Adsorption kinetics studies of an anti-inflammatory drug Mesalamine using Unsaturated Polyester Resin (UPR)

This study explores the removal of an anti-inflammatory drug Mesalamine a hazardous pharmaceutical pollutants, from aqueous solution by Unsaturated Polyester Resin (UPR) a non-carbon adsorbent. The sorption of Mesalamine species has been carried out as a function of pH, contact time, adsorbate concentration (0.1-0.7 mg/mL) and temp. (30-50 °C). The optimum pH for maximum adsorption of Mesalamine was found to be at pH 10.2. The amounts adsorbed by UPR increased with the increasing concentration of hydroxide ions. The results indicate that the Langmuir adsorption isotherm model fits the data better than the Freundlich adsorption isotherm model. The calculated thermodynamic parameters (ΔGo, ΔHo and ΔSo) showed that the adsorption of Mesalamine onto UPR was feasible, spontaneous and endothermic. Mass transfer property of the sorption process was studied using Lagergren pseudo-first-order kinetic models. The values of kad for Mesalamine were calculated at different temperatures (303 − 323 K). The mechanism of the adsorption process was determined from the intraparticle diffusion model. The linear portions of the curves do not pass through the origin indicating that mechanism of Mesalamine removal onto UPR is complex and both the surface adsorption as well as intra-particle diffusion contributes to the rate determining step.