Adsorption and photo-Fenton catalytic degradation of organic dyes over crystalline LaFeO-doped porous silica.

LaFeO (LFO)-doped mesoporous silica (HPS) (HPS-LFO with theoretical LFO/silica molar ratio = 0.075, 0.15, 0.3) was successfully prepared impregnation of metal ions into the porous silica HPS-0LFO support and subsequent calcination. The characterization studies suggest that increasing the doping of LFO, which exhibited a particle size of ∼10-15 nm, in the silica support led to a reduction in surface area and bandgap of the resulting catalyst. The use of HPS-0.15LFO yielded a superior removal rate (98.9%) of Rhodamine B (RhB), thanks to the effective dark adsorption and visible light-induced photo-Fenton degradation, both of which were greater than those of pure LFO crystals. This enhancement could be explained by the unique properties of the mesoporous silica support. In particular, the wide-opening mesopores created a large surface area to dope LFO as active sites and minimize diffusion of RhB into pores during the photo-Fenton reaction. The photo-Fenton catalytic degradation of RhB could reach 98.6% within 90 min exposure to visible light irradiation under optimized conditions: RhB concentration = 10 mg L, catalyst dosage = 1 g L, pH = 6 and HO = 15 mM. Moreover, the recycle and reuse test proved the good stability and repetitive use of HPS-0.15LFO for high performance RhB removal.