Study of CO2 adsorption capacity of mesoporous carbon and activated carbon modified by triethylenetetramine (TETA)

NASA Astrophysics Data System (ADS)

Sulistianti, I.; Krisnandi, Y. K.; Moenandar, I.

2017-04-01

Mesoporous carbon was synthesized by soft template method using phloroglucinol and formaldehyde as a carbon source; and Pluronic F-127 as a mesoporous template. The synthesized mesoporous carbon and commercial activated carbon were modified with triethylenetetramine (TETA) to increase CO2 adsorption capacity. Based on FTIR characterization, the synthesized mesoporous carbon and the activated carbon without modification process has similarity pattern. After the modification, both of them showed absorption peaks in the area around 1580 to 1650 cm-1 which is known as N-H bending vibration and absorption peaks in the area around 3150 to 3380 cm-1 which is known as N-H stretching vibration. The XRD results showed two peaks at 2θ = 24.21° and 2θ = 43.85°, according to JCPDS index No. 75-1621 those peak are the typical peaks for hexagonal graphite carbon. In BET analysis, the synthesized mesoporous carbon and activated carbon modified TETA have surface area, pore volume and pore diameter lower than without modification process. In carbon dioxide adsorption testing, the synthesized mesoporous carbon showed better performance than the commercial activated carbon for CO2 adsorption both without modification and by modification. The synthesized mesoporous carbon obtained CO2 adsorption of 9.916 mmol/g and the activated carbon of 3.84 mmol/g for on 3.5 hours of adsorption. It is three times better than activated carbon for adsorption of carbon dioxide. The modified mesoporous carbon has the best performance for adsorption of gas CO2 if compared by unmodified.

Removal of petroleum hydrocarbons from contaminated groundwater by the combined technique of adsorption onto perlite followed by the O3/H2O2 process.

PubMed

Moussavi, Gholamreza; Bagheri, Amir

2012-09-01

Groundwater contaminated with petroleum hydrocarbons was treated using a combined system of adsorption onto powdered expanded perlite (PEP) followed by the O3/H2O2 process. The pretreatment investigations indicated a high capacity for PEP to remove petroleum hydrocarbons from the contaminated water. An experimental total petroleum hydrocarbon (TPH) adsorption capacity of 275 mg/g PEP was obtained at the natural pH of water. The experimental data fit best with the Freundlich isotherm model and pseudo-second-order adsorption model. The second phase of the experiment evaluated the performance of the O3/H2O2 process in the removal of residual TPH from pretreated water and compared the results with that of raw water. The O3/H202 process attained a maximum TPH removal rate for the pretreated water after 70 min, when 93% of the residual TPH in the effluent of the adsorption system was removed. Overall, the combination of adsorption onto PEP for 100 min and the subsequent treatment with the O3/H2O2 process for 70min eliminated over 99% of the TPH of highly petroleum-contaminated groundwater, with initial values of 162 mg/L. Therefore, we can conclude that the developed treatment system is an appropriate method of remediation for petroleum-contaminated waters.

2,4-D adsorption to biochars: effect of preparation conditions on equilibrium adsorption capacity and comparison with commercial activated carbon literature data.

PubMed

Kearns, J P; Wellborn, L S; Summers, R S; Knappe, D R U

2014-10-01

Batch isotherm experiments were conducted with chars to study adsorption of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). Chars generated from corncobs, bamboo and wood chips in a laboratory pyrolyzer at 400-700 °C were compared with traditional kiln charcoals collected from villages in S/SE Asia and with activated carbons (ACs). 2,4-D uptake by laboratory chars obtained from bamboo and wood chips after 14 h of pyrolysis at 700 °C, from wood chips after 96 h of pyrolysis at 600 °C, and one of the field-collected chars (basudha) was comparable to ACs. H:C and O:C ratios declined with pyrolysis temperature and duration while surface area increased to >500 m(2)/g. Increasing pyrolysis intensity by increasing temperature and/or duration of heating was found to positively influence adsorption capacity yield (mg(2,4-D/g(feedstock))) over the range of conditions studied. Economic analysis showed that high temperature chars can be a cost-effective alternative to ACs for water treatment applications. Copyright © 2014 Elsevier Ltd. All rights reserved.

Adsorption of 2,4-dichlorophenoxyacetic acid by mesoporous activated carbon prepared from H3PO4-activated langsat empty fruit bunch.

PubMed

Njoku, V O; Islam, Md Azharul; Asif, M; Hameed, B H

2015-05-01

The removal of toxic herbicide from wastewater is challenging due to the availability of suitable adsorbents. The Langsat empty fruit bunch is an agricultural waste and was used in this study as a cheap precursor to produce activated carbon for the adsorption of herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) at different initial concentrations ranging from 50 to 400 mg/L. The produced Langsat empty fruit bunch activated carbon (LEFBAC) was mesoporous and had high surface area of 1065.65 m(2)/g with different active functional groups. The effect of shaking time, temperature and pH on 2,4-D removal were investigated using the batch technique. The adsorption capacity of 2,4-D by LEFBAC was decreased with increase in pH of solution whereas adsorption capacity increased with temperature. The adsorption data was well described by Langmuir isotherm followed by removal capacity of 261.2 mg/g at 30 °C. The results from this work showed that LEFBAC can be used as outstanding material for anionic herbicide uptake from wastewater. Copyright © 2015 Elsevier Ltd. All rights reserved.

Simultaneous adsorption of CO2 and H2O under Mars-like conditions and application to the evolution of the Martian climate

NASA Technical Reports Server (NTRS)

Zent, Aaron P.; Quinn, Richard

1994-01-01

The Martian regolith is the most substantial volatile reservoir on the planet; it holds CO2 as adsorbate, and can exchange that CO2 with the atmosphere-cap system over timescales of 10(exp 5) to 10(exp 6) years. The climatic response to insolation changes caused by obliquity and eccentricity variations depends in part on the total reservoir of adsorbed CO2. Previous estimates of the adsorbate inventory have been made by measuring the adsorptive behavior of one or more Mars-analyog materials, and deriving an empirical equation that described that adsorption as a function of the partial pressure of CO2 and the temperature of the regolith. The current CO2 inventory is that which satisfies adsorptive equilibrium, observed atmospheric pressure, and no permanent CO2 caps. There is laboratory evidence that H2O poisons the CO2 adsorptive capacity of most materials. No consideration of CO2 - H2O co-adsorption was given in previous estimates of the Martian CO2 inventory, although H2O is present in the vapor phase, and so as adsorbate, throughout the regolith.

Assessing changes in the physico-chemical properties and fluoride adsorption capacity of activated alumina under varied conditions

USGS Publications Warehouse

Craig, Laura; Stillings, Lisa; Decker, David L.

2017-01-01

Adsorption using activated alumina is a simple method for removing fluoride from drinking water, but to be cost effective the adsorption capacity must be high and effective long-term. The intent of this study was to assess changes in its adsorption capacity under varied conditions. This was determined by evaluating the physico-chemical properties, surface charge, and fluoride (F−) adsorption capacity and rate of activated alumina under conditions such as hydration period, particle size, and slow vs. fast titrations. X-ray diffraction and scanning electron microscopy analyses show that the mineralogy of activated alumina transformed to boehmite, then bayerite with hydration period and a corresponding reduction in adsorption capacity was expected; while surface area analyses show no notable changes with hydration period or particle size. The pH dependent surface charge was three times higher using slow potentiometric titrations as compared to fast titrations (due largely to diffusion into pore space), with the surface acidity generally unaffected by hydration period. Results from batch adsorption experiments similarly show no change in fluoride adsorption capacity with hydration period. There was also no notable difference in fluoride adsorption capacity between the particle size ranges of 0.5–1.0 mm and 0.125–0.250 mm, or with hydration period. However, adsorption rate increased dramatically with the finer particle sizes: at an initial F− concentration of 0.53 mmol L−1 (10 mg L−1), 90% was adsorbed in the 0.125–0.250 mm range after 1 h, while the 0.5–1.0 mm range required 24 h to achieve 90% adsorption. Also, the pseudo-second-order adsorption rate constants for the finer vs. larger particle sizes were 3.7 and 0.5 g per mmol F− per min respectively (24 h); and the initial intraparticle diffusion rate of the former was 2.6 times faster than the latter. The results show that adsorption capacity of activated alumina remains consistent and

CO2 Adsorption in Low-Rank Coals: Progress Toward Assessing the National Capacity to Store CO2 in the Subsurface

NASA Astrophysics Data System (ADS)

Stanton, R. W.; Burruss, R. C.; Flores, R. M.; Warwick, P. D.

2001-05-01

Subsurface environments for geologic storage of CO2 from combustion of fossil fuel include saline formations, depleted oil and gas reservoirs, and unmineable coalbeds. Of these environments, storage in petroleum reservoirs and coal beds offers a potential economic benefit of enhanced recovery of energy resources. Meaningful assessment of the volume and geographic distribution of storage sites requires quantitative estimates of geologic factors that control storage capacity. The factors that control the storage capacity of unmineable coalbeds are poorly understood. In preparation for a USGS assessment of CO2 storage capacity we have begun new measurements of CO2 and CH4 adsorption isotherms of low-rank coal samples from 4 basins. Initial results for 13 samples of low-rank coal beds from the Powder River Basin (9 subbituminous coals), Greater Green River Basin (1 subbituminous coal), Williston Basin (2 lignites) and the Gulf Coast (1 lignite) indicate that their adsorption capacity is up to 10 times higher than it is for CH4. These values contrast with published measurements of the CO2 adsorption capacity of bituminous coals from the Fruitland Formation, San Juan basin, and Gates Formation, British Columbia, that indicate about twice as much carbon dioxide as methane can be adsorbed on coals. Because CH4 adsorption isotherms are commonly measured on coals, CO2 adsorption capacity can be estimated if thecorrect relationship between the gases is known. However, use a factor to predict CO2 adsorption that is twice that of CH4 adsorption, which is common in the published literature, grossly underestimates the storage capacity of widely distributed, thick low-rank coal beds. Complete petrographic and chemical characterization of these low-rank coal samples is in progress. Significant variations in adsorption measurements among samples are depicted depending on the reporting basis used. Properties were measured on an "as received" (moist) basis but can be converted to a

Amine-tethered solid adsorbents coupling high adsorption capacity and regenerability for CO2 capture from ambient air.

PubMed

Choi, Sunho; Gray, McMahan L; Jones, Christopher W

2011-05-23

Silica supported poly(ethyleneimine) (PEI) materials are prepared via impregnation and demonstrated to be promising adsorbents for CO(2) capture from ultra-dilute gas streams such as ambient air. A prototypical class 1 adsorbent, containing 45 wt% PEI (PEI/silica), and two new modified PEI-based aminosilica adsorbents, derived from PEI modified with 3-aminopropyltrimethoxysilane (A-PEI/silica) or tetraethyl orthotitanate (T-PEI/silica), are prepared and characterized by using thermogravimetric analysis and FTIR spectroscopy. The modifiers are shown to enhance the thermal stability of the polymer-oxide composites, leading to higher PEI decomposition temperatures. The modified adsorbents present extremely high CO(2) adsorption capacities under conditions simulating ambient air (400 ppm CO(2) in inert gas), exceeding 2 mol(CO (2)) kg(sorbent)(-1), as well as enhanced adsorption kinetics compared to conventional class 1 sorbents. The new adsorbents show excellent stability in cyclic adsorption-desorption operations, even under dry conditions in which aminosilica adsorbents are known to lose capacity due to urea formation. Thus, the adsorbents of this type can be considered promising materials for the direct capture of CO(2) from ultra-dilute gas streams such as ambient air. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

DFT simulation on H2 adsorption over Ni-decorated defective h-BN nanosheets

NASA Astrophysics Data System (ADS)

Zhou, Xuan; Chu, Wei; Zhou, Yanan; Sun, Wenjing; Xue, Ying

2018-05-01

Nickel doped defective h-BN nanosheets and their potential application on hydrogen storage were explored by density functional theory (DFT) calculation. Three types of defective h-BN (SW defect, VB and VN substrates) were modeled. In comparison with the SW defect, the B or N vacancy can improve the interaction between Ni atom and h-BN nanosheet strikingly. Furthermore, the Ni-doped SW defect sheet shows chemisorption on H2 molecules, and the Hsbnd H bond is partially dissociated. While on the VB sheet, Ni adatom interacts with H2 in the range of physisorption. However, the Ni-functionalized VN sheet exhibits a desirable adsorption on H2, and the corresponding energy varies from -0.40 to -0.51 eV, which is favorable for H2 adsorption and release at ambient conditions. As a result, the VN substrate is expected to a desirable support for H2 storage. Our work provides an insight into H2 storage on Ni-functionalized defective h-BN monolayer.

High-Capacity and Photoregenerable Composite Material for Efficient Adsorption and Degradation of Phenanthrene in Water.

PubMed

Liu, Wen; Cai, Zhengqing; Zhao, Xiao; Wang, Ting; Li, Fan; Zhao, Dongye

2016-10-18

We report a novel composite material, referred to as activated charcoal supported titanate nanotubes (TNTs@AC), for highly efficient adsorption and photodegradation of a representative polycyclic aromatic hydrocarbon (PAH), phenanthrene. TNTs@AC was prepared through a one-step hydrothermal method, and is composed of an activated charcoal core and a shell of carbon-coated titanate nanotubes. TNTs@AC offered a maximum Langmuir adsorption capacity of 12.1 mg/g for phenanthrene (a model PAH), which is ∼11 times higher than the parent activated charcoal. Phenanthrene was rapidly concentrated onto TNTs@AC, and subsequently completely photodegraded under UV light within 2 h. The photoregenerated TNTs@AC can then be reused for another adsorption-photodegradation cycle without significant capacity or activity loss. TNTs@AC performed well over a wide range of pH, ionic strength, and dissolved organic matter. Mechanistically, the enhanced adsorption capacity is attributed to the formation of carbon-coated ink-bottle pores of the titanate nanotubes, which are conducive to capillary condensation; in addition, the modified microcarbon facilitates transfer of excited electrons, thereby inhibiting recombination of the electron-hole pairs, resulting in high photocatalytic activity. The combined high adsorption capacity, photocatalytic activity, and regenerability/reusability merit TNTs@AC a very attractive material for concentrating and degrading a host of micropollutants in the environment.

Reactive adsorption of SO2 on activated carbons with deposited iron nanoparticles.

PubMed

Arcibar-Orozco, Javier A; Rangel-Mendez, J Rene; Bandosz, Teresa J

2013-02-15

The effect of iron particle size anchored on the surface of commercial activated carbon on the removal of SO(2) from a gas phase was studied. Nanosize iron particles were deposited using forced hydrolysis of FeCl(3) with or without H(3)PO(4) as a capping agent. Dynamic adsorption experiments were carried out on either dry or pre-humidified materials and the adsorption capacities were calculated. The surface of the initial and exhausted materials was extensively characterized by microscopic, porosity, thermogravimetric and surface chemistry. The results indicate that the SO(2) adsorption capacity increased two and half times after the prehumidification process owing to the formation of H(2)SO(4) in the porous system. Iron species enhance the SO(2) adsorption capacity only when very small nanoparticles are deposited on the pore walls as a thin layer. Large iron nanoparticles block the ultramicropores decreasing the accessibility of the active sites and consuming oxygen that rest adsorption centers for SO(2) molecules. Iron nanoparticles of about 3-4 nm provide highly dispersed adsorption sites for SO(2) molecules and thus increase the adsorption capacity of about 80%. Fe(2)(SO(4))(3) was detected on the surface of exhausted samples. Copyright © 2012 Elsevier B.V. All rights reserved.

Investigation of copper (Cu2+) adsorption performances and gamma radiation dose effect of polymeric hydrogel

NASA Astrophysics Data System (ADS)

Hassan, Safia; Yasin, Tariq; Imran, Zahid; Batool, Syeda Sitwat

2018-02-01

In present study, series of gamma irradiated poly(acrylic acid)/Penytriethoxytrisilane (PTES) based hydrogels were synthesized. The hydrogels were used for the adsorption of Cu2+ from the aqueous solution. Batch adsorption experiments were performed by varying contact time (0-10 hours), pH value (2-6), hydrogels weight (15-155 mg) and initial Cu2+ concentration (0.003-90 mg/L). The results indicated that lowering the gamma irradiation dose (30-15 kGy) and PTES amount (1.65-0.83 μmol) into hydrogel polymeric networks, improved the initial rate of adsorption and final adsorption capacity of hydrogel for Cu2+. AA40/15 had 143.4mg/g Cu2+ adsorption capacity higher than AA80/30 which is 106.0mg/g. Hydrogels exhibited maximum o adsorption capacity for Cu2+ within a wide pH range. All adsorption data was described by the pseudo—first order and second order kinetic model equations and isotherm data by Langmuir model. FTIR spectra analysis before and after adsorption of Cu2+ on the AA hydrogels gave detail analysis of adsorption mechanism. The behavior of adsorption expressed that the enhanced adsorption capacity was due to the porous structure and e presence of functional groups onto surface of adsorbate. It is expected this polymeric hydrogel has potential to work as alternative biomedical sorbents and environmental use as pH altered.

Micropore Formation of [Zn2(Oxac) (Taz)2]·(H2O)2.5 via CO2 Adsorption.

PubMed

Zubir, Moondra; Hamasaki, Atom; Iiyama, Taku; Ohta, Akira; Ohki, Hiroshi; Ozeki, Sumio

2017-01-24

As-synthesized [Zn 2 (Oxac) (Taz) 2 ]·(H 2 O) 2.5 , referred to as ZOTW 2.5 , was prepared from aqueous methanol solutions of Zn 5 (CO 3 ) 2 (OH) 6 and two kinds of ligands of 1,2,4-triazole (Taz) and oxalic acid (Oxac) at 453 K for 12 h. The crystal structure was determined by the Rietveld method. As-synthesized ZOTW 2.5 was pretreated at 383 K and 1 mPa for t pt h, ZOTW x (t pt h). ZOTW x (≥3h) showed a type I adsorption isotherm for N 2 at 77 K having a saturation amount (V s ) of 180 mg/g, but that pretreated shortly showed only 1/10 in V s . CO 2 was adsorbed at 303 K in sigmoid on nonporous ZOTW x (≤2h) and in Langmuir-type on ZOTW x (≥3h) to reach the adsorption amount of 120 mg/g at 700 Torr. N 2 adsorption on ZOTW x (≤2h)deCO 2 , degassed after CO 2 adsorption on ZOTW x (≤2h), was promoted 5-fold from 180 mg/g on ZOTW x (t pt h) and ZOTW x (≥3h)deCO 2 up to ca. 1000 mg/g. The interaction of CO 2 and H 2 O molecules in micropores may lead to a new route for micropore formation.

Molecular simulation study of the competitive adsorption of H2O and CO2 in zeolite 13X.

PubMed

Joos, Lennart; Swisher, Joseph A; Smit, Berend

2013-12-23

The presence of H2O in postcombustion gas streams is an important technical issue for deploying CO2-selective adsorbents. Because of its permanent dipole, H2O can interact strongly with materials where the selectivity for CO2 is a consequence of its quadrupole interacting with charges in the material. We performed molecular simulations to model the adsorption of pure H2O and CO2 as well as H2O/CO2 mixtures in 13X, a popular zeolite for CO2 capture processes that is commercially available. The simulations show that H2O reduces the capacity of these materials for adsorbing CO2 by an order of magnitude and that at the partial pressures of H2O relevant for postcombustion capture, 13X will be essentially saturated with H2O .

H2O Adsorption Kinetics on Smectites

NASA Technical Reports Server (NTRS)

Zent, Aaron P.; Quinn, Richard C.; Howard, Jeanie; DeVincenzi, Donald L. (Technical Monitor)

2000-01-01

The adsorptive equilibration of H2O a with montomorillonite, a smectite clay has been measured. At low temperatures and pressures, equilibration can require many hours, effectively preventing smectites at the martian surface from responding rapidly to diurnal pressure and temperature variations.

A First Principles Study of H2 Adsorption on LaNiO3(001) Surfaces

PubMed Central

Pan, Changchang; Chen, Yuhong; Wu, Na; Zhang, Meiling; Yuan, Lihua; Zhang, Cairong

2017-01-01

The adsorption of H2 on LaNiO3 was investigated using density functional theory (DFT) calculations. The adsorption sites, adsorption energy, and electronic structure of LaNiO3(001)/H2 systems were calculated and indicated through the calculated surface energy that the (001) surface was the most stable surface. By looking at optimized structure, adsorption energy and dissociation energy, we found that there were three types of adsorption on the surface. First, H2 molecules completely dissociate and then tend to bind with the O atoms, forming two –OH bonds. Second, H2 molecules partially dissociate with the H atoms bonding to the same O atom to form one H2O molecule. These two types are chemical adsorption modes; however, the physical adsorption of H2 molecules can also occur. When analyzing the electron structure of the H2O molecule formed by the partial dissociation of the H2 molecule and the surface O atom, we found that the interaction between H2O and the (001) surface was weaker, thus, H2O was easier to separate from the surface to create an O vacancy. On the (001) surface, a supercell was constructed to accurately study the most stable adsorption site. The results from analyses of the charge population; electron localization function; and density of the states indicated that the dissociated H and O atoms form a typical covalent bond and that the interaction between the H2 molecule and surface is mainly due to the overlap-hybridization among the H 1s, O 2s, and O 2p states. Therefore, the conductivity of LaNiO3(001)/H2 is stronger after adsorption and furthermore, the conductivity of the LaNiO3 surface is better than that of the LaFeO3 surface. PMID:28772396

Adsorption Device Based on a Langatate Crystal Microbalance for High Temperature High Pressure Gas Adsorption in Zeolite H-ZSM-5.

PubMed

Ding, Wenjin; Baracchini, Giulia; Klumpp, Michael; Schwieger, Wilhelm; Dittmeyer, Roland

2016-08-25

We present a high-temperature and high-pressure gas adsorption measurement device based on a high-frequency oscillating microbalance (5 MHz langatate crystal microbalance, LCM) and its use for gas adsorption measurements in zeolite H-ZSM-5. Prior to the adsorption measurements, zeolite H-ZSM-5 crystals were synthesized on the gold electrode in the center of the LCM, without covering the connection points of the gold electrodes to the oscillator, by the steam-assisted crystallization (SAC) method, so that the zeolite crystals remain attached to the oscillating microbalance while keeping good electroconductivity of the LCM during the adsorption measurements. Compared to a conventional quartz crystal microbalance (QCM) which is limited to temperatures below 80 °C, the LCM can realize the adsorption measurements in principle at temperatures as high as 200-300 °C (i.e., at or close to the reaction temperature of the target application of one-stage DME synthesis from the synthesis gas), owing to the absence of crystalline-phase transitions up to its melting point (1,470 °C). The system was applied to investigate the adsorption of CO2, H2O, methanol and dimethyl ether (DME), each in the gas phase, on zeolite H-ZSM-5 in the temperature and pressure range of 50-150 °C and 0-18 bar, respectively. The results showed that the adsorption isotherms of these gases in H-ZSM-5 can be well fitted by Langmuir-type adsorption isotherms. Furthermore, the determined adsorption parameters, i.e., adsorption capacities, adsorption enthalpies, and adsorption entropies, compare well to literature data. In this work, the results for CO2 are shown as an example.

Adsorption Device Based on a Langatate Crystal Microbalance for High Temperature High Pressure Gas Adsorption in Zeolite H-ZSM-5

PubMed Central

Ding, Wenjin; Baracchini, Giulia; Klumpp, Michael; Schwieger, Wilhelm; Dittmeyer, Roland

2016-01-01

We present a high-temperature and high-pressure gas adsorption measurement device based on a high-frequency oscillating microbalance (5 MHz langatate crystal microbalance, LCM) and its use for gas adsorption measurements in zeolite H-ZSM-5. Prior to the adsorption measurements, zeolite H-ZSM-5 crystals were synthesized on the gold electrode in the center of the LCM, without covering the connection points of the gold electrodes to the oscillator, by the steam-assisted crystallization (SAC) method, so that the zeolite crystals remain attached to the oscillating microbalance while keeping good electroconductivity of the LCM during the adsorption measurements. Compared to a conventional quartz crystal microbalance (QCM) which is limited to temperatures below 80 °C, the LCM can realize the adsorption measurements in principle at temperatures as high as 200-300 °C (i.e., at or close to the reaction temperature of the target application of one-stage DME synthesis from the synthesis gas), owing to the absence of crystalline-phase transitions up to its melting point (1,470 °C). The system was applied to investigate the adsorption of CO2, H2O, methanol and dimethyl ether (DME), each in the gas phase, on zeolite H-ZSM-5 in the temperature and pressure range of 50-150 °C and 0-18 bar, respectively. The results showed that the adsorption isotherms of these gases in H-ZSM-5 can be well fitted by Langmuir-type adsorption isotherms. Furthermore, the determined adsorption parameters, i.e., adsorption capacities, adsorption enthalpies, and adsorption entropies, compare well to literature data. In this work, the results for CO2 are shown as an example. PMID:27585356

Gas adsorption capacity of wood pellets

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

Yazdanpanah, F.; Sokhansanj, Shahabaddine; Lim, C. Jim

In this paper, temperature-programmed desorption (TPD) analysis was used to measure and analyze the adsorption of off-gases and oxygen by wood pellets during storage. Such information on how these gases interact with the material helps in the understanding of the purging/stripping behavior of off-gases to develop effective ventilation strategies for wood pellets. Steam-exploded pellets showed the lowest carbon dioxide (CO 2) uptake compared to the regular and torrefied pellets. The high CO 2 adsorption capacity of the torrefied pellets could be attributed to their porous structure and therefore greater available surface area. Quantifying the uptake of carbon monoxide by pelletsmore » was challenging due to chemical adsorption, which formed a strong bond between the material and carbon monoxide. The estimated energy of desorption for CO (97.8 kJ/mol) was very high relative to that for CO 2 (7.24 kJ/mol), demonstrating the mechanism of chemical adsorption and physical adsorption for CO and CO 2, respectively. As for oxygen, the strong bonds that formed between the material and oxygen verified the existence of chemical adsorption and formation of an intermediate material.« less

Gas adsorption capacity of wood pellets

DOE PAGES

Yazdanpanah, F.; Sokhansanj, Shahabaddine; Lim, C. Jim; ...

2016-02-03

In this paper, temperature-programmed desorption (TPD) analysis was used to measure and analyze the adsorption of off-gases and oxygen by wood pellets during storage. Such information on how these gases interact with the material helps in the understanding of the purging/stripping behavior of off-gases to develop effective ventilation strategies for wood pellets. Steam-exploded pellets showed the lowest carbon dioxide (CO 2) uptake compared to the regular and torrefied pellets. The high CO 2 adsorption capacity of the torrefied pellets could be attributed to their porous structure and therefore greater available surface area. Quantifying the uptake of carbon monoxide by pelletsmore » was challenging due to chemical adsorption, which formed a strong bond between the material and carbon monoxide. The estimated energy of desorption for CO (97.8 kJ/mol) was very high relative to that for CO 2 (7.24 kJ/mol), demonstrating the mechanism of chemical adsorption and physical adsorption for CO and CO 2, respectively. As for oxygen, the strong bonds that formed between the material and oxygen verified the existence of chemical adsorption and formation of an intermediate material.« less

High-capacity adsorption of Cr(VI) from aqueous solution using a hierarchical porous carbon obtained from pig bone.

PubMed

Wei, Shaochen; Li, Dongtian; Huang, Zhe; Huang, Yaqin; Wang, Feng

2013-04-01

A hierarchical porous carbon obtained from pig bone (HPC) was utilized as the adsorbent for removal of Cr(VI) from aqueous solution. The effects of solution pH value, concentration of Cr(VI), and adsorption temperature on the removal of Cr(VI) were investigated. The experimental data of the HPC fitted well with the Langmuir isotherm and its adsorption kinetic followed pseudo-second order model. Compared with a commercial activated carbon adsorbent (Norit CGP), the HPC showed an high adsorption capability for Cr(VI). The maximum Cr(VI) adsorption capacity of the HPC was 398.40 mg/g at pH 2. It is found that a part of the Cr(VI) was reduced to Cr(III) on the adsorbent surface from desorption experiment data. The regeneration showed adsorption capacity of the HPC can still achieve 92.70 mg/g even after fifth adsorption cycle. Copyright © 2013 Elsevier Ltd. All rights reserved.

Removal of carbonyl sulfide using activated carbon adsorption.

PubMed

Sattler, Melanie L; Rosenberk, Ranjith Samuel

2006-02-01

Wastewater treatment plant odors are caused by compounds such as hydrogen sulfide (H2S), methyl mercaptans, and carbonyl sulfide (COS). One of the most efficient odor control processes is activated carbon adsorption; however, very few studies have been conducted on COS adsorption. COS is not only an odor causing compound but is also listed in the Clean Air Act as a hazardous air pollutant. Objectives of this study were to determine the following: (1) the adsorption capacity of 3 different carbons for COS removal; (2) the impact of relative humidity (RH) on COS adsorption; (3) the extent of competitive adsorption of COS in the presence of H2S; and (4) whether ammonia injection would increase COS adsorption capacity. Vapor phase react (VPR; reactivated), BPL (bituminous coal-based), and Centaur (physically modified to enhance H2S adsorption) carbons manufactured by Calgon Carbon Corp. were tested in three laboratory-scale columns, 6 in. in depth and 1 in. in diameter. Inlet COS concentrations varied from 35 to 49 ppmv (86-120 mg/m3). RHs of 17%, 30%, 50%, and 90% were tested. For competitive adsorption studies, H2S was tested at 60 ppmv, with COS at 30 ppmv. COS, RH, H2S, and ammonia concentrations were measured using an International Sensor Technology Model IQ-350 solid state sensor, Cole-Parmer humidity stick, Interscan Corp. 1000 series portable analyzer, and Drager Accuro ammonia sensor, respectively. It was found that the adsorption capacity of Centaur carbon for COS was higher than the other two carbons, regardless of RH. As humidity increased, the percentage of decrease in adsorption capacity of Centaur carbon, however, was greater than the other two carbons. The carbon adsorption capacity for COS decreased in proportion to the percentage of H2S in the gas stream. More adsorption sites appear to be available to H2S, a smaller molecule. Ammonia, which has been found to increase H2S adsorption capacity, did not increase the capacity for COS.

Simultaneous Online Measurement of H2O and CO2 in the Humid CO2 Adsorption/Desorption Process.

PubMed

Yu, Qingni; Ye, Sha; Zhu, Jingke; Lei, Lecheng; Yang, Bin

2015-01-01

A dew point meter (DP) and an infrared (IR) CO2 analyzer were assembled in a humid CO2 adsorption/desorption system in series for simultaneous online measurements of H2O and CO2, respectively. The humidifier, by using surface-flushing on a saturated brine solution was self-made for the generation of humid air flow. It was found that by this method it became relatively easy to obtain a low H2O content in air flow and that its fluctuation could be reduced compared to the bubbling method. Water calibration for the DP-IR detector is necessary to be conducted for minimizing the measurement error of H2O. It demonstrated that the relative error (RA) for simultaneous online measurements H2O and CO2 in the desorption process is lower than 0.1%. The high RA in the adsorption of H2O is attributed to H2O adsorption on the transfer pipe and amplification of the measurement error. The high accuracy of simultaneous online measurements of H2O and CO2 is promising for investigating their co-adsorption/desorption behaviors, especially for direct CO2 capture from ambient air.

Comparative study of carbon nanotubes and granular activated carbon: Physicochemical properties and adsorption capacities.

PubMed

Gangupomu, Roja Haritha; Sattler, Melanie L; Ramirez, David

2016-01-25

The overall goal was to determine an optimum pre-treatment condition for carbon nanotubes (CNTs) to facilitate air pollutant adsorption. Various combinations of heat and chemical pre-treatment were explored, and toluene was tested as an example hazardous air pollutant adsorbate. Specific objectives were (1) to characterize raw and pre-treated single-wall (SW) and multi-wall (MW) CNTs and compare their physical/chemical properties to commercially available granular activated carbon (GAC), (2) to determine the adsorption capacities for toluene onto pre-treated CNTs vs. GAC. CNTs were purified via heat-treatment at 400 °C in steam, followed by nitric acid treatment (3N, 5N, 11N, 16N) for 3-12 h to create openings to facilitate adsorption onto interior CNT sites. For SWNT, Raman spectroscopy showed that acid treatment removed impurities up to a point, but amorphous carbon reformed with 10h-6N acid treatment. Surface area of SWNTs with 3 h-3N acid treatment (1347 m(2)/g) was higher than the raw sample (1136 m(2)/g), and their toluene maximum adsorption capacity was comparable to GAC. When bed effluent reached 10% of inlet concentration (breakthrough indicating time for bed cleaning), SWNTs had adsorbed 240 mg/g of toluene, compared to 150 mg/g for GAC. Physical/chemical analyses showed no substantial difference for pre-treated vs. raw MWNTs. Copyright © 2015 Elsevier B.V. All rights reserved.

Application of a High-Throughput Analyzer in Evaluating Solid Adsorbents for Post-Combustion Carbon Capture via Multicomponent Adsorption of CO2, N-2, and H2O

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

Mason, JA; McDonald, TM; Bae, TH

Despite the large number of metal-organic frameworks that have been studied in the context of post-combustion carbon capture, adsorption equilibria of gas mixtures including CO2, N-2, and H2O, which are the three biggest components of the flue gas emanating from a coal- or natural gas-fired power plant, have never been reported. Here, we disclose the design and validation of a high-throughput multicomponent adsorption instrument that can measure equilibrium adsorption isotherms for mixtures of gases at conditions that are representative of an actual flue gas from a power plant. This instrument is used to study 15 different metal-organic frameworks, zeolites, mesoporousmore » silicas, and activated carbons representative of the broad range of solid adsorbents that have received attention for CO2 capture. While the multicomponent results presented in this work provide many interesting fundamental insights, only adsorbents functionalized with alkylamines are shown to have any significant CO2 capacity in the presence of N-2 and H2O at equilibrium partial pressures similar to those expected in a carbon capture process. Most significantly, the amine-appended metal organic framework mmen-Mg-2(dobpdc) (mmen = N,N'-dimethylethylenediamine, dobpdc (4-) = 4,4'-dioxido-3,3'-biphenyldicarboxylate) exhibits a record CO2 capacity of 4.2 +/- 0.2 mmol/g (16 wt %) at 0.1 bar and 40 degrees C in the presence of a high partial pressure of H2O.« less

Application of a high-throughput analyzer in evaluating solid adsorbents for post-combustion carbon capture via multicomponent adsorption of CO2, N2, and H2O.

PubMed

Mason, Jarad A; McDonald, Thomas M; Bae, Tae-Hyun; Bachman, Jonathan E; Sumida, Kenji; Dutton, Justin J; Kaye, Steven S; Long, Jeffrey R

2015-04-15

Despite the large number of metal-organic frameworks that have been studied in the context of post-combustion carbon capture, adsorption equilibria of gas mixtures including CO2, N2, and H2O, which are the three biggest components of the flue gas emanating from a coal- or natural gas-fired power plant, have never been reported. Here, we disclose the design and validation of a high-throughput multicomponent adsorption instrument that can measure equilibrium adsorption isotherms for mixtures of gases at conditions that are representative of an actual flue gas from a power plant. This instrument is used to study 15 different metal-organic frameworks, zeolites, mesoporous silicas, and activated carbons representative of the broad range of solid adsorbents that have received attention for CO2 capture. While the multicomponent results presented in this work provide many interesting fundamental insights, only adsorbents functionalized with alkylamines are shown to have any significant CO2 capacity in the presence of N2 and H2O at equilibrium partial pressures similar to those expected in a carbon capture process. Most significantly, the amine-appended metal organic framework mmen-Mg2(dobpdc) (mmen = N,N'-dimethylethylenediamine, dobpdc (4-) = 4,4'-dioxido-3,3'-biphenyldicarboxylate) exhibits a record CO2 capacity of 4.2 ± 0.2 mmol/g (16 wt %) at 0.1 bar and 40 °C in the presence of a high partial pressure of H2O.

Effect of pH and Electrolytes on Adsorption of 2,4-D onto Kaolinite

NASA Astrophysics Data System (ADS)

Sharma, A.; Kawamoto, K.; Komatsu, T.; Moldrup, P.

2006-12-01

The fate and transport of pesticides in soil can be greatly influenced by adsorption onto clay minerals such as kaolinite. The ionic pesticide 2,4-D (2,4-dichlorophenoxyacetic acid) is one of the most commonly used herbicides. The purpose of this study is to investigate the effect of electrolytes and pH on the adsorption of 2,4- D onto kaolinite. The adsorption coefficient (Kd) of 2,4-D on two types of kaolinite was measured in batch experiments using water and 4 different electrolytes (0.005M CaSO4, 0.005M CaCl2, 0.01M KCl, and 0.01M NaCl). The experiments were carried out with 0.5 g kaolinite at a solid:liquid ratio of 1:20 and at different pH (1.9-6.3). The pH of the solution was controlled by addition of 0.2N of HCl. X-ray diffraction analysis of both kaolinite with and without adsorbed 2,4-D was also done to understand the location of 2,4-D adsorption. The effects of pH and electrolytes on Kd were compared and possible adsorption mechanisms were revealed for 2,4-D adsorption onto the two different types of kaolinite. The results implied that 2,4-D adsorption was higher for an electrolyte solution with monovalent cation than with divalent cation for one type of kaolinite, while no such trend was observed for the other kaolinite. The adsorption of 2,4-D increased significantly with decreasing pH for both types of kaolinite.

High-capacity adsorption of aniline using surface modification of lignocellulose-biomass jute fibers.

PubMed

Gao, Da-Wen; Hu, Qi; Pan, Hongyu; Jiang, Jiping; Wang, Peng

2015-10-01

Pyromellitic dianhydride (PMDA) modified jute fiber (MJF) were prepared with microwave treatment to generate a biosorbent for aniline removal. The characterization of the biosorbent was investigated by SEM, BET and FT-IR analysis to discuss the adsorption mechanism. The studies of various factors influencing the adsorption behavior indicated that the optimum dosage for aniline adsorption was 3g/L, the maximum adsorption capacity was observed at pH 7.0 and the adsorption process is spontaneous and endothermic. The aniline adsorption follows the pseudo second order kinetic model and Langmuir isotherm model. Moreover, the biosorbent could be regenerated through the desorption of aniline by using 0.5M HCl solution, and the adsorption capacity after regeneration is even higher than that of virgin MJF. All these results prove MJF is a promising adsorbent for aniline removal in wastewater. Copyright © 2015 Elsevier Ltd. All rights reserved.

Fe-doped graphene nanosheet as an adsorption platform of harmful gas molecules (CO, CO2, SO2 and H2S), and the co-adsorption in O2 environments

NASA Astrophysics Data System (ADS)

Cortés-Arriagada, Diego; Villegas-Escobar, Nery; Ortega, Daniela E.

2018-01-01

The adsorption of pollutant gases (CO, CO2, SO2 and H2S) onto Fe-doped graphene nanosheets (FeG) is studied on the basis of density functional theory calculations at the PBE/Def2-SVP level of theory. The most stable adsorption configurations, binding characteristics, electronic properties and stability at room temperature of the FeG-Gas interactions is fully analyzed. The gas molecules are chemisorbed onto FeG with adsorption energies in the range of 0.54-1.8 eV, with an enhanced adsorption strength compared to intrinsic graphene. The stability of the FeG-Gas interactions is dominated by Lewis-acid-base interactions, and its strength is sorted as SO2 > CO > H2S > CO2. The adsorption stability is also retained at room temperature (300 K). Due to the strong interaction of SO2, CO, and H2S, FeG could catalyze or activate these gas molecules, suggesting the possibility of FeG as a catalyst substrate. The electron acceptor/donor character of CO, CO2, SO2 and H2S molecules when adsorbed onto FeG causes charge transfer processes that are responsible for the change in conductance of FeG; thus, the response of the HOMO-LUMO gap of FeG under gas adsorption could be useful for sensing applications. Furthermore, the analysis of the co-adsorption in O2 environments shows that the CO2 interaction turns unstable onto FeG, while the sensing response towards H2S is suppressed. Finally, these results give new insights into the emerging applications of Fe-doped graphene in gas capture/filtration devices, solid-state gas sensors or as a catalyst substrate.

Density functional study of H2O molecule adsorption on α-U(001) surface.

PubMed

Huang, Shanqisong; Zeng, Xiu-Lin; Zhao, Feng-Qi; Ju, Xuehai

2016-04-01

Periodic density functional theory (DFT) calculations were performed to investigate the adsorption of H2O on U(001) surface. The metallic nature of uranium atom and different adsorption sites of U(001) surface play key roles in the H2O molecular dissociate reaction. The long-bridge site is the most favorable site of H2O-U(001) adsorption configuration. The triangle-center site of the H atom is the most favorable site of HOH-U(001) adsorption configuration. The interaction between H2O and U surface is more evident on the first layer than that on any other two sub-layers. The dissociation energy of one hydrogen atom from H2O is -1.994 to -2.215 eV on U(001) surface, while the dissociating energy decreases to -3.351 to -3.394 eV with two hydrogen atoms dissociating from H2O. These phenomena also indicate that the Oads can promote the dehydrogenation of H2O. A significant charge transfer from the first layer of the uranium surface to the H and O atoms is also found to occur, making the bonding partly ionic.

Adsorption, hydrogenation and dehydrogenation of C2H on a CoCu bimetallic layer

NASA Astrophysics Data System (ADS)

Wu, Donghai; Yuan, Jinyun; Yang, Baocheng; Chen, Houyang

2018-05-01

In this paper, adsorption, hydrogenation and dehydrogenation of C2H on a single atomic layer of bimetallic CoCu were investigated using first-principles calculations. The CoCu bimetallic layer is formed by Cu replacement of partial Co atoms on the top layer of a Co(111) surface. Our adsorption and reaction results showed those sites, which have stronger adsorption energy of C2H, possess higher reactivity. The bimetallic layer possesses higher reactivity than either of the pure monometallic layer. A mechanism of higher reactivity of the bimetallic layer is proposed and identified, i.e. in the bimetallic catalyst, the catalytic performance of one component is promoted by the second component, and in our work, the catalytic performance of Co atoms in the bimetallic layer are improved by introducing Cu atoms, lowing the activation barrier of the reaction of C2H. The bimetallic layer could tune adsorption and reaction of C2H by modulating the ratio of Co and Cu. Results of adsorption energies and adsorption configurations reveal that C2H prefers to be adsorbed in parallel on both the pure Co metallic and CoCu bimetallic layers, and Co atoms in subsurface which support the metallic or bimetallic layer have little effect on C2H adsorption. For hydrogenation reactions, the products greatly depend on the concentration and initial positions of hydrogen atoms, and the C2H hydrogenation forming acetylene is more favorable than forming vinylidene in both thermodynamics and kinetics. This study would provide fundamental guidance for hydrocarbon reactions on Co-based and/or Cu-based bimetallic surface chemistry and for development of new bimetallic catalysts.

