水合氧化铁对含磷废水的吸附特性研究

以Fe(NO3)3为前驱物,制备了水合氧化铁吸附剂样品,以NaOH为解吸剂,研究了样品对模拟废水中磷酸根的吸附和解吸性能。结果表明,水合氧化铁对磷酸根有较好的吸附效果;随着pH的降低,水合氧化铁对磷酸根的吸附能力增强,在pH为2时吸附达92.5%;吸附前15 min吸附速率较快,约150 min达到平衡,吸附动力学曲线符合二级动力学模型;用水合氧化铁对初始浓度为50~100 mg/L模拟含磷废水吸附,随着初始浓度的增大,磷的去除率下降;水合氧化铁对磷酸根的吸附等温线较符合Langmuir吸附模型;用NaOH对水合氧化铁行解吸,浓度为40 g/L有最好的解吸率,60 min时达到解吸平衡。     

水合氧化铁对废水中磷酸根的吸附-解吸性能研究

以FeCl₃为原料制备水合氧化铁吸附剂,研究其对废水中磷酸根的吸附-解吸性能.结果表明,随着溶液pH的降低,水合氧化铁对磷酸根的吸附能力不断提高,其吸附动力学曲线符合二级动力学模型,吸附等温线符合Langmuir吸附模型.被吸附的磷酸根在50 g/L的NaOH溶液中进行解吸,解吸率>98%.解吸率与单位水合氧化铁的吸附饱和程度没有相关性.利用水合氧化铁对城市某污水处理厂污泥浓缩池上清液进行磷的吸附和解吸实验,结果表明该工艺对磷的回收率>90%.根据实验结果设计了城市污水中磷去除和回收工艺流程,该流程包括：吸附过程、解吸再生过程、富磷解吸液中磷回收等过程.     

CTAB作用下绿色合成纳米铁的制备及降解孔雀绿

化学合成纳米铁存在成本高和二次污染等问题,探寻低成本、环境友好的合成方法是纳米技术在环境修复中的研究热点之一.本课题组前期采用绿茶提取液(GTE)还原Fe2+合成纳米铁颗粒(Fe NPs),发现GTE合成的Fe NPs易被氧化和团聚.本文采用阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)对绿色合成纳米铁形貌和粒径进行改善,提高了纳米铁颗粒的分散性和抗氧化性.通过SEM、XRD、FT-IR、UV-vis等表征手段对GTE合成的Fe NPs和CTAB作用下合成的Fe NPs的微观结构表征以及对孔雀绿降解效果对比表明:CTAB作用下合成的Fe NPs分散均匀,CTAB的包覆提高了Fe NPs的稳定性,从而提高了Fe NPs的反应活性.GTE合成的Fe NPs对孔雀绿的去除率为75.66%,而CTAB作用下绿色合成的Fe NPs的去除率高达91.06%.最后,提出了CTAB作用下GTE合成Fe NPs的可能机理.     

石英砂负载氧化铁的表征及其除锑吸附性能研究

通过SEM/EDAX以及Nova-1000表面分析仪对石英砂负载的氧化铁颗粒进行了表征,发现负载氧化铁的粒径为200 nm左右,其表面孔径及孔隙率分别为2×10-9～9×10-9m及0.11%,负载氧化铁的石英砂的比表面积为原砂的5倍.考察了石英砂负载氧化铁(IOCS)在不同的实验条件下(吸附时间,pH值,温度等)对水溶液中锑的去除效果,在pH为3～9范围内,其去除率均超过了98%.吸附动力学及吸附等温线实验数据分别符合二级反应动力学模型及Langmuir等温吸附模型.热动力学实验结果进一步表明:IOCS吸附锑的过程是自发的、吸热的化学吸附反应.     

生物质基纳米HZO杂化材料的研制及其除磷特性

采用3-氯-2-羟丙基三甲基氯化胺(CTA)对生物质秸秆进行胺基化改性获得St-N',通过正交试验确定其最佳合成条件为Na OH质量分数30%、CTA体积100 m L、反应温度80℃、反应时间3h.通过原位沉积法将纳米水合氧化锆(HZO)固载于St-N'内部,制备得到生物质基纳米HZO杂化材料St-N'-Zr.SEM、TEM、XRD与BET等技术表明纳米HZO已成功负载于StN'内部,以无定形为主,分布均匀,粒径为50~100 nm.批次吸附实验结果表明,St-N'-Zr吸附磷酸根符合Langmuir吸附等温模型,最大吸附量为33.90 mg·g-1;最佳吸附pH为1.8~6.0,可用于酸性水体除磷;强竞争离子体系中,磷去除率始终高于初始吸附量的70%,性能明显优于商用阴离子交换树脂D-201,吸附选择性良好.经10次吸附-解吸循环,再生性能良好,表明在水体磷污染深度治理领域具有一定应用潜力.     

反应气氛对绿色合成纳米铁的组分及其活性的影响

成本低廉和无二次污染的"绿色"合成纳米材料是发展原位纳米环境修复技术的前沿研究课题之一.本文以绿茶提取液为还原剂和稳定剂进行"绿色"合成纳米铁,探讨在不同的气氛下"绿色"合成的纳米铁颗粒的主要成分,以期为调控合成纳米铁系材料提供基础研究.首先,利用扫描电子显微镜(SEM)、X射线能谱(EDS)、X射线光电子能谱分析(XPS)和傅里叶变换红外光谱(FTIR)等表征手段对不同反应气氛下合成的纳米铁颗粒的表面微观形貌、尺寸和价态结构进行分析.结果发现,在通入N2情况下,合成的纳米铁颗粒粒径为(84.7±11.5)nm,其主要成分以纳米零价铁为主;在通入空气情况下,合成的纳米铁粒径为(117.8±26.2)nm,其主要成分是纳米零价铁、氧化铁和四氧化三铁的混合物;通入O2时,合成的纳米铁粒径为(141.2±26.3)nm,其主要成分以四氧化三铁为主.其次,评价在不同气氛条件下合成纳米铁颗粒对去除亚甲基蓝(MB)的反应活性.结果表明,在反应温度313 K下降解初始浓度为50 mg·L-1的MB溶液,反应5 min时已达到平衡,通入N2合成的纳米铁降解MB,去除率高达98.7%,而通入O2合成的纳米铁反应效率低,对MB的去除率仅为65.3%.最后,从以上发现提出不同气氛下可以调控"绿色"合成的铁系纳米材料成分,从而导致不同的纳米修复环境中污染物的能力.     

