REMOVAL OF POLYSTYRENE NANOPARTICLES FROM WATER BY PHOTO-FENTON OXIDATION

GARCÍA, JORGE; DI LUCA, CARLA; ORTIZ, DAVID; MUNOZ, MACARENA; CARBAJO, JAIME; MARTÍNEZ DE PEDRO, ZAHARA; CASAS, JOSÉ A.

Buenos Aires

Congreso; 11th WORLD CONGRESS OF CHEMICAL ENGINEERING (WCCE11); 2023

The ubiquitous occurrence of micro- and nanoplastics (MNPs) in the environment represents a high risk for the ecosystems, as they have been detected throughout the entire trophic chain given their tiny size1. Water is considered the main vector for the introduction of these particles in the environment. Particularly, wastewater treatment plants (WWTPs) are a key route in the life cycle of plastic particles. Since WWTPs are not designed with the purpose of eliminating these persistent pollutants, they act as sink but also a source of these solids into the environment2. Accordingly, research into technologies that allow the complete removal of MNPs from water is crucial. Advanced Oxidation Processes (AOPs) appear as promising alternatives, but they have been scarcely investigated for such goal so far. Photocatalysis has received major attention but is strongly limited due to the long reaction times required to achieve the degradation of plastic particles and the difficult photocatalyst recovery3. In this work, the application of photo-Fenton process for the removal of polystyrene (PS) nanoparticles under ambient conditions has been investigated.Oxidation tests were carried out in an immersion-wall batch jacketed photoreactor (0.7 L) equipped with a 200 W/m2 medium pressure lamp with a temperature control unit. A complete operating condition study was carried out considering the reactor temperature, dose of iron, H2O2 concentration and the initial concentration of PS nanospheres (D0 = 140 nm). Under optimized conditions (T = 25ºC, [Fe3+]0 = 10 mg/L, pH0 = 3, [H2O2]0 = 130 mg/L (5 doses, 1 every 30 min), [PS]0 = 20 mg/L), complete nanoplastics elimination was achieved after 150 min, which was confirmed by TEM and turbidity analyses. Furthermore, almost total mineralization (XTOC > 98%) was reached at the end of the experiment (150 min), confirming the complete removal of dissolved organic intermediates from water. Fig. 1 displays the evolution of TOC concentration together with the images of the reactor al initial time (1) and after 150 min of photo-Fenton treatment (2). These results demonstrate the high effectiveness of photo-Fenton process for nanoplastics removal and open the door for further research in this field, which could be interesting for practical application in the obtention of high-quality reclaimed water at WWTPs.