Evaluation of treatment and energy efficiencies of an advanced electrochemical system for Chlorella removal equipped with aluminum, graphite, and RGO nanoparticles-coated cathodes

Advanced material sciences and technologies can help to address environmental challenges in order to achieve sustainable development goals by developing innovative materials capable of mitigating energy consumption in treatment systems. In this study, an innovative electrocoagulation unit for algae removal was optimized, and the effects of various variables, including novel cathode materials (i.e., graphite and reduced graphene oxide nanoparticles), on treatment efficiency and energy consumption were evaluated. Reduced graphene oxide nanoparticles were synthesized and then immobilized on the graphite cathode surface with the modified Hummer's method. Stabilization of nanoparticles was achieved with polytetrafluoroethylene. The use of the reduced graphene oxide nanoparticles-coated cathode led to a significant decrease (42.93%) in energy consumption, compared to the case with an aluminum cathode. In the optimum conditions (a current density of 3 mA/cm², an electrolyte concentration of 2 g/L, an electrode surface area of 56 cm², a processing time of 60 min, and a sedimentation time of 30 min), the novel electrocoagulation unit, equipped with an aluminum anode and a reduced graphene oxide nanoparticles-coated cathode electrode, achieved removal efficiencies of 72.69% for Chlorella species and 72.96% for turbidity.