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Sample records for oxalic acid solutions

  1. Sonolysis of an oxalic acid solution under xenon lamp irradiation.

    PubMed

    Tanaka, Hisashi; Harada, Hisashi

    2010-06-01

    The photosonolysis of oxalic acid was carried out in an Ar atmosphere. The detectable products of sonolysis were CO(2), CO, H(2), and H(2)O(2). The yield of CO(2) was higher than that for the sum of sonolysis and photolysis reactions. Namely, a synergistic effect was observed during simultaneous irradiations of 200 kHz ultrasound and Xe lamp. The degradation of oxalic acid was promoted by active species such as H(2)O(2) produced from water by sonolysis. An oxalic acid-H(2)O(2) complex is likely to be present in the solution, but could not be detected. The effects of not only the photo-irradiation but also the thermal or incident energy during Xe lamp illumination were also considered.

  2. GADOLINIUM OXALATE SOLUBILITY MEASUREMENTS IN NITRIC ACID SOLUTIONS

    SciTech Connect

    Pierce, R.

    2012-02-22

    HB-Line will begin processing Pu solutions during FY2012 that will involve the recovery of Pu using oxalate precipitation and filtration. After the precipitation and filtration processes, the filtrate solution will be transferred from HB-Line to H-Canyon. The presence of excess oxalate and unfiltered Pu oxalate solids in these solutions create a criticality safety issue if they are sent to H-Canyon without controls in H-Canyon. One approach involves H-Canyon receiving the filtrate solution into a tank that is poisoned with soluble gadolinium (Gd). Decomposition of the oxalate will occur within a subsequent H-Canyon vessel. The receipt of excess oxalate into the H-Canyon receipt tanks has the potential to precipitate a portion of the Gd poison in the receipt tanks. Because the amount of Gd in solution determines the maximum amount of Pu solids that H-Canyon can receive, H-Canyon Engineering requested that SRNL determine the solubility of Gd in aqueous solutions of 4-10 M nitric acid (HNO{sub 3}), 4-12 g/L Gd, and 0.15-0.25 M oxalic acid (H{sub 2}C{sub 2}O{sub 4}) at 25 C. The target soluble Gd concentration is 6 g/L. The data indicate that the target can be achieved above 6 M HNO{sub 3} and below 0.25 M H{sub 2}C{sub 2}O{sub 4}. For 6 M HNO{sub 3}, 10.5 g/L and 7 g/L Gd are soluble in 0.15 M and 0.25 M H{sub 2}C{sub 2}O{sub 4}, respectively. In 4 M HNO{sub 3}, the Gd solubility drops significantly to 2 g/L and 0.25 g/L in 0.15 M and 0.25 M H{sub 2}C{sub 2}O{sub 4}, respectively. The solubility of Gd at 8-10 M HNO{sub 3} exceeds the solubility at 6 M HNO{sub 3}. The data for 4 M HNO{sub 3} showed good agreement with data in the literature. To achieve a target of 6 g/L soluble Gd in solution in the presence of 0.15-0.25 M oxalate, the HNO{sub 3} concentration must be maintained at or above 6 M HNO{sub 3}.

  3. Bioavailability of oxalic acid from spinach, sugar beet fibre and a solution of sodium oxalate consumed by female volunteers.

    PubMed

    Hanson, C F; Frankos, V H; Thompson, W O

    1989-03-01

    Oxalate bioavailability from sugar beet fibre (40 g), spinach (25 g) and a solution of sodium oxalate (182 mg) was tested in nine women using a triplicated 3 x 3 Latin square arrangement. Each test substance provided 120 mg oxalic acid. Throughout the study the volunteers consumed a control diet and the test substances were administered at breakfast on specified days. After an initial 2-day control period, oxalate was administered in three test periods that consisted of one test day followed by one control day. Urine collected during 24-hr periods was analysed daily for oxalate. Oxalate excretion did not differ among the five control days and was not increased significantly following the ingestion of sugar beet fibre by the volunteers. Oxalate excretion was greater (P less than 0.0001) for the mean of the spinach and sodium oxalate solution diets than for the mean of the sugar beet fibre and control diets. Oxalate bioavailability from sugar beet fibre was 0.7% compared with bioavailabilities of 4.5 and 6.2% for spinach and oxalate solutions, respectively. The low bioavailability of oxalate from sugar beet fibre may be attributable to its high ratio of minerals (calcium and magnesium) to oxalate, its complex fibre matrix or the loss of the soluble oxalate during processing of sugar beets.

  4. GADOLINIUM OXALATE SOLUBILITY MEASUREMENTS IN NITRIC ACID SOLUTIONS

    SciTech Connect

    Pierce, R. A.

    2012-03-12

    HB-Line will begin processing Pu solutions during FY2012 that will involve the recovery of Pu using oxalate precipitation and filtration. After the precipitation and filtration processes, the filtrate solution will be transferred from HB-Line to H-Canyon. The presence of excess oxalate and unfiltered Pu oxalate solids in these solutions create a criticality safety issue if they are sent to H-Canyon without controls in H-Canyon. One approach involves H-Canyon receiving the filtrate solution into a tank that is poisoned with soluble gadolinium (Gd). Decomposition of the oxalate will occur within a subsequent H-Canyon vessel. The receipt of excess oxalate into the H-Canyon receipt tanks has the potential to precipitate a portion of the Gd poison in the receipt tanks. Because the amount of Gd in solution determines the maximum amount of Pu solids that H-Canyon can receive, H-Canyon Engineering requested that SRNL determine the solubility of Gd in aqueous solutions of 4-10 M nitric acid (HNO{sub 3}), 4-12 g/L Gd, and 0.15-0.25 M oxalic acid (H{sub 2}C{sub 2}O{sub 4}) at 25 °C. The target soluble Gd concentration is 6 g/L. The data indicate that the target can be achieved above 6 M HNO{sub 3} and below 0.25 M H{sub 2}C{sub 2}O{sub 4}. At 25 °C, for 6 M HNO{sub 3}, 11 g/L and 7 g/L Gd are soluble in 0.15 M and 0.25 M H{sub 2}C{sub 2}O{sub 4}, respectively. In 4 M HNO{sub 3}, the Gd solubility drops significantly to 2.5 g/L and 0.8 g/L in 0.15 M and 0.25 M H{sub 2}C{sub 2}O{sub 4}, respectively. The solubility of Gd at 8-10 M HNO{sub 3} exceeds the solubility at 6 M HNO{sub 3}. The data for 4 M HNO{sub 3} showed good agreement with data in the literature. To achieve a target of 6 g/L soluble Gd in solution in the presence of 0.15-0.25 M oxalate, the HNO{sub 3} concentration must be maintained at or above 6 M HNO{sub 3}. The solubility of Gd in 4 M HNO{sub 3} with 0.15 M oxalate at 10 °C is about 1.5 g/L. For 6 M HNO{sub 3} with 0.15 M oxalate, the solubility of Gd at 10

  5. [Catalytic ozonation by ceramic honeycomb for the degradation of oxalic acid in aqueous solution].

    PubMed

    Zhao, Lei; Sun, Zhi-Zhong; Ma, Jun

    2007-11-01

    Comparative experiments for the degradation of oxalic acid in aqueous solution were carried out in the three processes of ozonation alone, ceramic honeycomb-catalyzed ozonation and ceramic honeycomb adsorption. The results show that the degradation rates of oxalic acid in the ceramic honeycomb-catalyzed ozonation, ozonation alone and ceramic honeycomb adsorption systems are 37.6%, 2.2% and 0.4%, and the presence of ceramic honeycomb catalyst significantly improves the degradation rate of oxalic acid compared to the results from non-catalytic ozonation and adsorption. With the addition of tert-butanol, the degradation rates of oxalic acid in catalytic ozonation system decrease by 24.1%, 29.0% and 30.1%, respectively, at the concentration of 5, 10 and 15 mg x L(-1). This phenomenon indicates that ceramic honeycomb-catalyzed ozonation for the degradation of oxalic acid in aqueous solution follows the mechanism of *OH oxidation, namely the heterogeneous surface of catalyst enhances the initiation of *OH. The results of TOC analysis demonstrate that the process of ceramic honeycomb-catalyzed ozonation can achieve the complete mineralization level without the formation of intermediary degradation products. The experimental results suggest that the reaction temperature has positive relationship with the degradation rate of oxalic acid. The degradation rates of oxalic acid in the ceramic honeycomb-catalyzed ozonation system are 16.4%, 37.6%, 61.3% and 68.2%, at the respective reaction temperature of 10, 20, 30 and 40 degrees C.

  6. Corrosion Behavior of Alloy 22 in Oxalic Acid and Sodium Chloride Solutions

    SciTech Connect

    Day, S D; Whalen, M T; King, K J; Hust, G A; Wong, L L; Estill, J C; Rebak, R B

    2003-06-24

    Nickel based Alloy 22 (NO6022) is extensively used in aggressive industrial applications, especially due to its resistance to localized corrosion and stress corrosion cracking in high chloride environments. The purpose of this work was to characterize the anodic behavior of Alloy 22 in oxalic acid solution and to compare its behavior to sodium chloride (NaCl) solutions. Standard electrochemical tests such as polarization resistance and cyclic polarization were used. Results show that the corrosion rate of Alloy 22 in oxalic acid solutions increased rapidly as the temperature and the acid concentration increased. Extrapolation studies show that even at a concentration of 10{sup -4}M oxalic acid, the corrosion rate of Alloy 22 would be higher in oxalic acid than in 1 M NaCl solution. Alloy 22 was not susceptible to localized corrosion in oxalic acid solutions. Cyclic polarization tests in 1 M NaCl showed that Alloy 22 was susceptible to crevice corrosion at 90 C but was not susceptible at 60 C.

  7. SAVANNAH RIVER SITE TANK CLEANING: CORROSION RATE FOR ONE VERSUS EIGHT PERCENT OXALIC ACID SOLUTION

    SciTech Connect

    Ketusky, E.; Subramanian, K.

    2011-01-20

    Until recently, the use of oxalic acid for chemically cleaning the Savannah River Site (SRS) radioactive waste tanks focused on using concentrated 4 and 8-wt% solutions. Recent testing and research on applicable dissolution mechanisms have concluded that under appropriate conditions, dilute solutions of oxalic acid (i.e., 1-wt%) may be more effective. Based on the need to maximize cleaning effectiveness, coupled with the need to minimize downstream impacts, SRS is now developing plans for using a 1-wt% oxalic acid solution. A technology gap associated with using a 1-wt% oxalic acid solution was a dearth of suitable corrosion data. Assuming oxalic acid's passivation of carbon steel was proportional to the free oxalate concentration, the general corrosion rate (CR) from a 1-wt% solution may not be bound by those from 8-wt%. Therefore, after developing the test strategy and plan, the corrosion testing was performed. Starting with the envisioned process specific baseline solvent, a 1-wt% oxalic acid solution, with sludge (limited to Purex type sludge-simulant for this initial effort) at 75 C and agitated, the corrosion rate (CR) was determined from the measured weight loss of the exposed coupon. Environmental variations tested were: (a) Inclusion of sludge in the test vessel or assuming a pure oxalic acid solution; (b) acid solution temperature maintained at 75 or 45 C; and (c) agitation of the acid solution or stagnant. Application of select electrochemical testing (EC) explored the impact of each variation on the passivation mechanisms and confirmed the CR. The 1-wt% results were then compared to those from the 8-wt%. The immersion coupons showed that the maximum time averaged CR for a 1-wt% solution with sludge was less than 25-mils/yr for all conditions. For an agitated 8-wt% solution with sludge, the maximum time averaged CR was about 30-mils/yr at 50 C, and 86-mils/yr at 75 C. Both the 1-wt% and the 8-wt% testing demonstrated that if the sludge was removed from

  8. Oxalic acid complexes: promising draw solutes for forward osmosis (FO) in protein enrichment.

    PubMed

    Ge, Qingchun; Chung, Tai-Shung

    2015-03-21

    Highly soluble oxalic acid complexes (OACs) were synthesized through a one-pot reaction. The OACs exhibit excellent performance as draw solutes in FO processes with high water fluxes and negligible reverse solute fluxes. Efficient protein enrichment was achieved. The diluted OACs can be recycled via nanofiltration and are promising as draw solutes.

  9. [Analysis of oxalic acid and oxalates].

    PubMed

    Leskovar, P

    1979-08-01

    It is reported on individual methods for the estimation of the oxalic acid in body fluids, particularly in the urine. The case in question is a survey of the oxalate estimation methods, which, however, has no pretensions to completeness. The at present most actualestimation methods are brought somewhat more in detail. The data are not sufficient for the laboratorytechnical performance of the individual methods, this would transgress the possibilities of the work. However, the original papers are cited which contain all the necessary details. Some technical difficulties and disturbances in the individual estimation methods are also entered. Despite excellent work of several teams the problems of standardization, of the absolutely reliable reference methoda as well as of an objective consideration of advantages and disadvantages of individual, often subjectively judged methods is not yet solved. Comparing these methods, one gets the impression that several reliable methods of the same value are established. It seems that this estimation method brings the greatest progress which will reliably establish so small quantities of oxalate as they are in the blood or in the liquor. By this also the oxalate clearance and the renal oxalate treatment becomes more exactly establishable than up to now.

  10. Porous aluminum room temperature anodizing process in a fluorinated-oxalic acid solution

    NASA Astrophysics Data System (ADS)

    Dhahri, S.; Fazio, E.; Barreca, F.; Neri, F.; Ezzaouia, H.

    2016-08-01

    Anodizing of aluminum is used for producing porous insulating films suitable for different applications in electronics and microelectronics. Porous-type aluminum films are most simply realized by galvanostatic anodizing in aqueous acidic solutions. The improvement in application of anodizing technique is associated with a substantial reduction of the anodizing voltage at appropriate current densities as well as to the possibility to carry out the synthesis process at room temperature in order to obtain a self-planarizing dielectric material incorporated in array of super-narrow metal lines. In this work, the anodizing of aluminum to obtain porous oxide was carried out, at room temperature, on three different substrates (glass, stainless steel and aluminum), using an oxalic acid-based electrolyte with the addition of a relatively low amount of 0.4 % of HF. Different surface morphologies, from nearly spherical to larger porous nanostructures with smooth edges, were observed by means of scanning electron microscopy. These evidences are explained by considering the formation, transport and adsorption of the fluorine species which react with the Al3+ ions. The behavior is also influenced by the nature of the original substrate.

  11. Mechanisms of enhanced total organic carbon elimination from oxalic acid solutions by electro-peroxone process.

    PubMed

    Wang, Huijiao; Yuan, Shi; Zhan, Juhong; Wang, Yujue; Yu, Gang; Deng, Shubo; Huang, Jun; Wang, Bin

    2015-09-01

    Electro-peroxone (E-peroxone) is a novel electrocatalytic ozonation process that combines ozonation and electrolysis process to enhance pollutant degradation during water and wastewater treatment. This enhancement has been mainly attributed to several mechanisms that increase O3 transformation to ·OH in the E-peroxone system, e.g., electro-generation of H2O2 from O2 at a carbon-based cathode and its subsequent peroxone reaction with O3 to ·OH, electro-reduction of O3 to ·OH at the cathode, and O3 decomposition to ·OH at high local pH near the cathode. To get more insight how these mechanisms contribute respectively to the enhancement, this study investigated total organic carbon (TOC) elimination from oxalic acid (OA) solutions by the E-peroxone process. Results show that the E-peroxone process significantly increased TOC elimination rate by 10.2-12.5 times compared with the linear addition of the individual rates of corresponding ozonation and electrolysis process. Kinetic analyses reveal that the electrochemically-driven peroxone reaction is the most important mechanism for the enhanced TOC elimination rate, while the other mechanisms contribute minor to the enhancement by a factor of 1.6-2.5. The results indicate that proper selection of electrodes that can effectively produce H2O2 at the cathode is critical to maximize TOC elimination in the E-peroxone process.

  12. ELECTROCHEMICAL STUDIES ON THE CORROSION OF CARBON STEEL IN OXALIC ACID CLEANING SOLUTIONS

    SciTech Connect

    Wiersma, B; John Mickalonis, J

    2007-10-08

    The Savannah River Site (SRS) will disperse or dissolve precipitated metal oxides as part of radioactive waste tank closure operations. Previously SRS has utilized oxalic acid to accomplish this task. Since the waste tanks are constructed of carbon steel, a significant amount of corrosion may occur. Although the total amount of corrosion may be insignificant for a short contact time, a significant amount of hydrogen may be generated due to the corrosion reaction. Linear polarization resistance and anodic/cathodic polarization tests were performed to investigate the corrosion behavior during the process. The effect of process variables such as temperature, agitation, aeration, sample orientation, light as well as surface finish on the corrosion behavior were evaluated. The results of the tests provided insight into the corrosion mechanism for the iron-oxalic acid system.

  13. CORROSION TESTING OF CARBON STEEL IN OXALIC ACID CHEMICAL CLEANING SOLUTIONS

    SciTech Connect

    Wiersma, B.; Mickalonis, J.; Subramanian, K.; Ketusky, E.

    2011-10-14

    Radioactive liquid waste has been stored in underground carbon steel tanks for nearly 60 years at the Savannah River Site. The site is currently in the process of removing the waste from these tanks in order to place it into vitrified, stable state for longer term storage. The last stage in the removal sequence is a chemical cleaning step that breaks up and dissolves metal oxide solids that cannot be easily pumped out of the tank. Oxalic acid has been selected for this purpose because it is an effective chelating agent for the solids and is not as corrosive as other acids. Electrochemical and immersion studies were conducted to investigate the corrosion behavior of carbon steel in simulated chemical cleaning environments. The effects of temperature, agitation, and the presence of sludge solids in the oxalic acid on the corrosion rate and the likelihood of hydrogen evolution were determined. The testing showed that the corrosion rates decreased significantly in the presence of the sludge solids. Corrosion rates increased with agitation, however, the changes were less noticeable.

  14. Degradation of 17beta-estradiol in aqueous solution by ozonation in the presence of manganese(II) and oxalic acid.

    PubMed

    Jiang, Liying; Zhang, Lu; Chen, Jianmeng; Ji, Hong

    2013-01-01

    Natural estrogens, such as 17beta-estradiol (E2), are the main substances responsible for estrogenic activity found in domestic sewage. In the work described herein, the degradation of E2 has been investigated by single ozonation and catalytic ozonation in the presence of manganese ion (Mn2+) and oxalic acid. The presence of Mn2+ and oxalic acid in the ozonation processes significantly improved the E2 degradation and, hence, the reduction of estrogenic activity in aqueous solution. The addition of Mn2+ and oxalic acid produced many more hydroxyl radicals in the catalytic ozonation system than in the single ozonation system. Oxidation products formed during ozonation of E2 have been identified by means of gas chromatography-mass spectrometry (GC-MS), on the basis of which a possible reaction pathway for E2 degradation by ozonation is proposed. E2 was first oxidized to hydroxyl-semiquinone isomers, and these were subsequently degraded to low molecular weight compounds such as oxalic acid and malonic acid. The latter were easily oxidized by ozone to form carbon dioxide (CO2). The results demonstrate that the ozonation-Mn(2+)-oxalic acid system may serve as a powerful tool for removing E2, and the addition of Mn2+ and oxalic acid is favourable for the complete removal of estrogenic activity induced by steroid estrogens in aqueous solution.

  15. [Characterization and analysis of direction extraction and precipitation of cerium loading organic phase by oxalic acid solution].

    PubMed

    Mei, Yan; Xia, Chuan; Chen, Xiao-Li; Sun, He; Nie, Zuo-Ren

    2011-11-01

    In the condition of sodium hydroxide saponification, the test results using direction extraction and precipitation of cerium from P507 loading organic phase by oxalic acid solution were studied. Infared (IR) spectrum, X-ray diffraction (XRD), transmission electron microscope (TEM) and thermogravimetry (TG-DSC) were used to study and characterize organic cerium precipitates and the final calcined products. The results showed that organic cerium precipitates and final calcined products were spheric organic cerium coordination and spheric cube CeO2 crystal, respectively, showing their morphologies were successive. IR made out that the structures of organic cerium precipitates and final calcined products were different. TG-DSC indicated that the final calcined products weightlessness was 3.5% and chemical composing was CeO2 x 1/3H2O.

  16. Measurements of oxalic acid, oxalates, malonic acid, and malonates in atmospheric particulates.

    PubMed

    Yang, Liming; Yu, Liya E

    2008-12-15

    This study systematically examined effects of analytical approaches on resultant concentrations of oxalic acid, oxalates, malonic acid, and malonates. Results demonstrated that employing separate water extraction and THF extraction is required to properly quantify dicarboxylic acids vs dicarboxylates using IC or GC-MS. Applications of the recommended methods to analyze PM2.5 collected in Singapore showed that concentrations of oxalate ranged from 361.4 to 481.4 ng m(-3), which were 10-14.7 times higher than that of oxalic acid. Unlike that of oxalates, malonate concentrations (10.5-23.4 ng m(-3)) were no more than half of malonic acid concentration (43.8-53.9 ng m(-3)) in PM2.5. Concentration ratios of oxalate-to-oxalic acid and malonate-to-malonic acid obtained from this work were applied to reported literature data; as a first approximation, in urban environments similar to that in Singapore, quantifiable oxalic acid, oxalates, malonic acid, and malonates in PM2.5 could range from 7.6 to 68.0, 82.2 to 732.8, 6.3 to 150, and 1.3 to 60 ng m(-3), respectively. Because photooxidation properties and hygroscopicity of dicarboxylic acids can substantially differ from that of dicarboxylates, more studies are needed to quantify ambient oxalic acid and malonic acid vs oxalates and malonates.

  17. Metabolic Conversion of l-Ascorbic Acid to Oxalic Acid in Oxalate-accumulating Plants.

    PubMed

    Yang, J C; Loewus, F A

    1975-08-01

    l-Ascorbic acid-1-(14)C and its oxidation product, dehydro-l-ascorbic acid, produced labeled oxalic acid in oxalate-accumulating plants such as spinach seedlings (Spinacia oleracea) and the detached leaves of woodsorrel (Oxalis stricta and O. oregana), shamrock (Oxalis adenopylla), and begonia (Begonia evansiana). In O. oregana, conversion occurred equally well in the presence or absence of light. This relationship between l-ascorbic acid metabolism and oxalic acid formation must be given careful consideration in attempts to explain oxalic accumulation in plants.

  18. Metabolic Conversion of l-Ascorbic Acid to Oxalic Acid in Oxalate-accumulating Plants 1

    PubMed Central

    Yang, Joan C.; Loewus, Frank A.

    1975-01-01

    l-Ascorbic acid-1-14C and its oxidation product, dehydro-l-ascorbic acid, produced labeled oxalic acid in oxalate-accumulating plants such as spinach seedlings (Spinacia oleracea) and the detached leaves of woodsorrel (Oxalis stricta and O. oregana), shamrock (Oxalis adenopylla), and begonia (Begonia evansiana). In O. oregana, conversion occurred equally well in the presence or absence of light. This relationship between l-ascorbic acid metabolism and oxalic acid formation must be given careful consideration in attempts to explain oxalic accumulation in plants. PMID:16659288

  19. A ratiometric fluorescent probe for oxalate based on alkyne-conjugated carboxamidoquinolines in aqueous solution and imaging in living cells.

    PubMed

    He, Chunsheng; Qian, Xuhong; Xu, Yufang; Yang, Chunmei; Yin, Liyan; Zhu, Weiping

    2011-02-07

    A novel ratiometric fluorescent probe for oxalic acid was designed and synthesized, based on the zinc-containing [DAQZ@2Zn(2+)] complex. It shows highly selective "on-off" fluorescence changes with a more than 20 nm blue shift in wavelength for oxalic acids in aqueous solution. Moreover, it can fluorescently respond to oxalic acid in living cells.

  20. Oxalic acid enhances Cr tolerance in the accumulating plant Leersia hexandra Swartz.

    PubMed

    Wang, Dunqiu; Zhang, Xuehong; Liu, Jie; Zhu, Yinian; Zhang, Hui; Zhang, Aili; Jin, Xiaodan

    2012-12-01

    This study examined the relationship between oxalic acid and Cr tolerance in an accumulating plant Leersia hexandra Swartz. The plants grown in hydroponics were exposed to Cr at 0, 5, 30, and 60 mg/L (without oxalate), and 0, 40, and 80 mg/L concentrations of Cr (with 70 mg/L oxalate or without oxalate). The results showed that more than 50% of Cr in shoots was found in HCl-extracted fraction (chromium oxalate) when the plants were exposed to Cr. Cr supply significantly increased oxalate concentration in shoots of L. hexandra (p < 0.05), but did not increase oxalate concentration in roots. Under 80 mg/L Cr stress, electrolyte leakages from roots and shoots with oxalate treatment were both significantly lower than those without oxalate treatment (p < 0.05), indicating exogenous oxalate supply alleviated Cr-induced membrane damage. Oxalate added to growth solution ameliorated reduction of biomass and inhibition of root growth induced by Cr, which demonstrated that application of oxalate helped L. hexandra tolerate Cr stress. However, oxalate supply did not affect the Cr concentrations both in roots and shoots of L. hexandra. These results suggest that oxalic acid may act as an important chelator and takes part in detoxifying chromium in internal process of L. hexandra.

  1. Oxalic acid excretion after intravenous ascorbic acid administration.

    PubMed

    Robitaille, Line; Mamer, Orval A; Miller, Wilson H; Levine, Mark; Assouline, Sarit; Melnychuk, David; Rousseau, Caroline; Hoffer, L John

    2009-02-01

    Ascorbic acid is frequently administered intravenously by alternative health practitioners and, occasionally, by mainstream physicians. Intravenous administration can greatly increase the amount of ascorbic acid that reaches the circulation, potentially increasing the risk of oxalate crystallization in the urinary space. To investigate this possibility, we developed gas chromatography mass spectrometry methodology and sampling and storage procedures for oxalic acid analysis without interference from ascorbic acid and measured urinary oxalic acid excretion in people administered intravenous ascorbic acid in doses ranging from 0.2 to 1.5 g/kg body weight. In vitro oxidation of ascorbic acid to oxalic acid did not occur when urine samples were brought immediately to pH less than 2 and stored at -30 degrees C within 6 hours. Even very high ascorbic acid concentrations did not interfere with the analysis when oxalic acid extraction was carried out at pH 1. As measured during and over the 6 hours after ascorbic acid infusions, urinary oxalic acid excretion increased with increasing doses, reaching approximately 80 mg at a dose of approximately 100 g. We conclude that, when studied using correct procedures for sample handling, storage, and analysis, less than 0.5% of a very large intravenous dose of ascorbic acid is recovered as urinary oxalic acid in people with normal renal function.

  2. Kinetics of Mo, Ni, V and Al leaching from a spent hydrodesulphurization catalyst in a solution containing oxalic acid and hydrogen peroxide.

    PubMed

    Szymczycha-Madeja, Anna

    2011-02-28

    The kinetics of molybdenum, nickel, vanadium and aluminium leaching from a spent hydrodesulphurization catalyst in a solution containing oxalic acid and hydrogen peroxide was investigated. The effects of temperature and particle size were examined. In addition, the reaction mechanism for the dissolution of the spent catalyst was discussed. The results of the kinetic analysis for various experimental conditions indicated that the reaction rate of leaching process is controlled by chemical reaction at the particle surface. The values of the activation energies of 31±2, 36±4, 30±4 and 57±3 kJ mol(-1) for Mo, Ni, V and Al, respectively, are characteristic for mechanism controlled by chemical reaction.

  3. Adsorption of dyestuff from aqueous solutions through oxalic acid-modified swede rape straw: adsorption process and disposal methodology of depleted bioadsorbents.

    PubMed

    Feng, Yanfang; Dionysiou, Dionysios D; Wu, Yonghong; Zhou, Hui; Xue, Lihong; He, Shiying; Yang, Linzhang

    2013-06-01

    Swede rape straw (Brassica napus L.) was modified by oxalic acid under mild conditions producing an efficient dye adsorbent (SRSOA). This low-cost and environmental friendly bioadsorbent was characterized by various techniques and then applied to purify dye-contaminated aqueous solutions. Equilibrium study showed that the Langmuir model demonstrated the best fit to the equilibrium data and the methylene blue (MB) adsorption capacity calculated by this model was 432mgg(-1). The adsorption process and mechanism is also discussed. To properly deal with the dye-loaded bioadsorbents, the disposal methodology is discussed and a biochar based on depleted bioadsorbents was for the first time produced and examined. This method both solved the disposal problem of contaminant-loaded bioadsorbents and produced an useful adsorbent thereafter. The study indicates that SRSOA is a promising substitute for ACs in purifying dye-contaminated wastewater and that producing biochars from contaminant-loaded bioadsorbents maybe a feasible disposal method.

  4. Gas chromatographic determination of oxalic acid in foods.

    PubMed

    Ohkawa, H

    1985-01-01

    A new quantitative gas chromatographic (GC) method has been developed for the determination of oxalic acid in foods. Solid sample is extracted with water (soluble oxalic acid) or 2N hydrochloric acid (total oxalic acid) at room temperature. An aliquot of sample extract is evaporated to dryness, and the oxalic acid in the residue is methylated with 7% hydrochloric acid-methanol. The reaction mixture is extracted with chloroform, and dimethyl oxalate is quantitated by GC. Recovery of oxalic acid added to liquid samples averaged 100.6%; recoveries from extracts of solid samples were 96.2-99.5 and 97.2-100.1% for water and hydrochloric acid extractions, respectively. Results are shown for determination of oxalic acid in spinach and beverages. The technique is simple, rapid, and accurate, and small samples may be used. The limit of determination is 20 micrograms.

  5. Modulation of polyepoxysuccinic acid on crystallization of calcium oxalate

    SciTech Connect

    Zhang, Yanqing; Tang, Yongming; Xu, Jinqiu; Zhang, Dongqin; Lu, Gang; Jing, Wenheng

    2015-11-15

    The influence of polyepoxysuccinic acid (PESA) on the phase composition and crystal morphology of calcium oxalate was investigated in this paper. It was found that the presence of PESA inhibited the growth of the monoclinic calcium oxalate monohydrate (COM) crystal and promoted the nucleation of the tetragonal calcium oxalate dihydrate (COD). In addition, with the increase in PESA concentration, the aggregation of COD crystals was reduced but the particle size was increased. Under the conditions of low calcium-to-oxalate ratio and high CaOx concentration, PESA could not effectively stabilize the formation of COD. Based on molecular dynamic simulations, the adsorption of PESA on CaOx crystal faces was confirmed. - Graphical abstract: Introduction of PESA into crystallization solutions promotes the formation of calcium oxalate dehydrate and modifies the morphology of crystals. - Highlights: • PESA induces the formation of COD at low supersaturation. • Establishment of Ca-rich surface augments the adsorption of PESA. • At Ca/Ox=0.5 PESA cannot induce the formation of COD compared with Ca/Ox=2. • Interaction of PESA with COM faces is stronger than that with COD faces.

  6. [Formation of oxalate in oxaliplatin injection diluted with infusion solutions].

    PubMed

    Eto, Seiji; Yamamoto, Kie; Shimazu, Kounosuke; Sugiura, Toshimune; Baba, Kaori; Sato, Ayaka; Goromaru, Takeshi; Hagiwara, Yoshiaki; Hara, Keiko; Shinohara, Yoshitake; Takahashi, Kojiro

    2014-01-01

    Oxaliplatin use can cause acute peripheral neuropathy characterized by sensory paresthesias, which are markedly exacerbated by exposure to cold temperatures, and is a dose-limiting factor in the treatment of colorectal cancer.Oxalate is eliminated in a series of nonenzymatic conversions of oxaliplatin in infusion solutions or biological fluids.Elimination of oxalate from oxaliplatin has been suggested as one of the reasons for the development of acute neuropathy.In this study, we developed a high-performance liquid chromatography(HPLC)-based method to detect oxalate formation, and investigated the time dependent formation of oxalate in oxaliplatin diluted with infusion solutions.The results obtained showed that the amount of oxalate in the solution corresponded to 1.6% of oxaliplatin 8 h after oxaliplatin dilution with a 5% glucose solution. On the other hand, oxalate formation from oxaliplatin diluted with a saline solution was ten-fold higher than that from oxaliplatin diluted with the 5% glucose solution.Most patients who were intravenously injected with oxaliplatin experienced venous pain.As a preventive measure against venous pain, dexamethasone was added to the oxaliplatin injection.We measured the amount of oxalate formed in the dexamethasone-containing oxaliplatin injection diluted with a 5% glucose solution.The amount of oxalate formed when dexamethasone was added did not differ significantly from that formed when dexamethasone was not added.Thus, there are no clinical problems associated with the stability of oxaliplatin solutions.

  7. Oxalic acid mineralization by electrochemical oxidation processes.

    PubMed

    Huang, Yao-Hui; Shih, Yu-Jen; Liu, Cheng-Hong

    2011-04-15

    In this study, two electrochemical oxidation processes were utilized to mineralize oxalic acid which was a major intermediate compound in the oxidation of phenols and other aromatic compounds. The anode rod and cathode net were made of a titanium coated with RuO(2)/IrO(2) (Ti-DSA) and stainless steel (S.S. net, SUS304), respectively. First, the Fered-Fenton process, which used H(2)O(2) and Fe(2+) as additive reagents, achieved 85% of TOC removal. It proceeded with ligand-to-metal charge-transfer (LMCT), which was evidenced by the accumulation of metallic foil on the selected cathode. However, in the absence of H(2)O(2)/Fe(2+), it showed a higher TOC removal efficiency while using Cl(-) only as an additive reagent due to the formation of hypochlorite on the anode. It was also found that the mineralization of oxalic acid by electrolysis generated hypochlorite better than the dosage of commercial hypochlorite without electricity. Also, pH value was a major factor that affected the mineralization efficiency of the oxalic acid due to the chlorine chemistry. 99% TOC removal could be obtained by Cl(-) electrolysis in an acidic environment.

  8. Red facts: Oxalic acid. Fact sheet

    SciTech Connect

    Not Available

    1992-12-01

    All pesticides sold or used in the United States must be registered by EPA, based on scientific studies showing that they can be used without posing unreasonable risks to people or the environment. Because of advances in scientific knowledge, the law requires that pesticides which were first registered years ago be reregistered to ensure that they meet today's more stringent standards. Oxalic acid is registered for use as a disinfectant to control bacteria and germs, and as a sanitizer, in toilet bowls, urinals and bathroom premises. Oxalic acid also has many diverse, non-pesticidal, manufacturing and industrial uses including use in fabric printing and dyeing; bleaching straw hats; removing paint, varnish, rust or ink stains; and cleaning wood.

  9. Interaction between oxalic acid and titania in aqueous ethanol dispersions.

    PubMed

    Dahlsten, Per; Rosenholm, Jarl B

    2013-02-15

    The charging effects resulting from adsorption of oxalic acid and oxalate anions on titania (anatase) surfaces in anhydrous or mixed water-ethanol suspensions is summarized. The suddenly enhanced electrical conductance with respect to titania free solutions has previously been explained in terms of surface-induced electrolytic dissociation (SIED) of weak acids. A recently published model has previously been found to successfully characterize the complex SIED effect. The model is evaluated experimentally by recording the conductance and pH of the dispersion and the zeta potential of the particles. The experimental results can be condensed to master curves, which reveal the major properties of the systems and facilitate further modeling of extensive experimental results. The equilibrium and transport properties of solutions and particles were related, but different mechanisms was found to be active in each case. The results suggest that at least three adsorption equilibria should be considered in order to improve the model.

  10. Effect of oxalic acid treatment on sediment arsenic concentrations and lability under reducing conditions.

    PubMed

    Sun, Jing; Bostick, Benjamin C; Mailloux, Brian J; Ross, James M; Chillrud, Steven N

    2016-07-05

    Oxalic acid enhances arsenic (As) mobilization by dissolving As host minerals and competing for sorption sites. Oxalic acid amendments thus could potentially improve the efficiency of widely used pump-and-treat (P&T) remediation. This study investigates the effectiveness of oxalic acid on As mobilization from contaminated sediments with different As input sources and redox conditions, and examines whether residual sediment As after oxalic acid treatment can still be reductively mobilized. Batch extraction, column, and microcosm experiments were performed in the laboratory using sediments from the Dover Municipal Landfill and the Vineland Chemical Company Superfund sites. Oxalic acid mobilized As from both Dover and Vineland sediments, although the efficiency rates were different. The residual As in both Dover and Vineland sediments after oxalic acid treatment was less vulnerable to microbial reduction than before the treatment. Oxalic acid could thus improve the efficiency of P&T. X-ray absorption spectroscopy analysis indicated that the Vineland sediment samples still contained reactive Fe(III) minerals after oxalic acid treatment, and thus released more As into solution under reducing conditions than the treated Dover samples. Therefore, the efficacy of enhanced P&T must consider sediment Fe mineralogy when evaluating its overall potential for remediating groundwater As.

  11. The function of oxalic acid in the human metabolism.

    PubMed

    Robertson, Daniel Stewart

    2011-09-01

    Biochemical reactions in cells which involve oxalic acid are described. It is shown that this compound is required for the formation of uracil and orotic acid. The former is a component of RNA which is common to all cells in the human metabolism. On the basis of the biochemical reactions described a possible treatment to relieve the effects of calcium oxalate renal calculi whose origin is related to the metabolic concentration of oxalic acid is proposed.

  12. Catalytic kinetic spectrophotometry for the determination of trace amount of oxalic acid in biological samples with oxalic acid-rhodamine B-potassium dichromate system

    NASA Astrophysics Data System (ADS)

    Zhai, Qing-Zhou; Zhang, Xiao-Xia; Liu, Qing-Zhou

    2006-09-01

    A new catalytic kinetic spectrophotometric method was proposed for determining trace oxalic acid based on the catalytic effect of oxalate on the oxidation of potassium dichromate with rhodamin B in 0.10 M of sulfuric acid. Good linearity is obtained over the concentration range 0.40-6.0 μg/mL of oxalic acid. After the reactions of the catalytic and non-catalytic systems were terminated by using 2.00 mL of 4 M sodium hydroxide solution, they can be stable for 3 h at room temperature. The apparent activation energy of the catalytic reaction is 12.44 kJ/mol. The effect of 50 coexisting substances was observed. The method was used to determine trace oxalic acid in tea, spinach and urine samples with satisfactory results.

  13. Catalytic kinetic spectrophotometry for the determination of trace amount of oxalic acid in biological samples with oxalic acid-rhodamine B-potassium dichromate system.

    PubMed

    Zhai, Qing-Zhou; Zhang, Xiao-Xia; Liu, Qing-Zhou

    2006-09-01

    A new catalytic kinetic spectrophotometric method was proposed for determining trace oxalic acid based on the catalytic effect of oxalate on the oxidation of potassium dichromate with rhodamin B in 0.10 M of sulfuric acid. Good linearity is obtained over the concentration range 0.40-6.0 microg/mL of oxalic acid. After the reactions of the catalytic and non-catalytic systems were terminated by using 2.00 mL of 4 M sodium hydroxide solution, they can be stable for 3 h at room temperature. The apparent activation energy of the catalytic reaction is 12.44 kJ/mol. The effect of 50 coexisting substances was observed. The method was used to determine trace oxalic acid in tea, spinach and urine samples with satisfactory results.

  14. Reregistration eligibility document (RED): Oxalic acid

    SciTech Connect

    Not Available

    1992-12-01

    EPA is directed by the Federal Insecticide, Fungicide, and Rodenticide Act as amended in 1988 (FIFRA '88) to review all pesticide products containing active ingredients initially registered before November 1, 1984, and to reregister those products that have a substantially complete data base and do not pose unreasonable adverse effects to people or the environment. This pesticide reregistration program is to be completed by the late 1990's. The Reregistration Eligibility Document (or RED) for oxalic acid discusses the scientific data and other information supporting EPA's regulatory conclusion that products containing a pesticide do not pose unreasonable risks when used as directed by Agency-approved labeling, and are eligible for reregistration.

  15. Characterization of oxalic acid pretreatment on lignocellulosic biomass using oxalic acid recovered by electrodialysis.

    PubMed

    Lee, Hong-Joo; Seo, Young-Jun; Lee, Jae-Won

    2013-04-01

    The properties of pretreated biomass and hydrolysate obtained by oxalic acid pretreatment using oxalic acid recovered through electrodialysis (ED) were investigated. Most of the oxalic acid was recovered and some of the fermentation inhibitors were removed by ED. For the original hydrolysate, the ethanol production was very low and fermentable sugars were not completely consumed by Pichia stipitis during fermentation. Ethanol yield was less than 0.12 g/g in all stage. For the ED-treated hydrolysate, ethanol production was increased by up to two times in all stages compared to the original hydrolysate. The highest ethanol production was 19.38 g/l after 72 h which correspond to the ethanol yield of 0.33 g/g. Enzymatic conversion of the cellulose to glucose for all the pretreated biomass was in the range of 76.03 and 77.63%. The hydrolysis rate on each pretreated biomass was not significantly changed when oxalic acid recovered by ED was used for pretreatment.

  16. EFFECTIVENESS OF USING DILUTE OXALIC ACID TO DISSOLVEHIGH LEVEL WASTE IRON BASED SLUDGE SIMULANT

    SciTech Connect

    Ketusky, E

    2008-07-11

    At the Savannah River Site (SRS), near Aiken South Carolina, there is a crucial need to remove residual quantities of highly radioactive iron-based sludge from large select underground storage tanks (e.g., 19,000 liters of sludge per tank), in order to support tank closure. The use of oxalic acid is planned to dissolve the residual sludge, hence, helping in the removal. Based on rigorous testing, primarily using 4 and 8 wt% oxalic acid solutions, it was concluded that the more concentrated the acid, the greater the amount of residual sludge that would be dissolved; hence, a baseline technology on using 8 wt% oxalic acid was developed. In stark contrast to the baseline technology, reports from other industries suggest that the dissolution will most effectively occur at 1 wt% oxalic acid (i.e., maintaining the pH near 2). The driver for using less oxalic acid is that less (i.e., moles) would decrease the severity of the downstream impacts (i.e., required oxalate solids removal efforts). To determine the initial feasibility of using 1 wt% acid to dissolve > 90% of the sludge solids, about 19,000 liters of representative sludge was modeled using about 530,000 liters of 0 to 8 wt% oxalic acid solutions. With the chemical thermodynamic equilibrium based software results showing that 1 wt% oxalic acid could theoretically work, simulant dissolution testing was initiated. For the dissolution testing, existing simulant was obtained, and an approximate 20 liter test rig was built. Multiple batch dissolutions of both wet and air-dried simulant were performed. Overall, the testing showed that dilute oxalic acid dissolved a greater fraction of the stimulant and resulted in a significantly larger acid effectiveness (i.e., grams of sludge dissolved/mole of acid) than the baseline technology. With the potential effectiveness confirmed via simulant testing, additional testing, including radioactive sludge testing, is planned.

  17. Growth Conditions To Reduce Oxalic Acid Content of Spinach

    NASA Technical Reports Server (NTRS)

    Johnson-Rutzke, Corinne

    2003-01-01

    A controlled-environment agricultural (CEA) technique to increase the nutritive value of spinach has been developed. This technique makes it possible to reduce the concentration of oxalic acid in spinach leaves. It is desirable to reduce the oxalic acid content because oxalic acid acts as an anti-nutritive calcium-binding component. More than 30 years ago, an enzyme (an oxidase) that breaks down oxalic acid into CO2 and H2O2 was discovered and found to be naturally present in spinach leaves. However, nitrate, which can also be present because of the use of common nitratebased fertilizers, inactivates the enzyme. In the CEA technique, one cuts off the supply of nitrate and keeps the spinach plants cool while providing sufficient oxygen. This technique provides the precise environment that enables the enzyme to naturally break down oxalate. The result of application of this technique is that the oxalate content is reduced by 2/3 in one week.

  18. Oxalic acid degradation by a novel fungal oxalate oxidase from Abortiporus biennis.

    PubMed

    Grąz, Marcin; Rachwał, Kamila; Zan, Radosław; Jarosz-Wilkołazka, Anna

    2016-01-01

    Oxalate oxidase was identified in mycelial extracts of a basidiomycete Abortiporus biennis strain. Intracellular enzyme activity was detected only after prior lowering of the pH value of the fungal cultures by using oxalic or hydrochloric acids. This enzyme was purified using size exclusion chromatography (Sephadex G-25) and ion-exchange chromatography (DEAE-Sepharose). This enzyme exhibited optimum activity at pH 2 when incubated at 40°C, and the optimum temperature was established at 60°C. Among the tested organic acids, this enzyme exhibited specificity only towards oxalic acid. Molecular mass was calculated as 58 kDa. The values of Km for oxalate and Vmax for the enzyme reaction were 0.015 M and 30 mmol min(-1), respectively.

  19. Effect of Oxalate on the Recycle of Neptunium Filtrate Solution by Anion Exchange

    SciTech Connect

    Kyser, E

    2004-11-18

    A series of laboratory column runs has been performed that demonstrates the recovery of neptunium (Np) containing up to 0.05 M oxalate. Np losses were generally less than one percent to the raffinate for feed solutions that contained 2 to 10 g Np/L. Up to 16 percent Np losses were observed with lower Np feed concentrations, but those losses were attributed to the shortened residence times rather than the higher oxalate to Np ratios. Losses in the plant are expected to be significantly less due to the lower cross-section flowrate possible with existing plant pumps. Elimination of the permanganate treatment of filtrates appears to be reasonable since the amount of Np in those filtrates does not appear to be practical to recover. Combination of untreated filtrates with other actinide rich solutions is not advisable as precipitation problems are likely. If untreated filtrates are kept segregated from other actinide rich streams, the recovery of the remaining Np is probably still possible, but could be limited due to the excessively high oxalate to Np ratio. The persistence of hydrazine/hydrazoic acid in filtrate solutions dictates that the nitrite treatment be retained to eliminate those species from the filtrates prior to transfer to the canyon. Elimination of the permanganate treatment of precipitator flushes and recovery by anion exchange does not appear to be limited by the oxalate effect on anion exchange. Np from solutions with higher oxalate to Np molar ratios than expected in precipitator flushes was recovered with low to modest losses. Solubility problems appear to be unlikely when the moles of oxalate involved are less than the total number of moles of Np due to complexation effects. The presence of significant concentrations of iron (Fe) in the solutions will further decrease the probability of Np oxalate precipitation due the formation of Fe oxalate complexes. Np oxalate solubility data in 8 M HNO{sub 3} with from one to six times as much oxalate as Np have

  20. Oxalic acid in saliva, teeth and tooth tartar.

    PubMed

    Wahl, R; Kallee, E

    1994-11-01

    Oxalic acid was determined in human saliva, teeth, tartar, and in animal teeth. Saliva from dentally healthy male subjects contained 0.10 +/- 0.09 mmol/l (n = 41) and those of dentally healthy female subjects 0.18 +/- 0.17 mmol/l (n = 40). Oxalic acid in tartar from 16 patients was 3.3 +/- 1.2 mmol/kg tartar. In human teeth, oxalic acid was 1.0 +/- 0.3 mmol/kg in milk teeth (n = 12) and 0.9 +/- 0.6 mmol/kg in permanent teeth (n = 60). Human teeth were sorted into age groups and into molars, incisors and premolars. In animal teeth, oxalic acid content varied widely. The formed calcium oxalate is proposed to be a 'physiological' protective mechanism for teeth.

  1. Oxalic acid decreases calcium absorption in rats

    SciTech Connect

    Weaver, C.M.; Martin, B.R.; Ebner, J.S.; Krueger, C.A.

    1987-11-01

    Calcium absorption from salts and foods intrinsically labeled with /sup 45/Ca was determined in the rat model. Calcium bioavailability was nearly 10 times greater for low oxalate kale, CaCO/sub 3/ and CaCl/sub 2/ than from CaC/sub 2/O/sub 4/ (calcium oxalate) and spinach (high in oxalates). Extrinsic and intrinsic labeling techniques gave a similar assessment of calcium bioavailability from kale but not from spinach.

  2. Oxalic acid decreases calcium absorption in rats.

    PubMed

    Weaver, C M; Martin, B R; Ebner, J S; Krueger, C A

    1987-11-01

    Calcium absorption from salts and foods intrinsically labeled with 45Ca was determined in the rat model. Calcium bioavailability was nearly 10 times greater for low oxalate kale, CaCO3 and CaCl2 than from CaC2O4 (calcium oxalate) and spinach (high in oxalates). Extrinsic and intrinsic labeling techniques gave a similar assessment of calcium bioavailability from kale but not from spinach.

  3. Oxalic acid and sclerotial differentiation of Polyporus umbellatus.

    PubMed

    Xing, Yong-Mei; Yin, Wan-Qiang; Liu, Meng-Meng; Wang, Chun-Lan; Guo, Shun-Xing

    2015-06-01

    The present investigation aimed to uncover the effects of exogenous oxalic acid during the sclerotial formation of Polyporus umbellatus, with an emphasis on determining the content of the endogenic oxalic acid in the fungus. To this end, the oxalic acid content of the vegetative mycelia, sclerotia, culture mediums and sclerotial exudate were measured using High Performance Liquid Chromatography (HPLC). Furthermore, the lipid peroxidation was estimated by detecting thiobarbituric bituric acid reactive substances (TBARS). The results showed that the exogenous oxalic acid caused a delay in sclerotial differentiation (of up to 9 or more days), suppressed the sclerotial biomass and decreased the lipid peroxidation significantly in a concentration-dependent manner. Oxalic acid was found at very low levels in the mycelia and the maltose medium, whereas it was found at high levels in the mycelia and sucrose medium. After sclerotial differentiation, oxalic acid accumulated at high levels in both the sclerotia and the sclerotial exudate. Oxalic acid was therefore found to inhibit P. umbellatus sclerotial formation.

  4. Acetate induced enhancement of photocatalytic hydrogen peroxide production from oxalic acid and dioxygen.

    PubMed

    Yamada, Yusuke; Nomura, Akifumi; Miyahigashi, Takamitsu; Ohkubo, Kei; Fukuzumi, Shunichi

    2013-05-09

    The addition of acetate ion to an O2-saturated mixed solution of acetonitrile and water containing oxalic acid as a reductant and 2-phenyl-4-(1-naphthyl)quinolinium ion (QuPh(+)-NA) as a photocatalyst dramatically enhanced the turnover number of hydrogen peroxide (H2O2) production. In this photocatalytic H2O2 production, a base is required to facilitate deprotonation of oxalic acid forming oxalate dianion, which acts as an actual electron donor, whereas a Brønsted acid is also necessary to protonate O2(•-) for production of H2O2 by disproportionation. The addition of acetate ion to a reaction solution facilitates both the deprotonation of oxalic acid and the protonation of O2(•-) owing to a pH buffer effect. The quantum yield of the photocatalytic H2O2 production under photoirradiation (λ = 334 nm) of an O2-saturated acetonitrile-water mixed solution containing acetate ion, oxalic acid and QuPh(+)-NA was determined to be as high as 0.34, which is more than double the quantum yield obtained by using oxalate salt as an electron donor without acetate ion (0.14). In addition, the turnover number of QuPh(+)-NA reached more than 340. The reaction mechanism and the effect of solvent composition on the photocatalytic H2O2 production were scrutinized by using nanosecond laser flash photolysis.

  5. Alleviation of chilling injury in tomato fruit by exogenous application of oxalic acid.

    PubMed

    Li, Peiyan; Yin, Fei; Song, Lijun; Zheng, Xiaolin

    2016-07-01

    The effects of oxalic acid on the development of chilling injury (CI), energy metabolism and lycopene metabolism in tomato fruit (Solanum lycopersicum L.) were investigated. Mature green tomatoes were dipped in 10mmoll(-1) oxalic acid (OA) solution for 10min at 25°C. Tomatoes were subsequently stored at 4±0.5°C for 20days before being transferred to 25°C for 12days. Oxalic acid treatment apparently alleviated CI development and membrane damage; maintained higher levels of ATP and ADP; increased activities of succinic dehydrogenase (SDH), Ca(2+)-adenosine triphosphatase (Ca(2+)-ATPase) and H(+)-adenosine triphosphatase (H(+)-ATPase); and elevated lycopene accumulation associated with the upregulation of PSY1 and ZDS expression in tomatoes during a period at room temperature following exposure to chilling stress. Thus, oxalic acid treatment benefited the control of CI and the maintenance of fruit quality in tomatoes stored for long periods (approximately 32days).

  6. Determination of water-soluble forms of oxalic and formic acids in soils by ion chromatography

    NASA Astrophysics Data System (ADS)

    Karicheva, E.; Guseva, N.; Kambalina, M.

    2016-03-01

    Carboxylic acids (CA) play an important role in the chemical composition origin of soils and migration of elements. The content of these acids and their salts is one of the important characteristics for agrochemical, ecological, ameliorative and hygienic assessment of soils. The aim of the article is to determine water-soluble forms of same carboxylic acids — (oxalic and formic acids) in soils by ion chromatography with gradient elution. For the separation and determination of water-soluble carboxylic acids we used reagent-free gradient elution ion-exchange chromatography ICS-2000 (Dionex, USA), the model solutions of oxalate and formate ions, and leachates from soils of the Kola Peninsula. The optimal gradient program was established for separation and detection of oxalate and formate ions in water solutions by ion chromatography. A stability indicating method was developed for the simultaneous determination of water-soluble organic acids in soils. The method has shown high detection limits such as 0.03 mg/L for oxalate ion and 0.02 mg/L for formate ion. High signal reproducibility was achieved in wide range of intensities which correspond to the following ion concentrations: from 0.04 mg/g to 10 mg/L (formate), from 0.1 mg/g to 25 mg/L (oxalate). The concentration of formate and oxalate ions in soil samples is from 0.04 to 0.9 mg/L and 0.45 to 17 mg/L respectively.

  7. Oxalic acid is available as a natural antioxidant in some systems.

    PubMed

    Kayashima, Tomoko; Katayama, Tetsuyuki

    2002-10-10

    Oxalic acid is found in a wide variety of plants. This study showed that oxalic acid suppressed in vitro lipid peroxidation in a concentration-dependent manner. Furthermore, oxalic acid reduced the rate of ascorbic acid oxidation in the presence of hydrogen peroxide and Cu(2+). These results suggest that oxalic acid is available as a natural antioxidant.

  8. Hausmannite (Mn3O4) conversion to manganite (γ-MnOOH) in dilute oxalate solution

    USGS Publications Warehouse

    Lind, Carol J.

    1988-01-01

    Oxalic acid retards the alteration of Mn3O4 to γ-MnOOH during aging at pH 7.4 ?? 0.2 in well-aerated, abiotic suspensions that contain 4.4 ?? 10-3 M total Mn. In solutions of 1.25 ?? 10-3 M oxalate and greater, about 15% of the initial Mn3O4 altered to ??-MnOOH by day 10, and in solutions of 6.7 ?? 10-4 M oxalate, about 45% altered to ??-MnOOH by day 67. Although precipitation continued through day 365, the degree of conversion remained the same as at day 10 and day 67, respectively. In oxalate-free suspensions, the conversion was about 80% complete by day 67 and 100% by day 109. Oxalate complexed most of the dissolved divalent Mn, lowered the free Mn(II) and MnSO40 concentrations, but increased the total dissolved Mn. Steric hindrance of surface reactions by a suggested manganese oxalate layer on the Mn3O4 surface may explain the blockage of the oxidation cycle.

  9. Production of oxalic acid by some fungi infected tubers.

    PubMed

    Faboya, O; Ikotun, T; Fatoki, O S

    1983-01-01

    Oxalic acid (as oxalate) was detected in four tubers commonly used for food in Nigeria-Dioscorea rotundata (White yam), Solanum tuberosum (Irish potato), Ipomoea batatas (Sweet potato), and Manihot esculenta (cassava). Whereas healthy I. batata had the highest oxalic acid content, healthy M. esculenta contained the lowest. When all tubers were artifically inoculated with four fungi-Penicillium oxalicum CURIE and THOM, Aspergillus niger VAN TIEGH, A. flavus and A. tamarii KITA, there was an increase in oxalate content/g of tuber tissue. The greatest amount of oxalate was produced by P. oxalicum in D. rotundata tuber. Consistently higher amounts of oxalate were produced by the four fungi in infected sweet potato tuber than in any other tuber and consistently lower amounts of oxalate were produced by the four fungi in Irish potato tuber. Differences in the carbohydrate type present in the tubers and in the biosynthesis pathway are thought to be responsible for variation in the production of oxalate in the different tubers by the four fungi used.

  10. [Kinetics of the growth of Ca oxalate crystals from supersaturated solutions].

    PubMed

    Leskovar, P; Hartung, R

    1979-04-01

    Several factors influencing the nucleation and growth of Ca-oxalate crystals from metastable and instable solutions were studied in some detail. Factors of interest were the absolute concentration of calcium respectively oxalate, the quotient oxalate/calcium, repeated additions of calcium and/or oxalate, the presence or absence of crystal seeds, the agitation respectively stagnation of the metastable Ca-oxalate solution, the duration of crystallization, etc. The striking findings are the eminent role of oxalate in the formation of big crystals and crystal aggregates, the distinct inhibition of crystal growth at higher and very high calcium concentrations, as well as the substantial crystal enlargement at the presistent oxalate load.

  11. Production and Degradation of Oxalic Acid by Brown Rot Fungi

    PubMed Central

    Espejo, Eduardo; Agosin, Eduardo

    1991-01-01

    Our results show that all of the brown rot fungi tested produce oxalic acid in liquid as well as in semisolid cultures. Gloeophyllum trabeum, which accumulates the lowest amount of oxalic acid during decay of pine holocellulose, showed the highest polysaccharide-depolymerizing activity. Semisolid cultures inoculated with this fungus rapidly converted 14C-labeled oxalic acid to CO2 during cellulose depolymerization. The other brown rot fungi also oxidized 14C-labeled oxalic acid, although less rapidly. In contrast, semisolid cultures inoculated with the white rot fungus Coriolus versicolor did not significantly catabolize the acid and did not depolymerize the holocellulose during decay. Semisolid cultures of G. trabeum amended with desferrioxamine, a specific iron-chelating agent, were unable to lower the degree of polymerization of cellulose or to oxidize 14C-labeled oxalic acid to the extent or at the rate that control cultures did. These results suggest that both iron and oxalic acid are involved in cellulose depolymerization by brown rot fungi. PMID:16348522

  12. Isolation of oxalic acid tolerating fungi and decipherization of its potential to control Sclerotinia sclerotiorum through oxalate oxidase like protein.

    PubMed

    Yadav, Shivani; Srivastava, Alok K; Singh, Dhanajay P; Arora, Dilip K

    2012-11-01

    Oxalic acid plays major role in the pathogenesis by Sclerotinia sclerotiorum; it lowers the pH of nearby environment and creates the favorable condition for the infection. In this study we examined the degradation of oxalic acid through oxalate oxidase and biocontrol of Sclerotinia sclerotiorum. A survey was conducted to collect the rhizospheric soil samples from Indo-Gangetic Plains of India to isolate the efficient fungal strains able to tolerate oxalic acid. A total of 120 fungal strains were isolated from root adhering soils of different vegetable crops. Out of 120 strains a total of 80 isolates were able to grow at 10 mM of oxalic acid whereas only 15 isolates were grow at 50 mM of oxalic acid concentration. Then we examined the antagonistic activity of the 15 isolates against Sclerotinia sclerotiorum. These strains potentially inhibit the growth of the test pathogen. A total of three potential strains and two standard cultures of fungi were tested for the oxalate oxidase activity. Strains S7 showed the maximum degradation of oxalic acid (23 %) after 60 min of incubation with fungal extract having oxalate oxidase activity. Microscopic observation and ITS (internally transcribed spacers) sequencing categorized the potential fungal strains into the Aspergillus, Fusarium and Trichoderma. Trichoderma sp. are well studied biocontrol agent and interestingly we also found the oxalate oxidase type activity in these strains which further strengthens the potentiality of these biocontrol agents.

  13. Microelectrophoretic study of calcium oxalate monohydrate in macromolecular solutions

    NASA Technical Reports Server (NTRS)

    Curreri, P. A.; Onoda, G. Y., Jr.; Finlayson, B.

    1987-01-01

    Electrophoretic mobilities were measured for calcium oxalate monohydrate (COM) in solutions containing macromolecules. Two mucopolysaccharides (sodium heparin and chondroitin sulfate) and two proteins (positively charged lysozyme and negatively charged bovine serum albumin) were studied as adsorbates. The effects of pH, calcium oxalate surface charge (varied by calcium or oxalate ion activity), and citrate concentration were investigated. All four macromolecules showed evidence for adsorption. The macromolecule concentrations needed for reversing the surface charge indicated that the mucopolysaccharides have greater affinity for the COM surface than the proteins. Citrate ions at high concentrations appear to compete effectively with the negative protein for surface sites but show no evidence for competing with the positively charged protein.

  14. Effect of oxalic acid on Nosema ceranae infection.

    PubMed

    Nanetti, Antonio; Rodriguez-García, Cristina; Meana, Aránzazu; Martín-Hernández, Raquel; Higes, Mariano

    2015-10-01

    Nosema ceranae is a honey bee pathogen parasitizing the ventricular epithelium and potentially causing colony death. The effect of 0.25 M oxalic acid solution administered to the bees in the form of sugar syrup was determined in laboratory and field trials. The spore numbers in an 8-day laboratory experiment were significantly lower when AO was administered (treated: 11.86 ± 0.94 s.e. × 10^6; untreated: 30.64 ± 0.31 s.e.x10^6). When administered in autumn to free flying colonies twice, 3 weeks apart, the infection prevalence decreased in young (relative reduction of 53.8% ± 6.5 s.e.) and old bees (relative reduction of 44.4% ± 6.0 s.e.). Meanwhile increased prevalence in all the controls was detected (young and old bees: relative increase of 45.7% ± 22.8 s.e. and 10.2% ± 5.9 s.e., respectively). While all the treated colonies overwintered correctly, the untreated ones did not (3 out of 5 were dead). In the absence of commercial products approved in several countries to control nosemosis, oxalic acid syrup appears promising in the development of alternative management strategies.

  15. A feasibility study on the multistage process for the oxalic acid pretreatment of a lignocellulosic biomass using electrodialysis.

    PubMed

    Lee, Hong-Joo; Ahn, Sung Ju; Seo, Young-Jun; Lee, Jae-Won

    2013-02-01

    The present study investigated the feasibility of the recovery and reuse oxalic acid in a multistage process for the pretreatment of a lignocellulosic biomass. Electrodialysis (ED), an electrochemical process using ion exchange membranes, was used to recover and reuse oxalic acid in the multistage process. The ED optimal condition for recover oxalic acid was potential of 10V and pH 2.2 in synthetic solutions. The recovery efficiency of oxalic acid from hydrolysates reached 100% at potential of 10V. The power consumption to treat 1mol of oxalic acid was estimated to be 41.0wh. At the same time, ethanol production increased up to 19g/L in the ED-treated hydrolysate, corresponding to ethanol productivity of 0.27g/L/h. It was clearly shown that bioethanol fermentation efficiency increased using the ED process, due to a small loss of fermentable sugar and a significantly high removal of inhibitory chemicals.

  16. Formation of solid solutions between racemic and enantiomeric citalopram oxalate.

    PubMed

    de Diego, Heidi Lopez; Bond, Andrew D; Dancer, Robert James

    2011-05-01

    The X-ray powder diffractograms of racemic citalopram oxalate and (S)-citalopram oxalate are very similar, but the melting point of the racemate is higher than that of the pure enantiomer. The higher melting point indicates that the racemate is a racemic compound, rather than a conglomerate. The crystal structure of the enantiomer contains two molecules of (S)-citalopram in the asymmetric unit. The conformation of the two molecules is different but they approximate mirror images of each other if the aromatic groups are interchanged. The crystal structure of the racemate is essentially isostructural with that of the enantiomer, having almost the same cell parameters but containing a crystallographic inversion centre that is not retained in the enantiomer structure. The closely-comparable crystal structures permit solid solutions to be formed between racemic and enantiomeric citalopram oxalate. Phase diagrams of the (R)-citalopram and (S)-citalopram oxalate system are constructed, and they show that solid solutions are formed at all ratios of the two enantiomers.

  17. REMOVING SLUDGE HEELS FROM SAVANNAH RIVER SITE WASTE TANKS BY OXALIC ACID DISSOLUTION

    SciTech Connect

    Poirier, M; David Herman, D; Fernando Fondeur, F; John Pareizs, J; Michael Hay, M; Bruce Wiersma, B; Kim Crapse, K; Thomas Peters, T; Samuel Fink, S; Donald Thaxton, D

    2009-03-01

    The Savannah River Site (SRS) will remove sludge as part of waste tank closure operations. Typically the bulk sludge is removed by mixing it with supernate to produce a slurry, and transporting the slurry to a downstream tank for processing. Experience shows that a residual heel may remain in the tank that cannot be removed by this conventional technique. In the past, SRS used oxalic acid solutions to disperse or dissolve the sludge heel to complete the waste removal. To better understand the actual conditions of oxalic acid cleaning of waste from carbon steel tanks, the authors developed and conducted an experimental program to determine its effectiveness in dissolving sludge, the hydrogen generation rate, the generation rate of other gases, the carbon steel corrosion rate, the impact of mixing on chemical cleaning, the impact of temperature, and the types of precipitates formed during the neutralization process. The test samples included actual SRS sludge and simulated SRS sludge. The authors performed the simulated waste tests at 25, 50, and 75 C by adding 8 wt % oxalic acid to the sludge over seven days. They conducted the actual waste tests at 50 and 75 C by adding 8 wt % oxalic acid to the sludge as a single batch. Following the testing, SRS conducted chemical cleaning with oxalic acid in two waste tanks. In Tank 5F, the oxalic acid (8 wt %) addition occurred over seven days, followed by inhibited water to ensure the tank contained enough liquid to operate the mixer pumps. The tank temperature during oxalic acid addition and dissolution was approximately 45 C. The authors analyzed samples from the chemical cleaning process and compared it with test data. The conclusions from the work are: (1) Oxalic acid addition proved effective in dissolving sludge heels in the simulant demonstration, the actual waste demonstration, and in SRS Tank 5F. (2) The oxalic acid dissolved {approx} 100% of the uranium, {approx} 100% of the iron, and {approx} 40% of the manganese

  18. The control of Varroa destructor using oxalic acid.

    PubMed

    Gregorc, Ales; Planinc, I

    2002-05-01

    Twenty-four honeybee (Apis mellifera) colonies were used to monitor the efficacy of a solution of 2.9% oxalic acid (OA) and 31.9% sugar against the mite Varroa destructor. Mite mortality was established prior to and after OA treatments, which were conducted in August and September. The treatments resulted in 37% mite mortality as opposed to 1.11% in the controls. OA treatment conducted in September on previously untreated colonies resulted in 25% mite mortality. OA treatments in October and November resulted in approximately 97% mite mortality. These results suggest that OA is effective during the broodless period and less effective when applied to colonies with capped broods. The possible use of OA against the Varroa mite in honeybee colonies as an alternative to routine chemical treatments is discussed.

  19. The effect of rumen adaptation to oxalic acid on selection of oxalic-acid-rich plants by goats.

    PubMed

    Duncan, A J; Frutos, P; Young, S A

    2000-01-01

    Rumen microbial degradation is an important route for detoxification of secondary plant compounds encountered in the diets of free-grazing ruminants. Exposure to diets containing particular secondary plant compounds can lead to increased rates of secondary compound degradation in the rumen. An experiment was conducted to determine whether rumen adaptation to oxalic acid would influence the diet selection of goats offered choices between plant species differing in their oxalic acid content. Twelve adult female goats were divided into two groups of six animals each. One group received a daily oral dose, in gelatin capsules, of 0.6 mmol oxalic acid/kg live weight per d throughout the experiment while the other group received placebos consisting of empty gelatin capsules. After an adaptation period of 8 d, the animals were allowed to graze a mixture of spinach (rich in oxalic acid) and cabbage (low in oxalic acid) for 7 h/d on two consecutive days per week during four consecutive 1-week periods. Intervening days were spent on grass pasture. Diet composition and intake were measured using cuticular wax n-alkanes as internal markers. Results showed that adapted goats included a higher proportion of spinach in their diet (P < 0.05) although absolute intakes of spinach were the same for the two groups. Goats in the oxalic-acid-adapted group consumed less cabbage than control animals (P < 0.05) suggesting that adaptation to oxalic acid at the rumen level may have interfered with detoxification of cabbage-derived secondary plant compounds. Voluntary intake increased progressively through the four experimental periods (P < 0.001) with a tendency for higher intakes among control than among adapted animals (P < 0.1). The experiment demonstrates how differences in the rate of degradation of secondary plant compounds may influence diet selection in ruminants.

  20. Photocatalytic decomposition of perfluorooctanoic acid (PFOA) by TiO2 in the presence of oxalic acid.

    PubMed

    Wang, Yuan; Zhang, Pengyi

    2011-09-15

    Heterogeneous photocatalytic decomposition of perfluoroocatanoic acid (PFOA) by TiO(2) under 254 nm UV light was investigated. Adding oxalic acid as a hole-scavenger significantly accelerated PFOA decomposition under nitrogen atmosphere. Fluoride ion, formic acid and six shorter-chain perfluorinated carboxylic acids (PFCAs) bearing C(2)-C(7) were identified as intermediates. When using perchloric acid (HClO(4)) as a replacement of oxalic acid to maintain the same pH of the reaction solution, PFOA did not decomposition efficiently. Compared with oxalic acid, potassium iodide (KI, another hole-scavenger) also led to a slower PFOA decomposition, while the addition of an electron acceptor (potassium persulfate, K(2)S(2)O(8)) obviously inhibited PFOA decomposition. This suggested that oxalic acid played more than one role in PFOA decomposition rather than simply providing acidity and acting as a hole-scavenger. The electron paramagnetic resonance (EPR) measurements confirmed the existence of carboxyl anion radicals (CO(2)(-)) in the photocatalytic process, which was a result of the reaction between oxalic acid and photogenerated hole. These findings indicated that PFOA decomposition was primarily induced by CO(2)(-) radicals, although photogenerated electron was also conducive to PFOA decomposition. A possible mechanism for PFOA decomposition was proposed.

  1. Means for reducing oxalic acid to a product

    SciTech Connect

    Morduchowitz, A.; Sammells, A.F.

    1988-12-06

    This patent describes an apparatus for reducing oxalic acid to a product comprising: a cell including a separator for separating the cell into two chambers, a catholyte chamber and an anolyte chamber, each chamber having an inlet and an outlet; a porous anode arranged within the anolyte section in a manner so that an electrolyte entering through the inlet of the anolyte section will pass through the anode and exit through the outlet of the anolyte section; means for providing an electrolyte to the inlet of the anolyte chamber in a manner so that it will exit through the outlet of the anolyte chamber; means for providing a mixture of oxalic acid and an electrolyte to the inlet of the catholyte chamber; porous cathode means located in the catholyte chamber for reducing the oxalic acid in the oxalic acid-electrolyte mixture to the product within the cathode means when a d.c. voltage provided across the anode and the cathode means, the product exiting the cell by way of the catholyte chamber's outlet; and means for providing a d.c. voltage across the cathode means and the anode so as to cooperate in the reduction of the oxalic acid; and in which the cathode means includes a porous cathode having discrete sites of platinum and mercury as catalysts and the product is ethylene glycol.

  2. Effects of oxalic acid on availability of zinc from spinach leaves and zinc sulfate to rats.

    PubMed

    Welch, R M; House, W A; Van Campen, D

    1977-06-01

    Some effects of dietary oxalic acid on availability of zinc from organic and inorganic sources were assessed. Male rats fed zinc-deficient diets with and without added sodium oxalate were orally dosed once with either 65Zn-labeled spinach leaves or 65Zn-labeled zinc sulfate. Spinach plants (Spinacia oleracea, var. "Winter Bloomsdale") were grown in 65Zn-labeled nutrient solutions that contained 0.033, 0.131 or 0.262 ppm zinc. Increasing zinc supply to the plants increased zinc concentration in the leaves. Oxalic acid content in all leaves was about 7% dry weight. Dietary oxalate enhanced the availability of 65Zn from zinc sulfate, but had no effect on absorption and retention of 65Zn from spinach leaves. Regardless of dietary oxalate levels, absorption and retention of 65Zn was greater from spinach leaves than from zinc sulfate. We concluded that endogenous zinc in spinach leaves was readily available to zinc-deficient rats, and that dietary oxalate was not deleterious to zinc availability.

  3. Dissolution of kaolinite induced by citric, oxalic, and malic acids.

    PubMed

    Wang, Xingxiang; Li, Qingman; Hu, Huafeng; Zhang, Taolin; Zhou, Yiyong

    2005-10-15

    Kaolinite is a dominant clay mineral in the soils in tropical and subtropical regions, and its dissolution has an influence on a variety of soil properties. In this work, kaolinite dissolution induced by three kinds of low-molecular-weight organic acid, i.e., citric, oxalic, and malic acids, was evaluated under far-from-equilibrium conditions. The rates of kaolinite dissolution depended on the kind and concentration of organic acids, with the sequence R(oxalate)>R(citrate)>R(malate). Chemical calculation showed the change in concentration of organic ligand relative to change in concentration of organic acid in suspensions of kaolinite and organic acid. The effect of organic acid on kaolinite dissolution was modeled by species of organic anionic ligand. For oxalic acid, L(2-)(oxalic) and HL(-)(oxalic) jointly enhanced the dissolution of kaolinite, but for malic and citric acids, HL(-)(malic) and H2L-(citric) made a higher contribution to the total dissolution rate of kaolinite than L(2-)(malic) and L(3-)(citric), respectively. For oxalic acid, the proposed model was R(Si)=1.89x10(-12)x[(25x)/(1+25x)]+1.93x10(-12)x[(1990x1)/(1+1990x1)] (R2=0.9763), where x and x1 denote the concentrations of HL(oxalic) and L(oxalic), respectively, and x1=10(-3.81)xx/[H+]. For malic acid, the model was R(Si)=4.79x10(-12)x[(328x)/(1+328x)]+1.67x10(-13)x[(1149x1)/(1+1149x1)] (R2=0.9452), where x and x1 denote the concentrations of HL(malic) and L(malic), respectively, and x1=10(-5.11)xx/[H+], and for citric acid, the model was R(Si)=4.73x10(-12)x[(845x)/(1+845x)]+4.68x10(-12)x[(2855x1)/(1+2855x1)] (R2=0.9682), where x and x1 denote the concentrations of H2L(citric) and L(citric), respectively, and [Formula: see text] .

