添加生物炭对西北黄土吸附克百威的影响

研究了不同温度下制得的生物炭对西北黄土吸附农药克百威的影响,并对溶液p H值和初始浓度对吸附的影响进行了探讨.结果表明,克百威在添加生物炭黄土上的动力学吸附过程较好地符合准二级吸附动力学模型;热力学吸附较好地符合Freundlich等温吸附模型;随着系统温度的升高,添加生物炭的黄土对克百威的吸附量增大,且其对克百威的吸附自由能变(ΔGθ)小于0,吸附焓变(ΔHθ)及吸附熵变(ΔSθ)均大于0,表明吸附是一个自发吸热且体系混乱程度增大的等温吸附过程.溶液p H值和克百威的初始浓度对添加生物炭的土样吸附影响较明显.当p H值为4~7时,添加生物炭的土样饱和吸附量随p H升高呈缓慢降低,当p H值大于7时,吸附容量随p H升高呈明显降低趋势.克百威初始浓度从20 mg·L-1增至50 mg·L-1的过程中,吸附量快速上升,初始浓度大于50 mg·L-1时,吸附量随初始浓度的升高而缓慢增加并逐渐趋于平衡.     

改性活性炭纤维对废水中2,4-D的吸附性能研究

以改性活性炭纤维作为吸附剂,研究了改性活性炭纤维(activated carbon fiber,ACF)在不同初始浓度、p H、温度、吸附剂投加量、吸附平衡时间条件下对2,4-D的吸附特性。结果表明,HNO3改性活性炭纤维吸附能力较好;改性ACF的吸附平衡时间为90 min;2,4-D初始溶液最佳p H值为2.0;改性ACF的吸附速率随温度的升高而增加,升高温度有利于吸附进行。改性ACF对2,4-D的吸附符合Langmuir吸附模型;吸附动力学符合拟二级模型;热力学计算结果显示ΔG0、ΔH0、ΔS0,吸附是自发、吸热、熵增加的物理过程;吸附过程中主要有范德华力、氢键力、电子供体/受体和静电力作用。实验表明,改性活性炭纤维对废水中2,4-D的去除具有实际应用的潜力。     

臭氧氧化降解水中三氯乙烯的效能研究

卤代烃是地下水污染中常见的有机污染物,三氯乙烯(Trichloroethylene,TCE)作为一种典型的卤代烃,具有高检出率、易挥发、致癌性等特征,而对地下水中TCE的治理一直是研究的热点.因此,本文以TCE为目标污染物,采用臭氧氧化技术对其进行降解效能分析,重点考察了不同臭氧投加量、初始p H、温度、初始TCE浓度对臭氧氧化降解水中TCE的影响,并对反应产物及可能的臭氧氧化机理进行了推测.结果表明,溶液的初始p H、臭氧投加量、初始TCE浓度均会对TCE的降解效率和降解速率产生一定的影响.在优化的实验条件下(p H=9、臭氧投加量5mg·L~(-1)、TCE初始浓度1 mg·L~(-1)、温度30℃),TCE在2 h的降解率可以达到100%,反应结束后TCE脱氯率为71.1%.动力学实验表明,臭氧氧化TCE的反应符合伪一级动力学.热力学研究表明,臭氧氧化TCE的焓变(ΔH)为15.53 k J·mol~(-1),熵变(ΔS)为-226.5 J·mol~(-1)·K~(-1),活化能E_a为18.05 k J·mol~(-1),表明臭氧氧化TCE的反应易于进行.机理研究表明,臭氧氧化降解TCE主要是由臭氧分解所形成的羟基自由基进行的.     

TiO2@酵母菌复合催化剂对刚果红的吸附特性研究

研究了TiO2@酵母复合型催化剂对阴离子染料刚果红的吸附性能,考察了pH、催化剂投加量、刚果红初始浓度、温度等因素对吸附效率的影响,并对吸附过程进行了动力学、等温模型和热力学分析.结果表明pH对吸附效率影响较大,最佳pH值为3;当刚果红浓度在10~50mg·L-1时,吸附量随着浓度的增加而增加;催化剂投加量为0.5 g·L-1,吸附效率较高;温度对吸附过程影响较小.TiO2@酵母复合催化剂吸附刚果红的过程符合准二级动力学模型;化学吸附为主要控制步骤;吸附过程符合Langmuir等温吸附方程,为单分子层吸附;ΔG为负值且ΔH为正值表明吸附是自发吸热过程.     

磁性石墨烯吸附水中Cr(Ⅵ)研究

以氧化石墨和铁盐为原料,采用化学沉淀法制备出磁性石墨烯复合材料,运用静态吸附实验研究了吸附动力学、热力学、等温吸附模型以及不同因素如p H、温度、时间对Cr(Ⅵ)吸附的影响.结果表明,吸附动力学符合假二级动力学模型;与Freundlich模型相比,Langmuir模型更适合描述吸附过程.热力学参数为:ΔHθ=33.89 k J·mol-1,ΔSθ=120.15 J·(mol·K)-1,ΔGθ=-2.51 k J·mol-1(303 K),这表明吸附过程是吸热并且自发的.实验最佳p H值为2,升高温度和延长时间均有利于吸附的进行.初始Cr(Ⅵ)浓度为5 mg·L-1时,重复利用3次后吸附量由3.9 mg·g-1下降到2.1 mg·g-1.在磁铁存在的条件下吸附剂可轻易从溶液中分离出来,利用Na OH可使其再生,因此可作为去除Cr(Ⅵ)的良好吸附剂.     

