Heavy metal removal using nanoscale zero-valent iron (nZVI): Theory and application

Shaolin Li; Wei Wang; Feipeng Liang; Wei-Xian Zhang

doi:10.1016/j.jhazmat.2016.01.032

Heavy metal removal using nanoscale zero-valent iron (nZVI): Theory and application

J Hazard Mater. 2017 Jan 15;322(Pt A):163-171. doi: 10.1016/j.jhazmat.2016.01.032. Epub 2016 Jan 15.

Authors

Shaolin Li¹, Wei Wang², Feipeng Liang², Wei-Xian Zhang³

Affiliations

¹ State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai 200092, China. Electronic address: lishaolin@tongji.edu.cn.
² State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai 200092, China.
³ State Key Laboratory of Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Tongji University, Shanghai 200092, China. Electronic address: zhangwx@tongji.edu.cn.

PMID: 26861641
DOI: 10.1016/j.jhazmat.2016.01.032

Abstract

Treatment of wastewater containing heavy metals requires considerations on simultaneous removal of different ions, system reliability and quick separation of reaction products. In this work, we demonstrate that nanoscale zero-valent iron (nZVI) is an ideal reagent for removing heavy metals from wastewater. Batch experiments show that nZVI is able to perform simultaneous removal of different heavy metals and arsenic; reactive nZVI in uniform dispersion brings rapid changes in solution E_h, enabling a facile way for reaction regulation. Microscope characterizations and settling experiments suggest that nZVI serves as solid seeds that facilitate products separation. A treatment process consisting of E_h-controlled nZVI reaction, gravitational separation and nZVI recirculation is then demonstrated. Long-term (>12 months) operation shows that the process achieves >99.5% removal of As, Cu and a number of other toxic elements. The E_h-controlled reaction system sustains a highly-reducing condition in reactor and reduces nZVI dosage. The process produces effluent of stable quality that meets local discharge guidelines. The gravitational separator shows high efficacy of nZVI recovery and the recirculation improves nZVI material efficiency, resulting in extraordinarily high removal capacities ((245mg As+226 mg-Cu)/g-nZVI). The work provides proof that nanomaterials can offer truly green and cost-effective solutions for wastewater treatment.

Keywords: E(h)-controlled nZVI reactor; Heavy metal; Nanoscale zero-valent iron; Wastewater treatment; nZVI recirculation.