锂渣吸附酸性Cr^(6+)的温度效应及机理研究

Mechanism and Temperature Effects of Acidic Cr^(6+) Adsorption on Lithium Slag

研究了不同吸附温度下锂渣对酸性Cr6+的吸附性能、吸附过程的热力学和动力学行为,结合X荧光表征,阐明其吸附机理。结果表明,适当提高吸附温度有利于锂渣对Cr6+的吸附,随着吸附温度从20℃升至40℃时,Cr6+的吸附率增大,且符合Freundlich吸附等温模型,焓变(△H)和熵变(△S)为正值表明吸附过程为熵增的吸热过程,自由能变(△G)为负值说明该吸附过程为自发进行,吸附动力学符合准二级速率方程和外部液膜扩散方程。成分分析表明,锂渣中FeO的含量下降了0.2%,Cr3+和Cr6+的含量分别提高了0.2022%和0.0309%。说明锂渣对Cr6+的吸附包含了还原与吸附两个作用,锂渣中的FeO充当了还原剂,降低了Cr6+的浓度,随着锂渣的吸附作用,将Cr3+从水中去除。

Under different adsorption temperature,the effects of lithium-slag on adsorption performance of acidic Cr6 ＋ ,thermodynamics and dynamics in adsorption process were researched and the adsorption mechanism were clarified with X-ray fluorescence characterization.The result showed that appropriately in-creasing adsorption of lithrum-slag Cr6 ＋ .When adsorption temperature was increased from 20 ℃ to 40 ℃, Cr6 ＋ adsorption rate increased and met Freundlich isotherm models with adsorption temperature.The posi-tive value ofΔH andΔS showed that adsorption process was adsorption heat process of entropy.Negative value ofΔG indicated that the adsorption process was spontaneous,the adsorption kinetics met the pseudo-second-order rate equation and boyd diffusion equation.Component analysis showed that：lithium-slag con-tent of FeO reduced by 0.2%,Cr3 ＋ content increased by 0.2022%,Cr6 ＋ content increased by 0.0309%.The result revealed that lithium-slag adsorbs acidic Cr6 ＋ which contained the restore and the adsorption effect, its FeO is acted as a reducing agent that reduces the concentration of Cr6 ＋ ,along with the adsorption of lithium slag,the Cr3 ＋ was removed from the water.