Arsenic in Drinking Water and Its Removal

Abstract

Superfluous arsenic in drinking water can do harm to human health. In this paper, a broad overview of the available technologies for arsenic removal has been presented on the basis of literature survey. The main treatment methods included coagulation-sedimentation, adsorption separation and ion exchange, membrane technique, which have both advantages and disadvantages. It concluded that the selection of treatment process should be site specific and prevailing conditions and no process can serve the purpose under diverse conditions as each technology has its own limitations. In order to gain good results, some methods should be improved.     

基于水化学与硫同位素的卡林型金矿区岩溶水文地球化学特征及控制因素

采矿活动通过抽排改变地下水水位和流动条件,促进了地下水与含水层岩石之间的相互作用,同时矿山排水排入地表水系,从而影响整个岩溶水系统的水文地球化学过程.基于水文地球化学和δ³⁴ S同位素,揭示了典型卡林型金矿区及其周边矿山废水、岩溶地下水、地表水等水文地球化学过程、特征及其主要控制因子.结果表明,未受金矿开采活动影响的地下水和地表水的丰、枯水期水化学组分主要受灰岩和白云质灰岩风化作用控制,离子以Ca²⁺、Mg²⁺和HCO₃^-为主,水化学类型均为Ca-HCO₃型.而矿山废水及其下游受纳水体受碳酸盐和硅酸盐矿物溶蚀与离子交换作用影响,离子以Ca²⁺、Mg²⁺、Na⁺和SO₄^2-为主,水化学类型由Ca-HCO₃型逐步演化为Ca-SO₄型.受矿山开采影响的各类水体中SO₄^2-是特征组分,SO₄^2-浓度在井下呈现从上至下逐渐降低的显著规律.未受矿山废水影响的地下水和地表水δ³⁴ S值偏正,SO₄^2-主要来源于雄黄矿的氧化,而矿山废水及其下游受纳水体δ³⁴ S值偏负,SO₄^2-主要受雄黄矿氧化和大气降水两个端元混合作用的影响,黄铁矿也有一定贡献.同时,各类水体的NO₃^-源于农业化肥施用和农村生活污水直排的输入.     

磁性离子印迹聚合物的制备及其对水中Pb(Ⅱ)的吸附

以铅离子为模板离子、乙二醇二甲基丙烯酸酯和偶氮二异丁腈为交联剂和引发剂、稀盐酸为洗脱剂,采用微波辅助反相乳液悬浮聚合法,制备了磁性离子印迹聚合物(MIIP),通过SEM、FTIR、XRD和BET技术对其进行了表征,并将其用于水中Pb(Ⅱ)的吸附.在初始质量浓度60 mg/L、溶液pH 6、吸附温度303 K、吸附时间6...     

钢渣-蒙脱石复合吸附剂对水中Cd~(2+)的吸附去除

研究了钢渣-蒙脱石复合吸附剂对废水中Cd2+的吸附性能,并探讨了影响吸附的因素和吸附机理.结果表明,钢渣蒙脱石质量比为1∶1的复合吸附剂对Cd2+的吸附效果优于钢渣及蒙脱石对Cd2+的单一吸附.当温度为25℃,废水pH=6~7时,1.2 g钢渣-蒙脱石复合吸附剂对100 mL Cd2+溶液(100 mg·L-1)吸附60 min后,Cd2+的去除率可达到96.99%.钢渣-蒙脱石复合吸附剂对镉离子的吸附反应符合二级动力学方程,可决系数为0.9991;符合Langmuir方程,可决系数为0.9725.对Cd2+的理论饱和吸附量为12.45 mg·g-1.溶液中Pb2+、Cu2+的存在会降低复合吸附剂对Cd2+的吸附量,且Cd2+受Cu2+的影响较大.吸附饱和的钢渣-蒙脱石颗粒材料用1 mol·L-1的氯化钠溶液再生效果好.     

Calorimetric behaviors of hydroxylamine and its salts caused by Fe(III)

The objective of this study is to obtain information on the calorimetric behaviors of aqueous solutions of hydroxylamine (HA), hydroxylamine chloride (HACl), and hydroxylamine nitrate(HAN) caused by different Fe(III) states (free Fe(III) from Fe(NH₄)(SO₄)₂, Fe(CN)₆³⁻, and Fe(EDTA)⁻). The calorimetric data were obtained with a small-scaled reaction calorimeter, Super-CRC.

In the mixing with Fe(III), HA showed the highest reactivity among three substrates. Free Fe(III) and Fe(EDTA)⁻ showed catalytic effects in the reactions. In the overall heat of reactions, Fe(EDTA)⁻ exceeded free Fe(III), which precipitated as Fe(OH)₃ and decreased the chances of interactions with HA. It was suggested that the generation of NH₃ had taken place in the process of reducing HA along with Fe(II) oxidation. Fe(CN)₆³⁻ was less reactive than free Fe(III) and Fe(EDTA)⁻.

The ability of masking Fe(III) was estimated for CyDTA. The HA including CyDTA had no exothermic peak; however, there was an endothermic peak of the heat flow at Fe(III) injection. CyDTA was found to have the ability to inhibit a violent exothermic reaction of HA.     

