INVESTIGATING REMOVAL OF TRIMETHYLXANTHINE BY ACTIVATED CARBON PREPARED FROM PET WASTE

Activated carbon (BK) has been prepared from polymeric wastes by chemical activation with KOH. Adsorption of trimethylxanthine onto BK was investigated with variations of pH, contact time, trimethylxanthine concentration, and temperature. The results were analyzed by the Langmuir and Freundlich equations. Adsorption of trimethylxanthine (caffeine) onto BK follows the Langmuir isotherm model. The kinetics of trimethylxanthine adsorption has been discussed using three kinetic models, i. e., the pseudo first-order, the pseudo second-order, and the intraparticle diffusion models. The kinetic studies showed that the adsorption followed a pseudo second-order reaction. The intraparticle diffusion rate constant, the external mass transfer coefficient, film and pore diffusion coefficients at various temperatures were evaluated. The thermodynamic parameters, such as Delta G super(o), Delta S super(o), and Delta H super(o), have been calculated. The thermodynamics of the trimethylxanthine -BK system indicated an endothermic process.