Stabilization of iron-arsenic deposits by encapsulation with montmorillonite inorganic gels

Yan, Jingmin; Wang, Yongliang; Wang, Yanhua; Liu, Xiang; Ye, Shufeng

doi:.0..

DOI: https://doi.org/10.4491/eer.2020.671

Stabilization of iron-arsenic deposits by encapsulation with montmorillonite inorganic gels

Jingmin Yan^1,2, Yongliang Wang^1,3, Yanhua Wang^1,2, Xiang Liu^1,2, and Shufeng Ye^1,3^†

¹tate Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
²School of Chemistry and Chemical Engineering of University of Chinese Academy of Sciences, Beijing 100049, China
³Innovation Academy for Green Manufacture, Chinese Academy of Sciences, Beijing 100190, China

Corresponding Author: Shufeng Ye ,Tel: +13911828468, Fax: +86-10-62588029, Email: sfye@ipe.ac.cn

Received: December 2, 2020; Accepted: January 18, 2020.

ABSTRACT

Encapsulation is recognized as an effective technique for enhancing the stability of hazardous waste by coating it with an inert material. In this work, an eco-friendly montmorillonite (Mt) inorganic gel with the characteristics of high viscosity, adsorption and easy preparation was developed and coated on the surface of iron-arsenic deposits (IAD) to restrain the release of arsenic (As). The encapsulation system investigated involves Mt/IAD mass ratio and aging temperature of the coated iron-arsenic deposits (C-IAD). The C-IAD was characterized by XRF, XRD, SEM-EDS, TEM, FTIR and BET. The results revealed that the IAD was completely encapsulated by the montmorillonite inorganic gel. From the experiment of stability, when IAD was coated with montmorillonite inorganic gel (Mt/IAD mass ratio 0.75) and aged at 25℃, As release decreased from 3.15 mg/L to 0.64 mg/L at pH 5 after 24 h, and then dropped to 0.11 mg/L after 7 d. Furthermore, the results indicated that the IAD encapsulated with montmorillonite inorganic gel was eﬀective in suppressing the release of As under both weakly acidic and alkaline conditions.