One-pot synthesis of La-Fe-O@CN composites as photo-Fenton catalysts for highly efficient removal of organic dyes in wastewater

The improvement of catalytic efficiency of catalyst is a challenging topic especially for solid catalyst that has restrained surface to contact reactants. Herein, we reported an effective way to improve the catalytic efficiency by designing composites catalyst (to induce synergistic effect) and performing the reaction under united technologies (to make cooperative contribution). As a model case, La-Fe-O mixture (abbreviated as LFO) and graphitic carbon nitride (abbreviated as g-CN) composites (LFO@CN-n, where n means the molar ratio of the precursors of LFO to g-CN) were synthesized and used as photo-Fenton catalysts for oxidation removal of dyes in wastewater. Results showed that LFO@CN-16, with g-CN loading of 69%, has the properties of both LFO and gCN, and exhibits high efficiency for dyes oxidation in the presence of H2O2 and light irradiation, with 98% rhodamine B conversion within 25 min, for example. Mechanistic studies suggested that center dot OH radicals produced from H2O2 are the reaction intermediates, which participate both in the Fenton- and the photo-catalytic processes. Moreover, the catalyst can be reused for at least 5 cycles with no appreciable loss of activity, and can be applied to various organic dyes containing benzene-like cyclic structures with high efficiency.