四氧化三铁/聚乙烯亚胺纳米颗粒的制备及除磷性能的研究

采用化学共沉淀法,以聚乙烯亚胺(PEI)为改性剂,制备了聚乙烯亚胺改性的纳米四氧化三铁复合材料(Fe3O4/PEI).Zeta电位、透射电镜和FTIR表征结果显示,PEI修饰提高了纳米Fe3O4在水中的分散性和稳定性,同时也增强了其表面正电荷,从而提高了Fe3O4对水中磷酸根的去除能力.在磷酸根初始浓度为50 mg·L~(-1),Fe3O4/PEI投加量为200 mg,p H=3,温度为25℃的条件下,Fe3O4/PEI对100 m L磷酸根的吸附去除率达到91%.吸附过程在3 h内达到平衡.吸附等温数据表明,该吸附过程符合Langmuir吸附等温方程,可决系数R2达到0.99,最大吸附量为29.88 mg·L~(-1).Fe3O4/PEI复合材料重复利用性好,在第5次吸附-解析后还能保持对磷酸根75%以上的吸附去除率.磷的解析效率随着p H增加而增加,在p H=13时,解析效率达到65%.     

尿素分解共沉淀法中反应时间对 ZnAl类水滑石结构和磷吸附性能的影响

采用尿素分解均匀共沉淀法合成了一系列反应时间不同的ZnAl类水滑石,考察了其结构特征及其对水中磷酸根的吸附性能.结果表明,随着反应时间由12 h增加至96 h,制得的ZnAl均具有典型的类水滑石层状结构,但其中的n(Zn)/n(Al)由2.06降至0.70,比表面积升至ZnAl-12的7.6倍.样品中Al比例升高引起的层板正电性增加以及样品比表面积的升高引起了ZnAl对水中磷酸根的吸附性能总体上随着其制备反应时间的增加逐渐增强,同时表明表面的物理化学吸附在磷酸根的去除过程中具有重要作用.当反应时间为24 h时,制备得到的ZnAl类水滑石由于其很高的可交换阴离子含量而具有最高的磷酸根吸附性能,其在25℃的饱和吸附量(以P计)约为34.1 mg.g-1.这说明离子交换也是一种十分重要的磷去除途径.此外,不同反应时间制得的类水滑石对磷酸根的吸附等温线表现为Langmuir型;测得的磷吸附动力学结果均符合准二级动力学方程.     

载镧磁性水热生物炭的制备及其除磷性能

将小麦秸秆在水热条件下(220℃)炭化2 h得到水热生物炭(HTC),以HTC为载体,通过一步共沉淀法制备了一种吸附容量高、易于磁分离回收的载镧磁性水热生物炭复合材料(La-MHTC).通过等温线和动力学等吸附实验方法,研究了该材料对磷酸根的吸附特性,考察了载镧量、初始pH和共存离子等因素对磷酸根吸附过程的影响.结果表明La~(3+)∶Fe~(3+)为2∶1时,材料(2-La-MHTC)具有良好的吸附磷酸根的能力;在吸附剂投加量为0. 1 g·L~(-1),pH为7时,对磷酸盐吸附量达到100. 25mg·g~(-1);吸附符合Langmuir等温模型,吸附动力学过程遵循准二级动力学,并且吸附不受其它离子的影响(在Cl~-、NO_3~-和SO_4~(2-)等共存离子体系磷酸盐去除率达到98%),在较广的pH(3～10)范围都具有良好的吸磷能力.吸附的磷酸根可用NaOH溶液解吸,5次吸附-脱附循环实验中磷酸盐去除率均能达到90%以上,脱附效率为65%左右,说明该吸附剂具有良好的脱附和重复利用能力.应用其处理实际含磷污水,可将磷酸盐浓度从0. 87 mg·L~(-1)降低到0. 05 mg·L~(-1).吸附机制主要为静电吸附作用和La(OH)_3与磷酸盐通过配体交换形成内层络合物.     

改性麦草秸秆对水中磷酸根吸附效果的研究

为实现农作物秸秆资源化,解决水体富营养化问题,将麦草秸秆化学改性成一种可以有效吸附水体中磷酸根的阳离子型吸附剂.考察了吸附剂投加量、磷酸根溶液初始pH、温度等因素对吸附效果的影响,分析了改性麦草秸秆对磷酸根的吸附动力学过程和吸附机理.结果表明,在吸附剂投加量为4 g·L-1和磷酸根溶液初始pH为4.0～7.5条件下,改性麦草秸秆对磷酸根的吸附效果最好,去除率均高于90%;改性麦草秸秆对磷酸根的吸附符合Freundlich等温模式,饱和吸附容量为2.38 mmol·g-1;吸附过程符合一级反应动力学方程,为快速反应过程;反应活化能为12.6 kJ·mol-1,反应速率对温度的变化不敏感.     

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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