Functionalization of magnetic chitosan with graphene oxide for removal of cationic and anionic dyes from aqueous solution

• Synthesized Fe3O4 supported chitosan-graphene oxide composite.
• Studied removal of both cationic and anionic dyes as textile effluents are complex mixtures.
• Evaluated kinetic, equilibrium and thermodynamic aspects.
• From practical utility perspective, ionic strength and recyclability studies were undertaken.
• Application to the clean-up of spiked real samples showed promising results.

In the present study, we decorated chitosan (©) with Fe3O4 nanoparticles followed by cross-linking with GO to prepare Fe3O4 supported chitosan-graphene oxide composite (Fe3O4©-GO). Different properties of synthesized material were investigated by SEM, XRD, FTIR, TGA and EDX. Batch adsorption experiments were performed to remove toxic cationic and anionic dyes from industrial wastewater. To maximize removal efficiency of composite material, effect of pH (4–12), time (0–80 min), Fe3O4©-GO dosage (2–10 mg), initial dye concentration (2–30 μg mL̄ 1) and temperature (303, 313, and 323 K) were studied. The uptake of dyes presented relatively fast adsorption kinetics with pseudo-second-order equation as the best fitting model. To understand the interaction of dye with adsorbent, Langmuir and Freundlich isotherm were applied. Thermodynamic studies were conducted to calculate the changes in free energy (ΔG0), enthalpy (ΔH0) and entropy (ΔS0). In view of practical application, the influence of ionic strength, recycling as well as investigations based on percent recoveries from spiked real water samples were also taken into account.

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