Interactions between titanium dioxide nanoparticles and polyethylene microplastics: Adsorption kinetics, photocatalytic properties, and ecotoxicity

Abstract

The present study investigated the adsorption mechanism of titanium dioxide nanoparticles (nTiO2) on poly-ethylene microplastics (MPs) and the resulting photocatalytic properties. This effort was supported by ecotoxi-cological assessments of MPs with adsorbed nTiO2 on the immobility and behaviour of Daphnia magna in presence and absence of UV irradiation. The results showed that nTiO2 were rapidly adsorbed on the surface of MPs (72% of nTiO2 in 9 h). The experimental data fit well with the pseudo-second order kinetic model. Both suspended nTiO2 and nTiO2 immobilized on MPs exhibited comparable photocatalytic properties, with the latter showing a lower effect on Daphnia mobility. A likely explanation is that the suspended nTiO2 acted as a ho-mogeneous catalyst under UV irradiation and generated hydroxyl radicals throughout the test vessel, whereas the nTiO2 adsorbed on MPs acted as a heterogeneous catalyst and generated hydroxyl radicals only locally and thus near the air-water interface. Consequently, Daphnia, which were hiding at the bottom of the test vessel, actively avoided exposure to hydroxyl radicals. These results suggest that the presence of MPs can modulate the phototoxicity of nTiO2 - at least the location at which it is active - under the studied conditions.

Keywords

Adsorption; Freshwaters; Microbeads; Nanoparticles; Reactive oxygen species

Published in

Chemosphere
2023, volume: 329, article number: 138628
Publisher: PERGAMON-ELSEVIER SCIENCE LTD

SLU Authors

• Bundschuh, Mirco

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    
  • University of Kaiserslautern-Landau (RPTU)

UKÄ Subject classification

Environmental Sciences

Publication identifier

• DOI: https://doi.org/10.1016/j.chemosphere.2023.138628

Permanent link to this page (URI)

https://res.slu.se/id/publ/122331