Preparation of activated carbon from worn tires for removal of Cu(II), Ni(II) and Co(II) ions from synthetic wastewater

In this study, activated carbon was produced through pyrolysis process from worn tires and applied as an effective and low-cost adsorbent to remove heavy metal ions of copper, nickel and cobalt from aqueous solutions. Scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR) and Brunauer–Emmett–Teller (BET) analyses were utilized to investigate the characteristics of the adsorbent. The specific surface area of activated carbon by BET analysis was reported as 32.39 m 2 /g which shows activated carbon has a suitable porous surface. The adsorption process of metal ions carried out discontinuously and effects of parameters like pH, temperature, contact time and adsorbent dosage on adsorption efficiency were examined. The results showed that adsorption efficiency increased by increasing initial pH (from 2 to 6), contact time and adsorbent dosage. But increasing the temperature, reduced adsorption efficiency showing that the adsorption process is exothermic. Besides, isotherm behavior of adsorption processes was studied using Langmuir and Freundlich isotherm models. According to correlation coefficient (R 2 ), the Freundlich isotherm model was more capable to describe isotherm behavior of adsorption process of metal ions in comparison with the Langmuir model. The maximum adsorption capacity ( q max ) based on Langmuir isotherm model was determined as 109.89 mg/g, 74.626 mg/g and 90.09 mg/g for nickel, copper and cobalt adsorption, respectively which are significant amounts. The values of parameters n and R L showed that the adsorption process is physical and desirable. Also, thermodynamic behavior showed that adsorption process was exothermic and spontaneous. Additionally, kinetic models showed that the pseudo second-order model has a greater ability to describe the kinetic behavior of the process.