mahmood; Ghiaee, Reza

2015-03-01

A pilot scale hydrodynamic cavitation (HC) reactor, using iron metal blades, as the heterogeneous catalyst, with no external source of H₂O₂ was developed for catalytic decontamination of unsymmetrical dimethylhydrazine (UDMH) waste water. In situ generation of Fenton reagents suggested an induced advanced Fenton process (IAFP) to explain the enhancing effect of the used catalyst in the HC process. The effects of the applied catalyst, pH of the initial solution (1.0-9.7), initial UDMH concentration (2-15 mg/l), inlet pressure (5.5-7.8bar), and downstream pressure (2-6 bar), have been investigated. The results showed that the highest cavitation yield can be obtained at pH 3 and initial UDMH concentration of 10mg/l. Also, an increase in the inlet pressure would lead to an increase in the extent of UDMH degradation. In addition, the optimum value of 3 bar was determined for the downstream pressure that resulted to 98.6% degradation of UDMH after 120 min of processing time. Neither n-nitrosodimethylamine (NDMA) nor any other toxic byproduct (/end-product) was observed in the investigated samples. Formic acid and acetic acid, as well as nitromethane, were identified as oxidation by-products. The present work has conclusively established that hydrodynamic cavitation in combination with Fenton's chemistry can be effectively used for the degradation of UDMH. Copyright © 2014 Elsevier B.V. All rights reserved.

Degradation of aniline by heterogeneous Fenton's reaction using a Ni-Fe oxalate complex catalyst.

PubMed

Liu, Yucan; Zhang, Guangming; Fang, Shunyan; Chong, Shan; Zhu, Jia

2016-11-01

A Ni-Fe oxalate complex catalyst was synthesized and characterized by means of Brunauer-Emmet-Teller (BET) method, scanning electron microscope (SEM) and X-ray photo-electron spectroscopy (XPS). The catalyst showed good catalytic activity for aniline degradation by heterogeneous Fenton's reaction, in which the synergetic index was 9.3. The effects of reaction temperature, catalyst dosage, hydrogen peroxide concentration and initial pH were investigated. Under the optimum conditions (T = 293 K, catalyst dosage = 0.2 g/L, H2O2 concentration = 4 mmol/L and initial pH = 5.4), 100% aniline could be removed within 35 min, and approximately 88% deamination efficiency was achieved in 60 min. The aniline degradation process followed the pseudo-first-order kinetic (k = 0.177 min(-1)) with activation energy (Ea) of 49.4 kJ mol(-1). Aniline could be removed in a broad initial pH (3-8) due to the excellent pH-tolerance property of the catalyst. The detected ammonium ion indicated that deamination occurred during aniline degradation. It was proposed that deamination synchronized with aniline removal, and aniline was attacked by free radicals to generate benzoquinonimine and phenol. This system is promising for the removal of aniline from water. Copyright © 2016 Elsevier Ltd. All rights reserved.

Chitosan-induced Au/Ag nanoalloy dispersed in IL and application in fabricating an ultrasensitive glucose biosensor based on luminol-H₂O₂-Cu²⁺/IL chemiluminescence system.

PubMed

Chaichi, M J; Alijanpour, S O

2014-11-01

A novel glucose biosensor based on the chemiluminescence (CL) detection of enzymatically generated hydrogen peroxide (H₂O₂) was constructed by one covalent immobilization of glucose oxidase (GOD) in glutaraldehyde-functionalized glass cell. In following, chitosan-induced Au/Ag nanoparticles dispersed in ion liquid (IL) were synthesised and immobilized on it. Herein, chitosan molecules acted as both the reducing and stabilizing agent for the preparation of NPs and also, as a coupling agent GOD and Au/Ag alloy NPs. In addition to catalyze luminol CL reaction, these NPs offered excellent catalytic activity toward hydrogen peroxide generation in enzymatic reaction between GOD and glucose. The used IL in fabrication of biosensor increased its stability. Also, IL alongside Cu(2+) accelerated enzymatic and CL reaction kinetic, and decreased luminol CL reaction optimum pH to 7.5 which would enable sensitive and precision determination of glucose. Under optimum condition, linear response range of glucose was found to be 1.0 × 10(-6)-7.5 × 10(-3)M, and detection limit was 4.0 × 10(-7)M. The CL biosensor exhibited good storage stability, i.e., 90% of its initial response was retained after 2 months storage at pH 7.0. The present CL biosensor has been applied satisfactory to analysis of glucose in real serum and urine samples. Copyright © 2014 Elsevier B.V. All rights reserved.

Comparison of phthalic acid removal from aqueous solution by electrochemical methods: Optimization, kinetic and sludge study.

PubMed

Sandhwar, Vishal Kumar; Prasad, Basheshwar

2017-12-01

In this work, comparative study between electrochemical processes such as electrocoagulation (EC), peroxi-coagulation (PC) and peroxi-electrocoagulation (PEC) was performed for the removal of phthalic acid (PA) and chemical oxygen demand (COD) from aqueous medium. Initially, acid treatment was studied at various pH (1-3) and temperature (10-55 °C). Subsequently, the supernatant was re-treated by electrochemical processes such as EC, PC and PEC separately. Independent parameters viz. pH, current density (CD), electrolyte concentration (m), electrode gap (g), H 2 O 2 concentration and electrolysis time (t) were optimized by Central Composite Design (CCD) for these electrochemical processes. All three processes were compared based on removal, energy consumption, kinetic analysis, operating cost and sludge characteristics. In this study, PEC process was found more efficient among EC, PC and PEC processes in order to get maximum removal, minimum energy consumption and minimum operating cost. Maximum removal of PA- 68.21%, 74.36%, 82.25% & COD- 64.79%, 68.15%, 75.21% with energy consumption - 120.95, 97.51, 65.68 (kWh/kg COD removed) were attained through EC, PC and PEC processes respectively at their corresponding optimum conditions. Results indicated that PA and COD removals are in order of PEC > PC > EC under optimum conditions. First order kinetic model was found able to describe the degradation kinetics and provided best correlation for the removal rate within the acceptable error range. Copyright © 2017 Elsevier Ltd. All rights reserved.

Bioprocessing of some agro-industrial residues for endoglucanase production by the new subsp.; Streptomyces albogriseolus subsp. cellulolyticus strain NEAE-J

PubMed Central

El-Naggar, Noura El-Ahmady; Abdelwahed, Nayera A.M.; Saber, Wesam I.A.; Mohamed, Asem A.

2014-01-01

The use of low cost agro-industrial residues for the production of industrial enzymes is one of the ways to reduce significantly production costs. Cellulase producing actinomycetes were isolated from soil and decayed agricultural wastes. Among them, a potential culture, strain NEAE-J, was selected and identified on the basis of morphological, cultural, physiological and chemotaxonomic properties, together with 16S rDNA sequence. It is proposed that strain NEAE-J should be included in the species Streptomyces albogriseolus as a representative of a novel sub-species, Streptomyces albogriseolus subsp. cellulolyticus strain NEAE-J and sequencing product was deposited in the GenBank database under accession number JN229412. This organism was tested for its ability to produce endoglucanase and release reducing sugars from agro-industrial residues as substrates. Sugarcane bagasse was the most suitable substrate for endoglucanase production. Effects of process variables, namely incubation time, temperature, initial pH and nitrogen source on production of endoglucanase by submerged fermentation using Streptomyces albogriseolus subsp. cellulolyticus have been studied. Accordingly optimum conditions have been determined. Incubation temperature of 30 °C after 6 days, pH of 6.5, 1% sugarcane bagasse as carbon source and peptone as nitrogen source were found to be the optimum for endoglucanase production. Optimization of the process parameters resulted in about 2.6 fold increase in the endoglucanase activity. Therefore, Streptomyces albogriseolus subsp. cellulolyticus coud be potential microorganism for the intended application. PMID:25242966

A Decolorization Technique with Spent “Greek Coffee” Grounds as Zero-Cost Adsorbents for Industrial Textile Wastewaters

PubMed Central

Kyzas, George Z.

2012-01-01

In this study, the decolorization of industrial textile wastewaters was studied in batch mode using spent “Greek coffee” grounds (COF) as low-cost adsorbents. In this attempt, there is a cost-saving potential given that there was no further modification of COF (just washed with distilled water to remove dirt and color, then dried in an oven). Furthermore, tests were realized both in synthetic and real textile wastewaters for comparative reasons. The optimum pH of adsorption was acidic (pH = 2) for synthetic effluents, while experiments in free pH (non-adjusted) were carried out for real effluents. Equilibrium data were fitted to the Langmuir, Freundlich and Langmuir-Freundlich (L-F) models. The calculated maximum adsorption capacities (Qmax) for total dye (reactive) removal at 25 °C was 241 mg/g (pH = 2) and 179 mg/g (pH = 10). Thermodynamic parameters were also calculated (ΔH0, ΔG0, ΔS0). Kinetic data were fitted to the pseudo-first, -second and -third order model. The optimum pH for desorption was determined, in line with desorption and reuse analysis. Experiments dealing the increase of mass of adsorbent showed a strong increase in total dye removal.

Conversion and degradation of shellfish wastes by Serratia sp. TKU016 fermentation for the production of enzymes and bioactive materials.

PubMed

Wang, San-Lang; Chang, Tao-Jen; Liang, Tzu-Wen

2010-06-01

A chitosanase and a protease were purified from the culture supernatant of Serratia sp. TKU016 with shrimp shell as the sole carbon/nitrogen source. The molecular masses of the chitosanase and protease determined by SDS-PAGE were approximately 65 and 53 kDa, respectively. The chitosanase was inhibited completely by Mn2+, but the protease was enhanced by all of tested divalent metals. The optimum pH, optimum temperature, pH stability, and thermal stability of the chitosanase and protease were (pH 7, 50 degrees C, pH 6-7, <50 degrees C) and (pH 8-10, 40 degrees C, pH 5-10, <50 degrees C), respectively. SDS (2 mM) had stimulatory effect on TKU016 protease activity. The result demonstrates that TKU016 protease is SDS-resistant protease and probably has a rigid structure. Besides, TKU016 culture supernatant (2% SPP) incubated for 2 days has the highest antioxidant activity, the DPPH scavenging ability was about 76%. With this method, we have shown that shrimp shell wastes can be utilized and it's effective in the production of enzymes, antioxidants, peptide and reducing sugar, facilitating its potential use in biological applications and functional foods.

Finding stable cellulase and xylanase: evaluation of the synergistic effect of pH and temperature.

PubMed

Farinas, Cristiane S; Loyo, Marcel Moitas; Baraldo, Anderson; Tardioli, Paulo W; Neto, Victor Bertucci; Couri, Sonia

2010-12-31

Ethanol from lignocellulosic biomass has been recognized as one of the most promising alternatives for the production of renewable and sustainable energy. However, one of the major bottlenecks holding back its commercialization is the high costs of the enzymes needed for biomass conversion. In this work, we studied the enzymes produced from a selected strain of Aspergillus niger under solid state fermentation. The cellulase and xylanase enzymatic cocktail was characterized in terms of pH and temperature by using response surface methodology. Thermostability and kinetic parameters were also determined. The statistical analysis of pH and temperature effects on enzymatic activity showed a synergistic interaction of these two variables, thus enabling to find a pH and temperature range in which the enzymes have a higher activity. The results obtained allowed the construction of mathematical models used to predict endoglucanase, β-glucosidase and xylanase activities under different pH and temperature conditions. Optimum temperature values for all three enzymes were found to be in the range between 35°C and 60°C, and the optimum pH range was found between 4 and 5.5. The methodology employed here was very effective in estimating enzyme behavior under different process conditions. Copyright © 2010 Elsevier B.V. All rights reserved.

Optimum allocation of redundancy among subsystems connected in series. Ph.D. Thesis - Case Western Reserve Univ., Sep. 1970

NASA Technical Reports Server (NTRS)

Bien, D. D.

1973-01-01

This analysis considers the optimum allocation of redundancy in a system of serially connected subsystems in which each subsystem is of the k-out-of-n type. Redundancy is optimally allocated when: (1) reliability is maximized for given costs; or (2) costs are minimized for given reliability. Several techniques are presented for achieving optimum allocation and their relative merits are discussed. Approximate solutions in closed form were attainable only for the special case of series-parallel systems and the efficacy of these approximations is discussed.

Studies on the Development of Mouse Embyros in Vitro

PubMed Central

Brinster, Ralph L.

2016-01-01

The effect of various possible energy sources on the development in vitro of two-cell mouse ova into blastocysts was examined. Energy for development of two-cell mouse ova could be supplied by lactate, pyruvate, oxaloacetate, or phosphoenolpyruvate. Compounds such as glucose, fructose, ribose, glucose-6-phosphate, fructose-1, 6-phosphate, acetate, citrate, α-ketoglutarate, succinate, fumarate, and malate could not provide energy for development of two-cell mouse ova. The optimum concentrations at pH 7.38 for those compounds which would supply energy was 5.00 × 10−2 M lactate, 3.16 × 10−4 M pyruvate, 3.16 × 10−4 M oxaloacetate, and 1.00 × 10−2 M phosphoenolpyruvate. The possibility that interactions existed between the effects of osmolarity, pH, and energy source was examined in several experiments. There was no interaction between the effects of osmolarity and pH or osmolarity and the four possible energy sources. However, there was a significant interaction between energy source and pH. The result of this is that an increase in pH of the medium results in an increase in the optimum concentration of the compound supplying energy to the developing ova. PMID:14299682

Comperative study of catalase immobilization on chitosan, magnetic chitosan and chitosan-clay composite beads.

PubMed

Başak, Esra; Aydemir, Tülin; Dinçer, Ayşe; Becerik, Seda Çınar

2013-12-01

Catalase was immobilized on chitosan and modified chitosan. Studies were carried out on free-immobilized catalase concerning the determination of optimum temperature, pH, thermal, storage stability, reusability, and kinetic parameters. Optimum temperature and pH for free catalase and catalase immobilized were found as 35°C and 7.0, respectively. After 100 times of repeated tests, the immobilized catalases on chitosan-clay and magnetic chitosan maintain over 50% and 60% of the original activity, respectively. The ease of catalase immobilization on low-cost matrices and good stability upon immobilization in the present study make it a suitable product for further use in the food industry.

Draft Genome Sequence of Bacillus urumqiensis BZ-SZ-XJ18T, a Moderately Haloalkaliphilic Bacterium Isolated from a Saline-Alkaline Lake.

PubMed

Liao, Ziya; Ren, Chao; Guo, Xiaomeng; Yan, Yanchun; Li, Jun; Zhao, Baisuo

2018-05-31

The moderately haloalkaliphilic bacterium Bacillus urumqiensis BZ-SZ-XJ18 T was isolated from a saline-alkaline lake located in the Xinjiang Uyghur Autonomous Region of China. Optimum growth occurred at the total Na + concentration of 1.08 M, with a broad optimum pH of 8.5 to 9.5. The draft genome consists of approximately 3.28 Mb and contains 3,228 predicted genes. A number of genes associated with adaptation strategies for osmotic balance and alkaline pH homeostasis were identified, providing pertinent insight into specific adaptations to the double-extreme environment. Copyright © 2018 Liao et al.

Purification and characterization of chitinases and chitosanases from a new species strain Pseudomonas sp. TKU015 using shrimp shells as a substrate.

PubMed

Wang, San-Lang; Chen, Shin-Jen; Wang, Chuan-Lu

2008-05-19

A chitinase (CHT1) and a chitosanase (CHS1) were purified from the culture supernatant of Pseudomonas sp. TKU015 with shrimp shell wastes as the sole carbon and nitrogen source. The optimized conditions of this new species strain (Gen Bank Accession Number EU103629) for the production of chitinases were found to be when the culture was shaken at 30 degrees C for 3 days in 100 mL of medium (pH 8) containing 0.5% shrimp shell powder (SSP) (w/v), 0.1% K2HPO4, and 0.05% MgSO(4).7H2O. The molecular weights of CHT1 and CHS1 determined by SDS-PAGE were approximately 68 kDa and 30 kDa, respectively. The optimum pH, optimum temperature, pH stability, and the thermal stability of CHT1 and CHS1 were pH 6, 50 degrees C, pH 5-7, <50 degrees C and pH 4, 50 degrees C, pH 3-9, <50 degrees C, respectively. CHT1 was inhibited completely by Mn2+ and Fe2+, and CHS1 was inhibited by Mn2+, Cu2+, and PMSF. CHT1 was only specific to chitin substrates, whereas the relative activity of CHS1 increased when the degree of deacetylation of soluble chitosan increased.

Removal of ammonium from aqueous solutions with volcanic tuff.

PubMed

Marañón, E; Ulmanu, M; Fernández, Y; Anger, I; Castrillón, L

2006-10-11

This paper presents kinetic and equilibrium data concerning ammonium ion uptake from aqueous solutions using Romanian volcanic tuff. The influence of contact time, pH, ammonium concentration, presence of other cations and anion species is discussed. Equilibrium isotherms adequately fit the Langmuir and Freundlich models. The results showed a contact time of 3h to be sufficient to reach equilibrium and pH of 7 to be the optimum value. Adsorption capacities of 19 mg NH(4)(+)/g were obtained in multicomponent solutions (containing NH(4)(+), Zn(2+), Cd(2+), Ca(2+), Na(2+)). The presence of Zn and Cd at low concentrations did not decrease the ammonium adsorption capacity. Comparison of Romanian volcanic tuff with synthetic zeolites used for ammonium removal (5A, 13X and ZSM-5) was carried out. The removal efficiciency of ammonium by volcanic tuff were similar to those of zeolites 5A and 13X at low initial ammonium concentration, and much higher than those of zeolite ZSM-5.

Preparation and Characterization of Biochars from Eichornia crassipes for Cadmium Removal in Aqueous Solutions.

PubMed

Li, Feng; Shen, Kaixuan; Long, Xiaolin; Wen, Jiasheng; Xie, Xiaojie; Zeng, Xiangyun; Liang, Yanyan; Wei, Yansha; Lin, Zefeng; Huang, Wenrou; Zhong, Ruida

2016-01-01

The study investigated the preparation and characterization of biochars from water hyacinth at 300°C to 700°C for cadmium (Cd) removal from aqueous solutions. The adsorption process was dominated by oxygen-containing functional groups with irregular surfaces via esterification reactions. Furthermore, the mineral components in the biochars also contributed to Cd absorption through precipitation. Parameters such as the effects of solution pH, contact time, and initial concentration were studied. The optimum pH value was observed at 5.0, in which nearly 90% of Cd was removed. The maximum Cd adsorption capacities based on the Langmuir isotherm were calculated at 49.837, 36.899, and 25.826 mg g(-1). The adsorption processes of the biochars followed the pseudo-second-order kinetics, with the equilibrium achieved around 5 h. The biochar from E. crassipes is a promising adsorbent for the treatment of wastewater, which can in turn convert one environmental problem to a new cleaning Technology.

Preparation and Characterization of Biochars from Eichornia crassipes for Cadmium Removal in Aqueous Solutions

PubMed Central

Li, Feng; Shen, Kaixuan; Long, Xiaolin; Wen, Jiasheng; Xie, Xiaojie; Zeng, Xiangyun; Liang, Yanyan; Wei, Yansha; Lin, Zefeng; Huang, Wenrou; Zhong, Ruida

2016-01-01

The study investigated the preparation and characterization of biochars from water hyacinth at 300°C to 700°C for cadmium (Cd) removal from aqueous solutions. The adsorption process was dominated by oxygen-containing functional groups with irregular surfaces via esterification reactions. Furthermore, the mineral components in the biochars also contributed to Cd absorption through precipitation. Parameters such as the effects of solution pH, contact time, and initial concentration were studied. The optimum pH value was observed at 5.0, in which nearly 90% of Cd was removed. The maximum Cd adsorption capacities based on the Langmuir isotherm were calculated at 49.837, 36.899, and 25.826 mg g−1. The adsorption processes of the biochars followed the pseudo-second-order kinetics, with the equilibrium achieved around 5 h. The biochar from E. crassipes is a promising adsorbent for the treatment of wastewater, which can in turn convert one environmental problem to a new cleaning Technology. PMID:26882239

Synthesis, Characterization and Application of N-Ti/13X/MCM-41 Mesoporous Molecular Sieves.

PubMed

Tao, Hong; Nguyen, Nhat-Thien; Hei, Xiao-Hui; Nguyen, Cong Nguyen; Tsai, Hsiao-Hsin; Chang, I-Cheng; Chang, Chang-Tang

2016-06-01

Di-n-butyl phthalate (DBP) is a type of phthalate ester. In recent years, an increasing number of studies have examined the removal of DBP. In this study we use a composite material of N-Ti/13X/MCM-41, synthesized by nitrogen, molecular sieve 13X, tetrabutyl orthotitanate and tetraethyl orthosilicate as raw materials, CTAB as a structural template and tetrabutyl titanate and urea under hydrothermal conditions. The optimized experimental conditions, such as the amount of material, reaction time, pH value and initial concentration were tested. The surface areas of N-Ti/13X/MCM-41 were found to be 664 m2g(-1). TEM micrographs revealed N-Ti/13X/MCM-41 is consisting of aggregates of spherical particles, similar with standard synthesized MCM-41 (Mobil Composition of Matter No. 41). Through photocatalytic degradation experiments, the optimum degradation efficiency of DBP was more than 90% at a pH 6.0 with catalyst dosing of 0.15 g L(-1).

Immobilization of an L-aminoacylase-producing strain of Aspergillus oryzae into gelatin pellets and its application in the resolution of D,L-methionine.

PubMed

Yuan Yj, Ying-jin; Wang Sh, Shu-hao; Song Zx, Zheng-xiao; Gao Rc, Rui-chang

2002-04-01

The conditions for immobilization of an l-aminoacylase-producing strain of Aspergillus oryzae in gelatin and the enzymic characteristics of the immobilized pellets were studied. The optimal concentrations of gelatin, glutaraldehyde and ethyldiamine and time of immobilization were determined. Scanning electron micrographs reveal the cross-linked structure differences between the native and immobilized pellets. Optimum pH and temperature of the native and immobilized pellets were determined. Effects of ionic strength and substrate concentration on relative activity of the native and immobilized pellets were investigated in detail. The immobilized pellets were more stable over broader temperature and pH ranges. In addition, the immobilized pellets showed stable activity under operational and storage conditions. The immobilized pellets lost about 20% of their initial activity after five cycles of reuse. The results reported in this paper show the potential for using the immobilized A. oryzae pellets to resolve d,l-methionine.

Simultaneous enhancement of methane production and methane content in biogas from waste activated sludge and perennial ryegrass anaerobic co-digestion: The effects of pH and C/N ratio.

PubMed

Dai, Xiaohu; Li, Xiaoshuai; Zhang, Dong; Chen, Yinguang; Dai, Lingling

2016-09-01

It is necessary to find an appropriate strategy to simultaneously enhance the methane production and methane content in biogas from waste activated sludge (WAS) and grass co-digestion. In this study an efficient strategy, i.e., adjusting the initial pH 12 and C/N ratio 17/1, for simultaneous enhancement of methane production and methane content in biogas from WAS and perennial ryegrass co-digestion was reported. Experimental results indicated that the maximal methane production was 310mL/gVSadd at the optimum conditions after 30-d anaerobic digestion, which was, respectively, about 1.5- and 3.8-fold of the sole WAS and sole perennial ryegrass anaerobic digestion. Meanwhile, the methane content in biogas was about 74%, which was much higher than that of sole WAS (64%) or sole perennial ryegrass (54%) anaerobic digestion. Copyright © 2016 Elsevier Ltd. All rights reserved.

Enhanced cellulase production by Penicillium oxalicum for bio-ethanol application.

PubMed

Saini, Reetu; Saini, Jitendra Kumar; Adsul, Mukund; Patel, Anil Kumar; Mathur, Anshu; Tuli, Deepak; Singhania, Reeta Rani

2015-01-01

Present study was focused on cellulase production from an indigenously isolated filamentous fungal strain, identified as Penicillium oxalicum. Initially, cellulase production under submerged fermentation in shake flasks resulted in cellulase activity of 0.7 FPU/mL. Optimization of process parameters enhanced cellulase production by 1.7-fold and resulted in maximum cellulase activity of 1.2 FPU/mL in 8 days. Cellulase production was successfully scaled-up to 7 L fermenter under controlled conditions and incubation time was reduced from 8 days to 4 days for achieving similar cellulase titer. Optimum pH and temperature for activity of the crude enzyme were pH 5 and 50 °C, respectively. At 50 °C the produced cellulase retained approximately 50% and 26% of its activity at 48 h and 72 h, respectively. Hydrolytic efficiency of P. oxalicum was comparable to commercial cellulase preparations which indicate its great potential for application in the lignocellulose hydrolysis. Copyright © 2015 Elsevier Ltd. All rights reserved.

Biodegradability and swelling capacity of kaolin based chitosan-g-PHEMA nanocomposite hydrogel.

PubMed

Pradhan, Arun Kumar; Rana, Pradeep Kumar; Sahoo, Prafulla Kumar

2015-03-01

Chitosan, a natural biopolymer, obtained by alkaline deacetylation of chitin, exhibits excellent biological properties such as biodegradability, immunological and antibacterial activity. Recently, there has been a growing interest in the chemical modification of chitosan in order to widen its applications. The chemical modification of chitosan has been achieved via grafting of monomer, 2-hydroxyethyl methacrylate (HEMA) in the presence of the initiator, ammonium persulfate (APS) and kaolin was added to improve the mechanical strength of the newly developed nanocomposites hydrogel. The so prepared grafted nanocomposites hydrogel was characterized by FTIR, XRD, SEM, TEM and TGA. The equilibrium water content (EWC) of the samples were measured at different pH ranges 6.5-8.0 and found optimum at pH 7.5 for biomedical applications. Further, the biodegradability of the samples was studied at different time intervals from 15 days to 1 year but, the kaolin based nanohydrogels exhibited good biodegradability. Copyright © 2015 Elsevier B.V. All rights reserved.

The Study of Blocking Agent on Lengkeng (Euphoria Logan Lour) Fruit Shell and Seed for Adsorption of Pb (II) from Aqueous Solution

NASA Astrophysics Data System (ADS)

Kurniawati, D.; Zein, R.; Chaidir, Z.; Aziz, H.

2018-04-01

The study focuses on the roles played by mayor functional groups(carboxyl) in the lengkeng shell for sorption of Pb (II). The biosorbent was characterized by FTIR and elemental analyses. The parameters such as pH, initial concentration, particle sizes, adsorbent dose and flow rate were also studied. The results showed that the optimum condition was at pH = 3, concentration 400 mg/l, 250 μm particle sizes, adsorbent dose 0,5 g and 2 ml/min flow rate with adsorption capacity 4,8933 mg/g(shell) and 5,2720 mg/g(seed). It is show that ion exchange play as a more important role in the sorption of Pb (II) on lengkeng shell and seed. Blocking of COOH groups by chemical esterification resulted in Pb important reduction in metal binding.The result showed that adsorption capacity of lengkeng shell uncreases until 63.67 % and lengkeng seed uncreases 98.70%.

Razor clam (Ensis directus) shell as a low-cost adsorbent for the removal of Congo red and Rhodamine B dyes from aqueous solution

NASA Astrophysics Data System (ADS)

Areibat, Lila Elamari Mohamed; Kamari, Azlan

2017-05-01

Wastewater originating from industrial effluents contains many types of pollutants including dyes. Anionic and cationic dyes are very toxic and they can cause several problems to aquatic system. In present study, razor clam shell was used as a potential adsorbent to remove two classes of dyes, namely anionic (Congo red, CR) and cationic (Rhodamine B, RB) dyes from aqueous solution. Batch adsorption experiments were performed to study the effects of three experimental parameters, namely solution pH, adsorbent dosage and initial dye concentration, on adsorption capacity of CR and RB onto razor clam shell. Results indicated that pH 2.0 was optimum pH for adsorbent to adsorb both CR and RB. At an initial concentration of 20 mg/L, the removal percentages of CR and RB were 97% and 38%, respectively. The Freundlich and Langmuir isotherm models were used to describe adsorption behaviour of CR and RB, as well as the relationship between adsorbent and adsorbate. The adsorption equilibrium data were well fitted to Freundlich isotherm model. The separation factor (RL) constants suggest that both CR and RB were favourably adsorbed by razor clam shell. Razor clam shell was characterised by using two techniques, namely Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectrometry (FTIR). Overall, this study suggests that razor clam shell has great potential to be an alternative to expensive adsorbents.

Adsorption of Cu2+ to biomass ash and its modified product.

PubMed

Xu, Lei; Cui, Hongbiao; Zheng, Xuebo; Liang, Jiani; Xing, Xiangyu; Yao, Lunguang; Chen, Zhaojin; Zhou, Jing

2017-04-01

Ash produced by biomass power plants has great potential for the removal of heavy metal ions from aqueous solution. The pollution of toxic heavy metals to water is a worldwide environmental problem. Discharges containing copper, in particular, are strictly controlled because the excessive copper can cause serious harm to the environment and human health. This work aims to investigate the adsorption characteristics of copper ions in aqueous solution by biomass ash and the modified products, and to evaluate their potential application in water pollution control. The biomass ash was modified with a mesoporous siliceous material and functionalized with 3-aminopropyltriethoxysilane. The surface properties of the biomass ash and the new matrix were studied to evaluate their adsorption property for Cu 2+ ions at different pHs, initial metal concentrations and the thermodynamic and kinetic were studied. The chemical and morphological properties of this modified material are analyzed; the specific surface area of the modified biomass ash was nine times that of the initial ash. Both of the two materials showed a strong affinity for Cu 2+ , and the Langmuir model could best represent the adsorption characteristics of Cu 2+ on the two kinds of materials. The adsorption capacity of copper on the material increased with the increase of pH and pH 6 was the optimum pH. Thermodynamic analysis results showed that the adsorption of Cu 2+ was spontaneous and endothermic in nature. The adsorptions of Cu 2+ onto the modified biomass ash followed pseudo-second-order kinetics.

Batch and fixed-bed assessment of sulphate removal by the weak base ion exchange resin Amberlyst A21.

PubMed

Guimarães, Damaris; Leão, Versiane A

2014-09-15

This paper investigated sulphate removal from aqueous solutions by Amberlyst A21, a polystyrene weak base ion exchange resin. Both the pH and initial sulphate concentration were observed to strongly affect sorption yields, which were largest in acidic environments. Working under optimum operational conditions, sulphate sorption by Amberlyst A21 was relatively fast and reached equilibrium after 45 min of contact between the solid and liquid phases. Sorption kinetics could be described by either the pseudo-first order (k1=3.05 × 10(-5)s(-1)) or pseudo-second order model (k2=1.67 × 10(-4)s(-1)), and both the Freundlich and Langmuir models successfully fitted the equilibrium data. Sulphate uptake by Amberlyst A21 was a physisorption process (ΔH=-25.06 kJ mol(-1)) that occurred with entropy reduction (ΔS=-0.042 kJ mol(-1)K(-1)). Elution experiments showed that sulphate is easily desorbed (∼ 100%) from the resin by sodium hydroxide solutions at pH 10 or pH 12. Fixed-bed experiments assessed the effects of the initial sulphate concentration, bed height and flow rate on the breakthrough curves and the efficiency of the Amberlyst A21 in the treatment of a real effluent. In all studied conditions, the maximum sulphate loading resin varied between 8 and 40 mg(SO4(2-))mL(resin)(-1). Copyright © 2014 Elsevier B.V. All rights reserved.

A Sensitive Microplate Assay for Lipase Activity Measurement Using Olive Oil Emulsion Substrate: Modification of the Copper Soap Colorimetric Method.

PubMed

Mustafa, Ahmad; Karmali, Amin; Abdelmoez, Wael

2016-01-01

The present work involves a sensitive high-throughput microtiter plate based colorimetric assay for estimating lipase activity using cupric acetate pyridine reagent (CAPR). In the first approach, three factors two levels factorial design methodology was used to evaluate the interactive effect of different parameters on the sensitivity of the assay method. The optimization study revealed that the optimum CAPR concentration was 7.5% w/v, the optimum solvent was heptane and the optimum CAPR pH was 6. In the second approach, the optimized colorimetric microplate assay was used to measure lipase activity based on enzymatic hydrolysis of olive oil emulsion substrate at 37°C and 150 rpm. The emulsion substrates were formulated by using olive oil, triton X-100 (10% v/v in pH 8) and sodium phosphate buffer of pH 8 in ratio of 1:1:1 in the case of Candida sp. lipase. While in the case of immobilized lipozyme RMIM, The emulsion substrates were formulated by using olive oil, triton X-100 (1% v/v in pH 8) and sodium phosphate buffer of pH 8 in ratio of 2:1:1. Absorbance was measured at 655 nm. The stability of this assay (in terms of colored heptane phase absorbance readings) retained more than 92.5% after 24 h at 4°C compared to the absorbance readings measured at zero time. In comparison with other lipase assay methods, beside the developed sensitivity, the reproducibility and the lower limit of detection (LOD) of the proposed method, it permits analyzing of 96 samples at one time in a 96-well microplate. Furthermore, it consumes small quantities of chemicals and unit operations.

Highly thermostable, thermophilic, alkaline, SDS and chelator resistant amylase from a thermophilic Bacillus sp. isolate A3-15.

PubMed

Arikan, Burhan

2008-05-01

A thermostable alkaline alpha-amylase producing Bacillus sp. A3-15 was isolated from compost samples. There was a slight variation in amylase synthesis within the pH range 6.0 and 12.0 with an optimum pH of 8.5 (8mm zone diameter in agar medium) on starch agar medium. Analyses of the enzyme for molecular mass and amylolytic activity were carried out by starch SDS-PAGE electrophoresis, which revealed two independent bands (86,000 and 60,500 Da). Enzyme synthesis occurred at temperatures between 25 and 65 degrees C with an optimum of 60 degrees C on petri dishes. The partial purification enzyme showed optimum activity at pH 11.0 and 70 degrees C. The enzyme was highly active (95%) in alkaline range of pH (10.0-11.5), and it was almost completely active up to 100 degrees C with 96% of the original activity remaining after heat treatment at 100 degrees C for 30 min. Enzyme activity was enhanced in the presence of 5mM CaCl2 (130%) and inhibition with 5mM by ZnCl2, NaCl, Na-sulphide, EDTA, PMSF (3mM), Urea (8M) and SDS (1%) was obtained 18%, 20%, 36%, 5%, 10%, 80% and 18%, respectively. The enzyme was stable approximately 70% at pH 10.0-11.0 and 60 degrees C for 24h. So our result showed that the enzyme was both, highly thermostable-alkaline, thermophile and chelator resistant. The A3-15 amylase enzyme may be suitable in liquefaction of starch in high temperature, in detergent and textile industries and in other industrial applications.

Recovery of choline oxidase activity by in vitro recombination of individual segments.

PubMed

Heinze, Birgit; Hoven, Nina; O'Connell, Timothy; Maurer, Karl-Heinz; Bartsch, Sebastian; Bornscheuer, Uwe T

2008-11-01

Initial attempts to express a choline oxidase from Arthrobacter pascens (APChO-syn) in Escherichia coli starting from a synthetic gene only led to inactive protein. However, activity was regained by the systematic exchange of individual segments of the gene with segments from a choline oxidase-encoding gene from Arthrobacter globiformis yielding a functional chimeric enzyme. Next, a sequence alignment of the exchanged segment with other choline oxidases revealed a mutation in the APChO-syn, showing that residue 200 was a threonine instead of an asparagine, which is, thus, crucial for confering enzyme activity and, hence, provides an explanation for the initial lack of activity. The active recombinant APChO-syn-T200N variant was biochemically characterized showing an optimum at pH 8.0 and at 37 degrees C. Furthermore, the substrate specificity was examined using N,N-dimethylethanolamine, N-methylethanolamine and 3,3-dimethyl-1-butanol.

Effect and interaction study of acetamiprid photodegradation using experimental design.

PubMed

Tassalit, Djilali; Chekir, Nadia; Benhabiles, Ouassila; Mouzaoui, Oussama; Mahidine, Sarah; Merzouk, Nachida Kasbadji; Bentahar, Fatiha; Khalil, Abbas

2016-10-01

The methodology of experimental research was carried out using the MODDE 6.0 software to study the acetamiprid photodegradation depending on the operating parameters, such as the initial concentration of acetamiprid, concentration and type of the used catalyst and the initial pH of the medium. The results showed the importance of the pollutant concentration effect on the acetamiprid degradation rate. On the other hand, the amount and type of the used catalyst have a considerable influence on the elimination kinetics of this pollutant. The degradation of acetamiprid as an environmental pesticide pollutant via UV irradiation in the presence of titanium dioxide was assessed and optimized using response surface methodology with a D-optimal design. The acetamiprid degradation ratio was found to be sensitive to the different studied factors. The maximum value of discoloration under the optimum operating conditions was determined to be 99% after 300 min of UV irradiation.

Removal of some metal ions by activated carbon prepared from Phaseolus aureus hulls.

PubMed

Rao, M Madhava; Ramana, D K; Seshaiah, K; Wang, M C; Chien, S W Chang

2009-07-30

Removal of lead [Pb(II)], zinc [Zn(II)], copper [Cu(II)], and cadmium [Cd(II)] from aqueous solutions using activated carbon prepared from Phaseolus aureus hulls (ACPAH), an agricultural waste was studied. The influence of various parameters such as effect of pH, contact time, adsorbent dose, and initial concentration of metal ions on the removal was evaluated by batch method. The removal of metal ions by ACPAH was pH dependent and the optimum pH values were 7.0, 8.0, 7.0 and 6.0 for Cu(II), Cd(II), Zn(II), and Pb(II), respectively. The sorption isotherms were studied using Langmuir, Freundlich, Dubinin-Radushkevich (D-R), and Temkin isotherm models. The maximum adsorption capacity values of ACPAH for metal ions were 21.8 mg g(-1) for Pb(II), 21.2 mg g(-1) for Zn(II), 19.5 mg g(-1) for Cu(II), and 15.7 mg g(-1) for Cd(II). The experiments demonstrated that the removal of metal ions followed the pseudo-second-order kinetic model. Desorption experiments were carried out using HCl solution with a view to regenerate the spent adsorbent and to recover the adsorbed metal ions.

Mutagenesis and evaluation of cellulase properties and cellulose hydrolysis of Talaromyces piceus.

PubMed

He, Ronglin; Cai, Pengli; Wu, Gaihong; Zhang, Can; Zhang, Dongyuan; Chen, Shulin

2015-11-01

A fungal species with a high yield of β-glucosidase was isolated and identified as Talaromyces piceus 9-3 (anamorph: Penicillium piceum) by morphological and molecular characterization. Through dimethyl sulphate mutagenesis, the cellulase over-producing strain T. piceus H16 was obtained. The FPase activity and β-glucosidase activity of T. piceus H16 were 5.83 and 53.12 IU ml(-1) respectively--a 5.34- and 4.43-times improvement from the parent strain T. piceus 9-3. The optimum pH and temperature for enzyme activity were pH 5.0 and 50 °C for FPase activity and pH 5.0 and 55 °C for β-glucosidase activity, respectively. The cellulase were quite stable at 37 °C, only losing <10% of their initial activity after 24 h of incubation. Hydrolysis analysis results showed that a highly efficient synergistic effect was achieved by combining cellulase from T. piceus H16 with that from Trichoderma reesei RUT C30 on hydrolyzing different substrates due to the high β-glucosidase activity of T. piceus H16. These data suggest that T. piceus H16 can be used as a potential cellulase producer with good prospects.

Statistical medium optimization of an alkaline protease from Pseudomonas aeruginosa MTCC 10501, its characterization and application in leather processing.

PubMed

Boopathy, Naidu Ramachandra; Indhuja, Devadas; Srinivasan, Krishnan; Uthirappan, Mani; Gupta, Rishikesh; Ramudu, Kamini Numbi; Chellan, Rose

2013-04-01

Proteases are shown to have greener mode of application in leather processing for dehairing of goat skins and cow hides. Production of protease by submerged fermentation with potent activity is reported using a new isolate P. aeruginosa MTCC 10501. The production parameters were optimized by statistical methods such as Plackett-Burman and response surface methodology. The optimized production medium contained (g/L); tryptone, 2.5; yeast extract, 3.0; skim milk 30.0; dextrose 1.0; inoculum concentration 4%: initial pH 6.0; incubation temperature 30 degrees C and optimum production at 48 h with protease activity of 7.6 U/mL. The protease had the following characteristics: pH optima, 9.0; temperature optima 50 degrees C; pH stability between 5.0-10.0 and temperature stability between 10-40 degrees C. The protease was observed to have high potential for dehairing of goat skins in the pre- tanning process comparable to that of the chemical process as evidenced by histology. The method offers cleaner processing using enzyme only instead of toxic chemicals in the pre-tanning process of leather manufacture.

The catalytic oxidation of malachite green by the microwave-Fenton processes.

PubMed

Zheng, Huaili; Zhang, Huiqin; Sun, Xiaonan; Zhang, Peng; Tshukudu, Tiroyaone; Zhu, Guocheng

2010-01-01

Catalytic oxidation of malachite green using the microwave-Fenton process was investigated. 0% of malachite green de-colorization using the microwave process and 23.5% of malachite green de-colorization using the Fenton process were observed within 5 minutes. In contrast 95.4% of malachite green de-colorization using the microwave-Fenton was observed in 5 minutes. During the microwave-Fenton process, the optimum operating conditions for malachite green de-colorization were found to be 3.40 of initial pH, 0.08 mmol/L of Fe2+ concentration and 12.5 mmol/L of H2O2 concentration. Confirmatory tests were carried out under the optimum conditions and the COD removal rate of 82.0% and the de-colorization rate of 99.0% were observed in 5 minutes. The apparent kinetics equation of -dC/dt=0.0337 [malachite green]0.9860[Fe2+)]0.8234[H2O2]0.1663 for malachite green de-colorization was calculated, which implied that malachite green was the dominant factor in determining the removal efficiency of malachite green based on microwave-Fenton process.

Synthesis of a novel alginate-rubber joint immobilization strains H-1 and its application in removal of Pb (II) from aqueous solution

NASA Astrophysics Data System (ADS)

Li, Huidong; Huo, Kaili; Li, Xiaolei; Zhang, Lin; Yun, Yueqing; Song, Lei; Bai, Runying; Liu, Yuhong

2018-02-01

In this study, a novel alginate-rubber-strains immobilized beads (ARSIBs) was synthesized at the optimum conditions that the concentration of sodium alginate was 4%; the volume of bacterial suspension was 75%; the quality of rubber powder was 3.2%; the crosslinking time was 24 h by the orthogonal experiments. The optimum conditions for Pb (II) adsorption were 1.2% ARSIBs, 100 mg L-1 initial concentrations, pH 5 and 3 h contact time. The equilibrium data were well fitted by the Freundlich isotherm model. The biosorption process was nearly consistent with the pseudo-second-order model. Meanwhile, the biosorption mechanism could be that Pb (II) was adsorbed by the hydroxyl and carboxyl, finally precipitated with phosphate in the form of NaPb4(PO4)3, Pb5(PO4)3(OH) and Pb(H2PO4)2 based on the spectra of FTIR and XRD, respectively. In addition, the stability of ARSIBs was enhanced due to the addition to the rubber powder in the process of wastewater treatment.

Preparation of microcapsules by complex coacervation of gum Arabic and chitosan.

PubMed

Butstraen, Chloé; Salaün, Fabien

2014-01-01

Gum Arabic-chitosan microcapsules containing a commercially available blend of triglycerides (Miglyol 812 N) as core phase were synthesized by complex coacervation. This study was conducted to clarify the influence of different parameters on the encapsulation process, i.e. during the emulsion formation steps and during the shell formation, using conductometry, zeta potential, surface and interface tension measurement and Fourier-transform infrared spectroscopy. By carefully analyzing the influencing factors including phase volume ratio, stirring rate and time, pH, reaction time, biopolymer ratio and crosslinking effect, the optimum synthetic conditions were found out. For the emulsion step, the optimum phase volume ratio chosen was 0.10 and an emulsion time of 15 min at 11,000 rpm was selected. The results also indicated that the optimum formation of these complexes appears at a pH value of 3.6 and a weight ratio of chitosan to gum Arabic mixtures of 0.25. Copyright © 2013 Elsevier Ltd. All rights reserved.

