Glutaraldehyde cross-linked magnetic chitosan nanocomposites: Reduction precipitation synthesis, characterization, and application for removal of hazardous textile dyes

Magnetic chitosan nanocomposites (MCNCs) were synthesized by an inexpensive reduction precipitation technique using a glutaraldehyde cross-linking agent at room temperature. Successful chitosan coating of iron oxide nanoparticles was confirmed by X-ray photoemission spectroscopy. X-ray diffraction data revealed crystalline particle sizes for the iron oxide and MCNCs to be around 6–7 and 8–9 nm, respectively. In addition, the MCNCs exhibited supermagnetic properties having magnetic saturation of 17.5 emu/g. The synthesized MCNCs showed 91.60% absorption of Acid Red 2, while iron oxide 16.40% absorption; enhanced performance in MCNCs was resulted from presence of free amino and hydroxyl groups. Furthermore, the optimum pH and adsorbent concentration were 3 and 1.0 g/L, respectively. The Redlich–Peterson isotherm fit experimental data better than Langmuir and Freundlich models, based on non-linear regression. Finally, MCNCs showed 96% American Dye Manufacturing Institute (ADMI) value removal and gave recovery efficiency of 100%, making them attractive for further practical applications.