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Kinetic modeling of adsorption of vanadium and iron from acid solution through ion exchange resins 被引量:2
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作者 JoséHelber VINCO Amilton Barbosa BOTELHO JUNIOR +2 位作者 Heitor Augusto DUARTE Denise Crocce Romano ESPINOSA Jorge Alberto Soares TENÓRIO 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2022年第7期2438-2450,共13页
This study assessed the adsorption process and the reaction kinetics involved in the selective recovery of vanadium from an acid solution containing iron as an impurity.Four commercial resins were studied:Lewatit^(... This study assessed the adsorption process and the reaction kinetics involved in the selective recovery of vanadium from an acid solution containing iron as an impurity.Four commercial resins were studied:Lewatit^(®)MonoPlus TP 209 XL,Lewatit^(®) TP 207,Dowex^(TM)M4195(chelating resin)and Lewatit^(®) MonoPlus S 200 H(strong cationic exchange resin).To investigate the effect of time on the adsorption process,batch experiments were carried out using the following initial conditions:pH 2.0,298 K,and a proportion of 1 g of resin to 50 mL of solution.The variation of pH over time was analyzed.Chelating resin released less H+ions as the adsorption occurred,resulting in a lower drop of pH when compared to S 200 H resin.Ion adsorption by the resins was also evaluated through FT-IR and SEM−EDS before and after the experiments.Among the evaluated kinetic models(pseudo-first order,pseudo-second order,Elovich and intraparticle diffusion models),the pseudo-second order model best fits the experimental data of the adsorption of vanadium and iron by all of the four resins.M4195 resin showed the highest recovery of vanadium and the lowest adsorption of iron.Kinetic data,which are fundamental to industrial processes applications,are provided. 展开更多
关键词 vanadium recovery ADSORPTION chelating resins metal ions cation exchange resin batch experiments
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Kinetic Modeling of Esterification Reaction of Free Fatty Acids Present in Macauba Oil Using a Cationic Resin as Catalyst
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作者 Daniel Bastos de Rezende Carlos Augusto Silva +1 位作者 Vanya Marcia Duarte Pasa Maria Helena Carlo de Andrade 《Journal of Chemistry and Chemical Engineering》 2015年第3期153-161,共9页
The cost of raw materials has the largest contribution to the final price of biodiesel produced by traditional routes, currently adopted in most industrial scale processes. That contribution comes from the need to use... The cost of raw materials has the largest contribution to the final price of biodiesel produced by traditional routes, currently adopted in most industrial scale processes. That contribution comes from the need to use edible and noble oils, with low acidity, such as soybean oil. This work proposes'the use of Macauba oil, a vegetable oil in focus in the State of Minas Gerais, Brazil, in which the current extractive yield generates a raw material with high acidity, therefore, not suitable to be used in biodiesel production. To make it technically feasible, a cationic exchange resin, the Purolite CT275DR, was used as a catalyst for esterification reaction with samples of Macauba oil, aiming to reduce its acidity. The resin can be reused, regenerated and easily removed from the reaction product, reducing costs with catalyst and purification stages. As a result of this work, in a sample of oil with an initial acidity of about 10% m/m were achieved acidity reductions up to 97% by using cationic resins as catalyst, demonstrating its potential use in the oil pretreatrnent step. Additionally, the data collected during all the analysis made it possible to define the chemical kinetic of the esterification reaction. 展开更多
关键词 ESTERIFICATION chemical kinetic cationic resin Acrocomiaaculeata free fatty acids.