Preparation of granular activated carbons from yellow mombin fruit stones for CO2 adsorption.

PubMed

Fiuza, Raildo Alves; Medeiros de Jesus Neto, Raimundo; Correia, Laise Bacelar; Carvalho Andrade, Heloysa Martins

2015-09-15

Stones of yellow mombin, a native fruit of the tropical America and West Indies, were used as starting materials to produce activated carbons, subsequently used as adsorbent for CO2 capture. The carbonaceous materials were either chemically activated with HNO3, H3PO4 and KOH or physically activated with CO2. The carbon samples were characterized by SEM, EDX, TG/DTA, Raman spectroscopy, physical adsorption for textural analysis and by acid-base titrations. The CO2 adsorption capacity and adsorption cycles were investigated by TG. The results indicate that the capacity of CO2 adsorption may be maximized on highly basic surfaces of micropores smaller than 1 nm. The KOH activated carbon showed high and stable capacity of CO2 adsorption after 10 cycles. Copyright © 2015 Elsevier Ltd. All rights reserved.

Synthesis of bilayer MoS{sub 2} nanosheets by a facile hydrothermal method and their methyl orange adsorption capacity

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

Ye, Lijuan; Xu, Haiyan; Zhang, Dingke

2014-07-01

Highlights: • Hexagonal phase of MoS{sub 2} nanosheets was synthesized by a facile hydrothermal method. • FE-SEM and TEM images show the sheets-like morphology of MoS{sub 2}. • Bilayer MoS{sub 2} can be grown under the optimized mole ratio of 2:1 of S:Mo at 180 °C for 50 h. • The MoS{sub 2} nanosheets possess high methyl orange adsorption capacity due to the large surface area. - Abstract: Molybdenum disulfide (MoS{sub 2}) nanosheets have received significant attention recently due to the potential applications for exciting physics and technology. Here we show that MoS{sub 2} nanosheets can be prepared by amore » facile hydrothermal method. The study of the properties of the MoS{sub 2} nanosheets prepared at different conditions suggests that the mole ratio of precursors and hydrothermal time significantly influences the purity, crystalline quality and thermal stability of MoS{sub 2}. X-ray diffraction, Raman spectra and transmission electron microscopy results indicate that bilayer MoS{sub 2} can be grown under an optimized mole ratio of 2:1 of S:Mo at 180 °C for 50 h. Moreover, such ultrathin nanosheets exhibit a prominent photoluminescence and possess high methyl orange adsorption capacity due to the large surface area, which can be potentially used in photodevice and photochemical catalyst.« less

CO2/H2O adsorption equilibrium and rates on metal-organic frameworks: HKUST-1 and Ni/DOBDC.

PubMed

Liu, Jian; Wang, Yu; Benin, Annabelle I; Jakubczak, Paulina; Willis, Richard R; LeVan, M Douglas

2010-09-07

Metal-organic frameworks (MOFs) have recently attracted intense research interest because of their permanent porous structures, huge surface areas, and potential applications as novel adsorbents and catalysts. In order to provide a basis for consideration of MOFs for removal of carbon dioxide from gases containing water vapor, such as flue gas, we have studied adsorption equilibrium of CO(2), H(2)O vapor, and their mixtures and also rates of CO(2) adsorption in two MOFs: HKUST-1 (CuBTC) and Ni/DOBDC (CPO-27-Ni or Ni/MOF-74). The MOFs were synthesized via solvothermal methods, and the as-synthesized products were solvent exchanged and regenerated before experiments. Pure component adsorption equilibria and CO(2)/H(2)O binary adsorption equilibria were studied using a volumetric system. The effects of H(2)O adsorption on CO(2) adsorption for both MOF samples were determined, and the results for 5A and NaX zeolites were included for comparison. The hydrothermal stabilities for the two MOFs over the course of repetitive measurements of H(2)O and CO(2)/H(2)O mixture equilibria were also studied. CO(2) adsorption rates from helium for the MOF samples were investigated by using a unique concentration-swing frequency response (CSFR) system. Mass transfer into the MOFs is rapid with the controlling resistance found to be macropore diffusion, and rate parameters were established for the mechanism.

Adsorption characteristics of hexavalent chromium on HCB/TiO2

NASA Astrophysics Data System (ADS)

Zhang, Li; Zhang, Yonggang

2014-10-01

Sol-gel method was adopted to prepare HCB/TiO2 and its adsorption ability of hexavalent chromium, Cr(VI), and removal from aqueous solution were investigated. The samples were characterized by Power X-ray diffraction (XRD) and a transmission electron microscope (TEM) which showed that the TiO2 was deposited on the surface of HCB. FTIR was used to identify the changes of the surface functional groups before and after adsorption. Potentiometric titration method was used to characterize the zero charge (pHpzc) characteristics of the surface of HCB/TiO2 which showed more acidic functional groups containing. Batch experiments showed that initial pH, absorbent dosage, contact time and initial concentration of Cr(VI) were important parameters for the Cr(VI) adsorption studies. The Freundlich isotherm model better reflected the experimental data better. Cr(VI) adsorption process followed the pseudo-second order kinetic model, which illustrated chemical adsorption. The thermodynamic parameters, such as Gibbs free energy (ΔG), changes in enthalpy change (ΔH) and changes in entropy change (ΔS) were also evaluated. Negative value of free energy occurred at temperature range of 25-45 °C, so Cr(VI) adsorption by HCB/TiO2 is spontaneous. Desorption results showed that the adsorption capacity could maintain 80% after five cycles. The maximum adsorption capacity for Cr(VI) was at 27.33 mg g-1 in an acidic medium, of which the value is worth comparable with other low-cost adsorbents.

Adsorption of H2O, H2, O2, CO, NO, and CO2 on graphene/g-C3N4 nanocomposite investigated by density functional theory

NASA Astrophysics Data System (ADS)

Wu, Hong-Zhang; Bandaru, Sateesh; Liu, Jin; Li, Li-Li; Wang, Zhenling

2018-02-01

Motivated by the photocatalytic reactions of small molecules on g-C3N4 by these insights, we sought to explore the adsorption of H2O and CO2 molecules on the graphene side and H2O, H2, O2, CO, NO, and CO2 molecules on the g-C3N4 side of hybrid g-C3N4/graphene nanocomposite using first-principles calculations. The atomic structure and electronic properties of hybrid g-C3N4/graphene nanocomposite is explored. The adsorption of small molecules on graphene/g-C3N4 nanocomposite is thoroughly investigated. The computational studies revels that all small molecules on graphene/g-C3N4 nanocomposite are the physisorption. The adsorption characteristics of H2O and CO2 molecules on the graphene side are similar to that on graphene. The adsorption of H2O, H2, O2, CO, NO, and CO2 molecules on the g-C3N4 side always leads to a buckle structure of graphene/g-C3N4 nanocomposite. Graphene as a substrate can significantly relax the buckle degree of g-C3N4 in g-C3N4/graphene nanocomposite.

Comparison of H2S adsorption by two hydrogel composite (HBC) derived by Empty Fruit Bunch (EFB) biochar and Coal Fly Ash (CFA)

NASA Astrophysics Data System (ADS)

Meri, N. H.; Alias, A. B.; Talib, N.; Rashid, Z. A.; Ghani, W. A. W. A. K.

2018-03-01

This study are covered the adsorption performance of two adsorbent Empty Fruit Bunch Hydrogel Biochar Composite (EFB-HBC) and Coal Fly Ash Hydrogel Composite (CFA-HC) on hydrogen sulphide. The EFB biochar were produce by pyrolysed and heated from room temperature to 550˚C at 10˚C/min under the Nitrogen flow. Meanwhile, coal fly ash collected from a power plant located in Selangor, Malaysia. Both of the materials is a waste from different industries and became the precursor to our adsorbents. EFB biochar and coal fly ash has been synthesized to become hydrogel by polymerization process with acrylamide (AAm) as monomer, N,N’-methylene bisacry lamide (MBA) as cross linker and ammonium persulfate (APS) as initiator. In addition, because of the speciality of hydrogel itself, which is has high ability in storing water, the effect of H2O wetness on EFB-HBC and CFA-HC were investigate in adsorption of H2S. EFB-HBC gave a longest breakthrough time and highest adsorption capacity compared with CFA-HC in both condition (dry/wet). The result also indicated that, the increased the bed height, increased the adsorption capacity.

Powdered activated carbon adsorption of two fishy odorants in water: Trans,trans-2,4-heptadienal and trans,trans-2,4-decadienal.

PubMed

Li, Xin; Wang, Jun; Zhang, Xiaojian; Chen, Chao

2015-06-01

Powdered activated carbon (PAC) adsorption of two fishy odorants, trans,trans-2,4-heptadienal (HDE) and trans,trans-2,4-decadienal (DDE), was investigated. Both the pseudo first-order and the pseudo second-order kinetic models well described the kinetics curves, and DDE was more readily removed by PAC. In isotherm tests, both Freundlich and Modified Freundlich isotherms fitted the experimental data well. PAC exhibited a higher adsorption capacity for DDE than for HDE, which could be ascribed to the difference in their hydrophobicity. The calculated thermodynamic parameters (ΔG0, ΔH0, and ΔS0) indicated an exothermic and spontaneous adsorption process. PAC dosage, pH, and natural organic matter (NOM) presence were found to influence the adsorption process. With increasing PAC dosage, the pseudo first-order and pseudo second-order rate constants both increased. The value of pH had little influence on HDE or DDE molecules but altered the surface charge of PAC, and the maximum adsorption capacity occurred at pH9. The presence of NOM, especially the fraction with molecular weight less than 1k Dalton, hindered the adsorption. The study showed that preloaded NOM impaired the adsorption capacity of HDE or DDE more severely than simultaneously fed NOM did. Copyright © 2015. Published by Elsevier B.V.

Adsorption, desorption, and displacement kinetics of H2O and CO2 on TiO2(110).

PubMed

Smith, R Scott; Li, Zhenjun; Chen, Long; Dohnálek, Zdenek; Kay, Bruce D

2014-07-17

The adsorption, desorption, and displacement kinetics of H2O and CO2 on TiO2(110) are investigated using temperature programmed desorption (TPD) and molecular beam techniques. The TPD spectra for both H2O and CO2 have well-resolved peaks corresponding to desorption from bridge-bonded oxygen (Ob), Ti5c, and defect sites in order of increasing peak temperature. Analysis of the saturated surface spectrum for both species reveals that the corresponding adsorption energies on all sites are greater for H2O than for CO2. Sequential dosing of H2O and CO2 reveals that, independent of the dose order, H2O molecules will displace CO2 in order to occupy the highest energy binding sites available. Isothermal experiments show that the displacement of CO2 by H2O occurs between 75 and 80 K.

Molecular simulation of methane adsorption characteristics on coal macromolecule

NASA Astrophysics Data System (ADS)

Yang, Zhiyuan; He, Xiaoxiao; Meng, Zhuoyue; Xue, Wenying

2018-02-01

In this paper, the molecular model of anthracite named Wender2 was selected to study the adsorption behaviour of single component CH4 and the competitive adsorption of CH4/CO2, CH4/H2O and CH4/N2. The molecular model of anthracite was established by molecular simulation software (Materials Studio 8.0), and Grand Canonical Monte Carlo (GCMC) simulations were carried out to investigate the single and binary component adsorption. The effects of pressure and temperature on the adsorption position, adsorption energy and adsorption capacity were mainly discussed. The results show that for the single component adsorption, the adsorption capacity of CH4 increases rapidly with the pressure ascending, and then tends to be stable after the first step. The low temperature is favourable for the adsorption of CH4, and the high temperature promotes desorption quantity of CH4 from the coal. Adsorbent molecules are preferentially adsorbed on the edge of coal macromolecules. The order of adsorption capacity of CH4/CO2, CH4/H2O and CH4/N2 in the binary component is H2O>CO2>CH4>N2. The change of pressure has little effect on the adsorption capacity of the adsorbent in the competitive adsorption, but it has a great influence on the adsorption capacity of the adsorbent, and there is a positive correlation between them.

Two basic bismuth nitrates: [Bi6O6(OH)2](NO3)4 · 2H2O with superior photodegradation activity for rhodamine B and [Bi6O5(OH)3](NO3)5 · 3H2O with ultrahigh adsorption capacity for methyl orange

NASA Astrophysics Data System (ADS)

Pang, Jiawei; Han, Qiaofeng; Liu, Weiqi; Shen, Zichen; Wang, Xin; Zhu, Junwu

2017-11-01

A novel basic bismuth nitrate, [Bi6O6(OH)2](NO3)4·2H2O (denoted as BiON-4N), was easily obtained at room temperature in the existence of 2-methoxyethanol (CH3OCH2CH2OH; 2ME) with a pH value ranging from 4.5 to 7.0. The morphology of BiON-4N could be easily tailored by changing the variety and amount of bases like urea, hexamethylenetetramine (HMTA), NaOH and NH3·H2O. When the solution pH was decreased lower than 4.5, another basic bismuth nitrate, [Bi6O5(OH)3](NO3)5·3H2O (denoted as BiON-5N), could be synthesized. Among those, BiON-4N nanoparticles obtained with 40 mmol of HMTA exhibited superior photocatalytic activity for rhodamine B (RhB) degradation with an efficiency of 100% within 4 min of UV light irradiation, which was much higher than that of commercial TiO2 (P25). The excellent photocatalytic performance of BiON-4N was mainly attributed to higher surface area (13.1 m2 g-1) in comparison with other basic bismuth nitrates. Furthermore, the as-prepared BiON-5N revealed excellent adsorption performance for the anions like methyl orange (MO) and K2Cr2O7, and especially for MO, the maximum adsorption capacity arrived up to 730 mg g-1, which should be relevant to highly positively charged surface. This work provides a new strategy for developing bismuth-based nanomaterials in the big bismuth family as potential photocatalyst and adsorbent for the removal of dyes and contaminants.

Adsorption and removal of arsenic (V) using crystalline manganese (II,III) oxide: Kinetics, equilibrium, effect of pH and ionic strength.

PubMed

Babaeivelni, Kamel; Khodadoust, Amid P; Bogdan, Dorin

2014-01-01

Manganese (II,III) oxide (Mn3O4) crystalline powder was evaluated as a potential sorbent for removal of arsenic (V) from water. Adsorption isotherm experiments were carried out to determine the adsorption capacity using de-ionized (DI) water, a synthetic solution containing bicarbonate alkalinity, and two natual groundwater samples. Adsorption isotherm data followed the Langmuir and Freundlich equations, indicating favorable adsorption of arsenic (V) onto Mn3O4, while results from the Dubinin-Radushkevich equation were suggestive of chemisorption of arsenic (V). When normalized to the sorbent surface area, the maximum adsorption capacity of Mn3O4 for arsenic (V) was 101 μg m(-2), comparable to that of activated alumina. Arsenic (V) adsorption onto Mn3O4 followed pseudo-second-order kinetics. Adsorption of arsenic (V) was greatest at pH 2, while adsorption at pH 7-9 was within 91% of maximum adsorption, whereas adsorption decreased to 32% of maximum adsorption at pH 10. Surface charge analysis confirmed the adsorption of arsenic (V) onto the acidic surface of the Mn3O4 sorbent with a pHPZC of 7.32. The presence of coexisting ions bicarbonate and phosphate resulted in a decrease in arsenic (V) uptake. Comparable adsorption capacities were obtained for the synthetic solution and both groundwater samples. Overall, crystalline Mn3O4 was an effective and viable sorbent for removal of arsenic (V) from natural water, removing greater than 95% of arsenic (V) from a 1 mg L(-1) solution within 60 min of contact time.

Comparative adsorption of Pb2+ and Cd2+ by cow manure and its vermicompost.

PubMed

Zhu, Weiqin; Du, Wenhui; Shen, Xuyang; Zhang, Hangjun; Ding, Ying

2017-08-01

Organic waste has great potential for use as an amendment to immobilize heavy metals in the environment. Therefore, this study investigates various properties of cow manure (CM) and its derived vermicompost (CV), including the pH, cationic exchangeable capacity (CEC), elemental composition and surface structure, to determine the potential of these waste products to remove Pb 2+ and Cd 2+ from solution. The results demonstrate that CV has a much higher pH, CEC and more irregular pores than CM and is enriched with minerals and ash content but has a lower C, H, O and N content. Adsorption isotherms studies shows that the adsorption of Pb 2+ and Cd 2+ onto either CM or CV follows a Langmuir model and presents maximum Pb 2+ and Cd 2+ adsorption capacities of 102.77 mg g -1 and 38.11 mg g -1 onto CM and 170.65 and 43.01 mg g -1 onto CV, respectively. Kinetic studies show that the adsorption of Pb 2+ onto CM and CV fits an Elovich model, whereas the adsorption of Cd 2+ onto CM and CV fits a pseudo-second-order model. Desorption studies indicate that CV is more effective than CM in removing Pb 2+ and Cd 2+ . FTIR analysis demonstrates that the adsorption of Pb 2+ and Cd 2+ onto CM mainly depends on existed aliphatic alcohol, aromatic acid as well as new produced carbonates, whereas that onto CV may be contributed by the existed aliphatic alcohol, aromatic acids as well as some carbonates and phosphates. Thus, vermicomposting disposal of cow manure with destination mineral addition may broaden the way of its recycle and environmental usage. Copyright © 2017 Elsevier Ltd. All rights reserved.

Adsorption, Desorption, and Displacement Kinetics of H2O and CO2 on TiO2(110)

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

Smith, R. Scott; Li, Zhenjun; Chen, Long

The adsorption, desorption, and displacement kinetics of H2O and CO2 on TiO2(110) are investigated using temperature programmed desorption (TPD) and molecular beam techniques. The TPD spectra for both H2O and CO2 have well-resolved peaks corresponding to desorption from bridge-bonded oxygen (BBO), Ti, and oxygen vacancies (VO) sites in order of increasing peak temperature. Analysis of the saturated monolayer peak for both species reveals that the corresponding adsorption energies on all sites are greater for H2O and for CO2. Sequential dosing of H2O and CO2 reveals that, independent of the dose order, H2O molecules will displace CO2 in order to occupymore » the highest energy binding sites available. Isothermal experiments show that the displacement of CO2 by H2O occurs between 75 and 80 K. Further analysis shows that a ratio of 4 H2O to 3 CO2 molecules is needed to displace CO2 from the TiO2(110) surface.« less

Experimental and Theoretical Studies of Gas Adsorption in Cu3(BTC)2: An Effective Activation Procedure

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

Liu, J.; Culp, J.T.; Natesakhawat, Sittichai

2007-07-05

We have improved the activation process for CuBTC [Cu3(BTC)2, BTC ) 1,3,5-benzenetricarboxylate] by extracting the N,N-dimethylformamide-solvated crystals with methanol; we identify material activated in this way as CuBTC-MeOH. This improvement allowed the activation to be performed at a much lower temperature, thus greatly mitigating the danger of reducing the copper ions. A review of the literature for H2 adsorption in CuBTC shows that the preparation and activation process has a significant impact on the adsorption capacity, surface area, and pore volume. CuBTC-MeOH exhibits a larger pore volume and H2 adsorption amount than any previously reported results for CuBTC. We havemore » performed atomically detailed modeling to complement experimentally measured isotherms. Quantum effects for hydrogen adsorption in CuBTC were found to be important at 77 K. Simulations that include quantum effects are in good agreement with the experimentally measured capacity for H2 at 77 K and high pressure. However, simulations underpredict the amount adsorbed at low pressures. We have compared the adsorption isotherms from simulations with experiments for H2 adsorption at 77, 87, 175, and 298 K; nitrogen adsorption at 253 and 298 K; and argon adsorption at 298 and 356 K. Reasonable agreement was obtained in all cases.« less

Selective Adsorption Resonances in the Scattering of n-H2 p-H2 n-D2 and o-D2 from Ag(111)

NASA Astrophysics Data System (ADS)

Yu, Chien-Fan; Whaley, K. Birgitta; Hogg, Charles S.; Sibener, Steven J.

1983-12-01

Diffractive and rotationally mediated selective adsorption scattering resonances are reported for n-H2 p-H2 n-D2 and o-D2 on Ag(111). Small resonance shifts and line-width differences are observed between n-H2 and p-H2 indicating a weak orientation dependence of the laterally averaged H2/Ag(111) potential. The p-H2 and o-D2 levels were used to determine the isotropic component of this potential, yielding a well depth of ~ 32 meV.

Factors affecting adsorption characteristics of Zn2+ on two natural zeolites.

PubMed

Oren, Ali Hakan; Kaya, Abidin

2006-04-17

Mining-related and industrial wastes are primary sources of heavy metal contamination in soils and groundwater. The limitation of such waste in drinking water needs to meet government requirements in order to safeguard human health and environment. Zinc, one of the most preponderant pollutants, is difficult to remove from wastewater rather than other heavy metals (i.e. lead, copper and cadmium). This paper investigates Zn2+ adsorption characteristics of two natural zeolites found in the regions of Gordes and Bigadic, in western Turkey. The results show that the Zn2+ adsorption behavior of both zeolites is highly dependent on the pH. Adsorption dependence on lower pH values (pH<4) is explained by the dissolution of crystal structure and the competition of the zinc ions with the H+. Between pH 4 and 6, the basic mechanism is the ion exchange process. The results also showed that decrease in grain size does not increase the adsorption capacity of zeolite from Gordes, yet it increases that of zeolite from Bigadic about 23%. The results also reveal that an increase in the initial concentration of Zn2+ in the system causes an increase in the adsorption capacity to a degree, then it becomes more constant at higher concentrations. With this, the removal efficiency of Gordes zeolite is two times higher than that of Bigadic zeolite. Results show that an increase in slurry concentration results in a lower uptake of Zn2+. In the final part of the paper, we compared the experimental data with the Langmuir and Freundlich isotherms. The results show that there is a good fit between the experimental data and empirical isotherms.

A Porous Aromatic Framework Constructed from Benzene Rings Has a High Adsorption Capacity for Perfluorooctane Sulfonate

PubMed Central

Luo, Qin; Zhao, Changwei; Liu, Guixia; Ren, Hao

2016-01-01

A low-cost and easily constructed porous aromatic framework (PAF-45) was successfully prepared using the Scholl reaction. PAF-45 was, for the first time, used to remove perfluorooctane sulfonate (PFOS) from aqueous solution. Systematic experiments were performed to determine the adsorption capacity of PAF-45 for PFOS and to characterize the kinetics of the adsorption process. The adsorption of PFOS onto PAF-45 reached equilibrium in 30 min, and the adsorption capacity of PAF-45 for PFOS was excellent (5847 mg g−1 at pH 3). The amount of PFOS adsorbed by PAF-45 increased significantly as the cation (Na+, Mg2+, or Fe3+) concentration increased, which probably occurred because the cations enhanced the interactions between the negatively charged PFOS molecules and the positively charged PAF-45 surface. The cations Na+, Mg2+, and Fe3+ were found to form complexes with PFOS anions in solution. Density functional theory was used to identify the interactions between PFOS and Na+, Mg2+, and Fe3+. We expect that materials of the same type as PAF-45 could be useful adsorbents for removing organic pollutants from industrial wastewater and contaminated surface water. PMID:26843015

A Porous Aromatic Framework Constructed from Benzene Rings Has a High Adsorption Capacity for Perfluorooctane Sulfonate.

PubMed

Luo, Qin; Zhao, Changwei; Liu, Guixia; Ren, Hao

2016-02-04

A low-cost and easily constructed porous aromatic framework (PAF-45) was successfully prepared using the Scholl reaction. PAF-45 was, for the first time, used to remove perfluorooctane sulfonate (PFOS) from aqueous solution. Systematic experiments were performed to determine the adsorption capacity of PAF-45 for PFOS and to characterize the kinetics of the adsorption process. The adsorption of PFOS onto PAF-45 reached equilibrium in 30 min, and the adsorption capacity of PAF-45 for PFOS was excellent (5847 mg g(-1) at pH 3). The amount of PFOS adsorbed by PAF-45 increased significantly as the cation (Na(+), Mg(2+), or Fe(3+)) concentration increased, which probably occurred because the cations enhanced the interactions between the negatively charged PFOS molecules and the positively charged PAF-45 surface. The cations Na(+), Mg(2+), and Fe(3+) were found to form complexes with PFOS anions in solution. Density functional theory was used to identify the interactions between PFOS and Na(+), Mg(2+), and Fe(3+). We expect that materials of the same type as PAF-45 could be useful adsorbents for removing organic pollutants from industrial wastewater and contaminated surface water.

Adsorption characteristics of nano-TiO2 onto zebrafish embryos and its impacts on egg hatching.

PubMed

Shih, Yu-Jen; Su, Chia-Chi; Chen, Chiu-Wen; Dong, Cheng-Di; Liu, Wen-Sheng; Huang, C P

2016-07-01

The characteristics of nanoparticles (NPs) uptake may fundamentally alter physicochemical effects of engineered NPs on aquatic organisms, thereby yielding different ecotoxicology assessment results. The adsorption behavior of nano-TiO2 (P-25) on zebrafish embryos in Holtfreter's medium (pH 7.2, I ∼ 7.2 × 10(-2) M) and the presence of sodium alginate (100 mg/L) as dispersant was investigated. Zebrafish embryos (total 100) were exposed to nano-TiO2 at different concentrations (e.g., 0, 10, 20, 60, 120 mg/L) in batch-mode assay. The adsorption capacity of nano-TiO2 on fish eggs was determined by measuring the Ti concentration on the egg surface using ICP-OES analysis. Results showed that the adsorption capacity increased rapidly in the first hour, and then declined to reach equilibrium in 8 h. The adsorption characteristics was visualized as a three-step process of rapid initial layer formation, followed by break-up of aggregates and finally rearrangement of floc structures; the maximum adsorption capacity was the sum of an inner rigid layers of aggregates of 0.81-0.84 μg-TiO2/#-egg and an outer softly flocculated layers of 1.01 μg-TiO2/#-egg. The Gibbs free energy was 543.29-551.26 and 100.75 kJ/mol, respectively, for the inner-layer and the outer-layer aggregates. Adsorption capacity at 0.5-1.0 μg-TiO2/#-egg promoted egg hatching; but hatching was inhibited at higher adsorption capacity. Results clearly showed that the configuration of TiO2 aggregates could impact the hatching efficiency of zebrafish embryos. Copyright © 2016 Elsevier Ltd. All rights reserved.

Modeling the adsorption of metal ions (Cu 2+, Ni 2+, Pb 2+) onto ACCs using surface complexation models

NASA Astrophysics Data System (ADS)

Faur-Brasquet, Catherine; Reddad, Zacaria; Kadirvelu, Krishna; Le Cloirec, Pierre

2002-08-01

Activated carbon cloths (ACCs), whose efficiency has been demonstrated for microorganics adsorption from water, were here studied in the removal of metal ions from aqueous solution. Two ACCs are investigated, they are characterized in terms of porosity parameters (BET specific surface area, percentage of microporosity) and chemical characteristics (acidic surface groups, acidity constants, point of zero charge). A first part consists in the experimental study of three metal ions removal (Cu 2+, Ni 2+ and Pb 2+) in a batch reactor. Isotherms modeling by Freundlich and Brunauer-Emmett-Teller (BET) equations enables the following adsorption order: Cu 2+>Ni 2+>Pb 2+ to be determined for adsorption capacities on a molar basis. It may be related to adsorbates characteristics in terms of electronegativity and ionic radius. The influence of adsorbent's microporosity is also shown. Adsorption experiments carried out for pH values ranging from 2 to 10 demonstrate: (i) an adsorption occurring below the precipitation pH; (ii) the strong influence of pH, with a decrease of electrostatic repulsion due to the formation of less charged hydrolyzed species coupled with a decrease of activated carbon surface charge as pH increases. The second part focuses on the modeling of adsorption versus the pH experimental data by the diffuse layer model (DLM) using Fiteql software. The model is efficient to describe the system behavior in the pH range considered. Regarding complexation constants, they show the following affinity for ACC: Pb 2+>Cu 2+>Ni 2+. They are related to initial concentrations used for the three metal ions.

Characterization of recycled rubber media for hydrogen sulphide (H2S) control.

PubMed

Wang, Ning; Park, Jaeyoung; Evans, Eric A; Ellis, Timothy G

2014-01-01

Hydrogen sulphide (H2S) adsorption capacities on recycled rubber media, tyre-derived rubber particle (TDRP), and other rubber material (ORM) have been evaluated. As part of the research, densities, moisture contents, and surface properties of TDRP and ORM have been determined. The research team findings show that TDRP and ORM are more particulate in nature and not highly porous-like activated carbon. The characteristics of surface area, pore size, and moisture content support chemisorption on the macrosurface rather than physical adsorption in micropores. For example, moisture content is essential for H2S adsorption on ORM, and an increase in moisture content results in an increase in adsorption capacity.

H2O Adsorption on Smectites: Application to the Diurnal Variation of H2O in the Martian Atmosphere

NASA Technical Reports Server (NTRS)

Zent, Aaron P.; Howard, J.; Quinn, R. C.

2000-01-01

Observations of the Martian planetary boundary layer lead to interpretations that are baffling and contradictory. In this paper, we specifically address the question of whether or not water vapor finds a substantial diurnal reservoir in the Martian regolith. To address this issue, we have measured H2O adsorption kinetics on SWy-1, a Na-rich montmorillonite from Wyoming. The highest-temperature (273 K) data equilibrates rapidly. Data gathered at realistic H2O partial pressures and temperatures appropriate to early morning show two phenomena that preclude a significant role for smectites in diurnally exchanging a large column abundance. First, the equilibration timescale is longer than a sol. Second, the equilibrium abundances are a small fraction of that predicted by earlier adsorption isotherms. The explanation for this phenomenon is that smectite clay actually increases its surface area as a function of adsorptive coverage. At Mars-like conditions, we show that the interlayer sites of smectites are likely to be unavailable.

Effect of the pH in the adsorption and in the immersion enthalpy of monohydroxylated phenols from aqueous solutions on activated carbons.

PubMed

Blanco-Martínez, D A; Giraldo, L; Moreno-Piraján, J C

2009-09-30

An activated carbon Carbochem--PS230 was modified by chemical and thermal treatment in flow of H(2) in order to evaluate the influence of the activated carbon chemical surface in the adsorption of the monohydroxylated phenols. The solid-solution interaction was determined by analyzing the adsorption isotherms at 298 K at pH 7, 9 and 11 during 48 h. The adsorption capacity of activated carbons increases when the pH solution decreases. The amount adsorbed increases in the reduced carbon at the maximum adsorption pH and decreases in the oxidized carbon. In the sample of granulated activated carbon, CAG, the monohydroxylated phenols adsorption capacity diminishes in the following order catechol >hydroquinone >resorcinol, at the three pH values. The experimental data are evaluated with Freundlich's and Langmuir's models. The immersion enthalpies are determined and increase with the retained amount, ranging between 21.5 and 45.7 J g(-1). In addition, the immersion enthalpies show more interaction with the reduced activated carbon that has lower total acidity contents.

Adsorption of tetracycline on Fe (hydr)oxides: effects of pH and metal cation (Cu2+, Zn2+ and Al3+) addition in various molar ratios

PubMed Central

Hsu, Liang-Ching; Liu, Yu-Ting; Syu, Chien-Hui; Huang, Mei-Hsia; Teah, Heng Yi

2018-01-01

Iron (Fe) (hydr)oxides control the mobility and bioavailability of tetracycline (TC) in waters and soils. Adsorption of TC on Fe (hydr)oxides is greatly affected by polyvalent metals; however, impacts of molar metal/TC ratios on TC adsorptive behaviours on Fe (hydr)oxides remain unclear. Results showed that maximum TC adsorption on ferrihydrite and goethite occurred at pH 5–6. Such TC adsorption was generally promoted by the addition of Cu2+, Zn2+ and Al3+. The greatest increase in TC adsorption was found in the system with molar Cu/TC ratio of 3 due to the formation of Fe hydr(oxide)–Cu–TC ternary complexes. Functional groups on TC that were responsible for the complexation with Cu2+shifted from phenolic diketone groups at Cu/TC molar ratio < 1 to amide groups at Cu/TC molar ratio ≥ 1. For the addition of Al3+, the complexation only took place with phenolic diketone groups, resulting in the enhanced TC adsorption at a molar Al/TC ratio of 1. However, TC adsorption decreased for Al/TC molar ratio > 1 as excess Al3+ led to the competitive adsorption with Al/TC complexes. For the Zn2+ addition, no significant correlation was found between TC adsorption capacity and molar Zn/TC ratios. PMID:29657795

Background electrolytes and pH effects on selenate adsorption using iron-impregnated granular activated carbon and surface binding mechanisms.

PubMed

Zhang, Ning; Gang, Daniel Dianchen; McDonald, Louis; Lin, Lian-Shin

2018-03-01

Iron-impregnated granular activated carbon (Fe-GAC) has been shown effective for selenite adsorptive removal from aqueous solutions, but similar effectiveness was not observed with selenate. This study examined the effects of background electrolytes and pH on selenate adsorption on to Fe-GAC, and surface bindings to elucidate the selenate adsorption mechanisms. The decrease magnitude of selenate adsorption capacity under three background electrolytes followed the order: LiCl > NaCl > KCl, as ionic strength increased from 0.01 to 0.1 M. Larger adsorption capacity differences among the three electrolytes were observed under the higher ionic strengths (0.05 and 0.1 M) than those under 0.01 M. Multiplet peak fittings of high resolution X-ray photoelectron spectra for O1s and Fe2p 3/2 indicated the presence of iron (III) on adsorbent surface. pH variations during the adsorbent preparation within 3-8 in NaCl solutions did not cause appreciable changes in the iron redox state and composition. Raman spectra showed the formation of both monodentate and bidentate inner sphere complexes under pHs <7 and a mixture of outer sphere and inner sphere complexes at pH 8. These results explained the lower selenate adsorption under alkaline conditions. Mechanisms for monodentate and bidentate formations and a stable six-member ring structure were proposed. Two strategies were recommended for modifying Fe-GAC preparation procedure to enhance the selenate adsorption: (1) mixed-metal oxide coatings to increase the point of zero charge (pH zpc ); and (2) ferrous iron coating to initially reduce selenate followed by selenite adsorption. Copyright © 2017 Elsevier Ltd. All rights reserved.

Non-contact analysis of the adsorptive ink capacity of nano silica pigments on a printing coating base.

PubMed

Jiang, Bo; Huang, Yu Dong

2014-01-01

Near infrared spectra combined with partial least squares were proposed as a means of non-contact analysis of the adsorptive ink capacity of recording coating materials in ink jet printing. First, the recording coating materials were prepared based on nano silica pigments. 80 samples of the recording coating materials were selected to develop the calibration of adsorptive ink capacity against ink adsorption (g/m2). The model developed predicted samples in the validation set with r2  = 0.80 and SEP = 1.108, analytical results showed that near infrared spectra had significant potential for the adsorption of ink capacity on the recording coating. The influence of factors such as recording coating thickness, mass ratio silica: binder-polyvinyl alcohol and the solution concentration on the adsorptive ink capacity were studied. With the help of the near infrared spectra, the adsorptive ink capacity of a recording coating material can be rapidly controlled.

Adsorption of arsenic from aqueous solution using magnetic graphene oxide

NASA Astrophysics Data System (ADS)

Sherlala, A. I. A.; Raman, A. A.; Bello, M. M.

2017-06-01

A binary of graphene oxide (GO) and iron oxide (IO) was prepared and used for the removal of arsenic from aqueous solution. The synthesized compound was characterized using XRD analysis. The prepared composite was used for the adsorption of arsenic from aqueous solution. Central Composite Design was used to design the adsorption experiments and to investigate the effects of operational parameters (initial concentration of arsenic, adsorbent dosage, pH and time) on the adsorption capacity and efficiency. The adsorbent shows a high adsorption capacity for the arsenic. The adsorption efficiency ranges between 33.2 % and 99.95 %. The most significant factors affecting the adsorption capacity were found to be the initial concentration of arsenic and the adsorbent dosage. The initial pH of the solution slightly affects the adsorption capacity, with the maximum adsorption capacity occurring around pH 6 - 7. Thus, the developed adsorbent has a potential for effective removal of arsenic from aqueous solution.

Adsorption of aliphatic polyhydroxy carboxylic acids on gibbsite: pH dependency and importance of adsorbate structure.

PubMed

Schneckenburger, Tatjana; Riefstahl, Jens; Fischer, Klaus

2018-01-01

Aliphatic (poly)hydroxy carboxylic acids [(P)HCA] occur in natural, e.g. soils, and in technical (waste disposal sites, nuclear waste repositories) compartments . Their distribution, mobility and chemical reactivity, e.g. complex formation with metal ions and radionuclides, depend, among others, on their adsorption onto mineral surfaces. Aluminium hydroxides, e.g. gibbsite [α-Al(OH) 3 ], are common constituents of related solid materials and mimic the molecular surface properties of clay minerals. Thus, the study was pursued to characterize the adsorption of glycolic, threonic, tartaric, gluconic, and glucaric acids onto gibbsite over a wide pH and (P)HCA concentration range. To consider specific conditions occurring in radioactive wastes, adsorption applying an artificial cement pore water (pH 13.3) as solution phase was investigated additionally. The sorption of gluconic acid at pH 4, 7, 9, and 12 was best described by the "two-site" Langmuir isotherm, combining "high affinity" sorption sites (adsorption affinity constants [Formula: see text] > 1 L mmol -1 , adsorption capacities < 6.5 mmol kg -1 ) with "low affinity" sites ([Formula: see text] < 0.1 L mmol -1 , adsorption capacities ≥ 19 mmol kg -1 ). The total adsorption capacities at pH 9 and 12 were roughly tenfold of that at pH 4 and 7. The S-shaped pH sorption edge of gluconic acid was modelled applying a constant capacitance model, considering electrostatic interactions, hydrogen bonding, surface complex formation, and formation of solved polynuclear complexes between Al 3+ ions and gluconic acid. A Pearson and Spearman rank correlation between (P)HCA molecular properties and adsorption parameters revealed the high importance of the size and the charge of the adsorbates. The adsorption behaviour of (P)HCAs is best described by a combination of adsorption properties of carboxylic acids at acidic pH and of polyols at alkaline pH. Depending on the molecular properties of the adsorbates and

MgO-based adsorbents for CO2 adsorption: Influence of structural and textural properties on the CO2 adsorption performance.

PubMed

Elvira, Gutiérrez-Bonilla; Francisco, Granados-Correa; Víctor, Sánchez-Mendieta; Alberto, Morales-Luckie Raúl

2017-07-01

A series of MgO-based adsorbents were prepared through solution-combustion synthesis and ball-milling process. The prepared MgO-based powders were characterized using X-ray diffraction, scanning electron microscopy, N 2 physisorption measurements, and employed as potential adsorbents for CO 2 adsorption. The influence of structural and textural properties of these adsorbents over the CO 2 adsorption behaviour was also investigated. The results showed that MgO-based products prepared by solution-combustion and ball-milling processes, were highly porous, fluffy, nanocrystalline structures in nature, which are unique physico-chemical properties that significantly contribute to enhance their CO 2 adsorption. It was found that the MgO synthesized by solution combustion process, using a molar ratio of urea to magnesium nitrate (2:1), and treated by ball-milling during 2.5hr (MgO-BM2.5h), exhibited the maximum CO 2 adsorption capacity of 1.611mmol/g at 25°C and 1atm, mainly via chemisorption. The CO 2 adsorption behaviour on the MgO-based adsorbents was correlated to their improved specific surface area, total pore volume, pore size distribution and crystallinity. The reusability of synthesized MgO-BM2.5h was confirmed by five consecutive CO 2 adsorption-desorption times, without any significant loss of performance, that supports the potential of MgO-based adsorbent. The results confirmed that the special features of MgO prepared by solution-combustion and treated by ball-milling during 2.5hr are favorable to be used as effective MgO-based adsorbent in post-combustion CO 2 capture technologies. Copyright © 2016. Published by Elsevier B.V.

Effect of degree of deacetylation of chitosan on adsorption capacity and reusability of chitosan/polyvinyl alcohol/TiO2 nano composite.

PubMed

Habiba, Umma; Joo, Tan Chin; Siddique, Tawsif A; Salleh, Areisman; Ang, Bee Chin; Afifi, Amalina M

2017-11-01

The chitosan/polyvinyl alcohol/TiO 2 composite was synthesized. Two different degrees of deacetylation of chitosan were prepared by hydrolysis to compare the effectiveness of them. The composite was analyzed via field emission scanning electron microscopy, Fourier transform infrared, X-ray diffraction, thermal gravimetric analysis, weight loss test and adsorption study. The FTIR and XRD results proved the interaction among chitosan, PVA and TiO 2 without any chemical reaction. It was found that, chitosan with higher degree of deacetylation has better stability. Furthermore, it also showed that higher DD of chitosan required less time to reach equilibrium for methyl orange. The adsorption followed the pseudo-second-order kinetic model. The Langmuir and Freundlich isotherm models were fitted well for isotherm study. Adsorption capacity was higher for the composite containing chitosan with higher DD. The dye removal rate was independent of the dye's initial concentration. The adsorption capacity was increased with temperature and it was found from reusability test that the composite containing chitosan with higher DD is more reusable. It was notable that adsorption capacity was even after 15 runs. Therefore, chitosan/PVA/TiO 2 composite can be a very useful material for dye removal. Copyright © 2017 Elsevier B.V. All rights reserved.

