几种酚衍生物对青海弧菌Q67毒性的3D-QSAR研究

测定了16种酚衍生物对青海弧菌(Q67)的半致死浓度EC50(mol·L-1),通过比较分子力场分析方法(CoMFA)和比较分子相似性指数分析方法(CoMSIA),对16种酚衍生物的毒性进行了三维定量结构-活性相关(3D-QSAR)研究,建立了CoMFA和CoMSIA模型.其中CoMFA模型交叉验证相关系数Q2=0.703,非交叉验证相关系数R2=0.983,F检验值F=178.635;CoMSIA模型交叉验证相关系数Q2=0.588,非交叉验证相关系数R2=0.946,F检验值F=52.074,所建立的模型均有较强的稳定性和良好的预测能力.通过分析比较CoMFA和CoMSIA的三维等势图,全面直观地了解了酚衍生物的结构对致毒性的影响.在酚类化合物毒性作用过程中,化合物的氢键供受体特性因素起主要作用,其次是取代基的电负性和疏水性特征.     

羧酸类药用活性化合物在生物碳质上的吸附特性

为研究生物碳质吸附在处理水土环境中羧酸类PhACs（药用活性化合物）的作用,通过比表面积、红外光谱、元素分析及电镜扫描对商业水稻秸秆生物碳质的结构与性质进行了讨论,同时研究了生物碳质对不同初始pH及不同初始质量浓度的五种羧酸类PhACs[KTP（酮洛芬）、IBP（布洛芬）、NPX（萘普生）、ASP（阿司匹林）、SYA（水杨酸）]吸附特征的影响.结果表明:吸附过程包括前期快速吸附和后期缓慢吸附至平衡两个阶段;在第一阶段,外表面吸附与大孔及中孔扩散是控制吸附的机制,在第二阶段,生物碳质内表面吸附及基质在微孔中的扩散是影响吸附的主要机制.初始pH为6.0~7.0时,等温吸附数据符合Freundlich吸附等温方程,反映了非均匀性表面的吸附特性.五种羧酸类PhACs在生物碳质上的吸附能力[通过K_d,0.01（特定液相浓度下的单点分配系数）表达]表现为NPX（24.30 g/L）> IBP（15.82 g/L）> KTP（10.44 g/L）> SYA（2.64 g/L）> ASP（1.24 g/L）.溶液初始pH变化对所选PhACs的吸附量有显著影响,初始溶液pH处于pKa±1.0范围内时,所选吸附质的吸附量达到最大值,随着初始pH的升高,所选PhACs主要以阴离子形式存在,同时生物碳质表面负电性增加,增强的静电斥力减弱了氢键作用.研究显示,氢键作用在生物碳质吸附PhACs过程中起到主要促进作用,除此之外,还受到范德华力及π-π电子供受体等多种作用驱动.      

芳香族化合物在XAD-4上吸附机理的研究

通过批量吸附实验考查了7种芳香族化合物在XAD-4上的吸附热力学行为.结果表明,在实验条件下,Freundlich方程能很好地拟合这7种化合物在XAD-4上的等温吸附数据,且都为优惠吸附,吸附能力均随着温度的升高而降低.结合7种化合物的分子结构描述符和Freundlich方程的吸附平衡常数,建立了QSPR模型,较高的可决系数R2(0.991)、去一法交互检验可决系数R2CV(0.985)和外部预测集交互检验系数Q2ext(0.994)表明,该模型具有较高的稳定性能和预测能力.模型结果表明,水杨酸等7种芳香族化合物在XAD-4上的Freundlich吸附平衡常数与溶质疏水性能呈正比关系,与温度、溶质分子极性和溶质分子的氢键酸度常数呈反比关系.     