The biochemical characterization, stabilization studies and the antiproliferative effect of bromelain against B16F10 murine melanoma cells.

PubMed

São Paulo Barretto Miranda, Íngara Keisle; Fontes Suzart Miranda, Anderson; Souza, Fernanda Vidigal Duarte; Vannier-Santos, Marcos André; Pirovani, Carlos Priminho; Pepe, Iuri Muniz; Rodowanski, Ivanoé João; Ferreira, Katiúcia Tícila de Souza Eduvirgens; Mendes Souza Vaz, Luciano; de Assis, Sandra Aparecida

2017-06-01

The current study aims to extract bromelain from different parts (stem, crown, peels, pulp and leaves) of Ananas comosus var. comosus AGB 772; to determine of optimum pH and temperature; to test bromelain stability in disodium EDTA and sodium benzoate, and to investigate its pharmacological activity on B16F10 murine melanoma cells in vitro. The highest enzymatic activity was found in bromelain extracted from the pulp and peel. The optimum bromelain pH among all studied pineapple parts was 6.0. The optimum temperature was above 50 °C in all bromelain extracts. The fluorescence analysis confirmed the stability of bromelain in the presence of EDTA and sodium benzoate. Bromelain was pharmacologically active against B16F10 melanoma cells and it was possible verifying approximately 100% inhibition of tumor cell proliferation in vitro. Since bromelain activity was found in different parts of pineapple plants, pineapple residues from the food industry may be used for bromelain extraction.

Ozonation of Common Textile Auxiliaries

NASA Astrophysics Data System (ADS)

Iskender, Gulen; Arslan-Alaton, Idil; Koyunluoglu, Sebnem; Yilmaz, Zeynep; Germirli Babuna, Fatos

2016-10-01

The treatability of four different commonly applied textile auxiliary chemicals, namely two tannin formulations (Tannin 1: a condensation product of aryl sulphonate; Tannin 2: natural tannic acid) and two biocidal finishing agents (Biocide 1: 2,4,4’-trichloro-2’- hydroxydiphenyl ether; Biocide 2: a nonionic diphenyl alkane derivative) with ozone was investigated. Increasing the ozone dose yielded higher COD removals for the natural tannin. Optimum ozone doses of 485 and 662 mg/h were obtained at a pH of 3.5 for natural and synthetic tannin carrying textile bath discharges, respectively. When the reaction pH was increased from 3.5 to 7.0, a slight decrease in COD removal was observed for the natural tannin due to ozone selectivity towards its polyaromatic structure. The same increase in ozonation pH enhanced COD removals for the synthetic tannin as a result of enhanced ozone decomposition rendering free radical chain reactions dominant. Optimum ozone doses of 499 and 563 mg/h were established for Biocide 1 and 2, respectively. With the increase of ozonation, pH exhibited a positive influence on COD removals for both textile tannins. A substantial improvement in terms of TOC removals was observed as the reaction pH was increased from 3.5 to 7.0 for the synthetic tannin, and from 7 to 12 for both textile biocides. Higher AOX removals were evident at pH 7 than at pH 12 for Biocide 1 as a result of the higher selectivity of the dehalogenation reaction at neutral pH.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rudneva, Irina A.; Timofeeva, Tatiana A.; Ignatieva, Anna V.

In the present study we assessed pleiotropic characteristics of the antibody-selected mutations. We examined pH optimum of fusion, temperatures of HA heat inactivation, and in vitro and in vivo replication kinetics of the previously obtained influenza H5 escape mutants. Our results showed that HA1 N142K mutation significantly lowered the pH of fusion optimum. Mutations of the escape mutants located in the HA lateral loop significantly affected H5 HA thermostability (P<0.05). HA changes at positions 131, 144, 145, and 156 and substitutions at positions 131, 142, 145, and 156 affected the replicative ability of H5 escape mutants in vitro and inmore » vivo, respectively. Overall, a co-variation between antigenic specificity and different HA phenotypic properties has been demonstrated. We believe that the monitoring of pleiotropic effects of the HA mutations found in H5 escape mutants is essential for accurate prediction of mutants with pandemic potential. - Highlights: • HA1 N142K mutation significantly lowered the pH of fusion optimum. • Mutations located in the HA lateral loop significantly affected H5 HA thermostability. • HA changes at positions 131, 142, 144, 145, and 156 affected the replicative ability of H5 mutants. • Acquisition of glycosylation site could lead to the emergence of multiple pleiotropic effects.« less

Solid-substrate bioprocessing of cow dung for the production of carboxymethyl cellulase by Bacillus halodurans IND18.

PubMed

Vijayaraghavan, P; Prakash Vincent, S G; Dhillon, G S

2016-02-01

The production of carboxymethyl cellulase (CMCase) by Bacillus halodurans IND18 under solid substrate fermentation (SSF) using cow dung was optimized through two level full factorial design and second order response surface methodology (RSM). The central composite design (CCD) was employed to optimize the vital fermentation parameters, such as pH of the substrate, concentration of nitrogen source (peptone) and ion (sodium dihydrogen phosphate) sources in medium for achieving higher enzyme production. The optimum medium composition was found to be 1.46% (w/w) peptone, 0.095% (w/w) sodium dihydrogen phosphate and pH 8.0. The model prediction of 4210IU/g enzyme activity at optimum conditions was verified experimentally as 4140IU/g. The enzyme was active over a broad temperature range (40-60±1°C) and pH (7.0-9.0) with maximal activity at 60±1°C and pH 8.0. This study demonstrated the potential of cow dung as novel substrate for CMCase production. Copyright © 2015 Elsevier Ltd. All rights reserved.

Degradation of 4-aminoantipyrine by electro-oxidation with a boron-doped diamond anode: Optimization by central composite design, oxidation products and toxicity.

PubMed

de Melo da Silva, Lucas; Gozzi, Fábio; Sirés, Ignasi; Brillas, Enric; de Oliveira, Silvio Cesar; Machulek, Amilcar

2018-08-01

Electro-oxidation with electrogenerated H 2 O 2 (EO-H 2 O 2 ) was applied to treat acidic aqueous solutions of 4-aminoantipyrine (4-AA), a persistent drug metabolite of dipyrone, in sulfate medium. Trials were made using a boron-doped diamond anode in the presence of H 2 O 2 electrogenerated on site. A 2 4 central composite design (CCD) was employed to evaluate the effect of four independent variables, namely current density (j), pH, 4-AA concentration and electrolysis time, on the percentages of degradation and mineralization, as well as on mineralization current efficiency (MCE). Predicted responses agreed with observed values, showing linear trendlines with good R 2 and R 2 adj values. The degradation was optimum at j=77.5mAcm -2 , pH3.5 and 62.5mgL -1 4-AA, leading to 63% and 99% removal after 3 and 7min, respectively. For those solutions, the largest mineralization was found at j=77.5mAcm -2 , attaining 45% abatement at 175min. Low MCE values were obtained in all electrolyses. An initial route for 4-AA degradation is proposed based on one dimer and eleven aromatic and aliphatic intermediates detected in the treated solutions at pH3.5 by LC-MS. The initial 62.5mgL -1 solution at pH3.5 presented acute toxicity on Artemia salina larvae, with LC 50 =13.6mgL -1 , being substantially reduced after 3 and 7min of EO-H 2 O 2 at j=77.5mAcm -2 due to the formation of less toxic derivatives. Copyright © 2018 Elsevier B.V. All rights reserved.

Effect of soya lecithin on the enzymatic system of the white-rot fungi Anthracophyllum discolor.

PubMed

Bustamante, M; González, M E; Cartes, A; Diez, M C

2011-01-01

The present work optimized the initial pH of the medium and the incubation temperature for ligninolytic enzymes produced by the white-rot fungus Anthracophyllum discolor. Additionally, the effect of soya lecithin on mycelial growth and the production of ligninolytic enzymes in static batch cultures were evaluated. The critical micelle concentration of soya lecithin was also studied by conductivity. The effects of the initial pH (3, 4, and 5) and incubation temperature (20, 25, and 30°C) on different enzymatic activities revealed that the optimum conditions to maximize ligninolytic activity were 26°C and pH 5.5 for laccase and manganese peroxidase (MnP) and 30°C and pH 5.5 for manganese-independent peroxidase (MiP). Under these culture conditions, the maximum enzyme production was 10.16, 484.46, and 112.50 U L(-1) for laccase, MnP, and manganese-independent peroxidase MiP, respectively. During the study of the effect of soya lecithin on A. discolor, we found that the increase in soya lecithin concentration from 0 to 10 g L(-1) caused an increase in mycelial growth. On the other hand, in the presence of soya lecithin, A. discolor produced mainly MnP, which reached a maximum concentration of 30.64 ± 4.61 U L(-1) after 25 days of incubation with 1 g L(-1) of the surfactant. The other enzymes were produced but to a lesser extent. The enzymatic activity of A. discolor was decreased when Tween 80 was used as a surfactant. The critical micelle concentration of soya lecithin calculated in our study was 0.61 g L(-1).

Biosorption of antimony(V) by freshwater cyanobacteria Microcystis from Lake Taihu, China: effects of pH and competitive ions.

PubMed

Sun, Fuhong; Yan, Yuanbo; Liao, Haiqing; Bai, Yingchen; Xing, Baoshan; Wu, Fengchang

2014-05-01

There is limited knowledge available on metalloid biosorption by freshwater algae. In this study, biosorption properties of anionic Sb(OH) 6 (-) by naturally occurring cyanobacteria Microcystis were investigated as a function of initial pH, biosorbent dosage, contact time, and addition sequences of competitive ions, and their binding mechanisms were discussed. The biosorption process was fast and equilibrium was reached at 2 h. Sb(V) biosorption decreased with the increase of pH and the optimum pH range was 2.5-3.0, which corresponded with the changes of surface charges of the cell wall of Microcystis. The biosorption data satisfactorily followed the Freundlich model. The simultaneous addition of H2PO4 (-) and Ca(2+) enhanced Sb(V) biosorption, while NO3 (-) greatly inhibited the biosorption, compared with single Sb(V) addition. The initial addition of the competitive ions reduced Sb(V) biosorption at higher Sb(V) concentrations, compared with simultaneous addition. A fraction of biosorbed Sb(V) was replaced by the competitive ions which were added subsequently, and the exchange only occurred at higher concentrations of Sb(V). 1.0 mol/L HCl demonstrated the highest desorption efficiency. Speciation analyses indicated that no reduction of Sb(V) into Sb(III) occurred. Based on the results of zeta potential and attenuated total reflection infrared spectroscopy spectra, Sb(OH) 6 (-) bound to the biomass through electrostatic attraction and surface complexation, and amino, carboxyl, and hydroxyl groups were involved in the biosorption process. The study suggest that Microcystis from cyanobacteria blooms could be used as a potential biosorbent to remove Sb(V) from effluents at environmentally relevant concentrations (≤10.0 mg/L).

Examination of the polished surface character of fused silica.

PubMed

Tesar, A A; Fuchs, B A; Hed, P P

1992-12-01

Investigation of the surface character of fused silica polished with various compounds dispersed in water identified pH 4 as the optimum condition for high quality. Analyses support the conclusion that at this pH redeposition of hydrated material onto the surface during polishing is limited. Comparative polishing results for Zerodur are included. Improvement of the laser-damage threshold of a coating on the pH 4 polished fused silica is suggested.

Optimum Disinfection Properties and Commercially Available Disinfectants

DTIC Science & Technology

1989-07-01

organic constituents that display a chlorine demand.) d. Upon addition to water, the agent should dissolve quickly and release its active ingredient(s...trione pH dependence alkaline pH favored Temperature dependence high at low residual Palatability Taste and odor claimed to be lartgly absent Color...CryptosgortdLjM at various temperature and pH levels. 2. A field procedwu for masueing disinfectant residual is ".eded for chlorin dioaide. 3. Stability

Examination of the polished surface character of fused silica

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tesar, A.A.; Fuchs, B.A.; Hed, P.P.

1992-12-01

Investigation of the surface character of fused silica polished with various compounds dispersed in water identified pH 4 as the optimum condition for high quality. Analyses support the conclusion that at this pH redeposition of hydrated material onto the surface during polishing is limited. Comparative polishing results for Zerodur are included. Improvement of the laser-damage threshold of a coating on the pH 4 polished fused silica is suggested.

Transient kinetic studies of pH-dependent hydrolyses by exo-type carboxypeptidase P on a 27-MHz quartz crystal microbalance.

PubMed

Furusawa, Hiroyuki; Takano, Hiroki; Okahata, Yoshio

2008-02-15

pH-Dependent kinetic parameters (k(on), k(off), and k(cat)) of protein (myoglobin) hydrolyses catalyzed by exo-enzyme (carboxypeptidase P, CPP) were obtained by using a protein-immobilized quartz crystal microbalance (QCM) in acidic aqueous solutions. The formation of the enzyme-substrate (ES) complex (k(on)), the decay of the ES complex (k(off)), and the formation of the product (k(cat)) could be analyzed by transient kinetics as mass changes on the QCM plate. The Kd (k(off)/k(on)) value was different from the Michaelis constant Km calculated from (k(off) + k(cat))/k(on) due to k(cat) > k(off). The rate-determining step was the binding step (k(on), and the catalytic rate k(cat) was faster than other k(on) and k(off) values. In the range of pH 2.5-5.0, values of k(on) gradually increased with decreasing pH showing a maximum at pH 3.7, values of k(off) were independent of pH, and k(cat) increased gradually with decreasing pH. As a result, the apparent rate constant (k(cat)/Km) showed a maximum at pH 3.7 and gradually increased with decreasing pH. The optimum pH at 3.7 of k(on) is explained by the optimum binding ability of CPP to the COOH terminus of the substrate with hydrogen bonds. The increase of k(cat) at the lower pH correlated with the decrease of alpha-helix contents of the myoglobin substrate on the QCM.

Comparison of Fenton process and adsorption method for treatment of industrial container and drum cleaning industry wastewater.

PubMed

Güneş, Elçin; Çifçi, Deniz İzlen; Çelik, Suna Özden

2018-04-01

The present study aims to explore the characterization of industrial container and drum cleaning (ICDC) industry wastewater and treatment alternatives of this wastewater using Fenton and adsorption processes. Wastewater derived from ICDC industry is usually treated by chemical coagulation and biological treatment in Turkey and then discharged in a centralized wastewater treatment facility. It is required that the wastewater COD is below 1500 mg/L to treat in a centralized wastewater treatment facility. The wastewater samples were characterized for parameters of pH, conductivity, COD, BOD 5 , TSS, NH 3 -N, TN, TOC, TP, Cd, Cr, Cu, Fe, Ni, Pb, Zn, and Hg. Initial COD values were in the range of 11,300-14,200 mg/L. The optimum conditions for Fenton treatment were 35-40 g/L for H 2 O 2 , 2-5 g/L for Fe 2+ , and 13-36 for H 2 O 2 /Fe 2+ molar ratio. The optimum conditions of PAC doses and contact times in adsorption studies were 20-30 g/L and 5-12 h, respectively. Removal efficiencies of characterized parameters for the three samples were compared for both Fenton and adsorption processes under optimum conditions. The results suggest that these wastewaters are suitable for discharge to a centralized wastewater treatment plant.

Ultrasonic enhancement of the simultaneous removal of quaternary toxic organic dyes by CuO nanoparticles loaded on activated carbon: Central composite design, kinetic and isotherm study.

PubMed

Dashamiri, Somayeh; Ghaedi, Mehrorang; Dashtian, Kheibar; Rahimi, Mahmood Reza; Goudarzi, Alireza; Jannesar, Ramin

2016-07-01

Copper oxide nanoparticles loaded on activated carbon (CuO-NPs-AC) were prepared and fully analyzed and characterized with FE-SEM, XRD and FT-IR. Subsequently, this novel material was used for simultaneous ultrasound-assisted adsorption of brilliant green (BG), auramine O (AO), methylene blue (MB) and eosin yellow (EY) dyes. Problems regard to dyes spectra overlap in quaternary solution of this dyes were omitted by derivative spectrophotometric method. The best pH in quaternary system was studied by using one at a time method to achieved maximum dyes removal percentage. Subsequently, sonication time, adsorbent dosage and initial dyes concentrations influence on dyes removal was optimized by central composite design (CCD) combined with desirability function approach (DFA). Desirability score of 0.978 show optimum conditions set at sonication time (4.2 min), adsorbent mass (0.029 g), initial dyes concentration (4.5 mg L(-1)). Under this optimum condition the removal percentage for MB, AO, EY and BG dyes 97.58, 94.66, 96.22 and 94.93, respectively. The adsorption rate well fitted by pseudo second-order while adsorption capacity according to the Langmuir model as best equilibrium isotherm model for BG, MB, AO and EY was 20.48, 21.26, 22.34 and 21.29 mg g(-1), respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

Liquid Phase adsorption kinetics and equilibrium of toluene by novel modified-diatomite.

PubMed

Sheshdeh, Reza Khalighi; Abbasizadeh, Saeed; Nikou, Mohammad Reza Khosravi; Badii, Khashayar; Sharafi, Mohammad Sadegh

2014-01-01

The adsorption equilibria of toluene from aqueous solutions on natural and modified diatomite were examined at different operation parameters such as pH, contact time, initial toluene concentration was evaluated and optimum experimental conditions were identified. The surface area and morphology of the nanoparticles were characterized by SEM, BET, XRD, FTIR and EDX analysis. It was found that in order to obtain the highest possible removal of toluene, the experiments can be carried out at pH 6, temperature 25°C, an agitation speed of 200 rpm, an initial toluene concentration of 150 mg/L, a centrifugal rate of 4000 rpm, adsorbent dosage = 0.1 g and a process time of 90 min. The results of this work show that the maximum percentage removal of toluene from aqueous solution in the optimum conditions for NONMD was 96.91% (145.36 mg/g). Furthermore, under same conditions, the maximum adsorption of natural diatomite was 71.45% (107.18 mg/g). Both adsorption kinetic and isotherm experiments were carried out. The experimental data showed that the adsorption follows the Langmuir model and Freundlich model on natural and modified diatomite respectively. The kinetics results were found to conform well to pseudo-second order kinetics model with good correlation. Thus, this study demonstrated that the modified diatomite could be used as potential adsorbent for removal of toluene from aqueous solution.

pH controls over methanogenesis and iron reduction along soil depth profile in Arctic tundra

NASA Astrophysics Data System (ADS)

Zheng, J.; Gu, B.; Wullschleger, S. D.; Graham, D. E.

2017-12-01

Increasing soil temperature in the Arctic is expected to accelerate rates of soil organic matter decomposition. However, the magnitude of this impact is uncertain due to the many physical, chemical, and biological processes that control the decomposition pathways. Varying soil redox conditions present a key control over pathways of organic matter decomposition by diverting the flow of reductants among different electron accepting processes and further driving acid-base reactions that alter soil pH. In this study we investigated the pH controls over anaerobic carbon mineralization, methanogenesis, Fe(III) reduction and the interplay between these processes across a range of pH and redox conditions. pH manipulation experiments were conducted by incubating soils representing organic, mineral, cryoturbated transitional layers and permafrost. In the experiments we sought to understand (1) if methanogenesis or Fe(III) reduction had similar pH optima; (2) if this pH response also occurs at `upstream' fermentation process; and (3) if pH alters organo-mineral association or organic matter sorption and desorption and its availability for microbial degradation. Our preliminary results suggest that the common bell-shaped pH response curve provides a good fit for both Fe(III) reduction and methanogenesis, with optimum pH at 6.0-7.0. Exceptions to this were found in transitional layer where methanogenesis rates positively correlated with increasing pH, with maximum rates measured at pH 8.5. It is likely that the transitional layer harbors distinct groups of methanogens that prefer a high pH. Variations in the optimum pH of Fe(III) reduction and methanogenesis may play a significant role in regulating organic matter decomposition pathways and thus greenhouse gas production in thawing soils. These results support biogeochemical modeling efforts to accurately simulate organic matter decomposition under changing redox and pH conditions.

The potential of melt-mixed polypropylene-zeolite blends in the removal of heavy metals from aqueous media

NASA Astrophysics Data System (ADS)

Motsa, Machawe M.; Thwala, Justice M.; Msagati, Titus A. M.; Mamba, Bhekie B.

The continued deterioration of the water quality in natural water sources such as rivers and lakes has led to tensions amongst relevant stakeholders to such an extent that cooperative water resource management is being regarded as an ideal solution to culminate conflicts and maximise the benefits. The desire to develop technologies that combine the three most important aspects of integrated water resource management (namely social, economic and environmental) has been encouraged by relevant authorities. This paper therefore reports the application of clinoptilolite-polypropylene (CLI-PP) blends/composites for the removal of lead from aqueous media. Just like many other heavy metals, lead poses a threat to water and soil quality as well as to plant and animal health. The findings on the adsorption behaviour of clinoptilolite-polypropylene composites with respect to Pb 2+ are also reported here, with the aim of extending its application to wastewater and environmental water purification. The batch equilibrium adsorption method was employed and the influence of contact time, pH, initial metal-ion concentration, temperature and pretreatment was determined. The optimum pH was found to be between pH 6 and pH 8 while the maximum sorption of lead at optimal pH was 95%. No big difference was observed between the adsorption behaviour of composites functionalised with 20% and 30% clinoptilolite, respectively. The pretreatment with HCl and NaCl made a slight difference to the adsorption capacity of composites.

Batch technique to evaluate the efficiency of different natural adsorbents for defluoridation from groundwater

NASA Astrophysics Data System (ADS)

Kumar, Pankaj; Saraswat, Chitresh; Mishra, Binaya Kumar; Avtar, Ram; Patel, Hiral; Patel, Asha; Sharma, Tejal; Patel, Roshni

2017-09-01

Fluoride pollution (with concentration >1.0 mg/L) in groundwater has become a global threat in the recent past due to the lesser availability of potable groundwater resource. In between several defluoridation techniques discovered so far, the adsorption process proved to be most economic and efficient. This study is an effort to evaluate defluoridation efficiency of powdered rice husk, fine chopped rice husk and sawdust by the batch adsorption process. Optimum defluoridation capacity is achieved by optimizing various parameters, viz. dose of adsorbent, pH, contact time and initial concentration. It was found that all three materials can be employed for the defluoridation technique, but powdered rice husk is the best adsorbent in the midst of all three. Powdered rice husk showed fluoride removal efficiency ranging between 85 and 90 % in the contact period of 7 h only in conditions of all optimized parameter. Following this parameter optimization, adsorption efficiency was also evaluated at natural pH of groundwater to minimize the cost of defluoridation. No significant difference was found between fluoride adsorption at optimized pH (pH = 4) and natural one (pH = 7), which concludes that powdered rice husk can be efficiently used for the defluoridation technique at field scale. The adsorption isotherm using this adsorbent perfectly followed Langmuir isotherms. The value of calculated separation factor also suggests the favourable adsorption of fluoride onto this adsorbent under the conditions used for the experiments. The field application for defluoridation of groundwater using this adsorbent (based on pH of natural groundwater there and seasonal variation of temperature) showed the high success rate.

Optimization of maltodextrin production from avocado seed starch by response surface methodology

NASA Astrophysics Data System (ADS)

Nguyen, Thanh Viet; Ma, Tuyen-Hoang Nguyen; Nguyen, Tha Thi; Ho, Vinh-Nghi Kim; Vo, Hau Tan

2018-04-01

A process for maltodextrin production from avocado seed starch was reported in this study. Response surface methodology was used to investigate the effects of three independent variables for hydrolysis of the starch using a commercial food-grade α-amylase, Termamyl SC. These variables included enzyme concentration (0.05 - 0.15% starch), pH (5.0 - 6.0) and hydrolysis time (1.0 - 3.0 h), while the temperature fixed at 95°C. The result showed that the optimum conditions were using enzyme concentration at 0.12%, pH at 5.5 and 2.75 h of the incubation time. Under the optimum conditions, the recovered starch yield was 79.8% and the maltodextrin powder had 15.8 of dextrose equivalent.

Investigation on removal of malachite green using EM based compost as adsorbent.

PubMed

Bhagavathi Pushpa, T; Vijayaraghavan, J; Sardhar Basha, S J; Sekaran, V; Vijayaraghavan, K; Jegan, J

2015-08-01

The discarded materials from different sources can be utilized as effective materials in wastewater remediation. This proposed study was aimed mainly to investigate the possibility of Effective Microorganisms based compost (EMKC), which is derived from the kitchen solid waste, as a non-conventional low cost adsorbent for the removal of malachite green from aqueous solution. Batch experiments were carried out to evaluate the optimum operating parameters like pH (2-9), initial dye concentration (50-1000mg/L), adsorbent particle size (0.6-2.36mm) and adsorbent dosage (2-12g/L). EMKC recorded maximum uptake of 136.6mg/g of MG at pH 8, initial dye concentration 1000mg/L, adsorbent particle size 1.18mm and adsorbent dosage 4g/L. Two and three parameter adsorption models were employed to describe experimental biosorption isotherm data. The results revealed that the Sips model resulted in better fit than other models. The pseudo-first and -second order models were applied to describe kinetic data, of which the pseudo-second order described experimental data better with high correlation coefficient. This investigation suggested that EMKC could be an effective and low cost material for the removal of malachite green dye from aqueous solution. Copyright © 2015 Elsevier Inc. All rights reserved.

The effect of turbidity levels and Moringa oleifera concentration on the effectiveness of coagulation in water treatment.

PubMed

Nkurunziza, T; Nduwayezu, J B; Banadda, E N; Nhapi, I

2009-01-01

Laboratory experiments were carried out to assess the water purification and antimicrobial properties of Moringa oleifera (MO). Hence different concentrations (25 to 300 mg/L) were prepared from a salt (1 M NaCl) extract of MO fine powder and applied to natural surface water whose turbidity levels ranged from 50 to 450 NTU. The parameters determined before and after coagulation were turbidity, pH, colour, hardness, iron, manganese and Escherichia coli. The experiments showed that turbidity removal is influenced by the initial turbidity since the lowest turbidity removal of 83.2% was observed at 50 NTU, whilst the highest of 99.8% was obtained at 450 NTU. Colour removal followed the same trend as the turbidity. The pH exhibited slight variations through the coagulation. The hardness removal was very low (0 to 15%). However, high removals were achieved for iron (90.4% to 100%) and manganese (93.1% to 100%). The highest E. coli removal achieved was 96.0%. Its removal was associated with the turbidity removal. The optimum MO dosages were 150 mg/L (50 NTU and 150 NTU) and 125 mg/L for the rest of the initial turbidity values. Furthermore all the parameters determined satisfied the WHO guidelines for drinking water except for E. coli.

Development of a new adsorbent from agro-industrial waste and its potential use in endocrine disruptor compound removal.

PubMed

Rovani, Suzimara; Censi, Monique T; Pedrotti, Sidnei L; Lima, Eder C; Cataluña, Renato; Fernandes, Andreia N

2014-04-30

A new activated carbon (AC) material was prepared by pyrolysis of a mixture of coffee grounds, eucalyptus sawdust, calcium hydroxide and soybean oil at 800°C. This material was used as adsorbent for the removal of the endocrine disruptor compounds 17β-estradiol (E2) and 17α-ethinylestradiol (EE2) from aqueous solutions. The carbon material was characterized by scanning electron microscopy (SEM), infrared spectroscopy (FTIR), N2 adsorption/desorption curves and point of zero charge (pHPZC). Variables including the initial pH of the adsorbate solutions, adsorbent masses and contact time were optimized. The optimum range of initial pH for removal of endocrine disruptor compounds (EDC) was 2.0-11.0. The kinetics of adsorption were investigated using general order, pseudo first-order and pseudo-second order kinetic models. The Sips isotherm model gave the best fits of the equilibrium data (298K). The maximum amounts of E2 and EE2 removed at 298K were 7.584 (E2) and 7.883mgg(-1) (EE2) using the AC as adsorbent. The carbon adsorbent was employed in SPE (solid phase extraction) of E2 and EE2 from aqueous solutions. Copyright © 2014 Elsevier B.V. All rights reserved.

Potential immobilized Saccharomyces cerevisiae as heavy metal removal

NASA Astrophysics Data System (ADS)

Raffar, Nur Izzati Abdul; Rahman, Nadhratul Nur Ain Abdul; Alrozi, Rasyidah; Senusi, Faraziehan; Chang, Siu Hua

2015-05-01

Biosorption of copper ion using treated and untreated immobilized Saccharomyces cerevisiae from aqueous solution was investigate in this study. S.cerevisiae has been choosing as biosorbent due to low cost, easy and continuously available from various industries. In this study, the ability of treated and untreated immobilized S.cerevisiae in removing copper ion influence by the effect of pH solution, and initial concentration of copper ion with contact time. Besides, adsorption isotherm and kinetic model also studied. The result indicated that the copper ion uptake on treated and untreated immobilized S.cerevisiae was increased with increasing of contact time and initial concentration of copper ion. The optimum pH for copper ion uptake on untreated and treated immobilized S.cerevisiae at 4 and 6. From the data obtained of copper ion uptake, the adsorption isotherm was fitted well by Freundlich model for treated immobilized S.cerevisiae and Langmuir model for untreated immobilized S.cerevisiae according to high correlation coefficient. Meanwhile, the pseudo second order was described as suitable model present according to high correlation coefficient. Since the application of biosorption process has been received more attention from numerous researchers as a potential process to be applied in the industry, future study will be conducted to investigate the potential of immobilized S.cerevisiae in continuous process.

Adsorptive removal of Cu(II) from aqueous solution and industrial effluent using natural/agricultural wastes.

PubMed

Singha, Biswajit; Das, Sudip Kumar

2013-07-01

The potentiality of low cost natural/agricultural waste biomasses for the removal of Cu(II) ion from aqueous solution has been investigated in batch experiments. The effect of various physico-chemical parameters such as initial pH, initial Cu(II) concentration, adsorbent dosage, contact time and temperature has been studied. The optimum pH for adsorption was found to be 6 for all adsorbents used. Kinetics data were best described by the pseudo-2nd-order model. The experimental data were fitted well with Freundlich and Halsey isotherm models. The diffusion coefficient and sorption energy indicated that the adsorption process was chemical in nature. Thermodynamic parameters such as ΔG°, ΔH° and ΔS° were calculated, and it was observed that the adsorption process was spontaneous and endothermic. The mean sorption energy was calculated using Dubinin-Radushkevich isotherm model and it confirmed that the sorption process was chemical in nature. Different active functional groups were identified by FTIR studies which were responsible for Cu(II) ion adsorption process. Application study using electroplating industrial waste water and regeneration experiment of the adsorbent were also investigated. Design procedure for the batch process was also reported. Copyright © 2013 Elsevier B.V. All rights reserved.

Fermentative production of l-galactonate by using recombinant Saccharomyces cerevisiae containing the endogenous galacturonate reductase gene from Cryptococcus diffluens.

PubMed

Matsubara, Takeo; Hamada, Shohei; Wakabayashi, Ayaka; Kishida, Masao

2016-11-01

The GAR1 gene, encoding d-galacturonate reductase in Cryptococcus diffluens, was isolated, and the GAR1-expression plasmid was constructed by insertion of GAR1 downstream of the yeast constitutive promoter in the yeast-integrating vector. Recombinant Saccharomyces cerevisiae expressing C. diffluensd-galacturonate reductase from a genome integrated copy of the gene was cultured for use the conversion of d-galacturonic acid to l-galactonic acid. The optimum conditions for l-galactonic acid production were determined in terms of the initial concentration of d-galacturonic acid, fermentation pH, and mixed sugars. The following conditions yielded high efficiency in the conversion of d-galacturonic acid to l-galactonic acid in large-scale cultures: 0.1% initial d-galacturonic acid concentration, pH 3.5, and glucose as additional sugar. The aerobic condition was necessary for the conversion of d-galacturonic acid. Subculture of that recombinant was not showing to decrease of the d-galacturonic acid conversion rate even though it was repeated in ten generations. Culturing in scale-up, the conversion rate of d-galacturonic acid to l-galactonic acid was increased. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Utilization Chitosan-p-t-Butylcalix[4]Arene for Red MX 8B Adsorbent

NASA Astrophysics Data System (ADS)

Handayani, D. S.; Kusumaningsih, T.; Hak, L. A.

2017-02-01

Adsorption of Procion Red MX 8B using chitosan dan chitosan-linked p-t-butylcalix[4]arene has been done. The research aimed to understand the adsorption of Procion Red MX 8B using chitosan p-t-butylcalix[4]arene compared to ordinary chitosan. The research was conducted in a batch process varying in pH, contact time and initial concentration of the Procion Red MX 8B. The amount of dye adsorbed was determined using UV-Vis spectrophotometer and the adsorben was characterized using FTIR and SEM-EDX spectrophotometer. The result showed that the optimum condition was achieved when the pH was set at 4, contact time 135 minutes and initial concentration at 200 ppm. The kinetic analysis showed that the adsorption followed Ho kinetic model and pseudo second order with the adsorption rate constant was 3.69×10-3 g/mg.minute and 2.03×10-3 g/mg.minute. The isotherm analysis showed that the adsorption process tend to occur following the Langmuir model with maximum capacity for chitosan and chitosan-linked p-t-butylcalix[4]arene 136.09 mg/g and 147.35 mg/g respectively. The adsorption energy of chitosan and chitosan-linked p-t-butylcalix[4]arene at 30.53 kJ/mole and 33.65 kJ/mole.

Adsorption capacity of Curcuma longa for the removal of basic green 1 dye--equilibrium, kinetics and thermodynamic study.

PubMed

Roopavathi, K V; Shanthakumar, S

2016-09-01

In the present study, Curcuma longa (turmeric plant) was used as an adsorbent to remove Basic Green 1 (BG) dye. Batch study was carried out to evaluate the adsorption potential of C. longa and influencing factors such as pH (4-10), adsorbent dose (0.2-5 g l-1), initial dye concentration (50-250 mg l-1) and temperature (30-50°C) on dye removal were analysed. The characterisation of adsorbent was carried out using fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and Brunauer, Emmett and Teller (BET) method. Isotherm models that included Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich, and kinetic models such as pseudo first order, pseudo second-order, Elovich and intraparticle diffusion models were studied. A maximum removal percentage (82.76%) of BG dye from aqueous solution was obtained with optimum conditions of pH 7, 1g l-1 adsorbent dose and 30°C temperature, for 100 mg l-1 initial dye concentration. The equilibrium and kinetic study revealed that the experimental data fitted suitably the Freundlich isotherm and Pseudo second order kinetic model. Thermodynamic analysis proved that adsorption system in this study was spontaneous, feasible and endothermic in nature.

Prediction of phycoremediation of As(III) and As(V) from synthetic wastewater by Chlorella pyrenoidosa using artificial neural network

NASA Astrophysics Data System (ADS)

Podder, M. S.; Majumder, C. B.

2017-11-01

An artificial neural network (ANN) model was developed to predict the phycoremediation efficiency of Chlorella pyrenoidosa for the removal of both As(III) and As(V) from synthetic wastewater based on 49 data-sets obtained from experimental study and increased the data using CSCF technique. The data were divided into training (60%) validation (20%) and testing (20%) sets. The data collected was used for training a three-layer feed-forward back propagation (BP) learning algorithm having 4-5-1 architecture. The model used tangent sigmoid transfer function at input to hidden layer ( tansing) while a linear transfer function ( purelin) was used at output layer. Comparison between experimental results and model results gave a high correlation coefficient (R allANN 2 equal to 0.99987 for both ions and exhibited that the model was able to predict the phycoremediation of As(III) and As(V) from wastewater. Experimental parameters influencing phycoremediation process like pH, inoculum size, contact time and initial arsenic concentration [either As(III) or As(V)] were investigated. A contact time of 168 h was mainly required for achieving equilibrium at pH 9.0 with an inoculum size of 10% (v/v). At optimum conditions, metal ion uptake enhanced with increasing initial metal ion concentration.

Multidrug resistance protein MdtM adds to the repertoire of antiporters involved in alkaline pH homeostasis in Escherichia coli

PubMed Central

2013-01-01

Background In neutralophilic bacteria, monovalent metal cation/H+ antiporters play a key role in pH homeostasis. In Escherichia coli, only four antiporters (NhaA, NhaB, MdfA and ChaA) are identified to function in maintenance of a stable cytoplasmic pH under conditions of alkaline stress. We hypothesised that the multidrug resistance protein MdtM, a recently characterised homologue of MdfA and a member of the major facilitator superfamily, also functions in alkaline pH homeostasis. Results Assays that compared the growth of an E. coli ΔmdtM deletion mutant transformed with a plasmid encoding wild-type MdtM or the dysfunctional MdtM D22A mutant at different external alkaline pH values (ranging from pH 8.5 to 10) revealed a potential contribution by MdtM to alkaline pH tolerance, but only when millimolar concentrations of sodium or potassium was present in the growth medium. Fluorescence-based activity assays using inverted vesicles generated from transformants of antiporter-deficient (ΔnhaA, ΔnhaB, ΔchaA) E. coli TO114 cells defined MdtM as a low-affinity antiporter that catalysed electrogenic exchange of Na+, K+, Rb+ or Li+ for H+. The K+/H+ antiport reaction had a pH optimum at 9.0, whereas the Na+/H+ exchange activity was optimum at pH 9.25. Measurement of internal cellular pH confirmed MdtM as contributing to maintenance of a stable cytoplasmic pH, acid relative to the external pH, under conditions of alkaline stress. Conclusions Taken together, the results support a role for MdtM in alkaline pH tolerance. MdtM can therefore be added to the currently limited list of antiporters known to function in pH homeostasis in the model organism E. coli. PMID:23701827

Multidrug resistance protein MdtM adds to the repertoire of antiporters involved in alkaline pH homeostasis in Escherichia coli.

PubMed

Holdsworth, Scarlett R; Law, Christopher J

2013-05-23

In neutralophilic bacteria, monovalent metal cation/H+ antiporters play a key role in pH homeostasis. In Escherichia coli, only four antiporters (NhaA, NhaB, MdfA and ChaA) are identified to function in maintenance of a stable cytoplasmic pH under conditions of alkaline stress. We hypothesised that the multidrug resistance protein MdtM, a recently characterised homologue of MdfA and a member of the major facilitator superfamily, also functions in alkaline pH homeostasis. Assays that compared the growth of an E. coli ΔmdtM deletion mutant transformed with a plasmid encoding wild-type MdtM or the dysfunctional MdtM D22A mutant at different external alkaline pH values (ranging from pH 8.5 to 10) revealed a potential contribution by MdtM to alkaline pH tolerance, but only when millimolar concentrations of sodium or potassium was present in the growth medium. Fluorescence-based activity assays using inverted vesicles generated from transformants of antiporter-deficient (ΔnhaA, ΔnhaB, ΔchaA) E. coli TO114 cells defined MdtM as a low-affinity antiporter that catalysed electrogenic exchange of Na+, K+, Rb+ or Li+ for H+. The K+/H+ antiport reaction had a pH optimum at 9.0, whereas the Na+/H+ exchange activity was optimum at pH 9.25. Measurement of internal cellular pH confirmed MdtM as contributing to maintenance of a stable cytoplasmic pH, acid relative to the external pH, under conditions of alkaline stress. Taken together, the results support a role for MdtM in alkaline pH tolerance. MdtM can therefore be added to the currently limited list of antiporters known to function in pH homeostasis in the model organism E. coli.

Biochemical characteristics and thermal inhibition kinetics of polyphenol oxidase extracted from Thompson seedless grape

USDA-ARS?s Scientific Manuscript database

Polyphenol oxidase (PPO) was isolated from Thompson seedless grape (Vitis vinifera 'Thompson Seedless') and its biochemical characteristics were studied. Optimum pH and temperature for grape PPO activity were pH 6.0 and 25 degrees C with 10 mM catechol as substrate. The enzyme was heat-stable betwee...

Electrocoagulation and nanofiltration integrated process application in purification of bilge water using response surface methodology.

PubMed

Akarsu, Ceyhun; Ozay, Yasin; Dizge, Nadir; Elif Gulsen, H; Ates, Hasan; Gozmen, Belgin; Turabik, Meral

Marine pollution has been considered an increasing problem because of the increase in sea transportation day by day. Therefore, a large volume of bilge water which contains petroleum, oil and hydrocarbons in high concentrations is generated from all types of ships. In this study, treatment of bilge water by electrocoagulation/electroflotation and nanofiltration integrated process is investigated as a function of voltage, time, and initial pH with aluminum electrode as both anode and cathode. Moreover, a commercial NF270 flat-sheet membrane was also used for further purification. Box-Behnken design combined with response surface methodology was used to study the response pattern and determine the optimum conditions for maximum chemical oxygen demand (COD) removal and minimum metal ion contents of bilge water. Three independent variables, namely voltage (5-15 V), initial pH (4.5-8.0) and time (30-90 min) were transformed to coded values. The COD removal percent, UV absorbance at 254 nm, pH value (after treatment), and concentration of metal ions (Ti, As, Cu, Cr, Zn, Sr, Mo) were obtained as responses. Analysis of variance results showed that all the models were significant except for Zn (P > 0.05), because the calculated F values for these models were less than the critical F value for the considered probability (P = 0.05). The obtained R(2) and Radj(2) values signified the correlation between the experimental data and predicted responses: except for the model of Zn concentration after treatment, the high R(2) values showed the goodness of fit of the model. While the increase in the applied voltage showed negative effects, the increases in time and pH showed a positive effect on COD removal efficiency; also the most effective linear term was found as time. A positive sign of the interactive coefficients of the voltage-time and pH-time systems indicated synergistic effect on COD removal efficiency, whereas interaction between voltage and pH showed an antagonistic effect.

Optimizing the synthesis conditions of silver nanoparticles using corn starch and their catalytic reduction of 4-nitrophenol

NASA Astrophysics Data System (ADS)

Salaheldin, Hosam I.

2018-06-01

In this study, silver nanoparticles (SNPs) were synthesised in an aqueous solution of corn starch. To fabricate the SNPs, reaction conditions, such as varying silver nitrate () concentration, time, temperature and solution pH of the reaction, were optimized. Since, the optimum reaction conditions were found 1 mmo l‑1, 15 min and , respectively. Then, to study the role of pH on SNP synthesis, varying pH values of the solution (3, 5, 7, 9 and 11) were investigated. Subsequently, the obtained silver/starch nanocomposites were characterised using different techniques. The x-ray diffraction (XRD) results revealed that the particles were face-centred cubic (FCC), and had an average particle size of 7.5 nm. This was confirmed by high-resolution transmission electron microscopy (HR-TEM) images. Moreover, the synthesised SNPs, at different pH values, were used as nanocatalyst for the reduction of 4-nitrophenol to 4-aminophenol in the presence of sodium borohydride. Under optimum reaction conditions, the higher catalytic activity was obtained with SNPs synthesised at pH 11 compared to lower pH of 7 or 9. Therefore, the rapid, reproducible, cost-effective silver/starch nanocomposite can be widely used for various applications such as drug manufacturing (e.g. analgesics and antipyretics) and the removal of pollutants from wastewater.

Conversion of shrimp shell by using Serratia sp. TKU017 fermentation for the production of enzymes and antioxidants.

