Highly efficient and selective removal of U(VI) from acidic aqueous solution by chitosan/fluorapatite composite

Chitosan (CS) and natural fluorapatite (FAP) were utilized as raw materials to produce chitosan-natural fluorapatite (CS/FAP) by the blending and crosslinking method. The adsorption capacity of CS/FAP was 243.79 mg/g under the conditions of pH 3, initial U(VI) concentration of 10 mg/L and CS/FAP dosage of 0.2 g/L. Compared to single fluorapatite, CS/FAP exhibits a broader pH range(2–7) and demonstrates exceptional adsorption performance, as well as selective adsorption capabilities. Additionally, it can be easily regenerated. The removal mechanism of U(VI) by CS/FAP involves surface complexation, with phosphate groups playing a pivotal role. Consequently, the development of CS/FAP expands the potential applications of fluorapatite in treating uranium-containing wastewater.