【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6.07~13.15(mg.g-1),吸附量随着温度或Cd2+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。更多还原

【Abstract】 The adsorption of Cd2+ 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 Cd2+ was 6.07～13.15(mg·g-1) after 90 min under the experiment conditions,and this capacity was increased with the increasing temperature or Cd2+ 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(ΔH) and the entropy changes(ΔS) were positive,while the free energy changes(ΔG) were negative.更多还原