海泡石黏土矿物对Cu2+的吸附动力学研究

研究分析了海泡石黏土矿物对铜离子的吸附性能和动力学特征,结果表明,海泡石黏土矿物对Cu~(2 )吸附的最佳pH值为6.0左右,随着pH值的增大,吸附作用减弱;在Cu~(2 )]=100mg·l~(-1),溶液pH值为6,吸附时间为2h时,添加0.1 g海泡石,海泡石对Cu~(2 )的吸附去除率仅为39.5%,当海泡石用量提高至0.4 g时,其对Cu~(2 )的吸附去除率提高到94.8%;实验结果同样显示,18min内有90%的Cu~(2 )被海泡石吸附,随着吸附时间的增加,吸附作用趋于稳定,2h可达到吸附平衡。该吸附过程符合Langmuir和Freundlich等温吸附方程.同时,分别采用拟一级模型和拟二级模型考察了吸附动力学,并计算了这些动力学模型的速率常数.实验数据和拟二级模型计算结果之间有较好的相关性.

KINETIC OF THE ADSORPTION OF COPPER FROM AQUEOUS SOLUTION BY NATURAL SEPIOLITE

In this study,removal of copper(Cu~(2 ))from aqueous solutions is investigated using natural sepiolite. During the removal process,batch technique is used,and the effects of pH,clay amount,heavy metal con- centration and agitation time on adsorption efficiency are studied.Results of equilibrium experiments showed that the solution pH was the key parameter affecting the adsorption characteristics.The adsorption of Cu~(2 )ions onto natural sepiolite occurs up to the precipitation pH,and then the precipitation of Cu ions starts.Increasing pH,clay amount,initial metal ion concentration increased the sorption capacity of the adsorbent.Langmuir and Freundlich adsorption isotherms are applied in order to determine the efficiency of natural sepiolite used as an adsorbent.The kinetics of the adsorption of Cu~(2 )by natural sepiolite was also studied.Results of kinetic experiments showed that the Cu~(2 )adsorption rate was fast and more than 90% of Cu~(2 )adsorption occurred within 18 min.It is determined that adsorption of Cu~(2 )is well-fitted by the second order reaction kinetic.In addition,calculated and experimental heavy metal amounts adsorbed by the unit clay mass are too close to each other.It is concluded that natural sepiolite can be used as an effective adsorbent for removing Cu~(2 )from aqueous solutions.