臭氧氧化降解水中青霉素G特性和动力学特征

为考察水中PCN（青霉素G）在臭氧氧化过程中的降解规律与特征,采用臭氧直接氧化法处理模拟废水中的PCN,研究了初始pH、ρ（臭氧）、初始ρ（PCN）、自由基抑制剂TBA（叔丁醇）、反应温度等对水中PCN去除效果的影响,并分析了PCN在臭氧氧化降解过程中的降解特性和动力学特征.结果表明:①在溶液体积为1 L、初始ρ（PCN）为50 mg/L、初始pH为11、ρ（臭氧）为15 mg/L、反应温度为20℃时,反应5 min时PCN去除率为100%,反应2 h时TOC去除率为28.98%.②PCN的降解速率和TOC去除效果随pH的增大而升高,碱性环境有利于PCN的矿化.③臭氧氧化过程中,PCN的降解以臭氧直接氧化为主,其降解中间产物的矿化主要以臭氧间接氧化为主,TBA可抑制强氧化性羟基自由基的产生效率,因而对TOC的矿化有明显的抑制作用.④对PCN的降解过程进行一级、伪一级和二级动力学方程拟合,结果表明,伪一级动力学方程拟合相关性（R2=0.999 7）最高,k（反应速率常数）最大值为0.825 5 min-1.研究显示,臭氧直接氧化可有效降解水中PCN,但对中间产物的矿化去除效果较为有限,臭氧氧化降解PCN的过程遵循伪一级反应动力学方程.      

饮用水中甲羟孕酮的臭氧氧化降解研究

以饮用水中内分泌干扰物孕激素类甲羟孕酮(MPA)为目标物,采用臭氧氧化工艺对其进行降解,对臭氧降解过程动力学进行了研究,并考察液相臭氧浓度、pH、羟基自由基(.OH)清除剂(HCO3-)对降解过程的影响.结果表明,臭氧在合适条件下能够有效降解水溶液中的MPA,MPA初始浓度为3、5、10 mg.L-1,采用连续臭氧曝气方式降解时,降解过程遵守一级反应动力学模型;采用序批式臭氧投加方式进行降解时,降解过程符合二级反应动力学模型.pH的升高和HCO3-的添加都会对降解效果产生负面影响.在反应温度为20℃,采用序批式臭氧投加方式,MPA的去除率从pH=3.10时的89.8%下降到pH=9.02时的74.6%.相同反应条件下,添加羟基自由基清除剂HCO3-后,降解反应速率常数由0.146 3 L.(mg.min)-1下降到0.049 5 L.(mg.min)-1,去除率下降了22.2个百分点.     

敌敌畏的臭氧氧化处理

在12 L的反应器中,观察了臭氧浓度分别为4.9、6.7和7.6 mg/L,溶液温度10.50℃,pH值为3.1、5.3、7.2、9.4和11.2条件下,臭氧氧化浓度为30 mg/L的有机磷杀虫剂敌敌畏的处理效果,并计算了臭氧氧化敌敌畏的反应动力学.结果表明,臭氧氧化法是处理敌敌畏的高效方法.不同浓度臭氧处理5 min时敌敌畏的去除率均在96%以上,6.7 mg/L的臭氧氧化处理敌敌畏4 min时矿化度(以TOC 计)可达34.8%.臭氧浓度越高,敌敌畏的降解速率越快.随着敌敌畏初始浓度的升高,敌敌畏的氧化去除率下降,但绝对去除量升高.试验范围内的pH值和温度对敌敌畏的臭氧氧化去除效果影响不大.在臭氧浓度6.7 mg/L,pH 7.2和室温20℃的条件下,臭氧氧化敌敌畏的反应级数为0.11,反应速率常数k为7.72 mg·(L·min)-1.     

