Waste Tire Rubber–Derived Activated Carbon for Wastewater Treatment

The adsorption performance of activated carbon derived from waste tire rubber for the removal of methyl orange dye from aqueous solutions was investigated in the present laboratory-scale experiment. The activated carbon was prepared from ground waste tire rubber via chemical activation using potassium hydroxide (KOH) and hydrochloric acid (HCl). The carbonization process was conducted at 300 °C for 1 h, followed by further heating at 800 °C for 2 h under a nitrogen atmosphere. Chemical activation was carried out using 4 M (mol L⁻¹) KOH or HCl, followed by a final activation step at 800 °C for 1 h. Surface morphology and textural properties were characterized using scanning electron microscopy (SEM) and Brunauer–Emmett–Teller (BET) analysis. The BET surface areas of HCl-activated and KOH-activated carbons reached 925 m² g⁻¹ and 1048 m² g⁻¹, respectively. Batch adsorption experiments were conducted at initial dye concentrations of 50–200 mg L⁻¹ and temperatures ranging from 20 to 35 °C. Maximum dye removal efficiencies of 97.5 % and 98.7 % were achieved for HCl-activated and KOH-activated carbons, respectively. Equilibrium data were well described by the Langmuir isotherm model, indicating monolayer adsorption on a relatively homogeneous surface. The results confirm that waste tire rubber is a promising and sustainable precursor for producing high-performance activated carbon for wastewater treatment applications.