English abstract
Activated carbon (AC) was prepared from date palm leaflets and was oxidized using nitric acid to produce oxidized activated carbon (OAC). OAC was functionalized via amide coupling to produce hydrophobic activated carbons (HACs) using n-alkyl amine surfactants: n-ethyl amine, n-propyl amine, n-butyl amine and n-octyl amine. AC possesses high surface area (425 m-/g). It possesses less carbon-oxygen functional groups on its surface with slightly higher mesoporosity. Upon oxidation and surface functionalization, the surface area tremendously decreased and microporosity diminished.
Bisphenol A, an endocrine disruptor, was tested for its removal from aqueous solution at different initial pH, time, concentration, temperature. Optimum adsorption took place at initial pH = 6.0, thus, kinetic and equilibrium studies were carried out at initial pH of 6.00 using the carbons produced in this work together with a commercial activated carbon (CAC) for comparison, Equilibrium time was found to be - 10 hours for HACs, however for AC, CAC and QAC, ~ 30 hours were required for reaching equilibrium. Adsorption data were found to follow the pseudo second order kinetic model. Adsorption rate was found to increase as temperature increases with the activation energy ranging between 4.23-14.0 kJ/mol indicating the physical nature of BPA adsorption. The equilibrium studies show a better fitting to the Langmuir isotherm when compare to the Freundlich isotherm. Equilibrium adsorption was found to increase with the increase in temperature. Hydrophobic activated carbons (HACE, HACP and HACB) show higher adsorption capacity than AC. Thermodynamic parameters show that the removal of BPA is spontaneous and endothermic in nature with physical adsorption dominating their removal from aqueous solution. From this study, HACs, particularly with short immobilized n-alkyl chains, show better performance than activated carbons in terms of kinetics and equilibrium.