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Decomposition mechanisms of nuclear-grade cationic exchange resin by advanced oxidation processes:Statistical molecular fragmentation model and DFT calculations
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作者 Xiang Meng Pierre Désesquelles Lejin Xu 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2024年第1期433-448,共16页
The treatment and disposal of radioactive waste are presently facing great challenges.Spent ion exchange resins have become a focus of attention due to their high production and serious environmental risks.In this pap... The treatment and disposal of radioactive waste are presently facing great challenges.Spent ion exchange resins have become a focus of attention due to their high production and serious environmental risks.In this paper,a simplified model of cationic exchange resin is proposed,and the degradation processes of cationic resin monomer initiated by hydroxyl radicals(·OH)are clarified by combining statistical molecular fragmentation(SMF)model and density functional theory(DFT)calculations.The prediction of active sites indicates that the S-O bonds and the C-S bond of the sulfonic group are more likely to react during the degradation.The meta-position of the sulfonic group on the benzene ring is the most active site,and the benzene ring without the sulfonic group has a certain reactivity.The C11-C14 and C17-C20 bonds,on the carbon skeleton,are the most easily broken.It is also found that dihydroxy addition and elimination reactions play a major role in the process of desulfonation,carbon skeleton cleavage and benzene ring separation.The decomposition mechanisms found through the combination of physical models and chemical calculations,provide theoretical guidance for the treatment of complex polycyclic aromatic hydrocarbons. 展开更多
关键词 cationic exchange resin Statistical molecular fragmentation model Density functional theory Hydroxyl radical Decomposition mechanism
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Purification method of rohitukine from the stem bark of Dysoxylum binectariferum
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作者 崔保松 马晓庆 +2 位作者 杨东辉 胡学桥 蔡少青 《Journal of Chinese Pharmaceutical Sciences》 CAS 2008年第2期153-157,共5页
To develop a simple and rapid purification method of rohitukine from the stem bark of Dysoxylum binectariferum. A L9 (34) orthogonal test was designed to optimize the extraction condition. Rohitukine in the plant e... To develop a simple and rapid purification method of rohitukine from the stem bark of Dysoxylum binectariferum. A L9 (34) orthogonal test was designed to optimize the extraction condition. Rohitukine in the plant extract was purified by using solvent-solvent partition and cation exchange resion (CER). Five different types of packing materials, including XAD-2 resin, polyamide, Sephadex LH-20, ODS and CER, were compared and CER showed the best capacity for rohitukine separation. The purification procedure was optimized as follows: the plant material powder was extracted with 70% ethanol (v/m = 60) by ultrasonic agitation for 60 min, then the 70% ethanol extract was dissolved in aqueous solution (pH 1, adjusted with 0.5 mol/L HCl) and extracted with equal volume of n-butanol. The aqueous layer was retained and the pH was adjusted to 10 with 25% aqueous ammonia and a solventsolvent partition was performed with equal volume of n-butanol. The obtained n-butanol extract was dissolved in aqueous solution (pH 1, adjusted with 0.5 mol/L HCl), and purified by a CER column eluting with H2O and 70% ethanol (pH 10, adjusted with 25% aqueous ammonia), successively. Rohitukine existed in 70% ethanol eluate, with a purity up to 53.3%. The method developed in this study provides a simple and rapid approach for the preparation of rohitukine from the stem bark ofD. binectariferum. 展开更多
关键词 Rohitukine Dysoxylum binectariferum PURIFICATION Liquid-liquid extraction Cation exchange resin
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Synthesis of cation exchange resin-supported iron and magnesium oxides/hydroxides composite for nitrate removal in water 被引量:2
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作者 Trung Thanh Nguyen Vu Anh Khoa Tran +6 位作者 Le Ba Tran Phuoc Toan Phan Minh Tan Nguyen Long Giang Bach Surapol Padungthon Cong Khiem Ta Nhat Huy Nguyen 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2021年第4期378-384,共7页
