High-efficiency and low-carbon remediation of zinc contaminated sludge by magnesium oxysulfate cement

Binglin Guo; Yongshan Tan; Lei Wang; Liang Chen; Zuliang Wu; Keiko Sasaki; Viktor Mechtcherine; Daniel C W Tsang

doi:10.1016/j.jhazmat.2020.124486

High-efficiency and low-carbon remediation of zinc contaminated sludge by magnesium oxysulfate cement

J Hazard Mater. 2021 Apr 15:408:124486. doi: 10.1016/j.jhazmat.2020.124486. Epub 2020 Nov 5.

Authors

Binglin Guo¹, Yongshan Tan², Lei Wang³, Liang Chen⁴, Zuliang Wu⁵, Keiko Sasaki¹, Viktor Mechtcherine⁶, Daniel C W Tsang⁴

Affiliations

¹ Department of Earth Resources Engineering, Kyushu University, Fukuoka 819-0395, Japan.
² College of Civil Science and Engineering, Yangzhou University, Yangzhou 225127, China.
³ Institute of Construction Materials, Technische Universität Dresden, 01062 Dresden, Germany. Electronic address: lei.wang1@mailbox.tu-dresden.de.
⁴ Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
⁵ School of Environmental and Safety Engineering, Changzhou University, Jiangsu 213164, China.
⁶ Institute of Construction Materials, Technische Universität Dresden, 01062 Dresden, Germany.

PMID: 33243654
DOI: 10.1016/j.jhazmat.2020.124486

Abstract

Electroplating sludge is classified as a hazardous waste due to its extremely high leachability of potentially toxic elements. This study concerns the use of magnesium oxysulfate cement (MOSC) for the stabilisation/solidification (S/S) of Zn-rich electroplating sludge. According to X-ray diffraction and thermogravimetric analyses, Zn was mainly immobilised through both chemical interaction and physical encapsulation in the MOSC hydrates of 5Mg(OH)₂·MgSO₄.7H₂O (5-1-7) phase. The crystal size analysis, elemental mapping, and extended X-ray absorption fine structure (EXAFS) analysis proved that the Zn²⁺ was also incorporated in the structure of 5-1-7 phase. Unlike Portland cement system, hydration kinetics, setting time, and compressive strength of the MOSC system were only negligibly modified by the presence of Zn, indicating its superior compatibility. Subsequent S/S experiments demonstrated that the MOSC binder exhibited an excellent performance on immobilisation efficiency of Zn (up to 99.9%), as well as satisfying the requirements of setting time and mechanical strength of sludge S/S products. Therefore, MOSC could be an effective and sustainable binder for the treatment of the Zn-rich industrial wastes.

Keywords: Electroplating sludge; Green and sustainable remediation; Hazardous waste immobilisation; Magnesium oxysulfate cement; Metal leachability; Stabilisation/solidification.

Publication types

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