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101.
Laboratory based approaches for arsenic remediation from contaminated water: recent developments 总被引:4,自引:0,他引:4
Arsenic contamination in water has posed severe health problems around the world. In spite of the availability of some conventional techniques for arsenic removal from contaminated water, development of new laboratory based techniques along with enhancement and cost reduction of conventional techniques are essential for the benefit of common people. This paper provides an overview of the arsenic issue in water such as modes of contamination of ground water as well as surface water by arsenic, its metabolism and health impacts, factors influencing arsenic poisoning, fundamentals of arsenic poisoning mechanism and world scenario of arsenic poisoning. It discusses and compares the conventional laboratory based techniques, like precipitation with alum, iron, Fe/Mn, lime softening, reverse osmosis, electro dialysis, ion exchanges, adsorption on activated alumina/carbon, etc., for arsenic removal from contaminated water. It also discusses the best available techniques and mentions the cost comparison among these techniques too. Recent developments in the research on the laboratory based arsenic removal techniques, like improvement of conventional techniques and advances in removal technology along with its scopes and limitations have also been reviewed. 相似文献
102.
Janet E. Hails Stuart J.C. Irvine David J. Cole-Hamilton Jean Giess Michael R. Houlton Andrew Graham 《Journal of Electronic Materials》2008,37(9):1291-1302
Acceptor doping of many II–VI compound semiconductors has proved problematic and doping of epitaxial mercury cadmium telluride
(MCT, Hg1−x
Cd
x
Te) with arsenic is no exception. High-temperature (>400°C) anneals followed by a lower temperature mercury-rich vacancy-filling
anneal are frequently required to activate the dopant. The model frequently used to explain p-type doping with arsenic invokes an amphoteric nature of group V atoms in the II–VI lattice. This requires that group VI
substitution with arsenic only occurs under mercury-rich conditions either during growth or the subsequent annealing and involves
site switching of the As. However, there are inconsistencies in the amphoteric model and unexplained experimental observations,
including arsenic which is 100% active as grown by metalorganic vapor-phase epitaxy (MOVPE). A new model, based on hydrogen
passivation of the arsenic, is therefore proposed. 相似文献
103.
微波消解-塞曼石墨炉原子吸收光谱法测定食品中的总砷 总被引:3,自引:0,他引:3
目的 测定食品中的总砷。方法 采用微波消解处理,塞曼石墨炉原子吸收光谱法进行测定,最高温度为180℃,消解30min,以硝酸钯为基体改进剂,灰化温度1100℃,原子化温度为2600℃。结果砷的线性范围0~0.100μg/L,曲线相关系数为0.9992,检出限为0.52μg,回收率范围85%~95%。结论 本方法准确、快速、经济。 相似文献
104.
105.
106.
ABSTRACTArsenic can cause environmental pollution and also affect mineral processing efficiency. To determine the mechanism of separating arsenic from minerals, microwave roasting tests were conducted using Hunan arsenic sulfide gold concentrate as a raw material. The heating behaviour of gold concentrates under microwave irradiation was analysed. The effects of roasting temperature, reaction time, and oxygen content on arsenic removal were investigated. Temperature has the greatest effect on arsenic removal, followed by reaction time and oxygen content. The optimum parameters were determined experimentally. The removal rate of arsenic was 93.16% (gas supply: 4?L min?1, reaction temperature: 650°C, duration: 15?min). Scanning electron microscopy analysis of the minerals after microwave roasting and conventional roasting showed that there are more cracks on the surface of minerals after microwave roasting, and the specific surface area is larger. The reaction mechanism of arsenic separation from gold concentrate during microwave roasting is discussed. 相似文献
107.
The chemical composition of an irreversibly adsorbed layer of arsenic on Pt(1 1 1) in sulfuric acid solution has been studied by X-ray photoelectron spectroscopy (XPS). From the chemical shift of the As 3d level, a change in the valence state from As(0) to As(III) with positive-going electrode potential is deduced, the total amount of As on the surface remaining constant. The As coverage derived from XPS is around 0.33 ML, which is in agreement with the charge under the current peak in the cyclic voltammogram. From the coadsorption of anions, accompanying the valence transition of As, As(III) is assumed to exist as As(OH)3 on the surface. 相似文献
108.
