氯酚溶液的γ辐照还原降解研究

氯酚由于氯取代基产生的诱导效应,使其容易受到亲核粒子的攻击而被还原降解.通过测定γ辐照前后氯酚母体、Cl-离子以及反应中间产物的浓度变化,研究了4种氯酚水溶液(4-CP、2-CP、2,4-DCP、2,4,6-TCP)与水合电子ea-q反应的降解脱氯过程.结果表明,在水合电子ea-q还原体系中,4种氯酚的降解脱氯顺序依次为:2,4,6-TCP>2,4-DCP>2-CP>4-CP,多氯酚比单氯酚容易降解脱氯,邻位上的氯原子要比对位上的氯原子更容易去除,苯酚和Cl-是氯酚反应降解的最终产物.另外,4种氯酚的降解和脱氯过程皆遵循一级反应动力学特征,4-CP、2-CP、2,4-DCP和2,4,6-TCP的降解反应常数分别是0.154、0.253、0.750和1.188 kGy-1,脱氯反应常数分别为0.137、0.219、0.251和0.306 kGy-1.     

萘普生在氯消毒过程中的去除、转化与风险评价

药用活性化合物（PhACs）在氯消毒过程中生成消毒副产物的问题引起了广泛关注.以典型PhACs物质萘普生（NAP）为研究对象,考察各因素对游离氯与NAP反应的影响,探究NAP氯化机制并进行风险评估.结果表明,NAP氯化反应遵循一级反应动力学,NAP在氯化过程中的降解率和反应速率常数随着NAP初始浓度和氨根离子投加量的增加而降低,随着游离氯初始浓度的增加而增大,酸性条件下更有利于NAP的氯化反应.基于HPLC-MS/MS分析鉴定出5种含氯降解中间产物,并提出氯化NAP反应机制.ESCOAR风险预测和发光菌毒性分析表明氯化NAP过程中生成了毒性更高的中间产物,对饮用水安全可能构成潜在威胁.     

水中酚类的色谱测定

测定天然水和饮用水里酚类,通过多孔阴离子一交换树脂的处理,用丙酮洗提,然后由气相色谱法测定.本文介绍的方法,是在测定酚时,可防止酚的氯化、氧化作用和其它反应而引起的损失.一般无机离子和许多有机物质不引起干扰;保留在树脂中的中性有机物可用甲醇洗涤去除.此法对于酚、酚基和氯代酚类可精确测定到PPb到PPm浓度范围.对测定饮用水和地表水里痕量的有机污染物的方法,经多方面的改进得到了进一步     

危险废物破坏的直接质谱研究——在TiO_2作用下三氯乙烯的气相光催化氧化反应的机理和生成物

本文所探讨的是利用二氧化钛使三氯乙烯(TCE)产生气相光催化氧化反应的方法,去破坏一般的污染物质。该项研究的结果与以前所获得的TCE的高速率的破坏相一致。与这些高速率破坏同时发生的是高量子产额(接近整数)。但是,直接抽样的质谱测定和气相傅里叶转换红外线光谱仪(FTIR)显示:有大量的副产品生成(碳酰氯、二氯乙酰氯(DCAC)、一氧化碳、分子氯)。在化学反应的基础上,DCAC的生成得到了合理的解释:在含有C1原子的链式反应中,TCE分子被氧化了。这一反应机理似乎也适用于其它氯化乙烯的试验(如全氯乙烯、二氯乙烯)。碳酰氯至少有一部分来自于DCAC的光催化氧化,而分子氯是由氯原子的再次结合所形成的。本研究也探讨了TCE的液相光催化氧化反应,这里可以发现氯化媒介物。     

环境化学

X13 99013944一氯酚光化学反应过程中C一Cl键的断裂/郁志勇…(中科院生态环境研究中心)//环境科学/中科院生态环境研究中心一1998,19(5),一45~47 环信X一5 反应体系20mg/L4一氯酚在光照条件下,c-Cl键断裂,用离子色谱检测了a一浓度。在模拟太阳光照射下,A13+加速C一Cl键断裂的作用较明显;在紫外光照射下,氯原子迅速从4一氯酚分子中苯环上断裂,A13+、Fe2+、Fe3+对该过程的影响很小。最后用Cl一浓度变化研究了反应体系的动力学性质。图2表1参7氧化程度出发,研究易降解有机物对氯代物芳香化合物生物降解性能的影响。结果表明,易降解有机物…     