小麦秸秆生物碳质吸附剂从水中吸附硝基苯的机理

在炭化温度为300℃下,以小麦秸秆为材料制备生物碳质吸附剂,采用批量平衡试验,研究了其对水中硝基苯的吸附特性,并从动力学及热力学角度探讨其吸附硝基苯的作用机理.结果表明,硝基苯在生物碳质上的吸附过程符合拉格朗日假二级动力学方程,反应活化能为12.2 kJ/mol;吸附行为可用Freundlich吸附等温方程描述,饱和吸附容量为91.58 mg/g.由吸附热力学方程计算得到的等量吸附焓变(ΔH)<0,吸附自由能变(ΔG)<0,吸附熵变(ΔS)>0,表明生物碳质对硝基苯的吸附为放热和熵减少的自发过程.      

酸碱改性生物炭对水中磺胺噻唑的吸附性能研究

以马铃薯茎叶为原料,采用限氧裂解法制备生物炭,通过H2SO4和KOH处理制备酸、碱改性生物炭.应用比表面积法(BET)、扫描电镜(SEM)和红外光谱(FTIR)研究了改性前后3种生物炭的结构与性质,并通过单因素实验研究了吸附时间、温度、磺胺噻唑初始浓度、p H值等因素对原始及酸碱改性3种生物炭吸附磺胺噻唑效果的影响,初步探讨了吸附机制.结果表明,3种生物炭对磺胺噻唑的吸附行为符合准二级动力学方程;酸改性生物炭对磺胺噻唑的吸附等温线符合Temkin模型,原炭和碱改性生物炭的吸附等温曲线符合Freundlich模型.酸改性极大的提高了生物炭对磺胺噻唑的吸附能力,最大吸附量为7.69 mg·g-1,是原炭吸附量的2.4倍;溶液p H对3种生物炭吸附磺胺噻唑影响不明显.热力学研究表明,酸改性生物炭对磺胺噻唑的吸附为自发的吸热反应.FTIR分析表明,酸改性生物炭表面有更多含氧官能团,为磺胺噻唑的吸附提供了吸附点.氢键、范德华力及偶极距力作用对生物炭吸附磺胺噻唑起到主要作用.     

玉米秸秆生物炭对灰钙土吸附金霉素的影响

为研究生物炭(BC)添加对灰钙土(HGT)吸附金霉素(CTC)的影响,本文以玉米秸秆为原料分别在200、400和600℃下制备BC.采用批平衡法,研究CTC在HGT和HGT+BC上的吸附行为.结果表明,HGT对CTC的吸附平衡时间为240 min,添加BC使平衡时间相对延长,符合准二级动力学模型.CTC的总体吸附速率由表面扩散和颗粒内扩散共同控制,且表面扩散速率更快,疏水分配作用促进吸附进行.3种等温吸附模型拟合对CTC在HGT和HGT+BC中的吸附均呈现较好相关性.添加BC使HGT对CTC的吸附分配系数Kd值增大,亲和力增强.不同温度时分配系数Kd的差异性表明吸附过程为放热反应.吸附满足不同等温线型(L型和S型),是以化学吸附为主的非均质复杂吸附过程,伴随静电引力、氢键相互作用等表面吸附和物理吸附.pH=3时,CTC+与土壤表面的负性位点大量结合,发生阳离子交换与静电吸引作用,吸附量最大.pH增大,CTC存在形态改变,HGT和BC对其吸附能力减弱.BC在不同pH下始终增强HGT对CTC的吸附,且添加量越大,CTC的吸附分配系数Kd值越大.吸附是由HGT和BC的有机质含量、矿物组成、理化性质及CTC存在形态和环境因素共同作用的结果.研究表明适量添加BC对HGT吸附CTC具有积极影响,裂解温度200℃时作用最显著,可以有效促进HGT对CTC的吸附与固定作用.     

分配作用对沉积物吸附对硝基苯酚的贡献

研究了杭州东苕溪、西湖、运河(杭州段)和嘉兴南湖4个不同水体的18个沉积物对对硝基苯酚的吸附作用及机理.结果表明,分配作用在沉积物吸附对硝基苯酚的过程中占主导地位,其等温吸附曲线呈线性,吸附系数K与有机碳含量f_oc呈显著正相关(r=0.983).同一来源的沉积物,有机碳标化的分配系数Koc大致为常数.阳离子交换容量CEC对沉积物吸附对硝基苯酚几乎没有影响.     

