高效磷吸附剂Mg/Al-LDO的制备及除磷机制

针对污水中磷的去除问题,采用优化后的恒定pH值共沉淀法制备了Mg/Al-layered double hydroxides(Mg/Al-LDHs),经高温焙烧得到高效磷吸附剂Mg/Al-layered double oxide(Mg/Al-LDO);在对其吸附特性研究的基础上,并结合Zeta电位、XRD、FTIR分析吸附前后材料等电点、晶体结构及层间阴离子的变化,探讨Mg/Al-LDO吸附除磷机制.结果表明,采用优化后的共沉淀法,在Mg/Al比为2∶1,焙烧温度450℃,焙烧时间2 h条件下制备出的Mg/Al-LDO对磷酸根吸附性最好,最大吸附容量可达到176.94 mg·g-1,与理论吸附容量191.57 mg·g-1基本一致,远高出Mg/Al-LDHs及其它磷吸附剂.实验数据对准二级反应动力学模型的拟合结果较好,吸附过程符合Langmuir吸附等温模型.结合Zeta电位、XRD、FTIR的结果推测,Mg/AlLDO吸附除磷主要是通过静电引力、阴离子插层、离子交换、表面配位这4种作用协同完成.     

粘土颗粒吸附直接染料的分形特征

粘土颗粒对直接耐晒黑和直接大红染料的吸附均可分为快速的边缘覆盖和慢速的晶层吸附2个过程,整个吸附过程符合准-二级反应动力学方程式,除了伊利土-直接耐晒黑染料的吸附体系之外,其它体系的吸附过程中以晶层吸附为主的阶段均具有类分形特征.体系的非线性吸附等温线符合Langmuir型吸附等温模式,并且除了蒙脱土吸附直接大红染料之外,也可以用分形Langmuir吸附等温模式获得较好的模拟效果.在不同原始浓度下直接大红染料在粘土颗粒表面发生的边缘覆盖和晶层吸附这2个过程的程度是不同的,从而导致了吸附等温线在原始染料为150mg·L-1时出现最大的吸附量,而且颗粒边缘覆盖的直接大红染料的比例较高.染料进入粘土颗粒的晶层后,扩大了晶层间距,改变了其表面微孔几何结构.颗粒表面棱角变得光滑,结构疏松,片层结构逐渐减少,上述效果在蒙脱土颗粒上或直接耐晒黑染料吸附时表现地更为显著.而且吸附染料后蒙脱土颗粒对N2的吸附量比伊利土下降的幅度小,其比表面积、孔体积和平均孔径的下降比例也比伊利土小,其中平均孔径的差异比较明显.吸附染料之后粘土颗粒表面分形维数Ds均升高了,晶层膨胀和开孔作用抵消了"表面粗糙度屏蔽"、"孔阻塞效应"机理降低Ds的影响.增加了表面粗糙度.     

不同岩性对氨氮吸附影响的实验研究

用粉砂、粉质粘土、粉土为材料,研究不同岩性对垃圾填埋场渗滤液中NH4 -N的吸附作用.同时对粉砂、粉质粘土、粉土吸附NH4 -N的机理进行了初步探讨.实验结果表明,三种岩性吸附N出-N的等温吸附曲线均符合Langmuir模式,且最大吸附量分别为粉砂1.653mg/g,粉质粘土1.735 mg/g,粉土0.358mg/g.不同岩性吸附NH4 -N的能力差异较大,三种岩性的吸附顺序为:粉质粘土＞粉砂＞粉土.说明粉砂和粉质粘土的防污能力较粉土强.     

阴离子粘土(LDH)吸附腐殖酸的动力学研究

利用实验室制备的镁铝阴离子粘土材料,研究其吸附水中腐殖酸的动力学.研究结果表明:在初始浓度10～40 mg/L及温度298～323 K的范围内,阴离子粘土对水中腐殖酸的吸附动力学符合拟二级速率方程;阴离子粘土对腐殖酸的吸附符合Langmuir和Freundlich等温吸附方程,吸附是吸热反应,吸附量随温度升高而略有增加,但吸附表观活化能只有15.36 kJ/mol,说明温度对此吸附的影响并不显著.     

Ac-Co/UiO-66对水中阴离子染料的吸附性能

通过溶剂热法在醋酸改性的条件下制备合成了新型钴掺杂的UiO-66纳米颗粒（Ac-Co/UiO-66）,并采用SEM、XRD和BET分析证实了材料主体结构的合成.同时,以阴离子染料直接蓝、达旦黄和刚果红为目标污染物,系统研究了吸附时间、初始浓度、pH因素对Ac-Co/UiO-66吸附效果的影响.结果表明,吸附进行120 min后3种染料的吸附量趋于平衡,吸附过程均符合拟二级动力学模型,证明化学吸附是主要的速率控制步骤.3种染料的吸附等温数据均采用Langmuir等温线模型拟合效果较好,证明染料分子在Ac-Co/UiO-66上属于单层吸附,直接蓝、达旦黄和刚果红的Langmuir最大吸附容量分别为378.3、525.8、1234.6 mg·g^-1.Ac-Co/UiO-66适合在酸中性环境去除染料.在二元染料体系中发现阴离子染料之间的吸附具有拮抗效应,且染料浓度比的增大会导致染料的竞争效应向独立效应演变.染料的吸附机理涵盖了氢键作用、静电作用及π-π堆积作用力.Ac-Co/UIO-66对直接蓝、达旦黄和刚果红的吸附容量经历4个循环后分别维持在71.2%、65.3%和91.4%.     

