pH对δ-MnO_(2)吸附硫酸锰溶液中Co^(2+)、Ni^(2+)的影响

Effect of pH on adsorption of Co^(2+) and Ni^(2+) by δ-MnO_(2) in manganese sulfate solution

硫酸锰溶液中重金属离子的深度净化,一直是锰行业研究的热点和重点。利用X射线衍射(XRD)、扫描电镜(SEM)和红外光谱(FT-IR)等手段对所制备的δ-MnO_(2)进行表征,利用Visual Minteq软件模拟硫酸锰溶液中Mn、Co和Ni的离子形态随pH的变化关系,研究不同pH条件对δ-MnO_(2)吸附硫酸锰溶液中Co^(2+)、Ni^(2+)的影响。结果表明:δ-MnO_(2)结晶性较差,缺陷和空隙较多,表面羟基丰富。随着硫酸锰溶液pH升高,δ-MnO_(2)对于Co^(2+)和Ni^(2+)吸附率逐渐增加,Co^(2+)比Ni^(2+)更容易被吸附。在低pH下,δ-MnO_(2)吸附效果受结构缺陷和空隙影响,pH高于5时,在表面负电荷和羟基的共同作用下大量吸附Co^(2+)和Ni^(2+),Co^(2+)、Ni^(2+)吸附率最高达到99.98%、89.53%。对吸附后δ-MnO_(2)进行XRD和FT-IR分析进一步验证了吸附机理,为解决锰系电池原材料硫酸锰溶液中重金属杂质离子难去除问题提供一定基础。

The deep purification of heavy metal ions in manganese sulfate solution has been a hot spot and focus of research in the manganese industry.In this paper, XRD,SEM and FT-IR were used to characterize prepared δ-MnO_(2).Visual Minteq software was applied to simulate the ionic forms of Mn, Co and Ni in manganese sulfate solution and then the effects of different pH on the adsorption of Co^(2+)and Ni^(2+)in manganese sulfate solution by δ-MnO_(2)were investigated.The results showed that δ-MnO_(2)had poor crystallinity, more defects and voids, but had rich surface hydroxyl groups.With the increase of pH of manganese sulfate solution, the adsorption rates of δ-MnO_(2)to Co^(2+)and Ni^(2+)gradually increased, and Co^(2+)was easier to be adsorbed than Ni^(2+).At low pH,the adsorption effect of δ-MnO_(2)was affected by structural defects and voids.When pH was higher than 5,a large amount of Co^(2+)and Ni^(2+)was adsorbed under the synergy of surface negative charge and hydroxyl, and the adsorption rates of Co^(2+)and Ni^(2+)reached up to 99.98% and 89.53%,respectively.XRD and FT-IR analysis of δ-MnO_(2)after adsorption further verified the adsorption mechanism, which provided a basis for solving the difficult removal of heavy metal ions in manganese sulfate solution of raw material of manganese battery.