Effect of Copper (II) Ions on the Removal of Antibiotics from Wastewater via Electrocoagulation

Antibiotic residues such as tetracycline (TC) and ofloxacin (OFL) are frequently found coexisting with copper (II) ions (Cu2⁺) in wastewater, forming stable metal-ligand complexes that hinder effective degradation and removal. This study examines the effect of varying Cu2⁺ concentrations on the efficiency of EC as a treatment method for removal of TC and OFL. Experiments were carried out in a batch electrochemical reactor with Al electrodes at initial pH5.5 and current densities of 12.6 A/m2 for TC and 13.5 A/m2 for OFL. Results obtained using ultraviolet-visible (UV-Vis) spectroscopy indicated that at TC/Cu molar ratio of 1.4298, TC removal reached a maximum of 88.3%, a 103.9% improvement from removal in the absence of Cu2⁺. Meanwhile, at OFL/Cu molar ratio of 1.7585, OFL removal reached a maximum of 75.3%, attaining a 20.5% increase from removal without Cu2⁺. The adsorption kinetics followed the pseudo-second-order model, suggesting that chemisorption was the primary removal mechanism. Scanning electron microscopy (SEM) and elemental analysis by Energy Dispersive X-ray Spectroscopy (EDX) revealed crystalline surface morphology on flocs with optimum Cu2⁺ concentration, characterized by slightly poorer adsorption but heightened retention. This work demonstrates that optimizing the molar ratio of pharmaceutical to Cu2⁺ in EC systems can significantly enhance pollutant removal efficiency while lowering operational costs by reducing energy, electricity, and electrode consumption.