碳纳米管负载TiO2对1,2,4-三氯苯的光降解研究

碳纳米管负载TiO2复合光催化剂与纳米TiO2光催化剂对1,2,4-三氯苯的光催化降解效果,及降解动力学的研究结果表明,复合光催化剂比纳米TiO2有更好的光催化降解效果,经254 nm紫外光辐照60 min后,使用复合光催化剂的1,2,4-三氯苯降解了70%,而使用纳米TiO2为催化剂的1,2,4-三氯苯仅降解了51%...     

V-M/TiO2(M=Cu、Cr、Ce、Mn、Mo)催化燃烧含氯有机废气

以TiO2为载体,采用浸渍法制备V-M/TiO2(M=Cu、Cr、Ce、Mn、Mo)双金属氧化物催化剂,考察其催化燃烧氯苯、二氯甲烷等含氯有机废气(CVOCs)的性能,并通过XRD、BET、H2-TPR和NH3-TPD对催化剂进行了表征.结果表明,V-Mo/TiO2催化剂比表面积最大,催化剂表面活性组分的高分散性和良好的酸性分布使得V-Mo/TiO2能够在260oC将氯苯完全转化为CO2和HCl.而V-Mn/TiO2则具有丰富的活性氧,可显著提高催化剂深度氧化二氯甲烷的能力,在380℃时二氯甲烷即可完全燃烧,并且反应对CO2有着很高的选择性.     

轻工业废物处理与综合利用

X791.03 200401121 纳米TiO2光催化降解直接耐晒蓝的研究/黄丽华(复旦大学环境科学与工程系)…∥环境化学/中科院生态环境研究中心.-2003,22(4).-359- 363 环图X-87 利用溶胶-凝胶法以钛酸四丁酯制备TiO2纳米粉末,考察不同温度焙烧的TiO2催化剂对直接耐晒蓝的光催化降解性能,并用XRD和TEM对催化剂进行了表征。结果表明,400-550℃焙烧的     

低温等离子体与催化剂联用降解空气中低浓度的苯

采用介质阻挡放电(DBD)与催化剂(MnO2,TiO2)联用降解空气中低浓度的苯(C6H6)。考察了苯的转化率、产物选择性、能量效率随能量密度的变化关系。研究发现,苯的转化率随能量密度的增加而增加,当注入DBD反应器的能量密度为1200J/L时,等离子体协同催化剂MnO2氧化苯的转化率达到了92%。苯的氧化产物为一氧化碳(CO)和二氧化碳(CO2),进而阐述了其氧化机理。当能量密度为430J/L时,在催化剂MnO2,TiO2存在的条件下,能量效率分别达到了0.062与0.043mol/kWh。     

石墨烯/二氧化钛降解亚甲基蓝的研究

以钛酸丁酯和氧化石墨烯为前驱物,通过水热法制备石墨烯/二氧化钛(GR/TiO2)复合光催化剂。采用XRD、TEM和FT-IR等技术手段对GR/TiO2粉体的结构和形貌进行了表征。利用对亚甲基蓝光催化降解,考察了GR/TiO2的光催化降解能力,并研究了H2O2用量和p H等因素对光催化降解速率的影响。结果表明:复合催化剂中,TiO2为锐钛型晶体,粒径为25 nm左右,分散在薄纱状的石墨烯上;复合催化剂通过紫外光下光催化性能有所提高,对可见光产生响应,具有良好的稳定性;加入适量H2O2能提高反应速率,碱性条件下,对亚甲基蓝的降解效率更高。     

SO42-改性TiO2催化降解茜素红水溶液

基于SO42-对TiO2超强酸化改性制备了SO42-/TiO2催化剂,以茜素红为目标物试验研究了该催化剂的催化降解性能,并考察了降解条件等因素对脱色率的影响.结果表明,SO42-/TiO2具有较强催化降解性能及一定的光催化活性,降解过程中SO42-流失是催化剂失活的主要原因.在pH=7,催化剂加入量为2.5g/L,起始浓度为140mg/L,太阳光等优化工艺条件下降解效果最好,脱色率达到92%.     

