Magnetic chitosan–GO nanocomposite: Synthesis, characterization and batch adsorber design for Cr(VI) removal

• Magnetic chitosan–graphene oxide composite (CGM) is synthesized, characterized and used for Cr(VI) removal.
• CGM has very high adsorption capacity for Cr(VI).
• The composite material can be magnetically separable from the solution and can be reused for 5th cycle of regeneration.
• Performances of CGM in Cr(VI) removal are investigated by designing single stage batch adsorber.

A magnetically modified graphene oxide–chitosan composite was synthesized and exploited for removal of chromium(VI). The composite material was characterized by BET, SEM, TEM, XRD and FTIR. The optimum pH was 3.0 (±0.1). Film diffusion and pseudo-second-order equation governs the overall kinetics. Langmuir and Redlich–Peterson isotherms describe the experimental data. Negative ΔG° (−15.49 to −15.67 kJ mol−1) with positive ΔH° (11.29 kJ mol−1) indicated spontaneous and endothermic reaction. Optimum regenerate solution is 0.05 M NaOH and spent adsorbents could be reused up to 5th cycle of regeneration, where the composite retained its adsorption capacity ˜92% of its original. A single stage batch adsorber is proposed for removal of Cr(VI) concentration up to 0.05 mg L−1.

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