Fast and highly efficient removal of dye from aqueous solution using natural locust bean gum based hydrogels as adsorbent

Abstract

For the first time, stable LBG-cl-Poly(DMAAm) hydrogel is prepared via free radical in situ polymerization of N, N-dimethyl acrylamide by employing N, N'-methylene bis(acrylamide) as cross-linkers. The hydrogel was characterized by different physicochemical techniques like equilibrium swelling percentage, point of zero charges (pHPZC), FTIR, SEM, and TGA. The LBG-cl-Poly(DMAAm) hydrogel was used in experiments on swelling behavior and adsorption of water-soluble cationic dye-Brilliant green (BG). The influence of pH on the structural change of BG dye was discussed. The swelling of hydrogel was sensitive toward the pH, ionic strength, and temperature stimuli. Adsorption behavior of hydrogel was investigated for the adsorption of BG dye and it was found to highly efficient in removing 97.7% of BG dye in 50 mg L-1 of dye solution. Adsorption data displayed that the adsorption of BG followed the pseudo-second-order kinetic model (R2 = 0.998) and Langmuir isotherm model (R2 = 0.988) with a maximum adsorption capacity of 142.85 mg g-1. The developed LBG-cl-Poly(DMAAm) hydrogel demonstrated efficient separation of BG dye and maintained maximum adsorption capacity after 6th regeneration cycles. The results indicated that LBG-cl-Poly(DMAAm) hydrogel can be used as an alternative and promising adsorbent to be applied in the treatment of effluents containing the BG dye.