阳离子聚合物改性膨润土对六价铬的吸附特性研究

采用阳离子聚合物聚环氧氯丙烷二甲铵（EPIDMA）和聚二甲基二烯丙基氯化铵（PDMDAAC）分别对钠基膨润土进行了改性,研究了改性膨润土吸附Cr(Ⅵ)的主要影响因素.结果表明,膨润土经阳离子聚合物改性处理后,吸附Cr(Ⅵ)的能力提高了5倍以上.改性膨润土所使用的阳离子聚合物量、阳离子聚合物/膨润土的投加量、溶液pH值、温度、振荡时间影响其对Cr(Ⅵ)的吸附行为.阳离子聚合物负载量分别为99.6 mg/g的EPIDMA/Bt和55.1 mg/g的PDMDAAC/Bt,在20℃、pH=4.0的溶液中,投加量为10 g/L反应120 min时,对Cr(Ⅵ)的吸附量分别为0.71 mg/g和0.56 mg/g.EPIDMA/Bt和PDMDAAC/Bt对Cr(Ⅵ)的吸附符合伪二级动力学方程和Langmuir等温吸附模式.     

改性麦麸生物吸附剂对废水中苯酚的吸附机理研究

将麦麸分别用氯化铵(NH4Cl)、十八烷基二甲基苄基氯化铵(SDMBA-Cl)、三乙基苄基氯化铵(TEBAC)进行改性,制得一系列改性麦麸吸附剂。经筛选,确定采用经SDMBA-Cl改性的麦麸作为吸附剂,探讨各种吸附条件对改性麦麸吸附苯酚的影响。当苯酚初始浓度为50 mg·L~(-1),pH=9.0,吸附剂投加量为30 g·L~(-1),吸附时间为240 min时,改性麦麸吸附剂对苯酚的去除率达76.8%,最大理论吸附量为30.12 mg·g~(-1)。吸附动力学研究表明,该吸附过程符合准二级动力学方程,属于化学吸附。改性麦麸对苯酚的吸附符合Langmuir和Freundlich等温吸附模型,R~2均大于0.99。     

有机膨润土吸附苯酚的性能及其在水处理中的应用初探

分别用氯化十六烷基吡啶（CPC）和溴化十六烷基三甲铵（CTMAB）改性膨润土,试验了制备有机膨润土的适宜条件及其对吸附苯酚性能的影响。上述两种有机膨润土吸附水中苯酚很快能达到平衡。pH值为3─9时,有机膨润土处理苯酚的效果基本一致;pH>11时,有较高的去除率。CPC－膨润土或CTMAB－膨润土对苯酚的饱和吸附容量分别为103.5mg/g和75.0mg/g。有机膨润土处理苯酚的效果比原土提高8倍以上。     

改性黄豆荚对含酚废水的吸附机理研究

将天然黄豆荚分别用氯化铵、三乙基苄基氯化铵(TEBAC)、十八烷基二甲基苄基氯化铵(SDMBA-Cl)进行改性,制备改性黄豆荚吸附剂。探讨了用SDMBA-Cl改性黄豆荚吸附处理苯酚废水的条件及机理。结果表明:当苯酚溶液初始浓度为100 mg·L~(-1),吸附剂投加量为30 g·L~(-1),pH为9.0,吸附时间为120 min时,该吸附剂对苯酚废水的去除率达到72.3%。此吸附过程符合准二级动力学方程,以化学吸附为主;Langmuir方程能较好的拟合等温吸附过程,为单分子吸附。     

苯酚、苯在水／阴离子有机膨润土界面的环境行为研究

研究了苯酚在水／阴离子有机膨润土界面的吸附行为，初步探讨了阴离子有机膨润土对苯酚、苯的吸附性能、机理及影响因素。结果表明，阴离子表面活性剂改性后，膨润土中有机碳含量增加了10～38倍，对苯酚、苯的吸附能力大大提高。水中苯酚、苯在水／阴离子有机膨润土界面的吸附行为主要分配作用所致，其吸附等温线呈线性。     

有机膨润土吸附对硝基苯酚的性能及其在水处理中的应用初探

分别用溴化十六烷基三甲铵（ＣＴＭＡＢ）和氯化十六烷基吡啶（ＣＰＣ）改性膨润土，研究了制备有机膨润土的适宜条件及其对吸附对对硝基苯酚性能的影响。２５℃时，ＣＴＭＢ－膨润土和ＣＰＣ－膨润土对对硝基苯酚的饱和吸附量分别为４７５ｍｇ／ｇ，远大于原土的饱和吸附量（１２５ｍｇ／ｇ）。ｐＨ〉７时，有机膨润土吸附处理对硝基苯酚的去除率都在８５％以上，比原土的去除率（８．６％）大９倍，通过Ｘ－衍射、红外光谱分析、比     

