Highly efficient poly(6-acryloylamino-N-hydroxyhexanamide) resin for adsorption of heavy metal ions

Heavy metal wastewater pollution has become an ecological challenge worldwide. This study reports the development of a novel poly (6-acryloylamino-N-hydroxyhexanamide) (PAHHA) resin for effective adsorption of heavy metal ions , including Cu 2+ , Pb 2+ and Ni 2+ . The chelating resin was synthesized by the grafting reaction between 6-amino-N-hydroxyhexanamide and polyacrylic resin , thus containing the hydroxamate and acylamino groups. The batch adsorption experiments revealed that the PAHHA resin exhibited an excellent adsorption performance for Cu 2+ , Pb 2+ and Ni 2+ . The maximum adsorption capacities of Cu 2+ , Pb 2+ and Ni 2+ were determined to be 238.59, 232.48 and 115.77 mg·g −1 , respectively. Based on the adsorption kinetics , the pseudo-second-order kinetic model was noted to fit well for all metal ions. The metal ion concentration as a function of the equilibrium adsorption capacity fitted well with the Langmuir isotherm , thus indicating the single layer adsorption process . The adsorption mechanism was investigated by using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), density functional theory (DFT) calculations, X-ray photoelectron spectroscopy (XPS) and adsorption isotherms . It was revealed that the PAHHA resin possessed multiple active sites, including –CONHOH, –CONH– and –COOH, which could strongly adsorb the metal ions. Specifically, the –CONHOH group displayed a high affinity by forming a stable five-membered ring with heavy metal ions. Overall, the developed resin exhibits advantages such as simple synthesis, inexpensive raw material and good recyclability , along with high adsorption ability, thus providing a new approach for efficiently treating wastewater contaminated with heavy metal ions.