An innovative concentrate-and-destroy approach for wastewater remediation: the double role of BiOBr towards dyes, drugs and polyphenols abatement

Water crisis caused by insufficient water supply and water pollution leads to drought, famine, and death. 1.1 billion people worldwide suffer from poor access to water, and a total of 2.7 billion experience water scarcity for at least one month each year [1]. The treatment of wastewater contaminated by different pollutants is of significant environmental and commercial importance. Due to its efficacy in mineralizing persistent pollutants, heterogeneous photocatalysis has emerged as an important subject of scientific research among numerous water treatment technologies, operating under ambient conditions and degrading many pollutants without the addition of chemical oxidants [2, 3]. However, photocatalytic processes are less effective when used to treat trace concentrations of pollutants in a large volume of contaminated matrices due to: 1) large reactor size (necessity of particular reactor configuration, with consequent increase of the costs), 2) limited light penetration, 3) high energy cost, and 4) difficulties in recycling and reusing the photocatalysts. To facilitate the degradation of traces of pollutants, sophisticated carbon/TiO2 nanotubes composites have been proposed [4, 5] that combine high adsorption capacity and photoreactivity. In the present study, we report our recent results in using BiOBr as an innovative adsorptive photocatalyst able to concentrate on their surface different classes of pollutants (polyphenols, drugs, dyes, etc.) also in the dark and degrade them quantitatively after exposure to solar light irradiation. Moreover, preliminary studies in environmentally friendly floating devices revealed results of great significance.