天然海水中碳钢缓蚀剂吸附和阳极脱附行为的研究

以锌盐、葡萄糖酸盐为主要缓蚀成分复配的适用于天然海水中碳钢的高效缓蚀剂,采用极化曲线、循环伏安曲线和交流阻抗谱图分析了该缓蚀剂的阳极脱附行为.结果表明,碳钢在海水中的零电荷电位约为-0.6 V;缓蚀剂的吸附电位区间为-0.5～-0.8 V,缓蚀剂在该区间内存在特性吸附.当阳极极化电位超过-0.45 V时,极化电流迅速增大,缓蚀剂因发生大量脱附而失去对阳极过程的控制.     

电增强活性炭纤维吸附有机污染物的动力学研究

研究了在电极化条件下,几种具有代表性污染物质在活性炭纤维上的电吸附动力学特性.结果表明,各种污染物的电吸附动力学比较好地符合Lagergren一级吸附动力学,其平衡吸附量在电极化下的增加量各不相同.在400mV的极化电位下,苯酚钠的吸附量从开路时的0.008 3mmol·g^-1增加到0.18 mmol·g^-1,增加了17倍;而对硝基苯酚的吸附量从开路时的2.93mmol·g^-1降到2.65 mmol·g^-1.在-400mV的极化电位下,苯胺的吸附量从开路时的3.60 mmol·g^-1增加到3.88 mmol·g^-1;而十二烷基苯磺酸钠的吸附量从开路时的2.20 mmol·g^-1降到1.59 mmol·g^-1.说明不同取代基的苯衍生物,电吸附改变量不相同,供电子基团的单取代苯,正极化都能明显增强其吸附量;但是吸电子基团的单取代,正负极化对吸附量的影响都很小;供体-共轭桥键-受体型结构的苯衍生物,正负极化都使其吸附减弱但吸附速率加快.静电作用在离子型污染物的电吸附中表现明显.     

活性炭处理皂素废水及其再生的实验研究

采用活性炭对皂素废水进行吸附处理,研究了活性炭投加量、吸附时间及吸附次数对皂素废水色度去除率的影响.同时,研究了在微波辐照条件下,微波功率和辐照时间对吸附皂素废水后的活性炭脱附的影响.结果表明,当活性炭投加量为0.13g·mL-1时,吸附12h后皂素废水的色度去除率为96.17%.此条件下活性炭可以重复吸附皂素废水3次(按照色度去除率70%为限).当微波功率为500W、辐照时间为30min时,活性炭可被有效地再生,活性炭的再生率可达79.75%.     

电增强环氧树脂基聚合物膜萃取水样中的硝基苯

以环氧树脂基聚合物膜为萃取相,在电场作用下富集目标物,与高效液相色谱(HPLC)联用,应用于环境水样中硝基苯污染物的测定.考察了电压大小、萃取时间、洗脱时间、离子强度和溶液pH值对电增强萃取效率的影响.实验结果表明,环氧树脂基聚合物膜的萃取量与膜上所施加的控制电位相关,阴极极化时,膜对硝基苯的萃取量增大;在阳极极化时,膜萃取量减小.在电压为-0.3kV,硝基苯溶液pH=4的条件下,萃取20min,得到该方法的检出限为0.015μg·mL-1,在0.05～3.0μg·mL-1范围内具有良好的线性关系,可决系数为0.9929,变异系数小于5%.用上述方法分析鱼塘水,硝基苯3种不同加标水平的回收率为79.8%～108.2%.结果表明,该方法既可用于环境水样品中的硝基苯去除又可用于检测.     

电场辅助活性炭吸附法去除水中的Cu2+

通过电场辅助活性炭吸附水中的Cu²⁺,分析吸附机理,pH值对Cu²⁺吸附的影响以及活性炭电极的再生性.结果表明,活性炭电极添加电场后,Cu²⁺的去除率明显提高,当活性炭电极间施加1.0V电压时,Cu²⁺的去除率提高了223.5%.通过Langmuir和Freundlich吸附等温线模型分析,添加电场后,活性炭电吸附Cu²⁺主要是带电活性炭表面形成的双电层作用,而不仅仅是活性炭表面化学吸附点位.pH值对电场辅助活性炭吸附水中Cu²⁺的影响极大,pH值太低时,水中H⁺会与Cu²⁺竞争活性炭表面化学吸附点位以及双电层点位.研究发现采用电极短接方式可提高Cu²⁺后的脱附率及脱附速率,脱附率达到79.1%.通过FTIR图谱可知,表面官能团-COOH和-C=O吸附的Cu²⁺难以脱附出来,但得益于此,再循环吸附-脱附2~4次时,主要以双电层静电吸附为主,脱附效率提高,电极的再生性良好.     