臭氧及催化臭氧化降解2,4-滴丙酸动力学研究

对臭氧及催化臭氧氧化降解2,4-滴丙酸(DCPP)的效率进行了研究,并利用竞争动力学法算得了DCPP与臭氧及羟基自由基的反应速率常数,参比有机物为硝基苯(NB).结果表明,DCPP与臭氧的反应速率常数K-DCPP为(0.733±0.163)L·mol-1·s-1,与羟基自由基的kOH-DCPP为2.367×109L·mol-1·s-1.在单独臭氧和Mn(Ⅱ)催化臭氧化降解DCPP过程中,基于上述结果计算所得的速率常数与实际所测的表观反应速率常数具有较好的吻合度.以上结果对臭氧化处理含DCPP废水具有很好的理论指导意义.     

臭氧降解水中苯并三唑反应动力学及效能研究

对臭氧氧化去除水中痕量苯并三唑(BTri)的反应动力学、效能及其影响因素进行了实验研究.结果表明,臭氧分子与BTri直接反应速率常数k_Ｏ3=20.18 L·(mol·s)^-1,臭氧与BTri反应的表观反应速率常数K_BTri随pH值的不同而有显著差异,当pH值由6.63增加到7.83时,表观反应速率常数由63.42 L·(mol·s)^-1提高至582.69 L·(mol·s)^-1,增加约8倍.单独臭氧化可以有效地去除水体中痕量BTri,最终去除率可达85％;随着水体pH值的增加及水体温度的升高,BTri的反应速率大幅度提高;自然水体中常见阴离子NO^-₃、SO^2-₄、Cl^-对臭氧化去除BTri的去除率及反应速率无明显影响;羟基自由基(·OH)抑制剂叔丁醇对臭氧氧化去除BTri有一定的抑制作用,说明·OH也对臭氧氧化去除BTri有一定的贡献,表明臭氧化去除BTri的过程为O₃直接氧化及·OH间接氧化共同作用的结果.     

MgO低温催化臭氧降解氨氮的机制研究

研究了低温条件下单独臭氧及MgO催化臭氧化降解水中氨氮的效率和特征,并对其反应机制分别进行了探讨.结果表明,pH是影响臭氧和催化臭氧化除氨的重要因素,不仅影响溶液中NH_3与NH~+_4的比例和臭氧氧化氨氮的速率,还影响氧化产物种类,从而影响脱氮效果.10℃时,单独臭氧对水中氨氮的氧化降解效率随pH的升高而增大,pH≤9时整体降解效率不高,pH=9时仅为16.39%,而pH=10时达到41.77%.臭氧和·OH共同参与降解氨氮的过程.单独臭氧氧化氨氮生成氮气的选择性具有pH依赖性,并与Cl~-密切相关.pH低(≤9)时,氨氮多以NH~+_4形态存在,O_3与Cl~-反应生成ClO~-_x(x=1、3),再氧化NH~+_4,从而生成气态产物N_2或N_2O.MgO在低温条件下具有很强的催化臭氧化降解氨氮的能力且温度升高有利于反应的进行,0、10、20℃时,MgO催化臭氧化氨氮的效率分别为77.53%、80.17%、91.26%.此过程中,·OH参与反应的程度低,一部分氨氮降解依靠ClO~-_x氧化NH~+_4,而氨氮降解的主要途径为O_3对NH_3的直接氧化.     

CuO-Ru/A_2lO_3催化臭氧化降解苯乙酮的研究

采用浸渍法制备了以活性Al2O3为载体的双组分催化剂CuO-Ru/Al2O3,利用该催化剂催化臭氧化降解了苯乙酮.结果表明,贵金属钌掺杂能显著提高CuO/Al2O3催化臭氧化苯乙酮的降解效率,如在相同条件下处理30 min后,单独臭氧氧化、CuO/Al2O3/O3和CuO-Ru/Al2O3/O3对苯乙酮水溶液的COD去除率分别为6.3%、20.0%和54.0%.pH对CuO-Ru/Al2O3催化臭氧化降解苯乙酮的效率并没有影响,但与单独臭氧化相比,该催化臭氧化体系更适合在中性或酸性条件下应用.CuO-Ru/Al2O3对水中臭氧有较好的催化分解活性,臭氧分解的速率常数达2.58×10-3s-1,高于二次水中臭氧的分解速率常数1.19×10-3s-1.叔丁醇的试验结果表明,CuO-Ru/Al2O3/O3降解苯乙酮反应遵循羟基自由基(.OH)反应机制.     

