Effect of surface modification of carbon felts on capacitive deionization for desalination

Abstract

Surface modified carbon felts were utilized as an electrode for the removal of inorganic ions from seawater. The surfaces of the carbon felts were chemically modified by alkaline and acidic solutions, respectively. The potassium hydroxide (KOH) modified carbon felt exhibited high Brunauer-Emmett-Teller (BET) surface areas and large pore volume, and oxygencontaining functional groups were increased during KOH chemical modification. However, the BET surface area significantly decreased by nitric acid (HNO 3 ) chemical modification due to severe chemical dissolution of the pore structure. The capability of electrosorption by an electrical double-layer and the efficiency of capacitive deionization (CDI) thus showed the greatest enhancement by chemical KOH modification due to the appropriate increase of carboxyl and hydroxyl functional groups and the enlargement of the specific surface area.

Charge and Potential Balancing for Optimized Capacitive Deionization Using Lignin‐Derived, Low‐Cost Activated Carbon Electrodes

“…Cyclic voltammograms were recorded at scan rates (n)o f5t o 500 mV s À1 within ap otential window of 0t o0 .6 V( vs. Ag/AgCl). The specific capacitance (C S [F g À1 ]) and the average capacitance (C CV [F g À1 ]) of the electrodes were calculated by using Equations (11) and (12):…”

“…[3,4] To achieve high-performance desalination, the CDI electrode material should present al arge pore volumea ccessible for ion electrosorption, high electrical conductivity,h ydrophilicity,a nd chemi-cal stability. [5] Usually,C DI electrodes are carbon-based materials, which have been exploredi nt he forms of carbonn anotubes, [6,7] mesoporousc arbon, [8][9][10] and microporous carbons such as carbon felts, [11] carbide-derived carbon, [12] and carbon beads. [13] Some of these materials are expensive, and their synthesis may involve environmentally unfriendly procedures;f or instance, the synthesis of carbide-derived carbons requires the use of halogens.…”

Carbon‐Based Capacitive Deionization Electrodes: Development Techniques and its Influence on Electrode Properties

“…A study by Lee et al . showed the effect of HNO 3 and KOH on the surface characteristics of carbon felt and its CDI performance [55] . An increase in C=O, C−O, and OH functionalities was observed for both chemical treatments.…”

Reciclagem de fibras de carbono oriundas de compósitos estruturais de matriz epóxi por processo térmico de pirólise e aplicação como materiais de eletrodo em supercapacitores

“…Nos espectros estão delimitadas apenas as regiões e os picos correspondentes aos modos vibracionais dos grupos funcionais mais relevantes que evidenciaram modificações superficiais com os tratamentos realizados. Comparando os espectros FTIR, observa-se que a FCP-TQ e FCP-Q apresentaram alterações de alguns modos vibracionais comparada com a FCP, destacando a atenuação do sinal observada na região de 3.630 a 2.984 cm -1 resultante dos modos de estiramento dos grupos OH e de 1.720 a 1.540 cm -1 atrelado as vibrações de estiramento de C=O de ésteres e ácidos carboxílicos para a FCP-TQ [19][20][21][22][23][24]. Por outro lado, um aumento do sinal no espectro correspondente a esses modos vibracionais foi observado para a FCP, cujo aumento se atribui à oxidação química devido a uma maior quantidade de grupos OH e C=O formados, com a incorporação de uma quantidade maior de grupos carboxílicos a superfície da FCP.…”