表面活性剂强化超声波-离子液体预处理对水葫芦酶解的影响

为探讨表面活性剂对超声波-离子液体(US-IL)预处理木质纤维素的影响,本试验采用十二烷基硫酸钠(SDS)强化US-IL对水葫芦进行预处理,通过酶解、组成成分、表面形貌、结晶度以及化学结构的变化对预处理效果进行考察.结果显示,与未添加SDS相比,超声波-离子液体-十二烷基硫酸钠(US-IL-SDS)预处理能够有效降低纤维素的结晶度并去除木质素,酶解还原糖产量、纤维转化率及其脱木率分别提高72.23%、58.74%及21.01%.并且,SEM、XRD以及FTIR结果也表明SDS能够促进US-IL对水葫芦结构的破坏.因此,将SDS运用于辅助US-IL预处理木质纤维素具有一定可行性和良好的运用前景.     

表面活性剂辅助离子液体预处理稻秆的酶解动力学与结构变化分析

以稻秆为原料进行酶解研究,考察了纤维素酶和β-葡萄糖苷酶单独作用及协同作用对稻秆酶解还原糖产量的影响,以确定最佳酶体系,并研究在最佳酶体系中不同种类表面活性剂辅助离子液体对稻秆酶解的影响和动力学特征,最后通过稻秆成分分析、FTIR、XRD、SEM对预处理前后的稻秆结构、结晶性进行了分析比较.结果表明,纤维素酶与β-葡萄糖苷酶具有协同作用,而且在最佳酶体系中,与未处理稻秆及单独离子液体预处理相比,不同种类表面活性剂辅助离子液体预处理的稻秆在酶水解48 h时纤维转化率分别增加40%~85%、10%~31%,并且预处理对反应速率的提高有促进作用.     

不同种类表面活性剂联合离子液体预处理稻秆的物化特性研究

预处理是提高木质纤维材料酶解效果的关键步骤,更是木质纤维材料制造生物乙醇的重要环节.因此,对木质纤维材料进行预处理以促进酶解糖化过程具有重要意义.本研究以稻秆为原料,探讨不同类型表面活性剂(包括阳离子型、阴离子型、非离子型、生物)联合离子液体对木质纤维材料转化率及酶解初速度的影响,并通过稻秆成分分析、FTIR、XRD对处理前后稻秆的结构、结晶性进行了分析比较.结果表明,与单独离子液体处理相比,表面活性剂联合离子液体预处理稻秆可提升纤维转化率,效果为:生物表面活性剂-离子液体非离子型表面活性剂-离子液体阴离子型表面活性剂-离子液体阳离子型表面活性剂-离子液体.与未处理及单独离子液体处理稻秆相比,生物表面活性剂-离子液体预处理稻秆的纤维转化率分别提高55.38%和22.03%.     

超声辅助氨解预处理对纤维素酶酶解餐厨垃圾的影响研究

为了提高餐厨垃圾酶解产糖能力,从而能得到更多的燃料乙醇,就纤维素预处理对餐厨垃圾酶解产糖能力的影响进行了试验研究,考察了餐厨垃圾氨解、超声预处理对酶解产糖的影响规律。结果表明：在纤维素酶加酶量为12 g/100g实验垃圾样品、pH4.8、酶解糖化温度为42℃～58℃、反应时间为60 min的条件下,餐厨垃圾经过氨水-超声（10%氨水,固液比1∶20,超声30min）预处理的酶解产糖率比没进行预处理的产糖率有较大提高。     

园林生物质中离子液体-复合菌剂共降解体系的筛选与构建

园林生物质的绿色高效降解是实现生态系统物质循环的重要环节,离子液体-生物酶作为环境友好型降解体系备受关注.通过合成1-丁基-3-甲基咪唑（[Bmim]）和1-乙基-3-甲基咪唑（[Emim]）型离子液体衍生物,比较了温和条件下各离子液体对园林生物质的溶解再生性.结合复合微生物菌剂开展酶解试验,通过考察酶解率、纤维素酶活力、降解失重率和木质素含量变化等,筛选并构建最优降解体系组合.结果表明,两种离子液体的盐取代物对园林生物质有着较好的溶解再生性,当质量分数为70%~80%时,[Emim]型离子液体-复合菌剂体系的酶解率和酶活力最高.在降解末期,[Emim]Ac_75%和[Emim]FeCl_4·75%体系的降解失重率分别为46.9%和52.6%,均为阳性对照组的1.6倍,同时木质素含量分别减少41.7%和47.2%.[Emim]FeCl_4·75%-复合菌剂体系对园林生物质有着更为显著的降解效应.     

