• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Removal of Heavy Metals and PAH from Contaminated Soil by Chemical Enhanced Soil Flushing/Washing and Advanced Oxidation Processes.
【24h】

Removal of Heavy Metals and PAH from Contaminated Soil by Chemical Enhanced Soil Flushing/Washing and Advanced Oxidation Processes.

机译：通过化学增强的土壤冲洗/清洗和高级氧化工艺去除污染土壤中的重金属和多环芳烃。

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

As a consequence of the increasing concern about soil contamination, research on soil remediation technology has grown rapidly. The effects of the chelant dosage, solution pH, soil-to-solution ratio and the dissolved/soil organic matter on metal extraction with the application of ethylene-diamine-tetraacetic acid (EDTA) and [S,S]-stereoisomer of ethylenediaminedisuccinic acid (EDDS) mixture (including individual additions) were investigated through batch and column studies. In addition, soil contaminated with both heavy metals and organic pollutants are commonly found and often require extra effort for remediation. The effectiveness and mechanisms of heavy metal and naphthalene co-removal from artificially contaminated soil by FeEDTA/FeEDDS-activated persulfate were investigated, again through batch studies.;Compared with Cu extraction, Pb and Zn extraction exhibit different kinetic behaviors at varying EDDS-to-metal molar ratios (under EDDS deficiency conditions) within two days. The extracted Pb and Zn were readily re-adsorbed onto the soil surfaces over time until reaching an apparent equilibrium between extraction and re-adsorption. In contrast, no readsorption occurred for Cu due to its high preference for forming complexes with EDDS. An alkaline pH range was preferable for Pb extraction when the EDDS was deficient, whereas the influence of varying the soil-to-solution ratio under EDDS deficiency was marginal compared with that of the EDDS-to-metal molar ratio and solution pH.;Higher Pb extraction by EDDS and EDTA mixture was found compared with individual additions of EDDS or EDTA under chelant deficiency conditions. It appears that the EDDS and EDTA mixture can be utilized for metal extraction in a more efficient way according to their respective affinity towards particular metals, in which Pb is primarily complexed with EDTA, while Cu and Zn bind with both EDTA and EDDS. The synergistic performance of the EDDS and EDTA mixture probably resulted from the change of chemical speciation and thus provided less competition among the Cu, Zn and Pb for the chelants.;With an excess amount of EDDS, a higher efficiency of heavy metal extraction was achieved compared to that with a deficiency of EDDS. No re-adsorption and competition among the heavy metals for EDDS was observed when a sufficient amount of EDDS was provided. In addition, the extraction of Cu, Zn and Pb by EDDS was enhanced in the presence of dissolved organic matter. The enhancement was probably due to the formation of metal-humate complexes and the soil disruption due to the humic acid enhanced Al and Fe dissolution, which induced more metals to dissolve from the soil. However, re-adsorption of the metal-humate complexes onto the soil surfaces occurred before the soil was saturated with organic matter, resulting in minor enhancement of the metal extraction.;EDDS and EDTA were found to be effective in extracting heavy metals, primarily from