Photodegradation of sodium naproxen and oxytetracycline hydrochloride in aqueous medium using as photocatalysts Mg-Al calcined hydrotalcites

• Published in: Journal of photochemistry and photobiology. A, Chemistry. Chemistry., 2014-03, Vol.277, p.82-89
• Main Authors: Jácome-Acatitla, G., Tzompantzi, F., López-González, R., García-Mendoza, C., Alvaro, J.M., Gómez, R.
• Format: Article
• Language: English
• Subjects: Fluorescence probe; MgAl calcined LDHs; Oxytetracycline hydrochloride photodegradation; Oxytetracycline TOC analysis; Sodium naproxen photodegradation; Sodium naproxen TOC analysis
• ISSN: 1010-6030; 1873-2666
• DOI: 10.1016/j.jphotochem.2013.12.014

UV-light irradiation to the reactant system containing pharmaceutical compounds and Mg-Al calcined hydrotalcites as photocatalysts, provokes the generation of electron–hole pairs, in which the electron is delocalized towards the charge electro deficient Al3+and the hole allows the formation of OH radicals, giving way thus to the photooxidation of the drugs. •MgAl LDHs with different MII/MIII molar ratio, were synthesized by the co-precipitation method.•MgAl catalysts were obtained by thermal decomposition (450°C) of the respective LDH's.•MgAl calcined hydrotalcites were proved for first time in the photodegradation of sodium naproxen and oxytetracycline hydrochloride in aqueous medium.•The efficient mineralization of sodium naproxen and oxytetracycline hydrochloride by the MgAl calcined hydrotalcites was observed. Layered double hydroxides (LDH) MgAl with different MII/MIII ratios were synthesized by the co-precipitation method. The materials were calcined at 723K and characterized by XRD, nitrogen adsorption, UV–vis DRS and FTIR. The catalytic activity of the calcined solids was tested in the photodegradation of two water soluble pharmaceuticals: sodium naproxen, a non-steroidal anti-inflammatory, and oxytetracycline hydrochloride, a tetracycline family antibiotic. The synthesized solids mineralize rapidly both pharmaceuticals using UV as light source and after 5h of reaction, about 90% of sodium naproxen and 70% of oxytetracycline hydrochloride were degraded by the catalyst with the higher photoactivity. Comparative studies were performed with TiO2 P25 commercial semiconductor. The results showed that the MgAl calcined hydrotalcites have a greater photoactivity in the degradation of the target molecules than TiO2. Fluorescence spectroscopy study suggests the generation of hydroxyl radicals as the oxidative species of the target molecules when MgAl calcined hydrotalcites are irradiated.