纳米零价铁颗粒去除As(III)和As(V)的动力学过程及性能研究

本研究系统分析了不同初始砷浓度和不同nZVI投加量等条件下,nZVI去除As（III）和As（V）的动力学过程和除砷性能.结果表明,nZVI可快速有效地去除As（III）和As（V）,除砷过程均符合准二级动力学模型,且As（III）的去除速率明显快于As（V）.在砷浓度为5 mg·L^-1时,As（III）去除速率常数达最大值0.30 g·mg^-1·min^-1,为As（V）去除速率（0.034 g·mg^-1·min^-1）的8.8倍.Weber-Morris粒子内扩散模型拟合结果表明,nZVI除砷速率是由外扩散和颗粒内扩散共同控制的.分析反应平衡时砷浓度测定结果,发现不同砷浓度条件下nZVI对As（III）的去除量为As（V）的1.5~2.6倍,nZVI对砷的去除量随初始砷浓度增加而降低,随nZVI投加量增加而增加.砷浓度为50.0 mg·L^-1时,As（III）和As（V）去除量达到最高,分别为152.14 mg·g^-1和62.02 mg·g^-1,均高于传统（羟基）氧化铁对As（III）和As（V）的去除量.因此,nZVI可高效去除水中As（III）和As（V）,且用于修复以As（III）污染为主的地下水更具有优势.     

原位形成生物铁锰氧化物对砷(Ⅲ/V)的去除效果与机制

通过改变砷的初始浓度、砷价态、细菌接种比、铁锰浓度等因素来研究不同条件下Pseudomonas putida strain MnB1原位诱导形成生物铁锰氧化物（Biogenic Fe-Mn oxides,BFMO）对As（Ⅲ）和As（V）的去除效果与机制.结果表明：①当As（Ⅲ）和As（V）初始浓度为0.5~5 mg·L^-1时,原位形成的BFMO对As（Ⅲ）和As（V）有良好的去除效率,均在62%以上;②当细菌接种比为0.1%~0.5%时,As（Ⅲ）和As（V）的去除效率与细菌接种比成正比,当细菌接种比大于0.5%时,As（Ⅲ）和As（V）的去除效率基本维持在85%以上,未发生明显变化;③当MnCO₃浓度为0.2~0.8 g·L^-1或Fe（Ⅱ）浓度为2.5~25 mg·L^-1时,原位诱导产生的BFMO对As（Ⅲ）和As（V）的去除率随MnCO₃浓度或Fe（Ⅱ）浓度的增加而增大;当MnCO₃或Fe（Ⅱ）浓度再升高时,As（Ⅲ）和As（V）的去除效率基本保持不变.微观特征分析结果表明,原位形成的BFMO与As（Ⅲ）和As（V）反应后主要产物为As（V）,其去除主要以吸附为主,还存在共沉淀作用.总体而言,原位形成的BFMO适用于砷污染水环境的修复.     

负载AsOB离子交换纤维FFA-1去除水中三价砷

对比两组填充了离子交换纤维FFA-1的固定床反应器（R1和R2）的运行处理效果,研究负载功能微生物的离子纤维组合工艺对不同浓度As（III）的去除能力.研究结果表明接种了三价砷氧化菌（AsOB）的R1能够长期稳定并高效地去除不同浓度（1~10 mg·L^-1）As（III）.未接种AsOB的R2反应器初期无法去除As（III）,随着微生物逐步侵入R2反应器,7 d后R2反应器As（III）去除率逐渐与R1接近.相对于一直稳定运行的R1反应器,每次提升进水中As（III）浓度后R2去除率呈现先下降后上升的趋势.同时,在运行过程中发现进水中NO₃^-和SO₄^2-等阴离子也会被R1和R2去除从而导致As（III）去除总量的下降.离子交换纤维FFA-1再生实验证实R1和R2中的纤维与原始的离子交换纤维FFA-1再生效果相当（再生率均达到90%以上）.进一步研究微生物种群结构在反应器中的变化发现离子交换纤维作为微生物载体可能是影响微生物种群结构的重要因素.本研究证实了功能微生物AsOB联合离子交换纤维可以作为一种高效去除地下水中三价砷的工艺,具有很好的应用前景.     

