Mussel-inspired synthesis of magnetic carboxymethyl chitosan aerogel for removal cationic and anionic dyes from aqueous solution

A novel and facile method that magnetic carboxymethyl chitosan aerogel (Fe3O4@PDA/CMC) has been developed with the combination of mussel-inspired chemistry and Schiff base reaction to remove cation and anion dyes. The resulted aerogel were systematically characterized by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), thermogravimetric analysis (TGA), N2 adsorption–desorption, and point of zero charge (pHpzc). Diverse factors affecting adsorption behavior such as pH, contact time, adsorbent dosage, initial concentration, ionic strength of dyes was investigated. The kinetic results show that the adsorption process can be well described by the pseudo-second-order. The Langmuir isotherm model can fit the equilibrium data well. The thermodynamic analyses show that the adsorption of cation and anion dyes onto Fe3O4@PDA/CMC aerogel is endothermic and spontaneous. In this study, the obtained Fe3O4@PDA/CMC aerogel is a simple, facile and environmentally friendly procedure which involves non-toxic organic solvent. The designed magnetic aerogel exhibited an excellent recyclability and removal efficiency after seven adsorption-desorption cycles.