  4. The adsorption and photo-degradation of oxalic acid at the TiO2 surface.

    NASA Astrophysics Data System (ADS)

    Mendive, Cecilia; Blesa, Miguel; Bahnemann, Detlef

    2006-03-01

    Oxalic acid is the simplest model compound to study the heterogeneous photocatalytic oxidation of pollutants on TiO2 containing more than one carboxylate group. We have carried out a study of a system of an oxalic acid solution in contact with a thin film of TiO2 particles employing ATR - FTIR in combination with quantum chemical calculations. Thus, possible adsorption structures have been identified and molecular dynamic simulations have been used to compare their predictions with the experimental data. It was found that the adsorption of oxalic acid on TiO2 in the dark can be explained in terms of two surface complexation modes for the anatase phase and only one surface complexation mode for the rutile phase. We have found that under illumination one of the complexes on the anatase phase preferably undergoes photo-degradation. At the same time water molecules are desorbed from the TiO2 surface by a thermal mechanism induced by the absorption of photons. Both processes favor the adsorption of more molecules of oxalic acid at the TiO2 surface which is thus enriched in the second complexation mode. A similar mechanism was found to occur on the rutile phase. The only complexation mode appears not to be photo-sensitive but the TiO2 surface is enriched in oxalic acid under illumination due to the replacement of photo-desorbed water molecules.

  5. Oxalic acid adsorption states on the clean Cu(110) surface

    NASA Astrophysics Data System (ADS)

    Fortuna, Sara

    2016-11-01

    Carboxylic acids are known to assume a variety of configurations on metallic surfaces. In particular oxalic acid on the Cu(110) surface has been proposed to assume a number of upright configurations. Here we explore with DFT calculations the possible structures that oxalic acid can form on copper 110 at different protonation states, with particular attention at the possibility of forming structures composed of vertically standing molecules. In its fully protonated form it is capable of anchoring itself on the surface thanks to one of its hydrogen-free oxygens. We show the monodeprotonated upright molecule with two oxygens anchoring it on the surface to be the lowest energy conformation of a single oxalic molecules on the Cu(110) surface. We further show that it is possible for this configuration to form dense hexagonally arranged patterns in the unlikely scenario in which adatoms are not involved.

  6. Preferential Enrichment of DL-Leucine Using Cocrystal Formation With Oxalic Acid Under Nonequilibrium Crystallization Conditions.

    PubMed

    Manoj, Kochunnoonny; Takahashi, Hiroki; Morita, Yoko; Gonnade, Rajesh G; Iwama, Sekai; Tsue, Hirohito; Tamura, Rui

    2015-07-01

    By utilizing the preferential enrichment (PE) technique, we achieved an improved enantiomeric resolution of DL-leucine (Leu) using a 1:1 cocrystal (DL-) of DL-Leu and oxalic acid. The crystal structure analysis of DL- indicated the occurrence of a novel type of phase transition and subsequent preferential redissolution of one enantiomer from the resulting crystals into solution.

  7. Inhibitory effect of oxalic acid on bacterial spoilage of raw chilled chicken.

    PubMed

    Anang, D M; Rusul, G; Radu, Son; Bakar, Jamilah; Beuchat, L R

    2006-08-01

    Oxalic acid was evaluated as a treatment for reducing populations of naturally occurring microorganisms on raw chicken. Raw chicken breasts were dipped in solutions of oxalic acid (0, 0.5, 1.0, 1.5, and 2.0%, wt/vol) for 10, 20, and 30 min, individually packed in oxygen-permeable polyethylene bags, and stored at 4 degrees C. Total plate counts of aerobic bacteria and populations of Pseudomonas spp. and Enterobacteriaceae on breasts were determined before treatment and after storage for 1, 3, 7, 10, and 14 days. The pH and Hunter L, a, and b values of the breast surface were measured. Total plate counts were ca. 1.5 and 4.0 log CFU/g higher on untreated chicken breasts after storage for 7 and 14 days, respectively, than on breasts treated with 0.5% oxalic acid, regardless of dip time. Differences in counts on chicken breasts treated with water and 1.0 to 2.0% of oxalic acid were greater. Populations of Pseudomonas spp. on chicken breasts treated with 0.5 to 2.0% oxalic acid and stored at 4 degrees C for 1 day were less than 2 log CFU/g (detection limit), compared with 5.14 log CFU/g on untreated breasts. Pseudomonas grew on chicken breasts treated with 0.5% oxalic acid to reach counts not exceeding 3.88 log CFU/g after storage for 14 days. Counts on untreated chicken exceeded 8.83 log CFU/g at 14 days. Treatment with oxalic acid caused similar reductions in Enterobacteriaceae counts. Kocuria rhizophila was the predominant bacterium isolated from treated chicken. Other common bacteria included Escherichia coli and Empedobacter brevis. Treatment with oxalic acid caused a slight darkening in color (decreased Hunter L value), retention of redness (increased Hunter a value), and increase in yellowness (increased Hunter b value). Oxalic acid has potential for use as a sanitizer to reduce populations of spoilage microorganisms naturally occurring on raw chicken, thereby extending chicken shelf life.

  8. The abiotic degradation of soil organic matter to oxalic acid

    NASA Astrophysics Data System (ADS)

    Studenroth, Sabine; Huber, Stefan; Schöler, H. F.

    2010-05-01

    The abiotic degradation of soil organic matter to volatile organic compounds was studied intensely over the last years (Keppler et al., 2000; Huber et al., 2009). It was shown that soil organic matter is oxidised due to the presence of iron (III), hydrogen peroxide and chloride and thereby produces diverse alkyl halides, which are emitted into the atmosphere. The formation of polar halogenated compounds like chlorinated acetic acids which are relevant toxic environmental substances was also found in soils and sediments (Kilian et al., 2002). The investigation of the formation of other polar halogenated and non-halogenated compounds like diverse mono- and dicarboxylic acids is going to attain more and more importance. Due to its high acidity oxalic acid might have impacts on the environment e.g., nutrient leaching, plant diseases and negative influence on microbial growth. In this study, the abiotic formation of oxalic acid in soil is examined. For a better understanding of natural degradation processes mechanistic studies were conducted using the model compound catechol as representative for structural elements of the humic substances and its reaction with iron (III) and hydrogen peroxide. Iron is one of the most abundant elements on earth and hydrogen peroxide is produced by bacteria or through incomplete reduction of oxygen. To find suitable parameters for an optimal reaction and a qualitative and quantitative analysis method the following reaction parameters are varied: concentration of iron (III) and hydrogen peroxide, time dependence, pH-value and influence of chloride. Analysis of oxalic acid was performed employing an ion chromatograph equipped with a conductivity detector. The time dependent reaction shows a relatively fast formation of oxalic acid, the optimum yield is achieved after 60 minutes. Compared to the concentration of catechol an excess of hydrogen peroxide as well as a low concentration of iron (III) are required. In absence of chloride the

  9. Evaluation of Oxalic Acid Treatments against the Mite Varroa destructor and Secondary Effects on Honey Bees Apis mellifera

    PubMed Central

    Adjlane, Noureddine; Tarek, El-Ounass; Haddad, Nizar

    2016-01-01

    Background: The Varroa destructor varroasis is a very serious parasite of honeybee Apis mellifera. The objective of this study was to evaluate the effectiveness of Varroa treatment using organic acid (oxalic acid) in Algeria identifying its side effects on bee colonies. Methods: Treatment was conducted in one apiary consisting 30 colonies kept in Langstroth hives kind. Oxalic acid dripped directly on bees 5ml of this solution of oxalic acid per lane occupied by a syringe. Three doses were tested: 4.2, 3.2 and 2.1% oxalic acid is 100, 75 and 50 g of oxalic acid dehydrate in one litter of sugar syrup (1water to1 surge) concentration. Results: The percentage of average efficiency obtained for the first dose was 81%, 72.19% for the second dose, and 65% for third one, while the dose of 100 g oxalic acid causes a weakening of honey bee colonies. Conclusion: The experiments revealed that clear variation in the treatment efficiency among colonies that this might be related to brood presence therefore in order to assure the treatment efficiency oxalic acid should be part of a bigger strategy of Varroa treatment. PMID:28032102

  10. The electrokinetic behavior of calcium oxalate monohydrate in macromolecular solutions

    NASA Technical Reports Server (NTRS)

    Curreri, P. A.; Onoda, G. Y., Jr.; Finlayson, B.

    1988-01-01

    Electrophoretic mobilities were measured for calcium oxalate monohydrate (COM) in solutions containing macromolecules. Two mucopolysaccharides (sodium heparin and chrondroitin sulfate) and two proteins (positively charged lysozyme and negatively charged bovine serum albumin) were studied as adsorbates. The effects of pH, calcium oxalate surface charge (varied by calcium or oxalate ion activity), and citrate concentration were investigated. All four macromolecules showed evidence for chemical adsorption. The macromolecule concentrations needed for reversing the surface charge indicated that the mucopopolysacchrides have greater affinity for the COM surface than the proteins. The amount of proteins that can chemically adsorb appears to be limited to approximately one monomolecular layer. When the surface charge is high, an insufficient number of proteins can chemically adsorb to neutralize or reverse the surface charge. The remaining surface charge is balanced by proteins held near the surface by longer range electrostatic forces only. Citrate ions at high concentrations appear to compete effectively with the negative protein for surface sites but show no evidence for competing with the positively charged protein.

  11. Equilibrium aluminium hydroxo-oxalate phases during initial clay formation; H +-Al 3+-oxalic acid-Na + system

    NASA Astrophysics Data System (ADS)

    Bilinski, Halka; Horvath, Laszlo; Ingri, Nils; Sjöberg, Staffan

    1986-09-01

    The conditions necessary for initial clay formation have been studied in different model systems comprising different organic acids besides Si and Al. In the present paper the solid phases and the precipitation boundary characterizing the subsystem H +-Al 3+-oxalic acid (H 2L) are discussed. pH and tyndallometric measurements were performed in an ionic medium of 0.6 M Na(Cl) at 25 °C. The two phases Al 3(OH) 7(C 2O 4) · 3H 2O (phase I) and NaAl(OH) 2(C 2O 4) · 3H 2O (phase II) determine the precipitation boundary. The following formation constants for the two phases were deduced: lgβ1 = lg([ Al3+] -3[ H2C2O4] -1[ H+] 9 = -21.87 ± 0.08 and lgβ11 = lg([ Al3+] -1[ H2C2O4] -1[ H+] 4 = -5.61 ± 0.06. Phase I exists in the range [ Al] tot≥ 10 -4.4moldm-3,[ H2C2O4] tot ≥ 10 -4.9moldm-3 and at pH < 6.8, thus being a possible precipitate in oxalic-rich natural waters. The more soluble sodium phase is unlikely to exist in natural waters. The two phases are metastable relative to crystalline gibbsite and may be considered as the first precipitation step in the transition from aqueous Al oxalates down to stable Al hydroxide. Model calculations illustrating these competing hydrolysis-complexation reactions are discussed in terms of predominance and speciation diagrams. The solid phases have been characterized by X-ray analysis of powders, TGA and IR spectra, and tentative structures are proposed. Phase I seems to be an octahedral layer structure, in which 3/5 of the octahedral sites between two close packed oxygen sheets are occupied by Al 3+ and the oxalate ion acts as a bridge ligand between two aluminium atoms. Phase II forms a more open sheet structure and has ion exchange properties. Powder data for a phase crystallized from the studied solution after a year are also presented. This phase, Na 4Al 2(OH) 2(C 2O 4) 4 · 10H 2O, supports the results from the equilibrium analysis of recent solution data by SJöBERG and ÖHMAN (1985), who have found the dinuclear

  12. Calcium extraction from brine water and seawater using oxalic acid

    NASA Astrophysics Data System (ADS)

    Natasha, Nadia Chrisayu; Lalasari, Latifa Hanum

    2017-01-01

    Calcium can be extracted not only from rocks but also from natural liquor such as seawater and brine water. In order to extract the calcium from seawater and brine water, oxalic acid was used in this research. Effect of variations of the volume of the oxalic acid at a constant concentration in seawater and brine water to produce calcium was investigated. The concentration of oxalic acid was 100 g/l and the variations of its volume were 2 ml, 4 ml, 6 ml, 8 ml, 10 ml, 20 ml, 30 ml, 40 ml, and 50 ml. The used seawater and brine water were firstly evaporated from 100 ml into 50 ml and then the oxalic acid was added into them with mixing to produce the calcium precipitates. The precipitates were analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM) and the filtrates were analyzed by inductively coupled plasma-optical emission spectrometry (ICP-OES). The SEM analysis showed that the precipitates from brine water were consisted of only calcium compound while from seawater sodium one was also found along with calcium compound. The XRD analysis showed that the calcium was present in the form of calcium oxalate for both seawater and brine water. The ICP-OES analysis of the filtrate from seawater precipitation showed that the its calcium content was decreased from 826.20 ppm to 0.04 ppm while from brine water, it decreased from 170.06 ppm to 1.96 ppm. These results showed that both seawater and brine water have the potential to be a raw material for calcium production.

  13. Separation of americium, curium, and rare earths from high-level wastes by oxalate precipitation: experiments with synthetic waste solutions

    SciTech Connect

    Forsberg, C.W.

    1980-01-01

    The separation of trivalent actinides and rare earths from other fission products in high-level nuclear wastes by oxalate precipitation followed by ion exchange (OPIX) was experimentally investigated using synthetic wastes and a small-scale, continuous-flow oxalic acid precipitation and solid-liquid separation system. Trivalent actinide and rare earth oxalates are relatively insoluble in 0.5 to 1.0 M HNO/sub 3/ whereas other fission product oxalates are not. The continuous-flow system consisted of one or two stirred-tank reactors in series for crystal growth. Oxalic acid and waste solutions were mixed in the first tank, with the product solid-liquid slurry leaving the second tank. Solid-liquid separation was tested by filters and by a gravity settler. The experiments determined the fraction of rare earths precipitated and separated from synthetic waste streams as a function of number of reactors, system temperature, oxalic acid concentration, liquid residence time in the process, power input to the stirred-tank reactors, and method of solid-liquid separation. The crystalline precipitate was characterized with respect to form, size, and chemical composition. These experiments are only the first step in converting a proposed chemical flowsheet into a process flowsheet suitable for large-scale remote operations at high activity levels.

  14. Natural abiotic formation of oxalic acid in soils: results from aromatic model compounds and soil samples.

    PubMed

    Studenroth, Sabine; Huber, Stefan G; Kotte, Karsten; Schöler, Heinz F

    2013-02-05

    Oxalic acid is the smallest dicarboxylic acid and plays an important role in soil processes (e.g., mineral weathering and metal detoxification in plants). We have first proven its abiotic formation in soils and investigated natural abiotic degradation processes based on the oxidation of soil organic matter, enhanced by Fe(3+) and H(2)O(2) as hydroxyl radical suppliers. Experiments with the model compound catechol and further hydroxylated benzenes were performed to examine a common degradation pathway and to presume a general formation mechanism of oxalic acid. Two soil samples were tested for the release of oxalic acid and the potential effects of various soil parameters on oxalic acid formation. Additionally, the soil samples were treated with different soil sterilization methods to prove the oxalic acid formation under abiotic soil conditions. Different series of model experiments were conducted to determine a range of factors including Fe(3+), H(2)O(2), reaction time, pH, and chloride concentration on oxalic acid formation. Under certain conditions, catechol is degraded up to 65.6% to oxalic acid referring to carbon. In serial experiments with two soil samples, oxalic acid was produced, and the obtained results are suggestive of an abiotic degradation process. In conclusion, Fenton-like conditions with low Fe(3+) concentrations and an excess of H(2)O(2) as well as acidic conditions were required for an optimal oxalic acid formation. The presence of chloride reduced oxalic acid formation.

  15. Oxalic acid production by citric acid-producing Aspergillus niger overexpressing the oxaloacetate hydrolase gene oahA.

    PubMed

    Kobayashi, Keiichi; Hattori, Takasumi; Honda, Yuki; Kirimura, Kohtaro

    2014-05-01

    The filamentous fungus Aspergillus niger is used worldwide in the industrial production of citric acid. However, under specific cultivation conditions, citric acid-producing strains of A. niger accumulate oxalic acid as a by-product. Oxalic acid is used as a chelator, detergent, or tanning agent. Here, we sought to develop oxalic acid hyperproducers using A. niger as a host. To generate oxalic acid hyperproducers by metabolic engineering, transformants overexpressing the oahA gene, encoding oxaloacetate hydrolase (OAH; EC 3.7.1.1), were constructed in citric acid-producing A. niger WU-2223L as a host. The oxalic acid production capacity of this strain was examined by cultivation of EOAH-1 under conditions appropriate for oxalic acid production with 30 g/l glucose as a carbon source. Under all the cultivation conditions tested, the amount of oxalic acid produced by EOAH-1, a representative oahA-overexpressing transformant, exceeded that produced by A. niger WU-2223L. A. niger WU-2223L and EOAH-1 produced 15.6 and 28.9 g/l oxalic acid, respectively, during the 12-day cultivation period. The yield of oxalic acid for EOAH-1 was 64.2 % of the maximum theoretical yield. Our method for oxalic acid production gave the highest yield of any study reported to date. Therefore, we succeeded in generating oxalic acid hyperproducers by overexpressing a single gene, i.e., oahA, in citric acid-producing A. niger as a host.

  16. Spectroscopic evidence for organic diacid complexation with dissolved silica in aqueous systems—I. Oxalic acid

    USGS Publications Warehouse

    Marley, N.A.; Bennett, P.; Janecky, D.R.; Gaffney, J.S.

    1989-01-01

    Increased solubility of quartz and mobilization in contaminated groundwater due to the complexation with dissolved organic acids has been recently proposed [Bennett and Siegel, Nature326, 684–686 (1987)]. Using laser Raman and Fourier transform infrared spectroscopies, we have examined mixed solutions of oxalic and silicic acids at near neutral pH in the tenth molar concentration ranges in an attempt to directly observe the proposed organo-silicate complexes.In both laser Raman and infrared spectra, product bands were observed that indicate an oxalate/silicic acid ester is being formed in the reaction. These data support the observation that organic diacids can lead to enhanced solubility of quartz in hydrogeological systems.

  17. Polyacrylonitrile/manganese acetate composite nanofibers and their catalysis performance on chromium (VI) reduction by oxalic acid.

    PubMed

    Zhang, Chengcheng; Li, Xiang; Bian, Xiujie; Zheng, Tian; Wang, Ce

    2012-08-30

    Polyacrylonitrile(PAN)/manganese acetate(Mn(CH(3)COO)(2)) composite nanofibers have been fabricated by electrospinning, a simple and effective technology. The obtained composite nanofibers were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectrometer (FT-IR). The composite nanofibers are amorphous in structure, continuous, even and smooth. At the same time, the reduction performance of Cr(VI) by oxalic acid in the presence of the composite nanofibers is also investigated. The results indicate that the composite nanofibers have exhibited excellent catalysis performance for Cr(VI) reduction from a Cr(2)O(7)(2-)-containing solution by oxalic acid. And the critical parameters, such as the catalyst dosage, oxalic acid content, chromium concentration, the pH value of the reaction solution and light have important impact on the reduction process. Under the simulated solar light irradiation, after only 60 min, 1.2mM initial Cr(VI) solution was reduced absolutely in the presence of PAN/Mn(CH(3)COO)(2) composite nanofibers containing 17.5 wt.% Mn(CH(3)COO)(2) by 0.3 mL 0.5M oxalic acid. In light, the reduction of Cr(VI) by oxalic acid is markedly accelerated.

  18. Activated carbon enhanced ozonation of oxalate attributed to HO oxidation in bulk solution and surface oxidation: effect of activated carbon dosage and pH.

    PubMed

    Xing, Linlin; Xie, Yongbing; Minakata, Daisuke; Cao, Hongbin; Xiao, Jiadong; Zhang, Yi; Crittenden, John C

    2014-10-01

    Ozonation of oxalate in aqueous phase was performed with a commercial activated carbon (AC) in this work. The effect of AC dosage and solution pH on the contribution of hydroxyl radicals (HO) in bulk solution and oxidation on the AC surface to the removal of oxalate was studied. We found that the removal of oxalate was reduced by tert-butyl alcohol (tBA) with low dosages of AC, while it was hardly affected by tBA when the AC dosage was greater than 0.3g/L. tBA also inhibited ozone decomposition when the AC dosage was no more than 0.05g/L, but it did not work when the AC dosage was no less than 0.1g/L. These observations indicate that HO in bulk solution and oxidation on the AC surface both contribute to the removal of oxalate. HO oxidation in bulk solution is significant when the dosage of AC is low, whereas surface oxidation is dominant when the dosage of AC is high. The oxalate removal decreased with increasing pH of the solution with an AC dosage of 0.5g/L. The degradation of oxalate occurs mainly through surface oxidation in acid and neutral solution, but through HO oxidation in basic bulk solution. A mechanism involving both HO oxidation in bulk solution and surface oxidation was proposed for AC enhanced ozonation of oxalate.

  19. Crystal structure of di­methyl­ammonium hydrogen oxalate hemi(oxalic acid)

    PubMed Central

    Diallo, Waly; Gueye, Ndongo; Crochet, Aurélien; Plasseraud, Laurent; Cattey, Hélène

    2015-01-01

    Single crystals of the title salt, Me2NH2 +·HC2O4 −·0.5H2C2O4, were isolated as a side product from the reaction involving Me2NH, H2C2O4 and Sn(n-Bu)3Cl in a 1:2 ratio in methanol or by the reaction of the (Me2NH2)2C2O4 salt and Sn(CH3)3Cl in a 2:1 ratio in ethanol. The asymmetric unit comprises a di­methyl­ammonium cation (Me2NH2 +), an hydrogenoxalate anion (HC2O4 −), and half a mol­ecule of oxalic acid (H2C2O4) situated about an inversion center. From a supra­molecular point of view, the three components inter­act together via hydrogen bonding. The Me2NH2 + cations and the HC2O4 − anions are in close proximity through bifurcated N—H⋯(O,O) hydrogen bonds, while the HC2O4 − anions are organized into infinite chains via O—H⋯O hydrogen bonds, propagating along the a-axis direction. In addition, the oxalic acid (H2C2O4) mol­ecules play the role of connectors between these chains. Both the carbonyl and hydroxyl groups of each diacid are involved in four inter­molecular inter­actions with two Me2NH2 + and two HC2O4 − ions of four distinct polymeric chains, via two N—H⋯O and two O—H⋯O hydrogen bonds, respectively. The resulting mol­ecular assembly can be viewed as a two-dimensional bilayer-like arrangement lying parallel to (010), and reinforced by a C—H⋯O hydrogen bond. PMID:25995858

  20. Oxalic acid has an additional, detoxifying function in Sclerotinia sclerotiorum pathogenesis.

    PubMed

    Heller, Annerose; Witt-Geiges, Tanja

    2013-01-01

    The mechanism of the diseases caused by the necrotroph plant pathogen Sclerotinia sclerotiorum is not well understood. To investigate the role of oxalic acid during infection high resolution, light-, scanning-, transmission electron microscopy and various histochemical staining methods were used. Our inoculation method allowed us to follow degradation of host plant tissue around single hyphae and to observe the reaction of host cells in direct contact with single invading hyphae. After penetration the outer epidermal cell wall matrix appeared degraded around subcuticular hyphae (12-24 hpi). Calcium oxalate crystals were detected in advanced (36-48 hpi) and late (72 hpi) infection stages, but not in early stages. In early infection stages, surprisingly, no toxic effect of oxalic acid eventually secreted by S. sclerotiorum was observed. As oxalic acid is a common metabolite in plants, we propose that attacked host cells are able to metabolize oxalic acid in the early infection stage and translocate it to their vacuoles where it is stored as calcium oxalate. The effects, observed on healthy tissue upon external application of oxalic acid to non-infected, living tissue and cell wall degradation of dead host cells starting at the inner side of the walls support this idea. The results indicate that oxalic acid concentrations in the early stage of infection stay below the toxic level. In plant and fungi oxalic acid/calcium oxalate plays an important role in calcium regulation. Oxalic acid likely could quench calcium ions released during cell wall breakdown to protect growing hyphae from toxic calcium concentrations in the infection area. As calcium antimonate-precipitates were found in vesicles of young hyphae, we propose that calcium is translocated to the older parts of hyphae and detoxified by building non-toxic, stable oxalate crystals. We propose an infection model where oxalic acid plays a detoxifying role in late infection stages.

  1. Field Assessment of Yeast- and Oxalic Acid-generated Carbon Dioxide for Mosquito Surveillance

    DTIC Science & Technology

    2014-12-01

    FIELD ASSESSMENT OF YEAST- AND OXALIC ACID –GENERATED CARBON DIOXIDE FOR MOSQUITO SURVEILLANCE1 JAMES F. HARWOOD, ALEC G. RICHARDSON, JENNIFER A...were evaluated in order to address this capability gap: 1) an electrolyzer that converts solid oxalic acid into CO2 gas, and 2) CO2 produced by yeast...surveillance was compared to dry ice and compressed gas in Jacksonville, FL. The electrolyzed oxalic acid only slightly increased the number of

  2. The oxalic acid biosynthetic activity of Burkholderia mallei is encoded by a single locus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although it is known that oxalic acid provides a selective advantage to the secreting microbe, our understanding of how this acid is biosynthesized remains incomplete. This study reports the identification, cloning, and partial characterization of the oxalic acid biosynthetic enzyme from the animal ...

  3. COMPARISON OF OXALIC ACID CLEANING RESULTS AT SRS AND HANFORD AND THE IMPACT ON ENHANCED CHEMICAL CLEANING DEPLOYMENT

    SciTech Connect

    Spires, R.; Ketusky, E.

    2010-01-05

    Waste tanks must be rendered clean enough to satisfy very rigorous tank closure requirements. During bulk waste removal, most of the radioactive sludge and salt waste is removed from the waste tank. The waste residue on the tank walls and interior components and the waste heel at the bottom of the tank must be removed prior to tank closure to render the tank clean enough to meet the regulatory requirement for tank closure. Oxalic acid has been used within the DOE complex to clean residual materials from carbon steel tanks with varying degrees of success. Oxalic acid cleaning will be implemented at both the Savannah River Site and Hanford to clean tanks and serves as the core cleaning technology in the process known as Enhanced Chemical Cleaning. Enhanced Chemical Cleaning also employs a process that decomposes the spent oxalic acid solutions. The oxalic acid cleaning campaigns that have been performed at the two sites dating back to the 1980's are compared. The differences in the waste characteristics, oxalic acid concentrations, flushing, available infrastructure and execution of the campaigns are discussed along with the impact on the effectiveness of the process. The lessons learned from these campaigns that are being incorporated into the project for Enhanced Chemical Cleaning are also explored.

  4. Facile C(sp(2))-C(sp(2)) bond cleavage in oxalic acid-derived radicals.

    PubMed

    Molt, Robert W; Lecher, Alison M; Clark, Timothy; Bartlett, Rodney J; Richards, Nigel G J

    2015-03-11

    Oxalate decarboxylase (OxDC) catalyzes the Mn-dependent conversion of the oxalate monoanion into CO2 and formate. Many questions remain about the catalytic mechanism of OxDC although it has been proposed that the reaction proceeds via substrate-based radical intermediates. Using coupled cluster theory combined with implicit solvation models we have examined the effects of radical formation on the structure and reactivity of oxalic acid-derived radicals in aqueous solution. Our results show that the calculated solution-phase free-energy barrier for C-C bond cleavage to form CO2 is decreased from 34.2 kcal/mol for oxalic acid to only 9.3 kcal/mol and a maximum of 3.5 kcal/mol for the cationic and neutral oxalic acid-derived radicals, respectively. These studies also show that the C-C σ bonding orbital of the radical cation contains only a single electron, giving rise to an elongated C-C bond distance of 1.7 Å; a similar lengthening of the C-C bond is not observed for the neutral radical. This study provides new chemical insights into the structure and stability of plausible intermediates in the catalytic mechanism of OxDC, and suggests that removal of an electron to form a radical (with or without the concomitant loss of a proton) may be a general strategy for cleaving the unreactive C-C bonds between adjacent sp(2)-hybridized carbon atoms.

  5. Sugar yields from dilute oxalic acid pretreatment of maple wood compared to those with other dilute acids and hot water.

    PubMed

    Zhang, Taiying; Kumar, Rajeev; Wyman, Charles E

    2013-01-30

    Dilute oxalic acid pretreatment was applied to maple wood to improve compatibility with downstream operations, and its performance in pretreatment and subsequent enzymatic hydrolysis was compared to results for hydrothermal and dilute hydrochloric and sulfuric acid pretreatments. The highest total xylose yield of ∼84% of the theoretical maximum was for both 0.5% oxalic and sulfuric acid pretreatment at 160 °C, compared to ∼81% yield for hydrothermal pretreatment at 200 °C and for 0.5% hydrochloric acid pretreatment at 140 °C. The xylooligomer fraction from dilute oxalic acid pretreatment was only 6.3% of the total xylose in solution, similar to results with dilute hydrochloric and sulfuric acids but much lower than the ∼70% value for hydrothermal pretreatment. Combining any of the four pretreatments with enzymatic hydrolysis with 60 FPU cellulase/g of glucan plus xylan in the pretreated maple wood resulted in virtually the same total glucose plus xylose yields of ∼85% of the maximum possible.

  6. Pseudomonas fluorescens ATCC 13525 containing an artificial oxalate operon and Vitreoscilla hemoglobin secretes oxalic acid and solubilizes rock phosphate in acidic alfisols.

    PubMed

    Yadav, Kavita; Kumar, Chanchal; Archana, G; Naresh Kumar, G

    2014-01-01

    Oxalate secretion was achieved in Pseudomonas fluorescens ATCC 13525 by incorporation of genes encoding Aspergillus niger oxaloacetate acetyl hydrolase (oah), Fomitopsis plaustris oxalate transporter (FpOAR) and Vitreoscilla hemoglobin (vgb) in various combinations. Pf (pKCN2) transformant containing oah alone accumulated 19 mM oxalic acid intracellularly but secreted 1.2 mM. However, in the presence of an artificial oxalate operon containing oah and FpOAR genes in plasmid pKCN4, Pf (pKCN4) secreted 13.6 mM oxalate in the medium while 3.6 mM remained inside. This transformant solubilized 509 μM of phosphorus from rock phosphate in alfisol which is 4.5 fold higher than the Pf (pKCN2) transformant. Genomic integrants of P. fluorescens (Pf int1 and Pf int2) containing artificial oxalate operon (plac-FpOAR-oah) and artificial oxalate gene cluster (plac-FpOAR-oah, vgb, egfp) secreted 4.8 mM and 5.4 mM oxalic acid, released 329 μM and 351 μM P, respectively, in alfisol. The integrants showed enhanced root colonization, improved growth and increased P content of Vigna radiata plants. This study demonstrates oxalic acid secretion in P. fluorescens by incorporation of an artificial operon constituted of genes for oxalate synthesis and transport, which imparts mineral phosphate solubilizing ability to the organism leading to enhanced growth and P content of V. radiata in alfisol soil.

  7. The fluorimetric determination of oxalic acid in blood and other biological materials

    PubMed Central

    Zarembski, P. M.; Hodgkinson, A.

    1965-01-01

    1. Oxalic acid is separated from interfering substances by extraction with tri-n-butyl phosphate followed by co-precipitation with calcium sulphate. The precipitated oxalic acid is then reduced to glyoxylic acid, which is coupled with resorcinol to form a coloured fluorescent complex. 2. The spectrofluorometric method described is sensitive and highly specific, the minimum detectable amount of oxalic acid being 0·9μmole under the recommended conditions. 3. The concentration of oxalic acid in blood from 15 normal adults was 200–320μg./100ml. For serum the range was 135–280μg./100ml. The urinary excretion of oxalic acid by 60 normal adults on a normal diet was 9·0–28·5mg./24hr. PMID:5862411

  8. Oxalic acid biosynthesis is encoded by an operon in Burkholderia glumae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although the biosynthesis of oxalic acid is known to occur in a number of bacteria, the mechanism(s) regulating its production remains largely unknown. To date, there is no report on the identification of an oxalic acid biosynthetic pathway gene from bacteria. In an attempt to identify such a gene...

  9. Oxalic acid biosynthesis is encoded by an operon in Burkholderia glumae.

    PubMed

    Nakata, Paul A; He, Cixin

    2010-03-01

    Although the biosynthesis of oxalic acid is known to occur in a number of bacteria, the mechanism(s) regulating its production remains largely unknown. To date, there is no report on the identification of an oxalic acid biosynthetic pathway gene from bacteria. In an attempt to identify such a gene(s), a mutant screen was conducted using the simple oxalic acid-producing phytopathogenic bacterium, Burkholderia glumae. Four mutants that failed to produce oxalic acid were isolated from a transposon-mutagenized B. glumae library and named Burkholderia oxalate defective (Bod)1. DNA sequence analysis revealed that each mutant contained an insertion event at different sites in the same ORF, which we referred to as the oxalate biosynthetic component (obc)A locus. Complementation of the Bod1 mutant with the obcA gene, however, resulted only in a partial restoration of the oxalic acid-producing phenotype. Further complementation studies utilizing a larger DNA fragment encompassing the obcA locus coupled with deletion mutagenesis led to the identification of another ORF that we named the obcB locus, which was essential for higher levels of oxalic acid production. Transcript analysis indicated that both obcA and obcB are coexpressed and encoded on a single polycistron message.

  10. The pathogenic white-rot fungus Heterobasidion parviporum responds to spruce xylem defense by enhanced production of oxalic acid.

    PubMed

    Nagy, Nina Elisabeth; Kvaalen, Harald; Fongen, Monica; Fossdal, Carl Gunnar; Clarke, Nicholas; Solheim, Halvor; Hietala, Ari M

    2012-11-01

    Pathogen challenge of tree sapwood induces the formation of reaction zones with antimicrobial properties such as elevated pH and cation content. Many fungi lower substrate pH by secreting oxalic acid, its conjugate base oxalate being a reductant as well as a chelating agent for cations. To examine the role of oxalic acid in pathogenicity of white-rot fungi, we conducted spatial quantification of oxalate, transcript levels of related fungal genes, and element concentrations in heartwood of Norway spruce challenged naturally by Heterobasidion parviporum. In the pathogen-compromised reaction zone, upregulation of an oxaloacetase gene generating oxalic acid coincided with oxalate and cation accumulation and presence of calcium oxalate crystals. The colonized inner heartwood showed trace amounts of oxalate. Moreover, fungal exposure to the reaction zone under laboratory conditions induced oxaloacetase and oxalate accumulation, whereas heartwood induced a decarboxylase gene involved in degradation of oxalate. The excess level of cations in defense xylem inactivates pathogen-secreted oxalate through precipitation and, presumably, only after cation neutralization can oxalic acid participate in lignocellulose degradation. This necessitates enhanced production of oxalic acid by H. parviporum. This study is the first to determine the true influence of white-rot fungi on oxalate crystal formation in tree xylem.

  11. Availability to rats of iron from spinach: Effects of oxalic acid.

    PubMed

    Van Campen, D R; Welch, R M

    1980-08-01

    The availability to rats of iron from two varieties of spinach was determined. Also, the absorption of Fe was compared between FeCl3 and Fe-oxalate and the effects of adding 0.75% oxalate to the diet were determined. Absorption of iron from both varieties of spinach was comparable to that from FeCl3 and the iron was equally available from Fe-oxalate and FeCl3. The addition of 0.75% oxalic acid to the diet did not depress iron absorption and, if anything, appeared to enhance iron utilization by rats.

  12. Old acid, new chemistry. Negative metal anions generated from alkali metal oxalates and others.

    PubMed

    Curtis, Sharon; Renaud, Justin; Holmes, John L; Mayer, Paul M

    2010-11-01

    A brief search in Sci Finder for oxalic acid and oxalates will reward the researcher with a staggering 129,280 hits. However, the generation of alkali metal and silver anions via collision-induced dissociation of the metal oxalate anion has not been previously been reported, though Tian and coworkers recently investigated the dissociation of lithium oxalate. The exothermic decomposition of alkali metal oxalate anion to carbon dioxide in the collision cell of a triple quadrupole mass spectrometer leaves no place for the electron to reside, resulting in a double electron-transfer reaction to produce an alkali metal anion. This reaction is facilitated by the negative electron affinity of carbon dioxide and, as such, the authors believe that metal oxalates are potentially unique in this respect. The observed dissociation reactions for collision with argon gas (1.7-1.8 × 10(-3) mbar) for oxalic acid and various alkali metal oxalates are discussed and summarized. Silver oxalate is also included to demonstrate the propensity of this system to generate transition-metal anions, as well.

  13. Determination of trace amount of oxalic acid with zirconium(IV)-(DBS-arsenazo) by spectrophotometry

    NASA Astrophysics Data System (ADS)

    Zhai, Qing-Zhou

    2008-11-01

    A novel method is proposed for the determination of trace amount of oxalic acid in the present article. In 1.0 M hydrochloric acid medium, oxalic acid can react with the zirconium(IV) in Zr(IV)-(DBS-arsenazo) complex and replaces the DBS-arsenazo to produce a hyperchromic effect at 520 nm. The hyperchromic degree is proportional to the concentration of the oxalic acid added over a defined range. Based on this property, a new method for the spectrophotometric determination of trace oxalic acid was developed. Beer's law is held over the concentration range of 9.0 × 10 -6 to 5.0 × 10 -4 M for oxalic acid with a correlation coefficient of 0.9995. The apparent molar absorptivity of the method is ɛ520 nm = 1.16 × 10 3 L mol -1 cm -1 and the detection limit for oxalic acid is 0.815 μg/mL. The developed method was directly applied to the determination of oxalic acid in tomato samples with satisfactory results.

  14. Determination of trace amount of oxalic acid with zirconium(IV)-(DBS-arsenazo) by spectrophotometry.

    PubMed

    Zhai, Qing-Zhou

    2008-11-15

    A novel method is proposed for the determination of trace amount of oxalic acid in the present article. In 1.0M hydrochloric acid medium, oxalic acid can react with the zirconium(IV) in Zr(IV)-(DBS-arsenazo) complex and replaces the DBS-arsenazo to produce a hyperchromic effect at 520 nm. The hyperchromic degree is proportional to the concentration of the oxalic acid added over a defined range. Based on this property, a new method for the spectrophotometric determination of trace oxalic acid was developed. Beer's law is held over the concentration range of 9.0 x 10(-6) to 5.0 x 10(-4)M for oxalic acid with a correlation coefficient of 0.9995. The apparent molar absorptivity of the method is epsilon520 nm = 1.16 x 10(3)L mol(-1)cm(-1) and the detection limit for oxalic acid is 0.815 microg/mL. The developed method was directly applied to the determination of oxalic acid in tomato samples with satisfactory results.

  15. Biodegradation of oxalic acid from spinach using cereal radicles.

    PubMed

    Betsche, Thomas; Fretzdorff, Barbara

    2005-12-14

    A high level of oxalate intake constitutes a health risk for infants and metabolically disposed adults. Spinach, acclaimed for its many health benefits, is among the vegetables richest in oxalate. Blanching reduces oxalate unsatisfactorily and unspecifically. An alternative, biological method is proposed on the basis of rye seedlings or radicles (also barley and wheat) containing an oxalate-specific oxalate oxidase by nature. Dissolved oxalate (0.25 mM) was rapidly degraded in the presence of radicles (e.g., 70% within 100 min). With commercial deep-frozen spinach, near-complete degradation of soluble oxalate was achieved at pH 3.5. The total level of oxalate was reduced by half. Similarly high rates occurred from 18 to 35 degrees C. Even at 55 degrees C appreciable rates were observed. The seedling as a whole is effective, too, and enrichment with cereal-specific healthy components would occur. Removal of oxalate from other vegetables, juices, cycled process waters, or feeds is conceivable with fresh or heat-dried cereal seedlings or radicles.

  16. Removal of aqueous oxalic acid by heterogeneous catalytic ozonation with MnOx/sewage sludge-derived activated carbon as catalysts.

    PubMed

    Huang, Yuanxing; Sun, Yaru; Xu, Zhihua; Luo, Mengyu; Zhu, Chunlei; Li, Liang

    2017-01-01

    MnOx/sewage sludge-derived activated carbon (MnOx/SAC) was prepared as catalysts to improve the performance of aqueous oxalic acid degradation by ozonation. The results indicated that MnOx/SAC had excellent catalytic activity in mineralization of oxalic acid during heterogeneous catalytic ozonation process. MnOx/SAC with a manganese load of 30% exhibited the strongest catalytic activity under the condition of solution pH3.5, which enhanced the oxalic acid removal from 10.3% to 92.2% in 60min compared with that treated by ozone alone. Increase of catalyst dosage and aqueous ozone concentration was advantageous for oxalic acid removal from water. On the basis of catalyst characterization analysis and the observation of inhibitory effect induced by higher pH, less catalyst dosage as well as the presence of hydroxyl radical scavenger, it was deduced that the reaction mechanism involved both hydroxyl radicals attack and surface reactions.

  17. Influence of oxalic acid formed on the degradation of phenol by Fenton reagent.

    PubMed

    Nakagawa, Hiroyuki; Yamaguchi, Emi

    2012-06-01

    The objective of this work is to examine the influence of oxalic acid formed on the degradation of phenol by Fenton reagent. Oxalic acid formed at initial stage within 30 min significantly suppresses the reduction of ferric ion, thus terminating degradation reaction. The yield of oxalic acid is dependent on the amount of ferrous ion dosed since the minimal amount of oxalic acid is formed after the degradation reaction terminates. Mineralization of phenol by Fenton reagent stagnates after 120 min under the conditions used in this study. The reason why the mineralization stagnated can be assumed to be following two mechanisms other than the depletion of H(2)O(2). In the case where a small amount of ferrous ions is dosed, the reduction of ferric ions is minimal by oxalic acid formed. In the case where a large amount of ferrous ions is dosed, the amount of degradable organic compounds is insufficient owing to preferential conversion to oxalic acid. The mineralization can be enhanced by the intermittent dosing of ferrous ions, which facilitates the suppression of oxalic acid formation during the degradation by Fenton reagent.

  18. Effect of waters of crystallization on terahertz spectra: anhydrous oxalic acid and its dihydrate.

    PubMed

    King, Matthew D; Korter, Timothy M

    2010-07-08

    Oxalic acid and oxalic acid dihydrate were studied using terahertz spectroscopy and solid-state density functional theory (DFT) in the spectral range 10-100 cm(-1). The size of the oxalic acid molecule and its limited internal degrees of freedom make it ideal for evaluating the performance of computational methods for the structural and dynamical simulation of strongly hydrogen-bonded solids. Calculations of the solid-state structures and terahertz spectra of oxalic acid and oxalic acid dihydrate were performed using the hybrid B3LYP and B3PW91 and the nonhybrid BLYP and PW91 density functionals employing the 6-311G(2d,2p) basis set. When these simulations were compared to the experimental spectra of the oxalic acid solids, a constant overprediction of the dihydrate frequencies was observed in contrast to the results of the anhydrous system. This change in behavior is connected to the nature of the vibrational motions being accessed. The primary molecular motion contributions to the terahertz vibrations of oxalic acid dihydrate were found to originate in the external motions of the cocrystallized H(2)O molecules. The observed overestimation of the vibrational energies in the simulated terahertz spectra is attributed to increased anharmonicity of the vibrational motions in the dihydrate system versus the anhydrous, resulting from weaker hydrogen bonding through the networked water molecules.

  19. Equilibrium studies of oxalate and aluminum containing solutions

    SciTech Connect

    Hay, M. S.; King, W. D.; Peters, T. B.; Jones, D. H.

    2015-11-01

    The Savannah River National Laboratory (SRNL) was tasked to develop data on the solubility and conditions leading to precipitation of sodium oxalate, sodium nitrate, Bayerite (a polymorph of gibbsite, Al(OH)3), and sodium aluminosilicate solids recently found in the Modular Caustic Side Solvent Extraction Unit (MCU). The data generated will be used to improve the OLI Systems thermodynamic database for these compounds allowing better prediction of solids formation by the modeling software in the future.

  20. Modeling aqueous ozone/UV process using oxalic acid as probe chemical.

    PubMed

    Garoma, Temesgen; Gurol, Mirat D

    2005-10-15

    A kinetic model that describes the removal of organic pollutants by an ozone/UV process is described. Oxalic acid, which reacts with a very low rate constant with ozone and relatively high rate constant with hydroxyl radical (OH*), was used as the probe chemical to model the process. The model was verified by experimental data on concentrations of oxalic acid and hydrogen peroxide (H202) under various experimental conditions, i.e., ozone gas dosage, UV light intensity, and varying oxalic acid concentrations.

  1. Enhanced Nitrogen Availability in Karst Ecosystems by Oxalic Acid Release in the Rhizosphere

    PubMed Central

    Pan, Fujing; Liang, Yueming; Zhang, Wei; Zhao, Jie; Wang, Kelin

    2016-01-01

    In karst ecosystems, a high level of CaCO3 enhances the stabilization of soil organic matter (SOM) and causes nitrogen (N) and/or phosphorus (P) limitation in plants. Oxalic acid has been suggested to be involved in the nutrient-acquisition strategy of plants because its addition can temporarily relieve nutrient limitation. Therefore, understanding how oxalic acid drives N availability may help support successful vegetation restoration in the karst ecosystems of southwest China. We tested a model suggested by Clarholm et al. (2015) where oxalate reacts with Ca bridges in SOM, thus exposing previously protected areas to enzymatic attacks in a way that releases N for local uptake. We studied the effects of oxalic acid, microbial biomass carbon (MBC), and β-1,4-N-acetylglucosaminidase (NAG) on potential N mineralization rates in rhizosphere soils of four plant species (two shrubs and two trees) in karst areas. The results showed that rhizosphere soils of shrubs grown on formerly deforested land had significantly lower oxalic acid concentrations and NAG activity than that of trees in a 200-year-old forest. The levels of MBC in rhizosphere soils of shrubs were significantly lower than those of trees in the growing season, but the measure of shrubs and trees were similar in the non-growing season; the potential N mineralization rates showed a reverse pattern. Positive relationships were found among oxalic acid, MBC, NAG activity, and potential N mineralization rates for both shrubs and trees. This indicated that oxalic acid, microbes, and NAG may enhance N availability for acquisition by plants. Path analysis showed that oxalic acid enhanced potential N mineralization rates indirectly through inducing microbes and NAG activities. We found that the exudation of oxalic acid clearly provides an important mechanism that allows plants to enhance nutrient acquisition in karst ecosystems. PMID:27252713

  2. Enhanced Nitrogen Availability in Karst Ecosystems by Oxalic Acid Release in the Rhizosphere.

    PubMed

    Pan, Fujing; Liang, Yueming; Zhang, Wei; Zhao, Jie; Wang, Kelin

    2016-01-01

    In karst ecosystems, a high level of CaCO3 enhances the stabilization of soil organic matter (SOM) and causes nitrogen (N) and/or phosphorus (P) limitation in plants. Oxalic acid has been suggested to be involved in the nutrient-acquisition strategy of plants because its addition can temporarily relieve nutrient limitation. Therefore, understanding how oxalic acid drives N availability may help support successful vegetation restoration in the karst ecosystems of southwest China. We tested a model suggested by Clarholm et al. (2015) where oxalate reacts with Ca bridges in SOM, thus exposing previously protected areas to enzymatic attacks in a way that releases N for local uptake. We studied the effects of oxalic acid, microbial biomass carbon (MBC), and β-1,4-N-acetylglucosaminidase (NAG) on potential N mineralization rates in rhizosphere soils of four plant species (two shrubs and two trees) in karst areas. The results showed that rhizosphere soils of shrubs grown on formerly deforested land had significantly lower oxalic acid concentrations and NAG activity than that of trees in a 200-year-old forest. The levels of MBC in rhizosphere soils of shrubs were significantly lower than those of trees in the growing season, but the measure of shrubs and trees were similar in the non-growing season; the potential N mineralization rates showed a reverse pattern. Positive relationships were found among oxalic acid, MBC, NAG activity, and potential N mineralization rates for both shrubs and trees. This indicated that oxalic acid, microbes, and NAG may enhance N availability for acquisition by plants. Path analysis showed that oxalic acid enhanced potential N mineralization rates indirectly through inducing microbes and NAG activities. We found that the exudation of oxalic acid clearly provides an important mechanism that allows plants to enhance nutrient acquisition in karst ecosystems.

  3. DEPOSITION TANK CORROSION TESTING FOR ENHANCED CHEMICAL CLEANING POST OXALIC ACID DESTRUCTION

    SciTech Connect

    Mickalonis, J.

    2011-08-29

    An Enhanced Chemical Cleaning (ECC) process is being developed to aid in the high level waste tank closure at the Savannah River Site. The ECC process uses an advanced oxidation process (AOP) to destroy the oxalic acid that is used to remove residual sludge from a waste tank prior to closure. The AOP process treats the dissolved sludge with ozone to decompose the oxalic acid through reactions with hydroxyl radicals. The effluent from this oxalic acid decomposition is to be sent to a Type III waste tank and may be corrosive to these tanks. As part of the hazardous simulant testing that was conducted at the ECC vendor location, corrosion testing was conducted to determine the general corrosion rate for the deposition tank and to assess the susceptibility to localized corrosion, especially pitting. Both of these factors impact the calculation of hydrogen gas generation and the structural integrity of the tanks, which are considered safety class functions. The testing consisted of immersion and electrochemical testing of A537 carbon steel, the material of construction of Type III tanks, and 304L stainless steel, the material of construction for transfer piping. Tests were conducted in solutions removed from the destruction loop of the prototype ECC set up. Hazardous simulants, which were manufactured at SRNL, were used as representative sludges for F-area and H-area waste tanks. Oxalic acid concentrations of 1 and 2.5% were used to dissolve the sludge as a feed to the ECC process. Test solutions included the uninhibited effluent, as well as the effluent treated for corrosion control. The corrosion control options included mixing with an inhibited supernate and the addition of hydroxide. Evaporation of the uninhibited effluent was also tested since it may have a positive impact on reducing corrosion. All corrosion testing was conducted at 50 C. The uninhibited effluent was found to increase the corrosion rate by an order of magnitude from less than 1 mil per year (mpy

  4. The influence of dicarboxylic acids: Oxalic acid and tartaric acid on the compressive strength of glass ionomer cements

    NASA Astrophysics Data System (ADS)

    Permana, Ahmadi Jaya; Setyawati, Harsasi; Hamami, Murwani, Irmina Kris

    2016-03-01

    Glass ionomer cement (GIC) has limitation on the mechanical properties especially compressive strength. The change of compressive strength of GIC by adding oxalic acid and tartaric acid has been investigated. Oxalic acid and tartaric acid was added to the liquid components at concentrations of 0 - 15% (w/w). Powder component of GIC was made from optimum experimental powder glass SiO2-Al2O3-CaF2. GIC was characterized by compressive strength test, SEM-EDX and FTIR. The addition of tartaric acid to GIC has greater improvement than addition of oxalic acid. The addition of tartaric acid at 10 % (w/w) to GIC has greatest value of compressive strength.

  5. Flow injection spectrophotometric determination of ultra trace amounts of oxalic acid.

    PubMed

    Ensafi, A A; Kazemzadeh, A

    2000-07-01

    A new simple, sensitive and rapid catalytic-spectrophotometric method for the determination of oxalic acid has been described based on its catalytic effect on the redox reaction between dichromate and Brilliant cresyl blue in acidic media by means of a flow injection analysis method. The color change of Brilliant cresyl blue due to its oxidation was monitored spectrophotometrically at 625 nm. The calibration graph was linear in the range of 0.020-4.70 microg/mL oxalic acid with a limit of detection 0.005 microg/mL of oxalic acid. The relative standard deviation for ten replicate measurements of 0.020 microg/mL and 0.900 microg/mL was 2.2% and 1.7%, respectively. No serious interference was identified. Oxalic acid was determined in wastewater and in spinach by the proposed method with satisfactory results.

  6. Acute renal failure and metabolic acidosis due to oxalic acid intoxication: a case report.

    PubMed

    Yamamoto, Rie; Morita, Seiji; Aoki, Hiromichi; Nakagawa, Yoshihide; Yamamoto, Isotoshi; Inokuchi, Sadaki

    2011-12-20

    Most of the reports of oxalic acid intoxication are in cases of ethylene glycol intoxication. These symptoms are known to be central nerve system manifestations, cardiopulmonary manifestations and acute renal failure. There have been only a few reports of direct oxalic acid intoxication. However, there have been a few recent reports of oxalic acid intoxication due to the ingestion of star fruit and ascorbic acid. We herein report the case of a patient with acute renal failure and metabolic acidosis caused directly by consumption of oxalic acid. During the initial examination by the physician at our hospital, the patient presented with tachypnea, a precordinal burning sensation, nausea and metabolic acidosis. After admission, the patient developed renal failure and anion gap high metabolic acidosis, but did not develop any CNS or cardio-pulmonary manifestations in the clinical course. The patient benefitted symptomatically from hemodialysis.

  7. Biosynthesis of L-ascorbic acid and conversion of carbons 1 and 2 of L-ascorbic acid to oxalic acid occurs within individual calcium oxalate crystal idioblasts.

    PubMed

    Kostman, T A; Tarlyn, N M; Loewus, F A; Franceschi, V R

    2001-02-01

    L-Ascorbic acid (AsA) and its metabolic precursors give rise to oxalic acid (OxA) found in calcium oxalate crystals in specialized crystal idioblast cells in plants; however, it is not known if AsA and OxA are synthesized within the crystal idioblast cell or transported in from surrounding mesophyll cells. Isolated developing crystal idioblasts from Pistia stratiotes were used to study the pathway of OxA biosynthesis and to determine if idioblasts contain the entire path and are essentially independent in OxA synthesis. Idioblasts were supplied with various (14)C-labeled compounds and examined by micro-autoradiography for incorporation of (14)C into calcium oxalate crystals. [(14)C]OxA gave heavy labeling of crystals, indicating the isolated idioblasts are functional in crystal formation. Incubation with [1-(14)C]AsA also gave heavy labeling of crystals, whereas [6-(14)C]AsA gave no labeling. Labeled precursors of AsA (L-[1-(14)C]galactose; D-[1-(14)C]mannose) also resulted in crystal labeling, as did the ascorbic acid analog, D-[1-(14)C]erythorbic acid. Intensity of labeling of isolated idioblasts followed the pattern OxA > AsA (erythorbic acid) > L-galactose > D-mannose. Our results demonstrate that P. stratiotes crystal idioblasts synthesize the OxA used for crystal formation, the OxA is derived from the number 1 and 2 carbons of AsA, and the proposed pathway of ascorbic acid synthesis via D-mannose and L-galactose is operational in individual P. stratiotes crystal idioblasts. These results are discussed with respect to fine control of calcium oxalate precipitation and the concept of crystal idioblasts as independent physiological compartments.

  8. Role of Oxalic Acid Overexcretion in Transformations of Toxic Metal Minerals by Beauveria caledonica

    PubMed Central

    Fomina, M.; Hillier, S.; Charnock, J. M.; Melville, K.; Alexander, I. J.; Gadd, G. M.

    2005-01-01

    The fungus Beauveria caledonica was highly tolerant to toxic metals and solubilized cadmium, copper, lead, and zinc minerals, converting them into oxalates. This fungus was found to overexcrete organic acids with strong metal-chelating properties (oxalic and citric acids), suggesting that a ligand-promoted mechanism was the main mechanism of mineral dissolution. Our data also suggested that oxalic acid was the main mineral-transforming agent. Cadmium, copper, and zinc oxalates were precipitated by the fungus in the local environment and also in association with the mycelium. The presence of toxic metal minerals often led to the formation of mycelial cords, and in the presence of copper-containing minerals, these cords exhibited enhanced excretion of oxalic acid, which resulted in considerable encrustation of the cords by copper oxalate hydrate (moolooite). It was found that B. caledonica hyphae and cords were covered by a thick hydrated mucilaginous sheath which provided a microenvironment for chemical reactions, crystal deposition, and growth. Cryo-scanning electron microscopy revealed that mycogenic metal oxalates overgrew parental fungal hyphae, leaving a labyrinth of fungal tunnels within the newly formed mineral matter. X-ray absorption spectroscopy revealed that oxygen ligands played a major role in metal coordination within the fungal biomass during the accumulation of mobilized toxic metals by B. caledonica mycelium; these ligands were carboxylic groups in copper phosphate-containing medium and phosphate groups in pyromorphite-containing medium. PMID:15640211

  9. The oxalic acid biosynthetic activity of Burkholderia mallei is encoded by a single locus.

    PubMed

    Nakata, Paul A

    2011-10-20

    Although it is known that oxalic acid provides a selective advantage to the secreting microbe our understanding of how this acid is biosynthesized remains incomplete. This study reports the identification, cloning, and partial characterization of the oxalic acid biosynthetic enzyme from the animal bacterial pathogen, Burkholderia mallei. The discovered gene was named oxalate biosynthetic component (obc)1. Complementation of Burkholderia oxalate defective (Bod)1, a Burkholderia glumae mutant that lacks expression of a functional oxalic acid biosynthetic operon, revealed that the obc1 was able to rescue the no oxalate mutant phenotype. This single gene rescue is in contrast to the situation found in B. glumae which required the expression of two genes, obcA and obcB, to achieve complementation. Enzyme assays showed that even though the two Burkholderia species differed in the number of genes required to encode a functional enzyme, both catalyzed the same acyl-CoA dependent biosynthetic reaction. In addition, mutagenesis studies suggested a similar domain structure of the assembled oxalate biosynthetic enzymes whether encoded by one or two genes.

  10. Voltammetric Detection of Oxalic Acid by Using Glassy Carbon Electrodes with Covalently Attached Nitrogen-containing Functional Groups.

    PubMed

    Matsuura, Hiroaki; Akabe, Syuhei; Kitamura, Tsubasa; Takahashi, Takuto; Uchiyama, Shunichi

    2015-01-01

    We report on a novel voltammetric detection of oxalic acid by using glassy carbon electrodes with covalently attached nitrogen-containing functional groups prepared by stepwise electrolysis. A glassy carbon electrode electrooxidized in an ammonium carbamate solution was electroreduced at -1.0 V (vs. Ag/AgCl) in 1.0 M sulfuric acid for a long time. We found that the electrocatalytic oxidation wave of oxalic acid obtained by this modified glassy carbon electrode was moved to a more negative potential region than that obtained by a platinum electrode in an acidic medium. A good linearity for the peak current signals was observed in the concentration range from 0.1 to 50 mM.

  11. A biogenic source of oxalic acid and glyoxal in marine boundary layer

    NASA Astrophysics Data System (ADS)

    Facchini, C.; Rinaldi, M.; Ceburnis, D.; O'Dowd, C.; Sciare, J.; Burrows, J. P.

    2011-12-01

    We present the results of oxalic acid aerosol measurements samples performed at Mace Head (Ireland, 53°20'N, 9°54'W) and Amsterdam Island (Indian Ocean, 37°48'S, 77°34'E), supporting the existence of a biogenic source of oxalic acid over the oceans. Aerosol oxalic acid was detected in clean marine air masses in concentrations ranging from 2.7 to 39 ng m-3, at Mace Head, and from 0.31 to 17 ng m-3, at Amsterdam Island. In both hemispheres, oxalic acid concentration showed a clear seasonal trend, with maxima in spring-summer and minima in the fall-winter period, in analogy with other marine biogenic aerosol components (e.g., MSA and amines). Oxalic acid was distributed along the whole aerosol size spectrum, with the major contribution given by the 1.0-2.0 μm size range, and by the lower accumulation mode (0.25-0.5 μm). Given the observed size distributions, marine aerosol oxalic acid can be assumed as the result of the combination of different formation processes, among which in-cloud oxidation of gaseous precursors [1] and photochemical degradation of biogenic unsaturated fatty acids [2] are likely the most important. Among aerosol oxalic acid precursors, glyoxal is the most likely candidate in the marine boundary layer, as a source of glyoxal over the oceans has recently been discovered by satellite observations [3] and confirmed by in situ measurements [4]. In support of this hypothesis, SCIAMACHY satellite retrieved glyoxal column concentrations, over the two sampling sites, resulted characterized by a clear seasonal trend, resembling the aerosol oxalic acid one. [1] Warneck, Atmospheric Environment, 37, 2423-2427, 2003. [2] Kawamura & Sakaguchi, J. Geophys. Res., 104, D3, 3501-3509, 1999. [3] Fu et al., J. Geophys. Res., 113, D15303, doi:10.1029/2007JD009505, 2008 [4] Sinreich et al., Atmos. Chem. Phys. Discuss., 10, 15075-15107, 2010.

  12. The combination of oxalic acid with power ultrasound fully degrades chrysotile asbestos fibres.

    PubMed

    Turci, Francesco; Tomatis, Maura; Mantegna, Stefano; Cravotto, Giancarlo; Fubini, Bice

    2007-10-01

    The simultaneous action of power ultrasound and oxalic acid, as a chelating agent, rapidly converts chrysotile asbestos into water soluble material and a non-asbestos debris, not classifiable as hazardous under worldwide safety regulations.

  13. Downscaled anodic oxidation process for aluminium in oxalic acid

    NASA Astrophysics Data System (ADS)

    Sieber, M.; Morgenstern, R.; Kuhn, D.; Hackert-Oschätzchen, M.; Schubert, A.; Lampke, T.

    2017-03-01

    The increasing multi-functionality of parts and assemblies in several fields of engineering demands, amongst others, highly functionalised surfaces. For the different applications, on the one hand, there is a need to scale up surface modification processes originating in the nano- and micro-scale. On the other hand, conventional macro-scale surface refinement methods offer a huge potential for application in the said nano- and micro-scale. The anodic oxidation process, which is established especially for aluminium and its alloys, allows the formation of oxide ceramic layers on the surface. The build-up of an oxide ceramic coating comes along with altered chemical, tribological and electrical surface properties. As a basis for further investigations regarding the use of the anodic oxidation process for micro-scale-manufacturing, the scale effects of oxalic acid anodising on commercially pure aluminium as well as on the AlZn5.5MgCu alloy are addressed in the present work. The focus is on the amount of oxide formed during a potentiostatic process in relation to the exchanged amount of charge. Further, the hardness of the coating as an integral measure to assess the porous oxide structure is approached by nano-indentation technique.

  14. Oxalic acid capped iron oxide nanorods as a sensing platform.

    PubMed

    Sharma, Anshu; Baral, Dinesh; Bohidar, H B; Solanki, Pratima R

    2015-08-05

    A label free impedimetric immunosensor has been fabricated using protein bovine serum albumin (BSA) and monoclonal antibodies against Vibrio cholerae (Ab) functionalized oxalic acid (OA) capped iron oxide (Fe3O4) nanorods for V. cholerae detection. The structural and morphological studies of Fe3O4 and OA-Fe3O4, were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and dynamic light scattering (DLS) techniques. The average crystalline size of Fe3O4, OA-Fe3O4 nanorods were obtained as about 29±1 and 39±1nm, respectively. The hydrodynamic radius of nanorods is found as 116nm (OA-Fe3O4) and 77nm (Fe3O4) by DLS measurement. Cytotoxicity of Fe3O4 and OA-Fe3O4 nanorods has been investigated in the presence of human epithelial kidney (HEK) cell line 293 using MTT assay. The cell viability and proliferation studies reveal that the OA-Fe3O4 nanorods facilitate cell growth. The results of electrochemical response studies of the fabricated BSA/Ab/OA-Fe2O3/ITO immunosensor exhibits good linearity in the range of 12.5-500ng mL(-1) with low detection limit of 0.5ng mL(-1), sensitivity 0.1Ωng(-1)ml(-1)cm(-2) and reproducibility more than 11 times.

  15. Evaluation of Pt Alloys as Electrocatalysts for Oxalic Acid Oxidation: A Combined Experimental and Computational Study

    DOE PAGES

    Perry, Albert; Babanova, Sofia; Matanovic, Ivana; ...

    2016-07-14

    Here in this study we combined experimental approaches and density functional theory to evaluate novel platinum-based materials as electrocatalysts for oxalic acid oxidation. Several Pt alloys, PtSn (1:1), PtSn (19:1), PtRu (1:4), PtRuSn (5:4:1), and PtRhSn (3:1:4), were synthetized using sacrificial support method and tested for oxidation of oxalic acid at pH 4. It was shown that PtSn (1:1) and PtRu (1:4) have higher mass activity relative to Pt. These two materials along with Pt and one of the least active alloys, PtSn (19:1), were further analyzed for the oxidation of oxalic acid at different pHs. The results show thatmore » all samples tested followed an identical trend of decreased onset potential with increased pH and increased catalytic activity with decreased pH. Density functional theory was further utilized to gain a fundamental knowledge about the mechanism of oxalic acid oxidation on Pt, PtSn (1:1), and PtRu (1:4). In conclusion, the results of the calculations along with the experimentally observed dependence of generated currents on the oxalic acid concentration indicate that the mechanism of oxalic acid oxidation on Pt proceeds without the participation of surface oxidizing species, while on Pt alloys it involves their participation.« less

  16. Evaluation of Pt Alloys as Electrocatalysts for Oxalic Acid Oxidation: A Combined Experimental and Computational Study

    SciTech Connect

    Perry, Albert; Babanova, Sofia; Matanovic, Ivana; Neumman, Anica; Serov, Alexey; Artyushkova, Kateryna; Atanassov, Plamen

    2016-07-14

    Here in this study we combined experimental approaches and density functional theory to evaluate novel platinum-based materials as electrocatalysts for oxalic acid oxidation. Several Pt alloys, PtSn (1:1), PtSn (19:1), PtRu (1:4), PtRuSn (5:4:1), and PtRhSn (3:1:4), were synthetized using sacrificial support method and tested for oxidation of oxalic acid at pH 4. It was shown that PtSn (1:1) and PtRu (1:4) have higher mass activity relative to Pt. These two materials along with Pt and one of the least active alloys, PtSn (19:1), were further analyzed for the oxidation of oxalic acid at different pHs. The results show that all samples tested followed an identical trend of decreased onset potential with increased pH and increased catalytic activity with decreased pH. Density functional theory was further utilized to gain a fundamental knowledge about the mechanism of oxalic acid oxidation on Pt, PtSn (1:1), and PtRu (1:4). In conclusion, the results of the calculations along with the experimentally observed dependence of generated currents on the oxalic acid concentration indicate that the mechanism of oxalic acid oxidation on Pt proceeds without the participation of surface oxidizing species, while on Pt alloys it involves their participation.

  17. Oxalic acid: a signal molecule for fungus-feeding bacteria of the genus Collimonas?

    PubMed

    Rudnick, M B; van Veen, J A; de Boer, W

    2015-10-01

    Mycophagous (=fungus feeding) soil bacteria of the genus Collimonas have been shown to colonize and grow on hyphae of different fungal hosts as the only source of energy and carbon. The ability to exploit fungal nutrient resources might require a strategy for collimonads to sense fungi in the soil matrix. Oxalic acid is ubiquitously secreted by soil fungi, serving different purposes. In this study, we investigated the possibility that collimonads might use oxalic acid secretion to localize a fungal host and move towards it. We first confirmed earlier indications that collimonads have a very limited ability to use oxalic acid as growth substrate. In a second step, with using different assays, we show that oxalic acid triggers bacterial movement in such a way that accumulation of cells can be expected at micro-sites with high free oxalic acid concentrations. Based on these observations we propose that oxalic acid functions as a signal molecule to guide collimonads to hyphal tips, the mycelial zones that are most sensitive for mycophagous bacterial attack.

  18. [Research on Raman spectra of oxalic acid during decarboxylation under high temperature and high pressure].

    PubMed

    Wang, Hui-yuan; Zheng, Hai-fei

    2012-03-01

    The present research studied the thermal stability of oxalic acid under high temperature and pressure and its in-situ transformation by Raman spectroscopy using a hydrothermal diamond anvil cell. Raman spectra allow the detection of ionic and covalent atomic aggregates through the acquisition of vibrational spectra that are characteristic of their structures and molecular bond types. The result showed that there was no change in characteristic vibrational Raman peaks of oxalic acid in the low-temperature stage. With the increase in temperature and pressure, the characteristic vibrational Raman peaks of oxalic acid became weaker and the peaks disappeared at a certain high temperature, and decarboxylation happened. Oxalic acid decomposes to produce CO2 and H2, according to the reaction: C2 H2O4-2CO2 + H2. It was found that the decarboxylation was highly related with pressure and that the decarboxylation would be hindered at high pressure. Decarboxylation of oxalic acid under high temperature and pressure showed a linear relationship between temperature and pressure. The data fitting generated the formula: P(MPa) = 12. 839T(K)-5 953.7, R2 = 0.99. The molar volume change of decarboxylation of oxalic acid can be described by deltaV(cm(-3) x mol(-1)) = 16.69-0.002P (MPa) + 0.005 2T(K), R = 0.99.

  19. Oxalic acid-induced modifications of postglycation activity of lysozyme and its glycoforms.

    PubMed

    Gao, Hong Ying; Yaylayan, Varoujan A; Yeboah, Faustinus

    2010-05-26

    The role of selected carboxylic acids and their potential to influence the glycation pattern and the enzymatic activity of lysozyme using glucose and ribose were investigated independently of the pH of the reaction medium. The model systems were incubated with and without selected carboxylic acids (maleic, acetic, oxalic, and citraconic) at 50 degrees C for 12 or 24 and 48 h at constant pH of 6.5. The effect of carboxylic acids on the glycation of lysozyme was studied by electrospray ionization mass spectrometry (ESI-MS) and by the measurement of the residual enzyme activity of lysozyme in the glycated samples. Of the carboxylic acids evaluated, oxalic acid showed the highest antiglycation activity. The residual lysozyme activity in both oxalic acid-glucose and oxalic acid-ribose systems was >80% compared with 46 and 36% activity in the controls of glucose and ribose systems, respectively. On the other hand, maleic, acetic, and citraconic acid containing systems with both sugars did not exhibit any enhanced enzyme activity relative to the controls. The results of this study show that oxalic acid was unique among the carboxylic acids evaluated with respect to its ability to interact with sugars and inhibit glycation.

  20. Screening of indigenous oxalate degrading lactic acid bacteria from human faeces and South Indian fermented foods: assessment of probiotic potential.

    PubMed

    Gomathi, Sivasamy; Sasikumar, Ponnusamy; Anbazhagan, Kolandaswamy; Sasikumar, Sundaresan; Kavitha, Murugan; Selvi, M S; Selvam, Govindan Sadasivam

    2014-01-01

    Lactic acid bacteria (LAB) have the potential to degrade intestinal oxalate and this is increasingly being studied as a promising probiotic solution to manage kidney stone disease. In this study, oxalate degrading LAB were isolated from human faeces and south Indian fermented foods, subsequently assessed for potential probiotic property in vitro and in vivo. Based on preliminary characteristics, 251 out of 673 bacterial isolates were identified as LAB. A total of 17 strains were found to degrade oxalate significantly between 40.38% and 62.90% and were subjected to acid and bile tolerance test. Among them, nine strains exhibited considerable tolerance up to pH 3.0 and at 0.3% bile. These were identified as Lactobacillus fermentum and Lactobacillus salivarius using 16S rDNA sequencing. Three strains, Lactobacillus fermentum TY5, Lactobacillus fermentum AB1, and Lactobacillus salivarius AB11, exhibited good adhesion to HT-29 cells and strong antimicrobial activity. They also conferred resistance to kanamycin, rifampicin, and ampicillin, but were sensitive to chloramphenicol and erythromycin. The faecal recovery rate of these strains was observed as 15.16% (TY5), 6.71% (AB1), and 9.3% (AB11) which indicates the colonization ability. In conclusion, three efficient oxalate degrading LAB were identified and their safety assessments suggest that they may serve as good probiotic candidates for preventing hyperoxaluria.

  1. Screening of Indigenous Oxalate Degrading Lactic Acid Bacteria from Human Faeces and South Indian Fermented Foods: Assessment of Probiotic Potential

    PubMed Central

    Kavitha, Murugan; Selvi, M. S.; Selvam, Govindan Sadasivam

    2014-01-01

    Lactic acid bacteria (LAB) have the potential to degrade intestinal oxalate and this is increasingly being studied as a promising probiotic solution to manage kidney stone disease. In this study, oxalate degrading LAB were isolated from human faeces and south Indian fermented foods, subsequently assessed for potential probiotic property in vitro and in vivo. Based on preliminary characteristics, 251 out of 673 bacterial isolates were identified as LAB. A total of 17 strains were found to degrade oxalate significantly between 40.38% and 62.90% and were subjected to acid and bile tolerance test. Among them, nine strains exhibited considerable tolerance up to pH 3.0 and at 0.3% bile. These were identified as Lactobacillus fermentum and Lactobacillus salivarius using 16S rDNA sequencing. Three strains, Lactobacillus fermentum TY5, Lactobacillus fermentum AB1, and Lactobacillus salivarius AB11, exhibited good adhesion to HT-29 cells and strong antimicrobial activity. They also conferred resistance to kanamycin, rifampicin, and ampicillin, but were sensitive to chloramphenicol and erythromycin. The faecal recovery rate of these strains was observed as 15.16% (TY5), 6.71% (AB1), and 9.3% (AB11) which indicates the colonization ability. In conclusion, three efficient oxalate degrading LAB were identified and their safety assessments suggest that they may serve as good probiotic candidates for preventing hyperoxaluria. PMID:24723820

  2. [Uric acid and oxalate lithiasis. Physico-chemical and crystallo-chemical explanation of the relationship].

    PubMed

    Leskovar, P

    1980-03-01

    It is tried to explain physico-chemically or crystallo-chemically the so-called "salting out effect", i.e. the influence of the Ca-oxalate precipitation by uric often discussed in urolith research which, indeed, is regarded as real by several researchers and by other investigators refused with emphasis, in order to understand better the connections between hyperuricosuria and oxalate lithiasis which obtrude themselves from the observation material. However, this phenomenon of the facilitated oxalate precipitation at increased uric acid level in the urine further needs directed research.

  3. THE QUANTUM YIELD OF OXYGEN PRODUCTION BY CHLOROPLASTS SUSPENDED IN SOLUTIONS CONTAINING FERRIC OXALATE

    PubMed Central

    French, C. S.; Rabideau, G. S.

