镉污染土壤淋洗修复技术研究

采用振荡淋洗法处理Cd污染土壤。考察了不同淋洗剂对污染土壤中Cd的去除效果,以及淋洗剂浓度、淋洗剂pH、淋洗剂体积与土壤质量比(液土比)等条件对淋洗效果的影响。采用Tessier分步提取法对淋洗前后的Cd形态分布进行分析,并对淋洗废液的再生利用情况进行了研究。实验结果表明：乙二胺四乙酸二钠(EDTA-Na₂)是高效的Cd污染土壤淋洗剂,当EDTA-Na₂浓度为0.03 mol/L、淋洗剂pH为3、液土比为4:1时,Cd去除率可达73.27%;土壤中Cd的主要去除形态为可交换态;采用新型二硫代羧酸功能化树枝状聚合物(DPETA-CSSNa)对淋洗废液进行再生,再生后淋洗液的Cd去除性能基本不变。     

复合淋洗剂对熔炼厂遗留场地土壤Pb、Cd的浸提效果

以某熔炼厂遗留场地重金属污染土壤作为研究对象,选取柠檬酸(CA)、复合聚天冬氨酸(PASP)、十二烷基苯磺酸钠(SDBS)作为淋洗剂,采用振荡淋洗法研究了不同浓度和配比的单一淋洗剂和复合淋洗剂对污染土壤Pb和Cd的去除效果。实验结果表明:CA、PASP、SDBS单独使用时对Pb和Cd的浸提率均随淋洗剂浓度提高而增大,CA对Pb、PASP对Pb、SDBS对Cd的最高浸提率分别为45.71%、63.69%和39.04%;CA-PASP复合淋洗剂淋洗Pb时有拮抗作用,单独使用PASP淋洗Pb效果更好,CA-PASP复合淋洗剂对Cd的浸提率较低;CASDBS复合淋洗剂效果最佳,对Pb和Cd的最高浸提率分别为55.22%和73.90%。     

汞矿区汞污染土壤的淋洗修复

以贵州省铜仁市汞矿区汞污染土壤为研究对象,分别采用KI、Na_2S_2O_3、乙二胺四乙酸、柠檬酸、酒石酸、十二烷基硫酸钠溶液对其进行淋洗修复,筛选出合适的淋洗剂,优化了淋洗条件,并探索了淋洗液的处理方法。实验结果表明:对该土壤淋洗效果最好的淋洗剂为Na_2S_2O_3,最佳淋洗条件为Na_2S_2O_3浓度0.01 mol/L、固液比(g/m L)1∶5、淋洗时间4 h、淋洗次数1次,在此条件下土壤中总汞的淋洗率为13.41%,有效态汞含量可降至原来的61.54%;Na2S对淋洗液中的汞具有较好的去除效果,每升淋洗液加入0.6 g Na_2S处理后,即可满足GB8978—1996《污水综合排放标准》。     

酒石酸协同草酸淋洗镍污染土壤

研究了柠檬酸、酒石酸、苹果酸和草酸及酒石酸协同草酸淋洗镍污染土壤的效果，优化了淋洗的工艺条件。结果表明：采用0.30 mol/L的酒石酸与0.20 mol/L的草酸以体积比为1∶4配成淋洗剂，淋洗时间为720 min，液固比（淋洗剂体积与土壤质量比，mL/g）为25.0，淋洗剂pH不做调节，淋洗后土壤中镍的去除率达73.7%，镍的浸出质量浓度降至3.89 mg/L，低于危险废物鉴别标准值5 mg/L；酒石酸协同草酸淋洗使土壤中镍的弱酸提取态含量下降了80.2%，可还原态含量下降了74.7%。     

无患子皂苷与柠檬酸协同洗脱污染土壤中镉铅

以某废弃铅锌矿区重金属污染土壤为研究对象,采用无患子皂苷与柠檬酸（CA）协同洗脱污染土壤中的Cd和Pb。以无患子果皮投加量为20 g/L所得水浸提液和浓度为0.3 mol/L的CA配制复配淋洗剂。在浸提液中添加CA后,能有效提高对土壤中Pb的去除率。在浸提液和CA的体积比为1∶3、淋洗剂pH为5、淋洗时间为12.0 h的条件下,复配淋洗剂对Cd和Pb的去除率分别为75.2%和41.6%。双常数方程和Elovich方程均可较好描述复配淋洗剂对污染土壤中Cd和Pb的淋洗过程,表明Cd和Pb的解吸主要为非均相扩散过程。复合淋洗剂能有效降低土壤中Cd的可交换态和Pb的铁锰氧化态含量,并可促进重金属形态的转变。     

