Integrated nanostructures of CeO2/attapulgite/g-C3N4 as efficient catalyst for photocatalytic desulfurization: Mechanism, kinetics and influencing factors

Abstract

CeO2/attapulgite (ATP)/g-C3N4 nanocomposite materials were prepared by a facile electrostatic-induced self-assembly method. In this ternary structure, ATP skeleton effectively increases the surface area with abundant adsorption sites and prevents g-C3N4 from restacking while the g-C3N4 extends the adsorption edge of the CeO2 to visible region and facilitates the separation of electrons and holes via the formation of CeO2/g-C3N4 heterojunctions. The mass ratio of CeO2 and g-C3N4 in the CeO2/ATP/g-C3N4 nanocomposites was adjusted so that r=MCe/(MCe+Mg) was 0.1, 0.3, 0.5, 0.7, 0.9, respectively. Benefiting from the synergetic effect, 98% of dibenzothiophene (DBT) in the model oil was converted within 3h by using CeO2/ATP/g-C3N4 (r=0.5) as the photocatalyst under visible light irradiation. Moreover, the CeO2/ATP/g-C3N4 composite had no detectable loss of photocatalytic activity after eight cycles, indicating excellent recyclability as was also supported by in-situ TEM heating measurement. The OH radicals and holes are responsible for the photocatalytic oxidation as elucidated by the test of electron spin resonance (ESR) and gas chromatography–mass spectrometry (GC–MS). Reaction kinetics and influencing parameters, including catalyst dosage and H2O2 amount, on the desulfurization were further investigated.