Synergistic effect of bio-inspired Psyllium/Okra hybrid backbone based hydrogel using RSM optimization for efficient removal of toxic malachite green dye and sequestration of uranium (VI) ions from water

Abstract

The objective of the present work is to fabricate environment-friendly biosorbent semi-Interpenetrating Network Device based on Psyllium-Okra hybrid backbone and acrylamide by using citric acid and ammonium persulphate as the crosslinker and initiator respectively. Response Surface Methodology (RSM) was used for the optimization of different reaction parameters that sequentially maximized the percentage swelling of the fabricated gel. Amalgamation of acrylamide chains onto Psyllium-Okra based hybrid backbone functional groups present and crosslinking between the different polymeric chains were further confirmed through techniques like FTIR, SEM-EDX and PXRD. The sample showed better thermal stability with decomposition of different phases at higher temperatures. The synthesized semi-IPN was successfully proved to be the proficient candidate for the removal of cationic toxic malachite green dye (62.38 %) with an adsorbent dose of 1.0 g, initial concentration of 10 mg L-1 and time interval of five minute at ambient temperature. Langmuir and Freundlich adsorption isotherm models were studied in order to determine the nature of adsorption took place and it was analysed that Langmuir adsorption isotherm was the best fit model for the removal of toxic cationic malachite green dye. Kinetic studies for the sorption of dyes favoured the reaction mechanism to occur via a pseudo second order pathway with R2 value about 0.99. The synthesized semi-IPN was also utilized in uranium (VI) uptake with an adsorbent dose of 1.0 g, initial concentration of 100 ppb, time interval of 55 minutes at room temperature. The semi-IPN could uptake 97.10 ppb uranium (VI) and was observed highly efficient in uranium (VI) ions removal from aqueous medium. Thus, adsorption studies indicated that semi-IPN prepared out of natural blend was found effective in the sequestration of toxic dyes and heavy metal ions.