Lay Summary

Antidepressant drug residues have become a serious environmental concern, primarily as emerging contaminants of natural waters and wastewaters. This is mainly due to the exponential increase in their prescription and consumption rates in recent years in Western societies, such as EU member countries, where the old stigma associated with the regular use of psychiatric medication by the general population to deal with the mental challenges of everyday life has mostly disappeared today. Unfortunately, large amounts of antidepressant residues ending up in water streams cause severe damage to aquatic life and thus ecological imbalances. Therefore, technical solutions are actively sought to remove this novel class of contaminants from the environment.

This project has offered such a solution, namely a combined extractive and photodegradative water treatment option against tricyclic antidepressant (TCA) contaminants. For the complete separation of TCAs from water, an environmentally friendly nonionic surfactant and benign oils that are typically used as fragrances  or as food flavoring agents were employed to prepare water-in-oil emulsions with nanoscale particles that successfully transported the TCA molecules out of the contaminated water. Then, the resulting emulsions were subjected briefly (for a few tens of minutes up to a few hours) to irradiation using UVC lamps, which led to the complete conversion of organic TCA contaminants into inorganic harmless products, like carbon dioxide, nitrogen, and water. 

These findings constitute a stepping stone towards the development of such integrated technologies against emerging organic contaminants at a larger scale, for example to be employed in wastewater treatment plants worldwide where pharmaceuticals are likely occurring as contaminants.