Adsorption of lead ions onto chemically activated carbon from waste tire char and optimization of the process using response surface methodology

Abstract

Tires play an important role in the automobile industry. However, their disposal when worn out has adverse effects on the environment. The main aim of this study was to prepare activated carbon from waste tire pyrolysis char by impregnating KOH onto pyrolytic char. Adsorption studies on lead onto chemically activated carbon were carried out using response surface methodology. The effect of process parameters such as temperature (°C), adsorbent dosage (g/100 ml), pH, contact time (minutes) and initial lead concentration (mg/l) on the adsorption capacity were investigated. It was found out that the adsorption capacity increased with an increase in adsorbent dosage, contact time, pH, and decreased with an increase in lead concentration and temperature. Optimization of the process variables was done using a numerical optimization method. Fourier Transform Infrared Spectra (FTIR) analysis, X-ray Diffraction (XRD), Thermogravimetric analysis (TGA) and scanning electron microscope were used to characterize the pyrolytic carbon char before and after activation. The numerical optimization analysis results showed that the maximum adsorption capacity of 93.176 mg/g was obtained at adsorbent dosage of 0.97 g/100 ml, pH 7, contact time of 115.27 min, initial metal concentration of 100 mg/and temperature of 25°C. FTIR and TGA analysis showed the presence of oxygen containing functional groups on the surface of the activated carbon produced and that the weight loss during the activation step was negligible.