Modification of ZIF-8 on bacterial cellulose for an efficient selective capture of U(VI)

Abstract

MOFs are confined to solid supports to overcome their inherent disadvantages of lightweight and submicron size, which pose challenges to the adsorption operation. ZIF-8 nanoparticles can be loaded onto bacterial cellulose (BC) in a simple manner, and subsequently carbonized at 700 °C to obtain a larger specific surface area (expressed as BC@ZIF-8 carbon aerogels (BZCA). SEM indicates that ZIF-8 was successfully self-assembled on bacterial cellulose. Various characterization techniques (SEM, TEM, FT-IR, XRD, BET, and XPS) indicated that BZCA had been successfully prepared, with a large specific surface area (220.45 m2/g) and sufficient functional groups (-NH-, -OH, Zn–O, N–O, and C = N-). The relationship of the adsorption of BZCA to UO22+ with both contact time and initial concentration was then studied. Results showed that the adsorption of UO22+ followed a pseudo-second-order kinetic model (R2 = 0.999). After calculation, the maximum adsorption capacity of BZCA was 535 mg/g, which was comparable to or better than that of other adsorbents. The kinetic analysis disclosed that 70 min was enough for BZCA to reach the adsorption equilibrium. The adsorption mechanism of the prepared adsorbent on UO22+ was studied by FTIR and XPS.