常见有机物对催化臭氧化降解水中硝基苯的影响

考察了有机物甲醛、甲醇、甲酸和邻苯二甲酸二丁酯对单独臭氧氧化和蜂窝陶瓷催化臭氧化工艺去除水中硝基苯降解效果的影响规律.单独臭氧氧化和蜂窝陶瓷催化臭氧化对硝基苯的去除率随着甲醛浓度的升高(0～12 mg·L-1)分别降低了11.6%和9.6%;2种工艺对硝基苯的去除率都随着甲醇浓度的增加(0～16mg·L-1,)先增高再降低,单独臭氧氧化和蜂窝陶瓷催化臭氧化分别在浓度为2 mg·L-1和4 mg·L-1时去除率达到最大值;随着甲酸浓度的增加(0～8 mg·L-1)去除率也都先增高再降低,单独臭氧氧化和蜂窝陶瓷催化臭氧化分别在浓度为0.5 mg·L-1和2 mg·L-1时去除率达到最大值;低浓度的甲醇和甲酸促进了硝基苯的降解,高浓度的甲醇和甲酸抑制了硝基苯的降解.单独臭氧氧化和蜂窝陶瓷催化臭氧化在邻苯二甲酸二丁酯浓度增加(0～10 mg·L-1)的情况下对硝基苯的去除率分别降低了19.7%和18.6%.     

纳米铁去除废水中硫离子的研究

研究了实验室自制的纳米铁对人工配制的含硫废水中S2-吸附的影响因素、吸附等温线、吸附动力学.并对纳米铁去除S2-的机制进行了初探.结果表明.增加纳米铁的投加量能增大S2-的去除率;增加初始S2-浓度,去除率下降,<100 mg·L-1的初始S2-浓度能被10 g·L-1纳米铁完全去除;纳米铁对S2-的吸附能力随pH值的升高而下降.且变化较大,pH为2、7、13时的去除率分别为87.34%、65.80%和44.61%;25℃时纳米铁对S2-的吸附能力最强,平衡吸附量为19.17 mg·g-1;温度升高或降低,吸附能力均下降,但变化不大;纳米铁对S2-的吸附等温线符合Langmuir和Freundlich方程;纳米铁吸附S2-的过程符合拟二级动力学方程,初始时刻的吸附速率h在25℃最大,为1.575 3 mg·(g·mg)-1,而吸附速率常数随温度的升高而增大;吸附反应的活化能E.为8.22 kJ·mol-1;纳米铁对S2-的去除主要是通过形成表面络合物、硫氢基氧化铁和硫化铁(FeS、FeS2、FeSn)沉淀吸附在纳米铁表面来去除.     

蜂窝陶瓷催化臭氧化降解水中痕量硝基苯的机理研究

实验考察了HCO3-、CO32-、HPO42-、H2PO4-和叔丁醇等羟基自由基抑制剂存在条件下,单独臭氧氧化和臭氧/蜂窝陶瓷氧化对水中硝基苯降解效果的影响规律,初步推测了反应机理.结果表明,2种工艺对硝基苯的去除率都随着HCO3-浓度的增加(0～200 mg·L-1)先增高再降低,在浓度为50 mg·L-1时去除率达到最大值;单独臭氧氧化和臭氧/蜂窝陶瓷对硝基苯的去除率随着CO32-浓度的增加(0～20 mg·L-1)分别降低了16.57%和27.52%,随着HPO42-浓度的增加(0～12 mg·L-1)分别降低了13.61%和17.52%,随着H2PO4-浓度的增加(0～120 mg·L-1)分别降低了6.61%和12.52%,随着叔丁醇浓度的增加(0～10mg·L-1)硝基苯去除率降低了30.06%和46.09%.证明单独臭氧氧化和臭氧/蜂窝陶瓷氧化对硝基苯的降解遵循·OH氧化机理,叔丁醇更适合作为自由基抑制剂用来推断单独臭氧氧化和臭氧/蜂窝陶瓷氧化降解硝基苯的反应机理.单独臭氧氧化对硝基苯的去除率随着pH值的升高(3.02～10.96)而增大,臭氧/蜂窝陶瓷氧化对硝基苯的去除率在pH=9.23时达到最大值.     

