Enhanced selective adsorption properties of graphene oxide modified with bi-ligand triazole-thione compounds for Cu(Ⅱ) and its mechanism

A novel composite material, MIBuXATT@GO, was synthesized by functionalizing graphene oxide (GO) with a bi-ligand triazole-thione ligand, 3-methyl isobutylxanthate-4-amino-1,2,4-triazole-5-thione (MIBuXATT), for the efficient adsorption of Cu(II) ions. This modified material served as an adsorbent to enhance the selective adsorption of Cu(II) from wastewater by synergistically combining physical and chemical adsorption mechanisms. MIBuXATT@GO was characterized by XRD, SEM/EDS, and FTIR. Under the optimal conditions (pH=4, adsorbent dosage 250 mg/L, contact time 60 min), the maximum adsorption capacity of Cu(II) by the material is 97.24 mg/g, which is 1.3 times higher than that of GO. Meanwhile, the adsorption process of MIBuXATT@GO to Cu(II) is characterized as spontaneous endothermic chemisorption. Furthermore, the experimental results regarding metal ion adsorption selectivity indicate that MIBuXATT@GO exhibits superior selectivity for Cu(II) compared to Mn(II), Zn(II), Co(II), and Ni(II), which is an improvement over GO. The results indicate that MIBuXATT@GO is a promising adsorbent for the removal of Cu(II) ions from aqueous solutions, offering high capacity, rapid kinetics, and excellent selectivity. The adsorption mechanism was elucidated through FTIR, UV, XPS, and DFT calculations, revealing the critical role of the thiocarbonyl and triazole-thione functional groups in Cu(II) coordination. This work provides a new strategy for designing efficient adsorbents for heavy metal ion removal.