锰氧化物负载施氏矿物去除酸性矿山废水中As(III)的性能及机理

施氏矿物是天然的砷吸附剂,但其存在酸性条件下对As(III)吸附性能较弱且无法对As(III)氧化降毒的缺陷. 采用液相沉淀法成功制备出锰氧化物负载施氏矿物(MnO_x@Sch),研究锰负载量、初始pH值和共存离子对MnO_x@Sch去除As(III)的影响,并采用吸附动力学结合XPS、FTIR及TEM等表征探究该过程的机理. 结果表明:在初始pH=3、投加量为0.5 g·L^-1、As(III)初始浓度为1 mg·L^-1的条件下,As(III)与MnO_x@Sch反应后的剩余浓度仅为2.42~3.38 μg·L^-1.MnO_x@Sch去除As(III)受初始pH影响较小,H₂PO₄^-共存时As(III)去除存在明显的抑制作用. MnO_x@Sch 去除As(III)的过程符合准二级动力学方程和颗粒内扩散方程. 液相化学组分和固相产物表征分析显示MnO_x@Sch对As(III)的去除机理可概括为As(III)氧化、静电吸附和络合配位及配体交换. 研究结果可为施氏矿物及其改性材料应用于酸性矿山废水砷污染治理提供理论依据.     

BiVO4表面氧缺陷调控及其光催化氧化三价砷

以乙二醇为溶剂,采用溶剂热-煅烧法制备缺陷型BiVO₄光催化剂,通过控制溶剂热反应时间调控BiVO₄表面氧缺陷以增强对As （III）的光催化氧化性能.同时,借助各种表征手段如XRD、SEM和XPS等分析样品的晶型结构、形貌特征及化学组成等性质,考察其在可见光下对As（III）的光催化氧化性能,并研究其氧化机理.结果表明,溶剂热反应时间对BiVO₄的晶粒尺寸和光吸收性能没有影响,但能通过影响比表面积调控BiVO₄的表面氧缺陷浓度.经优化得到,反应时间为14 h时制备的BiVO₄光催化剂（BiVO-14）对As（III）（6 mg·L^-1）的氧化效率高达95.7%,并具有良好的光催化稳定性.BiVO₄氧化As （III）的主要途径是光生空穴（h⁺）的直接氧化作用.表面氧缺陷能增强导电性能,促进电荷分离和迁移,强化h⁺的氧化作用,从而提高BiVO₄的光催化氧化性能.BiVO-14能有效促使As（III）转化为低毒的As（V）,在饮用水源As污染去除方面具有广阔应用前景.     

碱/抗坏血酸活化分子氧氧化水中As（III）

研究了碱/抗坏血酸（H₂A）活化分子氧体系（碱/H₂A体系）氧化水中三价砷（As（III））的过程与机理.考察了pH、H₂A浓度、As（III）初始浓度、水中常见阴离子（Cl^-、NO₃^-、HCO₃^-）和有机质富里酸对As（III）氧化效率的影响,通过自由基抑制实验及电子自旋共振（ESR）鉴定了体系中的活性氧物质（ROS）,并采用液相色谱-质谱分析技术鉴定了H₂A的降解产物.结果表明,在pH=9~12范围内,pH值越高,As（III）氧化速率越快;pH=10条件下,随着H₂A浓度从0.05 mmol·L^-1增加到1 mmol·L^-1,反应1 h后,As（III）氧化率从24%增加至92%.机理研究结果表明,H₂O₂是碱/H₂A活化分子氧体系中氧化As（III）的主要ROS,它主要来自碱性条件下H₂A与分子氧的单电子或双电子反应,同时,体系中H₂A也发生了氧化性降解.碱/H₂A体系可用于含砷废水的预处理,并与离子交换吸附方法联合,实现高效除砷.     