    1945-01-01

    1. The quantum yield of oxygen liberation by spinach and Tradescantia chloroplasts suspended in solutions containing ferric oxalate and potassium ferricyanide varied from 0.013 to 0.080. 2. It was concluded that the nature of this oxygen liberation reaction is not fundamentally different from the formation of oxygen in normal photosynthesis, with respect to its light efficiency. PMID:19873423

  4. Biological Control of Meloidogyne incognita by Aspergillus niger F22 Producing Oxalic Acid

    PubMed Central

    Jang, Ja Yeong; Choi, Yong Ho; Shin, Teak Soo; Kim, Tae Hoon; Shin, Kee-Sun; Park, Hae Woong; Kim, Young Ho; Kim, Hun; Choi, Gyung Ja; Jang, Kyoung Soo; Cha, Byeongjin; Kim, In Seon; Myung, Eul Jae

    2016-01-01

    Restricted usage of chemical nematicides has led to development of environmentally safe alternatives. A culture filtrate of Aspergillus niger F22 was highly active against Meloidogyne incognita with marked mortality of second-stage juveniles (J2s) and inhibition of egg hatching. The nematicidal component was identified as oxalic acid by organic acid analysis and gas chromatography-mass spectroscopy (GC-MS). Exposure to 2 mmol/L oxalic acid resulted in 100% juvenile mortality at 1 day after treatment and suppressed egg hatching by 95.6% at 7 days after treatment. Oxalic acid showed similar nematicidal activity against M. hapla, but was not highly toxic to Bursaphelenchus xylophilus. The fungus was incubated on solid medium and dried culture was used for preparation of a wettable powder-type (WP) formulation as an active ingredient. Two WP formulations, F22-WP10 (ai 10%) and oxalic acid-WP8 (ai 8%), were prepared using F22 solid culture and oxalic acid. In a field naturally infested with M. incognita, application of a mixture of F22-WP10 + oxalic acid-WP8 at 1,000- and 500-fold dilutions significantly reduced gall formation on the roots of watermelon plants by 58.8 and 70.7%, respectively, compared to the non-treated control. The disease control efficacy of the mixture of F22-WP10 + oxalic acid-WP8 was significantly higher than that of a chemical nematicide, Sunchungtan (ai 30% fosthiazate). These results suggest that A. niger F22 can be used as a microbial nematicide for the control of root-knot nematode disease. PMID:27258452

  5. Biological Control of Meloidogyne incognita by Aspergillus niger F22 Producing Oxalic Acid.

    PubMed

    Jang, Ja Yeong; Choi, Yong Ho; Shin, Teak Soo; Kim, Tae Hoon; Shin, Kee-Sun; Park, Hae Woong; Kim, Young Ho; Kim, Hun; Choi, Gyung Ja; Jang, Kyoung Soo; Cha, Byeongjin; Kim, In Seon; Myung, Eul Jae; Kim, Jin-Cheol

    2016-01-01

    Restricted usage of chemical nematicides has led to development of environmentally safe alternatives. A culture filtrate of Aspergillus niger F22 was highly active against Meloidogyne incognita with marked mortality of second-stage juveniles (J2s) and inhibition of egg hatching. The nematicidal component was identified as oxalic acid by organic acid analysis and gas chromatography-mass spectroscopy (GC-MS). Exposure to 2 mmol/L oxalic acid resulted in 100% juvenile mortality at 1 day after treatment and suppressed egg hatching by 95.6% at 7 days after treatment. Oxalic acid showed similar nematicidal activity against M. hapla, but was not highly toxic to Bursaphelenchus xylophilus. The fungus was incubated on solid medium and dried culture was used for preparation of a wettable powder-type (WP) formulation as an active ingredient. Two WP formulations, F22-WP10 (ai 10%) and oxalic acid-WP8 (ai 8%), were prepared using F22 solid culture and oxalic acid. In a field naturally infested with M. incognita, application of a mixture of F22-WP10 + oxalic acid-WP8 at 1,000- and 500-fold dilutions significantly reduced gall formation on the roots of watermelon plants by 58.8 and 70.7%, respectively, compared to the non-treated control. The disease control efficacy of the mixture of F22-WP10 + oxalic acid-WP8 was significantly higher than that of a chemical nematicide, Sunchungtan (ai 30% fosthiazate). These results suggest that A. niger F22 can be used as a microbial nematicide for the control of root-knot nematode disease.

  6. Calcium oxalate syntheses in a solution containing glucose by the atmospheric pressure plasma irradiation

    NASA Astrophysics Data System (ADS)

    Kurake, Naoyuki; Tanaka, Hiromasa; Ishikawa, Kenji; Nakamura, Kae; Kajiyama, Hiroaki; Kikkawa, Fumitaka; Mizuno, Masaaki; Yamanishi, Yoko; Hori, Masaru

    2016-09-01

    The non-equilibrium atmospheric pressure plasma (NEAPP) has been attracted attention because of its characteristic high reactivity even in a low temperature so that various phenomena by the NEAPP such as a sterilization, growth promotion and so forth have been reported around the world. Previously, we reported the NEAPP irradiation generated the calcium oxalate crystals in the medium, which contains 31 kinds of organics and inorganics. The Dulbecco's Modified Eagle Medium (DMEM) which was used in previous study is composed of no oxalate. Interestingly, not only crystallization but also synthesis of the oxalate was occurred by the NEAPP irradiation. Also the crystallization details were analyzed with the X-ray diffraction (XRD). In this study, we have clarified the mechanism on the crystallization due that D-glucose, calcium ion and bicarbonate ions are minimum essential components. The oxalate synthesis was proved by the gas chromatography and mass spectrometer (GC-MS). Finally, we conclude that a supersaturation of oxalic acid synthesized in those 3 species by the NEAPP.

  7. LITERATURE REVIEW FOR OXALATE OXIDATION PROCESSES AND PLUTONIUM OXALATE SOLUBILITY

    SciTech Connect

    Nash, C.

    2012-02-03

    A literature review of oxalate oxidation processes finds that manganese(II)-catalyzed nitric acid oxidation of oxalate in precipitate filtrate is a viable and well-documented process. The process has been operated on the large scale at Savannah River in the past, including oxidation of 20 tons of oxalic acid in F-Canyon. Research data under a variety of conditions show the process to be robust. This process is recommended for oxalate destruction in H-Canyon in the upcoming program to produce feed for the MOX facility. Prevention of plutonium oxalate precipitation in filtrate can be achieved by concentrated nitric acid/ferric nitrate sequestration of oxalate. Organic complexants do not appear practical to sequester plutonium. Testing is proposed to confirm the literature and calculation findings of this review at projected operating conditions for the upcoming campaign. H Canyon plans to commence conversion of plutonium metal to low-fired plutonium oxide in 2012 for eventual use in the Mixed Oxide Fuel (MOX) Facility. The flowsheet includes sequential operations of metal dissolution, ion exchange, elution, oxalate precipitation, filtration, and calcination. All processes beyond dissolution will occur in HB-Line. The filtration step produces an aqueous filtrate that may have as much as 4 M nitric acid and 0.15 M oxalate. The oxalate needs to be removed from the stream to prevent possible downstream precipitation of residual plutonium when the solution is processed in H Canyon. In addition, sending the oxalate to the waste tank farm is undesirable. This report addresses the processing options for destroying the oxalate in existing H Canyon equipment.

  8. Urinary excretion of orally administered oxalic acid in saccharin and o-phenylphenol-fed NMRI mice.

    PubMed

    Salminen, E; Salminen, S

    1986-01-01

    Both saccharin and o-phenylphenol have been suggested to be carcinogenic to the urinary bladder in experimental animals, but the mechanism has remained unclear. The aim of this study was to investigate the effects of dietary saccharin and o-phenylphenol on the urinary excretion of dietary oxalic acid. Male NMRI mice were gradually adapted to either 3% o-phenylphenol or 5% saccharin in their diet. Having being adapted to these diets for 1 week or after consuming them for 3 months, the animals were fasted for 6 h and given a 2.5-microCi oral dose of U-14C-oxalic acid. Dosed animals were kept in metabolism cages for 48 h to monitor urinary and fecal excretion of the label. Adaptation to dietary o-phenylphenol appeared to increase the urinary excretion of orally administered U-14C-oxalic acid when food and water were available during urinary and fecal collections. Adaptation to dietary saccharin had little effect on urinary oxalate levels when compared to control animals. These results indicate that changes in urinary oxalate levels should be more carefully studied in connection with potential urinary bladder carcinogens to avoid the possibility of bladder irritation by increased urinary oxalate excretion.

  9. Comparison of sulfuric and oxalic acid anodizing for preparation of thermal control coatings for spacecraft

    NASA Technical Reports Server (NTRS)

    Le, Huong G.; Watcher, John M.; Smith, Charles A.

    1988-01-01

    The development of thermal control surfaces, which maintain stable solar absorptivity and infrared emissivity over long periods, is challenging due to severe conditions in low-Earth orbit (LEO). Some candidate coatings are second-surface silver-coated Teflon; second-surface, silvered optical solar reflectors made of glass or quartz; and anodized aluminum. Sulfuric acid anodized and oxalic acid anodized aluminum was evaluated under simulated LEO conditions. Oxalic acid anodizing shows promise of greater stability in LEO over long missions, such as the 30 years planned for the Space Station. However, sulfuric acid anodizing shows lower solar absorptivity.

  10. Interaction of gas phase oxalic acid with ammonia and its atmospheric implications.

    PubMed

    Peng, Xiu-Qiu; Liu, Yi-Rong; Huang, Teng; Jiang, Shuai; Huang, Wei

    2015-04-14

    Oxalic acid is believed to play an important role in the formation and growth of atmospheric organic aerosols. However, as a common organic acid, the understanding of the larger clusters formed by gas phase oxalic acid with multiple ammonia molecules is incomplete. In this work, the structural characteristics and thermodynamics of oxalic acid clusters with up to six ammonia molecules have been investigated at the PW91PW91/6-311++G(3df,3pd) level of theory. We found that oxalic acid forms relatively stable clusters with ammonia molecules, and that ionization events play a key role. The analyses of the thermodynamics and atmospheric relevance indicate that the heterodimer (H2C2O4)(NH3) shows an obvious relative concentration in the atmosphere, and thus likely participates in new particle formation. However, with increasing number of ammonia molecules, the concentration of clusters decreases gradually. Additionally, clusters of oxalic acid with ammonia molecules are predicted to form favorably in low temperature conditions and show high Rayleigh scattering intensities.

  11. Interaction of Gas Phase Oxalic Acid with Ammonia and its Atmospheric Implications

    SciTech Connect

    Peng, Xiu-Qiu; Liu, Yi-Rong; Huang, Teng; Jiang, Shuai; Huang, Wei

    2015-04-14

    Oxalic acid is believed to play an important role in the formation and growth of atmospheric organic aerosols. However, as a common organic acid, the understanding of the larger clusters formed by gas phase oxalic acid with multiple ammonia molecules is incomplete. In this work, the structural characteristics and thermodynamics of oxalic acid clusters with up to six ammonia molecules have been investigated at the PW91PW91/6-311++G(3df,3pd) level of theory. We found that oxalic acid forms relatively stable clusters with ammonia molecules, and that ionization events play a key role. The analyses of the thermodynamics and atmospheric relevance indicate that the heterodimer (H2C2O4)(NH3) shows an obvious relative concentration in the atmosphere, and thus likely participates in new particle formation. However, with increasing number of ammonia molecules, the concentration of clusters decreases gradually. Additionally, clusters of oxalic acid with ammonia molecules are predicted to form favorably in low temperature conditions and show high Rayleigh scattering intensities.

  12. Fungal production of citric and oxalic acid: importance in metal speciation, physiology and biogeochemical processes.

    PubMed

    Gadd, G M

    1999-01-01

    The production of organic acids by fungi has profound implications for metal speciation, physiology and biogeochemical cycles. Biosynthesis of oxalic acid from glucose occurs by hydrolysis of oxaloacetate to oxalate and acetate catalysed by cytosolic oxaloacetase, whereas on citric acid, oxalate production occurs by means of glyoxylate oxidation. Citric acid is an intermediate in the tricarboxylic acid cycle, with metals greatly influencing biosynthesis: growth limiting concentrations of Mn, Fe and Zn are important for high yields. The metal-complexing properties of these organic acids assist both essential metal and anionic (e.g. phosphate) nutrition of fungi, other microbes and plants, and determine metal speciation and mobility in the environment, including transfer between terrestrial and aquatic habitats, biocorrosion and weathering. Metal solubilization processes are also of potential for metal recovery and reclamation from contaminated solid wastes, soils and low-grade ores. Such 'heterotrophic leaching' can occur by several mechanisms but organic acids occupy a central position in the overall process, supplying both protons and a metal-complexing organic acid anion. Most simple metal oxalates [except those of alkali metals, Fe(III) and Al] are sparingly soluble and precipitate as crystalline or amorphous solids. Calcium oxalate is the most important manifestation of this in the environment and, in a variety of crystalline structures, is ubiquitously associated with free-living, plant symbiotic and pathogenic fungi. The main forms are the monohydrate (whewellite) and the dihydrate (weddelite) and their formation is of significance in biomineralization, since they affect nutritional heterogeneity in soil, especially Ca, P, K and Al cycling. The formation of insoluble toxic metal oxalates, e.g. of Cu, may confer tolerance and ensure survival in contaminated environments. In semi-arid environments, calcium oxalate formation is important in the formation and

  13. The effect of oxalic and itaconic acids on threo-Ds-isocitric acid production from rapeseed oil by Yarrowia lipolytica.

    PubMed

    Kamzolova, Svetlana V; Allayarov, Ramil K; Lunina, Julia N; Morgunov, Igor G

    2016-04-01

    The effect of oxalic and itaconic acids, the inhibitors of the isocitrate lyase, on the production of isocitric acid by the wild strain Yarrowia lipolytica VKM Y-2373 grown in the medium containing rapeseed oil was studied. In the presence of oxalic and itaconic acids, strain Y. lipolytica accumulated in the medium isocitric acid (70.0 and 82.7 g/L, respectively) and citric acid (23.0 and 18.4 g/L, respectively). In control experiment, when the inhibitors were not added to the medium, the strain accumulated isocitric and citric acids at concentrations of 62.0 and 28.0 g/L, respectively. Thus, the use of the oxalic and itaconic acids as additives to the medium is a simple and convenient method of isocitric acid production with a minimum content of citric acid.

  14. Reduction of carbadox mediated by reaction of Mn(III) with oxalic acid.

    PubMed

    Chen, Wan-Ru; Liu, Cun; Boyd, Stephen A; Teppen, Brian J; Li, Hui

    2013-02-05

    Manganese(III) geocomponents are commonly found in the soil environment, yet their roles in many biogeochemical processes remain unknown. In this study, we demonstrated that Mn(III) generated from the reaction of MnO(2) and oxalic acid caused rapid and extensive decompositions of a quinoxaline-di-N-oxide antibiotics, viz carbadox. The reaction occurred primarily at the quinoxaline-di-N-oxide moiety resulting in the removal of one -O from N1-oxide and formation of desoxycarbadox. The reaction rate was accelerated by increasing amounts of Mn(III), carbadox and oxalate. The critical step in the overall reaction was the formation of a quinoxaline-di-N-oxide/Mn(III)/oxalate ternary complex in which Mn(III) functioned as the central complexing cation and electron conduit in which the arrangement of ligands facilitated electron transfer from oxalate to carbadox. In the complex, the C-C bond in oxalate was cleaved to create CO(2)(-•) radicals, followed by electron transfer to carbadox through the Mn(III) center. This proposed reaction mechanism is supported by the reaction products formed, reaction kinetics, and quantum mechanical calculations. The results obtained from this study suggest that naturally occurring Mn(III)-oxalic acid complexes could reductively decompose certain organic compounds in the environment such as the antibiotic quinoxaline-di-N-oxide.

  15. Tungsten carbide nanotubes supported platinum nanoparticles as a potential sensing platform for oxalic acid.

    PubMed

    Maiyalagan, Thandavarayan; Kannan, Palanisamy; Jönsson-Niedziolka, Martin; Niedziolka-Jönsson, Joanna

    2014-08-05

    Supported tungsten carbide is an efficient and vital nanomaterial for the development of high-performance, sensitive, and selective electrochemical sensors. In this work, tungsten carbide with tube-like nanostructures (WC NTs) supported platinum nanoparticles (PtNPs) are synthesized and explored as an efficient catalyst toward electrochemical oxidation of oxalic acid for the first the time. The WC NTs supported PtNPs modified glassy carbon (GC) electrode is highly sensitive toward the electrochemical oxidation of oxalic acid. A large decrease in the oxidation overpotential (220 mV) and significant enhancement in the peak current compared to unmodified and Pt/C modified GC electrodes have been observed without using any redox mediator. Moreover, WC NTs supported PtNPs modified electrode possessed wide linear concentration ranges from 0 to 125 nM and a higher sensitivity toward the oxidation of oxalic acid (80 nA/nM) achieved by the amperometry method. The present modified electrode showed an experimentally determined lowest detection limit (LOD) of 12 nM (S/N = 3). Further, WC NTs supported PtNPs electrode can be demonstrated to have an excellent selectivity toward the detection of oxalic acid in the presence of a 200-fold excess of major important interferents. The practical application of WC NTs supported PtNPs has also been demonstrated in the detection of oxalic acid in tomato fruit sample, by differential pulse voltammetry under optimized conditions.

  16. Influence of Amitraz and Oxalic Acid on the Cuticle Proteolytic System of Apis mellifera L. Workers

    PubMed Central

    Strachecka, Aneta; Paleolog, Jerzy; Olszewski, Krzysztof; Borsuk, Grzegorz

    2012-01-01

    This work verifies that amitraz and oxalic acid treatment affect honeybee cuticle proteolytic enzymes (CPE). Three bee groups were monitored: oxalic acid treatment, amitraz treatment, control. Electrophoresis of hydrophilic and hydrophobic CPE was performed. Protease and protease inhibitor activities (in vitro) and antifungal/antibacterial efficiencies (in vivo), were analyzed. Amitraz and oxalic acid treatment reduced hydrophobic, but did not affect hydrophilic, protein concentrations and reduced both hydrophilic and hydrophobic body surface asparagine and serine protease activities in relation to most substrates and independently of pH. The activities of natural cuticle inhibitors of acidic, neutral, and alkaline proteases were suppressed as a result of the treatments, corresponding with reduced antifungal and antibacterial activity. Electrophoretic patterns of low-, medium-, and high-molecular-weight proteases and protease inhibitors were also affected by the treatments. PMID:26466630

  17. Iron dissolution of dust source materials during simulated acidic processing: the effect of sulfuric, acetic, and oxalic acids.

    PubMed

    Chen, Haihan; Grassian, Vicki H

    2013-09-17

    Atmospheric organic acids potentially display different capacities in iron (Fe) mobilization from atmospheric dust compared with inorganic acids, but few measurements have been made on this comparison. We report here a laboratory investigation of Fe mobilization of coal fly ash, a representative Fe-containing anthropogenic aerosol, and Arizona test dust, a reference source material for mineral dust, in pH 2 sulfuric acid, acetic acid, and oxalic acid, respectively. The effects of pH and solar radiation on Fe dissolution have also been explored. The relative capacities of these three acids in Fe dissolution are in the order of oxalic acid > sulfuric acid > acetic acid. Oxalate forms mononuclear bidentate ligand with surface Fe and promotes Fe dissolution to the greatest extent. Photolysis of Fe-oxalate complexes further enhances Fe dissolution with the concomitant degradation of oxalate. These results suggest that ligand-promoted dissolution of Fe may play a more significant role in mobilizing Fe from atmospheric dust compared with proton-assisted processing. The role of atmospheric organic acids should be taken into account in global-biogeochemical modeling to better access dissolved atmospheric Fe deposition flux at the ocean surface.

  18. On the factors governing the abundance of oxalic acid in tropospheric aerosol particles

    NASA Astrophysics Data System (ADS)

    van Pinxteren, D.; Neusuess, C.; Brüggemann, E.; Gnauk, T.; Müller, K.; Herrmann, H.

    2010-12-01

    Oxalic acid is frequently observed as one of the most abundant single organic compounds in tropospheric particles. Its sources are commonly believed to be of secondary nature. In state-of-the-art multiphase chemistry models, different pathways exist, which can lead to oxalic acid as final product. Anthropogenic hydrocarbon emissions can be photochemically degraded to glyoxal and methyglyoxal, which - after partitioning into deliquescent particles or cloud droplets - are further oxidized via glyoxylic acid to oxalic acid [Herrmann et al., 2005]. A biogenic oxidation pathway starts with isoprene or monoterpene emissions and leads to glycolaldehyde and methylglyoxal via methacrolein and methylvinylketone, followed by aqueous phase oxalic acid formation [Lim et al., 2005]. As suggested by Warneck, 2003, a marine pathway might exist, starting from marine ethene emissions and leading via glycolaldehyde to oxalic acid. The aim of this study was to elucidate from field measurements the importance of each of these pathways. To this aim, oxalic acid concentrations from 144 size-resolved particle samples (5-stage Berner impactor) from different continental and coastal European sampling sites were statistically analyzed using principal component analysis (PCA). Hourly back trajectories were calculated for each sampling interval using the HYSPLIT model [Draxler and Rolph, 2003] and combined in a novel way with global land cover data to yield “residence times” of the sampled air masses above urban, agricultural, forested, and oceanic areas. These residence times served as quantitative proxies for different emission regimes (anthropogenic, biogenic, marine) in the statistical analysis. Additionally, meteorological parameters such as sunflux along the trajectories or mixing layer depth at the sampling site were retrieved from the HYSPLIT output. PCA of the continental dataset retrieved two factors that were connected to the oxalic acid concentrations. A first one showed high

  19. A role for oxalic acid generation in ozone-induced signallization in Arabidopis cells.

    PubMed

    Tran, Daniel; Kadono, Takashi; Molas, Maria Lia; Errakhi, Rafik; Briand, Joël; Biligui, Bernadette; Kawano, Tomonori; Bouteau, François

    2013-03-01

    Ozone (O(3) ) is an air pollutant with an impact increasingly important in our industrialized world. It affects human health and productivity in various crops. We provide the evidences that treatment of Arabidopsis thaliana with O(3) results in ascorbate-derived oxalic acid production. Using cultured cells of A. thaliana as a model, here we further showed that oxalic acid induces activation of anion channels that trigger depolarization of the cell, increase in cytosolic Ca(2+) concentration, generation of reactive oxygen species and cell death. We confirmed that O(3) reacts with ascorbate in the culture, thus resulting in production of oxalic acid and this could be part of the O(3) -induced signalling pathways that trigger programmed cell death.

  20. THORIUM OXALATE-URANYL ACETATE COUPLED PROCEDURE FOR THE SEPARATION OF RADIOACTIVE MATERIALS

    DOEpatents

    Gofman, J.W.

    1959-08-11

    The recovery of fission products from neutronirradiated uranium is described. The neutron-irradiated uranium is dissolved in acid and thorium oxalate is precipitated in ihe solution formed, whereby the fission products are carried on the thorium oxalate. The separated thorium oxalate precipitate is then dissolved in an aqueous oxalate solution and the solution formed is acidified, limiting ihe excess acidity to a maximum of 2 N, whereby thorium oxalate precipitates and carries lanthanum-rareearth- and alkaline-earth-metal fission products while the zirconium-fission-product remains in solution. This precipitate, too, is dissolved in an aqaeous oxalate solution at elevated temperature, and lanthanum-rare-earth ions are added to the solution whereby lanthanum-rare-earth oxalate forms and the lanthanum-rare-earth-type and alkalineearth-metal-type fission products are carried on the oxalate. The precipitate is separated from the solution.

  1. Catalytic ozonation of oxalic acid using carbon nanofibres on macrostructured supports.

    PubMed

    Restivo, J; Órfão, J J M; Pereira, M F R; Vanhaecke, E; Rönning, M; Iouranova, T; Kiwi-Minsker, L; Armenise, S; Garcia-Bordejé, E

    2012-01-01

    Carbon nanofibres (CNFs) were grown on different macrostructured supports such as cordierite monoliths, carbon felts and sintered metal fibres. The resulting composites exhibited excellent resistance to attrition/corrosion and its porosity is mainly due to mesoporous structures. The CNF/structured materials were tested in the ozonation of oxalic acid in a conventional semi-batch reactor after being crushed to powder form, and in a newly designed reactor that may operate in semi-batch or continuous operation. The CNFs supported on the different structured materials exhibited high catalytic activity in the mineralization of oxalic acid.

  2. Heterogeneous photochemistry of oxalic acid on Mauritanian sand and Icelandic volcanic ash.

    PubMed

    Styler, Sarah A; Donaldson, D J

    2012-08-21

    Teragram quantities of crustal and volcanic aerosol are released into the atmosphere on an annual basis. Although these substrates contain photoactive metal oxides, little is known about the role that they may play in catalyzing the heterogeneous phototransformation of semivolatile organic species. In the present study, we have investigated oxalic acid photochemistry at the surface of Fe(2)O(3), TiO(2), Mauritanian sand, and Icelandic volcanic ash in the presence and absence of oxygen using a photochemical Knudsen cell reactor. Illumination of all sample types resulted in the production of gas-phase CO(2). In the case of Mauritanian sand, the production of gas-phase CO(2) scaled with the loss of surface oxalic acid. In the absence of oxygen, the production of CO(2) by the sand and ash films scaled with the absorption spectrum of iron oxalate, which suggests that the reaction is at least in part iron-mediated. The presence of oxygen suppressed CO(2) production at the Fe(2)O(3) surface, enhanced CO(2) production at the Mauritanian sand surface, and did not have a net effect upon CO(2) production at the Icelandic ash surface. These different oxygen dependencies imply that oxalic acid photochemistry at the authentic surfaces under study was not solely iron-mediated. Experiments at the TiO(2) surface, which showed enhanced CO(2) production from oxalic acid in the presence of oxygen, suggest that Ti-mediated photochemistry played an important role. In summary, these results provide evidence that solid-phase aerosol photochemistry may influence the atmospheric lifetime of oxalic acid in arid regions, where its removal via wet deposition is insignificant.

  3. Oxalic acid alleviates chilling injury in peach fruit by regulating energy metabolism and fatty acid contents.

    PubMed

    Jin, Peng; Zhu, Hong; Wang, Lei; Shan, Timin; Zheng, Yonghua

    2014-10-15

    The effects of postharvest oxalic acid (OA) treatment on chilling injury, energy metabolism and membrane fatty acid content in 'Baifeng' peach fruit stored at 0°C were investigated. Internal browning was significantly reduced by OA treatment in peaches. OA treatment markedly inhibited the increase of ion leakage and the accumulation of malondialdehyde. Meanwhile, OA significantly increased the contents of adenosine triphosphate and energy charge in peach fruit. Enzyme activities of energy metabolism including H(+)-adenosine triphosphatase, Ca(2+)-adenosine triphosphatase, succinic dehydrogenase and cytochrome C oxidase were markedly enhanced by OA treatment. The ratio of unsaturated/saturated fatty acid in OA-treated fruit was significantly higher than that in control fruit. These results suggest that the alleviation in chilling injury by OA may be due to enhanced enzyme activities related to energy metabolism and higher levels of energy status and unsaturated/saturated fatty acid ratio.

  4. Effects of pyruvate salts, pyruvic acid, and bicarbonate salts in preventing experimental oxalate urolithiasis in rats.

    PubMed

    Ogawa, Y; Yamaguchi, K; Tanaka, T; Morozumi, M

    1986-05-01

    Sodium pyruvate, potassium pyruvate, pyruvic acid, sodium bicarbonate and potassium bicarbonate were added to a calcium-oxalate lithogenic diet (a glycolic-acid diet) in order to determine their effects in preventing lithogenicity. Male Wistar-strain rats who had been fed the glycolic-acid diet developed marked urinary calculi within four weeks. Rats in the sodium and potassium pyruvate groups had, however, almost no stones in the urinary system. Rats in the bicarbonate and pyruvic-acid groups showed slightly less effect than those in the pyruvate groups. Urinary oxalate excretion was high in all the groups during the experiment. The urinary oxalate concentration was relatively higher in the sodium-pyruvate group, and significantly higher in the potassium-pyruvate group, than in the glycolic-acid group. Urinary citrate excretion was high both in the pyruvate and bicarbonate groups; the urinary citrate concentration was, however, significantly higher in the pyruvate groups than in the bicarbonate groups at the fourth experimental week. The urinary calcium and magnesium concentrations were irrelevant to the diets administered. Therefore, it can be concluded that pyruvate salts inhibit urinary calculi formation, not by decreasing oxalate synthesis, but by increasing the urinary citrate concentration; bicarbonate salts work in the same manner, but a little less effectively.

  5. Reuse of washing effluent containing oxalic acid by a combined precipitation-acidification process.

    PubMed

    Lim, Mihee; Kim, Myoung-Jin

    2013-01-01

    This study aims at evaluating the reuse feasibility of effluent produced by the soil washing of mine tailings with oxalic acid. Alkaline chemicals such as NaOH, Ca(OH)(2), and Na(2)CO(3) are used for the precipitation of arsenic and heavy metals in the effluent containing oxalic acid. All of the target contaminants are removed with very high efficiency (up to 100%) at high pH. The precipitation using NaOH at pH 9 is determined to be the most cost-effective method for the removal of arsenic as well as heavy metals in the effluent. The effluent decontaminated by NaOH is consecutively reused for the soil washing of raw mine tailings, resulting in considerable efficiency. Furthermore, even more arsenic and heavy metals are extracted from raw mine tailings by acidifying the decontaminated effluent under the alkaline condition, compared with direct reuse of the decontaminated effluent. Here, the oxalic acid, which is a weak complex-forming ligand as well as a weak acid, has noticeable effects on both soil washing and effluent treatment by precipitation. It extracts efficiently the contaminants from the mine tailings without adverse change of soil and also makes possible the precipitation of the contaminants in the effluent unlike strong chelating reagent. Reuse of the washing effluent containing oxalic acid would make the existing soil washing process more environment-friendly and cost-effective.

  6. Oxalic acid: a prospective tool for reducing Varroa mite populations in package bees.

    PubMed

    Aliano, Nicholas P; Ellis, Marion D

    2009-08-01

    Numerous studies have investigated using oxalic acid (OA) to control Varroa mites in honey bee colonies. In contrast, techniques for treating package bees with OA have not been investigated. The goal of this study was to develop a protocol for using OA to reduce mite infestation in package bees. We made 97 mini packages of Varroa-infested adult bees. Each package contained 1,613 +/- 18 bees and 92 +/- 3 mites, and represented an experimental unit. We prepared a 2.8% solution of OA by mixing 35 g OA with 1 l of sugar water (sugar:water = 1:1; w:w). Eight treatments were assigned to the packages based on previous laboratory bioassays that characterized the acute contact toxicity of OA to mites and bees. We administered the treatments by spraying the OA solution directly on the bees through the mesh screen cage using a pressurized air brush and quantified mite and bee mortality over a 10-day period. Our results support applying an optimum volume of 3.0 ml of a 2.8% OA solution per 1,000 bees to packages for effective mite control with minimal adult bee mortality. The outcome of our research provides beekeepers and package bee shippers guidance for using OA to reduce mite populations in package bees.

  7. YfdW and YfdU are required for oxalate-induced acid tolerance in Escherichia coli K-12.

    PubMed

    Fontenot, Elise M; Ezelle, Karen E; Gabreski, Lauren N; Giglio, Eleanor R; McAfee, John M; Mills, Alexandria C; Qureshi, Maryam N; Salmon, Kristin M; Toyota, Cory G

    2013-04-01

    Escherichia coli has several mechanisms for surviving low-pH stress. We report that oxalic acid, a small-chain organic acid (SCOA), induces a moderate acid tolerance response (ATR) in two ways. Adaptation of E. coli K-12 at pH 5.5 with 50 mM oxalate and inclusion of 25 mM oxalate in pH 3.0 minimal challenge medium separately conferred protection, with 67% ± 7% and 87% ± 17% survival after 2 h, respectively. The combination of oxalate adaptation and oxalate supplementation in the challenge medium resulted in increased survival over adaptation or oxalate in the challenge medium alone. The enzymes YfdW, a formyl coenzyme A (CoA) transferase, and YfdU, an oxalyl-CoA decarboxylase, are required for the adaptation effect but not during challenge. Unlike other SCOAs, this oxalate ATR is not a part of the RpoS regulon but appears to be linked to the signal protein GadE. We theorize that this oxalate ATR could enhance the pathogenesis of virulent E. coli consumed with oxalate-containing foods like spinach.

  8. YfdW and YfdU Are Required for Oxalate-Induced Acid Tolerance in Escherichia coli K-12

    PubMed Central

    Fontenot, Elise M.; Ezelle, Karen E.; Gabreski, Lauren N.; Giglio, Eleanor R.; McAfee, John M.; Mills, Alexandria C.; Qureshi, Maryam N.; Salmon, Kristin M.

    2013-01-01

    Escherichia coli has several mechanisms for surviving low-pH stress. We report that oxalic acid, a small-chain organic acid (SCOA), induces a moderate acid tolerance response (ATR) in two ways. Adaptation of E. coli K-12 at pH 5.5 with 50 mM oxalate and inclusion of 25 mM oxalate in pH 3.0 minimal challenge medium separately conferred protection, with 67% ± 7% and 87% ± 17% survival after 2 h, respectively. The combination of oxalate adaptation and oxalate supplementation in the challenge medium resulted in increased survival over adaptation or oxalate in the challenge medium alone. The enzymes YfdW, a formyl coenzyme A (CoA) transferase, and YfdU, an oxalyl-CoA decarboxylase, are required for the adaptation effect but not during challenge. Unlike other SCOAs, this oxalate ATR is not a part of the RpoS regulon but appears to be linked to the signal protein GadE. We theorize that this oxalate ATR could enhance the pathogenesis of virulent E. coli consumed with oxalate-containing foods like spinach. PMID:23335415

  9. Simultaneous saccharification and ethanol fermentation of oxalic acid pretreated corncob assessed with response surface methodology.

    PubMed

    Lee, Jae-Won; Rodrigues, Rita C L B; Jeffries, Thomas W

    2009-12-01

    Response surface methodology was used to evaluate optimal time, temperature and oxalic acid concentration for simultaneous saccharification and fermentation (SSF) of corncob particles by Pichia stipitis CBS 6054. Fifteen different conditions for pretreatment were examined in a 2(3) full factorial design with six axial points. Temperatures ranged from 132 to 180 degrees C, time from 10 to 90 min and oxalic acid loadings from 0.01 to 0.038 g/g solids. Separate maxima were found for enzymatic saccharification and hemicellulose fermentation, respectively, with the condition for maximum saccharification being significantly more severe. Ethanol production was affected by reaction temperature more than by oxalic acid and reaction time over the ranges examined. The effect of reaction temperature was significant at a 95% confidence level in its effect on ethanol production. Oxalic acid and reaction time were statistically significant at the 90% level. The highest ethanol concentration (20 g/l) was obtained after 48 h with an ethanol volumetric production rate of 0.42 g ethanol l(-1) h(-1). The ethanol yield after SSF with P. stipitis was significantly higher than predicted by sequential saccharification and fermentation of substrate pretreated under the same condition. This was attributed to the secretion of beta-glucosidase by P. stipitis. During SSF, free extracellular beta-glucosidase activity was 1.30 pNPG U/g with P. stipitis, while saccharification without the yeast was 0.66 pNPG U/g.

  10. Response to oxalic acid as a resistance assay for Sclerotinia minor in peanut

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Response to oxalic acid was evaluated as a potential assay for screening peanut breeding lines for resistance to Sclerotinia blight caused by Sclerotinia minor. Detached stems of seven Spanish- and six runner-type peanut cultivars and advanced breeding lines, varying in resistance to Sclerotinia bl...

  11. The role of nanoparticulate agglomerates in TiO2 photocatalysis: degradation of oxalic acid

    NASA Astrophysics Data System (ADS)

    Ivanova, Irina; Mendive, Cecilia B.; Bahnemann, Detlef

    2016-07-01

    The simultaneous bimodal study of the photocatalytic oxalic acid degradation by aqueous TiO2 suspensions revealed that particular systems possess the capacity to protect a certain amount of oxalic acid from oxidation, thus hindering, to some extent, the photocatalytic reaction. While measurements of the oxalic acid concentration in the bulk liquid phase indicated full photocatalytic degradation; in situ pH-stat measurements allowed the quantification of the amount of oxalic acid remaining in the part of the nanoparticulate agglomerates where light could apparently not access. An explanation for this phenomenon takes into account the possibility of the formation of TiO2 agglomerates in which these molecules are hidden from the effect of the light, thus being protected from photocatalytic degradation. Studies of different TiO2 materials with different particle sizes allowed a deeper exploration of this phenomenon. In addition, because this property of encapsulating pollutant molecules by photocatalytic systems is found to be a reversible phenomenon, P25 appears to be more convenient and advantageous as compared to the use of large surface area photocatalysts.

  12. Efficacy of oxalic acid to reduce Salmonella spp. at various states of poultry processing

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The microbiological safety of fresh eviscerated poultry has continued to be a major concern of the consumer and the poultry industry due to the frequent foodborne illnesses caused by Salmonella spp. Oxalic acid (OA) was evaluated as an antimicrobial treatment at equivalent dip, scalding, and chillin...

  13. Morphological control of calcium oxalate particles in the presence of poly-(styrene-alt-maleic acid)

    NASA Astrophysics Data System (ADS)

    Yu, Jiaguo; Tang, Hua; Cheng, Bei; Zhao, Xiujian

    2004-10-01

    Calcium oxalate (CaOx) particles exhibiting different shapes and phase structures were fabricated by a simple precipitation reaction of sodium oxalate with calcium chloride in the absence and presence of poly-(styrene-alt-maleic acid) (PSMA) as a crystal modifier at room temperature. The as-obtained products were characterized with scanning electron microscopy (SEM) and X-ray diffraction (XRD). The effects of reaction conditions including pH, [Ca2+]/[C2O42-] ratio and concentration of PSMA and CaC2O4 on the crystal forms and morphologies of the as-obtained calcium oxalate were investigated. The results show that various crystal morphologies of calcium oxalate, such as parallelograms, plates, spheres, bipyramids etc. can be obtained depending on the experimental conditions. Higher polymer concentration favors formation of the metastable calcium oxalate dihydrate (COD) crystals. Lower pH is beneficial to the formation of plate-like CaOx crystals. Especially, the monodispersed parallelogram-like CaOx crystals can be produced by PSMA as an additive at pH 2. PSMA may act as a good inhibitor for urolithiasis since it induces the formation of COD and reduces the particle size of CaOx. This research may provide new insight into the morphological control of CaOx particles and the prevention of urolithiasis.

  14. Spectra investigation on surface characteristics of graphene oxide nanosheets treated with tartaric, malic and oxalic acids

    NASA Astrophysics Data System (ADS)

    Teng, Xiyao; Yan, Manqing; Bi, Hong

    2014-01-01

    The surface characteristics of graphene oxide nanosheets (GO) treated respectively with tartaric acid, malic acid and oxalic acid, have been investigated by mainly using optical spectroscopic methods including Fourier transform infrared spectroscopy (FT-IR), Ultraviolet-visible (UV-Vis) absorption and Raman spectroscopy. Additionally, the electrochemical property of the products has also been studied. The data revealed that oxygen-containing groups such as sbnd OH, sbnd COOH and sbnd Cdbnd O on the GO surface have been almost removed and thus reduced graphene oxide nanosheets (RGN) were obtained. Interestingly, the number of sp2 domains of RGN increases as treated by tartaric acid < malic acid < oxalic acid whereas the steric hindrance (SH) decreases and the ionization constant (IC) differs among these three acids. Furthermore, the specific capacitances (Cs) of GO have been greatly promoted from 2.4 F g-1 to 100.8, 112.4, and 147 F g-1 after treated with tartaric, malic and oxalic acids, respectively. This finding agrees well with the spectra result of the tendency of surface conjugated degree alteration. We claim that the difference in both SH and IC among these acids is the main reason for the diverse surface characteristics as well as the improved Cs of the RGN.

  15. Spectra investigation on surface characteristics of graphene oxide nanosheets treated with tartaric, malic and oxalic acids.

    PubMed

    Teng, Xiyao; Yan, Manqing; Bi, Hong

    2014-01-24

    The surface characteristics of graphene oxide nanosheets (GO) treated respectively with tartaric acid, malic acid and oxalic acid, have been investigated by mainly using optical spectroscopic methods including Fourier transform infrared spectroscopy (FT-IR), Ultraviolet-visible (UV-Vis) absorption and Raman spectroscopy. Additionally, the electrochemical property of the products has also been studied. The data revealed that oxygen-containing groups such as OH, COOH and CO on the GO surface have been almost removed and thus reduced graphene oxide nanosheets (RGN) were obtained. Interestingly, the number of sp(2) domains of RGN increases as treated by tartaric acidacid acid whereas the steric hindrance (SH) decreases and the ionization constant (IC) differs among these three acids. Furthermore, the specific capacitances (Cs) of GO have been greatly promoted from 2.4 F g(-1) to 100.8, 112.4, and 147 F g(-1) after treated with tartaric, malic and oxalic acids, respectively. This finding agrees well with the spectra result of the tendency of surface conjugated degree alteration. We claim that the difference in both SH and IC among these acids is the main reason for the diverse surface characteristics as well as the improved Cs of the RGN.

  16. In Situ Oxalic Acid Injection to Accelerate Arsenic Remediation at a Superfund Site in New Jersey.

    PubMed

    Wovkulich, Karen; Stute, Martin; Mailloux, Brian J; Keimowitz, Alison R; Ross, James; Bostick, Benjamin; Sun, Jing; Chillrud, Steven N

    2014-09-25

    Arsenic is a prevalent contaminant at a large number of US Superfund sites; establishing techniques that accelerate As remediation could benefit many sites. Hundreds of tons of As were released into the environment by the Vineland Chemical Co. in southern New Jersey during its manufacturing lifetime (1949-1994), resulting in extensive contamination of surface and subsurface soils and sediments, groundwater, and the downstream watershed. Despite substantial intervention at this Superfund site, sufficient aquifer cleanup could require many decades if based on traditional pump and treat technologies only. Laboratory column experiments have suggested that oxalic acid addition to contaminated aquifer solids could promote significant As release from the solid phase. To evaluate the potential of chemical additions to increase As release in situ and boost treatment efficiency, a forced gradient pilot scale study was conducted on the Vineland site. During spring/summer 2009, oxalic acid and bromide tracer were injected into a small portion (~50 m(2)) of the site for 3 months. Groundwater samples indicate that introduction of oxalic acid led to increased As release. Between 2.9 and 3.6 kg of As were removed from the sampled wells as a result of the oxalic acid treatment during the 3-month injection. A comparison of As concentrations on sediment cores collected before and after treatment and analyzed using X-ray fluorescence spectroscopy suggested reduction in As concentrations of ~36% (median difference) to 48% (mean difference). While further study is necessary, the addition of oxalic acid shows potential for accelerating treatment of a highly contaminated site and decreasing the As remediation time-scale.

  17. Immobilization of lead in anthropogenic contaminated soils using phosphates with/without oxalic acid.

    PubMed

    Su, Xiaojuan; Zhu, Jun; Fu, Qingling; Zuo, Jichao; Liu, Yonghong; Hu, Hongqing

    2015-02-01

    Understanding the effects of oxalic acid (OA) on the immobilization of Pb(II) in contaminated soils by phosphate materials, has considerable benefits for risk assessment and remediation strategies for the soil. A series of phosphate amendments with/without oxalic acid were applied to two anthropogenic contaminated soils. We investigated the immobilization of Pb(II) by KH2PO4, phosphate rock (PR), activated phosphate rock (APR) and synthetic hydroxyapatite (HAP) at different phosphate:Pb (P:Pb) molar ratios (0, 0.6, 2.0 and 4.0) in the presence/absence of 50 mmol oxalic acid/kg soil, respectively. The effects of treatments were evaluated using single extraction with deionized water or CaCl2, Community Bureau of Reference (BCR) sequential extraction and toxicity characteristic leaching procedure (TCLP) methods. Our results showed that the concentration of water extractable, exchangeable and TCLP-Pb all decreased with incubation time. The concentration of water-extractable Pb after 120 days was reduced by 100% when soils were amended with APR, HAP and HAP+OA, and the TCLP-Pb was <5 mg/L for the red soil at P:Pb molar ratio 4.0. Water-soluble Pb could not be detected and the TCLP-Pb was <5 mg/L at all treatments applied to the yellow-brown soil. BCR results indicated that APR was most effective, although a slight enhancement of water-soluble phosphate was detected at the P:Pb molar ratio 4.0 at the beginning of incubation. Oxalic acid activated phosphates, and so mixing insoluble phosphates with oxalic acid may be a useful strategy to improve their effectiveness in reducing Pb bioavailability.

  18. Correlation between the production of exopolysaccharides and oxalic acid secretion by Ganoderma applanatum and Tyromyces palustris.

    PubMed

    Osińska-Jaroszuk, Monika; Wlizło, Kamila; Szałapata, Katarzyna; Jarosz-Wilkołazka, Anna

    2014-12-01

    The secretion of exopolysaccharides and oxalic acid in cultures of a white rot Ganoderma applanatum strain and a brown rot Tyromyces palustris strain were tested in terms of culture time, pH range, and temperature. The high yield of exopolysaccharides (EPS) required a moderate temperature of 28 °C for G. applanatum and 20 °C for T. palustris. G. applanatum and T. palustris accumulated more EPS when the concentration of the carbon source (maltose for G. applanatum and fructose for T. palustris) was 30 g/L. The results indicate that the production of oxalic acid by G. applanatum is correlated with the initial pH value of the culture medium and the concentration of oxalic acid increased to 1.66 ± 0.2 mM at the initial pH of 6.5 during the fungal growth. During the growth of T. palustris, the reduction of the initial pH value of the growing medium lowered the oxalic acid concentration from 7.7 ± 0.6 mM at pH 6.0 to 1.99 ± 0.2 mM at pH 3.5. T. palustris accumulated considerably more oxalic acid than G. applanatum and its presence did not affect significantly the production of exopolysaccharides. We also observed that the maximum amounts of exopolysaccharides secreted during cultivation of G. applanatum and T. palustris were 45.8 ± 1.2 and 19.1 ± 1.2 g/L, respectively.

  19. In Situ Oxalic Acid Injection to Accelerate Arsenic Remediation at a Superfund Site in New Jersey

    PubMed Central

    Wovkulich, Karen; Stute, Martin; Mailloux, Brian J.; Keimowitz, Alison R.; Ross, James; Bostick, Benjamin; Sun, Jing; Chillrud, Steven N.

    2015-01-01

    Arsenic is a prevalent contaminant at a large number of US Superfund sites; establishing techniques that accelerate As remediation could benefit many sites. Hundreds of tons of As were released into the environment by the Vineland Chemical Co. in southern New Jersey during its manufacturing lifetime (1949–1994), resulting in extensive contamination of surface and subsurface soils and sediments, groundwater, and the downstream watershed. Despite substantial intervention at this Superfund site, sufficient aquifer cleanup could require many decades if based on traditional pump and treat technologies only. Laboratory column experiments have suggested that oxalic acid addition to contaminated aquifer solids could promote significant As release from the solid phase. To evaluate the potential of chemical additions to increase As release in situ and boost treatment efficiency, a forced gradient pilot scale study was conducted on the Vineland site. During spring/summer 2009, oxalic acid and bromide tracer were injected into a small portion (~50 m2) of the site for 3 months. Groundwater samples indicate that introduction of oxalic acid led to increased As release. Between 2.9 and 3.6 kg of As were removed from the sampled wells as a result of the oxalic acid treatment during the 3-month injection. A comparison of As concentrations on sediment cores collected before and after treatment and analyzed using X-ray fluorescence spectroscopy suggested reduction in As concentrations of ~36% (median difference) to 48% (mean difference). While further study is necessary, the addition of oxalic acid shows potential for accelerating treatment of a highly contaminated site and decreasing the As remediation time-scale. PMID:25598701

  20. Evaluation Of Sludge Heel Dissolution Efficiency With Oxalic Acid Cleaning At Savannah River Site

    SciTech Connect

    Sudduth, Christie; Vitali, Jason; Keefer, Mark

    2014-01-08

    The chemical cleaning process baseline strategy at the Savannah River Site was revised to improve efficiency during future execution of the process based on lessons learned during previous bulk oxalic acid cleaning activities and to account for operational constraints imposed by safety basis requirements. These improvements were also intended to transcend the difficulties that arise from waste removal in higher rheological yield stress sludge tanks. Tank 12 implemented this improved strategy and the bulk oxalic acid cleaning efforts concluded in July 2013. The Tank 12 radiological removal results were similar to previous bulk oxalic acid cleaning campaigns despite the fact that Tank 12 contained higher rheological yield stress sludge that would make removal more difficult than the sludge treated in previous cleaning campaigns. No appreciable oxalate precipitation occurred during the cleaning process in Tank 12 compared to previous campaigns, which aided in the net volume reduction of 75-80%. Overall, the controls established for Tank 12 provide a template for an improved cleaning process.

  1. Degradation of oxalic acid by the mycoparasite Coniothyrium minitans plays an important role in interacting with Sclerotinia sclerotiorum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Coniothyrium minitans is a mycoparasite of the phytopathogenic fungus Sclerotinia sclerotiorum. Sclerotinia sclerotiorum produces a virulence factor oxalic acid (OA) which is toxic to plants and also to C. minitans, and C. minitans detoxifies OA by degradation. In this study, two oxalate decarboxyla...

  2. Corrosion Testing of Carbon Steel in Oxalic Acid that Contains Dissolved Iron

    SciTech Connect

    Wiersma, Bruce J.; Mickalonis, John I.; Subramanian, Karthik H.

    2012-10-11

    Radioactive liquid waste has been stored in underground carbon steel tanks for nearly 60 years at the Savannah River Site. The site is currently in the process of removing the waste from these tanks in order to place it into vitrified, stable state for longer term storage. The last stage in the removal sequence is a chemical cleaning step that breaks up and dissolves metal oxide solids that cannot be easily pumped out of the tank. Oxalic acid (OA) will be used to chemically clean the tanks after waste retrieval is completed. The waste tanks at SRS were constructed from carbon steel materials and thus are vulnerable to corrosion in acidic media. In addition to structural impacts, the impact of corrosion on the hydrogen generated during the process must be assessed. Electrochemical and coupon immersion tests were used to investigate the corrosion mechanism at anticipated process conditions. The testing showed that the corrosion rates were dependent upon the reduction of the iron species that had dissolved in solution. Initial corrosion rates were elevated due to the reduction of the ferric species to ferrous species. At later times, as the ferric species depleted, the corrosion rate decreased. On the other hand, the hydrogen evolution reaction became more dominant.

  3. Dilute oxalic acid pretreatment for high total sugar recovery in pretreatment and subsequent enzymatic hydrolysis.

    PubMed

    Qing, Qing; Huang, Meizi; He, Yucai; Wang, Liqun; Zhang, Yue

    2015-12-01

    Oxalic acid was evaluated as an alternative reagent to mineral inorganic acid in pretreatment of corncob to achieve high xylose yield in addition to highly digestible solid residue. A quadratic polynomial model of xylose formation was developed for optimization of pretreatment process by the response surface methodology based on the impact factors of pretreatment temperature, reaction time, acid concentration, and solid-to-liquid ratio. The highest xylose yield was 94.3 % that was obtained under the pretreatment condition of 140 °C for 40 min with 0.5 wt% oxalic acid at a solid loading of 7.5 %. Under these conditions, the xylose yield results of verification experiments were very close to the model prediction, which indicated that the model was applicable. The solid residue generated under this condition also demonstrated a satisfactory enzymatic digestibility and fermentability.

  4. NIR spectroscopic properties of aqueous acids solutions.

    PubMed

    Omar, Ahmad Fairuz; Atan, Hanafi; Matjafri, Mohd Zubir

    2012-06-15

    Acid content is one of the important quality attributes in determining the maturity index of agricultural product, particularly fruits. Despite the fact that much research on the measurement of acidity in fruits through non-destructive spectroscopy analysis at NIR wavelengths between 700 to 1,000 nm has been conducted, the same response towards individual acids is not well known. This paper presents NIR spectroscopy analysis on aqueous citric, tartaric, malic and oxalic solutions through quantitative analysis by selecting a set of wavelengths that can best be used to measure the pH of the solutions. The aquaphotomics study of the acid solutions has generated R² above 0.9 for the measurement of all acids. The most important wavelengths for pH are located at 918-925 nm and 990-996 nm, while at 975 nm for water.

  5. Repression of oxalic acid-mediated mineral phosphate solubilization in rhizospheric isolates of Klebsiella pneumoniae by succinate.

    PubMed

    Rajput, Mahendrapal Singh; Naresh Kumar, G; Rajkumar, Shalini

    2013-02-01

    Two strains of Klebsiella (SM6 and SM11) were isolated from rhizospheric soil that solubilized mineral phosphate by secretion of oxalic acid from glucose. Activities of enzymes for periplasmic glucose oxidation (glucose dehydrogenase) and glyoxylate shunt (isocitrate lyase and glyoxylate oxidase) responsible for oxalic acid production were estimated. In presence of succinate, phosphate solubilization was completely inhibited, and the enzymes glucose dehydrogenase and glyoxylate oxidase were repressed. Significant activity of isocitrate lyase, the key enzyme for carbon flux through glyoxylate shunt and oxalic acid production during growth on glucose suggested that it could be inducible in nature, and its inhibition by succinate appeared to be similar to catabolite repression.

  6. Coadsorption of Cd(II) and oxalate ions at the TiO2/electrolyte solution interface.

    PubMed

    Janusz, W; Matysek, M

    2006-04-01

    The study of the adsorptions of cadmium and oxalate ions at the titania/electrolyte interface and the changes of the electrical double layer (edl) structure in this system are presented. The adsorption of cadmium or oxalate ions was calculated from an uptake of their concentration from the solution. The concentration of Cd(II) or oxalate ions in the solution was determined by radiotracer method. For labeling the solution 14C and 115Cd isotopes were used. Coadsorption of Cd(II) and oxalic ions was determined simultaneously. Besides, the main properties of the edl, i.e., surface charge density and zeta potential were determined by potentiometer titration and electrophoresis measurements, respectively. The adsorption of cadmium ions increases with pH increase and shifts with an increase of the initial concentration of Cd(II) ions towards higher pH values. The adsorption process causes an increase of negatively charged sites on anatase and a decrease of the zeta potential with an increase of initial concentration of these ions. The adsorption of oxalate anions at the titania/electrolyte interface proceeds through the exchange with hydroxyl groups. A decrease of pH produces an increase of adsorption of oxalate ions. The processes of anion adsorption lead to increase the number of the positively charged sites at the titania surface. However, specific adsorption of bidenate ligand as oxalate on one surface hydroxyl group may form inner sphere complexes on the metal oxide surface and may overcharge the compact part of the edl. The presence of oxalate ions in the system affects the adsorption of Cd(II) ions on TiO2, increasing the adsorption at low pH range and decreasing the adsorption at high pH range. Using adsorption as a function of pH data, some characteristic parameters of adsorption envelope were calculated.

  7. Enhanced bioethanol production from yellow poplar by deacetylation and oxalic acid pretreatment without detoxification.

    PubMed

    Kundu, Chandan; Lee, Hong-Joo; Lee, Jae-Won

    2015-02-01

    In order to produce ethanol from yellow poplar, deacetylation was performed using sodium hydroxide (NaOH). Optimal deacetylation conditions were determined by a response surface methodology. The highest acetic acid concentration obtained was 7.06 g/L when deacetylation was performed at 60 °C for 80 min with 0.8% NaOH. Acetic acid was recovered by electrodialysis from the deacetylated hydrolysate. The oxalic acid pretreatment of deacetylated biomass was carried out and the hydrolysate directly used for ethanol production without detoxification. Ethanol yields ranged from 0.34 to 0.47 g/g and the highest ethanol yield was obtained when pretreatment was carried out at 150 °C with 50 mM oxalic acid. The highest ethanol concentration obtained from pretreated biomass was 27.21 g/L at 170 °C, using a 50 mM of oxalic acid for the simultaneous saccharification and fermentation (SSF). Overall, 20.31 g of ethanol was obtained by hydrolysate and SSF from 100 g of deacetylated yellow poplar.

  8. Pre-storage application of oxalic acid alleviates chilling injury in mango fruit by modulating proline metabolism and energy status under chilling stress.

    PubMed

    Li, Peiyan; Zheng, Xiaolin; Liu, Yan; Zhu, Yuyan

    2014-01-01

    Effects of oxalic acid on chilling injury, proline metabolism and energy status in mango fruit were investigated after mango fruit (Mangifera indica L. cv. Zill) were dipped in 5mM oxalic acid solution for 10min at 25°C and then stored at low temperature (10±0.5°C) for 49days thereafter transferred to 25°C for 4days. Pre-storage application of oxalic acid apparently inhibited the development of chilling injury, notably elevated proline accumulation actually associated with increase in Δ(1)-pyrroline-5-carboxylate synthetase (P5CS) activity and decrease in proline dehydrogenase (PDH) activity in the peel and the flesh, without activation of ornithine-δ-aminotransferase (OAT) activity, and maintained high ATP level and energy charge in the flesh during storage. It was suggested that these effects of oxalic acid might collectively contribute to improving chilling tolerance, thereby alleviating chilling injury and maintaining quality of mango fruit in long term cold storage.

  9. Kinetic spectrophotometric method for the determination of oxalic acid by its catalytic effect on the oxidation of safranine by dichromate

    NASA Astrophysics Data System (ADS)

    Ensafi, Ali A.; Abbasi, S.; Rezaei, B.

    2001-08-01

    A new catalytic kinetic spectrophotometric method for the determination of oxalic acid has been described based on its catalytic effect on the redox reaction between safranine and dichromate in dilute sulfuric acid media. The reaction is monitored photometrically by measuring the decrease in absorbance of safranine at the maximum wavelength of 530 nm. Under the optimum conditions, a calibration graph from 0.10 to 10.00 μg ml -1 of oxalic acid with a detection limit of 0.08 μg ml -1 was obtained. The relative standard deviation (R.S.D.) for ten replicate measurements of 1.0 and 5.0 μg ml -1 oxalic acid was 2.7 and 2.5%, respectively. The purposed method is simple, sensitive, selective and inexpensive. The applicability of the proposed method was determined by the determination of oxalic acid in spinach and wastewater samples with satisfactory results.

  10. Kinetic spectrophotometric method for the determination of oxalic acid by its catalytic effect on the oxidation of safranine by dichromate.

    PubMed

    Ensafi, A A; Abbasi, S; Rezaei, B

    2001-08-01

    A new catalytic kinetic spectrophotometric method for the determination of oxalic acid has been described based on its catalytic effect on the redox reaction between safranine and dichromate in dilute sulfuric acid media. The reaction is monitored photometrically by measuring the decrease in absorbance of safranine at the maximum wavelength of 530 nm. Under the optimum conditions, a calibration graph from 0.10 to 10.00 microg ml(-1) of oxalic acid with a detection limit of 0.08 microg ml(-1) was obtained. The relative standard deviation (R.S.D.) for ten replicate measurements of 1.0 and 5.0 microg ml(-1) oxalic acid was 2.7 and 2.5%, respectively. The purposed method is simple, sensitive, selective and inexpensive. The applicability of the proposed method was determined by the determination of oxalic acid in spinach and wastewater samples with satisfactory results.

  11. Comparing oxalic acid and sucrocide treatments for Varroa destructor (Acari: Varroidae) control under desert conditions.

    PubMed

    Sammataro, D; Finley, J; Underwood, R

    2008-08-01

    The effectiveness of oxalic acid (OA) and Sucrocide (S) (AVA Chemical Ventures, L.L.C., Portsmouth, NH) in reducing populations of the varroa mite Varroa destructor Anderson & Trueman (Acari: Varroidae) in honey bee, Apis mellifera L. (Hymenoptera: Apidae) colonies was measured under the desert conditions of Arizona, USA. OA and S were applied three times 7 d apart. A 3.2% solution of OA was applied in sugar syrup via a large volume syringe, trickling 5 ml per space between frames in the colony. S was applied at a concentration of 0.625% (mixed with water), according to the label directions, using a compressed air Chapin sprayer at 20 psi to apply 59 ml per frame space. Varroa mites, collected on a sticky board before, during, and after the treatments, were counted to assess the effectiveness of the treatments. This study showed that a desert climate zone did not confer any positive or negative results on the acaricidal properties of OA. Even with brood present in colonies, significant varroa mite mortality occurred in the OA colonies. In contrast, we found that Sucrocide was not effective as a mite control technique. Despite its ability to increase mite mortality in the short-term, varroa mite populations measured posttreatment were not affected any more by Sucrocide than by no treatment at all.

  12. Rotenone and oxalic acid as alternative acaricidal treatments for Varroa destructor in honeybee colonies.

    PubMed

    Gregorc, Ales; Poklukar, Janez

    2003-02-27

    This experiment assessed the efficacy of rotenone and oxalic acid (OA) in an aqueous sugar solution in controlling the honeybee mite Varroa destructor. Colonies were populated with mite-infested brood combs and worker bees. Three rotenone or OA treatments administered during the period with capped brood on 31 July, 14 and 18 August resulted in an average efficacy of 24.10%. In untreated colonies mite mortality averaged 5.40%. No significant differences (P>0.05) were found between the rotenone and OA treatments. Three OA treatments administered on 9, 12 and 18 September resulted in a 77.93% mite mortality. An increase in mite drop (P<0.05) was observed at 2 and 4 days after each treatment. OA applications in broodless colonies resulted in significantly (P<0.001) higher mite mortality rates (98.65% average) than the three treatments of rotenone or OA in colonies with capped brood. The dynamics of mite mortality after each rotenone or OA treatment are discussed in this study.

  13. Deuterium MAS NMR studies of dynamics on multiple timescales: histidine and oxalic acid.

    PubMed

    Chan-Huot, Monique; Wimperis, Stephen; Gervais, Christel; Bodenhausen, Geoffrey; Duma, Luminita

    2015-01-12

    Deuterium ((2) H) magic-angle spinning (MAS) nuclear magnetic resonance is applied to monitor the dynamics of the exchanging labile deuterons of polycrystalline L-histidine hydrochloride monohydrate-d7 and α-oxalic acid dihydrate-d6 . Direct experimental evidence of fast dynamics is obtained from T1Z and T1Q measurements. Further motional information is extracted from two-dimensional single-quantum (SQ) and double-quantum (DQ) MAS spectra. Differences between the SQ and DQ linewidths clearly indicate the presence of motions on intermediate timescales for the carboxylic moiety and the D2 O in α-oxalic acid dihydrate, and for the amine group and the D2 O in L-histidine hydrochloride monohydrate. Comparison of the relaxation rate constants of Zeeman and quadrupolar order with the relaxation rate constants of the DQ coherences suggests the co-existence of fast and slow motional processes.

  14. Composites of manganese oxide with carbon materials as catalysts for the ozonation of oxalic acid.

    PubMed

    Orge, C A; Órfão, J J M; Pereira, M F R

    2012-04-30

    Manganese oxide and manganese oxide-carbon composites were prepared and tested as catalysts for the removal of oxalic acid by ozonation. Their performances were compared with the parent carbon material (activated carbon or carbon xerogel) used to prepare the composites. Oxalic acid degradation by carbon materials is slower than that attained with manganese oxide or manganese oxide-carbon composites. A complete degradation after 90 and 45 min of reaction was obtained for carbon materials and for the catalysts containing manganese, respectively. The ozonation in the presence of the prepared composites are supposed to occur mainly by surface reactions, following a direct oxidation mechanism by molecular ozone and/or surface oxygenated radicals.

  15. Characterization of ofloxacin-oxalic acid complex by PXRD, NMR, and THz spectroscopy.

    PubMed

    Limwikrant, Waree; Higashi, Kenjirou; Yamamoto, Keiji; Moribe, Kunikazu

    2009-12-01

    A novel ofloxacin-oxalic acid complex was prepared by the cogrinding method. The obtained complex was characterized by powder X-ray diffraction (PXRD), infrared (IR), solid-state nuclear magnetic resonance (NMR), and terahertz (THz) spectroscopy. The PXRD measurement revealed that the ofloxacin-oxalic acid complex induced by cogrinding was formed at a molar ratio of 1:2. Weak interaction between two components, not a hydrogen bonding, was found by IR and solid-state NMR spectroscopy. The distinctive THz spectrum showed that the vibrational modes of the complex were different from those of the starting materials, suggesting that THz spectroscopy is an alternative tool to evaluate complex formation through weak interactions.

  16. IN-SITU MONITORING OF CORROSION DURING A LABORATORY SIMULATION OF OXALIC ACID CHEMICAL CLEANING

    SciTech Connect

    Wiersma, B; John Mickalonis, J; Michael Poirier, M; John Pareizs, J; David Herman, D; David Beam, D; Samuel Fink, S; Fernando Fondeur, F

    2007-10-08

    The Savannah River Site (SRS) will disperse or dissolve precipitated metal oxides as part of radioactive waste tank closure operations. Previously SRS used oxalic acid to accomplish this task. To better understand the conditions of oxalic acid cleaning of the carbon steel waste tanks, laboratory simulations of the process were conducted to determine the corrosion rate of carbon steel and the generation of gases such as hydrogen and carbon dioxide. Open circuit potential measurements, linear polarization measurements, and coupon immersion tests were performed in-situ to determine the corrosion behavior of carbon steel during the demonstration. Vapor samples were analyzed continuously to determine the constituents of the phase. The combined results from these measurements indicated that in aerated environments, such as the tank, that the corrosion rates are manageable for short contact times and will facilitate prediction and control of the hydrogen generation rate during operations.

  17. Induction of an oxalate decarboxylase in the filamentous fungus Trametes versicolor by addition of inorganic acids.

    PubMed

    Zhu, Cui Xia; Hong, Feng

    2010-01-01

    In order to improve yields and to reduce the cost of oxalate decarboxylase (OxDC, EC 4.1.1.2), the induction of OxDC in the white-rot fungus Trametes versicolor was studied in this work. OxDC was induced by addition of inorganic acids including hydrochloric acid, sulfuric acid, and phosphoric acid to culture media. The results showed that all the acids could enhance OxDC expression. The activity of the acid-induced OxDC rose continuously. All of the OxDC volumetric activities induced by the inorganic acids were higher than 20.0 U/L and were two times higher than that obtained with oxalic acid. OxDC productivity was around 4.0 U*L(-1)*day(-1). The highest specific activity against total protein was 3.2 U/mg protein at day 8 after induction of sulfuric acid, and the specific activity against mycelial dry weight was 10.6 U/g at day 9 after induction of hydrochloric acid. The growth of mycelia was inhibited slightly when the pH values in culture media was around 2.5-3.0, while the growth was inhibited heavily when the pH was lower than 2.5.

  18. Oxalate catabolism in Arabidopsis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Oxalic acid is found in most plant species and can serve beneficial roles that protect the plant from a variety of environmental stresses. Excessive amounts of oxalate, however, can be detrimental to plant health. Thus, careful coordination of oxalate metabolism is needed. Despite the important impa...

  19. Oxidation of ferrocene by thiocyanic acid in the presence of ammonium oxalate

    SciTech Connect

    Ruslin, Farah bt; Yamin, Bohari M.

    2014-09-03

    A flake-like crystalline salt was obtained from the reaction of ferrocene, oxalic acid and ammonium thiocyanate in ethanol The elemental analysis and spectroscopic data were in agreement with the preliminary X-ray molecular structure. The compound consists of four ferrocenium moieties and a counter anion consisting of two (tetraisothiocyanato)iron(III) linked by an oxalato bridging group in such a way that both iron central atoms adopt octahedral geometries.

  20. Removal of oxalic acid, oxamic acid and aniline by a combined photolysis and ozonation process.

    PubMed

    Orge, C A; Faria, J L; Pereira, M F R

    2015-01-01

    Aniline (ANL), an aromatic amine, oxalic acid (OXA) and oxamic acid (OMA), short-chain carboxylic acids, were chosen as model organic pollutants for testing the combined effect of neat photolysis and ozonation in the treatment of aqueous effluents. In order to better understand the results, single ozonation and neat photolysis were also carried out. OXA has a high refractory character relatively to single ozonation and neat photolysis only accounted for 26% conversion of OXA after 2 h of reaction. On the other hand, OXA complete degradation was observed in less than an hour when ozone and light were used simultaneously. Despite OMA, a compound never studied before by a combined ozonation and photolysis treatment, being highly refractory to oxidation, more than 50% was removed by photo-ozonation after 3 h of reaction. In the case of ANL, both single ozonation and photo-ozonation resulted in 100% removal in a short reaction period due to the high reactivity of ozone to attack this type of molecules; however, only the combined method leads to efficient mineralization (89%) after 3 h of reaction. A significant synergetic effect was observed in the degradation of the selected contaminants by the simultaneous use of ozone and light, since the mineralization rate of combined method is higher than the sum of the mineralization rates of the individual treatments. The promising results observed in the degradation of the selected contaminants are paving the way to the application of photo-ozonation in the treatment of wastewater containing this type of pollutants.

  1. The Role of Oxalic Acid in New Particle Formation from Methanesulfonic Acid, Methylamine, and Water.

    PubMed

    Arquero, Kristine D; Gerber, R Benny; Finlayson-Pitts, Barbara J

    2017-02-21

    Atmospheric particles are notorious for their effects on human health and visibility and are known to influence climate. Though sulfuric acid and ammonia/amines are recognized as main contributors to new particle formation (NPF), models and observations have indicated that other species may be involved. It has been shown that nucleation from methanesulfonic acid (MSA) and amines, which is enhanced with added water, can also contribute to NPF. While organics are ubiquitous in air and likely to be involved in NPF by stabilizing small clusters for further growth, their effects on the MSA-amine system are not known. This work investigates the effect of oxalic acid (OxA) on NPF from the reaction of MSA and methylamine (MA) at 1 atm and 294 K in the presence and absence of water vapor using an aerosol flow reactor. OxA and MA do not efficiently form particles even in the presence of water, but NPF is enhanced when adding MSA to OxA-MA with and without water. The addition of OxA to MSA-MA mixtures yields a modest NPF enhancement, whereas the addition of OxA to MSA-MA-H2O has no effect. Possible reasons for these effects are discussed.

  2. Bioethanol production from deacetylated yellow poplar pretreated with oxalic acid recovered through electrodialysis.

    PubMed

    Kundu, Chandan; Jeong, So-Yeon; Lee, Jae-Won

    2016-05-01

    Electrodialysis (ED) was used to develop a multistage oxalic acid recovery and pretreatment system to produce ethanol from deacetylated yellow poplar. Pretreatment of the biomass was performed at 150°C for 42 min using 0.16 M oxalic acid. The efficiency of oxalic acid recovery from the hydrolysate reached up to 92.32% in all the stages. Ethanol production and ethanol yield of ED-treated hydrolysate in each stage showed a uniform pattern ranging from 6.81 g/L to 7.21 g/L and 0.40 g/g to 0.43 g/g, respectively. The results showed that efficiency of ethanol production increased when deacetylated biomass and ED process was used. Ethanol yield from the pretreated biomass using simultaneous saccharification and fermentation (SSF) was in the range of 80.59-83.36% in all the stages. The structural characterization of the pretreated biomass at each stage was investigated and structural changes were not significantly different among the various pretreated biomass.

  3. Theoretical study on the structure and stabilities of molecular clusters of oxalic acid with water.

    PubMed

    Weber, Kevin H; Morales, Francisco J; Tao, Fu-Ming

    2012-11-29

    The importance of aerosols to humankind is well-known, playing an integral role in determining Earth's climate and influencing human health. Despite this fact, much remains unknown about the initial events of nucleation. In this work, the molecular properties of common organic atmospheric pollutant oxalic acid and its gas phase interactions with water have been thoroughly examined. Local minima single-point energies for the monomer conformations were calculated at the B3LYP and MP2 level of theory with both 6-311++G(d,p) and aug-cc-pVDZ basis sets and are compared with previous works. Optimized geometries, relative energies, and free energy changes for the stable clusters of oxalic acid conformers with up to six waters were then obtained from B3LYP calculations with 6-31+G(d) and 6-311++G(d,p) basis sets. Initially, cooperative binding is predicted to be the most important factor in nucleation, but as the clusters grow, dipole cancellations are found to play a pivotal role. The clusters of oxalic acid hydrated purely with water tend to produce extremely stable and neutral core systems. Free energies of formation and atmospheric implications are discussed.

  4. PREPARATION OF OXALATES OF METALS OF ATOMIC NUMBER GREATER THAN 88

    DOEpatents

    Duffield, R.B.

    1959-02-01

    A method is presented for the preparation of oxalates of metals of atomic number greater than 88. A solid peroxide of the heavy metal is contacted with an aqueous oxalic acid solution ai a temperature of about 50 C for a period of time sufficient to form the insoluble metal oxalate which is subsequentiy recovered as a pures crystalline compound.

  5. Preparation of iron oxide-impregnated spherical granular activated carbon-carbon composite and its photocatalytic removal of methylene blue in the presence of oxalic acid.

    PubMed

    Kadirova, Zukhra C; Hojamberdiev, Mirabbos; Katsumata, Ken-Ichi; Isobe, Toshihiro; Matsushita, Nobuhiro; Nakajima, Akira; Sharipov, Khasan; Okada, Kiyoshi

    2014-01-01

    The spherical granular activated carbon-carbon composites (GAC-Fe) with different iron oxide contents (Fe mass% = 0.6-10) were prepared by a pore volume impregnation method. The X-ray diffraction (XRD), scanning electron microscopy (SEM), and N2-adsorption results confirm the presence of amorphous iron oxide, pyrolytic carbon, and graphitized globular carbon nanoparticles covered with amorphous carbon in the CAG-Fe. The rate of photodegradation of methylene blue (MB) in aqueous solution under UV light in the presence of oxalic acid correlates with porosity of the prepared materials. The total MB removal includes the combination of adsorption and photodegradation without the addition of H2O2. The results of total organic carbon (TOC) analysis reveal that the decolorization of MB in aqueous solution containing oxalic acid corresponds to the decomposition of organic compounds to CO2 and H2O.

  6. Reaction mechanism and metal ion transformation in photocatalytic ozonation of phenol and oxalic acid with Ag(+)/TiO2.

    PubMed

    Chen, Yingying; Xie, Yongbing; Yang, Jun; Cao, Hongbin; Zhang, Yi

    2014-03-01

    Photocatalytic ozonation of phenol and oxalic acid (OA) was conducted with a Ag(+)/TiO2 catalyst and different pathways were found for the degradation of different compounds. Ag(+) greatly promoted the photocatalytic degradation of contaminants due to its role as an electron scavenger. It also accelerated the removal rate of OA in ozonation and the simultaneous process for its complex reaction with oxalate. Phenol could be degraded both in direct ozonation and photolysis, but the TOC removal rates were much higher in the simultaneous processes due to the oxidation of hydroxyl radicals resulting from synergetic effects. The sequence of photo-illumination and ozone exposure in the combined process showed quite different effects in phenol degradation and TOC removal. The synergetic effects in different combined processes were found to be highly related to the properties of the target pollutants. The color change of the solution and TEM result confirmed that Ag(+) was easily reduced and deposited on the surface of TiO2 under photo-illumination, and dissolved again into solution in the presence of ozone. This simple cycle of enrichment and distribution of Ag(+) can greatly benefit the design of advanced oxidation processes, in which the sequences of ozone and photo-illumination can be varied according to the needs for catalyst recycling and the different properties of pollutants.