KOH活化微孔活性炭对对硝基苯胺的吸附动力学

以互花米草为原料,经过碳化、KOH活化两步法制备了低成本、高比表面的微孔活性炭SAAC.通过静态实验研究了活性炭SAAC对水溶液中对硝基苯胺的吸附特性,并从动力学角度探讨了吸附机理.结果表明,微孔活性炭SAAC对对硝基苯胺吸附动力学数据符合准二级方程,吸附速率在前25min由内扩散控制,而后由膜扩散与内扩散共同控制.Freundlich方程能更好地描述对硝基苯胺在活性炭SAAC上的等温吸附行为;在15℃时,活性炭SAAC对对硝基苯胺的Langmuir最大吸附量为719mg/g.     

载溴活性炭去除烟气中的单质汞

为提高活性炭对烟气中单质汞的吸附作用,利用溴对活性炭进行处理.通过对吸附容量和吸附动力学的测试,研究了载溴活性炭对气体中的单质汞的去除行为.结果表明,载溴可使活性炭对单质汞的吸附量显著增加,并加快对单质汞的吸附速率.实验条件下,当载溴量为0.33%时,活性炭对汞的饱合吸附量可增加约80倍,吸附容量达0.2mg/g;相对吸附系数增加了约40倍.溴负载量越高,吸附强化作用越显著.温度升高,载溴活性炭的吸附能力略有下降,烟气中的二氧化硫对单质汞的吸附速率略有抑制作用.     

高比表面积活性炭(HSAAC)对水中镉(Ⅱ)吸附性能的研究

以石油焦基为原料,采用KOH活化法制取高比表面积活性炭.考察了高比表面积活性炭吸附水中Cd(Ⅱ)时,pH值、Cd(Ⅱ)浓度、吸附时间和活性炭用量等因素对Cd(Ⅱ)吸附量和水中Cd(Ⅱ)残余浓度的影响.实验结果表明高比表面积活性炭在适宜条件下对Cd(Ⅱ)具有较大的吸附量和良好的再生效果.为HSAAC在废水中的实际应用提供了理论依据.     

海洋工程用新型牺牲阳极设计与性能研究(Ⅲ)——中尺寸阳极实海试验研究

目的通过构型优化设计一种新型牺牲阳极,使其在与常规阳极质量相当的前提下,增加初期发生电流,使被保护体较快极化到保护电位,后期发生电流降低,满足平均和末期保护电流需要,达到节约牺牲阳极用量的目的。方法通过在传统梯形阳极两侧增加两个翼翅优化设计出新型牺牲阳极,并针对中等规格尺寸的新型阳极与常规阳极进行实海试验。结果质量与常规阳极相近的新型阳极,初期发生电流增加11%,而后逐渐增加到18%,被保护体优先极化到保护电位。翼翅消耗完全后,新型阳极与常规阳极均呈圆柱形,发生电流亦与常规阳极相当。结论所设计的新型牺牲阳极在与常规阳极质量相当的前提下,可使被保护体较快极化到保护电位,节约了牺牲阳极用量。     

一种两步联合控制吸附动力学模型的研究

以酸性染料为对象 ,进行了粒状活性炭吸附扩散过程的动力学研究 .实验结果表明活性炭对酸性红B的吸附反应速度主要受吸附物质向活性炭表面的迁移速度和活性炭颗粒内的扩散速度的影响 ,由此建立了一种新的活性炭吸附过程的复合动态吸附模型 ,并使模型符合在较低浓度时受一级扩散反应控制为主 ,在较高浓度时受Boyd扩散控制为主 .该模型能将不同浓度下的扩散动力学过程统一起来     

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.     

Oxidation of As(Ⅲ) by potassium permanganate

The oxidation of As(Ⅲ) with potassium permanganate was studied under conditions including pH, initial As(Ⅲ) concentration and dosage of Mn(Ⅶ). The results have shown that potassium permanganate was an effective agent for oxidizing of As(Ⅲ) in a wide pH range. The pH value of tested water was not a significant factor affecting the oxidation of As(Ⅲ) by Mn(Ⅶ). Although theoretical redox analyses suggest that Mn(Ⅶ) should have better performance in oxidization of As(Ⅲ) within lower pH ranges, the experimental results show that the oxidation efficiencies of As(Ⅲ) under basic and acidic conditions were similar, which may be due to the adsorption of As(Ⅲ) on the Mn(OH)2 and MnO2 resulting from the oxidation of As(Ⅲ).     