PubMed

Wang, San-Lang; Li, Jeng-Yu; Liang, Tzu-Wen; Hsieh, Jia-Lin; Tseng, Wan-Nine

2010-01-01

A chitinase (CHT), and a protease (PRO) were purified from the culture supernatant of Serratia sp. TKU017 with shrimp shell as the sole carbon/nitrogen source. The molecular masses of CHT and PRO determined by SDS-PAGE were approximately 65 kDa and 53 kDa, respectively. CHT was inhibited by Mn2+, Cu2+ and PRO was inhibited by most tested divalent metals, EDTA. The optimum pH, optimum temperature, pH stability, and thermal stability of CHT and PRO were (pH 5, 50 degrees , pH 5 degrees ) and (pH 9, 40 degrees , pH 5 degrees ), respectively. PRO retained 95% of its protease activity in the presence of 0.5 mM SDS. The result demonstrates that PRO is SDS-resistant protease and probably has a rigid structure. The 4th day supernatant showed the strongest antioxidant activity (70%, DPPH scavenging ability) and the highest total phenolic content (196+/-6.2 microng of gallic acid equival/mL). Significant associations between the antioxidant potency and the total phenolic content, as well as between the antioxidant potency and free amino groups, were found for the supernatant. With this method, we have shown that shrimp shell wastes can be utilized and it's effective in the production of enzymes and antioxidants, facilitating its potential use in industrial applications and functional foods.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qasim, Mohammad A., E-mail: qasimm@ipfw.edu; Song, Jikui; Markley, John L.

Research highlights: {yields} Large pK shifts in ionizable groups when buried in the protein interior. {yields} Substrate dependent shifts in pH optimum for serine proteases. {yields} Lys side chain is a stronger acid in serine protease S{sub 1} pocket than Asp side chain. -- Abstract: Enzymatic hydrolysis of the synthetic substrate succinyl-Ala-Ala-Pro-Xxx-pNA (where Xxx = Leu, Asp or Lys) catalyzed by bovine chymotrypsin (CHYM) or Streptomyces griseus protease B (SGPB) has been studied at different pH values in the pH range 3-11. The pH optima for substrates having Leu, Asp, and Lys have been found to be 7.5-8.0, 5.5-6.0, andmore » {approx}10, respectively. At the normally reported pH optimum (pH 7-8) of CHYM and SGPB, the substrate with Leu at the reactive site is more than 25,000-fold more reactive than that with Asp. However, when fully protonated, Asp is nearly as good a substrate as Leu. The pK values of the side chains of Asp and Lys in the hydrophobic S{sub 1} pocket of CHYM and SGPB have been calculated from pH-dependent hydrolysis data and have been found to be about 9 for Asp and 7.4 and 9.7 for Lys for CHYM and SGPB, respectively. The results presented in this communication suggest a possible application of CHYM like enzymes in cleaving peptide bonds contributed by acidic amino acids between pH 5 and 6.« less

Laboratory investigation of inorganic carbon uptake by cryoconite debris from Werenskioldbreen, Svalbard

NASA Astrophysics Data System (ADS)

Stibal, Marek; Tranter, Martyn

2007-12-01

Laboratory experiments were undertaken to determine the inorganic carbon uptake rate and the interactions between photosynthesis and water chemistry, particularly pH and nutrient concentrations, for cryoconite debris from Werenskioldbreen, a well-researched Svalbard glacier. Microorganisms in cryoconite debris took up inorganic carbon at rates between 0.6 and 15 μg C L-1 h-1 and fixed it as organic carbon. Cyanobacterial photosynthesis (75-93%) was the main process responsible for inorganic carbon fixation, while heterotrophic uptake (6-15%) only accounted for a minor part. The microbes in cryoconite debris were active shortly after melt and fixed carbon as long as there were favorable conditions. They were not truly psychrophilic: their physiological optimum temperature was higher than is prevalent in cryoconite holes. The pH was also a factor affecting photosynthesis in the cryoconite slurry. The highest dissolved inorganic carbon (DIC) uptake rates per liter of slurry occurred at pH ˜7, and there was a significant correlation between the initial pH and DIC fixation on a per cell basis, showing increasing DIC uptake rates when pH increased from ˜5.5 to 9. Inorganic carbon fixation resulted in an increased pH in solution. However, the microbes were able to photosynthesize in a wide range of pH from ˜4 to ˜10. The average C:N:P molar ratios in solution were ˜350:75:1. Unlike nitrogen, phosphorus concentrations decreased with increasing carbon uptake, and when the rate approached ˜15 μg C L-1 h-1, all available dissolved phosphorus was utilized within 6 h. Hence phosphorus is probably biolimiting in this system.

Treatment of Palm Oil Mill Effluent by a Microbial Consortium Developed from Compost Soils

PubMed Central

Nwuche, Charles O.; Ogbonna, James C.

2014-01-01

A method for the aerobic treatment of palm oil mill effluent (POME) was investigated in shake-flask experiments using a consortium developed from POME compost. POME was initially centrifuged at 4,000 g for 15 min and the supernatant was enriched with (NH4)2SO4 (0.5%) and yeast extract (0.25%) to boost its nitrogen content. At optimum pH (pH 4) and temperature (40°C) conditions, the chemical oxygen demand (COD) of the effluent decreased from 10,350 to 1,000 mg/L (90.3%) after 7 days. The total bacterial population determined by plate count enumeration was 2.4 × 106 CFU/mL, while the fungal count was 1.8 × 103 colonies/mL. Bacteria of the genera Pseudomonas, Flavobacterium, Micrococcus, and Bacillus were isolated, while the fungal genera included Aspergillus, Penicillium, Trichoderma, and Mucor. When the isolated species were each inoculated into separate batches of the raw effluent, both pH and COD were unchanged. However, at 75 and 50% POME dilutions, the COD dropped by 52 and 44%, respectively, while the pH increased from 4 to 7.53. POME treatment by aerobic method is sustainable and holds promising prospects for cushioning the environment from the problems associated with the use of anaerobic systems. PMID:27433536

Immobilization of pectin depolymerising polygalacturonase using different polymers.

PubMed

Ur Rehman, Haneef; Aman, Afsheen; Nawaz, Muhammad Asif; Karim, Asad; Ghani, Maria; Baloch, Abdul Hameed; Ul Qader, Shah Ali

2016-01-01

Polygalacturonase catalyses the hydrolysis of pectin substances and widely has been used in food and textile industries. In current study, different polymers such as calcium alginate beads, polyacrylamide gel and agar-agar matrix were screened for the immobilization of polygalacturonase through entrapment technique. Polyacrylamide gel was found to be most promising one and gave maximum (89%) immobilization yield as compared to agar-agar (80%) and calcium alginate beads (46%). The polymers increased the reaction time of polygalacturonase and polymers entrapped polygalacturonases showed maximum pectinolytic activity after 10 min of reaction as compared to free polygalacturonase which performed maximum activity after 5.0 min of reaction time. The temperature of polygalacturonase for maximum enzymatic activity was increased from 45°C to 50°C and 55°C when it was immobilized within agar-agar and calcium alginate beads, respectively. The optimum pH (pH 10) of polygalacturonase was remained same when it was immobilized within polyacrylamide gel and calcium alginate beads, but changed from pH 10 to pH 9.0 after entrapment within agar-agar. Thermal stability of polygalacturonase was improved after immobilization and immobilized polygalacturonases showed higher tolerance against different temperatures as compared to free enzyme. Polymers entrapped polygalacturonases showed good reusability and retained more than 80% of their initial activity during 2nd cycles. Copyright © 2015 Elsevier B.V. All rights reserved.

Alkaline Fe(III) reduction by a novel alkali-tolerant Serratia sp. isolated from surface sediments close to Sellafield nuclear facility, UK.

PubMed

Thorpe, Clare L; Morris, Katherine; Boothman, Christopher; Lloyd, Jonathan R

2012-02-01

Extensive denitrification resulted in a dramatic increase in pH (from 6.8 to 9.5) in nitrate-impacted, acetate-amended sediment microcosms containing sediment representative of the Sellafield nuclear facility, UK. Denitrification was followed by Fe(III) reduction, indicating the presence of alkali-tolerant, metal-reducing bacteria. A close relative (99% 16S rRNA gene sequence homology) to Serratia liquefaciens dominated progressive enrichment cultures containing Fe(III)-citrate as the sole electron acceptor at pH 9 and was isolated aerobically using solid media. The optimum growth conditions for this facultatively anaerobic Serratia species were investigated, and it was capable of metabolizing a wide range of electron acceptors including oxygen, nitrate, FeGel, Fe-NTA and Fe-citrate and electron donors including acetate, lactate, formate, ethanol, glucose, glycerol and yeast extract at an optimum pH of c. 6.5 at 20 °C. The alkali tolerance of this strain extends the pH range of highly adaptable Fe(III)-reducing Serratia species from mildly acidic pH values associated with acid mine drainage conditions to alkali conditions representative of subsurface sediments stimulated for extensive denitrification and metal reduction. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Coagulant from Leucaena leucocephala for Chromium Removal

NASA Astrophysics Data System (ADS)

Razak, N. H. Abd; Khairuddin, N.; Ismail, K. N.; Musa, M.

2018-05-01

This research investigated the effectiveness of leucaena leucocephala as a natural coagulant for chromium removal. Leucaena leucocephala is a permanent non-climbing shrub tree which is wild and abundant in Malaysia and commonly known as petai belalang. Coagulation experiment using jar test were performed where the effect of coagulant dosage and pH were examined. The parameters investigated were suspended solid (SS), chemical oxygen demand (COD), biological oxygen demand (BOD), turbidity and chromium content. The optimum of leucaena leucocephala coagulant dosage for removal of suspended solid, turbidity, COD, BOD and Chromium is at range 400-600 mg/L which yielded 45, 31.4, 38.5, 27.5 and 4.05% removal respectively. While the optimum pH is at pH 2-4 (acidic) which give 33.3, 26.8, 33.75, 31.4 and 14.06% removal of suspended solid, COD, BOD, turbidity and chromium content respectively. It is concluded that the leucaena leucocephala showed tremendous potential for chromium removal.

Preparation of Curcumin Loaded Egg Albumin Nanoparticles Using Acetone and Optimization of Desolvation Process.

PubMed

Aniesrani Delfiya, D S; Thangavel, K; Amirtham, D

2016-04-01

In this study, acetone was used as a desolvating agent to prepare the curcumin-loaded egg albumin nanoparticles. Response surface methodology was employed to analyze the influence of process parameters namely concentration (5-15%w/v) and pH (5-7) of egg albumin solution on solubility, curcumin loading and entrapment efficiency, nanoparticles yield and particle size. Optimum processing conditions obtained from response surface analysis were found to be the egg albumin solution concentration of 8.85%w/v and pH of 5. At this optimum condition, the solubility of 33.57%, curcumin loading of 4.125%, curcumin entrapment efficiency of 55.23%, yield of 72.85% and particles size of 232.6 nm were obtained and these values were related to the values which are predicted using polynomial model equations. Thus, the model equations generated for each response was validated and it can be used to predict the response values at any concentration and pH.

Novel inexpensive fungi proteases: Production by solid state fermentation and characterization.

PubMed

Novelli, Paula Kern; Barros, Margarida Maria; Fleuri, Luciana Francisco

2016-05-01

A comparative study was carried out for proteases production using agroindustrial residues as substrate for solid state fermentation (SSF) of several fungal strains. High protease production was observed for most of the microorganisms studied, as well as very different biochemical characteristics, including activities at specific temperatures and a wide range of pH values. The enzymes produced were very different regarding optimum pH and they showed stability at 50 °C. Aspergillus oryzae showed stability at all pH values studied. Penicillium roquefortii and Aspergillus flavipes presented optimum activity at temperatures of 50 °C and 90 °C, respectively. Lyophilized protease from A. oryzae reached 1251.60 U/g and yield of 155010.66 U/kg of substrate. Therefore, the substrate as well as the microorganism strain can modify the biochemical character of the enzyme produced. The high protease activity and stability established plus the low cost of substrates, make these fungal proteases potential alternatives for the biotechnological industry. Copyright © 2015 Elsevier Ltd. All rights reserved.

Adsorption of Ni(II) onto Chemically Modified Spent Grated Coconut (Cocos Nucifera)

NASA Astrophysics Data System (ADS)

Hamzah, F. I.; Khalid, K.; Hanafiah, M. A. K. M.

2017-06-01

A new adsorbent of plant waste origin from coconut processing food factory was explored for removing Ni(II) from aqueous solutions. Several parameters such as pH, dosage, concentration and contact time were studied to obtain optimum conditions for treatment of Ni(II) contaminated wastewater. Spent grated coconut (Cocos nucifera) treated with sulfuric acid (SSGC) showed good adsorption capacity for Ni(II) ion. The amount adsorbed was affected by solution pH with the highest value achieved at pH 5. Other optimum conditions found were; dosage of 0.02 g, and 60 min of equilibrium time. Ni(II) adsorption obeyed the pseudo-second order kinetic model which suggested that chemisorption mechanism occurred in the adsorption process. The equilibrium data presented a better fitting to the Langmuir isotherm model, an indication that monolayer adsorption occurred onto a homogeneous surface. The maximum adsorption capacity, qmax was 97.09 mg g-1, thus SSGC can be classified as good and comparable with other plant waste adsorbents.

Extraction of rare earth elements from low-grade Bauxite via precipitation reaction

NASA Astrophysics Data System (ADS)

Kusrini, E.; Nurani, Y.; Bahari, ZJ

2018-03-01

The aim of this research was to determine the optimum hydrometallurgical parameters to extract the rare earth elements (REE) from low-grade bauxite through acid leaching and precipitation reaction. REE or lanthanide recovery by a precipitation method with sodium sulphate and sodium phosphate as precipitation agents is reported where the effect of pH and recovery of REE are described. The metal composition of REE in low-grade bauxite after treatment were analyzed by ICP-OES. The total recovery values of REE elements at the first precipitation reaction using sodium sulphate as the precipitation agent at pH 3.5 showed ~68.2% of lanthanum, ~18.9% cerium, and ~7.8% yttrium. Lanthanum was the rare-earth element present at the highest concentration in the low-grade bauxite after the series treatments. An optimum pH of 3.5 for precipitation of rare-earth elements using sodium sulphate was demonstrated where this method is recommended for the extraction of REE elements from low-grade bauxite.

Purification and characterization of a fibrinolytic enzyme from tempeh bongkrek as an alternative of thrombolytic agents

NASA Astrophysics Data System (ADS)

Sasmita, I. R. A.; Sutrisno, A.; Zubaidah, E.; Wardani, A. K.

2018-03-01

Tempeh is one of Indonesia’s traditional foods that contain fibrinolytic enzymes. Tempeh bongkrek shows very strong activity among various tempeh. The fibrinolytic enzymes of bongkrek tempeh are obtained by steps of purification i.e, ammonium sulphate precipitation, ion exchange chromatography and gel filtration chromatography. The fibrinolytic enzymes has been successfully purified with a yield of 4.37%, specific activity of 3,361 U / mg and purification fold of 44.02. SDS PAGE analysis showed that the enzyme was purified in to single band with estimated molecular mass of 75.82 kDa. The purified enzyme has optimum pH of 7 and optimum temperature of 50°C and pH stability between pH 4 - 7 with temperature stability from 30°-50°C. The fibrinolytic activity is increased with addition of CaCl2 but inhibited with CuSO4, phenylmethylsulfonyl fluoride (PMSF), sodium dodecyl sulfate (SDS), and ethylenediaminetetraacetic acid (EDTA).

Removal of Heavy Metals from Solid Wastes Leachates Coagulation-Flocculation Process

NASA Astrophysics Data System (ADS)

Yousefi, Z.; Zazouli, M. A.

The main objectives of present research were to determine heavy metals (Ni, Cd, Cr, Zn and Cu) and COD concentration in raw leachate in Esfahan (Iran) composting plant and to examine the application of coagulation-flocculation process for the treatment of raw leachates. Jar-test experiments were employed in order to determine the optimum conditions (effective dosage and optimum pH) for the removal of COD and heavy metals. Alum (aluminum sulphate) and Ferric chloride were tested as conventional coagulants. Ten times had taken sampling from leachates as standard methods in the composting plant prior to composting process. The results showed that Leachate pH was 4.3-5.9 and the average was 4.98±0.62. The concentration of Leachate pollutants were more than effluent standard limits (Environment protection Agency). And also the results indicated, Cd and Zn with concentration 0.46±0.41 and 5.81±3.69 mg L-1, had minimum and maximum levels, respectively. The results of coagulation and flocculation tests showed that in optimum conditions, the removal efficiency of heavy metals and COD by using alum were 77-91 and 21%, respectively. While removal of heavy metals and COD by ferric chloride were 68-85.5% and 28%, respectively. Also the residues of heavy metals after treatment get to under of standard limits of Iran EPA. The results have indicated optimum pH of two coagulants for leachate treatment was 6.5 and 10 and also effective coagulant dosages were 1400 and 1000 mg L-1 for alum and ferric chloride, respectively. In view of economical, ferric chloride is cost benefit. The physico-chemical process may be used as a useful pretreatment step, especially for fresh leachates.

Study on gold concentrate leaching by iodine-iodide

NASA Astrophysics Data System (ADS)

Wang, Hai-xia; Sun, Chun-bao; Li, Shao-ying; Fu, Ping-feng; Song, Yu-guo; Li, Liang; Xie, Wen-qing

2013-04-01

Gold extraction by iodine-iodide solution is an effective and environment-friendly method. In this study, the method using iodine-iodide for gold leaching is proved feasible through thermodynamic calculation. At the same time, experiments on flotation gold concentrates were carried out and encouraging results were obtained. Through optimizing the technological conditions, the attained high gold leaching rate is more than 85%. The optimum process conditions at 25°C are shown as follows: the initial iodine concentration is 1.0%, the iodine-to-iodide mole ratio is 1:8, the solution pH value is 7, the liquid-to-solid mass ratio is 4:1, the leaching time is 4 h, the stirring intensity is 200 r/mim, and the hydrogen peroxide consumption is 1%.

Biodegradation of Decabromodiphenyl Ether (BDE-209) by Crude Enzyme Extract from Pseudomonas aeruginosa.

PubMed

Liu, Yu; Gong, Ai-Jun; Qiu, Li-Na; Li, Jing-Rui; Li, Fu-Kai

2015-09-18

The biodegradation effect and mechanism of decabromodiphenyl ether (BDE-209) by crude enzyme extract from Pseudomonas aeruginosa were investigated. The results demonstrated that crude enzyme extract exhibited obviously higher degradation efficiency and shorter biodegradation time than Pseudomonas aeruginosa itself. Under the optimum conditions of pH 9.0, 35 °C and protein content of 2000 mg/L, 92.77% of the initial BDE-209 (20 mg/L) was degraded after 5 h. A BDE-209 biodegradation pathway was proposed on the basis of the biodegradation products identified by GC-MS analysis. The biodegradation mechanism showed that crude enzyme extract degraded BDE-209 into lower brominated PBDEs and OH-PBDEs through debromination and hydroxylation of the aromatic rings.

Amylolysis of raw corn by Aspergillus niger for simultaneous ethanol fermentation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Han, I.Y.; Steinberg, M.P.

The novelty of this approach was hydrolysis of the raw starch in ground corn to fermentable sugars that are simultaneously fermented to ethanol by yeast in a nonsterile environment. Thus, the conventional cooking step can be eliminated for energy conservation. A koji of Aspergillus niger grown on whole corn for 3 days was the crude enzyme source. A ratio of 0.2 g dry koji/g total solids was found sufficient. Optimum pH was 4.2. Ethanol concentration was 7.7% (w/w) in the aqueous phase with 92% raw starch conversion. Agitation increased rate. Sacharification was the rate-limiting step. The initial ethanol concentration preventingmore » fermentation was estimated to be 8.3% by weight. (Refs. 96).« less

Biodegradation of Decabromodiphenyl Ether (BDE-209) by Crude Enzyme Extract from Pseudomonas aeruginosa

PubMed Central

Liu, Yu; Gong, Ai-Jun; Qiu, Li-Na; Li, Jing-Rui; Li, Fu-Kai

2015-01-01

The biodegradation effect and mechanism of decabromodiphenyl ether (BDE-209) by crude enzyme extract from Pseudomonas aeruginosa were investigated. The results demonstrated that crude enzyme extract exhibited obviously higher degradation efficiency and shorter biodegradation time than Pseudomonas aeruginosa itself. Under the optimum conditions of pH 9.0, 35 °C and protein content of 2000 mg/L, 92.77% of the initial BDE-209 (20 mg/L) was degraded after 5 h. A BDE-209 biodegradation pathway was proposed on the basis of the biodegradation products identified by GC-MS analysis. The biodegradation mechanism showed that crude enzyme extract degraded BDE-209 into lower brominated PBDEs and OH-PBDEs through debromination and hydroxylation of the aromatic rings. PMID:26393637

Production of Pectate Lyase by Penicillium viridicatum RFC3 in Solid-State and Submerged Fermentation

PubMed Central

Ferreira, Viviani; da Silva, Roberto; Silva, Dênis; Gomes, Eleni

2010-01-01

Pectate lyase (PL) was produced by the filamentous fungus Penicillium viridicatum RFC3 in solid-state cultures of a mixture of orange bagasse and wheat bran (1 : 1 w/w), or orange bagasse, wheat bran and sugarcane bagasse (1 : 1 : 0.5 w/w), and in a submerged liquid culture with orange bagasse and wheat bran (3%) as the carbon source. PL production was highest (1,500 U  mL−1 or 300 Ug−1 of substrate) in solid-state fermentation (SSF) on wheat bran and orange bagasse at 96 hours. PL production in submerged fermentation (SmF) was influenced by the initial pH of the medium. With the initial pH adjusted to 4.5, 5.0, and 5.5, the peak activity was observed after 72, 48, and 24 hours of fermentation, respectively, when the pH of the medium reached the value 5.0. PL from SSF and SmF were loaded on Sephadex-G75 columns and six activity peaks were obtained from crude enzyme from SSF and designated PL I, II, III, IV, V, and VI, while five peaks were obtained from crude enzyme from SmF and labeled PL  I′, II′, III′, IV′, and VII′. Crude enzyme and fraction III from each fermentative process were tested further. The optimum pH for crude PL from either process was 5.5, while that for PL III was 8.0. The maximum activity of enzymes from SSF was observed at 35°C, but crude enzyme was more thermotolerant than PL III, maintaining its maximum activity up to 45°C. Crude enzyme from SmF and PL III′ showed thermophilic profiles of activity, with maximum activity at 60 and 55°C, respectively. In the absence of substrate, the crude enzyme from SSF was stable over the pH range 3.0–10.0 and PL III was most stable in the pH range 4.0–7.0. Crude enzyme from SmF retained 70%–80% of its maximum activity in the acid-neutral pH range (4.0–7.0), but PIII showed high stability at alkaline pH (7.5–9.5). PL from SSF was more thermolabile than that from SmF. The latter maintained 60% of its initial activity after 1 h at 55°C. The differing behavior of the enzymes with respect to pH and temperature suggests that they are different isozymes. PMID:20689719

Cloning and high-level expression of β-xylosidase from Selenomonas ruminantium in Pichia pastoris by optimizing of pH, methanol concentration and temperature conditions.

PubMed

Dehnavi, Ehsan; Ranaei Siadat, Seyed Omid; Fathi Roudsari, Mehrnoosh; Khajeh, Khosro

2016-08-01

β-xylosidase and several other glycoside hydrolase family members, including xylanase, cooperate together to degrade hemicelluloses, a commonly found xylan polymer of plant-cell wall. β-d-xylosidase/α-l-arabinofuranosidase from the ruminal anaerobic bacterium Selenomonas ruminantium (SXA) has potential utility in industrial processes such as production of fuel ethanol and other bioproducts. The optimized synthetic SXA gene was overexpressed in methylotrophic Pichia pastoris under the control of alcohol oxidase I (AOX1) promoter and secreted into the medium. Recombinant protein showed an optimum pH 4.8 and optimum temperature 50 °C. Furthermore, optimization of growth and induction conditions in shake flask was carried out. Using the optimum expression condition (pH 6, temperature 20 °C and 1% methanol induction), protein production was increased by about three times in comparison to the control. The recombinant SXA we have expressed here showed higher turnover frequency using ρ-nitrophenyl β-xylopyranoside (PNPX) substrate, in contrast to most xylosidase experiments reported previously. This is the first report on the cloning and expression of a β-xylosidase gene from glycoside hydrolase (GH) family 43 in Pichia pastoris. Our results confirm that P. pastoris is an appropriate host for high level expression and production of SXA for industrial applications. Copyright © 2016. Published by Elsevier Inc.

Evaluating photo-degradation of COD and TOC in petroleum refinery wastewater by using TiO2/ZnO photo-catalyst.

PubMed

Aljuboury, Dheeaa Al Deen Atallah; Palaniandy, Puganeshwary; Abdul Aziz, Hamidi Bin; Feroz, Shaik; Abu Amr, Salem S

2016-09-01

The aim of this study is to investigate the performance of combined solar photo-catalyst of titanium oxide/zinc oxide (TiO 2 /ZnO) with aeration processes to treat petroleum wastewater. Central composite design with response surface methodology was used to evaluate the relationships between operating variables for TiO 2 dosage, ZnO dosage, air flow, pH, and reaction time to identify the optimum operating conditions. Quadratic models for chemical oxygen demand (COD) and total organic carbon (TOC) removals prove to be significant with low probabilities (<0.0001). The obtained optimum conditions included a reaction time of 170 min, TiO 2 dosage (0.5 g/L), ZnO dosage (0.54 g/L), air flow (4.3 L/min), and pH 6.8 COD and TOC removal rates of 99% and 74%, respectively. The TOC and COD removal rates correspond well with the predicted models. The maximum removal rate for TOC and COD was 99.3% and 76%, respectively at optimum operational conditions of TiO 2 dosage (0.5 g/L), ZnO dosage (0.54 g/L), air flow (4.3 L/min), reaction time (170 min) and pH (6.8). The new treatment process achieved higher degradation efficiencies for TOC and COD and reduced the treatment time comparing with other related processes.

Heterotrophic Nature of the Cell-Free Protein-Synthesizing System from the Strict Chemolithotroph, Thiobacillus thiooxidans

PubMed Central

Amemiya, K.; Umbreit, W. W.

1974-01-01

A cell-free protein-synthesizing system prepared from the strict chemolithotroph, Thiobacillus thiooxidans, was similar to that of heterotrophs. The poly-U directed system had a temperature optimum of 37 C, but in the presence of spermidine (3 mM) the optimum shifted to 45 C. Although growth of the chemolithotroph occurs only in acid conditions, the pH optimum for the cell-free system was pH 7.2. The endogenous-directed activity in the presence or absence of spermidine was maximal at pH 7.8. Spermidine had a stimulatory effect; however, this effect was dependent on the magnesium and tris(hydroxymethyl)aminomethane (Tris) concentrations. At low Tris concentrations (10 mM), spermidine (3 to 5 mM) could completely replace magnesium. When the Tris concentration was increased (50 mM), spermidine could not replace magnesium. Supernatant and ribosomal fractions from T. thiooxidans were exchanged with those of Bacillus thuringiensis and Escherichia coli, and the ribosomal fraction from the chemolithotroph gave good to moderate stimulation when exchanged with the supernatant from the heterotrophs. On the other hand, the supernatant from T. thiooxidans gave good stimulation when mixed with ribosomes from B. thuringiensis but poor activity with ribosomes from E. coli. Both supernatant and ribosomal fractions prepared from stationary phase extracts of T. thiooxidans were inactive in the cell-free system. PMID:4590488

Experimental Study on Treatment of Dyeing Wastewater by Activated Carbon Adsorption, Coagulation and Fenton Oxidation

NASA Astrophysics Data System (ADS)

Xiaoxu, SUN; Jin, XU; Xingyu, LI

2017-12-01

In this paper dyeing waste water was simulated by reactive brilliant blue XBR, activated carbon adsorption process, coagulation process and chemical oxidation process were used to treat dyeing waste water. In activated carbon adsorption process and coagulation process, the water absorbance values were measured. The CODcr value of water was determined in Fenton chemical oxidation process. Then, the decolorization rate and COD removal rate were calculated respectively. The results showed that the optimum conditions of activated carbon adsorption process were as follows: pH=2, the dosage of activated carbon was 1.2g/L, the adsorption reaction time was 60 min, and the average decolorization rate of the three parallel experiments was 85.30%. The optimum conditions of coagulation experiment were as follows: pH=8~9, PAC dosage was 70mg/L, stirring time was 20min, standing time was 45min, the average decolorization rate of the three parallel experiments was 74.48%. The optimum conditions for Fenton oxidation were Fe2+ 0.05g/L, H2O2 (30%) 14mL/L, pH=3, reaction time 40min. The average CODcr removal rate was 69.35% in three parallel experiments. It can be seen that in the three methods the activated carbon adsorption treatment of dyeing wastewater was the best one.

Glucose biosensor based on the immobilization of glucose oxidase on electrochemically synthesized polypyrrole-poly(vinyl sulphonate) composite film by cross-linking with glutaraldehyde.

PubMed

Colak, Ozlem; Yaşar, Ahmet; Cete, Servet; Arslan, Fatma

2012-10-01

In this study, a novel amperometric glucose biosensor was developed by immobilizing glucose oxidase (GOX) by cross-linking via glutaraldehyde on electrochemically polymerized polypyrrole-poly(vinyl sulphonate) (PPy-PVS) films on the surface of a platinum (Pt) electrode. Electropolymerization of pyrrole and poly(vinyl sulphonate) on the Pt surface was carried out with an electrochemical cell containing pyrrole and poly(vinyl sulphonate) by cyclic voltammetry between -1.0 and + 2.0 V (vs.Ag/AgCl) at a scan rate of 50 mV/s upon the Pt electrode. The amperometric determination was based on the electrochemical detection of H(2)O(2) generated in enzymatic reaction of glucose. Determination of glucose was carried out by the oxidation of enzymatically produced H(2)O(2) at 0.4 V vs. Ag/AgCl. The effects of pH and temperature were investigated and optimum parameters were found to be 7.5 and 65°C, respectively. The effect of working potential was investigated and optimum potential was determined to be 0.4 V. The operational stability of the enzyme electrode was also studied. The response of the PPy/PVS-GOX glucose biosensor exhibited good reproducibility with a relative standard deviation (RSD) of 2.48%. The glucose biosensor retained 63% of initial activity after 93 days when stored in 0.1 M phosphate buffer solution of pH 7.5 at 4°C. With the low operating potential, the biosensor demonstrated little interference from the possible interferants.

Sonophotocatalytic degradation of trypan blue and vesuvine dyes in the presence of blue light active photocatalyst of Ag3PO4/Bi2S3-HKUST-1-MOF: Central composite optimization and synergistic effect study.

PubMed

Mosleh, S; Rahimi, M R; Ghaedi, M; Dashtian, K

2016-09-01

An efficient simultaneous sonophotocatalytic degradation of trypan blue (TB) and vesuvine (VS) using Ag3PO4/Bi2S3-HKUST-1-MOF as a novel visible light active photocatalyst was carried out successfully in a continuous flow-loop reactor equipped to blue LED light. Ag3PO4/Bi2S3-HKUST-1-MOF with activation ability under blue light illumination was synthesized and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), photoluminescence (PL) and diffuse reflectance spectra (DRS). The effect of operational parameters such as the initial TB and VS concentration (5-45mg/L), flow rate (30-110mL/min), irradiation and sonication time (10-30min), pH (3-11) and photocatalyst dosage (0.15-0.35g/L) has been investigated and optimized using central composite design (CCD) combined with desirability function (DF). Maximum sonophotodegradation percentage (98.44% and 99.36% for TB and VS, respectively) was found at optimum condition set as: 25mg/L of each dye, 70mL/min of solution flow rate, 25min of irradiation and sonication time, pH 6 and 0.25g/L of photocatalyst dosage. At optimum conditions, synergistic index value was obtained 2.53 that indicated the hybrid systems including ultrasound irradiation and photocatalysis have higher efficiency compared with sum of the individual processes. Copyright © 2016. Published by Elsevier B.V.

Biodegradation of waste greases and biochemical properties of a novel lipase from Pseudomonas synxantha PS1.

PubMed

Cai, Xianghai; Chen, Siqi; Yang, Hong; Wang, Wei; Lin, Lin; Shen, Yaling; Wei, Wei; Wei, Dong-Zhi

2016-07-01

A lipase-producing bacterial strain was isolated from oil-well-produced water in Shengli oilfield (Shandong province, China) and was identified as Pseudomonas synxantha by 16S rDNA sequence analysis (named Pseudomonas synxantha PS1). Strain PS1 showed a maximum lipase activity of 10.8 U/mL after culturing for 48 h at 30 °C, with lactose (4 g/L) as carbon source, tryptone (8 g/L) as nitrogen source, olive oil (0.5%, v/v) as inductor, and the initial pH 8.0. Meanwhile, the lipase gene from P. synxantha PS1 was cloned and expressed in Escherichia coli BL21 with the vector pET28a. The novel gene (lipPS1) has an open reading frame of 1425 bp and encodes a 474 aa lipase (LipPS1) sharing the most identity (87%) with the lipase in Pseudomonas fluorescens. LipPS1 preferably acted on substrates with a long chain (C10-C18) of fatty acids. The optimum pH and temperature of the recombinant enzyme were 8.0 and 40 °C, respectively, towards the optimum substrate p-nitrophenyl palmitate. The LipPS1 showed remarkable stability under alkaline conditions and was stable at pH 7.0-10.0 (retaining more than 60% activity). From the organic solvents tests, the lipase was activated by 15% (v/v) methanol (112%), 15% ethanol (127%), and 15% n-butyl alcohol (116%). LipPS1 presented strong biodegradability of waste grease; 93% of waste grease was hydrolyzed into fatty acid after 12 h at 30 °C. This is the first report of the lipase activity and lipase gene obtained from P. synxantha (including wild strain and recombinant strain) and of the recombinant LipPS1 with the detailed enzymatic properties. Also a preliminary study of the biodegradability of waste greases shows the potential value in industry applications.

Sporulation boundaries and spore formation kinetics of Bacillus spp. as a function of temperature, pH and a(w).

PubMed

Baril, Eugénie; Coroller, Louis; Couvert, Olivier; El Jabri, Mohammed; Leguerinel, Ivan; Postollec, Florence; Boulais, Christophe; Carlin, Frédéric; Mafart, Pierre

2012-10-01

Sporulation niches in the food chain are considered as a source of hazard and are not clearly identified. Determining the sporulation environmental boundaries could contribute to identify potential sporulation niches. Spore formation was determined in a Sporulation Mineral Buffer. The effect of incubation temperature, pH and water activity on time to one spore per mL, maximum sporulation rate and final spore concentration was investigated for a Bacillus weihenstephanensis and a Bacillus licheniformis strain. Sporulation boundaries of B. weihenstephanensis and of B. licheniformis were similar to, or included within, the range of temperatures, pH and water activities supporting growth. For instance, sporulation boundaries of B. weihenstephanensis were evaluated at 5°C, 35°C, pH 5.2 and a(w) 0.960 while growth boundaries were observed at 5°C, 37°C, pH 4.9 and a(w) 0.950. Optimum spore formation was determined at 30°C pH 7.2 for B. weihenstephanensis and at 45°C pH 7.2 for B. licheniformis. Lower temperatures and pH delayed the sporulation process. For instance, the time to one spore per mL was tenfold longer when sporulation occurred at 10°C and 20°C, for each strain respectively, than at optimum sporulation temperature. The relative effect of temperature and pH on sporulation rates and on growth rates is similar. This work suggests that the influence of environmental factors on the quantitative changes in sporulation boundaries and rates was similar to their influence on changes in growth rate. Copyright © 2012 Elsevier Ltd. All rights reserved.

Acid-base characterization of 5-hydroxypyrazine-2-carboxylic acid and the role of ionic equilibria in the optimization of some process conditions for its biocatalytic production.

PubMed

Sak-Bosnar, M; Kovar, K

2005-10-01

This paper describes the use of potentiometric titration to determine the relevant acid-base properties of 5-hydroxypyrazine-2-carboxylic acid (5OH-PYCA), an important intermediate in the production of tuberculostatics. The data obtained were used for calculation of the dissociation constants of 5OH-PYCA. It was found that 5OH-PYCA dissociates in two steps, with the corresponding dissociation constants pK (a1)=3.42 and pK (a2)=7.96, designating 5OH-PYCA as a medium weak acid (1st step). The distribution diagram of dissociated species and the buffer-strength diagram of 5OH-PYCA provide useful information about its behaviour at different pH. The ionic equilibria data obtained can be used for selection of the optimum pH for biotransformation of pyrazine-2-carboxylic acid (PYCA) and for prediction of pH changes during the biotransformation. These data can also be used for selection of the optimum pH for precipitating 5OH-PYCA in downstream processing. All computations have been optimized by mathematical modelling using Solver.

Anoxybacter fermentans gen. nov., sp. nov., a piezophilic, thermophilic, anaerobic, fermentative bacterium isolated from a deep-sea hydrothermal vent.

PubMed

Zeng, Xiang; Zhang, Zhao; Li, Xi; Zhang, Xiaobo; Cao, Junwei; Jebbar, Mohamed; Alain, Karine; Shao, Zongze

2015-02-01

A novel piezophilic, thermophilic, anaerobic, fermentative bacterial strain, designated strain DY22613(T), was isolated from a deep-sea hydrothermal sulfide deposit at the East Pacific Rise (GPS position: 102.6° W 3.1° S). Cells of strain DY22613(T) were long, motile rods (10 to 20 µm in length and 0.5 µm in width) with peritrichous flagella and were Gram-stain-negative. Growth was recorded at 44-72 °C (optimum 60-62 °C) and at hydrostatic pressures of 0.1-55 MPa (optimum 20 MPa). The pH range for growth was from pH 5.0 to 9.0 with an optimum at pH 7.0. Growth was observed in the presence of 1 to 8 % (w/v) sea salts and 0.65 to 5.2 % (w/v) NaCl, with optimum salt concentrations at 3.5 % for sea salts and at 2.3 % for NaCl. Under optimal growth conditions, the shortest generation time observed was 27 min (60 °C, 20 MPa). Strain DY22613(T) was heterotrophic, able to utilize complex organic compounds, amino acids, sugars and organic acids including peptone, tryptone, beef extract, yeast extract, alanine, glutamine, methionine, phenylalanine, serine, threonine, fructose, fucose, galactose, gentiobiose, glucose, mannose, melibiose, palatinose, rhamnose, turanose, pyruvate, lactic acid, methyl ester, erythritol, galacturonic acid and glucosaminic acid. Strain DY22613(T) was able to reduce Fe(III) compounds, including Fe(III) oxyhydroxide (pH 7.0), amorphous iron(III) oxide (pH 9.0), goethite (α-FeOOH, pH 12.0), Fe(III) citrate and elementary sulfur. Products of fermentation were butyrate, acetate and hydrogen. Main cellular fatty acids were iso-C15 : 0, iso-C14 : 0 3-OH and C14 : 0. The genomic DNA G+C content of strain DY22613(T) was 36.7 mol%. Based on 16S rRNA gene sequence analysis, the strain forms a novel lineage within the class Clostridia and clusters with the order Haloanaerobiales (86.92 % 16S rRNA gene sequence similarity). The phylogenetic data suggest that the lineage represents at least a novel genus and species, for which the name Anoxybacter fermentans gen. nov., sp. nov. is proposed. The type strain is DY22613(T) ( = JCM 19466(T) = DSM 28033(T) = MCCC 1A06456(T)). © 2015 IUMS.

Kinetic characterization, optimum conditions for catalysis and substrate preference of secretory phospholipase A2 from Glycine max in model membrane systems.

PubMed

Mariani, María Elisa; Madoery, Ricardo Román; Fidelio, Gerardo Daniel

2015-01-01

Two secretory phospholipase A2 (sPLA2s) from Glycine max, GmsPLA2-IXA-1 and GmsPLA2-XIB-2, have been purified as recombinant proteins and the activity was evaluated in order to obtain the optimum conditions for catalysis using mixed micelles and lipid monolayers as substrate. Both sPLA2s showed a maximum enzyme activity at pH 7 and a requirement of Ca(2+) in the micromolar range. These parameters were similar to those found for animal sPLA2s but a surprising optimum temperature for catalysis at 60 °C was observed. The effect of negative interfacial charges on the hydrolysis of organized substrates was evaluated through initial rate measurements using short chain phospholipids with different head groups. The enzymes showed subtle differences in the specificity for phospholipids with different head groups (DLPC, DLPG, DLPE, DLPA) in presence or absence of NaCl. Both recombinant enzymes showed lower activity toward anionic phospholipids and a preference for the zwitterionic ones. The values of the apparent kinetic parameters (Vmax and KM) demonstrated that these enzymes have more affinity for phosphatidylcholine compared with phosphatidylglycerol, in contrast with the results observed for pancreatic sPLA2. A hopping mode of catalysis was proposed for the action of these sPLA2 on mixed phospholipid/triton micelles. On the other hand, Langmuir-monolayers assays indicated an optimum lateral surface pressure for activity in between 13 and 16 mN/m for both recombinant enzymes. Copyright © 2014 Elsevier B.V. and Société française de biochimie et biologie Moléculaire (SFBBM). All rights reserved.

Kinetic and equilibrium isotherm studies for the adsorptive removal of Brilliant Green dye from aqueous solution by rice husk ash.

PubMed

Mane, Venkat S; Deo Mall, Indra; Chandra Srivastava, Vimal

2007-09-01

The present study deals with the adsorption of Brilliant Green (BG) on rice husk ash (RHA). RHA is a solid waste obtained from the particulate collection equipment attached to the flue gas lines of rice husk fired boilers. Batch studies were performed to evaluate the influences of various experimental parameters like initial pH (pH0), contact time, adsorbent dose and initial concentration (C0) on the removal of BG. Optimum conditions for BG removal were found to be pH0 approximately 3.0, adsorbent dose approximately 6 g L(-1) of solution and equilibrium time approximately 5 h for the C0 range of 50-300 mg L(-1). Adsorption of BG followed pseudo-second-order kinetics. Intra-particle diffusion does not seem to control the BG removal process. Equilibrium isotherms for the adsorption of BG on RHA were analyzed by Freundlich, Langmuir, Redlich-Peterson (R-P), Dubnin-Radushkevich (D-R), and Temkin isotherm models using a non-linear regression technique. Langmuir and R-P isotherms were found to best represent the data for BG adsorption onto RHA. Adsorption of BG on RHA is favourably influenced by an increase in the temperature of the operation. Values of the change in entropy (DeltaS0) and heat of adsorption (DeltaH0) for BG adsorption on RHA were positive. The high negative value of change in Gibbs free energy (DeltaG0) indicates the feasible and spontaneous adsorption of BG on RHA.

Degradation of 4-chloro 2-aminophenol using combined strategies based on ultrasound, photolysis and ozone.

PubMed

Barik, Arati J; Gogate, Parag R

2016-01-01

The present work investigates the degradation of 4-chloro 2-aminophenol (4C2AP), a highly toxic organic compound, using ultrasonic reactors and combination of ultrasound with photolysis and ozonation for the first time. Two types of ultrasonic reactors viz. ultrasonic horn and ultrasonic bath operating at frequency of 20 kHz and 36 kHz respectively have been used in the work. The effect of initial pH, temperature and power dissipation of the ultrasonic horn on the degradation rate has been investigated. The established optimum parameters of initial pH as 6 (natural pH of the aqueous solution) and temperature as 30 ± 2°C were then used in the degradation studies using the combined approaches. Kinetic study revealed that degradation of 4C2AP followed first order kinetics for all the treatment approaches investigated in the present work. It has been established that US+UV+O3 combined process was the most promising method giving maximum degradation of 4C2AP in both ultrasonic horn (complete removal) and bath (89.9%) with synergistic index as 1.98 and 1.29 respectively. The cavitational yield of ultrasonic bath was found to be eighteen times higher as compared to ultrasonic horn implying that configurations with higher overall areas of transducers would be better selection for large scale treatment. Overall, the work has clearly demonstrated that combined approaches could synergistically remove the toxic pollutant (4C2AP). Copyright © 2015 Elsevier B.V. All rights reserved.

