Fe3O4 imbuing carboxymethyl cellulose/dextran sulfate nanocomposite hydrogel beads: an effective adsorbent for methylene blue dye pollutant

Abstract In this study, initially synthesized magnetic nanoparticles modified with citrate ions (MNPs/m-MNPs) were entrapped in aluminum-carboxymethyl cellulose/dextran sulfate beads to form hybrid nanocomposites (m-MNPs-C/D0.5) using a simple two-pot method. Sodium dodecyl sulfate surfactant was employed to develop a porous interconnected structure. The synergistic effect of the hybrid nanocomposites was studied for the parametric adsorption of methylene blue dye pollutant. The swelling ability of hybrid hydrogels was also studied for different solution pH. The results clearly indicated that equilibrium was reached faster at about 3 h for the m-MNPs-loaded magnetic beads (m-MNPs-C/D0.5), whereas at 6 h for the MNPs-loaded beads (MNPs0.4-C/D0.5) and the unloaded simple ones (MNPs0-C/D0.5). Experimental data modeling of adsorption kinetics and isotherms as well as thermodynamic study showed a good correlation with pseudo-second order kinetic and Langmuir models while the adsorption process on magnetic beads was exothermic. The maximum adsorption capacity for MNPs0-C/D0.5 and the optimized m-MNPs0.3-C/D0.5 hydrogel were 380 and 529 mg g−1, respectively. Furthermore, all hydrogels were perfectly regenerated and then reused for five adsorption-desorption cycles without apparent loss of stability that confirms their consideration as alternative and effective adsorbents for wastewater treatment. The manufactured beads were characterized by scanning electron microscopy/energy dispersive X-Ray, dynamic light scattering, X-ray diffraction, thermogravimetric analysis, vibrating sample magnetometer and fourier-transform infrared spectroscopy. Graphical Abstract