Temperature swing adsorption of melamine on thermosensitive poly(N-isopropylacrylamide) cryogels

In the past few years, polymer-based adsorbents have been emerging as highly effective alternatives to activated carbons for pollutants removal and recovery from industrial effluents. In this article, novel thermosensitive poly(N-isopropylacrylamide) (PNIPAAm) cryogels adsorbents were directly prepared with N-isopropylacrylamide (NIPAAm) as a thermosensitive monomer and PEG-20,000 as a porogen at -12 A degrees C by means of an in situ free-radical redox cryopolymerization. Subsequently, PNIPAAm cryogels were further employed to adsorb and desorb melamine through temperature swing adsorption (TSA) between 25 and 50 A degrees C. The adsorption isotherms were correlated to Langmuir and Freundlich isotherm models. Moreover, the result indicated that the developed PNIPAAm cryogels adsorbents could be utilized effectively to concentrate melamine from aqueous solutions and spiked liquid milk. The cycle of the adsorption and desorption could be repeated without much loss of the melamine adsorbing ability.