Enhanced desalination of produced water using graphene oxide-coated activated carbon cloth via capacitive deionization

Abstract

The oil and gas industries produce a large volume of water, representing a challenge in treating this byproduct. This study used graphene oxide to coat the activated carbon cloth electrodes, which were later used for synthetic-produced water and real-produced water desalination through capacitive deionization (CDI). Adding graphene oxide to the activated carbon cloth (GO-ACC) increases mesopores volume, enabling good hydrophilicity to allow fast ion migration, resulting in efficient solution/pore contact and a high adsorption capability. Activated carbon cloth was coated with various graphene oxide concentrations using simple dip-and-dry method, and the obtained electrodes were characterized morphologically and electrochemically. As such, GO-ACC electrodes offer a high specific capacitance of 130.2 F/g at 1 mV/s, enhancing electrical conductivity by observing the lower internal resistance and charge transfer resistance from the electrochemical study. The salt removal efficiency and salt adsorption capacity using 500 mg/L of synthetic-produced water and real-produced water were 41 % and 32 mg/g and 57 % and 52.58 mg/g, respectively. For ion selectivity in real-produced water, the salt removal efficiency of the ions with high valence and low hydrated radius were higher (Ca²⁺ > Mg²⁺ > Cl⁻ > Na⁺). These values are significantly greater than most CDI technologies based on carbon materials. Undoubtedly, this well-developed GO-ACC offers an excellent material platform within the CDI system for effectively addressing produced water concerns.