the exchangeable and carbonate fractions of soil (i.e., weakly sorbed fractions). To enhance the metal extraction, removal of heavy metals from the strongly sorbed fraction is necessary. Na4P 2O7 was employed after the application of EDTA and EDDS which significantly enhanced the removal of heavy metals. It promoted mineral dissolution, thereby enhancing the metal extraction as a result of soil disruption. In addition, the order of metal extraction by Na4P2O 7 was found to be Ni > Cr > Cu, probably due to the different affinities between the metals and P2O74--.;In most cases, heavy metals and polycyclic aromatic hydrocarbons in soil are removed with different individual treatment processes. Using FeEDTA/FeEDDS-activated persulfate, both types of contaminants were successfully removed from soil in one single treatment process. Heavy metals were removed due to (1) the formation of metal-chelant complexes with free EDDS/EDTA which dissociated from FeEDDS/FeEDTA; (2) metal leaching under acidic environments; (3) metal dissolution caused by soil disruption; and (4) metal exchange of sorbed metals on the soil surfaces with FeEDTA/FeEDDS. FeEDTA-activated persulfate resulted in higher naphthalene removal from the soil, compared with FeEDDS-activated persulfate. The removal was mainly via the dissolution of the naphthalene partitioned on mineral surfaces, followed by activated persulfate oxidation. Although EDDS is advantageous over EDTA in terms of biodegradability, it is not recommended for iron chelate-activated persulfate oxidation since persulfate is consumed to oxidize EDDS, resulting in a persulfate inadequacy for naphthalene oxidation.
机译：由于对土壤污染的日益关注，对土壤修复技术的研究发展迅速。乙二胺四乙酸（EDTA）和乙二胺二琥珀酸的[S，S]-立体异构体的应用对螯合剂用量，溶液pH值，土壤溶液比和溶解/土壤有机质的影响（EDDS）混合物（包括单个添加物）通过批处理和色谱柱研究进行了研究。另外，普遍发现被重金属和有机污染物污染的土壤，并且经常需要额外的补救工作。通过分批研究再次研究了FeEDTA / FeEDDS活化的过硫酸盐从人工污染的土壤中共去除重金属和萘的有效性和机理。与铜萃取相比，铅和锌的萃取在不同的EDDS-下表现出不同的动力学行为。 -两天内的金属摩尔比（在EDDS缺乏条件下）。随着时间的流逝，提取的Pb和Zn容易重新吸附到土壤表面，直到在提取和重新吸附之间达到明显的平衡。相反，由于铜非常倾向于与EDDS形成络合物，因此没有发生铜的重吸收。当EDDS不足时，优选碱性pH范围用于Pb萃取，而与EDDS与金属的摩尔比和溶液pH相比，在EDDS不足下改变土壤溶液比的影响很小。与在螯合剂缺乏条件下单独添加EDDS或EDTA相比，发现通过EDDS和EDTA混合物萃取铅。看来EDDS和EDTA混合物可根据它们对特定金属的亲和力，以更有效的方式用于金属萃取，其中Pb主要与EDTA络合，而Cu和Zn与EDTA和EDDS都结合。 EDDS和EDTA混合物的协同性能可能是由于化学形态的变化而引起的，从而使Cu，Zn和Pb之间的螯合剂竞争较少。; EDDS过量时，重金属的提取效率更高。与缺乏EDDS的相比。当提供足够量的EDDS时，未观察到重金属之间对EDDS的再吸附和竞争。此外，在溶解的有机物存在下，EDDS萃取铜，锌和铅的能力得到增强。增强作用可能是由于金属-腐殖酸盐配合物的形成，以及由于腐殖酸增强了铝和铁的溶解而导致土壤破坏，铝和铁的溶解导致更多的金属从土壤中溶解。然而，金属-腐殖酸盐络合物在土壤被有机物饱和之前发生了再吸附，导致金属提取率略有提高。EDDS和EDTA被发现可有效地提取重金属，主要是从土壤的可交换部分和碳酸盐部分（即弱吸收部分）。为了增强金属的提取，必须从强烈吸附的馏分中去除重金属。在应用EDTA和EDDS后使用Na4P 2O7，可显着提高重金属的去除率。它促进了矿物的溶解，从而由于土壤破坏而增强了金属的提取。此外，发现Na4P2O 7提取金属的顺序为Ni> Cr> Cu，这可能是由于金属与P2O74--之间的亲和力不同所致;在大多数情况下，土壤中的重金属和多环芳烃被去除具有不同的个体处理过程。使用FeEDTA / FeEDDS活化的过硫酸盐，在一次处理过程中就成功地从土壤中去除了两种类型的污染物。重金属被去除的原因是：（1）与游离的EDDS / EDTA形成的金属螯合剂络合物从FeEDDS / FeEDTA上解离出来； （2）酸性环境下的金属浸出； （3）土壤破坏引起的金属溶解； （4）用FeEDTA / FeEDDS在土壤表面进行吸附金属的金属交换。与FeEDDS活化的过硫酸盐相比，FeEDTA活化的过硫酸盐可从土壤中除去更高的萘。去除主要是通过将分配在矿物表面上的萘溶解，然后进行活化的过硫酸盐氧化。尽管就生物降解性而言，EDDS优于EDTA，但不建议将其用于螯合铁活化的过硫酸盐氧化，因为消耗过硫酸盐来氧化EDDS，导致过硫酸盐不足以进行萘氧化。

著录项

  • 作者

    Yan, Yuk Shing.;

  • 作者单位

    Hong Kong University of Science and Technology (Hong Kong).;

  • 授予单位 Hong Kong University of Science and Technology (Hong Kong).;
  • 学科 Engineering Environmental.
  • 学位 Ph.D.
  • 年度 2013
  • 页码 211 p.
  • 总页数 211
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号