纳米铁炭复合材料的制备及对水中镉(Cd)污染的修复

为提高纳米零价铁对水体中镉污染的修复效果,通过液相化学还原法制备纳米零价铁颗粒,并用活性炭包覆,制备纳米铁炭复合材料。设计单因素和正交实验,探讨材料制备中的3个主要因素对材料降解水体中镉(Cd(II))的影响。结果表明:在炭铁比为0.2,硼氢化钠加料速率为32 m L/min,搅拌强度为1 000 r/min的条件下,材料对水体中Cd(II)的降解效果最好;实验表明纳米铁炭复合材料对Cd(II)的去除以纳米零价铁的化学还原过程为主,活性炭的物理吸附为辅。     

纳米零价铁/生物炭材料吸附Cr(Ⅵ)的研究

为治理工业废水中重金属铬污染,该文以梧桐叶为原料、绿茶滤液为绿色还原剂制备出纳米零价铁/生物炭复合材料,对材料的微观形貌、所含官能团、元素组成等理化性质进行表征,考察其对水中Cr（Ⅵ）的吸附去除性能。结果表明：纳米零价铁颗粒均匀附着于光滑舒展的生物炭表面,材料含有酚类、烯烃、芳香化合物和醇类等多种有机化合物,负载纳米零价铁后生物炭本身的石墨结构无显著变化,XRD谱图具有零价铁的特征峰。600℃热解制备生物炭,Fe/C负载比为1∶24的负载纳米零价铁生物炭材料,投加量2.0 g,对50 mL初始浓度为10 mg/L Cr（Ⅵ）溶液吸附60 min后,最大去除率为58.72%。     

生物表面活性剂改性对纳米铁/炭去除地下水中NO3--N的影响

纳米铁由于其反应活性强、来源广泛等优点被广泛应用在去除地下水NO-3-N污染中.利用生物表面活性剂对纳米铁进行改性可以避免采用化学表面活性剂改性对环境造成的二次污染.本研究采用鼠李糖脂、茶皂素、无患子3种生物表面活性剂对纳米铁进行改性后附着在活性炭上构成改性纳米铁/炭复合材料,通过批试验、沉降试验、迁移试验等研究生物表面活性剂对纳米铁/炭复合材料的改性作用.结果表明:鼠李糖脂、茶皂素、无患子对纳米铁/炭改性后去除NO-3-N效果最佳时的投加量分别为0.7%、1.0%、0.7%,此时对比三者改性作用,鼠李糖脂改性纳米铁/炭去除NO-3-N效果最佳,无患子改性纳米铁/炭迁移效果最佳;鼠李糖脂投加量在0.1%到1.3%范围内时,改性纳米铁/炭迁移能力随投加量的增加而增大.     

铁炭填料去除模拟矿山酸性废水中Cu~(2+)的特性

研究了多孔铁炭填料对模拟矿山酸性废水中Cu~(2+)的去除特性,并与商业活性炭的吸附性能作了比较。研究表明,铁炭填料对Cu~(2+)的去除速度快,当填料投加量为1.14 g/L时,吸附10 min后Cu~(2+)的去除率超过95%,吸附平衡后Cu~(2+)的去除率达99.96%,模拟矿山酸性废水经铁炭微电解处理后,pH值从约3.0上升到5.0~5.5,降低了其酸污染。铁炭填料和活性炭对酸性矿山废水中Cu~(2+)的去除均符合准二级吸附动力学规律和Langmuir等温吸附模型,铁炭填料和活性炭对Cu~(2+)的最大吸附量分别为714.29和9.69 mg/g,铁炭填料去除Cu~(2+)的性能远高于活性炭。铁炭微电解去除Cu~(2+)包括了吸附、金属置换、微电解和絮凝等多种作用机理。     

CTMAB/CPAM/膨润土复合材料的制备与应用

以钠基膨润土为原料,CTMAB、CPAM为改性剂制备复合改性膨润土。探讨了最佳制备条件为:CTMAB投加量2 mmol,CPAM投加量0.03 g,原土投加量6 g,搅拌速度200 r/min,改性时间大于1.5 h。FTIR和XRD对复合改性膨润土进行表征,表明CTMAB、CPAM进入膨润土层间,扩大了膨润土的层间距从而提高了吸附性能。在原水浓度191 600 mg/L,改性土投加量2 g,搅拌时间1~3 h,pH值6~8,搅拌速度200~300 r/min,离心速度1 400 r/min,离心时间2 min的工艺条件下,制药废水COD去除率可达70%。吸附动力学研究结果表明准二级动力学模型能很好地描述膨润土复合材料对制药废水的吸附过程。     

糠醛废渣制备活性炭对糠醛废水的脱色研究

以水蒸气为活化剂,用热解糠醛废渣制备活性炭,着重研究了所制备的活性炭对糠醛废水的脱色性能. 结果表明:糠醛废渣制备的活性炭对糠醛废水脱色的最佳温度为50 ℃,并且在很短的时间内即可完成,该活性炭与糠醛废水混合搅拌15 min后,脱色率几乎不再变化. 由于采用糠醛废渣制备活性炭的成本较低,可以适当增加活性炭的投加量以提高糠醛废水的脱色率. 当活性炭投加量为10 g/L时,50 ℃条件下搅拌10 min,糠醛废水脱色率可达到86.65%. 经活性炭脱色后的糠醛废水无色、透明,以去离子水为参比溶液测定其吸光度,与自来水相当.      