CTMAB/CPAM复合改性膨润土吸附水中苯酚和硝基苯

用十六烷基三甲基溴化铵(CTMAB)和阳离子型聚丙烯酰胺(CPAM)改性膨润土,制得系列CTMAB-膨润土(C-Bt)、CPAM-膨润土(P-Bt)和复合改性膨润土(C/P-Bt).采用XRD分析了各类有机膨润土的底面间距,并比较了它们吸附水中苯酚和硝基苯的性能.结果显示,C/P-Bt的底面间距大于相应的C-Bt和P-Bt,表明CTMAB与CPAM能同时层插到膨润土层间.C/P-Bt吸附性能优于C-Bt及C-Bt加P-Bt,在相同平衡浓度下(苯酚为7 045 mg/L,硝基苯为409 mg/L),60C/4%P-Bt对苯酚和硝基苯的吸附量分别为150 mg/g和69 mg/g,吸附量比60C-Bt分别提高了26%和28%,比60C-Bt加4%P-Bt分别提高了22%和26%,表现出明显协同吸附效应.这说明CTMAB在C/P-Bt层间的排列模式受CPAM的影响,形成了对有机物亲和能力更强的吸附介质.该新型有机膨润土在有机污染控制中有良好的应用前景.     

十六烷基三甲基季铵盐-乙硫醇铵盐复合改性膨润土吸附性能研究

用十六烷基三甲基季铵盐(HDTMA)和乙硫醇铵盐(AET)双阳离子同时复合改性内蒙钙基膨润土(NMB),制得新型吸附材料HDTMA-AET-NMB.利用X射线衍射(XRD)、热分析(TG-DTA)、红外光谱(FT-IR)及N2-BET等测定发现,复合改性膨润土的表面性质和层间结构已发生显著改变.对重金属离子Cd2+和对硝基苯酚(PNP)的吸附研究表明,HDTMA-AET-NMB能协同吸附混合水溶液中的目标污染物,对水中重金属离子的吸附机理是膨润土层间的AET与被吸附的Cd2+形成了稳定的配合物;对水中对硝基苯酚的吸附源于其在长碳链疏水介质中的分配.复合改性膨润土可望应用于重金属-有机物混合废水的处理.     

CPC在膨润土处理含p-硝基苯酚废水中的增强效应

选用氯代十六烷基吡啶(CPC)和p-硝基苯酚为目标化合物,试验比较了CPC 膨润土直接混合体系和CPC改性有机膨润土对含p-硝基苯酚废水的吸附效果.结果表明,与CPC改性土相比,用相应浓度的CPC 膨润土混合直接处理含p-硝基苯酚废水更为有效,可使p-硝基苯酚的去除率提高2倍以上(45%~98%),并可以节约处理成本且基本不增加表面活性剂二次污染.最经济适宜的CPC投加量与膨润土阳离子交换容量(CEC)相当.     

壳聚糖/CTAB复合改性膨润土对活性红X-3B的吸附

以壳聚糖和十六烷基三甲基溴化铵(CTAB)为改性剂,制备了复合改性膨润土,并利用傅里叶红外光谱仪(FTIR)和X射线衍射(XRD)对其进行表征,研究了该改性膨润土对活性红X-3B的吸附效果.结果表明:壳聚糖能插入CTAB改性膨润土层间;当复合改性膨润土投加量为5 g·L~(-1),pH为3时,其对活性红X-3B的去除率可达99.15%;吸附过程符合拟二级动力学方程;吸附行为适于用Langmuir吸附等温方程描述.由吸附热力学方程计算得到,吸附焓变ΔH0,吸附自由能变ΔG0,吸附熵变ΔS0,表明吸附为放热和熵减少的自发过程.复合改性膨润土稳定性受搅拌时间和温度的影响不明显,pH较低(pH3)时稳定性会降低.通过Zeta电位分析认为,静电作用为吸附的主要机理.经过6次吸附/再生后,改性膨润土对活性红X-3B的去除率仍在60%以上,表明复合改性膨润土具有较好的重复利用性.研究表明,该复合改性膨润土是一种对水体中活性红X-3B具有良好吸附能力的吸附剂.     

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.     

