Adsorption of ibuprofen from wastewater using activated carbon and graphene oxide embedded chitosan-PVA: equilibrium, kinetics, and thermodynamics and optimization with central composite design

In the presented study, the feasibility of using activated carbon and graphene oxide embedded chitosan-poly (vinyl alcohol) (AC/CS-PVA and GO/CS-PVA) biocomposites as adsorbents for removal of ibuprofen from wastewater. The point of zero charge values, effect of AC and GO content in the biocomposites, optimum amount of biocomposites, optimum pH and ibuprofen concentration were considered. When AC and GO were embedded into CS-PVA polymer network, the ibuprofen removal performance increased from 11% to 83% and 94%, respectively. Adsorption isotherms were described by Langmuir, Freundlich, Dubinin-Radushkevich (D-R), Temkin, Halsey, Jovanovic, Elovich, and Harkins-Jura isotherm models. Freundlich, Temkin, Halsey, Elovich, and Harkins-Jura models were fitted to the adsorption better than Langmuir, D-R, and Jovanovic models. Adsorption kinetics was investigated by pseudo-first order, pseudo-second order, Elovich, Weber-Morris, and Bangham models and ibuprofen adsorption onto biocomposites represented by pseudo-second order kinetic model. The thermodynamic parameter, Delta H degrees, Delta S degrees, and Delta G degrees, values were determined and the enthalpy of ibuprofen adsorption was found positive supporting the endothermic nature of pharmaceutical pollutant adsorption. The influence of various operating variables and optimum process conditions for the ibuprofen adsorption was investigated using central composite design.