基于光电子能谱的高含水输油管道内壁腐蚀减薄试验分析

鄂尔多斯盆地高含水输油管道内壁腐蚀减薄现象普遍,腐蚀穿孔频次逐年上升,管道安全防护管理成为难题。为了识别输油管道内壁腐蚀减薄原因,作者在分析含水率、地层水水型、溶解氧对管道内腐蚀影响的基础上选择特征试验管段,基于X射线光电子能谱技术开展管道内壁厚度变化、金相组织、腐蚀产物特性、边缘腐蚀状态研究。结果表明:高含水输油管道内壁腐蚀减薄类型为Cl+O2+H2O环境下的垢下腐蚀,以溶解氧（O2）腐蚀为主,氯离子（Cl－）腐蚀为辅;内壁腐蚀减薄原因为原油含水率过高、水中氯离子含量过高、水中含有溶解氧和介质流速偏低。     

化学沉淀-微滤-络合-超滤处理高浓度含镍废水

在pH=9下,镍离子浓度为5562.71mg/L的镍废水经充分沉淀后,以0.5μm孔径陶瓷膜微滤处理,发现浓缩时膜通量(J)先快速降低,经缓慢下降后,再较快降低,镍截留系数(R_Ni)接近1,当体积浓缩因子(VCF)从1增大到10时,截留液镍浓度(C_r)从5562.71mg/L浓缩至55507.76mg/L,渗透液镍浓度(C_p)为13.26mg/L.以陶瓷膜渗透液为料液,以聚乙烯亚胺为络合剂,考察聚合物与金属质量比(r_p/m)、pH值、温度和操作压力对恒容超滤R_Ni和J的影响,并研究超滤浓缩过程.结果表明,R_Ni随r_p/m或pH增大而增大,随温度升高而略下降,与操作压力无关;J随温度或操作压力增大而增大,随pH增大而增大至不变,r_p/m对J影响甚微.超滤浓缩时,控制r_p/m=7和pH=9,当VCF从1增大到30时,J仅下降9.76%,C_r从13.26mg/L增大至396.64mg/L,C_p约0.04mg/L,镍离子被浓缩,超滤渗透液可直接排放.     

Enhanced degradation of trichloroethene by calcium peroxide activated with Fe(III) in the presence of citric acid

Trichloroethene (TCE) degradation by Fe(III)-activated calcium peroxide (CP) in the presence of citric acid (CA) in aqueous solution was investigated. The results demonstrated that the presence of CA enhanced TCE degradation significantly by increasing the concentration of soluble Fe(III) and promoting H₂O₂ generation. The generation of HO? and O₂^-? in both the CP/Fe(III) and CP/Fe(III)/CA systems was confirmed with chemical probes. The results of radical scavenging tests showed that TCE degradation was due predominantly to direct oxidation by HO?, while O₂^-? strengthened the generation of HO? by promoting Fe(III) transformation in the CP/Fe(III)/CA system. Acidic pH conditions were favorable for TCE degradation, and the TCE degradation rate decreased with increasing pH. The presence of Cl^-, HCO₃^-, and humic acid (HA) inhibited TCE degradation to different extents for the CP/Fe(III)/CA system. Analysis of Cl^- production suggested that TCE degradation in the CP/Fe(III)/CA system occurred through a dechlorination process. In summary, this study provided detailed information for the application of CA-enhanced Fe(III)-activated calcium peroxide for treating TCE contaminated groundwater.     

Online single particle analysis of chemical composition and mixing state of crop straw burning particles: from laboratory study to field measurement

Fresh straw burning (SB) particles were generated in the laboratory by the combustion of rice straw and corn straw. The chemical composition and mixing state of the fresh SB particles were investigated by an Aerosol Time-of-Flight Mass Spectrometer (ATOFMS). Based on the mass spectral patterns, the SB particles were clustered into four major types: Salt, Organic Carbon (OC), Elemental Carbon (EC), and internally mixed particles of EC and OC (EC-OC). In addition, particles containing ash, polycyclic aromatic hydrocarbons, heavy metals or nicotine were also observed. Physical and chemical changes of the SB particles immediately after the emission were analyzed with highly time-resolved data. During the aging processes, the average particle size increased steadily. Freshly emitted organic compounds were gradually oxidized to more oxygenated compounds in the OC-containing particles. Meanwhile, an important displacement reaction (2KCl+ SO42−→ K₂SO₄ + 2Cl⁻) was observed. The marker ions for SB particles were optimized and applied to identify the SB particles in the ambient atmosphere. The fluctuation of the number fraction of ambient SB particles sorted by ATOFMS agrees well with that of water soluble K⁺ measured by an online ion chromatography, demonstrating that the optimized marker ions could be good tracers for SB particles in field measurements.     

锂离子电池常用有机液体电解质中有机溶剂的生命周期评价

评价了锂离子二次电池常用有机液体电解质对环境的影响.在其它条件相同的情况下,电解液中不同有机溶剂配比的不同,使得其对环境的影响值不同,碳酸乙烯酯和碳酸甲乙酯两种有机溶剂按不同比例混合,比例越大对环境影响越小.通过评价和分析两种有机溶剂对环境影响值的贡献率,可为二次电池研发者提供选择最优配比的方法.