The role of cupric ions in the oxidative dissolution process of marmatite: A dependence on Cu2+ concentration

Xiaoyu Meng; Hongbo Zhao; Menglin Sun; Yisheng Zhang; Yanjun Zhang; Xin Lv; Hyunjung Kim; Mikhail Vainshtein; Shuai Wang; Guanzhou Qiu

doi:10.1016/j.scitotenv.2019.04.227

The role of cupric ions in the oxidative dissolution process of marmatite: A dependence on Cu²⁺ concentration

Sci Total Environ. 2019 Jul 20:675:213-223. doi: 10.1016/j.scitotenv.2019.04.227. Epub 2019 Apr 17.

Authors

Affiliations

¹ Central South University, Changsha, Hunan, China.
² Central South University, Changsha, Hunan, China; Key Lab of Biohydrometallurgy, Ministry of Education, Changsha, Hunan, China; State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization, Kunming University of Science and Technology, China. Electronic address: zhbalexander@csu.edu.cn.
³ Department of Mineral Resources and Energy Engineering, Chonbuk National University, Jeonju, Republic of Korea.
⁴ G.K. Skryabin Institute of Biochemistry and Physiology of Microorganisms RAS (IBPM RAS), Russia.
⁵ Central South University, Changsha, Hunan, China. Electronic address: wangshuai@csu.edu.cn.
⁶ Central South University, Changsha, Hunan, China; Key Lab of Biohydrometallurgy, Ministry of Education, Changsha, Hunan, China.

PMID: 31030129
DOI: 10.1016/j.scitotenv.2019.04.227

Abstract

Cupric ions (Cu²⁺) play an important role in the oxidative dissolution process of marmatite in an acidic environment. In this work, dissolution experiments and numerous analytical techniques were utilized to investigate the role of Cu²⁺ in the oxidative dissolution process of marmatite in sulfuric acid. The dissolution experiments showed that the role of Cu²⁺ is significantly dependent on its concentration. A low Cu²⁺ concentration (0.25-750 mg/L) can significantly accelerate marmatite dissolution, and a relatively high Cu²⁺ concentration (above 1000 mg/L) can hinder marmatite dissolution. Element analysis, synchrotron radiation-based X-ray diffraction (SR-XRD) and Raman spectra of the leaching residues proved that no copper containing mineralogical phase was produced by the reactions between Cu²⁺ and marmatite. The X-ray photoelectron spectroscopy (XPS) analysis indicated that Cu²⁺ was first adsorbed on the marmatite surface and then produced Cu-S surface species. An electrochemical measurement further indicated that the adsorption of Cu²⁺ can remarkably enhance the electrochemical reactivity of the marmatite surface, thus catalyzing the oxidative dissolution process. However, a high percentage of Cu²⁺ adsorption on the marmatite surface can produce a passivation layer when the Cu²⁺ concentration is high in the solution, which decreases the electrochemical reactivity, thus resulting in the hinderance of the oxidative dissolution process of marmatite.

Keywords: Catalytic mechanism; Cupric ions; Marmatite; Oxidative dissolution; Passivation.