BiOBr分子印迹材料的制备及其降解诺氟沙星性能

为了有效处理低浓度抗生素残留废水,以水热法制备的BiOBr为载体,诺氟沙星（NOR）为模板,通过表面分子印迹法制备了BiOBr分子印迹材料（MIP）.同时,采用SEM与XRD对制备的材料进行相分析及显微结构分析,并利用XPS、FTIR、BET和UV-Vis DRS对所合成材料的微观结构进行观察.最后,以诺氟沙星（NOR）为目标污染物,对MIP在暗反应下的吸附性能及300 W Xe灯照射下的光催化性能进行测定,并探讨pH、投加量、初始浓度、是否印迹处理对NOR去除的影响.实验结果表明,在pH为中性,MIP投加量为2.5 g·L^-1的条件下,MIP对5 mg·L^-1 NOR溶液的去除率达到96.2%,且对低浓度（1 mg·L^-1）NOR溶液的去除率达到99%.综合表明,本文所制备的MIP适用于低浓度诺氟沙星废水的处理.     

甲苯、邻二甲苯和二氯甲烷混合气体降解菌群构建及其性能研究

挥发性有机物（VOCs）排放导致一系列环境问题,而生物法是一项绿色处理技术.本实验选取3种VOCs（甲苯、邻二甲苯、二氯甲烷）作为模型污染物,利用甲苯、邻二甲苯降解菌Zoogloea resiniphila HJ1（菌株HJ1）及二氯甲烷降解菌Methylobacterium rhodesianum H13（菌株H13）构建复合菌株,采用“专属菌+综合菌”模式以复合菌株和驯化污泥构建复合强化菌群.研究表明,复合菌株可完全降解400 mg·L^-1甲苯、256 mg·L^-1邻二甲苯、200 mg·L^-1二氯甲烷,矿化率分别为74.3%、61.1%、82.7%.复合菌株可完全降解480 mg·L^-1混合污染物（3种污染物浓度比为1∶1∶1）,降解速率依次为甲苯>邻二甲苯>二氯甲烷.经过优化,菌株HJ1和菌株H13最佳配比被确定为1∶5.复合强化菌群不仅大幅提高了 邻二甲苯、二氯甲烷降解速率,还提高了混合污染物矿化率.甲苯、邻二甲苯的存在对二氯甲烷降解产生明显抑制效应,而低浓度二氯甲烷 （< 240 mg·L^-1）对甲苯、邻二甲苯降解无明显抑制作用.本研究为VOCs生物净化过程中菌群构建提供数据支撑.     

桉树生物炭负载绿色合成纳米零价铁去除水中Cr (Ⅵ)

以桉树叶提取物绿色合成的纳米零价铁（nZVI）为主体,使用桉树生物炭（EBC）负载,成功制备一种高效去除Cr （Ⅵ）的复合材料（EBC-nZVI）,考察单一材料和复合材料去除Cr （Ⅵ）的效果差异和循环利用潜力;并研究投加量和溶液初始pH对去除效果的影响.使用GC-MS分析合成前后提取液中成分变化,通过SEM-EDS、FTIR、XRD和XPS对材料表征,结合吸附动力学和吸附等温线实验讨论去除机制.结果表明,绿色合成过程中桉树叶提取液提供了充当还原剂和封端剂的生物分子,复合材料分散性良好并有效缓解nZVI的钝化.复合材料去除Cr （Ⅵ）的过程中EBC和nZVI表现出协同作用,在pH为3,投加量1g·L^-1条件下对100mg·L^-1的Cr （Ⅵ）溶液去除率达到99.5%以上,且具有良好的循环利用潜力.EBC-nZVI吸附过程符合准二级动力学模型和Langmuir吸附等温模型,活性位点与Cr （Ⅵ）的化学吸附过程是去除速率的主要限制因素.EBC-nZVI与Cr （Ⅵ）的反应机制是nZVI和Fe （Ⅱ）将吸附的Cr （Ⅵ）还原为Cr （Ⅲ）,然后通过表面络合、官能团吸附和共沉淀以FeOOH、Fe₂O₃、Cr （OH）₃和Cr₂O₃的形式实现去除.     