  7. Effect of Macerase, Oxalic Acid, and EGTA on Deep Supercooling and Pit Membrane Structure of Xylem Parenchyma of Peach

    PubMed Central

    Wisniewski, Michael; Davis, Glen; Arora, Rajeev

    1991-01-01

    The object of this study was to determine if calcium cross-linking of pectin in the pit membrane of xylem parenchyma restricts water movement which results in deep supercooling. Current year shoots of `Loring' peach (Prunus persica) were infiltrated with oxalic acid or EGTA solutions for 24 or 48 hours and then either prepared for ultrastructural analysis or subjected to differential thermal analysis. The effect of 0.25 to 1.0% pectinase (weight/volume) on deep supercooling was also investigated. The use of 5 to 50 millimolar oxalic acid and pectinase resulted in a significant reduction (flattening) of the low temperature exotherm and a distinct swelling and partial degradation of the pit membrane. EGTA (10 millimolar) for 24 or 48 hours shifted the low temperature exotherm to warmer temperatures and effected the outermost layer of the pit membrane. A hypothesis is presented on pectin-mediated regulation of deep supercooling of xylem parenchyma. ImagesFigure 3Figure 4Figure 5Figure 6Figure 7Figure 8 PMID:16668341

  8. Use of microfocused X-ray techniques to investigate the mobilization of arsenic by oxalic acid

    NASA Astrophysics Data System (ADS)

    Wovkulich, Karen; Mailloux, Brian J.; Bostick, Benjamin C.; Dong, Hailiang; Bishop, Michael E.; Chillrud, Steven N.

    2012-08-01

    Improved linkages between aqueous phase transport and solid-phase reactions are needed to better predict and model transport of contaminants through the subsurface. Here we develop and apply a new method for measuring As mobilization in situ within soil columns that utilizes synchrotron-based X-ray fluorescence. By performing these measurements in situ during column transport experiments, we simultaneously monitor grain-scale solid phase reactions and column-scale transport. Arsenic may be effectively mobilized by oxalic acid but the geochemical and mineralogical factors that influence the rate and extent of mobilization are not well understood. Column experiments (˜4 cm long × 0.635 cm ID) using As contaminated sediments from the Vineland Chemical Company Superfund site were performed on the laboratory bench as well as in the synchrotron beamline. Microfocused synchrotron X-ray fluorescence (μSXRF) maps for As and Fe were collected at the same location in the columns (<1 mm2) before and during treatment with 10 mM oxalic acid. The fraction of As and Fe removed by oxalic acid treatment was calculated from the change in flux-normalized counts for each pixel in the map images, and these data were used to calculate kinetic parameters over the studied area. Between 79% and 83% of the As was removed from the sediments by the oxalic acid treatment based on μSXRF data; these removal percentages agreed well with laboratory data based on column effluent (88-95%). Considerably less Fe was removed by oxalic acid treatment, 14-25% based on μSXRF counts, which is somewhat higher than the 7-9% calculated from laboratory column effluent concentrations. Microfocused X-ray absorption near edge spectroscopy (μXANES) on a subset of points indicates most of the Fe was oxidized and present as a mixture of goethite, hematite, and ferrihydrite on sand grain coatings. Treatment with oxalic acid led to subtle shifts in Fe (III) species following oxalic acid treatment, either removing

  9. Use of Microfocused X-ray Techniques to Investigate the Mobilization of As by Oxalic Acid

    PubMed Central

    Wovkulich, Karen; Mailloux, Brian J.; Bostick, Benjamin C.; Dong, Hailiang; Bishop, Michael E.; Chillrud, Steven N.

    2012-01-01

    Improved linkages between aqueous phase transport and solid-phase reactions are needed to better predict and model transport of contaminants through the subsurface. Here we develop and apply a new method for measuring As mobilization in situ within soil columns that utilizes synchrotron-based X-ray fluorescence. By performing these measurements in situ during column transport experiments, we simultaneously monitor grain-scale solid phase reactions and column-scale transport. Arsenic may be effectively mobilized by oxalic acid but the geochemical and mineralogical factors that influence the rate and extent of mobilization are not well understood. Column experiments (~4 cm long × 0.635 cm ID) using As contaminated sediments from the Vineland Chemical Company Superfund site were performed on the laboratory bench as well as in the synchrotron beamline. Microfocused synchrotron X-ray fluorescence (μSXRF) maps for As and Fe were collected at the same location in the columns (<1 mm2) before and during treatment with 10 mM oxalic acid. The fraction of As and Fe removed by oxalic acid treatment was calculated from the change in flux-normalized counts for each pixel in the map images, and these data were used to calculate kinetic parameters over the studied area. Between 79% and 83% of the As was removed from the sediments by the oxalic acid treatment based on μSXRF data; these removal percentages agreed well with laboratory data based on column effluent (88–95%). Considerably less Fe was removed by oxalic acid treatment, 14–25% based on μSXRF counts, which is somewhat higher than the 7–9% calculated from laboratory column effluent concentrations. Microfocused X-ray absorption near edge spectroscopy (μXANES) on a subset of points indicates most of the Fe was oxidized and present as a mixture of goethite, hematite, and ferrihydrite on sand grain coatings. Treatment with oxalic acid led to subtle shifts in Fe (III) species following oxalic acid treatment, either

  10. New cloud chamber experiments on the heterogeneous ice nucleation ability of oxalic acid in the deposition nucleation and immersion freezing modes

    NASA Astrophysics Data System (ADS)

    Moehler, O.; Wagner, R.; Saathoff, H.; Schnaiter, M.; Leisner, T.

    2010-12-01

    Dicarboxylic acids are ubiquitous components of the water-soluble organic fraction of the tropospheric aerosol. Their contribution to the total particulate organic carbon typically ranges from 1 - 3 wt% in urban and semi-urban areas to up to 10 wt% in remote marine atmospheres [1,2]. Oxalic acid, malonic acid, and succinic acid are usually the most abundant species, partly comprising more than 80% of the total diacid mass concentrations [3]. Several recent studies have addressed the ice nucleation potential of solid low-molecular weight dicarboxylic acids. On the one hand, the dicarboxylic acids can act as deposition mode ice nuclei provided that they are directly exposed to an ice supersaturated environment, e.g. in form of a coating layer that was formed by physical and chemical processing on prevalent particulates such as mineral dust and soot. At typical tropospheric relative humidities, diacids of low water solubility like oxalic and succinic acid may, on the other hand, also be present as solids that are immersed in aqueous inorganic and/or organic solution droplets [4,5]. These embedded crystals can act as ice nuclei in the immersion mode. Here we present new results from recent experiments at the aerosol and cloud chamber facility of the Karlsruhe Institute of Technology. The ice nucleation ability of aqueous and crystalline oxalic acid aerosol particles was investigated at expansion cooling conditions in the temperature range between 244 and 228 K [6]. Oxalic acid dihydrate particles with diameters between 0.03 to 0.8 μm, that were either formed by nucleation from a gaseous oxalic acid/air mixture or by rapid crystallisation of highly supersaturated aqueous oxalic acid solution droplets, showed a high deposition mode ice activity at temperatures around 244 K. The ice onset humidity was below 110 % with respect to ice, and the ice-active fraction of the aerosol population was in the range from 0.1 to 22%. In contrast, oxalic acid dihydrate particles

  11. Thermodynamics of the Complexation of Uranium(VI) by oxalate in aqueous solution at 10-70oC

    SciTech Connect

    Di Bernardo, Plinio; Zanonato, Pier Luigi; Tian, Guoxin; Tolazzi, Marilena; Rao, Linfeng

    2009-03-31

    The protonation reactions of oxalate (ox) and the complex formation of uranium(VI) with oxalate in 1.05 mol kg{sup -1} NaClO{sub 4} were studied at variable temperatures (10-70 C). Three U(VI)/ox complexes (UO{sub 2}ox{sub j}{sup (2-2j){sup +}} with j = 1, 2, 3) were identified in this temperature range. The formation constants and the molar enthalpies of complexation were determined by spectrophotometry and calorimetry. The complexation of uranium(VI) with oxalate ion is exothermic at lower temperatures (10-40 C) and becomes endothermic at higher temperatures (55-70 C). In spite of this, the free energy of complexation becomes more negative at higher temperatures due to increasingly more positive entropy of complexation that exceeds the increase of the enthalpy of complexation. The thermodynamic parameters at different temperatures, in conjunction with the literature data for other dicarboxylic acids, provide insight into the relative strength of U(VI) complexes with a series of dicarboxylic acids (oxalic, malonic and oxydiacetic) and rationalization for the highest stability of U(VI)/oxalate complexes in the series. The data reported in this study are of importance in predicting the migration of uranium(VI) in geological environments in the case of failure of the engineering barriers which protect waste repositories.

  12. [EXPERIENCE OF USE OF BLEMAREN® IN THE TREATMENT OF PATIENTS IN URIC ACID AND CALCIUM OXALATE UROLITHIASIS].

    PubMed

    Konstantinova, O V; Yanenko, E K

    2015-01-01

    154 patients with urolithiasis were under outpatient observation for 2-8 years. Among them there were 76 women and 78 men aged 21-66 years, of which 46 patients with uric acid urolithiasis, and 88--with calcium oxalate urolithiasis. Treatment of patients was carried out systematically, depending on their condition. Indications for the application of Blemaren® included the presence of uric acid stones, uric acid and/or oxalate crystalluria. The duration of treatment was 6.1 months. The dosage of the drug varied from 6 to 18 g per day and was selected individually, depending on the purpose of the appointment of Blemaren®. Reduction of the urine pH to 6.2- 6.8-7.2 was the criterion for properly selected dose. To dissolve uric acid stones in the presence of hyperuricemia and/or hyperuricuria, Blemaren® was administered in combination with allopurinol at a dose of 0.1 g 3-4 times a day. Besides pharmacotherapy, treatment included diet therapy. It was found that the morning urine pH in urate urolithiasis is sustainable and has a range of 5.0-6.0, in 80.4% of cases--range of 5.0-5.5. In calcium oxalate urolithiasis this parameter is also stable and has a range of 5.0-6.7, in 82.9% of cases--range of 5.5-6.0. Optimal urine pH to eliminate uric acid and oxalate crystalluria in patients with uric acid and calcium oxalate urolithiasis is the interval of 6.2-6.4. It was shown that Blemaren® is a highly effective agent for treatment and prevention of uric acid and calcium oxalate crystalluria in calcium oxalate and uric acid urolithiasis. Further, its effectiveness in dissolving of uric acid stones in the absence of an infectious inflammatory process is 82.3%.

  13. Communication: Remarkable electrophilicity of the oxalic acid monomer: an anion photoelectron spectroscopy and theoretical study.

    PubMed

    Buonaugurio, Angela; Graham, Jacob; Buytendyk, Allyson; Bowen, Kit H; Ryder, Matthew R; Keolopile, Zibo G; Haranczyk, Maciej; Gutowski, Maciej

    2014-06-14

    Our experimental and computational results demonstrate an unusual electrophilicity of oxalic acid, the simplest dicarboxylic acid. The monomer is characterized by an adiabatic electron affinity and electron vertical detachment energy of 0.72 and 1.08 eV (±0.05 eV), respectively. The electrophilicity results primarily from the bonding carbon-carbon interaction in the singly occupied molecular orbital of the anion, but it is further enhanced by intramolecular hydrogen bonds. The well-resolved structure in the photoelectron spectrum is reproduced theoretically, based on Franck-Condon factors for the vibronic anion → neutral transitions.

  14. The Relationship between Serum Oxalic Acid, Central Hemodynamic Parameters and Colonization by Oxalobacter formigenes in Hemodialysis Patients

    PubMed Central

    Gulhan, Baris; Turkmen, Kultigin; Aydin, Merve; Gunay, Murat; Cıkman, Aytekin; Kara, Murat

    2015-01-01

    Background/Objective Elevated pulse wave velocity (PWV) and central aortic blood pressures are independent predictors of increased cardiovascular morbidity and mortality in hemodialysis (HD) patients. Oxalic acid is a uremic retention molecule that is extensively studied in the pathogenesis of calcium oxalate stones. Oxalobacter formigenes, a member of the colon microbiota, has important roles in oxalate homeostasis. Data regarding the colonization by and the exact role of O. formigenes in the pathogenesis of oxalic acid metabolism in HD patients are scant. Hence, we aimed to determine the relationship between fecal O. formigenes colonization, serum oxalic acid and hemodynamic parameters in HD patients with regard to the colo-reno-cardiac axis. Methods Fifty HD patients were enrolled in this study. PWV and central aortic systolic (cASBP) and diastolic blood pressures (cADBP) were measured with a Mobil-O-Graph (I.E.M. GmbH, Stolberg, Germany). Serum oxalic acid levels were assessed by ELISA, and fecal O. formigenes DNA levels were isolated and measured by real-time PCR. Results Isolation of fecal O. formigenes was found in only 2 HD patients. One of them had 113,609 copies/ml, the other one had 1,056 copies/ml. Serum oxalic acid levels were found to be positively correlated with PWV (r = 0.29, p = 0.03), cASBP (r = 0.33, p = 0.001) and cADBP (r = 0.42, p = 0.002) and negatively correlated with LDL (r = −0.30, p = 0.03). In multivariate linear regression analysis, PWV was independently predicted by oxalic acid, glucose and triglyceride. Conclusions This is the first study that demonstrates the absence of O. formigenes as well as a relation between serum oxalic acid and cASBP, cADBP and PWV in HD patients. Replacement of O. formigenes with pre- and probiotics might decrease serum oxalic acid levels and improve cardiovascular outcomes in HD patients. PMID:26195968

  15. Corrosion Behavior of Alloy 22 in Chloride Solutions Containing Organic Acids

    SciTech Connect

    Carranza, R M; Giordano, C M; Rodr?guez, M A; Rebak, R B

    2005-11-04

    Alloy 22 (N06022) is a nickel based alloy containing alloying elements such as chromium, molybdenum and tungsten. It is highly corrosion resistant both under reducing and under oxidizing conditions. Electrochemical studies such as electrochemical impedance spectroscopy (EIS) were performed to determine the corrosion behavior of Alloy 22 in 1M NaCl solutions at various pH values from acidic to neutral at 90 C. Tests were also carried out in NaCl solutions containing oxalic acid or acetic acid. It is shown that the corrosion rate of Alloy 22 was higher in a solution containing oxalic acid than in a solution of the same pH acidified with HCl. Acetic acid was not corrosive to Alloy 22. The corrosivity of oxalic acid was attributed to its capacity to form stable complex species with metallic cations from Alloy 22.

  16. Absorption kinetics of oxalate from oxalate-rich food in man.

    PubMed

    Prenen, J A; Boer, P; Dorhout Mees, E J

    1984-11-01

    The absorption of oxalate was investigated in a healthy subject after ingestion of oxalate-rich meals (spinach and rhubarb) with and without addition of 14C-labeled oxalic acid and calcium oxalate, and after oxalate-free meals with addition of nonlabeled sodium oxalate and calcium oxalate. Under these conditions, calcium oxalate was absorbed to the same extent as soluble oxalate; only a small percentage (2.4 +/- 0.7) of the total oxalate load was absorbed. Significant oxalate absorption occurred within 1 to 8 h after ingestion. The results suggest that under normal conditions the proximal part of the small bowel is a major absorption site.

  17. Inhibition of calcium oxalate crystal growth in vitro by uropontin: another member of the aspartic acid-rich protein superfamily.

    PubMed Central

    Shiraga, H; Min, W; VanDusen, W J; Clayman, M D; Miner, D; Terrell, C H; Sherbotie, J R; Foreman, J W; Przysiecki, C; Neilson, E G

    1992-01-01

    The majority of human urinary stones are primarily composed of calcium salts. Although normal urine is frequently supersaturated with respect to calcium oxalate, most humans do not form stones. Inhibitors are among the multiple factors that may influence the complex process of urinary stone formation. We have isolated an inhibitor of calcium oxalate crystal growth from human urine by monoclonal antibody immunoaffinity chromatography. The N-terminal amino acid sequence and acidic amino acid content of this aspartic acid-rich protein, uropontin, are similar to those of other pontin proteins from bone, plasma, breast milk, and cells. The inhibitory effect of uropontin on calcium oxalate crystal growth in vitro supports the concept that pontins may have a regulatory role. This function would be analogous to that of other members of the aspartic acid-rich protein superfamily, which stereospecifically regulate the mineralization fronts of calcium-containing crystals. Images PMID:1729712

  18. Adsorption and oxidation of oxalic acid on anatase TiO2 (001) surface: A density functional theory study.

    PubMed

    Sun, Tao; Wang, Yun; Zhang, Haimin; Liu, Porun; Zhao, Huijun

    2015-09-15

    Anatase TiO2 (001) surfaces have attracted great interest for photo-degradation of organic species recently due to their high reactivity. In this work, adsorption properties and oxidation mechanisms of oxalic acid on the anatase TiO2 (001) surface have been theoretically investigated using the first-principles density functional theory. Various possible adsorption configurations are considered by diversifying the connectivity of carboxylic groups with the surface. It is found that the adsorption of oxalic acid on the anatase (001) surface prefer the dissociative states. A novel double-bidentate configuration has been found due to the structural match between oxalic acid and the (001) surface. More charge is transferred from the adsorbed oxalic acid to the surface with the double-bidentate configuration when comparing with other adsorption structures. Thus, there is a positive correlation relationship between the transferred charge amount and the interfacial bond numbers when oxalic acid adsorbs on the anatase TiO2 (001) surface. The adsorption energies with dispersion corrections have demonstrated that the van der Waals interactions play an important role in the adsorption, especially when adsorbates are close to the surface.

  19. The roles of xylan and lignin in oxalic acid pretreated corncob during separate enzymatic hydrolysis and ethanol fermentation.

    PubMed

    Lee, Jae-Won; Rodrigues, Rita C L B; Kim, Hyun Joo; Choi, In-Gyu; Jeffries, Thomas W

    2010-06-01

    High yields of hemicellulosic and cellulosic sugars are critical in obtaining economical conversion of agricultural residues to ethanol. To optimize pretreatment conditions, we evaluated oxalic acid loading rates, treatment temperatures and times in a 2(3) full factorial design. Response-surface analysis revealed an optimal oxalic acid pretreatment condition to release sugar from the cob of Zea mays L. ssp. and for Pichia stipitis CBS 6054. To ferment the residual cellulosic sugars to ethanol following enzymatic hydrolysis, highest saccharification and fermentation yields were obtained following pretreatment at 180 degrees C for 50 min with 0.024 g oxalic acid/g substrate. Under these conditions, only 7.5% hemicellulose remained in the pretreated substrate. The rate of cellulose degradation was significantly less than that of hemicellulose and its hydrolysis was not as extensive. Subsequent enzymatic saccharification of the residual cellulose was strongly affected by the pretreatment condition with cellulose hydrolysis ranging between 26.0% and 76.2%. The residual xylan/lignin ratio ranged from 0.31 to 1.85 depending on the pretreatment condition. Fermentable sugar and ethanol were maximal at the lowest ratio of xylan/lignin and at high glucan contents. The model predicts optimal condition of oxalic acid pretreatment at 168 degrees C, 74 min and 0.027 g/g of oxalic acid. From these findings, we surmised that low residual xylan was critical in obtaining maximal glucose yields from saccharification.

  20. A new approach to the decontamination of asbestos-polluted waters by treatment with oxalic acid under power ultrasound.

    PubMed

    Turci, Francesco; Tomatis, Maura; Mantegna, Stefano; Cravotto, Giancarlo; Fubini, Bice

    2008-04-01

    A suspension of chrysotile asbestos fibres in aqueous 0.5M oxalic acid was subjected to power ultrasound with the aim to disrupt and detoxify the mineral by the leaching action of oxalic acid on its structural cations acting simultaneously with a vigorous acoustic cavitation. Sonication was performed in a "cavitating tube", a vertical hollow vibrating cylinder made of titanium, operating at 19.2 kHz and 150 W. Treatment lasted from 2.5 to 21 h. Scanning electron microscopy (SEM) showed that the joint action of the chelating agent and ultrasound (though not of either when applied independently) mostly converted asbestos fibres into micrometric aggregates and nano-sized debris, whose morphology totally differed from asbestos fibres. When treated suspensions were filtered through CA membranes (pore size 0.20 microm), more than half of the asbestos went through the filter because it had either been brought in solution or dispersed in the form of extremely small particles. Most of the structural metal ions were brought into solution (ICP-AES). After the treatment the BET surface area of the recovered solid was tenfold greater than the original. The crystalline fraction of residual solids, though resembling the original sample in XRD, was shown by micro-Raman spectra to be made of antigorite, a polymorph form of serpentine. Furthermore, as the length of these antigorite fibrils lay outside the fibre range rated as a health hazard under worldwide regulations, our procedure can be employed for the decontamination of chrysotile-polluted waters and sediments.

  1. Cadmium induced oxalic acid secretion and its role in metal uptake and detoxification mechanisms in Phanerochaete chrysosporium.

    PubMed

    Xu, Piao; Leng, Yang; Zeng, Guangming; Huang, Danlian; Lai, Cui; Zhao, Meihua; Wei, Zhen; Li, Ningjie; Huang, Chao; Zhang, Chen; Li, Fangling; Cheng, Min

    2015-01-01

    This study examines the role of oxalic acid in the uptake of Cd and participation in detoxification process in Phanerochaete chrysosporium. Cd-induced oxalic acid secretion was observed with growth inhibition and enzyme inactivation (LiP and MnP) of P. chrysosporium. The peak value of oxalic acid concentration was 16.6 mM at initial Cd concentration of 100 mg L(-1). During the short-term uptake experiments, the uptake of Cd was enhanced and accelerated in the presence of oxalic acid and resulted in alleviated growth and enzyme inhibition ratios. The formation of a metal-oxalate complex therefore may provide a detoxification mechanism via effect on metal bioavailability, whereby many fungi can survive and grow in environments containing high concentrations of toxic metals. The present findings will advance the understanding of fungal resistance to metal stress, which could show promise for a more useful application of microbial technology in the treatment of metal-polluted waste.

  2. Separation of Am-Cm from Al(NO/sub 3/)/sub 3/ waste solutions by in-canyon-tank precipitation as oxalates

    SciTech Connect

    Gray, L.W.; Burney, G.A.; Wilson, T.W.; McKibben, J.M.; Bibler, N.E.; Holtzscheiter, E.W.; Campbell, T.G.

    1982-04-01

    A process for recovery of Am-Cm residues from high-activity waste concentrates has been developed specifically for application in Savannah River Plant (SRP) canyon tanks. The Am-Cm residues were collected from a campaign to produce plutonium containing high isotopic concentrations of /sup 242/Pu. The separation of Am-Cm from the high-activity waste stream, containing about 2M Al(NO/sub 3/)/sub 3/, is necessary to produce an acceptable feed solution for a later pressurized cation exchange chromatography separation and purification step. The new process includes formic acid denitration, adjustment of contaminating cations by evaporation and water dilution, and oxalate precipitation of the actinides and lanthanides. After washing, the precipitate was dissolved in 8M nitric acid and the oxalate was destroyed by nitric acid oxidation that was catalyzed by manganous ions. This new process generates about one-fourth the waste of the californium solvent extraction process, which it replaced. The new process also produces a cleaner feed solution for the pressurized cation exchange chromatography separation and purification step.

  3. Efficacy of repeated trickle applications of oxalic acid in syrup for varroosis control in Apis mellifera: influence of meteorological conditions and presence of brood.

    PubMed

    Bacandritsos, Nicolaos; Papanastasiou, Iosif; Saitanis, Costas; Nanetti, Antonio; Roinioti, Erifylli

    2007-09-01

    Oxalic acid field trails for the control of varroosis (Varroa destructor) were carried out in an apiary located on the Mt. Imittos (Attica, Greece). The colonies received four successive applications (approximately one every 16 days) with 4.2% oxalic acid (OA) and 60% sugar solution by trickling method with two alternative types of syringes (an automatic self-filling dosing and a single-use) from the broodright to broodless period. The results indicate that the first three applications (from 6th October to 25th November-broodright period) resulted in 65.3% cumulative mite mortality, while only the last application (after the 26th November-broodless period) resulted in 77.3% mite mortality. Very low outern temperatures reduce to the minimum the bee movability, which may result into a slower development of the OA efficacy. No poor colony growth or queen loss were observed even if the bee colonies were received the four successive OA applications with the last one taken place at a very low outern temperature (6.2 degrees C). The trickling method using an automatic-filling syringe seems to be a very quick way for applying oxalic acid in large apiaries (approximately 150hives/h).

  4. Biosynthesis of l-Ascorbic Acid and Conversion of Carbons 1 and 2 of l-Ascorbic Acid to Oxalic Acid Occurs within Individual Calcium Oxalate Crystal Idioblasts1

    PubMed Central

    Kostman, Todd A.; Tarlyn, Nathan M.; Loewus, Frank A.; Franceschi, Vincent R.

    2001-01-01

    l-Ascorbic acid (AsA) and its metabolic precursors give rise to oxalic acid (OxA) found in calcium oxalate crystals in specialized crystal idioblast cells in plants; however, it is not known if AsA and OxA are synthesized within the crystal idioblast cell or transported in from surrounding mesophyll cells. Isolated developing crystal idioblasts from Pistia stratiotes were used to study the pathway of OxA biosynthesis and to determine if idioblasts contain the entire path and are essentially independent in OxA synthesis. Idioblasts were supplied with various 14C-labeled compounds and examined by micro-autoradiography for incorporation of 14C into calcium oxalate crystals. [14C]OxA gave heavy labeling of crystals, indicating the isolated idioblasts are functional in crystal formation. Incubation with [1-14C]AsA also gave heavy labeling of crystals, whereas [6-14C]AsA gave no labeling. Labeled precursors of AsA (l-[1-14C]galactose; d-[1-14C]mannose) also resulted in crystal labeling, as did the ascorbic acid analog, d-[1-14C]erythorbic acid. Intensity of labeling of isolated idioblasts followed the pattern OxA > AsA (erythorbic acid) > l-galactose > d-mannose. Our results demonstrate that P. stratiotes crystal idioblasts synthesize the OxA used for crystal formation, the OxA is derived from the number 1 and 2 carbons of AsA, and the proposed pathway of ascorbic acid synthesis via d-mannose and l-galactose is operational in individual P. stratiotes crystal idioblasts. These results are discussed with respect to fine control of calcium oxalate precipitation and the concept of crystal idioblasts as independent physiological compartments. PMID:11161021

  5. Novel approach to recover cobalt and lithium from spent lithium-ion battery using oxalic acid.

    PubMed

    Zeng, Xianlai; Li, Jinhui; Shen, Bingyu

    2015-09-15

    With the booming of consumer electronics (CE) and electric vehicle (EV), a large number of spent lithium-ion battery (LIBs) have been generated worldwide. Resource depletion and environmental concern driven from the sustainable industry of CE and EV have motivated spent LIBs should be recovered urgently. However, the conventional process combined with leaching, precipitating, and filtering was quite complicated to recover cobalt and lithium from spent LIBs. In this work, we developed a novel recovery process, only combined with oxalic acid leaching and filtering. When the optimal parameters for leaching process is controlled at 150 min retention time, 95 °C heating temperature, 15 g L(-1) solid-liquid ratio, and 400 rpm rotation rate, the recovery rate of lithium and cobalt from spent LIBs can reach about 98% and 97%, respectively. Additionally, we also tentatively discovered the leaching mechanism of lithium cobalt oxide (LiCoO2) using oxalic acid, and the leaching order of the sampling LiCoO2 of spent LIBs. All the obtained results can contribute to a short-cut and high-efficiency process of spent LIBs recycling toward a sound closed-loop cycle.

  6. The effects of oxalate treatment on the smear layer of ground surfaces of human dentine.

    PubMed

    Pashley, D H; Galloway, S E

    1985-01-01

    The layer was evaluated by scanning electron microscopy and by measurement of hydraulic conductance before and after 2-min topical treatment with potassium chloride, neutral potassium oxalate, half-neutralized oxalic acid or both neutral and acidic oxalates. The treated smear layers were then re-evaluated microscopically and functionally both before and after acid challenge. The layers treated with KCl were not altered either microscopically or functionally and were susceptible to acid etching. Dentine surfaces treated with either oxalate solutions became less permeable and were acid-resistant.

  7. Structural tuning of photoluminescence in nanoporous anodic alumina by hard anodization in oxalic and malonic acids.

    PubMed

    Santos, Abel; Alba, Maria; Rahman, Mahbubur M; Formentín, Pilar; Ferré-Borrull, Josep; Pallarès, Josep; Marsal, Lluis F

    2012-04-19

    We report on an exhaustive and systematic study about the photoluminescent properties of nanoporous anodic alumina membranes fabricated by the one-step anodization process under hard conditions in oxalic and malonic acids. This optical property is analysed as a function of several parameters (i.e. hard anodization voltage, pore diameter, membrane thickness, annealing temperature and acid electrolyte). This analysis makes it possible to tune the photoluminescent behaviour at will simply by modifying the structural characteristics of these membranes. This structural tuning ability is of special interest in such fields as optoelectronics, in which an accurate design of the basic nanostructures (e.g. microcavities, resonators, filters, supports, etc.) yields the control over their optical properties and, thus, upon the performance of the nanodevices derived from them (biosensors, interferometers, selective filters, etc.).

  8. Structural tuning of photoluminescence in nanoporous anodic alumina by hard anodization in oxalic and malonic acids

    PubMed Central

    2012-01-01

    We report on an exhaustive and systematic study about the photoluminescent properties of nanoporous anodic alumina membranes fabricated by the one-step anodization process under hard conditions in oxalic and malonic acids. This optical property is analysed as a function of several parameters (i.e. hard anodization voltage, pore diameter, membrane thickness, annealing temperature and acid electrolyte). This analysis makes it possible to tune the photoluminescent behaviour at will simply by modifying the structural characteristics of these membranes. This structural tuning ability is of special interest in such fields as optoelectronics, in which an accurate design of the basic nanostructures (e.g. microcavities, resonators, filters, supports, etc.) yields the control over their optical properties and, thus, upon the performance of the nanodevices derived from them (biosensors, interferometers, selective filters, etc.) PMID:22515214

  9. The relationship between colonization of Oxalobacter formigenes serum oxalic acid and endothelial dysfunction in hemodialysis patients: from impaired colon to impaired endothelium.

    PubMed

    Turkmen, K; Erdur, F M

    2015-03-01

    Cardiovascular disease (CVD) remains the leading cause of morbidity and mortality in chronic kidney disease (CKD) patients receiving hemodialysis (HD). Oxalic acid is a uremic retention molecule that has been extensively studied in the pathogenesis of calcium-oxalate stones. Oxalobacter formigenes (O. formigenes), a component of the colonic microbiota, plays an important role in oxalate homeostasis. Little is known regarding the colonization of HD patients by O. formigenes and the exact role of this bacterial species in oxalic acid metabolism in these patients. We hypothesized that oxalic acid may be insufficiently degraded in HD patients due to under colonization of the colon by O. formigenes in these patients. To test this hypothesis, we sought to quantitatively measure fecal O. formigenes levels and serum oxalic acid levels in HD patients. We also suggest that increased oxalic acid levels may be associated with endothelial dysfunction and aortic stiffness, both of which are commonly observed in HD patients. Increased colonization with O. formigenes via the ingestion of prebiotics and probiotics could potentially decrease serum oxalic acid levels and improve cardiovascular outcomes in HD patients.

  10. Poly(acrylic acid) to induce competitive crystallization of a theophylline/oxalic acid cocrystal and a theophylline polymorph

    NASA Astrophysics Data System (ADS)

    Jang, Jisun; Kim, Il Won

    2016-01-01

    Polymeric additives to induce competitive crystallization of pharmaceutical compounds were explored. A cocrystal of theophylline and oxalic acid was used as a model system, and poly(acrylic acid), poly(caprolactone), and poly(ethylene glycol) were the additives. The cocrystal formation was selectively hindered with addition of poly(acrylic acid). First the size of the cocrystals were reduced, and eventually the cocrystallization was inhibited to generate neat theophylline crystals. The theophylline crystals were of a distinctively different crystal structure from known polymorphs, based on powder X-ray diffraction. They were also obtained in nanoscale size, when millimeter-scale crystals formed without poly(acrylic acid). Polymeric additives that could form specific interactions with crystallizing compounds seem to be useful tools for the phase and size control of pharmaceutical crystals.

  11. A Neat Trick Using Oxalic Acid Dihydrate and Potassium Permanganate and Other Experiments with Small Organic Amine or Oxygenated Compounds

    ERIC Educational Resources Information Center

    Kelland, Malcolm A.

    2011-01-01

    Solid potassium permanganate (KMnO[subscript 4]) is shown to react in a variety of ways with small organic amines or oxygenated compounds depending on whether they are liquids or solids and whether water is present. In particular, its reaction with solid oxalic acid dihydrate can be initiated by the moisture in one's breath, making an intriguing…

  12. Impact of oxalic acid on rumen function and bacterial community in sheep.

    PubMed

    Belenguer, A; Ben Bati, M; Hervás, G; Toral, P G; Yáñez-Ruiz, D R; Frutos, P

    2013-06-01

    Oxalic acid (OA) is a secondary compound occurring in a wide range of plants consumed by ruminants, especially in saline lands or in arid and semi-arid regions. However, its impact on the rumen microbial community and its changes over time, as well as the potential consequences on ruminal function, remain unknown. To examine this impact, five ewes fitted with a ruminal cannula and fed low-quality grass hay were dosed daily with 0.6 mmol of OA/kg body weight through the cannula for 14 days. On days 0 (before the start), 4, 7 and 14 of the administration period, samples of ruminal digesta were collected throughout the day (0, 3, 6 and 9 h after the morning feeding) for analysis of the bacterial community and fermentation parameters (pH, ammonia and volatile fatty acid (VFA) concentrations). In addition, two feedstuffs were incubated in situ using the nylon bag technique to estimate ruminal degradation. Terminal restriction fragment length polymorphism was employed to monitor the dynamics of total bacteria, and quantitative real-time PCR was used to investigate the abundance of the oxalate-degrading Oxalobacter formigenes. Neither pH nor total VFA concentrations were affected. Nevertheless, OA dosing altered molar proportions of most individual VFA and ammonia concentrations (P < 0.001). The dry matter disappearance of alfalfa hay was reduced on days 7 and 14 and that of barley straw only on day 7 (P < 0.01). These slight changes were related to others observed in the relative frequency of a number of terminal restriction fragments. Variations in the ruminal microbiota occurred rapidly with OA administration, which did not modify the bacterial diversity significantly but altered the structure of the community. However, many of these changes were reversed by the end of the experiment, with no significant differences between days 0 and 14 of dosing. These results suggest a rapid adaptation of the rumen bacterial community linked to the estimated increase in the

  13. Theoretical study on stable small clusters of oxalic acid with ammonia and water.

    PubMed

    Weber, Kevin H; Liu, Qian; Tao, Fu-Ming

    2014-02-27

    Thermodynamically stable small clusters of oxalic acid (CO2H)2, ammonia (NH3), and water (H2O) are studied through quantum chemical calculations. The (CO2H)2-NH3 core system with up to three waters of hydration was examined by B3LYP density functional theory and MP2 molecular orbital theory with the aug-cc-pVDZ basis set. The (CO2H)2-NH3 core complexes are observed to hydrogen bond strongly and should be found in appreciably significant concentrations in the atmosphere. Subsequent hydration of the (CO2H)2-NH3 core, however, is found to be somewhat prohibitive under ambient conditions. Relative populations of the examined clusters are predicted and the binding patterns detailed. Atmospheric implications related to new particle formations are discussed.

  14. Oxalic Acid from Lentinula edodes Culture Filtrate: Antimicrobial Activity on Phytopathogenic Bacteria and Qualitative and Quantitative Analyses

    PubMed Central

    Kwak, A-Min; Lee, In-Kyoung; Lee, Sang-Yeop

    2016-01-01

    The culture filtrate of Lentinula edodes shows potent antimicrobial activity against the plant pathogenic bacteria Ralstonia solanacearum. Bioassay-guided fractionation was conducted using Diaion HP-20 column chromatography, and the insoluble active compound was not adsorbed on the resin. Further fractionation by high-performance liquid chromatography (HPLC) suggested that the active compounds were organic acids. Nine organic acids were detected in the culture filtrate of L. edodes; oxalic acid was the major component and exhibited antibacterial activity against nine different phytopathogenic bacteria. Quantitative analysis by HPLC revealed that the content of oxalic acid was higher in the water extract from spent mushroom substrate than in liquid culture. This suggests that the water extract of spent L. edodes substrate is an eco-friendly control agent for plant diseases. PMID:28154495

  15. Improvement of the fermentability of oxalic acid hydrolysates by detoxification using electrodialysis and adsorption.

    PubMed

    Jeong, So-Yeon; Trinh, Ly Thi Phi; Lee, Hong-Joo; Lee, Jae-Won

    2014-01-01

    A two-step detoxification process consisting of electrodialysis and adsorption was performed to improve the fermentability of oxalic acid hydrolysates. The constituents of the hydrolysate differed significantly between mixed hardwood and softwood. Acetic acid and furfural concentrations were high in the mixed hardwood, whereas 5-hydroxymethylfurfural (HMF) concentration was relatively low compared with that of the mixed softwood. The removal efficiency of acetic acid reached 100% by electrodialysis (ED) process in both hydrolysates, while those of furfural and HMF showed very low, due to non-ionizable properties. Most of the remaining inhibitors were removed by XAD-4 resin. In the mixed hardwood hydrolysate without removal of the inhibitors, ethanol fermentation was not completed. Meanwhile, both ED-treated hydrolysates successfully produced ethanol with 0.08 and 0.15 g/Lh ethanol productivity, respectively. The maximum ethanol productivity was attained after fermentation with 0.27 and 0.35 g/Lh of detoxified hydrolysates, which were treated by ED, followed by XAD-4 resin.

  16. Suppression of Growth Rate of Colony-Associated Fungi by High Fructose Corn Syrup Feeding Supplement, Formic Acid, and Oxalic Acid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Select colony-associated fungi (bee isolates). Absidia sp., Ascosphaera apis, Aspergillus flavus, Fusarium sp., Penicillium glabrum, Mucor sp., showed a 40% reduction in radial growth rate with formic acid, a 28% reduction with oxalic acid, and a 15% reduction with fructose and high fructose corn sy...

  17. Determination of oxalate in black liquor by headspace gas chromatography.

    PubMed

    Li, Hailong; Chai, Xin-Sheng; DeMartini, Nikolai; Zhan, Huaiyu; Fu, Shiyu

    2008-05-30

    This study demonstrated a headspace gas chromatographic method (HS-GC) for the determination of oxalate content in black liquor (alkaline aqueous solution of inorganic chemicals and dissolved wood species from the alkaline pulping of wood). The method described in this paper is based on the reaction between oxalic and manganese dioxide in an acidic medium, in which oxalic acid is converted to carbon dioxide that is measured with a GC using a thermal conductivity detector. The challenge in developing this method was ensuring complete conversion of oxalic acid while minimizing the contribution of side reactions between carbohydrates, lignin and manganese dioxide to the carbon dioxide measured. It was found that a complete conversion of oxalate to carbon dioxide can be achieved within 3 min at a temperature of 70 degrees C; a MnO(2):C(oxalate) (concentration of H(2)C(2)O(4)+HC(2)O(4)(-)+C(2)O(4)(2-)) mole ratio of 60 and H(2)SO(4) concentration of 0.005-0.01 mol/L in the headspace vial. The method can detect concentrations as low as 0.39 microg of oxalate. The standard deviation was found to be 7% while recovery experiments with black liquor showed recoveries of 93-108% which were deemed acceptable for analysis of oxalate in an industrial sample such as black liquor.

  18. Mineralization of the recalcitrant oxalic and oxamic acids by electrochemical advanced oxidation processes using a boron-doped diamond anode.

    PubMed

    Garcia-Segura, Sergi; Brillas, Enric

    2011-04-01

    Oxalic and oxamic acids are the ultimate and more persistent by-products of the degradation of N-aromatics by electrochemical advanced oxidation processes (EAOPs). In this paper, the kinetics and oxidative paths of these acids have been studied for several EAOPs using a boron-doped diamond (BDD) anode and a stainless steel or an air-diffusion cathode. Anodic oxidation (AO-BDD) in the presence of Fe(2+) (AO-BDD-Fe(2+)) and under UVA irradiation (AO-BDD-Fe(2+)-UVA), along with electro-Fenton (EF-BDD), was tested. The oxidation of both acids and their iron complexes on BDD was clarified by cyclic voltammetry. AO-BDD allowed the overall mineralization of oxalic acid, but oxamic acid was removed much more slowly. Each acid underwent a similar decay in AO-BDD-Fe(2+) and EF-BDD, as expected if its iron complexes were not attacked by hydroxyl radicals in the bulk. The faster and total mineralization of both acids was achieved in AO-BDD-Fe(2+)-UVA due to the high photoactivity of their Fe(III) complexes that were continuously regenerated by oxidation of their Fe(II) complexes. Oxamic acid always released a larger proportion of NH(4)(+) than NO(3)(-) ion, as well as volatile NO(x) species. Both acids were independently oxidized at the anode in AO-BDD, but in AO-BDD-Fe(2+)-UVA oxamic acid was more slowly degraded as its content decreased, without significant effect on oxalic acid decay. The increase in current density enhanced the oxidation power of the latter method, with loss of efficiency. High Fe(2+) contents inhibited the oxidation of Fe(II) complexes by the competitive oxidation of Fe(2+) to Fe(3+). Low current densities and Fe(2+) contents are preferable to remove more efficiently these acids by the most potent AO-BDD-Fe(2+)-UVA method.

  19. Thermodynamical and structural study of protactinium(V) oxalate complexes in solution.

    PubMed

    Mendes, Mickaël; Hamadi, Séna; Le Naour, Claire; Roques, Jérôme; Jeanson, Aurélie; Den Auwer, Christophe; Moisy, Philippe; Topin, Sylvain; Aupiais, Jean; Hennig, Christoph; Di Giandomenico, Maria-Vita

    2010-11-01

    The complexation of protactinium(V) by oxalate was studied by X-ray absorption spectroscopy (XAS), density functional theory (DFT) calculations, capillary electrophoresis coupled with inductively coupled plasma mass spectrometry (CE-ICP-MS) and solvent extraction. XAS measurements showed unambiguously the presence of a short single oxo-bond, and the deduced structure agrees with theoretical calculations. CE-ICP-MS results indicated the formation of a highly charged anionic complex. The formation constants of PaO(C(2)O(4))(+), PaO(C(2)O(4))(2)(-), and PaO(C(2)O(4))(3)(3-) were determined from solvent extraction data by using protactinium at tracer scale (C(Pa) < 10(-10) M). Complexation reactions of Pa(V) with oxalate were found to be exothermic with relatively high positive entropic variation.

  20. Oxalic acid-assisted combustion synthesized LiVO3 cathode material for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Jian, X. M.; Wenren, H. Q.; Huang, S.; Shi, S. J.; Wang, X. L.; Gu, C. D.; Tu, J. P.

    2014-01-01

    LiVO3 materials are synthesized by combustion method with oxalic acid as fuel. Owing to its relatively low crystallization and small particle size, the LiVO3 calcined at 450 °C for 2 h displays optimal electrochemical performances, delivering a high discharge capacity of 298.4 mAh g-1 and 262.5 mAh g-1 between 1.0 and 3.5 V at a current density of 50 mA g-1 and 500 mA g-1 respectively, and exhibiting good cyclic stability. In this work, the chemical diffusion coefficient of Li+ (DLi+) in the LiVO3 electrode is determined by electrochemical impedance spectroscopy (EIS) and galvanostatic intermittent titration technique (GITT). The value calculated by EIS is in the range of 10-9-10-8 cm2 s-1, while it calculated by GITT is 10-9.5-10-8 cm2 s-1.

  1. Synthesis, growth, optical and mechanical studies of ferroelectric urea-oxalic acid single crystals

    NASA Astrophysics Data System (ADS)

    Vizhi, R. Ezhil; Dhivya, R.; Babu, D. Rajan

    2016-10-01

    A single crystal of urea oxalic acid was grown by slow evaporation method. The lattice parameters are a=5.13 Å, b=12.48 Å, c=7.07 Å, β=98.13° with V=448.5 Å3 which belongs to monoclinic system with space group P21/c obtained from single crystal X-ray diffraction analysis. UV-visible spectrum was recorded from the wavelength region of 200-800 nm and its cutoff wavelength was found to be 270 nm. Optical energy band gap of 4.57 eV was determined using Tau's plot relation. Fourier transform infrared vibrational spectrum confirmed the presence of N-H asymmetric stretching which occurs at 3444 cm-1 and 1853 cm-1 arising due to the amide C=O symmetric stretching. The emission was observed at 364 nm from the photoluminescence spectrum. The mechanical stability of the grown crystal was estimated by Vickers microhardness studies and it is evident that the grown crystal belongs to soft material category. Hardness related parameters such as elastic stiffness constant, fracture mechanics, brittleness index and yield strength were also evaluated. The dielectric constant and dielectric loss of the grown crystal were carried out as a function of frequency for different temperatures.

  2. Non-enzymatic oxalic acid sensor using platinum nanoparticles modified on graphene nanosheets.

    PubMed

    Chen, Xiaomei; Cai, Zhixiong; Huang, Zhiyong; Oyama, Munetaka; Jiang, Yaqi; Chen, Xi

    2013-07-07

    An enzyme-free oxalic acid (OA) electrochemical sensor was assembled using a platinum nanoparticle-loaded graphene nanosheets (PtNPGNs)-modified electrode. The PtNPGNs, with a high yield of PtNPs dispersed on the graphene nanosheets, were successfully achieved by a green, rapid, one-step and template-free method. The resulting PtNPGNs were characterized by transmission electron microscopy (TEM), high-resolution TEM, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and an X-ray diffraction technique. Electrochemical oxidation of OA on the PtNPGNs-modified electrode was investigated by cyclic voltammetry and differential pulse voltammetry methods. Based on the results, the modified electrode exhibited high electrochemical activity with well-defined peaks of OA oxidation and a notably decreased overpotential compared to the bare or even the GNs-modified electrode. Under optimized conditions, a good linear response was observed for the concentration of OA and its current response was in the range of 0.1-15 mM and 15-50 mM with a detection limit (S/N = 3) of 10 μM. Furthermore, the electrochemical sensor presented good characteristics in terms of stability and reproducibility, promising the applicability of the sensor in practical analysis.

  3. Fermentation parameter optimization of microbial oxalic acid production from cashew apple juice.

    PubMed

    Betiku, Eriola; Emeko, Harrison A; Solomon, Bamidele O

    2016-02-01

    The potential of cashew apple juice (CAJ) as a carbon source for oxalic acid (OA) production via fermentation process was investigated in this study. The effects and interactions of CAJ concentration, time, pH, NaNO3 concentration and methanol concentration on OA production were determined in a central composite design (CCD) and the process was modelled and optimized using response surface methodology (RSM). The results showed that OA fermentation can be described significantly (p < 0.05) by a quadratic model giving regression coefficient (R (2)) of 0.9964. NaNO3 concentration was the most significant positive variable while methanol was not a significant variable. A maximum OA concentration of 122.68 g/l could be obtained using the optimum levels of CAJ of 150.0 g/l, pH of 5.4, time of 7.31 days, NaNO3 of 2 g/l and methanol of 1% volume. The production of OA was found to increase from 106.75 to 122.68 g/l using the statistically design optimization. This study revealed that CAJ could serve as an inexpensive and abundant feedstock for fermentative OA production, the resulting model could be used in the design of a typical pilot plant for a scale up production.

  4. Esophageal mucosa exfoliation induced by oxalic acid poisoning: A case report

    PubMed Central

    WANG, JIERU; KAN, BAOTIAN; JIAN, XIANGDONG; WU, XIAOPENG; YU, GUANCAI; SUN, JING

    2016-01-01

    This study reports the case of a 44-year-old woman with oral oxalic acid poisoning. As the illness progressed, the patient exhibited severe metabolic acidosis, large-area esophageal mucosa injury and acute kidney injury, which required dialysis. A guide wire slipped out of position during the process of hemodialysis and moved back and forth in the veins, but was removed successfully by interventional endovascular treatment. However, the patient's esophageal mucosa exfoliated, which lead to severe benign esophageal stenosis and dysphagia. Balloon distention was conducted twice in the upper digestive tract using X-ray location in combination with a dumb-bell bladder and interventional wire. The patient exhibited convulsions, shock, embolism and loss of consciousness while undergoing the second balloon distention procedure. Following symptomatic treatment, the patient eventually remained in a stable condition, the digestive tract expansion procedure was not resumed and a jejunostomy was performed in order to facilitate enteral nutrition, which was administered via the jejunum and had little stimulatory effect on the pancreas. Following various treatments, the patient's condition improved markedly, with renal function returning to normal. PMID:26889241

  5. Atmospheric oxalic acid and related secondary organic aerosols in Qinghai Lake, a continental background site in Tibet Plateau

    NASA Astrophysics Data System (ADS)

    Meng, Jingjing; Wang, Gehui; Li, Jianjun; Cheng, Chunlei; Cao, Junji

    2013-11-01

    Summertime PM2.5 aerosols collected from Qinghai Lake (3200 m a.s.l.), a remote continental site in the northeastern part of Tibetan Plateau, were analyzed for dicarboxylic acids (C2-C11), ketocarboxylic acids and α-dicarbonyals. Oxalic acid (C2) is the dominant dicarboxylic acid in the samples, followed by malonic, succinic and azelaic acids. Total dicarboxylic acids (231 ± 119 ng m-3), ketocarboxylic acids (8.4 ± 4.3 ng m-3), and α-dicarbonyls (2.7 ± 2.1 ng m-3) at the Tibetan background site are 2-5 times less than those detected in lowland areas such as 14 Chinese megacities. Compared to those in other urban and marine areas enhancements in relative abundances of C2/total diacids and diacids-C/WSOC of the PM2.5 samples suggest that organic aerosols in the region are more oxidized due to strong solar radiation. Molecular compositions and air mass trajectories demonstrate that the above secondary organic aerosols in the Qinghai Lake atmosphere are largely derived from long-range transport. Ratios of oxalic acid, glyoxal and methylglyoxal to levoglucosan in PM2.5 aerosols emitted from household burning of yak dung, a major energy source for Tibetan in the region, are 30-400 times lower than those in the ambient air, which further indicates that primary emission from biomass burning is a negligible source of atmospheric oxalic acid and α-dicarbonyls at this background site.

  6. Comparison of hot hydroxylamine hydrochloride and oxalic acid leaching of stream sediment and coated rock samples as anomaly enhancement techniques

    USGS Publications Warehouse

    Filipek, L.H.; Chao, T.T.; Theobald, P.K.

    1982-01-01

    A hot hydroxylamine hydrochloride (H-Hxl) extraction in 25% acetic acid is compared with the commonly used oxalic acid extraction as a method of anomaly enhancement for Cu and Zn in samples from two very different metal deposits and climatic environments. Results obtained on minus-80-mesh stream sediments from an area near the Magruder massive sulfide deposit in Lincoln County, Georgia, where the climate is humid subtropical, indicate that H-Hxl enhances the anomaly for Cu by a factor of 2 and for Zn by a factor of 1.5, compared to the oxalic method. Analyses of Fe oxide-coated rock samples from outcrops overlying the North Silver Bell porphyry copper deposit near Tucson, Arizona, where the climate is semi-arid to arid, indicate that both techniques effectively outline the zones of hydrothermal alteration. The H-Hxl extraction can also perform well in high-carbonate or high-clay environments, where other workers have suggested that oxalic acid is not very effective. Therefore, the H-Hxl method is recommended for general exploration use. ?? 1982.

  7. The effect of natural iron oxide and oxalic acid on the photocatalytic degradation of isoproturon: a kinetics and analytical study.

    PubMed

    Boucheloukh, H; Remache, W; Parrino, F; Sehili, T; Mechakra, H

    2017-03-27

    The photocatalytic degradation of isoproturon, a persistent toxic herbicide, was investigated in the presence of natural iron oxide and oxalic acid and under UV irradiation. The influence of the relevant parameters such as the pH and the iron oxide and oxalic acid concentrations has been studied. The presence of natural iron oxide and oxalic acid in the system effectively allow the degradation of isoproturon, whereas the presence of t-butyl alcohol adversely affects the phototransformation of the target pollutant, thus indicating that an OH radical initiated the degradation mechanism. The degradation mechanism of isoproturon was investigated by means of GC-MS analysis. Oxidation of both the terminal N-(CH3)2 and isopropyl groups is the initial process leading to N-monodemethylated (NHCH3), N-formyl (N(CH3)CHO), and CHCH3OH as the main intermediates. The substitution of the isopropyl group by an OH group is also observed as a side process.

  8. Sequential electrokinetic treatment and oxalic acid extraction for the removal of Cu, Cr and As from wood.

    PubMed

    Isosaari, Pirjo; Marjavaara, Pieti; Lehmus, Eila

    2010-10-15

    Removal of Cu, Cr and As from utility poles treated with chromated copper arsenate (CCA) was investigated using different one- to three-step combinations of oxalic acid extraction and electrokinetic treatment. The experiments were carried out at room temperature, using 0.8% oxalic acid and 30 V (200 V/m) of direct current (DC) or alternating current in combination (DC/AC). Six-hour extraction removed only 15%, 11% and 28% and 7-day electrokinetic treatment 57%, 0% and 17% of Cu, Cr and As from wood chips, respectively. The best combination for all the metals was a three-step process consisting of pre-extraction, electrokinetics and post-extraction steps, yielding removals of 67% for Cu, 64% for Cr and 81% for As. Oxalic acid extraction prior to electrokinetic treatment was deleterious to further removal of Cu, but it was necessary for Cr and As removal. Chemical equilibrium modelling was used to explain the differences in the behaviour of Cu, Cr and As. Due to the dissimilar nature of these metals, it appeared that even more process sequences and/or stricter control of the process conditions would be needed to obtain the >99% removals required for safe recycling of the purified wood material.

  9. Efficient electron-induced removal of oxalate ions and formation of copper nanoparticles from copper(II) oxalate precursor layers

    PubMed Central

    Rückriem, Kai; Grotheer, Sarah; Vieker, Henning; Penner, Paul; Beyer, André; Gölzhäuser, Armin

    2016-01-01

    Summary Copper(II) oxalate grown on carboxy-terminated self-assembled monolayers (SAM) using a step-by-step approach was used as precursor for the electron-induced synthesis of surface-supported copper nanoparticles. The precursor material was deposited by dipping the surfaces alternately in ethanolic solutions of copper(II) acetate and oxalic acid with intermediate thorough rinsing steps. The deposition of copper(II) oxalate and the efficient electron-induced removal of the oxalate ions was monitored by reflection absorption infrared spectroscopy (RAIRS). Helium ion microscopy (HIM) reveals the formation of spherical nanoparticles with well-defined size and X-ray photoelectron spectroscopy (XPS) confirms their metallic nature. Continued irradiation after depletion of oxalate does not lead to further particle growth giving evidence that nanoparticle formation is primarily controlled by the available amount of precursor. PMID:27547602

  10. An improved thermodynamic model for the complexation of trivalent actinides and lanthanide with oxalic acid valid to high ionic strength.

    DOE PAGES

    Xiong, Yongliang; Thakur, Punam; Borkowski, Marian

    2015-07-30

    The dissociation constants of oxalic acid (Ox), and the stability constants of Am3+, Cm3+ and Eu3+ with Ox2– have been determined at 25 °C, over a range of concentration varying from 0.1 to 6.60 m NaClO4 using potentiometric titration and extraction techniques, respectively. The experimental data support the formation of complexes, M(Ox)n3 – 2n, where (M = Am3+, Cm3+ and Eu3+ and n = 1 and 2). The dissociation constant and the stability constant values measured as a function of NaClO4 concentration were used to estimate the Pitzer parameters for the respective interactions of Am3+, Cm3+ and Eu3+ with Ox.more » Furthermore, the stability constants data of Am3+ –Ox measured in NaClO4 and in NaCl solutions from the literature were simultaneously fitted in order to refine the existing actinide–oxalate complexation model that can be used universally in the safety assessment of radioactive waste disposal. The thermodynamic stability constant: log β0101 = 6.30 ± 0.06 and log β0102 = 10.84 ± 0.06 for Am3+ was obtained by simultaneously fitting data in NaCl and NaClO4 media. Additionally, log β0101 = 6.72 ± 0.08 and log β0102 = 11.05 ± 0.09 for the Cm3+ and log β0101 = 6.67 ± 0.08 and log β0102 = 11.15 ± 0.09 for the Eu3+ were calculated by extrapolation of data to zero ionic strength in NaClO4 medium only. For all stability constants, the Pitzer model gives an excellent representation of the data using interaction parameters β(0), β(1), and CΦ determined in this work. The thermodynamic model developed in this work will be useful in accurately modeling the potential solubility of trivalent actinides and early lanthanides to ionic strength of 6.60 m in low temperature environments in the presence of Ox. Furthermore, the work is also applicable to the accurate modeling transport of rare earth elements in various environments under the surface conditions.« less

  11. Thermal degradation of aqueous oxalate species

    SciTech Connect

    Crossey, L.J. )

    1991-06-01

    The aqueous thermal degradation of oxalic acid (a naturally occurring dicarboxylic acid) and its anions has been examined experimentally under variable conditions of temperature (160-230C), time (24-96 h), buffered pH (4-7), and ionic strength (0.2-0.5 M). Decomposition of oxalate species follows a first-order rate law. Degradation rate increases with decreasing pH; the effects of ionic strength are not significant. Changes in reaction rate over the temperature range studied give activation energies that range from 29-50 kcal/mol over a starting solution pH range of 5-7. Extrapolation of these data to sedimentary basin temperatures suggests that oxalate species may be long-lived in formation waters. At 80C, half-lives range from 2,500 to 28,000 years at pH values of 5 and 7, respectively. Formate species are relatively stable degradation products over the range of conditions studied. Comparison of these data are relatively stable degradation products over the range of conditions studied. Comparison of these data with results of other thermal degradation studies of carboxylic acids and their anions indicate that acetate stability {much gt} formate stability > oxalate stability > gallate and malonate stability. These results are consistent with the high concentrations of acetate relative to oxalate and malonate observed in formation waters.

  12. Literature review for oxalate oxidation processes and plutonium oxalate solubility

    SciTech Connect

    Nash, C. A.

    2015-10-01

    A literature review of oxalate oxidation processes finds that manganese(II)-catalyzed nitric acid oxidation of oxalate in precipitate filtrate is a viable and well-documented process. The process has been operated on the large scale at Savannah River in the past, including oxidation of 20 tons of oxalic acid in F-Canyon. Research data under a variety of conditions show the process to be robust. This process is recommended for oxalate destruction in H-Canyon in the upcoming program to produce feed for the MOX facility. Prevention of plutonium oxalate precipitation in filtrate can be achieved by concentrated nitric acid/ferric nitrate sequestration of oxalate. Organic complexants do not appear practical to sequester plutonium. Testing is proposed to confirm the literature and calculation findings of this review at projected operating conditions for the upcoming campaign.

  13. Light-induced multiphase chemistry of gas phase ozone on aqueous pyruvic and oxalic acids: Aerosol chamber study

    NASA Astrophysics Data System (ADS)

    Gligorovski, S.; Grgic, I.; Net, S.; Böge, O.; Iinuma, Y.; Kahnt, A.; Scheinhardt, S.; Herrmann, H.; Wortham, H.

    2010-12-01

    The light-absorbing organic compounds present in and on condensed aerosol particles interacting with trace gases such as ozone can initiate a new and potentially important photo-induced multiphase chemistry. However, investigations of light induced multiphase processes are very scarce at present. We have launched the idea of pyruvic acid (PA) acting as a photosensitizer in the multiphase reactions between gas-phase ozone and aqueous oxalic acid (OA). The performed photochemical batch experiments yielded a complex suite of organic molecules which resulted primarily from the oligomerization of OA/PA and subsequent reactions, including decarboxylation and cycloadition (Grgic et al., 2010). In the atmosphere, pyruvic acid will always be accompanied by other carboxylic acids (and also other organics) which are constituents of either aerosol particles or aqueous droplets the effects of a possible photochemistry triggered by pyruvic acid should be experimentally studied in depth and under natural conditions as far as possible. Hence, in a very recent study experiments in the aerosol chamber facility LEAK at IFT, Leipzig, were performed to verify the influence of pyruvic on the multiphase (photo)oxidation of oxalic acid. The aim of these experiments was to study the multiphase photo-induced oxidation reactions with airborne deliquescent particles to demonstrate the applicability of the reactions mentioned above under more realistic conditions than in a batch reactor. State of the art sampling and analytical tools were applied for the analysis of the ongoing chamber runs and the formed particulate products which include denuder sampling, carbonyl compound derivatisation, PTR-MS measurements, GC-MS measurements and HPLC-MS and CE-MS for the particle phase. First results from these joint complex chamber experiments will be presented and discussed. Reference: Grgić I., Nieto-Gligorovski L.I., Net S., Temime-Roussel B., Gligorovski S., Wortham H. Light induced multiphase

  14. Beta-alanine-oxalic acid (1:1) hemihydrate crystal: structure, 13C NMR and vibrational properties, protonation character.

    PubMed

    Godzisz, D; Ilczyszyn, M; Ilczyszyn, M M

    2003-03-01

    The crystal structure of beta-alanine-oxalic acid (1:1) hemihydrate complex has been reinvestigated by X-ray diffraction method at 293 K. Formation of monoclinic crystal system belonging to C2/c space group and consisting of semi-oxalate chains, diprotonated beta-alanine dimers and water molecules bonded to both these units is confirmed. New results are obtained for distances in the carboxylic groups and hydrogen bonds. These structural observations are used for protonation degree monitoring on the carboxylic oxygen atoms. They are in accordance with our vibrational study. The 13C NMR spectra provide insights into the solid structure of this complex, character of its hydrogen bonds and the beta-alanine protonation.

  15. ACTUAL-WASTE TESTS OF ENHANCED CHEMICAL CLEANING FOR RETRIEVAL OF SRS HLW SLUDGE TANK HEELS AND DECOMPOSITION OF OXALIC ACID

    SciTech Connect

    Martino, C.; King, W.; Ketusky, E.

    2012-01-12

    Savannah River National Laboratory conducted a series of tests on the Enhanced Chemical Cleaning (ECC) process using actual Savannah River Site waste material from Tanks 5F and 12H. Testing involved sludge dissolution with 2 wt% oxalic acid, the decomposition of the oxalates by ozonolysis (with and without the aid of ultraviolet light), the evaporation of water from the product, and tracking the concentrations of key components throughout the process. During ECC actual waste testing, the process was successful in decomposing oxalate to below the target levels without causing substantial physical or chemical changes in the product sludge.

  16. Adsorption and photodegradation of methylene blue by iron oxide impregnated on granular activated carbons in an oxalate solution

    NASA Astrophysics Data System (ADS)

    Kadirova, Zukhra C.; Katsumata, Ken-ichi; Isobe, Toshihiro; Matsushita, Nobuhiro; Nakajima, Akira; Okada, Kiyoshi

    2013-11-01

    The photocatalytic adsorbents BAU-OA, BAU-CL and BAU-HA with varying iron oxide content (9-10 mass%) were prepared by heat treatment at 250 °C from commercial activated carbon (BAU) impregnated with iron oxalate, chloride, tris-benzohydroxamate, respectively. The XRD patterns showed amorphous structure in the BAU-CL sample (SBET 50 m2/g) and low crystallinity (as FeOOH and Fe2O3 phases) in the BAU-HA and BAU-OA samples (SBET 4 and 111 m2/g, respectively). The methylene blue adsorption capacities was decreased in order of BAU-OA < BAU-CL < BAU-HA sample and the adsorption followed Langmuir model. The apparent MB photodegradation rate constant (kapp) was increased in same order BAU-HA < BAU-CL < BAU-OA under the standard experimental conditions (initial MB concentrations 0.015-0.025 mM; sample content - 10 mg/l; initial oxalic acid concentration - 0.43 mM; pH 3-4; UV illumination). The process included high efficiency combination of adsorption, heterogeneous and homogeneous catalysis under UV and solar lights illumination without addition of hydrogen peroxide. The detoxification of water sample containing organic dyes was confirmed after combined sorption-photocatalytic treatment.

  17. Oxalic acid and diacylglycerol 36:3 are cross-species markers of sleep debt.

    PubMed

    Weljie, Aalim M; Meerlo, Peter; Goel, Namni; Sengupta, Arjun; Kayser, Matthew S; Abel, Ted; Birnbaum, Morris J; Dinges, David F; Sehgal, Amita

    2015-02-24

    Sleep is an essential biological process that is thought to have a critical role in metabolic regulation. In humans, reduced sleep duration has been associated with risk for metabolic disorders, including weight gain, diabetes, obesity, and cardiovascular disease. However, our understanding of the molecular mechanisms underlying effects of sleep loss is only in its nascent stages. In this study we used rat and human models to simulate modern-day conditions of restricted sleep and addressed cross-species consequences via comprehensive metabolite profiling. Serum from sleep-restricted rats was analyzed using polar and nonpolar methods in two independent datasets (n = 10 per study, 3,380 measured features, 407 identified). A total of 38 features were changed across independent experiments, with the majority classified as lipids (18 from 28 identified). In a parallel human study, 92 metabolites were identified as potentially significant, with the majority also classified as lipids (32 of 37 identified). Intriguingly, two metabolites, oxalic acid and diacylglycerol 36:3, were robustly and quantitatively reduced in both species following sleep restriction, and recovered to near baseline levels after sleep restriction (P < 0.05, false-discovery rate < 0.2). Elevated phospholipids were also noted after sleep restriction in both species, as well as metabolites associated with an oxidizing environment. In addition, polar metabolites reflective of neurotransmitters, vitamin B3, and gut metabolism were elevated in sleep-restricted humans. These results are consistent with induction of peroxisome proliferator-activated receptors and disruptions of the circadian clock. The findings provide a potential link between known pathologies of reduced sleep duration and metabolic dysfunction, and potential biomarkers for sleep loss.

  18. Ascorbate metabolism and the developmental demand for tartaric and oxalic acids in ripening grape berries

    PubMed Central

    2009-01-01

    Background Fresh fruits are well accepted as a good source of the dietary antioxidant ascorbic acid (Asc, Vitamin C). However, fruits such as grapes do not accumulate exceptionally high quantities of Asc. Grapes, unlike most other cultivated fruits do however use Asc as a precursor for the synthesis of both oxalic (OA) and tartaric acids (TA). TA is a commercially important product in the wine industry and due to its acidifying effect on crushed juice it can influence the organoleptic properties of the wine. Despite the interest in Asc accumulation in fruits, little is known about the mechanisms whereby Asc concentration is regulated. The purpose of this study was to gain insights into Asc metabolism in wine grapes (Vitis vinifera c.v. Shiraz.) and thus ascertain whether the developmental demand for TA and OA synthesis influences Asc accumulation in the berry. Results We provide evidence for developmentally differentiated up-regulation of Asc biosynthetic pathways and subsequent fluctuations in Asc, TA and OA accumulation. Rapid accumulation of Asc and a low Asc to dehydroascorbate (DHA) ratio in young berries was co-ordinated with up-regulation of three of the primary Asc biosynthetic (Smirnoff-Wheeler) pathway genes. Immature berries synthesised Asc in-situ from the primary pathway precursors D-mannose and L-galactose. Immature berries also accumulated TA in early berry development in co-ordination with up-regulation of a TA biosynthetic gene. In contrast, ripe berries have up-regulated expression of the alternative Asc biosynthetic pathway gene D-galacturonic acid reductase with only residual expression of Smirnoff-Wheeler Asc biosynthetic pathway genes and of the TA biosynthetic gene. The ripening phase was further associated with up-regulation of Asc recycling genes, a secondary phase of increased accumulation of Asc and an increase in the Asc to DHA ratio. Conclusion We demonstrate strong developmental regulation of Asc biosynthetic, recycling and catabolic

  19. Influence of multi-step washing using Na2EDTA, oxalic acid and phosphoric acid on metal fractionation and spectroscopy characteristics from contaminated soil.

    PubMed

    Wei, Meng; Chen, Jiajun

    2016-11-01

    A multi-step soil washing test using a typical chelating agent (Na2EDTA), organic acid (oxalic acid), and inorganic weak acid (phosphoric acid) was conducted to remediate soil contaminated with heavy metals near an arsenic mining area. The aim of the test was to improve the heavy metal removal efficiency and investigate its influence on metal fractionation and the spectroscopy characteristics of contaminated soil. The results indicated that the orders of the multi-step washing were critical for the removal efficiencies of the metal fractions, bioavailability, and potential mobility due to the different dissolution levels of mineral fractions and the inter-transformation of metal fractions by XRD and FT-IR spectral analyses. The optimal soil washing options were identified as the Na2EDTA-phosphoric-oxalic acid (EPO) and phosphoric-oxalic acid-Na2EDTA (POE) sequences because of their high removal efficiencies (approximately 45 % for arsenic and 88 % for cadmium) and the minimal harmful effects that were determined by the mobility and bioavailability of the remaining heavy metals based on the metal stability (I R ) and modified redistribution index ([Formula: see text]).

  20. Recovery of zinc and manganese, and other metals (Fe, Cu, Ni, Co, Cd, Cr, Na, K) from Zn-MnO2 and Zn-C waste batteries: Hydroxyl and carbonate co-precipitation from solution after reducing acidic leaching with use of oxalic acid

    NASA Astrophysics Data System (ADS)

    Sobianowska-Turek, A.; Szczepaniak, W.; Maciejewski, P.; Gawlik-Kobylińska, M.

    2016-09-01

    The article discusses the current situation of the spent batteries and portable accumulators management. It reviews recycling technologies of the spent batteries and portable accumulators which are used in the manufacturing installations in the world. Also, it presents the authors' research results on the reductive acidic leaching of waste material of the zinc-carbon batteries (Zn-C) and zinc-manganese batteries (alkaline Zn-MnO2) delivered by a company dealing with mechanical treatment of this type of waste stream. The research data proved that the reductive acidic leaching (H2SO4 + C2H2O4) of the battery's black mass allows to recover 85.0% of zinc and 100% of manganese. Moreover, it was found that after the reductive acidic leaching it is possible to recover nearly 100% of manganese, iron, cadmium, and chromium, 98.0% of cobalt, 95.5% of zinc, and 85.0% of copper and nickel from the solution with carbonate method. On the basis of the results, it is possible to assume that the carbonate method can be used for the preparation of manganese-zinc ferrite.

  1. An improved thermodynamic model for the complexation of trivalent actinides and lanthanide with oxalic acid valid to high ionic strength.

    SciTech Connect

    Xiong, Yongliang; Thakur, Punam; Borkowski, Marian

    2015-07-30

    The dissociation constants of oxalic acid (Ox), and the stability constants of Am3+, Cm3+ and Eu3+ with Ox2– have been determined at 25 °C, over a range of concentration varying from 0.1 to 6.60 m NaClO4 using potentiometric titration and extraction techniques, respectively. The experimental data support the formation of complexes, M(Ox)n3 – 2n, where (M = Am3+, Cm3+ and Eu3+ and n = 1 and 2). The dissociation constant and the stability constant values measured as a function of NaClO4 concentration were used to estimate the Pitzer parameters for the respective interactions of Am3+, Cm3+ and Eu3+ with Ox. Furthermore, the stability constants data of Am3+ –Ox measured in NaClO4 and in NaCl solutions from the literature were simultaneously fitted in order to refine the existing actinide–oxalate complexation model that can be used universally in the safety assessment of radioactive waste disposal. The thermodynamic stability constant: log β0101 = 6.30 ± 0.06 and log β0102 = 10.84 ± 0.06 for Am3+ was obtained by simultaneously fitting data in NaCl and NaClO4 media. Additionally, log β0101 = 6.72 ± 0.08 and log β0102 = 11.05 ± 0.09 for the Cm3+ and log β0101 = 6.67 ± 0.08 and log β0102 = 11.15 ± 0.09 for the Eu3+ were calculated by extrapolation of data to zero ionic strength in NaClO4 medium only. For all stability constants, the Pitzer model gives an excellent representation of the data using interaction parameters β(0), β(1), and CΦ determined in this work. The thermodynamic model developed in this work will be useful in accurately modeling the potential solubility of trivalent

  2. Pre-harvest application of oxalic acid increases quality and resistance to Penicillium expansum in kiwifruit during postharvest storage.

    PubMed

    Zhu, Yuyan; Yu, Jie; Brecht, Jeffrey K; Jiang, Tianjia; Zheng, Xiaolin

    2016-01-01

    Kiwifruit (Actinidia deliciosa cv. Bruno) fruits were sprayed with 5mM oxalic acid (OA) at 130, 137, and 144 days after full blossom, and then harvested at commercial maturity [soluble solid content (SSC) around 10.0%] and stored at room temperature (20 ± 1 °C). Pre-harvest application of OA led to fruit with higher ascorbic acid content at harvest, slowed the decreases in fruit firmness and ascorbic acid content and increase in SSC during storage, and also decreased the natural disease incidence, lesion diameter, and patulin accumulation in fruit inoculated with Penicillium expansum, indicating that the OA treatment increased quality and induced disease resistance in kiwifruit. It was suggested that the increase in activities of defense-related enzymes and in levels of substances related to disease resistance might collectively contribute to resistance in kiwifruit against fungi such as P. expansum in storage.

  3. Synthesis and characterization of nanocrystalline nickel oxide using NaOH and oxalic acid as oxide sources

    NASA Astrophysics Data System (ADS)

    Sathishkumar, K.; Shanmugam, N.; Kannadasan, N.; Cholan, S.; Viruthagiri, G.