皂素和柠檬酸复合淋洗土壤中的钍

采用振荡淋洗和土柱动态淋洗实验研究了皂素和柠檬酸复合对土壤中钍的淋洗性能。实验结果表明:将质量浓度为20 g/L的皂素与浓度为20 mmol/L的柠檬酸以体积比1∶10配制复合淋洗液对污染土壤中钍的去除效果最佳,淋洗3.0 h,钍去除率为84.98%;准一级动力学方程能更好地描述复合淋洗液对钍的淋洗动力学特征;动态淋洗实验中当复合淋洗液用量为1 600 mL时,钍的累积去除量为73.66 mg/kg;淋洗后土壤中钍的酸可提取态、氧化结合态和有机结合态含量分别减少了79.63%、38.13%和20.34%,残渣态含量变化不大;淋洗后土壤中钍的稳定性增加。     

油田压裂返排液处理技术研究进展

分析了油田压裂返排液的组分和特点,归纳总结了成熟的传统压裂返排液处理技术和新型处理技术的优缺点,提出了压裂返排液处理应朝着优化工艺组合、开发高级氧化和电絮凝等新技术、研制撬装处理设备使处理工艺模块化和有效成分回收利用等未来方向发展,为油田压裂返排液无害化、资源化处理技术的研发提供了思路和参考。     

淋洗修复重金属和多环芳烃复合污染土壤的研究进展

重金属和多环芳烃（PAHs）常共存于土壤中形成复合污染。作为典型无机污染物和有机污染物的代表，淋洗法可同时有效去除这两类污染物，具有良好的发展前景。本文结合国内外的研究成果，从重金属和PAHs在环境中的行为着手，重点论述了常用淋洗剂的种类、去除机理和优缺点，分析了影响复合污染物去除效果的主要因素，并对今后该技术的发展方向进行了展望。     

化工过程废物最小化方法的研究进展

系统化的废物最小化方法对于环境友好且具有竞争力的化工过程的研发、综合、设计和改造具有非常重要的指导作用。简介了废物最小化的一般原则;综述了目前国内外各类系统的废物最小化方法,包括定性类方法如分层决策法、环境优化技术法、结构化法及3Es法等,定量类方法如各种数学优化法、夹点分析法、废物削减算法以及人工智能法及组合式方法;展望了该领域的研究发展趋势。     

湿法冶锌废渣中有价金属回收研究进展

综述了电化学法、沉淀法、吸附法、离子交换法、浮选法和液膜分离法等在分离回收湿法冶锌废渣中有价金属及相关领域的研究进展,阐述了吸附法和液膜分离法的原理,指出了湿法冶锌废渣中有价金属回收的研究方向:吸附法拥有巨大的潜力,是今后的研究重点;离子交换法的研究热点是开发新型树脂基体;液膜分离法的研究方向一是提升液膜稳定性,二是研发能够高效单一分离有价金属的载体。     

络合萃取法处理2-萘酚生产废水

采用络合萃取法处理2-萘酚生产废水，比较了分别以三辛胺、十二烷基二甲基胺（十二叔胺）、三烷基胺作为萃取剂的萃取效果，其中三辛胺萃取效果最佳，三烷基胺次之，十二叔胺的萃取效果最差。处理2-萘酚生产废水的最佳工艺条件为：以三辛胺作为萃取剂，萃取剂加入量为8.5%，废水pH为1.0。在此最佳工艺条件下废水的COD去除率可达97.2%。采用NaOH溶液反萃取后的萃取剂用于第二次萃取，COD去除率为96.4%，再反萃取后用于第三次萃取，COD去除率为94.9 %。萃取剂可重复使用。     

