Design and fabrication of environmentally benign cellulose based hydrogel matrix for selective adsorption of toxic dyes from industrial effluvia

The present study investigates the use of agri-waste derived superabsorbent graft copolymer for effective removal of hazardous dye from industrial effluents. The hydrogel was synthesized via free radical graft copolymerization of poly (3-acrylamidopropyl)-trimethylammonium chloride copolymer N,N-Dimethylacrylamide (APTAC-co-DMA) onto banana pseudo-stem carboxymethyl cellulose (BPCMC) backbone. The reaction was initiated by ammonium per sulfate (APS) whereas the polymer cross linking was achieved by the addition of N,N-methylene-bis-acrylamide (MBA). The hydrogel was evaluated for its structure, morphology and thermal behavior using FT-IR, FESEM and TGA analyses respectively. The parameters affecting the hydrogel's swelling capacity in distilled water were optimized and the optimum condition was used to perform pH sensitivity test on the hydrogel. The maximum swelling as high as 559g/g was obtained at the optimized condition of 0.0657mol/L, 0.0972mol/L and 0.5mol for APS, MBA and APATAC/DMA respectively. The pH sensitivity test revealed maximum swelling under pH7 for 570min. Furthermore, the hydrogel was evaluated for removal of Rhodamine B. (RhB) and Eriochrome black T (EBT) dyes. The respective maximum dye adsorption capacity to the tune of 434 and 714mg/g for RhB and EBT was obtained. The adsorption was modeled for isotherm studies and the Freundlich isotherm model was found to be the most favored models befitting the adsorption of both dyes.