Novel core-shell Fe-UiO-66/silicalite-1 catalysts for efficient degradation of phenolic wastewater

Novel Fe supported core-shell catalysts, composite materials of metal-organic frameworks (UiO-66) and zeolite (Silicalite-1), were designed for efficient catalytic wet peroxide oxidation of phenolic wastewater. The core-shell materials using UiO-66 and Silicalite-1 as the core layer or shell layer were prepared by secondary synthesis method and characterized by SEM, TEM, EDS mapping, XRD and FT-IR. The Fe species (5 wt%) supported core-shell catalysts were prepared by incipient wetness impregnation method. Characterization results certificated the successful preparation of core-shell catalysts, namely, Fe-UiO-66/Silicalite-1 (UiO-66 as the core material) and Fe-Silicalite-1/UiO-66 (Silicalite-1 as the core material). Meanwhile, the Fe supported core-shell catalysts exhibited good catalytic activity with complete phenol degradation and TOC conversions of 66% and 69% over the Fe-UiO-66(25)/Silicalite-1 and Fe-Silicalite-1(25)/UiO-66, respectively, without poisonous by-products detected in the treated wastewater, which further proved the green characteristic of the catalysts. The Fe leaching concentration in the treated solution over the Fe-UiO-66/Silicalite-1 and Fe-Silicalite-1/UiO-66 catalyst is 0.235 ppm and 0.352 ppm which certificated the enhanced stability of the MOFs Fenton catalysts by preparing the supported core-shell catalysts.