PROGRAMME

This work aims at evaluating the fate of polystyrene (PS) microplastics along Fenton oxidation. Experiments were carried out under relatively severe operating conditions (80 ºC) given the high persistence of these solids to oxidation. Slight mass losses (up to 10%) were found after the Fenton treatment of microplastics in the micro range (100–250 m). Nevertheless, the particles clearly suffered important changes in their surface due to the introduction of oxygen groups, which made them more acidic and hydrophilic. These surface alterations completely changed the sorption properties of microplastics. For instance, their adsorption capacity for diclofenac was sharply decreased from 102 to 28 g g-1. Apart from surface modifications, microplastics clearly decreased their size after Fenton oxidation, which was more evident in the 50–100 m range. To further evaluate the oxidation yield of PS microplastics upon Fenton oxidation, particles in the sub-micro range (140 nm) were treated. Notably, up to 75% TOC mineralization was achieved, which proved that microplastics can be completely oxidized to CO2 upon Fenton oxidation. Finally, the biodegradability of the dissolved compounds leached from oxidized microplastics was evaluated. Remarkably, bacterial growth efficiency was higher in the solution coming from the oxidized PS microplastics than that of the fresh one.