Electrokinetic remediation of metals and organics from historically contaminated soil

The electrokinetic remediation of an historically contaminated soil is described. The soil was contaminated with a range of metals including lead, zinc, manganese, copper and arsenic, polycyclic aromatic hydrocarbons (PAHs) and benzene, toluene, ethylbenzene and xylene (BTEX). A small‐scale experiment (973.2 g dry weight soil), utilising a planar electrode configuration, investigated the potential for moving metals and organics. After 23 days treatment at a current density of 3.72 A /m⁻², 44% of calcium and 29% of manganese were removed from the soil at the cathode. Of the other contaminating metals, zinc and lead moved towards the cathode, but with no significant removal from the soil. Movement of PAHs was also observed, with a 94% reduction in concentration in the third of the soil closest to the anode after 23 days. A larger scale experiment (46.7 kg dry weight soil) utilised a hexagonal array of tubular anodes surrounding a central tubular cathode. Treatment for 112 days led to acidification of the soil to pH 2.59 closest to the anode in a direct line between the anode and cathode. Soil not directly in line between the electrodes was not acidified significantly. Movement of metal ions was observed, in line with the electrodes, with concentrations of lead and arsenic increasing to 162% and 171% of starting concentrations closest to the anode, respectively, and those of zinc, copper and manganese decreasing to 42%, 68% and 57%, respectively. At positions not directly in line with the electrodes, no significant metal movements were observed. Overall, there was no significant removal of contaminating metals from the soil. PAHs and BTEX compounds were moved by electroosmosis towards the cathode, with soil concentrations of PAHs reduced from 720 mgkg⁻¹ to 4.7 mgkg⁻¹ after 22 days. PAHS (28 mg) and benzene (9660 mg) were recovered in granular activated carbon (GAC) columns. © 2000 Society of Chemical Industry     

Electrokinetic remediation of soils contaminated with heavy metals

This paper describes the results obtained from an electrokinetic treatment of a real soil polluted by lead acetate. Powdered soil samples were pressed with a consolidometer till 100 kPa to obtain cylindrical specimens with the same characteristics as a subsoil. Tests were carried out in a Perspex electrochemical cell where soil specimens were introduced with a hollow punch. A low intensity direct current was applied in order to remove contaminants, due to electrophoresis and electroosmosis phenomena. The water flow, conductivity, apparent electroosmotic coefficient, as well as other characteristic parameters, were measured throughout the test. The water content and degree of pore saturation were estimated at the beginning and end of the test. The soil slab was divided into four slices and the Pb concentration profile determined. The main factor governing the extraction of contaminant was found to be the pH in the acidic range. Indeed, under these conditions high removal efficiencies could be reached. These results could lead to the design of a new electrochemical treatment cell equipped with a cationic membrane to expand the region of favourable pH within the soil.     

金矿尾渣中铜的电动修复

以云南省大理白族自治州鹤庆县北衙金矿尾渣为研究对象,采用电动修复技术,研究了不同的阳极工作液、不同的可渗透反应材料(PRB)和不同的可渗透反应材料放置位置对矿渣中铜的去除率的影响,分析了尾矿中铜的形态分布及修复技术对不同形态铜的去除情况.矿渣中水溶态的铜含量占总含铜量的0.7%,弱酸可提取态占5.8%,铁锰氧化物结合态占40.9%,有机物及硫化物结合态占9.7%,残渣态占42.9%.结果表明,阳极工作液为0.1mol/L柠檬酸溶液、PRB为椰壳活性炭并置于距阳极10cm处时,近阳极区矿渣中水溶态的铜去除率为66.5%,弱酸可提取态铜的去除率为51.5%,铁锰氧化物结合态铜的去除率为58.5%,而电动修复对有机物及硫化物结合态和残渣态的铜几乎没有效果.     

土壤中铀污染修复技术研究进展

铀及其衰变产物引起的土壤污染是全球关注的重大环境问题,不仅会引起生态风险,还会对人体健康造成威胁。因此,如何有效地解决铀污染、完善铀污染土壤修复技术体系,是实现铀矿冶行业可持续发展的关键。目前,铀污染土壤的修复技术主要有物理-化学修复、生物修复以及联合修复3种方式。本文首先介绍了铀在土壤中的赋存形态及其危害,然后对各种修复技术的研究现状及优缺点进行了详细综述,阐述了铀污染修复的影响因素,最后总结了目前铀污染土壤修复技术存在的挑战,并展望了该领域修复技术未来的发展方向,以期在实际应用中充分结合环境因素和各种修复方法的适用性,选择合适的修复技术实现污染土壤中铀的高效去除。     