Partial biochemical characterization of crude extract extracellular chitinase enzyme from Bacillus subtilis B 298

NASA Astrophysics Data System (ADS)

Lestari, P.; Prihatiningsih, N.; Djatmiko, H. A.

2017-02-01

Extraction and characterization of extracellular chitinase from Bacillus subtilis B 298 have been done. Growth curve determination of B. subtilis B 298, production curve determination of crude extract chitinase from B. subtilis B 298, and partial biochemical characterization of crude extract chitinase have been achieved in this study. Optimum growth of B. subtilis B 298 was achieved at logarithmic phase within 9 hours incubation time, so it was used as inoculum for enzyme production. According to production curve of the enzyme, it was known that incubation time which gave the highest chitinase activity of 15 hours with activity of 6.937 U/mL respectively. Effect of various temperatures on chitinase activity showed that optimum activity was achieved at 40°C with an activity of 5.764 U/mL respectively. Meanwhile, the optimum pH for chitinase activity was achieved at pH of 5.0 with an activity of 6.813 U/mL respectively. This enzyme was then classified as metalloenzyme due to the decline of the activity by EDTA addition. All divalent cations tested acted as inhibitors.

Purification and biochemical characterization of glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and glutathione reductase from rat lung and inhibition effects of some antibiotics.

PubMed

Adem, Sevki; Ciftci, Mehmet

2016-12-01

G6PD, 6PGD and GR have been purified separately in the single step from rat lung using 2', 5'-ADP Sepharose 4B affinity chromatography. The purified enzymes showed a single band on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The molecular weights of the enzymes were estimated to be 134 kDa for G6PD, 107 kDa for 6PGD and 121 kDa for GR by Sephadex G-150 gel filtration chromatography, and the subunit molecular weights was respectively found to be 66, 52 and 63 kDa by SDS-PAGE. Optimum pH, stable pH, optimum ionic strength, optimum temperature, KM and Vmax values for substrates were determined. Product inhibition studies were also performed. The enzymes were inhibited by levofloxacin, furosemide, ceftazidime, cefuroxime and gentamicin as in vitro with IC50 values in the range of 0.07-30.13 mM. In vivo studies demonstrated that lung GR was inhibited by furosemide and lung 6PGD was inhibited by levofloxacin.

Distribution and characteristics of endogenous digestive enzymes in the red-eared slider turtle, Trachemys scripta elegans.

PubMed

Sun, Jian-Yi; Du, Jie; Qian, Li-Chun; Jing, Ming-Yan; Weng, Xiao-Yan

2007-08-01

Distribution and properties of the main digestive enzymes including protease and amylase, from stomach, pancreas and the anterior, middle and posterior intestine of the adult red-eared slider turtle Trachemys scripta elegans were studied at various pHs and temperatures. The optimum temperature and pH for protease in stomach, pancreas and the anterior, middle and posterior intestine were 40 degrees C, 2.5; 50 degrees C, 8.0; 50 degrees C, 7.0; 50 degrees C, 8.0; and 50 degrees C, 8.5; respectively. The optimum temperature and pH for amylase in stomach, pancreas and anterior, middle and posterior intestine were 40 degrees C, 8.0; 30 degrees C, 7.5; 40 degrees C, 7.0; 50 degrees C, 8.0; and 50 degrees C, 8.0; respectively. Under the optimum conditions, the order of protease activity from high to low was of pancreas, stomach and the anterior, posterior and middle intestine; the activity of amylase in descending order was of anterior intestine, pancreas, posterior intestine, middle intestine and stomach.

Rheology of Dead Sea shampoo containing the antidandruff climbazole.

PubMed

Abu-Jdayil, B; Mohameed, H A

2004-12-01

In this study, the effect of the antidandruff climbazole on the rheology of hair shampoo containing Dead Sea (DS) salt was investigated. The presence of either DS salt or the climbazole led to increase in the shampoo viscosity. An optimum concentration was found where the viscosity of shampoo was maximum. In the absence of DS salt, the viscosity of hair shampoo increased with increasing the climbazole concentration to reach a maximum value at 1.0 wt%. Further addition of climbazole decreased the viscosity of shampoo. Adjusting the pH of the shampoo at 5.5 and 5.0 shifted the optimum climbazole concentration (corresponds to maximum viscosity) to 0.8 wt% and led to increase in the viscosity of shampoo. On the other hand, the addition of climbazole to the shampoo containing DS salt resulted in a decrease in shampoo viscosity. This decrease of shampoo viscosity became more pronounced with increasing the climbazole and/or DS salt concentrations. By controlling the pH of shampoo, an optimum formula of shampoo comprising both climbazole and DS salt and having maximum viscosity was obtained.

Removal Efficiency of the Heavy Metals Zn(II), Pb(II) and Cd(II) by Saprolegnia delica and Trichoderma viride at Different pH Values and Temperature Degrees

PubMed Central

Hashem, Mohamed

2007-01-01

The removal efficiency of the heavy metals Zn, Pb and Cd by the zoosporic fungal species Saprolegnia delica and the terrestrial fungus Trichoderma viride, isolated from polluted water drainages in the Delta of Nile in Egypt, as affected by various ranges of pH values and different temperature degrees,was extensively investigated. The maximum removal efficiency of S. delica for Zn(II) and Cd(II) was obtained at pH 8 and for Pb(II) was at pH 6 whilst the removal efficiency of T. viride was found to be optimum at pH 6 for the three applied heavy metals. Regardless the median lethal doses of the three heavy metals, Zn recorded the highest bioaccumulation potency by S. delica at all pH values except at pH 4, followed by Pb whereas Cd showed the lowest removal potency by the fungal species and vice versa in case of T. viride. The optimum biomass dry weight production by S. delica was found when the fungus was grown in the medium treated with the heavy metal Pb at pH 6, followed by Zn at pH 8 and Cd at pH 8. The optimum biomass dry weight yield by T. viride amended with Zn,Pb and Cd was obtained at pH 6 for the three heavy metals with the maximum value at Zn. The highest yield of biomass dry weight was found when T. viride treated with Cd at all different pH values followed by Pb whilst Zn output was the lowest and this result was reversed in case of S. delica. The maximum removal efficiency and the biomass dry weight production for the three tested heavy metals was obtained at the incubation temperature 20℃ in case of S. delica while it was 25℃ for T. viride. Incubation of T. viride at higher temperatures (30℃ and 35℃) enhanced the removal efficiency of Pb and Cd than low temperatures (15℃ and 20℃) and vice versa in case of Zn removal. At all tested incubation temperatures, the maximum yield of biomass dry weight was attained at Zn treatment by the two tested fungal species. The bioaccumulation potency of S. delica for Zn was higher than that for Pb at all temperature degrees of incubation and Cd bioaccumulation was the lowest whereas T. viride showed the highest removal efficiency for Pb followed by Cd and Zn was the minor of the heavy metals. PMID:24015084

Removal Efficiency of Electrocoagulation Treatment Using Aluminium Electrode for Stabilized Leachate

NASA Astrophysics Data System (ADS)

Mohamad Zailani, L. W.; Amdan, N. S. Mohd; Zin, N. S. M.

2018-04-01

This research was conducted to investigate the performance of aluminium electrode in electrocoagulation process removing chemical oxygen demand (COD), ammonia, turbidity, colour and suspended solid (SS) from Simpang Renggam landfill leachate. Effects of current density, electrolysis duration and pH were observed in this study. From the data obtained, optimum condition at current density was recorded at 200 A/m2with the electrolysis duration of 20-minutes and optimum pH value at 4. The removal recorded at this condition for COD, ammonia, colour, turbidity and suspended solid were 60%, 37%, 94%, 88% and 89% respectively. Electrocoagulation treatment give a better result and can be applied for leachate treatment in future. Thus, electrocoagulation treatment has the potential to be used in treatment of leachate.

Characterization of cellulose acetate micropore membrane immobilized acylase I.

PubMed

Guo, Yong-Sheng; Wang, Jie; Song, Xi-Jin

2004-12-01

This paper describes an innovative method for the immobilization of acylase I, which was entrapped into the CA-CTA micropore membrane. The most suitable casting solutions proportion for immobilizing the enzyme was obtained through orthogonal experiment. Properties of the enzyme membrane were investigated and compared with those of free enzyme and blank membrane. The thermal stability and pH stability of the enzyme inside the membrane were changed by immobilization. The optimum pH was found to be 6.0, which changes 1.0 unit compared with that of free acylase I. The optimum temperature was found to be about 90 degrees C, which is higher than that of free acylase I (60 degrees C). Experimental results showed that immobilization had effects on the kinetic parameters of acylase I.

Optimization of composite coagulant made from polyferric chloride and tapioca starch in landfill leachate treatment

NASA Astrophysics Data System (ADS)

Shaylinda, M. Z. N.; Hamidi, A. A.; Mohd, N. A.; Ariffin, A.; Irvan, D.; Hazreek, Z. A. M.; Nizam, Z. M.

2018-04-01

In this research, the performance of polyferric chloride and tapioca flour as composite coagulants for partially stabilized leachate was investigated. Response surface methodology (RSM) was used to optimize the coagulation and flocculation process of partially stabilized leachate. Central composite design a standard design tool in RSM was applied to evaluate the interactions and effects of dose and pH. Dose 0.2 g/L Fe and pH 4.71 were the optimum value suggested by RSM. Experimental test based on the optimum condition, resulted in 95.9%, 94.6% and 50.4% of SS, color and COD removals, respectively. The percentage difference recorded between experimental and model responses was <5%. Therefore, it can be concluded that RSM was an appropriate optimization tool for coagulation and flocculation process.

Effect of immobilized biosorbents on the heavy metals (Cu2+) biosorption with variations of temperature and initial concentration of waste

NASA Astrophysics Data System (ADS)

Siwi, W. P.; Rinanti, A.; Silalahi, M. D. S.; Hadisoebroto, R.; Fachrul, M. F.

2018-01-01

The aims of research is to studying the efficiency of copper removal by combining immobilized microalgae with optimizations of temperature and initial Copper concentration. The research was conducted in batch culture with temperature variations of 25°C, 30°C, and 35°C, as well as initial Cu2+ concentrations (mg/l) of 3, 5, 10, 15 and 20 using monoculture of S. cerevisiae, Chlorella sp., and mixed culture of them both as immobilized biosorbents. The optimum adsorption of 83.4% obtained in temperature of 30°C with an initial waste concentration of 17.62 mg/l, initial biomass concentration of 200 mg, pH of 4, and 120 minutes detention time by the immobilized mixed culture biosorbent. The cell morphology examined using Scanning Electron Microscope (SEM) has proved that the biosorbent surface was damaged after being in contact with copper (waste), implying that heavy metals (molecules) attach to different functional cell surfaces and change the biosorbent surface. The adsorption process of this research follows Langmuir Isotherm with the R2 value close to 1. The immobilized mixed culture biosorbent is capable of optimally removing copper at temperature of 30°C and initial Cu2+ concentration of 17.62 mg/l.

Mesoporous Nb2O5/SiO2 material obtained by sol-gel method and applied as adsorbent of crystal violet dye.

PubMed

Umpierres, Cibele S; Prola, Lizie D T; Adebayo, Matthew A; Lima, Eder C; Dos Reis, Glaydson S; Kunzler, Diego D F; Dotto, G L; Arenas, Leliz T; Benvenutti, Edilson V

2017-03-01

In this work, SiO 2 /Nb 2 O 5 (SiNb) material was prepared using sol-gel method and employed as adsorbent for removal of crystal violet dye (CV). The material was characterized using nitrogen adsorption-desorption isotherms, FTIR spectroscopy, pH pzc , and SEM-EDS. The analysis of N 2 isotherms revealed the presence of micro- and mesopores in the SiNb sample with specific surface area as high as 747 m 2  g -1 . For the CV adsorption process, variations of several parameters such as of pH, temperature, contact time, and concentration of dye of the process were evaluated. The optimum initial pH of the CV dye solution was 7.0. The adsorption kinetic and equilibrium data for CV adsorption were suitably represented by the general-order and Liu models, respectively. The maximum adsorption capacity of the CV dye by SiNb was achieved at 303 K, which attained 116 mg g -1 at this temperaure. Dye effluents were simulated and used to check the applicability of the SiNb material for treatment of effluents - the material showed very good efficiency for decolorization of dye effluents.

Evaluation of Sorption Mechanism of Pb (II) and Ni (II) onto Pea (Pisum sativum) Peels.

PubMed

Haq, Atta Ul; Saeed, Muhammad; Anjum, Salma; Bokhari, Tanveer Hussain; Usman, Muhammad; Tubbsum, Saiqa

2017-07-01

The present study was carried out to know the sorption mechanism of Pb (II) and Ni (II) in aqueous solution using pea peels under the influence of sorbent dose, pH, temperature, initial metal ion concentration and contact time. SEM and FTIR were used for characterization of pea peels. The study showed that solution pH affects sorption process and the optimum pH for Pb (II) was 6.0 while for that of Ni (II) was 7.0. Pseudo-second order kinetic model was found to be the most suitable one to explain the kinetic data not only due to high value of R 2 (>0.99) but also due to the closeness of the experimental sorption capacity values to that of calculated sorption capacity values of pseudo second order kinetic model. It can be seen from the results that Freundlich isotherm explains well the equilibrium data (R 2 >0.99). Sorption capacity of pea peels was 140.84 and 32.36 for Pb (II) and Ni (II) mg g -1 respectively. The positive value of ΔH° and negative values of ΔG° suggest that sorption of Pb (II) and Ni (II) onto pea peels is an endothermic and spontaneous process respectively.

Decontamination of industrial cyanide-containing water in a solar CPC pilot plant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duran, A.; Monteagudo, J.M.; San Martin, I.

2010-07-15

The aim of this work was to improve the quality of wastewater effluent coming from an Integrated Gasification Combined-Cycle (IGCC) power station to meet with future environmental legislation. This study examined a homogeneous photocatalytic oxidation process using concentrated solar UV energy (UV/Fe(II)/H{sub 2}O{sub 2}) in a Solar Compound Parabolic Collector (CPC) pilot plant. The efficiency of the process was evaluated by analysis of the oxidation of cyanides and Total Organic Carbon (TOC). A factorial experimental design allowed the determination of the influences of operating variables (initial concentration of H{sub 2}O{sub 2}, oxalic acid and Fe(II) and pH) on the degradationmore » kinetics. Temperature and UV-A solar power were also included in the Neural Network fittings. The pH was maintained at a value >9.5 during cyanide oxidation to avoid the formation of gaseous HCN and later lowered to enhance mineralization. Under the optimum conditions ([H{sub 2}O{sub 2}] = 2000 ppm, [Fe(II)] = 8 ppm, pH = 3.3 after cyanide oxidation, and [(COOH){sub 2}] = 60 ppm), it was possible to degrade 100% of the cyanides and up to 92% of Total Organic Carbon. (author)« less

New insights into the pH-dependent interfacial adsorption of dog gastric lipase using the monolayer technique.

PubMed

Bénarouche, Anaïs; Point, Vanessa; Parsiegla, Goetz; Carrière, Frédéric; Cavalier, Jean-François

2013-11-01

The access to kinetic parameters of lipolytic enzyme adsorption onto lipids is essential for a better understanding of interfacial enzymology and lipase-lipid interactions. The interfacial adsorption of dog gastric lipase (DGL) was monitored as a function of pH and surface pressure (Π), independently from the catalytic activity, using non-hydrolysable 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) monomolecular films. The acid-stable DGL, which initiates fat digestion in the stomach, was then selected because its adsorption kinetics onto hydrophobic solid surfaces were already studied. This gastric lipase was therefore used as a model enzyme to validate both experimental and theoretical approaches. Results show that the adsorption process of DGL at the lipid/water interface depends on a pH-dependent adsorption equilibrium coefficient which is optimum at pH 5.0 (K(Ads) = 1.7 ± 0.05 × 10(8)M(-1)). KAds values further allowed an indirect estimation of the molar fraction (ΦE*(%), mol%) as well as the molecular area (AE*) of DGL adsorbed onto DLPC monolayer. Based on these data, a model for DGL adsorption onto DLPC monolayer at pH 5.0 is proposed for a surface pressure range of 15-25 mNm(-1). Copyright © 2013 Elsevier B.V. All rights reserved.

Preparation of photocatalytic ZnO nanoparticles and application in photochemical degradation of betamethasone sodium phosphate using taguchi approach

NASA Astrophysics Data System (ADS)

Giahi, M.; Farajpour, G.; Taghavi, H.; Shokri, S.

2014-07-01

In this study, ZnO nanoparticles were prepared by a sol-gel method for the first time. Taguchi method was used to identify the several factors that may affect degradation percentage of betamethasone sodium phosphate in wastewater in UV/K2S2O8/nano-ZnO system. Our experimental design consisted of testing five factors, i.e., dosage of K2S2O8, concentration of betamethasone sodium phosphate, amount of ZnO, irradiation time and initial pH. With four levels of each factor tested. It was found that, optimum parameters are irradiation time, 180 min; pH 9.0; betamethasone sodium phosphate, 30 mg/L; amount of ZnO, 13 mg; K2S2O8, 1 mM. The percentage contribution of each factor was determined by the analysis of variance (ANOVA). The results showed that irradiation time; pH; amount of ZnO; drug concentration and dosage of K2S2O8 contributed by 46.73, 28.56, 11.56, 6.70, and 6.44%, respectively. Finally, the kinetics process was studied and the photodegradation rate of betamethasone sodium phosphate was found to obey pseudo-first-order kinetics equation represented by the Langmuir-Hinshelwood model.

Whole cell immobilization of refractory glucose isomerase using tris(hydroxymethyl)phosphine as crosslinker for preparation of high fructose corn syrup at elevated temperature.

PubMed

Jia, Dong-Xu; Wang, Teng; Liu, Zi-Jian; Jin, Li-Qun; Li, Jia-Jia; Liao, Cheng-Jun; Chen, De-Shui; Zheng, Yu-Guo

2018-04-04

Glucose isomerase (GI) responsible for catalyzing the isomerization from d-glucose to d-fructose, was an important enzyme for producing high fructose corn syrup (HFCS). In a quest to prepare HFCS at elevated temperature and facilitate enzymatic recovery, an effective procedure for whole cell immobilization of refractory Thermus oshimai glucose isomerase (ToGI) onto Celite 545 using tris(hydroxymethyl)phosphine (THP) as crosslinker was established. The immobilized biocatalyst showed an activity of approximate 127.3 U/(g·immobilized product) via optimization in terms of cells loading, crosslinker concentration and crosslinking time. The pH optimum of the immobilized biocatalyst was displaced from pH 8.0 of native enzyme to neutral pH 7.0. Compared with conventional glutaraldehyde (GLU)-immobilized cells, it possessed the enhanced thermostability with 70.1% residual activity retaining after incubation at 90°C for 72 h. Moreover, the THP-immobilized biocatalyst exhibited superior operational stability, in which it retained 85.8% of initial activity after 15 batches of bioconversion at 85°C. This study paved a way for reducing catalysis cost for upscale preparation of HFCS with higher d-fructose concentration. Copyright © 2018 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Enzymatic decolourisation of Methyl Orange and Bismarck Brown using crude peroxidase from Armoracia rusticana

NASA Astrophysics Data System (ADS)

Ambatkar, Mugdha; Mukundan, Usha

2015-12-01

The decolourisation of Methyl Orange (MO) and Bismarck Brown (BB) by crude peroxidase from Armoracia rusticana (Horseradish) was studied by varying different reaction parameters. The pH of the reaction mixture, initial dye concentration, amount of enzyme and hydrogen peroxide concentration were optimised for ambient temperatures (30 ± 2 °C). The optimum pH for decolourisation was 4.0 (72.95 %) and 3.0 (79.24 %) for MO and BB, respectively. Also it was found that the Chemical Oxygen Demand of the enzyme-treated sample was significantly lower than that of the untreated controls for both dyes. The addition of a complex iron salt like Ferric EDTA was found to enhance the decolourisation of both dyes at pH 6.0, showing an increase of 8.69 % and 14.17 % in the decolourisation of MO and of BB, respectively. The present study explores the potential of crude peroxidase from horseradish to decolourise representative monoazo and diazo dyes, MO and BB, respectively. An attempt has been made to utilise a crude enzyme with appreciable activity obtained after minimal processing for the decolourisation of the aforesaid dyes. The findings of this study would find application in the enzymatic treatment of wastewater containing azo dyes.

Biodegradation of isoproturon by Pseudoxanthomonas sp. isolated from herbicide-treated wheat fields of Tarai agro-ecosystem, Pantnagar.

PubMed

Giri, Krishna; Pandey, Shailseh; Kumar, Rajesh; Rai, J P N

2016-12-01

A gram-negative, rod-shaped, isoproturon (IPU) utilizing bacterium was isolated from herbicide-applied wheat fields of Tarai agro-ecosystem, Pantnagar. The phylogenetic sequence analysis based on 16S rRNA sequence revealed that the isolate could be a distinct species within the genus Pseudomonas. The isolate was a close relative of Pseudoxanthomonas japonensis (95 % similarity) and designated as K2. The bacterial isolate showed positive reaction for oxidase, catalase, and 20 carbohydrates using KB009 Part A and B HiCarbohydrate™ Kit. Degradation experiments were conducted using 200 mg l -1 initial IPU as a source of carbon at different pH and temperatures. Maximum IPU degradation by K2 was observed at pH 7.0 and 30 °C, while least degradation at 6.5 pH and 25 °C. Addition of dextrose along with IPU as an auxiliary carbon source increased IPU degradation by 4.72 %, as compared to the IPU degradation without dextrose under optimum conditions. 4-isopropylaniline was detected as a degradation by-product in the medium. The present study demonstrated the IPU metabolizing capacity of a novel bacterial isolate K2 that can be a better choice for the remediation of IPU-contaminated sites.

Optimization of pH and nitrogen for enhanced hydrogen production by Synechocystis sp. PCC 6803 via statistical and machine learning methods.

PubMed

Burrows, Elizabeth H; Wong, Weng-Keen; Fern, Xiaoli; Chaplen, Frank W R; Ely, Roger L

2009-01-01

The nitrogen (N) concentration and pH of culture media were optimized for increased fermentative hydrogen (H(2)) production from the cyanobacterium, Synechocystis sp. PCC 6803. The optimization was conducted using two procedures, response surface methodology (RSM), which is commonly used, and a memory-based machine learning algorithm, Q2, which has not been used previously in biotechnology applications. Both RSM and Q2 were successful in predicting optimum conditions that yielded higher H(2) than the media reported by Burrows et al., Int J Hydrogen Energy. 2008;33:6092-6099 optimized for N, S, and C (called EHB-1 media hereafter), which itself yielded almost 150 times more H(2) than Synechocystis sp. PCC 6803 grown on sulfur-free BG-11 media. RSM predicted an optimum N concentration of 0.63 mM and pH of 7.77, which yielded 1.70 times more H(2) than EHB-1 media when normalized to chlorophyll concentration (0.68 +/- 0.43 micromol H(2) mg Chl(-1) h(-1)) and 1.35 times more when normalized to optical density (1.62 +/- 0.09 nmol H(2) OD(730) (-1) h(-1)). Q2 predicted an optimum of 0.36 mM N and pH of 7.88, which yielded 1.94 and 1.27 times more H(2) than EHB-1 media when normalized to chlorophyll concentration (0.77 +/- 0.44 micromol H(2) mg Chl(-1) h(-1)) and optical density (1.53 +/- 0.07 nmol H(2) OD(730) (-1) h(-1)), respectively. Both optimization methods have unique benefits and drawbacks that are identified and discussed in this study. (c) 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009.

Performance Study of Chromium (VI) Removal in Presence of Phenol in a Continuous Packed Bed Reactor by Escherichia coli Isolated from East Calcutta Wetlands

PubMed Central

Chakraborty, Bhaswati; Indra, Suvendu; Hazra, Ditipriya; Betai, Rupal; Ray, Lalitagauri; Basu, Srabanti

2013-01-01

Organic pollutants, like phenol, along with heavy metals, like chromium, are present in various industrial effluents that pose serious health hazard to humans. The present study looked at removal of chromium (VI) in presence of phenol in a counter-current continuous packed bed reactor packed with E. coli cells immobilized on clay chips. The cells removed 85% of 500 mg/L of chromium (VI) from MS media containing glucose. Glucose was then replaced by 500 mg/L phenol. Temperature and pH of the MS media prior to addition of phenol were 30°C and 7, respectively. Hydraulic retention times of phenol- and chromium (VI)-containing synthetic media and air flow rates were varied to study the removal efficiency of the reactor system. Then temperature conditions of the reactor system were varied from 10°C to 50°C, the optimum being 30°C. The pH of the media was varied from pH 1 to pH 12, and the optimum pH was found to be 7. The maximum removal efficiency of 77.7% was achieved for synthetic media containing phenol and chromium (VI) in the continuous reactor system at optimized conditions, namely, hydraulic retention time at 4.44 hr, air flow rate at 2.5 lpm, temperature at 30°C, and pH at 7. PMID:24073400

Identification of lipolytic enzymes isolated from bacteria indigenous to Eucalyptus wood species for application in the pulping industry.

PubMed

Ramnath, L; Sithole, B; Govinden, R

2017-09-01

This study highlights the importance of determining substrate specificity at variable experimental conditions. Lipases and esterases were isolated from microorganisms cultivated from Eucalyptus wood species and then concentrated (cellulases removed) and characterized. Phenol red agar plates supplemented with 1% olive oil or tributyrin was ascertained to be the most favourable method of screening for lipolytic activity. Lipolytic activity of the various enzymes were highest at 45-61 U/ml at the optimum temperature and pH of between at 30-35 °C and pH 4-5, respectively. Change in pH influenced the substrate specificity of the enzymes tested. The majority of enzymes tested displayed a propensity for longer aliphatic acyl chains such as dodecanoate (C 12 ), myristate (C 14 ), palmitate (C 16 ) and stearate (C 18 ) indicating that they could be characterised as potential lipases. Prospective esterases were also detected with specificity towards acetate (C 2 ), butyrate (C 4 ) and valerate (C 5 ). Enzymes maintained up to 95% activity at the optimal pH and temperature for 2-3 h. It is essential to test substrates at various pH and temperature when determining optimum activity of lipolytic enzymes, a method rarely employed. The stability of the enzymes at acidic pH and moderate temperatures makes them excellent candidates for application in the treatment of pitch during acid bi-sulphite pulping, which would greatly benefit the pulp and paper industry.

Influence of moisture content and temperature on degree of carbonation and the effect on Cu and Cr leaching from incineration bottom ash.

PubMed

Lin, Wenlin Yvonne; Heng, Kim Soon; Sun, Xiaolong; Wang, Jing-Yuan

2015-09-01

This study investigated the influence of moisture content and temperature on the degree of carbonation of municipal solid waste (MSW) incineration bottom ash (IBA) from two different incineration plants in Singapore. The initial rate of carbonation was affected by the nominal moisture content used. Carbonation temperature seemed to play a part in changing the actual moisture content of IBA during carbonation, which in turn affected the degree of carbonation. Results showed that 2h of carbonation was sufficient for the samples to reach a relatively high degree of carbonation that was close to the degree of carbonation observed after 1week of carbonation. Both Cu and Cr leaching also showed significant reduction after only 2h of carbonation. Therefore, the optimum moisture content and temperature were selected based on 2h of carbonation. The optimum moisture content was 15% for both incineration plants while the optimum temperature was different for the two incineration plants, at 35°C and 50°C. The effect on Cu and Cr leaching from IBA after accelerated carbonation was evaluated as a function of carbonation time. Correlation coefficient, Pearson's R, was used to determine the dominant leaching mechanism. The reduction in Cu leaching was found to be contributed by both formation of carbonate mineral and reduction of DOC leaching. On the other hand, Cr leaching seemed to be dominantly controlled by pH. Copyright © 2015 Elsevier Ltd. All rights reserved.

Optimised formation of blue Maillard reaction products of xylose and glycine model systems and associated antioxidant activity.

PubMed

Yin, Zi; Sun, Qian; Zhang, Xi; Jing, Hao

2014-05-01

A blue colour can be formed in the xylose (Xyl) and glycine (Gly) Maillard reaction (MR) model system. However, there are fewer studies on the reaction conditions for the blue Maillard reaction products (MRPs). The objective of this study is to investigate characteristic colour formation and antioxidant activities in four different MR model systems and to determine the optimum reaction conditions for the blue colour formation in a Xyl-Gly MR model system, using the random centroid optimisation program. The blue colour with an absorbance peak at 630 nm appeared before browning in the Xyl-Gly MR model system, while no blue colour formation but only browning was observed in the xylose-alanine, xylose-aspartic acid and glucose-glycine MR model systems. The Xyl-Gly MR model system also showed higher antioxidant activity than the other three model systems. The optimum conditions for blue colour formation were as follows: xylose and glycine ratio 1:0.16 (M:M), 0.20 mol L⁻¹ NaHCO₃, 406.1 mL L⁻¹ ethanol, initial pH 8.63, 33.7°C for 22.06 h, which gave a much brighter blue colour and a higher peak at 630 nm. A characteristic blue colour could be formed in the Xyl-Gly MR model system and the optimum conditions for the blue colour formation were proposed and confirmed. © 2013 Society of Chemical Industry.

Palaeococcus pacificus sp. nov., an archaeon from deep-sea hydrothermal sediment.

PubMed

Zeng, Xiang; Zhang, Xiaobo; Jiang, Lijing; Alain, Karine; Jebbar, Mohamed; Shao, Zongze

2013-06-01

A hyperthermophilic, anaerobic, piezophilic archaeon (strain DY20341(T)) was isolated from a sediment sample collected from an East Pacific Ocean hydrothermal field (1° 37' S 102° 45' W) at a depth of 2737 m. The cells were irregular cocci, 0.8-1.5 µm in diameter. Growth was observed between 50 and 90 °C (optimum 80 °C), pH 5.0 and 8.0 (optimum pH 7.0), 1% and 7% (w/v) sea salts (Sigma, optimum 3%), 1% and 4% (w/v) NaCl (optimum 3%) and 0.1 and 80 MPa (optimum 30 MPa). The minimum doubling time was 66 min at 30 MPa and 80 °C. The isolate was an obligate chemoorganoheterotroph, capable of utilizing complex organic compounds and organic acids including yeast extract, peptone, tryptone, casein, starch, Casamino acids, citrate, lactate, acetate, fumarate, propanoate and pyruvate for growth. It was strictly anaerobic and facultatively dependent on elemental sulfur or sulfate as electron acceptors, but did not reduce sulfite, thiosulfate, Fe(III) or nitrate. The presence of elemental sulfur enhanced growth. The G+C content of the genomic DNA was 43.6 ± 1 mol%. 16S rRNA gene sequence analysis revealed that the closest relative of the isolated organism was Palaeococcus ferrophilus DMJ(T) (95.7% 16S rRNA gene similarity). On the basis of its physiological properties and phylogenetic analyses, the isolate is considered to represent a novel species, for which the name Palaeococcus pacificus sp. nov. is proposed. The type strain is strain DY20341(T) (=JCM 17873(T)=DSM 24777(T)).

Study of Montmorillonite Clay for the Removal of Copper (II) by Adsorption: Full Factorial Design Approach and Cascade Forward Neural Network

PubMed Central

Turan, Nurdan Gamze; Ozgonenel, Okan

2013-01-01

An intensive study has been made of the removal efficiency of Cu(II) from industrial leachate by biosorption of montmorillonite. A 24 factorial design and cascade forward neural network (CFNN) were used to display the significant levels of the analyzed factors on the removal efficiency. The obtained model based on 24 factorial design was statistically tested using the well-known methods. The statistical analysis proves that the main effects of analyzed parameters were significant by an obtained linear model within a 95% confidence interval. The proposed CFNN model requires less experimental data and minimum calculations. Moreover, it is found to be cost-effective due to inherent advantages of its network structure. Optimization of the levels of the analyzed factors was achieved by minimizing adsorbent dosage and contact time, which were costly, and maximizing Cu(II) removal efficiency. The suggested optimum conditions are initial pH at 6, adsorbent dosage at 10 mg/L, and contact time at 10 min using raw montmorillonite with the Cu(II) removal of 80.7%. At the optimum values, removal efficiency was increased to 88.91% if the modified montmorillonite was used. PMID:24453833

Biotransformation of 5-hydroxy-methylfurfural into 2,5-furan-dicarboxylic acid by bacterial isolate using thermal acid algal hydrolysate.

PubMed

Yang, Chu-Fang; Huang, Ci-Ruei

2016-08-01

Thermal acid hydrolysis is often used to deal with lignocellulosic biomasses, but 5-hydroxy-methylfurfural (5-HMF) formed during hydrolysis deeply influences downstream fermentation. 2,5-Furan-dicarboxylic acid (FDCA), which is in the list of future important biomass platform molecules can be obtained using 5-HMF biotransformation. Based on the connection between 5-HMF removal in acid hydrolysate and FDCA production, the optimum thermal acid hydrolysis condition for macroalgae Chaetomorpha linum was established. Potential microbes capable of transforming 5-HMF into FDCA were isolated and characterized under various parameters and inoculated into algal hydrolysate to perform 5-HMF biotransformation. The optimum hydrolysis condition was to apply 0.5M HCl to treat 3% algal biomass under 121°C for 15min. Isolated Burkholderia cepacia H-2 could transform 2000mg/L 5-HMF at the initial pH of 7 at 28°C and 1276mg/L FDCA was received. Strain B. cepacia H-2 was suitable for treating the algal hydrolysate without dilution, receiving 989.5mg/L FDCA. Copyright © 2016 Elsevier Ltd. All rights reserved.

Optimization Recovery of Yttrium Oxide in Precipitation, Extraction, and Stripping Process

NASA Astrophysics Data System (ADS)

Perwira, N. I.; Basuki, K. T.; Biyantoro, D.; Effendy, N.

2018-04-01

Yttrium oxide can be used as a dopant control rod of nuclear reactors in YSH material and superconductors. Yttrium oxide is obtained in the Xenotime mineral derived from byproduct of tin mining PT Timah Bangka which contain rare earth elements (REE) dominant Y, Dy, and Gd whose content respectively about 29.53%, 7.76%, and 2.58%. Both usage in the field of nuclear and non-nuclear science and technology is need to pure from the impurities. The presence of impurities in the yttrium oxide may affect the characteristic of the material and the efficiency of its use. Thus it needs to be separated by precipitation and extraction-stripping and calcination in the making of the oxide. However, to obtain higher levels of Yttrium oxide, it is necessary to determine the optimum conditions for its separation. The purpose of this research was to determine the optimum pH of precipitation, determine acid media and concentration optimum in extraction and stripping process and determine the efficiency of the separation of Y from REE concentrate. This research was conducted with pH variation in the precipitation process that pHs were 4 - 8, the difference of acid media for the extraction process, i.e., HNO3, HCl and H2SO4 with each concentration of 0,5 M; 1 M; 1,5 M; and 2 M and for stripping process were HNO3, HCl, and H2SO4 with each concentration of 1 M; 2M; and 3 M. Based on the result, the optimum pH of precipitation process was 6,5, the optimumacid media was HNO3 0,5 M, and for stripping process media was HNO3 3 M. The efficiency of precipitation process at pH 6,5 was 69,53 %, extraction process was 96.39% and stripping process was 4,50%. The separation process from precipitation to extraction had increased the purity and the highest efficiency recovery of Y was in the extraction process and obtained Y2O3 purer compared to the feed with the Y2O3 content of 92.87%.

Biodegradation of Dimethyl Phthalate by Freshwater Unicellular Cyanobacteria.

PubMed

Zhang, Xiaohui; Liu, Lincong; Zhang, Siping; Pan, Yan; Li, Jing; Pan, Hongwei; Xu, Shiguo; Luo, Feng

2016-01-01

The biodegradation characteristics of dimethyl phthalate (DMP) by three freshwater unicellular organisms were investigated in this study. The findings revealed that all the organisms were capable of metabolizing DMP; among them, Cyanothece sp. PCC7822 achieved the highest degradation efficiency. Lower concentration of DMP supported the growth of the Cyanobacteria; however, with the increase of DMP concentration growth of Cyanobacteria was inhibited remarkably. Phthalic acid (PA) was detected to be an intermediate degradation product of DMP and accumulated in the culture solution. The optimal initial pH value for the degradation was detected to be 9.0, which mitigated the decrease of pH resulting from the production of PA. The optimum temperature for DMP degradation of the three species of organisms is 30°C. After 72 hours' incubation, no more than 11.8% of the residual of DMP aggregated in Cyanobacteria cells while majority of DMP remained in the medium. Moreover, esterase was induced by DMP and the activity kept increasing during the degradation process. This suggested that esterase could assist in the degradation of DMP.

Synthesis, characterisation of polyaniline-Fe3O4 magnetic nanocomposite and its application for removal of an acid violet 19 dye

NASA Astrophysics Data System (ADS)

Patil, Manohar R.; Khairnar, Subhash D.; Shrivastava, V. S.

2016-04-01

The present work deals with the development of a new method for the removal of dyes from an aqueous solution using polyaniline (PANI)-Fe3O4 magnetic nanocomposite. It is synthesised in situ through self-polymerisation of monomer aniline. Photocatalytic degradation studies were carried out for cationic acid violet 19 (acid fuchsine) dye using PANI-Fe3O4 nanocomposite in aqueous solution. Different parameters like catalyst dose, contact time and pH have been studied to optimise reaction condition. The optimum conditions for the removal of the dye are initial concentration 20 mg/l, adsorbent dose 6 gm/l, pH 7. The EDS technique gives elemental composition of synthesised PANI-Fe3O4. The SEM and XRD studies were carried for morphological feature characteristics of PANI-Fe3O4 nanocomposite. The VSM (vibrating sample magnetometer) gives magnetic property of PANI-Fe3O4 nanocomposite; also FT-IR analysis gives characteristics frequency of synthesised PANI-Fe3O4. Besides the above studies kinetic study has also been carried out.

Chitin-Lignin Material as a Novel Matrix for Enzyme Immobilization

PubMed Central

Zdarta, Jakub; Klapiszewski, Łukasz; Wysokowski, Marcin; Norman, Małgorzata; Kołodziejczak-Radzimska, Agnieszka; Moszyński, Dariusz; Ehrlich, Hermann; Maciejewski, Hieronim; Stelling, Allison L.; Jesionowski, Teofil

2015-01-01

Innovative materials were made via the combination of chitin and lignin, and the immobilization of lipase from Aspergillus niger. Analysis by techniques including FTIR, XPS and 13C CP MAS NMR confirmed the effective immobilization of the enzyme on the surface of the composite support. The electrokinetic properties of the resulting systems were also determined. Results obtained from elemental analysis and by the Bradford method enabled the determination of optimum parameters for the immobilization process. Based on the hydrolysis reaction of para-nitrophenyl palmitate, a determination was made of the catalytic activity, thermal and pH stability, and reusability. The systems with immobilized enzymes were found to have a hydrolytic activity of 5.72 mU, and increased thermal and pH stability compared with the native lipase. The products were also shown to retain approximately 80% of their initial catalytic activity, even after 20 reaction cycles. The immobilization process, using a cheap, non-toxic matrix of natural origin, leads to systems with potential applications in wastewater remediation processes and in biosensors. PMID:25903282

Combined heterogeneous Electro-Fenton and biological process for the treatment of stabilized landfill leachate.

PubMed

Baiju, Archa; Gandhimathi, R; Ramesh, S T; Nidheesh, P V

2018-03-15

Treatment of stabilized landfill leachate is a great challenge due to its poor biodegradability. Present study made an attempt to treat this wastewater by combining electro-Fenton (E-Fenton) and biological process. E-Fenton treatment was applied prior to biological process to enhance the biodegradability of leachate, which will be beneficial for the subsequent biological process. This study also investigates the efficiency of iron molybdophosphate (FeMoPO) nanoparticles as a heterogeneous catalyst in E-Fenton process. The effects of initial pH, catalyst dosage, applied voltage and electrode spacing on Chemical Oxygen Demand (COD) removal efficiency were analyzed to determine the optimum conditions. Heterogeneous E-Fenton process gave 82% COD removal at pH 2, catalyst dosage of 50 mg/L, voltage 5 V, electrode spacing 3 cm and electrode area 25 cm 2 . Combined E-Fenton and biological treatment resulted an overall COD removal of 97%, bringing down the final COD to 192 mg/L. Copyright © 2018 Elsevier Ltd. All rights reserved.

Structural, optical and photocatalytic properties of visible light driven zinc oxide hybridized two-dimensional π-conjugated polymeric g-C3N4 composite

NASA Astrophysics Data System (ADS)

Murugesan, Pramila; Girichandran, Nandalal; Narayanan, Sheeba; Manickam, Matheswaran

2018-01-01

Zinc oxide (ZnO) hybridized with graphitic carbon nitride (g-C3N4) composite was prepared via one step calcination method and well characterized using various physiochemical techniques. The prepared composite exhibits excellent photocatalytic activity and stability for decolorization of methylene blue (MB) dye solution under visible light irradiation. Effect of various rate determining parameters such as catalyst loading, initial dye concentration and pH on the decolorization of MB has been analyzed. The optimum conditions for efficient color removal were found to be 7, 10 ppm and 2 g/L for pH, dye concentration and catalyst dosage respectively. The intermediate compounds formed during the decolorization process were evaluated by GCMS spectra. It was inferred that the ZnO/g-C3N4 (98.83%) composite exhibits highest decolorization efficiency as compare with pure g-C3N4 (35.21%). Such enhancement of photocataytic activity is mainly attributed to the efficient separation of photo induced electron hole pairs via Z-scheme model composed of ZnO and g-C3N4.

Using Central Composite Experimental Design to Optimize the Degradation of Tylosin from Aqueous Solution by Photo-Fenton Reaction

PubMed Central

Sarrai, Abd Elaziz; Hanini, Salah; Merzouk, Nachida Kasbadji; Tassalit, Djilali; Szabó, Tibor; Hernádi, Klára; Nagy, László

2016-01-01

The feasibility of the application of the Photo-Fenton process in the treatment of aqueous solution contaminated by Tylosin antibiotic was evaluated. The Response Surface Methodology (RSM) based on Central Composite Design (CCD) was used to evaluate and optimize the effect of hydrogen peroxide, ferrous ion concentration and initial pH as independent variables on the total organic carbon (TOC) removal as the response function. The interaction effects and optimal parameters were obtained by using MODDE software. The significance of the independent variables and their interactions was tested by means of analysis of variance (ANOVA) with a 95% confidence level. Results show that the concentration of the ferrous ion and pH were the main parameters affecting TOC removal, while peroxide concentration had a slight effect on the reaction. The optimum operating conditions to achieve maximum TOC removal were determined. The model prediction for maximum TOC removal was compared to the experimental result at optimal operating conditions. A good agreement between the model prediction and experimental results confirms the soundness of the developed model. PMID:28773551

Laccase-conjugated amino-functionalized nanosilica for efficient degradation of Reactive Violet 1 dye

NASA Astrophysics Data System (ADS)

Gahlout, Mayur; Rudakiya, Darshan M.; Gupte, Shilpa; Gupte, Akshaya

2017-08-01

Immobilization of enzyme with nanostructures enhances its ideal characteristics, which may allow the enzyme to become more stable and resistant. The present investigation deals with the formulation of laccase nanosilica conjugates to overcome the problems associated with its stability and reusability. Synthesized nanosilica and laccase nanoparticles were spherical shaped, with the mean size of 220 and 615 nm, respectively. Laccase nanoparticles had an optimum temperature of 55 °C and pH 4.0 for the oxidation of ABTS. Laccase nanoparticle retained 79% of residual activity till 20th cycle. It also showed 91% of its initial activity at lower temperatures even after 60 days. Laccase nanoparticles were applied for Reactive Violet 1 degradation wherein 96.76% of decolourization was obtained at pH 5.0 and 30 °C within 12 h. Toxicity studies on microbes and plants suggested that the degraded metabolites were less toxic than control dye. Thus, the method applied for immobilization increased storage stability and reusability of laccase, and therefore, it can be utilized for efficient degradation of azo dyes.

