Adsorption performance and mechanism of g-C3N4/CS composite for U（Ⅵ） from aqueous solution

Aimed at the problem of environmental uranium pollution caused by uranium-containing wastewater generated in the process of nuclear energy development and application， by loading g-C3N4 on chitosan （CS） through the cross-linking method， g-C3N4/CS composite was synthesized and used to remove U（Ⅵ） from aqueous solutions. The surface properties and the interaction mechanism of g-C3N4/CS were analyzed. The results show that when the adsorbent dosage of g-C3N4/CS is 0.2 g/L， mass fraction of g-C3N4 is 20%， adsorption time is 120 min， adsorption temperature is 308 K， and pH is 6， the maximum adsorption capacity of g-C3N4/CS on U（Ⅵ） reaches 324.45 mg/g. The adsorption of U（Ⅵ） by g-C3N4/CS involves a spontaneous endothermic process that follows the Langmuir isotherm model and quasi-second-order kinetic model. The adsorption mechanism of U（Ⅵ） by g-C3N4/CS is primarily attributed to the coordinated complexation of functional groups such as —NH，—OH，C—O，C=O，and C—N. The results of the recycling experiments show that g-C3N4/CS has good reusability.