Chitosan functionalized with N,N-(2-aminoethyl)pyridinedicarboxamide for selective adsorption of gold ions from wastewater

Abstract

The recovery of gold from wastewater has always been a research hotspot. Here, a novel chitosan-based adsorbent (CS-DPDM) was successfully synthesized by functionalizing chitosan with (N, N-(2-aminoethyl))-2,6-pyridinedicarboxamide. The adsorbent was analyzed by fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (1H NMR), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and zeta potential method (Zeta). To investigate the adsorption performance of CS-DPDM for Au(III), the effects of pH, temperature, adsorption time and initial concentration were discussed. The maximum adsorption capacity of CS-DPDM for Au(III) at pH 5.0 is 659.02 mg/g at 318 K. The adsorption is a spontaneous endothermic behavior, and the adsorption process follows the quasi-second-order kinetic and Langmuir isotherm models, indicating that a single layer of chemical adsorption may have occurred on the surface of the adsorbent. The competitive adsorption and repetitive experiments show that CS-DPDM has considerable selectivity and reusability for Au(III). X-ray photoelectron spectroscopy (XPS) results show that N and O functional groups adsorb Au(III) on the surface of CS-DPDM through electrostatic, chelation and reduction. These results indicate that CS-DPDM has broad application prospects in recovering gold ions from aqueous solutions.