Photochemical degradation of an anionic surfactant by TiO2 nanoparticle doped with C, N in aqueous solution

NASA Astrophysics Data System (ADS)

Zamiri, M.; Giahi, M.

2016-12-01

Novel C,N-doped TiO2 nanoparticles were prepared by a solid phase reaction. The catalyst was characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). The results showed that crystallite size of synthesized C,N-doped TiO2 particles were in nanoscale. UV light photocatalytic studies were carried out using sodium naphthalenesulfonate formaldehyde condensate (SNF) as a model pollutant. The effects of initial concentration of surfactant, catalyst amount, pH, addition of oxidant on the reaction rate were ascertained and optimum conditions for maximum degradation was determined. The results indicated that for a solution of 20 mg/L of SNF, almost 98.7% of the substance were removed at pH 4.0 and 0.44 g/L photocatalyst load, with addition of 1 mM K2S2O8 and irradiation time of 90 min. The kinetics of the process was studied, and the photodegradation rate of SNF was found to obey pseudo-first-order kinetics equation represented by the Langmuir-Hinshelwood model.

Removal of Pb (II) ions from aqueous solutions by Cladophora rivularis (Linnaeus) Hoek.

PubMed

Jafari, Naser; Senobari, Zoreh

2012-01-01

Biosorption of Pb(II) using Cladophora rivularis was examined as a function of initial pH heavy metal concentration and temperature. The optimum pH value for the biosorption of lead was 4.0. The adsorption equilibriums were well described by Langmuir and Freundlich isotherm models and it was implied by the results that the C. rivularis biomass is suitable for the development of efficient biosorbent in order to remove Pb(II) from wastewater and to recover it. The high values of correlation coefficient (R(2) = 0.984) demonstrate equilibrium data concerning algal biomass, which is well fitted in Freundlich isotherms model equations. The dimensionless parameter R(L) is found in the range of 0.0639 to 0.1925 (0 < R(L) < 1), which confirms the favorable biosorption process. Fourier transform infra-red (FTIR) spectroscopy of C. rivularis was used to reveal the main function groups of biosorption, which were hydroxyl, amine groups, C-H stretching vibrations of -CH3 and -CH2, and complexation with functional groups. All these results suggest that C. rivularis can be used effectively for removal of Pb(II).

Biosorption of lead (II) ions by NaOH-activated apple (Malus domestica) juice residue

NASA Astrophysics Data System (ADS)

Arimurti, Devita Dwi; Heraldy, Eddy; Lestari, Witri Wahyu

2016-02-01

This research studied the removal of Pb(II) ions from aqueous solutions using NaOH-activated apple (Malus domestica) juice residue. Biosorbent was characterized with Fourier Transform Infrared Spectrophotometer (FTIR), and Surface Area Analyzer (SAA). The effects of biosorbent dosage, pH, contact time and initial metal ion concentration had been investigated in batch-adsorption method. The biosorption kinetic data were analyzed by pseudo-first-order and pseudo-second-order kinetics model. Freundlich and Langmuir's isotherm were used to describe the biosorption process. The optimum conditions of Pb(II) adsorption was observed at 60 min of contact time, pH 4, and 0.1 g biosorbent dosage in 25 ml solution. The biosorption kinetics followed the pseudo-second-order kinetic model, resulted biosorption constant rate of 0.184 g.mg-1.min-1. The Langmuir isotherm model exhibited the best fit to experimental data. The maximum biosorption capacity of Pb(II) determined according to the Langmuir model was 90.90 mg.g-1 at 302 K, with the adsorption energy of 26.429 kJ.mol-1.

Response surface methodology for cadmium biosorption on Pseudomonas aeruginosa.

PubMed

Ahmady-Asbchin, Salman

2016-01-01

In this research the effects of various physicochemical factors on Cd(2+) biosorption such as initial metal concentration, pH and contact exposure time were studied. This study has shown a Cd(2+) biosorption, equilibrium time of about 5 min for Pseudomonas aeruginosa and the adsorption equilibrium data were well described by Langmuir equation. The maximum capacity for biosorption has been extrapolated to 0.56 mmol.g(-1) for P. aeruginosa. The thermodynamic properties ΔG(0), ΔH(0), and ΔS(0) of Cd(2+) for biosorption were analyzed by the equilibrium constant value obtained from experimented data at different temperatures. The results show that biosorption of Cd(2+) by P. aeruginosa are endothermic and spontaneous with ΔH value of 36.35 J.mol(-1). By response surface methodology, the quadratic model has adequately described the experimental data based on the adjusted determination coefficient (R(2) = 0.98). The optimum conditions for maximum uptake onto the biosorbent were established at 0.5 g.l(-1) biosorbent concentration, pH 6 for the aqueous solution, and a temperature of 30 °C.

Preliminary Studies on Oleochemical Wastewater Treatment using Submerged Bed Biofilm Reactor (SBBR)

NASA Astrophysics Data System (ADS)

Ismail, Z.; Mahmood, N. A. N.; Ghafar, U. S. A.; Umor, N. A.; Muhammad, S. A. F.

2017-06-01

Wastewater discharge from the industry into water sources is one of the main reason for water pollution. The oleochemicals industry effluent produces high content of chemical oxygen demand (COD) with value between 6000-20,000 ppm. Effective treatment is required before wastewater effluent is discharged to environment. The aim of the study is to develop submerged bed biofilm reactor (SBBR) with packing materials in the cosmoball® carrier. Water quality such as chemical oxygen demands (COD), turbidity and pH were analysed. The result shows that the initial COD of 6000 ppm was reduced below 200 ppm. The optimum conditions for SBBR were obtained when green sponges used as packing material in cosmoball® effluent flowrate set at 100 mL/min; 1:1 ratio of cosmoball® volume to reactor volume and 1:1 ratio of active sludge (mixed culture) volume to reactor volume. Turbidity and pH were recorded with 9.0 NTU and 7.0 respectively, which indicated that SBBR is feasible as an alternative for conventional biological treatment in oleochemical industry.

Biodegradation of Dimethyl Phthalate by Freshwater Unicellular Cyanobacteria

PubMed Central

Zhang, Xiaohui; Liu, Lincong; Zhang, Siping; Pan, Yan; Li, Jing; Pan, Hongwei

2016-01-01

The biodegradation characteristics of dimethyl phthalate (DMP) by three freshwater unicellular organisms were investigated in this study. The findings revealed that all the organisms were capable of metabolizing DMP; among them, Cyanothece sp. PCC7822 achieved the highest degradation efficiency. Lower concentration of DMP supported the growth of the Cyanobacteria; however, with the increase of DMP concentration growth of Cyanobacteria was inhibited remarkably. Phthalic acid (PA) was detected to be an intermediate degradation product of DMP and accumulated in the culture solution. The optimal initial pH value for the degradation was detected to be 9.0, which mitigated the decrease of pH resulting from the production of PA. The optimum temperature for DMP degradation of the three species of organisms is 30°C. After 72 hours' incubation, no more than 11.8% of the residual of DMP aggregated in Cyanobacteria cells while majority of DMP remained in the medium. Moreover, esterase was induced by DMP and the activity kept increasing during the degradation process. This suggested that esterase could assist in the degradation of DMP. PMID:28078293

Treatment of wastewater containing toxic chromium using new activated carbon developed from date palm seed.

PubMed

El Nemr, Ahmed; Khaled, Azza; Abdelwahab, Ola; El-Sikaily, Amany

2008-03-21

The use of a new activated carbon developed from date palm seed wastes, generated in the jam industry, for removing toxic chromium from aqueous solution has been investigated. The activated carbon has been achieved from date palm seed by dehydrating methods using concentrated sulfuric acid. The batch experiments were conducted to determine the adsorption capacity of the biomass. The effect of initial metal concentration (25-125mgl(-1)), pH, contact time, and concentration of date palm seed carbon have been studied at room temperature. A strong dependence of the adsorption capacity on pH was observed, the capacity increase as pH value decrease and the optimum pH value is pH 1.0. Kinetics and adsorption equilibrium were studied at different sorbent doses. The adsorption process was fast and the equilibrium was reached within 180min. The maximum removal was 100% for 75mgl(-1) of Cr(+ concentration on 4gl(-1) carbon concentration and the maximum adsorption capacity was 120.48mgg(-1). The kinetic data were analyzed using various kinetic models - pseudo-first order equation, pseudo-second order equation, Elovich equation and intraparticle diffusion equation - and the equilibrium data were tested using several isotherm models, Langmuir, Freundlich, Koble-Corrigan, Redlich-Peterson, Tempkin, Dubinin-Radushkevich and Generalized isotherm equations. The Elovich equation and pseudo-second order equation provide the greatest accuracy for the kinetic data and Koble-Corrigan and Langmuir models the closest fit for the equilibrium data. Activation energy of sorption has also been evaluated as 0.115 and 0.229kJmol(-1).

Spatial characterization of proteolytic enzyme activity in the foregut region of the adult necrophagous fly, Protophormia terraenovae.

PubMed

Rivers, David B; Acca, Gillian; Fink, Marc; Brogan, Rebecca; Schoeffield, Andrew

2014-08-01

The spatial distribution of proteolytic enzymes in the adult foregut of Protophormia terraenovae was studied in the context of protein digestion and regurgitation. Based on substrate specificity, pH optima, and use of specific protease inhibitors, all adults tested displayed enzyme activity in the foregut consistent with pepsin, trypsin and chymotrypsin. Chymotrypsin-like and trypsin-like enzyme activity were detected in all gut fluids and tissues tested, with chymotrypsin displaying the highest activity in saliva and salivary gland tissue, whereas maximal trypsin activity was evident in the crop. Pepsin-like activity was only evident in crop fluids and tissues. The activity of all three enzymes was low or undetectable (pepsin) in the fluids and tissue homogenates derived from the esophagus and cardia of any of the adults assayed. Fed adult females displayed higher enzyme activities than fed males, and the activity of all three enzymes were much more prevalent in fed adults than starved. The pH optimum of the trypsin-like enzyme was between pH 7.0 and 8.0; chymotrypsin was near pH 8.0; and maximal pepsin-like activity occurred between pH 1.0 and 2.0. Regurgitate from fed adult females displayed enzyme activity consistent with the proteolytic enzymes detected in crop gut fluids. Enzymes in regurgitate were not derived from food sources based on assays of bovine liver samples. These latter observations suggest that adult flies release fluids from foregut when encountering dry foods, potentially as a means to initiate extra-oral digestion. Copyright © 2014 Elsevier Ltd. All rights reserved.

Different treatment strategies for highly polluted landfill leachate in developing countries.

PubMed

Mahmud, Kashif; Hossain, Md Delwar; Shams, Shahriar

2012-11-01

The aim of this research was to determine appropriate treatment technique for effective treatment of heavily polluted landfill leachate. We accomplished several treatment experiments: (i) aerobic biological treatment, (ii) chemical coagulation, (iii) advanced oxidation process (AOP) and (iv) several combined treatment strategies. Efficiency of these treatment procedures were monitored by analysing COD and colour removal. Leachate used for this study was taken from Matuail landfill site at Dhaka city. With extended aeration process which is currently used in Matuail landfill site for leachate treatment, maximum COD and colour removal of 36% and 20%, respectively could be achieved with optimum retention period of 7 days. With optimum aluminium sulphate dose of 15,000 mg/L and pH value of 7.0, maximum COD and colour removals of 34% and 66%, respectively were observed by using chemical coagulation. With optimum pH of 5.0 and optimum dosages of reagents having H(2)O(2)/Fe(2+) molar ratio of 1.3 the highest removal of COD and colour were found 68% and 87%, respectively with sludge production of 55%. Fenton treatment which is an advanced oxidation process was the most successful between these three separate treatment procedures. Among the combined treatment options performed, extended aeration followed by Fenton method was the most suitable one. Copyright © 2011 Elsevier Ltd. All rights reserved.

Exploring the Limits of Cell Adhesion under Shear Stress within Physiological Conditions and beyond on a Chip.

PubMed

Stamp, Melanie E M; Jötten, Anna M; Kudella, Patrick W; Breyer, Dominik; Strobl, Florian G; Geislinger, Thomas M; Wixforth, Achim; Westerhausen, Christoph

2016-10-21

Cell adhesion processes are of ubiquitous importance for biomedical applications such as optimization of implant materials. Here, not only physiological conditions such as temperature or pH, but also topographical structures play crucial roles, as inflammatory reactions after surgery can diminish osseointegration. In this study, we systematically investigate cell adhesion under static, dynamic and physiologically relevant conditions employing a lab-on-a-chip system. We screen adhesion of the bone osteosarcoma cell line SaOs-2 on a titanium implant material for pH and temperature values in the physiological range and beyond, to explore the limits of cell adhesion, e.g., for feverish and acidic conditions. A detailed study of different surface roughness R q gives insight into the correlation between the cells' abilities to adhere and withstand shear flow and the topography of the substrates, finding a local optimum at R q = 22 nm. We use shear stress induced by acoustic streaming to determine a measure for the ability of cell adhesion under an external force for various conditions. We find an optimum of cell adhesion for T = 37 °C and pH = 7.4 with decreasing cell adhesion outside the physiological range, especially for high T and low pH. We find constant detachment rates in the physiological regime, but this behavior tends to collapse at the limits of 41 °C and pH 4.

Factors affecting degradation of dimethyl sulfoxide (DMSO) by fluidized-bed Fenton process.

PubMed

Bellotindos, Luzvisminda M; Lu, Meng-Hsuan; Methatham, Thanakorn; Lu, Ming-Chun

2014-12-01

In this study, the target compound is dimethyl sulfoxide (DMSO), which is used as a photoresist stripping solvent in the semiconductor and thin-film transistor liquid crystal display (TFT-LCD) manufacturing processes. The effects of the operating parameters (pH, Fe(2+) and H2O2 concentrations) on the degradation of DMSO in the fluidized-bed Fenton process were examined. This study used the Box-Behnken design (BBD) to investigate the optimum conditions of DMSO degradation. The highest DMSO removal was 98 % for pH 3, when the H2O2 to Fe(2+) molar ratio was 12. At pH 2 and 4, the highest DMSO removal was 82 %, when the H2O2 to Fe(2+) molar ratio was 6.5. The correlation of DMSO removal showed that the effect of the parameters on DMSO removal followed the order Fe(2+) > H2O2 > pH. From the BBD prediction, the optimum conditions were pH 3, 5 mM of Fe(2+), and 60 mM of H2O2. The difference between the experimental value (98 %) and the predicted value (96 %) was not significant. The removal efficiencies of DMSO, chemical oxygen demand (COD), total organic carbon (TOC), and iron in the fluidized-bed Fenton process were higher than those in the traditional Fenton process.

Platinum and rhenium extraction from a spent refinery catalyst using Bacillus megaterium as a cyanogenic bacterium: statistical modeling and process optimization.

PubMed

Motaghed, M; Mousavi, S M; Rastegar, S O; Shojaosadati, S A

2014-11-01

The present study evaluated the potential of Bacillus megaterium as a cyanogenic bacterium to produce cyanide for solubilization of platinum and rhenium from a spent refinery catalyst. Response surface methodology was applied to study the effects and interaction between two main effective parameters including initial glycine concentration and pulp density. Maximum Pt and Re recovery was obtained 15.7% and 98%, respectively, under optimum conditions of 12.8 g/l initial glycine concentration and 4% (w/v) pulp density after 7 days. Increasing the free cyanide concentration to 3.6 mg/l, varying the pH from 6.7 to 9, and increasing the dissolved oxygen from 2 to 5mg/l demonstrated the growth characteristics of B. megaterium during bioleaching process. The modified shrinking core model was used to determine the rate limiting step of the process. It was found that diffusion through the product layer is the rate controlling step. Copyright © 2014 Elsevier Ltd. All rights reserved.

Studies on flower initiation of Super-Dwarf wheat under stress conditions simulating those on the Space Station, Mir

NASA Technical Reports Server (NTRS)

Jiang, L.; Salisbury, F. B.; Campbell, W. F.; Carman, J. G.; Nan, R.

1998-01-01

Super-Dwarf wheat plants were grown in growth chambers under 12 treatments with three photoperiods (18 h, 21 h, 24 h) and four carbon dioxide (CO2) levels (360, 1,200, 3,000 and 7,000 micromoles mol-1). Carbon dioxide concentrations affected flower initiation rates of Super-Dwarf wheat. The optimum CO2 level for flower initiation and development was 1,200 micromoles mol-1. Super-optimum CO2 levels delayed flower initiation, but did not decrease final flower bud number per head. Longer photoperiods not only accelerated flower initiation rates, but also decreased deleterious effects of super-optimum CO2. Flower bud size and head length at the same developmental stage were larger under longer photoperiods, but final flower bud number was not affected by photoperiod.

Simultaneous arsenic and fluoride removal from synthetic and real groundwater by electrocoagulation process: Parametric and cost evaluation.

PubMed

Thakur, Lokendra Singh; Mondal, Prasenjit

2017-04-01

Co-existence of arsenic and fluoride in groundwater has raised severe health issues to living being. Thus, the present research has been conducted for simultaneous removal of arsenic and fluoride from synthetic groundwater by using electrocoagulation process with aluminum electrode. Effects of initial pH, current density, run time, inter electrode distance and NaCl concentration over percentage removal of arsenic and fluoride as well as operating cost have been studied. The optimum experimental conditions are found to be initial pH: 7, current density: 10 A/m 2 , run time: 95 min, inter electrode distance: 1 cm, NaCl concentration: 0.71 g/l for removal of 98.51% arsenic (initial concentration: 550 μg/l) and 88.33% fluoride (initial concentration: 12 mg/l). The concentration of arsenic and fluoride in treated water are found to be 8.19 μg/l and 1.4 mg/l, respectively, with an operating cost of 0.357 USD/m 3 treated water. Pseudo first and second order kinetic model of individual and simultaneous arsenic and fluoride removal in electrocoagulation have also been studied. Produced sludge characterization studies also confirm the presence of arsenic in As(III) form, and fluoride in sludge. The present electrocoagulation process is able to reduce the arsenic and fluoride concentration of synthetic as well as real groundwater to below 10 μg/l and 1.5 mg/l, respectively, which are maximum contaminant level of these elements in drinking water according to WHO guidelines. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of reaction temperature on biodiesel production from waste cooking oil using lipase as biocatalyst

NASA Astrophysics Data System (ADS)

Istiningrum, Reni Banowati; Aprianto, Toni; Pamungkas, Febria Lutfi Udin

2017-12-01

This study aims to determine the effect of temperature on conversion of biodiesel from waste cooking oil enzymatically using lipase extracted from rice bran. The feedstock was simulated waste cooking oil and lipase enzyme was extracted with buffer pH variation. The enzyme activity was titrimetrically determined and the optimum pH buffer was used to study the effect of temperature on the transesterification reaction. Temperature effects were assessed in the range of 45-60 °C and the content of methyl esters in biodiesel was determined by GC-MS. The reaction temperature significantly influences the transesterification reaction with optimum biodiesel conversion occurred at 55 °C with methyl ester content of 81.19%. The methyl ester composition in the resulting biodiesel is methyl palmitate, methyl oleate and methyl stearate.

Enhancement of 2,3-Butanediol Production by Klebsiella oxytoca PTCC 1402

PubMed Central

Anvari, Maesomeh; Safari Motlagh, Mohammad Reza

2011-01-01

Optimal operating parameters of 2,3-Butanediol production using Klebsiella oxytoca under submerged culture conditions are determined by using Taguchi method. The effect of different factors including medium composition, pH, temperature, mixing intensity, and inoculum size on 2,3-butanediol production was analyzed using the Taguchi method in three levels. Based on these analyses the optimum concentrations of glucose, acetic acid, and succinic acid were found to be 6, 0.5, and 1.0 (% w/v), respectively. Furthermore, optimum values for temperature, inoculum size, pH, and the shaking speed were determined as 37°C, 8 (g/L), 6.1, and 150 rpm, respectively. The optimal combinations of factors obtained from the proposed DOE methodology was further validated by conducting fermentation experiments and the obtained results revealed an enhanced 2,3-Butanediol yield of 44%. PMID:21318172

Isolation, Fractionation and Characterization of Catalase from Neurospora crassa (InaCC F226)

NASA Astrophysics Data System (ADS)

Suryani; Ambarsari, L.; Lindawati, E.

2017-03-01

Catalase from Indigenous isolate Neurospora crassa InaCC F226 has been isolated, fractionated and characterized. Production of catalase by Neurospora crassa was done by using PDA medium (Potato Dextrosa Agar) and fractionated with ammonium sulphate with 20-80% saturation. Fraction 60% was optimum saturation of ammonium sulphate and had highest specific activity 3339.82 U/mg with purity 6.09 times, total protein 0.920 mg and yield 88.57%. The optimum pH and temperature for catalase activity were at 40°C and pH 7.0, respectively. The metal ions that stimulated catalase activity acted were Ca2+, Mn2+ and Zn2+, and inhibitors were EDTA, Mg2+ and Cu2+. Based on Km and Vmax values were 0.2384 mM and 13.3156 s/mM.

Optimization of volatile fatty acid production with co-substrate of food wastes and dewatered excess sludge using response surface methodology.

PubMed

Hong, Chen; Haiyun, Wu

2010-07-01

Central-composite design (CCD) and response surface methodology (RSM) were used to optimize the parameters of volatile fatty acid (VFA) production from food wastes and dewatered excess sludge in a semi-continuous process. The effects of four variables (food wastes composition in the co-substrate of food wastes and excess sludge, hydraulic retention time (HRT), organic loading rate (OLR), and pH) on acidogenesis were evaluated individually and interactively. The optimum condition derived via RSM was food wastes composition, 88.03%; HRT, 8.92 days; OLR, 8.31 g VSS/ld; and pH 6.99. The experimental VFA concentration was 29,099 mg/l under this optimum condition, which was well in agreement with the predicted value of 28,000 mg/l. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Column with CNT/magnesium oxide composite for lead(II) removal from water.

PubMed

Saleh, Tawfik A; Gupta, Vinod K

2012-05-01

In this study, manganese dioxide-coated multiwall carbon nanotube (MnO(2)/CNT) nanocomposite has been successfully synthesized. The as-produced nanocomposite was characterized by different characteristic tools, such as X-ray diffraction, SEM, and FTIR. The MnO(2)/CNT nanocomposite was utilized as a fixed bed in a column system for removal of lead(II) from water. The experimental conditions were investigated and optimized. The pH range between 3 and 7 was studied; the optimum removal was found when the pH was equal to 6 and 7. The thickness of MnO(2)/CNT nanocomposite compact layer was also changed to find the optimum parameter for higher removal. It was observed that the slower the flow rates of the feed solution the higher the removal because of larger contact time.

Characterization of water treatment sludge and its reuse as coagulant.

PubMed

Ahmad, Tarique; Ahmad, Kafeel; Ahad, Abdul; Alam, Mehtab

2016-11-01

Coagulation-flocculation process results in the generation of large volume of waste or residue, known as water treatment sludge (WTS), in the purification of surface water for potable supplies. Sustainable management of the inevitable waste requires careful attention from the plant operators and sludge managers. In this study, WTS produced with the optimum alum dose of 30 ml/L at the laboratory scale has been treated with sulphuric acid to bring forth a product known as sludge reagent product (SRP). The performance of SRP is evaluated for its efficiency in removing the colloidal suspensions from the Yamuna river water over wide pH range of 2-13. 1% sludge acidified with sulphuric acid of normality 2.5 at the rate of 0.05 ml/ml sludge has been observed as the optimum condition for preparing SRP from WTS. The percentage turbidity removal is greater at higher pH value and increases with increasing the dosage of SRP. The optimum SRP dosage of 8 ml/L in the pH range of 6-8 performed well in removing the colloidal suspension and other impurities from the Yamuna water. The quality of treated water met the prescribed standards for most of the quality parameters. Thus, SRP has the potential to substitute the conventional coagulants partially or completely in the water treatment process, depending on the quality needed at the users end. Copyright © 2016 Elsevier Ltd. All rights reserved.

Purification and biochemical characterization of insoluble acid invertase (INAC-INV) from pea seedlings.

PubMed

Kim, Donggiun; Lee, Gunsup; Chang, Man; Park, Jongbum; Chung, Youngjae; Lee, Sukchan; Lee, Taek-Kyun

2011-10-26

Invertase (EC 3.2.1.26) catalyzes the hydrolysis of sucrose into D-glucose and D-fructose. Insoluble acid invertase (INAC-INV) was purified from pea (Pisum sativum L.) by sequential procedures entailing ammonium sulfate precipitation, ion exchange chromatography, absorption chromatography, reactive green-19 affinity chromatography, and gel filtration. The purified INAC-INV had a pH optimum of 4.0 and a temperature optimum of 45 °C. The effects of various concentrations of Tris-HCl, HgCl(2), and CuSO(4) on the activities of the purified invertase were examined. INAC-INV was not affected by Tris-HCl and HgCl(2). INAC-INV activity was inhibited by 6.2 mM CuSO(4) up to 50%. The enzymes display typical hyperbolic saturation kinetics for sucrose hydrolysis. The K(m) and V(max) values of INAC-INV were determined to be 4.41 mM and 8.41 U (mg protein)(-1) min(-1), respectively. INAC-INV is a true member of the β-fructofuranosidases, which can react with sucrose and raffinose as substrates. SDS-PAGE and immunoblotting were used to determine the molecular mass of INAC-INV to be 69 kDa. The isoelectric point of INAC-INV was estimated to be about pH 8.0. Taken together, INAC-INV is a pea seedling invertase with a stable and optimum activity at lower acid pH and at higher temperature than other invertases.

Overexpression and characterization of laccase from Trametes versicolor in Pichia pastoris.

PubMed

Li, Q; Pei, J; Zhao, L; Xie, J; Cao, F; Wang, G

2014-01-01

A laccase-encoding gene of Trametes versicolor, lccA, was cloned and expressed in Pichia pastoris X33. The lccA gene consists ofa 1560 bp open reading frame encoding 519 amino acids, which was classified into family copper blue oxidase. To improve the expression level of recombinant laccase in P. pastoris, conditions of the fermentation were optimized by the single factor experiments. The optimal fermentation conditions for the laccase production in shake flask cultivation using BMGY medium were obtained: the optimal initial pH 7.0, the presence of 0.5 mM Cu2+, 0.6% methanol added into the culture every 24 h. The laccase activity was up to 11.972 U/L under optimal conditions after 16 days of induction in a medium with 4% peptone. After 100 h of large scale production in 5 L fermenter the enzyme activity reached 18.123 U/L. The recombinant laccase was purified by ultrafiltration and (NH4)2SO4 precipitation showing a single band on SDS-PAGE, which had a molecular mass of 58 kDa. The optimum pH and temperature for the laccase were pH 2.0 and 50 degrees C with 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) as a substrate. The recombinant laccase was stable over a pH range of 2.0-7.0. The K(m) and the V(max) value of LccA were 0.43 mM and 82.3 U/mg for ABTS, respectively.

Improved Production and Antitumor Properties of Triterpene Acids from Submerged Culture of Ganoderma lingzhi.

PubMed

Wang, Xiao-Ling; Ding, Zhong-Yang; Liu, Gao-Qiang; Yang, Hailong; Zhou, Guo-Ying

2016-10-20

Triterpene acids (TAs) are the major bioactive constituents in the medicinal fungus Ganoderma lingzhi . However, fermentative production of TAs has not been optimized for commercial use, and whether the TAs isolated from G. lingzhi submerged culture mycelia possess antitumor activity needs to be further proven. In this study, enhanced TA yield and productivity were attained with G. lingzhi using response surface methodology. The interactions of three variables were studied using a Box-Benhnken design, namely initial pH, dissolved oxygen (DO) and fermentation temperature. The optimum conditions were an initial pH of 5.9, 20.0% DO and 28.6 °C. These conditions resulted in a TA yield of 308.1 mg/L in a 5-L stirred bioreactor. Furthermore, the optimized conditions were then successfully scaled up to a production scale of 200 L, and maximum TA production and productivity of 295.3 mg/L and 49.2 mg/L/day were achieved, which represented 80.9% and 111.5% increases, respectively, compared with the non-optimized conditions. Additionally, the triterpene acid extract (TAE) from G. lingzhi mycelia was found to be cytotoxic to the SMMC-7721 and SW620 cell lines in vitro, and the TAE exhibited dose-dependent antitumor activity against the solid tumor sarcoma 180 in vivo. Chemical analysis revealed that the key active triterpene compounds, ganoderic acid T and ganoderic acid Me, predominated in the extract.

Exploitation of dark fermented effluent of cheese whey by co-culture of Rhodobacter sphaeroides and Bacillus firmus for photo-hydrogen production.

PubMed

Pandey, A; Pandey, A

2017-07-31

In this study photo-hydrogen production from cheese whey dark fermentation (DF) effluent by the co-culture of Rhodobacter sphaeroides -NMBL-01 and Bacillus firmus - NMBL-03 has been reported. The effect of pH, initial chemical oxygen demand (COD) and the concentration effect of FeSO4.7H2O on photo-hydrogen production have been investigated. The end products of dark fermentation effluent of cheese whey were mainly comprised of soluble organic acids, i.e. butyric acid and lactic acid. The batch process was carried out under light intensity of 2.5 kLux at 32 ± 2oC without any addition of extra carbon and nitrogen source. The single parameter optimization studies revealed optimum pH 6.5, initial COD 4.71 g/L and supplementation of Fe2+ concentration 100 mg/L. The maximum cumulative hydrogen production and yield were found to be 469 ± 45.8 ml H2/L and 146.56 ± 14.31 ml H2/g COD reduced (67.9% reduction in COD) respectively. The mutual interactions among the process parameters were also investigated by three factorial Box-Behnken design of response surface methodology. The optimized experimental values were found concurrent with the calculated values obtained from the theoretical model.

[Biodegradation characteristics of o-chlorophenol with photosynthetic bacteria PSB-1D].

PubMed

Hu, Xiao-min; Dong, Yi-hu; Li, Liang; Lu, Juan; He, Ying-dian; Gao, Yang

2010-07-01

A strain of photosynthetic bacteria named PSB-1D with degradation of o-chlorophenol (2-CP) was isolated and screened from the shallow substrate sludge in downstream side of the sewage outfall of an insecticide factory. The PSB-1D is identified preliminarily as Rhodopseudomonas sp. according to its colony and cell morphological properties, physiological biochemical characteristics and absorption spectrum analysis of living cells. The experiments results of relationship between PSB-1D growth and o-chlorophenol degradation showed that the degradation rate of o-chlorophenol was up to 57.26% after 7 days cultural time. The main environmental factors including way of illumination and oxygen, initial pH, cultural temperature, illumination intensity had distinctly influenced on the o-chlorophenol degradation with PSB-1D. The results showed that the optimum conditions were as following: an anaerobic light, pH 7.0, temperature 30 degrees C, illumination intensity 4000 lx,initial o-chlorophenol concentration 50 mg/L. Under that cultural condition, the degradation rate of o-chlorophenol could reach to 62.08%. The degradation kinetic data fitted the Andrews model well. In addition, the biodegradation process of o-chlorophenol can be well described by enzymatic reaction of high concentration inhibition, with the maximum substrate utilization rate 0.309 d(-1), Michaelis-Menten constant 2.733 mg/L, inhibitory constant 230.15 mg/L respectively.

Reversible adsorption of catalase onto Fe(3+) chelated poly(AAm-GMA)-IDA cryogels.

PubMed

Aktaş Uygun, Deniz; Uygun, Murat; Akgöl, Sinan; Denizli, Adil

2015-05-01

In this presented study, poly(acrylamide-glycidyl methacrylate) [poly(AAm-GMA)] cryogels were synthesized by cryopolymerization technique at sub-zero temperature. Prepared cryogels were then functionalized with iminodiacetic acid (IDA) and chelated with Fe(3+) ions in order produce the metal chelate affinity matrix. Synthesized cryogels were characterized with FTIR, ESEM and EDX analysis, and it was found that the cryogel had sponge like structure with interconnected pores and their pore diameter was about 200 μm. Fe(3+) chelated poly(AAm-GMA)-IDA cryogels were used for the adsorption of catalase and optimum adsorption conditions were determined by varying the medium pH, initial catalase concentration, temperature and ionic strength. Maximum catalase adsorption onto Fe(3+) chelated poly(AAm-GMA)-IDA cryogel was found to be 12.99 mg/g cryogel at 25 °C, by using pH 5.0 acetate buffer. Adsorbed catalase was removed from the cryogel by using 1.0M of NaCl solution and desorption yield was found to be 96%. Additionally, reusability profile of the Fe(3+) chelated poly(AAm-GMA)-IDA cryogel was also investigated and it was found that, adsorption capacity of the cryogels didn't decrease significantly at the end of the 40 reuses. Catalase activity studies were also tested and it was demonstrated that desorbed catalase retained 70% of its initial activity. Copyright © 2015 Elsevier B.V. All rights reserved.

The removal of uranium (VI) from aqueous solutions onto activated carbon developed from grinded used tire.

PubMed

Belgacem, Ahmed; Rebiai, Rachid; Hadoun, Hocine; Khemaissia, Sihem; Belmedani, Mohamed

2014-01-01

In this study, activated carbon was prepared from waste tire by KOH chemical activation. The pore properties including the BET surface area, pore volume, pore size distribution, and average pore diameter were characterized. BET surface area of the activated carbon was determined as 558 m(2)/g. The adsorption of uranium ions from the aqueous solution using this activated carbon has been investigated. Various physico-chemical parameters such as pH, initial metal ion concentration, and adsorbent dosage level and equilibrium contact time were studied by a batch method. The optimum pH for adsorption was found to be 3. The removal efficiency has also been determined for the adsorption system as a function of initial concentration. The experimental results were fitted to Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherm models. A comparison of best-fitting was performed using the coefficient of correlation and the Langmuir isotherm was found to well represent the measured sorption data. According to the evaluation using the Langmuir equation, the saturated monolayer sorption capacity of uranium ions onto waste tire activated carbon was 158.73 mg/g. The thermodynamic equilibrium constant and the Gibbs free energy were determined and results indicated the spontaneous nature of the adsorption process. Kinetics data were best described by pseudo-second-order model.

Stability of thermostable alkaline protease from Bacillus licheniformis RP1 in commercial solid laundry detergent formulations.

PubMed

Sellami-Kamoun, Alya; Haddar, Anissa; Ali, Nedra El-Hadj; Ghorbel-Frikha, Basma; Kanoun, Safia; Nasri, Moncef

2008-01-01

The stability of crude extracellular protease produced by Bacillus licheniformis RP1, isolated from polluted water, in various solid laundry detergents was investigated. The enzyme had an optimum pH and temperature at pH 10.0-11.0 and 65-70 degrees C. Enzyme activity was inhibited by PMSF, suggesting that the preparation contains a serine-protease. The alkaline protease showed extreme stability towards non-ionic (5% Tween 20% and 5% Triton X-100) and anionic (0.5% SDS) surfactants, which retained 100% and above 73%, respectively, of its initial activity after preincubation 60 min at 40 degrees C. The RP1 protease showed excellent stability and compatibility with a wide range of commercial solid detergents at temperatures from 40 to 50 degrees C, suggesting its further application in detergent industry. The enzyme retained 95% of its initial activity with Ariel followed by Axion (94%) then Dixan (93.5%) after preincubation 60 min at 40 degrees C in the presence of 7 mg/ml of detergents. In the presence of Nadhif and New Det, the enzyme retained about 83.5% of the original activity. The effects of additives such as maltodextrin, sucrose and PEG 4000 on the stability of the enzyme during spray-drying and during subsequent storage in New Det detergent were also examined. All additives tested enhanced stability of the enzyme.

Response surface modeling of boron adsorption from aqueous solution by vermiculite using different adsorption agents: Box-Behnken experimental design.

PubMed

Demirçivi, Pelin; Saygılı, Gülhayat Nasün

2017-07-01

In this study, a different method was applied for boron removal by using vermiculite as the adsorbent. Vermiculite, which was used in the experiments, was not modified with adsorption agents before boron adsorption using a separate process. Hexadecyltrimethylammonium bromide (HDTMA) and Gallic acid (GA) were used as adsorption agents for vermiculite by maintaining the solid/liquid ratio at 12.5 g/L. HDTMA/GA concentration, contact time, pH, initial boron concentration, inert electrolyte and temperature effects on boron adsorption were analyzed. A three-factor, three-level Box-Behnken design model combined with response surface method (RSM) was employed to examine and optimize process variables for boron adsorption from aqueous solution by vermiculite using HDTMA and GA. Solution pH (2-12), temperature (25-60 °C) and initial boron concentration (50-8,000 mg/L) were chosen as independent variables and coded x 1 , x 2 and x 3 at three levels (-1, 0 and 1). Analysis of variance was used to test the significance of variables and their interactions with 95% confidence limit (α = 0.05). According to the regression coefficients, a second-order empirical equation was evaluated between the adsorption capacity (q i ) and the coded variables tested (x i ). Optimum values of the variables were also evaluated for maximum boron adsorption by vermiculite-HDTMA (HDTMA-Verm) and vermiculite-GA (GA-Verm).

Thermodynamic and kinetic studies of biosorption of iron and manganese from aqueous medium using rice husk ash

NASA Astrophysics Data System (ADS)

Adekola, F. A.; Hodonou, D. S. S.; Adegoke, H. I.

2016-11-01

The adsorption behavior of rice husk ash with respect to manganese and iron has been studied by batch methods to consider its application for water and waste water treatment. The optimum conditions of adsorption were determined by investigating the effect of initial metal ion concentration, contact time, adsorbent dose, pH value of aqueous solution and temperature. Adsorption equilibrium time was observed at 120 min. The adsorption efficiencies were found to be pH dependent. The equilibrium adsorption experimental data were found to fit the Langmuir, Freundlich and Temkin isotherms for iron, but fitted only Langmuir isotherm for manganese. The pseudo-second order kinetic model was found to describe the manganese and iron kinetics more effectively. The thermodynamic experiment revealed that the adsorption processes involving both metals were exothermic. The adsorbent was finally applied to typical raw water with initial manganese and iron concentrations of 3.38 mg/l for Fe and 6.28 mg/l, respectively, and the removal efficiency was 100 % for Mn and 70 % for Fe. The metal ions were desorbed from the adsorbent using 0.01 M HCl, it was found to quantitatively remove 67 and 86 % of Mn and Fe, respectively, within 2 h. The results revealed that manganese and iron are considerably adsorbed on the adsorbent and could be an economic method for the removal of these metals from aqueous solutions.

Response surface method optimization of ectoine fermentation medium with moderate halophilic bacteria Halomonas sp. H02

NASA Astrophysics Data System (ADS)

Li, T. T.; Qu, A.; Yuan, X. N.; Tan, F. X.; Li, X. W.; Wang, T.; Zhang, L. H.

2017-07-01

Moderate halophilic bacteria are of halophilic bacteria whose suitable growth of NaCl is 5-10%. When the moderate halophilic bacteria response to high osmotic stress, the intracellular will synthesize small organic molecule compatible solutes. Ectoine, which is the major synthetic osmotic compatible solutes for moderate halophilic bacteria, can help microbial enzymes, nucleic acids and the whole cell resist to hypertonic, high temperature, freezing and other inverse environment. In order to increase the Ectoine production of Moderate halophilic bacteria Halomonas sp. H02, the Ectoine fermentation medium component was optimized by Plackett-Burman (PB) and Response Surface Methodology (RSM) based on the principle of non-complete equilibrium The results of PB experiments showed that the three main influencing factors of Moderate halophilic bacteria Halomonas sp. H02 synthesis Ectoine culture medium were C5H8NNaO4 concentration, NaCl concentration and initial pH. According to the center point of the steepest climbing experiment, the central combination design experiment was used to show that the model is consistent with the actual situation. The optimum combination of three influencing factors were C5H8NNaO4 41 g/L, NaCl 87.2 g/L and initial pH 5.9, and the predicted amount of Ectoine was 1835.8 mg/L, increased by 41.6%.

Nickel(II) biosorption by Rhodotorula glutinis.

PubMed

Suazo-Madrid, Alicia; Morales-Barrera, Liliana; Aranda-García, Erick; Cristiani-Urbina, Eliseo

2011-01-01

The present study reports the feasibility of using Rhodotorula glutinis biomass as an alternative low-cost biosorbent to remove Ni(II) ions from aqueous solutions. Acetone-pretreated R. glutinis cells showed higher Ni(II) biosorption capacity than untreated cells at pH values ranging from 3 to 7.5, with an optimum pH of 7.5. The effects of other relevant environmental parameters, such as initial Ni(II) concentration, shaking contact time and temperature, on Ni(II) biosorption onto acetone-pretreated R. glutinis were evaluated. Significant enhancement of Ni(II) biosorption capacity was observed by increasing initial metal concentration and temperature. Kinetic studies showed that the kinetic data were best described by a pseudo-second-order kinetic model. Among the two-, three-, and four-parameter isotherm models tested, the Fritz-Schluender model exhibited the best fit to experimental data. Thermodynamic parameters (activation energy, and changes in activation enthalpy, activation entropy, and free energy of activation) revealed that the biosorption of Ni(II) ions onto acetone-pretreated R. glutinis biomass is an endothermic and non-spontaneous process, involving chemical sorption with weak interactions between the biosorbent and Ni(II) ions. The high sorption capacity (44.45 mg g(-1) at 25°C, and 63.53 mg g(-1) at 70°C) exhibited by acetone-pretreated R. glutinis biomass places this biosorbent among the best adsorbents currently available for removal of Ni(II) ions from aqueous effluents.

Application of a mixed culture of adapted acidophilic bacteria in two-step bioleaching of spent lithium-ion laptop batteries

NASA Astrophysics Data System (ADS)

Heydarian, Ahmad; Mousavi, Seyyed Mohammad; Vakilchap, Farzane; Baniasadi, Mahsa

2018-02-01

The rapid increase in the production of electrical and electronic equipment, along with higher consumption of these products, has caused defective and obsolete equipment to accumulate in the environment. In this research, bioleaching of spent lithium-ion batteries (LIBs) used in laptops is carried out under two-step condition based on the bacterial activities of a mixture of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. First, the best inoculum ratio of two acidophilic bacteria for the mixed culture is obtained. Next, adaptation is carried out successfully and the solid-to-liquid ratio reaches 40 g L-1. Response surface methodology is utilized to optimize the effective variables of initial pH, iron sulfate and sulfur concentrations. The maximum recovery of metal is about 99.2% for Li, 50.4% for Co and 89.4% for Ni under optimum conditions of 36.7 g L-1 iron sulfate concentration, 5.0 g L-1 sulfur concentration and initial pH of 1.5 for the best inoculum ratio of 3/2. Results of FE-SEM, XRD and FTIR analysis before and after bioleaching confirm that bacterial activity is a promising and effective route for metal recovery from spent LIBs. Toxicity assessment tests demonstrate the suitability of the bioleached residual as a nonhazardous material that meets environmental limitations for safe disposal.

Anaerobic treatment of blended sugar industry and ethanol distillery wastewater through biphasic high rate reactor.