酿酒酵母对Ag^＋的吸附特性研究

为了深入探讨酿酒酵母吸附贵金属离子Ag+的特性,研究了吸附时间、离子浓度、初始pH值、温度对废弃酿酒酵母吸附Ag+的影响,并分析了动力学、热力学以及等温吸附特性.结果表明,酵母吸附Ag+的过程进行得很快,当Ag+初始浓度为1mmol·L-1、细胞浓度2 g·L-1条件下,反应10 min,Ag+可以达到平衡吸附量的86%以上.随后在24 h内吸附量缓慢增加,去除率基本维持在51%～55%左右.酵母吸附Ag+的过程可以用准一级和准二级动力学方程描述,后者模拟效果更好.酵母吸附Ag+的等温吸附过程可以用Langmuir方程描述,但Freundlich方程拟合效果较差.当Ag+初始浓度为0～8 mtool·L-1、酵母浓度2·L-1条件下,酵母吸附Ag+的Langmuir理论饱和生物吸附容量为0.385 mmol·g～.在pH 2.0-7.2范围内,吸附量随着溶液初始pH值升高而升高.10～40℃范围内,温度对酵母吸附Ag+的影响不如pH值的影响显著,特别是在低离子浓度下尤其如此.酵母吸附Ag+的较适宜温度为20～30℃.热力学分析表明,酵母吸附Ag+具有自发性、熵增特征.     

EDTA优化纳米Pd/Fe对2,4-D的催化脱氯研究

采用EDTA优化纳米Pd/Fe催化脱氯水中2,4-二氯苯氧乙酸(2,4-D),并考察了EDTA投加浓度、pH、钯化率、温度等因素对2,4-D还原的影响.结果表明,EDTA的加入络合了纳米Pd/Fe在催化脱氯过程中生成的铁离子,抑制纳米Pd/Fe颗粒表面钝化层的形成,提高了体系的反应活性.适宜的EDTA浓度、低pH、高钯化率、低温等有利于2,4-D的还原脱氯.当EDTA浓度为25.0 mmol·L-1,纳米铁含量为1.0 g·L-1,初始pH=4.3、钯化率为0.5%,温度为25.0℃,搅拌速率为200 r·min~(-1)时,反应50 min,10.0 mg·L-1的2,4-D去除率及苯氧乙酸(PA)生成率均达到100%.     

陶粒负载纳米TiO2催化臭氧化降解水中微量硝基苯

制备了以陶粒为载体的纳米二氧化钛催化剂,并以硝基苯为稳定性有机污染物的目标降解物,研究了其对臭氧化的催化性能,对影响催化效果因素及降解机理进行了探讨.实验对不同温度条件下烧结的催化剂催化臭氧化有机物能力进行了比较,使用SEM进行表征,确定最佳烧结温度.通过改变催化剂投量、硝基苯初始浓度、pH值、添加不同浓度自由基抑制剂和催化剂重复使用实验等,表明在700℃温度下烧结的催化剂具有最大催化活性;硝基苯臭氧化反应中主要氧化剂为羟基自由基,其降解反应为一级反应;硝基苯的去除率随催化剂投量增加而增大;在pH为10时催化剂具有最好的催化效果,对硝基苯的去除率为46.5%;催化剂连续3次重复使用性能良好.     

陶粒负载纳米TiＯ2催化臭氧化降解水中微量硝基苯

制备了以陶粒为载体的纳米二氧化钛催化剂,并以硝基苯为稳定性有机污染物的目标降解物,研究了其对臭氧化的催化性能,对影响催化效果因素及降解机理进行了探讨.实验对不同温度条件下烧结的催化剂催化臭氧化有机物能力进行了比较,使用SEM进行表征,确定最佳烧结温度.通过改变催化剂投量、硝基苯初始浓度、pH值、添加不同浓度自由基抑制剂和催化剂重复使用实验等,表明在700℃温度下烧结的催化剂具有最大催化活性;硝基苯臭氧化反应中主要氧化剂为羟基自由基,其降解反应为一级反应;硝基苯的去除率随催化剂投量增加而增大;在pH为10时催化剂具有最好的催化效果,对硝基苯的去除率为46.5%;催化剂连续3次重复使用性能良好.     

