Functionalization of Xonotlite Composite with Amidoxime Groups for the Sorption of Cu (Ⅱ) Ion

摘要

The xonotlite was synthesized from eggshell waste and modified with toluene diisocyanate (TDI). The xonotlite and amidoxime-modified xonotlite were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). FTIR revealed that the amidoxime group was successfully grafted onto the xonotlite. Factors affecting adsorption such as solution pH, adsorbent dose, contact time, and initial concentrations were set up to improve the adsorption performance. The adsorption of Cu (II) on all the adsorbents was well-described by the Freundlich model and pseudo-second-order model. The amidoxime-modified xonotlite showed rapid removal efficiency and reached equilibrium in 45 min at the pH of 5. The maximum adsorption capacities for Cu (II) (713.2 mg/g) on the modified xonotlite were 35.8% higher than that on the unmodified xonotlite. The existence of competing ions like K(I) and Na(I) had little effect on the Cu(II) removal efficiency. Therefore, the modified xonotlite could be used as a feasible adsorbent for the removal of Cu (II) in treating wastewater.