In Situ Electrochemical Dilatometry of Phosphate Anion Electrosorption
In Situ Electrochemical Dilatometry of Phosphate Anion Electrosorption
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DOI：
10.1021/acs.estlett.8b00542
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发表时间：
2018-12-01
影响因子：
10.9
通讯作者：
Hatzell, Marta C.
中科院分区：
文献类型：
--
作者：
Moreno, Daniel;Bootwala, Yousuf;Hatzell, Marta C.
在这里，我们通过电化学脱盐和膨胀法实验研究了一价和二价磷酸阴离子的竞争电吸附。通过原位膨胀法，我们监测了电极表面的应变，因为阴离子和阳离子被电吸附。应变测量表明，在阳离子(Na+)电吸附过程中，二价离子的存在促进了比预期更大的电极膨胀。用Na+观察到的膨胀等于用HPO42-观察到的膨胀。由于Na+的离子半径小于HPO42-的离子半径，对称膨胀表明二价阴离子在电极再生过程中不会完全解吸，导致共离子排出过程中与阳离子发生不利的相互作用。这导致了脱盐性能的下降，表现为盐吸附能力的下降。相反，一价磷酸阴离子(H_2PO_4-)在阴阳离子电吸附过程中发生了预期的不对称膨胀，表明一价离子可以被电极表面的阳离子有效地取代。
Here we investigate the competitive electrosorption of mono- and divalent phosphate anions through electrochemical desalination- and dilatometry-based experiments. Through in situ dilatometry, we monitor the strain at the electrode surface as anions and cations are electrosorbed. Strain measurements show that the presence of divalent ions promotes a greater than anticipated electrode expansion during cation (Na+) electrosorption. The expansion observed with Na+ equaled the expansion observed with HPO42-. Because the ionic radius of Na+ is smaller than that of HPO42-, the symmetric expansion suggests that divalent anions do not completely desorb during electrode regeneration, causing the adverse interactions with the cation during co-ion expulsion. This results in a decrease in desalination performance, indicated by a decreased salt adsorption capacity. Conversely, an expected asymmetric expansion during anion and cation electrosorption occurs with monovalent phosphate anions (H2PO4-), indicating that monovalent ions can be effectively replaced by the cation at the electrode surface.