Hydrogels as a Potential Chromatographic System: Absorption, Speciation, and Separation of Chromium Species from Aqueous Media

Abstract Hydrogels with highly charged forms and amphiphilic character, based on an anionic monomer 2-acrylamido-2-methyl-1-propansulfonic acid sodium salt (AMPSNa) and a cationic monomer 3-acrylamidopropyltrimethylammoniumchloride (APTMACl), were synthesized via a photo-polymerization technique and investigated for potential use in the separation of chromium species with different oxidation states. They were used for three main purposes. First, a single chromium species was successfully removed from an aqueous medium in the presence of other forms using the appropriate design and synthesis of the hydrogels. Secondly, the copolymerized p(AMPSNa-co-APTMACl) hydrogels were used to remove two chromium species simultaneously from an aqueous medium. Lastly, in addition to speciation of the chromium species, their separation and removal by an externally applied magnetic field using magnetically responsive hydrogels was demonstrated. Keywords: chromium species separationhydrogelmagnetic-compositeremovalspeciation ACKNOWLEDGEMENTS This work is supported by Çanakkale Onsekiz Mart University (COMU BAP 2010/186). Also, N. Sahiner greatly appreciated the financial support by the Turkish Academy of Science under the 2008-TUBA GEBIP Program. Notes *[Chromium ions concentration: 50, 100, 250, 500, 750, 1000, 1500 ppm; 50 ml, 0.2 g hydrogel]. *Concentration: 500 ppm (50 ml), Absorbent: 0.2 g hydrogel. a mg/g dry gel, N.S. Not synthesized. a 50 ml. b Detected by ICP-AES, confirmed by IC. c For 0.3 g hydrogel. d 0.5 M HCl (50 ml × 4). e according to initial concentration. (*) Cr (VI) prepared from K2CrO4. (**) Washed with DI water (2 × 50 ml) (before desorption). N.D. Not detected. a 50 ml. b Detected by ICP-AES, confirmed by IC. c For 0.3 g hydrogel. d According to initial concentration. e 0.5 M HCl (50 ml × 4). *Same hydrogel was employed in all absorbtion cycle. (*) Cr (VI) prepared from K2Cr2O7 and Cr (III) from CrCl3.