以砷污染土壤为研究对象,用化学萃取法中的批量振荡实验法,分别考察5种萃取剂的单一及复合作用效果,得到砷污染土壤的最佳萃取剂优化组合方式,并通过动力学特征实验考察萃取过程中的速率控制步骤和因素.结果表明:单一萃取剂对土壤中砷的去除效果依次为草酸(OX)>NaOH>乙二胺四乙酸(EDTA)>KH2 PO4>柠檬酸;2种复合萃取剂除砷率最高的组合为EDTA+OX,优化实验条件为m(土):V(溶液)=1:8,振荡萃取8 h,除砷率达85.5%;适当的组合萃取剂高于单一萃取剂的除砷效果.3种和2种萃取剂复合的作用效果无明显差别;不同复合萃取剂的动力学过程可用准二级方程描述(p<0.01),推测萃取过程主要受化学反应机理的控制,反应涉及萃取剂与砷化物之间的电子共用或电子转移.%Taking the arsenic-contaminated soil as the research object ,the single and compound effects of 5 extractants were investigated by the batch oscillation of chemical extraction method . The optimum combination method of the best extractant in arsenic-contaminated soil was obtained ,and the rate-determining steps and factors in the extraction process were investigated by the dynamic characteristic experiment .The results show that the removal effect of single extraction on arsenic in soil is oxalic acid (OX)> NaOH > ethylenediaminetetraacetic acid (EDTA )> KH2 PO4 > citric acid . The combination of EDTA and OX can achieve the highest arsenic removal rate with 85.5% under the optimized experiment conditions of m(soil): V (water)= 1 : 8 ,and oscillation time at 8 h .The appropriate two-two combination of extractant for arsenic-contaminated soil can achieve a better effect than single . There is no obvious difference in the effect of the combination of three and two extractants .The dynamic process of different compound extractants can be described by the quasi-second-order equation .It is speculated that the extraction process is mainly controlled by the chemical reaction mechanism , and the reaction involves electron sharing or electron transfer between the extractant and the arsenic compound .
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