In this study,we reported on the concept and practical use of cation exchange resin(CER)for removing anions in water via pretreating the CER with metal salts.The cation exchange resinsupported iron and magnesium oxide... In this study,we reported on the concept and practical use of cation exchange resin(CER)for removing anions in water via pretreating the CER with metal salts.The cation exchange resinsupported iron and magnesium oxides/hydroxides composite(FeMg/CER)was synthesized and introduced as a new and potential adsorbent for selective removal of nitrate ion in the water environment.Characteristics of FeMg/CER were determined by techniques such as Fouriertransform infrared spectroscopy,scanning electron microscopy,and Xray diffraction.The results showed that FeMg/CER material had a high nitrate adsorption capacity of 200 mg NO_(3)^()·g^(1)with a fast equilibrium adsorption time of 30 min at pH 5.In addition,it had good durability of at least 10 times of regeneration,which could be applied to practical water and wastewater treatment. 展开更多
关键词 Iron oxide/hydroxide Magnesium oxide/hydroxide Cation exchange resin ADSORPTION Environment NANOMATERIALS
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Kinetic and thermodynamic studies of the esterification of acidified oil catalyzed by sulfonated cation exchange resin 被引量:8
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作者 Lingling Ma Ying Han +2 位作者 Kaian Sun Jie Lu Jincheng Ding 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2015年第4期456-462,共7页
This study describes the kinetics and thermodynamics of the esterification of acidified oil with methanol catalyzed by sulfonated cation exchange resins(SCER). The effects of the mass ratio of methanol to acidified ... This study describes the kinetics and thermodynamics of the esterification of acidified oil with methanol catalyzed by sulfonated cation exchange resins(SCER). The effects of the mass ratio of methanol to acidified oil,reaction temperature,and catalyst loading were studied to optimize the conditions for maximum conversion of free fatty acids(FFAs). The results showed that the optimal conversion rate of FFAs was 91.87% at the mass ratio of methanol to acidified oil of 2.5:1.0,reaction temperature of 65.0 °C,catalyst loading of 5.0 g and reaction time of 8.0 h. The external and internal mass transfer resistances were negligible based on the experimental results and a pseudo-homogeneous kinetic model was proposed for the esterification. The activation energy and thermodynamic parameters including G,S and H were determined. The conversion rates of FFAs obtained from the established model were in good agreement with the experimental data. 展开更多
关键词 Acidified oil Biodiesel Esterification Pseudo-homogeneous model Sulfonated cation exchange resin
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Elements, Structure and Electrochemical Property of Carbon Derived from La^(3+) Adulterating Polystyrene Cation Exchange Resin
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作者 WANG Shu jun 1, LIU Qing guo 2 ( 1. Department of Chemical Engineer, University of Petroleum Beijing, Beijing 102200, China 2. Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083, China) 《Journal of Rare Earths》 SCIE EI CAS CSCD 2000年第3期214-214,共1页
The polystyrene cation exchange resin was exchanged by La 3+ and then were carbonized to make resin carbon material. The electrochemical properties of the resin carbon material as the electrode of the lithium ion... The polystyrene cation exchange resin was exchanged by La 3+ and then were carbonized to make resin carbon material. The electrochemical properties of the resin carbon material as the electrode of the lithium ion cell were investigated. The test results show that comparing with the polystyrene cation exchange resin without adulterating, the contents of hydrogen, oxygen and sulfur are changed obviously for the resin carbon material derived from the La 3+ adulterating polystyrene cation exchange resin. The contents of hydrogen and oxygen are increased, and the one of sulfur is decreased. The test results also indicate that it is more easily to form the stratum graphite minicrystal structure with bigger diameter for the La 3+ adulterating resin. According to the electrochemical test results, the electrode derived from La 3+ adulterating polystyrene cation exchange resin has much better electrochemical property, and the capacity of charge and discharge of the electrode is increased about 30 mAh·g -1 in average. 展开更多
关键词 rare earths ion adulterating polystyrene cation exchange resin CARBON electrode material
