Synthesis, Characterization and Application of [PVA-g-P (AAm-co-MBA)]/Fe3O4/ DES- Based Magnetic Composite for Rhodamine B DyeAdsorption

Abstract

      The research reports the synthesis, characterization, and application of a unique magnetic polymeric composite, a polyvinyl alcohol-grafted poly (acrylamide-co-methylenebisacrylamide) incorporated with iron oxide nanoparticles and deep eutectic solvents [PVA-g-P (AAm-co-MBA)]/Fe₃O₄/DES. The composite comprises polyvinyl alcohol-grafted poly (acrylamide-co-methylenebisacrylamide) integrated with iron oxide nanoparticles and deep eutectic solvents. The main aim is to create an effective, environmentally sustainable adsorbent for the removal of Rhodamine B (RB), a toxic cationic dye, from water solutions. DES was created using choline chloride with urea (1:2 ratios), and combined with PVA, acrylamide, MBA, and Fe₃O₄ nanoparticles to construct a hydrogel- based magnet nanocomposite. Diffraction of X- Rays (XRD), infrared spectroscopy with the Fourier transform (FTIR), and field emission scanning electron microscopy (FESEM) validated the hydrogels amorphous and permeable character, as well as the successful integration of magnetized nanoparticles and adsorption friendly functional groups. Batch adsorption tests were carried out to determine the influence of different factors such as contact duration, pH, temperature, adsorbent dose, and ionic strength on RB removal effectiveness. The composite exhibited rapid adsorption, reaching equilibrium in approximately one hour and achieving a maximum removal efficiency of 68.3% under optimal circumstances.  The adsorption process had pseudo-second-order kinetics and best suited the Langmuir isotherm model, implying multilayer adsorption on a heterogeneous surface. Thermodynamic investigations showed that RB adsorption was exothermic with a negative enthalpy change (ΔH° = -6.837 kJ/mol).  The composite was likewise sensitive to ionic strength and pH, with optimal adsorption occurring at pH 6.  The study supports the composite's significant potential for wastewater treatment applications due to its reusable nature, magnetic separability, and ecologically benign production method.