Enhancement of Cu(II) in water adsorption on D113 resin modified with bi-ligand amino-triazole-thione compounds: Investigation on adsorption behavior and mechanism

A novel 3-lauramide propyl ester-4-amino-1,2,4-triazole-5-thione modified polyacrylic acid resin (LmPATT-reD113), comprising a bi-ligand amide-based triazole-thione moiety and a carboxylic acid moiety, was prepared and employed for the effective removal of Cu(II) from wastewater. The adsorption experiments demonstrated that the maximum adsorption capacity of LmPATT-reD113 for Cu (II) was 191.94 mg/g, which was 3.03 times higher than that of the polyacrylic acid resin (D113). LmPATT-reD113 and D113 had penetration times of 200 and 150 min, and equilibrium times of 1000 and 675 min, respectively. Column adsorption results showed LmPATT-reD113 outperformed D113. After four adsorption–desorption cycles, LmPATT-reD113 maintained superior performance with a desorption efficiency of 93.23 %. The adsorption kinetics and thermodynamics showed that LmPATT-reD113 to Cu(II) followed the pseudo-second-order kinetic and Langmuir isotherm models, with Δ H , Δ S , and Δ G values of 24.836 kJ/mol, 102.187 J/(mol·K) and −3.092kJ/mol at 298.15 K, respectively. Moreover, the adsorption mechanism was investigated using X-ray photoelectron spectroscopy (XPS) and density-functional theory (DFT), the results showed that the affinity of LmPATT-reD113 for Cu(II) mainly originated from the formation of five-membered rings by C=S and C–N complexed with Cu(II) and the formation of porous structure by O=C–NH molecules through intermolecular hydrogen bonding to promote the adsorption of copper.