Adsorption performance of polyhydroxy-aluminum-modified coal-series kaolin for fluoride removal
SALTSUUD Sitegule
ZULCHIN Hairihan
MUSCHIN Tegshi
Abstract：Objective Kaolin,characterized by its unique layered structure and strong ion exchange capacity,has been widely used in envi-ronmental pollution prevention and wastewater treatment.However,coal-serieskaolin,often discarded as solid waste during coal processing,remains severely underutilized.To enhance its tilization rate,modification treatments are necessary.
Methods In this study,coal-series kaolin from Inner Mongolia was ball-milled and impregnated with alkali,followed by modifi-cation in a polyhydroxy-aluminum solution,which was prepared using different ratios of Al3+and OH-.The adsorption capacity of modified kaolin for fluoride(F-)was evaluated.Additionally,influencing factors,including adsorption time,initial solution pH,initial concentration of F-,and the adsorption isotherms and kinetics,were examined to analyze the effects of adsorption conditions on its adsorption performance.
Results and Discussion The kaolin samples after polyhydroxy-aluminum modification were characterized byX-ray diffraction(XRD),N2 adsorption-desorption,transmission electron microscopy(TEM),and energy dispersive spectroscopy(EDS).The results showed that the specific surface area of modified kaolin increased significantly while its structure remained largely unchanged.The removal rate for F-reached 95％at a F-concentration of 10 mg/L,20 times higher than that of raw kaolin(5％),demonstrating enhanced F-adsorption performance.Adsorption condition analysis revealed that the optimal F-adsorption perfor-mance occurred at a solution pH of 7.0 to 8.0,a thermodynamic temperature of 298 K,a shaking time of 100 min,and a shak-ing frequency of 200 r/min.The adsorption mechanism was also explored through the evaluation of adsorption kinetics and iso-therm models.The adsorption isotherm data conformed to the Freundlich model,while the adsorption kinetics followed the pseudo-second-order model.
Conclusion In this study,a polyhydroxy-aluminum modification method is used to enhance the F-adsorption capacity for coal-serieskaolin.This approach has the advantage of simple preparation process,low cost,low energy consumption,and environ-mental friendliness.It can effectively improve the adsorption performance of coal-series kaolin for F-ion from water.This approach enhances the effective utilization of coal-series kaolin waste resources and provides a cost-effective adsorbent for treat-ing F--containing water,thereby achieving waste treatment through waste utilization.Future research can explore the recycling potential of polyhydroxy-aluminum-modified kaolin adsorbents to reduce water treatment costs.
Keywords：coal-series kaolinpolyhydroxy-aluminum modificationfluoride removaladsorption performance
Publication Date：2025-07-01
Online Publishing Date：2026-05-22(First online date of this platform, not the publication date of the document)
Pages：14( 160-173 )