title: The mechanisms of heavy metal immobilization by cementitious material treatments and thermal treatments: A review.
abstract: Safe disposal of solid wastes containing heavy metals is a significant task for environment protection. Immobilization treatment is an effective technology to achieve this task. Cementitious material treatments and thermal treatments are two types of attractive immobilization treatments due to that the heavy metals could be encapsulated in their dense and durable wasteforms. This paper discusses the heavy metal immobilization mechanisms of these methods in detail. Physical encapsulation and chemical stabilization are two fundamental mechanisms that occur simultaneously during the immobilization processes. After immobilization treatments, the wasteforms build up a low permeable barrier for the contaminations. This reduces the exposed surface of wastes. Chemical stabilization occurs when the heavy metals transform into more stable and less soluble metal bearing phases. The heavy metal bearing phases in the wasteforms are also reviewed in this paper. If the heavy metals are incorporated into more stable and less soluble metal bearing phases, the potential hazards of heavy metals will be lower. Thus, converting heavy metals into more stable phases during immobilization processes should be a common way to enhance the immobilization effect of these immobilization methods.
authors.affiliation: Institute for Advanced Materials and Technology, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing 100083, PR China.
authors.forename: Bin
authors.initials: B
authors.lastname: Guo
authors.affiliation: Institute for Advanced Materials and Technology, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing 100083, PR China. Electronic address: liubo@ustb.edu.cn.
authors.forename: Bo
authors.initials: B
authors.lastname: Liu
authors.affiliation: Institute for Advanced Materials and Technology, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing 100083, PR China.
authors.forename: Jian
authors.initials: J
authors.lastname: Yang
authors.affiliation: Institute for Advanced Materials and Technology, University of Science and Technology Beijing, 30 Xueyuan Road, Haidian District, Beijing 100083, PR China.
authors.forename: Shengen
authors.initials: S
authors.lastname: Zhang
mesh_terms: D003247:Conservation of Natural Resources; D019216:Metals, Heavy; D062611:Solid Waste
chemical_list: D019216:Metals, Heavy; D062611:Solid Waste
keywords: Cement; Geopolymer; Heavy metal; Immobilization mechanism; Sintering; Vitrification