首页|Hydrothermal synthesis of zeolites-calcium silicate hydrate composite from coal fly ash with co-activation of Ca(OH)2-NaOH for aqueous heavy metals removal

Hydrothermal synthesis of zeolites-calcium silicate hydrate composite from coal fly ash with co-activation of Ca(OH)2-NaOH for aqueous heavy metals removal

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Coal fly ash is a 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 com-posite 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 concentra-tion of 0.5 mol/L,a hydrothermal temperature of 170℃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 transforma-tion of amorphous calcium silicate hydrate into crystallized tobermorite weakened the adsorption capac-ity of the composite.Besides,due to the competitive adsorption in a multiple ions solution,the adsorption capacities for these heavy metals had a reduction.

Coal fly ashAdsorption materialZeoliteCalcium silicate hydrateHeavy metals

Guanghui Li、Min Li、Xin Zhang、Pengxu Cao、Hao Jiang、Jun Luo、Tao Jiang

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School of Minerals Processing and Bioengineering,Central South University,Changsha 410083,China

National Natural Science Foun-dation of ChinaBasic Science Center Project for National Natural Science Foundation of ChinaPostdoctoral Science Foundation of ChinaScience and Technology Innovation Program of Hunan Pro-vince

52174273720881012021TQ03702021RC2003

2022

矿业科学技术学报(英文版)
中国矿业大学

矿业科学技术学报(英文版)

CSTPCDCSCDSCIEI
影响因子：1.222
ISSN：2095-2686
年,卷(期)：2022.32(3)
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