MnO₂·0.5H₂O的固相法制备及其对Li⁺的吸附动力学

石西昌，张志兵，周喜诚，周定方，肖 湘，陈白珍

(中南大学 冶金科学与工程学院，长沙 410083)

摘 要：采用两步固相法制备锂离子筛MnO₂·0.5H₂O，采用X射线衍射仪和相关动力学模型研究MnO₂·0.5H₂O的结构及其吸附性能，探讨离子筛对盐湖卤水中各主要金属离子的分离特性及循环吸附性能。结果表明：溶液pH值的升高有利于离子筛对Li⁺的吸附，但在较强的碱性溶液中离子筛的溶损相应增加；吸附数据对伪二级动力学方程和Langmuir吸附等温方程拟合较好，相关系数分别达0.998和0.993以上；动边界模型中各控制步骤方程的线性拟合都不够理想；离子筛对Li⁺具有较好的选择性和较优的循环吸附性能。这表明：吸附过程为化学吸附过程，且为单层吸附；吸附过程是一个复杂过程，是多个控制步骤共同作用的结果。

关键词：锂离子筛；MnO₂·0.5H₂O；固相法；动力学；吸附

Synthesis of MnO₂·0.5H₂O by solid method and its adsorption dynamics for Li⁺

SHI Xi-chang, ZHANG Zhi-bing, ZHOU Xi-cheng, ZHOU Ding-fang, XIAO Xiang, CHEN Bai-zhen

(School of Metallurgical Science and Engineering, Central South University, Changsha 410083, China)

Abstract:The lithium ion-sieve MnO₂·0.5H₂O was prepared by two-step solid phase and its adsorption properties were investigated by XRD and all sorts of relevant dynamic models. The separation characteristics of the lithium ion-sieve for the main metal ions in Salt Lake and circulation adsorption performance were also studied. The results show that the rise of pH is in favour of the adsorption of lithium ion-sieve, but in strong alkali solution the dissolution loss of the lithium ion-sieve also increases accordingly. The adsorption data fit better for the pseudo-second-order rate equation and Langmuir adsorption isotherm equation, and the correlation coefficients reach above 0.998 and 0.993, respectively. The performance of dynamic boundary models is not satisfactory. The lithium ion-sieve has good selectivity for lithium and circulation adsorption performance is very good. This suggests that the adsorption process is chemical adsorption with a single layer and a complicated process with some control steps.

Key words:lithium ion-sieve; MnO₂·0.5H₂O; solid method; dynamics; adsorption