One‐pot synthesis of chitosan/iron oxide nanocomposite as an eco‐friendly bioadsorbent for water remediation of methylene blue

Chitosan/iron oxide nanocomposite was synthesised via a one‐pot method, then its functional groups and morphological structure were characterised by Fourier transform infrared spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, Brunner, Emmett, and Teller analysis and energy‐dispersive X‐ray spectroscopy. The synthesised nanoparticles had an average particle size of 50 nm with a surface area, total pore volume and mean pore diameter of the nanocomposites calculated at 0.46 m 2 /g, 0.11 cm 3 /g and 53.209 nm, respectively. After characterisations, the nanoparticles were applied as the bioadsorbent for aqueous solutions, which were polluted with methylene blue as a model of cationic dyes. The maximum adsorption capacity obtained was 5.12 mg/g. The study parameters influencing the adsorption processes show that 0.2 g of chitosan/iron oxide nanocomposite removed 80% of the pollution (initial concentration 10 mg/l) from 50 ml of water with a pH > 4 after 60 min at 25°C, while unmodified chitosan removed only 20%. The nanoparticles were able to remove over 50% of the dye after five reused cycles. The application of different salts revealed that sodium chloride had a greater restraint effect than sodium sulphate on the adsorbent. The pseudo‐second‐order and the Langmuir model successfully exhibited the adsorption kinetic and isotherm.