One pot preparation of magnetic chitosan-cystamine composites for selective recovery of Au(III) from the aqueous solution

A novel magnetic chitosan adsorbent (CDF-CS) was synthesized by inserting magnetic particles into the crosslinked compound of chitosan (CS) and cystamine based on one-step method for selectively recovering Au(III) from aqueous solution. The characterization and adsorption mechanism of CDF-CS were studied by SEM-EDS, VSM, FT-IR and XPS, respectively. The experimental results show that the adsorption capacity of CDF-CS is still large in a wide range of pH values (from 1 to 7) and has a higher adsorption capacity for Au(III) than the raw chitosan, the maximum adsorption capacity of CDF-CS for Au(III) was 478.47 mg/g about 6 h at pH = 7.0. The adsorption behavior is most consistent with this pseudo-second-order kinetic model. The adsorption process of gold ions by CDF-CS follows the Langmuir adsorption isotherm. Furthermore, the thermodynamic parameter indicates that the adsorption reaction of gold ions by CDF-CS is an endothermic chemisorption. CDF-CS has great potential for removing gold ions from aqueous solutions due to the excellent repeatability and selectivity. Finally, the adsorption mechanism is that chelation reaction and ion exchange mainly occurred between CDF-CS and Au(III). Therefore, CDF-CS is very promising in recovery of Au(III) from aqueous solutions.