    2014-04-01

    Precursors of nickel oxide (NiO) nanoparticles were synthesized through a simple chemical precipitation method by changing the oxide source used for the synthesis. The synthesized precursors were subjected to thermo gravimetric analysis (TGA) to determine the temperature at which the precursors decompose into nickel oxide. The obtained results of TGA suggest that precursor NiO prepared using sodium hydroxide (NaOH) showed NiO formation at 600 °C, whereas, when oxalic acid was used as oxide source the formation of NiO took place at 400 °C. After calcinations of the precursors at respective temperatures, NiO nanocrystals have been harvested. The synthesized NiO powders were characterized by x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), photoluminescence (PL) spectroscopy, field emission scanning electron microscopy (FE-SEM), energy dispersive x-ray analysis (EDX), and vibrating sample magnetometer (VSM) analysis. An FE-TEM image of NiO prepared using oxalic acid showed spherical and elliptical particles with sizes in the range of 15 nm. The Williamson-Hall (W-H) plots were drawn for the annealed products to study their lattice strain and crystallite size. The sizes of NiO nanocrystals obtained from W-H analysis are well correlated with sizes estimated using Scherrer’s formula. The relatively low saturation magnetization of NiO confirms its super paramagnetic behavior.

  4. Biocontrol agents-mediated suppression of oxalic acid induced cell death during Sclerotinia sclerotiorum-pea interaction.

    PubMed

    Jain, Akansha; Singh, Akanksha; Singh, Surendra; Sarma, Birinchi Kumar; Singh, Harikesh Bahadur

    2015-05-01

    Oxalic acid (OA) is an important pathogenic factor during early Sclerotinia sclerotiorum-host interaction and might work by reducing hydrogen peroxide production (H2 O2 ). In the present investigation, oxalic acid-induced cell death in pea was studied. Pea plants treated with biocontrol agents (BCAs) viz., Pseudomonas aeruginosa PJHU15, Bacillus subtilis BHHU100, and Trichoderma harzianum TNHU27 either singly and/or in consortium acted on S. sclerotiorum indirectly by enabling plants to inhibit the OA-mediated suppression of oxidative burst via induction of H2 O2 . Our results showed that BCA treated plants upon treatment with culture filtrate of the pathogen, conferred the resistance via. significantly decreasing relative cell death of pea against S. sclerotiorum compared to control plants without BCA treatment but treated with the culture filtrate of the pathogen. The results obtained from the present study indicate that the microbes especially in consortia play significant role in protection against S. sclerotiorum by modulating oxidative burst and partially enhancing tolerance by increasing the H2 O2 generation, which is otherwise suppressed by OA produced by the pathogen.

  5. Degradation of oxalic acid by the mycoparasite Coniothyrium minitans plays an important role in interacting with Sclerotinia sclerotiorum.

    PubMed

    Zeng, Li-Mei; Zhang, Jing; Han, Yong-Chao; Yang, Long; Wu, Ming-de; Jiang, Dao-Hong; Chen, Weidong; Li, Guo-Qing

    2014-08-01

    Coniothyrium minitans (Cm) is a mycoparasite of the phytopathogenic fungus Sclerotinia sclerotiorum (Ss). Ss produces a virulence factor oxalic acid (OA) which is toxic to plants and also to Cm, and Cm detoxifies OA by degradation. In this study, two oxalate decarboxylase genes, Cmoxdc1 and Cmoxdc2, were cloned from Cm strain Chy-1. OA and low pH induced expression of Cmoxdc1, but not Cmoxdc2. Cmoxdc1 was partially responsible for OA degradation, whereas Cmoxdc2 had no effect on OA degradation. Disruption of Cmoxdc1 in Cm reduced its ability to infect Ss in dual cultures where OA accumulated. Compared with Chy-1, the Cmoxdc1-disrupted mutants had reduced expression levels of two mycoparasitism-related genes chitinase (Cmch1) and β-1,3-glucanase (Cmg1), and had no detectable activity of extracellular proteases in the presence of OA. On the other hand, the cultural filtrates of the Cmoxdc1-disrupted mutants in OA-amended media showed enhanced antifungal activity, possibly because of increased production of antifungal substances under acidic pH condition resulted from reduced Cmoxdc1-mediated OA degradation. This study provides direct genetic evidence of OA degradation regulating mycoparasitism and antibiosis of Cm against Ss, and sheds light on the sophisticated strategies of Cm in interacting with metabolically active mycelia and dormant sclerotia of Ss.

  6. Mode of Action: Oxalate Crystal-Induced Renal Tubule Degeneration and Glycolic Acid-Induced Dysmorphogenesis—Renal and Developmental Effects of Ethylene Glycol

    SciTech Connect

    Corley, Rick A.; Meek, M E.; Carney, E W.

    2005-10-01

    Ethylene glycol can cause both renal and developmental toxicity, with metabolism playing a key role in the mode of action (MOA) for each form of toxicity. Renal toxicity is ascribed to the terminal metabolite oxalic acid, which precipitates in the kidney in the form of calcium oxalate crystals and is believed to cause physical damage to the renal tubules. The human relevance of the renal toxicity of ethylene glycol is indicated by the similarity between animals and humans of metabolic pathways, the observation of renal oxalate crystals in toxicity studies in experimental animals and human poisonings, and cases of human kidney and bladder stones related to dietary oxalates and oxalate precursors. High-dose gavage exposures to ethylene glycol also cause axial skeletal defects in rodents (but not rabbits), with the intermediary metabolite, glycolic acid, identified as the causative agent. However, the mechanism by which glycolic acid perturbs development has not been investigated sufficiently to develop a plausible hypothesis of mode of action, nor have any cases of ethylene glycol-induced developmental effects been reported in humans. Given this, and the variations in sensitivity between animal species in response, the relevance to humans of ethylene glycol-induced developmental toxicity in animals is unknown at this time.

  7. Oxalate content of cereals and cereal products.

    PubMed

    Siener, Roswitha; Hönow, Ruth; Voss, Susanne; Seidler, Ana; Hesse, Albrecht

    2006-04-19

    Detailed knowledge of food oxalate content is of essential importance for dietary treatment of recurrent calcium oxalate urolithiasis. Dietary oxalate can contribute considerably to the amount of urinary oxalate excretion. Because cereal foods play an important role in daily nutrition, the soluble and total oxalate contents of various types of cereal grains, milling products, bread, pastries, and pasta were analyzed using an HPLC-enzyme-reactor method. A high total oxalate content (>50 mg/100 g) was found in whole grain wheat species Triticum durum (76.6 mg/100 g), Triticum sativum (71.2 mg/100 g), and Triticum aestivum (53.3 mg/100 g). Total oxalate content was comparably high in whole grain products of T. aestivum, that is, wheat flakes and flour, as well as in whole grain products of T. durum, that is, couscous, bulgur, and pasta. The highest oxalate content was demonstrated for wheat bran (457.4 mg/100 g). The higher oxalate content in whole grain than in refined grain cereals suggests that oxalic acid is primarily located in the outer layers of cereal grains. Cereals and cereal products contribute to the daily oxalate intake to a considerable extent. Vegetarian diets may contain high amounts of oxalate when whole grain wheat and wheat products are ingested. Recommendations for prevention of recurrence of calcium oxalate stone disease have to take into account the oxalate content of these foodstuffs.

  8. Prestorage oxalic acid treatment maintained visual quality, bioactive compounds, and antioxidant potential of pomegranate after long-term storage at 2 degrees C.

    PubMed

    Sayyari, Mohammad; Valero, Daniel; Babalar, Mesbah; Kalantari, Siamak; Zapata, Pedro J; Serrano, María

    2010-06-09

    Oxalic acid at three concentrations (2, 4, and 6 mM) was applied by dipping to pomegranate fruits of cv. Mollar de Elche, which were then stored for 84 days at 2 degrees C. Pomegranate is a chilling-sensitive fruit and, thus, control fruits exhibited chilling injury (CI) symptoms after long-term storage at 2 degrees C that were accompanied by increased respiration rate, weight loss, and electrolyte leakage (EL). The CI symptoms were significantly reduced by oxalic acid treatment, especially for the 6 mM concentration. In addition, control pomegranates showed significant reduction in the content of total phenolics and ascorbic acid as well as in total antioxidant activity (TAA), in both hydrophilic (H-TAA) and lipophilic (L-TAA) fractions. The application of oxalic acid led to lower losses of total phenolics and significant increase in both ascorbic acid content and H-TAA, whereas L-TAA remained unaffected. Thus, oxalic acid could be a promising postharvest treatment to alleviate CI and increase antioxidant potential.

  9. Oxaloacetate acetylhydrolase gene mutants of Sclerotinia sclerotiorum do not accumulate oxalic acid, but do produce limited lesions on host plants.

    PubMed

    Liang, Xiaofei; Liberti, Daniele; Li, Moyi; Kim, Young-Tae; Hutchens, Andrew; Wilson, Ron; Rollins, Jeffrey A

    2015-08-01

    The oxaloacetate acetylhydrolase (OAH, EC 3.7.1.1)-encoding gene Ss-oah1 was cloned and functionally characterized from Sclerotinia sclerotiorum. Ss-oah1 transcript accumulation mirrored oxalic acid (OA) accumulation with neutral pH induction dependent on the pH-responsive transcriptional regulator Ss-Pac1. Unlike previously characterized ultraviolet (UV)-induced oxalate-deficient mutants ('A' mutants) which retain the capacity to accumulate OA, gene deletion Δss-oah1 mutants did not accumulate OA in culture or during plant infection. This defect in OA accumulation was fully restored on reintroduction of the wild-type (WT) Ss-oah1 gene. The Δss-oah1 mutants were also deficient in compound appressorium and sclerotium development and exhibited a severe radial growth defect on medium buffered at neutral pH. On a variety of plant hosts, the Δss-oah1 mutants established very restricted lesions in which the infectious hyphae gradually lost viability. Cytological comparisons of WT and Δss-oah1 infections revealed low and no OA accumulation, respectively, in subcuticular hyphae. Both WT and mutant hyphae exhibited a transient association with viable host epidermal cells at the infection front. In summary, our experimental data establish a critical requirement for OAH activity in S. sclerotiorum OA biogenesis and pathogenesis, but also suggest that factors independent of OA contribute to the establishment of primary lesions.

  10. Actual-Waste Tests of Enhanced Chemical Cleaning for Retrieval of SRS HLW Sludge Tank Heels and Decomposition of Oxalic Acid - 12256

    SciTech Connect

    Martino, Christopher J.; King, William D.; Ketusky, Edward T.

    2012-07-01

    Savannah River National Laboratory conducted a series of tests on the Enhanced Chemical Cleaning (ECC) process using actual Savannah River Site waste material from Tanks 5F and 12H. Testing involved sludge dissolution with 2 wt% oxalic acid, the decomposition of the oxalates by ozonolysis (with and without the aid of ultraviolet light), the evaporation of water from the product, and tracking the concentrations of key components throughout the process. During ECC actual waste testing, the process was successful in decomposing oxalate to below the target levels without causing substantial physical or chemical changes in the product sludge. During ECC actual waste testing, the introduction of ozone was successful in decomposing oxalate to below the target levels. This testing did not identify physical or chemical changes in the ECC product sludge that would impact downstream processing. The results from these tests confirm observations made by AREVA NP during larger scale testing with waste simulants. This testing, however, had a decreased utilization of ozone, requiring approximately 5 moles of ozone per mole of oxalate decomposed. Decomposition of oxalates in sludge dissolved in 2 wt% OA to levels near 100 ppm oxalate using ECC process conditions required 8 to 12.5 hours without the aid of UV light and 4.5 to 8 hours with the aid of UV light. The pH and ORP were tracked during decomposition testing. Sludge components were tracked during OA decomposition, showing that most components have the highest soluble levels in the initial dissolved sludge and early decomposition samples and exhibit lower soluble levels as OA decomposition progresses. The Deposition Tank storage conditions that included pH adjustment to approximately 1 M free hydroxide tended to bring the soluble concentrations in the ECC product to nearly the same level for each test regardless of storage time, storage temperature, and contact with other tank sludge material. (authors)

  11. Contribution of calcium oxalate to soil-exchangeable calcium

    USGS Publications Warehouse

    Dauer, Jenny M.; Perakis, Steven S.

    2013-01-01

    Acid deposition and repeated biomass harvest have decreased soil calcium (Ca) availability in many temperate forests worldwide, yet existing methods for assessing available soil Ca do not fully characterize soil Ca forms. To account for discrepancies in ecosystem Ca budgets, it has been hypothesized that the highly insoluble biomineral Ca oxalate might represent an additional soil Ca pool that is not detected in standard measures of soil-exchangeable Ca. We asked whether several standard method extractants for soil-exchangeable Ca could also access Ca held in Ca oxalate crystals using spike recovery tests in both pure solutions and soil extractions. In solutions of the extractants ammonium chloride, ammonium acetate, and barium chloride, we observed 2% to 104% dissolution of Ca oxalate crystals, with dissolution increasing with both solution molarity and ionic potential of cation extractant. In spike recovery tests using a low-Ca soil, we estimate that 1 M ammonium acetate extraction dissolved sufficient Ca oxalate to contribute an additional 52% to standard measurements of soil-exchangeable Ca. However, in a high-Ca soil, the amount of Ca oxalate spike that would dissolve in 1 M ammonium acetate extraction was difficult to detect against the large pool of exchangeable Ca. We conclude that Ca oxalate can contribute substantially to standard estimates of soil-exchangeable Ca in acid forest soils with low soil-exchangeable Ca. Consequently, measures of exchangeable Ca are unlikely to fully resolve discrepancies in ecosystem Ca mass balance unless the contribution of Ca oxalate to exchangeable Ca is also assessed.

  12. Oxalic-acid leaching of rock, soil, and stream-sediment samples as an anomaly-accentuated technique

    USGS Publications Warehouse

    Alminas, Henry V.; Mosier, Elwin L.

    1976-01-01

    In many instances total-rock and sieved-soil and stream-sediment samples lack the sensitivity and contrast required for reconnaissance exploration and necessary in the search for blind ore deposits. Heavy-mineral concentrates incorporate the required sensitivity and contrast but are overly expensive for two reasons: time-consuming sample preparation is required to obtain them, and they cannot be easily derived from all bulk-sample types. Trace-metal-content comparisons of the oxalic-acid-leachable portions with heavy-mineral concentrates show that the leachates are equal to the heavy-mineral concentrates in sensitivity and contrast. Simplicity of preparation and the resultant cost savings are additional advantages of this proposed method.

  13. Structural variability in neptunium(V) oxalate compounds: synthesis and structural characterization of Na2NpO2(C2O4)OH.H2O.

    PubMed

    Bean, Amanda C; Garcia, Eduardo; Scott, Brian L; Runde, Wolfgang

    2004-10-04

    Reaction of a (237)Np(V) stock solution in the presence of oxalic acid, calcium chloride, and sodium hydroxide under hydrothermal conditions produces single crystals of a neptunium(V) oxalate, Na(2)NpO(2)(C(2)O(4))OH.H(2)O. The structure consists of one-dimensional chains running down the a axis and is the first example of a neptunium(V) oxalate compound containing hydroxide anions.

  14. The dissolution of quartz in dilute aqueous solutions of organic acids at 25°C

    USGS Publications Warehouse

    Bennett, P.C.; Melcer, M.E.; Siegel, D.I.; Hassett, J.P.

    1988-01-01

    The dissolution of quartz in dilute aqueous solutions of organic acids at 25° and standard pressure was investigated by the batch dissolution method. The bulk dissolution rate of quartz in 20 mmole/Kg citrate solutions at pH 7 was 8 to 10 times faster than that in pure water. After 1750 hours the concentration of dissolved silica in the citrate solution was 167 μmole/Kg compared to 50 μmole/Kg in water and a 20 mmole/Kg solution of acetate at pH 7. Solutions of salicylic, oxalic, and humic acids also accelerated the dissolution of quartz in aqueous solution at pH 7. The rate of dissolution in organic acids decreased sharply with decreasing pH.The possibility of a silica-organic acid complex was investigated using UV-difference spectroscopy. Results suggest that dissolved silica is complexed by citrate, oxalate and pyruvate at pH 7 by an electron-donor acceptor complex, whereas no complexation occurs between silica and acetate, lactate, malonate, or succinate. Three models are proposed for the solution and surface complexation of silica by organic acid anions which result in the accelerated dissolution and increased solubility of quartz in organic rich water.

  15. The dissolution of quartz in dilute aqueous solutions of organic acids at 25 degree C

    SciTech Connect

    Bennett, P.C.; Melcer, M.E.; Siegel, D.I.; Hassett, J.P. )

    1988-06-01

    The dissolution of quartz in dilute aqueous solutions of organic acids at 25{degree}C and standard pressure was investigated by the batch dissolution method. The bulk dissolution rate of quartz in 20 mmole/Kg citrate solutions at pH 7 was 8 to 10 times faster than that in pure water. After 1750 hours the concentration of dissolved silica in the citrate solution was 167 {mu}mole/Kg compared to 50 {mu}mole/Kg in water and a 20 mmole/Kg solution of acetate at pH 7. Solutions of salicylic, oxalic, and humic acids also accelerated the dissolution of quartz in aqueous solution at pH 7. The rate of dissolution in organic acids decreased sharply with decreasing pH. The possibility of a silica-organic acid complex was investigated using UV-difference spectroscopy. Results suggest that dissolved silica is complexed by citrate, oxalate and pyruvate at pH 7 by an electron-donor acceptor complex, whereas no complexation occurs between silica and acetate, lactate, malonate, or succinate. Three models are proposed for the solution and surface complexation of silica by organic acid which result in the accelerated dissolution and increased solubility of quartz in organic rich water.

  16. Tipping the balance: Sclerotinia sclerotiorum secreted oxalic acid suppresses host defenses by manipulating the host redox environment.

    PubMed

    Williams, Brett; Kabbage, Mehdi; Kim, Hyo-Jin; Britt, Robert; Dickman, Martin B

    2011-06-01

    Sclerotinia sclerotiorum is a necrotrophic ascomycete fungus with an extremely broad host range. This pathogen produces the non-specific phytotoxin and key pathogenicity factor, oxalic acid (OA). Our recent work indicated that this fungus and more specifically OA, can induce apoptotic-like programmed cell death (PCD) in plant hosts, this induction of PCD and disease requires generation of reactive oxygen species (ROS) in the host, a process triggered by fungal secreted OA. Conversely, during the initial stages of infection, OA also dampens the plant oxidative burst, an early host response generally associated with plant defense. This scenario presents a challenge regarding the mechanistic details of OA function; as OA both suppresses and induces host ROS during the compatible interaction. In the present study we generated transgenic plants expressing a redox-regulated GFP reporter. Results show that initially, Sclerotinia (via OA) generates a reducing environment in host cells that suppress host defense responses including the oxidative burst and callose deposition, akin to compatible biotrophic pathogens. Once infection is established however, this necrotroph induces the generation of plant ROS leading to PCD of host tissue, the result of which is of direct benefit to the pathogen. In contrast, a non-pathogenic OA-deficient mutant failed to alter host redox status. The mutant produced hypersensitive response-like features following host inoculation, including ROS induction, callose formation, restricted growth and cell death. These results indicate active recognition of the mutant and further point to suppression of defenses by the wild type necrotrophic fungus. Chemical reduction of host cells with dithiothreitol (DTT) or potassium oxalate (KOA) restored the ability of this mutant to cause disease. Thus, Sclerotinia uses a novel strategy involving regulation of host redox status to establish infection. These results address a long-standing issue involving the

  17. Estimation of the oxalate content of foods and daily oxalate intake

    NASA Technical Reports Server (NTRS)

    Holmes, R. P.; Kennedy, M.

    2000-01-01

    BACKGROUND: The amount of oxalate ingested may be an important risk factor in the development of idiopathic calcium oxalate nephrolithiasis. Reliable food tables listing the oxalate content of foods are currently not available. The aim of this research was to develop an accurate and reliable method to measure the food content of oxalate. METHODS: Capillary electrophoresis (CE) and ion chromatography (IC) were compared as direct techniques for the estimation of the oxalate content of foods. Foods were thoroughly homogenized in acid, heat extracted, and clarified by centrifugation and filtration before dilution in water for analysis. Five individuals consuming self-selected diets maintained food records for three days to determine their mean daily oxalate intakes. RESULTS: Both techniques were capable of adequately measuring the oxalate in foods with a significant oxalate content. With foods of very low oxalate content (<1.8 mg/100 g), IC was more reliable than CE. The mean daily intake of oxalate by the five individuals tested was 152 +/- 83 mg, ranging from 44 to 352 mg/day. CONCLUSIONS: CE appears to be the method of choice over IC for estimating the oxalate content of foods with a medium (>10 mg/100 g) to high oxalate content due to a faster analysis time and lower running costs, whereas IC may be better suited for the analysis of foods with a low oxalate content. Accurate estimates of the oxalate content of foods should permit the role of dietary oxalate in urinary oxalate excretion and stone formation to be clarified. Other factors, apart from the amount of oxalate ingested, appear to exert a major influence over the amount of oxalate excreted in the urine.

  18. Preharvest treatments with malic, oxalic, and acetylsalicylic acids affect the phenolic composition and antioxidant capacity of coriander, dill and parsley.

    PubMed

    El-Zaeddi, Hussein; Calín-Sánchez, Ángel; Nowicka, Paulina; Martínez-Tomé, Juan; Noguera-Artiaga, Luis; Burló, Francisco; Wojdyło, Aneta; Carbonell-Barrachina, Ángel A

    2017-07-01

    The effects of a preharvest treatment with malic (MA), oxalic (OA), or acetylsalicylic (ASA) acid at three concentrations (1, 2 and 3mM) on the bioactivity and antioxidant capacity of coriander, dill, and parsley were investigated. The antioxidant capacity of the herbs extracts was assayed by spectrophotometric methods by using three different analytical methods: ORAC, FRAP, and ABTS; the effects of treatments were very positive in coriander, produced intermediate results in dill, and no effects were found in parsley plants. Polyphenol compounds were identified by LC-MS-QTof and quantified by UPLC-PDA-FL. Thirty phenolic compounds were identified in these three herbs. The major compounds were (i) coriander: dimethoxycinnamoyl hexoside and quercetin-3-O-rutinoside, (ii) dill: neochlorogenic acid and quercetin glucuronide, and (iii) parsley: apigenin-7-apiosylglucoside (apiin) and isorhamnetin-3-O-hexoside. The application of these three organic acids favored the accumulation of phenolic compounds in coriander plants, but had no significant positive effects on dill and parsley. The treatments leading to the best results in all three plants were the application of MA or OA at 1mM.

  19. Preharvest application of oxalic acid increased fruit size, bioactive compounds, and antioxidant capacity in sweet cherry cultivars (Prunus avium L.).

    PubMed

    Martínez-Esplá, Alejandra; Zapata, Pedro Javier; Valero, Daniel; García-Viguera, Cristina; Castillo, Salvador; Serrano, María

    2014-04-16

    Trees of 'Sweet Heart' and 'Sweet Late' sweet cherry cultivars (Prunus avium L.) were treated with oxalic acid (OA) at 0.5, 1.0, and 2.0 mM at 98, 112, and 126 days after full blossom. Results showed that all treatments increased fruit size at harvest, manifested by higher fruit volume and weight in cherries from treated trees than from controls, the higher effect being found with 2.0 mM OA (18 and 30% higher weight for 'Sweet Heart' and 'Sweet Late', respectively). Other quality parameters, such as color and firmness, were also increased by OA treatments, although no significant differences were found in total soluble solids or total acidity, showing that OA treatments did not affect the on-tree ripening process of sweet cherry. However, the increases in total anthocyanins, total phenolics, and antioxidant activity associated with the ripening process were higher in treated than in control cherries, leading to fruit with high bioactive compounds and antioxidant potential at commercial harvest (≅45% more anthocyanins and ≅20% more total phenolics). In addition, individual anthocyanins, flavonols, and chlorogenic acid derivatives were also increased by OA treatment. Thus, OA preharvest treatments could be an efficient and natural way to increase the quality and functional properties of sweet cherries.

  20. Chrysotile asbestos detoxification with a combined treatment of oxalic acid and silicates producing amorphous silica and biomaterial.

    PubMed

    Valouma, Aikaterini; Verganelaki, Anastasia; Maravelaki-Kalaitzaki, Pagona; Gidarakos, Evangelos

    2016-03-15

    This study was primarily imposed by the ever increasing need for detoxification of asbestos and asbestos containing materials (ACM), with potential application onsite. The present work investigates potential detoxification of pure chrysotile (Chr) asbestos via a combined treatment of oxalic acid dihydrate (Oxac) (Η2C2Ο4·2Η2Ο) with silicates, such as tetraethoxysilane (TEOS) (SiH20C8O4) and pure water glass (WG) (potassium silicate) (K2SiO3). These reagents used in the experimental procedure, do not cause adverse effects on the environment and are cost effective. The results of FTIR, XRD, optical and scanning microscopy coupled with EDS analyses indicated that all of the applied treatments destructed the Chr structure and yielded silica of amorphous phase and the biomaterial glushinskite from the Oxac reacted with brucite [Mg(OH)2] layer. Each of the proposed formulations can be applied for the detoxification of asbestos, according to priorities related to the specific products of the recovery treatment. Therefore, Oxac acid leaching followed by the TEOS addition is preferred in cases of glushinskite recovery; TEOS treatment of asbestos with subsequent Oxac addition produced amorphous silica production; finally Oxac acid leaching followed by WG encapsulated the asbestos fibers and can be used in cases of onsite asbestos and ACM detoxification.

  1. Plutonium oxalate precipitation for trace elemental determination in plutonium materials

    DOE PAGES

    Xu, Ning; Gallimore, David; Lujan, Elmer; ...

    2015-05-26

    In this study, an analytical chemistry method has been developed that removes the plutonium (Pu) matrix from the dissolved Pu metal or oxide solution prior to the determination of trace impurities that are present in the metal or oxide. In this study, a Pu oxalate approach was employed to separate Pu from trace impurities. After Pu(III) was precipitated with oxalic acid and separated by centrifugation, trace elemental constituents in the supernatant were analyzed by inductively coupled plasma-optical emission spectroscopy with minimized spectral interferences from the sample matrix.

  2. CO2-Free Power Generation on an Iron Group Nanoalloy Catalyst via Selective Oxidation of Ethylene Glycol to Oxalic Acid in Alkaline Media

    NASA Astrophysics Data System (ADS)

    Matsumoto, Takeshi; Sadakiyo, Masaaki; Ooi, Mei Lee; Kitano, Sho; Yamamoto, Tomokazu; Matsumura, Syo; Kato, Kenichi; Takeguchi, Tatsuya; Yamauchi, Miho

    2014-07-01

    An Fe group ternary nanoalloy (NA) catalyst enabled selective electrocatalysis towards CO2-free power generation from highly deliverable ethylene glycol (EG). A solid-solution-type FeCoNi NA catalyst supported on carbon was prepared by a two-step reduction method. High-resolution electron microscopy techniques identified atomic-level mixing of constituent elements in the nanoalloy. We examined the distribution of oxidised species, including CO2, produced on the FeCoNi nanoalloy catalyst in the EG electrooxidation under alkaline conditions. The FeCoNi nanoalloy catalyst exhibited the highest selectivities toward the formation of C2 products and to oxalic acid, i.e., 99 and 60%, respectively, at 0.4 V vs. the reversible hydrogen electrode (RHE), without CO2 generation. We successfully generated power by a direct EG alkaline fuel cell employing the FeCoNi nanoalloy catalyst and a solid-oxide electrolyte with oxygen reduction ability, i.e., a completely precious-metal-free system.

  3. CO2-Free Power Generation on an Iron Group Nanoalloy Catalyst via Selective Oxidation of Ethylene Glycol to Oxalic Acid in Alkaline Media

    PubMed Central

    Matsumoto, Takeshi; Sadakiyo, Masaaki; Ooi, Mei Lee; Kitano, Sho; Yamamoto, Tomokazu; Matsumura, Syo; Kato, Kenichi; Takeguchi, Tatsuya; Yamauchi, Miho

    2014-01-01

    An Fe group ternary nanoalloy (NA) catalyst enabled selective electrocatalysis towards CO2-free power generation from highly deliverable ethylene glycol (EG). A solid-solution-type FeCoNi NA catalyst supported on carbon was prepared by a two-step reduction method. High-resolution electron microscopy techniques identified atomic-level mixing of constituent elements in the nanoalloy. We examined the distribution of oxidised species, including CO2, produced on the FeCoNi nanoalloy catalyst in the EG electrooxidation under alkaline conditions. The FeCoNi nanoalloy catalyst exhibited the highest selectivities toward the formation of C2 products and to oxalic acid, i.e., 99 and 60%, respectively, at 0.4 V vs. the reversible hydrogen electrode (RHE), without CO2 generation. We successfully generated power by a direct EG alkaline fuel cell employing the FeCoNi nanoalloy catalyst and a solid-oxide electrolyte with oxygen reduction ability, i.e., a completely precious-metal-free system. PMID:25004118

  4. Influence of oxalic and malic acids in chickpea leaf exudates on the biological activity of CryIAc towards Helicoverpa armigera.

    PubMed

    Devi, V Surekha; Sharma, Hari C; Rao, P Arjuna

    2013-04-01

    Efforts are being made to express toxin genes from the bacterium, Bacillus thuringiensis (Bt) in chickpea for minimizing the losses due to the pod borer, Helicoverpa armigera. However, there is an apprehension that acidic exudates in chickpea leaves may influence the protoxin-toxin conversion in the insect midgut, and thus, reduce the efficacy of Bt toxins. Therefore, we studied the influence of organic acids (oxalic acid and malic acid) present in the trichome exudates of chickpea on the biological activity and binding of Bt δ-endotoxin Cry1Ac to brush border membrane vesicles (BBMV) of the pod borer, H. armigera. Oxalic and malic acids in combination at concentrations present in chickpea leaves did not influence the biological activity of Bt toxin Cry1Ac towards H. armigera larvae. Amounts of Cry1Ac protein in the midgut of insects reared on diets with organic acids were similar to those reared on artificial diet without the organic acids. However, very high concentrations of the organic acids reduced the amounts of Cry1Ac in the midgut of H. armigera larvae. Organic acids in the artificial diet also increased the excretion of Cry1Ac in the fecal matter. Organic acids reduced the amount of protein in the BBMV of insects reared on diets with Cry1Ac, possibly because of reduced size of the larvae. Oxalic and malic acids at concentrations present in chickpea leaves did not affect the biological activity of Cry1Ac, but it will be desirable to have high levels of expression of Cry1Ac toxin proteins in chickpea for effective control of the pod borer, H. armigera.

  5. Effect of organic and conventional cropping systems on ascorbic acid, vitamin C, flavonoids, nitrate, and oxalate in 27 varieties of spinach (Spinacia oleracea L.).

    PubMed

    Koh, Eunmi; Charoenprasert, Suthawan; Mitchell, Alyson E

    2012-03-28

    This study was undertaken to compare the levels of ascorbic acid, vitamin C, flavonoids, nitrate, and oxalate in 27 spinach varieties grown in certified organic and conventional cropping systems. Liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-(ESI)MS/MS) of methanolic extracts of spinach demonstrated 17 flavonoids, including glucuronides and acylated di- and triglycosides of methylated and methylenedioxyderivatives of 6-oxygenated flavonoids. The mean levels of ascorbic acid and flavonoids were significantly (p < 0.001) higher in the organically grown [40.48 ± 6.16 and 2.83 ± 0.03 mg/kg of fresh weight (FW)] spinach compared to the conventionally grown spinach (25.75 ± 6.12 and 2.27 ± 0.02 mg/kg of FW). Conversely, the mean levels of nitrate were significantly (p < 0.001) higher in the conventionally grown spinach compared to the organically grown spinach. No significant effects were observed in the oxalate content of spinach from either production system. The levels of nitrate correlated negatively with those of ascorbic acid, vitamin C, and total flavonoids and showed a positive correlation with the oxalate content. These results suggest that organic cropping systems result in spinach with lower levels of nitrates and higher levels of flavonoids and ascorbic acid.

  6. Dissociation of protonated oxalic acid [HOOC-C(OH)2]+ into H3O+ + CO + CO2: An experimental and CBS-QB3 computational study

    NASA Astrophysics Data System (ADS)

    Ervasti, Henri K.; Lee, Richard; Burgers, Peter C.; Ruttink, Paul J. A.; Terlouw, Johan K.

    2006-03-01

    The predominant dissociation process observed for metastable protonated oxalic acid ions HOOC-C(OH)2+ (generated by self-protonation) leads to H3O++ CO + CO2. We have traced the mechanism of this intriguing reaction using the CBS-QB3 model chemistry. Our calculations show that a unique ter-body complex, OCO...H3O+...CO, plays a key role in the rearrangement process. This complex can also dissociate to the proton bound dimers [H2O...H...OCO]+ and [H2O...H...CO]+ which are minor processes observed in the metastable ion mass spectrum. A further minor process leads to the proton bound dimer OCO...H+...CO which is formed by water extrusion from the ter-body complex. Arguments are provided that the ter-body complex is also generated in the ion source by the collision encounter between neutral and ionized oxalic acid.

  7. A novel digestion method based on a choline chloride-oxalic acid deep eutectic solvent for determining Cu, Fe, and Zn in fish samples.

    PubMed

    Habibi, Emadaldin; Ghanemi, Kamal; Fallah-Mehrjardi, Mehdi; Dadolahi-Sohrab, Ali

    2013-01-31

    A novel and efficient digestion method based on choline chloride-oxalic acid (ChCl-Ox) deep eutectic solvent (DES) was developed for flame atomic absorption spectrometry (FAAS) determination of Cu, Zn, and Fe in biological fish samples. Key parameters that influence analyte recovery were investigated and optimized, using the fish protein certified reference material (CRM, DORM-3) throughout the procedure. In this method, 100 mg of the sample was dissolved in ChCl-Ox (1:2, molar ratio) at 100°C for 45 min. Then, 5.0 mL HNO(3) (1.0 M) was added. After centrifugation, the supernatant solution was filtered, diluted to a known volume, and analyzed by FAAS. Under optimized conditions, an excellent agreement between the obtained results and the certified values was observed, using Student's t-test (P=0.05); the extraction recovery of the all elements was greater than 95.3%. The proposed method was successfully applied to the determination of analytes in different tissues (muscle, liver, and gills) having a broad concentration range in a marine fish sample. The reproducibility of the method was validated by analyzing all samples by our method in a different laboratory, using inductively coupled plasma optical emission spectrometry (ICP-OES). For comparison, a conventional acid digestion (CAD) method was also used for the determination of analytes in all studied samples. The simplicity of the proposed experimental procedure, high extraction efficiency, short analysis time, lack of concentrated acids and oxidizing agents, and the use of safe and inexpensive components demonstrate the high potential of ChCl-Ox (1:2) for routine trace metal analysis in biological samples.

  8. The YvrI Alternative σ Factor Is Essential for Acid Stress Induction of Oxalate Decarboxylase in Bacillus subtilis▿ †

    PubMed Central

    MacLellan, Shawn R.; Helmann, John D.; Antelmann, Haike

    2009-01-01

    YvrI is a recently identified alternative σ factor in Bacillus subtilis that requires the coactivator YvrHa to activate transcription. Previously, a strain engineered to overproduce YvrI was found to overproduce oxalate decarboxylase (OxdC), and further analysis identified three YvrI-activated promoters preceding the yvrI-yvrHa, yvrJ, and oxdC-yvrL operons. Independently, proteome analyses identified OxdC as a highly abundant, cell wall-associated protein that accumulated under acidic growth conditions. We show here that the accumulation of OxdC in the cell wall proteome under acidic growth conditions is absolutely dependent on YvrI and is correlated with enhanced transcription of both the yvrI-yvrHa and the oxdC-yvrL operons. Conversely, OxdC accumulates to a high level even under nonacidic growth conditions in cells lacking YvrL, a negative regulator of YvrI/YvrHa-dependent transcription. These results indicate that YvrI and its associated coregulators YvrHa and YvrL are required for the regulation of OxdC expression by acid stress. The high-level accumulation of OxdC depends, in part, on a strong oxdC promoter. A regulatory sequence with similarity to an upstream promoter element (UP) was identified upstream of the oxdC promoter and is required for high-level promoter activity. Conservation of the YvrI/YvrHa/YvrL regulatory system among related species allowed us to deduce an expanded consensus sequence for the compositionally unusual promoters recognized by this new σ factor. PMID:19047353

  9. Graphene-supported PtPd Bimetallic Gathered Nanocrystals for Non-enzymatic Sensing of Oxalic Acid.

    PubMed

    Cai, Zhixiong; Zhao, Li; Zhao, Tingting; Wang, Yiru; Chen, Xi

    2015-01-01

    A novel non-enzymatic oxalic acid (OA) sensor was developed using a nanocrystal PtPd loaded reduced graphene nanosheets (PtPdNCs/RGO)-modified electrode. PtPdNCs/RGO were successfully achieved by a facile, one-step and template-free method, in which PtPd nanoparticles with 100 nm-scale were assembled from polyhedral PtPd nanocrystals of various shapes and dispersed on the graphene nanosheets. Resulting PtPdNCs/RGO were characterized and used for PtPdNCs/RGO-modified electrodes. Electrochemical oxidation of OA on the modified electrode was investigated by cyclic voltammetry and differential pulse voltammetry (DPV). Well-defined peaks of OA oxidation could be obtained using an electrode that indicated its high electrochemical activity. The concentration of OA and the current responses could be obtained in the ranges of 0.5 - 10 and 10 - 35 mM with correlation coefficients of 0.9994 and 0.9952; the detection limit (S/N = 3) was found to be 0.05 mM. The modified electrode presented good characteristics in terms of both stability and reproducibility, promising its applicability in practical analysis.

  10. Inhibition of crystallization of calcium oxalate by the extraction of Tamarix gallica L.

    PubMed

    Bensatal, Ahmed; Ouahrani, M R

    2008-12-01

    The main objective is to study the inhibitor effect of acid fraction of the extract of Tamarix gallica L on the crystallization of calcium oxalate. The extract of Tamarix gallica L is very rich by acid compounds that are used as an inhibitor of nephrolithiasis (calcium oxalate). Our study of the calcium oxalate crystallization is based on the model of turbidimetry by means of a spectrophotometer. The calcium oxalate formation is induced by the addition of oxalate solutions of sodium and of calcium chloride. The addition of inhibitor with various concentrations enabled us to give information on the percentage of inhibition. The comparison between the turbidimetric slopes with and without inhibitor gives the effectiveness of inhibitor for the acid fraction. By comparing the photographs of with and without inhibitor, we concluded that the extract of Tamarix gallica L acts at the stage of growth. The acid fraction of the extract of Tamarix gallica L gives an activity remarkable in the formation of urinary lithiasis (calcium oxalate); this effectiveness is due to the presence of functions of acid.

  11. Stability Constants of Technetium (IV) Oxalate Complexes as a Function of Ionic Strength

    SciTech Connect

    Xia, Yuanxian; Hess, Nancy J.; Felmy, Andrew R.

    2006-03-01

    Solvent extraction methods were used to determine the stability constants of Tc(IV) with oxalate anions in NaCl solutions ranging in concentration from 0.5 M to 2.0 M. All experiments were conducted in an atmosphere-controlled chamber under Ar atmosphere (< 1.0ppm O2). A reducing agent (hydrazine) was used during extractions to maintain technetium in the tetravalent oxidation state. Independent tests confirmed that the oxidation state of technetium did not change during extractions. The distribution ratio of Tc(IV) between the organic and aqueous phases was found to decrease as the concentration of oxalic acid increased. At the oxalic acid concentrations used in these experiments, the complexes TcO(Ox) and TcO(Ox)22- were found to be the dominant aqueous species. Based on these data, the thermodynamic stability constants of Tc(IV) with oxalate complexes were calculated by the Specific Ion Interaction Theory (SIT).

  12. Electric conductance of dispersions of metal oxides in solutions of weak acids in mixed dioxane-water solvents.

    PubMed

    Kosmulski, Marek; Mączka, Edward

    2012-08-15

    The electric conductance of solutions of sulfuric, oxalic, benzoic, and salicylic acid (up to 0.02 M) in dioxane-water mixed solvents (90% and 93% dioxane by mass) has been studied in the presence and absence of TiO(2) and Al(2)O(3) (0.5-5% by mass). TiO(2) and Al(2)O(3) enhanced the conductance of solutions of organic acids in aqueous dioxane. The conductance is interpreted in terms of adsorption of acid in molecular form, dissolution of ceramic oxides in form of anionic complexes, and leaching of acidic impurities from ceramic oxides.

  13. CONCENTRATION OF Pu USING OXALATE TYPE CARRIER

    DOEpatents

    Ritter, D.M.; Black, R.P.S.

    1960-04-19

    A method is given for dissolving and reprecipitating an oxalate carrier precipitate in a carrier precipitation process for separating and recovering plutonium from an aqueous solution. Uranous oxalate, together with plutonium being carried thereby, is dissolved in an aqueous alkaline solution. Suitable alkaline reagents are the carbonates and oxulates of the alkali metals and ammonium. An oxidizing agent selected from hydroxylamine and hydrogen peroxide is then added to the alkaline solution, thereby oxidizing uranium to the hexavalent state. The resulting solution is then acidified and a source of uranous ions provided in the acidified solution, thereby forming a second plutoniumcarrying uranous oxalate precipitate.

  14. Turning sunlight into stone: the oxalate-carbonate pathway in a tropical tree ecosystem

    NASA Astrophysics Data System (ADS)

    Cailleau, G.; Braissant, O.; Verrecchia, E. P.

    2011-02-01

    An African oxalogenic tree, the iroko tree (Milicia excelsa), has the property to enhance carbonate precipitation in tropical oxisols, where such accumulations are not expected due to the theoretical acidic conditions of these soils. This uncommon process is linked to the oxalate-carbonate pathway, which increases soil pH through oxalate oxidation. In order to investigate the oxalate-carbonate pathway in the iroko system, fluxes of matter have been identified, described, and evaluated from field to microscopic scales. In the first centimeters of the soil profile, decaying of the organic matter allows the release of whewellite crystals, mainly due to the action of termites and saprophytic fungi. Regarding the carbonate flux, another direct consequence of wood feeding is a concomitant flux of carbonate formed in wood tissues, which is not consumed by termites. Nevertheless, calcite biomineralization of the tree is not a consequence of in situ oxalate consumption, but rather related to the oxalate oxidation inside the upper part of the soil. The consequence of this oxidation is the presence of carbonate ions in the soil solution pumped through the roots, leading to preferential mineralization of the roots and the trunk base. An ideal scenario for the iroko biomineralization and soil carbonate accumulation starts with oxalatization: as the iroko tree grows, the organic matter flux to the soil constitutes the litter. Therefore, an oxalate pool is formed on the forest ground. Then, wood rotting gents (mainly termites, fungi, and bacteria) release significant amounts of oxalate crystals from decaying plant tissues. In addition some of these gents are themselves producers of oxalate (fungi). Both processes contribute to a soil pool of "available" oxalate crystals. Oxalate consumption by oxalotrophic bacteria can start. Carbonate and calcium ions present in the soil solution represent the end products of the oxalate-carbonate pathway. The solution is pumped through the

  15. Turning sunlight into stone: the oxalate-carbonate pathway in a tropical tree ecosystem

    NASA Astrophysics Data System (ADS)

    Cailleau, G.; Braissant, O.; Verrecchia, E. P.

    2011-07-01

    An African oxalogenic tree, the iroko tree (Milicia excelsa), has the property to enhance carbonate precipitation in tropical oxisols, where such accumulations are not expected due to the acidic conditions in these types of soils. This uncommon process is linked to the oxalate-carbonate pathway, which increases soil pH through oxalate oxidation. In order to investigate the oxalate-carbonate pathway in the iroko system, fluxes of matter have been identified, described, and evaluated from field to microscopic scales. In the first centimeters of the soil profile, decaying of the organic matter allows the release of whewellite crystals, mainly due to the action of termites and saprophytic fungi. In addition, a concomitant flux of carbonate formed in wood tissues contributes to the carbonate flux and is identified as a direct consequence of wood feeding by termites. Nevertheless, calcite biomineralization of the tree is not a consequence of in situ oxalate consumption, but rather related to the oxalate oxidation inside the upper part of the soil. The consequence of this oxidation is the presence of carbonate ions in the soil solution pumped through the roots, leading to preferential mineralization of the roots and the trunk base. An ideal scenario for the iroko biomineralization and soil carbonate accumulation starts with oxalatization: as the iroko tree grows, the organic matter flux to the soil constitutes the litter, and an oxalate pool is formed on the forest ground. Then, wood rotting agents (mainly termites, saprophytic fungi, and bacteria) release significant amounts of oxalate crystals from decaying plant tissues. In addition, some of these agents are themselves producers of oxalate (e.g. fungi). Both processes contribute to a soil pool of "available" oxalate crystals. Oxalate consumption by oxalotrophic bacteria can then start. Carbonate and calcium ions present in the soil solution represent the end products of the oxalate-carbonate pathway. The solution is

  16. USE OF AN EQUILIBRIUM MODEL TO FORECAST DISSOLUTION EFFECTIVENESS, SAFETY IMPACTS, AND DOWNSTREAM PROCESSABILITY FROM OXALIC ACID AIDED SLUDGE REMOVAL IN SAVANNAH RIVER SITE HIGH LEVEL WASTE TANKS 1-15

    SciTech Connect

    KETUSKY, EDWARD

    2005-10-31

    This thesis details a graduate research effort written to fulfill the Magister of Technologiae in Chemical Engineering requirements at the University of South Africa. The research evaluates the ability of equilibrium based software to forecast dissolution, evaluate safety impacts, and determine downstream processability changes associated with using oxalic acid solutions to dissolve sludge heels in Savannah River Site High Level Waste (HLW) Tanks 1-15. First, a dissolution model is constructed and validated. Coupled with a model, a material balance determines the fate of hypothetical worst-case sludge in the treatment and neutralization tanks during each chemical adjustment. Although sludge is dissolved, after neutralization more is created within HLW. An energy balance determines overpressurization and overheating to be unlikely. Corrosion induced hydrogen may overwhelm the purge ventilation. Limiting the heel volume treated/acid added and processing the solids through vitrification is preferred and should not significantly increase the number of glass canisters.

  17. Effect of Organic Acid Additions on the General and Localized Corrosion Susceptibility of Alloy 22 in Chloride Solutions

    SciTech Connect

    Carranza, R M; Giordano, C M; Rodr?guez, M A; Ilevbare, G O; Rebak, R B

    2007-08-28

    Electrochemical studies such as cyclic potentiodynamic polarization (CPP) and electrochemical impedance spectroscopy (EIS) were performed to determine the corrosion behavior of Alloy 22 (N06022) in 1M NaCl solutions at various pH values from acidic to neutral at 90 C. All the tested material was wrought Mill Annealed (MA). Tests were also performed in NaCl solutions containing weak organic acids such as oxalic, acetic, citric and picric. Results show that the corrosion rate of Alloy 22 was significantly higher in solutions containing oxalic acid than in solutions of pure NaCl at the same pH. Citric and picric acids showed a slightly higher corrosion rate, and acetic acid maintained the corrosion rate of pure chloride solutions at the same pH. Organic acids revealed to be weak inhibitors for crevice corrosion. Higher concentration ratios, compared to nitrate ions, were needed to completely inhibit crevice corrosion in chloride solutions. Results are discussed considering acid dissociation constants, buffer capacity and complex formation constants of the different weak acids.

  18. Probiotics and Other Key Determinants of Dietary Oxalate Absorption1

    PubMed Central

    Liebman, Michael; Al-Wahsh, Ismail A.

    2011-01-01

    Oxalate is a common component of many foods of plant origin, including nuts, fruits, vegetables, grains, and legumes, and is typically present as a salt of oxalic acid. Because virtually all absorbed oxalic acid is excreted in the urine and hyperoxaluria is known to be a considerable risk factor for urolithiasis, it is important to understand the factors that have the potential to alter the efficiency of oxalate absorption. Oxalate bioavailability, a term that has been used to refer to that portion of food-derived oxalate that is absorbed from the gastrointestinal tract (GIT), is estimated to range from 2 to 15% for different foods. Oxalate bioavailability appears to be decreased by concomitant food ingestion due to interactions between oxalate and coingested food components that likely result in less oxalic acid remaining in a soluble form. There is a lack of consensus in the literature as to whether efficiency of oxalate absorption is dependent on the proportion of total dietary oxalate that is in a soluble form. However, studies that directly compared foods of varying soluble oxalate contents have generally supported the proposition that the amount of soluble oxalate in food is an important determinant of oxalate bioavailability. Oxalate degradation by oxalate-degrading bacteria within the GIT is another key factor that could affect oxalate absorption and degree of oxaluria. Studies that have assessed the efficacy of oral ingestion of probiotics that provide bacteria with oxalate-degrading capacity have led to promising but generally mixed results, and this remains a fertile area for future studies. PMID:22332057

  19. Synthesis and characterization of polymorphs of photoluminescent Eu(III)-(2,5-furandicarboxylic acid, oxalic acid) MOFs

    NASA Astrophysics Data System (ADS)

    Shi, Fa-Nian; Ananias, Duarte; Yang, Ting-Hai; Rocha, João

    2013-08-01

    A novel metal organic framework (MOF) formulated as [Eu(H2O)2(fdc)(ox)0.5·(H2O)]n (1, fdc2-=2,5-furandicarboxylate, ox2-=oxalate), was hydrothermally synthesized via in situ ox2- generation from the partial decomposition of the fdc2- ligand. This material crystallizes in the monoclinic space group C2/c, unit cell parameters of 1: a=16.7570(10), b=10.5708(7), c=13.5348(14) Å, β=116.917(2)° (Z=8), and exhibits a three-dimensional (3D)-porous framework, with guest water molecules residing in the channel linking all other ligands (H2O, ox2-and fdc2-) via hydrogen bonding interactions. Compound 2 is a polymorph of 1 crystallizing in monoclinic P21/c space group. The photoluminescence properties of 1 and 2 were studied at room temperature. The spectra show the typical Eu3+ red emission and the differences observed reflects the slightly different structures of these polymorphs.

  20. Complex dynamic behavior in the bromate-oxalic acid-acetone-Mn(II) oscillating reaction in a continuous stirred tank reactor (CSTR)

    NASA Astrophysics Data System (ADS)

    Silva, Lucyane C.; Faria, Roberto B.

    2007-05-01

    The oscillating reaction bromate-oxalic acid-acetone-Mn(II)-sulfuric acid was observed for the first time in a CSTR at 20 °C. Depending on the bromate concentrations and flow rate, the system showed large amplitude oscillations, two kinds of mixed mode oscillations, quasiperiodicity and bursts of large amplitude oscillations, all mapped in a phase diagram. More complex behavior was favored at low bromate concentrations. The system without acetone was discovered to oscillate too, but the more complex patterns were not seen, indicating that acetone is implied in their formation.

  1. [Current status of prevention and therapy of urinary calculi and peroral chemo-litholysis with special attention to the relationship of increased excretion of uric acid in oxalate lithiasis].

    PubMed

    Leskovar, P

    1980-03-01

    A survey shall be given of the present state of prevention and therapy of urolithiasis as well as of the up to now much restricted possibilities of the chemolitholysis. Particular attention is paid to calcium on account of its participation in the development of oxalate and phosphate calculi which together might be 70--80% of all calculi as well as to the rather limited possibilities of the reduction of the oxalate secretion in the urine. The encouragement of the oxalate lithiasis by increased uric acid in the urine as well as the reduction of the frequency of relapses not only of the concrements of the uric acid but also of the oxalate concrements by the uricostatic Allopurinol (e.g. zyloric) is dealt with.

  2. Combined administration of oxalic acid, succimer and its analogue for the reversal of gallium arsenide-induced oxidative stress in rats.

    PubMed

    Flora, Swaran J S; Kannan, Gurusamy M; Pant, Bhagwat P; Jaiswal, Devendra K

    2002-06-01

    Gallium arsenide (GaAs), a group III-VA intermetallic semiconductor, possesses superior electronic and optical properties and has a wide application in the electronics industry. Exposure to GaAs in the semiconductor industry is a potential occupational hazard because cleaning and slicing GaAs ingots to yield the desired wafer could generate GaAs particles. The ability of GaAs to induce oxidative stress has not yet been reported. The present study reports the role of oxidative stress in GaAs-induced haematological and liver disorders and its possible reversal overturn by administration of meso-2,3-dimercaptosuccinic acid (DMSA) and one of its analogue, monoisoamyl DMSA (MiADMSA), either individually or in combination with oxalic acid. While DMSA and MiADMSA are potential arsenic chelators, oxalic acid is reported to be an effective gallium chelator. Male rats were exposed to 10 mg/kg GaAs orally, 5 days a week for 8 weeks. GaAs exposure was then stopped and rats were given a 0.5 mmol/kg dose of succimers (DMSA or MiADMSA), oxalic acid or a combination of the two, intraperitoneally once daily for 5 consecutive days. We found a significant fall in blood delta-aminolevulinic acid dehydratase (ALAD) activity and blood glutathione (GSH) level, and an increased urinary excretion of delta-aminolevulinic acid (ALA) and an increased malondialdehyde (MDA) level in erythrocytes of rats exposed to GaAs. Hepatic GSH levels decreased, whereas there was an increase in GSSG and MDA levels. The results suggest a role of oxidative stress in GaAs-induced haematological and hepatic damage. Administration of DMSA and MiADMSA produced effective recovery in most of the above variables. However, a greater effectiveness of the chelation treatment (i.e. removal of both gallium and arsenic from body organs) could be achieved by combined administration of succimer (DMSA) with oxalic acid since, after MiADMSA administration, a marked loss of essential metals (copper and zinc) is of concern.

  3. Zirconium-carbon hybrid sorbent for removal of fluoride from water: oxalic acid mediated Zr(IV) assembly and adsorption mechanism.

    PubMed

    Velazquez-Jimenez, Litza Halla; Hurt, Robert H; Matos, Juan; Rangel-Mendez, Jose Rene

    2014-01-21

    When activated carbon (AC) is modified with zirconium(IV) by impregnation or precipitation, the fluoride adsorption capacity is typically improved. There is significant potential to improve these hybrid sorbents by controlling the impregnation conditions, which determine the assembly and dispersion of the Zr phases on carbon surfaces. Here, commercial activated carbon was modified with Zr(IV) together with oxalic acid (OA) used to maximize the zirconium dispersion and enhance fluoride adsorption. Adsorption experiments were carried out at pH 7 and 25 °C with a fluoride concentration of 40 mg L(-1). The OA/Zr ratio was varied to determine the optimal conditions for subsequent fluoride adsorption. The data was analyzed using the Langmuir and Freundlich isotherm models. FTIR, XPS, and the surface charge distribution were performed to elucidate the adsorption mechanism. Potentiometric titrations showed that the modified activated carbon (ZrOx-AC) possesses positive charge at pH lower than 7, and FTIR analysis demonstrated that zirconium ions interact mainly with carboxylic groups on the activated carbon surfaces. Moreover, XPS analysis demonstrated that Zr(IV) interacts with oxalate ions, and the fluoride adsorption mechanism is likely to involve -OH(-) exchange from zirconyl oxalate complexes.

  4. Zirconium-carbon hybrid sorbent for removal of fluoride from water: oxalic acid mediated Zr(IV) assembly and adsorption mechanism

    PubMed Central

    Halla, Velazquez-Jimenez Litza; Hurt Robert, H; Juan, Matos; Rene, Rangel-Mendez Jose

    2014-01-01

    When activated carbon (AC) is modified with zirconium(IV) by impregnation or precipitation, the fluoride adsorption capacity is typically improved. There is significant potential to improve these hybrid sorbent by controlling the impregnation conditions, which determine the assembly and dispersion of the Zr phases on carbon surfaces. Here, commercial activated carbon was modified with Zr(IV) together with oxalic acid (OA) used to maximize the zirconium dispersion and enhance fluoride adsorption. Adsorption experiments were carried out at pH 7 and 25 °C with a fluoride concentration of 40 mg L−1. The OA/Zr ratio was varied to determine the optimal conditions for subsequent fluoride adsorption. The data was analyzed using the Langmuir and Freundlich isotherm models. FTIR, XPS and the surface charge distribution were performed to elucidate the adsorption mechanism. Potentiometric titrations showed that the modified activated carbon (ZrOx-AC) possesses positive charge at pH lower than 7, and FTIR analysis demonstrated that zirconium ions interact mainly with carboxylic groups on the activated carbon surfaces. Moreover, XPS analysis demonstrated that Zr(IV) interacts with oxalate ions, and the fluoride adsorption mechanism is likely to involve –OH− exchange from zirconyl oxalate complexes. PMID:24359079

  5. Removal of arsenic and cadmium with sequential soil washing techniques using Na2EDTA, oxalic and phosphoric acid: Optimization conditions, removal effectiveness and ecological risks.

    PubMed

    Wei, Meng; Chen, Jiajun; Wang, Xingwei

    2016-08-01

    Testing of sequential soil washing in triplicate using typical chelating agent (Na2EDTA), organic acid (oxalic acid) and inorganic weak acid (phosphoric acid) was conducted to remediate soil contaminated by heavy metals close to a mining area. The aim of the testing was to improve removal efficiency and reduce mobility of heavy metals. The sequential extraction procedure and further speciation analysis of heavy metals demonstrated that the primary components of arsenic and cadmium in the soil were residual As (O-As) and exchangeable fraction, which accounted for 60% and 70% of total arsenic and cadmium, respectively. It was determined that soil washing agents and their washing order were critical to removal efficiencies of metal fractions, metal bioavailability and potential mobility due to different levels of dissolution of residual fractions and inter-transformation of metal fractions. The optimal soil washing option for arsenic and cadmium was identified as phosphoric-oxalic acid-Na2EDTA sequence (POE) based on the high removal efficiency (41.9% for arsenic and 89.6% for cadmium) and the minimal harmful effects of the mobility and bioavailability of the remaining heavy metals.

  6. ELECTROLYTIC REDUCTION OF NITRIC ACID SOLUTIONS

    DOEpatents

    Alter, H.W.; Barney, D.L.

    1958-09-30

    A process is presented for the treatment of radioactivc waste nitric acid solutions. The nitric acid solution is neutralized with an alkali metal hydroxide in an amount sufficient to precipitate insoluble hydroxides, and after separation of the precipitate the solution is electrolyzed to convert the alkali nitrate formed, to alkali hydroxide, gaseous ammonla and oxygen. The solution is then reusable after reducing the volume by evaporating the water and dissolved ammonia.

  7. Speciation in experimental C-O-H fluids produced by the thermal dissociation of oxalic acid dihydrate

    USGS Publications Warehouse

    Morgan, G.B.; Chou, I.-Ming; Pasteris, J.D.

    1992-01-01

    Fluid speciations and their related reaction pathways were studied in C-O-H-system fluids produced by the thermal dissociation of oxalic acid dihydrate (OAD: H2C2O4 ?? 2H2O) sealed in silica glass capsules. Experiments were conducted in the temperature range 230-750??C, with bulk fluid densities in the range 0.01-0.53 g/cm3. Pressure was controlled by temperature and density in the isochoric systems. The quenched products of dissociation experiments were an aqueous liquid and one (supercritical fluid) or, rarely, two (vapor plus liquid) carbonic phase (s). In-situ Raman microanalyses were performed on the quenched carbonic phases at room temperature, at which fluid pressures ranged from about 50 to 340 bars. Bulk fluid speciations were reconstructed from the Raman analyses via mass balance constraints, and appear to monitor the true fluid speciations at run conditions. In experiments from the lowtemperature range (230-350??C), fluid speciations record the dissociation of OAD according to the reaction OAD = CO2 + CO + 3H2O. A process of the form CO + H2O = CO2 + H2 is driven to the right with increasing temperature. The hydrogen gas produced tends to escape from the sample systems via diffusion into/through the silica glass capsules, shifting bulk compositions toward equimolar binary H2O-CO2 mixtures. The speciations of fluids in experiments with minimal hydrogen loss show poor agreement with speciations calculated for equilibrium fluids by the corresponding-states model of Saxena and Fei (1988). Such disagreement suggests that the formations of CH4 and graphite are metastably inhibited in the current experiments, which correlates with their absence or trivial abundances in experimental products. Moreover, calculations in which the stabilities of methane and graphite are suppressed suggest that such metastable equilibrium is approached only in experiments at temperatures greater than about 600-650??C. These results have applications to fluid processes in geological

  8. Nitric acid recovery from waste solutions

    DOEpatents

    Wilson, A. S.

    1959-04-14

    The recovery of nitric acid from aqueous nitrate solutions containing fission products as impurities is described. It is desirable to subject such solutions to concentration by evaporation since nitric acid is regenerated thereby. A difficulty, however, is that the highly radioactive fission product ruthenium is volatilized together with the nitric acid. It has been found that by adding nitrous acid, ruthenium volatilization is suppressed and reduced to a negligible degree so that the distillate obtained is practically free of ruthenium.

  9. Oxalate content of foods and its effect on humans.

    PubMed

    Noonan, S C; Savage, G P

    1999-03-01

    Oxalic acid and its salts occur as end products of metabolism in a number of plant tissues. When these plants are eaten they may have an adverse effect because oxalates bind calcium and other minerals. While oxalic acid is a normal end product of mammalian metabolism, the consumption of additional oxalic acid may cause stone formation in the urinary tract when the acid is excreted in the urine. Soaking and cooking of foodstuffs high in oxalate will reduce the oxalate content by leaching. The mean daily intake of oxalate in English diets has been calculated to be 70-150 mg, with tea appearing to contribute the greatest proportion of oxalate in these diets; rhubarb, spinach and beet are other common high oxalate-content foods. Vegetarians who consume greater amounts of vegetables will have a higher intake of oxalates, which may reduce calcium availability. This may be an increased risk factor for women, who require greater amounts of calcium in the diet. In humans, diets low in calcium and high in oxalates are not recommended but the occasional consumption of high oxalate foods as part of a nuritious diet does not pose any particular problem.

  10. Mineralogical basis for the interpretation of multi-element (ICP-AES), oxalic acid, and aqua regia partial digestions of stream sediments for reconnaissance exploration geochemistry

    USGS Publications Warehouse

    Church, S.E.; Mosier, E.L.; Motooka, J.M.

    1987-01-01

    We have applied partial digestion procedures, primarily oxalic acid and aqua regia leaches, to several regional geochemical reconnaissance studies carried out using Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) analytical methods. We have chosen to use these two acids because the oxalic acid primarily attacks those compounds formed during secondary geochemical processes, whereas aqua regia will digest the primary sulfide phases as well as secondary phases. Application of the partial digestion technique has proven superior to total digestion because the concentration of metals in hydromorphic compounds and the sulfides is enhanced relative to the metals bound in the unattacked silicate phases. The aqua regia digestion attacks and leaches metals from the mafic chain silicates and the phyllosilicates (coordination number of VI or more), yielding a characteristic geochemical signature, but does not leach appreciable metal from many other silicates. In order to interpret the results from these leach studies, we have initiated an investigation of a large suite of hand-picked mineral separates. The study includes analyses of about two hundred minerals representing the common rock-forming minerals as well as end-member compositions of various silicates, oxides, sulfides, carbonates, sulfates, and some vanadates, molybdates, tungstates, and phosphates. The objective of this study is to evaluate the effect of leaching by acids of particular lattice sites in specific mineral structures. ?? 1987.

  11. A simple, efficient and environmentally benign synthetic protocol for the synthesis of spirooxindoles using choline chloride-oxalic acid eutectic mixture as catalyst/solvent system.

    PubMed

    Khandelwal, Sarita; Rajawat, Anshu; Tailor, Yogesh Kumar; Kumar, Mahendra

    2014-01-01

    An efficient and environmentally benign domino protocol has been presented for the synthesis of structurally diverse spirooxindoles spiroannulated with pyranopyridopyrimidines, indenopyridopyrimidines, and chromenopyridopyrimidines involving three-component reaction of aminouracils, isatins and cyclic carbonyl compounds in deep eutectic solvent (choline chloride-oxalic acid: 1:1) which acts as efficient catalyst and environmentally benign reaction medium. The present protocol offers several advantages such as operational simplicity with easy workup, shorter reaction times excellent yields with superior atom economy and environmentally benign reaction conditions with the use of cost-effective, recyclable, non-toxic and bio-degradable DES as catalyst/solvent.

  12. High abundances of oxalic, azelaic, and glyoxylic acids and methylglyoxal in the open ocean with high biological activity: Implication for secondary OA formation from isoprene

    NASA Astrophysics Data System (ADS)

    Bikkina, Srinivas; Kawamura, Kimitaka; Miyazaki, Yuzo; Fu, Pingqing

    2014-05-01

    Atmospheric dicarboxylic acids (DCA) are a ubiquitous water-soluble component of secondary organic aerosols (SOA), which can act as cloud condensation nuclei (CCN), affecting the Earth's climate. Despite the high abundances of oxalic acid and related compounds in the marine aerosols, there is no consensus on what controls their distributions over the open ocean. Marine biological productivity could play a role in the production of DCA, but there is no substantial evidence to support this hypothesis. Here we present latitudinal distributions of DCA, oxoacids and α-dicarbonyls in the marine aerosols from the remote Pacific. Their concentrations were found several times higher in more biologically influenced aerosols (MBA) than less biologically influenced aerosols. We propose isoprene and unsaturated fatty acids as sources of DCA as inferred from significantly higher abundances of isoprene-SOA tracers and azelaic acid in MBA. These results have implications toward the reassessment of climate forcing feedbacks of marine-derived SOA.

  13. Solution nonideality related to solute molecular characteristics of amino acids.

    PubMed Central

    Keener, C R; Fullerton, G D; Cameron, I L; Xiong, J

    1995-01-01

    By measuring the freezing-point depression for dilute, aqueous solutions of all water-soluble amino acids, we test the hypothesis that nonideality in aqueous solutions is due to solute-induced water structuring near hydrophobic surfaces and solute-induced water destructuring in the dipolar electric fields generated by the solute. Nonideality is expressed with a single solute/solvent interaction parameter I, calculated from experimental measure of delta T. A related parameter, I(n), gives a method of directly relating solute characteristics to solute-induced water structuring or destructuring. I(n)-values correlate directly with hydrophobic surface area and inversely with dipolar strength. By comparing the nonideality of amino acids with progressively larger hydrophobic side chains, structuring is shown to increase with hydrophobic surface area at a rate of one perturbed water molecule per 8.8 square angstroms, implying monolayer coverage. Destructuring is attributed to dielectric realignment as described by the Debye-Hückel theory, but with a constant separation of charges in the amino-carboxyl dipole. By using dimers and trimers of glycine and alanine, this destructuring is shown to increase with increasing dipole strength using increased separation of fixed dipolar charges. The capacity to predict nonideal solution behavior on the basis of amino acid characteristics will permit prediction of free energy of transfer to water, which may help predict the energetics of folding and unfolding of proteins based on the characteristics of constituent amino acids. Images FIGURE 6 PMID:7711253

  14. Recovery of pyruvic acid from biotransformation solutions.

    PubMed

    Ma, C Q; Li, J C; Qiu, J H; Wang, M; Xu, P

    2006-04-01

    The aim of this investigation was to separate pyruvic acid of biotransformation solutions from lactic acid through complex extraction. For this purpose, complex extraction was investigated from model solutions. Tri-n-octanylamine (TOA) was used as the extractant. The effects of various diluents, the stoichiometry of pyruvic acid to TOA, and the initial pH of the aqueous phase on the extraction process were investigated in this study. The effects of sodium hydroxide (NaOH) and trimethylamine (TMA) on the back extraction process were also studied, respectively. The optimal conditions attained from the model solutions proved efficient on the biotransformation solutions of different concentrations. A total recovery of 71-82% of pyruvic acid was obtained, whereas 89-92% of lactic acid was removed. The purity of pyruvic acid reached 97% after the removal of TMA by a simple distillation.

  15. Oxalic acid poisoning

    MedlinePlus

    ... national toll-free Poison Help hotline (1-800-222-1222) from anywhere in the United States. ... national toll-free Poison Help hotline (1-800-222-1222) from anywhere in the United States. This ...

  16. Mineral balances of men fed a diet containing fiber in fruits and vegetables and oxalic acid in spinach for six weeks.

    PubMed

    Kelsay, J L; Prather, E S; Clark, W M; Canary, J J

    1988-10-01

    In an investigation of the effects of fiber and oxalic acid on weekly mineral balances, 12 men consumed two diets consisting of natural foods for 6 wk each in a crossover design. One diet contained about 25 g neutral detergent fiber (NDF) in fruits and vegetables and included 100 g spinach, which is high in oxalic acid, every other day. The second diet was a low fiber diet that contained about 5 g NDF and the same amount of spinach as the first diet. On the basis of mean values for 6 wk, balances for calcium, magnesium, iron, zinc or manganese were not significantly different due to diet. Copper balances were significantly lower when the low fiber diet was consumed than when the diet containing fiber in fruits and vegetables and consequently a higher level of copper was consumed. Mineral balances were significantly different due to week. When results of both diets were considered together, mean mineral balances decreased at some time after wk 1 and returned to the wk 1 level during wk 6. Balances for wk 1 and 6 were not significantly different for any of the six minerals. These results demonstrate the importance of determining weekly balances for several weeks when conducting a human metabolic study.

  17. Reuse of sewage sludge as a catalyst in ozonation--efficiency for the removal of oxalic acid and the control of bromate formation.

    PubMed

    Wen, Gang; Pan, Zhi-Hui; Ma, Jun; Liu, Zheng-Qian; Zhao, Lei; Li, Jun-Jing

    2012-11-15

    Sewage derived sludge is produced with an annual amount increase of 2% all over the world and it is an urgent issue to be addressed by human being. In the present study, sludge was converted into sludge-based catalyst (SBC) with ZnCl2 as activation agent and characterized by several methods (e.g., scanning electron microscope, X-ray photoelectron spectroscope and Fourier transform infrared spectroscope). Then it was used as a catalyst to enhance the removal of refractory organic matter, oxalic acid, and to control the formation of bromate (BrO3-) in bench semi-continuous ozonation experiments. The effects of various operating parameters on the control of BrO3- formation were investigated. Furthermore, the mechanism for the enhancement of organic matter removal and the control of BrO3- formation was discussed as well. Results indicate that the combination of SBC with ozone shows a strong synergistic effect, resulting in a notable improvement on oxalic acid removal. A crucial surface reaction mechanism for the enhancement of organic matter removal is proposed on the basis of negative effect of higher pH and no inhibition effect of tert-butanol. The control for BrO3- formation was demonstrated and the reason for its control in the process of O3/SBC is the combined effect of SBC reductive properties, ozone exposure decrease and hydrogen peroxide concentration increase.

  18. OXALATE MASS BALANCE DURING CHEMICAL CLEANING IN TANK 6F

    SciTech Connect

    Poirier, M.; Fink, S.

    2011-07-22

    The Savannah River Remediation (SRR) is preparing Tank 6F for closure. The first step in preparing the tank for closure is mechanical sludge removal. Following mechanical sludge removal, SRS performed chemical cleaning with oxalic acid to remove the sludge heel. Personnel are currently assessing the effectiveness of the chemical cleaning to determine whether the tank is ready for closure. SRR personnel collected liquid samples during chemical cleaning and submitted them to Savannah River National Laboratory (SRNL) for analysis. Following chemical cleaning, they collected a solid sample (also known as 'process sample') and submitted it to SRNL for analysis. The authors analyzed these samples to assess the effectiveness of the chemical cleaning process. Analysis of the anions showed the measured oxalate removed from Tank 6F to be approximately 50% of the amount added in the oxalic acid. To close the oxalate mass balance, the author collected solid samples, leached them with nitric acid, and measured the concentration of cations and anions in the leachate. Some conclusions from this work are: (1) Approximately 65% of the oxalate added as oxalic acid was removed with the decanted liquid. (2) Approximately 1% of the oxalate (added to the tank as oxalic acid) formed precipitates with compounds such as nickel, manganese, sodium, and iron (II), and was dissolved with nitric acid. (3) As much as 30% of the oxalate may have decomposed forming carbon dioxide. The balance does not fully account for all the oxalate added. The offset represents the combined uncertainty in the analyses and sampling.

  19. Seasonal characteristics of oxalic acid and related SOA in the free troposphere of Mt. Hua, central China: implications for sources and formation mechanisms.

    PubMed

    Meng, Jingjing; Wang, Gehui; Li, Jianjun; Cheng, Chunlei; Ren, Yanqin; Huang, Yao; Cheng, Yuting; Cao, Junji; Zhang, Ting

    2014-09-15

    PM10 aerosols from the summit of Mt. Hua (2060 m a.s.l) in central China during the winter and summer of 2009 were analyzed for dicarboxylic acids, ketocarboxylic acids and α-dicarbonyls. Molecular composition of dicarboxylic acids (C2-C11) in the free tropospheric aerosols reveals that oxalic acid (C2, 399 ± 261 ng m(-3) in winter and 522 ± 261 ng m(-3) in summer) is the most abundant species in both seasons, followed by malonic (C3) and succinic (C4) acids, being consistent with that on ground levels. Most of the diacids are more abundant in summer than in winter, but adipic (C6) and phthalic (Ph) acids are twice lower in summer, suggesting more significant impact of anthropogenic pollution on the wintertime alpine atmosphere. Moreover, glyoxal (Gly) and methylglyoxal (mGly) are also lower in summer (12 ± 6.1 ng m(-3)) than in winter (22 ± 13 ng m(-3)). As both dicarbonyls are a major precursor of C2, their seasonal variation patterns, which are opposite to those of the diacids, indicate that the mountain troposphere is more oxidative in summer. C2 showed strong linear correlations with levoglucosan in winter and oxidation products of isoprene and monoterpene in summer. PCA analysis further suggested that the wintertime C2 and related SOA in the Mt. Hua troposphere mostly originate from photochemical oxidations of anthropogenic pollutants emitted from biofuel and coal combustion in lowland regions. On contrast, the summertime C2 and related SOA mostly originate from further oxidation of the mountainous isoprene and monoterpene oxidation products. The AIM model calculation results showed that oxalic acid concentration well correlated with particle acidity (R(2)=0.60) but not correlated with particle liquid water content, indicating that particle acidity favors the organic acid formation because aqueous-phase C2 production is the primary mechanism of C2 formation in ambient aerosols and is driven by acid-catalyzed oxidation.

  20. A Potentiometric, Spectrophotometric and Pitzer Ion-Interaction Study of Reaction Equilibria in the Aqueous H+-Al3+, H+-Oxalate and H+-Al3+-Oxalate Systems up to 5 mol*dm-3 NaCl

    SciTech Connect

    Boily, Jean F.; Qafoku, Odeta; Felmy, Andrew R.

