Arsenopyrite weathering in acidic water: Humic acid affection and arsenic transformation
Arsenopyrite weathering in acidic water: Humic acid affection and arsenic transformation
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酸性水中毒砂风化：腐殖酸影响和砷转化
DOI：
10.1016/j.watres.2021.116917
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发表时间：
2021
期刊：
影响因子：
12.8
通讯作者：
Qingyou Liu
中科院分区：
文献类型：
--
作者：
Shuai Wang;Kai Zheng;Heping Li;Xiaonan Fen;Luying Wang;Qingyou Liu
毒砂是一种常见的金属硫化物矿物，在开阔的环境中很容易风化，释放出砷，污染周围环境。腐植酸(HA)广泛存在于土壤、沉积物和水体中，含有多种官能团，与砷、铁等金属离子形成络合物，影响毒砂的风化行为。由于砷、铁和腐植酸是氧化还原活性化合物，本论文采用极化曲线、电化学阻抗谱和循环伏安法等电化学技术，从根本上研究了毒砂在各种环境条件下的风化过程和机理。极化曲线表明，较高的HA浓度(0~10 0 0 mg·L−1)、较高的温度(5~35℃)或较高的酸度(pH 1.0~7.0)促进毒砂的风化，腐蚀电流密度(ICORR)、温度(T)与酸度(PH)之间存在线性关系：ICORR=-3691.2/T+0 13.942；腐植酸的活化能为24.1kJ·m ol−-1，表明在腐植酸存在下，毒砂易发生风化；交流阻抗谱测定表明，反应动力学受表面反应控制，双电层电阻减小。循环伏安和表面表征(红外光谱和X射线光电子能谱)表明，毒砂首先氧化成S0、As(III)和Fe2+，然后S0和Fe2+最终转化为SO42−和Fe3+，而As(III)氧化成As(V)。此外，羟基磷灰石的羧基(-COOH)和酚基(-OH)可通过配体交换机制与As(III)/(V)-HA和As(III)/(V)-Fe-HA形成络合物，阻碍FeAsO4的形成，降低As的生物有效性。这项研究的结果对于理解酸性条件下砷的去向和迁移是有价值的，并对受采矿活动影响的含砷场地的修复和管理具有重要意义。
Arsenopyrite is a common metal sulfide mineral and weathers readily in the open environment, releases As, and pollutes the surrounding environment. Humic acid (HA) is ubiquitous in soils, sediments and waters, and contains various functional groups and complex with arsenic, iron and other metal ions that affect the weathering behavior of arsenopyrite. Because As, iron, and HA are redox-active compounds, electrochemical techniques, including polarization curves, electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV), were used to fundamentally investigate the weathering process and mechanism of arsenopyrite over a wide range of environmental relevant conditions. Polarization curves showed higher HA concentrations (0-1000 mg•L−1), higher temperatures (5-35°C) or acidities (pH 1.0-7.0) promoted arsenopyrite weathering; there was a linear relationship between the corrosion current density (icorr), temperature (T) and acidity (pH):icorr= -3691.2/T+ 13.942 andicorr= -0.2445pH + 2.2125, respectively. Arsenopyrite weathering readily occurred in the presence of HA as confirmed by its activation energy of 24.1 kJ•mol−1, and EIS measurements confirmed that the kinetics were controlled by surface reaction as confirmed by decreased double layer resistance. CV and surface characterization (FTIR and XPS) showed that arsenopyrite initially oxidized to S0, As(III) and Fe2+, then S0and Fe2+were ultimately converted into SO42−and Fe3+, while As(III) oxidized to As(V). Furthermore, the carboxyl (–COOH) and phenolic (–OH) of HA could bind with As(III)/(V) and Fe3+via a ligand exchange mechanism forming As(III)/(V)-HA and As(III)/(V)-Fe-HA complexes that hinders the formation of FeAsO4and decreases the bioavailability of As. Findings gained from this study are valuable for the understanding of the fate and transport of As in acidic conditions, and have powerful implications for the remediation and management of As-bearing sites affected by mining activities.