改性粉煤灰对糖蜜废水的吸附效果及机理

采用改性粉煤灰(MCFA)吸附糖蜜废水中的有机污染物,对吸附行为和机理进行了考察和分析。结果表明,MCFA投加量为30 g/L及pH为5.0的优化条件下,COD去除率为88.6%,饱和吸附量为89.7 mg COD/g MCFA。准二级方程能更好地描述糖蜜废水在MCFA上的吸附动力学。颗粒内扩散方程结果表明孔扩散并非唯一的速度控制步骤。吸附平衡表明,Freundlich等温线最符合吸附模式,为优惠吸附。D-R模式中的吸附自由能Ea值推断更可能是物理吸附而不是化学吸附。吸附热力学参数ΔG0(<0)、ΔH0(5.130 kJ/mol)和ΔS0(19.936 J/(mol.K))表明MCFA对糖蜜废水的吸附过程为可行的,自发性的吸热反应。

Adsorption effect and mechanisms of modified coal fly ash to molasses wastewater

This study investigates and analyzes the adsorption effect and mechanisms of molasses wastewater on modified coal fly ash(MCFA) for the removal of organic pollutants.The results showed that when the dose of MCFA was 30 g/L at pH of 5.0,88.6% of COD removal efficiency could be achieved with a sutured adsorption capacity of 89.7 mg COD/g MCFA.The kinetics of adsorption of molasses wastewater on MCFA was fit well to the pseudo-second order model.The intraparticle diffusion was identified not to be a sole rate limiting step.Freundlich gave a better fit to all adsorption isotherms with a favorable adsorption.The adsorption free energy by D-R model,Ea value,indicated that the adsorption process could be more likely to be a physical adsorption rather than a chemical one.The thermodynamic adsorption parameters,ΔH0(5.130 kJ/mol),ΔS0(19.936 J/(mol·K)) and the negative values of change in ΔG0 demonstrate the feasibility and spontaneous nature of the adsorptive treatment.