Floating ZnO nanoparticles-coated micro glass bubbles for the efficient photodegradation of micropollutants in water

Abstract

This study proposes a novel approach to fabricate floatable ZnO-coated micro glass bubbles (MGBs) using cold plasma as a surface modification method. Pre-treating MGBs with cold plasma enhances surface wettability and roughness and the adhesion of ZnO nanoparticles on their surface. Based on the results, the photodegradation performance of ZnO-coated MGBs under simulated solar light is directly affected by the cold plasma pre-treatment time, the solution depth, and the amount of the floatable material on the contaminated solution surface. Furthermore, a higher concentration of zinc acetate in the coating process led to larger ZnO particle sizes and increased coating efficiency, but it resulted in lower coating stability on the surface of the MGBs. Remarkably, ZnO-coated MGBs under 10 h of simulated solar radiation achieved almost 100 % removal of a mixture containing seven different micropollutants (caffeine, sulfamethoxazole, trimethoprim, carbamazepine, atrazine, naproxen, and ibuprofen) commonly detected in aquatic environments. Finally, ZnO-coated MGBs demonstrate excellent reusability and stability, suggesting their viability as a sustainable option for efficiently degrading organic pollutants in water.