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

Authors
  • Park, Ilhwan1
  • Tabelin, Carlito Baltazar2
  • Magaribuchi, Kagehiro3
  • Seno, Kensuke3
  • Ito, Mayumi2
  • Hiroyoshi, Naoki2
  • 1 Laboratory of Mineral Processing and Resources Recycling, Division of Sustainable Resources Engineering, Graduate School of Engineering, Hokkaido University, Japan. Electronic address: [email protected] , (Japan)
  • 2 Laboratory of Mineral Processing and Resources Recycling, Division of Sustainable Resources Engineering, Faculty of Engineering, Hokkaido University, Japan. , (Japan)
  • 3 Laboratory of Mineral Processing and Resources Recycling, Division of Sustainable Resources Engineering, Graduate School of Engineering, Hokkaido University, Japan. , (Japan)
Type
Published Article
Journal
Journal of hazardous materials
Publication Date
Feb 15, 2018
Volume
344
Pages
322–332
Identifiers
DOI: 10.1016/j.jhazmat.2017.10.025
PMID: 29080485
Source
Medline
Keywords
License
Unknown

Abstract

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) tris-catecholate 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 (β-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.

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