Abstract: 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)>KH2PO4>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.

Key words: kinetic characteristics, compound extractant, arsenic pollution, soil remediation