N-doped titanium dioxide for mixture of parabens degradation based on ozone action and toxicity evaluation: Precursor of nitrogen and titanium effect

Abstract

Degradation of a mixture of five parabens was evaluated using photocatalytic oxidation, photolytic ozonation and photocatalytic ozonation, being applied UVA radiation and N-TiO2 doped catalysts. Photocatalytic oxidation was not able to eliminate parabens, achieving less than 10 % of removal. The use of ozone and UVA radiation resulted in total contaminants abatement with a transferred ozone dose (TOD) of 46.2 mg L−1. Photocatalytic ozonation also totally removed parabens but with a considerable reduction of TOD required along with higher COD and TOC removals, up to 35.7 % and 34.1 %, respectively, for the best catalyst (ammonia-doped 10 % N-TiO2). Toxicity tests were conducted using three different species. Lepidium sativum seeds had higher growth indexes (GIs) when exposed to solutions treated by photocatalytic ozonation reactions. Nevertheless, Allivibrio fischeri and Corbicula fluminea demonstrated lower toxic responses to photolytic ozonation treated solution which may be related with the different by-products formed.