萃取法分离回收不锈钢酸洗污泥硫酸浸出液中的重金属

采用非皂化P204和皂化P204萃取剂对不锈钢酸洗污泥的硫酸浸出液进行萃取。在浸出液pH为0.80、非皂化P204体积分数为25%、萃取剂与浸出液体积比为1∶2、萃取时间为5 min的条件下,Fe~(3+)萃取率达99.64%,Cr~(3+)和Ni~(2+)萃取率为3.98%和6.99%,一次萃余液pH为0.64。采用皂化P204对除Fe~(3+)后的一次萃余液进行萃取,在P204体积分数为25%、萃取剂与浸出液体积比为1∶2、萃取剂皂化率为60%、一次萃余液pH为1.50、萃取时间为5 min的条件下,Ni~(2+)萃取率为93.12%,Cr~(3+)萃取率为20.69%,二次萃余液pH为2.63。     

RECOVERY OF GALLIUM FROM COAL FLY ASH BY A DUAL REACTIVE EXTRACTION PROCESS

The extraction of gallium from coal fly ash by leaching and extraction with commercial extractants Amberlite LA-2 and LIX 54N dissolved in kerosene was studied. Leaching of gallium and other metals from the fly ash was carried out with 6 M hydrochloric acid. The leaching liquor is first contacted with Amberlite LA-2 which extracts the gallium and iron. The iron is then precipitated with sodium hydroxide, while gallium remains in solution. Gallium is extracted selectively from the base solution with LIX 54; the resulting stripped solution contains 83% of the gallium present in the leaching liquor. A flow diagram for this dual-extraction process is proposed.     

从废FCC催化剂和废汽车尾气净化催化剂中回收稀土的研究进展

以稀土元素(简称稀土)用量较大的废FCC催化剂和废汽车尾气净化催化剂为研究对象,分析总结了两类废催化剂中稀土的成分和回收方法。从废催化剂中回收稀土普遍采用先浸出、后分离提纯的方法。浸出普遍采用无机酸(多为盐酸),分离方法包括溶剂萃取法、化学沉淀法等,最后经焙烧得到稀土氧化物。为从废催化剂中高效回收稀土,可着重考察新浸出机制的引入、分离方式的选择、分离试剂的应用,以及浸出和分离条件的优化,从而为实现工业化回收提供技术支持。     

Leaching behavior of heavy metals from municipal solid waste incineration bottom ash and its geochemical modeling

With the increase in the number of municipal solid waste incineration (MSWI) plants constructed in China recently, great attention has been paid to the heavy metal leaching toxicity of MSWI residues. In this study, the effects of various parameters, including extractant, leaching time, liquid-to-solid ratio, leachate pH, and heavy metal content, on the release properties of Cd, Cr, Cu, Ni, Pb, and Zn from MSWI bottom ash were investigated. Partial least-squares analysis was employed to highlight the interrelationships between the factors and response variables. Both experimental research and geochemical modeling using Visual MINTEQ software were conducted to study the pH-dependent leaching behavior of these metals in fresh and weathered bottom ash, considering precipitation/dissolution and surface complexation reactions (adsorption by hydrous ferric oxide and amorphous aluminum oxide/hydroxide). The results showed that leachate pH was the predominant factor influencing heavy metal leachability. The leaching of Cu, Pb, and Zn was mainly controlled by precipitation/dissolution reactions, whereas surface complexation had some effect on the leaching of Cr, Cd, and Ni for certain pH ranges. The modeling results aggreed well with the experimental results. Part of this work was presented at the Fourth International Conference on Combustion, Incineration/Pyrolysis and Emission Control (i-CIPEC)     

Influence of treatment techniques on Cu leaching and different organic fractions in MSWI bottom ash leachate