沸石分子筛对水中2,4-二甲基苯酚的吸附特性研究

以沸石分子筛为吸附剂,采用批次试验,研究静态吸附对水中2,4-二甲基苯酚(2,4-DMP)的吸附去除效果,比较了3种不同类型的沸石分子筛对2,4-DMP的吸附性能,选择其中吸附性能最好的沸石分子筛FAU-Y为吸附剂,分别考察了溶液初始p H、吸附剂投加量对吸附效果的影响,并对吸附动力学和吸附等温线进行了分析。结果表明,FAU-Y对2,4-DMP具有较大的吸附量,在2,4-DMP初始浓度为250 mgL,溶液初始p H为5.2,吸附剂投加量为5.0 gL时,室温条件下反应24h可以达到吸附平衡状态,饱和吸附容量为48.22 mgg;初始p H为2.0~9.3时,对FAU-Y吸附2,4-DMP没有明显影响;吸附动力学和吸附等温线分析结果表明,二级动力学能更好地描述FAU-Y对2,4-DMP的吸附,Langmuir-Freundlich吸附等温线对吸附平衡数据的拟合优于Langmuir吸附等温线和Freundlich吸附等温线。     

牛粪生物炭对磷的吸附特性及其影响因素研究

以牛粪生物炭为吸附剂,采用平衡吸附法研究了牛粪生物炭对磷的吸附特征.研究了pH值、共存离子、反应温度、投加量、热解温度等对牛粪生物炭吸附磷的影响.结果表明,牛粪生物炭吸附磷的最佳初始pH值为7.0;共存离子的存在对生物炭吸附磷的影响有限;反应温度升高不利于磷的吸附;当投加量为0.1g时,对磷的去除率较为理想;热解温度升高不利于对磷的吸附.通过对实验数据进行动力学、吸附等温线及热力学分析,发现牛粪生物炭对磷的吸附动力学数据符合拟二级吸附动力学方程,Langmuir-Freundlich(R2=0.9705)和Temkin(R2=0.9556)方程能很好地描述磷在牛粪生物炭上的吸附行为.热力学分析结果显示25,35,45℃下的吉布斯自由能变化(ΔG0)分别为-17.43,-15.98,-15.89kJ/mol,表明牛粪生物炭对磷的吸附是自发的过程.     

山竹壳粉吸附亚甲基蓝性能研究

研究了山竹壳粉吸附亚甲基蓝的吸附性能,考察了亚甲基蓝溶液的p H、不同初始浓度、吸附时间、温度等条件对吸附效果的影响。应用准一级动力学方程、准二级动力学方程、颗粒扩散方程模拟了山竹壳粉吸附亚甲基蓝的动力学过程,结果表明准二级动力学方程适合描述整个吸附过程。用Langmuir和Freundlich模型模拟吸附等温线,Langmuir方程更适合描述此吸附过程,在298K下最大单层吸附量为88.49mg/g。计算了吉布斯自由能(ΔG~0)、焓变(ΔH~0)、熵变(ΔS~0)、吸附势(E)等热力学参数,ΔG~0、ΔH~0、ΔS~0均0,说明此吸附过程是一个自发进行的、放热的、趋于有序的吸附过程。     

VUV/HPW/BMMs体系对全氟辛酸（PFOA）的脱氟研究

采用真空紫外灯(VUV)和双模型介孔材料(BMMs)负载磷钨酸(HPW)催化剂构建光催化体系,探究该体系对水中全氟辛酸(PFOA)的脱氟效果.研究了PFOA初始浓度、HPW/BMMs投加量、初始p H值对体系脱氟的影响,并采用响应曲面法(Response Surface Method,RSM)分析了最佳边界反应条件.结果表明,体系对PFOA具有明显的脱氟效果:脱氟效率随PFOA初始浓度的增大而减小;催化剂投加量为0.2 g·L~(-1),脱氟效率最高达50.2%;体系p H为3~4时,体系脱氟效果显著.基于Box-Behnken响应曲面法,各影响因子对脱氟效率的显著性排序为:p HPFOA初始浓度HPW/BMMs投加量.p H值与HPW/BMMs投加量及初始PFOA浓度交互作用显著,模型回归性良好,最佳运行条件为:p H=3.82,HPW/BMMs投加量为0.3 g·L~(-1),PFOA初始浓度为20 mg·L~(-1),反应4 h的脱氟率达到52.6%,与预测值相比偏差为1.2%.本研究为高效降解全氟化合物提供了新思路.     

改性芦苇生物炭对水中低浓度磷的吸附特征

为吸附处理低浓度含磷废水和实现芦苇资源化利用,将湿地植物芦苇制备成生物炭,通过负载氯化铁进行改性,探究了改性芦苇生物炭对水体中磷的吸附特征.结果表明,改性后芦苇生物炭的含铁量为11.98 mg·g~(-1),是改性前的44.7倍;改性芦苇生物炭p H_(pzc)为7.49,当溶液p H为7.0时,吸附效果最好;在磷溶液浓度为4.0 mg·L~(-1)、温度为298K时,改性芦苇生物炭平衡吸附量为0.658 mg·g~(-1),是未改性生物炭吸附量的34.6倍.研究不同温度下的吸附等温线,Langmiur方程很好地拟合不同温度的吸附等温线,该吸附是单层吸附,温度升高有利于吸附.吸附热力学研究表明,ΔG~θ0、ΔH~θ0和ΔS~θ0,说明该吸附是自发、熵增的吸热过程.假二级方程很好地拟合改性芦苇生物炭吸附磷的动力学数据,初始吸附速率随初始浓度的增大而增大,该吸附主要受颗粒内扩散控制.该研究为改性芦苇生物炭用于污水处理厂和水体深度除磷提供基础数据.     

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.