Synthesis of rare earth tailing-based geopolymer for efficiently immobilizing heavy metals. (10th September 2020)

• Record Type: Journal Article
• Authors: Hu, Sixian; Zhong, Lele; Yang, Xiaojun; Bai, Haoyu; Ren, Bo; Zhao, Yunliang; Zhang, Wei; Ju, Xing; Wen, Hanrui; Mao, Surong; Tao, Ran; Li, Cheng
• Is Part Of: Construction & building materials. Volume 254(2020)
• Publication Date: 2020-09-10
• Subjects: Geopolymer -- Rare earth tailings -- Heavy metals -- Immobilization; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2020.119273
• Languages: English
• ISSNs: 0950-0618

Abstract

Graphical abstract: Highlights: Successful synthesis of rare earth tailing-based geopolymer. The RET-geopolymer has high compressive strength. Over 95% immobilizing efficiency of heavy metals (Pb 2+ & Ba 2+ ). Pb 2+ /Ba 2+ participated in the polycondensation process to form fixed PbO/BaSiO3 . Abstract: Rare earth tailing (RET) is a specific tailing containing high content of heavy metals. In this work, RET-based geopolymer was successfully prepared, which not only possesses good mechanical performance but also can immobilize the heavy metals well. The compressive strength of the optimized RET-based geopolymer after 7 d can reach over 35 MPa. XRD results showed that the RET-based geopolymer had a typical broadening diffraction peak corresponding to the amorphous geopolymer structure, which was also supported by SEM micromorphology. The incorporated RET played a role similar to aggregate and has a reinforcement effect on the overall mechanical strength of RET-based geopolymer. The immobilizing mechanism of heavy metals in the RET-based geopolymer was investigated by XRD, FTIR, XPS, etc. The introduced heavy metal cations (Pb 2+ and Ba 2+ ) were immobilized in the geopolymer by combining with unbridged oxygen or with the Si/Al chain-like framework thereby generating corresponding new phase of PbO/BaSiO3 . This work provides a feasible strategy to utilize the RET solid waste through the preparation of geopolymer, which possesses extraordinary immobilizing ability on heavy metals and is conducive to the environmental-friendly waste management.