The leaching of heavy metals, such as copper, from municipal solid waste incinerator (MSWI) bottom ash is of concern in many countries and may inhibit the beneficial reuse of this secondary material. Previous studies have focused on the role of dissolved organic carbon (DOC) on the leaching of copper. Recently, a study of the Energy Research Centre of The Netherlands (ECN) showed fulvic acid-type components to exist in the MSWI bottom ash leachates and to be likely responsible for the generally observed enhanced copper leaching. These findings were verified for a MSWI bottom ash (slashed circle 0.1-2 mm) fraction from an incinerator in Flanders. The filtered leachates were subjected to the IHSS fractionation procedure to identify and quantify the fractions of humic acid (HA), fulvic acid (FA) and hydrophilic organic carbon (Hi). The possible complexation of fulvic acid with other heavy metals (e.g., lead) was also investigated. The identified role of fulvic acids in the leaching of copper and other heavy metals can be used in the development of techniques to improve the environmental quality of MSWI bottom ash. Thermal treatment and extraction with a 0.2 M ammonium-citrate solution were optimized to reduce the leaching of copper and other heavy metals. The effect of these techniques on the different fractions of organic matter (HA, FA, Hi) was studied. However, due to the obvious drawbacks of the two techniques, research is focused on finding other (new) techniques to treat MSWI bottom ash. In view of this, particle size-based separation was performed to evaluate its effect on heavy metal leaching and on HA, FA and Hi in MSWI bottom ash leachates.     

黑白显像管玻壳铅尘中铅的提取方法

研究了黑白显像玻壳生产中产生的含铅粉尘的水溶性,酸溶性,浸出毒性和铅的存在形态,提出了用盐酸循环浸铅,冷析ＰｂＣｌ２的提铅方法,考察了浸取剂及浓度,浸取温度,浸取时间对铅浸出率的影响,为充分利用铅资源及实现铅尘无害化提供了依据。     

Pretreatment and utilization of waste incineration bottom ashes: Danish experiences

Within recent years, researchers and authorities have had increasing focus on leaching properties from waste incineration bottom ashes. Researchers have investigated processes such as those related to carbonation, weathering, metal complexation, and leaching control. Most of these investigations, however, have had a strong emphasis on lab experiments with little focus on full-scale bottom ash upgrading methods. The introduction of regulatory limit values restricting leaching from utilized bottom ashes, has created a need for a better understanding of how lab-scale experiences can be utilized in full-scale bottom ash upgrading facilities, and the possibilities for complying with the regulatory limit values. A range of Danish research and development projects have, during 1997-2005, investigated important techniques for bottom ash upgrading. The primary focus has been placed on curing/aging, washing with and without additives, organic matter, sampling techniques, utilization options, and assessment tools. This paper provides an overview of these projects. The main results and experiences are discussed and evaluated with respect to bottom ash upgrading and utilization. Based on this discussion, development needs and potential management strategies are identified.     

多组分电镀污泥酸浸出液中铁的分离

研究了采用Ｐ５０７－煤油－Ｈ２ＳＯ４萃取体系分离电镀污泥酸浸出液中Ｆｅ＾３＋的工艺，确定了从含有多种上金属组分的硫酸溶液中萃取铁的最佳工艺条件以及负载有机相反萃取较优工艺条件，研究结果表明，以Ｐ５０７为萃取剂，硫酸为洗涤剂，经３级萃取、２级洗涤的分馏萃取后，可以从含有多种金属组分的硫酸溶液中分离出９９．９％的铁，其他金属的流失量小于１％，不影响后者的回收，铁在工艺过程中以ＦｅＣｌ３·６Ｈ２Ｏ的形式     

Removal of copper,chromium and arsenic from preservative-treated wood by chemical extraction-fungal bioleaching

Large volumes of preservative-treated wood containing toxic Cr, Cu and As salts are decommissioned worldwide. This study investigated the effectiveness of solid-state fermentation with copper-tolerant brown-rot fungi for the remediation of wood treated with chromated copper arsenate (CCA) and acid copper chromate (ACC) formulations. Treatment of CCA- and ACC-wood with the most effective strain, Antrodia vaillantii FRLP-14G, attained extensive leaching of As and/or Cr, but Cu elimination was poor (<18%). Additional research showed that a variety of organic acids, including citrate, are effective Cu extractants. Based on these findings, a process combining chemical extraction and subsequent fungal treatment was developed that proved highly effective in removing inorganic pollutants from CCA-wood. Extraction of CCA-wood with citric acid (30 mM, pH 3.10) followed by a 28-day solid-state fermentation period removed 87% Cu, 80% Cr, and 100% As. These results indicate the potential of the two-stage process for the remediation of preservative-treated wood.