Simultaneous suppression of acid mine drainage formation and arsenic release by Carrier-microencapsulation using aluminum-catecholate complexes
Simultaneous suppression of acid mine drainage formation and arsenic release by Carrier-microencapsulation using aluminum-catecholate complexes
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DOI：
10.1016/j.chemosphere.2018.04.088
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发表时间：
2018-08-01
期刊：
影响因子：
8.8
通讯作者：
Hiroyoshi, Naoki
中科院分区：
文献类型：
--
作者：
Park, Ilhwan;Tabelin, Carlito Baltazar;Hiroyoshi, Naoki
黄铁矿（FeS 2）是自然界中最常见的硫化物矿物，在矿山关闭和选矿作业后最严重的环境问题之一-酸性矿山废水（AMD）的形成中起着重要作用。同样，毒砂（FeAsS）是一种重要的硫化物矿物，因为它的溶解释放有毒的砷（As）到环境中。为了缓解黄铁矿和毒砂对环境造成的严重危害，本研究采用电化学技术和间歇浸出实验，结合表面敏感表征技术，研究了以邻苯二酚铝配合物为载体的微胶囊化技术（Carrier-Microencapsulation，CME），该技术可在硫化矿物表面选择性地形成保护膜。（单、双、三邻苯二酚）的氧化降解顺序为：[Al（cat）（3）]（3-）->[Al（cat）（2）]（-）->[Al（cat）]（-）-> Al ~（3+），且均为不可逆反应。在这三种配合物中，[Al（cat）]（+）对黄铁矿和毒砂氧化的抑制作用最强，因为它比其他两种配合物需要更少的步骤来完全分解。通过扫描电子显微镜结合能量色散X射线光谱（SEM-EDX）和漫反射红外傅里叶变换光谱（DRIFTS）对CME处理过的矿物进行分析表明，它们被羟基氧化铝（γ-AIO（OH））覆盖，在较高的[Al（cat）]（+）浓度下变得更加广泛。此外，该涂层即使在模拟表面氧化条件的相对高的施加电位下也是稳定的。在此基础上，提出了铝基CME的详细机理：（1）[Al（cat）]（+）在矿物表面的吸附，（2）[Al（cat）（+）的氧化分解和释放“游离”Al 3+，（3）沉淀和形成Al-羟基氧化物涂层。(C)2018爱思唯尔有限公司版权所有。
Pyrite (FeS2), the most common sulfide mineral in nature, plays an important role in the formation of acid mine drainage (AMD), one of the most serious environmental problems after the closure of mines and mineral processing operations. Likewise, arsenopyrite (FeAsS) is an important sulfide mineral because its dissolution releases toxic arsenic (As) into the environment. To mitigate the serious environmental problems caused by pyrite and arsenopyrite, this study investigated carrier-microencapsulation (CME) using Al-catecholate complexes, a technique that selectively forms protective coatings on the surfaces of sulfide minerals, by electrochemical techniques and batch leaching experiments coupled with surface sensitive characterization techniques.Cyclic voltammetry (CV) of Al-catecholate complexes (mono-, bis-, tris-catecholate) suggest that these three species could be oxidatively decomposed in this order: [Al(cat)(3)](3-)->[Al(cat)(2)](-)->[Al(cat)](-)-> Al3+, and these reactions were irreversible. Among these three species, [Al(cat)](+) was the most effective in suppressing pyrite and arsenopyrite oxidations because it requires less steps for complete decomposition than the other two complexes. Analyses of CME treated minerals by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) indicated that they were covered with Al-oxyhydroxide (gamma-AIO(OH)), which became more extensive at higher [Al(cat)](+) concentrations. In addition, this coating was stable even at relatively high applied potentials that simulated surface oxidizing conditions. Based on these results, a detailed mechanism of Al-based CME is proposed: (1) adsorption of [Al(cat)](+) on the surface of mineral, (2) oxidative decomposition of [Al(cat)(+) and release of "free" Al3+, and (3) precipitation and formation of Al-oxyhydroxide coating. (C) 2018 Elsevier Ltd. All rights reserved.