饮用水中氯消毒副产物的污染与控制

介绍了饮用水氯消毒的现状,分析了氯消毒副产物的形成机理,简要论述了其控制方法,提出了今后研究工作的方向,这对进一步系统开发可有效控制饮用水氯化消毒副产物的经济高效的相关处理新技术具有参考价值.     

Laboratory-scale column study for remediation of TCE-contaminated aquifers using three-section controlled-release potassium permanganate barriers

A laboratory-scale study with a sand column was designed to simulate trichloroethylene(TCE) pollution in the aquifer environment with three-section controlled-release potassium permanganate(CRP) barriers.The main objective of this study was to evaluate the feasibility of CRP barriers in remediation of TCE in aquifers in a long-term and controlled manner.CRP particles with a 1:3 molar ratio of KMnO 4 to stearic acid showed the best controlled-release properties in pure water,and the theoretical release time was 138.5 days.The results of TCE removal in the test column indicated that complete removal efficiency of TCE in a sand column by three-section CRP barriers could be reached within 15 days.The molar ratio of KMnO 4 to TCE in the three-section CRP barriers was 16:1,which was much lower than 82:1 as required when KMnO 4 solution is used directly to achieve complete destruction of TCE.This result revealed that the efficiency of CRP for remediation of TCE was highly improved after encapsulation.     

Rapid degradation of hexachlorobenzene by micron Ag/Fe bimetal particles

The feasibility of the rapid degradation of hexachlorobenzene (HCB) by micron-size silver (Ag)/iron (Fe) particles was investigated.Ag/Fe particles with different ratios (0,0.05%,0.09%,0.20%,and 0.45%) were prepared by electroless silver plating on 300 mesh Fe powder,and were used to degrade HCB at different pH values and temperatures.The dechlorination ability of Fe greatly increased with small Ag addition,whereas too much added Ag would cover the Fe surface and reduce the effective reaction surface,thereby decreasing the extent of dechlorination.The optimal Ag/Fe ratio was 0.09%.Tafel polarization curves showed that HCB was rapidly degraded at neutral or acidic pH,whereas low pH levels severely intensified H2 production,which consumed the reducing electrons needed for the HCB degradation.HCB degradation was more sensitive to temperature than pH.The rate constant of HCB dechlorination was 0.452 min-1 at 85℃,50 times higher than that at 31℃.HCB was degraded in a successive dechlorination pathway,yielding the main products 1,2,4,5-tetrachlorobenzene and 1,2,4-trichlorobenzene within 2 hr.     

活化过硫酸钠修复氯苯类污染场地的小试试验

氯苯类有机污染物由于其分子量大,不易挥发,分子结构中含有稳定的苯环,一般的修复技术对修复氯苯类污染场地难度较大。本文通过活化过硫酸钠氧化土壤中氯代有机类污染物的小试试验,确定活化过硫酸盐修复氯苯类有机污染场地的可行性,提出对后期中试和工程修复的结论和建议     

水中氯代酸性除草剂衍生气相色谱法主要要素探讨

建立了衍生气相色谱-负化学源质谱检测水中氯代酸性除草剂的方法,从四个方面对氯代酸性除草剂衍生气相色谱法中主要要素分析:针对不同需求选择确定萃取模式、萃取溶剂、酸度、浓缩方式等;对不同衍生方式进行比较,分析了辅助条件的必要性;针对衍生产物的不同选择离子源;标准物质的合理使用。     

Fe~0催化还原转化水中CCl_4的实验研究

通过在Fe0表面化学沉积Cu、Ag、Pd、Ni构建了Cu/Fe、Ag/Fe、Pd,Fe、Ni/Fe多种双金属催化还原体系.通过序批实验研究了水体中毒性污染物CCl在Fe0以及上述双金属催化Fe0体系中的还原脱氯.结果表明,CCl4在上述5种Fe0还原体系中都能发生快速还原脱氯反应,Cu、Ag、Pd等催化剂的加入能明显提高反应速率.还原脱氯反应服从准一级反应动力学方程,CCl4水溶液在Fe0、Cu/Fe、Ag/Fe、Pd/Fe、Ni/Fe 5种还原体系中的反应速率常数分别为0.039 3、0.092 5、0.158、0.049 6和0.053 3 min-1.使用GC/MS分析了CCl4在各种还原体系中的还原脱氯产物,探讨了水体中CCl4还原脱氯降解的反应途径和可能中间产物.CCL4在不同反应体系中不但反应速率不同而且降解产物也不相同,在Cu/Fe、Ag/Fe体系产物以三氯甲烷、二氯甲烷为主,而在Pd/Fe体系主要为甲烷.逐步氢解是CCl4在Fe0还原体系中发生还原脱氯反应的最主要途径.     