    2007-12-01

    Aluminium-oxalate complexation was determined in acidic media of aqueous NaCl solutions ranging from 0.1-5.0 mol•dm-3. Complexation in the H+-Al3+ and H+-Oxalate systems was also studied to provide a set of internally consistent thermodynamic data. The ionic strength dependent formation constants describing the stabilities of the Al3+, AlOH2+, Al3(OH)45+, Al13O4(OH)247+, H2L, HL-, L2-, AlL+, AlL2- and AlL33- species (where L is the oxalate ion) was also described using a Pitzer ion interaction model. The derived parameters can be used to predict chemical speciation in the H+-Al3+-Oxalate system in the 0.1-5.0 mol•dm-3 NaCl range.

  1. Three-dimensional hydrogen-bonded structures in the hydrated proton-transfer salts of isonipecotamide with the dicarboxylic oxalic and adipic acid homologues.

    PubMed

    Smith, Graham; Wermuth, Urs D

    2013-10-01

    The structures of the 1:1 hydrated proton-transfer compounds of isonipecotamide (piperidine-4-carboxamide) with oxalic acid, 4-carbamoylpiperidinium hydrogen oxalate dihydrate, C6H13N2O(+)·C2HO4(-)·2H2O, (I), and with adipic acid, bis(4-carbamoylpiperidinium) adipate dihydrate, 2C6H13N2O(+)·C6H8O4(2-)·2H2O, (II), are three-dimensional hydrogen-bonded constructs involving several different types of enlarged water-bridged cyclic associations. In the structure of (I), the oxalate monoanions give head-to-tail carboxylic acid O-H···O(carboxyl) hydrogen-bonding interactions, forming C(5) chain substructures which extend along a. The isonipecotamide cations also give parallel chain substructures through amide N-H···O hydrogen bonds, the chains being linked across b and down c by alternating water bridges involving both carboxyl and amide O-atom acceptors and amide and piperidinium N-H···O(carboxyl) hydrogen bonds, generating cyclic R4(3)(10) and R3(2)(11) motifs. In the structure of (II), the asymmetric unit comprises a piperidinium cation, half an adipate dianion, which lies across a crystallographic inversion centre, and a solvent water molecule. In the crystal structure, the two inversion-related cations are interlinked through the two water molecules, which act as acceptors in dual amide N-H···O(water) hydrogen bonds, to give a cyclic R4(2)(8) association which is conjoined with an R4(4)(12) motif. Further N-H···O(water), water O-H···O(amide) and piperidinium N-H···O(carboxyl) hydrogen bonds give the overall three-dimensional structure. The structures reported here further demonstrate the utility of the isonipecotamide cation as a synthon for the generation of stable hydrogen-bonded structures. The presence of solvent water molecules in these structures is largely responsible for the non-occurrence of the common hydrogen-bonded amide-amide dimer, promoting instead various expanded cyclic hydrogen-bonding motifs.

  2. Reference electrode for strong oxidizing acid solutions

    DOEpatents

    Rigdon, Lester P.; Harrar, Jackson E.; Bullock, Sr., Jack C.; McGuire, Raymond R.

    1990-01-01

    A reference electrode for the measurement of the oxidation-reduction potentials of solutions is especially suitable for oxidizing solutions such as highly concentrated and fuming nitric acids, the solutions of nitrogen oxides, N.sub.2 O.sub.4 and N.sub.2 O.sub.5, in nitric acids. The reference electrode is fabricated of entirely inert materials, has a half cell of Pt/Ce(IV)/Ce(III)/70 wt. % HNO.sub.3, and includes a double-junction design with an intermediate solution of 70 wt. % HNO.sub.3. The liquid junctions are made from Corning No. 7930 glass for low resistance and negligible solution leakage.

  3. Preparation and thermal characterization of oxalic acid dihydrate/bentonite composite as shape-stabilized phase change materials for thermal energy storage

    NASA Astrophysics Data System (ADS)

    Han, Lipeng; Xie, Shaolei; Sun, Jinhe; Jia, Yongzhong

    2017-03-01

    Oxalic acid dihydrate (OAD) which has very high initial phase transition enthalpy is a promising phase change material (PCM). In this paper, shape-stabilized composite PCMs composed of OAD and bentonite were prepared by a facile blending method to overcome the problem of leakage. FT-IR results indicated the interactions between OAD and bentonite, such as the capillary force and the hydrogen bonding, resulting in the confined crystallization process. As a result, the OAD was confined to be amorphous. The thermogravimetric analysis and scanning electron microscope results showed that sample had the best coating effect when the amount of bentonite was 17.7%. The differential scanning calorimetry analyses demonstrated that a decrease in the OAD content was accompanied by a continuous decrease in the melting point and phase change enthalpy of the composites.

  4. Waste Treatment of Acidic Solutions from the Dissolution of Irradiated LEU Targets for 99-Mo Production

    SciTech Connect

    Bakel, Allen J.; Conner, Cliff; Quigley, Kevin; Vandegrift, George F.

    2016-10-01

    One of the missions of the Reduced Enrichment for Research and Test Reactors (RERTR) program (and now the National Nuclear Security Administrations Material Management and Minimization program) is to facilitate the use of low enriched uranium (LEU) targets for 99Mo production. The conversion from highly enriched uranium (HEU) to LEU targets will require five to six times more uranium to produce an equivalent amount of 99Mo. The work discussed here addresses the technical challenges encountered in the treatment of uranyl nitrate hexahydrate (UNH)/nitric acid solutions remaining after the dissolution of LEU targets. Specifically, the focus of this work is the calcination of the uranium waste from 99Mo production using LEU foil targets and the Modified Cintichem Process. Work with our calciner system showed that high furnace temperature, a large vent tube, and a mechanical shield are beneficial for calciner operation. One- and two-step direct calcination processes were evaluated. The high-temperature one-step process led to contamination of the calciner system. The two-step direct calcination process operated stably and resulted in a relatively large amount of material in the calciner cup. Chemically assisted calcination using peroxide was rejected for further work due to the difficulty in handling the products. Chemically assisted calcination using formic acid was rejected due to unstable operation. Chemically assisted calcination using oxalic acid was recommended, although a better understanding of its chemistry is needed. Overall, this work showed that the two-step direct calcination and the in-cup oxalic acid processes are the best approaches for the treatment of the UNH/nitric acid waste solutions remaining from dissolution of LEU targets for 99Mo production.

  5. Theoretical description of hydrogen bonding in oxalic acid dimer and trimer based on the combined extended-transition-state energy decomposition analysis and natural orbitals for chemical valence (ETS-NOCV).

    PubMed

    Mitoraj, Mariusz P; Kurczab, Rafał; Boczar, Marek; Michalak, Artur

    2010-11-01

    In the present study we have analyzed hydrogen bonding in dimer and trimer of oxalic acid, based on a recently proposed charge and energy decomposition scheme (ETS-NOCV). In the case of a dimer, two conformations, α and β, were considered. The deformation density contributions originating from NOCV's revealed that the formation of hydrogen bonding is associated with the electronic charge deformation in both the σ-(Δρ(σ)) and π-networks (Δρ(π)). It was demonstrated that σ-donation is realized by electron transfer from the lone pair of oxygen on one monomer into the empty P*(H-O) orbital of the second oxalic acid fragment. In addition, a covalent contribution is observed by the density transfer from hydrogen of H-O group in one oxalic acid monomer to the oxygen atom of the second fragment. The resonance assisted component (Δρ(π)), is based on the transfer of electron density from the π-orbital localized on the oxygen of OH on one oxalic acid monomer to the oxygen atom of the other fragment. ETS-NOCV allowed to conclude that the σ(O---HO) component is roughly eight times as important as π (RAHB) contribution in terms of energetic estimation. The electrostatic factor (ΔE(elstat)) is equally as important as orbital interaction term (ΔE(orb)). Finally, comparing β-dimer of oxalic acid with trimer we found practically no difference concerning each of the O---HO bonds, neither qualitative nor quantitative.

  6. Contribution of dietary oxalate to urinary oxalate excretion

    NASA Technical Reports Server (NTRS)

    Holmes, R. P.; Goodman, H. O.; Assimos, D. G.

    2001-01-01

    BACKGROUND: The amount of oxalate excreted in urine has a significant impact on calcium oxalate supersaturation and stone formation. Dietary oxalate is believed to make only a minor (10 to 20%) contribution to the amount of oxalate excreted in urine, but the validity of the experimental observations that support this conclusion can be questioned. An understanding of the actual contribution of dietary oxalate to urinary oxalate excretion is important, as it is potentially modifiable. METHODS: We varied the amount of dietary oxalate consumed by a group of adult individuals using formula diets and controlled, solid-food diets with a known oxalate content, determined by a recently developed analytical procedure. Controlled solid-food diets were consumed containing 10, 50, and 250 mg of oxalate/2500 kcal, as well as formula diets containing 0 and 180 mg oxalate/2500 kcal. Changes in the content of oxalate and other ions were assessed in 24-hour urine collections. RESULTS: Urinary oxalate excretion increased as dietary oxalate intake increased. With oxalate-containing diets, the mean contribution of dietary oxalate to urinary oxalate excretion ranged from 24.4 +/- 15.5% on the 10 mg/2500 kcal/day diet to 41.5 +/- 9.1% on the 250 mg/2500 kcal/day diet, much higher than previously estimated. When the calcium content of a diet containing 250 mg of oxalate was reduced from 1002 mg to 391 mg, urinary oxalate excretion increased by a mean of 28.2 +/- 4.8%, and the mean dietary contribution increased to 52.6 +/- 8.6%. CONCLUSIONS: These results suggest that dietary oxalate makes a much greater contribution to urinary oxalate excretion than previously recognized, that dietary calcium influences the bioavailability of ingested oxalate, and that the absorption of dietary oxalate may be an important factor in calcium oxalate stone formation.

  7. The effect of preincubation of seed crystals of uric acid and monosodium urate with undiluted human urine to induce precipitation of calcium oxalate in vitro : implications for urinary stone formation.

    PubMed Central

    Grover, Phulwinder K.; Ryall, Rosemary L.

    2002-01-01

    BACKGROUND: Previous studies demonstrated that crystals of uric acid (UA) and sodium urate (NaU) can induce the precipitation of calcium oxalate (CaOx) from its inorganic metastable solutions, but similar effects have not been unequivocally shown to occur in urine. The aim of this investigation was to determine whether preincubation of these seeds with urine alter their ability to induce deposition of CaOx from solution and thus provide a possible explanation for discrepancy of results obtained from aqueous inorganic solutions and undiluted urine. MATERIALS AND METHODS: The effects of commercial seed crystals of UA, NaU and CaOx (6 mg/100 ml) on CaOx crystallization were compared in a solution with the same crystals that had been preincubated for 3 hours with healthy male urine. A Coulter Counter was used to follow the crystallization and decrease in soluble (14) C-oxalate was measured to determine the deposition of CaOx. The precipitated particles were examined by scanning electron microscopy (SEM). The preincubated seeds were demineralized and proteins released were analyzed by sodium dodecylsulphate polyacrylamide gel electrophoresis (SDS-PAGE). RESULTS: Analysis of (14) C-oxalate data revealed that while treated UA seeds did not affect CaOx deposition, those of NaU and CaOx inhibited the process by 51.9 (p<0.05) and 8.5% (p<0.05) relative to their respective untreated counterparts. Particle size analysis showed that the average modal sizes of particles precipitated in the presence of treated seed crystals of UA, NaU, and CaOx were very similar to those deposited in the presence of their respective untreated controls. These findings were confirmed by SEM which also showed that seed crystals of UA and NaU, untreated and treated, were attached like barnacles upon the surfaces of CaOx crystals which themselves were bigger than those precipitated in the presence of CaOx seeds. SDS-PAGE analysis of the demineralized treated seeds showed that they all selectively

  8. Aquatic photolysis: photolytic redox reactions between goethite and adsorbed organic acids in aqueous solutions

    USGS Publications Warehouse

    Goldberg, M.C.; Cunningham, K.M.; Weiner, Eugene R.

    1993-01-01

    Photolysis of mono and di-carboxylic acids that are adsorbed onto the surface of the iron oxyhydroxide (goethite) results in an oxidation of the organic material and a reduction from Fe(III) to Fe(II) in the iron complex. There is a subsequent release of Fe2+ ions into solution. At constant light flux and constant solution light absorption, the factors responsible for the degree of photolytic reaction include: the number of lattice sites that are bonded by the organic acid; the rate of acid readsorption to the surface during photolysis; the conformation and structure of the organic acid; the degree of oxidation of the organic acid; the presence or absence of an ??-hydroxy group on the acid, the number of carbons in the di-acid chain and the conformation of the di-acid. The ability to liberate Fe(III) at pH 6.5 from the geothite lattice is described by the lyotropic series: tartrate>citrate> oxalate > glycolate > maleate > succinate > formate > fumarate > malonate > glutarate > benzoate = butanoate = control. Although a larger amount of iron is liberated, the series is almost the same at pH 5.5 except that oxalate > citrate and succinate > maleate. A set of rate equations are given that describe the release of iron from the goethite lattice. It was observed that the pH of the solution increases during photolysis if the solutions are not buffered. There is evidence to suggest the primary mechanism for all these reactions is an electron transfer from the organic ligand to the Fe(III) in the complex. Of all the iron-oxyhydroxide materials, crystalline goethite is the least soluble in water; yet, this study indicates that in an aqueous suspension, iron can be liberated from the goethite lattice. Further, it has been shown that photolysis can occur in a multiphase system at the sediment- water interface which results in an oxidation of the organic species and release of Fe2+ to solution where it becomes available for further reaction. ?? 1993.

  9. Electrical conductivity of acidic chloride solutions

    NASA Astrophysics Data System (ADS)

    Majima, Hiroshi; Peters, Ernest; Awakura, Yasuhiro; Park, Sung Kook; Aoki, Masami

    1988-02-01

    The electrical conductivities of aqueous solutions in the system HCl-MCln (where M = K, Na, Mg, Ni, or Cd) were measured at different temperatures. The equivalent electrical conductivity of H+ was calculated on the basis of simple assumptions for these solutions, and show an inverse relationship with water activity in these solutions. The results obtained by varying temperatures, solute ratios, and ionic strength on the electrical conductivity were found to be consistent with a proton jump mechanism for the H+ ion, where the activity of water is the most significant parameter affecting its equivalent conductance, and a viscous (Stokes’ law) drag mechanism (i.e., Walden’s rule is obeyed) for other ions found in acidic solutions.

  10. An oxalyl-CoA dependent pathway of oxalate catabolism plays a role in regulating calcium oxalate crystal accumulation and defending against oxalate-secreting phytopathogens in Medicago truncatula

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Considering the widespread occurrence of oxalate in nature and its broad impact on a host of organisms, it is surprising that so little is known about the turnover of this important acid. In plants, oxalate oxidase is the most well studied enzyme capable of degrading oxalate, but not all plants pos...

  11. ENHANCED CHEMICAL CLEANING: EFFECTIVENESS OF THE UV LAMP TO DECOMPOSE OXALATES

    SciTech Connect

    Ketusky, E.; Huff, T.; Sudduth, C.

    2010-01-19

    Enhanced Chemical Cleaning is a new process scheduled to begin cleaning Savannah River Site High Level Waste Tanks in 2012. It is an improvement over the current chemical cleaning method, in that it minimizes downstream impacts on the High Level Waste System. It is based on a state of the art scale removal process used on the secondary side of nuclear power plants, with modifications to accommodate the unique constraints created by the tanks. Both Enhanced Chemical Cleaning and the scale removal process are founded on dissolving metal oxides/hydroxides using oxalic acid, with subsequent oxalate decomposition via hydroxylation using ozone or peroxide, and UV light as a catalyst. A divergence Enhanced Chemical Cleaning has from nuclear power scale removal is the significantly increased solids concentration during oxalate decomposition. These solids can limit the ability of the UV light to create hydroxyl radicals, either by limiting the ability of the light to penetrate through the solution, or by increasing the fouling rate on the UV light. Both will decrease the overall catalytic effectiveness, thereby decreasing the concentration of formed hydroxyl radicals. The hydroxyl radicals are the driving force behind the oxalate decomposition. To understand the impact of increased solids, testing was performed using a medium pressure UV light inside an ozone supplied Oxalate Decomposition Reactor. Using a dissolved metal sludge simulant with an initial oxalate concentration greater than 12,000 ppm, and an initial pH of about 2.0, the spent acid solution was recirculated through the reactor, while the UV light was allowed to foul. For the first few hours, the oxalate decomposition rate was about 1,300 ppm/hour. After about 3 hours, enough time for the UV lamp to foul, the oxalate decomposition rate decreased to about 500 ppm/hour. The decomposition rate then remained roughly constant for the next 16 hours. Overall, testing showed that the oxalate destruction rate decreased

  12. Evaluation of Oxalate Concentration in the U.S. Spinach Germplasm Collection

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In addition to its high nutrient content, spinach (Spinacia oleracea L.) is also known to have greater amount of oxalic acid than most crops. Oxalic acid may form crystals with minerals to reduce the bioavailability and absorption of calcium and iron in diets, and calcium oxalate may deposit in the...

  13. Impact of oxalate desensitizer combined with ethylene-diamine tetra acetic acid-conditioning on dentin bond strength of one-bottle adhesives during dry bonding

    PubMed Central

    Shafiei, Fereshteh; Doozandeh, Maryam

    2013-01-01

    Background: Elimination of water entrapment in hybrid layer during bonding procedure would increase bonding durability. Aims: This study evaluated the effect of oxalate desensitizer (OX) pretreatment on bond strength of three one-bottle adhesives to ethylene-diamine tetra acetic acid (EDTA)-conditioned dentin under dry bonding. Materials and Methods: Three adhesive systems, One-Step Plus (OS), Optibond Solo Plus (OP) and Adper Single Bond (SB) were bonded on dentin surfaces under four bonding conditions: (1) Wet-bonding on acid-etched dentin, (2) wet bonding on EDTA-conditioned dentin, (3) dry bonding on EDTA-conditioned dentin, (4) dry bonding associated with OX on the EDTA-conditioned dentin. After storage and thermo cycling, shear bond strength test was performed. Data were analyzed using two-way analysis of variance and Tukey tests. Results: Wet bonding with EDTA or acid etching showed similar bond strength for test adhesives. Dry bonding with EDTA significantly decreased the bond strength of OS, but it had no effect on the bonding of OP and SB. OX application in the forth bonding condition, in comparison with the third condition, had a negative effect on the bond strength of OP, but not influence on OS and SB. Conclusions: The use of an OX on EDTA-conditioned dentin compromised the bonding efficacy of OS and OP under dry bonding but compatible for SB. PMID:23833461

  14. Electrochemical synthesis and characterization of zinc oxalate nanoparticles

    SciTech Connect

    Shamsipur, Mojtaba; Roushani, Mahmoud; Pourmortazavi, Seied Mahdi

    2013-03-15

    Highlights: ► Synthesis of zinc oxalate nanoparticles via electrolysis of a zinc plate anode in sodium oxalate solutions. ► Design of a Taguchi orthogonal array to identify the optimal experimental conditions. ► Controlling the size and shape of particles via applied voltage and oxalate concentration. ► Characterization of zinc oxalate nanoparticles by SEM, UV–vis, FT-IR and TG–DTA. - Abstract: A rapid, clean and simple electrodeposition method was designed for the synthesis of zinc oxalate nanoparticles. Zinc oxalate nanoparticles in different size and shapes were electrodeposited by electrolysis of a zinc plate anode in sodium oxalate aqueous solutions. It was found that the size and shape of the product could be tuned by electrolysis voltage, oxalate ion concentration, and stirring rate of electrolyte solution. A Taguchi orthogonal array design was designed to identify the optimal experimental conditions. The morphological characterization of the product was carried out by scanning electron microscopy. UV–vis and FT-IR spectroscopies were also used to characterize the electrodeposited nanoparticles. The TG–DTA studies of the nanoparticles indicated that the main thermal degradation occurs in two steps over a temperature range of 350–430 °C. In contrast to the existing methods, the present study describes a process which can be easily scaled up for the production of nano-sized zinc oxalate powder.

  15. Sustainable Soil Washing: Shredded Card Filtration of Potentially Toxic Elements after Leaching from Soil Using Organic Acid Solutions.

    PubMed

    Ash, Christopher; Drábek, Ondřej; Tejnecký, Václav; Jehlička, Jan; Michon, Ninon; Borůvka, Luboš

    2016-01-01

    Shredded card (SC) was assessed for use as a sorbent of potentially toxic elements (PTE) carried from contaminated soil in various leachates (oxalic acid, formic acid, CaCl2, water). We further assessed SC for retention of PTE, using acidified water (pH 3.4). Vertical columns and a peristaltic pump were used to leach PTE from soils (O and A/B horizons) before passing through SC. Sorption onto SC was studied by comparing leachates, and by monitoring total PTE contents on SC before and after leaching. SC buffers against acidic soil conditions that promote metals solubility; considerable increases in solution pH (+4.49) were observed. Greatest differences in solution PTE content after leaching with/without SC occurred for Pb. In oxalic acid, As, Cd, Pb showed a high level of sorption (25, 15, and 58x more of the respective PTE in leachates without SC). In formic acid, Pb sorption was highly efficient (219x more Pb in leachate without SC). In water, only Pb showed high sorption (191x more Pb in leachate without SC). In desorption experiments, release of PTE from SC varied according to the source of PTE (organic/mineral soil), and type of solvent used. Arsenic was the PTE most readily leached in desorption experiments. Low As sorption from water was followed by fast release (70% As released from SC). A high rate of Cd sorption from organic acid solutions was followed by strong retention (~12% Cd desorption). SC also retained Pb after sorption from water, with subsequent losses of ≤8.5% of total bound Pb. The proposed use of this material is for the filtration of PTE from extract solution following soil washing. Low-molecular-mass organic acids offer a less destructive, biodegradable alternative to strong inorganic acids for soil washing.

  16. Sustainable Soil Washing: Shredded Card Filtration of Potentially Toxic Elements after Leaching from Soil Using Organic Acid Solutions

    PubMed Central

    Ash, Christopher; Drábek, Ondřej; Tejnecký, Václav; Jehlička, Jan; Michon, Ninon; Borůvka, Luboš

    2016-01-01

    Shredded card (SC) was assessed for use as a sorbent of potentially toxic elements (PTE) carried from contaminated soil in various leachates (oxalic acid, formic acid, CaCl2, water). We further assessed SC for retention of PTE, using acidified water (pH 3.4). Vertical columns and a peristaltic pump were used to leach PTE from soils (O and A/B horizons) before passing through SC. Sorption onto SC was studied by comparing leachates, and by monitoring total PTE contents on SC before and after leaching. SC buffers against acidic soil conditions that promote metals solubility; considerable increases in solution pH (+4.49) were observed. Greatest differences in solution PTE content after leaching with/without SC occurred for Pb. In oxalic acid, As, Cd, Pb showed a high level of sorption (25, 15, and 58x more of the respective PTE in leachates without SC). In formic acid, Pb sorption was highly efficient (219x more Pb in leachate without SC). In water, only Pb showed high sorption (191x more Pb in leachate without SC). In desorption experiments, release of PTE from SC varied according to the source of PTE (organic/mineral soil), and type of solvent used. Arsenic was the PTE most readily leached in desorption experiments. Low As sorption from water was followed by fast release (70% As released from SC). A high rate of Cd sorption from organic acid solutions was followed by strong retention (~12% Cd desorption). SC also retained Pb after sorption from water, with subsequent losses of ≤8.5% of total bound Pb. The proposed use of this material is for the filtration of PTE from extract solution following soil washing. Low-molecular-mass organic acids offer a less destructive, biodegradable alternative to strong inorganic acids for soil washing. PMID:26900684

  17. Arthritis associated with calcium oxalate crystals in an anephric patient treated with peritoneal dialysis

    SciTech Connect

    Rosenthal, A.; Ryan, L.M.; McCarty, D.J.

    1988-09-02

    The authors report a case of calcium oxalate arthropathy in a woman undergoing intermittent peritoneal dialysis who was not receiving pharmacologic doses of ascorbic acid. She developed acute arthritis, with calcium oxalate crystals in Heberden's and Bouchard's nodes, a phenomenon previously described in gout. Intermittent peritoneal dialysis may be less efficient than hemodialysis in clearing oxalate, and physicians should now consider calcium oxalate-associated arthritis in patients undergoing peritoneal dialysis who are not receiving large doses of ascorbic acid.

  18. Uranyl peroxide oxalate cage and core-shell clusters containing 50 and 120 uranyl ions.

    PubMed

    Ling, Jie; Qiu, Jie; Burns, Peter C

    2012-02-20

    Cage clusters built from uranyl hexagonal bipyramids and oxalate ligands crystallize from slightly acidic aqueous solution under ambient conditions, facilitating structure analysis. Each cluster contains uranyl ions coordinated by peroxo ligands in a bidentate configuration. Uranyl ions are bridged by shared peroxo ligands, oxalate ligands, or through hydroxyl groups. U(50)Ox(20) contains 50 uranyl ions and 20 oxalate groups and is a topological derivative of the U(50) cage cluster that has a fullerene topology. U(120)Ox(90) contains 120 uranyl ions and 90 oxalate groups and is the largest and highest mass cluster containing uranyl ions that has been reported. It has a core-shell structure, in which the inner shell (core) consists of a cluster of 60 uranyl ions and 30 oxalate groups, identical to U(60)Ox(30), with a fullerene topology. The outer shell contains 12 identical units that each consist of five uranyl hexagonal bipyramids that are linked to form a ring (topological pentagon), with each uranyl ion also coordinated by a side-on nonbridging oxalate group. The five-membered rings of the inner and outer shells (the topological pentagons) are in correspondence and are linked through K cations. The inner shell topology has therefore templated the location of the outer shell rings, and the K counterions assume a structure-directing role. Small-angle X-ray scattering data demonstrated U(50)Ox(20) remains intact in aqueous solution upon dissolution. In the case of clusters of U(120)Ox(90), the scattering data for dissolved crystals indicates the U(60)Ox(30) core persists in solution, although the outer rings of uranyl bipyramids contained in the U(120)Ox(90) core-shell cluster appear to detach from the cluster when crystals are dissolved in water.

  19. Metabolism of Fructose to Oxalate and Glycolate

    PubMed Central

    Knight, J.; Assimos, D. G.; Easter, L.; Holmes, R. P.

    2011-01-01

    Much attention has been recently directed at fructose consumption because of its association with obesity and subsequent development of chronic diseases. It was recently reported that an increased fructose intake increases the risk of forming kidney stones. It was postulated that fructose consumption may increase urinary oxalate, a risk factor for calcium oxalate kidney stone disease. However, conflicting results have been obtained in human studies examining the relationship between fructose metabolism and oxalate synthesis. To test whether fructose intake influences urinary excretions impacting kidney stone risk, healthy subjects consumed diets controlled in their contents of fructose, oxalate, calcium, and other nutrients. Subjects consumed diets containing 4, 13, and 21% of calories as fructose in a randomized order. No changes in the excretions of oxalate, calcium, and uric acid were observed. In vitro investigations with cultured liver cells incubated with 13C-labeled sugars indicated that neither fructose nor glucose was converted to oxalate by these cells. Fructose metabolism accounted for 12.4 ± 1.6% of the glycolate detected in the culture medium and glucose 6.4 ± 0.9%. Our results suggest that mechanisms for stone risk associated with fructose intake may lie in factors other than those affecting the major stone risk parameters in urine. PMID:20842614

  20. Specific detection of pathological three-repeat tau after pretreatment with potassium permanganate and oxalic acid in PSP/CBD brains.

    PubMed

    Uchihara, Toshiki; Nakamura, Ayako; Shibuya, Katsuhiko; Yagishita, Saburo

    2011-03-01

    Immunohistochemisty with RD3, a monoclonal antibody specific for three-repeat (3R) tau, is sometimes hampered by diffuse neuronal staining on formalin-fixed, paraffin-embedded sections pretreated with formic acid and heating. Additional pretreatment with potassium permanganate followed by oxalic acid completely eliminated this diffuse RD3-immunoreactivity (IR) in neurons. Furthermore, this additional pretreatment uniformly enhanced RD3-IR, as well as RD4-IR, a monoclonal antibody specific for four-repeat (4R) tau, on pathological deposits with tau IR. This enhanced sensitivity and specificity may allow more reliable identification of 3R and 4R tau in pathological deposits, which may be variable dependent on disease and regions. Cerebral cortex and midbrain from 8 patients [5 progressive supranuclear palsy (PSP) and 3 corticobasal degeneration (CBD)] were screened for RD3- and RD4-IR with this improved procedure. In addition to RD4-positive structures found both in cerebral cortex and brainstem, RD3-positive neurofibrillary tangles (NFTs) were also found in midbrain in 7 of these 8 cases but not in the cortex. Multi-labeling study demonstrated that most of RD3-negative neurons were positive for RD4. This reliable demonstration of pathological 3R tau deposits in the brainstem of PSP/CBD, so far presumably characterized by deposition of 4R tau, is useful to map tau-positive lesions according to their biochemical composition.

  1. Speciation in aqueous solutions of nitric acid.

    PubMed

    Hlushak, S; Simonin, J P; De Sio, S; Bernard, O; Ruas, A; Pochon, P; Jan, S; Moisy, P

    2013-02-28

    In this study, speciation in aqueous solutions of nitric acid at 25 °C was assessed in two independent ways. First, Raman experiments were carried out and interpreted in terms of free nitrate ions, ion pairs and neutral HNO(3) molecules. In parallel, a model was developed to account for the formation of these two kinds of pairs. It was based on an extension of the binding mean spherical approximation (BiMSA), or associative MSA (AMSA), in which the size and the charge of the ions in the chemical pair may differ from those of the free ions. A simultaneous fit of the osmotic coefficient and of the proportion of free ions (obtained from Raman spectroscopy experiments) led to an estimation of the speciation in nitric acid solutions. The result obtained using this procedure was compared with the estimation obtained from the Raman experiments.

  2. Alkaline earth cation extraction from acid solution

    DOEpatents

    Dietz, Mark; Horwitz, E. Philip

    2003-01-01

    An extractant medium for extracting alkaline earth cations from an aqueous acidic sample solution is described as are a method and apparatus for using the same. The separation medium is free of diluent, free-flowing and particulate, and comprises a Crown ether that is a 4,4'(5')[C.sub.4 -C.sub.8 -alkylcyclohexano]18-Crown-6 dispersed on an inert substrate material.

  3. Wet oxidation of salicylic acid solutions.

    PubMed

    Collado, Sergio; Garrido, Laura; Laca, Adriana; Diaz, Mario

    2010-11-15

    Salicylic acid is a frequent pollutant in several industrial wastewaters. Uncatalyzed wet air oxidation, which is a promising technique for the treatment of phenolic effluents, has not been analyzed yet for the removal of salicylic acid. The effect of different conditions of pH (1.3-12.3), pressure (1.0-4.1 MPa), temperature (413-443 K), and initial concentrations (1.45-14.50 mM) on the wet oxidation of salicylate/salicylic acid solutions have here been investigated. The pH value of the reaction media was found to be a key parameter for the rate of the oxidation process with an optimum at pH 3.1, when the concentrations of salicylic acid and salicylate were similar. The oxidation reaction followed pseudofirst-order kinetics with respect to salicylic acid and 0.82 order with respect to dissolved oxygen. Additionally, the evolution of the color during the wet oxidation was analyzed and discussed in relation with the formation of intermediate compounds. Then, a reaction pathway for the noncatalytic wet oxidation of the salicylic acid was proposed.

  4. A one-pot gold seed-assisted synthesis of gold/platinum wire nanoassemblies and their enhanced electrocatalytic activity for the oxidation of oxalic acid

    NASA Astrophysics Data System (ADS)

    Bai, Juan; Fang, Chun-Long; Liu, Zong-Huai; Chen, Yu

    2016-01-01

    Three-dimensional (3D) noble metal nanoassemblies composed of one-dimensional (1D) nanowires have been attracting much interest due to the unique physical and chemical properties of 1D nanowires as well as the particular interconnected open-pore structure of 3D nanoassemblies. In this work, well-defined Au/Pt wire nanoassemblies were synthesized by using a facile NaBH4 reduction method in the presence of a branched form of polyethyleneimine (PEI). A study of the growth mechanism indicated the morphology of the final product to be highly related to the molecular structure of the polymeric amine. Also, the preferred Pt-on-Pt deposition contributed to the formation of the 1D Pt nanowires. The Au/Pt wire nanoassemblies were functionalized with PEI at the same time that these nanoassemblies were synthesized due to the strong N-Pt bond. The chemically functionalized Au/Pt wire nanoassemblies exhibited better electrocatalytic activity for the electro-oxidation of oxalic acid than did commercial Pt black.Three-dimensional (3D) noble metal nanoassemblies composed of one-dimensional (1D) nanowires have been attracting much interest due to the unique physical and chemical properties of 1D nanowires as well as the particular interconnected open-pore structure of 3D nanoassemblies. In this work, well-defined Au/Pt wire nanoassemblies were synthesized by using a facile NaBH4 reduction method in the presence of a branched form of polyethyleneimine (PEI). A study of the growth mechanism indicated the morphology of the final product to be highly related to the molecular structure of the polymeric amine. Also, the preferred Pt-on-Pt deposition contributed to the formation of the 1D Pt nanowires. The Au/Pt wire nanoassemblies were functionalized with PEI at the same time that these nanoassemblies were synthesized due to the strong N-Pt bond. The chemically functionalized Au/Pt wire nanoassemblies exhibited better electrocatalytic activity for the electro-oxidation of oxalic acid than

  5. Reduction of Oxalate Levels in Tomato Fruit and Consequent Metabolic Remodeling Following Overexpression of a Fungal Oxalate Decarboxylase1[W

    PubMed Central

    Chakraborty, Niranjan; Ghosh, Rajgourab; Ghosh, Sudip; Narula, Kanika; Tayal, Rajul; Datta, Asis; Chakraborty, Subhra

    2013-01-01

    The plant metabolite oxalic acid is increasingly recognized as a food toxin with negative effects on human nutrition. Decarboxylative degradation of oxalic acid is catalyzed, in a substrate-specific reaction, by oxalate decarboxylase (OXDC), forming formic acid and carbon dioxide. Attempts to date to reduce oxalic acid levels and to understand the biological significance of OXDC in crop plants have met with little success. To investigate the role of OXDC and the metabolic consequences of oxalate down-regulation in a heterotrophic, oxalic acid-accumulating fruit, we generated transgenic tomato (Solanum lycopersicum) plants expressing an OXDC (FvOXDC) from the fungus Flammulina velutipes specifically in the fruit. These E8.2-OXDC fruit showed up to a 90% reduction in oxalate content, which correlated with concomitant increases in calcium, iron, and citrate. Expression of OXDC affected neither carbon dioxide assimilation rates nor resulted in any detectable morphological differences in the transgenic plants. Comparative proteomic analysis suggested that metabolic remodeling was associated with the decrease in oxalate content in transgenic fruit. Examination of the E8.2-OXDC fruit proteome revealed that OXDC-responsive proteins involved in metabolism and stress responses represented the most substantially up- and down-regulated categories, respectively, in the transgenic fruit, compared with those of wild-type plants. Collectively, our study provides insights into OXDC-regulated metabolic networks and may provide a widely applicable strategy for enhancing crop nutritional value. PMID:23482874

  6. Solubility of Plutonium (IV) Oxalate During Americium/Curium Pretreatment

    SciTech Connect

    Rudisill, T.S.

    1999-08-11

    Approximately 15,000 L of solution containing isotopes of americium and curium (Am/Cm) will undergo stabilization by vitrification at the Savannah River Site (SRS). Prior to vitrification, an in-tank pretreatment will be used to remove metal impurities from the solution using an oxalate precipitation process. Material balance calculations for this process, based on solubility data in pure nitric acid, predict approximately 80 percent of the plutonium in the solution will be lost to waste. Due to the uncertainty associated with the plutonium losses during processing, solubility experiments were performed to measure the recovery of plutonium during pretreatment and a subsequent precipitation process to prepare a slurry feed for a batch melter. A good estimate of the plutonium content of the glass is required for planning the shipment of the vitrified Am/Cm product to Oak Ridge National Laboratory (ORNL).The plutonium solubility in the oxalate precipitation supernate during pretreatment was 10 mg/mL at 35 degrees C. In two subsequent washes with a 0.25M oxalic acid/0.5M nitric acid solution, the solubility dropped to less than 5 mg/mL. During the precipitation and washing steps, lanthanide fission products in the solution were mostly insoluble. Uranium, and alkali, alkaline earth, and transition metal impurities were soluble as expected. An elemental material balance for plutonium showed that greater than 94 percent of the plutonium was recovered in the dissolved precipitate. The recovery of the lanthanide elements was generally 94 percent or higher except for the more soluble lanthanum. The recovery of soluble metal impurities from the precipitate slurry ranged from 15 to 22 percent. Theoretically, 16 percent of the soluble oxalates should have been present in the dissolved slurry based on the dilution effects and volumes of supernate and wash solutions removed. A trace level material balance showed greater than 97 percent recovery of americium-241 (from the beta dec

  7. EPR Spin Trapping of an Oxalate-Derived Free Radical in the Oxalate Decarboxylase Reaction

    PubMed Central

    Imaram, Witcha; Saylor, Benjamin T.; Centonze, Christopher P.; Richards, Nigel G. J.; Angerhofer, Alexander

    2011-01-01

    EPR spin trapping experiments on bacterial oxalate decarboxylase from Bacillus subtilis under turn-over conditions are described. The use of doubly 13C-labeled oxalate leads to a characteristic splitting of the observed radical adducts using the spin trap N-tert-butyl-α-phenylnitrone linking them directly to the substrate. The radical was identified as the carbon dioxide radical anion which is a key intermediate in the hypothetical reaction mechanism of both decarboxylase and oxidase activities. X-ray crystallography had identified a flexible loop, SENS161-4, which acts as a lid to the putative active site. Site directed mutagenesis of the hinge amino acids, S161 and T165 was explored and showed increased radical trapping yields compared to the wild type. In particular, T165V shows approximately ten times higher radical yields while at the same time its decarboxylase activity was reduced by about a factor of ten. This mutant lacks a critical H-bond between T165 and R92 resulting in compromised control over its radical chemistry allowing the radical intermediate to leak into the surrounding solution. PMID:21277974

  8. Trivalent Chromium Solutions for Sealing Anodized Aluminum

    DTIC Science & Technology

    1994-12-20

    the comparatively innocuous trivalent form before acid , chromic acid , oxalic acid , sulfophthalic acid , boric disposal. This method is expensive and...or had only faint anodized aluminum substrates by immersion in a mildly traces of corrosion . All 7075-T6 panels provided with acid solution containing...alloy panels wereP 10 anodized in 15% (weight) sulfuric acid solution for 30 To produce improved corrosion resistance on anod- minutes at 21 C. at 18

  9. ADVANCED OXIDATION: OXALATE DECOMPOSITION TESTING WITH OZONE

    SciTech Connect

    Ketusky, E.; Subramanian, K.

    2012-02-29

    At the Savannah River Site (SRS), oxalic acid is currently considered the preferred agent for chemically cleaning the large underground Liquid Radioactive Waste Tanks. It is applied only in the final stages of emptying a tank when generally less than 5,000 kg of waste solids remain, and slurrying based removal methods are no-longer effective. The use of oxalic acid is preferred because of its combined dissolution and chelating properties, as well as the fact that corrosion to the carbon steel tank walls can be controlled. Although oxalic acid is the preferred agent, there are significant potential downstream impacts. Impacts include: (1) Degraded evaporator operation; (2) Resultant oxalate precipitates taking away critically needed operating volume; and (3) Eventual creation of significant volumes of additional feed to salt processing. As an alternative to dealing with the downstream impacts, oxalate decomposition using variations of ozone based Advanced Oxidation Process (AOP) were investigated. In general AOPs use ozone or peroxide and a catalyst to create hydroxyl radicals. Hydroxyl radicals have among the highest oxidation potentials, and are commonly used to decompose organics. Although oxalate is considered among the most difficult organic to decompose, the ability of hydroxyl radicals to decompose oxalate is considered to be well demonstrated. In addition, as AOPs are considered to be 'green' their use enables any net chemical additions to the waste to be minimized. In order to test the ability to decompose the oxalate and determine the decomposition rates, a test rig was designed, where 10 vol% ozone would be educted into a spent oxalic acid decomposition loop, with the loop maintained at 70 C and recirculated at 40L/min. Each of the spent oxalic acid streams would be created from three oxalic acid strikes of an F-area simulant (i.e., Purex = high Fe/Al concentration) and H-area simulant (i.e., H area modified Purex = high Al/Fe concentration) after nearing

  10. Acidities of Water and Methanol in Aqueous Solution and DMSO

    ERIC Educational Resources Information Center

    Gao, Daqing

    2009-01-01

    The relative acidities of water and methanol have been a nagging issue. In gas phase, methanol is more acidic than water by 36.0 kJ/mol; however, in aqueous solution, the acidities of methanol and water are almost identical. The acidity of an acid in solution is determined by both the intrinsic gas-phase ionization Gibbs energy and the solvent…

  11. Stability-indicating RP-HPLC method for the simultaneous determination of escitalopram oxalate and clonazepam.

    PubMed

    Kakde, Rajendra B; Satone, Dinesh D; Gadapayale, Kamalesh K; Kakde, Megha G

    2013-07-01

    The objective of the current study was to develop a validated, specific stability-indicating reversed-phase liquid chromatographic (LC) method for the quantitative determination of escitalopram oxalate and clonazepam and their related substances in bulk drugs and pharmaceutical dosage forms in the presence of degradation products. Forced degradation studies were performed on the pure drugs of escitalopram oxalate and clonazepam, as per the stress conditions prescribed by the International Conference on Harmonization (ICH) using acid, base, oxidation, thermal stress and photolytic degradation to show the stability-indicating power of the method. Significant degradation was observed during acid and alkaline hydrolysis and no degradation was observed in other stress conditions. The chromatographic method was optimized using the samples generated from forced degradation studies. Good resolution between the peaks corresponded to the active pharmaceutical ingredients, escitalopram oxalate and clonazepam, and degradation products from the analyte were achieved on an ODS Hypersil C18 column (250 × 4.6 mm) using a mobile phase consisting of a mixture of acetonitrile-50 mM phosphate buffer + 10 mM triethylamine (70:30, v/v). The detection was conducted at 268 nm. The limit of detection and the limit of quantitation for escitalopram oxalate and clonazepam were established. The stress test solutions were assayed against the qualified working standards of escitalopram oxalate and clonazepam, which indicated that the developed LC method was stability-indicating. Validation of the developed LC method was conducted as per ICH requirements. The developed LC method was found to be suitable to check the quality of bulk samples of escitalopram oxalate and clonazepam.

  12. Heterogeneous catalysis by solid superacids--14. Perfluorinated resinsulfonic acid (nafion-h) catalyzed Friedel-crafts alkylation of toluene and phenol with alkyl chloroformates and oxalates

    SciTech Connect

    Olah, G.A.; Meidar, D.; Malhotra, R.; Olah, J.A.; Narang, S.C.

    1980-01-01

    Product distributions obtained in the alkylation of toluene with methyl, ethyl, and isopropyl chloroformate and dimethyl oxalate and of phenol with methyl and ethyl chloroformate and dimethyl- and diethyloxalate.

  13. Determining the Structure of Oxalate Anion Using Infrared and Raman Spectroscopy Coupled with Gaussian Calculations

    ERIC Educational Resources Information Center

    Peterson, Karen I.; Pullman, David P.

    2016-01-01

    A laboratory project for the upper-division physical chemistry laboratory is described, and it combines IR and Raman spectroscopies with Gaussian electronic structure calculations to determine the structure of the oxalate anion in solid alkali oxalates and in aqueous solution. The oxalate anion has two limiting structures whose vibrational spectra…

  14. Concentrations and stable carbon isotope compositions of oxalic acid and related SOA in Beijing before, during, and after the 2014 APEC

    NASA Astrophysics Data System (ADS)

    Wang, Jiayuan; Wang, Gehui; Gao, Jian; Wang, Han; Ren, Yanqin; Li, Jianjun; Zhou, Bianhong; Wu, Can; Zhang, Lu; Wang, Shulan; Chai, Fahe

    2017-01-01

    To ensure good air quality for the 2014 Asia-Pacific Economic Cooperation (APEC) summit, stringent emission controls were implemented in Beijing and its surrounding regions, leading to a significant reduction in PM2.5 loadings. To investigate the impact of the emission controls on aerosol chemistry, high-volume PM2.5 samples were collected in Beijing from 8 October to 24 November 2014 and determined for secondary inorganic aerosols (SIA, i.e., SO42-, NO3-, and NH4+), dicarboxylic acids, keto-carboxylic acid, and α-dicarbonyls, as well as stable carbon isotope composition of oxalic acid (C2). Our results showed that SIA, C2, and related secondary organic aerosols in PM2.5 during APEC were 2-4 times lower than those before APEC, which is firstly ascribed to the strict emission control measures and secondly attributed to the relatively colder and drier conditions during the event that are unfavorable for secondary aerosol production.C2 in the polluted air masses, which mostly occurred before APEC, are abundant and enriched in 13C. On the contrary, C2 in the clean air masses, which mostly occurred during APEC, is much less abundant but still enriched in 13C. In the mixed type of clean and polluted air masses, which mostly occurred after APEC, C2 is lower than that before APEC but higher than that during APEC and enriched in lighter 12C. A comparison on chemical composition of fine particles and δ13C values of C2 in two events that are characterized by high loadings of PM2.5 further showed that after APEC SIA and the total detected organic compounds (TDOC) are much less abundant and fine aerosols are enriched with primary organics and relatively fresh, compared with those before APEC.

  15. A one-pot gold seed-assisted synthesis of gold/platinum wire nanoassemblies and their enhanced electrocatalytic activity for the oxidation of oxalic acid.

    PubMed

    Bai, Juan; Fang, Chun-Long; Liu, Zong-Huai; Chen, Yu

    2016-02-07

    Three-dimensional (3D) noble metal nanoassemblies composed of one-dimensional (1D) nanowires have been attracting much interest due to the unique physical and chemical properties of 1D nanowires as well as the particular interconnected open-pore structure of 3D nanoassemblies. In this work, well-defined Au/Pt wire nanoassemblies were synthesized by using a facile NaBH4 reduction method in the presence of a branched form of polyethyleneimine (PEI). A study of the growth mechanism indicated the morphology of the final product to be highly related to the molecular structure of the polymeric amine. Also, the preferred Pt-on-Pt deposition contributed to the formation of the 1D Pt nanowires. The Au/Pt wire nanoassemblies were functionalized with PEI at the same time that these nanoassemblies were synthesized due to the strong N-Pt bond. The chemically functionalized Au/Pt wire nanoassemblies exhibited better electrocatalytic activity for the electro-oxidation of oxalic acid than did commercial Pt black.

  16. Analysis of nanopore arrangement and structural features of anodic alumina layers formed by two-step anodizing in oxalic acid using the dedicated executable software

    NASA Astrophysics Data System (ADS)

    Zaraska, Leszek; Stępniowski, Wojciech J.; Sulka, Grzegorz D.; Ciepiela, Eryk; Jaskuła, Marian

    2014-02-01

    Anodic porous alumina layers were fabricated by a two-step self-organized anodization in 0.3 M oxalic acid under various anodizing potentials ranging from 30 to 60 V at two different temperatures (10 and 17 ∘C). The effect of anodizing conditions on structural features and pore arrangement of AAO was investigated in detail by using the dedicated executable publication combined with ImageJ software. With increasing anodizing potential, a linear increase of the average pore diameter, interpore distance, wall thickness and barrier layer thickness, as well as a decrease of the pore density, were observed. In addition, the higher pore diameter and porosity values were obtained for samples anodized at the elevated temperature, independently of the anodizing potential. A degree of pore order was investigated on the basis of Delaunay triangulations (defect maps) and calculation of pair distribution or angle distribution functions (PDF or ADF), respectively. All methods confirmed that in order to obtain nanoporous alumina with the best, hexagonal pore arrangement, the potential of 40 V should be applied during anodization. It was confirmed that the dedicated executable publication can be used to a fast and complex analysis of nanopore arrangement and structural features of nanoporous oxide layers.

  17. Surface aggregation of urinary proteins and aspartic acid-rich peptides on the faces of calcium oxalate monohydrate investigated by in situ force microscopy

    SciTech Connect

    Weaver, M L; Qiu, S R; Hoyer, J R; Casey, W H; Nancollas, G H; De Yoreo, J J

    2008-05-28

    The growth of calcium oxalate monohydrate in the presence of Tamm-Horsfall protein (THP), osteopontin (OPN), and the 27-residue synthetic peptides (DDDS){sub 6}DDD and (DDDG){sub 6}DDD [where D = aspartic acid and X = S (serine) or G (glycine)] was investigated via in situ atomic force microscopy (AFM). The results show that these three growth modulators create extensive deposits on the crystal faces. Depending on the modulator and crystal face, these deposits can occur as discrete aggregates, filamentary structures, or uniform coatings. These proteinaceous films can lead to either the inhibition or increase of the step speeds (with respect to the impurity-free system) depending on a range of factors that include peptide or protein concentration, supersaturation and ionic strength. While THP and the linear peptides act, respectively, to exclusively increase and inhibit growth on the (-101) face, both exhibit dual functionality on the (010) face, inhibiting growth at low supersaturation or high modulator concentration and accelerating growth at high supersaturation or low modulator concentration. Based on analyses of growth morphologies and dependencies of step speeds on supersaturation and protein or peptide concentration, we argue for a picture of growth modulation that accounts for the observations in terms of the strength of binding to the surfaces and steps and the interplay of electrostatic and solvent-induced forces at crystal surface.

  18. Expanding the applications of the ilmenite mineral to the preparation of nanostructures: TiO2 nanorods and their photocatalytic properties in the degradation of oxalic acid.

    PubMed

    Tao, Tao; Chen, Ying; Zhou, Dan; Zhang, Hongzhou; Liu, Sanly; Amal, Rose; Sharma, Neeraj; Glushenkov, Alexey M

    2013-01-14

    The mineral ilmenite is one of the most abundant ores in the Earth's crust and it is the main source for the industrial production of bulk titanium oxide. At the same time, methods to convert ilmenite into nanostructures of TiO(2) (which are required for new advanced applications, such as solar cells, batteries, and photocatalysts) have not been explored to any significant extent. Herein, we describe a simple and effective method for the preparation of rutile TiO(2) nanorods from ball-milled ilmenite. These nanorods have small dimensions (width: 5-20 nm, length: 50-100 nm, thickness: 2-5 nm) and possess large specific surface areas (up to 97 m(2)  g(-1)). Dissolution/hydrolysis/precipitation is proposed as a growth mechanism. The nanorods were found to have attractive photocatalytic properties in the degradation of oxalic acid. Their photocatalytic activity is close to that of the benchmark Degussa P25 material and better than that of a commercial high-surface-area rutile powder.

  19. Genomic evaluation of oxalate-degrading transgenic soybean in response to Sclerotinia sclerotiorum infection

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Oxalate oxidases catalyze the degradation of oxalic acid (OA). Highly resistant transgenic soybean carrying an oxalate oxidase (OxO) gene and its susceptible parent soybean line, AC Colibri, were tested for genome-wide gene expression in response to the necrotrophic, OA producing pathogen Sclerotini...

  20. Reactive solute transport in acidic streams

    USGS Publications Warehouse

    Broshears, R.E.

    1996-01-01

    Spatial and temporal profiles of Ph and concentrations of toxic metals in streams affected by acid mine drainage are the result of the interplay of physical and biogeochemical processes. This paper describes a reactive solute transport model that provides a physically and thermodynamically quantitative interpretation of these profiles. The model combines a transport module that includes advection-dispersion and transient storage with a geochemical speciation module based on MINTEQA2. Input to the model includes stream hydrologic properties derived from tracer-dilution experiments, headwater and lateral inflow concentrations analyzed in field samples, and a thermodynamic database. Simulations reproduced the general features of steady-state patterns of observed pH and concentrations of aluminum and sulfate in St. Kevin Gulch, an acid mine drainage stream near Leadville, Colorado. These patterns were altered temporarily by injection of sodium carbonate into the stream. A transient simulation reproduced the observed effects of the base injection.

  1. Determination of fluoride and oxalate using the indicator reaction of Zr(IV) with methylthymol blue adsorbed on silica gel.

    PubMed

    Zaporozhets, Olga A; Tsyukalo, Lyudmila Ye

    2007-07-30

    Solid-phase spectrophotometric and visual test-methods of fluoride and oxalate determination are proposed. The methods are based on the competitive reactions of ZrOCl2 with methylthymol blue immobilized on silica gel and fluoride or oxalate in solution. Absorbance of the solid-phase reagent at 590 nm decreases with the growth of fluoride and oxalate contents in solution. The developed methods demonstrate high selectivity. The interference of Bi(III) and SO4(2-), PO4(3-) is eliminated by the addition of 0.01 mol L(-1) solution of ascorbic acid and 0.01 mol L(-1) of BaCl2, respectively. To eliminate the fluoride interference with oxalate determination 1x10(-3) mol L(-1) solution of Ca(NO3)2 at pH 1.5 was added. The anions of the organic acids were destructed prior to F- determination by ultrasonic exposition (44 kHz, intensity of < or = 10 W cm(-2) for 3 min). The proposed methods were applied to the analysis of mineral water, toothpaste and biological fluids.

  2. Ammonium reduces oxalate accumulation in different spinach (Spinacia oleracea L.) genotypes by inhibiting root uptake of nitrate.

    PubMed

    Liu, Xiaoxia; Lu, Lingli; Chen, Qiuhui; Ding, Wenya; Dai, Peibin; Hu, Yan; Yu, Yan; Jin, Chongwei; Lin, Xianyong

    2015-11-01

    Excessive accumulation of oxalate negatively affects nutritional value of many vegetables, such as spinach (Spinacia oleracea L.). Mixed solution of ammonium and nitrate could effectively reduce oxalate accumulation, while the mechanism involved remains unknown. High (Heizhenzhu) and low (Weilv) oxalate-accumulated spinach genotypes were used in this study to investigate the association of oxalate accumulation and root uptake of nitrogen. Exposure of increasing nitrate or mixed-nitrogen (nitrate:ammonium = 1:1) significantly increased leaf total and soluble oxalate contents. In contrast, increasing ammonium did not result in elevation of leaf oxalate. Correlation analysis confirmed that leaf oxalate accumulation was positively associated with root uptake of nitrate but not ammonium. Moreover, addition of ammonium significantly reduced nitrate uptake rate, and subsequently decreased leaf oxalate accumulation. The results suggest that oxalate synthesis in spinach leaves is associated with its root uptake of nitrate, and ammonium is able to reduce oxalate accumulation by inhibiting uptake of nitrate.

  3. Process for the extraction of strontium from acidic solutions

    DOEpatents

    Horwitz, E.P.; Dietz, M.L.

    1993-01-01

    The invention is a process for selectively extracting strontium values from aqueous nitric acid waste solutions containing these and other fission product values. The extractant solution is a macrocyclic polyether in an aliphatic hydrocarbon diluent containing a phase modifier. The process will selectively extract strontium values from nitric acid solutions which are up to 6 molar in nitric acid.

  4. Process for the extraction of strontium from acidic solutions

    DOEpatents

    Horwitz, E.P.; Dietz, M.L.

    1994-09-06

    The invention is a process for selectively extracting strontium values from aqueous nitric acid waste solutions containing these and other fission product values. The extractant solution is a macrocyclic polyether in an aliphatic hydrocarbon diluent containing a phase modifier. The process will selectively extract strontium values from nitric acid solutions which are up to 6 molar in nitric acid. 4 figs.

  5. Process for the extraction of strontium from acidic solutions

    DOEpatents

    Horwitz, E. Philip; Dietz, Mark L.

    1994-01-01

    The invention is a process for selectively extracting strontium values from aqueous nitric acid waste solutions containing these and other fission product values. The extractant solution is a macrocyclic polyether in an aliphatic hydrocarbon diluent containing a phase modifier. The process will selectively extract strontium values from nitric acid solutions which are up to 6 molar in nitric acid.

  6. Ultra-structural mapping of sugarcane bagasse after oxalic acid fiber expansion (OAFEX) and ethanol production by Candida shehatae and Saccharomyces cerevisiae

    PubMed Central

    2013-01-01

    Background Diminishing supplies of fossil fuels and oil spills are rousing to explore the alternative sources of energy that can be produced from non-food/feed-based substrates. Due to its abundance, sugarcane bagasse (SB) could be a model substrate for the second-generation biofuel cellulosic ethanol. However, the efficient bioconversion of SB remains a challenge for the commercial production of cellulosic ethanol. We hypothesized that oxalic-acid-mediated thermochemical pretreatment (OAFEX) would overcome the native recalcitrance of SB by enhancing the cellulase amenability toward the embedded cellulosic microfibrils. Results OAFEX treatment revealed the solubilization of hemicellulose releasing sugars (12.56 g/l xylose and 1.85 g/l glucose), leaving cellulignin in an accessible form for enzymatic hydrolysis. The highest hydrolytic efficiency (66.51%) of cellulignin was achieved by enzymatic hydrolysis (Celluclast 1.5 L and Novozym 188). The ultrastructure characterization of SB using scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy, Fourier transform–near infrared spectroscopy (FT-NIR), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) revealed structural differences before and after OAFEX treatment with enzymatic hydrolysis. Furthermore, fermentation mediated by C. shehatae UFMG HM52.2 and S. cerevisiae 174 showed fuel ethanol production from detoxified acid (3.2 g/l, yield 0.353 g/g; 0.52 g/l, yield, 0.246 g/g) and enzymatic hydrolysates (4.83 g/l, yield, 0.28 g/g; 6.6 g/l, yield 0.46 g/g). Conclusions OAFEX treatment revealed marked hemicellulose degradation, improving the cellulases’ ability to access the cellulignin and release fermentable sugars from the pretreated substrate. The ultrastructure of SB after OAFEX and enzymatic hydrolysis of cellulignin established thorough insights at the molecular level. PMID:23324164

  7. Global impacts of multiphase oxalate production

    NASA Astrophysics Data System (ADS)

    Tost, Holger; Taraborrelli, Domenico

    2013-04-01

    Fine mode atmospheric aerosols are dominated by the organic fraction. A large fraction of these organic compounds consists of oxalates and carboxylic acids. Some of these compounds are produced in the gas phase and then subsequently partition into aerosol particles whereas others are produced directly in the aqueous phase in either cloud droplets or deliquesced aerosol particles. In this study we investigate the contribution of oxalates to the global organic aerosol burden using a comprehensive atmospheric chemistry general circulation model including explicit multiphase chemistry schemes for clouds and aerosols. For that purpose the aqueous phase chemistry has been augmented by a mechanism for oxalates, combined with a consistent gas phase chemistry of corresponding oxidation products from isoprene degradation. Using these tools we will present an analysis of both budget and transport estimates which provide indications for the climate impact of these compounds.

  8. Cadmium, lead and zinc leaching from smelter fly ash in simple organic acids--simulators of rhizospheric soil solutions.

    PubMed

    Ettler, Vojtech; Vrtisková, Růzena; Mihaljevic, Martin; Sebek, Ondrej; Grygar, Tomás; Drahota, Petr

    2009-10-30

    Emissions from base-metal smelters are responsible for high contamination of the surrounding soils. Fly ash from a secondary Pb smelter was submitted to a batch leaching procedure (0.5-168 h) in 500 microM solutions of acetic, citric, or oxalic acids to simulate the release of toxic metals (Cd, Pb, Zn) in rhizosphere-like environments. Organic acids increased dissolution of fly ash by a factor of 1.3. Cadmium and Pb formed mobile chloro- and sulphate-complexes, whereas Zn partly present in a citrate (Zn-citrate(-)) complex is expected to be less mobile due to sorption onto the positively charged surfaces of hydrous ferric oxides (HFO) and organic matter (OM) in acidic soil.

  9. SEPARATION OF PLUTONIUM FROM AQUEOUS SOLUTIONS BY ION-EXCHANGE

    DOEpatents

    Schubert, J.

    1958-06-01

    A process is described for the separation of plutonium from an aqueous solution of a plutonium salt, which comprises adding to the solution an acid of the group consisting of sulfuric acid, phosphoric acid, and oxalic acid, and mixtures thereof to provide an acid concentration between 0.0001 and 1 M, contacting the resultant solution with a synthetic organic anion exchange resin, and separating the aqueous phase and the resin which contains the plutonium.

  10. The bioavailability of magnesium in spinach and the effect of oxalic acid on magnesium utilization examined in diets of magnesium-deficient rats.

    PubMed

    Kikunaga, S; Ishii, H; Takahashi, M

    1995-12-01

    Spinach was evaluated for its bioavailability of magnesium in the experiment with magnesium-deficient rats. The effect of oxalic acid on absorption of dietary magnesium was also examined in the same experiment. After there were significant differences in the body weight of the rats between the control group and the magnesium-deficient group, and after the number of dead rats increased, the magnesium-deficient rats were divided into six groups. They were pair-fed for 8 days on the magnesium-deficient diet, magnesium-deficient diet supplemented with raw powdered spinach (R-sp), boiled powdered spinach (B-sp), or fried powdered spinach (F-sp), control diet supplemented with oxalic acid (Ox-C), and control diet (+Mg). On the 10th day, there was no significant difference in the food intake of the rats between the control group and magnesium-deficient group. However, the body weight, and body weight gain of the rats increased more significantly in the control group than in those of the magnesium-deficient group. Also, the contents of calcium and phosphorus in the liver and kidneys, and serum calcium content increased significantly in the magnesium-deficient rats compared with those of the control rats. However, the serum magnesium content decreased significantly in the magnesium-deficient rats. An especially large amount of calcium was accumulated in the kidneys of the magnesium-deficient rats. At the end of the experimental period, there were no significant differences in the food intake, body weight and body weight gain of the rats among the control group and each of the spinach-added groups. The body weight and body weight gain of the Ox-C rats decreased significantly in comparison with those of the control group and each of the spinach-added groups. Although, there were no significant differences in the concentrations of serum minerals (Mg, Ca and P) among each of the groups, kidney magnesium, calcium and phosphorus, and liver magnesium and phosphorus were

  11. Sonolysis of Short-Chain Organic Dicarboxylic Acid Solutions

    NASA Astrophysics Data System (ADS)

    Naruke, Yukio; Harada, Hisashi

    2011-07-01

    Sonolyses of C4 (carbon number 4) dicarboxylic acids (succinic acid, maleic acid, and fumaric acid) were performed in aqueous solution. They changed one into the other during sonication, affording carbon-number-conserving transformations. Maleic acid and fumaric acid were produced from saccinic acid by dehydrogenation. Furthermore, malic acid and tartaric acid were obtained by hydroxylation. The sonochemical reaction processes are discussed in terms of the time dependences of products and the addition of radical scavengers. In addition, mutual isomerization of fumaric acid and maleic acid was observed during sonication without the use of mediators.

  12. Uranyl fluoride luminescence in acidic aqueous solutions

    SciTech Connect

    Beitz, J.V.; Williams, C.W.

    1996-08-01

    Luminescence emission spectra and decay rates are reported for uranyl species in acidic aqueous solutions containing HF or added NaF. The longest luminescence lifetime, 0.269 {+-} 0.006 ms, was observed from uranyl in 1 M HF + 1 M HClO{sub 4} at 296 K and decreased with increasing temperature. Based on a luminescence dynamics model that assumes equilibrium among electronically excited uranyl fluoride species and free fluoride ion, this long lived uranyl luminescence in aqueous solution is attributed primarily to UO{sub 2}F{sub 2}. Studies on the effect of added LiNO{sub 3} or Na{sub 2}WO{sub 4}{center_dot}2H{sub 2}O showed relatively weak quenching of uranyl fluoride luminescence which suggests that high sensitivity determination of the UF{sub 6} content of WF{sub 6} gas should be feasible via uranyl luminescence analysis of hydrolyzed gas samples of impure WF{sub 6}.

  13. Quasi-intrinsic colossal permittivity in Nb and In co-doped rutile TiO2 nanoceramics synthesized through a oxalate chemical-solution route combined with spark plasma sintering.

    PubMed

    Han, HyukSu; Dufour, Pascal; Mhin, Sungwook; Ryu, Jeong Ho; Tenailleau, Christophe; Guillemet-Fritsch, Sophie

    2015-07-14

    Nb and In co-doped rutile TiO2 nanoceramics (n-NITO) were successfully synthesized through a chemical-solution route combined with a low temperature spark plasma sintering (SPS) technique. The particle morphology and the microstructure of n-NITO compounds were nanometric in size. Various techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric (TG)/differential thermal analysis (DTA), Fourier transform infrared (FTIR), and Raman spectroscopy were used for the structural and compositional characterization of the synthesized compound. The results indicated that the as-synthesized n-NITO oxalate as well as sintered ceramic have a co-doped single phase of titanyl oxalate and rutile TiO2, respectively. Broadband impedance spectroscopy revealed that novel colossal permittivity (CP) was achieved in n-NITO ceramics exhibiting excellent temperature-frequency stable CP (up to 10(4)) as well as low dielectric loss (∼5%). Most importantly, detailed impedance data analyses of n-NITO compared to microcrystalline NITO (μ-NITO) demonstrated that the origin of CP in NITO bulk nanoceramics might be related with the pinned electrons in defect clusters and not to extrinsic interfacial effects.

  14. Nitric acid uptake by sulfuric acid solutions under stratospheric conditions - Determination of Henry's Law solubility

    NASA Technical Reports Server (NTRS)

    Reihs, Christa M.; Golden, David M.; Tolbert, Margaret A.

    1990-01-01

    The uptake of nitric acid by sulfuric acid solutions representative of stratospheric particulate at low temperatures was measured to determine the solubility of nitric acid in sulfuric acid solutions as a function of H2SO4 concentration and solution temperature. Solubilities are reported for sulfuric acid solutions ranging from 58 to 87 wt pct H2SO4 over a temperature range from 188 to 240 K, showing that, in general, the solubility of nitric acid increases with decreasing sulfuric acid concentration and with decreasing temperature. The measured solubilities indicate that nitric acid in the global stratosphere will be found predominantly in the gas phase.

  15. Growth of calcium oxalate monohydrate at phospholipid Langmuir monolayers

    NASA Astrophysics Data System (ADS)

    Whipps, Scott; Khan, Saeed R.; Jeffrey O'Palko, F.; Backov, Rénal; Talham, Daniel R.

    1998-08-01

    Calcium oxalate monohydrate crystals have been nucleated from metastable solutions at Langmuir monolayers of the phospholipids dipalmitoylphosphatidylglycerol (DPPG), dipalmitoylphosphatidylserine and dipalmitoylphosphatidylcholine and the fatty acid arachidic acid. The phospholipid monolayers were used as model systems for domains of pure lipid in cellular media as part of investigations of their potential role in the nucleation of calcium oxalate in the urinary tract. Crystal formation was monitored at the air/water interface using Brewster angle microscopy and in transferred films using SEM and TEM. For each Langmuir monolayer, it was observed that nucleation is heterogeneous and is selective with respect to the orientation and morphology of the precipitated crystals with up to 90% of crystals growing with the ( 1 0 1¯) face oriented towards the monolayer interface. The selectivity is attributed to calcium binding at the lipid monolayer favoring formation of the calcium-rich ( 1 0 1¯) face. The behavior at each monolayer was similar, although a higher rate of crystal formation was observed at the anionic DPPG interface.

  16. Lowering urinary oxalate excretion to decrease calcium oxalate stone disease

    PubMed Central

    Knight, John; Assimos, Dean G.

    2016-01-01

    Dietary modifications should be considered as a first line approach in the treatment of idiopathic calcium oxalate nephrolithiasis. The amounts of oxalate and calcium consumed in the diet are significant factors in the development of the disease due to their impact on urinary oxalate excretion. There are a number of strategies that can be employed to reduce oxalate excretion. The consumption of oxalate-rich foods should be avoided and calcium intake adjusted to 1000–1200 mg/day. To encourage compliance it should be emphasized to patients that they be vigilant with this diet as a deviation in any meal or snack could potentially result in significant stone growth. The evidence underlying these two modifications is outlined and other strategies to reduce urinary oxalate excretion are reviewed. PMID:26614109

  17. Acute oxalate nephropathy due to 'Averrhoa bilimbi' fruit juice ingestion.

    PubMed

    Bakul, G; Unni, V N; Seethaleksmy, N V; Mathew, A; Rajesh, R; Kurien, G; Rajesh, J; Jayaraj, P M; Kishore, D S; Jose, P P

    2013-07-01

    Irumban puli (Averrhoa bilimbi) is commonly used as a traditional remedy in the state of Kerala. Freshly made concentrated juice has a very high oxalic acid content and consumption carries a high risk of developing acute renal failure (ARF) by deposition of calcium oxalate crystals in renal tubules. Acute oxalate nephropathy (AON) due to secondary oxalosis after consumption of Irumban puli juice is uncommon. AON due to A. bilimbi has not been reported before. We present a series of ten patients from five hospitals in the State of Kerala who developed ARF after intake of I. puli fruit juice. Seven patients needed hemodialysis whereas the other three improved with conservative management.

  18. Solid state characterization of azelnidipine-oxalic acid co-crystal and co-amorphous complexes: The effect of different azelnidipine polymorphs.

    PubMed

    Pan, Yahui; Pang, Wenzhe; Lv, Jie; Wang, Jing; Yang, Caiqin; Guo, Wei

    2017-02-04

    In present study, based on the two polymorphs (α and β form) of azelnidipine (AZE), 12 complexes of AZE and oxalic acid (OXA) were prepared by solvent-assisted grinding (SG) and neat powder grinding (NG) methods at the AZE/OXA molar ratios of 2:1, 1:1, and 1:2. The effect of the different polymorphs of AZE on the micro-structure of the complexes were investigated by powder X-ray diffraction (PXRD), tempreture modulated differential scanning calorimetry and thermogravimetric analysis, cryo-field emission scanning electron microscope system, fourier transform infrared (FTIR), and solid-state nuclear magnetic resonance spectroscopy. β-AZE-OXA co-crystal was produced at β-AZE/OXA molar ratio of 2:1 when SG method was used; while α-AZE was used to produce α-AZE-OXA co-crystal at same condition. However, the other 10 combinations were in co-amorphous forms, including the NG samples with α (or β)-AZE/OXA molar ratios of 2:1, 1:1 (SG and NG), and 1:2 (SG and NG). Although the XRD pattern and IR spectra of the two co-crystals showed no difference, the melting enthalpy and specific heat cp of the β-AZE-OXA co-crystal was higher than that of the α-AZE-OXA co-crystal, indicating that the numbers of solvent molecules which entered the two co-crystal lattices were different. Interestingly, obvious difference occurred in the IR spectra between the α-AZE-OXA and β-AZE-OXA co-amorphous systems. 1745cm(-1) wave-numbers, which were assigned to the free CO groups, appeared in the α-AZE-OXA co-amorphous systems even when just a small amount of OXA was introduced, thereby indicating the presence of different intermolecular forces in the two series of co-amorphous forms. The solubility in different media and the dissolution rate in 0.1molL(-1) HCl of the 12 complexes were determined. The dramatically improved dissolution rates of the α- and β-AZE-OXA 1:2 (NG) combinations in vitro showed potential in improving the physicochemical properties of AZE by co-amorphous complex

  19. Two series of reactant's ratio-dependent lanthanide organic frameworks derived from nicotinic acid N-oxide and oxalate: synthesis, crystal structures and luminescence properties.

    PubMed

    Yu, Yanyan; Zhang, Lijuan; Zhou, Yunshan; Zuhra, Zareen

    2015-03-14

    Two series of lanthanide(III)–organic frameworks with the molecular formula [Ln2(NNO)2(OX)2(H2O)4]n (Ln = Eu 1, Tb 2, Sm 3, Dy 4, Gd 5) and [Ln2(NNO)4(OX)(H2O)2]n (Ln = Eu 6, Tb 7, Sm 8, Dy 9, Gd 10) were synthesized successfully under the same hydrothermal conditions with nicotinic N-oxide (HNNO) and oxalic acid (H2OX) as the mixed ligands merely through varying the molar ratio of the reactants. The compounds were characterized by IR, elemental analysis, UV, TG-DTA and powder X-ray diffraction (XRD). X-ray single-crystal diffraction analyses of compounds 1 and 7 selected as representatives and powder XRD analysis of the compounds revealed that both the series of compounds feature three-dimensional (3-D) open frameworks, and crystallize in the triclinic P1 space group while with different unit cell parameters. In compound 1, pairs of Eu(3+) ions and pairs of NNO(−) ligands connect with each other alternately to form a 1-D infinite Eu-NNO double chain, the adjacent 1-D double-chains are then joined together through OX(2−) ligands leading to a 2D layer, the 2-D layers are further ‘pillared’ by OX(2−) ligands resulting in a 3-D framework. In compound 7, the 1-D Tb-NNO infinite chain and its 2-D layer are formed in an almost similar fashion to that in compound 1. The difference between the structures of the two compounds 1 and 7 is that the adjacent 2-D layers in compound 7 are further connected by NNO(−) ligands resulting in a 3-D framework. The photoluminescence properties and energy transfer mechanism of the compounds were studied systematically. The energy level of the lowest triplet states of the HNNO ligand (23148 cm(−1)) was determined based on the phosphorescence spectrum of compound 5 at 77 K. The (5)D0 (Eu(3+)) and (5)D4 (Tb(3+)) emission lifetimes are 0.46 ms, 0.83 ms, 0.69 ms and 0.89 ms and overall quantum yields are 1.03%, 3.29%, 2.58% and 3.78% for the compounds 1, 2, 6 and 7, respectively.

  20. Selective adsorption in two porous triazolate–oxalate-bridged antiferromagnetic metal-azolate frameworks obtained via in situ decarboxylation of 3-amino-1,2,4-triazole-5-carboxylic acid

    SciTech Connect

    Hou, Juan-Juan; Xu, Xia; Jiang, Ning; Wu, Ya-Qin; Zhang, Xian-Ming

    2015-03-15

    Solvothermal reactions of metal salts, 3-amino-1,2,4-triazole-5-carboxylic acid (H{sub 2}atzc) and ammonium oxalate in different temperature produced two metal azolate frameworks, namely, [Cu{sub 3}(atzc){sub 2}(atz)(ox)]·1.5H{sub 2}O (1) and [Co{sub 5}(atz){sub 4}(ox){sub 3}(HCOO){sub 2}]·DMF (2) (H{sub 2}atzc=3-amino-1,2,4-triazole-5-carboxylic acid, Hatz=3-amino-1,2,4-triazole, and ox=oxalate), in which the atzc precusor was in situ decarboxylated. Structural determination reveals that 1 contains [Cu{sub 3}(atzc){sub 2}(atz)]{sup 2−} layers of mixed μ{sub 4}-atzc and μ{sub 3}-atz ligands, which are pillared by ox{sup 2−} groups to form a 3D porous framework. Compound 2 contains 2D layers with basic spindle-shaped decanuclear units, which extended by ox{sup 2−} and formates to form 3D porous framework. Gas adsorption investigation revealed that two kinds of frameworks exhibited selective CO{sub 2} over N{sub 2} sorption. Moreover, activated 2 shows H{sub 2} storage capacity. Additionally, magnetic properties of both the compounds have been investigated. - Graphical abstract: Solvothermal reactions of metal salts, 3-amino-1,2,4-triazole-5-carboxylate and oxalate produced two metal azolate frameworks, which could store gas molecules, especially H{sub 2} due to small pores. in situ decarboxylation of precursor was observed. - Highlights: • Two MAFs were synthesized via in situ decarboxylation of H{sub 2}atzc. • Both activated frameworks exhibited selective CO{sub 2} over N{sub 2} sorption. • Activated 2 could adsorb H{sub 2}, which makes it promising candidates for gas storage.

