Adsorption Studies of PVA Based Thermosensitive Polymers in Heavy Metal Removal

Thermosensitive copolymers were synthesized by grafting of N-isopropyl acrylamide (NIPAM) monomer onto crosslinked poly(vinyl alcohol) (PVA) and characterized by FTIR, XRD, elemental and SEM-EDS analysis. Also, the swelling capacities, water release values and cloud points of the copolymers were determined. The removal of Cu(II), Ni(II) and Cd(II) ions was studied by using of the copolymers as solid phase extractor. Dodecyltrimethylammonium chloride (DTAC) was the extractant to complex with ions in the process. The copolymer adsorbs the metal-extractant complexes above its lower critical solution temperature (LCST) by hydrophobic interaction. Increasing the time and initial metal ion concentration caused an increase in the adsorption capacities, and the copolymer displayed S-type adsorption in Giles's classification. The experimental data followed pseudo-second-order model, and the dominated adsorption mechanism was external mass diffusion. In addition, adsorption/desorption cycles presented the usability of the synthesized copolymer as sorbent for environmentally friendly processes.