【摘要】 为评估酸化条件下铁硅复合材料（IS）对砷（As）钝化的环境稳定性,以酸滴定法结合X射线衍射分析技术（XRD）对铁硅复合材料固持态砷（IS-As）的酸释放特征开展研究.结果表明,IS具有较强的应对环境酸化的酸缓冲能力;IS-As对酸最为敏感的pH值区间介于7.68～11.48,在该区间内随酸的加入,AsO₄^3-快速溶出,该非酸稳态砷占总As的37.5%;而在pH值7.68～4.10区间,As溶出速率相对缓慢,该弱酸稳态As约占总As的7%.酸化条件下稳定存在、释放微弱的As为酸稳态,该部份约占总As的55.5%.XRD结果表明,在加入H+过程中,铁硅材料主要固砷矿物随pH值由高到低溶解的顺序依次为Ca₃（As O₄）₂>Al As O₄>As₂O₃>Ca₄Si As₄>Fe As₃O₉·4H₂O>Mn₂As₂O₇/SiAs₂.酸化条件下IS-As元素溶出率依次为S（94.8%）>Na（93.0%）>Ca（78.8%）>As（44.5%）>Mg（41.7%）> Al（37.6%）>Mn（37.5%）> Fe（5.5%）. IS-As中主要含砷矿物pH值稳定区间与伴生元素酸溶解特征结果表明,非酸稳态砷主要为钙结合态砷,弱酸稳性As主要为镁、锰、铁弱结合态,酸稳态As主要为铁锰硅强结合态.研究结果为铁硅复合材料修复土壤砷的安全利用风险评估及揭示其修复稳定机理提供了依据,并为土壤砷修复材料选择及形态研究方法方面提供新的参考.更多还原

【Abstract】 In order to assess the environmental stability of As immobilized by IS（IS-As） under acidification conditions, the acid dissolution characteristics of IS-As were investigated by using acidimetric titration method and X-ray powder diffraction（XRD） analyses. The results showed that IS was strongly resilient to the acid dissolution. The As fixed by IS was the most sensitive to acid dissolution in the pH range of 7.68～11.48, in this range the acid dissolution rate of AsO₄^3- was fast, this non acid-stable As accounted for 37.5% of total dissolved As. The As dissolution rate was relatively low in the pH range of 7.68～4.10. In this range, the proportion of weak acid-stable As accounted for 7% of total As and of acid-stable As was 55.5% of total As. XRD results showed that the dissolution order of major As containing minerals in IS under acidic conditions（ranked from high pH values to low pH values） was: Ca₃（As O₄）₂>Al As O₄>As₂O₃>Ca₄ SiAs₄>Fe As₃O₉·4 H₂ O>Mn₂ As₂ O₇/SiAs₂. The acid dissolution rate of elements from IS-As was in the order: S（94.8%）>Na（93.0%）>Ca（78.8%）>As（44.5%）>Mg（41.7%）>Al（37.6%）>Mn（37.5%）>Fe（5.5%）. Results demonstrated that the non acid-stable As in IS was mainly Ca bound As, the weak acid-stable As was primarily and weakly binding with Mg-, Mn-,Fe bearing minerals, and the acid-stable As was dominantly and strongly binding with Fe-Mn-Si containing minerals. The results provided some basis for the safety risk evaluation of applying IS on soils for the remediation of As contamination. It also provided a new reference for the selection of remediation materials for As contaminated soils as well as studies of soil As speciation.更多还原