Kinetic modelling and thermodynamic studies on purification of Polyvinylpyrrolidone by Adsorption

Abstract

Polyvinylpyrrolidone (PVP), a highly water soluble polymer, with many technological, engineering and pharmaceutical applications, obtained by polymerization of N-vinylpyrrolidone, has been purified by adsorption onto activated carbon and strong acidic ion-exchange resin using PVP aqueous solution. Various parameters that can affect the process have been studied such as effect of contact time, effect of adsorbent dosage, effect of temperature, effect of PVP concentration and effect of NVP initial concentration. It has been clearly demonstrated that NVP adsorption is affected by all these factors. Adsorbent capacities have been determined by mathematical fitting of equilibrium data using the most common isotherms: Freundlich isotherm and Langmuir isotherm. Several kinetic models have been applied to the process. Thermodynamic parameters: △So, △Ho, △Go and Ea (kJ/mol) have been determined. It was found out that the process follows pseudo-second-order kinetic model suggesting that the
adsorption mechanism might be a chemisorption process; thermodynamic studies showed that this process is spontaneous and endothermic. These results are very important in optimization of this purification process.

Keywords: Polyvinylpyrrolidone (PVP), adsorption, activated carbon, resin, modelling.