摘要
采用高温煅烧的方法对镁铝水滑石进行改性,并以其为吸附剂,通过静态吸附实验考察其对Zn2+的吸附性能.实验结果表明,高温煅烧改性明显提高了镁铝水滑石对Zn2+的吸附性能,其提高程度取决于煅烧温度,在600℃煅烧的镁铝水滑石表现出最高的吸附容量.随着吸附时间、Zn2+初始浓度以及溶液pH的增加,所有镁铝水滑石对Zn2+的吸附容量均增加.当煅烧温度不高于200℃时,镁铝水滑石对Zn2+的吸附满足Langmuir等温吸附模型,当煅烧温度高于400℃时,镁铝水滑石对Zn2+的吸附满足Freundlich等温吸附模型.所有镁铝水滑石对Zn2+的吸附均满足伪二级动力学方程.Zn2+主要以Zn(OH)2沉淀形式沉积在镁铝水滑石的表面.
Abstract
The MgAl hydrotalcite was modified by high-temperature calcination to obtain the modified MgAl hydrotalcite adsorbent.The adsorption performance of MgAl hydrotalcite for Zn2+was investigated by static adsorption experiments.The experimental results showed that the adsorption capacity of MgAl hydrotalcite for Zn2+was obviously improved through high-temperature calcination mod-ification,and the improvement degree was dependent on the calcination temperature.The MgAl hydrotalcite calcined at 600℃showed the highest adsorption capacity.The adsorption capacity of all MgAl hydrotalcites increased with the increase of adsorption time,initial Zn2+concentration and pH of solution.The adsorption of MgAl hydrotalcites calcined at lower than 200 ℃ and higher than 400 ℃ for zinc would meet the Langmuir and Freundlich isothermal model,respectively.The adsorption of all MgAl hydrotal-cites for Zn2+satisfied the pseudo-second-order kinetic equation.Zn2+was mainly deposited on the surface of MgAl hydrotalcite as Zn(OH)2 precipitation.
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