Chloride Ion Adsorption Capacity of Anion Exchange Resin in Cement Mortar

PubMed Central

Lee, Hanseung; Jung, Dohyun; Chen, Zhengxin

2018-01-01

This paper presents the effect of anion exchange resin (AER) on the adsorption of chloride ions in cement mortar. The kinetic and equilibrium behaviors of AER were investigated in distilled water and Ca(OH)2 saturated solutions, and then the adsorption of chloride ions by the AER in the mortar specimen was determined. The AER was used as a partial replacement for sand in the mortar specimen. The mortar specimen was coated with epoxy, except for an exposed surface, and then immersed in a NaCl solution for 140 days. The chloride content in the mortar specimen was characterized by energy dispersive X-ray fluorescence analysis and electron probe microanalysis. The results showed that the AER could adsorb the chloride ions from the solution rapidly but had a relatively low performance when the pH of its surrounding environment increased. When the AER was mixed in the cement mortar, its chloride content was higher than that of the cement matrix around it, which confirms the chloride ion adsorption capacity of the AER. PMID:29621188

Adsorption of Hg2+, Cu2+ and Zn2+ ions from aqueous solution using formaldehyde cross-linked modified chitosan-thioglyceraldehyde Schiff's base.

PubMed

Monier, M

2012-04-01

A chitosan-thioglyceraldehyde Schiff's base cross-linked magnetic resin (CSTG) was prepared and characterized using various instrumental methods. Then, the prepared resin was used for comparative studies on the removal of toxic metal ions like: Hg(2+), Cu(2+) and Zn(2+) from aqueous solutions. The effects of the initial pH value of the solution, contact time, the initial metal ion concentration and temperature on the adsorption capacity of the composite were investigated. The kinetics data were analyzed by pseudo-first order and pseudo-second order equations. The adsorption kinetics was well described by the pseudo-second order equation, and the adsorption isotherms were better fitted by the Langmuir equation. The maximum theoretical adsorption capacities of the CSTG resin for Hg(2+), Cu(2+) and Zn(2+) were found to be 98±2, 76±1 and 52±1 mg g(-1), respectively. The negative values of Gibbs free energy of adsorption (ΔG(ads°) indicated the spontaneity of the adsorption of all metal ions on the novel resin. Copyright © 2011 Elsevier B.V. All rights reserved.

Molecular adsorption properties of CO and H2O on Au-, Cu-, and AuxCuy-doped MoS2 monolayer

NASA Astrophysics Data System (ADS)

Kadioglu, Yelda; Gökoğlu, Gökhan; Üzengi Aktürk, Olcay

2017-12-01

In this study, we investigate the adsorption properties of Au, Cu, and AuxCuy nanoclusters on MoS2 sheet and the interactions of the adsorbed systems with CO and H2O molecules by using first principles calculations. Results indicate that Au, Cu, or AuxCuy strongly binds to MoS2 monolayer resulting in enhanced chemical activity and sensitivity toward CO and H2O molecules compared to bare MoS2 monolayer. Although both CO and H2O molecules bind weakly to pristine MoS2 monolayer, CO strongly binds to MoS2 sheet in the presence of Au, Cu atoms or AuxCuy clusters. Semiconductor MoS2 monolayer turns into metal upon Au or Cu adsorption. AuxCuy nanocluster adsorption decreases the band gap of MoS2 monolayer acting as a n-type dopant. AuxCuy-doped MoS2 systems have improved adsorption properties for CO and H2O molecules, so the conclusions provided in this study can be useful as a guide for next generation device modeling.

Molecular Modelling of the H2 -Adsorptive Properties of Tetrazolate-Based Metal-Organic Frameworks: From the Cluster Approach to Periodic Simulations.

PubMed

Brea, Oriana; Luna, Alberto; Díaz, Cristina; Corral, Inés

2018-06-05

Hydrogen has been proposed as a long-term non-fossil fuel to be used in a future ideal carbon-neutral energetic economy. However, its low volumetric energy density hinders its storage and transportation. Metal-organic frameworks (MOFs) represent very promising materials for this purpose due to their very extended surface areas. Azolates, in particular tetrazolates, are - together with carboxylate functionalities - very common organic linkers connecting metallic secondary building units in MOFs. This study addresses, from a theoretical perspective, the H 2 adsorptive properties of tetrazolate linkers at the molecular level, following a size-progressive approach. Specifically, we have investigated how the physisorption energies and geometries are affected when changing the environment of the linker by considering the azolates in the gas phase, immersed in a finite cluster, or being part of an infinite extended crystal material. Furthermore, we also study the H 2 adsorptive capacity of these linkers within the cluster model. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

The investigation of adsorption and dissociation of H2O on Li2O (111) by ab initio theory

NASA Astrophysics Data System (ADS)

Kong, Xianggang; Yu, You; Ma, Shenggui; Gao, Tao; Lu, Tiecheng; Xiao, Chengjian; Chen, Xiaojun; Zhang, Chuanyu

2017-06-01

The adsorption and dissociation mechanism of H2O molecule on the Li2O (111) surface have been systematically studied by using the density functional theory calculations. The parallel and vertical configurations of H2O at six different symmetry adsorption sites on the Li2O (111) surface are considered. In our calculations, it is suggested that H2O can dissociate on the perfect Li2O surface, of which the corresponding adsorption energy is 1.118 eV. And the adsorption energy decrease to be 0.241 eV when oxygen atom of H2O bonds to lithium atom of the slab. The final configurations are sensitive to the initial molecular orientation. By Bader charge analysis, the charge transfer from slab to adsorbed H2O/OH can be found due to the downward shift of lowest-unoccupied molecular orbital. We also analyze the vibrational frequencies at the Brillouin Zone centre for H2O molecule adsorbed on the stoichiometric surface. Due to the slightly different structure parameters, the calculated values of the vibrational frequencies of hydroxyl group range from 3824 to 3767 cm-1. Our results agree well with experimental results performed in FT-IR spectrum, which showed that an absorption peak of OH group appeared at 3677 cm-1 at room temperature.

Non-Contact Analysis of the Adsorptive Ink Capacity of Nano Silica Pigments on a Printing Coating Base

PubMed Central

Jiang, Bo; Huang, Yu Dong

2014-01-01

Near infrared spectra combined with partial least squares were proposed as a means of non-contact analysis of the adsorptive ink capacity of recording coating materials in ink jet printing. First, the recording coating materials were prepared based on nano silica pigments. 80 samples of the recording coating materials were selected to develop the calibration of adsorptive ink capacity against ink adsorption (g/m2). The model developed predicted samples in the validation set with r2  = 0.80 and SEP  = 1.108, analytical results showed that near infrared spectra had significant potential for the adsorption of ink capacity on the recording coating. The influence of factors such as recording coating thickness, mass ratio silica: binder-polyvinyl alcohol and the solution concentration on the adsorptive ink capacity were studied. With the help of the near infrared spectra, the adsorptive ink capacity of a recording coating material can be rapidly controlled. PMID:25329464

Adsorption of multi-heavy metals Zn and Cu onto surficial sediments: modeling and adsorption capacity analysis.

PubMed

Li, Shanshan; Zhang, Chen; Wang, Meng; Li, Yu

2014-01-01

Improved multiple regression adsorption models (IMRAMs) was developed to estimate the adsorption capacity of the components [Fe oxides (Fe), Mn oxides (Mn), organic materials (OMs), residuals] in surficial sediments for multi-heavy metal Zn and Cu. IMRAM is an improved version over MRAM, which introduces a computer program in the model developing process. As MRAM, Zn(Cu) IMRAM, and Cu(Zn) IMRAM again confirmed that there is significant interaction effects that control the adsorption of compounded Zn and Cu, which was neglected by additional adsorption model. The verification experiment shows that the relative deviation of the IMRAMs is less than 13%. It is revealed by the IMRAMs that Mn, which has the greatest adsorption capability for compounded Zn and Cu (54.889 and 161.180 mg/l, respectively), follows by interference adsorption capacity of Fe/Mn (-1.072 and -24.591 mg/l respectively). Zn and Cu influence each other through different mechanisms. When Zn is the adsorbate, compounded Cu mainly affects the adsorption capacities of Fe/Mn and Fe/Mn/OMs; while when Cu is the adsorbate, compounded Zn mainly exerts its effect on Mn, Fe/Mn, and Mn/OMs. It also shows that the compounded Zn or Cu weakened the interference adsorption of Fe/Mn, and meanwhile, strengthened the interference adsorption of Mn/OMs.

Dimethyl Methylphosphonate Adsorption Capacities and Desorption Energies on Ordered Mesoporous Carbons.

PubMed

Huynh, Kim; Holdren, Scott; Hu, Junkai; Wang, Luning; Zachariah, Michael R; Eichhorn, Bryan W

2017-11-22

In this study, we determine effective adsorption capacities and desorption energies for DMMP with highly ordered mesoporous carbons (OMCs), 1D cylindrical FDU-15, 3D hexagonal CMK-3, 3D bicontinuous CMK-8, and as a reference, microporous BPL carbon. After exposure to DMMP vapor at room temperature for approximately 70 and 800 h, the adsorption capacity of DMMP for each OMC was generally proportional to the total surface area and pore volume, respectively. Desorption energies of DMMP were determined using a model-free isoconversional method applied to thermogravimetric analysis (TGA) data. Our experiments determined that DMMP saturated carbon will desorb any weakly bound DMMP from pores >2.4 nm at room temperature, and no DMMP will adsorb into pores smaller than 0.5 nm. The calculated desorption energies for high surface coverages, 25% DMMP desorbed from pores ≤2.4 nm, are 68-74 kJ mol -1 , which is similar to the DMMP heat of vaporization (52 kJ mol -1 ). At lower surface coverages, 80% DMMP desorbed, the DMMP desorption energies from the OMCs are 95-103 kJ mol -1 . This is overall 20-30 kJ mol -1 higher in comparison to that of BPL carbon, due to the pore size and diffusion through different porous networks.

The effects of surface chemistry of mesoporous silica materials and solution pH on kinetics of molsidomine adsorption

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

Dolinina, E.S.; Parfenyuk, E.V., E-mail: terrakott37@mail.ru

2014-01-15

Adsorption kinetics of molsidomine on mesoporous silica material (UMS), the phenyl- (PhMS) and mercaptopropyl-functionalized (MMS) derivatives from solution with different pH and 298 K was studied. The adsorption kinetics was found to follow the pseudo-second-order kinetic model for all studied silica materials and pH. Effects of surface functional groups and pH on adsorption efficiency and kinetic adsorption parameters were investigated. At all studied pH, the highest molsidomine amount is adsorbed on PhMS due to π–π interactions and hydrogen bonding between surface groups of PhMS and molsidomine molecules. An increase of pH results in a decrease of the amounts of adsorbedmore » molsidomine onto the silica materials. Furthermore, the highest adsorption rate kinetically evaluated using a pseudo-second-order model, is observed onto UMS and it strongly depends on pH. The mechanism of the adsorption process was determined from the intraparticle diffusion and Boyd kinetic film–diffusion models. The results showed that the molsidomine adsorption on the silica materials is controlled by film diffusion. Effect of pH on the diffusion parameters is discussed. - Graphical abstract: The kinetic study showed that the k{sub 2} value, the rate constant of pseudo-second order kinetic model, is the highest for molsidomine adsorption on UMS and strongly depends on pH because it is determined by availability and accessibility of the reaction sites of the adsorbents molsidomine binding. Display Omitted - Highlights: • The adsorption capacities of UMS, PhMS and MMS were dependent on the pH. • At all studied pH, the highest molsidomine amount is adsorbed on PhMS. • The highest adsorption rate, k{sub 2}, is observed onto UMS and strongly depends on pH. • Film diffusion was the likely rate-limiting step in the adsorption process.« less

Nuclear quantum effects on adsorption of H2 and isotopologues on metal ions

NASA Astrophysics Data System (ADS)

Savchenko, Ievgeniia; Gu, Bing; Heine, Thomas; Jakowski, Jacek; Garashchuk, Sophya

2017-02-01

The nuclear quantum effects on the zero-point energy (ZPE), influencing adsorption of H2 and isotopologues on metal ions, are examined using normal mode analysis of ab initio electronic structure results for complexes with 17 metal cations. The lightest metallic nuclei, Li and Be, are found to be the most 'quantum'. The largest selectivity in adsorption is predicted for Cu, Ni and Co ions. Analysis of the nuclear wavepacket dynamics on the ground state electronic potential energy surfaces (PES) performed for complexes of Li+ and Cu+2 with H2/D2/HD shows that the PES anharmonicity changes the ZPE by up to 9%.

Scaling trace organic contaminant adsorption capacity by granular activated carbon.

PubMed

Corwin, Christopher J; Summers, R Scott

2010-07-15

The role of particle size on the reduction of granular activated carbon (GAC) adsorption capacity for trace organic contaminants by dissolved organic matter (DOM) is examined and applied to performance scale-up. The adsorption capacity reduction, termed fouling, must be scalable in order to use bench scale tests, such as the rapid small-scale column test (RSSCT) to predict full-scale breakthrough. Equilibrium adsorption capacity tests with GAC preloaded with DOM and RSSCT breakthrough curves at three different GAC particle sizes indicate that GAC adsorption capacity is dependent on GAC particle size when DOM is present. Thus, the RSSCT cannot be expected to match full-scale results regardless of which RSSCT design approach is used (constant or proportional diffusivity), unless a scaling factor is applied to the results. Proportional diffusivity RSSCT breakthrough curves demonstrate that surface concentration of DOM is not a good measure of fouling. It is hypothesized that pore blockage is the mechanism responsible for the dependence on particle size. As GAC particle size increases, the microporous surface area behind a constricted pore also increases. The result is lower adsorption capacity per mass of adsorbent in the larger GAC particles. A scaling methodology for equilibrium and breakthrough data is presented that accounts for the dependence of NOM preloading effects on GAC particle diameter.

Insertion of bentonite with Organometallic [Fe3O(OOC6H5)6(H2O)3(NO3).nH2O] as Adsorbent of Congo Red

NASA Astrophysics Data System (ADS)

Said, Muhammad; Paluta Utami, Hasja; Hayati, Ferlina

2018-01-01

The adsorption of Congo red using bentonite inserted organometallic has been investigated. The insertion bentonite was characterized using FT-IR Spectrophotometer, XRD and XRF analysis. The FT-IR characterization showed the higher intensity of peak wavenumber at 470.6 cm-1 for Fe3O on the ratio 1:3. While the XRD characterization showed the shift of diffraction angle of 2θ was 5.2° and has a basal spacing of 16.8 Å. In the XRF characterization, the insertion process of organometallic occurred optimally with the percentage of metal oxide reached 71.75 %. The adsorption process of bentonite inserted organometallic compound [Fe3O(OOC6H5)6(H2O)3(NO3)·nH2O] showed the adsorption rate (k) is 0.050 min-1, the largest adsorption capacity (b) at 70°C is 4.48 mol/g, the largest adsorption energy at temperature 30°C which is 6.4 kJ/mol Organometallic compounds. The value of the enthalpy (ΔH) and entropy (ΔS) decreased with increasing concentrations of the Congo red. Effect of pH on the adsorption on at pH 3 shows the biggest of number Congo red absorbed is 19.52 mg/L for insertion of bentonite.

Characterization of the cation-binding capacity of a potassium-adsorption filter used in red blood cell transfusion.

PubMed

Suzuki, Takao; Muto, Shigeaki; Miyata, Yukio; Maeda, Takao; Odate, Takayuki; Shimanaka, Kimio; Kusano, Eiji

2015-06-01

A K(+) -adsorption filter was developed to exchange K(+) in the supernatant of stored irradiated red blood cells with Na(+) . To date, however, the filter's adsorption capacity for K(+) has not been fully evaluated. Therefore, we characterized the cation-binding capacity of this filter. Artificial solutions containing various cations were continuously passed through the filter in 30 mL of sodium polystyrene sulfonate at 10 mL/min using an infusion pump at room temperature. The cation concentrations were measured before and during filtration. When a single solution containing K(+) , Li(+) , H(+) , Mg(2+) , Ca(2+) , or Al(3+) was continuously passed through the filter, the filter adsorbed K(+) and the other cations in exchange for Na(+) in direct proportion to the valence number. The order of affinity for cation adsorption to the filter was Ca(2+) >Mg(2+) >K(+) >H(+) >Li(+) . In K(+) -saturated conditions, the filter also adsorbed Na(+) . After complete adsorption of these cations on the filter, their concentration in the effluent increased in a sigmoidal manner over time. Cations that were bound to the filter were released if a second cation was passed through the filter, despite the different affinities of the two cations. The ability of the filter to bind cations, especially K(+) , should be helpful when it is used for red blood cell transfusion at the bedside. The filter may also be useful to gain a better understanding of the pharmacological properties of sodium polystyrene sulfonate. © 2015 The Authors. Therapeutic Apheresis and Dialysis © 2015 International Society for Apheresis.

Methane adsorption capacity on graphene derived from glucose and ferric chloride

NASA Astrophysics Data System (ADS)

Ismail, M. S.; Yusof, N.; Yusop, M. Zamri; Ismail, A. F.; Nasri, N. S.; Othman, F. E. Che

2018-05-01

This study examines the methane adsorption capacity using graphene derived from glucose and ferric chloride (FeCl3). The graphene was prepared via simple method by dissolution of glucose and FeCl3 in water, vaporization of water in oven, and calcination process in quartz furnace. Graphene was successfully produced with impregnation ratio of glucose and FeCl3 at 1:1 and calcination temperature of 650 °C. The prepared graphene subsequently underwent a volumetric adsorption setup, to measure the adsorption capacity of methane (CH4). The highest CH4 adsorption capacity obtained was 6.37 mmol/g at 3.5 bar and 298 K for 40 minutes. These result shows that the prepared graphene displayed good adsorption characteristic for CH4.

Adsorption of fluoride to UiO-66-NH2 in water: Stability, kinetic, isotherm and thermodynamic studies.

PubMed

Lin, Kun-Yi Andrew; Liu, Yu-Ting; Chen, Shen-Yi

2016-01-01

To provide safe drinking water, fluoride in water must be removed and adsorption processes appear to be the most widely used method. Metal organic frameworks (MOFs) represent a new class of adsorbents that have been used in various adsorption applications. To study the adsorption mechanism of fluoride to MOFs in water and obtain related adsorption parameters, we synthesized a zirconium-based MOF with a primary amine group on its ligand, named UiO-66-NH2. The kinetics, adsorption isotherm and thermodynamics of fluoride adsorption to UiO-66-NH2 were investigated. The crystalline structure of UiO-66-NH2 remained intact and the local structure of zirconium in UiO-66-NH2 did not change significantly after being exposed to fluoride. The kinetics of the fluoride adsorption in UiO-66-NH2 could be well represented by the pseudo second order rate law. The enthalpy of the adsorption indicates that the F(-) adsorption to UiO-66-NH2 was classified as a physical adsorption. However, the comparison between the adsorption capacities of UiO-66-NH2 and UiO-66 suggests that the fluoride adsorption to UiO-66-NH2 might primarily involve a strong interaction between F(-) and the metal site. The fluoride adsorption capacity of UiO-66-NH2 was found to decrease when pH>7. While the presence of chloride/bromide ions did not noticeably change the adsorption capacity of UiO-66-NH2, the ionic surfactants slightly affected the adsorption capacity of UiO-66-NH2. These findings provide insights to further optimize the adsorption process for removal of fluoride using zirconium-based MOFs. Copyright © 2015 Elsevier Inc. All rights reserved.

Modified inverse micelle synthesis for mesoporous alumina with a high D4 siloxane adsorption capacity

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

Zhong, Wei; Jiang, Ting; Jafari, Tahereh

In this work, mesoporous aluminas (MAs) with uniform and monomodal pores were fabricated via a modified inverse micelle synthesis method, using a non-polar solvent (to minimize the effect of water content) and short reaction time (for a fast evaporation process). The effects of reaction times (4–8 h), surfactant chain lengths (non-ionic surfactants), and calcination temperatures and hold times (450–600 °C; 1–4 h) on the textural properties of MA were studied. Additionally, the targeted pore sizes of MA were obtained in the range of 3.1–5.4 nm by adjusting the surfactant and reaction time. The surface area and pore volume were controlledmore » by the calcination temperature and hold time while maintaining the thermal stability of the materials. The tuned MA of the large mesopore volume achieved 168 mg/g octamethylcyclotetrasiloxane (D4 siloxane) adsorption capacity, a 32% improvement compared to commercially activated alumina. Finally, after three adsorption recycles, the synthesized MA still maintained approximate 85% of its original adsorption capacity, demonstrating a sustainable adsorption performance and high potential for related industrial applications.« less

Modified inverse micelle synthesis for mesoporous alumina with a high D4 siloxane adsorption capacity

DOE PAGES

Zhong, Wei; Jiang, Ting; Jafari, Tahereh; ...

2016-10-18

In this work, mesoporous aluminas (MAs) with uniform and monomodal pores were fabricated via a modified inverse micelle synthesis method, using a non-polar solvent (to minimize the effect of water content) and short reaction time (for a fast evaporation process). The effects of reaction times (4–8 h), surfactant chain lengths (non-ionic surfactants), and calcination temperatures and hold times (450–600 °C; 1–4 h) on the textural properties of MA were studied. Additionally, the targeted pore sizes of MA were obtained in the range of 3.1–5.4 nm by adjusting the surfactant and reaction time. The surface area and pore volume were controlledmore » by the calcination temperature and hold time while maintaining the thermal stability of the materials. The tuned MA of the large mesopore volume achieved 168 mg/g octamethylcyclotetrasiloxane (D4 siloxane) adsorption capacity, a 32% improvement compared to commercially activated alumina. Finally, after three adsorption recycles, the synthesized MA still maintained approximate 85% of its original adsorption capacity, demonstrating a sustainable adsorption performance and high potential for related industrial applications.« less

Removal of Reactofix Navy Blue 2 GFN from aqueous solutions using adsorption techniques.

PubMed

Gupta, Vinod Kumar; Jain, Rajeev; Varshney, Shaily; Saini, Vipin Kumar

2007-03-15

The wheat husk, an agricultural by-product, has been activated and used as an adsorbent for the adsorption of Reactofix Navy Blue 2 GFN from aqueous solution. In this work, adsorption of Reactofix Navy Blue 2 GFN on wheat husk and charcoal has been studied by using batch studies. The equilibrium adsorption level was determined to be a function of the solution pH, adsorbent dosage, dye concentration and contact time. The equilibrium adsorption capacities of wheat husk and charcoal for dye removal were obtained using Freundlich and Langmuir isotherms. Thermodynamic parameters such as the free energies, enthalpies and entropies of adsorption were also evaluated. Adsorption process is considered suitable for removing color, COD from waste water.

Rapid adsorption of 2,4-dichlorophenoxyacetic acid by iron oxide nanoparticles-doped carboxylic ordered mesoporous carbon.

PubMed

Tang, Lin; Zhang, Sheng; Zeng, Guang-Ming; Zhang, Yi; Yang, Gui-De; Chen, Jun; Wang, Jing-Jing; Wang, Jia-Jia; Zhou, Yao-Yu; Deng, Yao-Cheng

2015-05-01

The ordered mesoporous carbon composite functionalized with carboxylate groups and iron oxide nanoparticles (Fe/OMC) was successfully prepared and used to adsorb 2,4-dichlorophenoxyacetic acid (2,4-D) from wastewater. The resultant adsorbent possessed high degree of order, large specific surface area and pore volume, and good magnetic properties. The increase in initial pollutant concentration and contact time would make the adsorption capacity increase, but the pH and temperature are inversely proportional to 2,4-D uptake. The equilibrium of adsorption was reached within 120 min, and the equilibrated adsorption capacity increased from 99.38 to 310.78 mg/g with the increase of initial concentration of 2,4-D from 100 to 500 mg/L. Notablely, the adsorption capacity reached 97% of the maximum within the first 5 min. The kinetics and isotherm study showed that the pseudo-second-order kinetic and Langmuir isotherm models could well fit the adsorption data. These results indicate that Fe/OMC has a good potential for the rapid adsorption of 2,4-D and prevention of its further diffusion. Copyright © 2014 Elsevier Inc. All rights reserved.

Facile synthesis of hydroxy-modified MOF-5 for improving the adsorption capacity of hydrogen by lithium doping.

PubMed

Kubo, Masaru; Hagi, Hayato; Shimojima, Atsushi; Okubo, Tatsuya

2013-11-01

A facile synthesis of partially hydroxy-modified MOF-5 and its improved H2-adsorption capacity by lithium doping are reported. The reaction of Zn(NO3)2·6H2O with a mixture of terephthalic acid (H2BDC) and 2-hydroxyterephthalic acid (H2BDC-OH) in DMF gave hydroxy-modified MOF-5 (MOF-5-OH-x), in which the molar fraction (x) of BDC-OH(2-) was up to 0.54 of the whole ligand. The MOF-5-OH-x frameworks had high BET surface areas (about 3300 m(2) g(-1)), which were comparable to that of MOF-5. We suggest that the MOF-5-OH-x frameworks are formed by the secondary growth of BDC(2-)-rich MOF-5 seed crystals, which are nucleated during the early stage of the reaction. Subsequent Li doping into MOF-5-OH-x results in increased H2 uptake at 77 K and 0.1 MPa from 1.23 to 1.39 wt.% and an increased isosteric heat of H2 adsorption from 5.1-4.2 kJ mol(-1) to 5.5-4.4 kJ mol(-1). Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Predicting CH4 adsorption capacity of microporous carbon using N2 isotherm and a new analytical model

USGS Publications Warehouse

Sun, Jielun; Chen, S.; Rostam-Abadi, M.; Rood, M.J.

1998-01-01

A new analytical pore size distribution (PSD) model was developed to predict CH4 adsorption (storage) capacity of microporous adsorbent carbon. The model is based on a 3-D adsorption isotherm equation, derived from statistical mechanical principles. Least squares error minimization is used to solve the PSD without any pre-assumed distribution function. In comparison with several well-accepted analytical methods from the literature, this 3-D model offers relatively realistic PSD description for select reference materials, including activated carbon fibers. N2 and CH4 adsorption data were correlated using the 3-D model for commercial carbons BPL and AX-21. Predicted CH4 adsorption isotherms, based on N2 adsorption at 77 K, were in reasonable agreement with the experimental CH4 isotherms. Modeling results indicate that not all the pores contribute the same percentage Vm/Vs for CH4 storage due to different adsorbed CH4 densities. Pores near 8-9 A?? shows higher Vm/Vs on the equivalent volume basis than does larger pores.

Pentaethylenehexamine-Loaded Hierarchically Porous Silica for CO2 Adsorption

PubMed Central

Ji, Changchun; Huang, Xin; Li, Lei; Xiao, Fukui; Zhao, Ning; Wei, Wei

2016-01-01

Recently, amine-functionalized materials as a prospective chemical sorbent for post combustion CO2 capture have gained great interest. However, the amine grafting for the traditional MCM-41, SBA-15, pore-expanded MCM-41 or SBA-15 supports can cause the pore volume and specific surface area of sorbents to decrease, significantly affecting the CO2 adsorption-desorption dynamics. To overcome this issue, hierarchical porous silica with interparticle macropores and long-range ordering mesopores was prepared and impregnated with pentaethylenehexamine. The pore structure and amino functional group content of the modified silicas were analyzed by scanning electron microscope, transmission electron microscope, N2 adsorption, X-ray powder diffraction, and Fourier transform infrared spectra. Moreover, the effects of the pore structure as well as the amount of PEHA loading of the samples on the CO2 adsorption capacity were investigated in a fixed-bed adsorption system. The CO2 adsorption capacity reached 4.5 mmol CO2/(g of adsorbent) for HPS−PEHA-70 at 75 °C. Further, the adsorption capacity for HPS-PEHA-70 was steady after a total of 15 adsorption-desorption cycles. PMID:28773956

Tetrahedral silsesquioxane-C2H2Ti complex for hydrogen storage

NASA Astrophysics Data System (ADS)

Konda, Ravinder; Tavhare, Priyanka; Ingale, Nilesh; Chaudhari, Ajay

2018-04-01

The interaction of molecular hydrogen with tetrahedral silsesquioxane (T4)-C2H2Ti complex has been studied using Density Functional Theory with M06-2X functional and MP2 method with 6-311++G** basis set. T4-C2H2Ti complex can absorb maximum five hydrogen molecules with the gravimetric hydrogen storage capacity of 3.4 wt %. Adsorption energy calculations show that H2 adsorption on T4-C2H2Ti complex is favorable at room temperature by both the methods. We have studied the effect of temperature and pressure on Gibbs free energy corrected adsorption energies. Molecular dynamics simulations for H2 adsorbed T4-C2H2Ti complex have also been performed at 300K and show that loosely bonded H2 molecule flies away within 1fs. Various interaction energies within the complex are studied. Stability of a complex is predicted by means of a gap between Highest Occupied Molecular Orbital (HUMO) and Lowest Unoccupied Molecular Orbital (LUMO). The H2 desorption temperature for T4-C2H2Ti complex is calculated with Van't Hoff equation and it is found to be 229K.

A one-step thermal decomposition method to prepare anatase TiO2 nanosheets with improved adsorption capacities and enhanced photocatalytic activities

NASA Astrophysics Data System (ADS)

Li, Wenting; Shang, Chunli; Li, Xue

2015-12-01

Anatase TiO2 nanosheets (NSs) with high surface area have been prepared via a one-step thermal decomposition of titanium tetraisopropoxide (TTIP) in oleylamine (OM), and their adsorption capacities and photocatalytic activities are investigated by using methylene blue (MB) and methyl orange (MO) as model pollutants. During the synthesis procedure, only one type of surfactant, oleylamine (OM), is used as capping agents and no other solvents are added. Structure and properties of the TiO2 NSs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption analysis, UV-vis spectrum, X-ray photoelectron spectroscopy (XPS) and Photoluminescence (PL) methods. The results indicate that the TiO2 NSs possess high surface area up to 378 m2 g-1. The concentration of capping agents is found to be a key factor controlling the morphology and crystalline structure of the product. Adsorption and photodegradation experiments reveal that the prepared TiO2 NSs possess high adsorption capacities of model pollutants MB and high photocatalytic activity, showing that TiO2 NSs can be used as efficient pollutant adsorbents and photocatalytic degradation catalysts of MB in wastewater treatment.

Orientation and temperature dependent adsorption of H 2S on GaAs: Valence band photoemission

NASA Astrophysics Data System (ADS)

Ranke, W.; Kuhr, H. J.; Finster, J.

A cylindrically shaped GaAs single crystal was used to study the adsorption of H 2S on the six inequivalent orientations (001), (113), (111), (110), (111) and (113) by angle resolved valence band photoelectron spectroscopy and surface dipole measurements. Adsorption at 150 K on the surface prepared by molecular beam epitaxy (MBE) yields similar adsorbate induced emission on all orientations which were ascribed to SH radicals. On (110), where preferential adsorption occurs additional features from molecular H 2S are observed. The adsorbate spectra at 720 K are ascribed to atomic sulphur. On the surface prepared by ion bombardment and annealing, defect enhanced adsorption occurs in the range (111)-(113). The adsorbate spectra are very similar to those on the MBE surface at 720 K. Thus, no new species are adsorbed on defects but only sticking probability and penetration capability are increased.

Preparation and properties of chitosan-metal complex: Some factors influencing the adsorption capacity for dyes in aqueous solution.

PubMed

Rashid, Sadia; Shen, Chensi; Yang, Jing; Liu, Jianshe; Li, Jing

2018-04-01

Chitosan-metal complexes have been widely studied in wastewater treatment, but there are still various factors in complex preparation which are collectively responsible for improving the adsorption capacity need to be further studied. Thus, this study investigates the factors affecting the adsorption ability of chitosan-metal complex adsorbents, including various kinds of metal centers, different metal salts and crosslinking degree. The results show that the chitosan-Fe(III) complex prepared by sulfate salts exhibited the best adsorption efficiency (100%) for various dyes in very short time duration (10min), and its maximum adsorption capacity achieved 349.22mg/g. The anion of the metal salt which was used in preparation played an important role to enhance the adsorption ability of chitosan-metal complex. SO 4 2- ions not only had the effect of crosslinking through electrostatic interaction with amine group of chitosan polymer, but also could facilitate the chelation of metal ions with chitosan polymer during the synthesis process. Additionally, the pH sensitivity and the sensitivity of ionic environment for chitosan-metal complex were analyzed. We hope that these factors affecting the adsorption of the chitosan-metal complex can help not only in optimizing its use but also in designing new chitosan-metal based complexes. Copyright © 2017. Published by Elsevier B.V.

High Water Tolerance of a Core-Shell-Structured Zeolite for CO2 Adsorptive Separation under Wet Conditions.

PubMed

Miyamoto, Manabu; Ono, Shumpei; Kusukami, Kodai; Oumi, Yasunori; Uemiya, Shigeyuki

2018-06-11

Dehumidification in CO 2 adsorptive separation processes is an important issue, owing to its high energy consumption. However, available adsorbents such as low-silica zeolites show a significant decrease in CO 2 adsorption capacity when water vapor is present. A core-shell-structured MFI-type zeolite with a hydrophilic ZSM-5 coated with a hydrophobic silicalite-1 shell layer was applied in CO 2 adsorptive separation under wet conditions. This hybrid material demonstrated remarkably high water tolerance with stable CO 2 adsorption performance without additional thermal treatment for regeneration, whereas a significant decrease in the CO 2 adsorption amount because of water vapor was observed on the parent ZSM-5. The core-shell structure of zeolites with high pore volumes, such as LTA or CHA, could also be suitable candidates for high CO 2 adsorption capacity and high water tolerance for practical applications. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evaluating the Adsorptive Capacities of Chemsorb 1000 and Chemsorb 1425

NASA Technical Reports Server (NTRS)

Monje, Oscar Alberto Monje; Surma, Jan M.; Johnsey, Marissa N.; Melendez, Orlando

2014-01-01

The Air Revitalization Lab at KSC tested Chemsorb 1000 and 1425, two candidate sorbents for use in future air revitalization technologies being evaluated by the ARREM project. Chemsorb 1000 and 1425 are granular coconut-shell activated carbon sorbents produced by Molecular Products, Inc. that may be used in the TCCS. Chemsorb 1000 is a high grade activated carbon for organic vapor adsorption. In contrast, Chemsorb 1425 is a high-grade impregnated activated carbon for adsorption of airborne ammonia and amines. Chemsorb 1000 was challenged with simulated spacecraft gas streams in order to determine its adsorptive capacities for mixtures of volatile organics compounds. Chemsorb 1425 was challenged with various NH3 concentrations to determine its adsorptive capacity.

Adsorption, Desorption, and Displacement Kinetics of H2O and CO2 on Forsterite, Mg2SiO4(011)

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

Smith, R. Scott; Li, Zhenjun; Dohnalek, Zdenek

We have examined the adsorbate-substrate interaction kinetics of CO2 and H2O on a natural forsterite crystal surface, Mg2SiO4(011), with 10-15% of substitutional Fe2+. We use temperature programmed desorption (TPD) and molecular beam techniques to determine the adsorption, desorption, and displacement kinetics for H2O and CO2. Neither CO2 nor H2O has distinct sub-monolayer desorption peaks but instead both have a broad continuous desorption feature that evolve smoothly into multilayer desorption. Inversion of the monolayer coverage spectra for both molecules reveals that the corresponding binding energies for H2O are greater than that for CO2 on all sites. The relative strength of thesemore » interactions is the dominant factor in the competitive adsorption/displacement kinetics. In experiments where the two adsorbates are co-dosed, H2O always binds to the highest energy binding sites available and displaces CO2. The onset of CO2 displacement by H2O occurs between 65 and 75 K.« less

Edge functionalised & Li-intercalated 555-777 defective bilayer graphene for the adsorption of CO2 and H2O

NASA Astrophysics Data System (ADS)

Lalitha, Murugan; Lakshmipathi, Senthilkumar; Bhatia, Suresh K.

2017-04-01

The adsorption of CO2 and H2O on divacanacy (DV) defected graphene cluster, and its bilayer counterpart is investigated using first-principles calculations. Both single and bilayer DV graphene cluster, are functionalised with H and F atoms. On these sheets the gas molecules are physisorbed, and the divacancy defect effectively improves the adsorption of CO2, while fluorination enhances the hydrophobicity of the graphene cluster. Among the convex and concave curvature regions induced due to the DV defect, the adsorption of the gas molecules on the concave meniscus is more favourable. Fluorine termination induces 73% reduction in Henry law constants for H2O, while for the CO2 molecule it increases by 8%, which indicates the DV defective sheet is a better candidate for CO2 capture compared to the STW defective sheet. Besides, both AA and AB divacant defect bilayer sheets are equally stable, wherein AA stacking results in a cavity between the sheets, while in AB stacking, the layers slide one over the other. Nevertheless, both these bilayer sheets are comparatively stabler than the monolayer. However, intercalation of lithium decreases the interlayer separation, particularly in AA stacking, which enhances the CO2 adsorption, but in the Bernal stacking enhances it hydrophobicity.

Adsorption of sulfur dioxide on ammonia-treated activated carbon fibers

USGS Publications Warehouse

Mangun, C.L.; DeBarr, J.A.; Economy, J.

2001-01-01

A series of activated carbon fibers (ACFs) and ammonia-treated ACFs prepared from phenolic fiber precursors have been studied to elucidate the role of pore size, pore volume, and pore surface chemistry on adsorption of sulfur dioxide and its catalytic conversion to sulfuric acid. As expected, the incorporation of basic functional groups into the ACFs was shown as an effective method for increasing adsorption of sulfur dioxide. The adsorption capacity for dry SO2 did not follow specific trends; however the adsorption energies calculated from the DR equation were found to increase linearly with nitrogen content for each series of ACFs. Much higher adsorption capacities were achieved for SO2 in the presence of oxygen and water due to its catalytic conversion to H2SO4. The dominant factor for increasing adsorption of SO2 from simulated flue gas for each series of fibers studied was the weight percent of basic nitrogen groups present. In addition, the adsorption energies calculated for dry SO2 were shown to be linearly related to the adsorption capacity of H2SO4 from this flue gas for all fibers. It was shown that optimization of this parameter along with the pore volume results in higher adsorption capacities for removal of SO2 from flue gases. ?? 2001 Elsevier Science Ltd. All rights reserved.

Adsorption behavior of hydrotalcite-like modified bentonite for Pb2+, Cu2+and methyl orange removal from water

NASA Astrophysics Data System (ADS)

Chen, Yu; Peng, Jingdong; Xiao, Huan; Peng, Huanjun; Bu, Lingli; Pan, Ziyu; He, Yan; Chen, Fang; Wang, Xiang; Li, Shiyu

2017-10-01

Hydrotalcite-like compound (HTlc) which contained lanthanum cation was prepared successfully. The title compound was characterized by thermogravimetry analysis, element analysis, X-ray fluorescence, Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, as well as specific surface area. The study sought to investigate the adsorption of heavy metals and dye (Pb2+, Cu2+ and methyl orange) in aqueous solution on Ben-HTlc. For optimization of adsorption behavior of the three elements, the pH value, contact time, adsorbate concentration were optimized. As for Pb2+, Cu2+ and methyl orange (MO), the single-component adsorption generally reached the maximum quantity in first 20 min and their respective adsorption capacities were 384.6 mg g-1, 156.3 mg g-1 and 333.3 mg g-1 (pH = 6.5 ± 0.1), the adsorption affinities were in the following sequence Pb2+ > MO > Cu2+. The repeated adsorption and regeneration studies showed the promising application of Ben-HTlc. The breakthrough experimental consequence had shown that the synthesized Ben-HTlc could efficiently remove heavy metals and dye from water, suggesting the potential utilization of Ben-HTlc in pollutants removal.

The Adsorption Capacity of GONs/CMC/Fe₃O₄ Magnetic Composite Microspheres and Applications for Purifying Dye Wastewater.

PubMed

Lv, Shenghua; Zhu, Linlin; Li, Ying; Jia, Chunmao; Sun, Shiyu

2017-01-11

Graphene oxide nanosheets (GONs)/carboxymethyl chitosan (CMC)/Fe₃O₄ magnetic composite microspheres (MCMs) were prepared by enclosing Fe₃O₄ particles with CMC and GONs in turn. The microstructures of GONs and GONs/CMC/Fe₃O₄ MCMs were characterized by FTIR, XRD, TEM, and SEM. The effects of GON content, pH value, and adsorption time on the adsorption capacity of the MCMs were investigated. The results show that the GONs/CMC/Fe₃O₄ MCMs have a greater specific surface area and a strong adsorption capacity for dye wastewater. Meanwhile, the adsorption mechanism was investigated, and the results accorded with the pseudo-second-order kinetic model and the Freundlich isotherm model. The search results indicate that GONs/CMC/Fe₃O₄ MCMs can be used to purify dye wastewater and has an important potential use in the practical purification of dye wastewater.

Kinetic studies of adsorption of thiocyanate onto ZnCl2 activated carbon from coir pith, an agricultural solid waste.

PubMed

Namasivayam, C; Sangeetha, D

2005-09-01

The adsorption of thiocyanate onto ZnCl2 activated carbon developed from coir pith was investigated to assess the possible use of this adsorbent. The influence of various parameters such as agitation time, thiocyanate concentration, adsorbent dose, pH and temperature has been studied. Adsorption followed second-order rate kinetics. Two theoretical adsorption isotherms, namely, Langmuir and Freundlich were used to describe the experimental results. The Langmuir adsorption capacity (Q0) was found to be 16.2 mg g(-1) of the adsorbent. The per cent adsorption was maximum in the pH range 3.0-7.0. pH effect and desorption studies showed that ion exchange and chemisorption mechanism are involved in the adsorption process. Thermodynamic parameters such as DeltaG0, DeltaH0 and DeltaS0 for the adsorption were evaluated. The negative values of DeltaH0 confirm the exothermic nature of adsorption. Effects of foreign ions on the adsorption of thiocyanate have been investigated. Removal of thiocyanate from ground water was also tested.