不同氧化剂辅助光催化反应对提高木质纤维素酶解效果的影响

木质纤维素以其可再生、丰富等优点成为可替代能源的理想选择,然而木质纤维素的致密结构使得后续的酶解过程极其困难,因此木质纤维素的预处理显得尤为重要.为了探讨氧化剂对光催化反应预处理木质纤维素的影响,在TiO₂/UV体系中添加不同种类的氧化剂对稻秆进行预处理,考察TiO₂/UV体系中影响光催化的因素〔ρ（TiO₂）、溶液pH及光催化时间〕,并进一步探讨在TiO₂/UV体系中添加O₃、SPC（过碳酸钠）、K₂S₂O₈及KIO₄等氧化剂对稻秆酶解效果的影响.结果表明:在TiO₂/UV体系中,当光催化时间为3 h、ρ（TiO₂）为10 g/L、pH为8时,稻秆的酶解效果最佳（310.17 mg/g）.TiO₂/UV/O₃光催化体系对稻秆的预处理效果强于TiO₂/UV/氧化剂体系,TiO₂/UV/O₃体系预处理稻秆酶解后产生的w（还原糖）最高,达到356.40 mg/g.TiO₂/UV/O₃体系预处理稻秆成分分析显示,木质素去除率为15.52%.FE-SEM（场发射扫描电镜）、FT-IR（红外光谱）及PXRD（X-射线粉末衍射）等表征分析结果表明,TiO₂/UV/O₃体系预处理能够对稻秆结构进行破坏.研究显示,TiO₂/UV/O₃光催化体系对稻秆进行预处理能够有效提高酶解效率.      

玉米芯经酸-超声波强化碱耦合预处理制取燃料乙醇

为研究酸碱耦合和超声波对玉米芯预处理效果的影响,通过成分分析、GC-MS分析、还原糖测定、X射线衍射和Jade软件的计算比较预处理后玉米芯的组成形态、结晶结构特点和酶解得率变化,以获得最佳的预处理条件. 结果表明:酸处理后的滤渣继续进行碱处理时,w(半纤维素)和w(木质素)均可降至14%左右;若在碱处理的同时进行超声波强化,当超声波功率为120 W,作用时间为5 min时,w(木质素)可进一步降至7.86%,酶解得率从34.09%升至37.32%,玉米芯的结晶度从59.79%降至57.46%. 以玉米芯为原料制取燃料乙醇的最佳预处理方式为“酸-超声波强化碱”耦合预处理.      

离子液体[bmim]BF_4掺杂纳米二氧化钛的制备及其光催化性能的研究

采用以离子液体为模板剂,辅助溶胶-凝胶法制备纳米级锐钛矿型二氧化钛。探索了合成N-甲基咪唑的实现条件,用微波法实现离子液体中间体及离子液体[bmim]BF4的合成,以合成的离子液体[bmim]BF4为模板制备纳米级光催化剂二氧化钛,研究该二氧化钛的光催化性能。在离子液体辅助下以溶胶-凝胶法制备的二氧化钛粒径更小,有更好的吸附性能和降解性能,光催化效果更好。     

氢氧化钠和碱性双氧水预处理对水稻秸秆酶解效果的影响

为提高水稻秸秆生物转化产糖效率,分别用氢氧化钠和碱性双氧水对其进行预处理,并考察处理液浓度、温度和时间对木质纤维素酶解糖化效果的影响. 通过分析预处理前后水稻秸秆组分和结构变化,揭示氢氧化钠预处理和碱性双氧水预处理对水稻秸秆酶解效果的影响机理. 结果表明:①在80 ℃的条件下,使用1.25%的氢氧化钠对水稻秸秆水浴处理3 h后效果较好,且酶解72 h后还原糖含量为480.81 mg/g. ②在50 ℃的条件下,使用碱性双氧水(1.5%的氢氧化钠+2%的双氧水)对水稻秸秆水浴处理5 h后效果较好,且酶解72 h后还原糖含量为575.85 mg/g. ③与未预处理的水稻糖化效果(132.7 mg/g)相比,经氢氧化钠预处理和碱性双氧水预处理后,水稻秸秆酶解产糖率分别提高了262.3%和336.2%. ④扫描电镜显示,经氢氧化钠和碱性双氧水预处理后,水稻秸秆的比表面积均显著增加,表面结构更加疏松. ⑤红外光谱和X射线衍射光谱表征显示,氢氧化钠预处理和碱性双氧水预处理均可消解水稻秸秆中的木质素并使其转化成纤维素,从而可以促进后续的酶解糖化效果. 研究显示,氢氧化钠预处理和碱性双氧水预处理都能较好地促进水稻秸秆的酶解糖化过程,得到较高的糖含量.      