水稻秸秆生物碳对重金属Pb2+的吸附作用及影响因素

以农业废弃物水稻秸秆为原料,采用限氧裂解法制备了不同温度(350、500和700℃)下的秸秆生物碳(RC350、RC500和RC700),研究了生物碳对Pb2+的吸附性能、作用机制及影响因素,为准确预测生物碳还田固碳对土壤中重金属迁移行为的影响提供理论参考.结果表明,生物碳对Pb2+的吸附行为符合准一级动力学方程,Pb2+在RC350、RC500、RC700上的吸附速率分别为0.167h-1、0.154h-1、0.388h-1;其等温吸附曲线符合Langmuir方程,最大吸附量分别为65.3、85.7和76.3mg·g-1,是原秸秆生物质RC100的5～6倍、活性炭AC的2～3倍.生物碳单位面积上的有效吸附点位比AC高约10倍.经酸化去除表面矿物成分后,RC350和RC700对Pb2+的吸附能力急剧下降,其最大吸附量、吸附亲和力与AC相近;红外光谱分析表明,去灰分后生物碳上有机碳官能团并无明显减少,而无机矿物(如SiO2)含量显著降低.生物碳中的有机碳组分和无机矿物组分对其吸附Pb2+均有重要贡献,其中无机矿物组分的吸附量及亲和力均大于有机碳组分.     

水稻秸秆生物碳的结构特征及其对有机污染物的吸附性能

以水稻秸秆为原料,采用限氧裂解法制备了不同温度(100 ～ 700℃)的秸秆生物碳,用TG-DTG热重分析、CHNO元素分析、FTIR、BET-N2比表面及孔径分布等手段表征生物碳的组成与结构,研究生物碳吸附水中硝基苯、对硝基甲苯、萘、菲等有机污染物的性能及影响因素,探讨其作用机制及构-效关系,试图为高效利用废弃农业秸秆资源、制备廉价的有机物吸附材料提供理论依据.结果表明,水稻秸秆生物碳含有丰富的有机碳组分和无机矿物组分,随着裂解温度升高,生物碳中有机组分的含碳量逐渐升高、极性减弱、芳香性增强,而无机矿物组分的相对含量则不断增加;当裂解温度从300℃升至400℃时,比表面积突然增大(0.16→110 m2·g-1)、微孔结构被打开,主要由于水稻秸秆中纤维素组分大量分解所致.水稻秸秆生物碳吸附有机污染物的主要介质为有机组分,等温吸附曲线符合Freundlich方程,回归参数N、logKf与生物碳的芳香性指数(H/C原子比)呈良好的线性关系;定量描述了分配作用和表面吸附作用的相对贡献.随碳化温度升高,等温吸附曲线由线性变为非线性,吸附机制从分配作用→分配作用+表面吸附作用→表面吸附作用;分配作用部分与有机污染物的logKow呈正相关,而表面吸附则与污染物的疏水性、分子尺寸及其与生物碳的极性匹配性有关.     

垃圾防渗粘性土对多环芳烃菲(PHEs)的吸附作用研究

研究了持久性有机污染物多环芳烃菲(PHEs)在垃圾防渗粘性土中的吸附机理规律及其吸附模型,探讨了pH值及土样颗粒等影响因素对吸附效果的作用机制,提出了垃圾填埋场防渗粘性土的优化设计。结果表明:菲在粘性土中的吸附过程包括4个阶段,达到吸附平衡的时间为9h;吸附等温线符合Freundlich模型,相关系数为0.98,属于非线性等温吸附;菲的水-土分配系数Kd为0.01,有机碳和水之间的分配系数为14.29;当pH值7.42时,土样对菲的吸附量随pH值的增大而迅速增大;pH值7.42的酸性环境中,对菲的吸附量也变大,但是随着酸性的加强,当pH值6.74之后,吸附能力不再有明显变化;菲的最大吸附量与土体的粘粒含量、比表面积呈正比,由大到小顺序为粘性土粉质粘土细砂。     

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.     

