A stable metal-organic framework nanofibrous membrane as photocatalyst for simultaneous removal of methyl orange and formaldehyde from aqueous solution

Abstract

A stable metal-organic framework (MOF) nanofibrous membrane (NFM) was successfully fabricated by in situ growing H3PW12O40 (PW12) @UiO-66 crystals onto crosslinked polyacrylic acid (PAA)-poly (vinyl alcohol) (PVA) nanofibers prepared through electrospinning. Characterization with High-angle annular dark field-scanning transmission electron microscopy (HAADF-STEM), Fourier transform infrared (FT-IR), Powder X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) confirmed that the crystallinity and structure of PW12@UiO-66 crystals maintained well on the PAA-PVA NFM. The as-prepared PAA-PVA/PW12@UiO-66 NFM can be used as a photocatalyst for simultaneous photocatalytic degradation of methyl orange (MO) and formaldehyde (FA) in aqueous solution. The possible mechanism was that electrons transferred from FA to MO via PAA-PVA/PW12@UiO-66 NFM, made the photodegradation of MO driven by the reductive pathway. At the same time, FA was oxidized due to the loss of electrons. PAA-PVA/PW12@UiO-66 NFM presented a satisfactory stability and reusability, mainly because the partially crosslinked PAA-PVA NFM can provide sufficient carboxyl groups for anchoring PW12@UiO-66 particles. Due to no separation process was needed for electrospun NFM after each photocatalytic cycle, the reuse process of PAA-PVA/PW12@UiO-66 NFM can be conducted more conveniently and rapidly compared with powdered MOFs photocatalysts. This work will be useful for the design of MOFs NFMs photocatalysts based on electrospinning applied to comprehensive treatment of organic pollutant wastewater.