Polyhydroxamic acid functionalized sorbent for effective removal of chromium from ground water and chromic acid cleaning bath

Abstract Polyhydroxamic acid sorbent was synthesized by polymerization of acrylamide using N, N′-methylene-bis-acrylamide as crosslinker and ammonium per sulphate as a thermal initiator. The sorbent was characterized for composition, thermal stability, functional group and morphology by elemental analysis, thermal analysis, infrared spectroscopy and secondary electron microscopy respectively. The synthesized sorbent was evaluated for the removal of trivalent and hexavalent chromium ion from aqueous solution. Experimental parameters such as pH, equilibration time, solute concentration and temperature were optimized. It showed a sorption capacity of 322 mg g −1 for Cr (III) and 176 mg g −1 for Cr (VI) at pH 4. The sorbent reduces the more toxic Cr (VI) to relatively less toxic Cr (III) during the sorption process as confirmed by X-ray photoelectron spectroscopy. The sorption phenomena followed Langmuir model and the sorption reaction was found to be pseudo–second order confirming chemisorption.