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USE OF CATION EXCHANGE RESIN IN SYNTHESIS OF N-SUBSTITUTED-1-AMINOALKANEPHOSPHONATE AND-PHOSPHINIC ACIDS
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作者 Yue Hua ZHANG Wen Qiang HUANG Ai Ju MEN Bing Lin HE Institute of Polymer Chemistry,Nankai University,Tianjin,300071 《Chinese Chemical Letters》 SCIE CAS CSCD 1993年第3期203-204,共2页
Strongly acidic cation exchange resin(1x1,H form)has been successfully used as a catalyst in synthesis of diphenyl N-benzyloxycarbonyl-1-aminobenzylphosphonate, N-benzyloxycarbonyl-1-aminobenzylphenylphosphinic acid a... Strongly acidic cation exchange resin(1x1,H form)has been successfully used as a catalyst in synthesis of diphenyl N-benzyloxycarbonyl-1-aminobenzylphosphonate, N-benzyloxycarbonyl-1-aminobenzylphenylphosphinic acid and N-p-tolylsulfonyl-1-aminobenzyl phenylphosphinic acid in high yields. 展开更多
关键词 CHEN USE OF CATION EXCHANGE RESIN IN SYNTHESIS OF N-SUBSTITUTED-1-AMINOALKANEPHOSPHONATE AND-PHOSPHINIC ACIDS
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Cationized Melamine-formaldehyde Resin for Improving the Wet Strength of Paper
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作者 HuaShan Wang LuMing Yang +3 位作者 YuFang Liu KaiWen Mou YiZe Li RuiTao Cha 《Paper And Biomaterials》 2016年第1期56-62,共7页
In this work, melamine-formaldehyde resin was cationized by adding modifiers so that the fibers closely bonded to improve their usability and the wet strength of paper was greatly improved. Triethanolamine and dimethy... In this work, melamine-formaldehyde resin was cationized by adding modifiers so that the fibers closely bonded to improve their usability and the wet strength of paper was greatly improved. Triethanolamine and dimethylamine were added to modify the melamine-formaldehyde resin,respectively.The mechanism of the cationized resin was explored and the possible chemical reactions were deduced. It was concluded that,with the use of triethanolamine,the most optimum product was obtained by hydroxymethylation for 30 min with a temperature of 85℃ and p H of 9. 0 where n( melamine) ∶ n( formaldehyde) ∶ n( methanol) ∶ n( triethanolamine) was 100 ∶ 330 ∶ 450 ∶ 15. With the combined use of dimethylamine and methanol,the optimal product was acquired by condensation for 30 min at a temperature of 50℃ and p H of 2. 0 at melamine, formaldehyde, methanol, and dimethylamine molar ratio of100∶ 330∶ 350∶ 20. With the only use of dimethylamine,the optimal product was obtained by condensation at melamine,formaldehyde,dimethylamine molar ratio of 100∶ 330∶ 10. The wet tensile strength of fruit-bagging paper was improved by adding cationized melamine-formaldehyde resin. The zeta potential,charge density,and conductivity of the melamine-formaldehyde resin were also studied. 展开更多
关键词 cationized melamine-formaldehyde resin wet tensile strength fruit-bagging paper TRIETHANOLAMINE DIMETHYLAMINE
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FACTORS AFFECT THE RELEASE OF PSEUDOEPHDRINE HYDROCHLORIDE FROM THE UNCOATED CATION EXCHANGE RESIN-BASED DRUG DELIVERY SYSTEM IN VITRO
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作者 LIZhenhua PIHongqiong HE Binglin 《Chinese Journal of Reactive Polymers》 2001年第1期8-14,共7页
In this paper, it was investigated that the effect of parameters such as the ionic strength, pH, counter-ion type of release medium, particle size, and cross linkage of cation exchange resin on the release of model dr... In this paper, it was investigated that the effect of parameters such as the ionic strength, pH, counter-ion type of release medium, particle size, and cross linkage of cation exchange resin on the release of model drug pseudoephedrine hydrochloride (PE) from uncoated drug-resin complex. The drug-resin complex was prepared by the reaction of PE with strongly acidic cation exchange resin (001×4, 001×7, 001×14). The result showed that the loading of PE increased with the increase of temperatures. The release of PE from drug-resin complex at 37℃ was monitored in vitro. From the experiments, it was found that the release rate of PE depends on the pH, composition of the releasing media, increased at lower pH media or with increase of ionic strength of media. Moreover, the release rate of PE was inversely proportional to the cross-linkage and particle size of the cation exchange resin. 展开更多
关键词 Pseudoephedrine hydrochloride Drug delivery system Cation exchange resin in vitro release.
