Kinetic and computational evaluation of activated carbon produced from rubber tires toward the adsorption of nickel in aqueous solutions

Abstract: This work aims to evaluate the potential of waste rubber tire as an inexpensive sorbent material for nickel ion removal from aqueous solution. A laboratory scale study carried out on the production of activated carbon (AC) from waste rubber tire by physical activation method. Scanning electron microscope analysis was used to characterize the surface properties of the AC adsorbent. The surface area of AC was measured to be 465 m²/g. This large surface area of the AC could play a vital role in enhancing the removal of Ni(II). Aqueous solutions containing nickel ion in varying concentrations were prepared. Batch adsorption experiments at different operating parameters such as pH, metal concentration, adsorbent dose, contact time and temperature were carried out. These in turn revealed the adsorption capacity and helped in determining the mechanism with respect to thermodynamics, equilibrium and kinetics. The kinetic studies were carried out to determine the kinetics of the adsorption process. The Langmuir isotherm was followed under the present conditions with R² = 0.938. The overall absolute deviations between experimental and predicted values were found to be 14.4%. The Langmuir model better appears to fit the adsorption of Ni onto AC adsorbent. The characterization and computational studies of the AC adsorbent after adsorption of nickel was also carried out and the results confirmed the positive adsorption process. FTIR analysis of AC before and after Ni adsorption indicated that adsorption of nickel metal on AC took place with the disappearance/diminishing of carbonyl groups. The results of nickel adsorption on AC revealed its potential for pollutant removal and finally its application in water treatment.