Adsorptive removal of Cr3+ from aqueous solutions using chitosan microfibers immobilized with plant polyphenols as biosorbents with high capacity and selectivity

NASA Astrophysics Data System (ADS)

Zhang, Ting; Wang, Yujia; Kuang, Yiwen; Yang, Ruilin; Ma, Jun; Zhao, Shilin; Liao, Yang; Mao, Hui

2017-05-01

A novel biosorbent was facilely prepared by immobilizing bayberry tannin (BT, a typical natural polyphenols) onto chitosan microfiber (CM). The as-prepared CM-BT adsorbent featured to a well-defined microfibrous morphology and highly distributed adsorption sites, which was highly efficient and selective for the adsorptive removal of Cr3+ from aqueous solutions. Based on batch experiments, the adsorption of Cr3+ on CM-BT was pH-dependent, and the optimized adsorption pH was determined to be 5.5. The adsorption capacity of CM-BT to Cr3+ was high up to 20.90 mg/g. The co-existing cations, such as Mg2+, Ca2+, Fe3+ and Cu2+, exhibited no significant influences on the adsorption of Cr3+ on CM-BT. The adsorption kinetics were well fitted by the pseudo-second-order rate model (R2 > 0.99) while the adsorption isotherms were well described by the Langmuir model (R2 > 0.98). Importantly, CM-BT was effective for the continues treatment of low concentration Cr3+ (2.0 mg/L) contaminated wastewater. Before reached the breakthrough point (5% of the initial Cr3+ concentration, 0.1 mg/L), the treated volume was as high as 894 bed volume, manifesting the great potential of CM-BT in practical treatment of Cr3+ contaminated wastewater.

Ultra-high adsorption capacity of MgO/SiO2 composites with rough surfaces for Congo red removal from water.

PubMed

Hu, Mengqing; Yan, Xinlong; Hu, Xiaoyan; Zhang, Jiajin; Feng, Rui; Zhou, Min

2018-01-15

Due to its high isoelectric point, relative safety and low environmental toxicity, magnesium oxide has attracted much attention for its role in the removal of toxic dyes from wastewater. Herein, MgO-SiO 2 composites with rough surfaces were synthesized by a one-step method. The as-prepared composites were characterized for the adsorption of Congo red from water using adsorption kinetics and isotherms. The adsorption capacity of the 20% MgO-SiO 2 sample could be as high as ∼4000mg/g at 25°C, which is the highest value reported to date. The adsorption process of Congo red on the as-synthesized samples obeyed the Langmuir adsorption model. The MgO-SiO 2 composite sample could be regenerated by calcination, and the regeneration efficiency remained for up to 5 cycles of the regeneration. Copyright © 2017 Elsevier Inc. All rights reserved.

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

PubMed

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

2017-04-01

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

H2S adsorption and dissociation on NH-decorated graphene: A first principles study

NASA Astrophysics Data System (ADS)

Faye, Omar; Eduok, Ubong; Szpunar, Jerzy; Samoura, Almoustapha; Beye, Aboubaker

2018-02-01

The removal of H2S gas poses an emerging environmental concern because of the lack of knowledge of an efficient adsorbent. A detailed theoretical study of H2S adsorption and dissociation on NH-doped graphene (GNH) has been carried out by means of density theory calculations. Our results reveal that the adsorption of H2S molecule on GNH composite is enhanced by the presence of active site such as the NH radicals. These NH radical sites formed NHsbnd H bonds and increase the charge transfer from H2S to GNH. The dissociation of the adsorbed H2S molecule leads the chemisorption of SH radical via H-transfer to GNH, while the formation of GNH2 at a weight percent of 3.76 wt% of NH radical is an endothermic process with an energy of 0.299 eV and 0.358 eV for ortho and para-position respectively. However, at 7.25 wt% NH radical, we observed a complete dissociation of H2S molecule with an energy released of 0.711 eV for the chemisorbed S atom on GN2H4. Moreover, the H-transfer of the second H atom of H2S molecule at 3.76 wt% was energetic unfavorable. The trend of predicted results within this study reveals that NH-doped graphene (GNH) successfully adsorbed and eliminated of H2S molecule; this work unveils definitive theoretical procedures which can be tested and validated experimentally.

Ultra-high adsorption capacity of zeolitic imidazole framework-67 (ZIF-67) for removal of malachite green from water.

PubMed

Lin, Kun-Yi Andrew; Chang, Hsuan-Ang

2015-11-01

Zeolitic imidazole frameworks (ZIFs), a new class of adsorbents, are proposed to adsorb Malachite Green (MG) in water. Particularly, ZIF-67 was selected owing to its stability in water and straightforward synthesis. The as-synthesized ZIF-67 was characterized and used to adsorb MG from water. Factors affecting the adsorption capacity were investigated including mixing time, temperature, the presence of salts and pH. The kinetics, adsorption isotherm and thermodynamics of the MG adsorption to ZIF-67 were also studied. The adsorption capacity of ZIF-67 for MG could be as high as 2430mgg(-1) at 20°C, which could be improved at the higher temperatures. Such an ultra-high adsorption capacity of ZIF-67 was almost 10-times of those of conventional adsorbents, including activated carbons and biopolymers. A mechanism for the high adsorption capacity was proposed and possibly attributed to the π-π stacking interaction between MG and ZIF-67. ZIF-67 also could be conveniently regenerated by washing with ethanol and the regeneration efficiency could remain 95% up to 4 cycles of the regeneration. ZIF-67 was also able to remove MG from the aquaculture wastewater, in which MG can be typically found. These features enable ZIF-67 to be one of the most effective and promising adsorbent to remove MG from water. Copyright © 2015 Elsevier Ltd. All rights reserved.

DFT studies on H 2O adsorption and its effect on CO oxidation over spinel Co 3O 4 (110) surface

NASA Astrophysics Data System (ADS)

Xu, Xiang Lan; Li, Jun Qian

2011-12-01

Adsorption of H2O and its effect on CO oxidation over spinel Co3O4 (110) surface were studied by density functional theory calculations. H2O is adsorbed favorably at the octahedral cobalt (Cooct) site through O atom on the surface. Hydrogen bonding interaction between 1s orbitals of H atoms in H2O and the 2p orbitals of surface active oxygen sites plays a key role for H2O adsorption. The inhibition effect of H2O adsorption on the CO oxidation over the surfaces is attributed to the competition between H2O and CO molecules for the surface twofold coordinated oxygen site.

Adsorption of Polycyclic aromatic hydrocarbons (fluoranthene and anthracenemethanol) by functional graphene oxide and removal by pH and temperature-sensitive coagulation.

PubMed

Zhang, Caili; Wu, Lin; Cai, Dongqing; Zhang, Caiyun; Wang, Ning; Zhang, Jing; Wu, Zhengyan

2013-06-12

A new kind of functional graphene oxide with fine stability in water was fabricated by mixing graphene oxide (GO) and brilliant blue (BB) with a certain weight ratio. The adsorption performance of this mixture of BB and GO (BBGO) to polycyclic aromatic hydrocarbons (anthracenemethanol (AC) and fluoranthene (FL)) was investigated, and the results indicated BBGO possessed adsorption capacity of 1.676 mmol/g and removal efficiency of 72.7% as to AC and adsorption capacity of 2.212 mmol/g and removal efficiency of 93.2% as to FL. After adsorption, pH and temperature-sensitive coagulation (PTC) method was used to remove the AC/BBGO or FL/BBGO complex and proved to be an effective approach to flocculate the AC/BBGO or FL/BBGO complex into large flocs, which tended to be removed from the aqueous solution.

High capacity adsorption media and method of producing

DOEpatents

Tranter, Troy J.; Mann, Nicholas R.; Todd, Terry A.; Herbst, Ronald S.

2010-10-05

A method of producing an adsorption medium to remove at least one constituent from a feed stream. The method comprises dissolving and/or suspending at least one metal compound in a solvent to form a metal solution, dissolving polyacrylonitrile into the metal solution to form a PAN-metal solution, and depositing the PAN-metal solution into a quenching bath to produce the adsorption medium. The at least one constituent, such as arsenic, selenium, or antimony, is removed from the feed stream by passing the feed stream through the adsorption medium. An adsorption medium having an increased metal loading and increased capacity for arresting the at least one constituent to be removed is also disclosed. The adsorption medium includes a polyacrylonitrile matrix and at least one metal hydroxide incorporated into the polyacrylonitrile matrix.

High capacity adsorption media and method of producing

DOEpatents

Tranter, Troy J [Idaho Falls, ID; Herbst, R Scott [Idaho Falls, ID; Mann, Nicholas R [Blackfoot, ID; Todd, Terry A [Aberdeen, ID

2008-05-06

A method of producing an adsorption medium to remove at least one constituent from a feed stream. The method comprises dissolving at least one metal compound in a solvent to form a metal solution, dissolving polyacrylonitrile into the metal solution to form a PAN-metal solution, and depositing the PAN-metal solution into a quenching bath to produce the adsorption medium. The at least one constituent, such as arsenic, selenium, or antimony, is removed from the feed stream by passing the feed stream through the adsorption medium. An adsorption medium having an increased metal loading and increased capacity for arresting the at least one constituent to be removed is also disclosed. The adsorption medium includes a polyacrylonitrile matrix and at least one metal hydroxide incorporated into the polyacrylonitrile matrix.

Simultaneous laboratory measurements of CO2 and H2O adsorption on palagonite: Implications for the Martian climate and volatile reservoir

NASA Technical Reports Server (NTRS)

Zent, A. P.; Quinn, R.

1993-01-01

We are measuring the simultaneous adsorption of H2O and CO2 on palagonite materials in order to improve the formulation of climate models for Mars. We report on the initial co-adsorption data. Models of the Martian climate and volatile inventory indicate that the regolith serves as one of the primary reservoirs of outgassed volatiles and that it exchanges H2O and CO2 with the atmosphere in response to changes in insolation associated with astronomical cycles. Physical adsorbate must exist on the surfaces of the cold particulates that constitute the regolith, and the size of that reservoir can be assessed through laboratory measurements of adsorption on terrestrial analogs. Many studies of the independent adsorption of H2O and CO2 on Mars analog were made and appear in the literature. Empirical expressions that relate the adsorptive coverage of each gas to the temperature of the soil and partial pressure have been derived based on the laboratory data. Numerical models incorporate these adsorption isotherms into climatic models, which predict how the adsorptive coverage of the regolith and hence, the pressure of each gas in the atmosphere will vary as the planet moves through its orbit. These models suggest that the regolith holds several tens to hundreds of millibars of CO2 and that during periods of high obliquity warming of the high-latitude regolith will result in desorption of the CO2, and a consequent increase in atmospheric pressure. At lower obliquities, the caps cool and the equator warms forcing the desorption of several tens of millibars of CO2, which is trapped into quasipermanent CO2 caps.

Mercury adsorption of modified mulberry twig chars in a simulated flue gas.

PubMed

Shu, Tong; Lu, Ping; He, Nan

2013-05-01

Mulberry twig chars were prepared by pyrolysis, steam activation and impregnation with H2O2, ZnCl2 and NaCl. Textural characteristics and surface functional groups were performed using nitrogen adsorption and FTIR, respectively. Mercury adsorption of different modified MT chars was investigated in a quartz fixed-bed absorber. The results indicated that steam activation and H2O2-impregnation can improve pore structure significantly and H2O2-impregnation and chloride-impregnation promote surface functional groups. However, chloride-impregnation has adverse effect on pore structure. Mercury adsorption capacities of impregnated MT chars with 10% or 30% H2O2 are 2.02 and 1.77 times of steam activated MT char, respectively. Mercury adsorption capacity of ZnCl2-impregnated MT char increase with increasing ZnCl2 content and is better than that of NaCl-impregnated MT char at the same chloride content. The modified MT char (MT873-A-Z5) prepared by steam activation following impregnation with 5% ZnCl2 exhibits a higher mercury adsorption capacity (29.55 μg g(-1)) than any other MT chars. Copyright © 2013 Elsevier Ltd. All rights reserved.

Enhancement of p-nitrophenol adsorption capacity through N2-thermal-based treatment of activated carbons

NASA Astrophysics Data System (ADS)

Álvarez-Torrellas, S.; Martin-Martinez, M.; Gomes, H. T.; Ovejero, G.; García, J.

2017-08-01

In this work several activated carbons showing different textural and chemical properties were obtained by chemical and physical activation methods, using a lignocellulosic material (peach stones) as precursor. The activated carbon resulting from the chemical activation, namely as CAC, revealed the best textural properties (SBET = 1521 m2 g-1, pore volume = 0.90 cm3 g-1) and an acidic character. It was found that the activated carbon obtained at 300 °C (under air atmosphere, PAC_air), and those synthesized at 750 °C in presence of N2 flow with bubbling of water/12 M H3PO4 solution (PAC_N2(H2O)/PAC_N2(H3PO4)), respectively, revealed worse textural properties, compared to CAC. Two functionalization treatments, by using sulphuric acid at boiling temperature (PACS) and nitric acid-urea-N2 heating at 800 °C (PAC-NUT), were applied to PAC_air, in order to enhance the adsorption ability of the carbon material. Several techniques were carried out to characterize the physical and chemical properties of the obtained carbon materials. The modification treatments had influence on the carbon surface properties, since the nitric acid-urea-N2 heating treatment led to a carbon material with highly-improved properties (SBET = 679 m2 g-1, pHIEP = 5.3). Accordingly, the original and modified-carbon materials were tested as adsorbents to remove 4-nitrophenol (4-NP), assessing batch and fixed-bed column adsorption tests. PAC-NUT carbon offered the best adsorption behavior (qe = 234 mg g-1), showing a high ability for the removal of 4-NP from water.

N-doping effectively enhances the adsorption capacity of biochar for heavy metal ions from aqueous solution.

PubMed

Yu, Wenchao; Lian, Fei; Cui, Guannan; Liu, Zhongqi

2018-02-01

N-doping was successfully employed to improve the adsorption capacity of biochar (BC) for Cu 2+ and Cd 2+ by direct annealing of crop straws in NH 3 . The surface N content of BC increased more than 20 times by N-doping; meanwhile the content of oxidized-N was gradually diminished but graphitic-N was formed and increased with increasing annealing temperature and duration time. After N-doping, a high graphitic-N percentage (46.4%) and S BET (418.7 m 2 /g) can be achieved for BC. As a result, the N-doped BC exhibited an excellent adsorption capacity for Cu 2+ (1.63 mmol g -1 ) and Cd 2+ (1.76 mmol g -1 ), which was up to 4.0 times higher than that of the original BC. Furthermore, the adsorption performance of the N-doped BC remained stable even at acidic conditions. A positive correlation can be found between adsorption capacity with the graphitic N content on BC surface. The surface chemistry of N-doped BC before and after the heavy metal ions adsorption was carefully examined by XPS and FTIR techniques, which indicated that the adsorption mechanisms mainly included cation-π bonding and complexation with graphitic-N and hydroxyl groups of carbon surfaces. Copyright © 2017 Elsevier Ltd. All rights reserved.

The role of high oxygen vacancy concentration on modification of surface properties and H2S adsorption on the rutile TiO2 (110)

NASA Astrophysics Data System (ADS)

Wei, Shiqian; Wang, Fang; Dan, Meng; Zeng, Kaiyue; Zhou, Ying

2017-11-01

In this work, spin-polarized DFT + U method has been employed to investigate adsorption properties of H2S on the rutile TiO2 (110) surface with a high coverage of bridging oxygen vacancies (BOVs). The influence of different BOV coverage (θ-BOVs) on the surface electronic structure is examined. Defected states increase within the band gap with θ-BOVs increasing from 1/8 to 4/8 monolayer (ML). The high defected surface with θ-BOVs = 4/8 ML is determined to have a desired band structure and noticeable visible light response. In addition, H2S adsorption behaviors are noticeably affected by different H2S coverage (θ-H2S). Particularly, it is found molecular adsorption at θ-H2S ≤ 1/8 ML and dissociative adsorption at the higher θ-H2S. The maximization of spontaneous dissociation of H2S can be realized when the BOVs are all covered by H2S molecules. This work gains mechanistic insights into BOVs in tuning the surface properties and provides a guide for the effective utilization of the active surface sites on the rutile TiO2 (110) in the field of H2S splitting.

Adsorption and Desorption Characteristics of Cd2+ and Pb2+ by Micro and Nano-sized Biogenic CaCO3

PubMed Central

Liu, Renlu; Guan, Yong; Chen, Liang; Lian, Bin

2018-01-01

The purpose of this study was to elucidate the characteristics and mechanisms of adsorption and desorption for heavy metals by micro and nano-sized biogenic CaCO3 induced by Bacillus subtilis, and the pH effect on adsorption was investigated. The results showed that the adsorption characteristics of Cd2+ and Pb2+ are well described by the Langmuir adsorption isothermal equation, and the maximum adsorption amounts for Cd2+ and Pb2+ were 94.340 and 416.667 mg/g, respectively. The maximum removal efficiencies were 97% for Cd2+, 100% for Pb2+, and the desorption rate was smaller than 3%. Further experiments revealed that the biogenic CaCO3 could maintain its high adsorption capability for heavy metals within wide pH ranges (3–8). The FTIR and XRD results showed that, after the biogenic CaCO3 adsorbed Cd2+ or Pb2+, it did not produce a new phase, which indicated that biogenic CaCO3 and heavy metal ions were governed by a physical adsorption process, and the high adsorptive capacity of biogenic CaCO3 for Cd2+ and Pb2+ were mainly attributed to its large total specific surface area. The findings could improve the state of knowledge about biogenic CaCO3 formation in the environment and its potential roles in the biogeochemical cycles of heavy metals. PMID:29434577

Adsorption of Eu(III) onto TiO2: effect of pH, concentration, ionic strength and soil fulvic acid.

PubMed

Tan, Xiaoli; Fang, Ming; Li, Jiaxing; Lu, Yi; Wang, Xiangke

2009-08-30

The effects of pH, initial Eu(III) concentration, ionic strength and fulvic acid (FA) on the adsorption of Eu(III) on TiO(2) are investigated by using batch techniques. The results indicate that the presence of FA strongly enhances the adsorption of Eu(III) on TiO(2) at low pH values. Besides, the adsorption of Eu(III) on TiO(2) is significantly dependent on pH values and independent of ionic strength. The adsorption of Eu(III) on TiO(2) is attributed to inner-sphere surface complexation. The diffuse layer model (DLM) is applied to simulate the adsorption data, and fits the experimental data well with the aid of FITEQL 3.2. X-ray photoelectron spectroscopy (XPS) is performed to study the species of Eu(III) adsorbed on the surfaces of TiO(2)/FA-TiO(2) hybrids at a molecular level, which suggest that FA act as "bridge" between Eu(III) and TiO(2) particles to enhance the ability to adsorb Eu(III) in solution.

Adsorption of SO2 on bituminous coal char and activated carbon fiber

USGS Publications Warehouse

DeBarr, Joseph A.; Lizzio, Anthony A.; Daley, Michael A.

1997-01-01

The SO2 adsorption behaviors of activated carbons produced from Illinois coal and of commercially prepared activated carbon fibers (ACFs) were compared. There was no relation between surface area of coal-based carbons and SO2 adsorption, whereas adsorption of SO2 on the series of ACFs was inversely proportional to N2 BET surface area. Higher surface area ACFs had wider pores and adsorbed less SO2; thus, pore size distribution is thought to play a significant role in SO2 adsorption for these materials. Oxidation with HNO3 and/or H2SO4, followed by heat treatment at 700−925°C to remove carbon−oxygen complexes, resulted in increased SO2 adsorption for both coal chars and ACFs. This behavior was explained by an increase in the available number of free sites, previously occupied by oxygen and now available for SO2 adsorption. The use of nitrogen-containing functional groups on ACFs of proper pore size shows promise for further increasing SO2 adsorption capacities. Knowledge of the relationship among the number of free sites, pore size, and surface chemistry on corresponding SO2 adsorption should lead to the development of more efficient adsorbents prepared from either coal or ACFs.

Tetracycline adsorption on kaolinite: pH, metal cations and humic acid effects.

PubMed

Zhao, Yanping; Geng, Jinju; Wang, Xiaorong; Gu, Xueyuan; Gao, Shixiang

2011-07-01

Contamination of environmental matrixes by human and animal wastes containing antibiotics is a growing health concern. Because tetracycline is one of the most widely-used antibiotics in the world, it is important to understand the factors that influence its mobility in soils. This study investigated the effects of pH, background electrolyte cations (Li(+), Na(+), K(+), Ca(2+) and Mg(2+)), heavy metal Cu(2+) and humic acid (HA) on tetracycline adsorption onto kaolinite. Results showed that tetracycline was greatly adsorbed by kaolinite over pH 3-6, then decreased with the increase of pH, indicating that tetracycline adsorption mainly through ion exchange of cations species and complexation of zwitterions species. In the presence of five types of cations (Li(+), Na(+), K(+), Ca(2+) and Mg(2+)), tetracycline adsorption decreased in accordance with the increasing of atomic radius and valence of metal cations, which suggested that outer-sphere complexes formed between tetracycline and kaolinite, and the existence of competitor ions lead to the decreasing adsorption. The presence of Cu(2+) greatly enhanced the adsorption probably by acting as a bridge ion between tetracycline species and the edge sites of kaolinite. HA also showed a major effect on the adsorption: at pH < 6, the presence of HA increased the adsorption, while the addition of HA showed little effect on tetracycline adsorption at higher pH. The soil environmental conditions, like pH, metal cations and soil organic matter, strongly influence the adsorption behavior of tetracycline onto kaolinite and need to be considered when assessing the environmental toxicity of tetracycline.

Adsorption of p-nitrophenols (PNP) on microalgal biochar: Analysis of high adsorption capacity and mechanism.

PubMed

Zheng, Heshan; Guo, Wanqian; Li, Shuo; Chen, Yidi; Wu, Qinglian; Feng, Xiaochi; Yin, Renli; Ho, Shih-Hsin; Ren, Nanqi; Chang, Jo-Shu

2017-11-01

Biochars derived from three microalgal strains (namely, Chlorella sp. Cha-01, Chlamydomonas sp. Tai-03 and Coelastrum sp. Pte-15) were evaluated for their capacity to adsorb p-nitrophenols (PNP) using raw microalgal biomass and powdered activated carbon (PAC) as the control. The results show that BC-Cha-01 (biochar from Chlorella sp. Cha-01) exhibited a high PNP adsorption capacity of 204.8mgg -1 , which is 250% and 140% higher than that of its raw biomass and PAC, respectively. The adsorption kinetics and equilibrium are well described with pseudo-second-order equation and Freundlich model, respectively. BC-Cha-01 was found to contain higher polarity moieties with more O-containing functional groups than PAC and other microalgae-derived biochars. The strong polarity of binding sites on BC-Cha-01 may be responsible for its superior adsorption capacity. The biochars from Chlorella sp. Cha-01 seem to have the potential to serve as a highly efficient PNP adsorbent for wastewater treatment or emergency water pollution control. Copyright © 2017 Elsevier Ltd. All rights reserved.

ISS and TPD study of the adsorption and interaction of CO and H2 on polycrystalline Pt

NASA Technical Reports Server (NTRS)

Melendez, Orlando; Hoflund, Gar B.; Schryer, David R.

1990-01-01

The adsorption and interaction of CO and H2 on polycrystalline Pt has been studied using ion scattering spectroscopy (ISS) and temperature programmed desorption (TPD). The ISS results indicate that the initial CO adsorption on Pt takes place very rapidly and saturates the Pt surface with coverage close to a monolayer. ISS also shows that the CO molecules adsorb at an angular orientation from the surface normal and perhaps parallel to the surface. A TPD spectrum obtained after coadsorbing C-12 O-16 and C-13 O-18 on Pt shows no isotopic mixing, which is indicative of molecular CO adsorption. TPD spectra obtained after coadsorbing H2 and CO on polycrystalline Pt provides evidence for the formation of a CO-H surface species.

Effect of heat treatment on CO2 adsorption of KOH-activated graphite nanofibers.

PubMed

Meng, Long-Yue; Park, Soo-Jin

2010-12-15

In this work, graphite nanofibers (GNFs) were successfully expanded intercalating KOH followed by heat treatment in the temperature range of 700-1000 °C. The aim was to improve the CO(2) adsorption capacity of the GNFs by increasing the porosity of GNFs. The effects of heat treatment on the pore structures of GNFs were investigated by N(2) full isotherms, XRD, SEM, and TEM. The CO(2) adsorption capacity was measured by CO(2) isothermal adsorption at 25 °C and 1 atm. From the results, it was found that the activation temperature had a major influence on CO(2) adsorption capacity and textural properties of GNFs. The specific surface area, total pore volume, and mesopore volume of the GNFs increased after heat treatment. The CO(2) adsorption isotherms showed that G-900 exhibited the best CO(2) adsorption capacity with 59.2 mg/g. Copyright © 2010 Elsevier Inc. All rights reserved.

Structural properties and adsorption capacity of holocellulose aerogels synthesized from an alkali hydroxide-urea solution

NASA Astrophysics Data System (ADS)

Kwon, Gu-Joong; Kim, Dae-Young; Hwang, Jae-Hyun; Kang, Joo-Hyon

2014-05-01

A tulip tree was used to synthesize a holocellulose aerogel from an aqueous alkali hydroxide-urea solution with the substitution of an organic solvent followed by freeze-drying. For comparison, the synthesized holocellulose aerogels were divided into two groups according to the source of the hydrogel, an upper suspended layer and a bottom concentrated layer of the centrifuged solution of cellulose and NaOH/urea solvents. We investigated the effects of the temperature of the pre-cooled NaOH/urea solution ( i.e., dissolution temperature) on the pore structure and the adsorption capacity of the holocellulose aerogel. A nano-fibrillar network structure of the holocellulose aerogel was observed, with little morphological difference in pore structure for different dissolution temperatures. Both micropores and mesopores were observed in the holocellulose aerogel. The specific surface area of the holocellulose aerogel was generally greater at lower dissolution temperatures. In a series of adsorption tests using methylene blue, the holocellulose aerogel showed the greatest adsorption capacity at the lowest dissolution temperature tested (-2°C). However, the dissolution temperature generally had little effect on the adsorption capacity. The holocellulose aerogel produced from the upper suspended layer of the centrifuged hydrogel solution showed a greater porosity and adsorption capacity than the one produced from the bottom concentrated layer. Overall, the aerogel made by utilizing a delignified tulip tree display a high surface area and a high adsorption property, indicating its possible application in eco-friendly adsorption materials.

Adsorption of Dissolved Gases (CH4, CO2, H2, Noble Gases) by Water-Saturated Smectite Clay Minerals

NASA Astrophysics Data System (ADS)

Bourg, I. C.; Gadikota, G.; Dazas, B.

2016-12-01

Adsorption of dissolved gases by water-saturated clay minerals plays important roles in a range of fields. For example, gas adsorption in on clay minerals may significantly impact the formation of CH4 hydrates in fine-grained sediments, the behavior of CH4 in shale, CO2 leakage across caprocks of geologic CO2 sequestration sites, H2 leakage across engineered clay barriers of high-level radioactive waste repositories, and noble gas geochemistry reconstructions of hydrocarbon migration in the subsurface. Despite its importance, the adsorption of gases on clay minerals remains poorly understood. For example, some studies have suggested that clay surfaces promote the formation of CH4 hydrates, whereas others indicate that clay surfaces inhibit the formation of CH4 hydrates. Here, we present molecular dynamics (MD) simulations of the adsorption of a range of gases (CH4, CO2, H2, noble gases) on clay mineral surfaces. Our results indicate that the affinity of dissolved gases for clay mineral surfaces has a non-monotone dependence on the hydrated radius of the gas molecules. This non-monotone dependence arises from a combination of two effects: the polar nature of certain gas molecules (in particular, CO2) and the templating of interfacial water structure by the clay basal surface, which results in the presence of interfacial water "cages" of optimal size for intermediate-size gas molecules (such as Ne or Ar).

Adsorption of Acid Blue 25 dye by bentonite and surfactant modified bentonite

NASA Astrophysics Data System (ADS)

Jeeva, Mark; Wan Zuhairi, W. Y.

2018-04-01

Adsorption of Acid Blue (AB 25) from water via batch adsorption experiments onto Na-Bentonite (NB) and CTAB-modified bentonite (CTAB-Ben) was investigated. Studies concerning the factors influencing the adsorption capacities of NB and CTAB-Ben, such as initial dye concentration, adsorbent dosage, pH, contact time and temperature were investigated and discussed. The results revealed that CTAB-modified bentonite demonstrated high adsorption capacities toward acid dyes, while NB exhibited sorption capacities lower than CTAB-Ben. The maximum adsorption efficiency was found to be 50% at an AB 25 concentration of 50 mg/L, adsorbent dosage of 1.8 g/L, reaction time of 90 min and equilibrium pH of 11. The results of isotherm study fit the Langmuir and Freundlich models (R2 > 0.93) and (R2 > 0.9) respectively.

Simultaneous adsorption of SO2 and NO from flue gas over mesoporous alumina.

PubMed

Sun, Xin; Tang, Xiaolong; Yi, Honghong; Li, Kai; Ning, Ping; Huang, Bin; Wang, Fang; Yuan, Qin

2015-01-01

Mesoporous alumina (MA) with a higher ability to simultaneously remove SO2 and NO was prepared by the evaporation-induced self-assembly process. The adsorption capacities of MA are 1.79 and 0.702 mmol/g for SO2 and NO, respectively. The Brunauer-Emmett-Teller method was used to characterize the adsorbent. Simultaneous adsorption of SO2 and NO from flue gas over MA in different operating conditions had been studied in a fixed bed reactor. The effects of temperature, oxygen concentration and water vapour were investigated. The experimental results showed that the optimum temperature for MA to simultaneously remove SO2 and NO was 90°C. The simultaneous adsorption capacities of SO2 and NO could be enhanced by increasing O2 when its concentration was below 5%. The changes of simultaneous adsorption capacities were not obvious when O2 concentration was above 5%. The increase in relative humidity results in an increase after dropping of SO2 adsorption capacity, whereas the adsorption capacity of NO showed an opposite trend. The results suggest that MA is a great adsorbent for simultaneous removal of SO2 and NO from flue gas.

Adsorption of Pb2+ on Thiol-functionalized Mesoporous Silica, SH-MCM-48

NASA Astrophysics Data System (ADS)

Taba, P.; Mustafa, R. D. P.; Ramang, L. M.; Kasim, A. H.

2018-03-01

Modification of mesoporous silica, MCM-48, by using 3- mercaptopropyltrimethoxysilane has been successfully conducted. MCM-48 and SH-MCM-48 were characterized using XRD and FTIR. SH-MCM-48 was used as an adsorbent of Pb2+ ions from solution. A number of Pb2+ ions adsorbed were studied as the function of time, pH, and concentration. The concentration of the ions after adsorption was determined by an Atomic Absorption Spectrophotometer. The removal of the adsorbed ions from the SH-MCM-48 was also studied using several desorbing agents. The result showed that the optimum time was 20 minutes and optimum pH was 4. The adsorption of Pb(II) ion followed the pseudo-second-order with the rate constant of 0,2632 g•mg-1•min-1. Adsorption of Pb(II) ion fitted the Langmuir isotherm with the adsorption capacity of 0,1088 mmol/g. The best desorbing agent to remove the adsorbed ion from SH-MCM-48 was 0.3 M HCl solution with the desorption percentage of 58.6%.

Adsorption of heavy metal ions by sawdust of deciduous trees.

PubMed

Bozić, D; Stanković, V; Gorgievski, M; Bogdanović, G; Kovacević, R

2009-11-15

The adsorption of heavy metal ions from synthetic solutions was performed using sawdust of beech, linden and poplar trees. The adsorption depends on the process time, pH of the solution, type of ions, initial concentration of metals and the sawdust concentration in suspension. The kinetics of adsorption was relatively fast, reaching equilibrium for less than 20 min. The adsorption equilibrium follows Langmuir adsorption model. The ion exchange mechanism was confirmed assuming that the alkali-earth metals from the adsorbent are substituted by heavy metal ions and protons. On lowering the initial pH, the adsorption capacity decreased, achieving a zero value at a pH close to unity. The maximum adsorption capacity (7-8 mg g(-1) of sawdust) was achieved at a pH between 3.5 and 5 for all the studied kinds of sawdust. The initial concentration of the adsorbate and the concentration of sawdust strongly affect the process. No influence of particles size was evidenced. A degree of adsorption higher than 80% can be achieved for Cu(2+) ions but it is very low for Fe(2+) ions, not exceeding 10%.

Granular bamboo-derived activated carbon for high CO(2) adsorption: the dominant role of narrow micropores.

PubMed

Wei, Haoran; Deng, Shubo; Hu, Bingyin; Chen, Zhenhe; Wang, Bin; Huang, Jun; Yu, Gang

2012-12-01

Cost-effective biomass-derived activated carbons with a high CO(2) adsorption capacity are attractive for carbon capture. Bamboo was found to be a suitable precursor for activated carbon preparation through KOH activation. The bamboo size in the range of 10-200 mesh had little effect on CO(2) adsorption, whereas the KOH/C mass ratio and activation temperature had a significant impact on CO(2) adsorption. The bamboo-derived activated carbon had a high adsorption capacity and excellent selectivity for CO(2) , and also the adsorption process was highly reversible. The adsorbed amount of CO(2) on the granular activated carbon was up to 7.0 mmol g(-1) at 273 K and 1 bar, which was higher than almost all carbon materials. The pore characteristics of activated carbons responsible for high CO(2) adsorption were fully investigated. Based on the analysis of narrow micropore size distribution of several activated carbons prepared under different conditions, a more accurate micropore range contributing to CO(2) adsorption was proposed. The volume of micropores in the range of 0.33-0.82 nm had a good linear relationship with CO(2) adsorption at 273 K and 1 bar, and the narrow micropores of about 0.55 nm produced the major contribution, which could be used to evaluate CO(2) adsorption on activated carbons. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Phosphorus recovery from biogas slurry by ultrasound/H2O2 digestion coupled with HFO/biochar adsorption process.

PubMed

He, Xuemeng; Zhang, Tao; Ren, Hongqiang; Li, Guoxue; Ding, Lili; Pawlowski, Lucjan

2017-02-01

Phosphorus (P) recovery from biogas slurry has recently attracted considerable interest. In this work, ultrasound/H 2 O 2 digestion coupled with ferric oxide hydrate/biochar (HFO/biochar) adsorption process was performed to promote P dissolution, release, and recovery from biogas slurry. The results showed that the optimal total phosphorus release efficiency was achieved at an inorganic phosphorus/total phosphorus ratio of 95.0% at pH 4, 1mL of added H 2 O 2 , and ultrasonication for 30min. The P adsorption by the HFO/biochar followed pseudo second-order kinetics and was mainly controlled by chemical processes. The Langmuir-Freundlich model matched the experimental data best for P adsorption by HFO/biochar at 298 and 308K, whereas the Freundlich model matched best at 318K. The maximum amount of P adsorbed was 220mg/g. The process was endothermic, spontaneous, and showed an increase in disorder at the solid-liquid interface. The saturated adsorbed HFO/biochar continually releases P and is most suitable for use in an alkaline environment. The amount of P released reached 29.1mg/g after five extractions. P mass balance calculation revealed that 11.3% of the total P can be made available. Copyright © 2016. Published by Elsevier Ltd.

Adsorption of phthalic acid and salicylic acid and their effect on exchangeable Al capacity of variable-charge soils.

PubMed

Li, Jiuyu; Xu, Renkou

2007-02-01

Low-molecular-weight (LMW) organic acids may be adsorbed by soils and the adsorption could affect their biodegradation and efficiency in many soil processes. In the present study, the adsorption of phthalic acid and salicylic acid and their effect on the exchangeable Al capacity of variable-charge soils were investigated. The results indicated that phthalic acid and salicylic acid were adsorbed by four variable-charge soils to some extent, oxisols showed a greater adsorption capacity for organic acids than ultisols, and the ability of the four variable-charge soils to adsorb the organic acids at different pH generally followed the order Kunming oxisol > Xuwen oxisol > Jinxian ultisol > Lechang ultisol, which was closely related to their content of free iron oxides and amorphous iron and aluminum oxides. The adsorption of organic acids induced a decrease in the zeta potentials of soils and oxides. Goethite has greater adsorption capacity for organic acid than Xuwen oxisol and the adsorption of organic acids resulted in a bigger decrease in the zeta potential of goethite suspensions. After free iron oxides were removed, less organic acid was adsorbed by Xuwen oxisol and no change was observed in zeta potential for the soil suspension after organic acid was added. The presence of phthalic acid increased the capacity of exchangeable Al and the increment in the four variable-charge soils also followed the order Kunming oxisol > Xuwen oxisol > Lechang ultisol and Jinxian ultisol. The presence of salicylic acid increased the capacity of exchangeable Al in Kunming oxisol, Xuwen oxisol, and Jinxian ultisol, but decreased it in Lechang ultisol due to less adsorption of the acid and formation of soluble Al-salicylate complexes in solution. After free iron oxides were removed, less effect of organic acid on exchangeable Al was observed for Xuwen oxisol, which further confirmed that the iron oxides played a significant role in organic acid adsorption and had a consequent effect

Adsorption and dissociation of H2O on the (001) surface of uranium mononitride: energetics and mechanism from first-principles investigation.

PubMed

Bo, Tao; Lan, Jian-Hui; Zhang, Yu-Juan; Zhao, Yao-Lin; He, Chao-Hui; Chai, Zhi-Fang; Shi, Wei-Qun

2016-05-21

The interfacial interaction of uranium mononitride (UN) with water from the environment unavoidably leads to corrosion of nuclear fuels, which affects a lot of processes in the nuclear fuel cycle. In this work, the microscopic adsorption behaviors of water on the UN(001) surface as well as water dissociation and accompanying H2 formation mechanisms have been investigated on the basis of DFT+U calculations and ab initio atomistic thermodynamics. For adsorption of one H2O monomer, the predicted adsorption energies are -0.88, -2.07, and -2.07 eV for the most stable molecular, partially dissociative, and completely dissociative adsorption, respectively. According to our calculations, a water molecule dissociates into OH and H species via three pathways with small energy barriers of 0.78, 0.72, and 0.85 eV, respectively. With the aid of the neighboring H atom, H2 formation through the reaction of H* + OH* can easily occur via two pathways with energy barriers of 0.61 and 0.36 eV, respectively. The molecular adsorption of water shows a slight coverage dependence on the surface while this dependence becomes obvious for partially dissociative adsorption as the water coverage increases from 1/4 to 1 ML. In addition, based on the "ab initio atomistic thermodynamic" simulations, increasing H2O partial pressure will enhance the stability of the adsorbed system and water coverage, while increasing temperature will decrease the H2O coverage. We found that the UN(001) surface reacts easily with H2O at room temperature, leading to dissolution and corrosion of the UN fuel materials.

Production of granular activated carbon from waste walnut shell and its adsorption characteristics for Cu(2+) ion.

PubMed

Kim, J W; Sohn, M H; Kim, D S; Sohn, S M; Kwon, Y S

2001-08-17

Production of granular activated carbon by chemical activation has been attempted employing walnut shells as the raw material. The thermal characteristics of walnut shell were investigated by TG/DTA and the adsorption capacity of the produced activated carbon was evaluated using the titration method. As the activation temperature increased, the iodine value increased. However, a temperature higher than 400 degrees C resulted in a thermal degradation, which was substantiated by scanning electron microscopy (SEM) analysis, and the adsorption capacity decreased. Activation longer than 1h at 375 degrees C resulted in the destruction of the microporous structure of activated carbon. The iodine value increased with the increase in the concentration of ZnCl2 solution. However, excessive ZnCl2 in the solution decreased the iodine value. The extent of activation by ZnCl2 was compared with that by CaCl2 activation. Enhanced activation was achieved when walnut shell was activated by ZnCl2. Applicability of the activated carbon as adsorbent was examined for synthetic copper wastewater. Adsorption of copper ion followed the Freundlich model. Thermodynamic aspects of adsorption have been discussed based on experimental results. The adsorption capacity of the produced activated carbon met the conditions for commercialization and was found to be superior to that made from coconut shell.

[Blood plasma protein adsorption capacity of perfluorocarbon emulsion stabilized by proxanol 268 (in vitro and in vivo studies)].

PubMed

Sklifas, A N; Zhalimov, V K; Temnov, A A; Kukushkin, N I

2012-01-01

The adsorption abilities of the perfluorocarbon emulsion stabilized by Proxanol 268 were investigated in vitro and in vivo. In vitro, the saturation point for the blood plasma proteins was nearly reached after five minutes of incubation of the emulsion with human/rabbit blood plasma and was stable for all incubation periods studied. The decrease in volume ratio (emulsion/plasma) was accompanied by the increase in the adsorptive capacity of the emulsion with maximal values at 1/10 (3.2 and 1.5 mg of proteins per 1 ml of the emulsion, for human and rabbit blood plasma, respectively) that was unchanged at lower ratios. In vivo, in rabbits, intravenously injected with the emulsion, the proteins with molecular masses of 12, 25, 32, 44, 55, 70, and 200 kDa were adsorbed by the emulsion (as in vitro) if it was used 6 hours or less before testing. More delayed testing (6 h) revealed elimination of proteins with molecular masses of 25 and 44 kDa and an additional pool of adsorpted new ones of 27, 50, and 150 kDa. Specific adsorptive capacity of the emulsion enhanced gradually after emulsion injection and reached its maximum (3.5-5 mg of proteins per 1 ml of the emulsion) after 24 hours.

Chloride Ion Adsorption Capacity of Anion Exchange Resin in Cement Mortar.

PubMed

Lee, Yunsu; Lee, Hanseung; Jung, Dohyun; Chen, Zhengxin; Lim, Seungmin

2018-04-05

This paper presents the effect of anion exchange resin (AER) on the adsorption of chloride ions in cement mortar. The kinetic and equilibrium behaviors of AER were investigated in distilled water and Ca(OH)₂ saturated solutions, and then the adsorption of chloride ions by the AER in the mortar specimen was determined. The AER was used as a partial replacement for sand in the mortar specimen. The mortar specimen was coated with epoxy, except for an exposed surface, and then immersed in a NaCl solution for 140 days. The chloride content in the mortar specimen was characterized by energy dispersive X-ray fluorescence analysis and electron probe microanalysis. The results showed that the AER could adsorb the chloride ions from the solution rapidly but had a relatively low performance when the pH of its surrounding environment increased. When the AER was mixed in the cement mortar, its chloride content was higher than that of the cement matrix around it, which confirms the chloride ion adsorption capacity of the AER.

Simutaneous adsorption of CO2 and H2O under Mars-like conditions and application to the evolution of the Martian climate

NASA Technical Reports Server (NTRS)

Zent, Aaron P.; Quinn, Richard C.