PubMed

Fito, Jemal; Tefera, Nurelegne; Kloos, Helmut; Van Hulle, Stijn W H

2018-06-07

This study aimed to investigate the physicochemical properties of sugar industry and ethanol distillery wastewater and the treatment of the blended wastewater through a two-stage anaerobic reactor. For this treatment, different initial chemical oxygen demand (COD) concentrations (5-20 g/L) and hydraulic retention times (HRTs) (2-10 days) were applied. The sugar industry effluent characteristics obtained in terms of organic matter (mg/L) were as follows: 5 days biochemical oxygen demand (BOD 5 ): 654.5-1,968; COD: 1,100-2,148.9; total solids (TS): 2,467-4,012 mg/L; and pH: 6.93-8.43. The ethanol distillery spent wash strengths obtained were: BOD 5 : 27,600-42,921 mg/L; COD: 126,000-167,534 mg/L; TS: 140,160-170,000 mg/L; and pH: 3.9-4.2. Maximum COD removal of 65% was obtained at optimum condition (initial COD concentration of 10 g/L and HRT of 10 days), and maximum color removal of 79% was recorded under similar treatment conditions. Hence, the performance of the two-stage anaerobic reactor for simultaneous removal of COD and color from high-strength blended wastewater is promising for scaling up in order to mitigate environmental problems of untreated effluent discharge.

Removal of Crystal Violet by Using Reduced-Graphene-Oxide-Supported Bimetallic Fe/Ni Nanoparticles (rGO/Fe/Ni): Application of Artificial Intelligence Modeling for the Optimization Process.

PubMed

Ruan, Wenqian; Hu, Jiwei; Qi, Jimei; Hou, Yu; Cao, Rensheng; Wei, Xionghui

2018-05-22

Reduced-graphene-oxide-supported bimetallic Fe/Ni nanoparticles were synthesized in this study for the removal of crystal violet (CV) dye from aqueous solutions. This material was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS), Raman spectroscopy, N₂-sorption, and X-ray photoelectron spectroscopy (XPS). The influence of independent parameters (namely, initial dye concentration, initial pH, contact time, and temperature) on the removal efficiency were investigated via Box⁻Behnken design (BBD). Artificial intelligence (i.e., artificial neural network, genetic algorithm, and particle swarm optimization) was used to optimize and predict the optimum conditions and obtain the maximum removal efficiency. The zero point of charge (pH ZPC ) of rGO/Fe/Ni composites was determined by using the salt addition method. The experimental equilibrium data were fitted well to the Freundlich model for the evaluation of the actual behavior of CV adsorption, and the maximum adsorption capacity was estimated as 2000.00 mg/g. The kinetic study discloses that the adsorption processes can be satisfactorily described by the pseudo-second-order model. The values of Gibbs free energy change (Δ G ⁰), entropy change (Δ S ⁰), and enthalpy change (Δ H ⁰) demonstrate the spontaneous and endothermic nature of the adsorption of CV onto rGO/Fe/Ni composites.

Immobilization and characterization of tannase from a metagenomic library and its use for removal of tannins from green tea infusion.

PubMed

Yao, Jian; Chen, Qinglong; Zhong, Guoxiang; Cao, Wen; Yu, An; Liu, Yuhuan

2014-01-01

Tannase (Tan410) from a soil metagenomic library was immobilized on different supports, including mesoporous silica SBA-15, chitosan, calcium alginate, and amberlite IRC 50. Entrapment in calcium alginate beads was comparatively found to be the best method and was further characterized. The optimum pH of the immobilized Tan410 was shifted toward neutrality compared with the free enzyme (from pH 6.4 to pH 7.0). The optimum temperature was determined to be 45°C for the immobilized enzyme and 30°C for the free enzyme, respectively. The immobilized enzyme had no loss of activity after 10 cycles, and retained more than 90% of its original activity after storage for 30 days. After immobilization, the enzyme activity was only slightly affected by Hg(2+), which completely inhibited the activity of the free enzyme. The immobilized tannase was used to remove 80% of tannins from a green tea infusion on the first treatment. The beads were used for six successive runs resulting in overall hydrolysis of 56% of the tannins.

Statistical key factors optimization of conditions for hydrogen production from S-TE (solubilization by thermophilic enzyme) waste sludge.

PubMed

Guo, Liang; Zhao, Jun; She, Zonglian; Lu, Mingmin; Zong, Yan

2013-06-01

Waste sludge can be solubilized after S-TE (solubilization by thermophilic enzyme) pretreatment as the cryptic growth occurs at the expense of the cell lysate. The hydrogen production from S-TE sludge is greatly influenced by many factors. In this study, factors including pH, C/N, C/P, and Fe(2+) affecting hydrogen production from S-TE sludge were optimized using uniform design. The optimum condition for maximum hydrogen yield of 68.4 ml H2/g VSS (volatile suspended solid) could be predicted from regression model, and the optimum conditions were pH of 6.4, C/N ratio of 38, C/P ratio of 265, and Fe(2+) concentration of 85 mg/L. There was interaction effect of factors on hydrogen production from S-TE sludge. Different pH, C/N, C/P and Fe(2+) conditions could influence the VSS removal rate, carbohydrate and protein utilization. When the highest compositions of acetate and ethanol and lowest propionate were observed in metabolites, effective hydrogen production was also achieved. Copyright © 2013 Elsevier Ltd. All rights reserved.

Using Chitosan/CHPATC as coagulant to remove color and turbidity of industrial wastewater: Optimization through RSM design.

PubMed

Momeni, Meysam Mohammad; Kahforoushan, Davood; Abbasi, Farhang; Ghanbarian, Saeid

2018-04-01

One of the most important solid-liquid separation processes is coagulation and flocculation that is extensively used in the primary treatment of industrial wastewater. The biopolymers, because of biodegradable properties and low cost have been used as coagulants. In this study, chitosan as a natural coagulant of choice, was modified by (3-chloro 2-hydroxypropyl)trimethylammonium chloride and was used to remove the color and turbidity of industrial wastewater. To evaluate the effect of pH, settling time, the initial turbidity of wastewater, the amount of coagulant, and the concentration of dye (Melanoidin) were chosen to study their effects on removal of wastewater color and turbidity. The experiments were done in a batch system by using a jar test. To achieve the optimum conditions for the removal of color and turbidity, the response surface methodology (RSM) experimental design method was used. The results obtained from experiments showed that the optimum conditions for the removal of color were as: pH = 3, concentration of dye = 1000 mg/L, settling time = 78.93 min, and dose of coagulant = 3 g/L. The maximum color removal in these conditions was predicted 82.78% by the RSM model. The optimal conditions for the removal of turbidity of the waste water were as: pH = 5.66, initial turbidity = 60 NTU, settling time = 105 min, and amount of coagulant = 3 g/L. The maximum turbidity removal in these circumstances was predicted 94.19% by the model. The experimental results obtained in optimum conditions for removal of color and turbidity were 76.20% and 90.14%, respectively, indicating the high accuracy of the prediction model. Copyright © 2018 Elsevier Ltd. All rights reserved.

High Aflatoxin Production on a Chemically Defined Medium 1

PubMed Central

Reddy, T. V.; Viswanathan, L.; Venkitasubramanian, T. A.

1971-01-01

Aspergillus parasiticus ATCC 15517 produced 28 to 30 mg of aflatoxin per 100 ml of a medium containing sucrose, asparagine, and salts in stationary and shaken cultures. In the absence of asparagine in the medium, the toxin yields fell drastically, and the thin-layer chromatograms of the chloroform extracts of the cultures indicated the total absence of aflatoxin G1 and the presence of new intense blue and green fluorescent bands having RF values lower than aflatoxins. Initial pH was critical and had to be around 4.5 for good growth and high toxin production on this medium. Optimum concentrations of KH2PO4 and MgSO4·7H2O in the medium were much lower than those normally used in fungal growth media. PMID:5119206

Fuel alcohol biosynthesis by Zymomonas anaerobia: optimization studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kosaric, N.; Ong, S.L.; Davnjak, Z.

1982-03-01

The optimum operating conditions for growth and ethanol production of Zymomonas anaerobia ATCC 29501 were established. The optimum pH range and temperature were found to be 5.0-6.0 and 35/sup 0/C, respectively. Based on the results obtained from the temperature optimization study, an Arrhenius-type temperature relationship for the specific growth rate was developed. The growth and ethanol production of this microbe also have been optimized in terms of concentrations of glucose, essential nutrients, and minerals. With optimum medium and operating conditions, an ethanol concentration of 96 g/L was obtained in 23h. Both growth and ethanol yield coefficients in dependence on initialmore » glucose concentrations were determined.« less

Organic solvent tolerance of an α-amylase from haloalkaliphilic bacteria as a function of pH, temperature, and salt concentrations.

PubMed

Pandey, Sandeep; Singh, S P

2012-04-01

A haloalkaliphilic bacterium was isolated from salt-enriched soil of Mithapur, Gujarat (India) and identified as Bacillus agaradhaerens Mi-10-6₂ based on 16S rRNA sequence analysis (NCBI gene bank accession, GQ121032). The bacterium was studied for its α-amylase characteristic in the presence of organic solvents. The enzyme was quite active and it retained considerable activity in 30% (v/v) organic solvents, dodecane, decane, heptane, n-hexane, methanol, and propanol. At lower concentrations of solvents, the catalysis was quite comparable to control. Enzyme catalysis at wide range of alkanes and alcohol was an interesting finding of the study. Mi-10-6₂ amylase retained activity over a broader alkaline pH range, with the optimal pH at 10-11. Two molars of salt was optimum for catalysis in the presence of most of the tested solvents, though the enzyme retained significant activity even at 4 M salt. With dodecane, the optimum temperature shifted from 50 °C to 60 °C, while the enzyme was active up to 80 °C. Over all, the present study focused on the effect of organic solvents on an extracellular α-amylase from haloalkaliphilic bacteria under varying conditions of pH, temperature, and salt.

A sacrificial millipede altruistically protects its swarm using a drone blood enzyme, mandelonitrile oxidase

PubMed Central

Ishida, Yuko; Kuwahara, Yasumasa; Dadashipour, Mohammad; Ina, Atsutoshi; Yamaguchi, Takuya; Morita, Masashi; Ichiki, Yayoi; Asano, Yasuhisa

2016-01-01

Soldiers of some eusocial insects exhibit an altruistic self-destructive defense behavior in emergency situations when attacked by large enemies. The swarm-forming invasive millipede, Chamberlinius hualienensis, which is not classified as eusocial animal, exudes irritant chemicals such as benzoyl cyanide as a defensive secretion. Although it has been thought that this defensive chemical was converted from mandelonitrile, identification of the biocatalyst has remained unidentified for 40 years. Here, we identify the novel blood enzyme, mandelonitrile oxidase (ChuaMOX), which stoichiometrically catalyzes oxygen consumption and synthesis of benzoyl cyanide and hydrogen peroxide from mandelonitrile. Interestingly the enzymatic activity is suppressed at a blood pH of 7, and the enzyme is segregated by membranes of defensive sacs from mandelonitrile which has a pH of 4.6, the optimum pH for ChuaMOX activity. In addition, strong body muscle contractions are necessary for de novo synthesis of benzoyl cyanide. We propose that, to protect its swarm, the sacrificial millipede also applies a self-destructive defense strategy—the endogenous rupturing of the defensive sacs to mix ChuaMOX and mandelonitrile at an optimum pH. Further study of defensive systems in primitive arthropods will pave the way to elucidate the evolution of altruistic defenses in the animal kingdom. PMID:27265180

Ebselen is a dehydroascorbate reductase mimic, facilitating the recycling of ascorbate via mammalian thioredoxin systems.

PubMed

Zhao, Rong; Holmgren, Arne

2004-02-01

Ebselen is a selanazal drug recently revealed as a highly efficient peroxiredoxin mimic catalyzing the hydroperoxide reduction by the mammalian thioredoxin system [thioredoxin (Trx), thioredoxin reductase (TrxR), and NADPH]. The mammalian Trx system is a dehydroascorbic acid reductase recycling ascorbic acid essential for cell functions. Here we report that ebselen strongly facilitated the recycling of ascorbic acid by the TrxR both with and without Trx present. Reduction of dehydroascorbic acid by TrxR has a pH optimum of 6.4, and only approximately 55% of this activity at a physiological pH of 7.4. Ebselen at 6 microM enhances this reaction three-fold and with the same pH optimum of 6.4. The mechanism of the ebselen effect is suggested to involve reduction of dehydroascorbic acid by the ebselen selenol, a highly efficient two-electron reductant. Thus, ebselen acts as an antioxidant to lower the peroxide tone inside cells and to facilitate the recycling of dehydroascorbic acid to ascorbic acid, so as to increase the radical scavenging capacity of ascorbic acid directly or indirectly via vitamin E. The high ascorbic acid recycling efficiency of ebselen at pH 6.4 may play a major role in oxidatively stressed cells, where cytosol acidosis may trigger various responses, including apoptosis.

Biochemical Evaluation of Phenylalanine Ammonia Lyase from Endemic Plant Cyathobasis fruticulosa (Bunge) Aellen. for the Dietary Treatment of Phenylketonuria

PubMed Central

Aydaş, Selcen Babaoğlu; Aslım, Belma

2016-01-01

Summary Enzyme substitution therapy with the phenylalanine ammonia lyase (PAL) is a new approach to the treatment of patients with phenylketonuria (PKU). This enzyme is responsible for the conversion of phenylalanine to trans-cinnamic acid. We assessed the PAL enzyme of the endemic plant Cyathobasis fruticulosa (Bunge) Aellen. for its possible role in the dietary treatment of PKU. The enzyme was found to have a high activity of (64.9±0.1) U/mg, with the optimum pH, temperature and buffer (Tris–HCl and l-phenylalanine) concentration levels of pH=8.8, 37 °C and 100 mM, respectively. Optimum enzyme activity was achieved at pH=4.0 and 7.5, corresponding to pH levels of gastric and intestinal juice, and NaCl concentration of 200 mM. The purification of the enzyme by 1.87-fold yielded an activity of 98.6 U/mg. PAL activities determined by HPLC analyses before and after purification were similar. Two protein bands, one at 70 and the other at 23 kDa, were determined by Western blot analysis of the enzyme. This enzyme is a potential candidate for serial production of dietary food and biotechnological products. PMID:27956861

A sacrificial millipede altruistically protects its swarm using a drone blood enzyme, mandelonitrile oxidase.

PubMed

Ishida, Yuko; Kuwahara, Yasumasa; Dadashipour, Mohammad; Ina, Atsutoshi; Yamaguchi, Takuya; Morita, Masashi; Ichiki, Yayoi; Asano, Yasuhisa

2016-06-06

Soldiers of some eusocial insects exhibit an altruistic self-destructive defense behavior in emergency situations when attacked by large enemies. The swarm-forming invasive millipede, Chamberlinius hualienensis, which is not classified as eusocial animal, exudes irritant chemicals such as benzoyl cyanide as a defensive secretion. Although it has been thought that this defensive chemical was converted from mandelonitrile, identification of the biocatalyst has remained unidentified for 40 years. Here, we identify the novel blood enzyme, mandelonitrile oxidase (ChuaMOX), which stoichiometrically catalyzes oxygen consumption and synthesis of benzoyl cyanide and hydrogen peroxide from mandelonitrile. Interestingly the enzymatic activity is suppressed at a blood pH of 7, and the enzyme is segregated by membranes of defensive sacs from mandelonitrile which has a pH of 4.6, the optimum pH for ChuaMOX activity. In addition, strong body muscle contractions are necessary for de novo synthesis of benzoyl cyanide. We propose that, to protect its swarm, the sacrificial millipede also applies a self-destructive defense strategy-the endogenous rupturing of the defensive sacs to mix ChuaMOX and mandelonitrile at an optimum pH. Further study of defensive systems in primitive arthropods will pave the way to elucidate the evolution of altruistic defenses in the animal kingdom.

A Novel Phytase Derived from an Acidic Peat-Soil Microbiome Showing High Stability under Acidic Plus Pepsin Conditions.

PubMed

Tan, Hao; Wu, Xiang; Xie, Liyuan; Huang, Zhongqian; Peng, Weihong; Gan, Bingcheng

2016-01-01

Four novel phytases of the histidine acid phosphatase family were identified in two publicly available metagenomic datasets of an acidic peat-soil microbiome in northeastern Bavaria, Germany. These enzymes have low similarity to all the reported phytases. They were overexpressed in Escherichia coli and purified. Catalytic efficacy in simulated gastric fluid was measured and compared among the four candidates. The phytase named rPhyPt4 was selected for its high activity. It is the first phytase identified from unculturable Acidobacteria. The phytase showed a longer half-life than all the gastric-stable phytases that have been reported to date, suggesting a strong resistance to low pH and pepsin. A wide pH profile was observed between pH 1.5 and 5.0. At the optimum pH (2.5) the activity was 2,790 μmol/min/mg at the physiological temperature of 37°C and 3,989 μmol/min/mg at the optimum temperature of 60°C. Due to the competent activity level as well as the high gastric stability, the phytase could be a potential candidate for practical use in livestock and poultry feeding. © 2016 S. Karger AG, Basel.

Effects of ultraviolet light on biogenic amines and other quality indicators of chicken meat during refrigerated storage.

PubMed

Lázaro, C A; Conte-Júnior, C A; Monteiro, M L G; Canto, A C V S; Costa-Lima, B R C; Mano, S B; Franco, R M

2014-09-01

Radiation from UV-C has been demonstrated as a potential surface decontamination method in addition to several advantages over regular sanitation methods. However, UV-C radiation possibly affects the physicochemical properties of meat products. To determine the optimum exposure time for bacterial reduction, 39 chicken breasts, inoculated with a pool of Salmonella spp., were submitted to 3 levels of UV-C intensities (0.62, 1.13, and 1.95 mW/cm²) for up to 120 s. After the optimum exposure time of 90 s was determined, changes in the biogenic amines, total aerobic mesophilic bacteria, Enterobacteriaceae, lipid oxidation, pH, and instrumental color were evaluated in 84 chicken breasts that were irradiated (0.62, 1.13, and 1.95 mW/cm²) and stored at 4°C for 9 d. The groups treated with UV-C radiation exhibited an increase in tyramine, cadaverine, and putrescine contents (P < 0.05). The highest UV-C intensity (1.95 mW/cm²) promoted a decrease in the initial bacterial load, and extended the lag phase and the shelf life. The groups irradiated with 1.13 and 1.95 mW/cm² exhibited a more stable b* value than the other groups; similar trends for L*, a*, pH, and TBA reactive substance values were observed among all groups. The UV-C light was demonstrated to be an efficient alternative technology to improve the bacteriological quality of chicken meat without negatively affecting the physical and chemical parameters of chicken breast meat. Nonetheless, the increases on the biogenic amines content should be considered as an effect of the UV processing and not as an indicator of bacterial growth. © 2014 Poultry Science Association Inc.

Simultaneous spectrophotometric determination of synthetic dyes in food samples after cloud point extraction using multiple response optimizations.

PubMed

Heidarizadi, Elham; Tabaraki, Reza

2016-01-01

A sensitive cloud point extraction method for simultaneous determination of trace amounts of sunset yellow (SY), allura red (AR) and brilliant blue (BB) by spectrophotometry was developed. Experimental parameters such as Triton X-100 concentration, KCl concentration and initial pH on extraction efficiency of dyes were optimized using response surface methodology (RSM) with a Doehlert design. Experimental data were evaluated by applying RSM integrating a desirability function approach. The optimum condition for extraction efficiency of SY, AR and BB simultaneously were: Triton X-100 concentration 0.0635 mol L(-1), KCl concentration 0.11 mol L(-1) and pH 4 with maximum overall desirability D of 0.95. Correspondingly, the maximum extraction efficiency of SY, AR and BB were 100%, 92.23% and 95.69%, respectively. At optimal conditions, extraction efficiencies were 99.8%, 92.48% and 95.96% for SY, AR and BB, respectively. These values were only 0.2%, 0.25% and 0.27% different from the predicted values, suggesting that the desirability function approach with RSM was a useful technique for simultaneously dye extraction. Linear calibration curves were obtained in the range of 0.02-4 for SY, 0.025-2.5 for AR and 0.02-4 μg mL(-1) for BB under optimum condition. Detection limit based on three times the standard deviation of the blank (3Sb) was 0.009, 0.01 and 0.007 μg mL(-1) (n=10) for SY, AR and BB, respectively. The method was successfully used for the simultaneous determination of the dyes in different food samples. Copyright © 2015 Elsevier B.V. All rights reserved.

Experimental Research on the Sterilization of Escherichia Coli and Bacillus Subtilis in Drinking Water by Dielectric Barrier Discharge

NASA Astrophysics Data System (ADS)

Li, Yang; Yi, Chengwu; Li, Jingjing; Yi, Rongjie; Wang, Huijuan

2016-02-01

The bactericidal effect on the representative type of Gram-negative Escherichia coli (E. coli) and Gram-positive Bacillus subtilis in drinking water was investigated in this paper by using dielectric barrier discharge (DBD) advanced oxidation technology. The sterilizing rates under different conditions of reaction time t, input voltage V, pH value, and initial concentration of bacteria C0 were investigated to figure out the optimum sterilization conditions. Our observations and comparisons of cell morphology alteration by scanning electron microscopy and transmission electron microscopy revealed the sterilization mechanisms. The results showed that the sterilizing rate increased obviously with the extension of reaction time t and the rise of input voltage V. The optimal sterilization effect was achieved when the pH value was 7.1. As the initial concentration of bacteria rose, the sterilizing rate decreased. When the input voltage was 2.2 kV and the initial concentration of bacteria was relatively low, the sterilizing rate almost reached 100% after a certain treatment time in neutral aqueous solution. The reasons for the great damage of cell structure and the killing of bacteria are the oxidation of O3, OH and the accumulation of active species produced by DBD. The article provides a certain theoretical and experimental basis for DBD application in water pollution treatment. supported by the Science and Technology Support Project Plan and Social Development of Jiangsu Province, China (No. BE2011732), the Science and Technology Support Project Plan and Social Development of Zhenjiang, Jiangsu Province, China (No. SH2012013)

Photocatalytic degradation of diclofenac using TiO2-SnO2 mixed oxide catalysts.

PubMed

Mugunthan, E; Saidutta, M B; Jagadeeshbabu, P E

2017-12-26

The complex nature of diclofenac limits its biological degradation, posing a serious threat to aquatic organisms. Our present work aims to eliminate diclofenac from wastewater through photocatalytic degradation using TiO 2 -SnO 2 mixed-oxide catalysts under various operating conditions such as catalyst loading, initial diclofenac concentration and initial pH. Different molar ratios of Ti-Sn (1:1, 5:1, 10:1, 20:1 and 30:1) were prepared by the hydrothermal method and were characterized. The results indicated that addition of Sn in small quantity enhances the catalytic activity of TiO 2 . Energy Band gap of the TiO 2 -SnO 2 catalysts was found to increase with an increase in Tin content. TiO 2 -SnO 2 catalyst with a molar ratio of 20:1 was found to be the most effective when compared to other catalysts. The results suggested that initial drug concentration of 20 mg/L, catalyst loading of 0.8 g/L and pH 5 were the optimum operating conditions for complete degradation of diclofenac. Also, the TiO 2 -SnO 2 catalyst was effective in complete mineralization of diclofenac with a maximum total organic carbon removal of 90% achieved under ultraviolet irradiation. The repeatability and stability results showed that the TiO 2 -SnO 2 catalyst exhibited an excellent repeatability and better stability over the repeated reaction cycles. The photocatalytic degradation of diclofenac resulted in several photoproducts, which were identified through LC-MS.

Comparative study of humic acid removal and floc characteristics by electrocoagulation and chemical coagulation.

PubMed

Semerjian, Lucy; Damaj, Ahmad; Salam, Darine

2015-11-01

The current study aims at investigating the efficiency of electrocoagulation for the removal of humic acid from contaminated waters. In parallel, conventional chemical coagulation was conducted to asses humic acid removal patterns. The effect of varying contributing parameters (matrix pH, humic acid concentration, type of electrode (aluminum vs. iron), current density, solution conductivity, and distance between electrodes) was considered to optimize the electrocoagulation process for the best attainable humic acid removal efficiencies. Optimum removals were recorded at pH of 5.0-5.5, an electrical conductivity of 3000 μS/cm at 25 °C, and an electrode distance of 1 cm for both electrode types. With aluminum electrodes, a current density of 0.05 mA/cm2 outperformed 0.1 mA/cm2 yet not higher densities, whereas a current density of 0.8 mA/cm2 was needed for iron electrodes to exhibit comparable performance. With both electrode types, higher initial humic acid concentrations were removed at a slower rate but ultimately attained almost complete removals. On the other hand, the best humic acid removals (∼90%) by chemical coagulation were achieved at 4 mg/L for both coagulants. Also, higher removals were attained at elevated initial humic acid concentrations. Humic acid removals of 90% or higher at an initial HA concentration of 40 mg/L were exhibited, yet alum performed better at the highest experimented concentration. It was evident that iron flocs were larger, denser, and more geometrical in shape compared to aluminum flocs.

Synthesis and antimicrobial activity of gold nanoparticle conjugates with cefotaxime

NASA Astrophysics Data System (ADS)

Titanova, Elena O.; Burygin, Gennady L.

2016-04-01

Gold nanoparticles (GNPs) have attracted significant interest as a novel platform for various applications to nanobiotechnology and biomedicine. The conjugates of GNPs with antibiotics and antibodies were also used for selective photothermal killing of protozoa and bacteria. Also the conjugates of some antibiotics with GNPs decreased the number of bacterial growing cells. In this work was made the procedure optimization for conjugation of cefotaxime (a third-generation cephalosporin antibiotic) with GNPs (15 nm) and we examined the antimicrobial properties of this conjugate to bacteria culture of E. coli K-12. Addition of cefotaxime solution to colloidal gold does not change their color and extinction spectrum. For physiologically active concentration of cefotaxime (3 μg/mL), it was shown that the optimum pH for the conjugation was more than 9.5. A partial aggregation of the GNPs in saline medium was observed at pH 6.5-7.5. The optimum concentration of K2CO3 for conjugation cefotaxime with GNPs-15 was 5 mM. The optimum concentration of cefotaxime was at 0.36 μg/mL. We found the inhibition of the growth of E. coli K12 upon application cefotaxime-GNP conjugates.

Purification and characterization of peroxidase from cauliflower (Brassica oleracea L. var. botrytis) buds.

PubMed

Köksal, Ekrem; Gülçin, Ilhami

2008-01-01

Peroxidases (EC 1.11.1.7; donor: hydrogen peroxide oxidoreductase) are part of a large group of enzymes. In this study, peroxidase, a primer antioxidant enzyme, was purified with 19.3 fold and 0.2% efficiency from cauliflower (Brassica oleracea L.) by ammonium sulphate precipitation, dialysis, CM-Sephadex ion-exchange chromatography and Sephadex G-25 purification steps. The substrate specificity of peroxidase was investigated using 2,2'-azino-bis(3-ethylbenz-thiazoline-6-sulphonic acid) (ABTS), 2-methoxyphenol (guaiacol), 1,2-dihydroxybenzene (catechol), 1,2,3-trihyidroxybenzene (pyrogallol) and 4-methylcatechol. Also, optimum pH, optimum temperature, optimum ionic strength, stable pH, stable temperature, thermal inactivation conditions were determined for guaiacol/H(2)O(2), pyrogallol/H(2)O(2), ABTS/H(2)O(2), catechol/H(2)O(2) and 4-methyl catechol/H(2)O(2) substrate patterns. The molecular weight (M(w)) of this enzyme was found to be 44 kDa by gel filtration chromatography method. Native polyacrylamide gel electrophoresis (PAGE) was performed for isoenzyme determination and a single band was observed. K(m) and V(max) values were calculated from Lineweaver-Burk graph for each substrate patterns.

Removal of gallium (III) ions from acidic aqueous solution by supercritical carbon dioxide extraction in the green separation process.

PubMed

Chou, Wei-Lung; Wang, Chih-Ta; Yang, Kai-Chiang; Huang, Yen-Hsiang

2008-12-15

Supercritical carbon dioxide extraction, which is a feasible "green" alternative, was applied in this study as a sample pretreatment step for the removal of gallium (III) ions from acidic aqueous solution. The effect of various process parameters, including various chelating agents, extraction pressure and temperature, dimensionless CO(2) volume, the concentration of the chelating agent, and the pH of the solution, governing the efficiency and throughput of the procedure were systematically investigated. The performance of the various chelating agents from different studies indicated that the extraction efficiency of supercritical CO(2) was in the order: thiopyridine (PySH)>thenoyltrifluoroacetone (TTAH)>acetylacetone (AcAcH). The optimal extraction pressure and temperature for the supercritical CO(2) extraction of gallium (III) with chelating agent PySH were found to be 70 degrees C and 3000psi, respectively. The optimum concentration of the chelating agent was found to be 50ppm. A value of 7.5 was selected as the optimum dimensionless CO(2) volume. The optimum pH of the solution for supercritical CO(2) extraction should fall in the range of 2.0-3.0.

Identification and Characterization of a High Efficiency Aniline Resistance and Degrading Bacterium MC-01.

PubMed

Yang, Liu; Ying, Chen; Fang, Ni; Zhong, Yao; Zhao-Xiang, Zhong; Yun, Sun

2017-05-01

Biodegradation is one of the important methods for the treatment of industrial wastewater containing aniline. In this paper, a degrading bacterium named MC-01, which could survive in high concentration aniline wastewater, was screened from industrial wastewater containing aniline and sludge. MC-01 was preliminarily identified as Ochrobactrum sp. based on the amplified 16S rDNA gene sequence and Biolog system identification. MC-01 was highly resistant to aniline. After 24-h culture under aniline concentration of 6500 mg/L, the amount of bacterium survived still remained 0.05 × 10 6  CFU/mL. Experiments showed that there was no coupling expression between the growth of MC-01 and aniline degradation. The optimum growth conditions in LB culture were pH 6.0, 30 °C of temperature, and 4% of incubation amount, respectively. And the optimum conditions of aniline degradation of MC-01 were pH 7.0, 45 °C of temperature, and 3.0% of salt concentration, respectively. The degradation rate of MC-01 (48 h) in different aniline concentrations (200~1600 mg/L) was stable under the optimum conditions, which could reach more than 75%.

Kinetic approach to the study of froth flotation applied to a lepidolite ore

NASA Astrophysics Data System (ADS)

Vieceli, Nathália; Durão, Fernando O.; Guimarães, Carlos; Nogueira, Carlos A.; Pereira, Manuel F. C.; Margarido, Fernanda

2016-07-01

The number of published studies related to the optimization of lithium extraction from low-grade ores has increased as the demand for lithium has grown. However, no study related to the kinetics of the concentration stage of lithium-containing minerals by froth flotation has yet been reported. To establish a factorial design of batch flotation experiments, we conducted a set of kinetic tests to determine the most selective alternative collector, define a range of pulp pH values, and estimate a near-optimum flotation time. Both collectors (Aeromine 3000C and Armeen 12D) provided the required flotation selectivity, although this selectivity was lost in the case of pulp pH values outside the range between 2 and 4. Cumulative mineral recovery curves were used to adjust a classical kinetic model that was modified with a non-negative parameter representing a delay time. The computation of the near-optimum flotation time as the maximizer of a separation efficiency (SE) function must be performed with caution. We instead propose to define the near-optimum flotation time as the time interval required to achieve 95%-99% of the maximum value of the SE function.

Optimum conditions for detecting hepatic micronuclei caused by numerical chromosome aberration inducers in mice.

PubMed

Igarashi, Miyuki; Setoguchi, Mayumi; Takada, Sanae; Itoh, Satoru; Furuhama, Kazuhisa

2007-08-15

To ascertain an optimum condition for detecting micronuclei in the liver caused by numerical aberration inducers, either carbendazim (125-1000mg/kg, p.o.), colchicine (0.375-1.5mg/kg, i.v.), cytochalasin B (2.5-20mg/kg, i.v.), diazepam (3.13-25mg/kg, i.v.), noscapine (7.8-62.5mg/kg, i.v.), paclitaxel (1-100mg/kg, i.v.) or trichlorfon (18.75-150mg/kg, i.v.) was administered once to male Slc:ddY mice 1 day before or after partial hepatectomy (PH, Day 1). Five days after PH (on Day 6), hepatic micronuclei were determined in conjunction with classifications of the main nuclei and relative liver weights as a proliferative indicator or a dysfunction marker of cell division. Additionally, hepatocyte proliferation index (HPI) was calculated by using mono-, bi- and multinucleated cell counts. Treatment of mice with six compounds, except for colchicine, after PH showed higher incidence of micronucleated hepatocytes (MNH) than that before PH, and also increases in binucleated and multinucleated cells. Especially for carbendazim, diazepam, noscapine and trichlorfon, the dosing after PH was essential for the detecting numerical aberration. Colchicine evidently increased HPI and decreased relative liver weights without MNH induction on Day 6. On Day 8 when HPI and relative liver weights almost returned to the basal range, a significant increase in MNH was noted. This implied that the strong inhibition of colchicine on hepatocyte proliferation may obstruct the induction of MNH on Day 6. In conclusion, to detect the potential numerical aberration, exposure of mice to test chemicals should be performed 1 day after PH, during which enhanced proliferation of hepatocytes was seen, and it would be better to analyze the liver specimens on Day 6 or more post-PH.

Roof-harvested rainwater for potable purposes: application of solar disinfection (SODIS) and limitations.

PubMed

Amin, Muhammad Tahir; Han, Mooyoung

2009-01-01

Efficiency of solar disinfection (SODIS) was evaluated for the potability of rainwater in view of the increasing water and energy crises especially in developing countries. Rainwater samples were collected from an underground storage tank in 2 L polyethylene terephthalate (PET) bottles and SODIS efficiency was evaluated at different weather conditions. For optimizing SODIS, PET bottles with different backing surfaces to enhance the optical and thermal effects of SODIS were used and different physicochemical parameters were selected and evaluated along with microbial re-growth observations and calculating microbial decay constants. Total and fecal coliforms were used along with Escherichia Coli and Heterotrophic Plate Counts (HPC) as basic microbial and indicator organisms of water quality. For irradiance less than 600 W/m(2), reflective type PET bottles were best types while for radiations greater than 700 W/m(2), absorptive type PET bottles offered best solution due to the synergistic effects of both thermal and UV radiations. Microbial inactivation did not improve significantly by changing the initial pH and turbidity values but optimum SODIS efficiency is achieved for rainwater with acidic pH and low initial turbidity values by keeping air-spaced PET bottles in undisturbed conditions. Microbial re-growth occurred after one day only at higher turbidity values and with basic pH values. First-order reaction rate constant was in accordance with recent findings for TC but contradicted with previous researches for E. coli. No microbial parameter met drinking water guidelines even under strong experimental weather conditions rendering SODIS ineffective for complete disinfection and hence needed more exposure time or stronger sunlight radiations. With maximum possible storage of rainwater, however, and by using some means for accelerating SODIS process, rainwater can be disinfected and used for potable purposes.

A study of Reactive Red 198 adsorption on iron filings from aqueous solutions.

PubMed

Azhdarpoor, Abooalfazl; Nikmanesh, Roya; Khademi, Fahime

2014-01-01

In recent years, reactive dyes have been widely used in textile industries with particular efficiency. They dyes are often toxic, carcinogenic and mutagenic. Improper treatment and non-scientific disposal of dyed wastewater from these industries into water sources has created many environmental problems and concerns around the world. The purpose of the present study is to investigate the efficiency of iron filings in adsorption of Reactive Red 198 from aqueous solutions. This study was conducted using an experimental method at the laboratory scale. In this study, the effects of operating parameters such as pH (1-11), initial dye concentration (40-400 mg/L), contact time (5-120 min) and iron dose (0.1-1 g) with a mesh of<100 were studied. Dye concentration was determined using a spectrophotometer at a wavelength of 520 nm. The results indicated that maximum adsorption capacity of the dye in question was obtained at pH 3, contact time of 60 min and adsorbent dose of 1 g. At initial dye concentration of 100 and 200 mg/L, by increasing the dose of waste iron from 0.1 to 1 g, the removal percentage increased from approximately 76.89% to 97.28% and from 22.64% to 68.03%, respectively. At pH 3, contact time of 5 min and constant waste iron dose of 0.8 g, the dye removal efficiency was 85.34%. By increasing the contact time to 120 min, the removal efficiency increased to 99.2%. Welding iron waste as an inexpensive and available adsorbent has an optimum ability for adsorption of Reactive Red 198 from aqueous solutions.

Defluoridation of water using activated alumina in presence of natural organic matter via response surface methodology.

PubMed

Samarghandi, Mohammad Reza; Khiadani, Mehdi; Foroughi, Maryam; Zolghadr Nasab, Hasan

2016-01-01

Adsorption by activated alumina is considered to be one of the most practiced methods for defluoridation of freshwater. This study was conducted, therefore, to investigate the effect of natural organic matters (NOMs) on the removal of fluoride by activated alumina using response surface methodology. To the authors' knowledge, this has not been previously investigated. Physico-chemical characterization of the alumina was determined by scanning electron microscope (SEM), Brunauer-Emmett-Teller (BET), Fourier transform infrared spectroscopy (FTIR), X-ray fluorescence (XRF), and X-ray diffractometer (XRD). Response surface methodology (RSM) was applied to evaluate the effect of single and combined parameters on the independent variables such as the initial concentration of fluoride, NOMs, and pH on the process. The results revealed that while presence of NOM and increase of pH enhance fluoride adsorption on the activated alumina, initial concentration of fluoride has an adverse effect on the efficiency. The experimental data were analyzed and found to be accurately and reliably fitted to a second-order polynomial model. Under optimum removal condition (fluoride concentration 20 mg/L, NOM concentration 20 mg/L, and pH 7) with a desirability value of 0.93 and fluoride removal efficiency of 80.6%, no significant difference was noticed with the previously reported sequence of the co-exiting ion affinity to activated alumina for fluoride removal. Moreover, aluminum residual was found to be below the recommended value by the guideline for drinking water. Also, the increase of fluoride adsorption on the activated alumina, as NOM concentrations increase, could be due to the complexation between fluoride and adsorbed NOM. Graphical abstract ᅟ.

Biosorption of heavy metals by Bacillus thuringiensis strain OSM29 originating from industrial effluent contaminated north Indian soil

PubMed Central

Oves, Mohammad; Khan, Mohammad Saghir; Zaidi, Almas

2012-01-01

The study was navigated to examine the metal biosorbing ability of bacterial strain OSM29 recovered from rhizosphere of cauliflower grown in soil irrigated consistently with industrial effluents. The metal tolerant bacterial strain OSM29 was identified as Bacillus thuringiensis following 16S rRNA gene sequence analysis. In the presence of the varying concentrations (25–150 mgl−1) of heavy metals, such as cadmium, chromium, copper, lead and nickel, the B. thuringiensis strain OSM29 showed an obvious metal removing potential. The effect of certain physico-chemical factors such as pH, initial metal concentration, and contact time on biosorption was also assessed. The optimum pH for nickel and chromium removal was 7, while for cadmium, copper and lead, it was 6. The optimal contact time was 30 min. for each metal at 32 ± 2 °C by strain OSM29. The biosorption capacity of the strain OSM29 for the metallic ions was highest for Ni (94%) which was followed by Cu (91.8%), while the lowest sorption by bacterial biomass was recorded for Cd (87%) at 25 mgl−1 initial metal ion concentration. The regression coefficients obtained for heavy metals from the Freundlich and Langmuir models were significant. The surface chemical functional groups of B. thuringiensis biomass identified by Fourier transform infrared (FTIR) were amino, carboxyl, hydroxyl, and carbonyl groups, which may be involved in the biosorption of heavy metals. The biosorption ability of B. thuringiensis OSM29 varied with metals and was pH and metal concentration dependent. The biosorption of each metal was fairly rapid which could be an advantage for large scale treatment of contaminated sites. PMID:24115905

Strain improvement of Pichia kudriavzevii TY13 for raised phytase production and reduced phosphate repression.

PubMed

Qvirist, Linnea; Vorontsov, Egor; Veide Vilg, Jenny; Andlid, Thomas

2017-03-01

In this work, we present the development and characterization of a strain of Pichia kudriavzevii (TY1322), with highly improved phytate-degrading capacity. The mutant strain TY1322 shows a biomass-specific phytate degradation of 1.26 mmol g -1  h -1 after 8 h of cultivation in a high-phosphate medium, which is about 8 times higher compared with the wild-type strain. Strain TY1322 was able to grow at low pH (pH 2), at high temperature (46°C) and in the presence of ox bile (2% w/v), indicating this strain's ability to survive passage through the gastrointestinal tract. The purified phytase showed two pH optima, at pH 3.5 and 5.5, and one temperature optimum at 55°C. The lower pH optimum of 3.5 matches the reported pH of the pig stomach, meaning that TY1322 and/or its phytase is highly suitable for use in feed production. Furthermore, P. kudriavzevii TY1322 tolerates ethanol up to 6% (v/v) and shows high osmotic stress tolerance. Owing to the phenotypic characteristics and non-genetically modified organisms nature of TY1322, this strain show great potential for future uses in (i) cereal fermentations for increased mineral bioavailability, and (ii) feed production to increase the phosphate bioavailability for monogastric animals to reduce the need for artificial phosphate fortification. © 2016 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

Purification and Characterization of Alkaline-Thermostable Protease Enzyme from Pitaya (Hylocereus polyrhizus) Waste: A Potential Low Cost of the Enzyme

PubMed Central

ABD Manap, Mohd Yazid; Zohdi, Nor Khanani

2014-01-01

The thermoalkaline protease enzyme from pitaya (Hylocereus polyrhizus) waste was purified by a factor of 221.2 with 71.3% recovery using ammonium sulphate precipitation, gel filtration, and cation exchange chromatography. Gel filtration chromatography together with sodium dodecyl sulphate gel electrophoresis (SDS-PAGE) revealed that the enzyme is monomeric with a molecular weight of 26.7 kDa. The apparent K m and V max of the protease were 2.8 mg/mL and 31.20 u/min, respectively. The optimum pH and temperature were 8.0 and 70°C. The enzyme was highly active and stable over a wide pH range (from pH 3.0 to pH 11.0 with the optimum activity at pH 8.0). The protease has broad specificity toward azocasein, casein, hemoglobin, and gelatine. Activity of the enzyme was inhibited by Fe2+ and Zn2+, while protease activity was increased in the presence of Ca2+ and Mg2+ and Cu2+ by factors of 125%, 110%, and 105%, respectively. The alkaline protease showed extreme stability toward surfactants and oxidizing agent. The purified protease exhibited extreme stability in the presence of organic solvents and inhibitors. In addition, the enzyme was relativity stable toward organic solvents and chelating agents, such as ethylenediaminetetraacetic acid (EDTA). The enzyme, derived from pitaya peel, possesses unique characteristics and could be used in various industrial and biotechnological applications. PMID:25328883

Isolation and characterization of Keratinibaculum paraultunense gen. nov., sp. nov., a novel thermophilic, anaerobic bacterium with keratinolytic activity.

PubMed

Huang, Yan; Sun, Yingjie; Ma, Shichun; Chen, Lu; Zhang, Hui; Deng, Yu

2013-08-01

A novel thermophilic, anaerobic, keratinolytic bacterium designated KD-1 was isolated from grassy marshland. Strain KD-1 was a spore-forming rod with a Gram-positive type cell wall, but stained Gram-negative. The temperature, pH, and NaCl concentration range necessary for growth was 30-65 °C (optimum 55 °C), 6.0-10.5 (optimum 8.0-8.5), and 0-6% (optimum 0.2%) (w/v), respectively. Strain KD-1 possessed extracellular keratinase, and the optimum activity of the crude enzyme was pH 8.5 and 70 °C. The enzyme was identified as a thermostable serine-type protease. The strain was sensitive to rifampin, chloramphenicol, kanamycin, and tetracycline and was resistant to erythromycin, neomycin, penicillin, and streptomycin. The main cellular fatty acid was predominantly C15:0 iso (64%), and the G+C content was 28 mol%. Morphological and physiological characterization, together with phylogenetic analysis based on 16S rRNA gene sequencing identified KD-1 as a new species of a novel genus of Clostridiaceae with 95.3%, 93.8% 16S rRNA gene sequence similarity to Clostridium ultunense BS(T) (DSM 10521(T)) and Tepidimicrobium xylanilyticum PML14(T) (= JCM 15035(T)), respectively. We propose the name Keratinibaculum paraultunense gen. nov., sp. nov., with KD-1 (=JCM 18769(T) =DSM 26752(T)) as the type strain. © 2013 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

Salinirubellus salinus gen. nov., sp. nov., isolated from a marine solar saltern.