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ISOLATION AND PURIFICATION OF ALKALOIDS FROM PLUMULA NELUMBINIS BY DOUBLE-COLUMN ADSORPTION CHROMOTOGRAPHY
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作者 ZHANG Jixiang GUO Jinsheng OU Lailiang 《Chinese Journal of Reactive Polymers》 2007年第1期119-124,共6页
The performance of adsorption and separation for liensinine, isoliensinine and neferine was studied by double-column adsorption chromatography using macroporous adsorption and cation exchange resins. The alkaloid extr... The performance of adsorption and separation for liensinine, isoliensinine and neferine was studied by double-column adsorption chromatography using macroporous adsorption and cation exchange resins. The alkaloid extract with 49.2% total contents by mass representing 10.6% liensinine, 10.6% isoliensinine and 28.0% neferine respectively was prepared by D72 cation exchange resins, in which most of the impurities were water-soluble alkaloids. Furthermore,the alkaloid extract with 82.6% total contents by mass containing 33.1%, 15.0% and 34.5% of the three adsorbates respectively was prepared by double-column adsorption chromatography using AKS-W macroporous adsorption and D72 cation exchange resins. As a result, the content of single and total alkaloids has been greatly increased by the double-column adsorption chromatography. 展开更多
关键词 Double-column adsorption chromatography Macroporous adsorption resin Cation exchange resin Alkaloids from plumula nelumbinis.
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Controlled Drug Release Studies of Atenolol Using Differently Sulfonated Acryloxyacetophenone and Methyl Methacrylate Copolymer Resins as Drug Carriers 被引量:2
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作者 K.Doraswamy P.Venkata Ramana 《Chinese Journal of Polymer Science》 SCIE CAS CSCD 2014年第3期280-291,共12页
2-Acryloxyacetophenone (AAP) was prepared and subjected to suspension polymerization with methyl methacrylate (MMA) using azobisisobutyronitrile (AIBN) as free radical initiator. The differently sulfonated AAP-M... 2-Acryloxyacetophenone (AAP) was prepared and subjected to suspension polymerization with methyl methacrylate (MMA) using azobisisobutyronitrile (AIBN) as free radical initiator. The differently sulfonated AAP-MMA cross-linked copolymer cationic exchange resins were prepared by sulfonation with concentrated sulphuric acid at 70 ~C. Several characteristics of the prepared resins were evaluated, i.e. FTIR, the ion-exchange capacity (IEC), thermo gravimetric analysis (TGA), particle size distribution and microscopic morphology. The resin characteristics were altered with degree of sulfonation, providing that differently sulfonated resins could be prepared. The behavior of atenolol (ATL) loading and in vitro release in the USP stimulated gastric and intestinal fluids of the obtained resins were evaluated. The drug loaded in the resin increased with increasing degree of sulfonation and hence the drug binding site in resin employed. The drug release was lower from the resins with higher content of sulfonic group due to the increase in the diffusive path depth. The drug release was a little lower in stimulated gastric fluid (SGF) than in stimulated intestinal fluids (SIF). The basic groups, ionized to a little greater extent in SGF and preferred binding with the resin rather than releasing. Hence, the differently sulfonated resins could be utilized as novel carriers for drug delivery. 展开更多
关键词 2-Acryloxyacetophenone Methyl methacrylate Different sulfonation cationic exchange resins ATENOLOL In vitro drug release.
