Fabrication and characterization of magneto-responsive polyvinyl alcohol–alginate composite hydrogel beads for the removal of cationic dyes from aqueous solutions

Abstract

In this study, magneto-responsive polyvinyl alcohol–alginate hydrogel beads are successfully fabricated using the electrospraying technique and applied as efficient adsorbents for the removal of cationic dyes, particularly malachite green (MG) and methylene blue (MeB), from water. The successful synthesis of the beads is confirmed using optical microscopy, Fourier transform infrared spectroscopy, and scanning electron microscopy. Additionally, batch adsorption studies are performed to evaluate the adsorption capacity of the hydrogel beads under varying concentrations, pH solution, and contact time. Results revealed that the beads exhibited excellent sorption capacities of 270.03 and 285.66 mg g−1 toward MG and MeB, respectively, indicating their potential as efficient adsorbents for cationic dye removal. The adsorption mechanism of the beads was further analyzed using kinetic and isotherm models, where the results revealed that the pseudo-second order kinetic model and Langmuir isotherm model exhibited the best fits with the experimental data. The incorporated magnetic nanoparticles enabled the easy separation and reuse of the hydrogel beads sample, as it maintained more than 75% of its efficiency even after five consecutive cycles. This study presents an innovative and sustainable solution for wastewater treatment, demonstrating the use of magneto-responsive hydrogel beads as effective and reusable adsorbents for cationic dye removal.