Adsorption of Cd2+ and Ni2+ ions in coal fly ash
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摘要: 考察了粉煤灰对Cd2+和Ni2+的单组分吸附和双组分吸附性能。结果表明,粉煤灰可有效吸附水溶液中的Cd2+和Ni2+,去除率随pH升高而增加。吸附约60min后趋于平衡。粉煤灰对Ni2+的吸附容量高于Cd2+。单组分吸附平衡符合Freundlich模型和RedlichPeterson (RP)模型。双组分吸附时,Ni2+和Cd2+之间存在明显的竞争吸附效应;随干扰离子浓度升高,竞争吸附效应增强。不同模型拟合结果表明,双组分吸附平衡符合Freundlich竞争吸附模型。脱附实验表明,Cd2+比Ni2+易于脱附;0.1mol/L HCl、0.1mol/L HNO3 和0.05mol/L H2SO4的脱附效果接近,对Cd2+脱附率>60%,对Ni2+脱附率>35%。Abstract: The single-component and bi-component adsorption properties of Cd2+ and Ni2+ ions in coal fly ash particles were investigated. The results showed that coal fly ash was very effective for the removal of Cd2+ and Ni2+ ions from aqueous solutions; the removal percent of metal ions increases with the solution pH value. The adsorption equilibrium is achieved in about 60min; the adsorption capacity of Ni2+ is higher than that of Cd2+. The single-component adsorption corresponds with the Freundlich and RedlichPeterson (RP) isotherms. A significant competitive adsorption effect was found between Cd2+ and Ni2+ ions in the bicomponent adsorption; this competitive effect increased with increasing the concentrations of interfering ions. Equilibrium isotherms for the bicomponent adsorption of Cd2+ and Ni2+ ions have been analyzed by different isotherm models, which suggested that the bicomponent adsorption equilibrium data can be fitted well by the Freundlich competitive adsorption model. The results of desorption tests revealed that Cd2+ desorption from ash was easier than Ni2+ desorption. The solutions of 0.1mol/L HCl, 0.1mol/L HNO3 and 0.05mol/L H2SO4 exhibit similar efficiencies for the desorption Cd2+ and Ni2+ from ash; the desorption rates are > 60% for Cd2+ and > 35% for Ni2+.
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Key words:
- coal fly ash /
- Cd2+ /
- Ni2+ ions /
- single-component /
- bi-component /
- competitive adsorption effect
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