Sustainable utilisation of waste carbon zinc battery derived carbon rods as cathodes in peroxicoagulation based wastewater treatment

The present study innovatively employs waste-derived carbon rods from used carbon-zinc batteries (CR-CZb) as an alternative cathode for the electrochemical treatment of wastewater. The acid modification of CR-CZb using HNO3 resulted in an enhancement of nitrogen content by 3% and introduced -C-OH- and -N=O- functional groups, which was verified by EDX and FTIR analysis. BET analysis indicated an improvement in the specific surface area to 8.923 m2/g for CR-CZb-HNO3 and revealed a pore size of 20.7 nm. XRD results confirmed the characteristics of graphitic carbon materials in CR-CZb-HNO3. LSV confirmed a peak current density of ∼8 mA/cm2 for CR-CZb-HNO3 compared to CR-CZb, which may improve the electroactivity for the two-electron ORR pathway. The experiments were systematically conducted in mixed dye wastewater by varying parameters, such as pH, current density and electrolysis duration. The optimal removal efficiencies achieved through the peroxicoagulation process for TN, COD and TOC removal were 76.36%, 94.32% and 90.23%, respectively, at a pH of 3, a current density of 30 mA/cm2 and an electrolysis time of 120 min. This study demonstrates that the waste carbon rods from used batteries can become a source of inexpensive electrodes that can degrade the pollutants.