铬污染土壤修复技术研究

Cr(Ⅵ)是世界公认的有毒致癌物,对人类健康有严重危害。随着铬化工行业的发展,铬污染问题,尤其是土壤的铬污染问题,越来越严重。描述了铬在土壤中的形态变化及土壤对铬的吸附特性,详细介绍了隔离包埋法、固化稳定法、化学还原法、土壤淋洗法、电化学修复法、微生物修复法和植物修复法等多种铬污染土壤的修复方法,并展望了当前土壤铬污染治理的发展趋势,为科学合理地处理土壤修复问题提供了方向。     

Electrokinetic remediation of a soil contaminated by the pyritic sludge spill of Aznalcollar (SW, Spain)

The electrokinetic remediation (EKR) of a soil sample contaminated with a sludge spill of pyritic mining origin is studied. The initial total metal content of the soil indicates that there is a very large concentration of Fe (about 100 g/kg), whereas other metals of environmental relevance are Zn (2390 mg/kg), Pb (1740 mg/kg), Cu (459 mg/kg) and Cd (7 mg/kg). A speciation procedure is performed for each of these metals, indicating that their mobility is quite different. Results indicate that EKR allows only the remediation of those fractions of the contaminants which are associated to the exchangeable and weak acid soluble fractions. These speciation results were used to obtain the values of the parameters that were introduced in a newly developed mathematical model which allows the prediction of the extent of the removal, the rate of recovery, and chemicals requirements. The experiments performed indicate that reversed electroosmosis (towards the anode) occurs and decreases the system performance.     

模拟Cd污染土壤的电动修复

文章研究电压、修复时间,添加新型绿色络合剂-PASP和缓冲液对电动修复实验效果的影响。结果表明,升高电压和加长修复时间都能提高Cd的迁移率。随络合剂浓度由2g,L升高到4g/L,阳极附近的迁移率由68．8％提高到78．5％,实验中在阴极加入醋酸后,阴极附近Cd的迁移率升高了12．3％,说明添加络合剂和醋酸可以提高修复效果。     

机械化学法修复石油烃污染土壤及对土壤特性的影响

以典型石油烃正十六烷为特征污染物,采用批次实验研究机械化学处理对模拟石油烃污染土壤的修复效果及影响因素;采用GC/MS分析土壤中正十六烷的降解产物,通过XRD、FTIR、SEM和BET对处理前后土壤样品进行表征,并分析土壤有机碳含量的变化,揭示石油烃污染土壤的机械化学法修复机理。结果表明,在球磨机转速为500r/min,球料比为35∶1,大、中、小钢球配比为2∶5∶3,正十六烷投加量为2.5μL/g时,球磨4h后正十六烷降解率达95.86%。球磨处理过后土壤颗粒表面变粗糙,助磨效果较好的石英含量显著增多。与处理前相比,球磨处理后未检出短链烷烃,表明正十六烷降解较为彻底。土壤有机碳含量和吸附能力显著提高,使得残留低浓度石油烃难以全部去除。机械化学法修复石油烃污染土壤具有快速、高效、彻底等优势,具有良好的应用前景。     

热解油基钻屑/橘皮钝化修复铜铅污染土壤

探究热解油基钻屑（OBDC）/橘皮（OB）生物炭资源化用于钝化修复铜铅污染土壤的效果及其对土壤微生物的影响，将热解OBDC/OB生物炭（OBDCs-OB）加入到Cu（Ⅱ）和Pb（Ⅱ）污染土壤中进行为期83 d的钝化修复实验。结果表明，OBDCs-OB表面具有—OH、—COOH等官能团、碳酸盐岩和黏土矿物等矿物组成以及多孔结构，可作为吸附剂使用；对比空白土壤，加入OBDCs-OB后，土壤阳离子交换容量（CEC）增加18.29 cmol/kg，维持pH在6.80左右；土壤中可酸溶态Cu（Ⅱ）和Pb（Ⅱ）浓度分别降低18.21%和20.07%；Cu和Pb的潜在浸出毒性分别降低52.8%和92.8%，有效钝化了Cu（Ⅱ）和Pb（Ⅱ）；土壤微生物菌落总数最大值为8.6×1010 cfu/g，土壤脱氢酶与脲酶活性最大值为127.10 μgTPE/(g·6 h)和167.10 mg/NH3-N/(kg·24 h)，增加土壤微生物群落多样性和丰富度，促进土壤微生物生长。     

