Highly efficient defluoridation using a porous MWCNT@NiMn-LDH composites based on ion transport of EDL coupled with ligand exchange mechanism
Highly efficient defluoridation using a porous MWCNT@NiMn-LDH composites based on ion transport of EDL coupled with ligand exchange mechanism
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基于EDL离子传输与配体交换机制的多孔MWCNT@NiMn-LDH复合材料的高效除氟
DOI：
10.1016/j.seppur.2019.04.052
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发表时间：
2019-09
影响因子：
8.6
通讯作者：
Guan Guoqing
中科院分区：
文献类型：
--
作者：
Yang Yanyan;Du Xiao;Abudula Abuliti;Zhang Zhonglin;Ma Xuli;Tang Keyong;Hao Xiaogang;Guan Guoqing
由于目前使用的大多数氟化物吸附剂吸附容量低且再生困难，水除氟仍然是一个挑战。在此，通过单极脉冲电沉积（UPED）方法成功在电极上制备了涂覆导电多壁碳纳米管（MWCNT）的NiMn层状双氢氧化物（NiMn-LDH）纳米片，以实现高效的水除氟。研究发现，具有大表面积的NiMn-LDH纳米片可以均匀地接枝在导电MWCNT的骨架上，以促进电子传输。与离子交换（IX）过程相比，通过调节复合材料双电层（EDL）上的正电荷和负电荷，并在电化学氧化还原过程中与NiMn-LDH活性位点的配体交换相结合，实现了更快、更有效的可逆吸收/释放氟离子（F−）。特别是，在较宽的pH范围内（4-10），电活性MWCNT@NiMn-LDH可以有效去除F−。此外，MWCNTs@NiMn-LDH对F的吸附遵循伪二阶模型，根据Langmuir模型，F的最大吸附量为135.1mg/g。经过5次吸收/释放循环后，离子交换量仍保持其初始值的92.4%。此外，通过XPS分析验证了MWCNTs@NiMn-LDH中EDL离子传输与配体交换机制的耦合。连续的F−分离运行表明，MWCNTs@NiMn-LDH 的F−通量是仅MWCNTs 的两倍，而浓度达到甚至低于WHO 标准的时间是仅MWCNTs 的四分之一。结论是，MWCNTs@NiMn-LDH是一种有前途的电活性除氟材料，特别是将其结合在电化学开关离子选择性渗透（ESIP）系统中可以实现连续的F−分离。
Water defluoridation still remains challenge since most of currently applied fluoride adsorbents always have low adsorption capacity with difficulty in regeneration. Herein, NiMn-layered double hydroxide (NiMn-LDH) nanosheets coated conductive multiwalled carbon nanotubes (MWCNTs) were successfully fabricated on the electrode via a unipolar pulse electrodeposition (UPED) method for efficient water defluoridation. It is found that the NiMn-LDH nanosheets with large surface areas can be grafted uniformly on the skeleton of conductive MWCNTs to facilitate the electron transport. Compared to ion exchange (IX) process, faster and more efficient reversible uptake/release of fluoride ions (F−) was realized by modulating the positive and negative charges on the electrical double layer (EDL) of the composite, coupling with ligand exchange at the active sites of NiMn-LDH during the electrochemical redox process. Especially, in a broad pH range (4–10), the electroactive MWCNTs@NiMn-LDH can remove F−effectively. Moreover, the F−adsorption onto MWCNTs@NiMn-LDH followed the pseudo-second-order model, with the maximum F−adsorption quantity of 135.1 mg/g from the Langmuir model. After 5 uptake/release cycles, ion exchange quantity still retained 92.4% of its initial value. Furthermore, the EDL ion transport coupled with ligand exchange mechanism in MWCNTs@NiMn-LDH was verified by XPS analysis. The continuous F−separation runs implied that the flux of F−by MWCNTs@NiMn-LDH was twice over that of by MWCNTs only while the time of the concentration reached even below WHO standard was quarter of that of by MWCNTs only. It is concluded that the MWCNTs@NiMn-LDH is a promising electroactive material for defluoridation, especially combining it in electrochemically switched ion permselective (ESIP) system can realize a continuous F−separation.
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影响因子：
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作者：
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影响因子：
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