Transactions of Nonferrous Metals Society of China The Chinese Journal of Nonferrous Metals

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中国有色金属学报(英文版)

Transactions of Nonferrous Metals Society of China

Vol. 27    No. 9    September 2017

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Redox behavior and chemical species of arsenic in acidic aqueous system
Jin-qin YANG1, Li-yuan CHAI1,2, Qing-zhu LI1,2, Yu-de SHU1,2

1. School of Metallurgy and Environment, Central South University, Changsha 410083, China; 2. National Engineering Research Centre for Control and Treatment of Heavy Metal Pollution, Central South University, Changsha 410083, China

Abstract:Arsenic (As) removal from smelting acidic wastewater is an urgent task. The most common method is oxidation of trivalent As(III) to pentavalent As(V) subsequently precipitated by ferric (Fe(III)) salts. Foundations of redox behavior and chemical species are of great importance for understanding As removal. In this work, cyclic voltammetry (CV) and UV-Vis spectroscopy were used for laboratory observation; meanwhile HSC and MINTEQ software were employed for theoretical analyses. It is found that As(III) oxidation, a multiple electron transfer reaction, is diffusion-controlled. The oxidation over-potential is very high (about 0.9 V) in sulfuric acid solutions (pH 1.0). In addition, Fe(III)-As(V) complexes are evidenced by UV-Vis spectra and chemical species analyses in series of Fe(III)-As(V)-H2SO4-H2O solutions. Therefore, the Fe(III) and As(V) species distribution against pH values are determined and a new φ-pH diagram with inclusion of Fe-As complexes is consequently compiled based on thermodynamic data predicted by other researchers.

 

Key words: arsenic; ferric-arsenic complexes; φ-pH diagram; chemical species; acidic wastewater

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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