PubMed

Hou, Jing; Zhao, Yang-Jie; Zhu, Lin; Cui, Heng-Lin

2018-06-01

A halophilic archaeal strain, designated ZS-35-S2 T , was isolated from Zhoushan marine solar saltern in Zhejiang Province, China. Cells were pleomorphic, Gram-stain-negative and formed red-pigmented colonies on agar plates. The cells lysed in distilled water and the minimal NaCl concentration to prevent cell lysis was 8 % (w/v). Strain ZS-35-S2 T was able to grow at 25-50 °C (optimum, 37 °C), with 1.4-4.8 M NaCl (optimum, 2.1 M), with 0-1.0 M MgCl2 (optimum, 0.1 M) and at pH 5.0-9.5 (optimum, pH 7.5). Phylogenetic tree reconstructions based on 16S rRNA genes and rpoB' genes revealed that strain ZS-35-S2 T was distinct from the related genera Halomarina, Natronomonas, Halorientalis, Salinirubrum and Halobaculum of the order Halobacteriales. The major polar lipids of the strain were phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester and three unidentified glycolipids. The two major glycolipids were chromatographically identical to S-DGD-1 and DGD-1, respectively. The DNA G+C content of strain ZS-35-S2 T is 67.0 mol%. The phenotypic, chemotaxonomic and phylogenetic properties suggested that strain ZS-35-S2 T (=CGMCC 1.12551 T =JCM 30036 T ) represents a novel species of a new genus within the order Halobacteriales, for which the name Salinirubellus salinus gen. nov., sp. nov. is proposed.

A newly-detected reductase from Rauvolfia closes a gap in the biosynthesis of the antiarrhythmic alkaloid ajmaline.

PubMed

Gao, Shujuan; von Schumann, Gerald; Stöckigt, Joachim

2002-10-01

A new enzyme, 1,2-dihydrovomilenine reductase (E.C. 1.3.1), has been detected in Rauvolfia cell suspension cultures. The enzyme specifically converts 2beta( R)-1,2-dihydrovomilenine through an NADPH-dependent reaction into 17-O-acetylnorajmaline, a close biosynthetic precursor of the antiarrhythmic alkaloid ajmaline from Rauvolfia. A five-step purification procedure using SOURCE 30Q chromatography, hydroxyapatite chromatography, 2',5'-ADP Sepharose 4B affinity chromatography and ion exchange chromatography on DEAE Sepharose and Mono Q delivered an approximately 200-fold enriched enzyme in a yield of approximately 6%. SDS-PAGE showed an M r for the enzyme of approximately 48 kDa. Optimum pH and optimum temperature of the reductase were at pH 6.0 and 37 degrees C. The enzyme shows a limited distribution in cell cultures expressing ajmaline biosynthesis, and is obviously highly specific for the ajmaline pathway.

Optimization of growth for the hyperthermophilic archaeon Aeropyrum pernix on a small-batch scale.

PubMed

Milek, Igor; Cigic, Blaz; Skrt, Mihaela; Kaletunç, Gönül; Ulrih, Natasa Poklar

2005-09-01

Growth of Aeropyrum pernix, the first reported aerobic neutrophilic hyperthermophilic archaeon, was investigated under different cultivation parameters. Different sources of seawater, pH, and the cultivation methods were tested with the aim to improve the biomass production. A 1-L glass flask fitted with a condenser and air diffuser was used as a bioreactor. The optimum conditions for maximizing A. pernix biomass were obtained when Na2S2O3.5H2O (1 g/L) with added marine broth 2216 at pH 7.0 (20 mmol HEPES buffer/L) was used as a growing medium in a 1-L flask. The biomass production was 0.45 g dry cell mass/L in 40 h under the optimum conditions, which is more than the 0.42 g dry cell mass/L in 60 h previously obtained.

Nickel solvent extraction from cold purification filter cakes of Angouran mine concentrate using LIX984N

NASA Astrophysics Data System (ADS)

Balesini, A. A.; Zakeri, A.; Razavizadeh, H.; Khani, A.

2013-11-01

Cold purification filter cakes generated in the hydrometallurgical processing of Angouran mine zinc concentrate commonly contain significant amounts of Zn, Cd, and Ni ions and thus are valuable resources for metal recovery. In this research, a nickel containing solution that was obtained from sulfuric acid leaching of the filter cake following cadmium and zinc removal was subjected to solvent extraction experiments using 10vol% LIX984N diluted in kerosene. Under optimum experimental conditions (pH 5.3, volume ratio of organic/aqueous (O:A) = 2:1, and contact time = 5 min), more than 97.1% of nickel was extracted. Nickel was stripped from the loaded organic by contacting with a 200 g/L sulfuric acid solution, from which 77.7% of nickel was recovered in a single contact at the optimum conditions (pH 1-1.5, O:A = 5:1, and contact time = 15 min).

Crystalline Bacterial Surface Layer (S-Layer) Opens Golden Opportunities for Nanobiotechnology in Textiles.

PubMed

Asadi, Narges; Chand, Nima; Rassa, Mehdi

2015-12-01

This study focuses on the successful recrystallization of bacterial S-layer arrays of the Lactobacillus acidophilus ATCC 4356 at textile surfaces to create a novel method and material. Optimum bacterial growth was obtained at approximately 45 °C, pH 5.0, and 14 h pi. The cells were resuspended in guanidine hydrochloride and the 43 kDa S-protein was dialyzed and purified. The optimum reassembly on the polypropylene fabric surface in terms of scanning electron microscopy (SEM), reflectance, and uniformity (spectrophotometry) was obtained at 30 °C, pH 5.0 for 30 minutes in the presence of 2 gr/l (liquor ratio; 1:40) of the S-protein. Overall, our data showed that the functional aspects and specialty applications of the fabric would be very attractive for the textile and related sciences, and result in advanced technical textiles.

Enzymatic browning and biochemical alterations in black spots of pineapple [Ananas comosus (L.) Merr.].

PubMed

Avallone, Sylvie; Guiraud, Joseph-Pierre; Brillouet, Jean-Marc; Teisson, Claude

2003-08-01

Penicillium funiculosum Thom. was consistently isolated from pineapple-infected fruitlet (black spots). Polyphenol oxidase, peroxidase, and laccase activities were determined in extracts from contiguous and infected fruitlets. Healthy fruitlets showed a rather high level of polyphenol oxidase (optimum pH 7.0), and this activity was tremendously increased (X 10) in contiguous infected fruitlets. Furthermore, infected fruitlets also exhibited laccase activity (optimum pH 4.0), while peroxidase was rather constant in both fruitlets. Browning reactions were attributed to qualitative and quantitative modifications of the enzymatic equipment (polyphenol oxidase and laccase) (p < 0.0001). In infected fruiltets, sucrose and L-malic acid were present at significantly lower amounts than in healthy ones, likely owing to fungal metabolism (p < 0.0001), whereas cell wall material was three times higher, which could be viewed as a defense mechanism to limit expansion of the mycelium.

A novel high-throughput screening format to identify inhibitors of secreted acid sphingomyelinase.

PubMed

Mintzer, Robert J; Appell, Kenneth C; Cole, Andrew; Johns, Anthony; Pagila, Rene; Polokoff, Mark A; Tabas, Ira; Snider, R Michael; Meurer-Ogden, Janet A

2005-04-01

Secreted extracellular acid sphingomyelinase (sASM) activity has been suggested to promote atherosclerosis by enhancing subendothelial aggregation and retention of low-density lipoprotein (LDL) with resultant foam cell formation. Compounds that inhibit sASM activity, at neutral pH, may prevent lipid retention and thus would be expected to be anti-atherosclerotic. With the goal of identifying novel compounds that inhibit sASM at pH 7.4, a high-throughput screen was performed. Initial screening was run using a modification of a proven system that measures the hydrolysis of radiolabeled sphingomyelin presented in detergent micelles in a 96-well format. Separation of the radiolabeled aqueous phosphorylcholine reaction product from uncleaved sphingomyelin lipid substrate was achieved by chloroform/methanol extraction. During the screening campaign, a novel extraction procedure was developed to eliminate the use of the hazardous organic reagents. This new procedure exploited the ability of uncleaved, radiolabeled lipid substrate to interact with hydrophobic phenyl-sepharose beads. A comparison of the organic-based and the bead-based extraction sASM screening assays revealed Z' factor values ranging from 0.7 to 0.95 for both formats. In addition, both assay formats led to the identification of sub- to low micromolar inhibitors of sASM at pH 7.4 with similar IC(50) values. Subsequent studies demonstrated that both methods were also adaptable to run in a 384-well format. In contrast to the results observed at neutral pH, however, only the organic extraction assay was capable of accurately measuring sASM activity at its pH optimum of 5.0. The advantages and disadvantages of both sASM assay formats are discussed.

Performance of combined persulfate/aluminum sulfate for landfill leachate treatment.

PubMed

Abu Amr, Salem S; Alkarkhi, Abbas F M; Alslaibi, Tamer M; Abujazar, Mohammed Shadi S

2018-08-01

Although landfilling is still the most suitable method for solid waste disposal, generation of large quantity of leachate is still considered as one of the main environmental problem. Efficient treatment of leachate is required prior to final discharge. Persulfate (S 2 O 8 2- ) recently used for leachate oxidation, the oxidation potential of persulfate can be improved by activate and initiate sulfate radical. The current data aimed to evaluate the performance of utilizing Al 2 SO4 reagent for activation of persulfate to treat landfill leachate. The data on chemical oxygen demand (COD), color, and NH 3 -H removals at different setting of the persulfate, Al 2 SO 4 dosages, pH, and reaction time were collected using a central composite design (CCD) were measured to identify the optimum operating conditions. A total of 30 experiments were performed, the optimum conditions for S 2 O 8 2- /Al 2 SO 4 oxidation process was obtained. Quadratic models for chemical oxygen demand (COD), color, and NH 3 -H removals were significant with p-value < 0.0001. The experimental results were in agreement with the optimum results for COD and NH 3 -N removal rates to be 67%, 81%, and 48%, respectively). The results obtained in leachate treatment were compared with those from other treatment processes, such as S 2 O 8 2- only and Al 2 SO 4 only, to evaluate its effectiveness. The combined method (i.e., /S 2 O 8 2- /Al 2 SO 4 ) showed higher removal efficiency for COD, color, and NH 3 -N compared with other studied applications.

Production of well-matured compost from night-soil sludge by an extremely short period of thermophilic composting.

PubMed

Nakasaki, Kiyohiko; Ohtaki, Akihito; Takemoto, Minoru; Fujiwara, Shunrokuro

2011-03-01

The effect of various operational conditions on the decomposition of organic material during the composting of night-soil treatment sludge was quantitatively examined. The optimum composting conditions were found to be a temperature of ca. 60°C and an initial pH value of 8. Rapid decomposition of organic matter ceased by the sixth day of composting under these optimum conditions, and the final value of the cumulative emission of carbon (E(C)), which represents the degree of organic matter decomposition, was less than 40%, indicating that the sludge contained only a small amount of easily degradable organic material. A plant growth assay using Komatsuna (Brassica campestris L. var. rapiferafroug) in a 1/5000a standard cultivation pot was then conducted for the compost at various degrees of organic matter decomposition: the raw composting material, the final compost obtained on day 6, and the 2 intermediate compost products (i.e., E(C)=10% and 20%). It was found that the larger the E(C), the greater the yield of Komatsuna growth. It was also found that 6 days of composting is sufficient to promote Komatsuna growth at the standard loading level, which is equivalent to a 1.5 g N/pot, since the promotion effect was as high as that obtained using chemical fertilizer. It can therefore be concluded that well-matured compost could be obtained in a short period of time (i.e., as early as 6 days), when night-soil sludge is composted under optimum conditions. Copyright © 2010 Elsevier Ltd. All rights reserved.

Molecular Identification of a Newly Isolated Bacillus subtilis BI19 and Optimization of Production Conditions for Enhanced Production of Extracellular Amylase

PubMed Central

Dash, Biplab Kumar; Rahman, M. Mizanur; Sarker, Palash Kumar

2015-01-01

A study was carried out with a newly isolated bacterial strain yielding extracellular amylase. The phylogenetic tree constructed on the basis of 16S rDNA gene sequences revealed this strain as clustered with the closest members of Bacillus sp. and identified as Bacillus subtilis BI19. The effect of various fermentation conditions on amylase production through shake-flask culture was investigated. Rice flour (1.25%) as a cheap natural carbon source was found to induce amylase production mostly. A combination of peptone and tryptone as organic and ammonium sulfate as inorganic nitrogen sources gave highest yield. Maximum production was obtained after 24 h of incubation at 37°C with an initial medium pH 8.0. Addition of surfactants like Tween 80 (0.25 g/L) and sodium lauryl sulfate (0.2 g/L) resulted in 28% and 15% increase in enzyme production, respectively. Amylase production was 3.06 times higher when optimized production conditions were used. Optimum reaction temperature and pH for crude amylase activity were 50°C and 6.0, respectively. The crude enzyme showed activity and stability over a fair range of temperature and pH. These results suggest that B. subtilis BI19 could be exploited for production of amylase at relatively low cost and time. PMID:26180814

Decolorization of sulfonated azo dye Metanil Yellow by newly isolated bacterial strains: Bacillus sp. strain AK1 and Lysinibacillus sp. strain AK2.

PubMed

Anjaneya, O; Souche, S Yogesh; Santoshkumar, M; Karegoudar, T B

2011-06-15

Two different bacterial strains capable of decolorizing a highly water soluble azo dye Metanil Yellow were isolated from dye contaminated soil sample collected from Atul Dyeing Industry, Bellary, India. The individual bacterial strains Bacillus sp. AK1 and Lysinibacillus sp. AK2 decolorized Metanil Yellow (200 mg L(-1)) completely within 27 and 12h respectively. Various parameters like pH, temperature, NaCl and initial dye concentrations were optimized to develop an economically feasible decolorization process. The maximum concentration of Metanil Yellow (1000 mg L(-1)) was decolorized by strains AK2 and AK1 within 78 and 84 h respectively. These strains could decolorize Metanil Yellow over a broad pH range 5.5-9.0; the optimum pH was 7.2. The decolorization of Metanil Yellow was most efficient at 40°C and confirmed by UV-visible spectroscopy, TLC, HPLC and GC/MS analysis. Further, both the strains showed the involvement of azoreductase in the decolorization process. Phytotoxicity studies of catabolic products of Metanil Yellow on the seeds of chick pea and pigeon pea revealed much reduction in the toxicity of metabolites as compared to the parent dye. These results indicating the effectiveness of strains AK1 and AK2 for the treatment of textile effluents containing azo dyes. Copyright © 2011 Elsevier B.V. All rights reserved.

Use of carbonised beet pulp carbon for removal of Remazol Turquoise Blue-G 133 from aqueous solution.

PubMed

Dursun, Arzu Y; Tepe, Ozlem; Dursun, Gülbeyi

2013-01-01

Carbonised beet pulp (BPC) produced from agricultural solid waste by-product in sugar industry was used as adsorbent for the removal of Remazol Turquoise Blue-G 133 (RTB-G 133) dye in this study. The kinetics and equilibrium of sorption process were investigated with respect to pH, temperature and initial dye concentration. Adsorption studies with real textile wastewater were also performed. The results showed that adsorption was a strongly pH-dependent process, and optimum pH was determined as 1.0. The maximum dye adsorption capacity was obtained as 47.0 mg g(-1)at the temperature of 25 °C at this pH value. The Freundlich and Langmuir adsorption models were used for describing the adsorption equilibrium data of the dye, and isotherm constants were evaluated depending on sorption temperature. Equilibrium data of RTB-G 133 sorption fitted very well to the Freundlich isotherm. Mass transfer and kinetic models were applied to the experimental data to examine the mechanisms of adsorption and potential rate-controlling steps. It was found that both external mass transfer and intra-particle diffusion played an important role in the adsorption mechanisms of dye and adsorption kinetics followed the pseudo second-order type kinetic model. The thermodynamic analysis indicated that the sorption process was exothermic and spontaneous in nature.

Electro persulphate oxidation for polishing of biologically treated palm oil mill effluent (POME).

PubMed

Bashir, Mohammed J K; Wei, Chong Jia; Aun, Ng Choon; Abu Amr, Salem S

2017-05-15

Malaysia alone produces more than 49 million m 3 palm oil mill effluent per year. Biological treated palm oil mill effluent via ponding system often fails to fulfill the regulatory discharge standards. This is due to remaining of non-biodegradable organics in the treated effluent. Thus, the aim of this study was to resolve such issue by using electro persulphate oxidation process, for the first time, as a post treatment of palm oil mill effluent. Central composite design in response surface methodology was used to analyze and optimize the interaction of operational variables (i.e., current density, contact time, initial pH and persulphate dosage) targeted on maximum treatment efficiency. The significance of quadratic model of each response was determined by analysis of variance, where all models indicated sufficient significance with p-value < 0.0001. Optimum operational conditions with 45 mA/cm 2 of current density, 45 min of contact time, pH 4 and 0.892 g of S 2 O 8 2- proved that 77.70% of Chemical Oxygen Demand, 97.96% of colour as well as 99.72% of Suspended Solids removal were achieved. The final pH of 5.88 of the effluent was obtained that fulfilled the limit and suitable for direct discharge to the natural environment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Degradation of pentachlorophenol by hydroxyl radicals and sulfate radicals using electrochemical activation of peroxomonosulfate, peroxodisulfate and hydrogen peroxide.

PubMed

Govindan, Kadarkarai; Raja, Mohan; Noel, Michael; James, E J

2014-05-15

The present study is to investigate the reactivity of free radicals (SO4(-) and HO) generated from common oxidants (peroxomonosulfate (PMS), peroxodisulfate (PDS) and hydrogen peroxide (HP)) activated by electrochemically generated Fe(2+)/Fe(3+) ions which furthermore are evaluated to destroy pentachlorophenol (PCP) in aqueous solution. The effect of solution pH and amount of oxidants (PMS, PDS and HP) in electrocoagulation (EC) on PCP degradation is analyzed in detail. The experimental results reveal that, optimum initial solution pH is 4.5 and PMS is more efficient oxidant addition in EC. 75% PCP degradation is achieved at 60min electrolysis time from PMS assisted EC. According to the first order rate constant, faster PCP degradation rate is obtained by PMS assisted EC. The PCP degradation rate by oxidant assisted EC is observed in the following order: EC/PMS>EC/PDS>EC/HP>EC. Further to identify the influences of experimental factors involved in PCP degradation by oxidant assisted EC, an experimental design based on an orthogonal array (OA) L9 (3(3)) is proposed using Taguchi method. The factors that most significantly affect the process robustness are identified as A (oxidant) and B (pH) which together account for nearly 86% of the variance. Copyright © 2014 Elsevier B.V. All rights reserved.

Selective removal of uranium ions from contaminated waters using modified-X nanozeolite.

PubMed

Shakur, H R; Rezaee Ebrahim Saraee, Kh; Abdi, M R; Azimi, G

2016-12-01

In order to efficiently remove of uranium anionic species (which are the most dominant species of uranium in natural water at neutral pH) from contaminated waters, nano-NaX zeolite was synthesized and then modified using various divalent cations (Mg 2+ , Ca 2+ , Mn 2+ ) and ZnO nanoparticles (from 1.7 to 10.3wt%). Different characterization techniques of XRF, XRD, FE-SEM, TEM, FT-IR, and AAS were used to characterize the final synthesized absorbents. Sorption experiments by batch technique were done to study the effect of solid-liquid ratio, initial uranium concentration, contact time and temperature under neutral condition of pH and presence of all anions and cations which are available in the waters. Results showed that although nano-NaX zeolite due to its negative framework charge had a low sorption capacity for adsorption of uranium anionic species, but modification of parent nano-NaX zeolite with ZnO nanoparticles and various cations effectively improved its uranium adsorption capacity. Also, results showed that under optimum condition of pH=7.56, contact time of 60min at 27°C with solid-liquid ratio of 20g/L a maximum uranium removal efficiency of 99.7% can be obtained in the presence of all anions and cations which are available in the drinking waters by NaX/ZnO nanocomposite. Copyright © 2016 Elsevier Ltd. All rights reserved.

Highly selective adsorption of hydroquinone by hydroxyethyl cellulose functionalized with magnetic/ionic liquid.

PubMed

Ding, Chaofan; Li, Yue; Wang, Yanhui; Li, Jianbo; Sun, Yuanling; Lin, Yanna; Sun, Weiyan; Luo, Chuannan

2018-02-01

Magnetic hydroxyethyl cellulose/ionic liquid (MHEC/IL) materials were fabricated through a facile and fast process and their application as excellent adsorbents for hydroquinone was also demonstrated. The thermal stability, chemical structure and magnetic property of the MHEC/IL were characterized by the Scanning electron microscope (SEM), Transmission Electron Microscope (TEM), Fourier transform infrared spectrometer (FT-IR) and X-ray diffraction (XRD), respectively. The adsorbents were used for the removal of hydroquinone from simulated wastewater with a fast solid-liquid separation in the presence of external magnetic field. The influence of various analytical parameters on the adsorption of hydroquinone such as pH, contact time and initial ion concentration were studied in detail. The results showed that the maximum adsorption capacity was 335.68mgg -1 , observed at pH 5 and temperature 30°C. Equilibrium adsorption was achieved within 30min. The kinetic data, obtained at the optimum pH 5, could be fitted with a pseudo-second order equation. Adsorption process could be well described by Freundlich adsorption isotherms. The obtained results indicated that the impregnation of the room temperature IL significantly enhances the removal efficiency of hydroquinone. The MHEC/IL may be suitable materials in phenols pollution cleanup if they are synthesized in largescale and at low price in near future. Copyright © 2017 Elsevier B.V. All rights reserved.

Conversion of rice husk into fermentable sugar by two stage hydrolysis

NASA Astrophysics Data System (ADS)

Salimi, M. N.; Lim, S. E.; Yusoff, A. H. M.; Jamlos, M. F.

2017-10-01

Rice husks, a complex lignocellulosic biomass which comprised of high cellulose content (38-50%), hemicellulose (23-32%) and lignin (15-25%) possesses the potential to pursue as low cost feedstock for production of ethanol. Dilute sulfuric acid at concentration of 1, 2, 3 (%, v/v) were used for pretreatments at varied hydrolysis time (15-60 min) and enzymatic saccharification at range of 45-60˚C and pH 4.5-6.0 were evaluated for conversion of rice husk’s cellulose and hemicellulose to fermentable sugars. The maximum yield of fermentable sugars from rice husks by dilute sulfuric acid (2%, 60 minutes) was 0.0751 g/l. Total fermentable sugar was identified using dinitrosalicylic acid (DNS) method and expressed in g/l. Enzymatic hydrolysis for conversion of cellulose to fermentable sugar has been studied by applying response surface methodology (RSM) and Analysis of Variance (ANOVA). Two independent variables namely initial pH and incubation temperature were considered using Central Composite Design (CCD). The determination coefficient, R2 obtained was 0.9848. This indicates that 98.48% capriciousness in the respond could be clarified by the ANOVA. Based on the data shown by Design Expert software, the optimum condition for total sugar production was at pH 6.0 and temperature 45˚C as it produced 0.5086 g/l of total sugar.

Effects of pH and Magnetic Material on Immunomagnetic Separation of Cryptosporidium Oocysts from Concentrated Water Samples

PubMed Central

Kuhn, Ryan C.; Rock, Channah M.; Oshima, Kevin H.

2002-01-01

In this study, we examined the effect that magnetic materials and pH have on the recoveries of Cryptosporidium oocysts by immunomagnetic separation (IMS). We determined that particles that were concentrated on a magnet during bead separation have no influence on oocyst recovery; however, removal of these particles did influence pH values. The optimal pH of the IMS was determined to be 7.0. The numbers of oocysts recovered from deionized water at pH 7.0 were 26.3% higher than those recovered from samples that were not at optimal pH. The results indicate that the buffers in the IMS kit did not adequately maintain an optimum pH in some water samples. By adjusting the pH of concentrated environmental water samples to 7.0, recoveries of oocysts increased by 26.4% compared to recoveries from samples where the pH was not adjusted. PMID:11916735

Cloning and sequencing of the gene coding for alcohol dehydrogenase of Bacillus stearothermophilus and rational shift of the optimum pH.

PubMed

Sakoda, H; Imanaka, T

1992-02-01

Using Bacillus subtilis as a host and pTB524 as a vector plasmid, we cloned the thermostable alcohol dehydrogenase (ADH-T) gene (adhT) from Bacillus stearothermophilus NCA1503 and determined its nucleotide sequence. The deduced amino acid sequence (337 amino acids) was compared with the sequences of ADHs from four different origins. The amino acid residues responsible for the catalytic activity of horse liver ADH had been clarified on the basis of three-dimensional structure. Since those catalytic amino acid residues were fairly conserved in ADH-T and other ADHs, ADH-T was inferred to have basically the same proton release system as horse liver ADH. The putative proton release system of ADH-T was elucidated by introducing point mutations at the catalytic amino acid residues, Cys-38 (cysteine at position 38), Thr-40, and His-43, with site-directed mutagenesis. The mutant enzyme Thr-40-Ser (Thr-40 was replaced by serine) showed a little lower level of activity than wild-type ADH-T did. The result indicates that the OH group of serine instead of threonine can also be used for the catalytic activity. To change the pKa value of the putative system, His-43 was replaced by the more basic amino acid arginine. As a result, the optimum pH of the mutant enzyme His-43-Arg was shifted from 7.8 (wild-type enzyme) to 9.0. His-43-Arg exhibited a higher level of activity than wild-type enzyme at the optimum pH.

Cloning and sequencing of the gene coding for alcohol dehydrogenase of Bacillus stearothermophilus and rational shift of the optimum pH.

PubMed Central

Sakoda, H; Imanaka, T

1992-01-01

Using Bacillus subtilis as a host and pTB524 as a vector plasmid, we cloned the thermostable alcohol dehydrogenase (ADH-T) gene (adhT) from Bacillus stearothermophilus NCA1503 and determined its nucleotide sequence. The deduced amino acid sequence (337 amino acids) was compared with the sequences of ADHs from four different origins. The amino acid residues responsible for the catalytic activity of horse liver ADH had been clarified on the basis of three-dimensional structure. Since those catalytic amino acid residues were fairly conserved in ADH-T and other ADHs, ADH-T was inferred to have basically the same proton release system as horse liver ADH. The putative proton release system of ADH-T was elucidated by introducing point mutations at the catalytic amino acid residues, Cys-38 (cysteine at position 38), Thr-40, and His-43, with site-directed mutagenesis. The mutant enzyme Thr-40-Ser (Thr-40 was replaced by serine) showed a little lower level of activity than wild-type ADH-T did. The result indicates that the OH group of serine instead of threonine can also be used for the catalytic activity. To change the pKa value of the putative system, His-43 was replaced by the more basic amino acid arginine. As a result, the optimum pH of the mutant enzyme His-43-Arg was shifted from 7.8 (wild-type enzyme) to 9.0. His-43-Arg exhibited a higher level of activity than wild-type enzyme at the optimum pH. Images PMID:1735726

Purification and characterization of halophilic lipase of Chromohalobacter sp. from ancient salt well.

PubMed

Ai, Li; Huang, Yaping; Wang, Chuan

2018-06-04

A halophilic lipase (LipS2) was produced by Chromohalobacter canadensis strain which was isolated from ancient salt well of Zigong, China. LipS2 was purified to homogeneity and showed a single band with molecular mass of 58 kDa by SDS-PAGE. LipS2 preferred middle-to-long acyl chain esters with C14 triglycerides as optimum substrate. It was noteworthy that LipS2 displayed efficient hydrolysis activity to some vegetable oils which were composed of polyunsaturated fatty acid. LipS2 showed high activity in range of 2.5-3.5 M NaCl, no activity without salt. Optimum temperature and pH were 55 °C and pH 8.5, respectively. Notably, the thermostability and pH stability of LipS2, varying with salt concentration, reached optimum in the presence of 3.0 M NaCl. LipS2 was stimulated by Ca 2+ and Mg 2+ , inhibited by Zn 2+ , Cu 2+ , Mn 2+ , Fe 2+ , and Hg 2+ . Moreover, LipS2 displayed significant tolerance to organic solvents including methanol, ethanol, ethyl acetate and acetone, especially, LipS2 activity was enhanced markedly by the hexane and benzene. Non-ionic surfactants increased LipS2 activity, while ionic surfactants decreased activity. This was the first report on halophilic lipase of Chromohalobacter from ancient salt well. The results suggested that LipS2 may have considerable potential for biotechnological applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Purification of 6-phosphogluconate dehydrogenase from parsley (Petroselinum hortense) leaves and investigation of some kinetic properties.

PubMed

Demir, Hülya; Ciftçi, Mehmet; Küfrevioğlu, O Irfan

2003-02-01

In this study, 6-phosphogluconate dehydrogenase (E.C.1.1.44; 6PGD) was purified from parsley (Petroselinum hortense) leaves, and analysis of the kinetic behavior and some properties of the enzyme were investigated. The purification consisted of three steps that are preparation of homogenate ammonium sulfate fractionation and on DEAE-Sephadex A50 ion exchange. The enzyme was obtained with a yield of 49% and had a specific activity of 18.3 U (mg proteins)(-1) (Lehninger, A.L.; Nelson, D.L.; Cox, M.M. Principles of Biochemistry, 2nd Ed.; Worth Publishers Inc.: N.Y., 2000, 558-560). The overall purification was about 339-fold. A temperature of +4 degrees C was maintained during the purification process. Enzyme activity was spectrophotometrically measured according to the Beutler method at 340 mn. In order to control the purification of the enzyme, SDS-polyacrylamide gel electrophoresis was carried out in 4% and 10% acrylamide for stacking and running gel, respectively. SDS-polyacrylamide gel electrophoresis showed a single band for enzyme. The molecular weight was found to be 97.5 kDa by Sephadex G-150 gel filtration chromatography. A protein band corresponding to a subunit molecular weight of 24.1 kDa was obtained on SDS-polyacrylamide gel electrophoresis. For the enzymes, the stable pH, optimum pH, and optimum temperature were found as 8.0, 8.0, and 50 degrees C, respectively. In addition, KM and Vmax values for NADP+ and G6-P at optimum pH and 25 degrees C were determined by means of Lineweaver-Burk plots.

Engineering of a glycosidase Family 7 cellobiohydrolase to more alkaline pH optimum: the pH behaviour of Trichoderma reesei Cel7A and its E223S/ A224H/L225V/T226A/D262G mutant.

PubMed Central

Becker, D; Braet, C; Brumer , H; Claeyssens, M; Divne, C; Fagerström, B R; Harris, M; Jones, T A; Kleywegt, G J; Koivula, A; Mahdi, S; Piens, K; Sinnott, M L; Ståhlberg, J; Teeri, T T; Underwood, M; Wohlfahrt, G

2001-01-01

The crystal structures of Family 7 glycohydrolases suggest that a histidine residue near the acid/base catalyst could account for the higher pH optimum of the Humicola insolens endoglucanase Cel7B, than the corresponding Trichoderma reesei enzymes. Modelling studies indicated that introduction of histidine at the homologous position in T. reesei Cel7A (Ala(224)) required additional changes to accommodate the bulkier histidine side chain. X-ray crystallography of the catalytic domain of the E223S/A224H/L225V/T226A/D262G mutant reveals that major differences from the wild-type are confined to the mutations themselves. The introduced histidine residue is in plane with its counterpart in H. insolens Cel7B, but is 1.0 A (=0.1 nm) closer to the acid/base Glu(217) residue, with a 3.1 A contact between N(epsilon2) and O(epsilon1). The pH variation of k(cat)/K(m) for 3,4-dinitrophenyl lactoside hydrolysis was accurately bell-shaped for both wild-type and mutant, with pK(1) shifting from 2.22+/-0.03 in the wild-type to 3.19+/-0.03 in the mutant, and pK(2) shifting from 5.99+/-0.02 to 6.78+/-0.02. With this poor substrate, the ionizations probably represent those of the free enzyme. The relative k(cat) for 2-chloro-4-nitrophenyl lactoside showed similar behaviour. The shift in the mutant pH optimum was associated with lower k(cat)/K(m) values for both lactosides and cellobiosides, and a marginally lower stability. However, k(cat) values for cellobiosides are higher for the mutant. This we attribute to reduced non-productive binding in the +1 and +2 subsites; inhibition by cellobiose is certainly relieved in the mutant. The weaker binding of cellobiose is due to the loss of two water-mediated hydrogen bonds. PMID:11336632

Structural Analysis of Alkaline β-Mannanase from Alkaliphilic Bacillus sp. N16-5: Implications for Adaptation to Alkaline Conditions

PubMed Central

Zhao, Yueju; Zhang, Yunhua; Cao, Yang; Qi, Jianxun; Mao, Liangwei; Xue, Yanfen; Gao, Feng; Peng, Hao; Wang, Xiaowei; Gao, George F.; Ma, Yanhe

2011-01-01

Significant progress has been made in isolating novel alkaline β-mannanases, however, there is a paucity of information concerning the structural basis for alkaline tolerance displayed by these β-mannanases. We report the catalytic domain structure of an industrially important β-mannanase from the alkaliphilic Bacillus sp. N16-5 (BSP165 MAN) at a resolution of 1.6 Å. This enzyme, classified into subfamily 8 in glycosyl hydrolase family 5 (GH5), has a pH optimum of enzymatic activity at pH 9.5 and folds into a classic (β/α)8-barrel. In order to gain insight into molecular features for alkaline adaptation, we compared BSP165 MAN with previously reported GH5 β-mannanases. It was revealed that BSP165 MAN and other subfamily 8 β-mannanases have significantly increased hydrophobic and Arg residues content and decreased polar residues, comparing to β-mannanases of subfamily 7 or 10 in GH5 which display optimum activities at lower pH. Further, extensive structural comparisons show alkaline β-mannanases possess a set of distinctive features. Position and length of some helices, strands and loops of the TIM barrel structures are changed, which contributes, to a certain degree, to the distinctly different shaped (β/α)8-barrels, thus affecting the catalytic environment of these enzymes. The number of negatively charged residues is increased on the molecular surface, and fewer polar residues are exposed to the solvent. Two amino acid substitutions in the vicinity of the acid/base catalyst were proposed to be possibly responsible for the variation in pH optimum of these homologous enzymes in subfamily 8 of GH5, identified by sequence homology analysis and pK a calculations of the active site residues. Mutational analysis has proved that Gln91 and Glu226 are important for BSP165 MAN to function at high pH. These findings are proposed to be possible factors implicated in the alkaline adaptation of GH5 β-mannanases and will help to further understanding of alkaline adaptation mechanism. PMID:21436878

Tylosin production by Streptomyces fradiae using raw cornmeal in airlift bioreactor.

PubMed

Choi, Dubok; Choi, On You; Shin, Hyun-Jae; Chung, Dong-Ok; Shin, Dae-Yewn

2007-07-01

Using a 50-l airlift bioreactor, for the effective production of tylosin from Streptomyces fradiae TM-224 using raw cornmeal as the energy source, various environmental factors were studied in flask cultures. The maximum tylosin concentration was obtained at 32 degrees C and pH between 7.0 and 7.5. When seed was inoculated after 24 h of culture, the maximum tylosin concentration, 5.7 g/l, was obtained after 4 days of culture. Various concentrations of raw cornmeal were tested to investigate the optimum initial concentration for the tylosin production. An initial raw cornmeal concentration of 80 g/l gave the highest tylosin concentration, 5.8 g/l, after 5 days of culture. Of the various nitrogen sources, soybean meal and fish meal were found to be the most effective for the production of tylosin. In particular, with the optimal mixing ratio, 12 g/l of soybean meal to 14 g/l of fish meal, 7.2 g/l of tylosin was obtained after 5 days of culture. To compare raw cornmeal and glucose for the production oftylosin in the 50-1 airlift bioreactor for 10 days, fed-batch cultures were carried out under the optimum culture conditions. When raw corn meal was used as the energy source, the tylosin production increased with increasing culture time. The maximum tylosin concentration after 10 days of culture was 13.5 g/l, with a product yield from raw cornmeal of 0.123 g/g of consumed carbon source, which was about 7.2 times higher than that obtained when glucose was used as the carbon source.

A ribonuclease from the wild mushroom Boletus griseus.

PubMed

Wang, Hexiang; Ng, T B

2006-10-01

A ribonuclease (RNase) with a molecular mass of 29 kDa and cospecific for poly A and poly U was isolated from fruiting bodies of the mushroom Boletus griseus. Its N-terminal sequence exhibited some similarity to those of RNases from the mushrooms Irpex lacteus and Lentinus edodes. The RNase was adsorbed on diethylaminoethyl-cellulose, Q-Sepharose, and Affi-gel blue gel and was unadsorbed on CM-cellulose. The enzyme exhibited a temperature optimum between 60 and 70 degrees C and a pH optimum at 3.5.

Statistical optimization of medium components for the production of Antrodia cinnamomea AC0623 in submerged cultures.

PubMed

Chang, Chien-Yu; Lee, Chun-Lin; Pan, Tzu-Ming

2006-10-01

The nutritional medium requirement for biomass and triterpenoid production by Antrodia cinnamomea AC0623 strain was optimized. Box-Behnken was applied to optimize biomass and triterpenoid production. According to response surface methodology (RSM), the optimum concentrations of N-source were determined. The results indicate that when a submerged culture in shake flasks was operated at 28 degrees C, initial pH 5.5, and rotation speed 105 rpm, the biomass and triterpenoid content in dry basis could be increased to 3.20% (w/w) and 31.8 mg/g, respectively. The experiments were further scaled up to 100- and 700-l fermentors. Higher content of triterpenoids (63.0 mg/g) was obtained in 700-l fermentations by means of the control of cultural conditions and the modification of medium composition based on the RSM.

Purification and characterization of the restriction endonuclease RsrI, an isoschizomer of EcoRI.

PubMed

Greene, P J; Ballard, B T; Stephenson, F; Kohr, W J; Rodriguez, H; Rosenberg, J M; Boyer, H W

1988-08-15

Rhodobacter sphaeroides strain 630 produces restriction enzyme RsrI which is an isoschizomer of EcoRI. We have purified this enzyme and initiated a comparison with the EcoRI endonuclease. The properties of RsrI are consistent with a reaction mechanism similar to that of EcoRI: the position of cleavage within the -GAATTC-site is identical, the MgCl2 optimum for the cleavage is identical, and the pH profile is similar. Methylation of the substrate sequence by the EcoRI methylase protects the site from cleavage by the RsrI endonuclease. RsrI cross-reacts strongly with anti-EcoRI serum indicating three-dimensional structural similarities. We have determined the sequence of 34 N terminal amino acids for RsrI and this sequence possesses significant similarity to the EcoRI N terminus.

Optimization of fermentation conditions for alcohol production.

PubMed

Bowman, L; Geiger, E

1984-12-01

The quantitative effects of carbohydrate levels, degree of initial saccharification, glucoamylase dosage, temperature, and fermentation time were investigated using a Box-Wilson central composite design protocol. With Saccharomyces cerevisiae ATCC 4126, it was found that the use of a partially saccharified starch substrate markedly increased yields and attainable alcohol levels. Balancing the degree of initial saccharification with the level of glucoamylase used to complete hydrolysis was found necessary to obtain optimum yields. The temperature optimum was found to be 36 degrees C. The regression equations obtained were used to model the fermentation in order to determine optimum fermentation conditions.

Thermococcus prieurii sp. nov., a hyperthermophilic archaeon isolated from a deep-sea hydrothermal vent.

PubMed

Gorlas, Aurore; Alain, Karine; Bienvenu, Nadège; Geslin, Claire

2013-08-01

A novel hyperthermophilic, anaerobic archaeon, strain Bio-pl-0405IT2(T), was isolated from a hydrothermal chimney sample collected from the East Pacific Rise at 2700 m depth in the 'Sarah Spring' area (7° 25' 24" S 107° 47' 66" W). Cells were irregular, motile cocci (0.8-1.5 µm in diameter) and divided by constriction. Growth was observed at temperatures between 60 °C and 95 °C with an optimum at 80 °C. The pH range for growth was between pH 4.0 and pH 8.0 with an optimum around pH 7.0. Strain Bio-pl-0405IT2(T) grew at salt concentrations of 1-5 % (w/v) NaCl with an optimum at 2 %. The novel isolate grew by fermentation or sulphur respiration on a variety of organic compounds. It was a chemoorganoheterotrophic archaeon growing preferentially with yeast extract, peptone and tryptone as carbon and energy sources and sulphur and organic compounds as electron acceptors; it also grew on maltose and starch. Sulphur or l-cystine were required for growth and were reduced to hydrogen sulfide. The strain was resistant to rifampicin, chloramphenicol, vancomycin and kanamycin (all at 100 µg ml(-1)) but was sensitive to tetracycline. The G+C content of its genomic DNA was 53.6 mol%. Phylogenetic analysis of the almost complete 16S rRNA gene sequence (1450 bp) of strain Bio-pl-0405IT2(T) showed that the novel isolate belonged to the genus Thermococcus. DNA-DNA hybridization values with the two closest relatives Thermococcus hydrothermalis AL662(T) and Thermococcus celer JCM 8558(T) were below the threshold value of 70 %. On the basis of the physiological and genotypic distinctness, we propose a novel species, Thermococcus prieurii sp. nov. The type strain is Bio-pl-0405IT2(T) ( = CSUR P577(T)= JCM 16307(T)).

Algicidal activity of an actinomycete strain, Streptomyces rameus, against Microcystis aeruginosa.

PubMed

Phankhajon, Kanchariya; Somdee, Anchana; Somdee, Theerasak

2016-09-01

An actinomycete strain (KKU-A3) with algicidal activity against Microcystis aeruginosa was isolated from soil in Khon Kaen Province, Thailand. Based on its phenotypic characteristics and 16S rDNA sequence, strain KKU-A3 was identified as Streptomyces rameus. Strain KKU-A3 also exhibited algicidal activity against the cyanobacteria Synechococcus elongatus, Cylindrospermum sp. and Oscillatoria sp. A mathematical and statistical technique was used to optimize the culture conditions and maximize its anti-Microcystis activity. The single factor experiments indicated that glucose and casein were the most effective carbon and nitrogen sources, respectively, and produced the highest anti-Microcystis activity. Response surface methodology indicated that the optimum culture conditions were 19.81 g/L glucose and 2.0 g/L casein at an initial pH of 7.8 and an incubation temperature of 30 °C. The anti-Microcystis activity increased from 82% to 95% under optimum conditions. In an internal airlift loop bioreactor, the removal of M. aeruginosa KKU-13 by the bacterium was investigated in batch and continuous flow experiments. In the batch experiment, KKU-A3 displayed maximum anti-Microcystis activity of 95% at day 7, whereas in the continuous flow experiment, KKU-A3 displayed maximum anti-Microcystis activity of 95% at day 10.

Biodegradation of toluene vapor in coir based upflow packed bed reactor by Trichoderma asperellum isolate.