建立了土壤中亚砷酸根(As~Ⅲ),砷酸根(As~Ⅴ),一甲基砷酸(MMA),二甲基砷酸(DMA)的液相色谱-电感耦合等离子体质谱(LC-ICP-MS)在线联用检测方法。以磷酸为提取剂,抗坏血酸为还原剂,水浴加热1h可以有效提取土壤中的As;4种砷形态经过Hamilton PRP-x100阴离子交换柱,用15mmol/L的(NH_4)_2HPO_4以1mL/min的流速进行洗脱分离。实验结果表明,3种土壤标准物质的As提取率在86.61%~108.06%之间,平均提取率为99.94%,且该方法检测的相对误差<10%,RSD(n=3)不大于3.69%。同时,对比了Hamilton PRP-x100阴离子交换柱与IonPac AS19阴离子交换柱对4种砷形态的分离效果。 相似文献
109.
Evaluation of the ability of an artificial neural network model to assess the variation of groundwater quality in an area of blackfoot disease in Taiwan 总被引:12,自引:0,他引:12
The back-propagation (BP) artificial neural network (ANN) is applied to forecast the variation of the quality of groundwater in the blackfoot disease area in Taiwan. Three types of BP ANN models were established to evaluate their learning performance. Model A included five concentration parameters as input variables for seawater intrusion and three concentration parameters as input variables for arsenic pollutant, respectively, whereas models B and C used only one concentration parameter for each. Furthermore, model C used seasonal data from two seasons to train the ANN, whereas models A and C used only data from one season. The results indicate that model C outperforms models A and B. Model C can describe complex variation of groundwater quality and be used to perform reliable forecasting. Moreover, the number of hidden nodes does not significantly influence the performance of the ANN model in training or testing. 相似文献
110.
Anaerobic microbial mobilization and biotransformation of arsenate adsorbed onto activated alumina 总被引:1,自引:0,他引:1
Sierra-Alvarez R Field JA Cortinas I Feijoo G Teresa Moreira M Kopplin M Jay Gandolfi A 《Water research》2005,39(1):199-209
Due to the enactment of a stricter drinking water standard for arsenic in the United States, larger quantities of arsenic will be treated resulting in larger volumes of treatment residuals. The current United States Environmental Protection Agency recommendation is to dispose spent adsorbent residuals from arsenic treatment into non-hazardous municipal solid waste (MSW) landfills. The potential of microorganisms to alter the speciation affecting the mobility of arsenic in the disposal environment is therefore a concern. The purpose of this paper was to evaluate the potential of an anaerobic microbial consortium to biologically mobilize arsenate (As(V)) adsorbed onto activated alumina (AA), a common adsorbent used for treating arsenic in drinking water. Three anaerobic columns (0.27 l) packed with 100 g dry weight of AA containing 0.657 mg adsorbed As(V) (expressed as arsenic) per gram dry weight were continuously flushed with synthetic landfill leachate for 257 days. The fully biologically active column was inoculated with methanogenic anaerobic sludge (10 g volatile suspended solids l(-1) column) and was operated with a mixture of volatile fatty acids (VFA) in the feed (2.5 g chemical oxygen demand l(-1) feed). At the end of the experiment, 37% of the arsenic was removed from the column, of which 48% was accounted for by arsenical species identified in the column effluent. The most important form of arsenic eluted was arsenite (As(III)), accounting for nearly all of the identified arsenic in periods of high mobilization. Additionally, two methylated metabolites, methylarsonic acid and dimethylarsinic acid were observed. Mobilization of arsenic is attributed to the biological reduction of As(V) to As(III) since literature data indicates that As(III) is more weakly adsorbed to AA compared to As(V). Batch and continuous assays confirmed that VFA, present in landfill leachates, served as an electron donating substrate supporting enhanced rates of As(V) reduction to As(III). Two control columns, lacking inoculum and/or VFA in the feed displayed low mobilization of arsenic compared to the fully biologically active column. Therefore, leachates generated in MSW landfills could potentially result in the biologically catalyzed mobilization of arsenic from As(V)-laden drinking water residuals. 相似文献