Preparation of UiO-66/chitosan and its adsorption mechanism of U(VI)

Uranium mining and smelting processes produce a large amount of low-concentration uranium wastewater, which endangers the ecological environment and human health. It is urgent to remove uranium (VI) from uranium-containing wastewater. In this study, UiO-66 and chitosan (CS) were used as raw materials to prepare UiO-66/CS new composite materials by cross-linking method. Through static adsorption experiments, different pH values, adsorbent dosage, adsorption time and initial uranium concentration were investigated. The influence of external factors on U(VI) removal rate. The UiO-66/CS material was characterized and analyzed by scanning electron microscopy (SEM), Fourier infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), etc., revealing the mechanism of adsorbent removal of U(VI). The results show that: when the initial uranium concentration is 5 mg/L, the temperature is 298 K, the pH is 5, the dosage is 0.15 g/L, and the adsorption time is 120 min, the removal rate of U(VI) by UiO-66/CS can reach 90.24%. The adsorption process conforms to the quasi-second-order kinetic model and Freundlich isotherm adsorption model. The adsorption and removal mechanism of U(VI) is mainly the complexation of —NH, —COOH, Zr—O,—OH and other functional groups with U(VI).