Photocatalytic Degradation of Diclofenac Using Al2O3-Nd2O3 Binary Oxides Prepared by the Sol-Gel Method

Abstract

This paper reports the sol-gel synthesis of Al2O3-Nd2O3 (Al-Nd-x; x = 5%, 10%, 15% and 25% of Nd2O3) binary oxides and the photodegradation of diclofenac activated by UV light. Al-Nd-based catalysts were analyzed by N2 physisorption, XRD, TEM, SEM, UV-Vis and PL spectroscopies. The inclusion of Nd2O3 in the aluminum oxide matrix in the 10–25% range reduced the band gap energies from 3.35 eV for the γ-Al2O3 to values as low as 3.13–3.20 eV, which are typical of semiconductor materials absorbing in the UV region. γ-Al2O3 and Al-Nd-x binary oxides reached more than 92.0% of photoconverted diclofenac after 40 min of reaction. However, the photocatalytic activity in the diclofenac degradation using Al-Nd-x with Nd2O3 contents in the range 10–25% was improved with respect to that of γ-Al2O3 at short reaction times. The diclofenac photoconversion using γ-Al2O3 was 63.0% at 10 min of UV light exposure, whereas Al-Nd-15 binary oxide reached 82.0% at this reaction time. The rate constants determined from the kinetic experiments revealed that the highest activities in the aqueous medium were reached with the catalysts with 15% and 25% of Nd2O3, and these compounds presented the lowest band gap energies. The experimental results also demonstrated that Nd2O3 acts as a separator of charges favoring the decrease in the recombination rate of electron-hole pairs.

A Generalized Semiempirical Approach to the Modeling of the Optical Band Gap of Ternary Al-(Ga, Nb, Ta, W) Oxides Containing Different Alumina Polymorphs

“…With this aim, we identified several ternary systems of variable composition x MO y + (1 – x )­AlO 1.5 , covering all the ranges of experimental and theoretically estimated optical gap values of alumina polymorphs, − as the most challenging test to our assumptions. However, for the sake of brevity, in this work, we will discuss the results pertaining to a few ternary oxides containing, apart from Al, both sp (Ga) and d-metals (Ta, Nb, and W). ,, Both crystalline ternary polymorphs and amorphous ternary oxides will be taken into account to test the ability of the proposed approach to model reliably the experimentally derived band gap values.…”

Enhanced Removal and Toxicity Decline of Diclofenac by Combining UVA Treatment and Adsorption of Photoproducts to Polyvinylidene Difluoride

“…Both processes are accompanied by high operating expenses like pre-treatment and post-treatment [ 20 , 21 , 22 ]. Advanced oxidation processes (AOPs, like photocatalysis, photo-Fenton, ozonation or electrochemical oxidation) are highly discussed and investigated processes to eliminate micropollutants from water [ 23 , 24 , 25 , 26 ]. Reactive oxygen species (hydroxyl radicals, hydrogen peroxide, ozone, and superoxide anion radicals) are generated and completely mineralize micropollutants with a low selectivity to carbon dioxide, water, and inorganic ions or acids.…”

Recent advances in removal of pharmaceutical pollutants in wastewater using metal oxides and carbonaceous materials as photocatalysts: a review

“…dioxide-polyethersulfone (PES) membrane, 712 A l2 O 3 -Nd 2 O 3 , 713 and TiO 2 -zeolite 714 based photocatalysts have also been evaluated for the photocatalytic degradation of diclofenac.…”

“…In view of this, the following photocatalytic methods have been used in the removal of diclofenac from water. 665–748…”

“…The photocatalyst also displayed excellent repeatability and better stability over repeated reaction cycles. Fe 3 O 4 /Ti x O y /activated carbon, 709 Fe 3 O 4 (nanosphere)/Bi 2 S 3 (nanorod)/BiOBr (nanosheet) 710 TiO 2 @ZnFe 2 O 4 /Pd, 711 nanotubular titanium dioxide–polyethersulfone (PES) membrane, 712 A l2 O 3 –Nd 2 O 3 , 713 and TiO 2 –zeolite 714 based photocatalysts have also been evaluated for the photocatalytic degradation of diclofenac.…”