  1. Method of forming yttria-gadolinia ceramic scintillator from ammonium dispersed oxalate precipitates

    SciTech Connect

    Dole, S.L.; Greskovich, C.D.

    1992-03-31

    This patent describes a method of forming a polycrystalline translucent-to-transparent yttria-gadolinia composition scintillator that does not require milling. It comprises: coprecipitating oxalates of the yttria-gadolinia composition, drying the oxalates at about 75{degrees} to 125{degrees}C.; dispersing the oxalates by agitating an admixture of an aqueous suspension of the oxalates, and an effective amount of an ammonium hydroxide solution to disperse agglomerations of the oxalates; calcining the oxalates to substantially fully oxidize the oxalates and form a powder of the yttria-gadolinia composition; cold pressing the powder to form a compact; and sintering the compact in a reducing atmosphere or vacuum to form the polycrystalline translucent-to-transparent yttria-gadolinia scintillator.

  2. Gut microbiota and oxalate homeostasis

    PubMed Central

    2017-01-01

    This perspective focuses on how the gut microbiota can impact urinary oxalate excretion in the context of hyperoxaluria, a major risk factor in kidney stone disease. In the genetic disease of Primary Hyperoxaluria Type 1 (PH1), an increased endogenous production of oxalate, due to a deficiency of the liver enzyme alanine-glyoxylate aminotransferase (AGT), results in hyperoxaluria and oxalate kidney stones. The constant elevation in urinary oxalate in PH1 patients ultimately leads to tissue deposition of oxalate, renal failure and death and the only known cure for PH1 is a liver or liver-kidney transplant. The potential impact of a probiotic/therapeutic approach may be clinically significant in PH1 and could also extend to a much larger population of idiopathic oxalate stone formers who comprise ~12% of Americans, individuals with enteric hyperoxaluria, and an emerging population of hyperoxaluric patients who have undergone bariatric surgery and develop kidney stone disease as a consequence. PMID:28217701

  3. In vitro efficacy of a novel potassium oxalate hydrogel for dentin hypersensitivity.

    PubMed

    Varoni, Elena M; Zuccheri, Tommaso; Carletta, Andrea; Palazzo, Barbara; Cochis, Andrea; Colonna, Martino; Rimondini, Lia

    2017-04-01

    A novel potassium oxalate-based hydrogel is proposed for treating dentin hypersensitivity and this study evaluates its in vitro performance as a remineralizing, desensitizing agent. Etched disks of human dentin were treated for 10 or 20 min using the test hydrogel, to mimic a professional application with dental mouth guards. Dentin disks were evaluated in terms of permeability indexes in a fluid-filled system, the surface morphology was assessed by scanning electron microscopy, and the structural properties were studied using X-ray diffraction analysis. The potassium oxalate hydrogel significantly reduced dentin permeability, in a time-dependent manner, and occluded most of the patent dentinal tubules via crystal precipitation, forming a remineralized layer. After hydrogel treatments, an acid solution (pH 4.2) was applied to the disks for 30 s, or 1, 2, or 5 min, in order to reproduce a plaque-like oral acidity, and further analysis showed a good resistance of the remineralized layer to the acid challenge. The potassium oxalate-based hydrogel showed a better performance over commercially available products and artificial saliva, appearing a promising candidate for the treatment of dentin hypersensitivity.

  4. Genetic evidence for differences in the pathways of druse and prismatic calcium oxalate crystal formation in Medicago truncatula

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Current evidence supports a single pathway of oxalate biosynthesis utilising ascorbic acid as the precursor. In this study, we begin to address the possibility that more than one pathway of oxalate biosynthesis and calcium oxalate formation occurs in Medicago truncatula Gaertn. (cv. Jemalong genotyp...

  5. Synthesis and characterisation of a new hydrated bismuth (III) oxalate : Bi2(C2O4)3,6H2O

    NASA Astrophysics Data System (ADS)

    Tortet, L.; Monnereau, O.; Roussel, P.; Conflant, P.

    2004-11-01

    This study presents results on synthesis and crystal structure of a new hydrated bismuth(III) oxalate : Bi2(C2O{4})3,6H2O. This compound is obtained by precipitation from Bi(NO3)3 solution and oxalic acid. Its structure is determined by X-ray crystallographic analysis from a single crystal: it is monoclinic with a = 9.761(1)Å, b = 8.193(1)Å, c = 10.214(1)Å, β = 99.66(1)circ, G.S. P2{1}/n. Its chemical composition is confirmed by chemical analyses, FTIR and TG-DTA experiments.

  6. Electrode kinetics at a platinum anode in chloroacetic acid solutions

    SciTech Connect

    Lotvin, B.M.; Vasil'ev, Yu.B.

    1987-02-01

    It was shown by direct comparison of kinetic and adsorption data that at platinum in solutions of mono- and trichloroacetic acid, the anodic processes are entirely analogous in character to the processes occurring in acetate solutions. The lack of Kolbe electrosynthesis products in the electrolysis of chloroacetic acids is to the special reaction features of the secondary chloroalkyl radicals.

  7. The effects of oxalate-containing products on the exposed dentine surface: an SEM investigation.

    PubMed

    Gillam, D G; Mordan, N J; Sinodinou, A D; Tang, J Y; Knowles, J C; Gibson, I R

    2001-11-01

    In-office products containing oxalates have been claimed to be clinically effective in reducing dentine sensitivity, although there has been limited supporting clinical data. The rationale for their use appears to be based on their potential to act as occluding and/or nerve desensitizing agents. Four commercially available oxalate-containing products were applied to etched dentine discs and the extent of tubule occlusion was observed by scanning electron microscopy. Tenure Quick (aluminium oxalate), Sensodyne Sealant (ferric oxalate) and MS Coat (oxalic acid) covered the dentine surface and occluded the tubules. However, Butler Protect (potassium oxalate) did not cover the surface to any great extent but provided some occlusion. The presence of oxalates after application to glass slides and dentine discs was examined using thin film X-ray diffraction. From samples on glass, only potassium oxalate could be clearly identified (JCPDS 14-0845). No oxalate was detected on dentine discs in either thin film geometry or standard theta two theta mode. We have demonstrated that professionally applied in-office products containing oxalate are capable of covering the dentine surface and/or occluding the tubules to varying degrees. However, X-ray diffraction analysis was unable to confirm the oxalate profile for all products as described in the available commercial literature.

  8. Process for the recovery of strontium from acid solutions

    DOEpatents

    Horwitz, E. Philip; Dietz, Mark L.

    1992-01-01

    The invention is a process for selectively extracting strontium and technetium values from aqueous nitric acid waste solutions containing these and other fission product values. The extractant is a macrocyclic polyether in a diluent which is insoluble in water, but which will itself dissolve a small amount of water. The process will extract strontium and technetium values from nitric acid solutions which are up to 6 molar in nitric acid.

  9. Process for the recovery of strontium from acid solutions

    DOEpatents

    Horwitz, E.P.; Dietz, M.L.

    1992-03-31

    The invention is a process for selectively extracting strontium and technetium values from aqueous nitric acid waste solutions containing these and other fission product values. The extractant is a macrocyclic polyether in a diluent which is insoluble in water, but which will itself dissolve a small amount of water. The process will extract strontium and technetium values from nitric acid solutions which are up to 6 molar in nitric acid. 5 figs.

  10. Determining the biochemical properties of the Oxalate Biosynthetic Component (Obc)1 from Burkholderia mallei

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Oxalic acid is produced by a variety of organisms ranging from simple microbes to complex animals. This acid has been proposed to fulfill various physiological and pathological functions which vary between organisms. In bacteria from the Burkholderia genus, oxalate secretion has been shown to be quo...

  11. REDUCTION OF ACIDITY OF NITRIC ACID SOLUTIONS BY USE OF FORMALDEHYDE

    DOEpatents

    Healy, T.V.

    1958-05-20

    A continuous method is described of concentrating by evaporation and reducing the nitrate ion content of an aqueous solution of metallic salts containing nitric acid not in excess of 8N. It consists of heating the solution and then passing formaldehyde into the heated solution to bring about decomposition of the nitric acid. The evolved gases containing NO are contacted countercurrently with an aqueous metal salt solution containing nitric acid in excess of 8N so as to bring about decomposition of the nitric acid and lower the normality to at least 8N, whereupon it is passed into the body of heated solution.

  12. Kinetic challenges facing oxalate, malonate, acetoacetate, and oxaloacetate decarboxylases.

    PubMed

    Wolfenden, Richard; Lewis, Charles A; Yuan, Yang

    2011-04-20

    To compare the powers of the corresponding enzymes as catalysts, the rates of uncatalyzed decarboxylation of several aliphatic acids (oxalate, malonate, acetoacetate, and oxaloacetate) were determined at elevated temperatures and extrapolated to 25 °C. In the extreme case of oxalate, the rate of the uncatalyzed reaction at pH 4.2 was 1.1 × 10(-12) s(-1), implying a 2.5 × 10(13)-fold rate enhancement by oxalate decarboxylase. Whereas the enzymatic decarboxylation of oxalate requires O(2) and Mn(II), the uncatalyzed reaction is unaffected by the presence of these cofactors and appears to proceed by heterolytic elimination of CO(2).

  13. Method for liquid chromatographic extraction of strontium from acid solutions

    DOEpatents

    Horwitz, E. Philip; Dietz, Mark L.

    1992-01-01

    A method and apparatus for extracting strontium and technetium values from biological, industrial and environmental sample solutions using a chromatographic column is described. An extractant medium for the column is prepared by generating a solution of a diluent containing a Crown ether and dispersing the solution on a resin substrate material. The sample solution is highly acidic and is introduced directed to the chromatographic column and strontium or technetium is eluted using deionized water.

  14. OXALATE DEPOSITION ON ASBESTOS BODIES

    EPA Science Inventory

    The clinical and histopathologic findings in three patients with a deposition of calcium oxalate crystals on ferruginous bodies after occupational exposure to asbestos are provided. In addition, we test the hypothesis that this oxalate can be generated through a nonenzymatic o...

  15. Evidence for a cytoplasmic pathway of oxalate biosynthesis in Aspergillus niger.

    PubMed Central

    Kubicek, C P; Schreferl-Kunar, G; Wöhrer, W; Röhr, M

    1988-01-01

    Oxalate accumulation of up to 8 g/liter was induced in Aspergillus niger by shifting the pH from 6 to 8. This required the presence of Pi and a nitrogen source and was inhibited by the protein synthesis inhibitor cycloheximide. Exogenously added 14CO2 was not incorporated into oxalate, but was incorporated into acetate and malate, thus indicating the biosynthesis of oxalate by hydrolytic cleavage of oxaloacetate. Inhibition of mitochondrial citrate metabolism by fluorocitrate did not significantly decrease the oxalate yield. The putative enzyme that was responsible for this was oxaloacetate hydrolase (EC 3.7.1.1), which was induced de novo during the pH shift. Subcellular fractionation of oxalic acid-forming mycelia of A. niger showed that this enzyme is located in the cytoplasm of A. niger. The results are consistent with a cytoplasmic pathway of oxalate formation which does not involve the tricarboxylic acid cycle. PMID:3132096

  16. Oxalate: Effect on calcium absorbability

    SciTech Connect

    Heaney, R.P.; Weaver, C.M. )

    1989-10-01

    Absorption of calcium from intrinsically labeled Ca oxalate was measured in 18 normal women and compared with absorption of Ca from milk in these same subjects, both when the test substances were ingested in separate meals and when ingested together. Fractional Ca absorption from oxalate averaged 0.100 +/- 0.043 when ingested alone and 0.140 +/- 0.063 when ingested together with milk. Absorption was, as expected, substantially lower than absorption from milk (0.358 +/- 0.113). Nevertheless Ca oxalate absorbability in these women was higher than we had previously found for spinach Ca. When milk and Ca oxalate were ingested together, there was no interference of oxalate in milk Ca absorption and no evidence of tracer exchange between the two labeled Ca species.

  17. An Oxalyl-CoA Dependent Pathway of Oxalate Catabolism Plays a Role in Regulating Calcium Oxalate Crystal Accumulation and Defending against Oxalate-Secreting Phytopathogens in Medicago truncatula

    PubMed Central

    Foster, Justin; Luo, Bin; Nakata, Paul A.

    2016-01-01

    Considering the widespread occurrence of oxalate in nature and its broad impact on a host of organisms, it is surprising that so little is known about the turnover of this important acid. In plants, oxalate oxidase is the most well studied enzyme capable of degrading oxalate, but not all plants possess this activity. Recently, an Acyl Activating Enzyme 3 (AAE3), encoding an oxalyl-CoA synthetase, was identified in Arabidopsis. AAE3 has been proposed to catalyze the first step in an alternative pathway of oxalate degradation. Whether this enzyme and proposed pathway is important to other plants is unknown. Here, we identify the Medicago truncatula AAE3 (MtAAE3) and show that it encodes an oxalyl-CoA synthetase activity exhibiting high activity against oxalate with a Km = 81 ± 9 μM and Vmax = 19 ± 0.9 μmoles min-1mg protein-1. GFP-MtAAE3 localization suggested that this enzyme functions within the cytosol of the cell. Mtaae3 knock-down line showed a reduction in its ability to degrade oxalate into CO2. This reduction in the capacity to degrade oxalate resulted in the accumulation of druse crystals of calcium oxalate in the Mtaae3 knock-down line and an increased susceptibility to oxalate-secreting phytopathogens such as Sclerotinia sclerotiorum. Taken together, these results suggest that AAE3 dependent turnover of oxalate is important to different plants and functions in the regulation of tissue calcium oxalate crystal accumulation and in defense against oxalate-secreting phytopathogens. PMID:26900946

  18. Acid rain: Engineering solutions, regulatory aspects

    SciTech Connect

    Schwieger, R.G.; Elliott, T.C.

    1985-01-01

    Keeping up with efforts to control acid rain, this reference presents current scientific aspects associated with the problem of political and legislative concerns and ideas for developing effective mitigation programs at reasonable cost. The contributors are the authorities in attendance at the Second International Conference on Acid Rain - and this work represents the first time engineers and managers with firsthand knowledge of systems and equipment to reduce SO/sub 2/ and NO/sub x/ emissions gathered in one place. Throughout the book, some 200 tables, charts, diagrams, and photographs augment the textual material.

  19. Decomposition Studies of Triphenylboron, Diphenylborinic Acid and Phenylboric Acid in Aqueous Alkaline Solutions Containing Copper

    SciTech Connect

    Crawford, C.L.; Peterson, R. A.

    1997-02-11

    This report documents the copper-catalyzed chemical kinetics of triphenylboron, diphenylborinic acid and phenylboric acid (3PB, 2PB and PBA) in aqueous alkaline solution contained in carbon-steel vessels between 40 and 70 degrees C.

  20. Cloning and sequencing of two Ceriporiopsis subvermispora bicupin oxalate oxidase allelic isoforms: implications for the reaction specificity of oxalate oxidases and decarboxylases.

    PubMed

    Escutia, Marta R; Bowater, Laura; Edwards, Anne; Bottrill, Andrew R; Burrell, Matthew R; Polanco, Rubén; Vicuña, Rafael; Bornemann, Stephen

    2005-07-01

    Oxalate oxidase is thought to be involved in the production of hydrogen peroxide for lignin degradation by the dikaryotic white rot fungus Ceriporiopsis subvermispora. This enzyme was purified, and after digestion with trypsin, peptide fragments of the enzyme were sequenced using quadrupole time-of-flight mass spectrometry. Starting with degenerate primers based on the peptide sequences, two genes encoding isoforms of the enzyme were cloned, sequenced, and shown to be allelic. Both genes contained 14 introns. The sequences of the isoforms revealed that they were both bicupins that unexpectedly shared the greatest similarity to microbial bicupin oxalate decarboxylases rather than monocupin plant oxalate oxidases (also known as germins). We have shown that both fungal isoforms, one of which was heterologously expressed in Escherichia coli, are indeed oxalate oxidases that possess < or =0.2% oxalate decarboxylase activity and that the organism is capable of rapidly degrading exogenously supplied oxalate. They are therefore the first bicupin oxalate oxidases to have been described. Heterologous expression of active enzyme was dependent on the addition of manganese salts to the growth medium. Molecular modeling provides new and independent evidence for the identity of the catalytic site and the key amino acid involved in defining the reaction specificities of oxalate oxidases and oxalate decarboxylases.

  1. Infrared, Polarized Raman, and SERS Spectra of Betaine Hydrogen Oxalate Monohydrate

    NASA Astrophysics Data System (ADS)

    Philip, Daizy; Aruldhas, G.

    1995-01-01

    Infrared and polarized Raman spectra of betaine hydrogen oxalate monohydrate are recorded and analyzed. The observed bands are assigned on the basis of vibrations due to oxalic acid, betaine, and water molecules. In the crystal it is found that oxalic acid molecules occupy a lower site and that betaine exists in zwitterionic form. Oxalic acid and water molecules are involved in strong hydrogen bending. Band assignments are confirmed by deuteration. Surface enhanced Raman scattering (SERS) spectra recorded in two silver colloids reveal chemisorption through different adsorption sites. The observed SERS spectra are interpreted on the basis of different adsorption sites, geometries, and adsorbate conformation/orientation. The change of the SERS spectrum with time is due to the different stabilities of the adsorbed states. The oxalic acid molecules of the compound are likely to be in a tilted orientation with respect to the silver surface.

  2. Vacuum-jacketed hydrofluoric acid solution calorimeter

    USGS Publications Warehouse

    Robie, R.A.

    1965-01-01

    A vacuum-jacketed metal calorimeter for determining heats of solution in aqueous HF was constructed. The reaction vessel was made of copper and was heavily gold plated. The calorimeter has a cooling constant of 0.6 cal-deg -1-min-1, approximately 1/4 that of the air-jacketed calorimeters most commonly used with HF. It reaches equilibrium within 10 min after turning off the heater current. Measurements of the heat of solution of reagent grade KCl(-100 mesh dried 2 h at 200??C) at a mole ratio of 1 KCl to 200 H2O gave ??H = 4198??11 cal at 25??C. ?? 1965 The American Institute of Physics.

  3. Oxalate deposition on asbestos bodies.

    PubMed

    Ghio, Andrew J; Roggli, Victor L; Richards, Judy H; Crissman, Kay M; Stonehuerner, Jacqueline D; Piantadosi, Claude A

    2003-08-01

    We report on a deposition of oxalate crystals on ferruginous bodies after occupational exposure to asbestos demonstrated in 3 patients. We investigated the mechanism and possible significance of this deposition by testing the hypothesis that oxalate generated through nonenzymatic oxidation of ascorbate by asbestos-associated iron accounts for the deposition of the crystal on a ferruginous body. Crocidolite asbestos (1000 microg/mL) was incubated with 500 micromol H(2)O(2) and 500 micromol ascorbate for 24 hours at 22 degrees C. The dependence of oxalate generation on iron-catalyzed oxidant production was tested with the both the metal chelator deferoxamine and the radical scavenger dimethylthiourea. Incubation of crocidolite, H(2)O(2), and ascorbate in vitro generated approximately 42 nmol of oxalate in 24 hours. Oxalate generation was diminished significantly by the inclusion of either deferoxamine or dimethylthiourea in the reaction mixture. Incubation of asbestos bodies and uncoated fibers isolated from human lung with 500 micromol H(2)O(2) and 500 micromol ascorbate for 24 hours at 22 degrees C resulted in the generation of numerous oxalate crystals. We conclude that iron-catalyzed production of oxalate from ascorbate can account for the deposition of this crystal on ferruginous bodies.

  4. Decomposition of pertoluic acid in chlorobenzene solution

    SciTech Connect

    Ariko, N.G.; Kornilova, N.N.; Mitskevich, N.I.

    1985-09-01

    The kinetics and composition of the decomposition products of pertoluic acid in chlorobenzene at 353-403 K were studied. The activation energy of the gross decomposition is 82.4 is identical to 6 kJ/mole; the main products are pertoluic acid and CO/sub 2/. On the basis of the dependence of the yields of CO/sub 2/ on the concentration of the peracid (0.01-0.05 M), it was concluded that the peracid undergoes radical breakdown, and induced breakdown with abstraction of a H atom from OOH group occurs. The formation of toluence (conversion product of the CH/sub 3/-C/sub 6/H/sub 4/. radical) and O/sub 2/ was demonstrated.

  5. Improved method for extracting lanthanides and actinides from acid solutions

    DOEpatents

    Horwitz, E.P.; Kalina, D.G.; Kaplan, L.; Mason, G.W.

    1983-07-26

    A process for the recovery of actinide and lanthanide values from aqueous acidic solutions uses a new series of neutral bi-functional extractants, the alkyl(phenyl)-N,N-dialkylcarbamoylmethylphosphine oxides. The process is suitable for the separation of actinide and lanthanide values from fission product values found together in high-level nuclear reprocessing waste solutions.

  6. Polymerization of beta-amino acids in aqueous solution

    NASA Technical Reports Server (NTRS)

    Liu, R.; Orgel, L. E.; Bada, J. L. (Principal Investigator)

    1998-01-01

    We have compared carbonyl diimidazole (CDI) and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDAC) as activating agents for the oligomerization of negatively-charged alpha- and beta-amino acids in homogeneous aqueous solution. alpha-Amino acids can be oligomerized efficiently using CDI, but not by EDAC. beta-Amino acids can be oligomerized efficiently using EDAC, but not by CDI. Aspartic acid, an alpha- and beta-dicarboxylic acid is oligomerized efficiently by both reagents. These results are explained in terms of the mechanisms of the reactions, and their relevance to prebiotic chemistry is discussed.

  7. Method for incorporating radioactive phosphoric acid solutions in concrete

    DOEpatents

    Wolf, G.A.; Smith, J.W.; Ihle, N.C.

    1982-07-08

    A method for incorporating radioactive phosphoric acid solutions in concrete is described wherein the phosphoric acid is reacted with Ca(OH)/sub 2/ to form a precipitate of hydroxyapatite and the hydroxyapatite is mixed with Portland cement to form concrete.

  8. Method for incorporating radioactive phosphoric acid solutions in concrete

    DOEpatents

    Wolf, Gary A [Kennewick, WA; Smith, Jeffrey W [Lancaster, OH; Ihle, Nathan C [Walla Walla, WA

    1984-01-01

    A method for incorporating radioactive phosphoric acid solutions in concrete is described wherein the phosphoric acid is reacted with Ca(OH).sub.2 to form a precipitate of hydroxyapatite and the hydroxyapatite is mixed with portland cement to form concrete.

  9. Phosphorylation of glyceric acid in aqueous solution using trimetaphosphate

    NASA Astrophysics Data System (ADS)

    Kolb, Vera; Orgel, Leslie E.

    1996-02-01

    The phosphorylation of glyceric acid is an interesting prebiotic reaction because it converts a simple, potentially prebiotic organic molecule into phosphate derivatives that are central to carbohydrate metabolism. We find that 0.05 M glyceric acid in the presence of 0.5 M trimetaphosphate in alkaline solution gives a mixture of 2- and 3-phosphoglyceric acids in combined yields of up to 40%.

  10. Phosphorylation of Glyceric Acid in Aqueous Solution Using Trimetaphosphate

    NASA Technical Reports Server (NTRS)

    Kolb, Vera; Orgel, Leslie E.

    1996-01-01

    The phosphorylation of glyceric acid is an interesting prebiotic reaction because it converts a simple, potentially prebiotic organic molecule into phosphate derivatives that are central to carbohydrate metabolism. We find that 0.05 M glyceric acid in the presence of 0.5 M trimetaphosphate in alkaline solution gives a mixture of 2- and 3-phosphoglyceric acids in combined yields of up to 40%.

  11. Reduction of Plutonium in Acidic Solutions by Mesoporous Carbons

    SciTech Connect

    Parsons-Moss, Tashi; Jones, Stephen; Wang, Jinxiu; Wu, Zhangxiong; Uribe, Eva; Zhao, Dongyuan; Nitsche, Heino

    2015-12-19

    Batch contact experiments with several porous carbon materials showed that carbon solids spontaneously reduce the oxidation state of plutonium in 1-1.5 M acid solutions, without significant adsorption. The final oxidation state and rate of Pu reduction varies with the solution matrix, and also depends on the surface chemistry and surface area of the carbon. It was demonstrated that acidic Pu(VI) solutions can be reduced to Pu(III) by passing through a column of porous carbon particles, offering an easy alternative to electrolysis with a potentiostat.

  12. FIRE EXTINGUISHERS CONTAINING INHIBITED LITHIUM CHLORIDE SOLUTION FOR POLAR USE

    DTIC Science & Technology

    Previous experiments under this task using small metal test panels resulted in the selection of a sodium dichromate- oxalic acid inhibitor for use in...of drawn brass or silicon bronze and lined with a lead alloys, were tested with the lithium chloride solution using either sodium dichromate- oxalic ... acid or sodium dichromate alone as an inhibitor. It was determined that 0.5 percent sodium dichromate satisfactorily inhibits corrosion by the water solution of lithium chloride when contained in an extinguisher of drawn brass.

  13. Cr{sup 3+} modified LiMn{sub 2}O{sub 4} spinel intercalation cathodes through oxalic acid assisted sol-gel method for lithium rechargeable batteries

    SciTech Connect

    Thirunakaran, R. . E-mail: rthirunakaran@yahoo.com; Kim, Ki-Tae; Kang, Yong-Mook; Young-Lee, Jai

    2005-01-04

    To improve the cycle performance of eco-friendly and cost-effective spinel LiMn{sub 2}O{sub 4} as the cathode of 4 V class Li secondary batteries, the spinel phase LiCr{sub x}Mn{sub 2-x}O{sub 4} (x = 0.01-0.20) was synthesized by soft chemistry method using oxalic acid as chelating agent. The present technique results in better homogeneity, good surface morphology, shorter heat treatment time, sub-micron sized particles, good agglomeration and better crystallinity. Electrochemical studies were monitored in the potential range of 3-4.5 V. The present paper reveals that chromium substituted manganese spinel improves the structural stability of the parent material.

  14. REMOVAL OF CHLORIDE FROM ACIDIC SOLUTIONS USING NO2

    SciTech Connect

    Visser, A; Robert Pierce, R; James Laurinat, J

    2006-08-22

    Chloride (Cl{sup -}) salt processing in strong acids is used to recycle plutonium (Pu) from pyrochemical residues. The Savannah River National Laboratory (SRNL) is studying the potential application of nitrogen dioxide (NO{sub 2}) gas to effectively convert dissolved pyrochemical salt solutions to chloride-free solutions and improve recovery operations. An NO{sub 2} sparge has been shown to effectively remove Cl{sup -} from solutions containing 6-8 M acid (H{sup +}) and up to 5 M Cl{sup -}. Chloride removal occurs as a result of the competition of at least two reactions, one which is acid-dependent. Below 4 M H+, NO2 reacts with Cl- to produce nitrosyl chloride (ClNO). Between 6 M and 8 M H{sup +}, the reaction of hydrochloric acid (HCl) with nitric acid (HNO{sub 3}), facilitated by the presence of NO{sub 2}, strongly affects the rate of Cl{sup -} removal. The effect of heating the acidic Cl{sup -} salt solution without pre-heating the NO{sub 2} gas has minimal effect on Cl{sup -} removal rates when the contact times between NO{sub 2} and the salt solution are on the order of seconds.

  15. Medical therapy, calcium oxalate urolithiasis

    NASA Technical Reports Server (NTRS)

    Ruml, L. A.; Pearle, M. S.; Pak, C. Y.

    1997-01-01

    The development of diagnostic protocols that identify specific risk factors for calcium oxalate nephrolithiasis has led to the formulation of directed medical regimens that are aimed at correcting the underlying metabolic disturbances. Initiation of these treatment programs has reduced markedly the rate of stone formation in the majority of patients who form stones. This article discusses the rationale that underlies the choice of medical therapy for the various pathophysiologic causes of calcium oxalate nephrolithiasis and the appropriate use of available medications.

  16. Coulometric determination of berkelium in sulfuric acid and nitric acid solutions

    SciTech Connect

    Timofeev, G.A.; Chistyakov, V.M.; Erin, E.A.

    1987-03-01

    Results are reported on the study and quantitative determination of berkelium by the coulometric method in 1 M sulfuric acid, in solutions of nitric acid, and in mixtures of these acids. The best results in the determination of berkelium were obtained in solutions of a mixture of nitric and sulfuric acids. In 1 M HNO/sub 3/ + 0.1 M H/sub 2/SO/sub 4/ solutions, berkelium can be determined with an accuracy within approx. +/- 2%, when its content is 10 ..mu..g/ml.

  17. An oxalyl-CoA synthetase is important for oxalate metabolism in Saccharomyces cerevisiae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although oxalic acid is common in nature, our understanding of the mechanism(s) regulating its turnover remains incomplete. In this study we identify Saccharomyces cerevisiae acyl-activating enzyme 3 (ScAAE3) as an enzyme capable of catalyzing the conversion of oxalate to oxalyl-CoA. Based on our fi...

  18. Functional characterization of the oxaloacetase encoding gene and elimination of oxalate formation in the β-lactam producer Penicillium chrysogenum.

    PubMed

    Gombert, A K; Veiga, T; Puig-Martinez, M; Lamboo, F; Nijland, J G; Driessen, A J M; Pronk, J T; Daran, J M

    2011-08-01

    Penicillium chrysogenum is widely used as an industrial antibiotic producer, in particular in the synthesis of ß-lactam antibiotics such as penicillins and cephalosporins. In industrial processes, oxalic acid formation leads to reduced product yields. Moreover, precipitation of calcium oxalate complicates product recovery. We observed oxalate production in glucose-limited chemostat cultures of P. chrysogenum grown with or without addition of adipic acid, side-chain of the cephalosporin precursor adipoyl-6-aminopenicillinic acid (ad-6-APA). Oxalate accounted for up to 5% of the consumed carbon source. In filamentous fungi, oxaloacetate hydrolase (OAH; EC3.7.1.1) is generally responsible for oxalate production. The P. chrysogenum genome harbours four orthologs of the A. niger oahA gene. Chemostat-based transcriptome analyses revealed a significant correlation between extracellular oxalate titers and expression level of the genes Pc18g05100 and Pc22g24830. To assess their possible involvement in oxalate production, both genes were cloned in Saccharomyces cerevisiae, yeast that does not produce oxalate. Only the expression of Pc22g24830 led to production of oxalic acid in S. cerevisiae. Subsequent deletion of Pc22g28430 in P. chrysogenum led to complete elimination of oxalate production, whilst improving yields of the cephalosporin precursor ad-6-APA.

  19. Population and size distribution of solute-rich mesospecies within mesostructured aqueous amino acid solutions.

    PubMed

    Jawor-Baczynska, Anna; Moore, Barry D; Lee, Han Seung; McCormick, Alon V; Sefcik, Jan

    2013-01-01

    Aqueous solutions of highly soluble substances such as small amino acids are usually assumed to be essentially homogenous systems with some degree of short range local structuring due to specific interactions on the sub-nanometre scale (e.g. molecular clusters, hydration shells), usually not exceeding several solute molecules. However, recent theoretical and experimental studies have indicated the presence of much larger supramolecular assemblies or mesospecies in solutions of small organic and inorganic molecules as well as proteins. We investigated both supersaturated and undersaturated aqueous solutions of two simple amino acids (glycine and DL-alanine) using Dynamic Light Scattering (DLS), Brownian Microscopy/Nanoparticles Tracking Analysis (NTA) and Cryogenic Transmission Electron Microscopy (Cryo-TEM). Colloidal scale mesospecies (nanodroplets) were previously reported in supersaturated solutions of these amino acids and were implicated as intermediate species on non-classical crystallization pathways. Surprisingly, we have found that the mesospecies are also present in significant numbers in undersaturated solutions even when the solute concentration is well below the solid-liquid equilibrium concentration (saturation limit). Thus, mesopecies can be observed with mean diameters ranging from 100 to 300 nm and a size distribution that broadens towards larger size with increasing solute concentration. We note that the mesospecies are not a separate phase and the system is better described as a thermodynamically stable mesostructured liquid containing solute-rich domains dispersed within bulk solute solution. At a given temperature, solute molecules in such a mesostructured liquid phase are subject to equilibrium distribution between solute-rich mesospecies and the surrounding bulk solution.

  20. Dephosphorization of Steelmaking Slag by Leaching with Acidic Aqueous Solution

    NASA Astrophysics Data System (ADS)

    Qiao, Yong; Diao, Jiang; Liu, Xuan; Li, Xiaosa; Zhang, Tao; Xie, Bing

    2016-09-01

    In the present paper, dephosphorization of steelmaking slag by leaching with acidic aqueous solution composed of citric acid, sodium hydroxide, hydrochloric acid and ion-exchanged water was investigated. The buffer solution of C6H8O7-NaOH-HCl system prevented changes in the pH values. Kinetic parameters including leaching temperature, slag particle size and pH values of the solution were optimized. The results showed that temperature has no obvious effect on the dissolution ratio of phosphorus. However, it has a significant effect on the dissolution ratio of iron. The dephosphorization rate increases with the decrease of slag particle size and the pH value of the solution. Over 90% of the phosphorus can be dissolved in the solution while the corresponding leaching ratio of iron was only 30% below the optimal condition. Leaching kinetics of dephosphorization follow the unreacted shrinking core model with a rate controlled step by the solid diffusion layer, the corresponding apparent activation energy being 1.233 kJ mol-1. A semiempirical kinetic equation was established. After leaching, most of the nC2S-C3P solid solution in the steelmaking slag was selectively dissolved in the aqueous solution and the iron content in the solid residue was correspondingly enriched.

  1. Coprecipitation of thorium and uranium peroxides from acid solutions

    SciTech Connect

    McTaggart, D.R.; Mailen, J.C.

    1981-01-01

    The factors affecting successful coprecipitation of thorium and uranium peroxides from acid media were studied. Variables considered in this work were H/sup +/ concentration, H/sub 2/O/sub 2/ concentration, duration of contact, and rate of feed solution addition. In all experiments, stock solutions of Th(NO/sub 3/)/sub 4/ and UO/sub 2/(NO/sub 3/)/sub 2/ were fed at a controlled rate into H/sub 2/O/sub 2/ solutions with constant stirring. Samples were taken as a function of time to follow the H/sup +/ concentration of the solution, uranium precipitation, thorium precipitation, precipitant weight/volume of solution, and crystalline structure and growth. The optimum conditions for maximum coprecipitation are low H/sup +/ concentration, high H/sub 2/O/sub 2/ concentration, and extended contact time between the solutions.

  2. γ-Irradiation of malic acid in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Negron-Mendoza, Alicia; Graff, Rebecca L.; Ponnamperuma, Cyril

    1980-12-01

    The γ-irradiation of malic acid in aqueous solutions was studied under initially oxygenated and oxygen-free conditions in an attempt to determine the possible interconversion of malic acid into other carboxylic acids, specifically those associated with Krebs cycle. The effect of dose on product formation of the system was investigated. Gas-liquid chromatography combined with mass spectrometry was used as the principal means of identification of the non-volatile products. Thin layer chromotography and direct probe mass spectroscopy were also employed. The findings show that a variety of carboxylic acids are formed, with malonic and succinic acids in greatest abundance. These products have all been identified as being formed in the γ-irradiation of acetic acid, suggesting a common intermediary. Since these molecules fit into a metabolic cycle, it is strongly suggestive that prebiotic pathways provided the basis for biological systems.

  3. Reflectance spectroscopy of oxalate minerals and relevance to Solar System carbon inventories

    NASA Astrophysics Data System (ADS)

    Applin, Daniel M.; Izawa, Matthew R. M.; Cloutis, Edward A.

    2016-11-01

    The diversity of oxalate formation mechanisms suggests that significant concentrations of oxalic acid and oxalate minerals could be widely distributed in the Solar System. We have carried out a systematic study of the reflectance spectra of oxalate minerals and oxalic acid, covering the 0.2-16 μm wavelength region. Our analyses show that oxalates exhibit unique spectral features that enable discrimination between oxalate phases and from other commonly occurring compounds, including carbonates, in all regions of the spectrum except for the visible. Using these spectral data, we consider the possible contribution of oxalate minerals to previously observed reflectance spectra of many objects throughout the Solar System, including satellites, comets, and asteroids. We find that polycarboxylic acid dimers and their salts may explain the reflectance spectra of many carbonaceous asteroids in the 3 μm spectral region. We suggest surface concentration of these compounds may be a type of space weathering from the photochemical and oxidative decomposition of the organic macromolecular material found in carbonaceous chondrites. The stability and ubiquity of these minerals on Earth, in extraterrestrial materials, and in association with biological processes make them useful for many applications in Earth and planetary sciences.

  4. Miniaturizing and automation of free acidity measurements for uranium (VI)-HNO3 solutions: Development of a new sequential injection analysis for a sustainable radio-analytical chemistry.

    PubMed

    Néri-Quiroz, José; Canto, Fabrice; Guillerme, Laurent; Couston, Laurent; Magnaldo, Alastair; Dugas, Vincent

    2016-10-01

    A miniaturized and automated approach for the determination of free acidity in solutions containing uranium (VI) is presented. The measurement technique is based on the concept of sequential injection analysis with on-line spectroscopic detection. The proposed methodology relies on the complexation and alkalimetric titration of nitric acid using a pH 5.6 sodium oxalate solution. The titration process is followed by UV/VIS detection at 650nm thanks to addition of Congo red as universal pH indicator. Mixing sequence as well as method validity was investigated by numerical simulation. This new analytical design allows fast (2.3min), reliable and accurate free acidity determination of low volume samples (10µL) containing uranium/[H(+)] moles ratio of 1:3 with relative standard deviation of <7.0% (n=11). The linearity range of the free nitric acid measurement is excellent up to 2.77molL(-1) with a correlation coefficient (R(2)) of 0.995. The method is specific, presence of actinide ions up to 0.54molL(-1) does not interfere on the determination of free nitric acid. In addition to automation, the developed sequential injection analysis method greatly improves the standard off-line oxalate complexation and alkalimetric titration method by reducing thousand fold the required sample volume, forty times the nuclear waste per analysis as well as the analysis time by eight fold. These analytical parameters are important especially in nuclear-related applications to improve laboratory safety, personnel exposure to radioactive samples and to drastically reduce environmental impacts or analytical radioactive waste.

  5. Highly accurate boronimeter assay of concentrated boric acid solutions

    SciTech Connect

    Ball, R.M. )

    1992-01-01

    The Random-Walk Boronimeter has successfully been used as an on-line indicator of boric acid concentration in an operating commercial pressurized water reactor. The principle has been adapted for measurement of discrete samples to high accuracy and to concentrations up to 6000 ppm natural boron in light water. Boric acid concentration in an aqueous solution is a necessary measurement in many nuclear power plants, particularly those that use boric acid dissolved in the reactor coolant as a reactivity control system. Other nuclear plants use a high-concentration boric acid solution as a backup shutdown system. Such a shutdown system depends on rapid injection of the solution and frequent surveillance of the fluid to ensure the presence of the neutron absorber. The two methods typically used to measure boric acid are the chemical and the physical methods. The chemical method uses titration to determine the ionic concentration of the BO[sub 3] ions and infers the boron concentration. The physical method uses the attenuation of neutrons by the solution and infers the boron concentration from the neutron absorption properties. This paper describes the Random-Walk Boronimeter configured to measure discrete samples to high accuracy and high concentration.

  6. Polymerization of Pu(IV) in aqueous nitric acid solutions

    SciTech Connect

    Toth, L.M.; Friedman, H.A.; Osborne, M.M.

    1980-10-01

    The polymerization of Pu(IV) in aqueous nitric acid solutions has been studied spectrophotometrically both to establish the influence of large UO{sub 2}(NO{sub 3}){sub 2} concentrations on the polymerization rates and, more generally, to review the influence of the major parameters on the polymer reaction. Typically, experiments have been performed at 50{sup 0}C and with 0.05 M Pu in nitric acid solutions that vary in acidity from 0.07 to 0.4 M. An induction period usually precedes the polymer growth stage during which time nucleation of primary hydrolysis products occurs. Uranyl nitrate retards the polymerization reaction by approximately 35% in spite of the counteracting influence of the nitrate ions associated with this solute. The rate of polymer formation, expressed as d(percent polymer)/dt, has been shown to depend on the total plutonium concentration in reactions where the Pu(IV) concentration remained constant; and it is therefore suggested that the polymer reaction rate is not first order with respect to the concentration of plutonium as was previously thought. It has been shown further that accurate acid determinations on stock reagents are essential in order to obtain reliable polymerization experiments. Satisfactory procedures for these analyses did not exist, so appropriate modifications to the iodate precipitation methods were developed. The most ideal plutonium reagent material has been shown to be crystalline Pu(IV) nitrate because it can be added directly to acid solutions without the occurrence of unintentional hydrolysis reactions.

  7. [Sorption of amino acids from aqueous solutions on activated charcoal].

    PubMed

    Nekliudov, A D; Tsibanov, V V

    1985-03-01

    Various methods for quantitative description of amino acid sorption from solutions for parenteral nutrition on activated charcoal were studied under dynamic and static conditions. With the use of the well-known Freindlich and Langmuir absorption isotherms it was shown to be possible to describe in a simplified way the complex multicomponent process of sorption of the amino acids and to estimate their loss at the filtration stage.

  8. Determination of As, Cr, Mo, Sb, Se and V in agricultural soil samples by inductively coupled plasma optical emission spectrometry after simple and rapid solvent extraction using choline chloride-oxalic acid deep eutectic solvent.

    PubMed

    Matong, Joseph M; Nyaba, Luthando; Nomngongo, Philiswa N

    2017-01-01

    A rapid, simple and green ultrasound-assisted extraction method using deep eutectic solvents (DES) for extraction of As, Cr, Mo, Sb, Se and V in soil samples, has been developed. Choline chloride-oxalic acid based DES was used as a solvent. The target analytes were subsequently quantified using inductively coupled plasma optical emission spectrometer (ICP OES). The parameters that affect the extraction of the target analytes was optimized using standard reference material of San Joaquin soil (SRM 2709a). In the optimization step, a two-level full factorial experimental design was used. The factors under investigation include extraction time, sample mass and acid concentration. Under optimized conditions, limits of detection (LOD) and limits of quantification (LOQ) ranged from 0.009 to 0.1 and 0.03-0.3µgg(-1), respectively. The repeatability (n=20) estimated in terms of relative standard deviation (%RSD) ranged from 0.9% to 3.7%. The accuracy of the proposed method was carried out using SRM 2709a. The obtained and certified/ indicative values were statistically in good agreement at 95% confidence level. The proposed method applied for quantification of As, Cr, Mo, Sb, Se and V in real soil samples. For comparison, the analytes of interest were also determined using a conventional acid digestion method. According to the paired t-test, the analytical results were not significant differences at 95% confidence level. The method was found to be accurate, precise and environmentally friendly.

  9. Cultivar-specific seedling vigor and expression of a putative oxalate oxidase germin-like protein in sugar beet (Beta vulgaris L.).

    PubMed

    de los Reyes, Benildo G; McGrath, J Mitchell

    2003-06-01

    For genetic screening and breeding purposes, an in vitro germination system that reflects relative field emergence potential was used to screen for germination-enhancing and stress-induced genes from germinating seedlings from two varieties of sugar beet. Three full-length germin-like protein (GLP) gene classes were recovered from stress-germinated seedlings of a superior emerging variety. GLP gene expression, oxalate oxidase protein activity, the H(2)O(2) content of stressed seedlings, but not catalase activity, were induced by stress germination conditions (e.g. excess water, NaCl, mannitol, or oxalate) in a good emerging hybrid and were not induced in a poor emerging variety. Only one of the three germin-like protein genes ( BvGer165) was differentially regulated, and was induced only in the good emerger. Hydrogen peroxide promoted germination and partially compensated solute-depressed germination percentages. Unlike other solute recovery by hydrogen peroxide regimes, recovery in oxalic acid plus H(2)O(2) was cultivar-independent. A block in oxalate metabolism is postulated to contribute to lower germination under stress in the lower emerging variety. Selection for stress-induced germin expression, or for down-stream targets, presents the first direct target to enable breeding for improved field emergence of sugar beet.

  10. [Calcium oxalate stones and hyperoxaluria secondary to treatment with pyridoxilate].

    PubMed

    Wolf, C; Maistre-Charransol, G; Barthélémy, C; Thomas, E; Thomas, J; Arvis, G; Steg, A

    1985-01-01

    Pyridoxilate is a salt formed from glyoxylic acid and pyridoxine. It has been used therapeutically as an antianoxic drug in the treatment of various arterial complaints. Its use is based theoretically on its ability to block the conversion of glyoxylic acid into oxalic acid. The following cases suggest, however, that pyridoxilate can cause stones. Intraperitoneal injection of glyoxylate in doses of 130 mg/kg will cause oxalate stones in rats. The same effect results from injection of 427 mg/kg pyridoxilate (i.e. an equivalent dose of glyoxylate). In human subjects, intravenous injection of 200 mg of pyridoxilate results in a fourfold increase in the urinary oxalic acid content in the two hours following the injection. Thirteen cases of chronic progressive oxalate stone disease have recently been reported in patients receiving a prolonged course of pyridoxilate at 450 to 600 mg daily. Eight of these patients had no previous history of lithiasis. Oxaluria levels of 80 to 100 mg daily are observed in all cases of lithiasis in patients receiving pyridoxilate. The levels fell after cessation of the pyridoxilate treatment, and reverted to normal (30 mg/24 hours) in all but three patients. These three patients maintained levels of close to 50 mg and all three had a previous history of urolithiasis.

  11. Cocoa shells for heavy metal removal from acidic solutions.

    PubMed

    Meunier, N; Laroulandie, J; Blais, J F; Tyagi, R D

    2003-12-01

    The development of economic and efficient processes for the removal of heavy metals present in acidic effluents from industrial sources or decontamination technologies has become a priority. The purpose of this work was to study the efficiency with which cocoa shells remove heavy metals from acidic solutions (pH 2) and to investigate how the composition of these solutions influences heavy metal uptake efficiency. Adsorption tests were conducted in agitated flasks with single-metal solutions (0.25 mM Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn), multi-metal solution (comprised of 0.25 mM of each of the cations above) and an effluent obtained from chemical leaching of metal-contaminated soil, in the presence of different cocoa shell concentrations (5-40 g/l). Results from the single-metal solution assays indicated that the fixation capacity of heavy metals by cocoa shells followed a specific order: Pb>Cr>Cd=Cu=Fe>Zn=Co>Mn=Ni=Al. Cocoa shells are particularly efficient in the removal of lead from very acidic solutions (q(max)=6.2 mg Pb/g, pH(i)=2.0 and T=22 degrees C). The presence of other metals and cations in solution did not seem to affect the recovery of lead. It was also observed that the maximum metal uptake was reached in less than 2 h. This research has also demonstrated that the removal of metals caused a decline in solution proton concentration (pH increase) and release of calcium, magnesium, potassium and sodium from the cocoa shells.

  12. [Investigation on mechanism of pyrite oxidation in acidic solutions].

    PubMed

    Wang, Nan; Yi, Xiao-Yun; Dang, Zhi; Liu, Yun

    2012-11-01

    The mechanism of pyrite oxidation in acidic solutions was investigated by electrochemical analysis methods, such as open-circuit potential, cyclic voltammetry, Tafel polarization curve and anodic polarization curve, using a pyrite-carbon paste electrode as working electrode. The results showed that the oxidation process of pyrite in acidic solutions was via a two-step reaction: the first step was the dissolution of iron moiety and formation of a passivation film composed of elemental sulphur, metal-deficient sulfide and polysulfide; the second step was the further oxidation of these intermediate products to SO4(2-). The final reaction products of pyrite oxidation were Fe3+ and SO4(2-) in acidic solutions. In addition, the open-circuit potential and corrosion potential were positively shifted, the peak current and the corrosion current were increased with the increase in concentration of H2SO4 solutions. This indicated that increased acidity of the system was advantageous to the oxidation of pyrite.

  13. Methanol Uptake by Low Temperature Aqueous Sulfuric Acid Solutions

    NASA Technical Reports Server (NTRS)

    Iraci, L. T.; Essin, A. M.; Golden, D. M.; Hipskind, R. Stephen (Technical Monitor)

    2001-01-01

    The global methanol budget is currently unbalanced, with source terms significantly larger than the sinks terms. To evaluate possible losses of gaseous methanol to sulfate aerosols, the solubility and reactivity of methanol in aqueous sulfuric acid solutions representative of upper tropospheric and lower stratospheric aerosols is under investigation. Methanol will partition into sulfate aerosols according to its Henry's law solubility. Using standard uptake techniques in a Knudsen cell reactor, we have measured the effective Henry's law coefficient, H*, for cold (196 - 220 K) solutions ranging between 45 and 70 wt % H2SO4. We have found that methanol solubility ranges from approx. 10(exp 5) - 10(exp 7) M/atm for UT/LS conditions. Solubility increases with decreasing temperature and with increasing sulfuric acid content. Although methanol is slightly more soluble than are acetone and formaldehyde, current data indicate that uptake by clean aqueous sulfuric acid particles will not be a significant sink for methanol in the UT/LS. These solubility measurements include uptake due to physical solvation and any rapid equilibria which are established in solution. Reaction between primary alcohols and sulfuric acid does occur, leading to the production of alkyl sulfates. Literature values for the rate of this reaction suggest that formation of CH3OSO3H is not significant over our experimental time scale for solutions below 80 wt % H2SO4. To confirm this directly, results obtained using a complementary equilibrium measurement technique will also be presented.

  14. LAB-SCALE DEMONSTRATION OF PLUTONIUM PURIFICATION BY ANION EXCHANGE, PLUTONIUM (IV) OXALATE PRECIPITATION, AND CALCINATION TO PLUTONIUM OXIDE TO SUPPORT THE MOX FEED MISSION

    SciTech Connect

    Crowder, M.; Pierce, R.

    2012-08-22

    H-Canyon and HB-Line are tasked with the production of PuO{sub 2} from a feed of plutonium metal. The PuO{sub 2} will provide feed material for the MOX Fuel Fabrication Facility. After dissolution of the Pu metal in H-Canyon, the solution will be transferred to HB-Line for purification by anion exchange. Subsequent unit operations include Pu(IV) oxalate precipitation, filtration and calcination to form PuO{sub 2}. This report details the results from SRNL anion exchange, precipitation, filtration, calcination, and characterization tests, as requested by HB-Line1 and described in the task plan. This study involved an 80-g batch of Pu and employed test conditions prototypical of HB-Line conditions, wherever feasible. In addition, this study integrated lessons learned from earlier anion exchange and precipitation and calcination studies. H-Area Engineering selected direct strike Pu(IV) oxalate precipitation to produce a more dense PuO{sub 2} product than expected from Pu(III) oxalate precipitation. One benefit of the Pu(IV) approach is that it eliminates the need for reduction by ascorbic acid. The proposed HB-Line precipitation process involves a digestion time of 5 minutes after the time (44 min) required for oxalic acid addition. These were the conditions during HB-line production of neptunium oxide (NpO{sub 2}). In addition, a series of small Pu(IV) oxalate precipitation tests with different digestion times were conducted to better understand the effect of digestion time on particle size, filtration efficiency and other factors. To test the recommended process conditions, researchers performed two nearly-identical larger-scale precipitation and calcination tests. The calcined batches of PuO{sub 2} were characterized for density, specific surface area (SSA), particle size, moisture content, and impurities. Because the 3013 Standard requires that the calcination (or stabilization) process eliminate organics, characterization of PuO{sub 2} batches monitored the

  15. Distinct effects of oxalate versus malonate on the iron redox chemistry: Implications for the photo-Fenton reaction.

    PubMed

    Xiao, Dongxue; Guo, Yaoguang; Lou, Xiaoyi; Fang, Changling; Wang, Zhaohui; Liu, Jianshe

    2014-05-01

    The dicarboxylic acids oxalate (Oxal) and malonate (Mal) are frequently detected as the final low-molecular-weight organic acids during oxidative degradation of aromatic compounds. Here a distinct effect of Oxal versus Mal on iron-based photocatalytic technologies was reported by testing the degradation efficiency of the dye rhodamine B. The rates of dye degradation in irradiated Fe(III) solutions depended on Fe(III/II) speciation, photoreactivities of Fe complexes and reactivities of Fe(II) complexes with H2O2. Photolysis of the Fe(III)-oxalato complex was favorable due to the formation of O2-, HO2 and OH for oxidizing the dye; however, an excess of H2O2 could quench the excited state of ferrioxalate, decreasing the degradation efficiency. In contrast, activities of UV/Fe(III) in the presence of Mal were significantly diminished because Fe(III)-Mal complexes, with much lower quantum yield of Fe(II) from photoreduction, dominated Fe(III) speciation. The results provide data for an understanding of the mechanism of iron redox (photo)chemistry mediated by diacids, which will aid in selecting appropriate Fe ligands, screening photo-Fenton conditions and designing UV/Fe(III) treatability.

  16. Comparison of the hydrogen-bond patterns in 2-amino-1,3,4-thiadiazolium hydrogen oxalate, 2-amino-1,3,4-thiadiazole-succinic acid (1/2), 2-amino-1,3,4-thiadiazole-glutaric acid (1/1) and 2-amino-1,3,4-thiadiazole-adipic acid (1/1).

    PubMed

    Matulková, Irena; Císařová, Ivana; Němec, Ivan; Fábry, Jan

    2014-10-01

    The X-ray single-crystal structure determinations of the chemically related compounds 2-amino-1,3,4-thiadiazolium hydrogen oxalate, C2H4N3S(+)·C2HO4(-), (I), 2-amino-1,3,4-thiadiazole-succinic acid (1/2), C2H3N3S·2C4H6O4, (II), 2-amino-1,3,4-thiadiazole-glutaric acid (1/1), C2H3N3S·C5H8O4, (III), and 2-amino-1,3,4-thiadiazole-adipic acid (1/1), C2H3N3S·C6H10O4, (IV), are reported and their hydrogen-bonding patterns are compared. The hydrogen bonds are of the types N-H···O or O-H···N and are of moderate strength. In some cases, weak C-H···O interactions are also present. Compound (II) differs from the others not only in the molar ratio of base and acid (1:2), but also in its hydrogen-bonding pattern, which is based on chain motifs. In (I), (III) and (IV), the most prominent feature is the presence of an R2(2)(8) graph-set motif formed by N-H···O and O-H···N hydrogen bonds, which are present in all structures except for (I), where only a pair of N-H···O hydrogen bonds is present, in agreement with the greater acidity of oxalic acid. There are nonbonding S···O interactions present in all four structures. The difference electron-density maps show a lack of electron density about the S atom along the S···O vector. In all four structures, the carboxylic acid H atoms are present in a rare configuration with a C-C-O-H torsion angle of ∼0°. In the structures of (II)-(IV), the C-C-O-H torsion angle of the second carboxylic acid group has the more common value of ∼|180|°. The dicarboxylic acid molecules are situated on crystallographic inversion centres in (II). The Raman and IR spectra of the title compounds are presented and analysed.

  17. Simultaneous treatment of chlorinated organics and removal of metals and radionuclides with bimetals and complexing acids - application to surfactant solutions

    SciTech Connect

    Korte, N.E.; Gu, B.

    1997-10-01

    Currently available methods for separation and treatment of radioactive mixed waste are typically energy-intensive, and often require high temperatures. Passive methods that operate at ambient temperatures are needed. The purpose of this task is to develop bimetallic substrates, using a base metal such as iron and a promoter metal such as palladium (Pd), to provide a passive, low-energy solution to a substantial portion of DOE`s mixed-waste problem. This technology consists of a porous medium that can simultaneously dechlorinate hazardous organics such as TCE and polychlorinated biphenyls (PCBs) at the same time that it removes metallic and hazardous wastes from a solvent/surfactant solution. The porous medium consists of a bimetallic substrate such as palladized iron (Pd/Fe). Palladium is readily chemically plated on iron and preliminary studies suggest that only 0.05 to 0.1% Pd is needed for an efficient reaction. Thus, the cost of the material is reasonable especially is it is long-lived or can be regenerated. Field implementation would consist of the passage of a surfactant-laden, mixed waste through a column or bed of the bimetallic substrate. The organic component of this mixed waste may contain semivolatile compounds such as PCBs or pesticides and herbicides. The bimetal simultaneously removes radionuclides and metals and degrades halogenated hydrocarbons. Virtually any concentration can be treated. Following reaction of the bimetal with the waste stream, the resulting effluent will consist of an uncontaminated aqueous solution of surfactant or solvent that can be reused. The bimetal would then be rinsed with a dilute mineral acid or a mild complexing acid (e.g., oxalic or citric acid) to regenerate the surface and to remove sorbed metals and non-hazardous organic residue. The latter effluent would be low-level radioactive waste in some cases, but it would now be much easier to manage and be of a lower volume than the original mixed waste.

  18. Pretreatment of americium/curium solutions for vitrification

    SciTech Connect

    Rudisill, T.S.

    1996-03-18

    Vitrification will be used to stabilize an americium/curium (Am/Cm) solution presently stored in F-Canyon for eventual transport to the heavy isotope programs at Oak Ridge National Laboratory. Prior to vitrification, an in-tank oxalate precipitation and a series of oxalic/nitric acid washes will be used to separate these elements and lanthanide fission products from the bulk of the uranium and metal impurities present in the solution. Pretreatment development experiments were performed to understand the behavior of the lanthanides and the metal impurities during the oxalate precipitation and properties of the precipitate slurry. The results of these experiments will be used to refine the target glass composition allowing optimization of the primary processing parameters and design of the solution transfer equipment.

  19. Oxalate Mass Balance During Chemical Cleaning in Tank 5F

    SciTech Connect

    Poirier, M.; Fink, S.

    2011-07-08

    The Savannah River Site (SRS) is preparing Tank 5F for closure. The first step in preparing the tank for closure is mechanical sludge removal. Following mechanical sludge removal, SRS performed chemical cleaning with oxalic acid to remove the sludge heel. Personnel are currently assessing the effectiveness of the chemical cleaning to determine whether the tank is ready for closure. SRS personnel collected liquid samples during chemical cleaning and submitted them to Savannah River National Laboratory (SRNL) for analysis. Following chemical cleaning, they collected a solid sample (also known as 'process sample') and submitted it to SRNL for analysis. The authors analyzed these samples to assess the effectiveness of the chemical cleaning process. Analysis of the anions showed the measured oxalate removed from Tank 5F to be approximately 50% of the amount added in the oxalic acid. To close the oxalate mass balance, the author collected solid samples, leached them with nitric acid, and measured the concentration of cations and anions in the leachate.

  20. Evaporation kinetics of acetic acid-water solutions

    NASA Astrophysics Data System (ADS)

    Duffey, K.; Wong, N.; Saykally, R.; Cohen, R. C.

    2012-12-01

    The transport of water molecules across vapor-liquid interfaces in the atmosphere is a crucial step in the formation and evolution of cloud droplets. Despite decades of study, the effects of solutes on the mechanism and rate of evaporation and condensation remain poorly characterized. The present work aims to determine the effect of atmospherically-relevant solutes on the evaporation rate of water. In our experiments, we create a train of micron-sized droplets and measure their temperature via Raman thermometry as they undergo evaporation without condensation. Analysis of the cooling rate yields the evaporation coefficient (γ). Previous work has shown that inorganic salts have little effect on γ, with surface-adsorbing anions causing a slight reduction in the coefficient from that measured for pure water. Organic acids are ubiquitous in aqueous aerosol and have been shown to disrupt the surface structure of water. Here we describe measurements of the evaporation rate of acetic acid solutions, showing that acetic acid reduces γ to a larger extent than inorganic ions, and that γ decreases with increasing acetic acid concentration.

  1. Solution Preserves Nucleic Acids in Body-Fluid Specimens

    NASA Technical Reports Server (NTRS)

    Pierson, Duane L.; Stowe, Raymond P.

    2004-01-01

    A solution has been formulated to preserve deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) in specimens of blood, saliva, and other bodily fluids. Specimens of this type are collected for diagnostic molecular pathology, which is becoming the method of choice for diagnosis of many diseases. The solution makes it possible to store such specimens at room temperature, without risk of decomposition, for subsequent analysis in a laboratory that could be remote from the sampling location. Thus, the solution could be a means to bring the benefits of diagnostic molecular pathology to geographic regions where refrigeration equipment and diagnostic laboratories are not available. The table lists the ingredients of the solution. The functions of the ingredients are the following: EDTA chelates divalent cations that are necessary cofactors for nuclease activity. In so doing, it functionally removes these cations and thereby retards the action of nucleases. EDTA also stabilizes the DNA helix. Tris serves as a buffering agent, which is needed because minor contaminants in an unbuffered solution can exert pronounced effects on pH and thereby cause spontaneous degradation of DNA. SDS is an ionic detergent that inhibits ribonuclease activity. SDS has been used in some lysis buffers and as a storage buffer for RNA after purification. The use of the solution is straightforward. For example, a sample of saliva is collected by placing a cotton roll around in the subject's mouth until it becomes saturated, then the cotton is placed in a collection tube. Next, 1.5 mL of the solution are injected directly into the cotton and the tube is capped for storage at room temperature. The effectiveness of the solution has been demonstrated in tests on specimens of saliva containing herpes simplex virus. In the tests, the viral DNA, as amplified by polymerase chain reaction, was detected even after storage for 120 days.

  2. Experimental alkali feldspar dissolution at 100 degree C by carboxylic acids and their anions

    SciTech Connect

    Stoessell, R.K. ); Pittman, E.D. )

    1990-05-01

    Feldspar dissolution will enhance sandstone porosity if the released aluminum can be transported away in the subsurface waters. Carboxylic acids have been proposed to provide hydrogen ions to promote dissolution and anions to complex aqueous aluminum to keep it in solution. However, the hydrogen ions should react quickly following acid generation in source beds, leaving monocarboxylic anions with lesser amounts of dicarboxylic acids and their anions on feldspar dissolution and the apparent complexing of aluminum in solution. Two-week dissolution experiments of alkali feldspar were run at 100{degree}C and 300 bars in acetic acid, oxalic acid, and sodium salt solutions of chloride, acetate, propionate, oxalate, and malonate. Extrapolation of the results, to reservoir conditions during sandstone diagenesis, implies that concentrations of aluminum-organic complexes are not significant for acetate and propionate and are possibly significant for oxalate and malonate, depending upon fluid compositions. Propionate appeared to inhibit feldspar dissolution and hence might decrease secondary porosity formation. Increases in aluminum concentrations in the presence of oxalic and acetic acid solutions appear to be due to enhanced dissolution kinetics and greater aluminum solubility under low-pH conditions. Such low-pH fluids are generally absent in subsurface reservoirs, making this an unlikely mechanism for enhancing porosity. Furthermore, the observed thermal instability of oxalate and malonate anions explains their general low concentrations in subsurface fluids which limits their aluminum complexing potential in reservoirs during late diagenesis.

  3. Oxalate-minus mutants of Sclerotinia sclerotiorum via random mutagenesis retain pathogenicity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sclerotinia sclerotiorum is a ubiquitous necrotrophic plant pathogen capable of infecting over 400 plant species including many economically important crops. Oxalic acid production has been shown in numerous studies to be a pathogenicity factor for Sclerotinia sclerotiorum through several mechanisms...

  4. A mechanistic study of copper electropolishing in phosphoric acid solutions

    NASA Astrophysics Data System (ADS)

    Mansson, Andrew

    The microelectronics industry is using copper as the interconnect material for microchips. A study of copper electropolishing is important for the process development of a new, low downforce approach, which is being developed to replace chemical mechanical polishing (CMP) of the copper overburden. A promising technology is a combination of electropolishing with conventional CMP. Electropolishing of copper in phosphoric acid has been studied for, more than 70 years. Previous work has shown that the polishing rate, as measured by current density is directly related to the viscosity of the electrolyte. Also, the limiting species is water. In this study, a multidimensional design of experiments was performed to develop an in-depth model of copper electropolishing. Phosphoric acid was mixed with alcohols of different molecular weight and related viscosity to investigate how the solvents' properties affected polishing. The alcohols used were methanol, ethanol, isopropanol, butanol, ethylene glycol, and glycerol. The limiting current densities and electrochemical behavior of each solution was measured by potentiodynamic and potentiostatic experiments. Also, the kinematic viscosity and density were measured to determine the dynamic viscosity to investigate the relationship of current density and viscosity. Water, methanol, ethanol, and isopropanol solutions were also examined at 20°C to 60°C. Next, the relative percentage of dissociated phosphoric acid was measured by Raman spectroscopy for each polishing solution. Raman spectroscopy was also used to measure the relative dissociation of phosphoric acid inside the polishing film. Additionally, wafers were electropolished and electrochemical mechanically polished to investigate the effects of the different solvents, fluid flow, current, and potential. The results of these experiments have shown that the molecular mass and the ability of the solvent to dissociate phosphoric acid are the primary electrolyte properties that

  5. Solution influence on biomolecular equilibria - Nucleic acid base associations

    NASA Technical Reports Server (NTRS)

    Pohorille, A.; Pratt, L. R.; Burt, S. K.; Macelroy, R. D.

    1984-01-01

    Various attempts to construct an understanding of the influence of solution environment on biomolecular equilibria at the molecular level using computer simulation are discussed. First, the application of the formal statistical thermodynamic program for investigating biomolecular equilibria in solution is presented, addressing modeling and conceptual simplications such as perturbative methods, long-range interaction approximations, surface thermodynamics, and hydration shell. Then, Monte Carlo calculations on the associations of nucleic acid bases in both polar and nonpolar solvents such as water and carbon tetrachloride are carried out. The solvent contribution to the enthalpy of base association is positive (destabilizing) in both polar and nonpolar solvents while negative enthalpies for stacked complexes are obtained only when the solute-solute in vacuo energy is added to the total energy. The release upon association of solvent molecules from the first hydration layer around a solute to the bulk is accompanied by an increase in solute-solvent energy and decrease in solvent-solvent energy. The techniques presented are expectd to displace less molecular and more heuristic modeling of biomolecular equilibria in solution.

  6. Acid hydrolysis of cellulose in zinc chloride solution

    SciTech Connect

    Cao, N.J.; Xu, Q.; Chen, L.F.

    1995-12-31

    The efficient conversion of cellulosic materials to ethanol has been hindered by the low yield of sugars, the high energy consumption in pretreatment processes, and the difficulty of recycling the pre-treatment agents. Zinc chloride may provide an alternative for pre-treating biomass prior to the hydrolysis of cellulose. The formation of a zinc-cellulose complex during the pretreatment of cellulose improves the yield of glucose in both the enzymatic and acid hydrolysis of cellulose. Low-temperature acid hydrolysis of cellulose in zinc chloride solution is carried out in two stages, a liquefaction stage and a saccharification stage. Because of the formation of zinc-cellulose complex in the first stage, the required amount of acid in the second stage has been decreased significantly. In 67% zinc chloride solution, a 99.5% yield of soluble sugars has been obtained at 70{degrees}C and 0.5M acid concentration. The ratio of zinc chloride to cellulose has been reduced from 4.5 to 1.5, and the yield of soluble sugars is kept above 80%. The rate of hydrolysis is affected by the ratio of zinc chloride to cellulose, acid concentration, and temperature.

  7. Method for extracting lanthanides and actinides from acid solutions

    DOEpatents

    Horwitz, E. Philip; Kalina, Dale G.; Kaplan, Louis; Mason, George W.

    1985-01-01

    A process for the recovery of actinide and lanthanide values from aqueous acidic solutions with an organic extractant having the formula: ##STR1## where .phi. is phenyl, R.sup.1 is a straight or branched alkyl or alkoxyalkyl containing from 6 to 12 carbon atoms and R.sup.2 is an alkyl containing from 3 to 6 carbon atoms. The process is suitable for the separation of actinide and lanthanide values from fission product values found together in high level nuclear reprocessing waste solutions.

  8. DC diaphragm discharge in water solutions of selected organic acids

    NASA Astrophysics Data System (ADS)

    Vyhnankova, Edita J.; Hammer, Malte U.; Reuter, Stephan; Krcma, Frantisek

    2015-07-01

    Effect of four simple organic acids water solution on a DC diaphragm discharge was studied. Efficiency of the discharge was quantified by the hydrogen peroxide production determined by UV-VIS spectrometry of a H2O2 complex formed with specific titanium reagent. Automatic titration was used to study the pH behaviour after the plasma treatment. Optical emission spectroscopy overview spectra were recorded and detailed spectra of OH band and Hβ line were used to calculate the rotational temperature and comparison of the line profile (reflecting electron concentration) in the acid solutions. Contribution to the topical issue "The 14th International Symposium on High Pressure Low Temperature Plasma Chemistry (HAKONE XIV)", edited by Nicolas Gherardi, Ronny Brandenburg and Lars Stollenwark

  9. Interaction of Ethyl Alcohol Vapor with Sulfuric Acid Solutions

    NASA Technical Reports Server (NTRS)

    Leu, Ming-Taun

    2006-01-01

    We investigated the uptake of ethyl alcohol (ethanol) vapor by sulfuric acid solutions over the range approx.40 to approx.80 wt % H2SO4 and temperatures of 193-273 K. Laboratory studies used a fast flow-tube reactor coupled to an electron-impact ionization mass spectrometer for detection of ethanol and reaction products. The uptake coefficients ((gamma)) were measured and found to vary from 0.019 to 0.072, depending upon the acid composition and temperature. At concentrations greater than approx.70 wt % and in dilute solutions colder than 220 K, the values approached approx.0.07. We also determined the effective solubility constant of ethanol in approx.40 wt % H2SO4 in the temperature range 203-223 K. The potential implications to the budget of ethanol in the global troposphere are briefly discussed.

  10. Nonaqueous solution synthesis process for preparing oxide powders of lead zirconate titanate and related materials

    DOEpatents

    Voigt, J.A.; Sipola, D.L.; Tuttle, B.A.; Anderson, M.T.

    1999-06-01

    A process is disclosed for producing powders of perovskite-type compounds which comprises mixing a metal alkoxide solution with a lead acetate solution to form a homogeneous, clear metal solution, adding an oxalic acid/n-propanol solution to this metal solution to form an easily filterable, free-flowing precursor powder and then calcining this powder. This process provides fine perovskite-phase powders with ferroelectric properties which are particularly useful in a variety of electronic applications. 4 figs.

  11. Nonaqueous solution synthesis process for preparing oxide powders of lead zirconate titanate and related materials

    DOEpatents

    Voigt, James A.; Sipola, Diana L.; Tuttle, Bruce A.; Anderson, Mark T.

    1999-01-01

    A process for producing powders of perovskite-type compounds which comprises mixing a metal alkoxide solution with a lead acetate solution to form a homogeneous, clear metal solution, adding an oxalic acid/n-propanol solution to this metal solution to form an easily filterable, free-flowing precursor powder and then calcining this powder. This process provides fine perovskite-phase powders with ferroelectric properties which are particularly useful in a variety of electronic applications.

  12. Recovery of rhenium from sulfuric acid solutions with activated coals

    SciTech Connect

    Troshkina, I.D.; Naing, K.Z.; Ushanova, O.N.; P'o, V.; Abdusalomov, A.A.

    2006-09-15

    Equilibrium and kinetic characteristics of rhenium sorption from sulfuric acid solutions (pH 2) by activated coals produced from coal raw materials (China) were studied. Constants of the Henry equation describing isotherms of rhenium sorption by activated coals were calculated. The effective diffusion coefficients of rhenium in the coals were determined. The dynamic characteristics of rhenium sorption and desorption were determined for the activated coal with the best capacity and kinetic characteristics.

  13. Effect of Aerva lanata on calcium oxalate urolithiasis in rats.

    PubMed

    Soundararajan, P; Mahesh, R; Ramesh, T; Begum, V Hazeena

    2006-12-01

    Calcium oxalate (CaOx) stone was induced in rats using 0.75% of ethylene glycol in drinking water for 28 days. Ethylene glycol treated rats showed significant increase in the activities of oxalate synthesizing enzymes such as glycolic acid oxidase (GAO) in liver and lactate dehydrogenase (LDH) in liver and kidney. CaOx crystal deposition, as indicated by increased excretion of stone-forming constituents in urine, such as calcium, oxalate, uric acid, phosphorus and protein and decreased concentration of inhibitors, such as citrate and magnesium was observed in ethylene glycol induced urolithic rats. Histopathological studies also confirmed the deposition of CaOx crystals. Administration of Aerva lanata aqueous suspension (2g/kg body wt/dose/day for 28 days) to CaOx urolithic rats had reduced the oxalate synthesizing enzymes, diminished the markers of crystal deposition in the kidney. The results of the present study confirmed that A. lanata can be used as an curative agent for urolithiasis.

  14. Fast hybridization solution for the detection of immobilized nucleic acids.

    PubMed

    Yang, T T; Kain, S R

    1995-03-01

    We have developed a fast hybridization solution, termed ExpressHyb, for the rapid and sensitive detection of nucleic acids immobilized on membrane supports. This solution reduces typical hybridization times of 12-24 h to as little as 1 h while simultaneously increasing the sensitivity of detection in many applications. Using ExpressHyb, human beta-actin mRNA was detected on a human multiple tissue Northern (MTN) blot following a 30-min hybridization, with optimal detection occurring with a 1-h hybridization interval. The moderately abundant human glyceraldehyde-3-phosphate dehydrogenase (G3PDH) mRNA was detected using similar hybridization conditions and yielded improved signal-to-background characteristics relative to overnight hybridizations in conventional solutions. ExpressHyb can be used with either 32P- or digoxigenin-labeled probes and works effectively with both cDNA and oligonucleotide probes. For non-isotopic detection in particular, ExpressHyb reduces the nonspecific background commonly encountered with this technique. In cDNA library screening, ExpressHyb was found to both reduce the time required for effective hybridizations and to increase the number of positive colonies obtained relative to conventional overnight procedures. Taken together, these results illustrate the broad capability of ExpressHyb Hybridization Solution to improve nucleic acid detection in a variety of important techniques.