厌氧生物法处理果胶废水的研究

采用经果胶废水驯化的厌氧污泥处理果胶废水,考察了果胶浓度、温度对厌氧去除果胶和COD的影响,并对降解产物进行了分析.结果表明,与未驯化厌氧污泥处理果胶废水相比,驯化后的污泥对果胶去除率提高了59.2%.果胶浓度分别为100、2 500和4 500 mg·L-1时,果胶降解速率分别为4.5、49.8和74.0 mg·(L·h)-1,说明果胶浓度越高,降解速率越快.果胶浓度低于500 mg·L-1,COD去除率较低,仅为41.6%~82.0%,果胶浓度高于1 000 mg·L-1,COD去除率稳定在91%以上.温度越高,降解果胶所需的时间越短.随着温度在5~35℃范围内变化,厌氧污泥对果胶废水中COD的去除率从38.6%逐渐增加到91.5%,当温度高于35℃时,厌氧污泥对果胶废水中COD的去除率逐渐降低.果胶降解的中间产物主要是乙酸、丙酸、低级酯、烷基醇(C12~C40).     

硅胶负载纳米TiO2催化臭氧化降解水中微量硝基苯的研究

研究了纳米TiO2负载于硅胶表面作为臭氧氧化硝基苯过程中的催化剂时,热处理温度对催化活性的影响.结果表明,在700℃条件下烧结的纳米TiO2/硅胶表现出了最佳活性,反应10min硝基苯去除率相比于单独臭氧氧化提高了约25%.在一定范围内催化剂投量越大,硝基苯去除率越高.碱性pH环境有利于催化臭氧化反应的进行,但当pH值高于10时,硝基苯去除率有所降低.催化臭氧化反应遵循一级反应,反应速率常数与硝基苯的初始浓度无关.典型的自由基捕获剂叔丁醇与碳酸根离子对硝基苯的降解有强烈的抑制作用,间接地证明催化臭氧化反应遵循自由基作用机理.反应温度为10～40℃之间时,硝基苯去除率随着温度升高而提高.催化剂重复使用实验证明TiO2在硅胶表面负载牢固,催化剂具有较好的稳定性与耐用性.     

光助芬顿反应催化降解气体中甲苯

以甲苯作为挥发性有机污染物(VOCs)的代表,利用连续进气动态实验装置,研究光助芬顿反应降解气体中甲苯的作用.考察了芬顿试剂溶液初始p H、H2O2浓度、Fe2+浓度以及甲苯初始浓度对降解甲苯的影响,并利用在线质谱和色谱对产物进行了定性、定量分析.结果表明,紫外光照加快了羟基自由基的生成,显著提高了气体中甲苯的去除率;p H=3.0、H2O2浓度为20 mmol·L-1、Fe2+浓度为0.3 mmol·L-1的条件下,甲苯去除率最高;当甲苯初始浓度为260 mg·m-3时,去除率能够达到98%;光助芬顿反应催化降解气体中甲苯实验未检测到CO2之外的中间产物,CO2产率分析表明去除的甲苯全部转化为CO2.     

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.     

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.     

Effects of chitosan on growth of an aquatic plant (Hydrilla verticillata) in polluted waters with different chemical oxygen demands

Effects of chitosan on a submersed plant, Hydrilla verticillata, were investigated. Results indicated that H. venicillata could prevent ultrastructure phytotoxicities and oxidativereaction from polluted water with high chemical oxygen demand (COD). Superoxide dismutase (SOD) activity and malondialdehyde (MDA) contents in H. verticillata treated with 0.1% chitosan in wastewater increased with high COD (980 mg/L) and decreased with low COD (63 mg/L), respectively. Ultrastructural analysis showed that the stroma and grana of chloroplast basically remained normal. However, plant cells from the control experiment (untreated with chitosan) were vacuolated and the cell interval increased. The relict of protoplast moved to the center, with cells tending to disjoint. Our findings indicate that wastewater with high COD concentration can cause a substantial damage to submersed plant, nevertheless, chitosan probably could alleviate the membrane lipid peroxidization and ultrastructure phytotoxicities, and protect plant cells from stress of high COD concentration polluted water.     

