Preparation of the chitosan grafted poly (quaternary ammonium)/Fe3O4 nanoparticles and its adsorption performance for food yellow 3

• Novel CTS-g-PTMAAC/SC-Fe3O4 composite magnetic nanoparticles with abundant surface positive charges were preprared.
• The structure, morphology, magnetic, isoelectric point and zeta potential of nanoparticles were studied.
• The composite magnetic nanoparticles were used to adsorb food yellow 3, a typical food dye.
• CTS-g-PTMAAC/SC-Fe3O4 nanoparticles showed more rapid adsoprtion speed and higher adsoprtion capacity than CTS-g-HTCC/SC-Fe3O4 nanoparticles.
• The adsorption pH sensitivity, kinetics, isotherm, thermodynamic parameters, desorption and reusability of magnetic nanoparticles were studied.

Chitosan and its derivatives can be used to modify magnetic materials to promote the adsorption properties of the magnetic materials and avoid the weakness of chitosan and its derivatives. In the present study, chitosan grafted poly(trimethyl allyl ammonium chloride) (CTS-g-PTMAAC) was prepared by graft copolymerization; then it was coated on the surfaces of the sodium citrate coated Fe3O4 nanoparticles (SC-Fe3O4) to prepare a novel composite CTS-g-PTMAAC/SC-Fe3O4 magnetic nanoparticles, with which possesses abundant surface positive charges. The structure and properties of the CTS-g-PTMAAC/SC-Fe3O4 composite magnetic nanoparticles were characterized by FTIR, TEM, VSM, and zeta potential. The dye adsorption characteristics of the CTS-g-PTMAAC/SC-Fe3O4 nanoparticles were determined using the food yellow 3 aqueous solutions as a model food effluent. Effect of pH of the dye solution on the adsorption of food yellow 3 was determined and compared with N-2-hydroxylpropyl trimethyl ammonium chloride chitosan coated sodium citrate-Fe3O4 (CTS-g-HTCC/SC-Fe3O4) composite magnetic nanoparticles. The adsorption kinetics, adsorption isotherms, adsorption thermodynamics, and desorption and reusability of the magnetic nanoparticles were investigated.