铁有机骨架材料的快速合成及对阴离子染料的吸附性能

染料废水色度高,难以生化处理,吸附法是有色废水处理的重要方法.采用常温快速合成铁有机骨架材料,通过IR和XRD对合成的材料进行表征;并研究铁有机骨架材料对阴离子染料的吸附性能.结果表明常温快速反应能够合成铁有机骨架材料,材料比表面积和孔体积较高,等电点p H为3.7.铁有机骨架材料在酸性条件下更容易吸附水中的阴离子染料;随染料浓度的增加,材料对染料的吸附量逐渐增大,Langmuir恒温吸附模型可以很好描述该过程,计算的吸附参数表明吸附过程容易进行.材料对染料的吸附为准二级动力学,染料结构会显著影响铁骨架材料吸附过程,络合结构的偶氮染料能够快速达到吸附平衡.     

水中高氯酸根的颗粒活性炭吸附过程及影响因素分析

通过批量实验研究了颗粒活性炭(GAC)对水中高氯酸根(ClO-4)的吸附特性,考察了pH、ClO-4初始浓度和共存阴离子对吸附作用的影响,并分析了吸附动力学和等温吸附模型.结果表明, GAC对ClO-4的吸附容量在碱性条件下减小,随初始浓度升高而增大,共存阴离子与ClO-4在GAC上存在竞争吸附,其影响顺序为SO2-4 > NO-3 > CO2-3 > H2PO-4 > BrO-3≈Cl-. ClO-4在GAC上的吸附最符合准二级动力学模型,吸附中存在大孔扩散过程,且孔扩散可能为GAC吸附ClO-4的主要速率控制步骤.试验浓度范围内吸附过程符合Langmuir、Freundlich和Tempkin 3种等温吸附模型,吸附过程是自发且放热的,温度升高不利于GAC对ClO-4的吸附,温度为288、298和308K时的饱和吸附容量分别为13.00、11.21和8.04 mg'g-1.说明GAC虽较易吸附水中ClO-4,但必须控制反应条件,如温度、pH和共存阴离子浓度等,以取得最佳吸附效果.     

Mg-Al-Me (Me=La,Ce,Zr)复合氧化物制备及其除氟性能

采用双滴共沉淀-煅烧法制备Mg-Al-Me(Me=La,Ce,Zr)金属复合氧化物吸附剂,通过扫描电子显微镜(SEM)和X射线衍射(XRD)对制备的吸附剂进行表征.采用批实验考察了吸附时间,初始氟浓度和共存离子(Cl~-、NO_3~-、SO_4~(2-)、CO_3~(2-)、HCO_3~-、PO_4~(3-))对氟吸附性能的影响.结果表明,3种吸附剂对氟吸附过程可用准二级动力学模型描述.3种吸附剂对氟吸附速率主要受液膜扩散速率、颗粒内扩散速率和吸附反应速率共同控制.等温吸附结果显示Mg-Al-La对氟吸附能力最大,MgAl-Ce次之,Mg-Al-Zr最小,3种材料对氟吸附规律均符合Langmuir等温吸附方程,其最大饱和吸附量分别为54.22、51.65、50.89 mg·g-1.共存离子对3种材料吸氟存在不同程度的竞争,其影响次序是Cl~-NO_3~-SO_4~(2-)CO_3~(2-)≈HCO_3~-PO_4~(3-).     

阴离子交换树脂对水杨酸的吸附与解吸性能

研究了714阴离子交换树脂对水中水杨酸的吸附与解吸性能,探讨了吸附的热力学和动力学特性.结果表明,树脂在pH=4～12时,吸附能力最好.等温吸附遵循Freundlich和Langmuir吸附平衡模型,为优惠吸附过程.在298～318K条件下,水杨酸吸附量为100～120mg/g的吸附焓变为-23.4-21.6kJ/mo...     

N、S共掺杂活化碳球对四环素的吸附特性与机理

四环素(Tetracycline,TC)是最常见的广谱抗生素之一,滥用四环素对环境所造成的危害日渐引起人们重视.为高效去除水体中残留的四环素,本研究以葡萄糖为碳基原料,通过添加阴离子表面活性剂和硫脲,采用水热反应和KOH高温活化法制备了氮硫共掺杂活化碳球(NSC).随后进行批量吸附试验,并利用等温吸附模型(Langmuir、Freundlich、Temkim、D-R模型)和吸附动力学模型(准一级动力学、准二级动力学、Elovich模型、颗粒内扩散模型)探究了NSC对TC的吸附特性.同时,通过扫描电子显微镜(SEM)、X射线衍射(XRD)、Brunauer-EmmettTeller(BET)比表面积及孔径分析、傅立叶红外光谱(FTIR)和X射线光电子能谱(XPS)等技术表征了NSC吸附TC前后结构形貌及性质的变化,结合吸附模型的拟合结果阐述了NSC对TC的吸附机理,并利用生命周期评价法估算了其制备成本.结果表明：(1)NSC的BET比表面积高达1688.14 m²·g^-1,含丰富的微孔结构、官能团和N、S掺杂的极性表面.(2)NSC对TC的等温...     

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.