层状复合金属氢氧化物对硫酸根离子等温吸附和动力学研究

通过共沉淀法制备了镁铝型层状复合金属氢氧化物和镁铝铁型层状复合金属氢氧化物及其焙烧产物(CLDH-Mg/Al和CLDH-Mg/Al/Fe),研究了其结构组成、等温吸附和动力学性质。结果表明:Fe3+的引入增加了表面正电荷,降低了层间间距,加快了层状复合金属氢氧化物初期吸附硫酸根的速度,但降低了达到吸附平衡时的吸附量。无论是镁铝型复合金属氢氧化物还是镁铝铁型复合金属氢氧化物,吸附过程均满足Langmuir吸附等温模型,Fe3+的引入使拟合的最大吸附量降低了19.7 mg/g左右。动力学均符合准二级动力学模型,Fe3+的引入降低了反应速率。

Research on isotherm adsorption and kinetics of layered compound hydroxides on sulfate ions

Mg/Al layered double hydroxides, Mg/Al/Fe layered compound hydroxides and their roasted prod- uct（CLDH-Mg/Al and CLDH-Mg/Al/Fe） were prepared using coprecipitation method, and then, the structural composition, isothermal adsorption and kinetics characteristics of them were studied. The results showed that： the introduction of Fe3＋ increased the positive charge on the CLDH-Mg/Al/Fe surface and decreased its interlayer spacing, which accelerated the speed of the layered compound hydroxides adsorbing sulfate ions at initial stage, however, decreased the adsorption quantity at the equilibrium state. It could be seen that, the adsorption processes of Mg/Al layered double hydroxides and Mg/Al/Fe layered compound hydroxides were both fit Langmuir adsorption isotherm model and the adsorption kinetics were consistent with pseudo-second-order. Besides, with the introduc- tion of Fe3＋, the maximum adsorption capacity was reduced by 19.7 mg/g and the reaction rate was also reduced.