Enhanced pyrite passivation by carrier-microencapsulation using Fe-catechol and Ti-catechol complexes

Xinlong Li; Ilhwan Park; Carlito Baltazar Tabelin; Kosuke Naruwa; Taiki Goda; Chie Harada; Sanghee Jeon; Mayumi Ito; Naoki Hiroyoshi

doi:10.1016/j.jhazmat.2021.126089

Enhanced pyrite passivation by carrier-microencapsulation using Fe-catechol and Ti-catechol complexes

J Hazard Mater. 2021 Aug 15:416:126089. doi: 10.1016/j.jhazmat.2021.126089. Epub 2021 May 14.

Authors

Xinlong Li¹, Ilhwan Park², Carlito Baltazar Tabelin³, Kosuke Naruwa⁴, Taiki Goda⁴, Chie Harada⁴, Sanghee Jeon⁵, Mayumi Ito⁵, Naoki Hiroyoshi⁵

Affiliations

¹ Division of Sustainable Resources Engineering, Graduate School of Engineering, Hokkaido University, Japan. Electronic address: rikinryu@gmail.com.
² Division of Sustainable Resources Engineering, Faculty of Engineering, Hokkaido University, Japan. Electronic address: i-park@eng.hokudai.ac.jp.
³ School of Minerals and Energy Resources Engineering, The University of New South Wales, Sydney, NSW 2052, Australia.
⁴ Division of Sustainable Resources Engineering, Graduate School of Engineering, Hokkaido University, Japan.
⁵ Division of Sustainable Resources Engineering, Faculty of Engineering, Hokkaido University, Japan.

PMID: 34492902
DOI: 10.1016/j.jhazmat.2021.126089

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 Fe₂TiO₅.

Keywords: Acid mine drainage; Carrier-microencapsulation; Fe-catecholate complex; Pyrite; Ti-catecholate complex.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Catechols
Iron*
Sulfides
Titanium*

Substances

Catechols
Sulfides
pyrite
Titanium
Iron