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.     

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.     

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.     

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.     

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 cadmium using MnO2 loaded D301 resin

MnO2 loaded weak basic anion exchange resin D301 （Anion exchange resin, macroreticular weak basic styrene） as adsorbent has been prepared and applied to the removal of cadmium. The adsorption characteristics have been investigated with respect to effect of pH, equilibrium isotherms, removal kinetic data, and interference of the coexisting ions. The results indicated that the Cd^2＋ could be efficiently removed using MnO2 loaded D301 resin in the pH range of 3-8 from aqueous solutions with the co-existence of high concentration of alkali and alkaline-earth metals ions. The saturate adsorption capacity of the Cd^2＋ was 77.88 mg/g. The adsorption process followed the pseudo first-order kinetics. The equilibrium data obtained in this study accorded excellently with the Langmuir adsorption isotherm.     

Evaluation of phytoextracting cadmium and lead by sunflower, ricinus, alfalfa and mustard in hydroponic culture

Soil contaminated with heavy metals cadmium(Cd)and lead(Pb)is hard to be remediated.Phytoremediation may be a feasible method to remove toxic metals from soil,but there are few suitable plants which can hyperaccumulate metals.In this study,Cd and Pb accumulation by four plants including sunflower(Helianthus annuus L.),mustard(Brassica juncea L.),alfalfa(Medicago sativa L.), ricinus(Ricinus communis L.)in hydroponic cultures was compared.Results showed that these plants could phytocxtract heavy metals, the ability of accumulation differed with species,concentrations and categories of heavy metals.Values of BCF(bioconcentration factor)and TF(translocation factor)indicated that four species had dissimilar abilities of phytoextraction and transportation of heavy metals.Changes on the biomass of plants,pH and Eh at different treatments revealed that these four plants had distinct responses to Cd and Pb in cultures.Measurements should be taken to improve the phytoremediation of sites contaminated with heavy metals,such as pH and Eh regulations,and so forth.     

Effect of coagulation pretreatment on the fouling of ultrafiltration membrane

The purpose of this study is to understand the effect and mechanism of preventing membrane fouling, by coagulation pretreatment, in terms of fractional component and molecular weight of natural organic matter （NOM）. A relatively higher molecular weight （MW） of hydrophobic compounds was responsible for a rapid decline in the ultrafiltration flux. Coagulation could effectively remove the hydrophobic organics, resulting in the increase of flux. It was found that a lower MW of neutral hydrophilic compounds, which could remove inadequately by coagulation, was responsible for the slow declining flux. The fluxes in the filtration of coagulated water and supernatant water were compared and the results showed that a lower MW of neutral hydrophilic compounds remained in the supernatant water after coagulation could be rejected by a membrane, resulting in fouling. It was also found that the coagulated flocs could absorb neutral hydrophilic compounds effectively. Therefore, with the coagulated flocs formed on the membrane surface, the flux decline could be improved.     

Penetration analysis of elements and bioleaching treatment of spent refractory for recycling

Acidithiobacillus ferrooxidans ATCC23270 and Acidithiobacillus thiooxidans TM-32 were used for bioleaching of spent refractories of aluminium and copper melting furnaces for their recycling.Firstly,penetration of elements into aluminium melting furnace refractory was investigated and it was found that up to 7 cm from surface was contaminated.Comparison on leaching efficiency by the strains ATCC23270 and TM-32 found that the strain ATCC23270 could treat larger amount of the refractories than the strain TM-32 could do.In the experiment of bioleaching of spent refractory aluminium melting furnace by the strain ATCC23270,high leaching efficiency were obtained on Al,Si,and Ca,and extremely low leaching performance was,however,shown on the rest of elements i.e.,Na,Mn,and Zn.Under the strain TM-32 use,relatively high leaching performance was recognized on Al,Si,Ca,Na,Mn,and Zn.In the experiment of bioleaching for spent refractory copper melting furnace,almost the same leaching trends were shown on Cu,Zn,Al,and Si under the strains ACTT23270 and TM-32 uses.