Performance improvement of pyrolytic coke by surface modification for the adsorption of copper(ii) ions from wastewater

Abstract

In this study, KOH, an activating agent, was used to activate pyrolytic coke (PC). Further, Fe₃O₄ magnetic nanoparticles were used to modify the surface of the coke to serve as an adsorbent. Several analyses, such as FT-IR spectroscopy, XRD, XRF, VSM, Raman spectroscopy, SEM, EDS mapping, BET, TGA, and AFM, were used to study the structural and surface properties of the adsorbent. The BET analysis showed that the specific surface area of AC/Fe₃O₄ (73.35 m² g⁻¹) increased significantly compared to PC (6.90 m² g⁻¹). The maximum adsorption of copper (Cu) ions was found to be at an adsorbent dosage of 1 g L⁻¹, pH of 6, contact time of 90 min, initial concentration of 30 mg L⁻¹, and temperature of 55 °C, and the adsorption efficiency was calculated to be 98.16% under optimal conditions. The Dubinin–Radushkevich isotherm model was more compatible with the experimental results of the Cu(II) ion adsorption process (R² = 0.9772). The maximum adsorption capacity was calculated to be 56.05 mg g⁻¹. Kinetic studies demonstrated that the adsorption process of Cu(II) ions follows a pseudo-first-order kinetic model (R² = 0.9962). Thermodynamic studies showed that the adsorption process is spontaneous and endothermic. The actual outcome of wastewater treatment demonstrated the excellent effectiveness of AC/Fe₃O₄ in removing Cu(II) ions. Therefore, AC/Fe₃O₄ is an affordable material for treating copper.