Design and synthesis of two novel carbon aerogels using citric and tartaric acids as catalysts for continuous water desalination

Abstract

This study aimed to find the best capacitive deionization (CD) carbon electrode without supercrit-ical drying by preparing two different types of carbon aerogels with citric (CA) and tartaric (CAS) acid catalysts. Both electrodes were prepared by the short sol–gel process through vacuum drying and pyrolysis with CO2 . The structure, pore size characterization, and electrosorption behavior of electrodes were characterized by scanning electron microscopy (SEM), N2 adsorption–desorption isotherms, and cyclic voltammetry (CV), respectively. SEM results showed highly porous, smooth, and homogeneous structures without any cracks in both aerogels; however, the two aerogels showed different pore structures. Analysis of the Brunauer–Emmett–Teller surface area also proved no difference between CA and CAS in specific surface area (819 and 636 m2 g–1, respectively). But the proportion of mesoporosity was higher in CD than CAS; so, CD outperformed CAS. CV also showed better capacitive behavior than CAS since CAS needed more potential. The performance of CD was considered in different concentrations of NaCl aqueous solutions (range: 200–1,000 mg L–1) and at various applied voltages (range: 0.8–2 V). Besides, results revealed that salt-adsorption for CA and CAS in optimum NaCl concentration of 250 mg L–1 and applied voltage of 2 V was 22.4 and 12.8 mg g–1, respectively.