会仙岩溶湿地水体金属元素分布与健康风险评价

以我国最大的低海拔岩溶湿地会仙岩溶湿地为研究区域,对该区域内4种主要类型水（井水、地表河水、地下河水和溶潭水）的23组样品中9种金属元素（As、Cr、Al、Cu、Pb、Zn、Ni、Mn和Hg）进行检测和分析,运用多元统计方法和健康风险评价模型分别研究了9种金属元素在4种类型水中的浓度特征和健康风险.结果显示,会仙岩溶湿地水体中金属元素平均浓度顺序为Al > Mn > Zn > Cr > Ni > As > Hg > Cu > Pb,井水中Hg（1.08 μg ·L^-1）、地表河水中Hg（0.78 μg ·L^-1）和Mn（259.00 μg ·L^-1）以及溶潭水中Hg（0.47 μg ·L^-1）和Al（300.00 μg ·L^-1）的最大浓度已超过我国相应水质标准,地下河水样中未出现金属元素超标.从水体中金属元素角度,井水和地下河水质总体优于地表河水和溶潭水.井水中Cr、Ni、Cu和Zn浓度主要与地质背景值有关,溶潭水中Al和Pb浓度主要受北部硫铁矿开采和居民活动影响,河流中As和Mn浓度可能受旅游活动、渔业养殖和河道底泥综合影响.健康风险评价结果显示,4种类型水中9种金属元素通过饮用水途径和皮肤入渗途径引起的年均总健康风险顺序为井水 > 地下河水 > 溶潭水 > 地表河水,井水中金属元素通过饮用水途径对成人（6.11×10^-5 a^-1）和儿童（6.67×10^-5 a^-1）引起的年均总健康风险值已超过最大可接受风险水平（5.0×10^-5 a^-1）.Cr是引起年均致癌健康风险的主要金属元素.从饮用水安全角度,在饮用前需对井水中的Hg和Cr污染物进行适当控制.     

Toxic effects of acetochlor, methamidophos and their combination on nifH gene in soil

Toxic effects of two agrochemicals on nifH gene in agricultural black soil were investigated using denaturing gradient gel electrophoresis （DGGE） and sequencing approaches in a microcosm experiment. Changes of soil nifH gene diversity and composition were examined following the application of acetochlor, methamidophos and their combination. Acetochlor reduced the nifH gene diversity （both in gene richness and diversity index values） and caused changes in the nifH gene composition. The effects of acetochlor on nifH gene were strengthened as the concentration of acetochlor increased. Cluster analysis of DGGE banding patterns showed that nifH gene composition which had been affected by low concentration of acetochlor （50 mg/kg） recovered firstly. Methamidophos reduced nifH gene richness that except at 4 weeks. The medium concentration of methamidophos （150 mg/kg） caused the most apparent changes in nifH gene diversity at the first week while the high concentration of methamidophos （250 mg/kg） produced prominent effects on nifH gene diversity in the following weeks. Cluster analysis showed that minimal changes of nifH gene composition were found at 1 week and maximal changes at 4 weeks. Toxic effects of acetochlor and methamidophos combination on nifH gene were also apparent. Different nifH genes （bands） responded differently to the impact of agrochemicals： four individual bands were eliminated by the application of the agrochemicals, five bands became predominant by the stimulation of the agrochemicals, and four bands showed strong resistance to the influence of the agrochemicals. Fifteen prominent bands were partially sequenced, yielding 15 different nifH sequences, which were used for phylogenetic reconstructions. All sequences were affiliated with the alpha- and beta-proteobacteria, showing higher similarity to eight different diazotrophic genera.     

EDTA-enhanced phytoremediation of lead contaminated soil by Bidens maximowicziana

Phytoremediation is a potential cleanup technology for the removal of heavy metals from contaminated soils.Bidens maximowicziana is a new Pb hyperaccumulator,which not only has remarkable tolerance to Pb but also extraordinary accumulation capacity for Pb.The maximum Pb concentration was 1509.3 mg/kg in roots and 2164.7 mg/kg in overground tissues.The Pb distribution order in the B. maximowicziana was:leaf>stem>root.The effect of amendments on phytoremediation was also studied.The mobility of soil Pb and the Pb concentrations in plants were both increased by EDTA application.Compared with CK(control check),EDTA application promoted translocation of Pb to overground parts of the plant.The Pb concentrations in overground parts of plants was increased from 24.23-680.56 mg/kg to 29.07-1905.57 mg/kg.This research demonstrated that B.maximowicziana appeared to be suitable for phytoremediation of Pb contaminated soil,especially,combination with EDTA.     