生物钝化修复镉污染土壤研究进展

回顾了我国含镉土壤的场地修复。综述了利用生物钝化技术修复镉污染土壤的研究现状,重点探讨了微生物的代谢产物与镉产生硫化物或磷酸盐沉淀的微生物沉淀作用、微生物的细胞壁和其分泌的胞外聚合物直接吸附镉的微生物吸附作用以及镉离子透过微生物的细胞膜而被固定在细胞内的微生物摄取作用等生物钝化机理,并对有机钝化过程和无机钝化过程进行了介绍和评价。分析了镉在土壤中的离子交换态、碳酸盐结合态、铁锰氧化物结合态、有机结合态和残渣态等赋存形态以及土壤中pH值、氧化还原电位、有机质、共存重金属和微生物等因素对镉的生物可利用度的影响。最后阐述了生物钝化技术的优点以及该技术不能将重金属从土壤中永久去除的问题,指出生物钝化技术与其他修复方法相结合是其未来的发展方向。     

国内土壤污染现状、特点和一些修复浅见

介绍了国内土壤污染现状及其特点,以及欧美等国对土壤修复概况,并对各种修复技术方法进行对比。现国内对此刚起步,无成熟经验,先选取几个土壤污染类型修复进行示范,待取得成功经验再推广。     

过氧化尿素与微生物联合修复石油污染土壤

为揭示化学氧化法与微生物法联合修复技术在石油污染土壤修复中应用可行性,本研究采用正交实验设计和联合修复实验,以过氧化尿素（UHP）为氧化剂,Fe²⁺为激活剂,研究了UHP去除石油烃的条件及其与微生物联合修复土壤石油污染物的效果。结果表明,利用UHP氧化土壤中石油烃的最佳条件为：UHP添加质量分数4%、UHP∶Fe²⁺ （摩尔比）=30∶1及水∶土=3∶2。过氧化尿素氧化法与微生物法联合作用下,石油烃降解率比单一微生物修复法和过氧化尿素氧化修复法分别提高了35.45%~47.26%和3.35%~15.16%。过氧化尿素与微生物的修复顺序优化结果显示,过氧化尿素预氧化联合微生物修复比先进行微生物修复再进行过氧化尿素氧化对土壤中石油烃的降解率提高了11.81%。研究结果证明过氧化尿素联合微生物修复对降解土壤中石油烃污染的可行性。     

活化过硫酸盐氧化法修复有机污染土壤的研究进展

过硫酸盐在不同活化因子的作用下可产生具有强氧化性的硫酸根自由基（SO₄^-·）,能氧化分解众多的有机化合物,同时因其具有的氧化能力强、反应速度快及应用范围广等特点,近年来在环境污染治理领域备受关注。本文在对活化过硫酸盐氧化机理分析的基础上,综述了国内外利用过渡金属离子、氧化剂、热、强碱及联合活化等多种方式活化过硫酸盐修复有机物污染土壤的研究现状,并对活化过硫酸盐修复污染土壤的影响因素如氧化剂的添加量及添加方式、初始pH和反应时间进行了综述。此外,对活化过硫酸盐氧化法与电动修复、微生物修复、表面活性剂洗脱、固化稳定化等技术在土壤修复中的联合应用同样进行了的阐述。最后提出了活化过硫酸盐应用于土壤修复领域存在的问题,并对今后的研究方向进行了展望。     

Organic acid enhanced electrodialytic extraction of lead from contaminated soil fines in suspension

The implementation of soil washing technology for the treatment of heavy metal contaminated soils is limited by the toxicity and unwieldiness of the remaining heavy metal contaminated sludge. In this work, the feasibility of combining electrodialytic remediation with heterotrophic leaching for decontamination of the sludge was investigated. The ability of 11 organic acids to extract Pb from the fine fraction of contaminated soil (grains < 63 µm) was investigated, and application of the acids as enhancing reagents during electrodialytic remediation (EDR) of Pb‐contaminated soil fines in suspension was tested. Five of the acids showed the ability to extract Pb from the soil fines in excess of the effect caused solely by pH changes. Addition of the acids, however, severely impeded EDR, hence promotion of EDR by combination with heterotrophic leaching was rejected. In contrast, enhancement of EDR with nitric acid gave promising results. Copyright © 2007 Society of Chemical Industry     

Electrokinetic properties of polypropylene‐layered silicate nanocomposite fibers

Nanocomposite fibers based on polypropylene (PP) polymer were prepared with different content of nanofiller. Filaments were spun from an isotactic iPP homopolymer. Montmorillonite modified by N,N‐dimethyl‐N,N dioctadecylammonium cations was used for preparation of PP nanocomposite fibers. A PP grafted with acrylic acid was added as a coupling agent. Nanocomposite fibers were characterized, i.e., the surface morphology of PP nanocomposite fibers was observed and surface properties were defined by electrokinetic properties determination by zeta potential measurements. For particle distribution observation the plasma etching was involved as a method for sample preparation. The addition of nanoparticles has an impact on ZP value of nanofilled fibers, however, isoelectric point IEP is not significantly influenced by different concentrations of nanofiller. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009