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 two sludge application on fractionation and phytotoxicity of zinc and copper in the soil

The potential harm of heavy metals is a primary concern in application of sludge to the agricultural land. A pot experiment was conducted to evaluate the effect of two sludges on fractionation of Zn and Cu in soil and their phytotoxicity to pakchoi. The loamy soil was mixed with 0%, 20%, 40%, 60% and 80% (by weight) of digested sewage sludge (SS) and composted sludge (SC). The additions of both sludges caused a significant raise in all fractions, resulting in that exchangeable (EXCH) and organic bound (OM) became predominance of Zn and organic bound Cu occupied the largest portion. There was more available amount of Zn and Cu in SS treatments than SC treatments. During the pot experiment, the concentration of Zn in EXCH, carbonate (CAR) and OM and Cu in EXCH and OM fractions decreased in all treatments, so their bioavailability reduced. Germination rate and plant biomass decreased when the addition rate was high and the best yield appeared in 20% mixtures at the harvest of pakchoi. The two sludges increased tissue contents of Zn and Cu especially in the SS treatments. Zn in pakchoi was not only in relationship to ΔEXCH and ΔCAR forms but also in ΔOM forms in the sludge-soil mixtures. Tissue content of Cu in pakchoi grown on SC-soils could not be predicted by ΔEXCH. These correlation rates between Zn and Cu accumulation in pakchoi and variation of different fractions increased with time, which might indicate that sludges represented stronger impacts on the plant in long-term land application.     

Intraspecific differences in effects of co-contamination of cadmium and

A hydroponic experiment was carried out to study intraspecific differences in the effects of different concentrations of cadmium (Cd)(0-10 mg/L) and arsenate (As(V)) (0-8 mg/L) on the growth parameters and accumulation of Cd and As in six wheat varieties Jing-9428, Duokang-1, Jingdong-11, Jing-411, Jingdong-8 and Zhongmai-8. The endpoints of wheat seedlings, including seed germination,biomass, root length and shoot height, decreased with increasing the Cd and As concentrations. Significant differences in seed germination, biomass, root length, shoot height and the accumulation of Cd and As were observed between the treatments and among the varieties (p ＜ 0.05). The lethal dosage 50% were about 20, 80, 60, 60, 80 and 20 mg As/L for Jing-9428, Duokang-1, Jingdong-11,Jing-411, Jingdong-8 and Zhongmai-8, respectively, and the corresponding values for Cd were about 30, 80, 20, 40, 60 and 10 mg Cd/L, respectively. Among the six varieties, Duokang-1 was found to be the most resistant to Cd and As toxicity, and Zhongmai-8 was the most sensitive to Cd and As co-contamination. The resistance of the six varieties was found dependant on the seedling uptake of Cd and As. Duokang-1 was the most suitable for cultivation in Cd and As co-contaminated soils.     

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

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Isolation and preliminary characterization of a 3-chlorobenzoate degrading bacteria

A study was conducted to compare the diversity of 2-, 3-, and 4-chlorobenzoate degraders in two pristine soils and one contaminated sewage sludge. These samples contained strikingly different populations of mono-chlorobenzoate degraders. Although fewer cultures were isolated in the uncontaminated soils than contaminated one, the ability of microbial populations to mineralize chlorobenzoate was widespread. The 3- and 4-chlorobenzoate degraders were more diverse than the 2-chlorobenzoate degraders. One of the strains isolated from the sewage sludge was obtained. Based on its phenotype, chemotaxonomic properties and 16S rRNA gene, the organism S-7 was classified as Rhodococcus erythropolis. The strain can grow at temperature from 4 to 37℃. It can utilize several （halo）aromatic compounds. Moreover, strain S-7 can grow and use 3-chlorobenzoate as sole carbon source in a temperatures range of 10-30℃ with stoichiometric release of chloride ions. The psychrotolerant ability was significant for bioremediation in low temperature regions. Catechol and chlorocatechol 1,2-dioxygenase activities were present in cell free extracts of the strain, but no （chloro）catechol 2,3- dioxygenase activities was detected. Spectral conversion assays with extracts from R. erythropolis S-7 showed accumulation of a compound with a similar UV spectrum as chloro-cis,cis-muconate from 3-chlorobenzoate. On the basis of these results, we proposed that S-7 degraded 3-chlorobenzoate through the modified ortho-cleave pathway.     

Single and joint effects of pesticides and mercury on soil urease

The influence of two pesticides including chlorimuron-ethyl and furadan and mercury （Hg） on urease activity in 4 soils （meadow burozem and phaeozem） was investigated. The soils were exposed to various concentrations of the two pesticides and Hg individually and simultaneously. Results showed that there was a close relationship between urease activity and organic matter content in soil. Chlorimuron-ethyl and furadan could both activate urease in the 4 soils. The maximum increment of urease activity by chlorimuronethyl was up to 14%-18%. There was almost an equal increase （up to 13%-21%） in the urease activity by furadan. On the contrary, Hg markedly inhibited soil urease activity. A logarithmic equation was used to describe the relationship （P〈0.05） between the concentration of Hg and the activity of soil urease in the 4 tested soils. Semi-effect dose （ED50） values by the stress of Hg based on the inhibition of soil urease in the 4 soils were 88, 5.5, 24 and 20 mg/kg, respectively, according to the calculation of the corresponding equations. The interactive effect of chlorimuron-ethyl or furadan with metal Hg on soil urease was mainly synergic at the highest tested concentrations.