Removal of cadmium using MnO2 loaded D301 resin

MnO2 loaded weak basic anion exchange resin D301 （Anion exchange resin, macroreticular weak basic styrene） as adsorbent has been prepared and applied to the removal of cadmium. The adsorption characteristics have been investigated with respect to effect of pH, equilibrium isotherms, removal kinetic data, and interference of the coexisting ions. The results indicated that the Cd^2＋ could be efficiently removed using MnO2 loaded D301 resin in the pH range of 3-8 from aqueous solutions with the co-existence of high concentration of alkali and alkaline-earth metals ions. The saturate adsorption capacity of the Cd^2＋ was 77.88 mg/g. The adsorption process followed the pseudo first-order kinetics. The equilibrium data obtained in this study accorded excellently with the Langmuir adsorption isotherm.     

Evaluation of phytoextracting cadmium and lead by sunflower, ricinus, alfalfa and mustard in hydroponic culture

Soil contaminated with heavy metals cadmium(Cd)and lead(Pb)is hard to be remediated.Phytoremediation may be a feasible method to remove toxic metals from soil,but there are few suitable plants which can hyperaccumulate metals.In this study,Cd and Pb accumulation by four plants including sunflower(Helianthus annuus L.),mustard(Brassica juncea L.),alfalfa(Medicago sativa L.), ricinus(Ricinus communis L.)in hydroponic cultures was compared.Results showed that these plants could phytocxtract heavy metals, the ability of accumulation differed with species,concentrations and categories of heavy metals.Values of BCF(bioconcentration factor)and TF(translocation factor)indicated that four species had dissimilar abilities of phytoextraction and transportation of heavy metals.Changes on the biomass of plants,pH and Eh at different treatments revealed that these four plants had distinct responses to Cd and Pb in cultures.Measurements should be taken to improve the phytoremediation of sites contaminated with heavy metals,such as pH and Eh regulations,and so forth.     

Effect of coagulation pretreatment on the fouling of ultrafiltration membrane

The purpose of this study is to understand the effect and mechanism of preventing membrane fouling, by coagulation pretreatment, in terms of fractional component and molecular weight of natural organic matter （NOM）. A relatively higher molecular weight （MW） of hydrophobic compounds was responsible for a rapid decline in the ultrafiltration flux. Coagulation could effectively remove the hydrophobic organics, resulting in the increase of flux. It was found that a lower MW of neutral hydrophilic compounds, which could remove inadequately by coagulation, was responsible for the slow declining flux. The fluxes in the filtration of coagulated water and supernatant water were compared and the results showed that a lower MW of neutral hydrophilic compounds remained in the supernatant water after coagulation could be rejected by a membrane, resulting in fouling. It was also found that the coagulated flocs could absorb neutral hydrophilic compounds effectively. Therefore, with the coagulated flocs formed on the membrane surface, the flux decline could be improved.     

Penetration analysis of elements and bioleaching treatment of spent refractory for recycling

Acidithiobacillus ferrooxidans ATCC23270 and Acidithiobacillus thiooxidans TM-32 were used for bioleaching of spent refractories of aluminium and copper melting furnaces for their recycling.Firstly,penetration of elements into aluminium melting furnace refractory was investigated and it was found that up to 7 cm from surface was contaminated.Comparison on leaching efficiency by the strains ATCC23270 and TM-32 found that the strain ATCC23270 could treat larger amount of the refractories than the strain TM-32 could do.In the experiment of bioleaching of spent refractory aluminium melting furnace by the strain ATCC23270,high leaching efficiency were obtained on Al,Si,and Ca,and extremely low leaching performance was,however,shown on the rest of elements i.e.,Na,Mn,and Zn.Under the strain TM-32 use,relatively high leaching performance was recognized on Al,Si,Ca,Na,Mn,and Zn.In the experiment of bioleaching for spent refractory copper melting furnace,almost the same leaching trends were shown on Cu,Zn,Al,and Si under the strains ACTT23270 and TM-32 uses.