铁砷共沉淀中的硫酸钙对砷固定作用  

Arsenic immobilization by gypsum during iron-arsenic coprecipitation process

作　　者：李小亮[1,2] 张丹妮[1] 王少锋[1] 王新[1] 宋雨[1,2] 贾永锋[1] 

机构地区：[1]中国科学院沈阳应用生态研究所污染生态与环境工程重点实验室,沈阳110016 [2]中国科学院大学,北京100049

出　　处：《生态学杂志》2014年第10期2803-2809,共7页Chinese Journal of Ecology

基　　金：国家杰出青年科学基金项目(40925011);国家自然科学基金项目(41103072)资助

摘　　要：铁砷共沉淀法被广泛应用于有色冶金废水的除砷固砷,但共沉淀过程中产生的硫酸钙的固砷作用迄今尚不清楚。本文利用抗坏血酸将铁砷共沉淀中的硫酸钙分离出来,分析其中的砷含量及确定其质量和固砷百分数,研究了不同pH值初始砷浓度、初始硫酸浓度及Fe/As摩尔比对砷固定的影响。结果表明:随pH值升高,硫酸钙中砷含量及固砷百分数增加。当提高体系初始砷浓度时,硫酸钙所固定的砷含量也增加。在较高初始硫酸浓度或较大Fe/As摩尔时,硫酸钙中砷含量较低,但硫酸钙固砷百分数增加。研究结果有助于进一步认清铁砷共沉淀中砷的赋存形态,为准确评价铁砷共沉淀含砷废弃物的环境风险提供科学依据。Iron（ Ⅲ）-arsenate copreeipitation is wideiy pract＇iced for the removal and immobilization of arsenic from mineral processing solutions and effluents in hydrometallurgical industry. However, the role of gypsum in the fixation of arsenic in the coprecipitation process is still un- known. In this study, the gypsum generated during iron-arsenate eopreeipitation process was iso- lated by ascorbic acid leaching and the content of arsenic, the mass of the gypsum and the percentage of arsenic fixed by gypsum were determined. The effects of initial arsenic and sulfuric acid concentrations and Fe/As molar ratio were investigated. The results showed that the content and the percentage of arsenic fixed by gypsum increased significantly with the increase of copre- cipitation pH. Raising the initial arsenic concentration of the starting solution would increase the arsenic content in gypsum. The generated gypsum contained lower content of arsenic at higher concentration of sulfuric acid or greater Fe/As molar ratios, but fixed higher percentage of arsenic from the starting solution. The findings in this work have important implications to a better understanding of the speciation of arsenic in the coprecipitates and their environmental risk assess- ments.

关 键 词：砷 共沉淀 硫酸钙 

分 类 号：X758[环境科学与工程—环境工程]