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.     

Chlorobenzenes in waterweeds from the Xijiang River （Guangdong section） of the Pearl River

The Xijiang River is the major source of water for about 4.5 millions of urban population and 28.7 millions of rural population. The water quality is very important for the health of the rural population. The concentration and distribution of chlorobenzenes (CBs) in both water and waterweeds collected from 4 stations in the Xijiang River (Gangdong section) of the Pearl River in April and November were determined. The result showed that nearly every congener of CBs was detected. The total contents of CBs (∑CBs) in the river water ranged from 111.1 to 360.0 ng/L in April and from 151.9 to 481.7 ng/L in November, respectively. The pollution level of CBs in the water in April was higher than that in November. The contents of ∑ CBs in waterweeds ranged from 13.53×102 μg/g to 38.27×102μg/g dry weight (dw). There was no significant difference between April and November in waterweeds. The distribution of CBs in roots, caulis, and leaves of Vallisneria spiralis L. showed different patterns. The leaves mainly contained low-molecular-weight CBs(DCBs), whereas the roots accumulated more PCBs and HCBs. The average lgBCFlip (bioconcentration factor) of CBs ranged from 0.64 to 3.57 in the waterweeds. The spatial distribution character of CBs in the Xijiang River was: Fengkai County ＜ Yunan County ＜Yun'an County ＜ Gaoyao County according to the ∑CBs, and the pollution deteriorated from the upstream to the downstream of the Xijiang River. Further analysis demonstrated that the discharge of waste containing CBs may be the main source of CBs pollution in the Xijiang River.     

Degradation of 2,4-dichlorophenol with a novel TiO2/Ti-Fe-graphite felt photoelectrocatalytic oxidation process

Degradation of 2,4-dichlorophenol(2,4-DCP)was studied in a novel three-electrode photoelectrocatalytic(PEC)integrative oxidation process,and the factors influencing the degradation rate,such as applied current,flow speed of O_2,pH,adscititious voltage and initial 2,4-DCP concentration were investigated and optimized.H_2O_2 was produced nearby cathode and Fe~(2 )continuously generated from Fe anode in solution when current and O_2 were applied,so,main reactions,H_2O_2-assisted TiO_2 PEC oxidation and E-Fenton reaction,occurred during degradation of 2,4-DCP in this integrative system.The degradation ratio of 2,4-DCP was 93% in this integrative oxidation process,while it was only 31% in E-Fenton process and 46% in H_2O_2-assisted TiO_2 PEC process.So,it revealed that the degradation of 2,4-DCP was improved greatly by photoelectrical cooperation effect.By the investigation of pH,it showed that this integrative process could work well in a wide pH range from pH 3 to pH 9.     

Effect of copper on the degradation of pesticides cypermethrin and cyhalothrin

The influence of coexisting copper (Cu) ion on the degradation of pesticides pyrethroid cypermethrin and cyhalothrin in soil and photodegradation in water system were studied.Serial concentrations of the pesticides with the addition of copper ion were spiked in the soil and incubated for a regular period of time,the analysis of the extracts from the soil was carried out using gas chromatography (GC).The photodegradation of pyrethroids in water system was conducted under UV irradiation.The effect of Cu~(2 ) on the pesticides degradation was measured with half life (t_(0.5)) of degradation.It was found that a negative correlation between the degradation of the pyrethroid pesticides in soil and Cu addition was observed.But Cu~(2 ) could accelerate photodegradation of the pyrethroids in water.The t_(0.5) for cyhalothrin extended from 6.7 to 6.8 d while for cypermethrin extended from 8.1 to 10.9 d with the presence of copper ion in soil.As for photodegradation,t_(0.5) for cyhalothrin reduced from 173.3 to 115.5 rain and for cypermethrin from 115.5 to 99.0 min.The results suggested that copper influenced the degradation of the pesticides in soil by affecting the activity of microorganisms.However, it had catalyst tendency for photodegradation in water system.The difference for the degradation efficiency of pyrethroid isomers in soil was also observed.Copper could obviously accelerate the degradation of some special isomers.     

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.