PubMed

Gopinath, M; Mohanapriya, C; Sivakumar, K; Baskar, G; Muthukumaran, C; Dhanasekar, R

2016-03-01

In the present study, a new biofiltration system involving a selective microbial strain isolated from aerated municipal sewage water attached with coir as packing material was developed for toluene degradation. The selected fungal isolate was identified as Trichoderma asperellum by 16S ribosomal RNA (16S rRNA) sequencing method, and pylogenetic tree was constructed using BLASTn search. Effect of various factors on growth and toluene degradation by newly isolated T. asperellum was studied in batch studies, and the optimum conditions were found to be pH 7.0, temperature 30 °C, and initial toluene concentration 1.5 (v/v)%. Continuous removal of gaseous toluene was monitored in upflow packed bed reactor (UFPBR) using T. asperellum. Effect of various parameters like column height, flow rate, and the inlet toluene concentration were studied to evaluate the performance of the biofilter. The maximum elimination capacity (257 g m(-3) h(-1)) was obtained with the packing height of 100 cm with the empty bed residence time of 5 min. Under these optimum conditions, the T. asperellum showed better toluene removal efficiency. Kinetic models have been developed for toluene degradation by T. asperellum using macrokinetic approach of the plug flow model incorporated with Monod model.

Comparative study of stability of soluble and cell wall invertase from Saccharomyces cerevisiae.

PubMed

Margetić, Aleksandra; Vujčić, Zoran

2017-03-16

Yeast Saccharomyces cerevisiae is the most significant source of enzyme invertase. It is mainly used in the food industry as a soluble or immobilized enzyme. The greatest amount of invertase is located in the periplasmic space in yeast. In this work, it was isolated into two forms of enzyme from yeast S. cerevisiae cell, soluble and cell wall invertase (CWI). Both forms of enzyme showed same temperature optimum (60°C), similar pH optimum, and kinetic parameters. The significant difference between these biocatalysts was observed in their thermal stability, stability in urea and methanol solution. At 60°C, CWI had 1.7 times longer half-life than soluble enzyme, while at 70°C CWI showed 8.7 times longer half-life than soluble enzyme. After 2-hr of incubation in 8 M urea solution, soluble invertase and CWI retained 10 and 60% of its initial activity, respectively. During 22 hr of incubation of both enzymes in 30 and 40% methanol, soluble invertase was completely inactivated, while CWI changed its activity within the experimental error. Therefore, soluble invertase and CWI have not shown any substantial difference, but CWI showed better thermal stability and stability in some of the typical protein-denaturing agents.

Thermostable purified endoglucanase II from Acidothermus cellulolyticus ATCC

DOEpatents

Adney, William S.; Thomas, Steven R.; Nieves, Rafael A.; Himmel, Michael E.

1994-01-01

A purified low molecular weight endoglucanase II from Acidothermus cellulolyticus (ATCC 43068) is disclosed. The endoglucanase is water soluble, possesses both C.sub.1, and C.sub.x types of enzyme activity, a high degree of stability toward heat, and exhibits optimum temperature activity at about 81.degree. C. at pH's from about 2 to about 9, and at a inactivation temperature of about 100.degree. C. at pH's from about 2 to about 9.

Alkaline stress response in Enterococcus faecalis: adaptation, cross-protection, and changes in protein synthesis.

PubMed Central

Flahaut, S; Hartke, A; Giard, J C; Auffray, Y

1997-01-01

The alkaline shock response in Enterococcus faecalis was studied in this work. Cells adapted to an optimum pH of 10.5 were tolerate to pH 11.9 conditions but acquired sensitivity to acid damage. An analysis of stress proteins revealed that 37 polypeptides were amplified. Two of these are DnaK and GroEL. The combined results show that bile salts and alkaline stress responses are closely related. PMID:9023964

Thermostable purified endoglucanase II from Acidothermus cellulolyticus ATCC

DOEpatents

Adney, W.S.; Thomas, S.R.; Nieves, R.A.; Himmel, M.E.

1994-11-22

A purified low molecular weight endoglucanase II from Acidothermus cellulolyticus (ATCC 43068) is disclosed. The endoglucanase is water soluble, possesses both C[sub 1], and C[sub x] types of enzyme activity, a high degree of stability toward heat, and exhibits optimum temperature activity at about 81 C at pH's from about 2 to about 9, and at a inactivation temperature of about 100 C at pH's from about 2 to about 9. 9 figs.

Comparison of two modified coal ash ferric-carbon micro-electrolysis ceramic media for pretreatment of tetracycline wastewater.

PubMed

Yang, Kunlun; Jin, Yang; Yue, Qinyan; Zhao, Pin; Gao, Yuan; Wu, Suqing; Gao, Baoyu

2017-05-01

Application of modified sintering ferric-carbon ceramics (SFC) and sintering-free ferric-carbon ceramics (SFFC) based on coal ash and scrap iron for pretreatment of tetracycline (TET) wastewater was investigated in this article. Physical property, morphological character, toxic metal leaching content, and crystal component were studied to explore the application possibility of novel ceramics in micro-electrolysis reactors. The influences of operating conditions including influent pH, hydraulic retention time (HRT), and air-water ratio (A/W) on the removal of tetracycline were studied. The results showed that SFC and SFFC were suitable for application in micro-electrolysis reactors. The optimum conditions of SFC reactor were pH of 3, HRT of 7 h, and A/W of 10. For SFFC reactor, the optimum conditions were pH of 2, HRT of 7 h, and A/W of 15. In general, the TET removal efficiency of SFC reactor was better than that of SFFC reactor. However, the harden resistance of SFFC was better than that of SFC. Furthermore, the biodegradability of TET wastewater was improved greatly after micro-electrolysis pretreatment for both SFC and SFFC reactors.

Removal of chromium (VI) using poly(methylacrylate) functionalized guar gum.

PubMed

Singh, Vandana; Kumari, Premlata; Pandey, Sadanand; Narayan, Tripti

2009-03-01

Using persulfate/ascorbic acid redox pair, poly(methylacrylate) was grafted on to guar gum and the conditions for the grafting were optimized. The copolymer sample having maximum %G was evaluated for the removal of Cr(VI) and the sorption conditions were optimized. The sorption was found pH dependent, pH 1.0 being the optimum value. Sorption data at pH 1.0 were modeled using both the Langmuir and Freundlich isotherms where the data fitted better to Freundlich isotherm. The equilibrium sorption capacity of 29.67mg/g was determined from the Langmuir isotherm. The sorption followed a pseudo-second-order kinetics with a rate constant 2.5x10(-4)gmg(-1) min(-1). The grafted product was also evaluated for Cr(VI) removal from local electroplating industrial waste water. The regeneration experiments revealed that the guar-graft-poly(methylacrylate) could be successfully reused for five cycles. In the present study conductivity measurements were used instead of conventional photometric method for determining Cr(VI) concentration in the equilibrium solutions and the results obtained have been compared with photometric method. Optimum Cr(VI) binding under highly acidic conditions indicated significant contribution of non electrostatic forces in the adsorption process.

Purification and characterization of trimethylamine-N-oxide demethylase from jumbo squid (Dosidicus gigas).

PubMed

Fu, Xue-Yan; Xue, Chang-Hu; Miao, Ben-Chun; Liang, Jun-Ni; Li, Zhao-Jie; Cui, Feng-Xia

2006-02-08

Trimethylamine-N-oxide demethylase (TMAOase) was purified from Jumbo squid (Dosidicus gigas) and characterized in detail herein. The TMAOase was extracted from squid with 20 mM Tris-acetate buffer (pH 7.0) containing 1.0 M NaCl, followed by acid treatment and heat treatment. Then it was purified by deithylaminoethyl-cellulose and Sephacryl S-300 chromatography, subsequently resulting in an 839-fold purification. The molecular mass of the TMAOase was defined to be 17.5 kDa. The optimum pH of the purified TMAOase was 7.0, and its optimum temperature was confirmed to be 55 degrees C. The TMAOase was stable to heat treatment up to 50 degrees C and stable at pH 7.0-9.0. Reducing agents such as DTT, Na2SO3, and NADH were effective at activating TMAOase, and ethylenediaminetetraacetic acid, as well as Mg2+ and Ca2+, could also enhance the activity of TMAOase remarkably, whereas the TMAOase could be significantly inhibited by tea polyphenol, phytic acid and acetic acid. In addition, the TMAOase converted TMAO to dimethylamine and formaldehyde stoichiometrically with a K(m) of 26.2 mM.

Simultaneous production of detergent stable keratinolytic protease, amylase and biosurfactant by Bacillus subtilis PF1 using agro industrial waste.

PubMed

Bhange, Khushboo; Chaturvedi, Venkatesh; Bhatt, Renu

2016-06-01

The present study is an attempt to optimize simultaneous production of keratinolytic protease, amylase and biosurfactant from feather meal, potato peel and rape seed cake in a single media by response surface methodology to evaluate their biochemical properties for detergent additive. The optimization was carried out using 20 run, 3 factor and 5-level of central composite design on design expert software which resulted in a 1.2, 0.84 and 2.28 fold increase in protease, amylase and biosurfactant production. The proteolytic activity was found to be optimum at pH 9.0 and 60 °C while optimum amylolytic activity was recorded at pH 6.0 and 70 °C respectively. Both enzymes were found to be stable in the presence of organic solvents, ionic and commercial detergent and oxidizing agents. The biosurfactant was extracted with chloroform and was found to be stable at varying pH and temperature; however a reduction in the activity was observed at temperature higher than 70 °C. The isolated enzymes and biosurfactants may find applications in the effective removal of stains.

Synthesis and Characterisation of Biocompatible Polymer-Conjugated Magnetic Beads for Enhancement Stability of Urease.

PubMed

Doğaç, Yasemin Ispirli; Teke, Mustafa

2016-04-01

We reported natural polymer-conjugated magnetic featured urease systems for removal of urea effectively. The optimum temperature (20-60 °C), optimum pH (3.0-10.0), kinetic parameters, thermal stability (4-70 °C), pH stability (4.0-9.0), operational stability (0-250 min), reusability (18 times) and storage stability (24 weeks) were studied for characterisation of the urease-encapsulated biocompatible polymer-conjugated magnetic beads. Also, the surface groups and chemical structure of the magnetic beads were determined by using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). The all urease-encapsulated magnetic beads protected their stability of 30-45 % relative activity at 70 °C. A significant increase was observed at their pH stability compared with the free urease for both acidic and alkaline medium. Besides this, their repeatability activity were approximately 100 % during 4(th) run. They showed residual activity of 50 % after 16 weeks. The importance of this work is enhancement stability of immobilised urease by biocompatible polymer-conjugated magnetic beads for the industrial application based on removal of urea.

Production and characterization of glucoamylase from fungus Aspergillus awamori expressed in yeast Saccharomyces cerevisiae using different carbon sources

PubMed Central

Pavezzi, Fabiana Carina; Gomes, Eleni; da Silva, Roberto

2008-01-01

Glucoamylase is widely used in the food industry to produce high glucose syrup, and also in fermentation processes for production beer and ethanol. In this work the productivity of the glucoamylase of Aspergillus awamori expressed by the yeast Saccharomyces cerevisiae, produced in submerged fermentation using different starches, was evaluated and characterized physico-chemically. The enzyme presented high specific activity, 13.8 U/mgprotein or 2.9 U/mgbiomass, after 48 h of fermentation using soluble starch as substrate. Glucoamylase presented optimum activity at temperature of 55°C, and, in the substratum absence, the thermostability was for 1h at 50°C. The optimum pH of activity was pH 3.5 - 4.0 and the pH stability between 5.0 and 7.0. The half life at 65°C was at 30.2 min, and the thermal energy of denaturation was 234.3 KJ mol-1. The hydrolysis of different substrate showed the enzyme’s preference for the substrate with a larger polymerization degree. The gelatinized corn starch was the substratum most susceptible to the enzymatic action. PMID:24031189

Purification and Characterization of a Cyclomaltodextrin Glucanotransferase From Paenibacillus campinasensis Strain H69-3

NASA Astrophysics Data System (ADS)

Alves-Prado, Heloiza Ferreira; Gomes, Eleni; da Silva, Roberto

A cyclomaltodextrin glucanotransferase (E.C. 2.4.1.19) from a newly isolated alkalophilic and moderately thermophilic Paenibacillus campinasensis strain H69-3 was purified as a homogeneous protein from culture supernatant. Cyclomaltodextrin glucanotransferase was produced during submerged fermentation at 45°C and purified by gel filtration on Sephadex G50 ion exchange using a Q-Sepharose column and ion exchange using a Mono-Q column. The molecular weight of the purified enzyme was 70 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and the pI was 5.3. The optimum pH for enzyme activity was 6.5, and it was stable in the pH range 6.0-11.5. The optimum temperature was 65°C at pH 6.5, and it was thermally stable up to 60°C without substrate during 1 h in the presence of 10 mM CaCl2 The enzyme activity increased in the presence of Co2+, Ba2+, and Mn2+. Using maltodextrin as substrate, the K m and K cat were 1.65 mg/mL and 347.9 μmol/mg-min, respectively.

Laccase Production from a Temperature and pH Tolerant Fungal Strain of Trametes hirsuta (MTCC 11397).

PubMed

Dhakar, Kusum; Pandey, Anita

2013-01-01

Laccase production by a temperature and pH tolerant fungal strain (GBPI-CDF-03) isolated from a glacial site in Indian Himalayan Region (IHR) has been investigated. The fungus developed white cottony mass on potato dextrose agar and revealed thread-like mycelium under microscope. ITS region analysis of fungus showed its 100% similarity with Trametes hirsuta. The fungus tolerated temperature from 4 to 48°C ± 2 (25°C opt.) and pH 3-13 (5-7 opt.). Molecular weight of laccase was determined approximately 45 kDa by native PAGE. Amplification of laccase gene fragment (corresponding to the copper-binding conserved domain) contained 200 bp. The optimum pH for laccase production, at optimum growth temperature, was determined between 5.5 and 7.5. In optimization experiments, fructose and ammonium sulfate were found to be the best carbon and nitrogen sources, respectively, for enhancing the laccase production. Production of laccase was favored by high carbon/nitrogen ratio. Addition of CuSO4 (up to 1.0 mM) induced laccase production up to 2-fold, in case of 0.4 mM concentration. Addition of organic solvents also induced the production of laccase; acetone showed the highest (2-fold) induction. The study has implications in bioprospecting of ecologically resilient microbial strains.

Isolation and identification of two extremely halophilic archaea from sebkhas in the Algerian Sahara.

PubMed

Khallef, Sakina; Lestini, Roxane; Myllykallio, Hannu; Houali, Karim

2018-03-31

In Algeria, many salt lakes are to be found spread from southern Tunisia up to the Atlas Mountains in northern Algeria. Oum Eraneb and Ain El beida sebkhas (salt lakes), are located in the Algerian Sahara. The aim of this study was to explore the diversity of the halobacteria in this type of habitats. The physicochemical properties of these shallow saline environments were examined and compared with other hypersaline and marine ecosystems. Both sites were relatively alkaline with a pH around 8.57- 8.74 and rich in salt at 13% and 16% (w/v) salinity for Oum Eraneb and Ain El beida, respectively, with dominant ions of sodium and chloride. The microbial approach revealed the presence of two halophilic archaea, strains JCM13561 and A33T in both explored sebkhas. Growth occurred between 10 and 25% (w/v) NaCl and the isolates grow optimally at 20% (w/v) NaCl. The pH range for growth was 6 to 9.5 with an optimum at pH 7.5 for the first strain and 7 to 9.5 with an optimum pH at 8.5-9 for the second strain. On the basis of 16S rRNA gene sequence analysis, strains JCM13561 and A33T were most closely related to Halorubrum litoreum and Natronorubrum bangense (99% and 96% similarity, respectively).

Influence of culture media and environmental factors on mycelial growth and sporulation of Lasiodiplodia theobromae (Pat.) Griffon and Maubl.

PubMed

Saha, A; Mandal, P; Dasgupta, S; Saha, D

2008-05-01

Lasiodiplodia theobromae, a common tea (Camellia sinensis) pathogen, usually does not sporulate or sporulates poorly in common media, which makes spore production difficult. In this study the effects of culture media, carbon source, nitrogen source, temperature, pH and light on mycelial growth and sporulation were evaluated. Among several carbon sources tested, glucose and sucrose were found superior for growth. Potassium nitrate supplemented media showed maximum growth amongst the tested inorganic nitrogen sources while peptone produced maximum growth among the tested organic nitrogen sources. Tea root extract supplemented potato dextrose agar medium was found to be the most suitable for mycelial growth and sporulation of L. theobromae. The fungus grow at temperatures ranging from 40 to 36 degrees C, with optimum growth at 28 degrees C and no growth was noted at 40 degrees C. There was no significant effect of different light period on growth of L. theobromae, but light enhanced sporulation. The fungus grow at pH 3.0-8.0 and optimum growth was observed at pH 6.0. Tea root extract supplemented potato dextrose agar medium with pH 6.0 was the most suitable for production of conidia of L. theobromae at 28 degrees C. Hence this media may be recommended for inoculum production for further studies.

Naphthol AS-BI (7-bromo-3-hydroxy-2-naphtho-o-anisidine) phosphatase and naphthol AS-BI. beta. -D-glucuronidase in Chinese hamster ovary cells: biochemical and flow cytometric studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dolbeare, F.A.; Phares, W.

1979-01-01

Conditions for the biochemical and flow cytometric assay of 7-bromo-3-hydroxy-2-naphtho-o-anisidine phosphatase and ..beta..-D-glucuronidase activities in Chinese hamster ovary cells were studied. In the biochemical assays, the pH optimum for the phosphatase activity was pH 4.6 with a Km of 10/sup -5/ M; the pH optimum for ..beta..-D-glucuronidase activity was pH 5.0 with a Km of 2 x 10/sup -5/ M. For intact cells the derived constants were 3 to 10 times higher. The rate of hydrolysis of both substrates was also examined by flow cytometry. Cellular fluorescence increased linearly for only about 15 min. Diffusion of the fluorescent product probablymore » caused nonlinearity of the fluorescence increase and was demonstrated by mixing cells incubated with substrate with those that had not been incubated. After 15 min, cells that had not been exposed previously to product or substrate contained the fluorescent product. Cells fractionated into size classes by centrifugal elutriation also were analyzed by flow cytometry for ..beta..-D-glucuronidase activity. The activity increased linearly with the increase in cell size corresponding to the progression from G/sub 1/ through S and into G/sub 2/-M phases of the cell cycle.« less

Methotrexate loading in chitosan nanoparticles at a novel pH: Response surface modeling, optimization and characterization.

PubMed

Hashad, Rania A; Ishak, Rania A H; Geneidi, Ahmed S; Mansour, Samar

2016-10-01

The aim of this study was to assess the feasibility of employing a novel but critical formulation pH (6.2) to encapsulate an anionic model drug (methotrexate, MTX) into chitosan(Cs)-tripolyphosphate nanoparticles(NPs). A response surface methodology using a three-level full factorial design was applied studying the effects of two independent variables namely; Cs concentration and MTX concentration. The responses investigated were the entrapment efficiency (EE%), mean hydrodynamic particle size (PS), polydispersity index (PDI) and zeta potential (ZP). In order to simultaneously optimize the series of models obtained, the desirability function approach was applied with a goal to produce high percent of MTX encapsulated into highly charged Cs-TPP NPs of homogenous optimum PS. MTX-loaded CsNPs were successfully prepared at the novel pH applied. The suggested significant models were found quadratic for EE, PS and ZP responses, while 2-factor interaction model for PDI. The optimization overlay graph showed that the maximum global desirability, D=0.856, was reached when the conditions were set at high Cs and MTX concentration. Thus, the use of such optimized conditions, at this novel pH, achieved a maximum drug EE% (73.38%) into NPs characterized by optimum PS (232.6nm), small PDI value (0.195) and highly surface charged (+18.4mV). Copyright © 2016 Elsevier B.V. All rights reserved.

Novel nanocomposite Kevlar fabric membranes: Fabrication characterization, and performance in oil/water separation

NASA Astrophysics Data System (ADS)

Karimnezhad, Hanieh; Rajabi, Laleh; Salehi, Ehsan; Derakhshan, Ali Ashraf; Azimi, Sara

2014-02-01

Nanocomposite membranes with hydrophilic surface were fabricated for separation of oil (n-hexane) from oil/water emulsion. Three different nanomaterials namely, para-aminobenzoate alumoxane (PAB-A), boehmite-epoxide and polycitrate alumoxane (PC-A) were coated on the Kevlar fabric (support), according to a three-step dip-coating protocol. FTIR, SEM, TEM, UV/vis spectrophotometer, and wettability analyses were used to characterize the composite membranes. The three coating layers interacted chemically with one another and also physically with the Kevlar fabric. Water uptake measurements indicated that the membrane is a hydrophilic one. SEM and TEM analyses showed the smooth surface of the composite membrane and three-dimensional dendrimeric hyper-branched structure of (PC-A), respectively. A dead-end filtration setup was applied to test the membranes performance under natural gravity force. Effect of pH as an important variable affecting separation process was investigated with the neutral pH provided the optimum condition for the separation. Oil rejection and permeate fluxes were also monitored. The optimum flux and rejection obtained, were 7392 (Lm-2 h-1) and 89.06% at pH 7, respectively. Fouling occurred as a gel layer on the membrane surface. The deposited oil droplets on the surface of the membrane were successfully washed away with satisfactory permeate flux recovery (FRR = 88.88% at neutral pH), using hot distilled water and acidic solution as eluents.

Production and application of a thermostable lipase from Serratia marcescens in detergent formulation and biodiesel production.

PubMed

García-Silvera, Edgar Edurman; Martínez-Morales, Fernando; Bertrand, Brandt; Morales-Guzmán, Daniel; Rosas-Galván, Nashbly Sarela; León-Rodríguez, Renato; Trejo-Hernández, María R

2018-03-01

In this study, extracellular lipase was produced by Serratia marcescens wild type and three mutant strains. The maximum lipase activity (80 U/mL) was obtained with the SMRG4 mutant strain using soybean oil. Using a 2 2 factorial design, the lipase production increased 1.55-fold (124 U/mL) with 4% and 0.05% of soybean oil and Triton X-100, respectively. The optimum conditions for maximum lipase activity were 50 °C and pH 8. However, the enzyme was active in a broad range of pH (6-10) and temperatures (5-55 °C). This lipase was stable in organic solvents and in the presence of oxidizing agents. The enzyme also proved to be efficient for the removal of triacylglycerol from olive oil in cotton cloth. A Box-Behnken experimental design was used to evaluate the effects of the interactions between total lipase activity, buffer pH, and wash temperatures on oil removal. The model obtained suggested that all selected factors had a significant impact on oil removal, with optimum conditions of 550 U lipase, 45 °C, pH 9.5, with 79.45% removal. Biotransformation of waste frying oil using the enzyme and in presence of methanol resulted in the synthesis of methyl esters such as methyl oleate, methyl palmitate, and methyl stearate. © 2017 International Union of Biochemistry and Molecular Biology, Inc.

A novel approach for rapidly and cost-effectively assessing toxicity of toxic metals in acidic water using an acidophilic iron-oxidizing biosensor.

PubMed

Yang, Shih-Hung; Cheng, Kuo-Chih; Liao, Vivian Hsiu-Chuan

2017-11-01

Contamination by heavy metals and metalloids is a serious environmental and health concern. Acidic wastewaters are often associated with toxic metals which may enter and spread into agricultural soils. Several biological assays have been developed to detect toxic metals; however, most of them can only detect toxic metals in a neutral pH, not in an acidic environment. In this study, an acidophilic iron-oxidizing bacterium (IOB) Strain Y10 was isolated, characterized, and used to detect toxic metals toxicity in acidic water at pH 2.5. The colorimetric acidophilic IOB biosensor was based on the inhibition of the iron oxidizing ability of Strain Y10, an acidophilic iron-oxidizing bacterium, by metals toxicity. Our results showed that Strain Y10 is acidophilic iron-oxidizing bacterium. Thiobacillus caldus medium (TCM) (pH 2.5) supplied with both S 4 O 6 2- and glucose was the optimum growth medium for Strain Y10. The optimum temperature and pH for the growth of Strain Y10 was 45 °C and pH 2.5, respectively. Our study demonstrates that the color-based acidophilic IOB biosensor can be semi-quantitatively observed by eye or quantitatively measured by spectrometer to detect toxicity from multiple toxic metals at pH 2.5 within 45 min. Our study shows that monitoring toxic metals in acidic water is possible by using the acidophilic IOB biosensor. Our study thus provides a novel approach for rapid and cost-effective detection of toxic metals in acidic conditions that can otherwise compromise current methods of chemical analysis. This method also allows for increased efficiency when screening large numbers of environmental samples. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effects of membrane curvature and pH on proton pumping activity of single cytochrome bo3 enzymes.

PubMed

Li, Mengqiu; Khan, Sanobar; Rong, Honglin; Tuma, Roman; Hatzakis, Nikos S; Jeuken, Lars J C

2017-09-01

The molecular mechanism of proton pumping by heme-copper oxidases (HCO) has intrigued the scientific community since it was first proposed. We have recently reported a novel technology that enables the continuous characterisation of proton transport activity of a HCO and ubiquinol oxidase from Escherichia coli, cytochrome bo 3 , for hundreds of seconds on the single enzyme level (Li et al. J Am Chem Soc 137 (2015) 16055-16063). Here, we have extended these studies by additional experiments and analyses of the proton transfer rate as a function of proteoliposome size and pH at the N- and P-side of single HCOs. Proton transport activity of cytochrome bo 3 was found to decrease with increased curvature of the membrane. Furthermore, proton uptake at the N-side (proton entrance) was insensitive to pH between pH6.4-8.4, while proton release at the P-side had an optimum pH of ~7.4, suggesting that the pH optimum is related to proton release from the proton exit site. Our previous single-enzyme experiments identified rare, long-lived conformation states of cytochrome bo 3 where protons leak back under turn-over conditions. Here, we analyzed and found that ~23% of cytochrome bo 3 proteoliposomes show ΔpH half-lives below 50s after stopping turnover, while only ~5% of the proteoliposomes containing a non-pumping mutant, E286C cytochrome bo 3 exhibit such fast decays. These single-enzyme results confirm our model in which HCO exhibit heterogeneous pumping rates and can adopt rare leak states in which protons are able to rapidly flow back. Copyright © 2017 Elsevier B.V. All rights reserved.

Preparation of Zeolite/Zinc Oxide Nanocomposites for toxic metals removal from water

NASA Astrophysics Data System (ADS)

Alswata, Abdullah A.; Ahmad, Mansor Bin; Al-Hada, Naif Mohammed; Kamari, Halimah Mohamed; Hussein, Mohd Zobir Bin; Ibrahim, Nor Azowa

This research work has proposed preparation of Zeolite/Zinc Oxide Nanocomposite (Zeolite/ZnO NCs) by using a co-precipitation method. Then, the prepared Nanocomposite has been tested for adsorption of Lead Pb (II) and Arsenic As (V) from aqueous solution under the room pressure and temperature. After that, the prepared adsorbent has been studied by several techniques. For adsorption process; the effect of the adsorbent masses, contact time, PH and initial metals concentration as well as, the kinetics and isotherm for adsorption process have been investigated. The results revealed that; ZnO nanoparticles (NPs) with average diameter 4.5 nm have successfully been loaded into Zeolite. The optimum parameters for the removal of the toxic metals 93% and 89% of Pb (II) and As (V), respectively, in 100 mg/L aqua solutions were pH4, 0.15 g and 30 min. According to the obtained results; pseudo second-order kinetic and Langmuir isotherm model have higher correlation coefficients and provided a better agreement with the experimental data. The prepared sorbent showed an economical and effective way to remove the heavy toxic metals due to its ambient operation conditions, low- consumption energy and facile regeneration method.

Treatment of wastewater containing o-phenylenediamine by ozone in a rotor-stator reactor.

PubMed

Arowo, Moses; Li, Yingwen; Chu, Guangwen; Sun, Baochang; Chen, Jianfeng; Shao, Lei

2016-01-01

This work employed a novel rotor-stator reactor (RSR) to intensify the degradation process of o-phenylenediamine (o-PDA) by ozone. The effects of different operating parameters including initial pH, temperature, rotation speed, liquid volumetric flow rate and inlet ozone concentration on the removal efficiency of o-PDA were investigated in an attempt to establish the optimum conditions. The removal efficiency was evaluated in terms of degradation ratio and chemical oxygen demand (COD) reduction ratio of the o-PDA wastewater. Results indicate that the removal efficiency decreased with increasing liquid volumetric flow rate but increased with an increase in pH and inlet ozone concentration. Also, the removal efficiency increased up to a certain level with an increase in rotation speed and temperature. Additionally, a comparison experiment was carried out in a stirred tank reactor (STR), and the results show that the degradation and COD reduction ratios reached a maximum of 94.6% and 61.2% in the RSR as compared to 45.3% and 28.6% in the STR, respectively. This work demonstrates that ozone oxidation carried out in RSR may be a promising alternative for pre-treatment of o-PDA wastewater.

Cell wall invertase in tobacco crown gall cells : enzyme properties and regulation by auxin.

PubMed

Weil, M; Rausch, T

1990-12-01

The cell wall invertase from an Agrobacterium tumefaciens-transformed Nicotiana tabacum cell line (SR1-C58) was purified. The heterogeneously glycosylated enzyme has the following properties: M(r) 63,000, pH optimum at 4.7, K(m sucrose) 0.6 millimolar (at pH 4.7), pl 9.5. Enzyme activity is inhibited by micromolar concentrations of HgCl(2) but is insensitive to H(2)O(2), N-ethylmaleimide and dithiothreitol. Upon transfer of transformed cells from the stationary phase to fresh medium, a cycloheximide- and tunicamycin-sensitive de novo formation of cell wall invertase is demonstrated in the absence or presence of sucrose. While in an auxin mutant (lacking gene 1;SR1-3845) 1 micromolar 1-naphthaleneacetic acid led to a further increased activity, the wild-type transformed cell line (SR1-C58) responded with a decreased activity compared to the control. An analysis of cell wall invertase in and around tumors initiated with Agrobacterium tumefaciens (strain C58) on Nicotiana tabacum stem and Kalanchoë daigremontiana leaves revealed gradients of activity. The results indicate that the auxin-stimulated cell wall invertase is essential for the establishment of the tumor sink.

Treatment of real wastewater produced from Mobil car wash station using electrocoagulation technique.

PubMed

El-Ashtoukhy, E-S Z; Amin, N K; Fouad, Y O

2015-10-01

This paper deals with the electrocoagulation of real wastewater produced from a car wash station using a new cell design featuring a horizontal spiral anode placed above a horizontal disc cathode. The study dealt with the chemical oxygen demand (COD) reduction and turbidity removal using electrodes in a batch mode. Various operating parameters such as current density, initial pH, NaCl concentration, temperature, and electrode material were examined to optimize the performance of the process. Also, characterization of sludge formed during electrocoagulation was carried out. The results indicated that the COD reduction and turbidity removal increase with increasing the current density and NaCl concentration; pH from 7 to 8 was found to be optimum for treating the wastewater. Temperature was found to have an insignificant effect on the process. Aluminum was superior to iron as a sacrificial electrode material in treating car wash wastewater. Energy consumption based on COD reduction ranged from 2.32 to 15.1 kWh/kg COD removed depending on the operating conditions. Finally, the sludge produced during electrocoagulation using aluminum electrodes was characterized by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) analysis.

Biodegradation characterization and immobilized strains' potential for quinoline degradation by Brevundimonas sp. K4 isolated from activated sludge of coking wastewater.

PubMed

Wang, Chunrong; Zhang, Mengru; Cheng, Fanglin; Geng, Qi

2015-01-01

A novel quinoline-degrading strain, named K4, was isolated from activated sludge of a coking wastewater treatment plant and identified as Brevundimonas sp. on the basis of its 16s rDNA gene sequence analysis. Its optimum temperature and pH for quinoline degradation were 30 °C and pH 9.0, respectively, and during the biodegradation process, at 100 mg/L initial quinoline concentration, an inoculation amount of 8% (OD600 of 0.23) was the optimal strain concentration. In addition, the kinetics of free K4 strains for quinoline degradation showed that it followed a zero-order equation. Furthermore, compared with free K4 strains, immobilized K4 strains' potential for quinoline degradation was investigated by adding both of them into SBR reactors for actual coking wastewater treatment on operation over 15 days. The results showed that bioaugmentation by both free and immobilized K4 strains enhanced quinoline removal efficiency, and especially, the latter could reach its stable removal after a shorter accommodation period, with 94.8% of mean quinoline removal efficiency.

Optimization of dextran production by Leuconostoc mesenteroides NRRL B-512 using cheap and local sources of carbohydrate and nitrogen.

PubMed

Behravan, Javad; Bazzaz, B Seddigheh Fazly; Salimi, Zohreh

2003-12-01

Using pure components for the fermentation medium in dextran production imposes high costs on the industry. In the present study, the economic production of dextran using local and cheap sources of carbohydrate and nitrogen was investigated. Different concentrations of molasses and wheat-bran extract, after filtration, steam sterilization and pH adjustment, were inoculated with a fresh suspension of Leuconostoc mesenteroides. Cultures were incubated, and then diluted with an equal volume of ethanol. The bacteria were pelleted, and an aliquot of the supernatant was diluted with ethanol and dextran was precipitated. The supernatant was removed and the precipitate was dissolved in a minimal volume of water. Activated charcoal was added and the solution was boiled. The solution was filtered and protein impurities removed by 2-methylbutan-2-ol/chloroform extraction. Dextran was again precipitated with cold ethanol as described above, and the precipitate was dried in a desiccator. Optimum conditions and composition of culture media for dextran production using sugar-beet molasses and wheat bran were determined. The best results were obtained when 20% (w/v) molasses and 15% (w/v) wheat bran were used. The optimal initial pH for dextran production was 7.5.

Removal of Pb (II) Ions from Aqueous Solutions by Cladophora rivularis (Linnaeus) Hoek

PubMed Central

Jafari, Naser; Senobari, Zoreh

2012-01-01

Biosorption of Pb(II) using Cladophora rivularis was examined as a function of initial pH heavy metal concentration and temperature. The optimum pH value for the biosorption of lead was 4.0. The adsorption equilibriums were well described by Langmuir and Freundlich isotherm models and it was implied by the results that the C. rivularis biomass is suitable for the development of efficient biosorbent in order to remove Pb(II) from wastewater and to recover it. The high values of correlation coefficient (R 2 = 0.984) demonstrate equilibrium data concerning algal biomass, which is well fitted in Freundlich isotherms model equations. The dimensionless parameter R L is found in the range of 0.0639 to 0.1925 (0 < R L < 1), which confirms the favorable biosorption process. Fourier transform infra-red (FTIR) spectroscopy of C. rivularis was used to reveal the main function groups of biosorption, which were hydroxyl, amine groups, C–H stretching vibrations of –CH3 and –CH2, and complexation with functional groups. All these results suggest that C. rivularis can be used effectively for removal of Pb(II). PMID:22629198

Cadmium-109 Radioisotope Adsorption onto Polypyrrole Coated Sawdust of Dryobalanops aromatic: Kinetics and Adsorption Isotherms Modelling

PubMed Central

Olatunji, Michael Adekunle; Khandaker, Mayeen Uddin; Amin, Yusoff Mohd; Mahmud, Habibun Nabi Muhammad Ekramul

2016-01-01

A radiotracer study was conducted to investigate the removal characteristics of cadmium (109Cd) from aqueous solution by polypyrrole/ sawdust composite. Several factors such as solution pH, sorbent dosage, initial concentration, contact time, temperature and interfering metal ions were found to have influence on the adsorption process. The kinetics of adsorption was relatively fast, reaching equilibrium within 3 hours. A lowering of the solution pH reduced the removal efficiency from 99.3 to ~ 46.7% and an ambient temperature of 25°C was found to be optimum for maximum adsorption. The presence of sodium and potassium ions inhibited 109Cd removal from its aqueous solution. The experimental data for 109Cd adsorption showed a very good agreement with the Langmuir isotherm and a pseudo-first order kinetic model. The surface condition of the adsorbent before and after cadmium loading was investigated using BET, FESEM and FTIR. Considering the low cost of the precursor’s materials and the toxicity of 109Cd radioactive metal, polypyrrole synthesized on the sawdust of Dryobalanops aromatic could be used as an efficient adsorbent for the removal of 109Cd radioisotope from radionuclide-containing effluents. PMID:27706232

Bioleaching combined brine leaching of heavy metals from lead-zinc mine tailings: Transformations during the leaching process.

PubMed

Ye, Maoyou; Yan, Pingfang; Sun, Shuiyu; Han, Dajian; Xiao, Xiao; Zheng, Li; Huang, Shaosong; Chen, Yun; Zhuang, Shengwei

2017-02-01

During the process of bioleaching, lead (Pb) recovery is low. This low recovery is caused by a problem with the bioleaching technique. This research investigated the bioleaching combination of bioleaching with brine leaching to remove heavy metals from lead-zinc mine tailings. The impact of different parameters were studied, including the effects of initial pH (1.5-3.0) and solid concentration (5-20%) for bioleaching, and the effects of sodium chloride (NaCl) concentration (10-200 g/L) and temperature (25 and 50 °C) for brine leaching. Complementary characterization experiments (Sequential extraction, X-ray diffractometer (XRD), scanning electronic microscope (SEM)) were also conducted to explore the transformation of tailings during the leaching process. The results showed that bioleaching efficiency was significantly influenced by initial pH and solid concentration. Approximately 85.45% of iron (Fe), 4.12% of Pb, and 97.85% of zinc (Zn) were recovered through bioleaching in optimum conditions. Increasing the brine concentration and temperature promoted lead recovery. Lead was recovered from the bioleaching residues at a rate of 94.70% at 25 °C and at a rate of 99.46% at 50 °C when the NaCl concentration was 150 g/L. The study showed that bioleaching significantly changed the speciation of heavy metals and the formation and surface morphology of tailings. The metals were mainly bound in stable fractions after bioleaching. Copyright © 2016 Elsevier Ltd. All rights reserved.

Computation of adsorption parameters for the removal of dye from wastewater by microwave assisted sawdust: Theoretical and experimental analysis.

PubMed

S, Suganya; P, Senthil Kumar; A, Saravanan; P, Sundar Rajan; C, Ravikumar

2017-03-01

In this research, the microwave assistance has been employed for the preparation of novel material from agro/natural bio-waste i.e. sawdust, for the effective removal of methylene blue (MB) dye from aqueous solution. The characterization of the newly prepared microwave assisted sawdust (MASD) material was performed by using FTIR, SEM and XRD analyses. In order to obtain the maximum removal of MB dye from wastewater, the adsorption experimental parameters such as initial dye concentration, contact time, solution pH and adsorbent dosage were optimized by trial and error approach. The obtained experimental results were applied to the different theoretical models to predict the system behaviour. The optimum conditions for the maximum removal MB dye from aqueous solution for an initial MB dye concentration of 25mg/L was calculated as: adsorbent dose of 3g/L, contact time of 90min, solution pH of 7.0 and at the temperature of 30°C. Freundlich and pseudo-second order models was best obeyed with the studied experimental data. Langmuir maximum monolayer adsorption capacity of MASD for MB dye removal was calculated as 58.14mg of MB dye/g of MASD. Adsorption diffusion model stated that the present adsorption system was controlled by intraparticle diffusion model. The obtained results proposed that, novel MASD was considered to be an effective and low-cost adsorbent material for the removal of dye from wastewater. Copyright © 2017 Elsevier B.V. All rights reserved.

Photocatalytic degradation of malathion using Zn2+-doped TiO2 nanoparticles: statistical analysis and optimization of operating parameters

NASA Astrophysics Data System (ADS)

Nasseri, Simin; Omidvar Borna, Mohammad; Esrafili, Ali; Rezaei Kalantary, Roshanak; Kakavandi, Babak; Sillanpää, Mika; Asadi, Anvar

2018-02-01

A Zn2+-doped TiO2 is successfully synthesized by a facile photodeposition method and used in the catalytic photo-degradation of organophosphorus pesticide, malathion. The obtained photocatalysts are characterized in detail by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). XRD results confirm the formation of the anatase and rutile phases for the Zn2+-doped TiO2 nanoparticles, with crystallite sizes of 12.9 nm. Zn2+-doped TiO2 that was synthesized by 3.0%wt Zn doping at 200 °C exhibited the best photocatalytic activity. 60 sets of experiments were conducted using response surface methodology (RSM) by adjusting five operating parameters, i.e. initial malathion concentration, catalyst dose, pH, reaction time at five levels and presence or absence of UV light. The analysis revealed that all considered parameters are significant in the degradation process in their linear terms. The optimum values of the variables were found to be 177.59 mg/L, 0.99 g/L, 10.99 and 81.04 min for initial malathion concentration, catalyst dose, pH and reaction time, respectively, under UV irradiation (UV ON). Under the optimized conditions, the experimental values of degradation and mineralization were 98 and 74%, respectively. Moreover, the effects of competing anions and H2O2 on photocatalyst process were also investigated.

A new morphological approach for removing acid dye from leather waste water: preparation and characterization of metal-chelated spherical particulated membranes (SPMs).

PubMed

Şenay, Raziye Hilal; Gökalp, Safiye Meriç; Türker, Evren; Feyzioğlu, Esra; Aslan, Ahmet; Akgöl, Sinan

2015-03-15

In this study, p(HEMA-GMA) poly(hydroxyethyl methacrylate-co-glycidyl methacrylate) spherical particulated membranes (SPMs) were produced by UV-photopolymerization and the synthesized SPMs were coupled with iminodiacetic acid (IDA). Finally the novel SPMs were chelated with Cr(III) ions as ligand and used for removing acid black 210 dye. Characterizations of the metal-chelated SPMs were made by SEM, FTIR and swelling test. The water absorption capacities and acid dye adsorption properties of the SPMs were investigated and the results were 245.0, 50.0, 55.0 and 51.9% for p(HEMA), p(HEMA-GMA), p(HEMA-GMA)-IDA and p(HEMA-GMA)-IDA-Cr(III) SPMs respectively. Adsorption properties of the p(HEMA-GMA)-IDA-Cr(III) SPMs were investigated under different conditions such as different initial dye concentrations and pH. The optimum pH was observed at 4.3 and the maximum adsorption capacity was determined as 885.14 mg/g at about 8000 ppm initial dye concentration. The concentrations of the dyes were determined using a UV/Vis Spectrophotometer at a wavelength of 435 nm. Reusability of p(HEMA-GMA)-IDA-Cr(III) SPMs was also shown for five adsorption-desorption cycles without considerable decrease in its adsorption capacity. Finally, the results showed that the metal-chelated p(HEMA-GMA)-IDA SPMs were effective sorbent systems removing acid dye from leather waste water. Copyright © 2014 Elsevier Ltd. All rights reserved.

Biomass recovery during municipal wastewater treatment using photosynthetic bacteria and prospect of production of single cell protein for feedstuff.

PubMed

Saejung, Chewapat; Thammaratana, Thani

2016-12-01

Utilization of photosynthetic bacteria (PSB) for wastewater treatment and production of biomass for economical single cell protein production is a feasible option. In this study, Rhodopseudomonas sp. CSK01 was used for municipal wastewater treatment and the effect of initial pH, light intensity and additional carbon source was investigated. Optimum chemical oxygen demand (COD) removal and biomass production were achieved when the initial pH and light intensity were 7 and 4000 lux, respectively. The specific growth rate, biomass yield and biomass productivity were found to be 0.4/d, 3.2 g/g COD and 2.1 g/L/d, respectively, which were improved by 100%, 167% and 200% relative to the original condition. Under the optimal conditions, COD removal reached 85% and maximum biomass was 6.2 g/L accomplished within three days of cultivation. The biomass had a relatively high protein content (60.1%) consisting of all essential amino acids. The contents of histidine, lysine, phenylalanine and leucine were superior to those of the previously described PSB. Results showed that COD removal was not improved in the presence of additional carbon sources (glucose, sucrose and malic acid). The addition of malic acid significantly increased the biomass accumulation by 279% relative to the original condition, whereas COD removal was declined due to carbon catabolite repression. In this study, PSB biomass recovery and catabolite repression are proposed in municipal wastewater treatment by Rhodopseudomonas sp.