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Preparation and characterization of EVAL hollow fiber membrane adsorbents filled with cation exchange resins
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作者 Fengli ZHANG Yuzhong ZHANG +1 位作者 Guangfen LI Hong LI 《Frontiers of Chemical Science and Engineering》 SCIE EI CSCD 2009年第4期462-467,共6页
EVAL hollow fiber membrane adsorbents filled with powder D061-type cation exchange resin were prepared through dry-wet spinning process,using hydrophilic copolymer EVAL as the fiber substrate.The microstructures of th... EVAL hollow fiber membrane adsorbents filled with powder D061-type cation exchange resin were prepared through dry-wet spinning process,using hydrophilic copolymer EVAL as the fiber substrate.The microstructures of the membrane adsorbents were observed,and the pure water fluxes,BSA rejection,and static adsorption capacities of membrane adsorbents for BSA were measured.The effect of the resin-filled content on membrane performance has been discussed.The results showed that EVAL hollow fiber membrane adsorbents filled with D061-type cation exchange resins had good adsorption capacity,and the adsorption capacity increased with the quantity of the resin-filled content.The static protein adsorption capacity was 77.14 mg BSA/g membrane adsorbents when D061 resin loading content was 65%at pH 4.5. 展开更多
关键词 EVAL hollow fiber membrane adsorbents cation exchange resin adsorption capacity
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Enzyme-assisted Extraction and Enrichment of Galanthamine from Lycoris aurea 被引量:5
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作者 Chun-lian Tian Peng Wang +3 位作者 Ji-xin Qin Xiao-pan Liu Ke Song Zhuo-bing Xiao 《Chinese Herbal Medicines》 CAS 2016年第2期182-188,共7页
Objective To explore the optimum condition for complex enzyme-assisted extraction of galanthamine from Lycoris aurea by L_9(3~4) orthogonal array design and separation effect of cation exchange resin on galanthamine... Objective To explore the optimum condition for complex enzyme-assisted extraction of galanthamine from Lycoris aurea by L_9(3~4) orthogonal array design and separation effect of cation exchange resin on galanthamine. Methods Cellulase and pectinase solution was used as the extraction solvent. The effects of p H value of enzyme, amount of complex enzyme, dissociation time, and enzymatic hydrolysis temperature on the extraction results were investigated. Results The optimal conditions were obtained as follows: ratio of solid to liquid(g:mL) 1:10, pH value 4.5, amount of complex enzymes 4%, enzymatic hydrolysis temperature 50oC, and reaction time 2.0 h. Under these conditions, the extraction yield of galanthamine was 0.0294%. In addition, D-001 cation exchange resin was selected for separation of galanthamine. The separation conditions were that adsorption flow rate was 3 BV/h with reagent of pH2 and the desorption flow rate was 3 BV/h with 70% ethanol solution containing 1.5 mol/L ammonia. After separation, the content of galanthamine was increased to 12.31%. Conclusion The results provide a reference for industrial production of galanthamine. 展开更多
关键词 cation exchange resin enzyme-assisted extraction GALANTHAMINE Lycoris aurea SEPARATION
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Catalytic effects of V_(2)O_(5) on oxidative pyrolysis of spent cation exchange resin 被引量:2
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作者 Qi SONG Jian-hua SHEN +3 位作者 Yong YANG Yao YANG Bin-bo JIANG Zu-wei LIAO 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2021年第2期94-105,共12页
Pyrolysis is a cost-effective and safe method for the disposal of radioactive spent resins.In this work,the catalytic effects of V_(2)O_(5) on the pyrolysis of cation exchange resin are investigated for the first time... Pyrolysis is a cost-effective and safe method for the disposal of radioactive spent resins.In this work,the catalytic effects of V_(2)O_(5) on the pyrolysis of cation exchange resin are investigated for the first time.The results show that it is a better catalyst than others so far studied and achieves a lowering of final pyrolysis temperature and residual rate simultaneously when aided by physical blending.The maximum reductions of the final pyrolysis temperature and the residual rate are 173℃and 11.9%(in weight),respectively.Under the action of V_(2)O_(5),low-temperature(445℃)removal of partial sulfonic acid groups occurs and the pyrolysis of the resin copolymer matrix is promoted.This is demonstrated by the analysis of pyrolysis residues at different temperatures by X-ray photoelectron spectroscopy(XPS)and element analysis.The catalytic activity of V_(2)O_(5) is determined by effects both at acid sites and oxidation-reduction centers via H2-TPR(temperature programmed reduction),V_(2)-TPD(temperature programmed desorption),CV_(2)-TPD,and NH3-TPD.The catalytic effect of oxidation-reduction centers in V_(2)O_(5) is achieved by close contact with the sulfur bond through chemisorption under the effect of acid sites.V_(2)O_(5) is also believed to be the reason for the removal of partial sulfonic acid groups at lower temperatures(445℃).V_(2)O_(5) is an effective catalyst for spent resin pyrolysis and can be further applied in industry. 展开更多
