Adsorption of Paracetamol and Naproxen from Wastewater onto Activated Carbon from Avocado Waste: Experimental and DFT Study

Adsorption behavior of paracetamol (Par) and sodium naproxen (Nap) onto a low-cost activated carbon prepared from waste avocado peels (APAC) has been investigated. The surface characteristics of APAC were analyzed using SEM, XRD, and FT-IR techniques. Batch adsorption experiments were carried out to investigate the influence of various parameters, such as initial drug concentration, adsorbent dosage, contact time, temperature, and pH. The experimental data for Par and Nap were analyzed using various adsorption isotherm models. Par demonstrated a good fit with both the Langmuir and Freundlich models, while the Freundlich equation provided the best fit for Nap. The data revealed that the kinetics of both drugs followed a pseudo-second order model. The estimated thermodynamic parameters ΔH°, ΔS°, and ΔG° indicate that the adsorption of Par and Nap onto the activated carbon is an exothermic, spontaneous, and physical sorption process. Furthermore, density functional theory (DFT) calculations were employed to provide insights into the adsorption mechanism. This study concludes that waste avocado peels offer a viable and economical adsorbent for the effective removal of paracetamol and sodium naproxen from aqueous solutions.