硫化砷渣一步水热矿化成臭葱石和单质硫的研究  

One-step hydrothermal transformation of arsenic sulfide residues to scorodite and sulfur

作　　者：时坚 李明洋 王永净 刘峰[2] 王永好 张静[2] SHI Jian;LI Mingyang;WANG Yongjing;LIU Feng;WANG Yonghao;ZHANG Jing(College of Environment and Resources,Fuzhou University,Fuzhou,350108,China;Research Center of Eco-Environmental Sciences,Chinese Academy of Sciences,Beijing,100085,China)

机构地区：[1]福州大学环境与资源学院,福州350108 [2]中国科学院生态环境研究中心,北京100085

出　　处：《环境化学》2022年第2期591-599,共9页Environmental Chemistry

基　　金：国家自然科学基金重点项目(21836002)资助。

摘　　要：硫化物沉淀法是最常用的处理含砷废水的方法之一,但该方法会产生大量的无定形硫化砷渣,砷渣中的砷元素在微生物和pH值等环境因素的影响下,容易重新释放到环境中引起二次污染.因此本文选取硫化砷作为研究对象,借鉴含砷废水的处理思路,将硫化砷在氧化性条件下转化成化学性质和结构稳定的臭葱石,同时回收单质硫,单质硫的回收率为90%左右,最终实现无定形硫化砷的稳定化处理.实验结果表明,最优的实验条件是水热温度和时间分别为120℃和10 h,最佳pH值为3,最佳的Fe/As摩尔比为1.2:1;在上述实验条件下,硫化砷能够一步直接转化成臭葱石,转化率达90%以上.该方法有效地减化了常见的硫化砷渣处理所涉及的溶解-调节-再处理的分步处理过程,且生成的臭葱石浸渍90 d后砷的浸出浓度为2.2 mg·L^(-1),小于国家的《危险废物鉴别标准浸出毒性鉴别》中规定的限值(5 mg·L^(-1));最终,将该方法应用于实际砷渣的处理,砷渣处理后砷的浸出浓度小于1mg·L^(-1),由此说明该方法是一种简单高效地稳定硫化砷渣和回收硫资源的方法.Sulfide precipitation is one of methods used to dispose arsenic-containing wastewater.Notably,the above process can produce many amorphous arsenic sulfide residues.The arsenic sulfide residues are highly toxic and might cause secondary pollution because of the leaching of arsenic element.In this work,the synthesized arsenic sulfide was adopted to study its stabilization based on the protocol of treatment of arsenic-containing wastewater.Under the oxidizing conditions,the arsenic sulfide can be transformed to scorodite and elemental sulfur.The recovery rate of elemental sulfur is about 90%.The optimal conditions are shown as following,hydrothermal temperature is 1200 C,hydrothermal time is 10 h,pH value is 2 and Fe/As=1.2:1.Under the optimal condition,the conversion rate of arsenic sulfide can reach more than 90%.This method greatly simplifies the conventional treatment of arsenic sulfide residues,which means the process of dissolving-reprecipitation can be accomplished by one step in this work.In addition,the leaching concentration of arsenics is 2.2 mg·L^(-1) for the treated arsenic sulfide after impregnating 90 days,which is lower than the limiting value(5 mg·L^(-1) originated from identification standards for hazardous wastes-identification for extraction toxicity).For actual arsenic sulfide,the leaching concentration of arsenics decreased from 425 mg·L^(-1) to 0.98 mg·L^(-1) by above transformation treatment.Therefore,this transformation protocol is a promising method for the stabilization of arsenic sulfide residues.

关 键 词：硫化砷渣 稳定化 臭葱石 硫单质 

分 类 号：X703[环境科学与工程—环境工程]