摘要
研究了生物可降解的螯合剂EDDS对城市污泥中的Cu,Zn,Cd和Pb的提取效应.EDDS提取动力学研究表明,Cu,Zn,Cd和Pb达到最大提取量的时间分别为12,24,36和36 h.EDDS提取液pH效应研究表明,pH对4种重金属元素的释放没有显著的影响.4种重金属元素的EDDS提取率：Cu为23%-39%,Zn为41%-42%,Cd为18%-24%,Pb为24%-44%.对比EDDS和EDTA对重金属的提取率：Cu为EDDS〉EDTA;Zn为EDDS≈EDTA;Cd和Pb为EDTA〉EDDS.提取之后,用BCR连续提取法研究污泥中残留的重金属元素的形态分布表明,酸溶/可交换态、可还原态和可氧化态金属浓度明显降低.综合考虑运行成本、提取率和城市污泥资源化利用价值,建议EDDS提取城市污泥条件为pH中性、提取时间24 h,从而可以有效地降低城市污泥中有效态重金属元素含量.
A biodegradable chelating agent-[S,SI stereoisomer of ethylenediamine disuccinate （EDDS） was used to extract Cu, Zn, Cd, and Pb in municipal sludges from different sources. The research on extraction kinetic of EDDS indicated that the time required to achieve maximum metal extraction from the sludges was 12 h, 24 h, 36 h and 36 h for Cu, Zn, Cd, and Pb respectively. The pH of extractant solution was not the dominant factor governing the release of the four metals. The metal extraction efficiency of EDDS was 23 % ～ 39 % for Cu, 41% - 42 % for Zn, 18% ～ 24% for Cd, and 24% ～ 44% for Pb. The order of metal extraction efficiency was as follows： EDDS 〉 EDTA for Cu, EDDS EDTA for Zn, and EDTA 〉 EDDS for Cd and Pb. After the extraction, fractions of heavy metals were separated using BCR sequential extraction procedure. Compared with the control, the obvious reduction of metal concentrations was observed in exchangeable and acid-soluble fractions, reducible fractions and oxidizable fraction. Comprehensively considering the operational cost, extraction efficiency and benefit from sludge resource utilization, the optimal conditions for EDDS extraction of municipal sludge are suggested to be neutral pH and 24 hours of extraction time, which could efficiently decrease the available heavy metals.
出处
《环境科学研究》
EI
CAS
CSCD
北大核心
2007年第6期110-114,共5页
Research of Environmental Sciences
基金
国家自然科学基金资助项目(20607010)
污染控制与资源研究国家重点实验室开放研究基金(PCRRF06001)
关键词
提取
重金属
污泥
EDDS
extraction
heavy metal
municipal sludge
ethylenediamine disuccinate （EDDS）
