Adsorption of diphenhydramine from its aqueous solution onto the surface of prepared activated carbon

Abstract

This research aims to prepare activated carbon from natural waste materials, such as pine cones, collected from forests in Mosul, Iraq. The activated carbon (SAC) was prepared at 750 °C using a 1:1 mixture of KOH and charcoal under a nitrogen atmosphere. The SAC product was observed as nanoparticles, with a particle size of 1.9719 nm measured by scanning electron microscopy and a BET surface area of 1147 m²/g. Iodine number, X-ray diffraction, and energy dispersive X-ray spectrum of the prepared activated carbon were also evaluated. The factors affecting the adsorption of diphenhydramine (DPH) in aqueous solution onto the prepared activated carbon were studied. Freundlich and Langmuir isotherms were applied; the Langmuir model was more relevant to the practical data of the studied system, as evidenced by a higher correlation coefficient (R² = 0.9850) than the Freundlich Model. Thermodynamic parameters of adsorption at equilibrium were evaluated. Pseudo-first order, pseudo-second order, and intra-particle molecular diffusion were studied. The kinetic results showed that the adsorption process at equilibrium followed the pseudo-second-order equation, indicating that molecular diffusion is not the sole mechanism governing adsorption.

KEY WORDS: Activated carbon, Nano carbon, BET surface area, Freundlich and Langmuir isotherms, Adsorption of diphenhydramine, Kinetic study

Bull. Chem. Soc. Ethiop. 2026, 40(1), 211-222.                                                             

DOI: https://dx.doi.org/10.4314/bcse.v40i1.17