Development of Photocatalysts for the Degradation of Emerging Contaminants in Water

The presence of emerging contaminants (EC), such as pharmaceuticals, in aqueous media is a serious and unresolved concern. Carbamazepine (CBZ) is a highly persistent antiepileptic drug that is resistant to biodegradation. The effect of CBZ on aquatic life has been evaluated as dangerous.

The use of ZnO as a photocatalyst has been widely used for the degradation of contaminants in water due to its low toxicity, low relative cost and wide bandgap. However, the rapid recombination of photogenerated electrons and holes, which added to photocorrosion, could decrease its photocatalytic activity . Modifying ZnO with metals allows to overcome these limitations, as well as visible light absorption.

In the present work, a series of Ce-doped ZnO materials were prepared by a simple wet chemical method at pH 4 (CeZnOa) and pH 8 (CeZnOb). They were characterized by several techniques such as HRTEM, SEM, IR, Raman and photoluminesce. The analyses revealed that the presence of Ce decreases the particle size and a second phase of crystalline CeO₂ appears when the dopant is higher than 0.4 at%.

The photocatalytic activity of the materials was studied for phenol degradation, as model of organic pollutant. Then, to apply the treatment to EC, they were used to study the CBZ degradation with a visible light source.

The crystalline CeZnOb showed a good photocatalytic performance for CBZ degradation (> 50 % after 3 h of visible light irradiation). Moreover, its use decreases the photodissolution of zinc in the aqueous media with respect to the undoped one.