关键词 Waste disposal Cation exchange resin V2O5 CATALYSIS Oxidative pyrolysis
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Cation exchange resin supported nanoscale zero-valent iron for removal of phosphorus in rainwater runoff 被引量:2
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作者 Bangmi XIE Jiane ZUO Lili GAN Fenglin LIU Kaijun WANG 《Frontiers of Environmental Science & Engineering》 SCIE EI CAS CSCD 2014年第3期463-470,共8页
Self-made cation exchange resin supported nanoscale zero-valent iron (R-nZVI) was used to remove phosphorus in rainwater runoff. 80% of phosphorus in rainwater runoff from grassland was removed with an initial conce... Self-made cation exchange resin supported nanoscale zero-valent iron (R-nZVI) was used to remove phosphorus in rainwater runoff. 80% of phosphorus in rainwater runoff from grassland was removed with an initial concentration of 0.72 mg. L-1 phosphorus when the dosage of R-nZVl is 8 g per liter rainwater, while only 26% of phosphorus was removed when using cation exchange resin without supported nanoscale zero-valent iron under the same condition. The adsorption capacity of R-nZVI increased up to 185 times of that of the cation exchange resin at a saturated equilibrium phosphorous concentration of 0.42 mg. L-1. Various techniques were implemented to characterize the R-nZVI and explore the mechanism of its removal of phosphate. Scanning electron microscopy (SEM) indicated that new crystal had been formed on the surface of R-nZVI. The result from inductive coupled plasma (ICP) indicated that 2.1% of nZVI was loaded on the support material. The specific surface area was increased after the load of nanoscale zero-valent iron (nZVI), according to the measurement of BET-N2 method. The result of specific surface area analysis also proved that phosphorus was removed mainly through chemical adsorption process. X-ray photoelectron spectroscopy (XPS) analysis showed that the new product obtained from chemical reaction between phosphate and iron was ferrous phosphate. 展开更多
关键词 nanoscale zero-valent iron(R-nZVI) cation exchange resin rainwater runoff phosphorus adsorption
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Capability of cation exchange technology to remove proven N-nitrosodimethylamine precursors
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作者 Shixiang Li Xulan Zhang +5 位作者 Er Bei Huihui Yue Pengfei Lin Jun Wang Xiaojian Zhang Chao Chen 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2017年第8期331-339,共9页
N-nitrosodimethylamine(NDMA) precursors consist of a positively charged dimethylamine group and a non-polar moiety, which inspired us to develop a targeted cation exchange technology to remove NDMA precursors. In th... N-nitrosodimethylamine(NDMA) precursors consist of a positively charged dimethylamine group and a non-polar moiety, which inspired us to develop a targeted cation exchange technology to remove NDMA precursors. In this study, we tested the removal of two representative NDMA precursors, dimethylamine(DMA) and ranitidine(RNTD), by strong acidic cation exchange resin. The results showed that pH greatly affected the exchange efficiency, with high removal(DMA 〉 78% and RNTD 〉 94%) observed at pH 〈 pk_a-1 when the molar ratio of exchange capacity to precursor was 4. The exchange order was obtained as follows: Ca^(2+)〉 Mg^(2+)〉 RNTD~+〉 K~+〉 DMA~+〉 NH_4~+〉 Na~+. The partition coefficient of DMA~+to Na~+was 1.41 ± 0.26, while that of RNTD~+to Na~+was 12.1 ± 1.9. The pseudo second-order equation fitted the cation exchange kinetics well. Bivalent inorganic cations such as Ca^(2+)were found to have a notable effect on NA precursor removal in softening column test. Besides DMA and RNTD, cation exchange process also worked well for removing other 7 model NDMA precursors. Overall, NDMA precursor removal can be an added benefit of making use of cation exchange water softening processes. 展开更多
关键词 Ion exchange Cation exchange resin N-nitrosamine precursors Dimethylamine Ranitidine
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