油页岩飞灰对重金属离子的吸附动力学及热力学

摘要

The kinetics and thermodynamics characteristics of Pb2+, Cu2+, Zn2+, Cd2+ adsorption onto fly ash from an oil shale-fired power plant was investigated using batch adsorption method. The results show that Freundlich equation is more applicable than Langmuir equation. The adsorption process was studied through fitting of the experimental data using the equation of Lagergren pseudo-first-order kinetics, the pseudo-second-order kinetics, the Elovich equation, and the intraparticle diffusion model. All the four equations were found applicable in initial stage of the adsorption. The absorption of Pb2+, Cu2+, Zn2+, Cd2+ on fly ash from oil shalefired CFB was in accordance of the pseudo-2nd-order reaction kinetics in the entire stage. The absorption characteristics of metal ions on oil shale fly ash is controlled by both film diffusion and particle diffusion.Thermodynamic analysis show that the processes of oil shale fly ash adsorbing Pb2+, Cu2+, Zn2+, Cd2+ are endothermic reaction.%采用批式振荡吸附法研究了燃油页岩电厂循环流化床锅炉飞灰对重金属离子Pb2+、Cu2+、Zn2+、Cd2+的吸附动力学及吸附热力学特性,并提出了吸附机理.结果表明,油页岩飞灰对Pb2+、Cu2+、Zn2+、Cd2+的吸附平衡数据符合Langmuir和Freundlich吸附等温方程,但Freundlich方程能够更好地描述吸附等温线.在油页岩飞灰对重金属离子吸附的初始阶段,拉格朗日准一级动力学方程、准二级动力学方程、Elovich方程、粒子内扩散模型均能很好地反映吸附模式,而整个吸附过程则遵循二级反应动力学方程,其吸附过程是液膜扩散和粒子内扩散共同作用的结果.油页岩飞灰对Pb2+、Cu2+、Zn2+、Cd2+的吸附是吸热反应.