Scorodite Synthesis in As(V)-Containing Fe(II) Solution in the Presence of Hematite as a Fe(III) Source
Scorodite Synthesis in As(V)-Containing Fe(II) Solution in the Presence of Hematite as a Fe(III) Source
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DOI：
10.2320/matertrans.m-m2018809
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发表时间：
2018-01-01
影响因子：
1.2
通讯作者：
Shibata, Etsuro
中科院分区：
文献类型：
--
作者：
Iizuka, Atsushi;Shinoda, Kozo;Shibata, Etsuro
通过沉淀大结晶铁长石（FeAsO4中心点2H(2)O）颗粒来稳定砷被认为是处理工业副产物中含有的As(V)的一种有前途的选择。在本研究中，研究了赤铁矿颗粒作为Fe（III）源直接添加到含有as (V)的Fe（II）溶液中，在不同的初始Fe（II）浓度下合成scoroite。在scorodite形成过程中，反应溶液的Fe（II）浓度和pH值几乎恒定，溶液中残留的砷浓度较低。初始Fe（II）浓度强烈影响球球石的形成，初始Fe（II）浓度越高，球球石晶粒越大。观测到的球石粒度比常规DMSP法形成的球石粒度大。赤铁矿粉直接加入到含As(V)的FeSO4溶液中，也可以得到粗面菱形铁长石。从环境浸出试验结果来看，短时间吹气将剩余不稳定的凝胶状前驱体转化为结晶的铁榴石，对防止砷浸出非常有效。此外，对于球球石合成过程初始阶段形成的凝胶状前驱体，在铁的Fe - K吸收边x射线吸收近边结构范围内的x射线吸收光谱化学状态分析表明，前驱体含有Fe（II）和Fe（III）。这表明铁云母不是由溶液中的赤铁矿和砷酸盐中的铁（III）离子直接形成的，而是由溶液中的铁（II）离子最初形成凝胶状前体，然后转化为结晶的铁云母。
Stabilization of arsenic by precipitation of large crystalline scorodite (FeAsO4 center dot 2H(2)O) particles is considered to be a promising option for treating As(V) contained in industrial by-products. In this study, scorodite synthesis by direct addition of hematite particles as a Fe(III) source to Fe(II) solution containing As(V) was investigated with different initial Fe(II) concentrations. During scorodite formation, the Fe(II) concentration and pH of the reaction solution are almost constant, and the residual arsenic concentration in the solution is low. The initial Fe(II) concentration strongly affects scorodite formation, and larger faceted crystalline scorodite particles are obtained with higher initial Fe(II) concentration. The observed scorodite particle size is larger than that formed by the conventional DMSP method. Coarse faceted scorodite can also be obtained by direct addition of hematite powder to FeSO4 solution with As(V). From the results of environmental leaching tests, O-2 gas blowing for a short time to convert the remaining unstable gel-like precursor to crystalline scorodite is very effective to prevent arsenic leaching. Furthermore, for the gel-like precursor formed in the initial stage of the scorodite synthesis process, chemical state analysis by X-ray absorption spectroscopy in the range of the X-ray absorption near-edge structure at the Fe K absorption edge for iron reveals that the precursor contains Fe(II) as well as Fe(III). This indicates that scorodite does not directly form from Fe(III) ions from hematite and arsenate ions from solution, but a gel-like precursor initially forms from Fe(II) ions in solution and is then converted to crystalline scorodite.