Photocatalytic Degradation of Diclofenac Using Al 2 O 3 -Nd 2 O 3 Binary Oxides Prepared by the Sol-Gel Method

• Published in: Materials Vol. 13; no. 6
• Main Authors: Casillas, José Eduardo, Campa-Molina, Jorge, Tzompantzi, Francisco, Carbajal Arízaga, Gregorio Guadalupe, López-Gaona, Alejandro, Ulloa-Godínez, Sandra, Cano, Mario Eduardo, Barrera, Arturo
• Format: Journal Article
• Language: English
• Published: Switzerland 16.03.2020
• Subjects: band-gap energy; photodegradation; Al2O3-Nd2O3; diclofenac; structure; sol-gel
• ISSN: 1996-1944; 1996-1944

This paper reports the sol-gel synthesis of Al O -Nd O (Al-Nd- ; = 5%, 10%, 15% and 25% of Nd O ) binary oxides and the photodegradation of diclofenac activated by UV light. Al-Nd-based catalysts were analyzed by N physisorption, XRD, TEM, SEM, UV-Vis and PL spectroscopies. The inclusion of Nd O in the aluminum oxide matrix in the 10-25% range reduced the band gap energies from 3.35 eV for the γ-Al O to values as low as 3.13-3.20 eV, which are typical of semiconductor materials absorbing in the UV region. γ-Al O 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- with Nd O contents in the range 10-25% was improved with respect to that of γ-Al O at short reaction times. The diclofenac photoconversion using γ-Al O 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 Nd O and these compounds presented the lowest band gap energies. The experimental results also demonstrated that Nd O acts as a separator of charges favoring the decrease in the recombination rate of electron-hole pairs.