1995-01-01

The Martian regolith is the most substantial volatile reservoir on the planet; estimates of its adsorbed inventory have been based on simple measurements of the adsorption of either water or CO2 in isolation. Under some conditions, H2O can poison adsorbate surfaces, such that CO2 uptake is greatly reduced. We have made the first measurements of the simultaneous adsorption of CO2 and H2O under conditions appropriate to the Martian regolith and have found that at H2O monolayer coverage above about 0.5, CO2 begins to be displaced into the gas phase. We have developed an empirical expression that describes our co-adsorption data and have applied it to standard models of the Martian regolith. We find that currently, H2O does not substantially displace CO2, implying that the adsorbate inventories previously derived may be accurate, not more than 3-4 kPa (30-40 mbar). No substantial increase in atmospheric pressure is predicted at higher obliquities because high-latitude ground ice buffers the partial pressure of H2O in the pores, preventing high monolayer coverages of H2O from displacing CO2. The peak atmospheric pressure at high obliquity does increase as the total inventory of exchangeable CO2 increases.

Study on the Adsorption Capacities for Airborne Particulates of Landscape Plants in Different Polluted Regions in Beijing (China)

PubMed Central

Zhang, Wei-Kang; Wang, Bing; Niu, Xiang

2015-01-01

Urban landscape plants are an important component of the urban ecosystem, playing a significant role in the adsorption of airborne particulates and air purification. In this study, six common landscape plants in Beijing were chosen as research subjects, and the adsorption capacities for each different plant leaf and the effects of the leaf structures for the adsorption capacities for particulates were determined. Preliminary results show that needle-leaved tree species adsorbed more airborne particulates than broad-leaved tree species for the same leaf area. Pinus tabuliformis exhibits the highest adsorption capacity, at 3.89 ± 0.026 μg·cm−2, almost two times as much as that of Populus tomentosa (2.00 ± 0.118 μg·cm−2). The adsorption capacities for PM10 of the same tree species leaves, in different polluted regions had significant differences, and the adsorption capacities for PM10 of the tree species leaf beside the Fifth Ring Road were higher than those of the tree species leaves in the Botanical Garden, although the adsorption capacities for PM2.5 of the same tree species in different polluted regions had no significant differences. By determining the soluble ion concentrations of the airborne particulates in two regions, it is suggested that the soluble ion concentrations of PM10 in the atmosphere in the Botanical Garden and beside the Fifth Ring Road have significant differences, while those of PM2.5 in the atmosphere had no significant differences. In different polluted regions there are significant adaptive changes to the leaf structures, and when compared with slightly polluted region, in the seriously polluted region the epidermis cells of the plant leaves shrinked, the surface textures of the leaves became rougher, and the stomas’ frequency and the pubescence length increased. Even though the plant leaves exposed to the seriously polluted region changed significantly, these plants can still grow normally and healthily. PMID:26287227

Simultaneous adsorption of CO2 and H2O under Mars-like conditions and application to the evolution of the Martian climate

NASA Technical Reports Server (NTRS)

Zent, Aaron, P.; Quinn, Richard C.

1995-01-01

The Martian regolith is the most substantial volatile reservoir on the planet; estimates of its adsorbed inventory have been based on simple measurements of the adsorption of either water or CO2 in isolation. Under some conditions, H2O can poison adsorbate surfaces, such that CO2 uptake is greatly reduced. We have made the first measurements of the simultaneous adsorption of CO2 and H2O under conditions appropriate to the Martian regolith and have found that at H2O monolayer coverage above about 0.5, CO2 begins to be displaced into the gas phase. We have developed an empirical expression that describes our co-adsorption data and have applied it to standard models of the Martian regolith. We find that currently, H2O does not substantially displace CO, implying that the adsorbate inventories previously derived may be accurate, not more than 3-4 kPa (30-40 mbar). No substantial increase in atmospheric pressure is predicted at higher obliquities because high-latitude ground ice buffers the partial pressure of H2O in the pores, preventing high monolayer coverages of H2O from displacing CO2. The peak atmospheric pressure at high obliquity does increase as the total inventory of exchangeable CO2 increases.

Experimental study on removals of SO2 and NOX using adsorption of activated carbon/microwave desorption.

PubMed

Ma, Shuang-Chen; Yao, Juan-Juan; Gao, Li; Ma, Xiao-Ying; Zhao, Yi

2012-09-01

Experimental studies on desulfurization and denitrification were carried out using activated carbon irradiated by microwave. The influences of the concentrations of nitric oxide (NO) and sulfur dioxide (SO 2 ), the flue gas coexisting compositions, on adsorption properties of activated carbon and efficiencies of desulfurization and denitrification were investigated. The results show that adsorption capacity and removal efficiency of NO decrease with the increasing of SO 2 concentrations in flue gas; adsorption capacity of NO increases slightly first and drops to 12.79 mg/g, and desulfurization efficiency descends with the increasing SO 2 concentrations. Adsorption capacity of SO 2 declines with the increasing of O 2 content in flue gas, but adsorption capacity of NO increases, and removal efficiencies of NO and SO 2 could be larger than 99%. Adsorption capacity of NO declines with the increase of moisture in the flue gas, but adsorption capacity of SO 2 increases and removal efficiencies of NO and SO 2 would be relatively stable. Adsorption capacities of both NO and SO 2 decrease with the increasing of CO 2 content; efficiencies of desulfurization and denitrification augment at the beginning stage, then start to fall when CO 2 content exceeds 12.4%. The mechanisms of this process are also discussed. [Box: see text].

Evaluation of phosphorus adsorption capacity of sesame straw biochar on aqueous solution: influence of activation methods and pyrolysis temperatures.

PubMed

Park, J H; Ok, Y S; Kim, S H; Cho, J S; Heo, J S; Delaune, R D; Seo, D C

2015-12-01

The phosphorus (P) adsorption characteristic of sesame straw biochar prepared with different activation agents and pyrolysis temperatures was evaluated. Between 0.109 and 0.300 mg L(-1) in the form of inorganic phosphate was released from raw sesame straw biochar in the first 1 h. The release of phosphate was significantly enhanced from 62.6 to 168.2 mg g(-1) as the pyrolysis temperature increased. Therefore, sesame straw biochar cannot be used as an adsorbent for P removal without change in the physicochemical characteristics. To increase the P adsorption of biochar in aqueous solution, various activation agents and pyrolysis temperatures were applied. The amount of P adsorbed from aqueous solution by biochar activated using different activation agents appeared in the order ZnCl2 (9.675 mg g(-1)) > MgO (8.669 mg g(-1)) ⋙ 0.1N-HCl > 0.1N-H2SO4 > K2SO4 ≥ KOH ≥ 0.1N-H3PO4, showing ZnCl2 to be the optimum activation agent. Higher P was adsorbed by the biochar activated using ZnCl2 under different pyrolysis temperatures in the order 600 °C > 500 °C > 400 °C > 300 °C. Finally, the amount of adsorbed P by activated biochar at different ratios of biochar to ZnCl2 appeared in the order 1:3 ≒ 1:1 > 3:1. As a result, the optimum ratio of biochar to ZnCl2 and pyrolysis temperature were found to be 1:1 and 600 °C for P adsorption, respectively. The maximum P adsorption capacity by activated biochar using ZnCl2 (15,460 mg kg(-1)) was higher than that of typical biochar, as determined by the Langmuir adsorption isotherm. Therefore, the ZnCl2 activation of sesame straw biochar was suitable for the preparation of activated biochar for P adsorption.

DFT study on stability and H2 adsorption activity of bimetallic Au79-nPdn (n = 1-55) clusters

NASA Astrophysics Data System (ADS)

Liu, Xuejing; Tian, Dongxu; Meng, Changgong

2013-03-01

The stability and H2 adsorption activity of bimetallic Au79-nPdn (n = 1-55) clusters were studied by density functional theory with GGA-PW91 functional. The stability order for four Pd substitution types is face > mid-edge > corner > edge, and the stability is improved with increasing Pd content. In contrast with the stability order, H2 adsorption activity is corner ≈ edge > mid-edge > face. The Au36Pd43 (3) with Au:Pd ≈ 1:1 ratio and twenty-four Pd substitutions at (1 1 1) facets and nineteen Pd substitutions at subshell sites shows high stability and H2 non-activated dissociation activity. The partial density of d-states and d band center revealed that the electronic properties are closely associated with the geometric characteristic and adsorption activity. Correlating the d band center ɛd and the adsorption energies, the ɛd order agrees with the adsorption activity that the Pd substitution at edge and corner sites are more active than at face and mid-edge sites.

Comparison of 4-chloro-2-nitrophenol adsorption on single-walled and multi-walled carbon nanotubes

PubMed Central

2012-01-01

The adsorption characteristics of 4-chloro-2-nitrophenol (4C2NP) onto single-walled and multi-walled carbon nanotubes (SWCNTs and MWCNTs) from aqueous solution were investigated with respect to the changes in the contact time, pH of solution, carbon nanotubes dosage and initial 4C2NP concentration. Experimental results showed that the adsorption efficiency of 4C2NP by carbon nanotubes (both of SWCNTs and MWCNTs) increased with increasing the initial 4C2NP concentration. The maximum adsorption took place in the pH range of 2–6. The linear correlation coefficients of different isotherm models were obtained. Results revealed that the Langmuir isotherm fitted the experimental data better than the others and based on the Langmuir model equation, maximum adsorption capacity of 4C2NP onto SWCNTs and MWCNTs were 1.44 and 4.42 mg/g, respectively. The observed changes in the standard Gibbs free energy, standard enthalpy and standard entropy showed that the adsorption of 4C2NP onto SWCNTs and MWCNTs is spontaneous and exothermic in the temperature range of 298–328 K. PMID:23369489

Drastic reduction of adsorption of CO and H2 on (111)-type Pd layers

NASA Technical Reports Server (NTRS)

Poppa, H.; Soria, F.

1983-01-01

Clean surfaces of (111)-type Pd layers, grown from the vapor phase on Mo(110) at room temperature, were used to study the adsorption of CO and H2 by temperature-programmed desorption, Auger electron spectroscopy, and low-energy electron diffraction. Mild annealing of the as-grown layers during a single desorption cycle (to about 600 K) drastically reduces the adsorption for both adsorbates. Low-dose argon-ion bombardment introduces surface imperfections which restore a high adsorption probability. The results are interpreted in terms of particular (111)-type surface structures that persist tp layer thicknesses of about four monolayers; the results raise questions with respect to the surface structure of supported thin epitaxial islands and particles of Pd and possibly also with respect to conventional methods of preparing bulk surfaces of Pd for adsorption studies.

Factors influencing antibiotics adsorption onto engineered adsorbents.

PubMed

Xia, Mingfang; Li, Aimin; Zhu, Zhaolian; Zhou, Qin; Yang, Weiben

2013-07-01

The study evaluated the adsorption of two antibiotics by four engineered adsorbents (hypercrosslinked resin MN-202, macroporous resin XAD-4, activated carbon F-400, and multi-walled carbon nanotubes (MWCNT)) from aqueous solutions. The dynamic results demonstrated the dominant influence of pore size in adsorption. The adsorption amounts of antibiotics on XAD-4 were attributed to the hydrophobic effect, whereas steric hindrance or micropore-filling played a main role in the adsorption of antibiotics by F-400 because of its high microporosity. Aside from F-400, similar patterns of pH-dependent adsorption were observed, implying the importance of antibiotic molecular forms to the adsorption process for adsorbents. Increasing the ionic concentration with CaC12 produced particular adsorption characteristics on MWCNT at pH 2.0 and F-400 at pH 8.0, which were attributed to the highly available contact surfaces and molecular sieving, respectively. Its hybrid characteristics incorporating a considerable portion of mesopores and micropores made hypercross linked MN-202 a superior antibiotic adsorbent with high adsorption capacity. Furthermore, the adsorption capacity of MWCNT on the basis of surface area was more advantageous than that of the other adsorbents because MWCNT has a much more compact molecular arrangement.

Effect of pH, Dosage and Concentration on the Adsorption of Congo Red onto Untreated and Treated Aluminium Dross

NASA Astrophysics Data System (ADS)

Zakaria Mohamad Zulfika, Hazielim B.; Baini, Rubiyah; Zauzi, Nur Syuhada Ahmad

2017-06-01

The adsorption of congo red onto aluminium dross was studied in batch process. The objective of this study is to adsorption capacity between untreated and treated aluminium dross in the removal of congo red. Aluminium dross was leached with 250 ml of 1% of NaOH and and precipitated with 30% H2O2. The treated aluminium dross being calcined at 600°C for 3 hours. The surface area for untreated and treated aluminium dross was 10.06 m2/g and 79.80 m2/g respectively. Then the adsorption process was carried out on an orbital shaker at 200 rpm for 4 hours. In the effect of pH, it was found that untreated removes more congo red compared to the treated while in the effect of concentration solution and dosage of adsorbent, treated aluminium dross removes more congo red. In conclusion, this adsorbent was found to be effective and economically viable in the removal of congo red in waste water treatment.

Study on adsorption properties and mechanism of Pb2+ with different carbon based adsorbents.

PubMed

Song, Min; Wei, Yuexing; Cai, Shipan; Yu, Lei; Zhong, Zhaoping; Jin, Baosheng

2018-03-15

Different activated carbon materials are prepared from a series of solid wastes (sawdust, acrylic fabric, tire powder and rice husk) by combination of the KOH activation method and steam activation method. The influences of several parameters such as pH, contact time, adsorbent dosage and temperature on adsorption performance of Pb 2+ with those different carbon adsorbents are investigated. The results demonstrate that C rice husk performance well in the adsorption process. In the following, the C rice husk is used to explain the adsorption mechanism of Pb 2+ by SEM-EDS, FT-IR and XPS. The results illustrate that the surface oxygen-containing functional groups such as carboxyl, lactone group, phenolic hydroxyl and other alkaline metal ions like Na + and K + have significant effect on the adsorption process. A reasonable mechanism of Pb 2+ adsorption is proposed that the ion exchange play key roles in the adsorption process. In addition, the effects of Cu 2+ , Zn 2+ on the Pb 2+ adsorption capacity with the four carbon adsorbents are also studied and the results demonstrate that other heavy metals play positive effects on the adsorption of Pb 2+ . Copyright © 2017 Elsevier B.V. All rights reserved.

Nuclear quantum effects on adsorption of H 2 and isotopologues on metal ions

DOE PAGES

Savchenko, Ievgeniia; Gu, Bing; Heine, Thomas; ...

2017-01-03

The nuclear quantum effects on the zero-point energy (ZPE), influencing adsorption of Hmore » $$_2$$ and isotopologues on metal ions, are examined in this study using normal mode analysis of ab initio electronic structure results for complexes with 17 metal cations. To estimate for the anharmonicity, a nuclear wavepacket dynamics on the ground state electronic potential energy surfaces (PES) have been employed for complexes of Li$^+$ and Cu$$^{+2}$$ with H$$_2$$, D$$_2$$, HD. The dynamics analysis shows that incorporation of the PES anharmonicity changes the ZPE by up to 9%. Finally, the lightest metallic nuclei, Li and Be, are found to be the most 'quantum'. The largest selectivity in adsorption is predicted for Cu, Ni and Co ions.« less

Adsorption of Reactive Red M-2BE dye from water solutions by multi-walled carbon nanotubes and activated carbon.

PubMed

Machado, Fernando M; Bergmann, Carlos P; Fernandes, Thais H M; Lima, Eder C; Royer, Betina; Calvete, Tatiana; Fagan, Solange B

2011-09-15

Multi-walled carbon nanotubes and powdered activated carbon were used as adsorbents for the successful removal of Reactive Red M-2BE textile dye from aqueous solutions. The adsorbents were characterised by infrared spectroscopy, N(2) adsorption/desorption isotherms and scanning electron microscopy. The effects of pH, shaking time and temperature on adsorption capacity were studied. In the acidic pH region (pH 2.0), the adsorption of the dye was favourable using both adsorbents. The contact time to obtain equilibrium at 298K was fixed at 1h for both adsorbents. The activation energy of the adsorption process was evaluated from 298 to 323K for both adsorbents. The Avrami fractional-order kinetic model provided the best fit to the experimental data compared with pseudo-first-order or pseudo-second-order kinetic adsorption models. For Reactive Red M-2BE dye, the equilibrium data were best fitted to the Liu isotherm model. Simulated dyehouse effluents were used to check the applicability of the proposed adsorbents for effluent treatment. Copyright © 2011 Elsevier B.V. All rights reserved.

Facile Preparation of Magnetic Graphene Oxide and Attapulgite Composite Adsorbent for the Adsorption of Ni (II)

NASA Astrophysics Data System (ADS)

Bigui, Wei; Xiaofei, Zhu; Xiabing, Cheng

2017-12-01

Graphene oxide (GO) is an excellent absorbent for heavy ion from wastewater, but it is hard to separate from water. To improve the adsorption capacity and separation performance of GO to nickel-containing wastewater, a composite magnetic GO-ATP adsorbent (MGA) was prepared by magnetizing GO and attapulgite (ATP) using ferroferric oxide and then carrying out hydrothermal reaction. The adsorption capacity and mechanism of MGA were investigated based on Ni2+ as targeted pollutant. Experimental results showed that the pH value significantly affects the removal rate of Ni2+, which is mainly due to that OH- in wastewater reacts with Ni2+, resulting in sediment that leads to the increase of removal rate. MGA can achieve max adsorption capacity of Ni2+ to 190.8 mg/g at pH = 5, and the adsorption process was mainly determined by chemical adsorption, which was in line with pseudo-secondary dynamics model. The adsorption was basically homogeneous monolayer adsorption with heat release, which was more agree with Langmuir adsorption isotherm equation. the adsorption process of Ni2+ by MGA. The adsorption process was a spontaneous process and an exothermic reaction. It can be confirmed that the prepared MGA adsorbent can realize slurry separation using magnetic separation principle and has high adsorption capacity to Ni2+.

Research of Co(II) Adsorption on Silica Gel Grafted with Dithiocarbamate (DTC-SiO2) in Aqueous Solution

NASA Astrophysics Data System (ADS)

Yao, Qingxu; Xu, Peng; Huo, Yonggang; Shang, Aiguo; Yu, Fengmei

2018-01-01

Dithiocarbamate grafted silica gel (DTC-SiO2) was prepared following two simple reaction steps. The properties of the composite were characterized by FTIR, SEM and element analysis. Its ability to remove Co2+ ions in aqueous solution with low concentration was also studied by static adsorption experiments. The effects of pH value in solution, contact time and temperature were investigated. The results show that the DTC-SiO2 exhibits excellent adsorption property for Co2+. The adsorption kinetics could be well described by pseudo-second-order model and the adsorption isotherms could be depicted by both Freundlich and Dubinin-Radushkevich models. The adsorption process belongs to chemisorption. The slightly influence of common interfering metal ions (Na+, K+, Ca2+ and Mg2+) on the adsorption capacity revealing the synthesized DTC-SiO2 performs excellent selective adsorption to Co2+.

Sonochemical surface functionalization of exfoliated LDH: Effect on textural properties, CO2 adsorption, cyclic regeneration capacities and subsequent gas uptake for simultaneous methanol synthesis.

PubMed

Ezeh, Collins I; Huang, Xiani; Yang, Xiaogang; Sun, Cheng-Gong; Wang, Jiawei

2017-11-01

To improve CO 2 adsorption, amine modified Layered double hydroxide (LDH) were prepared via a two stage process, SDS/APTS intercalation was supported by ultrasonic irradiation and then followed by MEA extraction. The prepared samples were characterised using Scanning electron microscope-Energy dispersive X-ray spectroscopy (SEM-EDX), X-ray Photoelectron Spectroscopy (XPS), X-ray diffraction (XRD), Temperature Programmed Desorption (TPD), Brunauer-Emmett-Teller (BET), and Thermogravimetric analysis (TGA), respectively. The characterisation results were compared with those obtained using the conventional preparation method with consideration to the effect of sonochemical functionalization on textural properties, adsorption capacity, regeneration and lifetime of the LDH adsorbent. It is found that LDHs prepared by sonochemical modification had improved pore structure and CO 2 adsorption capacity, depending on sonic intensity. This is attributed to the enhanced deprotonation of activated amino functional groups via the sonochemical process. Subsequently, this improved the amine loading and effective amine efficiency by 60% of the conventional. In addition, the sonochemical process improved the thermal stability of the adsorbent and also, reduced the irreversible CO 2 uptake, CUirrev, from 0.18mmol/g to 0.03mmol/g. Subsequently, improving the lifetime and ease of regenerating the adsorbent respectively. This is authenticated by subjecting the prepared adsorbents to series of thermal swing adsorption (TSA) cycles until its adsorption capacity goes below 60% of the original CO 2 uptake. While the conventional adsorbent underwent a 10 TSA cycles before breaking down, the sonochemically functionalized LDH went further than 30 TSA cycles. Copyright © 2017 Elsevier B.V. All rights reserved.

Adsorption behaviour of methylene blue onto Jordanian diatomite: a kinetic study.

PubMed

Al-Ghouti, Mohammad A; Khraisheh, Majeda A M; Ahmad, Mohammad N M; Allen, Stephen

2009-06-15

The effect of initial concentration, particle size, mass of the adsorbent, pH and agitation speed on adsorption behaviour of methylene blue (MB) onto Jordanian diatomite has been investigated. The maximum adsorption capacity, q, increased from 75 to 105 mg/g when pH of the dye solution increased from 4 to 11. It is clear that the ionisable charge sites on the diatomite surface increased when pH increased from 4 to 11. When the solution pH was above the pH(ZPC), the diatomite surface had a negative charge, while at low pH (pH<5.4) it has a positive charge. The adsorption capacity increased from 88.6 to 143.3mg/g as the initial MB concentrations increased from 89.6 to 225.2mg/dm(3). The experimental results were also applied to the pseudo-first and -second order kinetic models. It is noticed that the whole experimental data of MB adsorption onto diatomite did not follow the pseudo-first order model and had low correlation coefficients (R(2)<0.3). The calculated adsorption capacity, q(e,cal), values obtained from pseudo-first order kinetic model did not give acceptable values, q(e,exp.) The maximum uptake capacity seems to be independent of the particle size of the diatomite when the particle size distribution is less than 250-500 microm. While at larger particle size 250-500 microm, the maximum uptake capacity was dependent on the particle size. It would imply that the MB adsorption is limited by the external surface and that intraparticle diffusion is reduced. The effect of the agitation speeds on the removal of MB from aqueous solution using the diatomite is quite low. The MB removal increased from 43 to 100% when mass of the diatomite increased from 0.3 to 1.7 g.

An adsorbent with a high adsorption capacity obtained from the cellulose sludge of industrial residues.

PubMed

Orlandi, Géssica; Cavasotto, Jéssica; Machado, Francisco R S; Colpani, Gustavo L; Magro, Jacir Dal; Dalcanton, Francieli; Mello, Josiane M M; Fiori, Márcio A

2017-02-01

One of the major problems in effluent treatment plants of the cellulose and paper industry is the large amount of residual sludge generated. Therefore, this industry is trying to develop new methods to treat such residues and to use them as new products, such as adsorbents. In this regard, the objective of this work was to develop an adsorbent using the raw activated sludge generated by the cellulose and paper industry. The activated cellulose sludge, after being dried, was chemically activated with 42.5% (v/v) phosphoric acid at 85 °C for 1 h and was charred at 500 °C, 600 °C and 700 °C for 2 h. The efficiency of the obtained adsorbent materials was evaluated using kinetic tests with methylene blue solutions. Using the adsorption kinetics, it was verified that the three adsorbents showed the capacity to adsorb dye, and the adsorbent obtained at a temperature of 600 °C showed the highest adsorption capacity of 107.1 mg g -1 . The kinetic model that best fit the experimental data was pseudo-second order. The Langmuir-Freudlich isotherm adequately described the experimental data. As a result, the cellulose sludge generated by the cellulose and paper industries could be used as an adsorbent. Copyright © 2016 Elsevier Ltd. All rights reserved.

Characteristics of storage related capacity loss in Ni/H2 cells

NASA Technical Reports Server (NTRS)

Vaidyanathan, Hari

1993-01-01

The changes in the capacity, voltage and pressure profile of flight configuration Ni/H2 cells when they are stored for extended periods is examined. The Ni/H2 cells exhibit capacity fade phenomenon regardless of their design when they are stored at room temperature. Capacity loss also occurs if old cells (5 years old) are stored in a very low rate trickle charge (C/200 rate) condition. A periodic recharge technique leads to pressure rise in the cells. Conventional trickle charge (C/100 rate) helps in minimizing or eliminating the second plateau which is one of the characteristics of the capacity fade phenomenon.

Adsorption and reaction of CO and H2O on WC(0001) surface: A first-principles investigation

NASA Astrophysics Data System (ADS)

Tong, Yu-Jhe; Wu, Shiuan-Yau; Chen, Hsin-Tsung

2018-01-01

We have performed a spin-polarized density functional theory (DFT) study for understanding the detailed reaction mechanism of CO and H2O on WC (0001) surface. The adsorption properties and vibrational frequencies of H2O, OH, O, H, CO and CO2 on the WC (0001) surface were illustrated. These results are well in consistent with the experimental observations studied by temperature-programmed desorption (TPD) and high-resolution electron energy loss spectroscopy (HREELS). Based on the adsorption results, potential energy profiles of H2O and OH dehydrogenation and HCO, COH, COOH, and CO2 formation on the WC (0001) surface were predicted. The calculation results demonstrated that the WC (0001) surface as Fe (110) surface exhibits significantly reaction activity toward the dehydrogenation of H2O and OH but less activity toward the formation of HCO, COH, COOH and CO2 compared to the Cu (111) and Pt (111) surfaces.

Functionalized Sugarcane Bagasse for U(VI) Adsorption from Acid and Alkaline Conditions.

PubMed

Su, Shouzheng; Liu, Qi; Liu, Jingyuan; Zhang, Hongsen; Li, Rumin; Jing, Xiaoyan; Wang, Jun

2018-01-15

The highly efficient removal of uranium from mine tailings effluent, radioactive wastewater and enrichment from seawater is of great significance for the development of nuclear industry. In this work, we prepared an efficient U(VI) adsorbent by EDTA modified sugarcane bagasse (MESB) with a simple process. The prepared adsorbent preserves high adsorptive capacity for UO 2 2+ (pH 3.0) and uranyl complexes, such as UO 2 (OH) + , (UO 2 ) 2 (OH) 2 2+ and (UO 2 ) 3 (OH) 5 + (pH 4.0 and pH 5.0) and good repeatability in acidic environment. The maximum adsorption capacity for U(VI) at pH 3.0, 4.0 and 5.0 is 578.0, 925.9 and 1394.1 mg/g and the adsorption capacity loss is only 7% after five cycles. With the pH from 3.0 to 5.0, the inhibitive effects of Na + and K + decreased but increased of Mg 2+ and Ca 2+ . MESB also exhibits good adsorption for [UO 2 (CO 3 ) 3 ] 4- at pH 8.3 from 10 mg/L to 3.3 μg/L. Moreover, MESB could effectively extract U(VI) from simulated seawater in the presence of other metals ions. This work provided a general and efficient uranyl enriched material for nuclear industry.

Preparation of activated carbon from a renewable bio-plant of Euphorbia rigida by H 2SO 4 activation and its adsorption behavior in aqueous solutions

NASA Astrophysics Data System (ADS)

Gerçel, Özgül; Özcan, Adnan; Özcan, A. Safa; Gerçel, H. Ferdi

2007-03-01

The use of activated carbon obtained from Euphorbia rigida for the removal of a basic textile dye, which is methylene blue, from aqueous solutions at various contact times, pHs and temperatures was investigated. The plant material was chemically modified with H 2SO 4. The surface area of chemically modified activated carbon was 741.2 m 2 g -1. The surface characterization of both plant- and activated carbon was undertaken using FTIR spectroscopic technique. The adsorption process attains equilibrium within 60 min. The experimental data indicated that the adsorption isotherms are well described by the Langmuir equilibrium isotherm equation and the calculated adsorption capacity of activated carbon was 114.45 mg g -1 at 40° C. The adsorption kinetics of methylene blue obeys the pseudo-second-order kinetic model and also followed by the intraparticle diffusion model up to 60 min. The thermodynamic parameters such as Δ G°, Δ H° and Δ S° were calculated to estimate the nature of adsorption. The activation energy of the system was calculated as 55.51 kJ mol -1. According to these results, prepared activated carbon could be used as a low-cost adsorbent to compare with the commercial activated carbon for the removal textile dyes from textile wastewater processes.

Comparisons of multilayer H2O adsorption onto the (110) surfaces of alpha-TiO2 and SnO2 as calculated with density functional theory.

PubMed

Bandura, Andrei V; Kubicki, James D; Sofo, Jorge O

2008-09-18

Mono- and bilayer adsorption of H2O molecules on TiO2 and SnO 2 (110) surfaces has been investigated using static planewave density functional theory (PW DFT) simulations. Potential energies and structures were calculated for the associative, mixed, and dissociative adsorption states. The DOS of the bare and hydrated surfaces has been used for the analysis of the difference between the H2O interaction with TiO2 and SnO 2 surfaces. The important role of the bridging oxygen in the H2O dissociation process is discussed. The influence of the second layer of H2O molecules on relaxation of the surface atoms was estimated.

Effects of decreasing activated carbon particle diameter from 30 μm to 140 nm on equilibrium adsorption capacity.

PubMed

Pan, Long; Nishimura, Yuki; Takaesu, Hideki; Matsui, Yoshihiko; Matsushita, Taku; Shirasaki, Nobutaka

2017-11-01

The capacity of activated carbon particles with median diameters (D50s) of >∼1 μm for adsorption of hydrophobic micropollutants such as 2-methylisolborneol (MIB) increases with decreasing particle size because the pollutants are adsorbed mostly on the exterior (shell) of the particles owing to the limited diffusion penetration depth. However, particles with D50s of <1 μm have not been thoroughly investigated. Here, we prepared particles with D50s of ∼30 μm-∼140 nm and evaluated their adsorption capacities for MIB and several other environmentally relevant adsorbates. The adsorption capacities for low-molecular-weight adsorbates, including MIB, deceased with decreasing particle size for D50s of less than a few micrometers, whereas adsorption capacities increased with decreasing particle size for larger particles. The oxygen content of the particles increased substantially with decreasing particle size for D50s of less than a few micrometers, and oxygen content was negatively correlated with adsorption capacity. The decrease in adsorption capacity with decreasing particle size for the smaller particles was due to particle oxidation during the micromilling procedure used to decrease D50 to ∼140 nm. When oxidation was partially inhibited, the MIB adsorption capacity decrease was attenuated. For high-molecular-weight adsorbates, adsorption capacity increased with decreasing particle size over the entire range of tested particle sizes, even though particle oxygen content increased with decreasing particle size. Copyright © 2017 Elsevier Ltd. All rights reserved.

Hierarchical flower-like nickel(II) oxide microspheres with high adsorption capacity of Congo red in water.

PubMed

Zheng, Yingqiu; Zhu, Bicheng; Chen, Hua; You, Wei; Jiang, Chuanjia; Yu, Jiaguo

2017-10-15

Monodispersed hierarchical flower-like nickel(II) oxide (NiO) microspheres were fabricated by a facile solvothermal reaction with the assistance of ethanolamine and a subsequent calcination process. The as-synthesized samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, nitrogen adsorption-desorption isotherms, zeta potential measurement and Fourier transform infrared spectroscopy. Flower-like nickel(II) hydroxide microspheres with uniform diameters of approximate 6.3μm were obtained after the solvothermal reaction. After heat treatment at 350°C, the crystal phase transformed to NiO, but the hierarchical porous structure was maintained. The as-prepared microspheres exhibited outstanding performance for the adsorption of Congo red (CR), an anionic organic dye, from aqueous solution at circumneutral pH. The pseudo-second-order model can make a good description of the adsorption kinetics, while Langmuir model could well express the adsorption isotherms, with calculated maximum CR adsorption capacity of 534.8 and 384.6mgg -1 , respectively, for NiO and Ni(OH) 2 . The adsorption mechanism of CR onto the as-synthesized samples can be mainly attributed to electrostatic interaction between the positively charged sample surface and the anionic CR molecules. The as-prepared NiO microspheres are a promising adsorbent for CR removal in water treatment. Copyright © 2017 Elsevier Inc. All rights reserved.

Uniform Cu{sub 2}Cl(OH){sub 3} hierarchical microspheres: A novel adsorbent for methylene blue adsorptive removal from aqueous solution

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

Wei, Wei; Gao, Pin; Xie, Jimin, E-mail: xiejm391@sohu.com

2013-08-15

Using the solution phase method without any surfactants or templates, the hierarchical of Cu{sub 2}Cl(OH){sub 3} microspheres were synthesized by freeze drying. The size and surface area of the microspheres are ca. 1–2 µm and 76.61 m{sup 2} g{sup −1}, respectively. A possible formation mechanism is presented based on the experimental results. Methylene blue was chosen to investigate the adsorption capacity of the as-prepared adsorbent. The effects of various experimental parameters, such as pH, initial dye concentration, and contact time were investigated. The results showed that the dye removal increased with the increasing in the initial concentration of the dyemore » and also increased in the amount of microspheres used and initial pH. Adsorption data fitted well with the Freundlich adsorption isotherm. The thermodynamic analysis presented the exothermic, spontaneous and more ordered arrangement process. The microspheres could be employed effective for removal of dyes from aqueous solution. - Graphical abstract: The single-crystalline hierarchical Cu{sub 2}Cl(OH){sub 3} spheres can be prepared for the first time by using a template-free process through freeze-drying. Meanwhile, the hierarchical spheres exhibited high adsorption capacity to methylene blue. Display Omitted - Highlights: • Cu{sub 2}Cl(OH){sub 3} microspheres were successfully synthesized through a freeze drying process. • A possible formation mechanism of hierarchical microspheres was presented. • The Cu{sub 2}Cl(OH){sub 3} microspheres have high methylene blue adsorption capacity. • Methylene blue adsorption is a spontaneous and exothermic process. • The adsorption mechanism of microspheres onto dye was proposed in detail.« less

Adsorption of emerging contaminant metformin using graphene oxide.

PubMed

Zhu, Shuai; Liu, Yun-Guo; Liu, Shao-Bo; Zeng, Guang-Ming; Jiang, Lu-Hua; Tan, Xiao-Fei; Zhou, Lu; Zeng, Wei; Li, Ting-Ting; Yang, Chun-Ping

2017-07-01

The occurrence of emerging contaminants in our water resources poses potential threats to the livings. Due to the poor treatment in wastewater management, treatment technologies are needed to effectively remove these products for living organism safety. In this study, Graphene oxide (GO) was tested for the first time for its capacity to remove a kind of emerging wastewater contaminants, metformin. The research was conducted by using a series of systematic adsorption and kinetic experiments. The results indicated that GO could rapidly and efficiently reduce the concentration of metformin, which could provide a solution in handling this problem. The uptake of metformin on the graphene oxide was strongly dependent on temperature, pH, ionic strength, and background electrolyte. The adsorption kinetic experiments revealed that almost 80% removal of metformin was achieved within 20 min for all the doses studied, corresponding to the relatively high k 1 (0.232 min -1 ) and k 2 (0.007 g mg -1  min -1 ) values in the kinetic models. It indicated that the highest adsorption capacity in the investigated range (q m ) of GO for metformin was at pH 6.0 and 288 K. Thermodynamic study indicated that the adsorption was a spontaneous (ΔG 0  < 0) and exothermic (ΔH 0  < 0) process. The adsorption of metformin increased when the pH values changed from 4.0 to 6.0, and decreased adsorption were observed at pH 6.0-11.0. GO still exhibited excellent adsorption capacity after several desorption/adsorption cycles. Besides, both so-called π-π interactions and hydrogen bonds might be mainly responsible for the adsorption of metformin onto GO. Copyright © 2017 Elsevier Ltd. All rights reserved.

Synthesis and Electrospraying of Nanoscale MOF (Metal Organic Framework) for High-Performance CO2 Adsorption Membrane

NASA Astrophysics Data System (ADS)

Wahiduzzaman; Allmond, Kelsey; Stone, John; Harp, Spencer; Mujibur, Khan

2017-01-01

We report the sonochemical synthesis of MOF (metal organic framework) nanoparticles of 30-200 nm in size and electrospraying of those particles on electrospun nanofibers to process a MOF-attached nanofibrous membrane. This membrane displayed significant selectivity towards CO2 and capacity of adsorbing with 4000-5000 ppm difference from a mixed gas flow of 1% CO2 and 99% N2. Applying ultrasonic waves during the MOF synthesis offered rapid dispersion and formation of crystalline MOF nanoparticles in room temperature. The MOF nanoparticles of 100-200 nm in size displayed higher surface area and adsorption capacity comparing to that of 30-60 nm in size. Nanofibrous membrane was produced by electrospinning of MOF blended PAN solution followed by electrospraying of additional MOF nanoparticles. This yielded uniform MOF deposition on nanofibers, occurred due to electrostatic attraction between highly charged nanoparticles and conductive nanofibers. A test bench for real-time CO2 adsorption at room temperature was built with non-dispersive Infrared (NDIR) CO2 sensors. Comparative tests were performed on the membrane to investigate its enhanced adsorption capacity. Three layers of the as-produced membranes displayed CO2 adsorption for approximately 2 h. Thermogravimetric analysis (TGA) of the membrane showed the thermal stability of the MOF and PAN up to 290 and 425 °C, respectively.

Synthesis and Electrospraying of Nanoscale MOF (Metal Organic Framework) for High-Performance CO2 Adsorption Membrane.

PubMed

Wahiduzzaman; Allmond, Kelsey; Stone, John; Harp, Spencer; Mujibur, Khan

2017-12-01

We report the sonochemical synthesis of MOF (metal organic framework) nanoparticles of 30-200 nm in size and electrospraying of those particles on electrospun nanofibers to process a MOF-attached nanofibrous membrane. This membrane displayed significant selectivity towards CO 2 and capacity of adsorbing with 4000-5000 ppm difference from a mixed gas flow of 1% CO 2 and 99% N 2 . Applying ultrasonic waves during the MOF synthesis offered rapid dispersion and formation of crystalline MOF nanoparticles in room temperature. The MOF nanoparticles of 100-200 nm in size displayed higher surface area and adsorption capacity comparing to that of 30-60 nm in size. Nanofibrous membrane was produced by electrospinning of MOF blended PAN solution followed by electrospraying of additional MOF nanoparticles. This yielded uniform MOF deposition on nanofibers, occurred due to electrostatic attraction between highly charged nanoparticles and conductive nanofibers. A test bench for real-time CO 2 adsorption at room temperature was built with non-dispersive Infrared (NDIR) CO 2 sensors. Comparative tests were performed on the membrane to investigate its enhanced adsorption capacity. Three layers of the as-produced membranes displayed CO 2 adsorption for approximately 2 h. Thermogravimetric analysis (TGA) of the membrane showed the thermal stability of the MOF and PAN up to 290 and 425 °C, respectively.

Study on adsorption of rhodamine B onto Beta zeolites by tuning SiO2/Al2O3 ratio.

PubMed

Cheng, Zhi-Lin; Li, Yan-Xiang; Liu, Zan

2018-02-01

The exploration of the relationship between zeolite composition and adsorption performance favored to facilitate its better application in removal of the hazardous substances from water. The adsorption capacity of rhodamine B (RB) onto Beta zeolite from aqueous solution was reported. The relationship between SiO 2 /Al 2 O 3 ratio and adsorption capacity of Beta zeolite for RB was explored. The structure and physical properties of Beta zeolites with various SiO 2 /Al 2 O 3 ratios were determined by XRD, FTIR, TEM, BET, UV-vis and so on characterizations. The adsorption behavior of rhodamine B onto Beta zeolite matched to Langmuir adsorption isotherm and more suitable description for the adsorption kinetics was a pseudo-second-order reaction model. The maximum adsorption capacity of the as-prepared Beta zeolite with SiO 2 /Al 2 O 3 = 18.4 was up to 27.97mg/g. Copyright © 2017 Elsevier Inc. All rights reserved.

The Adsorption Capacity of GONs/CMC/Fe3O4 Magnetic Composite Microspheres and Applications for Purifying Dye Wastewater

PubMed Central

Lv, Shenghua; Zhu, Linlin; Li, Ying; Jia, Chunmao; Sun, Shiyu

2017-01-01

Graphene oxide nanosheets (GONs)/carboxymethyl chitosan (CMC)/Fe3O4 magnetic composite microspheres (MCMs) were prepared by enclosing Fe3O4 particles with CMC and GONs in turn. The microstructures of GONs and GONs/CMC/Fe3O4 MCMs were characterized by FTIR, XRD, TEM, and SEM. The effects of GON content, pH value, and adsorption time on the adsorption capacity of the MCMs were investigated. The results show that the GONs/CMC/Fe3O4 MCMs have a greater specific surface area and a strong adsorption capacity for dye wastewater. Meanwhile, the adsorption mechanism was investigated, and the results accorded with the pseudo-second-order kinetic model and the Freundlich isotherm model. The search results indicate that GONs/CMC/Fe3O4 MCMs can be used to purify dye wastewater and has an important potential use in the practical purification of dye wastewater. PMID:28772419

Investigation of protein adsorption performance of Ni2+-attached diatomite particles embedded in composite monolithic cryogels.

PubMed

Ünlü, Nuri; Ceylan, Şeyda; Erzengin, Mahmut; Odabaşı, Mehmet

2011-08-01

As a low-cost natural adsorbent, diatomite (DA) (2 μm) has several advantages including high surface area, chemical reactivity, hydrophilicity and lack of toxicity. In this study, the protein adsorption performance of supermacroporous composite cryogels embedded with Ni(2+)-attached DA particles (Ni(2+)-ADAPs) was investigated. Supermacroporous poly(2-hydroxyethyl methacrylate) (PHEMA)-based monolithic composite cryogel column embedded with Ni(2+)-ADAPs was prepared by radical cryo-copolymerization of 2-hydroxyethyl methacrylate (HEMA) with N,N'-methylene-bis-acrylamide (MBAAm) as cross-linker directly in a plastic syringe for affinity purification of human serum albumin (HSA) both from aqueous solutions and human serum. The chemical composition and surface area of DA was determined by XRF and BET method, respectively. The characterization of composite cryogel was investigated by SEM. The effect of pH, and embedded Ni(2+)-ADAPs amount, initial HSA concentration, temperature and flow rate on adsorption were studied. The maximum amount of HSA adsorption from aqueous solution at pH 8.0 phosphate buffer was very high (485.15 mg/g DA). It was observed that HSA could be repeatedly adsorbed and desorbed to the embedded Ni(2+)-ADAPs in poly(2-hydroxyethyl methacrylate) composite cryogel without significant loss of adsorption capacity. The efficiency of albumin adsorption from human serum before and after albumin adsorption was also investigated with SDS-PAGE analyses. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Physicochemical factors affecting ethanol adsorption by activated carbon.

