Construction of stable perovskite-type LaFeO3 particles on polymeric resin with boosted photocatalytic Fenton-like decaffeination under solar irradiation

Abstract

In this work, LaFeO3 perovskite particles were successfully immobilized on the commercial polymeric resin (Amberlite XAD-4) to yield a novel and applicable photocatalyst. The prepared catalysts were systematically characterized by XRD, XPS, FTIR, SEM, TEM-EDX, UV-DRS, PL and TGA analyses. It is demonstrated that LaFeO3 particles (LFO) with well crystallinity were immobilized onto the surface of resin, leading to the formation of composite LFO/XAD4 catalyst. The signals of La 3d, Fe 2p and O 1s on the composite were further confirmed by the XPS spectroscopy. The photocatalytic, Fenton and photo-Fenton performances of the samples were investigated by degrading caffeine under visible light illumination. Such an immobilization of the LaFeO3 particles onto the resin significantly altered the photocatalytic and photo-Fenton degradation of caffeine; the photo-Fenton degradation rate in the presence of the bare LaFeO3 (41.5%) enhanced to 78.5% after immobilization suggesting that the synergetic effect of adsorption and photocatalysis played a major role in the decaffeination process. Moreover, the increasing LaFeO3 ratio to a certain level over the resin surface greatly improved the degradation which could be resulted in more absorption of light radiation and enhanced transfer of the photo-induced electrons. The photo-Fenton catalytic mechanism under sun light illumination was also discussed in terms of solution pH, H2O2 concentration, co-existing anions and scavengers. In addition, reusability tests revealed that the immobilization also eases the separation and stability of the catalyst which can be effectively used until sixth cycle. The degradation pathways of photo-Fenton degradation of CAF were proposed. This work gives an insight into the usage of polymeric resins as potential supporting materials in the photocatalysis field.