CuO-Ru/Al2O3 催化臭氧化降解苯乙酮的研究

采用浸渍法制备了以活性Al2O3为载体的双组分催化剂CuO-Ru/Al2O3,利用该催化剂催化臭氧化降解了苯乙酮.结果表明,贵金属钌掺杂能显著提高CuO/Al2O3催化臭氧化苯乙酮的降解效率,如在相同条件下处理30 min后,单独臭氧氧化、CuO/Al2O3/O3和CuO-Ru/Al2O3/O3对苯乙酮水溶液的COD去除率分别为6.3%、20.0%和54.0%.pH对CuO-Ru/Al2O3催化臭氧化降解苯乙酮的效率并没有影响,但与单独臭氧化相比,该催化臭氧化体系更适合在中性或酸性条件下应用.CuO-Ru/Al2O3对水中臭氧有较好的催化分解活性,臭氧分解的速率常数达2.58×10-3s-1,高于二次水中臭氧的分解速率常数1.19×10-3s-1.叔丁醇的试验结果表明,CuO-Ru/Al2O3/O3降解苯乙酮反应遵循羟基自由基(.OH)反应机制.     

臭氧作用下酮洛芬的降解行为及机理研究

利用臭氧(O_3)氧化降解酮洛芬(KET)模拟废水,考察了初始pH值,臭氧流量(Q_(O_3)),反应温度(T)及KET初始浓度(C_0)对臭氧降解KET效果的影响.在KET初始浓度为20μmol/L,臭氧流量0.4L/min的反应体系中,室温条件下,研究了pH=4,7,10时O_3和羟基自由基(·OH)分别对KET降解的贡献率.采用竞争法,以布洛芬和苯甲酸为分子探针,分别测定了KET与O_3,·0H的二级反应速率常数.结果表明,不同实验条件下臭氧降解KET符合准一级动力学.pH值,Q_(O_3)及T的增大促进了KET降解,C_0的增大抑制了KET的降解.通过对实验数据进行拟合得到表观一级动力学的幂指数方程(k=154439exp(-32831/RT)Q_(O_3))~(0.679)C_0~(-0.2)[OH~-]~(0.07)).体系中O_3和·OH同时对KET存在氧化作用.在设定的条件下,pH值为4,7和10时O_3对KET降解的贡献率分别为18.4%,11.0%和6.2%,而·OH对KET降解的贡献率分别为81.6%,89.0%和93.8%.测得KET与O_3的二级反应速率常数为1.09L/(mol·s),与·OH的二级反应速率常数为8.82×l0~9L/(mol·s).     

蜂窝陶瓷催化臭氧化降解水中草酸的研究

实验比较了单独臭氧氧化、蜂窝陶瓷催化臭氧化和蜂窝陶瓷催化剂吸附3种工艺去除水中草酸的降解效果.结果表明,蜂窝陶瓷催化臭氧化、单独臭氧氧化和蜂窝陶瓷催化剂吸附对水中草酸的去除率分别为37 .6%、2 .2%和0 .4%,蜂窝陶瓷催化剂的存在显著提高了臭氧氧化降解水中草酸的去除效果.添加叔丁醇的浓度为5、10和15 mg·L^-1时,催化臭氧化对草酸的去除率分别降低了24 .1%、29 .0%和30 .1%,证明蜂窝陶瓷催化臭氧化降解水中草酸遵循·OH氧化机理,即非均相的催化剂表面强化了·OH的引发.TOC测试结果显示,蜂窝陶瓷催化臭氧化工艺可以将草酸彻底矿化,无中间产物生成.反应温度与草酸的去除效果成正相关性,当水体温度为10、20、30和40℃时,蜂窝陶瓷催化臭氧化降解水中草酸的去除率分别为16 .4%、37 .6%、61 .3%和68 .2%.     

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.     

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.     

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.     

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.     

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.     

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.     

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.     

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.     

Removal of heavy metals from sewage sludge by low costing chemical method and recycling in agriculture

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