污水处理厂尾水中有机氯化物的活性炭吸附深度处理

考虑到经氯消毒的城市污水处理厂尾水中可能存在的副产物,选择广东省东莞市两个典型污水处理厂尾水为研究对象,采用GC-MS分析其中的有机氯化物,并以某种粉末活性炭进行吸附深度处理及考察其效果.分析结果表明,尾水中存在二氯甲烷、三氯甲烷、四氯化碳、二氯一溴甲烷、二澳一氯甲烷、二氯硝基甲烷等多种有机氯化物,其中,三氯甲烷和四氯化碳在所取样品中都存在且相对含量之和超过80%;吸附结果表明,所选择的活性炭样在1 g·L-1投加量下,尾水中未检出有机氯化物.说明适宜的活性炭能够应用于污水处理厂尾水中多种有机氯化物的分离去除.     

Rush-hour aromatic and chlorinated hydrocarbons in selected subway stations of Shanghai, China

Air samples were collected simultaneously at platform, mezzanine and outdoor in five typical stations of subway system in Shanghai, China using stainless steel canisters and analyzed by gas chromatography-mass selective detector (GC-MSD) after cryogenic preconcentration. Benzene, toluene, ethylbenzene and xylenes (BTEX) at the platforms and mezzanines inside the stations averaged (10.3 ± 2.1), (38.7 ± 9.0), (19.4 ± 10.1) and (30.0 ± 11.1) μg/m³, respectively; while trichloroethylene (TrCE), tetrachloroethylene (TeCE) and para-dichlorobenzene (pDCB), vinyl chloride and carbon tetrachloride were the most abundant chlorinated hydrocarbons inside the stations with average levels of (3.6 ± 1.3), (1.3 ± 0.5), (4.1 ± 1.1), (2.2 ± 1.1) and (1.2 ± 0.3) μg/m³, respectively. Mean levels of major aromatic and chlorinated hydrocarbons were higher indoor (platforms and mezzanines) than outdoor with average indoor/outdoor (I/O) ratios of 1.1-9.5, whereas no significant indoor/outdoor differences were found except for benzene and TrCE. The highly significant mutual correlations (p < 0.01) for BTEX between indoor and outdoor and their significant correlation (p < 0.05) with methyl tert-butyl ether (MTBE), a marker of traffic-related emission without other indoor and outdoor sources, indicated that BTEX were introduced into the subway stations from indoor/outdoor air exchange and traffic emission should be their dominant source. TrCE and pDCB were mainly from indoor emission and TeCE might have both indoor emission sources and contribution from outdoor air, especially in the mezzanines.     

氯酚类污染物在小麦幼苗中的竞争吸附研究

极性有机污染物植物吸收行为的研究目前已有较多报道。文章将以小麦幼苗干样为研究对象,以2种氯酚(2,4-二氯酚,DCP;2,4,6-三氯酚,TCP)为吸附质,以菲(PHE)为非极性参照化合物,探讨竞争吸附条件下,可解离有机污染物的植物吸收行为。采用序批平衡实验分别研究了小麦幼苗干样干样对DCP、TCP、PHE单独吸附,及DCP或PHE共存影响下TCP的竞争吸附行为。结果表明,小麦幼苗干样对TCP、DCP和PHE各单组分的吸附呈显著线性相关,分配系数与类脂含量有关;TCP的解离作用使得TCP的类脂标化后植物-水分配系数对数值(logKlip)要小于其辛醇-水分配系数对数值(logKow);DCP或PHE的共存提升了小麦幼苗干样对TCP的吸附能力。TCP的存在不影响小麦幼苗干样对菲的吸附,却能影响其对DCP的吸附。     

挥发性氯代烃在湿润土壤中的平衡吸附研究

吸附是挥发性氯代烃(volatile chlorinated hydrocarbons,VCHs)赋存于土壤的主要机制之一.开展动态吸附实验,研究了4种常见VCHs污染物在我国8种典型土壤中的吸附平衡关系.结果表明,土壤在干燥条件下对VCHs气体的吸附能力要远大于湿润条件,且随含水率的升高吸附能力急剧下降,在含水率达到10%以后土壤吸附量趋于稳定.湿润土壤对三氯乙烯(TCE)、四氯乙烯(PCE)、1,1,1-三氯乙烷(MC)气体的吸附等温线符合Henry型吸附等温式,而1,1,2-三氯乙烷(1,1,2-TCA)符合Freundlich模型.VCHs在湿润土壤中的吸附量总体上与土壤有机碳(soil organic carbon,SOC)含量呈正相关,且受SOC类型和化合物极性影响较大.弱极性的TCE、PCE在土壤中的吸附能力与SOC含量呈严格正相关,而极性的MC、1,1,2-TCA在黑土等高碳土壤中不仅与SOC含量有关,还受到SOC物质组成的影响.建立了TCE和PCE在湿润土壤中的平衡吸附量预测模型,预测值与实测值相关性良好(n=80,R2=0.98).