Enhancing nanoplastics removal by metal ion-catalyzed ozonation

Abstract

Nanoplastics (NPs), characterized by sizes 99 % in less than 5 min of ozonation (TOD: 30 mg L−1) was confirmed. This fact could imply a new issue under the ozone disinfection conditions by the formation of smaller-size particles. However, in the presence of Co2+ (1 mM), the highest PSNPs ozonation performance was achieved, decreasing the turbidity up to 65 % and achieving 70 % of mineralization in the same ozonation time. The scavenger experiments with methanol confirmed that direct ozonation and catalyst role were responsible for PSNPs degradation, with the generation of •OH being the most dominant catalytic mechanism. Therefore, although single ozonation at disinfection doses reduced the particle size of PSNPs, the catalytic process demonstrated greater efficacy in the total removal of PSNPs. These results highlight the need to further investigate ozonation of NPs intermediates, and the synergic improvements of catalytic ozonation for their mineralization.

Keywords

• Catalytic ozonation
• Metal ions
• Mineralization
• Nanoplastics
• Water treatment