基于绿色合成法的纳米铁/活性碳复合材料对甲基橙的降解动力学研究

为了综合处理废水中的甲基橙,以绿茶萃取液为还原剂、活性炭为载体,采用液相还原法绿色合成了纳米铁/活性炭复合材料,研究了活性炭投放量、甲基橙溶液的初始浓度、溶液初始p H值及反应时间对甲基橙去除率的影响,探讨了不同影响因素下甲基橙的降解动力学。结果表明:甲基橙的降解反应近似符合一级反应动力学,反应速率常数为0.0047~0.0158 L/(mol·min)。在纳米铁/活性炭复合材料去除甲基橙的过程中,通过纳米铁的还原和活性炭的吸附共同作用,其中纳米铁对甲基橙的降解起主要作用。     

石墨烯负载铁镍复合材料去除水中的2,4-二氯酚

通过液相还原法成功制备了石墨烯负载纳米铁镍复合材料,该材料可高效快速地吸附水中的2,4-二氯酚(2,4-DCP)并对其进行脱氯.微观形貌分析结果表明,粒径为80～150nm的球形Fe/Ni纳米颗粒成功插入石墨烯片层,并主要分布在石墨烯片层边缘和褶皱处,Fe/Ni颗粒团聚现象明显减少,更多活性位点暴露出来.XRD分析和FTIR分析表明,纳米零价铁(nZVI)通过Fe-O键成功嵌入石墨烯(r GO)中,且Fe/Ni纳米颗粒结晶度较差,外围包覆有无定形的铁氧化物沉淀.探讨了不同制备条件如碳铁比、镍化率、氧化石墨烯(GO)还原程度对材料去除2,4-二氯酚(2,4-DCP)性能的影响.综合考虑材料制备成本及对2,4-DCP的吸附脱氯性能,Fe/Ni@rGO复合材料的最优制备条件为:石墨烯与Fe质量比1:2,镍负载率5%,硼氢化钠与铁盐的物质的量比为5:1.研究表明5种材料对2,4-DCP的去除率遵循如下顺序:Fe/Ni@rGO复合材料>Fe/Ni>Fe@rGO复合材料>石墨烯>nZVI.储存稳定性试验和循环试验表明,与Fe/Ni双金属相比,Fe/Ni@rGO材料具有稳定的...     

改性纳米铁/炭填充PRB去除地下水硝态氮研究

采用鼠李糖脂对纳米铁进行改性后负载在活性炭上制备出改性纳米铁/炭,将其作为PRB填充材料,并采用有机玻璃柱模拟连续墙式PRB来进行水中硝态氮地去除研究.结果表明：经过改性后的纳米铁能够有效负载在活性炭上,悬浮稳定性得到明显提高;改性纳米铁/炭粒径远大于纳米铁,将其作为填充材料可有效缓解PRB堵塞问题;当纳米铁与活性炭质量比为5：2时,PRB运行效果最佳;pH值越小,污染液硝态氮浓度越低,水流速度越小均有利于硝态氮地去除.     

铁炭复合材料对水体中SAs吸附去除性能的研究

以木炭作为载体,固载水合氧化铁,采用抽真空旋转蒸发法制备铁炭复合材料,通过比较不同制备条件下复合材料对水体中磺胺类抗生素的去除效果,对制备条件进行优化。并采用批量平衡试验,研究了铁炭复合材料对磺胺类抗生素的吸附去除特性。结果表明:以Fe(NO3)3溶液浸渍,铁炭质量比为0.224∶1,固化9 h条件下去除水体中磺胺类抗生素效果最佳;铁炭复合材料对磺胺和磺胺吡啶的去除效果明显优于单一炭材料,铁炭复合材料对磺胺和磺胺吡啶的去除率随抗生素初始浓度增加而降低,酸性条件下磺胺和磺胺吡啶去除率高于中性和碱性条件,溶液中背景离子强度变化对磺胺和磺胺吡啶的去除影响较小;铁炭复合材料对磺胺和磺胺吡啶的去除符合一级动力学模型,为物理化学吸附和化学降解的协同作用,且在反应过程中生成中间产物。     

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.     

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.     

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

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