Assessment of the efficiency of photocatalysis on tetracycline biodegradation

International audienceThe use of photocatalysis to improve the biodegradability of an antibiotic compound, tetracycline (TC) was investigated. The toxicity of TC and its degradation products were also examined. The Sturm test was conducted to assess the biodegradability of by-products formed in the photocatalytic process. The toxicity of tetracycline and its by-products was evaluated using a dehydrogenase inhibition test, which showed a decrease in toxicity during photocatalysis. However, the Sturm test results indicated that, like tetracycline, the by-products are not biodegradable. Possible structures of these by-products were determined using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS). It was found that, during the photocatalytic process, the TC aromatic ring is not opened and the structure of the identified by-products is quite similar to that of tetracycline. A reaction pathway is proposed. (C) 2012 Elsevier B.V. All rights reserved

Photocatalytic degradation of estradiol under simulated solar light and assessment of estrogenic activity

International audienceThe ability of nanostructured titanium materials developed in the FP7/EU collaborative Clean Water project to photocatalytically degrade pollutants was tested, using 17 beta-estradiol (E2) as the model compound. The photocatalytic degradation of E2 was carried out under simulated solar light (both the UV part (280-400 nm) and full spectrum (200 nm-30 mu m)). The efficiency of the process was assessed using several indicators including the conversion yield, the mineralization yield, the formation of by-products and their endocrine disrupting effects. The newly synthesized catalysts significantly degraded E2 and their efficiency was found to depend on the irradiation wavelength range. Some of the intermediates formed during the photocatalytic treatment with ECT-1023t and Evonik P25 were identified and their estrogenic effect was evaluated in vivo using the ChgH-GFP transgenic medaka line. This analysis confirmed that in the structure of the identified by-products, the phenol group is not destroyed and that the estrogenic effect is still present in the corresponding solution. The persistence of the estrogenic effect after the photocatalytic treatment is hypothesized to be due to the presence of the phenol group in the by-products. (C) 2014 Published by Elsevier B.V