石墨烯
渗透
膜
选择性
材料科学
氧化物
无机化学
锂(药物)
萃取(化学)
水溶液
聚苯乙烯磺酸盐
磺酸盐
盐(化学)
化学工程
纳米技术
钠
化学
色谱法
聚合物
有机化学
工程类
医学
内分泌学
催化作用
佩多:嘘
生物化学
作者
Su Liu,Xin Tong,Lei Huang,Chengchao Xiao,Kaihang Zhang,Yongsheng Chen,John C. Crittenden
标识
DOI:10.1016/j.memsci.2023.121448
摘要
Lithium-ion extraction and recovery from unconventional aqueous sources by utilizing membranes as a separation barrier are potential technologies to address the challenge of increased lithium demand. Separating lithium from other competing metal ions is challenging due to their low selectivity when using conventional membranes as selective barriers. Graphene oxide (GO) nanofluidic membranes possess a higher monovalent ion permeation rate than multivalent ions, however, the selectivity of lithium over other monovalent ions is low. In this study, we created freestanding GO-based membranes with enhanced Li+/monovalent ions selectivity to concentrate and recover lithium from aqueous solutions containing competing monovalent ions (e.g., K+ and Na+). Specifically, sulfonate groups are introduced into the membrane matrices by intercalating the spacing agent, polystyrene sulfonate (PSS), into the adjacent GO nanosheets. Additionally, neutral and positively charged spacing agents are also used for comparison, and to further investigate the transport mechanisms. The Li+ permeation rate of GOM-S (PSS-incorporated GO membrane) is higher than the other GO-based membranes in a single salt solution. In a mixed salt solution, the Li+/K+ selectivity of GOM-S depends on concentration and we observed the highest value, 3.43, when using 0.5 M LiCl and 0.5 M KCl as the feed (high) concentrations and 0.001 M LiCl and 0.001 M KCl as permeate (low) concentrations. We observed that as permeate concentration decreased the selectivity increased and the pH values from 3 to 10 did not change the selectivity. DFT calculations show that the Li–SO3H pair has smaller binding energy, facilitating lithium-ion transport along the membrane nanochannel. Also, the solution concentration is crucial to the competitive mixed ionic transport, which results from the preferential surface transport induced by the electrical double layer (EDL) extension within the confined membrane nanochannels.
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