Adsorption of food dyes from aqueous solution by glutaraldehyde cross-linked magnetic chitosan nanoparticles

•The GMCNs displayed higher food dye adsorption capacity and lower cytotoxicity.•Adsorption process was spontaneous and exothermic which fitted the Langmuir model.•The GMCNs were regenerated successfully and can be reuse for food dye adsorption. Glutaraldehyde cross-linked magnetic chitosan nanoparticles (GMCNs) were prepared through cross-linking modification of magnetic chitosan nanoparticles (MCNs) using glutaraldehyde as crosslinker, that not only exhibited excellent food dyes adsorption performance, but also showed low cytotoxicity. Adsorption characteristics of GMCNs in FD&C Blue 1 and D&C Yellow 5 aqueous solutions have been studied and results indicated that the adsorption capacities were affected by initial pH values, initial dye concentrations and temperatures. Food dyes adsorption followed with thepseudo-second-orderreaction, and equilibrium experiments were well fitted the Langmuir isotherm model. Maximum adsorption capacities of GMCNs displayed at pH 3.0 and at 25°C, being up to 475.61 and 292.07mg/g, for FD&C Blue 1 and D&C Yellow 5 respectively. Thermodynamic results demonstrated that the adsorption processes were spontaneous and exothermic. Furthermore, it was found that the GMCNs can be regenerated and reused through dye desorption in alkaline solution.