纳米TiO_2纤维的制备及其光催化降解甲醛研究

以胶原纤维为模板制备纳米TiO2纤维用于光助催化降解甲醛气体,用扫描电镜(SEM)、X射线衍射(XRD)和N2吸附-脱附技术对纳米TiO2纤维进行了表征。结果表明,纳米TiO2纤维的比表面积为11.33 m2/g,晶型为锐钛矿型。在相同催化反应条件下纳米TiO2纤维对甲醛气体的催化降解率与商品纳米TiO(2Degussa P25)催化剂相当。纳米TiO2纤维的用量、甲醛气体初始浓度是影响催化效果的两个因素。当甲醛气体初始浓度为0.270 mg/m3,相对湿度为38%,气体流速0.1 L/min,纳米TiO2纤维用量为1.0 g时,甲醛的降解率达到96%。因此,纳米TiO2纤维可用于室内甲醛气体的催化降解。     

氮掺杂型纳米TiO2在可见光及太阳光下的光催化性能研究

采用钛酸四丁酯为原料,以氨水水解-沉淀法制备出了氮掺杂型纳米TiO2催化剂(N/TiO2),以XRD、XPS、UV-Vis等手段对其进行表征;并通过对偶氮染料橙黄G的降解反应,研究了N/TiO2在可见光及太阳光下的光催化性能,探讨了pH值、外加H2O2氧化剂对光催化降解率的影响,并与P25型纳米TiO2进行了对比.结果表明,在可见光下,N/TiO2对橙黄G具有较高的催化活性,反应150min后降解率可达96.29%,显著高于P25型TiO2(42.55%);在太阳光下,N/TiO2对橙黄G的光催化降解速率较快,反应60min降解率与P25型TiO2基本相同,分别为99.37%、99.94%;较低的pH值环境并适量添加H2O2可显著提高N/TiO2催化效率,在可见光及太阳光下的最佳pH值均为2～3,最佳H2O2加入量分别为0.5mL·L-1、1.5 mL·L-1.     

银、钕掺杂TiO_2催化光解甲基橙的实验研究

实验用水热合成法制备出银、钕掺杂TiO2催化剂粉体,然后以高压汞灯为光源,掺杂TiO2催化剂粉体为光化降解催化剂,探究对甲基橙模拟印染废水光催化分解的效果。光解实验研究采用正交设计法,以模拟废水浓度、催化剂用量、光照时间以及pH为因素,各因素选取4个水平,对催化光解甲基橙染料的降解率进行评价。分析结果表明:银、钕掺杂TiO2催化剂对甲基橙光化降解有良好的效果,最佳实验条件为:溶液pH为5,甲基橙的初始质量浓度为2 mg/L,催化剂投加量60 mg/L和光照时间80 min。在最佳条件下,连续光照8 h后甲基橙的降解率达到92%以上。     

活性炭负载纳米TiO2对腐殖酸光催化降解动力学

采用溶胶-凝胶法制备了以颗粒活性炭(GAC)为载体的纳米TiO2/AC复合催化剂,并将其用于腐殖酸的光催化降解.动力学研究表明,TiO2/AC光催化降解腐殖酸过程可用Langmuir-Hinshelwood(L-H)动力学模式表示.L-H表观反应速率常数KLH=0.1124mg·L-·1min-1,吸附平衡常数K*=0.3402L·mg-1.活性炭负载TiO2对腐殖酸的光催化降解过程,体现了活性炭与TiO2的协同作用,活性炭的吸附作用提高了光催化反应速率.     

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

ＲｅｍｏｖａｌｏｆｈｅａｖｙｍｅｔａｌｓｆｒｏｍｓｅｗａｇｅｓｌｕｄｇｅｂｙｌｏｗｃｏｓｔｉｎｇｃｈｅｍｉｃａｌｍｅｔｈｏｄａｎｄｒｅｃｙｃｌｉｎｇｉｎａｇｒｉｃｕｌｔｕｒｅＷｕＱｉｔａｎｇ，ＮｙｉｒａｎｄｅｇｅＰａｓｃａｓｉｅ，ＭｏＣｅｈｕｉＦ...     

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.