Removal of Hexavalent Chromium by Electrospun Silicon Dioxide Nanofibers Embedded with Copper-Based Organic Frameworks

Abstract

A novel adsorbent copper-based organic skeleton/silicon dioxide (HKUST-1/SiO2) composite nanofiber, which can effectively remove Cr (VI) under synergistic action, has been prepared by embedding growth technique. This adsorbent was characterized by embedded growth of HKUST-1 on inorganic SiO2 electrospun nanofibers, which can remove Cr (VI) in water with the help of adsorption and membrane separation under synergistic action. The results revealed that HKUST-1 was successfully embedded between the pores of SiO2 electrospun nanofibers. The factors affecting the adsorption performance of the composite nanofibers were studied, and the result displayed that the concentration of Cr (VI) solution was 120 mg/L, the best range for pH was 3~7, the adsorption equilibrium was about 45 min, and the maximum adsorption amount was 62.38 mg/g. Compared with the SiO2 fiber without HKUST-1 growth, the adsorptive property of the composite fiber was significantly increased by 15 mg/g. The adsorption process was spontaneous and belonged to the heat absorption reaction, which was consistent with Langmuir adsorption and the pseudo-second-order kinetic model. In addition, HKUST-1/SiO2 NFs can be used for the recovery of chromium resources because the HKUST-1/SiO2 NFs captured Cr (VI) can be calcined and recovered in the later stage, which reduces the consumption of desorption liquid, simplifies the recovery steps, and is conducive to energy saving and emission reduction. Therefore, HKUST-1/SiO2 NFs are expected to be applied in the field of hexavalent chromium wastewater purification and resource recovery.