Modeling of copper removal from electroplating industry wastewaters using zinc oxide nano adsorbent supported on graphene oxide

A new nano adsorbent was prepared using zinc oxide nanoparticles supported on graphene oxide to separate copper from electroplating industry wastewater. Graphene oxide was synthesized via Hummer's modified method, and its surface morphology was characterized through FTIR spectroscopy and scanning electron microscopy (SEM). A systematic study of the adsorption process was conducted, varying pH, initial copper concentration, contact time, adsorbent dosage, and temperature. The experimental results revealed that the maximum adsorption capacity, with 89.77% efficiency, was achieved at a pH of 7 when 0.5 g of adsorbent was in contact with a 200 mg/L copper solution at 20°C for 30 minutes. The nano adsorbent exhibited a high adsorption capacity in both simulated and real industrial wastewater samples, effectively removing up to 99% of copper from industrial samples. Adsorption isotherm, kinetic, and thermodynamic studies were performed to elucidate the adsorption mechanism. The adsorption process followed pseudo-second-order models and the Freundlich isotherm. Thermodynamic studies indicated that the adsorption of copper ions on ZnO/GO was a spontaneous and exothermic reaction with an enthalpy of -6361.21 J/mol. This study demonstrates that nano ZnO/GO can be utilized as an effective, low-cost, and environmentally friendly nano adsorbent for electroplating wastewater treatment.