Suppression of the release of arsenic from arsenopyrite by carrier-microencapsulation using Ti-catechol complex

JOURNAL OF HAZARDOUS MATERIALS

卷:344

Article

Park, Ilhwan¹  Tabelin, Carlito Baltazar²  Magaribuchi, Kagehiro¹  Seno, Kensuke¹  Ito, Mayumi²  Hiroyoshi, Naoki² 

[1] Hokkaido Univ, Grad Sch Engn, Lab Mineral Proc & Resources Recycling, Div Sustainable Resources Engn, Sapporo, Hokkaido, Japan

[2] Hokkaido Univ, Fac Engn, Lab Mineral Proc & Resources Recycling, Div Sustainable Resources Engn, Sapporo, Hokkaido, Japan

关键词: Acid mine drainage;    Arsenic;    Arsenopyrite;    Microencapsulation;    Ti-catechol complex;   

DOI  :  10.1016/j.jhazmat.2017.10.025

来源: Elsevier

【 摘 要 】

Arsenopyrite is the most common arsenic-bearing sulfide mineral in nature, and its weathering contributes to acid mine drainage (AMD) formation and the release of toxic arsenic (As). To mitigate this problem, carrier-microencapsulation (CME) using titanium (Ti)-catechol complex (i.e., Ti-based CME) was investigated to passivate arsenopyrite by forming a protective coating. Ti4+ ion dissolved in sulfuric acid and catechol were used to successfully synthesize Ti(IV) triscatecholate complex, [Ti(Cat)(3)](2-), which was stable in the pH range of 5-12. Electrochemical studies on the redox properties of this complex indicate that its oxidative decomposition was a one-step, irreversible process. The leaching of As from arsenopyrite was suppressed by CME treatment using the synthesized Ti-catechol complex. Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) indicate that this suppression was primarily due to the formation of an anatase (beta-TiO2)-containing coating. Based on these results, a detailed 4-step mechanism to explain the decomposition of [Ti(Cat)(3)](2-) and formation of TiO2 coating in Ti-based CME is proposed: (1) adsorption, (2) partial oxidation-intermediate formation, (3) non electrochemical dissociation, and (4) hydrolysis-precipitation. (C) 2017 Elsevier B.V. All rights reserved.

【 授权许可】

Free