Removal of Cu(II) ions from aqueous solutions using petroleum coke-derived microporous carbon: investigation of adsorption equilibrium and kinetics

Petroleum coke (PC)-derived porous carbons were developed through chemical activation using KOH and applied to adsorb Cu(II) ions from aqueous solutions. The effects of KOH/PC mass ratio and activation temperature on the preparation and physical properties of porous carbon were studied. Also, the effects of the initial solution pH, contact time, operating temperature, dosage of adsorbent, and initial Cu(II) concentration on adsorption were investigated in detail. A maximum Cu(II) ion adsorption capacity of 89.85 mg g−1 was attained at 30 °C using PCK3-450, the porous carbon sample prepared using a KOH/PC mass ratio of 3:1 at 450 °C. Adsorption isotherms were analyzed using the Langmuir, Freundlich, and Temkin models, and the experimental data fit well with the Freundlich model. Pseudo first-order, pseudo second-order, Elovich, and intra-particle diffusion models were used to describe the adsorption kinetics, and the rate of adsorption conformed to the pseudo second-order kinetic model. The activation energy of Cu(II) ion adsorption on PCK3-450 was estimated at 29.61 kJ mol−1, and thermodynamic parameters were discussed. The porous carbon adsorbents developed in this study are inexpensive and effective for Cu(II) ion removal from aqueous solutions.