Efficient photocatalysis of CrVI and methylene blue by dispersive palygorskite-loaded zero-valent iron/carbon nitride

Abstract Our previous study reported that a more dispersed palygorskite (Pal) with a multiparous structure can be fabricated from rigid nano-rods by ion beam bombardment. In this study, the new multiparous structure of Pal (MPal) was used to carry a nanocomposite prepared from graphitic carbon nitride (CN) and nano zero-valent iron (NZVI) following a simple thermopolymerisation method for the first time. The as-prepared sample (MPal/NZVI/CN) achieved broader light absorption in the visible light region and low recombination, according to the characterisation results of the UV–vis diffuse reflectance and photoluminescence (PL) spectra of the photocatalysts. The photocatalysis of CrVI and methylene blue (MB) in an aqueous solution by MPal/NZVI/CN revealed that the MPal/NZVI/CN-1:5:6 composites exhibited superior catalytic activity, with CrVI and MB removal efficiencies of 98.48% and 99.2% in 120 min, respectively. Additionally, the reaction rate constants (kCr and kMB) of MPal/NZVI/CN were much higher than those of CN, NZVI/CN, and MPal/CN because the formation of MPal and NZVI composites with CN promoted the separation of photo-generated electron-hole pairs. After four cycles, MPal/NZVI/CN exhibited great photoactivity, which could not only be attributed to the improved dispersion of MPal, but also to the ability of the photo-generated electrons of CN to reduce the FeIII/FeII to Fe0. This study opens new opportunities for modifying photocatalysts using the inorganic nanomaterials readily formed by physical irradiation.