γ-射线辐照-H2O2联合技术降解3-氯酚的研究

利用60Coγ-射线辐照3-氯酚(3-CP)水溶液,研究了其辐射降解特性.通过测量辐射后3-氯酚的去除率、紫外-可见光谱、脱氯率、总有机碳(TOC)去除率等,探讨了吸收剂量、氯酚初始浓度、H2O2加入对氯酚降解效果的影响,并初步探讨了氯酚降解动力学特性.结果表明,当3-氯酚浓度为10 mg.L-1,辐射剂量为2 kGy时,脱氯率可达100%,TOC去除率达53%;当辐射剂量提高到8 kGy时,3-氯酚可完全矿化,TOC去除率达100%.3-氯酚的辐照降解过程可用一级反应动力学方程拟合.氯酚单独γ-辐射以及辐照/H2O2联合处理的一级反应动力学常数k分别为0.279 h-1和0.542 h-1.     

六六六在水溶液中的光异构化与光化学降解

以高压汞灯为光源,研究了六六六(BHC)在水溶液中的光解。在水溶液中,除α-BHC外,BHC的光化学降解与光异构化是同时发生的。光异构化规律是:分子中一个氯原子改变其原来构象而朝着形成对光更加稳定的异构体转化。经色质谱联用鉴定,证明氯苯、二氯苯、四氯环己烯、一氯酚、二氯酚、三氯酚及三氯环己烯醇为BHC在水溶液中的光解产物。提出了包含还原脱氯和羟基取代的这一光解反应的历程。     

纳米Fe0颗粒对三种单氯酚的降解

采用化学还原法制备了纳米Fe0颗粒,研究了不同条件下纳米Fe0对3种单氯酚(2-CP, 3-CP, 4-CP)的去除作用.结果表明,纳米Fe0对单氯酚具有良好的去除效果,主要降解途径为先脱氯后开环,实现氯酚分子与Fe原子间的电子转移,达到还原脱氯的效果.3种单氯酚的脱氯难易程度为2-CP＞3-CP＞4-CP,脱氯反应活性与其分子最低空轨道能量(ELUMO)有关.随着氯酚初始浓度的增大,其相对去除率略有降低, 但绝对降解量有较大提高.温度不仅影响脱氯速率,而且影响氯酚去除的途径,温度较高时,氯酚先脱氯后开环;温度低时,较易产生氧化产物.     

氯酚类化合物对淡水发光菌Q67的联合毒性

以淡水发光菌Q67——青海弧菌Q67(Vibrio qinghaiensis sp.-Q67)为生物材料,分别研究了2-氯酚,2,4-二氯酚和2,3,4-三氯酚及其等剂量、等毒性单位配比混合物的发光抑制毒性,并采用相加指数法和相似性参数法评价了混合物的联合毒性效应. 结果表明:3种氯酚对Q67菌的EC₅₀值分别为99.57,25.19和3.42 mg/L,说明氯酚类化合物对发光菌的急性毒性随着氯原子数目的增加而增大,氯酚的二元和三元混合物的毒性作用明显高于化合物的单一毒性. 2种评价指数均采用评价标准的95%置信区间,避免了由实验误差引起的不准确性. 氯酚混合物对Q67菌的联合毒性效应主要表现为简单的相加作用,只有2-氯酚与2,3,4-三氯酚的组合为弱的协同作用. 氯酚的等剂量和等毒性配比混合物毒性作用的评价结果相一致.      

