Semi-IPN hydrogels with enhanced performance by layered double hydroxide for selective anionic dye removal

The wastewater from the textile industry not only leads to environmental issues but also damages human life. To remove dyes from wastewater, semi-interpenetrating polymer network (sIPN) hydrogels, with or without layered double hydroxide (LDH), were designed and prepared by the polyvinylpyrrolidone-assisted copolymerization of [2-(methacryloyloxy)ethyl]trimethylammonium chloride and acrylamide. The successful fabrication of sIPN hydrogels was confirmed through Fourier transform infrared and diffraction (XRD) techniques. The optimized samples exhibited outstanding selectivity towards anionic dyes, with adsorption capacity values for methyl orange (MO) exceeding 500 mg g-1. Moreover, the incorporation of LDH significantly improved the fragility issue of pure sIPN hydrogels. The adsorption kinetics and isotherm analyses indicated that the adsorption process of the optimized samples adhered well to the pseudo-second-order kinetic model and Freundlich model, suggesting a strong electrostatic interaction mechanism and multilayered adsorption behavior. Notably, the sIPN hydrogel containing LDH could withstand at least 5 consecutive cycles with a regeneration efficiency of 91.3%. Consequently, it is believed that the developed sIPN hydrogels hold great potential as adsorbent materials for anionic dyes.