咪唑类离子液体的二氧化硫吸附性能

为研究咪唑类离子液体脱除烟道气中SO2的规律,以1-丁基,3-甲基氯代咪唑([Bmim]Cl)、1-丁基,3-甲基硝酸咪唑([Bmim]NO3)、1-丁基,3-甲基氟硼酸咪唑([Bmim]BF4)和1-戊基,3-甲基氯代咪唑([C5mim]Cl)4种离子液体作为SO2吸附剂,研究了不同条件下4种离子液体对模拟烟道气中SO2的吸附性能,并初步进行了离子液体再生脱硫试验.利用傅立叶变换红外光谱(FTIR)对吸附前、后和再生后的[Bmim]Cl结构变化进行了研究.结果表明,4种离子液体对SO2均有吸附能力,且吸附能力为:[C5mim]Cl[Bmim]Cl[Bmim]NO3[Bmim]BF4,其中[C5mim]Cl的累积脱硫量达到200.8mg/g,[Bmim]Cl的最佳脱硫温度为40.0℃;3种阴离子对脱硫性能的影响顺序为:Cl-NO3-BF4-.在温度为90.0℃、压强为0.09MPa、再生4.0h后,[Bmim]Cl的硫容从再生前的65.9mg/g下降到26.5mg/g.脱硫过程中离子液体的结构发生了变化,它对SO2分子同时存在物理吸附和化学吸附.     

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.     

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.     

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.     

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.     

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.     

Organochlorine pesticides in soils under different land usage in the Taihu Lake region, China

A field study was conducted in the Taihu Lake region, China in 2004 to reveal the organochlorine pesticide concentrations in soils after the ban of these substances in the year 1983. Thirteen organochlorine pesticides (OCPs) were analyzed in soils from paddy field, tree land and fallow land. Total organochlorine pesticide residues were higher in agricultural soils than in uncultivated fallow land soils. Among all the pesticides, ΣDDX (DDD, DDE and DDT) had the highest concentration for all the soil samples, ranging from 3.10 ng/g to 166.55 ng/g with a mean value of 57.04 ng/g and followed by ΣHCH, ranging from 0.73 ng/g to 60.97 ng/g with a mean value of 24.06 ng/g. Dieldrin, endrin, HCB and α-endosulfan were also found in soils with less than 15 ng/g. Ratios of p,p'-(DDD DDE)/DDT in soils under three land usages were: paddy field ＞ tree land ＞ fallow land, indicating that land usage inlfuenced the degradation of DDT in soils. Ratios of p,p'-(DDD DDE)/DDT ＞1, showing aged residues of DDTs in soils of the Taihu Lake region. The results were discussed with data from a former study that showed very low actual concentrations of HCH and DDT in soils in the Taihu Lake region, but according to the chemical half-lives and their concentrations in soils in 1980s, the concentration of DDT in soils seemed to be underestimated. In any case our data show that the ban on the use of HCH and DDT resulted in a tremendous reduction of these pesticide residues in soils, but there are still high amounts of pesticide residues in soils, which need more remediation processes.     

Alterations of organ histopathology and metallolhionein mRNA expression in silver barb, Puntius gonionotus during subchronic cadmium exposure

Common silver barb,Puntius gonionotus,exposed to the nominal concentration of 0.06 mg/L Cd for 60 d,were assessed for histopathological alterations(gills,liver and kidney),metal accumulation,and metallothionein(MT)mRNA expression.Fish exhibited pathological symptoms such as hypertrophy and hyperplasia of primary and secondary gill lamellae,vacuolization in hepatocytes,and prominent tubular and glomerular damage in the kidney.In addition,kidney accumulated the highest content of cadmium,more than gills and liver.Expression of MT mRNA was increased in both liver and kidney of treated fish.Hepatic MT levels remained high after fish were removed to Cd-free water.In contrast,MT expression in kidney was peaked after 28 d of treatment and drastically dropped when fish were removed to Cd-free water.The high concentrations of Cd in hepatic tissues indicated an accumulation site or permanent damage on this tissue.