相对速率法测量氯原子与几种酮类物质的反应速率常数

在(298±2) K和一个大气压条件下,采用相对速率法研究了一系列酮类物质与氯原子的反应动力学.使用丙醛和乙苯作为参比物,光解三氯乙酰氯作为氯原子产生源,测得2-己酮与氯原子的反应速率常数为(1.80±0.42)×10~(-10) cm~3·molecule~(-1)·s~(-1),与已有文献报道值非常符合,验证了实验方法和所选参比物的可靠性.首次测得了(298±2) K和一个大气压条件下2-庚酮和2-辛酮与氯原子反应的速率常数,分别为(2.54±0.62)×10~(-10)和(2.12±0.63)×10~(-10) cm~3·molecule~(-1)·s~(-1).与其母体烷烃的反应速率对比发现,酮类物质中羰基的存在使得其反应速率都比其母体烷烃变慢.利用所测的速率常数和氯原子的浓度信息估算这些酮类物质在大气中的平均寿命,结果显示,在海洋边界层或沿海地区等氯原子浓度较高的地区,这些物质与氯原子反应的大气化学寿命都在小时量级,完全可以与OH自由基的反应相竞争,是这些物质在大气中的重要降解途径.另外,在内陆污染地区或工业聚集区,氯原子的反应及其对二次污染物生成的贡献同样不能忽视.     

The role of metal oxides on oxidant decay and disinfection byproduct formation in drinking waters: Relevance to distribution systems

Maintaining a residual disinfectant/oxidant (e.g., chlorine and chlorine dioxide), is a generally used strategy to control microbial contaminants and bacterial regrowth in distribution systems. Secondarily oxidant, such as hypobromous acid (HOBr), can be formed during chlorination of bromide-containing waters. The decay of oxidants and formation of disinfection byproducts (DBPs) due to the interaction between oxidants and selected metal oxides were studied. Selected metal oxides generally enhanced the decay of these halogen-containing oxidants via three pathways: (1) catalytic disproportionation to yield an oxidized form of halogen (i.e., halate) and reduced form (halide for chlorine and bromine or chlorite for chlorine dioxide), (2) oxygen formation, and (3) oxidation of a metal in a reduced form (e.g., cuprous oxide) to a higher oxidation state. Cupric oxide (CuO) and nickel oxide (NiO) showed significantly strong abilities for the first pathway, and oxygen formation was a side reaction. Cuprous oxide can react with oxidants via the third pathway, while goethite was not involved in these reactions. The ability of CuO on catalytic disproportionation of HOBr remained stable up to four cycles. In chlorination process, bromate formation tends to be important (exceeding 10 µg/L) when initial bromide concentration is above 400 µg/L in the presence of dissolved organic matter. Increasing initial bromide concentrations increased the formation of DBPs and calculated cytotoxicity, and the maximum was observed at pH 8.6 during chlorination process. Therefore, the possible disinfectant loss and DBP formation should be carefully considered in drinking water distribution systems.     

南水北调丹江口水库水氯(胺)化消毒副产物产生特性与消毒工艺对比

系统研究了南水北调中线工程水源——丹江口水库水在氯(胺)化消毒条件下,常规消毒副产物的产生特性,考察了消毒方式、消毒剂投加量、接触时间、p H和溴离子浓度等因素的影响,并对消毒工艺参数进行了优化.结果发现,丹江口水库水经氯化消毒可产生三氯甲烷、二氯一溴甲烷等常规含碳和较低浓度二氯乙腈、三氯硝基甲烷等含氮消毒副产物,而氯胺化消毒仅产生三氯甲烷和三氯硝基甲烷等消毒副产物(disinfection by-products,DBPs).自由氯消毒过程产生的各类型DBPs浓度约为氯胺消毒的7.5倍,短时自由氯转氯胺方式DBPs产生量介于两者之间;随着自由氯投加量增加,各类型消毒副产物均呈现增加趋势,投加量大于2 mg·L-1后DBPs增加量较少.随氯胺投加量增加,三氯甲烷生成量变化不大,投加量大于2mg·L-1后可产生三氯硝基甲烷等副产物.随反应时间延长,自由氯的衰减速率明显大于氯胺,同时消毒副产物增长量明显快于氯胺消毒.随着p H升高,自由氯消毒后三卤甲烷含量呈现增加趋势,而氯胺消毒后变化不明显.随溴离子浓度的增加,自由氯和氯胺消毒后副产物类型均向溴代DBPs转变,同时总生成量明显增加,自由氯消毒DBPs增长量明显大于氯胺消毒过程.丹江口水库水采用氯胺化消毒可以降低消毒副产物的生成风险,如采用自由氯消毒方式,水厂需根据实际常规处理工艺重点控制自由氯的投加量等参数.     

