摘要
通过静态实验探讨了天然凹凸棒石吸附水中镉Cd2+时的影响因素、动力学、等温式和热力学。结果表明,在实验条件下吸附90min后天然凹凸棒石对Cd2+的吸附量为6.07～13.15mg/g,吸附量随着温度或Cd2+的初始浓度的增加而增加,但天然凹凸棒石用量增加,吸附量却减少。在pH值为5～7时随着pH值的增加而增加。此外,天然凹凸棒石吸附Cd2+的速度较快,吸附60min后基本达到平衡。吸附动力学规律符合Lagergren准二级反应模型,不同温度下的吸附等温式都与Freundlich方程符合很好。热力学分析表明,吸附过程吸热,吸附焓变ΔH和熵变ΔS都为正值,吸附自由能变ΔG为负值。
The adsorption of Cd^2＋ in aqueous solutions by natural attapulgite was investigated through batch experiments, including the affecting factors, kinetics, isotherms and thermodynamics of the adsorption. The adsorption capacity of Cd^2＋ was 6.07-13.15mg/g after 90 min under the experiment conditions, and this capacity was increased with the increasing temperature or Cd^2＋ initial concentration, but decreased with the increasing amounts of natural attapulgite. Also, increasing pH would enhance the adsorption capacity when pH was between 5 and 7. The adsorption speed was rapid before 5 min, and the adsorption process approximately reached equilibrium in 60 min, and the adsorption kinetics followed pseudo-second order reaction models. Besides, the adsorption isotherms in different temperature in accordance with the Freundlich equation and thermodynamics evaluation showed that the adsorption process was endothermic. The enthalpy changes （△H） and the entropy changes （△S） were positive, while the free energy changes （△G） were negative.
出处
《水科学与工程技术》
2009年第2期30-32,共3页
Water Sciences and Engineering Technology
关键词
天然凹凸棒石
吸附
动力学
等温式
热力学
natural attapulgite
adsorption
kinetics
isotherm
thermodynamics
