الملخص الإنجليزي
Dehydrated and activated carbons were prepared from date palm leaflets. Dehydrated carbon (DC) was prepared via phosphoric acid treatment at 150 °C for ~ 20 hours in presence of air. DC was transformed to activated carbon (AC) at 500 °C under nitrogen atmosphere. Dehydrated carbon is loaded with carbon-oxygen functional groups and exhibits low surface area (3.7 m2 g), whereas, activated carbon possesses high surface area (829 m2 g*'), with less carbon-oxygen functional groups on its surface. X-ray diffraction showed that both carbons are generally amorphous, however, AC was found to possess little graphitization. The developed carbons were tested for the removal of two drugs: Chlorpheniramine (CP) and Lisinopril (LIS) from aqueous solutions in terms of kinetics and equilibrium. The adsorption of CP and LIS was tested at different initial pH, time, drug concentration, temperature and salt in addition to column studies. Optimum adsorption of CP was found to be at pH 9.0, however, for LIS, it was at pH 4.0 – 5.0. Kinetic and equilibrium studies were carried out at their optimal initial pH values. Equilibrium time was ~ 48 hours for testing the removal of both drugs on the carbons under investigation. Adsorption data were found to follow the pseudo second order kinetic model. Adsorption rate was found to increase with temperature rise with the activation energy in the range of 2125 kJ moll indicating the physical nature of drug adsorption. Dehydrated carbon showed slower kinetics than activated carbon probably due to the narrower pores developed on drying and its very small surface area. The equilibrium studies show very good fitting with Langmuir isotherm more than Freundlich. Equilibrium adsorption was found to increase with temperature increase. Dehydrated carbon, even with very little surface area, still shows good drug adsorption compared with that of activated carbon. Thermodynamic parameters showed that the removal of CP and LIS is spontaneous and endothermic in nature with physical adsorption dominating their removal from aqueous solution. The presence of salt increases the adsorption efficiency due to the salting out effect. Dynamic adsorption studies show good breakthrough curves for the removal of both drugs. From this study, dehydrated carbon proved to be as efficient as activated carbon in removing pharmaceutical drugs from aqueous solution, however, with better desorption properties than activated carbons.
