Removal of [Pb.sup.2+] from aqueous solution by P hidrogela

A series of poly(2-hydroxyethyl acrylate-co-itaconic acid), P(HEA/IA), hydrogels with different HEA/IA ratio, were synthesized using free radical crosslinking/copolymerization and investigated as sorbents for [Pb.sup.2+] from aqueous solutions. Hydrogels were characterized using DMA, FTIR, DSC, SEM and AFM. The adsorption was found to be highly dependent on hydrogel composition, solution pH, sorbent weight, ionic strength and contact time. Five isotherm models, Langmuir, Freundlich, Redlich-Peterson, Temkin and Dubinin-Radushkevich, were applied to the sorption data. The best fit was obtained with Redlich-Peterson isotherm. The separation factor, [R.sub.L], value indicated favorable sorption for [Pb.sup.2+]. The maximum sorption capacities were 392.2 and 409.8 mg/g for P(HEA/2IA) and P(HEA/10IA), respectively. Kinetic data showed best fit with pseudo-second-order model. Thermodynamic studies revealed that the reaction was exothermic and proceeds with a decrease in entropy. Moreover, P(HEA/IA) hydrogel showed the most pronounced sorption toward [Pb.sup.2+] from environment containing [Cu.sup.2+], [Zn.sup.2+], [Cd.sup.2+], [Ni.sup.2+] and [Co.sup.2+]. Sorption/desorption experiments, showed that the P(HEA/IA) hydrogels could be reused without significant loss of the initial properties even after three adsorption-desorption cycles. Keywords: hydrogel, itaconic acid, reusability, lead removal. Available online at the Journal website: Hidrogelovi na bazi 2-hidroksietil-akrilata i itakonske kiseline su sintetisani polimerizacijom preko slobodnih radikala i ispitana je mogucnost njihove primene kao sorbenata za uklanjanje [Pb.sup.2+] iz vodenih rastvora. P(HEA/IA) kopolimeri sa razlicitim udelom itakonske kiseline su karakterisani pomocu DMA, FTIR, DSC, SEM i AFM analize. Ispitan je uticaj pH, mase sorbenta, jonske jacine, vremena sorpcije i pocetne koncentracije jona olova na proces sorpcije. Analizirano je pet modela adsorpcionih izotermi (Lengmir, Frojndlih, Redlih-Peterson, Tjomkin i Dubinin-Raduskevic). Najbolje slaganje sa eksperimentalnim vrednostima pokazuje Redlih-Petersonova izoterma. Maksimalni sorpcioni kapaciteti za P(HEA/2IA) i P(HEA/10IA) hidrogelove su bili 392,2 i 409,8 mg/g, redom. Kineticka analiza sorpcije je pokazala najbolje slaganje eksperimentalnih vrednosti sa pseudo-drugim redom reakcije. Ispitivanje termodinamickih parametara je pokazalo da je reakcija sorpcije olova egzotermna i odigrava se uz smanjenje entropije. Takode, P(HEA/ /IA) h