  15. Methanol Uptake By Low Temperature Aqueous Sulfuric Acid Solutions

    NASA Technical Reports Server (NTRS)

    Iraci, Laura T.; Essin, Andrew M.; Golden, David M.; Hipskind, R. Stephen (Technical Monitor)

    2001-01-01

    To evaluate the role of upper tropospheric and lower stratospheric aerosols in the global budget of methanol, the solubility and reactivity of CH3OH in aqueous sulfuric acid solutions are under investigation. Using standard uptake techniques in a Knudsen cell reactor, we have measured the effective Henry's law coefficient, H(*), for methanol dissolution into 45 to 70 percent by weight H2SO4. We find that methanol solubility ranges from 10(exp 5) to 10(exp 8) M/atm and increases with decreasing temperature and with increasing sulfuric acid content. These solubility measurements include uptake due to physical solvation and all rapid equilibria which are established in solution. Our data indicate that simple uptake by aqueous sulfuric acid particles will not be a significant sink for methanol in the UT/LS. These results differ from those recently reported in the literature, and an explanation of this disparity will be presented. In addition to solvation, reaction between primary alcohols and sulfuric acid does occur, leading to the production of alkyl sulfates. Literature values for the rate of this reaction suggest that formation of CH3OSO3H may proceed in the atmosphere but is not significant under our experimental conditions. Results obtained using a complementary equilibrium measurement technique confirm this directly. In addition, the extent of methanol sequestration via formation of mono- and dimethylsulfate will be evaluated under several atmospheric conditions.

  16. Synthesis of calcium oxalate crystals in culture medium irradiated with non-equilibrium atmospheric-pressure plasma

    NASA Astrophysics Data System (ADS)

    Kurake, Naoyuki; Tanaka, Hiromasa; Ishikawa, Kenji; Nakamura, Kae; Kajiyama, Hiroaki; Kikkawa, Fumitaka; Mizuno, Masaaki; Yamanishi, Yoko; Hori, Masaru

    2016-09-01

    Octahedral particulates several tens of microns in size were synthesized in a culture medium irradiated through contact with a plume of non-equilibrium atmospheric-pressure plasma (NEAPP). The particulates were identified in the crystalline phase as calcium oxalate dihydrate (COD). The original medium contained constituents such as NaCl, d-glucose, CaCl2, and NaHCO3 but not oxalate or oxalic acid. The oxalate was clearly synthesized and crystallized in the medium as thermodynamically unstable COD crystals after the NEAPP irradiation.

  17. Thermochemical comparisons of homogeneous and heterogeneous acids and bases. 1. Sulfonic acid solutions and resins as prototype Broensted acids

    SciTech Connect

    Arnett, E.M.; Haaksma, R.A.; Chawla, B.; Healy, M.H.

    1986-08-06

    Heats of ionization by thermometric titration for a series of bases (or acids) can be used to compare solid acids (or bases) with liquid analogues bearing the same functionalities in homogeneous solutions. The method is demonstrated for Broensted acids by reacting a series of substituted nitrogen bases with solutions of p-toluenesulfonic acid (PTSA) in acetonitrile and with suspensions of the microporous polymeric arylsulfonic acid resin-Dowex 50W-X8 in the same solvent. Under well-controlled anhydrous conditions there is a good correlation (r = 0.992) between the heats of reaction of the bases with the homogeneous and heterogeneous acid systems, but the homogeneous system gives a more exothermic interaction by 3-4 kcal mol/sup -1/ for a series of 29 substituted pyrimidines, anilines, and some other amines. This difference may be attributed to homohydrogen bonding interactions between excess acid and sulfonate anion sites which are more restricted geometrically in the resin than in solution. Other factors which affect the enthalpy change for the acid-base interaction are the acid/base ratio, the water content of the sulfonic acid, the solvent, and the resin structure (e.g., microporous vs. macroporous). Steric hindrance in the base does not differentiate solid from homogeneous acid. In addition to the use of titration calorimetry, heats of immersion are reported for the Dowex-arylsulfonic acid resins and the Nafion-perfluorinated sulfonic acid resin in a series of basic liquids. The results are compared with each other and with those from a previous study of several varieties of coal.

  18. Recovery of hydrochloric acid from the waste acid solution by diffusion dialysis.

    PubMed

    Xu, Jing; Lu, Shuguang; Fu, Dan

    2009-06-15

    Diffusion dialysis using a series of anion exchange membranes was employed to recover HCl acid from the waste acid solution. Effects of flow rate, flow rate ratio of water to feed, and Fe ion concentration on the recovery of HCl were investigated. It was found that the flow rate ratio was an important factor in the diffusion dialysis operation, and the recovered HCl concentration and Fe ion concentration in diffusate decreased significantly with the change of flow rate ratio from 0.4 to 1.7. In addition, the higher the Fe ion concentration in the feed, the higher the Fe leakage in the recovered acid solution. The HCl recovery efficiency was influenced not only by the recovered acid concentration, but also the outlet flow rate. While using the actual pot galvanizing waste HCl solution with the co-existence of 2.70 mol/L of Fe and 0.07 mol/L of Zn ions, over 88% HCl recovery efficiency could be achieved and Fe leakage was within the range of 11-23%. However, over 56% of Zn leakage was found due to the formation of negative Zn complexes in solution, which was unfavorable for the recovered acid reuse.

  19. Toluene nitration in irradiated nitric acid and nitrite solution

    SciTech Connect

    Gracy Elias; Bruce J. Mincher; Stephen P. Mezyk; Jim Muller; Leigh R. Martin

    2011-04-01

    The kinetics, mechanisms, and stable products produced for the aryl alkyl mild ortho-para director - toluene, in irradiated nitric acid and neutral nitrite solutions were investigated using ?, and pulse radiolysis. Electron pulse radiolysis was used to determine the bimolecular rate constants for the reaction of toluene with different transient species produced by irradiation. HPLC with UV detection was primarily used to assess the stable reaction products. GC-MS and LC-MS were used to confirm the results from HPLC. Free-radical nitration reaction products were found in irradiated acidic and neutral media. In acidic medium, the ring substitution and side chain substitution and oxidation produced different nitro products. In ring substitution, nitrogen oxide radicals were added mainly to hydroxyl radical-produced cyclohexadienyl radical, and in side chain substitution they were added to the carbon-centered benzyl radical produced by H-atom abstraction. In neutral nitrite toluene solution, radiolytic ring nitration products approached a statistically random distribution, suggesting a free-radical reaction involving addition of the •NO2 radical.

  20. Acute oxalate nephropathy due to ‘Averrhoa bilimbi’ fruit juice ingestion

    PubMed Central

    Bakul, G.; Unni, V. N.; Seethaleksmy, N. V.; Mathew, A.; Rajesh, R.; Kurien, G.; Rajesh, J.; Jayaraj, P. M.; Kishore, D. S.; Jose, P. P.

    2013-01-01

    Irumban puli (Averrhoa bilimbi) is commonly used as a traditional remedy in the state of Kerala. Freshly made concentrated juice has a very high oxalic acid content and consumption carries a high risk of developing acute renal failure (ARF) by deposition of calcium oxalate crystals in renal tubules. Acute oxalate nephropathy (AON) due to secondary oxalosis after consumption of Irumban puli juice is uncommon. AON due to A. bilimbi has not been reported before. We present a series of ten patients from five hospitals in the State of Kerala who developed ARF after intake of I. puli fruit juice. Seven patients needed hemodialysis whereas the other three improved with conservative management. PMID:23960349

  1. Photodegradation mechanism of sulfadiazine catalyzed by Fe(III), oxalate and algae under UV irradiation.

    PubMed

    Zhang, Junwei; Ma, Li

    2013-01-01

    Photodegradation mechanism of sulfadiazine (SD) in a solution containing Fe(III), oxalate and algae were investigated in this study. The results indicated that the degradation of SD was slow in a solution containing Fe(III) or oxalate, whereas it was markedly enhanced when Fe(III) and oxalate coexisted. The optimal pH for formation of *OH was 4; a higher or lower pH resulted in a decrease in formation of OH. A moderate increase of oxalate concentration was beneficial to the formation of *OH and the degradation of SD, and the algae enhanced the degradation rate of SD in a solution containing Fe(III) and oxalate. Also, the degradation rate of SD rapidly decreased at low initial concentrations but slowly decreased at high initial concentrations, and pseudo-first order kinetics described the degradation process of SD well. A possible reaction mechanism in solution containing Fe(III), oxalate and algae was proposed, and attack by *OH was the main pathway of SD degradation in the photocatalytic reaction.

  2. Crystal growth methods dedicated to low solubility actinide oxalates

    NASA Astrophysics Data System (ADS)

    Tamain, C.; Arab-Chapelet, B.; Rivenet, M.; Grandjean, S.; Abraham, F.

    2016-04-01

    Two novel crystal growth syntheses dedicated to low solubility actinide-oxalate systems and adapted to glove box handling are described. These methods based on the use of precursors of either actinide metal or oxalic acid have been optimized on lanthanide systems (analogue of actinides(III)) and then assessed on real actinide systems. They allow the synthesis of several actinide oxalate single crystals, Am2(C2O4)3(H2O)3·xH2O, Th(C2O4)2·6H2O, M2+x[PuIV2-xPuIIIx(C2O4)5]·nH2O and M1-x[PuIII1-xPuIVx(C2O4)2·H2O]·nH2O. It is the first time that these well-known compounds are formed by crystal growth methods, thus enabling direct structural studies on transuranic element systems and acquisition of basic data beyond deductions from isomorphic (or not) lanthanide compounds. Characterizations by X-ray diffraction, UV-visible solid spectroscopy, demonstrate the potentialities of these two crystal growth methods to obtain oxalate compounds.

  3. Plutonium and Americium Alpha Radiolysis of Nitric Acid Solutions.

    PubMed

    Horne, Gregory P; Gregson, Colin R; Sims, Howard E; Orr, Robin M; Taylor, Robin J; Pimblott, Simon M

    2017-02-02

    The yield of HNO2, as a function of absorbed dose and HNO3 concentration, from the α-radiolysis of aerated HNO3 solutions containing plutonium or americium has been investigated. There are significant differences in the yields measured from solutions of the two different radionuclides. For 0.1 mol dm(-3) HNO3 solutions, the radiolytic yield of HNO2 produced by americium α-decay is below the detection limit, whereas for plutonium α-decay the yield is considerably greater than that found previously for γ-radiolysis. The differences between the solutions of the two radionuclides are a consequence of redox reactions involving plutonium and the products of aqueous HNO3 radiolysis, in particular H2O2 and HNO2 and its precursors. This radiation chemical behavior is HNO3 concentration dependent with the differences between plutonium and americium α-radiolysis decreasing with increasing HNO3 concentration. This change may be interpreted as a combination of α-radiolysis direct effects and acidity influencing the plutonium oxidation state distribution, which in turn affects the radiation chemistry of the system.

  4. Adsorption of organic acids from dilute aqueous solution onto activated carbon

    SciTech Connect

    Wang, S.W.

    1980-06-01

    The radioisotope technique was used to study the removal of organic acid contaminants from dilute aqueous solutions onto activated carbon. Acetic acid, propionic acid, n-butyric acid, n-hexanoic acid and n-heptanoic acid were studied at 278, 298, and 313/sup 0/K. Three bi-solute acid mixtures (acetic and propionic acids, acetic and butanoic acids, and propionic and butanoic acids) were studied at 278 and 298/sup 0/K. Isotherms of the single-solute systems were obtained at three different temperatures in the very dilute concentration region (less than 1% by weight). These data are very important in the prediction of bi-solute equilibrium data. A Polanyi-based competitive adsorption potential theory was used to predict the bi-solute equilibrium uptakes. Average errors between calculated and experimental data ranges from 4% to 14%. It was found that the competitive adsorption potential theory gives slightly better results than the ideal adsorbed solution theory.

  5. Systems solutions by lactic acid bacteria: from paradigms to practice

    PubMed Central

    2011-01-01

    Lactic acid bacteria are among the powerhouses of the food industry, colonize the surfaces of plants and animals, and contribute to our health and well-being. The genomic characterization of LAB has rocketed and presently over 100 complete or nearly complete genomes are available, many of which serve as scientific paradigms. Moreover, functional and comparative metagenomic studies are taking off and provide a wealth of insight in the activity of lactic acid bacteria used in a variety of applications, ranging from starters in complex fermentations to their marketing as probiotics. In this new era of high throughput analysis, biology has become big science. Hence, there is a need to systematically store the generated information, apply this in an intelligent way, and provide modalities for constructing self-learning systems that can be used for future improvements. This review addresses these systems solutions with a state of the art overview of the present paradigms that relate to the use of lactic acid bacteria in industrial applications. Moreover, an outlook is presented of the future developments that include the transition into practice as well as the use of lactic acid bacteria in synthetic biology and other next generation applications. PMID:21995776

  6. Desorption of Mercury(II) on Kaolinite in the Presence of Oxalate or Cysteine

    SciTech Connect

    Senevirathna, W. U.; Zhang, Hong; Gu, Baohua

    2011-01-01

    Sorption and desorption of Hg(II) on clay minerals can impact the biogeochemical cycle and bio- uptake of Hg in aquatic systems. We studied the desorption of Hg(II) on kaolinite in the presence of oxalate or cysteine, representing the ligands with carboxylic and thiol groups of different affinities for Hg(II). The effects of pH (3, 5, 7), ligand concentration (0.25, 1.0 mM), and temperature (15, 25, 35 C) on the Hg(II) desorption were investigated through desorption kinetics. Our study showed that the Hg(II) desorption was pH-dependant. In the absence of any organic ligand, >90% of the previously adsorbed Hg(II) desorbed at pH 3 within 2 h, compared to <10% at pH 7. Similar results were observed in the presence of oxalate, showing that it hardly affected the Hg(II) desorption. Cysteine inhibited the Hg(II) desorption significantly at all the pH tested, especially in the first 80 min with the desorption less than 20%, but it appeared to enhance the Hg(II) desorption afterwards. The effect of ligand concentration on the Hg(II) desorption was small, especially in the presence of oxalate. The effect of temperature on the desorption was nearly insignificant. The effect of the organic acids on the Hg(II) sorption and desorption is explained by the formation of the ternary surface complexes involving the mineral, ligand, and Hg(II). The competition for Hg(II) between the cysteine molecules adsorbed on the particles and in the solution probably can also affect the Hg(II) desorption.

  7. [Rapid determination of eight organic acids in plant tissue by sequential extraction and high performance liquid chromatography].

    PubMed

    Huang, Tianzhi; Wang, Shijie; Liu Xiuming; Liu, Hong; Wu, Yanyou; Luo Xuqiang

    2014-12-01

    A sequential extraction method was developed to determine different forms of oxalate and seven oxalate-metabolism-related organic acids (glyoxylic acid, tartaric acid, glycolic acid, malic acid, acetic acid, citric acid, succinic acid) in plant tissue. The ultra-pure water was used as the extraction medium to obtain water-soluble oxalic acid and the other seven water-soluble organic acids. After the extraction of the water-soluble organic acids, the residues were extracted by dilute hydrochloric acid successively to get the acid-soluble oxalate which entered the liquid phase. A Hypersil ODS column was used with 5 mmol/L potassium dihydrogen phosphate buffer solution (pH 2. 8) as the mobile phase. The diode array detector was set at 210 nm and the column temperature at 30 °C with the injection volume of 5 µL. The flow rate was controlled at different times which allowed a good and rapid separation of the organic acids and hydrochloric acid. Under these conditions, the linear ranges of the method were 1-2000 mg/L for oxalic acid, 25-2,000 mg/L for acetic acid, and 10-2,000 mg/L for glyoxylic acid, tartaric acid, glycolic acid, malic acid, citric acid and succinic acid, with the correlation coefficients of the eight organic acids ≥ 0. 9996. The average recoveries of the eight organic acids in leaves and roots were 93. 5%-104. 4% and 85. 3%-105. 4% with RSDs of 0. 15% -2.43% and 0. 31%-2. 9% (n=7), respectively. The limits of detection ranged from 1 to 10 ng (S/N=3). The results indicated that the method is accurate, rapid and reproducible for the determination of organic acids in plant samples.

  8. Mobilization of soil-borne arsenic by three common organic acids: Dosage and time effects.

    PubMed

    Onireti, Olaronke O; Lin, Chuxia

    2016-03-01

    A batch experiment was conducted to investigate the mobilization of soil-borne arsenic by three common low-molecular-weight organic acids with a focus on dosage and time effects. The results show that oxalic acid behaved differently from citric acid and malic acid in terms of mobilizing As that was bound to iron compounds. At an equivalent molar concentration, reactions between oxalic acid and soil-borne Fe were kinetically more favourable, as compared to those between either citric acid or malic acid and the soil-borne Fe. It was found that reductive dissolution of soil-borne Fe played a more important role in liberating As, as compared to non-reductive reactions. Prior to the 7th day of the experiment, As mobility increased with increasing dose of oxalic acid while there was no significant difference (P > 0.05) in mobilized As among the treatments with different doses of citric acid or malic acid. The dosage effect on soil-borne As mobilization in the citric acid and malic acid treatments became clear only after the 7th day of the experiment. Soluble Ca present in the soils could cause re-immobilization of As by competing with solution-borne Fe for available organic ligands to form practically insoluble organic compounds of calcium (i.e. calcium oxalate). This resulted in transformation of highly soluble organic complexes of iron (i.e. iron oxalate complexes) into slightly soluble organic compounds of iron (i.e. iron oxalate) or free ferric ion, which then reacted with the solution-borne arsenate ions to form practically insoluble iron arsenates in the latter part of the experiment.

  9. A Previously Unknown Oxalyl-CoA Synthetase Is Important for Oxalate Catabolism in Arabidopsis[W

    PubMed Central

    Foster, Justin; Kim, Hyun Uk; Nakata, Paul A.; Browse, John

    2012-01-01

    Oxalate is produced by several catabolic pathways in plants. The best characterized pathway for subsequent oxalate degradation is via oxalate oxidase, but some species, such as Arabidopsis thaliana, have no oxalate oxidase activity. Previously, an alternative pathway was proposed in which oxalyl-CoA synthetase (EC 6.2.1.8) catalyzes the first step, but no gene encoding this function has been found. Here, we identify ACYL-ACTIVATING ENZYME3 (AAE3; At3g48990) from Arabidopsis as a gene encoding oxalyl-CoA synthetase. Recombinant AAE3 protein has high activity against oxalate, with Km = 149.0 ± 12.7 μM and Vmax = 11.4 ± 1.0 μmol/min/mg protein, but no detectable activity against other organic acids tested. Allelic aae3 mutants lacked oxalyl-CoA synthetase activity and were unable to degrade oxalate into CO2. Seeds of mutants accumulated oxalate to levels threefold higher than the wild type, resulting in the formation of oxalate crystals. Crystal formation was associated with seed coat defects and substantially reduced germination of mutant seeds. Leaves of mutants were damaged by exogenous oxalate and more susceptible than the wild type to infection by the fungus Sclerotinia sclerotiorum, which produces oxalate as a phytotoxin to aid infection. Our results demonstrate that, in Arabidopsis, oxalyl-CoA synthetase encoded by AAE3 is required for oxalate degradation, for normal seed development, and for defense against an oxalate-producing fungal pathogen. PMID:22447686

  10. Solution and gas-phase acidities of all-trans (all-E) retinoic acid: an experimental and computational study.

    PubMed

    Abboud, José-Luis M; Koppel, Ilmar A; Uggerud, Einar; Leito, Ivo; Koppel, Ivar; Sekiguchi, Osamu; Kaupmees, Karl; Saame, Jaan; Kütt, Karl; Mishima, Masaaki

    2015-07-27

    Retinoic acid is of fundamental biological importance. Its acidity was determined in the gas phase and in acetonitrile solution by means of mass spectrometry and UV/Vis spectrophotometry, respectively. The intrinsic acidity is slightly higher than that of benzoic acid. In solution, the situation is opposite. The experimental systems were described theoretically applying quantum chemical methods (wave function theory and density functional theory). This allowed the determination of the molecular structure of the acid and its conjugate base, both in vacuo and in solution, and for computational estimates of its acidity in both phases.

  11. Nanomechanical Behavior of Human Molars Soaked in Slight Acid Solutions

    NASA Astrophysics Data System (ADS)

    Fang, Te-Hua; Chang, Win-Jin; Kang, Shao-Hui; Chu, Chia-Chun

    This paper studied the mechanical and chemical properties of hydroxyl apatite (HA) crystal structure in the teeth when human molars were soaked in slight acid solution. First, we soaked the ground and polished molars respectively in the liquor of 30 wt.% H2CO3 and the liquor of 30 wt.% H2O2 for 10, 20, or 60 minutes. Next, we used a nanoindenter to measure the hardness and Young's modulus. Finally, we used a scanning electron microscope (SEM) coupled with energy dispersive spectroscopy (EDS) to analyze the variation of Ca, P and Na in teeth, a high resolution transmitting electron microscope (HRTEM) to observe the arrangement of crystallization phase of HA, and X-ray diffraction (XRD) to analyze the crystallinity of the hexagonal phase of HA. The results showed that the demineralization phenomenon of the calcium-phosphorous compound in teeth made the teeth reduce sharply in hardness and Young's modulus after they were soaked in the two slight acid solutions for 10 minutes, but the re-mineralization phenomenon made the hardness and Young's modulus ascend gradually when the time lasted longer. With the same period of time, the teeth soaked in H2CO3 were lower in the hardness and Young's modulus than that in H2O2.

  12. Electrocatalytic hydrogenation of 5-hydroxymethylfurfural in acidic solution.

    PubMed

    Kwon, Youngkook; Birdja, Yuvraj Y; Raoufmoghaddam, Saeed; Koper, Marc T M

    2015-05-22

    Electrocatalytic hydrogenation of 5-hydroxymethylfurfural (HMF) is studied on solid metal electrodes in acidic solution (0.5 M H2 SO4 ) by correlating voltammetry with on-line HPLC product analysis. Three soluble products from HMF hydrogenation are distinguished: 2,5-dihydroxymethylfuran (DHMF), 2,5-dihydroxymethyltetrahydrofuran (DHMTHF), and 2,5-dimethyl-2,3-dihydrofuran (DMDHF). Based on the dominant reaction products, the metal catalysts are divided into three groups: (1) metals mainly forming DHMF (Fe, Ni, Cu, and Pb), (2) metals forming DHMF and DMDHF depending on the applied potentials (Co, Ag, Au, Cd, Sb, and Bi), and (3) metals forming mainly DMDHF (Pd, Pt, Al, Zn, In, and Sb). Nickel and antimony are the most active catalysts for DHMF (0.95 mM cm(-2) at ca. -0.35 VRHE and -20 mA cm(-2) ) and DMDHF (0.7 mM cm(-2) at -0.6 VRHE and -5 mA cm(-2) ), respectively. The pH of the solution plays an important role in the hydrogenation of HMF: acidic condition lowers the activation energy for HMF hydro-genation and hydrogenates the furan ring further to tetrahydrofuran.

  13. Precipitation of sodium acid urate from electrolyte solutions

    NASA Astrophysics Data System (ADS)

    Füredi-Milhofer, Helga; Babić-Ivaniĉić, Vesna; Milat, Ognjen; Brown, Walter E.; Gregory, Thomas M.

    1987-07-01

    The precipitation of soduim urate from solutions containing uric acid, soduim hydroxide, hydrochloric acid, sodium chloride and water was investigated at constant pH (7.5±0.1) and temperature (308 K). Precipitates were observed by lights and electron microscopy and characterized by electron and X-ray diffraction. The results are presented in the form of "precipitation" and "chemical potential" diagrams, the latter giving the soduim-to-urate molar ratios of the precipitates. Two types of precipitation boundaries were observed, both of which had indicated soduim-to-urate moral ratios of 1:1. The ion activity product, (Na +)(HU -), associated with boundary I was AP I=(4.8±1.1)×10 -5 and with boundary II was with boundary II was AP II=(6.5±0.4)×10 -4. The supersaturation, S, at boundary II was S=AP II/ Ksp=12.3, in which Ksp is the solubility product of soduim acid urate monohydrate. The latter precipitated as well-formed crystals at supersaturations of 12.3 and above. The ion activity product associated with boundary I is approximately equal to the solubility product of soduim acid urate monohydrate. Small amounts of several morphologically different sodium urate crystals formed in the range of supersaturations (1≤ S≤12.3). Crystals formed in this range may include the monohydrate of sodium acid urate and possibly a higher hydrate. The findings have relevance to pathological renal stone formation and gouty arthritis.

  14. OXALATE FORMATION FROM GLYOXAL IN ERYTHROCYTES

    PubMed Central

    Knight, John; Wood, Kyle D.; Lange, Jessica N.; Assimos, Dean G.; Holmes, Ross P.

    2015-01-01

    OBJECTIVES To determine whether glyoxal can be converted to oxalate in human erythrocytes. Glyoxal synthesis is elevated in diabetes, cardiovascular disease and other diseases with significant oxidative stress. Erythrocytes are a good model system for such studies as they lack intracellular organelles and have a simplified metabolism. METHODS Erythrocytes were isolated from healthy volunteers and incubated with varying concentrations of glyoxal for different amounts of time. Metabolic inhibitors were used to help characterize metabolic steps. The conversion of glyoxal to glycolate and oxalate in the incubation medium was determined by chromatographic techniques. RESULTS The bulk of the glyoxal was converted to glycolate but ~1% was converted to oxalate. Inclusion of the pro-oxidant, menadione, in the medium increased oxalate synthesis, and the inclusion of disulfiram, an inhibitor of aldehyde dehydrogenase activity, decreased oxalate synthesis. CONCLUSIONS The glyoxalase system, which utilizes glutathione as a cofactor, converts the majority of the glyoxal taken up by erythrocytes to glycolate but a small portion is converted to oxalate. A reduction in intracellular glutathione increases oxalate synthesis and a decrease in aldehyde dehydrogenase activity lowers oxalate synthesis and suggests that glyoxylate is an intermediate. Thus, oxidative stress in tissues could potentially increase oxalate synthesis. PMID:26546809

  15. Genome-Wide Screen for Oxalate-Sensitive Mutants of Saccharomyces cerevisiae▿ †

    PubMed Central

    Cheng, V.; Stotz, H. U.; Hippchen, K.; Bakalinsky, A. T.

    2007-01-01

    Oxalic acid is an important virulence factor produced by phytopathogenic filamentous fungi. In order to discover yeast genes whose orthologs in the pathogen may confer self-tolerance and whose plant orthologs may protect the host, a Saccharomyces cerevisiae deletion library consisting of 4,827 haploid mutants harboring deletions in nonessential genes was screened for growth inhibition and survival in a rich medium containing 30 mM oxalic acid at pH 3. A total of 31 mutants were identified that had significantly lower cell yields in oxalate medium than in an oxalate-free medium. About 35% of these mutants had not previously been detected in published screens for sensitivity to sorbic or citric acid. Mutants impaired in endosomal transport, the rgp1Δ, ric1Δ, snf7Δ, vps16Δ, vps20Δ, and vps51Δ mutants, were significantly overrepresented relative to their frequency among all verified yeast open reading frames. Oxalate exposure to a subset of five mutants, the drs2Δ, vps16Δ, vps51Δ, ric1Δ, and rib4Δ mutants, was lethal. With the exception of the rib4Δ mutant, all of these mutants are impaired in vesicle-mediated transport. Indirect evidence is provided suggesting that the sensitivity of the rib4Δ mutant, a riboflavin auxotroph, is due to oxalate-mediated interference with riboflavin uptake by the putative monocarboxylate transporter Mch5. PMID:17644632

  16. Experimental study of aluminum-oxalate complexing at 80 °C: Implications for the formation of secondary porosity within sedimentary reservoirs

    NASA Astrophysics Data System (ADS)

    Fein, Jeremy B.

    1991-10-01

    An experimental study of aluminum-oxalate complexing at 80 °C indicates that the presence of oxalate in sedimentary basin fluids may play an important role in creating secondary porosity in reservoir rocks. The solubility of gibbsite was measured as a function of oxalate concentration. Geologically realistic oxalate concentrations were used in order to simulate the aluminum mobilities that occur in reservoir fluids. Although the stoichiometry of the important aluminum-oxalate species cannot be determined from these data, the results are used to quantify the minimum extent of aluminum-oxalate complexing that occurs in solution. Assuming that Al(Ox)33- is the only important aluminum-oxalate complex, the data limit the log of the dissociation constant of Al(Ox)33- to be ≤-16.5. Thermodynamic modeling of aluminum systems with fluids that contain NaCl, acetate, and oxalate illustrates that aluminum-oxalate complexing is much more important than aluminum-acetate complexing, even at relatively low oxalate concentrations and at very high acetate concentrations. In addition, these calculations show that aluminum-oxalate complexing can greatly increase aluminum mobility in formation waters and, therefore, may increase aluminosilicate mineral dissolution within sedimentary basin fluid-rock systems.

  17. Corrosion behavior of mild steel in acetic acid solutions

    SciTech Connect

    Singh, M.M.; Gupta, A.

    2000-04-01

    The corrosion behavior of mild steel in acetic acid (CH{sub 3}COOH) solutions was studied by weight loss and potentiostatic polarization techniques. The variation in corrosion rate of mild steel with concentrations of CH{sub 3}COOH, evaluated by weight loss and electrochemical techniques, showed marked resemblance. From both techniques, the maximum corrosion rate was observed for 20% CH{sub 3}COOH solution at all three experimental temperatures (25, 35, and 45 C). Anodic polarization curves showed active-passive behavior at each concentration, except at 80% CH{sub 3}COOH. Critical current density (i{sub c}) passive current density (I{sub n}), primary passivation potential (E{sub pp}), and potential for passivity (E{sub p}) had their highest values in 20% CH{sub 3}COOH solution. With an increase in temperature, while the anodic polarization curves shifted toward higher current density region at each concentration, the passive region became progressively less distinguishable. With the addition of sodium acetate (NaCOOCH{sub 3}) as a supporting electrolyte, the passive range was enlarged substantially. However, the transpassive region commenced at more or less the same potential. Cathodic polarization curves were almost identical irrespective of the concentration of CH{sub 3}COOH or temperature.

  18. Conformation of poly(γ-glutamic acid) in aqueous solution.

    PubMed

    Muroga, Yoshio; Nakaya, Asami; Inoue, Atsuki; Itoh, Daiki; Abiru, Masaya; Wada, Kaori; Takada, Masako; Ikake, Hiroki; Shimizu, Shigeru

    2016-04-01

    Local conformation and overall conformation of poly(γ-DL-glutamic acid) (PγDLGA) and poly(γ-L-glutamic acid) (PγLGA) in aqueous solution was studied as a function of degree of ionization ε by (1) H-NMR, circular dichroism, and potentiometric titration. It was clarified that their local conformation is represented by random coil over an entire ε range and their overall conformation is represented by expanded random-coil in a range of ε > ε(*) , where ε(*) is about 0.3, 0.35, 0.45, and 0.5 for added-salt concentration of 0.02M, 0.05M, 0.1M, and 0.2M, respectively. In a range of ε < ε(*) , however, ε dependence of their overall conformation is significantly differentiated from each other. PγDLGA tends to aggregate intramolecularly and/or intermolecularly with decreasing ε, but PγLGA still behaves as expanded random-coil. It is speculated that spatial arrangement of adjacent carboxyl groups along the backbone chain essentially affects the overall conformation of PγGA in acidic media.

  19. Infrared optical constants of H2O ice, amorphous nitric acid solutions, and nitric acid hydrates

    NASA Technical Reports Server (NTRS)

    Toon, Owen B.; Koehler, Birgit G.; Middlebrook, Ann M.; Tolbert, Margaret A.; Jordon, Joseph

    1994-01-01

    We determined the infrared optical constants of nitric acid trihydrate, nitric acid dihydrate, nitric acid monohydrate, and solid amorphous nitric acid solutions which crystallize to form these hydrates. We have also found the infrared optical constants of H2O ice. We measured the transmission of infrared light throught thin films of varying thickness over the frequency range from about 7000 to 500/cm at temperatures below 200 K. We developed a theory for the transmission of light through a substrate that has thin films on both sides. We used an iterative Kramers-Kronig technique to determine the optical constants which gave the best match between measured transmission spectra and those calculated for a variety of films of different thickness. These optical constants should be useful for calculations of the infrared spectrum of polar stratospheric clouds.

  20. The solvent effect on the acidities of haloacetic acids in aqueous solution. A RISM-SCF study

    NASA Astrophysics Data System (ADS)

    Kawata, Masaaki; Ten-no, Seiichiro; Kato, Shigeki; Hirata, Fumio

    1995-06-01

    The acidities of acetic, fluoracetic and chloroacetic acids in aqueous solution are calculated by means of the ab initio method combined with the reference interaction site method in the statistical mechanics of molecular liquids (the RISM-SCF method). The inversion in the order of acidities experimentally observed when a series of haloacetic acids is immersed into aqueous solution is reproduced. It is shown that the inversion is caused by competition between substitution and solvation effects. The solvation effect is discussed in molecular detail in terms of the charge distribution of the solute and the solute-solvent radial distribution functions.

  1. [Correlations between the metastable solutions of calculus-forming salts and crystals from coexistent insoluble urinary components].

    PubMed

    Leskovar, P; Hartung, R

    1978-09-01

    The correlations between the individual stone-forming systems, expecially the induction of heterogeneous crystallization from metastable solutions of one stone-forming system by preformed crystals of the other stone-forming system, were measured semiquantitatively by the Coulter-Counter-Size Distribution Analyzer technique. It has been found out that Ca-oxalate crystals may represent potent triggers and accelerators of the phosphate precipitation from metastable Ca-phosphate solutions. The importance of this phenomenon could be attributed especially to the induction of crystal rich phosphate crystalluria at moderate pH values (6,5--6,8) by the preceding Ca-oxalate crystalluria (,,starter "resp." primer "crystalluria). The favouring, promoting influence of uric acid on the stone formation and growth of Ca-oxalate crystals could be observed with the same experiments under changed conditions. This mechanism could be of some importance in the case when Ca-oxalate precipitates from the urine, saturated by uric acid, at low pH values (5,0--6,0). Uric acid resp. sodium urate crystals showed a moderate by clear favouring effect on the formation of Ca-phosphate crystals from metastable solutions. The influence of Ca-phosphate crystals upon the growth of Ca-oxalate crystals proved to be very limited.

  2. The extraction of actinides from nitric acid solutions with diamides of dipicolinic acid

    NASA Astrophysics Data System (ADS)

    Lapka, Joseph L.; Paulenova, Alena; Alyapyshev, Mikhail Yu; Babain, Vasiliy A.; Law, Jack D.; Herbst, R. Scott

    2010-03-01

    Diamides of dipicolinic acid (N,N'-diethyl-N,N'-ditolyl-dipicolinamide, EtTDPA) were synthesized and evaluated for their extraction capability for actinides. In this work the extractions of neptunium(V), protactinium(V), and thorium(IV) with EtTDPA in a polar fluorinated diluent from nitric acid were investigated. EtTDPA shows a high affinity for Th(IV) even at millimolar concentrations. Np(V) and Pa(V) are both reasonably extractable with EtTDPA; however, near saturated solutions are required to achieve appreciable distribution ratios. A comparison with previously published actinide extraction data is given.

  3. Radiolysis gases from nitric acid solutions containing HSA and HAN

    SciTech Connect

    Smith, J.R.

    1994-10-28

    The concentration of hydrogen (H{sub 2}) in the radiolytically produced off-gas from 2.76-4.25M HNO{sub 3}/PU solutions has been found to be greatly reduced in the presence of sulfamic acid (HSA) and hydroxylamine nitrate (HAN). The H{sub 2} concentration ([H{sub 2}]) is reduced from 35 percent to about 4 percent by dilution caused from an increase in the production rates of nitrogen (N{sub 2}), nitrous oxide (N{sub 2}O), and oxygen (O{sub 2}) gases. The generation rate of H{sub 2} was not affected by HSA or HAN giving a measured radiolytic yield, G(H{sub 2}), value of 0.201 molecules/100 eV for 2.765M NO{sub 3}{sup -} solution (a value of 0.213 is predicted from previous data). The G(H{sub 2}) values are dependent on the solution nitrate concentration ([NO{sub 3}{sup -}]). The generation rates of N{sub 2}, N{sub 2}O, and O{sub 2} are not dependent on the [NO{sub 3}{sup -}] in this narrow range, but are dependent on the presence of HSA and the concentration of HAN. The percentage [H{sub 2}] for the 2.5 to 3.0M NO{sub 3}{sup -} range expected in the off- from the FB-Line Pu{sup +3} Hold Tanks is conservatively estimated to be about 3.5 to 4.5 % for Pu + 3 solutions initially containing 0.023M HAN/0.165M HSA. The upper limit [H{sub 2}] may actually be about 4.1 % (4.3 % at 90 % confidence limits) but more {open_quotes}initial{close_quotes} off-gas rate data is needed at about 2.9M [NO{sub 3}{sup -}] in Pu{sup +3} solution for verification. Addition of ascorbic acid had no effect on the off-gas rate of Pu{sup +3} solutions containing HSA and NO{sub 3}{sup -} concentrations higher than those expected in the hold tanks. The maximum {open_quotes}hold time{close_quotes} for 50 grams/liter Pu{sup +3}/0.165M HSA/0.023M HAN/2.5-3.0M HNO{sub 3} solution is 20.3{+-}2.1 days. After this time the HSA initially present will become exhausted and the [H{sub 2}] will increase to 35 %. This hold time may be longer in [NO{sub 3}{sup -}] < 3.0M, but again more study is needed.

  4. Optical properties of chitosan in aqueous solution of L- and D-ascorbic acids

    NASA Astrophysics Data System (ADS)

    Malinkina, Olga N.; Shipovskaya, Anna B.; Kazmicheva, Olga F.

    2016-04-01

    The optical properties of aqueous chitosan solutions in L- and D-ascorbic acids were studied by optical rotatory dispersion and spectrophotometry. The specific optical rotation [α] of all chitosan solutions tested was positive, in contrast to aqueous solutions of the ascorbic acid enantiomers, which exhibit an inverse relationship of [α] values. Significant differences in the absolute values of [α] of the chitosan solutions at polymer-acid ratios exceeding the equimolar one were found.

  5. Association analysis for oxalate concentration in spinach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Screening and breeding low-oxalate germplasm is a major objective in spinach breeding. This research aims to conduct association analysis and identify SNP markers associated with oxalate concentration in spinach germplasm. A total of 310 spinach genotypes including 300 USDA germplasm accessions and ...

  6. Engineering calcium oxalate crystal formation in Arabidopsis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Many plants accumulate crystals of calcium oxalate. Just how these crystals form remains unknown. To gain insight into the mechanisms regulating calcium oxalate crystal formation, a crystal engineering approach was initiated utilizing the non-crystal accumulating plant, Arabidopsis. The success of t...

  7. pH dependency of sclerotial development and pathogenicity revealed by using genetically defined oxalate-minus mutants of Sclerotinia sclerotiorum.

    PubMed

    Xu, Liangsheng; Xiang, Meichun; White, David; Chen, Weidong

    2015-08-01

    The devastating plant pathogen Sclerotinia sclerotiorum produces copious (up to 50 mM) amounts of oxalic acid, which, for over a quarter century, has been claimed as the pathogenicity determinant based on UV-induced mutants that concomitantly lost oxalate production and pathogenicity. Such a claim was made without fulfilling the molecular Koch's postulates because the UV mutants are genetically undefined and harbour a developmental defect in sclerotial production. Here, we generated oxalate-minus mutants of S. sclerotiorum using two independent mutagenesis techniques, and tested the resulting mutants for growth at different pHs and for pathogenicity on four host plants. The oxalate-minus mutants accumulated fumaric acid, produced functional sclerotia and have reduced ability to acidify the environment. The oxalate-minus mutants retained pathogenicity on plants, but their virulence varied depending on the pH and buffering capacity of host tissue. Acidifying the host tissue enhanced virulence of the oxalate-minus mutants, whereas supplementing with oxalate did not. These results suggest that it is low pH, not oxalic acid itself, that establishes the optimum conditions for growth, reproduction, pathogenicity and virulence expression of S. sclerotiorum. Exonerating oxalic acid as the primary pathogenicity determinant will stimulate research into identifying additional candidates as pathogenicity factors towards better understanding and managing Sclerotinia diseases.

  8. Experimental oxalate urolith formation in rats.

    PubMed

    McIntosh, G H; Belling, G B; Bulman, F H

    1979-06-01

    Urinary calculi composed of calcium oxalate were produced in male hooded Wistar rats fed a vitamin B6 deficient diet over 16 weeks. This basic diet was modified by doubling the phosphate content or loading with vitamin C or D3 in three treatment groups. The number of rats developing oxalate stones was not altered by the addition of vitamin D3 or phosphate, but there was a significant increase in total weight of stone formed and histological evidence of extensive renal damage in rats on the high vitamin D3 diet. The addition of vitamin C to the vitamin B6 deficient rats resulted in a reduction in the number of rats with uroliths and a fall in urinary oxalate excretion, while similarly loaded vitamin B6 supplemented controls were free of oxalate calculi. It is concluded that the oxalate urolithiasis induced by vitamin B6 deficiency was exacerbated by added vitamin D3 and reduced by vitamin C.

  9. The oxalate-carbonate pathway: at the interface between biology and geology

    NASA Astrophysics Data System (ADS)

    Junier, P.; Cailleau, G.; Martin, G.; Guggiari, M.; Bravo, D.; Clerc, M.; Aragno, M.; Job, D.; Verrecchia, E.

    2012-04-01

    The formation of calcite in otherwise carbonate-free acidic soils through the biological degradation of oxalate is a mechanism termed oxalate-carbonate pathway. This pathway lies at the interface between biological and geological systems and constitutes an important, although underestimated, soil mineral carbon sink. In this case, atmospheric CO2 is fixed by the photosynthetic activity of oxalogenic plants, which is partly destined to the production of oxalate used for the chelation of metals, and particularly, calcium. Fungi are also able to produce oxalate to cope with elevated concentrations of metals. In spite of its abundance as a substrate, oxalate is a very stable organic anion that can be metabolized only by a group of bacteria that use it as carbon and energy sources. These bacteria close the biological cycle by degrading calcium oxalate, releasing Ca2+ and inducing a change in local soil pH. If parameters are favourable, the geological part of the pathway begins, because this change in pH will indirectly lead to the precipitation of secondary calcium carbonate (calcite) in unexpected geological conditions. Due to the initial acidic soil conditions, and the absence of geological carbonate in the basement, it is unexpected to find C in the form of calcite. The activity of the oxalate-carbonate pathway has now been demonstrated in several places around the world, suggesting that its importance can be even greater than expected. In addition, new roles for each of the biological players of the pathway have been revealed recently forcing us to reconsider a global biogeochemical model for oxalate cycling.

  10. Uptake of ozone to mixed sodium bromide/ citric acid solutions

    NASA Astrophysics Data System (ADS)

    Lee, Ming-Tao; Steimle, Emilie; Bartels-Rausch, Thorsten; Kato, Shunsuke; Lampimäki, Markus; Brown, Matthew; van Bokhoven, Jeroen; Nolting, Frithjof; Kleibert, Armin; Türler, Andreas; Ammann, Markus

    2013-04-01

    Sea-salt solution - air interfaces play an important role in the chemistry of the marine boundary layer. The reaction of ozone (O3) with bromide is of interest in the context of formation of photolabile halogens (Br2, BrCl) in the marine boundary layer. Recent experiments have suggested that the bromide oxidation rate is related to the surface concentration of bromide [1] and inversely related to the gas phase concentration of O3, an indication for a precursor mediated reaction at the surface [2]. So far, the effect of organics (such as those occurring at the ocean surface or in marine aerosols) on the reaction of O3 with bromide aerosols has not been studied yet. In our study we investigate the uptake kinetics of O3 to a mixed solution of sodium bromide (NaBr) and citric acid (CA), which represents highly oxidized organic compounds present in the environment, with a well-established coated wall flow tube technique, which leads to exposure of the film to O3 allowing the heterogeneous reactions to take place and the loss of O3 being measured. The results indicate that the uptake of O3 to the films with the higher bromide concentrations (0.34M and 4M) is independent of the gas phase concentration and roughly consistent with uptake limited by reaction in the bulk. For the lower bromide concentration (84mM), however, we observe a trend of the uptake coefficient to decrease with increasing O3 concentration, indicating an increasing importance of a surface reaction. In an attempt to constrain the kinetic data, we employed X-ray photoelectron spectroscopy (XPS) to get insight into the surface composition of the aqueous solution - air interface. Previous XPS studies have shown that halide ion concentrations are enhanced at the aqueous solution air interface [3-4], which likely promotes the surface reactions of bromide or iodide with O3. A first XPS study of ternary solutions of KI with butanol indicated the importance of specific interactions of the cation with the alcohol

  11. Oxalate metabolism in magnesium-deficient rats.

    PubMed

    Rattan, V; Thind, S K; Jethi, R K; Sidhu, H; Nath, R

    1993-06-01

    Male weanling rats were maintained on magnesium-deficient diet for 30 d and compared with pair-fed control rats fed magnesium-supplemented diet. Magnesium deficiency led to slow growth and finally to a significant decrease in body weight (P < 0.001) accompanied by a significant hypomagnesaemia, hypomagnesuria and hyperoxaluria (P < 0.001 in each case) in experimental rats as compared to the control rats. Magnesium deficiency altered the glyoxylate metabolism in the liver and kidney mitochondria by significantly decreasing glyoxylate oxidation (by 26 per cent in liver and 17 per cent in kidney) and activity of alpha-ketoglutarate:glyoxylate carboligase enzyme (by 35 per cent in liver and 27 per cent in kidney) in the experimental animals. A significant increase in the specific activities of glycolic acid oxidase (P < 0.001) and glycolic acid dehydrogenase (P < 0.01) and a significant decrease in alanine transaminase (P < 0.01) was also observed in magnesium-deficient rats. No change in liver and kidney lactate dehydrogenase was observed. Thus magnesium deficiency in rats leads to accumulation of glyoxylate in the tissues, a part of which is converted into oxalate, thereby promoting hyperoxaluria.

  12. Compatible solute influence on nucleic acids: Many questions but few answers

    PubMed Central

    Kurz, Matthias

    2008-01-01

    Compatible solutes are small organic osmolytes including but not limited to sugars, polyols, amino acids, and their derivatives. They are compatible with cell metabolism even at molar concentrations. A variety of organisms synthesize or take up compatible solutes for adaptation to extreme environments. In addition to their protective action on whole cells, compatible solutes display significant effects on biomolecules in vitro. These include stabilization of native protein and nucleic acid structures. They are used as additives in polymerase chain reactions to increase product yield and specificity, but also in other nucleic acid and protein applications. Interactions of compatible solutes with nucleic acids and protein-nucleic acid complexes are much less understood than the corresponding interactions of compatible solutes with proteins. Although we may begin to understand solute/nucleic acid interactions there are only few answers to the many questions we have. I summarize here the current state of knowledge and discuss possible molecular mechanisms and thermodynamics. PMID:18522725

  13. HYDROGEN CHEMISORPTION ON Pt SINGLE CRYSTAL SURFACES IN ACIDIC SOLUTIONS

    SciTech Connect

    Ross, Jr., Philip N.

    1980-04-01

    Hydrogen chemisorption from dilute acidic solution onto Pt single crystal surfaces was examined using an electrochemical cell directly coupled to LEED/Auger analytical system. No pre-anodization was used prior to observing hydrogen adsorption by cyclic voltammetry so that clean surfaces having the ordered structures indicated by LEED were studied. The problem of contributions from non-ordered parts of the electrode like support wires and edges was solved by using a gold evaporation masking technique. The specific contribution of atomic imperfections to the voltammetry curve was deduced from the ordered and countable imperfections occurring on high Miller index single crystal surfaces that have a stepped structure. The H-Pt bond energy Has found to be structure sensitive, and sensitive both to local site geometry and long range order in the surface. The bond strength was found to vary systematically: n(111)x(100) > (100) > n(111)x(111) > (110) > (111). Distinct states for hydrogen at steps versus hydrogen on terraces could be distinguished. The (110) surface is shown to be a (111) vicinal, probably the [3(111) x 2(111)] microfacetted surface. The zero coverage heat of adsorption on the well-ordered (111) surface (48 kJ/mol) in solutions is the same as the value reported by Ertl and co-workers for adsorption on a (111) surface in vacuum. Adsorption Isotherms for hydrogen on the (111) and (100) surfaces is adequately fit by the classical model for immobile adsorption at single sites with nearest neighbor repulsive interaction.

  14. Synthesis of labeled oxalic acid derivatives

    DOEpatents

    Martinez, Rodolfo A.; Unkefer, Clifford J.; Alvarez, Marc A.

    2004-06-22

    The present invention is directed to labeled compounds, specifically ##STR1## where each C* is selected from the group consisting of a carbon-12, i.e., .sup.12 C, or a carbon-13, i.e., .sup.13 C and at least one C* is .sup.13 C, R.sup.1 is selected from the group of C.sub.1 -C.sub.4 lower alkyl and aryl, and X is selected from the group of --NR.sup.2 R.sup.3 where R.sup.2 and R.sup.3 are each independently selected from the group of C.sub.1 -C.sub.4 lower alkyl, alkoxy and aryl, --SR.sup.4 where R.sup.4 is selected from the group of C.sub.1 -C.sub.4 lower alkyl, alkoxy and aryl, and --OR.sup.5 where R.sup.5 is selected from the group of C.sub.1 -C.sub.4 lower alkyl, alkoxy and aryl with the proviso that when R.sup.1 is methyl then R.sup.5 is other than methyl, when R.sup.1 is ethyl then R.sup.5 is other than ethyl, and when R.sup.1 is benzyl then R.sup.5 is other than benzyl.

  15. A review of plutonium oxalate decomposition reactions and effects of decomposition temperature on the surface area of the plutonium dioxide product

    NASA Astrophysics Data System (ADS)

    Orr, R. M.; Sims, H. E.; Taylor, R. J.

    2015-10-01

    Plutonium (IV) and (III) ions in nitric acid solution readily form insoluble precipitates with oxalic acid. The plutonium oxalates are then easily thermally decomposed to form plutonium dioxide powder. This simple process forms the basis of current industrial conversion or 'finishing' processes that are used in commercial scale reprocessing plants. It is also widely used in analytical or laboratory scale operations and for waste residues treatment. However, the mechanisms of the thermal decompositions in both air and inert atmospheres have been the subject of various studies over several decades. The nature of intermediate phases is of fundamental interest whilst understanding the evolution of gases at different temperatures is relevant to process control. The thermal decomposition is also used to control a number of powder properties of the PuO2 product that are important to either long term storage or mixed oxide fuel manufacturing. These properties are the surface area, residual carbon impurities and adsorbed volatile species whereas the morphology and particle size distribution are functions of the precipitation process. Available data and experience regarding the thermal and radiation-induced decompositions of plutonium oxalate to oxide are reviewed. The mechanisms of the thermal decompositions are considered with a particular focus on the likely redox chemistry involved. Also, whilst it is well known that the surface area is dependent on calcination temperature, there is a wide variation in the published data and so new correlations have been derived. Better understanding of plutonium (III) and (IV) oxalate decompositions will assist the development of more proliferation resistant actinide co-conversion processes that are needed for advanced reprocessing in future closed nuclear fuel cycles.

  16. Regional differences in oxalate absorption by rat intestine: evidence for excessive absorption by the colon in steatorrhoea.

    PubMed Central

    Saunders, D R; Sillery, J; McDonald, G B

    1975-01-01

    Clinical studies suggest that steatorrhoea can be associated with excessive absorption of dietary oxalate. We examined the influence of bile salts, Ca++, and long-chain fatty acid on the absorption of oxalate and water by rat intestine in vivo. Absorption was measured under steady-state conditions during single-pass infusions. Each intestinal segment served as its own control. In jejunum, 10 mM taurocholate, the principal salt in rat bile, depressed absorption of oxalate and water. Absorption was not depressed further by Ca++ or linoleic acid. In ileum, 10 mM taurocholate did not inhibit absorption. Linoleic acid, 2 mM, depressed absorption of both oxalate and water. In colon 10 mM taurocholate decreased absorption. Net water transport was depressed further when linoleic acid was added to the infusion, but oxalate absorption was enhanced. Ca++ negated these effects of linoleic acid. It is concluded that long-chain fatty acids may enhance the absorption of oxalate from the rat colon. This observation may be relevant to understanding hyperoxaluria in patients with steatorrhoea. PMID:1158192

  17. Effect of Kimchi Fermentation on Oxalate Levels in Silver Beet (Beta vulgaris var. cicla).

    PubMed

    Wadamori, Yukiko; Vanhanen, Leo; Savage, Geoffrey P

    2014-04-23

    Total, soluble and insoluble oxalates were extracted and analyzed by high performance liquid chromatography (HPLC) following the preparation of kimchi using silver beet (Beta vulgaris var. cicla) stems and leaves. As silver beet contains high oxalate concentrations and consumption of high levels can cause the development of kidney stones in some people, the reduction of oxalate during preparation and fermentation of kimchi was investigated. The silver beet stems and leaves were soaked in a 10% brine solution for 11 h and then washed in cold tap water. The total, soluble and insoluble oxalate contents of the silver beet leaves were reduced by soaking in brine, from 4275.81 ± 165.48 mg/100 g to 3709.49 ± 216.51 mg/100 g fresh weight (FW). Fermenting the kimchi for 5 days at 19.3 ± 0.8 °C in 5 L ceramic jars with a water airtight seal resulted in a mean 38.50% reduction in total oxalate content and a mean 22.86% reduction in soluble oxalates. The total calcium content was essentially the same before and after the fermentation of the kimchi (mean 296.1 mg/100 g FW). The study showed that fermentation of kimchi significantly (p < 0.05) reduced the total oxalate concentration in the initial mix from 609.32 ± 15.69 to 374.71 ± 7.94 mg/100 g FW in the final mix which led to a 72.3% reduction in the amount of calcium bound to insoluble oxalate.

  18. Temperature induced denaturation of collagen in acidic solution.

    PubMed

    Mu, Changdao; Li, Defu; Lin, Wei; Ding, Yanwei; Zhang, Guangzhao

    2007-07-01

    The denaturation of collagen solution in acetic acid has been investigated by using ultra-sensitive differential scanning calorimetry (US-DSC), circular dichroism (CD), and laser light scattering (LLS). US-DSC measurements reveal that the collagen exhibits a bimodal transition, i.e., there exists a shoulder transition before the major transition. Such a shoulder transition can recover from a cooling when the collagen is heated to a temperature below 35 degrees C. However, when the heating temperature is above 37 degrees C, both the shoulder and major transitions are irreversible. CD measurements demonstrate the content of triple helix slowly decreases with temperature at a temperature below 35 degrees C, but it drastically decreases at a higher temperature. Our experiments suggest that the shoulder transition and major transition arise from the defibrillation and denaturation of collagen, respectively. LLS measurements show the average hydrodynamic radius R(h), radius of gyration R(g)of the collagen gradually decrease before a sharp decrease at a higher temperature. Meanwhile, the ratio R(g)/R(h) gradually increases at a temperature below approximately 34 degrees C and drastically increases in the range 34-40 degrees C, further indicating the defibrillation of collagen before the denaturation.

  19. Hyaluronic acid solution injection for upper and lower gastrointestinal bleeding after failed conventional endoscopic therapy.

    PubMed

    Lee, Jin Wook; Kim, Hyung Hun

    2014-03-01

    Hyaluronic acid solution injection can be an additional endoscopic modality for controlling bleeding in difficult cases when other techniques have failed. We evaluated 12 cases in which we used hyaluronic acid solution injection for stopping bleeding. Immediately following hyaluronic acid solution injection, bleeding was controlled in 11 out of 12 cases. There was no clinical evidence of renewed bleeding in 11 cases during follow up.Hyaluronic acid solution injection can be a simple and efficient additional method for controlling upper and lower gastrointestinal bleeding after failed endoscopic therapy.

  20. Large-scale production of anhydrous nitric acid and nitric acid solutions of dinitrogen pentoxide

    DOEpatents

    Harrar, Jackson E.; Quong, Roland; Rigdon, Lester P.; McGuire, Raymond R.

    2001-01-01

    A method and apparatus are disclosed for a large scale, electrochemical production of anhydrous nitric acid and N.sub.2 O.sub.5. The method includes oxidizing a solution of N.sub.2 O.sub.4 /aqueous-HNO.sub.3 at the anode, while reducing aqueous HNO.sub.3 at the cathode, in a flow electrolyzer constructed of special materials. N.sub.2 O.sub.4 is produced at the cathode and may be separated and recycled as a feedstock for use in the anolyte. The process is controlled by regulating the electrolysis current until the desired products are obtained. The chemical compositions of the anolyte and catholyte are monitored by measurement of the solution density and the concentrations of N.sub.2 O.sub.4.

  1. Uptake of Hypobromous Acid (HOBr) by Aqueous Sulfuric Acid Solutions: Low-Temperature Solubility and Reaction

    NASA Technical Reports Server (NTRS)

    Iraci, Laura T.; Michelsen, Rebecca R.; Ashbourn, Samatha F. M.; Rammer, Thomas A.; Golden, David M.

    2005-01-01

    Hypobromous acid (HOBr) is a key species linking inorganic bromine to the chlorine and odd hydrogen chemical families. We have measured the solubility of HOBr in 45 - 70 wt% sulfuric acid solutions representative of upper tropospheric and lower stratospheric aerosol composition. Over the temperature range 201 - 252 K, HOBr is quite soluble in sulfuric acid, with an effective Henry's law coefficient, H* = 10(exp 4) - 10(exp 7) mol/L/atm. H* is inversely dependent on temperature, with Delta H = -46.2 kJ/mol and Delta S = -106.2 J/mol/K for 55 - 70 wt% H2SO4 solutions. Our study includes temperatures which overlap both previous measurements of HOBr solubility. For uptake into aqueous 45 wt% H2SO4, the solubility can be described by log H* = 3665/T - 10.63. For 55 - 70 wt% H2SO4, log H* = 2412/T - 5.55. At temperatures colder than approx. 213 K, the solubility of HOBr in 45 wt% H2SO4 is noticeably larger than in 70 wt% H2SO4. The solubility of HOBr is comparable to that of HBr, indicating that upper tropospheric and lower stratospheric aerosols should contain equilibrium concentrations of HOBr which equal or exceed those of HBr. Our measurements indicate chemical reaction of HOBr upon uptake into aqueous sulfuric acid in the presence of other brominated gases followed by evolution of gaseous products including Br2O and Br2, particularly at 70 wt% H2SO4.

  2. Artificial photosynthesis of oxalate and oxalate-based polymer by a photovoltaic reactor

    NASA Astrophysics Data System (ADS)

    Nong, Guangzai; Chen, Shan; Xu, Yuanjin; Huang, Lijie; Zou, Qingsong; Li, Shiqiang; Mo, Haitao; Zhu, Pingchuan; Cen, Weijian; Wang, Shuangfei

    2014-01-01

    A photovoltaic reactor was designed for artificial photosynthesis, based on the reactions involved in high energy hydrogen atoms, which were produced from water electrolysis. Water and CO2, under the conditions studied, were converted to oxalate (H2C2O4) and a polymer. This was the first time that the oxalates and oxalate-based polymer were produced from the artificial photosynthesis process.

  3. Artificial photosynthesis of oxalate and oxalate-based polymer by a photovoltaic reactor.

    PubMed

    Nong, Guangzai; Chen, Shan; Xu, Yuanjin; Huang, Lijie; Zou, Qingsong; Li, Shiqiang; Mo, Haitao; Zhu, Pingchuan; Cen, Weijian; Wang, Shuangfei

    2014-01-06

    A photovoltaic reactor was designed for artificial photosynthesis, based on the reactions involved in high energy hydrogen atoms, which were produced from water electrolysis. Water and CO2, under the conditions studied, were converted to oxalate (H2C2O4) and a polymer. This was the first time that the oxalates and oxalate-based polymer were produced from the artificial photosynthesis process.

  4. Artificial photosynthesis of oxalate and oxalate-based polymer by a photovoltaic reactor

    PubMed Central

    Nong, Guangzai; Chen, Shan; Xu, Yuanjin; Huang, Lijie; Zou, Qingsong; Li, Shiqiang; Mo, Haitao; Zhu, Pingchuan; Cen, Weijian; Wang, Shuangfei

    2014-01-01

    A photovoltaic reactor was designed for artificial photosynthesis, based on the reactions involved in high energy hydrogen atoms, which were produced from water electrolysis. Water and CO2, under the conditions studied, were converted to oxalate (H2C2O4) and a polymer. This was the first time that the oxalates and oxalate-based polymer were produced from the artificial photosynthesis process. PMID:24389750

  5. Oxalate oxidases and differentiating surface structure in wheat: germins.

    PubMed Central

    Lane, B G

    2000-01-01

    Oxalate oxidases (OXOs) have been found to be concentrated in the surface tissues of wheat embryos and grains: germin is concentrated in root and leaf sheaths that surround germinated embryos; pseudogermin (OXO-psi) is concentrated in the epidermis and bracts that 'encircle' mature grains. Most strikingly, the epidermal accumulation of OXO-psi was found to presage the transition of a delicate 'skin', similar to the fragile epidermis of human skin, into the tough shell (the miller's 'beeswing') that is typical of mature wheat grains. A narrow range of oxalate concentration (1--2 mM) in the hydrated tissues of major crop cereals (barley, maize, oat, rice, rye and wheat) contrasted with wide variations in their OXO expression, e.g. cold-tolerant and cold-sensitive varieties of maize have similar oxalate contents but the former was found to contain approx. 20-fold more germin than did the latter. Well-known OXOs in sorghum, a minor cereal, and beet, a dicotyledon, were found to have little antigenic relatedness to the germins, but the beet enzyme did share some of the unique stability properties that are peculiar to the germin-like OXOs that are found only in the major crop cereals. Their concentration in surface structures of domesticated wheat suggests a biochemical role for germin-like OXOs: programmed cell death in surface tissues might be a constitutive as well as an adaptive form of differentiation that helps to produce refractory barriers against tissue invasion by predators. Incidental to the principal investigation, and using an OXO assay (oxalate-dependent release of CO(2)) that did not rely on detecting H(2)O(2), which is often fully degraded in cell extracts, it was found that OXO activity in soluble extracts of wheat was manifested only in standard solution assays if the extract was pretreated in a variety of ways, which included preincubation with pepsin or highly substituted glucuronogalactoarabinoxylans (cell-wall polysaccharides). PMID:10861243

  6. Computational study on nitronium and nitrosonium oxalate: potential oxidizers for solid rocket propulsion?

    PubMed

    Gökçinar, Elif; Klapötke, Thomas M; Kramer, Michael P

    2010-08-26

    The enthalpies of formation for solid ionic nitrosonium oxalate, [NO](2)[O(2)C-CO(2)], nitronium oxalate, [NO(2)](2)[O(2)C-CO(2)], as well as covalent bis(nitroso)oxalic acid, ON-O(2)C-CO(2)-NO, and oxalic acid dinitrate ester, O(2)N-O(2)C-CO(2)-NO(2), were calculated using the complete basis set (CBS-4M) method of Petersson and coworkers to obtain very accurate energies. For the nitrosonium species, the ionic form ([NO](2)[O(2)C-CO(2)]) was identified as the more stable isomer, whereas for the nitrosonium compound, the covalently bound dinitrate ester (O(2)N-O(2)C-CO(2)-NO(2)) was found to be more stable. The combustion parameters with respect to possible use as ingredients in solid rocket motors for both stable species were calculated using the EXPLO5 and the ICT code. The performance of an aluminized formulation with covalently bound dinitrate ester (O(2)N-O(2)C-CO(2)-NO(2)) was shown to be comparable to that of ammonium perchlorate/aluminum. This makes oxalic acid dinitrate ester a potentially interesting perchlorate-free and environmentally benign oxidizer for solid rocket propulsion.

  7. Extraction equilibrium of indium(III) from nitric acid solutions by di(2-ethylhexyl)phosphoric acid dissolved in kerosene.

    PubMed

    Tsai, Hung-Sheng; Tsai, Teh-Hua

    2012-01-04

    The extraction equilibrium of indium(III) from a nitric acid solution using di(2-ethylhexyl) phosphoric acid (D2EHPA) as an acidic extractant of organophosphorus compounds dissolved in kerosene was studied. By graphical and numerical analysis, the compositions of indium-D2EHPA complexes in organic phase and stoichiometry of the extraction reaction were examined. Nitric acid solutions with various indium concentrations at 25 °C were used to obtain the equilibrium constant of InR₃ in the organic phase. The experimental results showed that the extraction distribution ratios of indium(III) between the organic phase and the aqueous solution increased when either the pH value of the aqueous solution and/or the concentration of the organic phase extractant increased. Finally, the recovery efficiency of indium(III) in nitric acid was measured.

  8. Oxalate adsorption at a plagioclase (An47) surface and models for ligand-promoted dissolution

    USGS Publications Warehouse

    Stillings, L.L.; Drever, J.I.; Poulson, S.R.

    1998-01-01

    Previous work on adsorption of oxalate at aluminosilicate surfaces suggests that maximum adsorption occurs through a bidentate attachment of the organic ligand, at near-neutral pH. Rates of ligand-promoted dissolution are expected to be greatest at this pH as well. We tested this model by measuring oxalate adsorption on the surface of andesine (An47), in solutions of pH 3- 5 and total oxalate concentrations of 0-8 mM. Contrary to expectation, the greatest adsorption density of 24 ??mol m-2 total oxalate was observed at pH 3 and 8 mM total oxalate. Adsorption is dependent upon the activities of both oxalate (C2O42-) and bioxalate (HC2O4-) in solution and can be modeled with either a two-term Langmuir or a two-term Freundlich isotherm. A Freundlich adsorption model provided the best fit to rate data because it was not constrained to a finite number of adsorption sites, as was the Langmuir model. The two-term ligand adsorption model was incorporated into a rate model: R(tot) = k(H-)[H(ads)/+](L) + k(HOx-)[HOx(ads)/-] + k(Ox2- )[Ox2(ads)/-] where R(tot) is the net dissolution rate of the feldspar, [i(ads)] is the concentration of species i adsorbed to the surface, and k(i) is the rate constant for release of the surface complex. The model was fit to data for oxalate-promoted dissolution of andesine, resulting in estimates for the rate constants of k(HOx-) = 1.16 x 10-12, k(Ox2-) = 1.05 x 10-12, and k(H-) = 9.61 x 10-13 mol of feldspar (??mol of i) (??mol of i)-1 s-1.Previous work on adsorption of oxalate at aluminosilicate surfaces suggests that maximum adsorption occurs through a bidentate attachment of the organic ligand, at near-neutral pH. Rates of ligand-promoted dissolution are expected to be greatest at this pH as well. We tested this model by measuring oxalate adsorption on the surface of andesine (An47), in solutions of pH 3-5 and total oxalate concentrations of 0-8 mM. Contrary to expectation, the greatest adsorption density of 24 ??mol m-2 total oxalate was

  9. Effects of long chain fatty acids on solute absorption: perfusion studies in the human jejunum.

    PubMed Central

    Ammon, H V; Thomas, P J; Phillips, S F

    1977-01-01

    Perfusion studies were performed in healthy volunteers to test the hypothesis that net fluid secretion induced by fatty acids is accompanied by parallel reduction in solute transport. Ricinoleic acid provoked a marked net secretion of fluid and concomitantly inhibited the absorption of all solutes tested; these included glucose, xylose, L-leucine, L-lysine, Folic acid, and 2-mono-olein. Oleic acid also reduced net fluid and solute transport, but was less potent in reducing solute absorption than was ricinoleic acid. When fluid secretion was induced osmotically with mannitol, glucose and xylose absorption was not affected. The mechanism for this generalised effect of fatty acids on solute absorption is uncertain, possibly nonspecific, and might be related to mucosal damage and altered mucosal permeability induced by these agents. PMID:590838

  10. Isothermal heat measurements of TBP-nitric acid solutions

    SciTech Connect

    Smith, J.R.; Cavin, W.S.

    1994-12-16

    Net heats of reaction were measured in an isothermal calorimeter for both single phase (organic) and two phase (organic and aqueous) TBP/HNO{sub 3} reacting solutions at temperatures above 100 C. The oxidation rate constant was determined to be 5.4E-4 min{sup {minus}1} at 110 C for an open ``vented`` system as compared to 1.33 E-3 min{sup {minus}1} in the closed system. The heat released per unit material oxidized was also reduced. The oxidation in both phases was found to be first order in nitric acid and pseudo-zero order in butylnitrate and water. The hydrolysis (esterification) rate constant determined by Nichols` (1.33E-3 min{sup {minus}1}) fit the experimental data from this work well. Forced evaporation of the volatile components by the product gases from oxidation resulted in a cooling mechanism which more than balanced the heat from the oxidation reaction in the two-phased systems. Rate expressions were derived and rate constants determined for both the single and two phase systems. An approximating mathematical model was developed to fit the experimental data and to extrapolate beyond the experimental conditions. This model shows that one foot of ``reacting`` 14.3M HNO{sub 3} aqueous phase solution at 121 C will transport sufficient water to the organic phase to replace evaporative losses, maintaining endothermicity, for organic layers up to 12.2 + 6.0 feet deep. If the pressure in a reacting system is allowed to increase due to insufficient venting the temperature of the organic phase would increase in temperature to reach a new equilibrium. The rate of oxidation would increase not only due to the increase in temperature but also from the increased concentration of dissolved HNO{sub 3} reduction products. Another important factor is that the cooling system described in this work becomes less effective as the total pressure increases. These factors probably contributed to the explosion at Tomsk.

  11. Characterization of calcium oxalate biominerals in some (non-Cactaceae) succulent plant species.

    PubMed

    Monje, Paula V; Baran, Enrique J

    2010-01-01

    The water-accumulating leaves of crassulacean acid metabolism plants belonging to five different families were investigated for the presence of biominerals by infrared spectroscopic and microscopic analyses. Spectroscopic results revealed that the mineral present in succulent species of Agavaceae, Aizoaceae, and Asphodelaceae was calcium oxalate monohydrate (whewellite, CaC2O4 x H2O). Crystals were predominantly found as raphides or solitary crystals of various morphologies. However, representative Crassulaceae members and a succulent species of Asteraceae did not show the presence of biominerals. Overall, these results suggest no correlation between calcium oxalate generation and crassulacean acid metabolism in succulent plants.

  12. Uptake of isoprene, methacrylic acid and methyl methacrylate into aqueous solutions of sulfuric acid and hydrogen peroxide.

    PubMed

    Liu, Ze; Ge, Maofa; Wang, Weigang

    2012-01-01

    Multiphase acid-catalyzed oxidation by hydrogen peroxide has been suggested to be a potential route to secondary organic aerosol formation from isoprene and its gas-phase oxidation products, but the lack of kinetics data significantly limited the evaluation of this process in the atmosphere. Here we report the first measurement of the uptake of isoprene, methacrylic acid and methyl methacrylate into aqueous solutions of sulfuric acid and hydrogen peroxide. Isoprene cannot readily partition into the solution because of its high volatility and low solubility, which hinders its further liquid-phase oxidation. Both methacrylic acid and methyl methacrylate can enter the solutions and be oxidized by hydrogen peroxide, and steady-state uptake was observed with the acidity of solution above 30 wt.% and 70 wt.%, respectively. The steady-state uptake coefficient of methacrylic acid is much larger than that of methyl methacrylate for a solution with same acidity. These observations can be explained by the different reactivity of these two compounds caused by the different electron-withdrawing conjugation between carboxyl and ester groups. The atmospheric lifetimes were estimated based on the calculated steady-state uptake coefficients. These results demonstrate that the multiphase acid-catalyzed oxidation of methacrylic acid plays a role in secondary organic aerosol formation, but for isoprene and methyl methacrylate, this process is not important in the troposphere.

  13. Chaga mushroom-induced oxalate nephropathy.

    PubMed

    Kikuchi, Yuko; Seta, Koichi; Ogawa, Yayoi; Takayama, Tatsuya; Nagata, Masao; Taguchi, Takashi; Yahata, Kensei

    2014-06-01

    Chaga mushrooms have been used in folk and botanical medicine as a remedy for cancer, gastritis, ulcers, and tuberculosis of the bones. A 72-year-old Japanese female had been diagnosed with liver cancer 1 year prior to presenting at our department. She underwent hepatectomy of the left lobe 3 months later. Chaga mushroom powder (4 - 5 teaspoons per day) had been ingested for the past 6 months for liver cancer. Renal function decreased and hemodialysis was initiated. Renal biopsy specimens showed diffuse tubular atrophy and interstitial fibrosis. Oxalate crystals were detected in the tubular lumina and urinary sediment and oxalate nephropathy was diagnosed. Chaga mushrooms contain extremely high oxalate concentrations. This is the first report of a case of oxalate nephropathy associated with ingestion of Chaga mushrooms.

  14. Effect of citric acid on the acidification of artificial pepsin solution for metacercariae isolation from fish.

    PubMed

    Kim, Min-Ki; Pyo, Kyoung-Ho; Hwang, Young-Sang; Chun, Hyang Sook; Park, Ki Hwan; Ko, Seong-Hee; Chai, Jong-Yil; Shin, Eun-Hee

    2013-11-15

    Artificial digestive solution based on pepsin is essential for collecting metacercariae from fish. To promote the enzymatic reactivity of pepsin, the pH of the solution has to be adjusted to pH 1.0-2.0. Hydrochloride (HCl) is usually used for this purpose, but the use of HCl raises safety concerns. The aim of this work was to address the usefulness of citric acid as an alternative for HCl for the acidification of pepsin solution, and to examine its potential to damage metacercariae during in vitro digestion as compared with HCl. Changes in pH after adding 1-9% of citric acid (m/v) to pepsin solution were compared to a 1% HCl (v/v) addition. Digestion of fish muscle was evaluated by measuring released protein concentrations by spectrophotometry. In addition, survival rates of metacercariae in pepsin solution were determined at different citric acid concentrations and were compared that of with 1% HCl. The present study shows that addition of citric acid reduced the pH of pepsin solutions to the required level. Addition of more than 5% of citric acid resulted in the effective digestion of fish muscle over 3h in vitro, and 5% citric acid was less lethal to metacercariae than 1% HCl in pepsin solution. Pepsin solution containing 5% citric acid had digestive capacity superior to pepsin solution containing 1% HCl after 3h incubation with released protein conce