Distribution and ecological effect of mercury in Laogang landfill, Shanghai, China

Laogang landfill near Shanghai is the largest landfill in China, and receives about 10000 t of daily garbage per day, Samples of topsoil and plants were analyzed to evaluate mercury pollution from the landfill. For topsoil samples, there were significant correlations among total mercury （HgT）, combinative mercury （Hgc） and gaseous mercury （HgG）, and content of total organic carbon （TOC）, but, no significantly relationship was found between Hg content and filling time. Hg content changes in vertical profiles with time showed that the average Hgv of profiles 1992, 1996, and 2000 was similar, but their average HgG was quite different. HgT was significantly correlated with Hgc in profile 1992 and 2000, and Hgv was significantly correlated with Hg6 in profile 1996. HgG/Hgv ratio in profile samples decreased in the order of （HgG,/HgT）1992〉（HgG/HgT）1996〉〉（HgG/HgT）2000. A simple outline of Hg release in landfill could be drawn： with increasing of filling time, degradation undergoes different biodegradation, accordingly, gaseous mercury goes through small, more, and small proportion to total mercury. Distribution of Hg in plants was inhomogeneous, following the order of leaf〉root〉stem. The highest value of leaf may be associated with higher atmospheric Hg from landfill. Ligneous plants （e.g. Phyllostachys glanca, Prunus salicina and Ligustrum lucidum） are capable of enriching more Hg than herbaceous plants.     

Arsenic uptake by arbuscular mycorrhizal maize （Zea mays L.） grown in an arsenic-contaminated soil with added phosphorus

The effects of arbuscular mycorrhizal (AM) fungus (Glomus mosseae) and phosphorus (P) addition (100 mg/kg soil) on arsenic (As) uptake by maize plants (Zea mays L.) from an As-contaminated soil were examined in a glasshouse experiment.Non-mycorrhizal and zero-P addition controls were included.Plant biomass and concentrations and uptake of As,P,and other nutrients,AM colonization,root lengths,and hyphal length densities were determined.The results indicated that addition of P significantly inhibited root colonization and development of extraradical mycelium.Root length and dry weight both increased markedly with mycorrhizal colonization under the zero-P treatments,but shoot and root biomass of AM plants was depressed by P application.AM fungal inoculation decreased shoot As concentrations when no P was added,and shoot and root As concentrations of AM plants increased 2.6 and 1.4 times with P addition,respectively.Shoot and root uptake of P,Mn,Cu,and Zn increased,but shoot Fe uptake decreased by 44.6%,with inoculation, when P was added.P addition reduced shoot P,Fe,Mn,Cu,and Zn uptake of AM plants,but increased root Fe and Mn uptake of the nonmycorrhizal ones.AM colonization therefore appeared to enhance plant tolerance to As in low P soil,and have some potential for the phytostabilization of As-contaminated soil,however,P application may introduce additional environmental risk by increasing soil As mobility.     

Enzymatic oxidation of aqueous pentachlorophenol

The influence of the nonionic surfactant Tween 80 on pentachlorophenol （PCP） oxidation catalyzed by horseradish peroxidase was studied. The surfactant was tested at concentrations below and above its critical micelle concentration （CMC）. Enhancement of PCP removal was observed at sub-CMCs. The presence of Tween 80 in the reaction mixture reduced enzyme inactivation which occurred through a combination of free radical attack and sorption by precipitated products. A simple first-order model was able to simulate time profiles for enzyme inactivation in the presence or absence of Tween 80. At supra-CMCs, the surfactant caused noticeable reductions in PCP removal, presumably through micelle partitioning of PCP which precluded the hydrophobic PCP molecule from interacting with the enzyme.     

Decomposition of alachlor by ozonation and its mechanism

Decomposition and corresponding mechanism of alachlor, an endocrine disruptor in water by ozonation were investigated. Results showed that alachlor could not be completely mineralized by ozone alone. Many intermediates and final products were formed during the process, including aromatic compounds, aliphatic carboxylic acids, and inorganic ions. In evoluting these products, some of them with weak polarity were qualitatively identified by GC-MS. The information of inorganic ions suggested that the dechlorination was the first and the fastest step in the ozonation of alachlor.     

