Unexpected Selective Absorption of Lithium in Thermally Reduced Graphene Oxide Membranes
Unexpected Selective Absorption of Lithium in Thermally Reduced Graphene Oxide Membranes
复制标题
热还原氧化石墨烯膜中锂的意外选择性吸收
DOI：
10.1088/0256-307x/38/11/116802
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发表时间：
2021-12-01
影响因子：
3.5
通讯作者：
Fang, Haiping
中科院分区：
文献类型：
--
作者：
Jiang, Jie;Mu, Liuhua;Fang, Haiping
锂在科学和工业过程中发挥着越来越重要的作用，从高Mg2+/Li+质量比盐水中提取锂或从废旧锂离子电池浸出液中回收锂极为重要。传统观点认为，低价态的Li+与石墨烯的吸附（和吸收能）比Mg2+等多价离子弱得多。在这里，我们展示了热还原氧化石墨烯 (rGO) 膜中 Li+ 相对于其他金属离子（如 Mg2+、Co2+、Mn2+、Ni2+ 或 Fe2+）的选择性吸附。有趣的是，Li+的吸附强度高达Mg2+吸附强度的5倍，并且Mg2+/Li+混合溶液的质量比高达500:1，仅在六个实验处理周期内就可以有效地降低至0.7:1，证明了rGO膜在Mg2+/Li+分离中的优异适用性。理论分析表明，这种意想不到的选择性归因于当水合阳离子进入 rGO 膜的有限空间时，阳离子 - π 相互作用和空间排斥之间的竞争。
Lithium plays an increasingly important role in scientific and industrial processes, and it is extremely important to extract lithium from a high Mg2+/Li+ mass ratio brine or to recover lithium from the leachate of spent lithium-ion batteries. Conventional wisdom shows that Li+ with low valence states has a much weaker adsorption (and absorption energy) with graphene than multivalent ions such as Mg2+. Here, we show the selective adsorption of Li+ in thermally reduced graphene oxide (rGO) membranes over other metal ions such as Mg2+, Co2+, Mn2+, Ni2+, or Fe2+. Interestingly, the adsorption strength of Li+ reaches up to 5 times the adsorption strength of Mg2+, and the mass ratio of a mixed Mg2+/Li+ solution at a very high value of 500 : 1 can be effectively reduced to 0.7 : 1 within only six experimental treatment cycles, demonstrating the excellent applicability of the rGO membranes in the Mg2+/Li+ separation. A theoretical analysis indicates that this unexpected selectivity is attributed to the competition between cation–π interaction and steric exclusion when hydrated cations enter the confined space of the rGO membranes.