ADSORPTION OF CEFIXIME TRIHYDRATE ONTO CHITOSAN 10B FROM AQUEOUS SOLUTION: KINETIC, EQUILIBRIUM AND THERMODYNAMIC STUDIES

Abstract

An efficient and biodegradable adsorbent chitosan 10B was used to eliminate cefixime trihydrate from aqueous solution. The kinetic behavior of cefixime trihydrate adsorption onto chitosan 10B was studied in aqueous medium, from various operational aspects, such as contact time, solution pH, antibiotic concentrations, and temperatures. Cefixime adsorption onto chitosan 10B was confirmed by Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDX). The antibiotic adsorption kinetics obeyed a pseudo-second-order model rather than pseudo-first-order and Elovich kinetic models. The best illustration of antibiotic adsorption equilibrium was made by the Langmuir model, with the highest adsorption ability qm: 37.04 μmol/g at 298 K. The activation energy (Ea) of the present adsorption system was computed to be 44.18 kJ/mol. The values of activation (ΔG‡, ΔH‡ and ΔS‡) and thermodynamic (ΔG, ΔH and ΔS) parameters confirmed that the cefixime trihydrate adsorption onto chitosan 10B in aqueous medium is an exothermic physisorption process. Cefixime desorption from antibiotic-loaded chitosan 10B was performed in 0.1 M NaOH solution and the recycled adsorbent was utilized for a second time without significant loss of its adsorption capacity.