Immobilization of in situ generated Fe⁰-nanoparticles in tripolyphosphate-crosslinking chitosan membranes for enhancing U(VI) adsorption

The in situ generated Fe⁰-nanoparticles (FeNPs) were incorporated to tripolyphosphate-crosslinking chitosan membranes (CS-Fe) for enhancing U(VI) adsorption. Results indicated that chitosan could improve the dispersion of FeNPs, while phosphate groups from CS-Fe provided the main sorption sites. The FeNPs offered additional sorption sites, as evidenced by the perfect fitting of bi-site Langmuir model for the sorption isotherms. The adsorption kinetic followed pseudo second-order model, indicating chemisorption as the rate-controlling step. The enhanced adsorption of U(VI) for CS-Fe (q_m,cal = 208.8 mg/g against q_m,cal = 131.6 mg/g for CS) was associated to the redox reaction between the well-dispersed FeNPs and U(VI). (author)