Highly efficient photocatalytic elimination of phenol and chlorinated phenols by CeO2/MgAl layered double hydroxides

Abstract

Mg/Al layered double hydroxides (LDHs) were synthesized by a simple, environment friendly method; then, cerium oxide was incorporated following two different procedures. Thus obtained bifunctional basic/semiconducting catalysts were characterized by several techniques, such as XRD, SEM/EDS, chemical analysis and N2 physisorption, to investigate their crystalline structure, morphology, CeO2 content and textural properties. The band gap energy was determined to be ∼3.2eV. The photocatalytic properties of the Ce–Mg–Al system were tested for the first time for the degradation, under UV irradiation, of three major pollutants: phenol, 4-chlorophenol and 2,4,6-trichlorophenol. The results obtained with phenol, which is the most recalcitrant of the studied molecules, were by far superior to those obtained with benchmark Degussa P25 TiO2 photocatalyst tested under the same conditions. Furthermore, a charge-transfer mechanism is proposed as the initiator of the photocatalytic degradation of phenol and 4-chlorophenol.