1. Enhanced pyrite passivation by carrier-microencapsulation using Fe-catechol and Ti-catechol complexes.
- Author
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Li, Xinlong, Park, Ilhwan, Tabelin, Carlito Baltazar, Naruwa, Kosuke, Goda, Taiki, Harada, Chie, Jeon, Sanghee, Ito, Mayumi, and Hiroyoshi, Naoki
- Subjects
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CATECHOL , *ACID mine drainage , *PYRITES , *SULFIDE minerals , *PASSIVATION , *MICROENCAPSULATION , *CYCLIC voltammetry , *IMPEDANCE spectroscopy - Abstract
Acid mine drainage (AMD) formation is mainly caused by the oxidation of pyrite. Carrier-microencapsulation (CME) using metal-catecholate complexes has been proposed to passivate sulfide minerals by forming surface-protective coatings on their surfaces. Among the various metal-catecholate complexes, Ti-catecholate formed stable coatings having superior acid-resistance, but a thick enough passivating film required considerable time (ca. 14 days) to grow. Meanwhile, Fe-catecholates can form Fe-oxyhydroxide coatings within 2 days, however, they are less stable than Ti-based coating. To address these drawbacks of using a single metal-complex, this study investigated the concurrent use of Fe-catechol and Ti-catechol complexes for accelerating the formation of stable passivating coating on pyrite. Compared with a single metal-complex system, the coating formation was significantly accelerated in mixed system. Linear sweep voltammetry showed the simultaneous decomposition of [Fe(cat)]+ and [Ti(cat) 3 ]2– as the main reason for improved coating formation. Electrochemical properties of coatings formed by single and mixed complex systems, confirmed by electrochemical impedance spectroscopy and cyclic voltammetry, indicated the coating formed in the mixed system had higher resistance and more electrochemically inert than the other cases. The simultaneous use of Fe-catechol and Ti-catechol complexes enhanced pyrite passivation by accelerating metal-complex decomposition and forming more stable coating composed of Fe 2 TiO 5. [Display omitted] • Pyrite passivation was investigated by CME using Fe- and Ti-catechol complexes. • When both complexes coexisted, their oxidative decompositions were accelerated. • CME using Fe-Ti-catechol complexes formed Fe 2 TiO 5 on pyrite surface. • Fe 2 TiO 5 had a higher resistance and more electrochemically inert than FeOOH. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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