Synthesis of imidazothiazole Schiff base functionalized silica as an adsorbent for efficient and selective removal of Cu(II) from wastewater: a combined experimental and theoretical investigation

Today's world faces a serious problem of heavy metal contamination in water, which can lead to serious health and environmental problems. In this work, an efficient and selective sorbent is synthesized, characterized, and reported to be used for adsorption of Cu(II) from aqueous solution. The obtained hybrid material was systematically characterized by Fourier-transform infrared spectroscopy, scanning electron microscope, and thermogravimetric analysis were confirmed that the imidazothiazole Schiff base was successfully functionalized the silica surface. Parameters influencing adsorption performance such as pH, time, initial concentration, and temperature were studied in the batch method. The results show that the excellent adsorption capacity of the adsorbent for Cu(II) ions was 110.33 mg/g at 30 min and pH = 6. Furthermore, the Cu(II) adsorption process exhibits a pseudo-second-order kinetic model and a Langmuir adsorption isotherm. Thermodynamic studies confirmed that the reaction was spontaneous and endothermic. Moreover, the adsorbent presents the better adsorption selectivity toward Cu(II). The coexisting cations did not show any competing effect on Cu(II) adsorption, and the adsorption performance did not decline appreciably after 5 cycles. The high adsorption efficiency of the sorbent provides potential applications for copper removal from wastewater. Theoretical methods using density functional theory, quantum theory of atoms in molecules (QTAIM), electron localization function (ELF), and localized orbital locator (LOL) confirm the experimentally discovered results. This study suggests that this adsorbent is an attractive material for the selective removal of Cu(II) from wastewater.