期刊
INTERNATIONAL JOURNAL OF MINING SCIENCE AND TECHNOLOGY
卷 32, 期 3, 页码 563-573出版社
ELSEVIER
DOI: 10.1016/j.ijmst.2022.03.0012095-2686
关键词
Coal fly ash; Adsorption material; Zeolite; Calcium silicate hydrate; Heavy metals
资金
- National Natural Science Foun-dation of China [52174273]
- Basic Science Center Project for National Natural Science Foundation of China [72088101]
- Postdoctoral Science Foundation of China [2021TQ0370]
- Science and Technology Innovation Program of Hunan Pro-vince [2021RC2003]
By synthesizing a composite material of crystalline zeolites and amorphous calcium silicate hydrate directly from fly ash, superior adsorption properties for various heavy metals can be achieved. However, competitive adsorption in multi-ion solutions results in a reduction of adsorption capacity.
Coal fly ash isa typical secondary aluminum/silicon resource. The preparation of zeolite-type absorbent is a potential way for its value-added utilization, while the purity and adsorption property of zeolite are limited due to the occurrence of side reactions in the synthesis process. In this study, a designated composite consisted of crystalline zeolites and amorphous calcium silicate hydrate was selected, which was direct synthesized from fly ash under conditions of a Ca/Si molar ratio of 0.8, an initial NaOH concentration of 0.5 mol/L, a hydrothermal temperature of 170 celcius and a liquid-solid ratio of 15 mL/g. The results indicated that this composite had superior adsorption property for a variety of heavy metals, which was based on the exchange of calcium and sodium ions in zeolites and calcium silicate hydrate. Its adsorption capacities for Pb2+, Ni2+, Cd2+, Zn2+, Cu2+ and Cr3+ attained 409.4, 222.4, 147.5, 93.2, 101.1 and 157.0 mg/g, respectively, in single solution with a pH of 4.5. After regulating the synthesis conditions, the transformation of amorphous calcium silicate hydrate into crystallized tobermorite weakened the adsorption capacity of the composite. Besides, due to the competitive adsorption in a multiple ions solution, the adsorption capacities for these heavy metals had a reduction. (c) 2022 Published by Elsevier B.V. on behalf of China University of Mining & Technology. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
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