黄原胶改良膨润土对Sr2+和Cs+的吸附特性探究

he safe and efficient disposal of radioactive waste remains one of the critical challenges in the field of environmental science. The development of cost-effective, green, and environmentally friendly adsorbent materials for the treatment of nuclear wastewater has emerged as a key technological issue to ensure environmental safety and promote sustainable development. In this study, the natural biopolymer xanthan gum (XG) was employed to modify Gaomiaozi bentonite (GMZ), resulting in the preparation of xanthan gum-modified Gaomiaozi bentonite (XG/GMZ). The adsorption behavior and underlying mechanisms of XG/GMZ toward representative radionuclides, Sr and Cs, in nuclear wastewater were systematically investigated. The effects of initial radionuclide concentration, adsorption time, and solution pH on the adsorption performance of XG/GMZ were investigated. To elucidate the modification mechanism and microstructural changes, a combination of characterization techniques, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM), was employed. The results indicate that both the total adsorption capacity and ion-exchange capacity of XG/GMZ for Sr and Cs increase with rising initial concentrations of the radionuclide solutions, eventually approaching equilibrium at higher concentrations. Mechanistic analysis revealed that ion exchange is the dominant adsorption mechanism, particularly under low-concentration conditions, where its contribution is more pronounced. When the radionuclide concentration exceeded 8 mmol/L, the adsorption capacity of XG/GMZ bentonite was significantly enhanced. Further investigation revealed that the optimal dosage of XG/GMZ for Sr adsorption was 1.5%, while that for Cs was 0.25%. During the adsorption of Sr, XG/GMZ exhibited a higher adsorption capacity and faster adsorption kinetics. In contrast, although the adsorption rate for Cs did not improve significantly, the overall adsorption performance was markedly enhanced. Moreover, XG/GMZ bentonite demonstrated excellent acidbase resistance over a broad pH range, indicating its strong adaptability for application in complex hydrochemical environments.