Adsorption of chromium (VI) on a novel quaternized chitosan resin

An inverse emulsion method was used to prepare the chitosan microspheres, which were crosslinked with epichlorohydrin between the hydroxyl groups under protection of amino groups to obtain crosslinked chitosan resin. Further chemical modification with glycidyl trimethylammonium chloride was used to form the quaternary ammonium ion resin. The resin had different adsorption ability for the chromium (VI) in anionic forms from that of the crosslinked chitosan beads. The crosslinked chitosan resin exhibited maximum adsorption for chromium (VI) at pH 3.0 and the adsorption capacity decreased sharply above pH 6, whereas the adsorption capacities of quaternized chitosan resin were significant over pH 3 to 11. The quaternized resin was more efficient than the crosslinked chitosan resin in media of pH above 5. The complete removal of chromium from the solution of K2Cr2O7was achieved with a column method using the quaternized chitosan resin, which was hard, and the decrease in pressure in the column was small. The breakthrough point of 10.0 mg L−1chromium in quaternized resin column was 3200 mL g−1resin greater than 600 mL g−1resin in the crosslinked chitosan resin column.