Sustainable Adsorbent: Activated Carbon From Waste Styrofoam for Efficient Aluminum Removal

This paper reports on batch investigations utilizing activated carbon (AC) made from waste Styrofoam to adsorb aluminum (Al³⁺) from aqueous solutions. The AC morphology and structure were examined using Fourier-transform infrared spectroscopy, scanning electron microscopy, and surface area analysis. The factors affecting the performance of adsorption were thoroughly examined. Al³⁺ removal was found to be maximal, that is, 98.65% using 0.2 g of AC at 90 min in a solution of pH 5 maintained at 60°C. Using a flame-mode atomic absorption spectrophotometer (AAnalyst 700, PerkinElmer, USA), the quantity of Al³⁺ in the adsorption solution was measured. For the purpose of studying adsorption, the pseudo-first-order, pseudo-second-order, Langmuir, Freundlich, Temkin, Jovanovich, and Harkins-Jura isotherms were analyzed. The kinetic study shows that the adsorption of Al³⁺ onto Al³⁺ is controlled by pseudo-second-order kinetics. It was observed that among these models, the Langmuir model showed the most favorable fit for the equilibrium data on the removal of Al³⁺ onto AC, with a strong fit (R² = 0.995). The values of thermodynamic parameters such as entropy (ΔS°), Gibbs free energy (ΔG°), and enthalpy (ΔH°) show that the adsorption process is spontaneous and exothermic in nature. In Al³⁺ solutions with low concentrations, the AC exhibited a high adsorption rate. In addition, a check of the error function was performed. To find out if the AC could be utilized again after the adsorption procedure, desorption investigations were carried out. Due to its high adsorption capacity (> 98%) and porous structure, the prepared AC shows significant promise as an alternative adsorbent for Al³⁺. These findings demonstrate that the AC is both effective and efficient in removing Al³⁺ from wastewater.