Surface response methodology–central composite design screening for the fabrication of a Gx-psy-g-polyacrylicacid adsorbent and sequestration of auramine-O dye from a textile effluent

Abstract

The present work reported the gum xanthan–psyllium based semi-IPN which was used for the efficient capture of auramine-O dye from aqueous fluid. The semi-IPN was prepared using a free radical polymerization technique under hot air conditions using ammonium persulphate-glutaraldehyde as an initiator–crosslinker system. The liquid uptake capacity of the candidate sample was optimized using Response Surface Methodology (RSM) design through a variation of different process variables as a function of percentage swelling. Interactions between different process variables were evaluated using a Central Composite Design (CCD) so as to find out the device with the maximum aqueous fluid uptake. Further, grafting of polyacrylic acid chains onto the hybrid backbone and the surface morphology of the synthesized semi-IPN were confirmed using techniques like FTIR, XRD and SEM-EDX. The optimum conditions for the removal of auramine-O from aqueous fluid were pH ≈ 7, temperature = 303 K, initial dye concentration = 26 mg L⁻¹ and adsorbent dose = 500 mg. Pseudo first order and pseudo second order kinetic models were employed to explain the adsorption kinetics of auramine-O on the semi-IPN. The obtained adsorption data was further analysed through Freundlich and Langmuir adsorption isotherms. Freundlich adsorption isotherm models and pseudo second order kinetics were observed to fit well to the experimental results. Equilibrium and kinetic parameters indicated the spontaneous nature of the adsorption process. Thus, the semi-IPN prepared using RSM design was found to be a promising adsorbent for the textile industry.