PubMed

Bradley, K J; Hamdy, M K; Toledo, R T

1987-03-01

Powder and granular activated charcoal were evaluated for ethanol adsorptivity from aqueous mixtures using an adsorption isotherm. Ethanol adsorption capacity was more pronounced at 25 degrees C as compared to 5, 15, and 40 degrees C. When pH of the ethanol-buffer mixture (0.09 ionic strength) was changed from acidic (2.3) to neutral and then to alkaline (11.2), ethanol adsorption was decreased. Increasing ionic strength of the ethanol-buffer mixtures from 0.05 to 0.09 enhanced ethanol adsorption but a further increase to 0.14 showed no significant effect. Ethanol adsorption was more efficient from an aqueous ethanol mixture as compared to semidefined and nondefined fermentation worts, respectively. Heating granular charcoal to 400 degrees C for 1 h and 600 degrees C for 3 h in N(2) increased ethanol adsorptivity and heating to 1000 degrees C (1 h) in CO(2) decreased it when ethanol was removed from dilute solutions by simple pass adsorption in a carbon packed column. Granular charcoal was superior to powdered charcoal and an inverse relationship was noted between the weight of the granular carbon bed in the column and ethanol adsorbed/g carbon. Decreasing the column feed flow rate from 7.5 to 2.0 L aqueous ethanol/min increased the adsorption rate.

Adsorptive Removal of Nitrate from Aqueous Solution Using Nitrogen Doped Activated Carbon.

PubMed

Machida, Motoi; Goto, Tatsuru; Amano, Yoshimasa; Iida, Tatsuya

2016-01-01

Activated carbon (AC) has been widely applied for adsorptive removal of organic contaminants from aqueous phase, but not for ionic pollutants. In this study, nitrogen doped AC was prepared to increase the adsorption capacity of nitrate from water. AC was oxidized with (NH 4 ) 2 S 2 O 8 solution to maximize oxygen content for the first step, and then NH 3 gas treatment was carried out at 950°C to aim at forming quaternary nitrogen (N-Q) species on AC surface (Ox-9.5AG). Influence of solution pH was examined so as to elucidate the relationship between surface charge and adsorption amounts of nitrate. The results showed that Ox-9.5AG exhibited about twice higher adsorption capacity than non-treatment AC at any initial nitrate concentration and any equilibrium solution pH (pH e ) investigated. The more decrease in pH e value, the more adsorption amount of negatively charged nitrate ion, because the surface charge of AC and Ox-9.5AG could become more positive in acidic solution. The oxidation and consecutive ammonia treatments lead to increase in nitrogen content from 0.35 to 6.4% and decrease in the pH of the point of zero charge (pH pzc ) from 7.1 to 4.0 implying that positively charged N-Q of a Lewis acid was created on the surface of Ox-9.5AG. Based on a Langmuir data analysis, maximum adsorption capacity attained 0.5-0.6 mmol/g of nitrate and adsorption affinity was 3.5-4.0 L/mmol at pH e 2.5 for Ox-9.5AG.

Effective Adsorption/Reduction of Cr(VI) Oxyanion by Halloysite@Polyaniline Hybrid Nanotubes.

PubMed

Zhou, Tianzhu; Li, Cuiping; Jin, Huiling; Lian, Yangyang; Han, Wenmei

2017-02-22

Halloysite@polyaniline (HA@PANI) hybrid nanotubes are synthesized by the in situ chemical polymerization of aniline on halloysite clay nanotubes. By facilely tuning the dopant acid, pH, and apparent weight proportion for aniline (ANI) and halloysite (HA) nanotubes in the synthesis process, PANI with tuned oxidation state, doping extent, and content are in situ growing on halloysite nanotubes. The reaction system's acidity is tuned by dopant acid, such as HCl, H 2 SO 4 , HNO 3 , and H 3 PO 4 . The adsorption result shows the fabricated HA@PANI hybrid nanotubes can effectively adsorb Cr(VI) oxyanion and the adsorption ability changes according to the dopant acid, pH, and apparent weight proportion for ANI and HA in the synthesis process. Among them, the HA@PANI fabricated with HCl as dopant acid tuning the pH at 0.5 and 204% apparent weight proportion for ANI and HA (HP/0.5/204%-HCl) shows the highest adsorption capacity. The adsorption capacity is in accordance well with the doping extent of PANI in HA@PANI. Furthermore, when HP/0.5/204%-HCl is redoped with HNO 3 , H 2 SO 4 , and H 3 PO 4 , the adsorption capacity declines, implying the dopant acid in the process of redoping exhibits a marked effect on Cr(VI) oxyanion adsorption for the HA@PANI hybrid nanotubes. HP/0.5/204%-HCl and HP/0.5/204%-H 3 PO 4 have demonstrated good regenerability with an above 80% removal ratio after four cycles. Moreover, the HA@PANI adsorbent has better sedimentation ability than that of pure PANI. The adsorption behavior is in good agreement with Langmuir and pseudo second-order equations, indicating the adsorption of HA@PANI for Cr(VI) oxyanion is chemical adsorption. FT-IR and XPS of HA@PANI after Cr(VI) oxyanion adsorption indicate that the doped amine/imine groups (-NH + /═N + - groups) are the main adsorption sites for the removal of Cr(VI) oxyanion by electrostatic adsorption and reduction of the adsorbed Cr (VI) oxyanion to Cr(III) simultaneously.

Adsorption of cadmium by sulphur dioxide treated activated carbon.

PubMed

Macías-García, A; Gómez-Serrano, V; Alexandre-Franco, M F; Valenzuela-Calahorro, C

2003-10-01

Merck carbon (1.5 mm) was treated in three ways: heating from ambient temperature to 900 degrees C in SO(2); treatment at ambient temperature in SO(2); or successive treatments in SO(2) and H(2)S at ambient temperature. All samples were then characterised and tested as adsorbents of Cd(2+) from aqueous solution. The characterisation was in terms of composition by effecting ultimate and proximate analyses and also of textural properties by N(2) adsorption at -196 degrees C. Kinetics and extent of the adsorption process of Cd(2+) were studied at 25 and 45 degrees C at pH of the Cd(2+) solution (i.e., 6.2) and at 25 degrees C also at pH 2.0. The various treatments of the starting carbon had no significant effect on the kinetics of the adsorption of Cd(2+), but increased its adsorption capacity. The most effective treatment was heating to 900 degrees C, the adsorption in this case being 70.3% more than that of the starting carbon. The adsorption increased at 45 degrees C but decreased at pH 2.0 when compared to adsorption at 25 degrees C and pH 6.2, respectively.

Studies on adsorption capacity of clay-Sargassum sp biosorbent for Cr (VI) removal in wastewater from electroplating industry

NASA Astrophysics Data System (ADS)

Aprianti, Tine; Aprilyanti, Selvia; Apriani, Rachmawati; Sisnayati

2017-11-01

Various raw biosorbents have been studied for pollutant treatment of heavy metals contained in wastewater. In this study, clay and brown seaweed, Sargassum sp, are used for hexavalent chromium [Cr (VI)] biosorption. The adsorption capacity is adequately improved by combining clay and Sargassum sp as the adsorbent agent. Ion exchange of metal ions has shown strong coordination cross-linkage due to organic functional hydroxyl groups (OH-) contained in brown seaweed that provide sites to capture and bind the metal ions. Clay is known as an inexpensive adsorbent due to its wide availability besides its large specific surface area. Combining clay and Sargassum sp as biosorbent resulting better adsorption, the adsorption capacity reaches most favorable results of 99.39% at Sargassum: clay ratio of 40:60 on contact time 10 h. This study has proven that composit biosorbent used has succeeded in reducing hexavalent chromium pollutant in wastewater.

A Novel Exopolysaccharide with Metal Adsorption Capacity Produced by a Marine Bacterium Alteromonas sp. JL2810

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

Zhang, Zilian; Cai, Ruanhong; Zhang, Wenhui

Most marine bacteria can produce exopolysaccharides (EPS). However, very few structures of EPS produced by marine bacteria have been determined. The characterization of EPS structure is important for the elucidation of their biological functions and ecological roles. In this study, the structure of EPS produced by a marine bacterium, Alteromonas sp. JL2810, was characterized, and the biosorption of the EPS for heavy metals Cu 2+, Ni 2+, and Cr 6+ was also investigated. Nuclear magnetic resonance (NMR) analysis indicated that the JL2810 EPS have a novel structure consisting of the repeating unit of [-3)-α-Rhap-(1→3)-α-Manp-(1→4)-α-3OAc-GalAp-(1→]. The biosorption of the EPS formore » heavy metals was affected by a medium pH; the maximum biosorption capacities for Cu 2+ and Ni 2+ were 140.8-8.2 mg/g and 226.3-3.3 mg/g at pH 5.0; however, for Cr 6+ it was 215.2-5.1 mg/g at pH 5.5. Infrared spectrometry analysis demonstrated that the groups of O-H, C=O, and C-O-C were the main function groups for the adsorption of JL2810 EPS with the heavy metals. The adsorption equilibrium of JL2810 EPS for Ni 2+ was further analyzed, and the equilibrium data could be better represented by the Langmuir isotherm model. The novel EPS could be potentially used in industrial applications as a novel bio-resource for the removal of heavy metals.« less

A Novel Exopolysaccharide with Metal Adsorption Capacity Produced by a Marine Bacterium Alteromonas sp. JL2810

DOE PAGES

Zhang, Zilian; Cai, Ruanhong; Zhang, Wenhui; ...

2017-06-12

Most marine bacteria can produce exopolysaccharides (EPS). However, very few structures of EPS produced by marine bacteria have been determined. The characterization of EPS structure is important for the elucidation of their biological functions and ecological roles. In this study, the structure of EPS produced by a marine bacterium, Alteromonas sp. JL2810, was characterized, and the biosorption of the EPS for heavy metals Cu 2+, Ni 2+, and Cr 6+ was also investigated. Nuclear magnetic resonance (NMR) analysis indicated that the JL2810 EPS have a novel structure consisting of the repeating unit of [-3)-α-Rhap-(1→3)-α-Manp-(1→4)-α-3OAc-GalAp-(1→]. The biosorption of the EPS formore » heavy metals was affected by a medium pH; the maximum biosorption capacities for Cu 2+ and Ni 2+ were 140.8-8.2 mg/g and 226.3-3.3 mg/g at pH 5.0; however, for Cr 6+ it was 215.2-5.1 mg/g at pH 5.5. Infrared spectrometry analysis demonstrated that the groups of O-H, C=O, and C-O-C were the main function groups for the adsorption of JL2810 EPS with the heavy metals. The adsorption equilibrium of JL2810 EPS for Ni 2+ was further analyzed, and the equilibrium data could be better represented by the Langmuir isotherm model. The novel EPS could be potentially used in industrial applications as a novel bio-resource for the removal of heavy metals.« less

Summary of Adsorption Capacity and Adsorption Kinetics of Uranium and Other Elements on Amidoxime-based Adsorbents from Time Series Marine Testing at the Pacific Northwest National Laboratory

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

Gill, Gary A.; Kuo, Li-Jung; Strivens, Jonathan E.

The Pacific Northwest National Laboratory (PNNL) has been conducting marine testing of uranium adsorbent materials for the Fuel Resources Program, Department of Energy, Office of Nuclear Energy (DOE-NE) beginning in FY 2012. The marine testing program is being conducted at PNNL’s Marine Sciences Laboratory (MSL), located at Sequim Bay, along the coast of Washington. One of the main efforts of the marine testing program is the determination of adsorption capacity and adsorption kinetics for uranium and selected other elements (e.g. vanadium, iron, copper, nickel, and zinc) for adsorbent materials provided primarily by Oak Ridge National Laboratory (ORNL), but also includesmore » other Fuel Resources Program participants. This report summarizes the major marine testing results that have been obtained to date using time series sampling for 42 to 56 days using either flow-through column or recirculating flume exposures. The major results are highlighted in this report, and the full data sets are appended as a series of Excel spreadsheet files. Over the four year period (2012-2016) that marine testing of amidoxime-based polymeric adsorbents was conducted at PNNL’s Marine Science Laboratory, there has been a steady progression of improvement in the 56-day adsorbent capacity from 3.30 g U/kg adsorbent for the ORNL 38H adsorbent to the current best performing adsorbent prepared by a collaboration between the University of Tennessee and ORNL to produce the adsorbent SB12-8, which has an adsorption capacity of 6.56 g U/kg adsorbent. This nearly doubling of the adsorption capacity in four years is a significant advancement in amidoxime-based adsorbent technology and a significant achievement for the Uranium from Seawater program. The achievements are evident when compared to the several decades of work conducted by the Japanese scientists beginning in the 1980’s (Kim et al., 2013). The best adsorbent capacity reported by the Japanese scientists was 3.2 g U

Vertically aligned double wall carbon nanotube arrays adsorbent for pure and mixture adsorption of H2S, ethylbenzene and carbon monoxide, grand canonical Monte Carlo simulation.

PubMed

Tasharrofi, Saeideh; Taghdisian, Hossein; Golchoobi, Abdollah

2018-05-01

In this study, pure and ternary adsorption of hydrogen sulfide (H 2 S), ethylbenzene (EB), and carbon monoxide (CO) on different arrays of zigzag double wall carbon nanotube was investigated using grand canonical Monte Carlo simulations. The internal diameters of nanotube were fixed at 2r = 50.17 Å while nanotube wall distances were different values from d = 0 Å to d = 150 Å. Pure simulation results indicated that adsorption quantity of H 2 S and EB in low pressure ranges of P = 1.9 bar to P = 3.1 bar was at least 100% more than CO adsorption quantities. At high pressure ranges of P = 23.1 bar to P = 38.2 bar H 2 S adsorption was greater than EB and CO by about 200 molecules per unit cell (UC) at low nanotube distances. This was related to smaller kinetic diameter and greater dipole moment of H 2 S compared to EB and CO. At higher nanotube distance the effect of size however disappears and all three gases approach to adsorption quantity of about 800 molecules/UC. Graphical representation of adsorption areas showed that H 2 S and CO form multilayer adsorption around nanotube inner and outer walls while EB fill the whole space uniformly without any congestion around the walls. Ternary adsorption results EB/CO and H 2 S/CO selectivity are greater than EB/H 2 S selectivity. In addition, at smaller nanotube distances H 2 S/CO selectivity is generally higher than EB/CO selectivity, which at higher nanotube distance the order becomes revers suggesting that size dependent effects on adsorption vanishes. Isosteric heat of adsorption shows that the order of EB > H 2 S > CO suggesting that ethylbenzene interaction with nanotube arrays was strongest. Although H 2 S has a greater dipole moment and smaller molecular dimension, EB adsorption at higher nanotube distance is greater than H 2 S by at least 50% probably because EB is less volatile. Copyright © 2018 Elsevier Inc. All rights reserved.

Evaluation of adsorption capacities of humic acids extracted from Algerian soil on polyaniline for application to remove pollutants such as Cd(II), Zn(II) and Ni(II) and characterization with cavity microelectrode.

PubMed

Terbouche, Achour; Ramdane-Terbouche, Chafia Ait; Hauchard, Didier; Djebbar, Safia

2011-01-01

The adsorption capacities of new humic acids isolated from Yakouren forest (YHA) and Sahara (Tamenrasset: THA) soils (Algeria) and commercial humic acid (PFHA) on polyaniline emeraldine base (PEB) were studied at pH 6.6. Also the adsorption of heavy metals such as Cd2+, Zn2+ and Ni2+ on humic acid-polyaniline systems (HA-PEB) was investigated at the same conditions. HA-PEB compounds were characterized by scanning electron microscopy (SEM), infrared spectrometry and cavity microelectrode. In addition, batch adsorption and cavity microelectrode were used in the adsorption study of Cd2+, Zn2+ and Ni2+ on HA-PEB. To develop biocaptors of polluting metals using a cavity microelectrode modified by HA-PEB systems, the adsorption kinetic and adsorption capacity were investigated. The SEM analysis showed that the presence of humic acid affected the PEB surface and caused the formation of a granular morphology. The maximum adsorption capacities (q(max)) of PFHA, THA and YHA determined by adsorption isotherms were 91.31, 132.1 and 151.0 mg/g, respectively. Batch adsorption results showed that q(max) of Cd2+, Zn2+ and Ni2+ on HA-PEB followed the order: THA-PEB > YHA-PEB > PFHA-PEB. The voltammograms obtained with HA-PEB modified cavity microelectrode showed the appearance of new redox couples reflecting the adsorption of HA on PEB. Metal-humic acid-polyaniline voltammograms were characterized by appearance of oxidation-reduction couples or reduction wave corresponding to metal. Finally, the result may be exploited to develop a biocaptor based on the cavity microelectrode amended by THA-PEB and YHA-PEB.

Hexavalent chromium adsorption from aqueous solution using carbon nano-onions (CNOs).

PubMed

Sakulthaew, Chainarong; Chokejaroenrat, Chanat; Poapolathep, Amnart; Satapanajaru, Tunlawit; Poapolathep, Saranya

2017-10-01

The capacity of carbon nano-onions (CNOs) to remove hexavalent chromium (Cr(VI)) from aqueous solution was investigated. Batch experiments were performed to quantify the effects of the dosage rate, pH, counter ions, and temperature. The adsorption of Cr(VI) onto CNOs was best described by a pseudo-second order rate expression. The adsorption efficiency increased with increasing adsorbent dosage and contact time and reached equilibrium in 24 h. The equilibrium data showed better compliance with a Langmuir isotherm than a Freundlich isotherm. Effective removal of Cr(VI) was demonstrated at pH values ranging from 2 to 10. The adsorption capacity of Cr(VI) was found to be highest (82%) at pH 3.4 and greatly depended on the solution pH. We found that Cr(VI) adsorption decreased with increasing pH over the pH range of 3.4-10. The adsorption capacity increased dramatically when the temperature increased from 10 °C to 50 °C regardless of the amount of CNOs used. Cr(VI) removal decreased by ∼13% when Zn(II), Cu(II), and Pb(II) were present, while there were no significant changes observed when NO 3 - or SO 4 2- was present. The overall results support that CNOs can be used as an alternative adsorbent material to remove Cr(VI) in the water treatment industry. Copyright © 2017 Elsevier Ltd. All rights reserved.

Adsorptive removal of organics from aqueous phase by acid-activated coal fly ash: preparation, adsorption, and Fenton regenerative valorization of "spent" adsorbent.

PubMed

Wang, Nannan; Hao, Linlin; Chen, Jiaqing; Zhao, Qiang; Xu, Han

2018-05-01

Raw coal fly ash was activated to an adsorbent by sulfuric acid impregnation. The activation condition, the adsorption capacity, and the regenerative valorization of the adsorbent were studied. The results show that the optimal preparation conditions of the adsorbent are [H 2 SO 4 ] = 1 mol L -1 , activation time = 30 min, the ratio of coal fly ash to acid = 1:20 (g:mL), calcination temperature = 100 °C. The adsorption of p-nitrophenol on the adsorbent accords with the pseudo-second-order kinetic equation and the adsorption rate constant is 0.089 g mg -1  min -1 . The adsorption on this adsorbent can be considered enough after 35 min, when the corresponding adsorption capacity is 1.07 mg g -1 (85.6% of p-nitrophenol removal). Compared with raw coal fly ash, the adsorbent has a stable adsorption performance at low pH range (pH = 1-6) and the adsorption of p-nitrophenol is an exothermic process. Ninety minutes is required for the regenerative valorization of saturated adsorbent by Fenton process. The regenerative valorization for this saturated adsorbent can reach 89% under the optimal proposed conditions (30 °C, pH = 3, [H 2 O 2 ] = 5.0 mmol L -1 , [Fe 2+ ] = 5.5 mmol L -1 ). Within 15 experimental runs, the adsorbent has a better and better stability with the increase of experimental runs. Finally, the mechanism of activating coal fly ash is proposed, being verified by the results of the SEM and BET test.

Characteristics and mechanisms of nickel adsorption on biochars produced from wheat straw pellets and rice husk.

PubMed

Shen, Zhengtao; Zhang, Yunhui; McMillan, Oliver; Jin, Fei; Al-Tabbaa, Abir

2017-05-01

The adsorption characteristics and mechanisms of Ni 2+ on four-standard biochars produced from wheat straw pellets (WSP550, WSP700) and rice husk (RH550, RH700) at 550 and 700 °C, respectively, were investigated. The kinetic results show that the adsorption of Ni 2+ on the biochars reached an equilibrium within 5 min. The increase of the solid to liquid ratio resulted in an increase of Ni 2+ removal percentage but a decrease of the adsorbed amount of Ni 2+ per weight unit of biochar. The Ni 2+ removal percentage increased with the increasing of initial solution pH values at the range of 2-4, was relatively constant at the pH range of 4-8, and significantly increased to ≥98% at pH 9 and stayed constantly at the pH range of 9-10. The calculated maximum adsorption capacities of Ni 2+ for the biochars follow the order of WSP700 > WSP550 > RH700 > RH550. Both cation exchange capacity and pH of biochar can be a good indicator of the maximum adsorption capacity for Ni 2+ showing a positively linear and exponential relationship, respectively. This study also suggests that a carefully controlled standardised production procedure can make it reliable to compare the adsorption capacities between different biochars and investigate the mechanisms involved.

[Adsorption of the TiO2 @ yeast composite microspheres for adsorbing Fluorescent Whitening Agent-VBL in fixed bed].

PubMed

Wu, Fei; Zhang, Kai-Qiang; Bai, Bo; Wang, Hong-Lun; Suo, You-Rui

2015-02-01

In this work, the adsorption potential of TiO2@ yeast composite microspheres to remove Fluorescent Whitening Agent-VBL (FWA-VBL) from aqueous solution was investigated using fixed-bed adsorption column. The effects of pH(2.0-8.0), bed height (1-3 cm), inlet concentration (20-80 mg x L(-1)) and feed flow rate (5-11 mL x min(-1)) on the breakthrough characteristics of the adsorption system were determined. The results showed that the highest bed capacity of 223.80 mg x g(-1) was obtained under the condition of pH 2.0, 80 mg x L(-1) inlet dye concentration, 1.0 cm bed height and 5 mL x min(-1) flow rate. The adsorption data were fitted to three well-established fixed-bed adsorption models, namely, BDST model, Thomas model and Yoon-Nelson model. The results fitted well to the three models with coefficients of correlation R2 > 0.980 in different conditions. The TiO2 @ yeast composite microspheres have desired regeneration ability and could be reused for four times.

Adsorptive removal of antibiotics from water using magnetic ion exchange resin.

PubMed

Wang, Tianyue; Pan, Xun; Ben, Weiwei; Wang, Jianbing; Hou, Pin; Qiang, Zhimin

2017-02-01

The occurrence of antibiotics in the environment has recently raised serious concern regarding their potential threat to aquatic ecosystem and human health. In this study, the magnetic ion exchange (MIEX) resin was applied for removing three commonly-used antibiotics, sulfamethoxazole (SMX), tetracycline (TCN) and amoxicillin (AMX) from water. The results of batch experiments show that the maximum adsorption capacities on the MIEX resin for SMX, TCN and AMX were 789.32, 443.18 and 155.15μg/mL at 25°C, respectively, which were 2-7 times that for the powdered activated carbon. The adsorption kinetics of antibiotics on the MIEX resin could be simulated by the pseudo-second-order model (R 2 =0.99), and the adsorption isotherm data were well described by the Langmuir model (R 2 =0.97). Solution pH exhibited a remarkable impact on the adsorption process and the absorbed concentrations of the tested antibiotics were obtained around the neutral pH. The MIEX resin could be easily regenerated by 2mol/L NaCl solution and maintained high adsorption removal for the tested antibiotics after regeneration. Anion exchange mechanism mainly controlled the adsorption of antibiotic and the formation of hydrogen binding between the antibiotic and resin can also result in the increase of adsorption capacity. The high adsorption capacity, fast adsorption rate and prominent reusability make the MIEX resin a potential adsorbent in the application for removing antibiotics from water. Copyright © 2016. Published by Elsevier B.V.

Synthesis and Absorption Properties of Hollow-spherical Dy2Cu2O5 via a Coordination Compound Method with [DyCu(3,4-pdc)2(OAc)(H2O)2]•10.5H2O Precursor.

PubMed

Liu, Xuanwen; You, Junhua; Wang, Renchao; Ni, Zhiyuan; Han, Fei; Jin, Lei; Ye, Zhiqi; Fang, Zhao; Guo, Rui

2017-10-12

Dy 2 Cu 2 O 5 nanoparticles with perovskite structures were synthesized via a simple solution method (SSM) and a coordination compound method (CCM) using [DyCu(3,4-pdc) 2 (OAc)(H 2 O) 2 ]•10.5H 2 O (pdc = 3,4-pyridinedicarboxylic acid) as precursor. The as-prepared samples were structurally characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), x-ray photoelectron spectroscopy (XPS) and standard Brunauer-Emmett-Teller (BET) methods. Compared to the aggregated hexahedral particles prepared by SSM, the Dy 2 Cu 2 O 5 of CCM showed hollow spherical morphology composed of nanoparticles with average diameters of 100-150 nm and a larger special surface area up to 36.5 m 2 /g. The maximum adsorption capacity (Q m ) of CCM for malachite green (MG) determined by the adsorption isotherms with different adsorbent dosages of 0.03-0.07 g, reached 5.54 g/g at room temperature. The thermodynamic parameters of adsorption process were estimated by the fittings of the isotherms at 298, 318, and 338 K, and the kinetic parameters were obtained from the time-dependent adsorption isotherms. The results revealed that the adsorption process followed a pseudo-second-order reaction. Finally, the adsorption mechanism was studied using a competitive ion (CI) experiments, and the highly efficient selective adsorption was achieved due to strong O-Cu and O-Dy coordination bonds between Dy 2 Cu 2 O 5 and MG.

Effects of hydrogenated TiO2 nanotube arrays on protein adsorption and compatibility with osteoblast-like cells.

PubMed

Lu, Ran; Wang, Caiyun; Wang, Xin; Wang, Yuji; Wang, Na; Chou, Joshua; Li, Tao; Zhang, Zhenting; Ling, Yunhan; Chen, Su

2018-01-01

Modified titanium (Ti) substrates with titanium dioxide (TiO 2 ) nanotubes have broad usage as implant surface treatments and as drug delivery systems. To improve drug-loading capacity and accelerate bone integration with titanium, in this study, we hydrogenated anodized titanium dioxide nanotubes (TNTs) by a thermal treatment. Three groups were examined, namely: hydrogenated TNTs (H 2 -TNTs, test), unmodified TNTs (air-TNTs, control), and Ti substrates (Ti, control). Our results showed that oxygen vacancies were present in all the nanotubes. The quantity of -OH groups greatly increased after hydrogenation. Furthermore, the protein adsorption and loading capacity of the H 2 -TNTs were considerably enhanced as compared with the properties of the air-TNTs ( P <0.05). Additionally, time-of-flight secondary ion mass spectrometry (TOF-SIMS) was used to investigate the interactions of TNTs with proteins. During the protein-loading process, the H 2 -TNTs not only enabled rapid protein adsorption, but also decreased the rate of protein elution compared with that of the air-TNTs. We found that the H 2 -TNTs exhibited better biocompatibility than the air-TNT and Ti groups. Both cell adhesion activity and alkaline phosphatase activity were significantly improved toward MG-63 human osteoblast-like cells as compared with the control groups ( P <0.05). We conclude that hydrogenated TNTs could greatly improve the loading capacity of bioactive molecules and MG-63 cell proliferation.

Removal of arsenic from water by Friedel's salt (FS: 3CaO·Al2O3·CaCl2·10H2O).

PubMed

Zhang, Danni; Jia, Yongfeng; Ma, Jiayu; Li, Zhibao

2011-11-15

Low levels of arsenic can be effectively removed from water by adsorption onto various materials and searching for low-cost, high-efficiency new adsorbents has been a hot topic in recent years. In the present study, the performance of Friedel's salt (FS: 3CaO·Al(2)O(3)·CaCl(2)·10H(2)O), a layered double hydroxide (LDHs), as an adsorbent for arsenic removal from aqueous solution was investigated. Friedel's salt was synthesized at lower temperature (50°C) compared to traditional autoclave methods by reaction of calcium chloride with sodium aluminate. Kinetic study revealed that adsorption of arsenate by Friedel's salt was fast in the first 12h and equilibrium was achieved within 48 h. The adsorption kinetics are well described by second-order Lageren equation. The adsorption capacity of the synthesized sorbent for arsenate at pH 4 and 7 calculated from Langmuir adsorption isotherms was 11.85 and 7.80 mg/g, respectively. Phosphate and silicate markedly decreased the removal of arsenate, especially at higher pH, but sulfate was found to suppress arsenate adsorption at lower pH and the adverse effect was disappeared at pH ≥ 6. Common metal cations (Ca(2+), Mg(2+)) enhanced arsenate adsorption. The results suggest that Friedel's salt is a potential cost-effective adsorbent for arsenate removal in water treatment. Copyright © 2011 Elsevier B.V. All rights reserved.

Activated Carbon Preparation and Modification for Adsorption

NASA Astrophysics Data System (ADS)

Cao, Yuhe

Butanol is considered a promising, infrastructure-compatible biofuel. Butanol has a higher energy content than ethanol and can be used in conventional gas engines without modifications. Unfortunately, the fermentation pathway for butanol production is restricted by its toxicity to the microbial strains used in the process. Butanol is toxic to the microbes, and this can slow fermentation rates and reduce butanol yields. Gas stripping technology can efficiently remove butanol from the fermentation broth as it is produced, thereby decreasing its inhibitory effects. Traditional butanol separation heavily depends on the energy intensive distillation method. One of the main issues in acetone-butanol-ethanol fermentation is that butanol concentrations in the fermentation broth are low, ranging from 1 to 1.2 percent in weight, because of its toxicity to the microorganisms. Therefore distillation of butanol is even worse than distillation of corn ethanol. Even new separation methods, such as solid- extraction methods involve adding substances, such as polymer resin and zeolite or activated carbon, to biobutanol fermentatioon broth did not achieve energy efficient separation of butanol due to low adsorption selectivity and fouling in broth. Gas-stripping - condensation is another new butanol recovery method, however, the butanol in gas-stripping stream is too low to be condensed without using expensive and energy intensive liquid nitrogen. Adsorption can then be used to recover butanol from the vapor phase. Activated carbon (AC) samples and zeolite were investigated for their butanol vapor adsorption capacities. Commercial activated carbon was modified via hydrothermal H2O2 treatment, and the specific surface area and oxygen-containing functional groups of activated carbon were tested before and after treatment. Hydrothermal H2O 2 modification increased the surface oxygen content, Brunauer-Emmett-Teller surface area, micropore volume, and total pore volume of active carbon

Adsorption of methyl orange using activated carbon prepared from lignin by ZnCl2 treatment

NASA Astrophysics Data System (ADS)

Mahmoudi, K.; Hamdi, N.; Kriaa, A.; Srasra, E.

2012-08-01

Lignocellulosic materials are good and cheap precursors for the production of activated carbon. In this study, activated carbons were prepared from the lignin at different temperatures (200 to 500°C) by ZnCl2. The effects influencing the surface area of the resulting activated carbon are activation temperature, activation time and impregnation ratio. The optimum condition, are found an impregnation ratio of 2, an activation temperature of 450°C, and an activation time of 2 h. The results showed that the surface area and micropores volume of activated carbon at the experimental conditions are achieved to 587 and 0.23 cm3 g-1, respectively. The adsorption behavior of methyl orange dye from aqueous solution onto activated lignin was investigated as a function of equilibrium time, pH and concentration. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms. A maximum adsorption capacity of 300 mg g-1 of methyl orange by activated carbon was achieved.

Efficient removal of arsenite through photocatalytic oxidation and adsorption by ZrO2-Fe3O4 magnetic nanoparticles

NASA Astrophysics Data System (ADS)

Sun, Tianyi; Zhao, Zhiwei; Liang, Zhijie; Liu, Jie; Shi, Wenxin; Cui, Fuyi

2017-09-01

Bifunctional ZrO2-Fe3O4 magnetic nanoparticles were synthesized and characterized, to remove As(III) through photocatalyic oxidation and adsorption. With a saturation magnetization of 27.39 emu/g, ZrO2-Fe3O4 nanoparticles with size of 10-30 nm could be easily separated from solutions with a simple magnetic process. Under UV light, As(III) could be completely oxidized to less toxic As(V) by ZrO2-Fe3O4 nanoparticles within 40 min in the photocatalytic reaction. Simultaneously, As(V) could be adsorbed onto the surface of nanoparticles with high efficiency. The adsorption of As(V) was well fitted by the pseudo-second-order model and the Freundlich isotherm model, respectively, and the maximum adsorption capacities of the nanoparticles was 133.48 mg/g at pH 7.0. As(III) could be effectively removed by ZrO2-Fe3O4 nanoparticles at initial pH range from 4 to 8. Among all the common coexisting ions investigated, except for chloride and sulfate, carbonate, silicate and phosphate decreased the As(III) removal by competing with arsenic species for adsorption sites. The synthesized magnetic ZrO2-Fe3O4 combined the photocatalytic oxidation property of ZrO2 and the high adsorption capacity of both ZrO2 and Fe3O4, which make it have significant potential applications in the As(III)-contaminated water treatment.

Methane and CO2 Adsorption Capacities of Kerogen in the Eagle Ford Shale from Molecular Simulation.

PubMed

Psarras, Peter; Holmes, Randall; Vishal, Vikram; Wilcox, Jennifer

2017-08-15

Over the past decade, the United States has become a world leader in natural gas production, thanks in part to a large-fold increase in recovery from unconventional resources, i.e., shale rock and tight oil reservoirs. In an attempt to help mitigate climate change, these depleted formations are being considered for their long-term CO 2 storage potential. Because of the variability in mineral and structural composition from one formation to the next (even within the same region), it is imperative to understand the adsorption behavior of CH 4 and CO 2 in the context of specific conditions and pore surface chemistry, i.e., relative total organic content (TOC), clay, and surface functionality. This study examines two Eagle Ford shale samples, both recovered from shale that was extracted at depths of approximately 3800 m and having low clay content (i.e., less than 5%) and similar mineral compositions but distinct TOCs (i.e., 2% and 5%, respectively). Experimentally validated models of kerogen were used to the estimate CH 4 and CO 2 adsorption capacities. The pore size distributions modeled were derived from low-pressure adsorption isotherm data using CO 2 and N 2 as probe gases for micropores and mesopores, respectively. Given the presence of water in these natural systems, the role of surface chemistry on modeled kerogen pore surfaces was investigated. Several functional groups associated with surface-dissociated water were considered. Pressure conditions from 10 to 50 bar were investigated using grand canonical Monte Carlo simulations along with typical outgassing temperatures used in many shale characterization and adsorption studies (i.e., 60 and 250 °C). Both CO 2 and N 2 were used as probe gases to determine the total pore volume available for gas adsorption spanning pore diameters ranging from 0.3 to 30 nm. The impacts of surface chemistry, outgassing temperature, and the inclusion of nanopores with diameters of less than 1.5 nm were determined for applications

Postsynthetic Functionalization of Mg-MOF-74 with Tetraethylenepentamine: Structural Characterization and Enhanced CO2 Adsorption.

PubMed

Su, Xiao; Bromberg, Lev; Martis, Vladimir; Simeon, Fritz; Huq, Ashfia; Hatton, T Alan

2017-03-29

Postsynthetic functionalization of magnesium 2,5-dihydroxyterephthalate (Mg-MOF-74) with tetraethylenepentamine (TEPA) resulted in improved CO 2 adsorption performance under dry and humid conditions. XPS, elemental analysis, and neutron powder diffraction studies indicated that TEPA was incorporated throughout the MOF particle, although it coordinated preferentially with the unsaturated metal sites located in the immediate proximity to the surface. Neutron and X-ray powder diffraction analyses showed that the MOF structure was preserved after amine incorporation, with slight changes in the lattice parameters. The adsorption capacity of the functionalized amino-Mg-MOF-74 (TEPA-MOF) for CO 2 was as high as 26.9 wt % versus 23.4 wt % for the original MOF due to the extra binding sites provided by the multiunit amines. The degree of functionalization with the amines was found to be important in enhancing CO 2 adsorption, as the optimal surface coverage improved performance and stability under both pure CO 2 and CO 2 /H 2 O coadsorption, and with partially saturated surface coverage, optimal CO 2 capacity could be achieved under both wet and dry conditions by a synergistic binding of CO 2 to the amines as well as metal centers.

Magnetic dendritic materials for highly efficient adsorption of dyes and drugs.

PubMed

Zhou, Li; Gao, Chao; Xu, Weijian

2010-05-01

A versatile and robust adsorbent with both magnetic property and very high adsorption capacity is presented on the basis of functionalization of iron oxide-silica magnetic particles with carboxylic hyperbranched polyglycerol (Fe(3)O(4)/SiO(2)/HPG-COOH). The structure of the resulting product was confirmed by Fourier transform infrared (FTIR) spectra, thermo gravimetric analysis (TGA), zeta-potential, and transmission electron microscopy (TEM). According to the TGA results, the density of the carboxylic groups on the surface of Fe(3)O(4)/SiO(2)/HPG-COOH is calculated to be as high as 3.0 mmol/g, posing a powerful base for adsorbing dyes and drugs. Five kinds of dyes and one representative anticancer drug were chosen to investigate the adsorption capacity of the as-prepared magnetic adsorbent. The adsorbent shows highly efficient adsorption performance for all of the adsorbates especially for the cationic dyes and drug. For example, the saturated adsorption capacity of the Fe(3)O(4)/SiO(2)/HPG-COOH for methyl violet (MV) can reach 0.60 mmol/g, which is much higher than the previous magnetic adsorbents (usually lower than 0.30 mmol/g). 95% of MV and 90% of R6G could be adsorbed within 5 min, and both of the adsorptions reached equilibrium in about 15 min. The adsorption kinetics and isotherm of the adsorbents were investigated in detail and found that the kinetic and equilibrium adsorptions are well-modeled using pseudo-second-order kinetics and Langmuir isotherm model, respectively. In addition, the influences of pH and ionic strength on the adsorption capacity were also examined and found that pH has much greater effect on the adsorption capacity compared with the ionic strength. Regeneration experiments showed that the Fe(3)O(4)/SiO(2)/HPG-COOH can be well-regenerated in ethanol and partially regenerated in 1 M HCl aqueous solution. After regeneration, the magnetic adsorbents can still show high adsorption capacity even for 10 cycles of desorption-adsorption. No

Suitability of adsorption isotherms for predicting the retention capacity of active slag filters removing phosphorus from wastewater.

PubMed

Pratt, C; Shilton, A

2009-01-01

Active slag filters are an emerging technology for removing phosphorus (P) from wastewater. A number of researchers have suggested that adsorption isotherms are a useful tool for predicting P retention capacity. However, to date the appropriateness of using isotherms for slag filter design remains unverified due to the absence of benchmark data from a full-scale, field filter operated to exhaustion. This investigation compared the isotherm-predicted P retention capacity of a melter slag with the P adsorption capacity determined from a full-scale, melter slag filter which had reached exhaustion after five years of successfully removing P from waste stabilization pond effluent. Results from the standard laboratory batch test showed that P adsorption correlated more strongly with the Freundlich Isotherm (R(2)=0.97, P<0.01) than the Langmuir Isotherm, a similar finding to previous studies. However, at a P concentration of 10 mg/L, typical of domestic effluent, the Freundlich equation predicted a retention capacity of 0.014 gP/kg slag; markedly lower than the 1.23 gP/kg slag adsorbed by the field filter. Clearly, the result generated by the isotherm bears no resemblance to actual field capacity. Scanning electron microscopy analysis revealed porous, reactive secondary minerals on the slag granule surfaces from the field filter which were likely created by weathering. This slow weathering effect, which generates substantial new adsorption sites, is not accounted for by adsorption isotherms rendering them ineffective in slag filter design.

Simultaneous adsorption of Cu2+ and Acid fuchsin (AF) from aqueous solutions by CMC/bentonite composite.

PubMed

Gong, Ning; Liu, Yanping; Huang, Ruihua

2018-04-21

Carboxymethyl-chitosan (CMC)/bentonite composite was prepared by the method of membrane-forming, and characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) techniques. The simultaneous adsorption of Cu 2+ and Acid fuchsin (AF) applying CMC/bentonite composite as an adsorbent in single or binary systems was investigated. The adsorption study was conducted systematically by varying the ratio of CMC to bentonite, adsorbent dosage, initial pH value, initial Cu 2+ (or AF) concentration, contact time and the interaction of two components in binary solutions. The results showed that the presence of Cu 2+ hindered the adsorption of AF, while the presence of AF almost had no influence on the adsorption of Cu 2+ in binary systems. The adsorption data of Cu 2+ and AF were both suitable for Langmuir isotherm model, and the maximum adsorption capacities of CMC/bentonite composite, according to the Langmuir isotherm model were 81.4 mg/g for Cu 2+ and 253.2 mg/g for AF at 298 K. The pseudo-second-order model could better describe the adsorption process of Cu 2+ and AF. Thermodynamic constant values illustrated that the adsorption of Cu 2+ was endothermic, while the adsorption process of AF was exothermic. Copyright © 2018. Published by Elsevier B.V.

Adsorption and dissociation mechanism of SO2 and H2S on Pt decorated graphene: a DFT-D3 study

NASA Astrophysics Data System (ADS)

Chen, Dachang; Zhang, Xiaoxing; Tang, Ju; Fang, Jiani; Li, Yi; Liu, Huijun

2018-06-01

This study explores the diffusion behavior of one Pt atom on graphene as well as the interaction mechanism between two types of gas molecule (SO2 and H2S) and Pt-graphene based on density functional theory (DFT) considering a dispersion correction about van der Walls force. Results suggest that one Pt atom shows high mobility with low activation energy and Pt doped graphene exhibits relatively stronger interaction with H2S than SO2 according to adsorption energy. SO2 accepts electrons from Pt-graphene while H2S losses electrons. Both two molecules introduce obvious hybridization with Pt-graphene in density of states. The charge density difference and Electron Localization Function (ELF) configurations indicate evident changes in the distribution of electrons about Pt-graphene and gas molecule before and after gas adsorption. H2S is easy to dissociate on Pt-graphene due to the much lower energy barrier compared to SO2. The work provides quantum chemistry methods to investigate the chemical interaction between Pt decorated graphene and two typical gases to shed light on practical application of Pt-graphene in adsorbing and detecting these two kinds of gases or other types of gases.

