Operational Parameters, Kinetics and Energy Consumption of Chloride Removal by Graphene as a Capacitive Deionization Sorbent

Capacitive deionization (CDI), a novel and emerging technology provides a solution to the conventional difficulties linked to desalination. The optimum benefits can be harnessed from the technology if a proper electrode material is chosen and its influential parameters are enhanced. The primary objective of the work is to enhance the maximum chloride removal efficiency of graphene employed in flow-by CDI cells by varying flow rate, voltage, pH, electrode spacing, and electrolyte concentration. The secondary objective is to assess the energy consumption and the rate-limiting period for optimal operational conditions. Results show that 95.8% of chloride can be effectively reduced by employing graphene as a CDI electrode. However, this removal efficiency was achieved by maintaining the applied voltage, flow rate, electrolytic concentration, pH, and electrode spacing at 2.36 V, 2 mg/L, 250 mg/L, 5.67, and 0.84 cm, respectively. Isotherm studies reveal that the electrosorption of chloride onto graphene follows the Freundlich isotherm. An increase in flow rate, voltage, duration, and electrode distance, proportionally increases the energy consumption, exclusive of an increase in electrolytic concentration.