颗粒改性活性氧化铝吸附除氟动力学和热力学的研究

通过对硫酸铁改性活性氧化铝颗粒（FMAA）吸附除氟的静态实验研究，得到其吸附动力学和吸附热力学描述，并进一步探讨了吸附机理和速率控制步骤。用拟一阶动力学模型、拟二阶动力学模型、Elovich模型、Boyd模型对吸附动力学实验数据进行拟合，发现所有动力学数据均符合拟二阶动力学模型，且Boyd模型拟合结果支持颗粒内扩散为动力学控制步骤的结论。采用Langmuir、Freundlich和Sips吸附等温线模型对数据进行拟合，结果显示吸附平衡数据与Sips模型相关性好，且Sips常数γ=0.712，说明FMAA上的氟离子是不均一的单层吸附。由范特霍夫方程求得吸附焓变ΔH⁰=30.39 kJ/mol，且动力学实验数据与Elovich方程相关性好，说明FMAA对氟离子的吸附主要为化学吸附。

Kinetics and thermodynamics of modified granular activated alumina for fluoride removal

The kinetic and equilibrium data from batch experiments using ferric sulfate-modified granular activated alumina as an adsorbent for fluoride ions have been used to investigate the kinetic control step and adsorption mechanism. The kinetic data were fitted by pseudo-first-order, pseudo-second-order, Elovich and Boyd models. The results showed that the kinetic data were best fitted by the pseudo-second-order model, and the Boyd model showed that intraparticle diffusion is the kinetic control step. By fitting the equilibrium data with the Freundlich, Langmuir and Sips isotherm models, it was found that the Sips isotherm fitted the data best with a Sips constant γ=0.712, which indicated that the adsorption of fluoride on FMAA involves heterogeneous monolayer adsorption. A value of the adsorption enthalpy of ΔH⁰=30.4 kJ/mol was obtained by the Van der Hof equation, and the kinetic experimental data were in good agreement with the Elovich equation, which indicated that the adsorption of fluoride ion by FMAA occurs mainly by chemisorption.