The Adsorption and Desorption of Pb(2+) and Cd(2+) in Freeze-Thaw Treated Soils.

PubMed

Li, Linhui; Ma, Jincai; Xu, Meng; Li, Xu; Tao, Jiahui; Wang, Guanzhu; Yu, Jitong; Guo, Ping

2016-01-01

Adsorption and desorption are important processes that influence the potential toxicity and bioavailability of heavy metals in soils. However, information regarding adsorption and desorption behavior of heavy metals in soils subjected to freeze-thaw cycles is poorly understood. In the current study, the effect of freeze-thaw cycles with different freezing temperature (-15, -25, -35°C) on soil properties was investigated. Then the adsorption and desorption behavior of Pb(2+) and Cd(2+) in freeze-thaw treated soils was studied. The adsorption amounts of Pb(2+) and Cd(2+) in freeze-thaw treated soils were smaller than those in unfrozen soils (p < 0.05), due to the fact that pH, cation exchange capacity, organic matter content, free iron oxide content, and CaCO3 content in freeze-thaw treated soils were smaller than those in unfrozen soils. The adsorption amounts of Pb(2+) and Cd(2+) in soils treated with lower freezing temperatures were higher than those in soils treated with higher freezing temperatures. Desorption percentages of Pb(2+) and Cd(2+) in unfrozen soils were smaller than those in freeze-thaw treated soils (p < 0.05). The desorption percentages of Pb(2+) and Cd(2+) were smaller in soils treated with lower freezing temperatures than those in soils treated with higher freezing temperatures. The results obtained highlight the change of the adsorption and desorption behavior of typical heavy metals in freeze-thaw treated soils located in seasonal frozen soils zone in northeast China.

Fabrication of carbon/SiO2 composites from the hydrothermal carbonization process of polysaccharide and their adsorption performance.

PubMed

Li, Yinhui; Li, Kunyu; Su, Min; Ren, Yanmei; Li, Ying; Chen, Jianxin; Li, Liang

2016-11-20

In this work, carbon/SiO2 composites, using amylose and tetraethyl orthosilicate (TEOS) as raw materials, were successfully prepared by a facial hydrothermal carbonization process. The carbon/SiO2 composites were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Energy Dispersive Spectroscopy (EDS), transmission electron microscope (TEM), N2 adsorption and Thermogravimetric (TG) analysis. The composites, which were made up of amorphous SiO2 and amorphous carbon, were found to have hierarchical porous structures. The mass ratios of amylose and SiO2 and the hydrothermal carbonization time had significant effects on the morphology of the composites, which had three shapes including monodispersed spheres, porous pieces and the nano-fibers combined with nano-spheres structures. The adsorption performance of the composites was studied using Pb(2+) as simulated contaminants from water. When the mass ratio of amylose and SiO2 was 9/1, the hydrothermal time was 30h and the hydrothermal temperature was 180°C, the adsorption capacity of the composites achieved to 52mg/g. Experimental data show that adsorption kinetics of the carbon/SiO2 composites can be fitted well by the Elovich model, while the isothermal data can be perfectly described by the Langmuir adsorption model and Freundlich adsorption model. The maximum adsorption capacity of the carbon/SiO2 composites is 56.18mgg(-1). Copyright © 2016 Elsevier Ltd. All rights reserved.

Mesoporous g-C₃N₄ Nanosheets: Synthesis, Superior Adsorption Capacity and Photocatalytic Activity.

PubMed

Li, Dong-Feng; Huang, Wei-Qing; Zou, Lan-Rong; Pan, Anlian; Huang, Gui-Fang

2018-08-01

Elimination of pollutants from water is one of the greatest challenges in resolving global environmental issues. Herein, we report a high-surface-area mesoporous g-C3N4 nanosheet with remarkable high adsorption capacity and photocatalytic performance, which is prepared through directly polycondensation of urea followed by a consecutive one-step thermal exfoliation strategy. This one-pot method to prepare mesoporous g-C3N4 nanosheet is facile and rapid in comparison with others. The superior adsorption capacity of the fabricated mesoporous g-C3N4 nanostructures is demonstrated by a model organic pollutant-methylene blue (MB), which is up to 72.2 mg/g, about 6 times as that of the largest value of various g-C3N4 adsorbents reported so far. Moreover, this kind of porous g-C3N4 nanosheet exhibits high photocatalytic activity to MB and phenol degradation. Particularly, the regenerated samples show excellent performance of pollutant removal after consecutive adsorption/degradation cycles. Therefore, this mesoporous g-C3N4 nanosheet may be an attractive robust metal-free material with great promise for organic pollutant elimination.

Rapid adsorptive removal of toxic Pb(2+) ion from aqueous solution using recyclable, biodegradable nanocomposite derived from templated partially hydrolyzed xanthan gum and nanosilica.

PubMed

Ghorai, Soumitra; Sarkar, Amit Kumar; Pal, Sagar

2014-10-01

This work studied the application of a novel biodegradable nanocomposite based on partially hydrolyzed polyacrylamide grafted xanthan gum and nanosilica (h-XG/SiO2) towards efficient and rapid removal of toxic Pb(2+) ions from aqueous environment. The uptake ability of Pb(2+) using h-XG/SiO2 has been studied in batch adsorption experiments with variation of adsorption parameters. The excellent removal rate (99.54% adsorption within 25min) and superior adsorption capacity (Qmax=1012.15mgg(-1)) of the composite material have been explained on the basis of synergistic and chelating effects of h-XG/SiO2 with Pb(2+) ion through electrostatic interactions. The kinetics, isotherm and thermodynamics studies reveal that Pb(2+) adsorb rapidly on nanocomposite surface, which is in agreement with pseudo-second-order kinetics and Langmuir adsorption isotherm models. In consequence of excellent adsorption as well as regeneration characteristics of nanocomposite, it has been found to be a promising adsorbent towards removal of Pb(2+) ions from battery industry wastewater. Copyright © 2014 Elsevier Ltd. All rights reserved.

Composites of ZnO nanoparticles and biomass based activated carbon: adsorption, photocatalytic and antibacterial capacities.

PubMed

Cruz, G J F; Gómez, M M; Solis, J L; Rimaycuna, J; Solis, R L; Cruz, J F; Rathnayake, B; Keiski, R L

2018-05-01

Composite material (AC-ZnO) was prepared by growing ZnO nanoparticles during the production of biomass based-activated carbon (AC) via the incorporation of zinc acetate in the process. Comprehensive analyses confirmed the presence of ZnO nanoparticles over the AC surface and described the particular nature of the composite adsorbent. Methylene blue (MB) equilibrium data fitted the Dubinin-Radushkevich model. The MB adsorption capacity was higher for the bare activated carbons (197.9-188.7 mg/g) than the activated carbons with ZnO nanoparticles (137.6-149.7 mg/g). The adsorption of the MB on the adsorbents is physical because the mean adsorption energy (E) is between 1.76 and 2.00 kJ/mol. Experiments that combine adsorption and photocatalysis were carried out with different loads of adsorbents and with and without UV-light exposure. Photocatalytic activity was identified mostly at the first stage of the adsorption process and, in the case of experiments with less load of the composite AC-ZnO, because the light obstruction effect of the activated carbon is more for higher loads. The ZnO grown over AC improves the adsorption of cations such as Pb, Al and Fe in aqueous phase (polluted river water) and provides antibacterial capacity against Escherichia coli and Salmonella typhimurium.

Kinetics and thermodynamics studies on the BMP-2 adsorption onto hydroxyapatite surface with different multi-morphological features.

PubMed

Lu, Zhiwei; Huangfu, Changxin; Wang, Yanying; Ge, Hongwei; Yao, Yao; Zou, Ping; Wang, Guangtu; He, Hua; Rao, Hanbing

2015-01-01

The effect of the surface topography on protein adsorption process is of great significance for designing hydroxyapatite (HA) ceramic material surfaces. In this work, three different topographies of HA materials HA-sheet, HA-rod, and HA-whisker were synthesized and testified by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Brunauer-Emmett-Teller (BET) and a field emission scanning electron microscopy (FE-SEM). We have systematically investigated the adsorption kinetics and thermodynamics of bone morphogenetic proteins (BMP-2) on the three different topography surfaces of HA, respectively. The results showed that the maximum adsorption capacities of HA-sheet, HA-rod and HA-whisker were (219.96 ± 10.18), (247.13 ± 12.35), and (354.67 ± 17.73) μg · g(-1), respectively. Kinetic parameters, rate constants, equilibrium adsorption capacities and related correlation coefficients, for each kinetic model were calculated as well as discussed. It demonstrated that the adsorption of BMP-2 onto HA could be described by the pseudo second-order equation. Adsorption of BMP-2 onto HA followed the Langmuir isotherm. It confirmed that compared with other samples HA-whisker had more adsorption sites for its high specific surface area which could provide more opportunities for protein molecules. The adsorption processes were endothermic (ΔH > 0), spontaneous (ΔG < 0) and entropy increasing (ΔS > 0). A possible adsorption mechanism has been proposed. In addition, the BMP-2 could be adsorbed to the surface which existed slight conformational changes by FT-IR. Copyright © 2015 Elsevier B.V. All rights reserved.

Adsorptive removal of 2-chlorophenol by low-cost coir pith carbon.

PubMed

Namasivayam, C; Kavitha, D

2003-03-17

Adsorption of 2-chlorophenol (2-CP) by coir pith carbon was carried out by varying the parameters such as agitation time, 2-CP concentration, adsorbent dose, pH and temperature. Adsorption equilibrium reached at 40, 60, 80 and 100 min for 2-CP concentration of 10, 20, 30 and 40 mg/l, respectively. Adsorption followed second-order kinetics. The adsorption equilibrium data obeyed Freundlich isotherm. Acidic pH was favorable for the adsorption of 2-CP. Desorption studies showed that chemisorption plays a major role in the adsorption process. Copyright 2003 Elsevier Science B.V.

Humic acid provenance influence to the adsorption capacity in uranium and thorium removal

NASA Astrophysics Data System (ADS)

Prasetyo, E.

2018-01-01

It is common knowledge that humic acid is organic compound without certain chemical composition since it is derived from different organic materials. Further this raises question whether the different humic acid sample used could lead to different adsorbent properties e.g. adsorption capacity. To address the problem, this paper is aimed to clarify the relation between the provenances of humic acid and synthesized adsorbent properties especially adsorption capacities by quantitative and qualitative functional groups determination including discussion on their effect to the metal ion adsorption mechanism using three humic acid samples. Two commercial samples were derived from recent compost while the other extracted from tertiary carbonaceous mudstone strata.

Complexes of DOTA-bisphosphonate conjugates: probes for determination of adsorption capacity and affinity constants of hydroxyapatite.

PubMed

Vitha, Tomas; Kubícek, Vojtech; Hermann, Petr; Kolar, Zvonimir I; Wolterbeek, Hubert Th; Peters, Joop A; Lukes, Ivan

2008-03-04

The adsorption on hydroxyapatite of three conjugates of a bisphosphonate and a macrocycle having C1, C2, and C3 spacers and their terbium complexes was studied by the radiotracer method using 160Tb as the label. The radiotracer-containing complex of the conjugate with the C3 spacer was used as a probe for the determination of the adsorption parameters of other bisphosphonates that lack a DOTA unit. A physicochemical model describing the competitive adsorption was successfully applied in the fitting of the obtained data. The maximum adsorption capacity of bisphosphonates containing bulky substituents is determined mainly by their size. For bisphosphonates having no DOTA moiety, the maximum adsorption capacity is determined by the electrostatic repulsion between negatively charged bisphosphonate groups. Compounds with a hydroxy or amino group attached to the alpha-carbon atom show higher affinities. Macrocyclic compounds containing a short spacer between the different bisphosphonic acid groups and the macrocyclic unit exhibit high affinities, indicating a synergic effect of the bisphosphonic and the macrocyclic groups during adsorption. The competition method described uses a well-characterized complex and allows a simple evaluation of the adsorption behavior of bisphosphonates. The application of the macrocycle-bisphosphonate conjugates allows easy radiolabeling via complexation of a suitable metal isotope.

Prediction of equilibrium parameters of adsorption of lead (II) ions onto diatomite

NASA Astrophysics Data System (ADS)

Salman, Taylan; Ardalı, Yüksel; Gamze Turan, N.

2013-04-01

Heavy metals from industrial wastewaters are one of the most important environmental issues to be solved today. Due to their toxicity and nonbiodegradable nature, heavy metals cause environmental and public health problems. Various techniques have been developed to remove heavy metals from aqueous solutions. These include chemical precipitation, reverse osmosis, ion Exchange and adsorption. Among them, adsorption is considered to be a particularly competitive and effective process for the removal of heavy metals from aqueous solutions. There is growing interest in using low cost, commercially available materials for the adsorption of heavy metals. Diatomite is a siliceous sedimentary rock having an amorphous form of silica (SiO2. nH2O) containing a small amount of microcrystalline material. It has unique combination of physical and chemical properties such as high porosity, high permeability, small particle size, large surface area, and low thermal conductivity. In addition, it is available in Turkey and in various locations around the world. Therefore, diatomite has been successfully used as adsorbent for the removal of heavy metals. The aim of the study is to investigate the adsorption properties of diatomite. The equilibrium adsorption data were applied to the Langmuir, Freundlich and Dubinin-Radushkevic (D-R) isotherm models. Adsorption experiments were performed under batch process, using Pb (II) initial concentration, pH of solution and contact time as variables. The results demonstrated that the adsorption of Pb (II) was strongly dependent on pH of solution. The effect of pH on adsorption of Pb(II) on diatomite was conducted by varying pH from 2 to 12 at 20 oC. In the pH range of 2.0-4.0, the adsorption percentage increases slightly as the pH increasing. At pH>4, the adsorption percentage decreases with increasing pH because hydrolysis product and the precipitation begin to play an important role in the sorption of Pb (II). At pH4, the maximum adsorption

Adsorption of pharmaceuticals onto trimethylsilylated mesoporous SBA-15.

PubMed

Bui, Tung Xuan; Pham, Viet Hung; Le, Son Thanh; Choi, Heechul

2013-06-15

The adsorption of a complex mixture of 12 selected pharmaceuticals to trimethylsilylated mesoporous SBA-15 (TMS-SBA-15) has been investigated by batch adsorption experiments. The adsorption of pharmaceuticals to TMS-SBA-15 was highly dependent on the solution pH and pharmaceutical properties (i.e., hydrophobicity (logKow) and acidity (pKa)). Good log-log linear relationships between the adsorption (Kd) and pH-dependent octanol-water coefficients (Kow(pH)) were then established among the neutral, anionic, and cationic compounds, suggesting hydrophobic interaction as a primary driving force in the adsorption. In addition, the neutral species of each compound accounted for a major contribution to the overall compound adsorption onto TMS-SBA-15. The adsorption kinetics of pharmaceuticals was evaluated by the nonlinear first-order and pseudo-second-order models. The first-order model gave a better fit for five pharmaceuticals with lower adsorption capacity, whereas the pseudo-second-order model fitted better for seven pharmaceuticals having higher adsorption capacity. In the same group of properties, pharmaceuticals having higher adsorption capacity exhibited faster adsorption rates. The rate-limiting steps for adsorption of pharmaceuticals onto TMS-SBA-15 are boundary layer diffusion and intraparticle diffusion including diffusion in mesopores and micropores. In addition, the adsorption of pharmaceuticals to TMS-SBA-15 was not influenced by the change of initial pharmaceutical concentration (10-100μgL(-1)) and the presence of natural organic matter. Copyright © 2013 Elsevier B.V. All rights reserved.

Improving the capacity of lithium-sulfur batteries by tailoring the polysulfide adsorption efficiency of hierarchical oxygen/nitrogen-functionalized carbon host materials.

PubMed

Schneider, Artur; Janek, Jürgen; Brezesinski, Torsten

2017-03-22

The use of monolithic carbons with structural hierarchy and varying amounts of nitrogen and oxygen functionalities as sulfur host materials in high-loading lithium-sulfur cells is reported. The primary focus is on the strength of the polysulfide/carbon interaction with the goal of assessing the effect of (surface) dopant concentration on cathode performance. The adsorption capacity - which is a measure of the interaction strength between the intermediate lithium polysulfide species and the carbon - was found to scale almost linearly with the nitrogen level. Likewise, the discharge capacity of lithium-sulfur cells increased linearly. This positive correlation can be explained by the favorable effect of nitrogen on both the chemical and electronic properties of the carbon host. The incorporation of additional oxygen-containing surface groups into highly nitrogen-functionalized carbon helped to further enhance the polysulfide adsorption efficiency, and therefore the reversible cell capacity. Overall, the areal capacity could be increased by almost 70% to around 3 mA h cm -2 . We believe that the design parameters described here provide a blueprint for future carbon-based nanocomposites for high-performance lithium-sulfur cells.

Arsenite removal from aqueous solutions by γ-Fe2O3-TiO2 magnetic nanoparticles through simultaneous photocatalytic oxidation and adsorption.

PubMed

Yu, Lian; Peng, Xianjia; Ni, Fan; Li, Jin; Wang, Dongsheng; Luan, Zhaokun

2013-02-15

A novel Fe-Ti binary oxide magnetic nanoparticles which combined the photocatalytic oxidation property of TiO(2) and the high adsorption capacity and magnetic property of γ-Fe(2)O(3) have been synthesized using a coprecipitation and simultaneous oxidation method. The as-prepared samples were characterized by powder XRD, TEM, TG-DTA, VSM and BET methods. Photocatalytic oxidation of arsenite, the effect of solution pH values and initial As(III) concentration on arsenite removal were investigated in laboratory experiments. Batch experimental results showed that under UV light, As(III) can be efficiently oxidized to As(V) by dissolved O(2) in γ-Fe(2)O(3)-TiO(2) nanoparticle suspensions at various pH values. At the same time, As(V) was effectively removed by adsorption onto the surface of nanoparticles. The maximum removal capability of the nano-material for arsenite was 33.03 mg/g at pH 7.0. Among all the common coexisting ions investigated, phosphate was the greatest competitor with arsenic for adsorptive sites on the nano-material. Regeneration studies verified that the γ-Fe(2)O(3)-TiO(2) nanoparticles, which underwent five successive adsorption-desorption processes, still retained comparable catalysis and adsorption performance, indicating the excellent stability of the nanoparticles. The excellent photocatalytic oxidation performance and high uptake capability of the magnetic nano-material make it potentially attractive material for the removal of As(III) from water. Copyright © 2012 Elsevier B.V. All rights reserved.

Enhanced adsorption of chromium onto activated carbon by microwave-assisted H(3)PO(4) mixed with Fe/Al/Mn activation.

PubMed

Sun, Yuanyuan; Yue, Qinyan; Mao, Yanpeng; Gao, Baoyu; Gao, Yuan; Huang, Lihui

2014-01-30

FeCl3, AlCl3 and MnCl2 were used as the assisted activation agent in activated carbon preparation by H3PO4 activation using microwave heating method. The physico-chemical properties of activated carbons were investigated by scanning electron microscope (SEM), N2 adsorption/desorption, Boehm's titration, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). To investigate the adsorption performances of chromium onto these newly developed activated carbons, a batch of experiments were performed under different adsorption conditions: solution pH, initial Cr(VI) ion concentration, contact time and co-existing ions. The results suggested that carbon with MnCl2 as assisted activation agent displayed the highest BET surface area (1332m(2)/g) and the highest pore volume (1.060cm(3)/g). FeCl3, AlCl3 and MnCl2 had successfully improved Cr(VI) adsorption and activated carbon with FeCl3 as assisted activation agent exhibited the best uptake capacity. To study the transformation of Cr(VI) in adsorption process, total chromium in the aqueous solution was also recorded. The ratio of the amount of Cr(VI) to Cr(III) on each adsorbent was explained by XPS analysis results. Both the co-existing salts (Na2SO4 and NaNO3) demonstrated promoted effects on Cr(VI) removal by four carbons. The pseudo-second-order model and Freundlich equation displayed a good correlation with adsorption data. Copyright © 2013 Elsevier B.V. All rights reserved.

Adsorption of proteins on γ-Fe2O3 and γ-Fe2O3/SiO2 magnetic materials

NASA Astrophysics Data System (ADS)

Khokhlova, T. D.

2017-10-01

γ-Fe2O3-SiO2 composites are synthesized via the coprecipitation of a γ-Fe2O3 magnetic carrier (with specific surface S = 17 m2/g and pore volume V = 0.51 cm3/g) and silicon dioxide from an aqueous glass (sodium silicate) solution. The effect coagulation agent NaCl has on the coprecipitation process and structural characteristics of the composite is discussed. Adding NaCl to the aqueous glass solution prevents the formation of SiO2 macrogel making it possible to obtain highly porous composites with high adsorption capacity for proteins cytochrome C and hemoglobin. It is established that a composite that is 50% SiO2 and produced with the addition of 5% NaCl ( S = 150 m2/g and V = 0.87 cm3/g) has a sixfold and twofold higher capacity (280 and 175 mg/g) for cytochrome C and hemoglobin, respectively, than the initial ferric oxide (45 and 82 mg/g). The capacity for cytochrome C and hemoglobin of a composite synthesized without NaCl ( S = 50 m2/g and V = 0.45 cm3/g) is 19 and 20 mg/g, respectively, which is twofold and fourfold lower than those of the initial γ-Fe2O3. The dependence of protein adsorption on pH and the ionic strength of a solution is studied, and the conditions for the maximum adsorption and complete desorption of proteins are established. It is concluded that composites synthesized with additions of NaCl can be used as magnetocontrollable sorbents for the purification, concentration, and immobilization of proteins, and for the preparation of biocatalysts based on immobilized enzymes.

Enhancing Nitrogen Availability, Ammonium Adsorption-Desorption, and Soil pH Buffering Capacity using Composted Paddy Husk

NASA Astrophysics Data System (ADS)

Latifah, O.; Ahmed, O. H.; Abdul Majid, N. M.

2017-12-01

Form of nitrogen present in soils is one of the factors that affect nitrogen loss. Nitrate is mobile in soils because it does not absorb on soil colloids, thus, causing it to be leached by rainfall to deeper soil layers or into the ground water. On the other hand, temporary retention and timely release of ammonium in soils regulate nitrogen availability for crops. In this study, composted paddy husk was used in studies of soil leaching, buffering capacity, and ammonium adsorption and desorption to determine the: (i) availability of exchangeable ammonium, available nitrate, and total nitrogen in an acid soil after leaching the soil for 30 days, (ii) soil buffering capacity, and (iii) ability of the composted paddy husk to adsorb and desorb ammonium from urea. Leaching of ammonium and nitrate were lower in all treatments with urea and composted paddy husk compared with urea alone. Higher retention of soil exchangeable ammonium, available nitrate, and total nitrogen of the soils with composted paddy husk were due to the high buffering capacity and cation exchange capacity of the amendment to adsorb ammonium thus, improving nitrogen availability through temporary retention on the exchange sites of the humic acids of the composted paddy husk. Nitrogen availability can be enhanced if urea is amended with composted paddy husk.

pH-dependence of pesticide adsorption by wheat-residue-derived black carbon.

PubMed

Yang, Yaning; Chun, Yuan; Sheng, Guangyao; Huang, Minsheng

2004-08-03

The potential of black carbon as an adsorbent for pesticides in soils may be strongly influenced by the properties of the adsorbent and pesticides and by the environmental conditions. This study evaluated the effect of pH on the adsorption of diuron, bromoxynil, and ametryne by a wheat (Triticum aestivum L.) residue derived black carbon (WC) as compared to a commercial activated carbon (AC). The pH drift method indicated that WC had a point of zero charge of 4.2, much lower than that of 7.8 for AC. The density of oxygen-containing surface functional groups, measured by the Boehm titration, on WC was 5.4 times higher than that on AC, resulting in a pesticide adsorption by WC being 30-50% of that by AC, due to the blockage of WC surface by the waters associated with the functional groups. A small decrease (5.5%/unit pH) in diuron adsorption by WC with increase in pH resulted from increased deprotonation of surface functional groups at higher pH values. A much larger decrease (14-21%/unit pH) in bromoxynil adsorption by WC with increase in pH resulted from the deprotonation of both the adsorbate and surface functional groups of the adsorbent. The deprotonation reduced the adsorptive interaction between bromoxynil and the neutral carbon surface and increased the electrical repulsion between the negatively charged WC surface and bromoxynil anions. Deprotonation of ametryne with increase in pH over the low pH range increased its fraction of molecular form and thus adsorption on WC by 15%/unit pH. Further increase in pH resulted in a 20%/unit pH decrease in ametryne adsorption by WC due primarily to the development of a negative charge on the surface of WC. The pH-dependent adsorption of pesticides by black carbon may significantly influence their environmental fate in soils.

Adsorption of tetracycline on soil and sediment: effects of pH and the presence of Cu(II).

PubMed

Zhang, Zheyun; Sun, Ke; Gao, Bo; Zhang, Guixiang; Liu, Xitao; Zhao, Ye

2011-06-15

Tetracycline (TC) is frequently detected in the environment, however, knowledge on the environmental fate and transport of TC is still limited. Batch adsorption experiments of TC by soil and sediment samples were conducted. The distribution of charge and electrostatic potential of individual atoms of various TC species in the aqueous solution were determined using MOPAC version 0.034 W program in ChemBio3D Ultra software. Most of the adsorption isotherms on the soil, river and marine sediments were well fitted with the Freundlich and Polanyi-Manes (PMM) models. The single point organic carbon (OC)-normalized adsorption distribution coefficients (K(OC)) and PMM saturated adsorption capacity (Q(OC)(0)) values of TC were associated with the mesopore volume and clay content to a greater extent, indicating the mesopore volume of the soil and sediments and their clay content possibly influenced the fate and transport of TC in the natural environment. The adsorption of TC on soil and sediments strongly depended on the pH and presence of Cu(II). The presence of Cu(II) facilitated TC adsorption on soil and sediments at low pH (pH<5), possibly due to the metallic complexation and surface-bridging mechanism by Cu(II) adsorption on soil and sediments. The cation exchange interaction, metallic complexation and Coulombic interaction of mechanisms for adsorption of TC to soils and sediments were further supported by quantum chemical calculation of various TC species in different pH. Copyright © 2011 Elsevier B.V. All rights reserved.

Laboratory study on the adsorption of Mn(2+) on suspended and deposited amorphous Al(OH)(3) in drinking water distribution systems.

PubMed

Wang, Wendong; Zhang, Xiaoni; Wang, Hongping; Wang, Xiaochang; Zhou, Lichuan; Liu, Rui; Liang, Yuting

2012-09-01

Manganese (II) is commonly present in drinking water. This paper mainly focuses on the adsorption of manganese on suspended and deposited amorphous Al(OH)(3) solids. The effects of water flow rate and water quality parameters, including solution pH and the concentrations of Mn(2+), humic acid, and co-existing cations on adsorption were investigated. It was found that chemical adsorption mainly took place in drinking water with pHs above 7.5; suspended Al(OH)(3) showed strong adsorption capacity for Mn(2+). When the total Mn(2+) input was 3 mg/L, 1.0 g solid could accumulate approximately 24.0 mg of Mn(2+) at 15 °C. In drinking water with pHs below 7.5, because of H(+) inhibition, active reaction sites on amorphous Al(OH)(3) surface were much less. The adsorption of Mn(2+) on Al(OH)(3) changed gradually from chemical coordination to physical adsorption. In drinking water with high concentrations of Ca(2+), Mg(2+), Fe(3+), and HA, the removal of Mn(2+) was enhanced due to the effects of co-precipitation and adsorption. In solution with 1.0 mg/L HA, the residual concentration of Mn(2+) was below 0.005 mg/L, much lower than the limit value required by the Chinese Standard for Drinking Water Quality. Unlike suspended Al(OH)(3), deposited Al(OH)(3) had a much lower adsorption capacity of 0.85 mg/g, and the variation in flow rate and major water quality parameters had little effect on it. Improved managements of water age, pipe flushing and mechanical cleaning were suggested to control residual Mn(2+). Copyright © 2012 Elsevier Ltd. All rights reserved.

Adsorption of selected pharmaceuticals and an endocrine disrupting compound by granular activated carbon. 1. Adsorption capacity and kinetics.

PubMed

Yu, Zirui; Peldszus, Sigrid; Huck, Peter M

2009-03-01

The adsorption of two representative PhACs (naproxen and carbamazepine) and one EDC (nonylphenol) were evaluated on two granular activated carbons (GAC). The primary objective was to investigate preloading effects by natural organic matter (NOM) on adsorption capacity and kinetics under conditions and concentrations (i.e., ng/L) relevantfor drinking water treatment Isotherms demonstrated that all compounds were significantly negatively impacted by NOM fouling. Adsorption capacity reduction was most severe for the acidic naproxen, followed by the neutral carbamazepine and then the more hydrophobic nonylphenol. The GAC with the wider pore size distribution had considerably greater NOM loading, resulting in lower adsorption capacity. Different patterns forthe change in Freundlich K(F) and 1/n with time revealed different competitive mechanisms for the different compounds. Mass transport coefficients determined by short fixed-bed (SFB) tests with virgin and preloaded GAC demonstrated thatfilm diffusion primarily controls mass transfer on virgin and preloaded carbon. Naproxen suffered the greatest deteriorative effect on kinetic parameters due to preloading, followed by carbamazepine, and then nonylphenol. A type of surface NOM/biofilm, which appeared to add an additional masstransfer resistance layer and thus reduce film diffusion, was observed. In addition, electrostatic interactions between NOM/biofilm and the investigated compounds are proposed to contribute to the reduction of film diffusion. A companion paper building on this work describes treatability studies in pilot-scale GAC adsorbers and the effectiveness of a selected fixed-bed model.

Adsorption of CO2 from flue gas streams by a highly efficient and stable aminosilica adsorbent.

PubMed

Liu, Shou-Heng; Lin, Yuan-Chung; Chien, Yi-Chi; Hyu, Han-Ren

2011-02-01

Three ordered mesoporous silicas (OMSs) with different pore sizes and pore architectures were prepared and modified with amine functional groups by a postgrafting method. The carbon dioxide (CO2) adsorption on these amine-modified OMSs was measured by using microbalances at 348 K, and their adsorption capacities were found to be 0.2-1.4 mmol g(-1) under ambient pressure using dry 15% CO2. It was found experimentally that the CO2 adsorption capacity and adsorption rate were attributed to the density of amine groups and pore volume, respectively. A simple method is described for the production of densely anchored amine groups on a solid adsorbent invoking direct incorporation of tetraethylenepentamine onto the as-synthesized OMSs. Unlike conventional amine-modified OMSs, which typically show CO2 adsorption capacity less than 2 mmol g(-1), such organic template occluded amine-OMS composites possessed remarkably high CO2 uptake of approximately 4.6 mmol g(-1) at 348 K and 1 atm for a dry 15% CO2/nitrogen feed mixture. The enhancement of 8% in CO2 adsorption capacity was also observed in the presence of 10.6% water vapor. Durability tests done by cyclic adsorption-desorption revealed that these adsorbents also possess excellent stability.

Gas adsorption capacity in an all carbon nanomaterial composed of carbon nanohorns and vertically aligned carbon nanotubes.

PubMed

Puthusseri, Divya; Babu, Deepu J; Okeil, Sherif; Schneider, Jörg J

2017-10-04

Whereas vertically aligned carbon nanotubes (VACNTs) typically show a promising adsorption behavior at high pressures, carbon nanohorns (CNHs) exhibit superior gas adsorption properties in the low pressure regime due to their inherent microporosity. These adsorption characteristics are further enhanced when both materials are opened at their tips. The so prepared composite material allows one to investigate the effect of physical entrapment of CO 2 molecules within the specific adsorption sites of VACNTs composed of opened double walled carbon nanotubes (CNTs) and in specific adsorption sites created by spherically aggregated opened single walled carbon nanohorns. Combining 50 wt% of tip opened CNTs with tip opened CNHs increases the CO 2 adsorption capacity of this material by ∼24% at 30 bar and 298 K compared to opened CNHs alone.

Ultrasonic-assisted synthesis of superabsorbent hydrogels based on sodium lignosulfonate and their adsorption properties for Ni2.

PubMed

Wang, Xiaohong; Wang, Yingying; He, Shufu; Hou, Haiqian; Hao, Chen

2018-01-01

Nowadays, the attention of both academic and industrial research is paid to the novel materials based on renewable organic resources. Sodium lignosulphonate (SLS) is selected in this study to synthesize novel superabsorbent hydrogels by ultrasonic polymerization. The structure, morphology and stability of SLS-based hydrogel were confirmed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). Under the optimal condition, SLS-based hydrogel possesses the water absorbency of 1328g·g -1 in distilled water and 110g·g -1 in 0.9wt% NaCl solution. In addition, the prepared SLS-hydrogel as an adsorbent was applied to remove Ni 2+ from an aqueous solution in virtue of its low cost and favorable adsorption capacity. The various experimental conditions that influence the adsorption capacity were investigated such as temperature (20-60°C), pH (2.0-7.0), contact time (0-360min) and initial concentration of the Ni 2+ solution (100-600mg·L -1 ). Then the adsorption capability could reach 293mg·g -1 under optimal conditions. The results revealed that the adsorption behavior is spontaneous and endothermic. Furthermore, it was observed that the adsorption mechanism and adsorption equilibrium data obeyed pseudo-second-order kinetic and Freundlich models. Copyright © 2017 Elsevier B.V. All rights reserved.

Evaluation of the adsorption potential of eco-friendly activated carbon prepared from cherry kernels for the removal of Pb2+, Cd2+ and Ni2+ from aqueous wastes.

PubMed

Pap, Sabolč; Radonić, Jelena; Trifunović, Snežana; Adamović, Dragan; Mihajlović, Ivana; Vojinović Miloradov, Mirjana; Turk Sekulić, Maja

2016-12-15

Development, characterization and evaluation of the efficiency of cost-effective medium for the removal of Pb 2+ , Cd 2+ and Ni 2+ from aqueous systems, as a novel, eco-friendly solution for wastewater remediation were done. The precursors for low-cost adsorbent were lignocellulosic raw materials (sweet/sour cherry kernels), as industrial byproducts and components of organic solid waste. Activated carbon synthesis was carried out by thermochemical conversion (H 3 PO 4 , 500 °C) in the complete absence of inert atmosphere. Characterization of the activated carbon was performed by elemental analysis, FTIR, SEM, EDX and BET. BET surface area corresponds to 657.1 m 2  g -1 . The evaluation also included the influence of pH, contact time, solute concentration and adsorbent dose on the separation efficiency in the batch operational mode. The equilibrium and kinetic studies of adsorption were done. The maximum adsorption capacity of the activated carbon for Cd 2+ ions was calculated from the Langmuir isotherm and found to be 198.7 mg g -1 . Adsorption of Pb 2+ and Ni 2+ were better suitable to Freundlich model with the maximum adsorption capacity of 180.3 mg g -1 and 76.27 mg g -1 , respectively. The results indicate that the pseudo-second-order model best describes adsorption kinetic data. Based on desorption study results, activated carbon was successfully regenerated with HNO 3 for 3 cycles. In order to provide the results for basic cost-effective analysis, competing ion-effects in a real sample have been evaluated. Copyright © 2016 Elsevier Ltd. All rights reserved.

Carbon nanotube membranes with ultrahigh specific adsorption capacity for water desalination and purification.

PubMed

Yang, Hui Ying; Han, Zhao Jun; Yu, Siu Fung; Pey, Kin Leong; Ostrikov, Kostya; Karnik, Rohit

2013-01-01

Development of technologies for water desalination and purification is critical to meet the global challenges of insufficient water supply and inadequate sanitation, especially for point-of-use applications. Conventional desalination methods are energy and operationally intensive, whereas adsorption-based techniques are simple and easy to use for point-of-use water purification, yet their capacity to remove salts is limited. Here we report that plasma-modified ultralong carbon nanotubes exhibit ultrahigh specific adsorption capacity for salt (exceeding 400% by weight) that is two orders of magnitude higher than that found in the current state-of-the-art activated carbon-based water treatment systems. We exploit this adsorption capacity in ultralong carbon nanotube-based membranes that can remove salt, as well as organic and metal contaminants. These ultralong carbon nanotube-based membranes may lead to next-generation rechargeable, point-of-use potable water purification appliances with superior desalination, disinfection and filtration properties.

Carbon dots decorated magnetic ZnFe2O4 nanoparticles with enhanced adsorption capacity for the removal of dye from aqueous solution

NASA Astrophysics Data System (ADS)

Shi, Weilong; Guo, Feng; Wang, Huibo; Liu, Changan; Fu, Yijun; Yuan, Songliu; Huang, Hui; Liu, Yang; Kang, Zhenhui

2018-03-01

Widely used synthetic dyes have been caused serious environmental pollution. Therefore, it is imperative to acquire highly efficient adsorbent to remove them. Here, we report the carbon dots/ZnFe2O4 (CDs/ZFO) composites were prepared through a facile hydrothermal route for absorption removal of dye from aqueous solution. The characterizations reveal the CDs were uniformly deposited on the surfaces of ZFO nanoparticles in the composite. The CDs/ZFO composites as adsorbents exhibit enhanced adsorption behavior for methyl orange (MO) in comparison of pristine ZFO, in which the 5% CDs/ZFO (with the CDs mass content of 5 wt%) shows the highest absorption activity. Experimental studies on adsorption isotherms of MO over the 5% CDs/ZFO composite indicate that experimental data were found to follow Langmuir model with a monolayer adsorption capacity of 181.2 mg g-1. The corresponding adsorption kinetics was fitted well with the pseudo-second-order kinetic model. Moreover, thermodynamics parameters including ΔG°, ΔH° and ΔS° were tested, demonstrating that the adsorption of MO over CDs/ZFO composite was spontaneous and exothermic in nature. The remarkably increased adsorption performance of CDs/ZFO composites can be attributed to abundant oxygen-containing groups on the surface of CDs.

Nitroimidazoles adsorption on activated carbon cloth from aqueous solution.

PubMed

Ocampo-Pérez, R; Orellana-Garcia, F; Sánchez-Polo, M; Rivera-Utrilla, J; Velo-Gala, I; López-Ramón, M V; Alvarez-Merino, M A

2013-07-01

The objective of this study was to analyze the equilibrium and adsorption kinetics of nitroimidazoles on activated carbon cloth (ACC), determining the main interactions responsible for the adsorption process and the diffusion mechanism of these compounds on this material. The influence of the different operational variables, such as ionic strength, pH, temperature, and type of water (ultrapure, surface, and waste), was also studied. The results obtained show that the ACC has a high capacity to adsorb nitroimidazoles in aqueous solution. Electrostatic interactions play an important role at pH<3, which favors the repulsive forces between dimetridazole or metronidazole and the ACC surface. The formation of hydrogen bonds and dispersive interactions play the predominant role at higher pH values. Modifications of the ACC with NH3, K2S2O8, and O3 demonstrated that its surface chemistry plays a predominant role in nitroimidazole adsorption on this material. The adsorption capacity of ACC is considerably high in surface waters and reduced in urban wastewater, due to the levels of alkalinity and dissolved organic matter present in the different types of water. Finally, the results of applying kinetic models revealed that the global adsorption rate of dimetridazole and metronidazole is controlled by intraparticle diffusion. Copyright © 2013 Elsevier Inc. All rights reserved.

Effective adsorption of malachite green using magnetic barium phosphate composite from aqueous solution

NASA Astrophysics Data System (ADS)

Zhang, Fan; Wei, Zhong; Zhang, Wanning; Cui, Haiyan

2017-07-01

Magnetic Ba3(PO4)2/Fe3O4-nanoparticle (called BPFN) was prepared, characterized, and developed as a low-cost adsorbent for malachite green (MG) from aqueous solution. Factors such as adsorption temperature, pH of solution, dosage of adsorbent, adsorption kinetics and isotherms were investigated. The maximum adsorption capacity obtained in this work was 1639 mg g- 1 at 45 °C and pH 6. The adsorption process fitted the pseudo-first-order kinetic model and Langmuir isotherm model. Evidences from zeta potential, Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS) data revealed that the adsorption process was driven by electrostatic attraction, the interaction between Lewis base sbnd N(CH3)2 in MG and Lewis acid Ba sites of BPFN. In addition, the BPFN could be easily regenerated by a magnet and the adsorption capacity maintained at 70% after five cycles. The present study suggests that the BPFN had high potential of removing MG from wastewater.

Enhancing gas adsorption and separation capacity through ligand functionalization of microporous metal-organic framework structures.

PubMed

Zhao, Yonggang; Wu, Haohan; Emge, Thomas J; Gong, Qihan; Nijem, Nour; Chabal, Yves J; Kong, Lingzhu; Langreth, David C; Liu, Hui; Zeng, Heping; Li, Jing

2011-04-26

Hydroxyl- and amino- functionalized [Zn(BDC)(TED)(0.5)]·2DMF·0.2H(2)O leads to two new structures, [Zn(BDC-OH)(TED)(0.5)]·1.5DMF·0.3H(2)O and [Zn(BDC-NH(2))(TED)(0.5)]·xDMF·yH(2)O (BDC=terephthalic acid, TED=triethylenediamine, BDC-OH=2-hydroxylterephthalic acid, BDC-NH(2)=2-aminoterephthalic acid). Single-crystal X-ray diffraction and powder X-ray diffraction studies confirmed that the structures of both functionalized compounds are very similar to that of their parent structure. Compound [Zn(BDC)(TED)(0.5)]·2DMF·0.2H(2)O can be considered a 3D porous structure with three interlacing 1D channels, whereas both [Zn(BDC-OH)(TED)(0.5)]·1.5DMF·0.3H(2)O and [Zn(BDC-NH(2))(TED)(0.5)]·xDMF·yH(2)O contain only 1D open channels as a result of functionalization of the BDC ligand by the OH and NH(2) groups. A notable decrease in surface area and pore size is thus observed in both compounds. Consequently, [Zn(BDC)(TED)(0.5)]·2DMF·0.2H(2)O takes up the highest amount of H(2) at low temperatures. Interestingly, however, both [Zn(BDC-OH)(TED)(0.5)]·1.5DMF·0.3H(2)O and [Zn(BDC-NH(2))(TED)(0.5)]·xDMF·yH(2)O show significant enhancement in CO(2) uptake at room temperature, suggesting that the strong interactions between CO(2) and the functionalized ligands, indicating that surface chemistry, rather than porosity, plays a more important role in CO(2) adsorption. A comparison of single-component CO(2), CH(4), CO, N(2), and O(2) adsorption isotherms demonstrates that the adsorption selectivity of CO(2) over other small gases is considerably enhanced through functionalization of the frameworks. Infrared absorption spectroscopic measurements and theoretical calculations are also carried out to assess the effect of functional groups on CO(2) and H(2) adsorption potentials. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hydrogen production from food wastes and gas post-treatment by CO{sub 2} adsorption

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

Redondas, V.; Gomez, X., E-mail: xagomb@unileon.es; Garcia, S.

