Adsorption of fexofenadine and diphenhydramine on dehydrated and activated carbons from date palm leaflets

Abstract

Dehydrated carbon (DC) was prepared from date palm leaflets via sulfuric acid treatment at C in the presence of air. Acidified DC was converted to activated carbon (AC) at C under nitrogen atmosphere. DC shows low surface area (48 m2 g−1), whereas activated carbon possesses high surface area (405 m2 g−1). Both carbons were tested for the adsorption of fexofenadine (FEX) and diphenhydramine (DPH) at different initial pH, concentration and temperature. Maximum adsorption took place at pH 4.0 for FEX and pH 8.0 for DPH. Adsorption kinetics was found to follow well pseudo second-order kinetic model with increased adsorption as temperature increased within the range of 25–C. Activation energy, Ea, was 12–17.5 kJ mol−1 indicating physical adsorption of both drugs. Drug uptake was found to increase with temperature rise in the range of 25–45°C. Thermodynamic parameters showed that the adsorption of drugs is spontaneous and endothermic in nature with physical adsorption dominating the removal processes. Despite having very low surface area, DC shows competitive adsorption capability for AC. Drug desorption from loaded carbons showed better performance from DC than from AC. The effect of the presence of KCl on adsorption of FEX and DPH was also studied.