Impact of disinfection on drinking water biofilm bacterial community

Disinfectants are commonly applied to control the growth of microorganisms in drinking water distribution systems. However, the effect of disinfection on drinking water microbial community remains poorly understood. The present study investigated the impacts of different disinfectants (chlorine and chloramine) and dosages on biofilm bacterial community in bench-scale pipe section reactors. Illumina MiSeq sequencing illustrated that disinfection strategy could affect both bacterial diversity and community structure of drinking water biofilm. Proteobacteria tended to predominate in chloraminated drinking water biofilms, while Firmicutes in chlorinated and unchlorinated biofilms. The major proteobacterial groups were influenced by both disinfectant type and dosage. In addition, chloramination had a more profound impact on bacterial community than chlorination.     

Influencing factors and degradation products of antipyrine chlorination in water with free chlorine

Owing to its low cost, free chlorine is one of the most common disinfectants for wastewater and drinking water treatment. However, the formation of disinfection byproducts has been found to occur after free chlorine disinfection in recent decades. Antipyrine (ANT), an anti-inflammatory analgesic, has been frequently detected in the aquatic environment. In this work, the removal efficiency of ANT by free chlorine oxidation in ultrapure water was investigated with batch experiments. The influencing factors on the removal of ANT were explored at initial concentrations of ANT from 0.04 to 0.64 mg/L, free chlorine dosage from 0.30 to 1.31 mg/L, and pH from 1.5 to 9.0. The main degradation products were identified by solid phase extraction-gas chromatography-mass spectrometry. The results showed that ANT reacted rapidly with free chlorine in ultrapure water systems and up to 90.6% removal efficiency of ANT was achieved after 25 sec (initial free chlorine 1 mg/L, ANT 0.5 mg/L, pH 7.0). Higher oxidant dosage, lower ANT initial concentration and low pH favor the ANT removal. The main degradation product in ANT chlorination was a monochlorine substitution product (4-chloro-1,2-dihydro- 1,5-dimethyl-2-phenyl-3H-pyrazol-3-one), which can be further chlorinated by free chlorine. In addition, the total organic carbon result indicated that ANT is difficult to be mineralized using chlorine.     

Formation and control of disinfection byproducts and toxicity during reclaimed water chlorination: A review

Chlorination is essential to the safety of reclaimed water; however, this process leads to concern regarding the formation of disinfection byproducts (DBPs) and toxicity. This study reviewed the formation and control strategies for DBPs and toxicity in reclaimed water during chlorination. Both regulated and emerging DBPs have been frequently detected in reclaimed water during chlorination at a higher level than those in drinking water, indicating they pose a greater risk to humans. Luminescent bacteria and Daphnia magna acute toxicity, anti-estrogenic activity and cytotoxicity generally increased after chlorination because of the formation of DBPs. Genotoxicity by umu-test and estrogenic activity were decreased after chlorination because of destruction of toxic chemicals. During chlorination, water quality significantly impacted changes in toxicity. Ammonium tended to attenuate toxicity changes by reacting with chlorine to form chloramine, while bromide tended to aggravate toxicity changes by forming hypobromous acid. During pretreatment by ozonation and coagulation, disinfection byproduct formation potential (DBPFP) and toxicity formation potential (TFP) occasionally increase, which is accompanied by DOC removal; thus, the decrease of DOC was limited to indicate the decrease of DBPFP and TFP. It is more important to eliminate the key fraction of precursors such as hydrophobic acid and hydrophilic neutrals. During chlorination, toxicities can increase with the increasing chlorine dose and contact time. To control the excessive toxicity formation, a relatively low chlorine dose and short contact time were required. Quenching chlorine residual with reductive reagents also effectively abated the formation of toxic compounds.     

饮用水中典型微生物消毒过程中消毒副产物的生成规律

以饮用水中典型微生物--大肠杆菌（Escherichia coli）为试验对象,研究pH值、氯化时间、氯投量及细菌浓度对大肠杆菌在氯化消毒过程中生成消毒副产物（DBPs）的影响,并分析何种氯化条件下,DBPs控制效果最佳.研究表明：随氯投量增加,二氯乙腈（DCAN）呈先上升后下降趋势;随氯化时间延长,三氯丙酮（1,1,1-TCP）和DCAN先增加后减少;在pH值从5升高到9时,1,1,1-DCP、三氯硝基甲烷（TCNM）、二氯乙酸（DCAA）和三氯乙酸（TCAA）持续降低;细菌污染水源事件在近年常有报道,当水源水中细菌浓度增加时,饮用水中三氯甲烷（TCM）、TCNM、DCAA和TCAA浓度增加,但DCAN、三氯乙腈（TCAN）、二氯丙酮（1,1-DCP）和1,1,1-TCP不一定增加.为了达到低毒性的目的,氯投量浓度不宜太高,同时控制氯化时间为6h和pH>8.     