2012-01-15

of H{sub 2}S present in the bio-H{sub 2} exiting the column. Nevertheless, the concentration of H{sub 2}S was very low, and this co-adsorption did not affect the CO{sub 2} capture capacity of the activated carbon.« less

Enhanced chromium adsorption capacity via plasma modification of natural zeolites

NASA Astrophysics Data System (ADS)

Cagomoc, Charisse Marie D.; Vasquez, Magdaleno R., Jr.

2017-01-01

Natural zeolites such as mordenite are excellent adsorbents for heavy metals. To enhance the adsorption capacity of zeolite, sodium-exchanged samples were irradiated with 13.56 MHz capacitively coupled radio frequency (RF) argon gas discharge. Hexavalent chromium [Cr(VI)] was used as the test heavy metal. Pristine and plasma-treated zeolite samples were soaked in 50 mg/L Cr solution and the amount of adsorbed Cr(VI) on the zeolites was calculated at predetermined time intervals. Compared with untreated zeolite samples, initial Cr(VI) uptake was 70% higher for plasma-treated zeolite granules (50 W 30 min) after 1 h of soaking. After 24 h, all plasma-treated zeolites showed increased Cr(VI) uptake. For a 2- to 4-month period, Cr(VI) uptake increased about 130% compared with untreated zeolite granules. X-ray diffraction analyses between untreated and treated zeolite samples revealed no major difference in terms of its crystal structure. However, for plasma-treated samples, an increase in the number of surface defects was observed from scanning electron microscopy images. This increase in the number of surface defects induced by plasma exposure played a crucial role in increasing the number of active sorption sites on the zeolite surface.

Nickel adsorption by magnetic alginate microcapsules containing an extractant.

PubMed

Ngomsik, Audrey-Flore; Bee, Agnès; Siaugue, Jean-Michel; Cabuil, Valérie; Cote, Gérard

2006-05-01

The adsorption of heavy metals on biomaterials was investigated by studying the potential of alginate microcapsules containing an extractant (Cyanex 272) and magnetic nanoparticles (gamma-Fe2O3) for the adsorption of nickel (II) from aqueous solutions. A two-stage kinetics behaviour was observed with 70% of the maximum sorption capacity achieved within 8 h. An increase in nickel removal with increase in pH occurred, the maximum uptake capacity being around 0.42 mmol g-1 at pH 8. The adsorption isotherm (pH about 5.3) was obtained in a wide range of initial nickel concentrations; the experimental data were fitted by a Langmuir model and the qmax value was estimated to be 0.52 mmol g-1. Moreover, including magnetic particles in the microcapsules allowed easy isolation of the beads from the aqueous solutions after the sorption process. Magnetic microcapsules are then suitable for the development of efficient biosorbents for removal and recovery of heavy metals from wastewater using magnetic separation.

Experimental study on removals of SO2 and NO(x) using adsorption of activated carbon/microwave desorption.

PubMed

Ma, Shuang-Chen; Yao, Juan-Juan; Gao, Li; Ma, Xiao-Ying; Zhao, Yi

2012-09-01

Experimental studies on desulfurization and denitrification were carried out using activated carbon irradiated by microwave. The influences of the concentrations of nitric oxide (NO) and sulfur dioxide (SO2), the flue gas coexisting compositions, on adsorption properties of activated carbon and efficiencies of desulfurization and denitrification were investigated. The results show that adsorption capacity and removal efficiency of NO decrease with the increasing of SO2 concentrations in flue gas; adsorption capacity of NO increases slightly first and drops to 12.79 mg/g, and desulfurization efficiency descends with the increasing SO2 concentrations. Adsorption capacity of SO2 declines with the increasing of O2 content in flue gas, but adsorption capacity of NO increases, and removal efficiencies of NO and SO2 could be larger than 99%. Adsorption capacity of NO declines with the increase of moisture in the flue gas, but adsorption capacity of SO2 increases and removal efficiencies of NO and SO2 would be relatively stable. Adsorption capacities of both NO and SO2 decrease with the increasing of CO2 content; efficiencies of desulfurization and denitrification augment at the beginning stage, then start to fall when CO2 content exceeds 12.4%. The mechanisms of this process are also discussed. The prominent SO2 and NOx treatment techniques in power plants are wet flue gas desulfurization (FGD) and the catalytic decomposition method like selective catalytic reduction (SCR) or nonselective catalytic reduction (NSCR). However, these processes would have some difficulties in commercial application due to their high investment, requirement of expensive catalysts and large-scale equipment, and so on. A simple SO2 and NOx reduction utilizing decomposition by microwave energy method can be used. The pollutants control of flue gas in the power plants by the method of microwave-induced decomposition using adsorption of activated carbon/microwave desorption can meet the

Study on the adsorption of bacteria in ceramsite and their synergetic effect on adsorption of heavy metals.

PubMed

Qiu, Shan; Ma, Fang; Huang, Xu; Xu, Shanwen

2014-01-01

In this paper, heavy metal adsorption by ceramsite with or without Bacillus subtilis (B. subtilis) immobilization was studied, and the synergetic effect of ceramsite and bacteria was discussed in detail. To investigate the roles of the micro-pore structure of ceramsite and bacteria in removing heavy metals, the amount of bacteria immobilized on the ceramsite was determined and the effect of pH was evaluated. It was found that the immobilization of B. subtilis on the ceramsite was attributed to the electrostatic attraction and covalent bond. The scanning electron microscopy results revealed that, with the presence of ceramsite, there was the conglutination of B. subtilis cells due to the cell outer membrane dissolving. In addition, the B. subtilis immobilized ceramsite showed a different adsorption capacity for different heavy metals, with the adsorption capacity ranking of La(3+) > Cu(2+) > Mg(2+) > Na(+).

Surfactant-free synthesis of octahedral ZnO/ZnFe2O4 heterostructure with ultrahigh and selective adsorption capacity of malachite green

NASA Astrophysics Data System (ADS)

Liu, Jue; Zeng, Min; Yu, Ronghai

2016-05-01

A new octahedral ZnO/ZnFe2O4 heterostructure has been fabricated through a facile surfactant-free solvothermal method followed by thermal treatment. It exhibits a record-high adsorption capacity (up to 4983.0 mg·g-1) of malachite green (MG), which is a potentially harmful dye in prevalence and should be removed from wastewater and other aqueous solutions before discharging into the environment. The octahedral ZnO/ZnFe2O4 heterostructure also demonstrates strong selective adsorption towards MG from two kinds of mixed solutions: MG/methyl orange (MO) and MG/rhodamine B (RhB) mixtures, indicating its promise in water treatment.

Surfactant-free synthesis of octahedral ZnO/ZnFe2O4 heterostructure with ultrahigh and selective adsorption capacity of malachite green

PubMed Central

Liu, Jue; Zeng, Min; Yu, Ronghai

2016-01-01

A new octahedral ZnO/ZnFe2O4 heterostructure has been fabricated through a facile surfactant-free solvothermal method followed by thermal treatment. It exhibits a record-high adsorption capacity (up to 4983.0 mg·g−1) of malachite green (MG), which is a potentially harmful dye in prevalence and should be removed from wastewater and other aqueous solutions before discharging into the environment. The octahedral ZnO/ZnFe2O4 heterostructure also demonstrates strong selective adsorption towards MG from two kinds of mixed solutions: MG/methyl orange (MO) and MG/rhodamine B (RhB) mixtures, indicating its promise in water treatment. PMID:27142194

Simultaneous adsorption of Cd²⁺ and BPA on amphoteric surfactant activated montmorillonite.

PubMed

Liu, Chongmin; Wu, Pingxiao; Zhu, Yajie; Tran, Lytuong

2016-02-01

The study mainly investigated the simultaneous adsorption of bisphenol A (BPA) and Cd(2+) from aqueous solution on octadecane-betaine modified montmorillonite (BS-Mt). The characteristics of the obtained materials were analyzed by X-ray diffraction (XRD), Fourier-transform infrared (FTIR), Specific surface area (BET) and Scanning electron microscopy/Energy disperse spectroscopy (SEM/EDS), confirming that BS-18 was successfully introduced into Mt. Also, factors including initial solution pH, initial Cd(2+)/BPA concentration, contact time and adsorbent dosage on the adsorption processes were shown to be crucial for Cd(2+) adsorption, whereas had negligible effects on BPA adsorption. In this study, we found that pseudo-second-order model fitted well with the adsorption kinetic studies for both Cd(2+) and BPA with an equilibrium time of 24 h. The Cd(2+) and BPA adsorption isotherm could be well described by Freundlich model and Langmuir model, respectively. On the basis of kinetic models, the maximum adsorption capacity of Cd(2+) in aqueous solution was slightly enhanced after modification, indicating that Cd(2+) adsorption on BS-Mt was mainly attributed to direct electrostatic attraction and the chelate reaction, while the dramatic enhancement of maximum adsorption capacity for BPA was due to the hydrophobic interaction. Copyright © 2015 Elsevier Ltd. All rights reserved.

[Preparation of HDTMA-modified Zeolite and Its Performance in Nitro-phenol Adsorption from Wastewaters].

PubMed

Guo, Jun-yuan; Wang, Bin

2016-05-15

In this study, natural zeolite was modified by HDTMA. Effects of the modified conditions, HDTMA-modified zeolite doses, solution pH values, and reaction time on nitro-phenol removal were investigated, and the adsorption kinetics and isotherms were discussed. Compared with natural zeolite, HDTMA-modified zeolite showed better performance in nitro-phenol removal. An adsorption capacity of 2.53 mg · g⁻¹ was achieved when the concentration of HDTMA solution (pH = 10) was 1.2% in preparation of modified zeolite. This adsorption capacity was higher than that obtained by natural zeolite (0.54 mg · g⁻¹). In adsorption tests, when HDTMA- modified zeolite dose was adjusted to 8 g · L⁻¹, the removal efficiency of nitro-phenol reached 93.9% after 90 min reaction, with wastewater pH of 6. Furthermore, the nitro-phenol adsorption process could be well fitted to the pseudo-first-order kinetics model (R² > 0.90), whereas the adsorption isotherm results indicated that Langmuir model provided the best fitting for the equilibrium data at different temperatures, with R² of higher than 0.90.

Comparative study on the effect of H2 pre-adsorption on CO oxidation in O2-poor atmosphere over Au/TiO2 and TiO2: Temperature programmed surface reaction by a multiplexed mass spectrometer testing

NASA Astrophysics Data System (ADS)

Si, Ruiru; Liu, Junfeng; Zhang, Yujuan; Chen, Xun; Dai, Wenxin; Fu, Xianzhi

2016-11-01

The behaviors of H2 pre-adsorption on CO oxidation in an O2-poor stream containing a trace H2O over Au/TiO2 and TiO2 have been investigated by a temperature programmed surface reaction testing, respectively. It was found that the H2 pre-adsorption could keep CO oxidation without H2O consumption over Au/TiO2, but suppress CO oxidation over TiO2. The chemisorption testing showed that the H2 adsorption at Au/TiO2 could benefit to the formation of Ti-bonded hydroxyl species (Ti4+-OH), while the H2 adsorption at TiO2 would consume the Ti-bonded hydroxyl species and form the bridge hydroxyl species (Ti4+-OH-Ti4+). These results show that only the Ti-bonded hydroxyl species (not all kinds of hydroxyl species) could act as the active species of oxidizing CO. Furthermore, it is suggested that the dissociative hydrogen adsorbed at Au sites could activate the lattice oxygen of TiO2 to form the active Ti-bonded hydroxyl species (hydrogen spillover from Au to TiO2), which exhibit a strong reducibility than the H directly adsorbed at TiO2.

Gas-phase formaldehyde adsorption isotherm studies on activated carbon: correlations of adsorption capacity to surface functional group density.

PubMed

Carter, Ellison M; Katz, Lynn E; Speitel, Gerald E; Ramirez, David

2011-08-01

Formaldehyde (HCHO) adsorption isotherms were developed for the first time on three activated carbons representing one activated carbon fiber (ACF) cloth, one all-purpose granular activated carbon (GAC), and one GAC commercially promoted for gas-phase HCHO removal. The three activated carbons were evaluated for HCHO removal in the low-ppm(v) range and for water vapor adsorption from relative pressures of 0.1-0.9 at 26 °C where, according to the IUPAC isotherm classification system, the adsorption isotherms observed exhibited Type V behavior. A Type V adsorption isotherm model recently proposed by Qi and LeVan (Q-L) was selected to model the observed adsorption behavior because it reduces to a finite, nonzero limit at low partial pressures and it describes the entire range of adsorption considered in this study. The Q-L model was applied to a polar organic adsorbate to fit HCHO adsorption isotherms for the three activated carbons. The physical and chemical characteristics of the activated carbon surfaces were characterized using nitrogen adsorption isotherms, X-ray photoelectron spectroscopy (XPS), and Boehm titrations. At low concentrations, HCHO adsorption capacity was most strongly related to the density of basic surface functional groups (SFGs), while water vapor adsorption was most strongly influenced by the density of acidic SFGs.

Superior lithium adsorption and required magnetic separation behavior of iron-doped lithium ion-sieves

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

Wang, Shulei; Zheng, Shili; Wang, Zheming

The recent research on adsorption-based lithium recovery from lithium-containing solutions has been centred on adsorption capacity and separation of lithium ion-sieves powder from solutions. Herein, an effective iron-doped lithium titanium oxide (Fe-doped Li2TiO3) was synthesized by Fe-doping via solid state reactions followed by acid treatment to form iron-doped lithium ion-sieves (Fe/Ti-x(H)). The resulting solid powder displays both superior adsorption capacity of lithium and high separation efficiency of the adsorbent from the solutions. SEM imaging and BET surface area measurement results showed that at Fe doping levels x0.15, Fe-doping led to grain shrinkage as compared to Li2TiO3 and at the samemore » time the BET surface area increased. The Fe/Ti-0.15(H) exhibited saturated magnetization values of 13.76 emu g-1, allowing effective separation of the material from solid suspensions through the use of a magnet. Consecutive magnetic separation results suggested that the Fe/Ti-0.15(H) powders could be applied at large-scale and continuously removed from LiOH solutions with separation efficiency of 96% or better. Lithium adsorption studies indicated that the equilibrium adsorption capacity of Fe/Ti-0.15(H) in LiOH 2 solutions (1.8 g L-1 Li, pH 12) reached 53.3 mg g-1 within 24 h, which was higher than that of pristine Li2TiO3 (50.5 mg g-1) without Fe doping. Competitive adsorption and regeneration results indicated that the Fe/Ti-0.15(H) possessed a high selectivity for Li with facile regeneration. Therefore, it could be expected that the iron-doped lithium ion-sieves have practical applicability potential for large scale lithium extraction and recovery from lithium-bearing solutions.« less

Adsorption of reovirus by minerals and soils.

PubMed Central

Moore, R S; Taylor, D H; Reddy, M M; Sturman, L S

1982-01-01

Adsorption of [35S]methionine-labeled reovirus by 30 dry soils, minerals, and finely ground rocks suspended in synthetic freshwater at pH 7 was investigated to determine the conditions necessary for optimum virus removal during land application of wastewaters. All of the minerals and soils studied were excellent adsorbents of reovirus, with greater than 99% of the virus adsorbed after 1 h at 4 degrees C. Thereafter, virus remaining in suspension was significantly inactivated, and within 24 h a three to five log10 reduction in titer occurred. The presence of divalent cations, i.e., Ca2+ and Mg2+, in synthetic freshwater enhanced removal, whereas soluble organic matter decreased the amount of virus adsorbed in secondary effluent. The amount of virus adsorbed by these substrates was inversely correlated with the amount of organic matter, capacity to adsorb cationic polyelectrolyte, and electrophoretic mobility. Adsorption increased with increasing available surface area, as suspended infectivity was reduced further by the more finely divided substrates. However, the organic content of the soils reduced the level of infectious virus adsorbed below that expected from surface area measurements alone. The inverse correlation between virus adsorption and substrate capacity for cationic polyelectrolyte indicates that the adsorption of infectious reovirus particles is predominately a charged colloidal particle-charged surface interaction. Thus, adsorption of polyelectrolyte may be useful in predicting the fate of viruses during land application of sewage effluents and sludges. PMID:7149717

Organic Adsorption Capacity of Aluminum for Potential Mars Sample Return Contamination Analysis

NASA Astrophysics Data System (ADS)

Skoog, E. J.; Tuite, M. L., Jr.; Williford, K. H.

2017-12-01

The NASA Mars 2020 rover will sample martian rock and regolith as it searches for biosignatures and chemical potential for life. Possible contamination of martian samples by Earth-derived organic and inorganic materials poses a challenge to the ultimate goal of determining whether features detected within samples are of martian origin. To address this issue, Mars 2020 will implement a contamination knowledge strategy that includes "witness blanks": special sample tubes that contain multiple "getter" materials designed to witness any ambient contamination in the environment during sampling events on Mars. One getter material being considered for use inside witness tubes is aluminum foil. Here we present data from a series of experiments to evaluate the capacity of aluminum foil to adsorb organics and release them by solvent extraction. Strips of clean aluminum foil were suspended in closed vials containing 0.15 mg of pyrene and heated to 50°C to provide a bounding case for ambient pyrene concentration. Another set of foil strips in vials was stored at -20°C to better simulate martian conditions. After ten weeks, these foil strips were exposed to pyrene at additive 15 minute increments to test the time dependence of pyrene adsorption at -20°C. Foil strips were removed from vials and subjected to solvent extraction gas chromatography mass spectrometry. Preliminary results suggest that the pyrene adsorption capacity of aluminum at 50°C is 1-10 ng/cm2 after 24 hours. Further research will test the adsorption capacity of aluminum at varying temperatures, varying times, and varying organic compositions.

Synthesis and characterization of Silica/polyvinyl imidazole/H2PO4-core-shell nanoparticles as recyclable adsorbent for efficient scavenging of Sm(III) and Dy(III) from water.

PubMed

Ettehadi Gargari, Jafar; Sid Kalal, Hossein; Shakeri, Alireza; Khanchi, Alireza

2017-11-01

In this study, we used Silica/polyvinyl imidazole core-shell nanoparticles impregnated with sodium dihydrogen phosphate (SiO 2 /PVI/H 2 PO 4 - NPs) for adsorption of samarium and dysprosium ions from aqueous solutions. The effects of the pH, adsorbent dose, contact time, and initial concentration of the adsorbate on the Core-shell nanoparticles adsorption capacity have been studied. The pH value for maximum removal of Sm (III) and Dy (III) on the core-shell nanoparticles surface were found to be 4. The saturated capacity of SiO 2 /PVI/H 2 PO 4 - NPs was up to 160mg.g -1 and 150mg.g -1 at 25°C for Sm (III) and Dy (III) ions respectively. The obtained uptake data were analyzed by the Langmuir and Freundlich equations using a linearized correlation coefficient at room temperature. The Freundlich isotherm was found to fit well with the equilibrium data. The adsorption kinetics could be modeled by a pseudo-second-order rate expression. Thermodynamic investigation revealed the adsorption process of the studied ions is entropy driven. Furthermore, the performance of regeneration and reutilization were studied. The adsorbed Sm (III) and Dy (III) can be desorbed by 0.5mol/L HCl, with the desorption percentage of 90% for Sm (III) and Dy (III). After five adsorption-desorption cycles, the adsorption capacity shows a slight decrease (about 15%), implying that the SiO 2 /PVI/H 2 PO 4 - NPs can be used as an effective adsorbent for the removal and recovery of Sm(III) and Dy(III) from aqueous solution. The colloid stability of the SiO 2 /PVI/H 2 PO 4 - NPs was investigated by dynamic light scattering measurements. The SiO 2 /PVI/H 2 PO 4 - NPs are stable in adsorption media after five adsorption - desorption cycles. The high stability of SiO 2 /PVI/H 2 PO 4 - NPs can be attributed to steric stabilization by polyvinyl imidazole adsorbed on SiO 2 nanoparticle surfaces. Copyright © 2017 Elsevier Inc. All rights reserved.

Adsorption of SO2 onto oxidized and heat-treated activated carbon fibers (ACFs)

USGS Publications Warehouse

Daley, M.A.; Mangun, C.L.; DeBarr, J.A.; Riha, S.; Lizzio, A.A.; Donnals, G.L.; Economy, J.

1997-01-01

Oxidation of the ACFs, using an aqueous oxidant, decreased their adsorption capacity for SO2 from flue gas due to a decrease in pore volume and repulsion of the SO2 from acidic surface groups. If these samples were heat-treated to desorb the oxygen containing function groups, the amount of SO2 adsorption increased. This increase in adsorption capacity was directly correlated to the amount of CO2 evolved during heat-treatment of the oxidized ACFs. The amount of SO2 adsorbed for these samples was related to the pore size, pore surface chemistry and pore volume. This analysis is explained in more detail in this paper.

Poly(hydroxyethyl methacrylate-co-methacryloylglutamic acid) nanospheres for adsorption of Cd2+ ions from aqueous solutions

NASA Astrophysics Data System (ADS)

Esen, Cem; Şenay, Raziye Hilal; Feyzioğlu, Esra; Akgöl, Sinan

2014-02-01

Poly(2-hydroxyethyl methacrylate-co- N-methacryloyl-( l)-glutamic acid) p(HEMA-MAGA) nanospheres have been synthesized, characterized, and used for the adsorption of Cd2+ ions from aqueous solutions. Nanospheres were prepared by surfactant free emulsion polymerization. The p(HEMA-MAGA) nanospheres were characterized by SEM, FTIR, zeta size, and elemental analysis. The specific surface area of nanospheres was found to be 1,779 m2/g. According to zeta size analysis results, average size of nanospheres is 147.3 nm with poly-dispersity index of 0.200. The goal of this study was to evaluate the adsorption performance of p(HEMA-MAGA) nanospheres for Cd2+ ions from aqueous solutions by a series of batch experiments. The Cd2+ concentration was determined by inductively coupled plasma-optical emission spectrometer. Equilibrium sorption experiments indicated a Cd2+ uptake capacity of 44.2 mg g-1 at pH 4.0 at 25 °C. The adsorption of Cd2+ ions increased with increasing pH and reached a plateau value at around pH 4.0. The data were successfully modeled with a Langmuir equation. A series of kinetics experiments was then carried out and a pseudo-second order equation was used to fit the experimental data. Desorption experiments which were carried out with nitric acid showed that the p(HEMA-MAGA) nanospheres could be reused without significant losses of their initial properties in consecutive adsorption and elution operations.

Zeolite Y Adsorbents with High Vapor Uptake Capacity and Robust Cycling Stability for Potential Applications in Advanced Adsorption Heat Pumps.

PubMed

Li, Xiansen; Narayanan, Shankar; Michaelis, Vladimir K; Ong, Ta-Chung; Keeler, Eric G; Kim, Hyunho; McKay, Ian S; Griffin, Robert G; Wang, Evelyn N

2015-01-01

Modular and compact adsorption heat pumps (AHPs) promise an energy-efficient alternative to conventional vapor compression based heating, ventilation and air conditioning systems. A key element in the advancement of AHPs is the development of adsorbents with high uptake capacity, fast intracrystalline diffusivity and durable hydrothermal stability. Herein, the ion exchange of NaY zeolites with ingoing Mg 2+ ions is systematically studied to maximize the ion exchange degree (IED) for improved sorption performance. It is found that beyond an ion exchange threshold of 64.1%, deeper ion exchange does not benefit water uptake capacity or characteristic adsorption energy, but does enhance the vapor diffusivity. In addition to using water as an adsorbate, the uptake properties of Mg,Na-Y zeolites were investigated using 20 wt.% MeOH aqueous solution as a novel anti-freeze adsorbate, revealing that the MeOH additive has an insignificant influence on the overall sorption performance. We also demonstrated that the labscale synthetic scalability is robust, and that the tailored zeolites scarcely suffer from hydrothermal stability even after successive 108-fold adsorption/desorption cycles. The samples were analyzed using N 2 sorption, 27 Al/ 29 Si MAS NMR spectroscopy, ICP-AES, dynamic vapor sorption, SEM, Fick's 2 nd law and D-R equation regressions. Among these, close examination of sorption isotherms for H 2 O and N 2 adsorbates allows us to decouple and extract some insightful information underlying the complex water uptake phenomena. This work shows the promising performance of our modified zeolites that can be integrated into various AHP designs for buildings, electronics, and transportation applications.

Application of activated carbon modified by acetic acid in adsorption and separation of CO2 and CH4

NASA Astrophysics Data System (ADS)

Song, Xue; Wang, Li'ao; Zeng, Yunmin; Zhan, Xinyuan; Gong, Jian; Li, Tong

2018-03-01

Compared with the methods to modify the activated carbons by alkalis for gas adsorption, fewer studies of that by organic acids have been reported. The acid modified activated carbons are usually utilized to treat wastewater, whereas the application in the separation of CO2/CH4 has less been studied. In this study, acetic acid was used to modify activated carbon. N2 adsorption/desorption isotherms and FT-IR were adopted to describe the properties of the samples. According to the adsorption data of pure gas component at 298 K, the gas adsorbed amount and the selectivity on the modified samples were larger than that on the raw sample. Besides, the adsorbed amount of CO2 and the selectivity on 15H-AC in the adsorption breakthrough experiments showed better performance. The results confirm that the method to modify the activated carbons with acetic acid is feasible to improve the adsorption capacity and the separation effect of CO2/CH4.

A study in the adsorption of Fe(2+) and NO(3)(-) on pine needles based hydrogels.

PubMed

Chauhan, Ghanshyam S; Chauhan, Sandeep; Kumar, Sunil; Kumari, Anita

2008-09-01

Novel supports for use as cation and anion adsorbents were prepared from lignocellulosics using pine needles and their carboxymethylated forms by network/hydrogel formation with acrylamide and N,N-methylene bisacrylamide. The hydrogels thus prepared were further functionalized by partial alkaline hydrolysis with 0.5 N NaOH and were characterized by FTIR, SEM and nitrogen analysis. Adsorption of Fe(2+) on these hydrogels was carried as a function of time, temperature, pH and ionic strength. The hydrogel having the maximum adsorption capacity was loaded with Fe(2+) at the conditions those afforded maximum uptake and was used as novel anionic adsorbent for NO(3)(-). The water uptake capacities and biodegradability of the hydrogels before and after the ion loading was studied to evaluate the possible end-uses of these hydrogels as alternate materials in the removal of ionic species from water.

[Preparation of Pb2+ imprinted acrylic acid-co-styrene and analysis of its adsorption properties by FAAS].

PubMed

Shawket, Abliz; Abdiryim, Supahun; Wang, Ji-De; Ismayil, Nurulla

2011-06-01

With lead ion template, acrylic acid as functional monomer, potassium persulfate as initiator, strytrene as framework monomer, lead ion imprinted polymers (Pb(II)-IIPs) were prepared using free emulsion polymerization method. The structure and morphology of the polymers were analyzed by UV-spectra, FTIR and scanning electron microscopy. The adsorption/ desorption and selectivity for Pb2+ were investigated by flame atomic absorption spectrometry (FAAS) as the detection means. The results show that compared with non-imprinted polymers(NIPs), the Pb(II)-IIPs had higher specific adsorption properties and selective recognition ability for Pb(II). The relative selectivity coefficient of Pb(II)-IIPs for Pb(II) was 6.25, 6.18, 6.25 and 6.38 in the presence of Cd(II), Cu(II), Mn(II) and Zn(II) interferences, respectively. The absorption rate was the best at the pH of adsorbent solution of 6, Adsorption rate reached 96% during the 2.5 h static adsorption time. Using 3.0 mol x L(-1) HCI as the best desorption solvent to desorb the adsorbents, the desorbtion rate reached 98%. Under the best adsorption conditions, the adsorption capacity of Pb(II)-IIPs for Pb(II) was found to be 40. mg x g(-1).

Amine-functionalized PVA-co-PE nanofibrous membrane as affinity membrane with high adsorption capacity for bilirubin.

PubMed

Wang, Wenwen; Zhang, Hao; Zhang, Zhifeng; Luo, Mengying; Wang, Yuedan; Liu, Qiongzhen; Chen, Yuanli; Li, Mufang; Wang, Dong

2017-02-01

In this study, poly(vinyl alcohol-co-ethylene) (PVA-co-PE) nanofibrous membrane was activated by sodium hydroxide and cyanuric chloride, and then the activated membranes were functionalized by 1,3-propanediamine, hexamethylenediamine and diethylenetriamine to be affinity membranes for bilirubin removal, respectively. The chemical structures and morphologies of membranes were investigated by SEM, FTIR and XPS. And the adsorption ability of different amine-functionalized nanofibrous membranes for bilirubin was characterized. Furthermore, the effects of temperature, initial concentration of bilirubin, NaCl concentration and BSA concentration on the adsorption capacity for bilirubin of diethylenetriamine-functionalized nanofibrous membrane were studied. Results indicated that the adsorption capacity for bilirubin of diethylenetriamine-functionalized nanofibrous membrane could reach 85mg/g membrane when the initial bilirubin concentration was 200mg/L while the adsorption capacity could be increased to 110mg/g membrane if the initial bilirubin concentration was more than 400mg/L. The dynamic adsorption of diethylenetriamine-functionalized nanofibrous membrane showed that the ligands of amine groups on the membrane surface could be used as far as possible by recirculating the plasma with certain flow rates. Therefore, the diethylenetriamine-functionalized PVA-co-PE nanofibrous membrane possessed high adsorption capacity for bilirubin and it can be candidate as affinity membrane for bilirubin removal. Copyright © 2016. Published by Elsevier B.V.

Adsorption of Copper Ion using Acrylic Acid-g-Polyaniline in Aqueous Solution

NASA Astrophysics Data System (ADS)

Kamarudin, Sabariah; Mohammad, Masita

2018-04-01

A conductive polymer, polyaniline (PANI) has unique electrical behaviour, stable in the environment, easy synthesis and have wide application in various fields. Modification of PANI in order to improve its adsorption capacity has been done. In this study, the polyaniline-grafted acrylic acid has been prepared and followed by adsorption of copper ion in aqueous solution. Acrylic acid, PANI and acrylic acid-g-polyaniline (Aag-PANI) were characterized by FTIR and SEM to determine its characteristic. The adsorption capacity was investigated to study the removal capacity of Cu ion from aqueous solution. Two parameters were selected which are pH (2, 4 and 6) and initial metal ion concentration (50 mg/L, 100 mg/L and 200 mg/L). The maximum adsorption capacity for PANI and Aag-PANI are 1.7 mg/g and 64.6 mg/g, respectively, at an initial concentration of 100 mg/L. The Langmuir adsorption isotherm model and Freundlich adsorption isotherm model have been used and showed that it is heterolayer adsorption by follows the Freundlich isotherm model.

Batch soil adsorption and column transport studies of 2,4-dinitroanisole (DNAN) in soils

NASA Astrophysics Data System (ADS)

Arthur, Jennifer D.; Mark, Noah W.; Taylor, Susan; Šimunek, J.; Brusseau, M. L.; Dontsova, Katerina M.

2017-04-01

The explosive 2,4,6-trinitrotoluene (TNT) is currently a main ingredient in munitions; however the compound has failed to meet the new sensitivity requirements. The replacement compound being tested is 2,4-dinitroanisole (DNAN). DNAN is less sensitive to shock, high temperatures, and has good detonation characteristics. However, DNAN is more soluble than TNT, which can influence transport and fate behavior and thus bioavailability and human exposure potential. The objective of this study was to investigate the environmental fate and transport of DNAN in soil, with specific focus on sorption processes. Batch and column experiments were conducted using soils collected from military installations located across the United States. The soils were characterized for pH, electrical conductivity, specific surface area, cation exchange capacity, and organic carbon content. In the batch rate studies, change in DNAN concentration with time was evaluated using the first order equation, while adsorption isotherms were fitted using linear and Freundlich equations. Solution mass-loss rate coefficients ranged between 0.0002 h- 1 and 0.0068 h- 1. DNAN was strongly adsorbed by soils with linear adsorption coefficients ranging between 0.6 and 6.3 L g- 1, and Freundlich coefficients between 1.3 and 34 mg1 - n Ln kg- 1. Both linear and Freundlich adsorption coefficients were positively correlated with the amount of organic carbon and cation exchange capacity of the soil, indicating that similar to TNT, organic matter and clay minerals may influence adsorption of DNAN. The results of the miscible-displacement column experiments confirmed the impact of sorption on retardation of DNAN during transport. It was also shown that under flow conditions DNAN transforms readily with formation of amino transformation products, 2-ANAN and 4-ANAN. The magnitudes of retardation and transformation observed in this study result in significant attenuation potential for DNAN, which would be anticipated to

Batch soil adsorption and column transport studies of 2,4-dinitroanisole (DNAN) in soils.

PubMed

Arthur, Jennifer D; Mark, Noah W; Taylor, Susan; Šimunek, J; Brusseau, M L; Dontsova, Katerina M

2017-04-01

The explosive 2,4,6-trinitrotoluene (TNT) is currently a main ingredient in munitions; however the compound has failed to meet the new sensitivity requirements. The replacement compound being tested is 2,4-dinitroanisole (DNAN). DNAN is less sensitive to shock, high temperatures, and has good detonation characteristics. However, DNAN is more soluble than TNT, which can influence transport and fate behavior and thus bioavailability and human exposure potential. The objective of this study was to investigate the environmental fate and transport of DNAN in soil, with specific focus on sorption processes. Batch and column experiments were conducted using soils collected from military installations located across the United States. The soils were characterized for pH, electrical conductivity, specific surface area, cation exchange capacity, and organic carbon content. In the batch rate studies, change in DNAN concentration with time was evaluated using the first order equation, while adsorption isotherms were fitted using linear and Freundlich equations. Solution mass-loss rate coefficients ranged between 0.0002h -1 and 0.0068h -1 . DNAN was strongly adsorbed by soils with linear adsorption coefficients ranging between 0.6 and 6.3Lg -1 , and Freundlich coefficients between 1.3 and 34mg 1 - n L n kg -1 . Both linear and Freundlich adsorption coefficients were positively correlated with the amount of organic carbon and cation exchange capacity of the soil, indicating that similar to TNT, organic matter and clay minerals may influence adsorption of DNAN. The results of the miscible-displacement column experiments confirmed the impact of sorption on retardation of DNAN during transport. It was also shown that under flow conditions DNAN transforms readily with formation of amino transformation products, 2-ANAN and 4-ANAN. The magnitudes of retardation and transformation observed in this study result in significant attenuation potential for DNAN, which would be anticipated to

Antifungal activities against toxigenic Fusarium specie and deoxynivalenol adsorption capacity of ion-exchanged zeolites.

PubMed

Savi, Geovana D; Cardoso, William A; Furtado, Bianca G; Bortolotto, Tiago; Zanoni, Elton T; Scussel, Rahisa; Rezende, Lucas F; Machado-de-Ávila, Ricardo A; Montedo, Oscar R K; Angioletto, Elidio

2018-03-04

Zeolites are often used as adsorbents materials and their loaded cations can be exchanged with metal ions in order to add antimicrobial properties. The aim of this study was to use the 4A zeolite and its derived ion-exchanged forms with Zn 2+ , Li + , Cu 2+ and Co 2+ in order to evaluate their antifungal properties against Fusarium graminearum, including their capacity in terms of metal ions release, conidia germination and the deoxynivalenol (DON) adsorption. The zeolites ion-exchanged with Li + , Cu 2+ , and Co 2+ showed an excellent antifungal activity against F. graminearum, using an agar diffusion method, with a zone of inhibition observed around the samples of 45.3 ± 0.6 mm, 25.7 ± 1.5 mm, and 24.7 ± 0.6 mm, respectively. Similar results using agar dilution method were found showing significant growth inhibition of F. graminearum for ion-exchanged zeolites with Zn 2+ , Li + , Cu 2+ , and Co 2+ . The fungi growth inhibition decreased as zeolite-Cu 2+ >zeolite-Li + >zeolite-Co 2+ >zeolite-Zn 2+ . In addition, the conidia germination was strongly affected by ion-exchanged zeolites. With regard to adsorption capacity, results indicate that only zeolite-Li + were capable of DON adsorption significantly (P < 0.001) with 37% at 2 mg mL -1 concentration. The antifungal effects of the ion-exchanged zeolites can be ascribed to the interactions of the metal ions released from the zeolite structure, especially for zeolite-Li + , which showed to be a promising agent against F. graminearum and its toxin.

Support effects in single atom iron catalysts on adsorption characteristics of toxic gases (NO2, NH3, SO3 and H2S)

NASA Astrophysics Data System (ADS)

Gao, Zhengyang; Yang, Weijie; Ding, Xunlei; Lv, Gang; Yan, Weiping

2018-04-01

The effects of support on gas adsorption is crucial for single atom catalysts design and optimization. To gain insight into support effects on gas adsorption characteristics, a comprehensive theoretical study was performed to investigate the adsorption characteristics of toxic gases (NO2, NH3, SO3 and H2S) by utilizing single atom iron catalysts with three graphene-based supports. The adsorption geometry, adsorption energy, electronic and magnetic properties of the adsorption system have been explored. Additionally, the support effects have been analyzed through d-band center and Fermi softness, and thermodynamic analysis has been performed to consider the effect of temperature on gas adsorption. The support effects have a remarkable influence on the adsorption characteristics of four types of toxic gases which is determined by the electronic structure of graphene-based support, and the electronic structure can be characterized by Fermi softness of catalysts. Fermi softness and uplift height of Fe atom could be good descriptors for the adsorption activity of single atom iron catalysts with graphene-based supports. The findings can lay a foundation for the further study of graphene-based support effects in single atom catalysts and provide a guideline for development and design of new graphene-based support materials utilizing the idea of Fermi softness.

Adsorption separation of carbon dioxide from flue gas by a molecularly imprinted adsorbent.

PubMed

Zhao, Yi; Shen, Yanmei; Ma, Guoyi; Hao, Rongjie

2014-01-01

CO2 separation by molecularly imprinted adsorbent from coal-fired flue gas after desulfurization system has been studied. The adsorbent was synthesized by molecular imprinted technique, using ethanedioic acid, acrylamide, and ethylene glycol dimethacrylate as the template, functional monomer, and cross-linker, respectively. According to the conditions of coal-fired flue gas, the influencing factors, including adsorption temperature, desorption temperature, gas flow rate, and concentrations of CO2, H2O, O2, SO2, and NO, were studied by fixed bed breakthrough experiments. The experimental conditions were optimized to gain the best adsorption performance and reduce unnecessary energy consumption in future practical use. The optimized adsorption temperature, desorption temperature, concentrations of CO2, and gas flow rate are 60 °C, 80 °C, 13%, and 170 mL/min, respectively, which correspond to conditions of practical flue gases to the most extent. The CO2 adsorption performance was nearly unaffected by H2O, O2, and NO in the flue gas, and was promoted by SO2 within the emission limit stipulated in the Chinese emission standards of air pollutants for a thermal power plant. The maximum CO2 adsorption capacity, 0.57 mmol/g, was obtained under the optimized experimental conditions, and the SO2 concentration was 150 mg/m(3). The influence mechanisms of H2O, O2, SO2, and NO on CO2 adsorption capacity were investigated by infrared spectroscopic analysis.

Olsalazine-Based Metal-Organic Frameworks as Biocompatible Platforms for H2 Adsorption and Drug Delivery.

PubMed

Levine, Dana J; Runčevski, Tomče; Kapelewski, Matthew T; Keitz, Benjamin K; Oktawiec, Julia; Reed, Douglas A; Mason, Jarad A; Jiang, Henry Z H; Colwell, Kristen A; Legendre, Christina M; FitzGerald, Stephen A; Long, Jeffrey R

2016-08-17

The drug olsalazine (H4olz) was employed as a ligand to synthesize a new series of mesoporous metal-organic frameworks that are expanded analogues of the well-known M2(dobdc) materials (dobdc(4-) = 2,5-dioxido-1,4-benzenedicarboxylate; M-MOF-74). The M2(olz) frameworks (M = Mg, Fe, Co, Ni, and Zn) exhibit high surface areas with large hexagonal pore apertures that are approximately 27 Å in diameter. Variable temperature H2 adsorption isotherms revealed strong adsorption at the open metal sites, and in situ infrared spectroscopy experiments on Mg2(olz) and Ni2(olz) were used to determine site-specific H2 binding enthalpies. In addition to its capabilities for gas sorption, the highly biocompatible Mg2(olz) framework was also evaluated as a platform for the delivery of olsalazine and other encapsulated therapeutics. The Mg2(olz) material (86 wt % olsalazine) was shown to release the therapeutic linker through dissolution of the framework under simulated physiological conditions. Furthermore, Mg2(olz) was used to encapsulate phenethylamine (PEA), a model drug for a broad class of bioactive compounds. Under simulated physiological conditions, Mg2(olz)(PEA)2 disassembled to release PEA from the pores and olsalazine from the framework itself, demonstrating that multiple therapeutic components can be delivered together at different rates. The low toxicity, high surface areas, and coordinatively unsaturated metal sites make these M2(olz) materials promising for a range of potential applications, including drug delivery in the treatment of gastrointestinal diseases.

Olsalazine-Based Metal–Organic Frameworks as Biocompatible Platforms for H 2 Adsorption and Drug Delivery

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