氟化物
吸附
化学
无机化学
沸石
朗缪尔吸附模型
碳酸氢盐
氯化物
镧
核化学
催化作用
有机化学
作者
Renjie Yang,Jiabin Chen,Zhiyong Zhang,Deyi Wu
出处
期刊:Chemosphere
[Elsevier]
日期:2022-11-01
卷期号:307: 136063-136063
被引量:27
标识
DOI:10.1016/j.chemosphere.2022.136063
摘要
Defluoridation of water is still challenging due to the fluoride pollution of both groundwater and surface water worldwide. In this study, lanthanum-modified zeolite (LMZ) was synthesized from coal fly ash and was investigated for fluoride removal from water by conducting batch and column experiments. Our results indicated that the process of fluoride adsorption was endothermic and the adsorption kinetics on LMZ followed the pseudo-second-order model. A higher temperature increased both the capacity and the rate of adsorption. The maximum fluoride adsorption capacity of LMZ reached 141.5 mg/g with a F/La molar ratio of 4.21, as estimated from the Langmuir model which best fitted the isotherm data. Fluoride adsorption greatly depended on pH, with optimal performance being achieved within ∼5.0–∼7.0. The point of zero charge of LMZ was pH 8.8, at which only bicarbonate ions greatly affected fluoride removal. However, no competing effect was observed at pH 6.3 for all tested anions including chloride, sulphate, nitrate, bicarbonate and acetate. The dominant adsorption mechanism was the ligand exchange of fluoride with hydroxyls on LMZ, as illustrated by the rise in pH due to fluoride adsorption and by the molecular scale spectroscopic FTIR, Raman and XPS studies. Fluoride adsorbed on LMZ was successfully desorbed using NaOH solution, and regenerated LMZ could be reused. The results of column studies showed that LMZ granulated with alginate performed well in treating F−-containing water. In conclusion, LMZ is a promising material for efficient defluoridation from water.
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