饮用水氯化消毒过程的动力学模型研究进展

饮用水氯化消毒的安全性问题一直是水处理领域的研究重点,其氯化消毒过程动力学过程模型的建立,对于饮用水含氯量监测、评价及生成消毒副产物的控制具有重要意义。本文概述了饮用水氯化消毒过程的有关动力学模型研究现状及进展,从模型依据的机理和表达形式等方面分析了饮用水氯化消毒过程的动力学模型研究进展,介绍了广泛应用的几种模型,如Clark自由氯衰减模型、Valentine氯胺衰减模型等,通过对相关模型的原理、异同点、优缺点、适用性的对比及对影响模型的因素分析,对氯化消毒过程中动力学模型的今后发展趋势作了展望。     

Genotoxicity of drinking water treated with different disinfectants and effects of disinfection conditions detected by umu-test

The genotoxicity of drinking water treated with 6 disinfection methods and the effects of disinfection conditions were investigated using the umu-test. The pretreatment procedure of samples for the umu-test was optimized for drinking water analysis. The results of the umu-test were in good correlation with those of the Ames-test. The genotoxicity and production of haloacetic acids (HAAs) were the highest for chlorinated samples. UV + chloramination is the safest disinfection method from the aspects of genotoxicity, HAA production and inactivation effects. For chloramination, the effects of the mass ratio of Cl₂ to N of chloramine on genotoxicity were also studied. The changes of genotoxicity were different from those of HAA production, which implied that HAA production cannot represent the genotoxic potential of water. The genotoxicity per chlorine decay of chlorination and chloramination had similar trends, indicating that the reaction of organic matters and chlorine made a great contribution to the genotoxicity. The results of this study are of engineering significance for optimizing the operation of waterworks.     

饮用水消毒副产物-卤乙酸的分析检测

卤乙酸是氯化消毒饮用水中一类主要的消毒副产物 ,由于存在的广泛性和潜在的健康危害 ,许多国家和卫生组织相继将其列为饮用水常规监测项目 ,而我国至今还没有相关规定 ;为更好地控制饮用水中卤乙酸的形成 ,世界各国科研人员先后研究和开发出了性能逐趋完善的多种分析检测方法 ;在大量国内外文献调研的基础上 ,对卤乙酸的各种分析检测方法进行系统的介绍 ,并指明今后的发展方向     

Formation of iodo-trihalomethanes, iodo-haloacetic acids, and haloacetaldehydes during chlorination and chloramination of iodine containing waters in laboratory controlled reactions

Iodine containing disinfection by-products (I-DBPs) and haloacetaldehydes (HALs) are emerging disinfection by-product (DBP) classes of concern. The former due to its increased potential toxicity and the latter because it was found to be the third most relevant DBP class in mass in a U.S. nationwide drinking water study. These DBP classes have been scarcely investigated, and this work was performed to further explore their formation in drinking water under chlorination and chloramination scenarios. In order to do this, iodo-trihalomethanes (I-THMs), iodo-haloacetic acids (I-HAAs) and selected HALs (mono-HALs and di-HALs species, including iodoacetaldehyde) were investigated in DBP mixtures generated after chlorination and chloramination of different water matrices containing different levels of bromide and iodide in laboratory controlled reactions. Results confirmed the enhancement of I-DBP formation in the presence of monochloramine. While I-THMs and I-HAAs contributed almost equally to total I-DBP concentrations in chlorinated water, I-THMs contributed the most to total I-DBP levels in the case of chloraminated water. The most abundant and common I-THM species generated were bromochloroiodomethane, dichloroiodomethane, and chlorodiiodomethane. Iodoacetic acid and chloroiodoacetic acid contributed the most to the total I-HAA concentrations measured in the investigated disinfected water. As for the studied HALs, dihalogenated species were the compounds that predominantly formed under both investigated treatments.