Degradation of metabolites accumulated of benzo[a]pyrene by coupling Penicillium Chrysogenum with KMnO4

Several main metabolites of benzo[a]pyrene （BaP） formed by Penicillium chrysogenum, Benzo[a]pyrene-1,6-quinone （BP 1,6- quinone）, trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene （BP 7,8-diol）, 3-hydroxybenzo[a]pyrene （3-OHBP）, were identified by high-performance liquid chromatography （HPLC）. The three metabolites were liable to be accumulated and were hardly further metabolized because of their toxicity to microorganisms. However, their further degradation was essential for the complete degradation of BaP. To enhance their degradation, two methods, degradation by coupling Penicillium chrysogenum with KMnO4 and degradation only by Penicillium chrysogenum, were compared; Meanwhile, the parameters of degradation in the superior method were optimized. The results showed that （1） the method of coupling Penicillium chrysogenum with KMnO4 was better and was the first method to be used in the degradation of BaP and its metabolites; （2） the metabolite, BP 1,6-quinone was the most liable to be accumulated in pure cultures; （3） the effect of degradation was the best when the concentration of KMnO4 in the cultures was 0.01% （w/v）, concentration of the three compounds was 5 mg/L and pH was 6.2. Based on the experimental results, a novel concept with regard to the bioremediation of BaP-contaminated environment was discussed, considering the influence on environmental toxicity of the accumulated metabolites.     

Impact of atrazine and nitrogen fertilizers on the sorption of chlorotoluron in soil and model sorbents

Sorption of chlorotoluron in ammonium sulfate, urea and atrazine multi-solutes system was investigated by batch experiments. The results showed application of nitrogen fertilizers to the soil could affect the behavior of chlorotoluron. At the same concentration of N, sorption of chlorotoluron decreased as the concentration of atrazine increased on the day 0 and 6 in soil, respectively. The sorption of chlorotoluron increased from 0 to 6 d when soils were preincubated with deionized water, ammonium sulfate and urea solution for 6 d. That indicated incubation time was one of the most important factors for the sorption of chlorotoluron in nitrogen fertilizers treatments. The individual sorption isotherms of chlorotoluron in rubbery polymer and silica were strictly linear in single solute system, but there were competition sorption between pesticides or between pesticides and nitrogen fertilizers. That indicated the sorption taken place by concurrent solid-phase dissolution mechanism and sorption on the interface of water-organic matter or water-mineral matter.     

基于综合水质标识指数和对应分析法的校园河道水质评价

以三峡大学的校园河道求索溪为研究对象,利用综合水质标识指数法确定求索溪水质类别,分析其水质时空变化规律,并利用对应分析法得出求索溪中不同监测点的主要污染因子.研究结果表明:求索溪整体的综合水质标识指数为7.423,整体水质为劣V类(地表水环境质量标准GB 3838-2002)且黑臭.从时间变化来看,求索溪4月份的水质最差,5月份次之,4、5月份所有监测点的水质都劣于V类且黑臭;8月份水质最好,水质为Ⅳ类;从空间分布来看,8个监测点综合水质标识指数均超过6.0,水质为劣V类,其中6号监测点的水质相对最好,监测点3号的水质相对最差;对应分析法得出求索溪的整体水体污染程度受总氮因子的影响最大,其次为总磷.该研究拟为求索溪及类似校园河道的水环境治理研究提供基础依据和参考.     

Potential of plant polyphenol oxidases in the decolorization and removal of textile and non-textile dyes

In this study an effort has been made to use plant polyphenol oxidases; potato （Solanum tuberosum） and brinjal （Solanum melongena）, for the treatment of various important dyes used in textile and other industries. The ammonium sulphate fractionated enzyme preparations were used to treat a number of dyes under various experimental conditions. Majority of the treated dyes were maximally decolorized at pH 3.0. Some of the dyes were quickly decolorized whereas others were marginally decolorized. The initial first hour was sufficient for the maximum decolorization of dyes. The rate of decolorization was quite slow on long treatment of dyes. Enhancement in the dye decolorization was noticed on increasing the concentration of enzymes. The complex mixtures of dyes were treated with both preparations of polyphenol oxidases in the buffers of varying pH values. Potato polyphenol oxidase was significantly more effective in decolorizing the dyes to higher extent as compared to the enzyme obtained from brinjal polyphenol oxidase. Decolorization of dyes and their mixtures, followed by the formation of an insoluble precipitate, which could be easily removed simply by centrifugation.