Effect of the electronegativity on the electrosorption selectivity of anions during capacitive deionization

Recent advances in ion selectivity with capacitive deionization

“…129,130 Akin to the work of Yeo et al, Zuo et al investigated the viability of a resin to selectively remove sulfate from a mixture with chloride. 131 An experiment with the pristine high surface area carbon electrode demonstrated a higher selectivity towards chloride than sulfate (S i/j = 2.2), in agreement with the work of Sun et al 75 The authors were able to reverse the selectivity (SO 4 2À /Cl À of 2.4) by coating the activated carbon electrode with the selective resin. The resin-coated carbon was able to maintain the selectivity of 1.9 towards sulfate even upon increasing the chloride concentration by a factor of 100.…”

“…A possible explanation for such discrepancy can arise from the dependence of ion selectivity on the type and pore size of the electrode material and operational parameters such as cell voltage, time dependency, and initial feed ratio and concentration. 24,74 Since there was no selectivity value provided by the authors, we calculated the selectivity towards chloride based on the removal efficiencies (R, Table 1) ( Table 3 of Li et al); Sun et al 75 proposed another mechanism of ion adsorption in carbon electrodes based on electronegativity. Instead of ionic size, the authors proposed that ion selectivity was a result of the differences in the electronegativity of adsorbing ions.…”

Bromide and iodide selectivity in membrane capacitive deionisation, and its potential application to reduce the formation of disinfection by-products in water treatment

“…Our findings, however, contradict the result of the previous study on the effect of electronegativity in the CDI process wherein it was found that the anions with higher electronegativity were more selectively removed (Sun et al, 2017). However, a closer 15 look at their experimental methodology revealed that the concentration of different anions was fixed on mass-based instead of molar concentration.…”

Grafting the Charged Functional Groups on Carbon Nanotubes for Improving the Efficiency and Stability of Capacitive Deionization Process

“…As a novel desalination technology, capacitive deionization (CDI) has attracted much consideration because of its outstanding features, such as low external power supply, high energy efficiency, and high ion removal rate. , Typically, the working principle of CDI is similar to that of a capacitor, in which the feed solution is circulated in a channel being in contact with two parallel fixed CDI electrodes. When an external voltage (e.g., 1.2 V) is applied across the CDI cell, charged ions in the feed solution are adsorbed and held on the surface or into the pores of the electrodes via the formation of the electrical double layers (EDL) at the electrode/solution interface and the adsorbed ions can be released back to the bulk stream once the electrodes are shorted or open. , Owing to this reversible adsorption/desorption process, CDI technology is recognized as a promising desalination technology for fresh water.…”

“…When an external voltage (e.g., 1.2 V) is applied across the CDI cell, charged ions in the feed solution are adsorbed and held on the surface or into the pores of the electrodes via the formation of the electrical double layers (EDL) at the electrode/solution interface and the adsorbed ions can be released back to the bulk stream once the electrodes are shorted or open. 3,4 Owing to this reversible adsorption/desorption process, CDI technology is recognized as a promising desalination technology for fresh water.…”