Preparation of a porous, magnetic, quaternary chitosan salt by preadsorption and desorption for azo dye adsorption from water

A porous magnetic quaternary chitosan salt (pre-CS/EPTAC/Fe 3 O 4 ) was successfully prepared via a kind of novel method of preadsorption and desorption. The physicochemical properties of pre-CS/EPTAC/Fe 3 O 4 were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and vibrating sample magnetometry. The adsorption of pre-CS/EPTAC/Fe 3 O 4 for methyl orange (MO) showed much higher dye uptakes compared with Npre-CS/EPTAC/Fe 3 O 4 without the preadsorption and desorption of MO, and the maximum adsorption capability for MO was 486.1 mg/g. Adsorption isotherms and adsorption kinetics were well fitted by the Freundlich isotherm model and the pseudo-second order model, respectively. Thermodynamic parameters, such as the standard free energy change, enthalpy change, and entropy change, were also calculated; this indicated that the adsorption was spontaneous and exothermic. The introduction of MO preadsorption and desorption into the process of preparation improved not only the adsorption of MO but also the adsorption of acid red 1 and orange G. Furthermore, pre-CS/EPTAC/Fe 3 O 4 particles could be easily regenerated and remained almost constant (98.5%) for six cycles of adsorption and desorption. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133 , 43448