Interaction of disposable face mask (nano)microplastics with antibiotics: performance and mechanisms

Abstract

The recent COVID-19 pandemic has increased the use of disposable face masks (DFMs). Due to a lack of manufacturing and disposal guidelines, DFMs are among the most common solid wastes worldwide. Common masks are made of polypropylene, which releases (nano)microplastics into the environment as it ages, causing environmental problems. In this work, the mechanism of aging of DFMs under UV radiation is studied and also the interaction mechanism of three antibiotics (ciprofloxacin (CIP), sulfamethoxazole (SMX) and tetracycline (TC)) with the original and UV-aged (nano)microplastics of the mask is investigated. The results showed that aging caused more antibiotics to be adsorbed onto the mask (nano)microplastics, mainly due to the oxygen-containing groups on the surface of the aged-mask. The adsorption capacity of the different layers of the (nano)microplastic mask for antibiotics was in descending order: inner-layer > outer-layer > middle-layer. The adsorption affinity of new and aged mask (nano)microplastics for antibiotics followed SMX > CIP > TC, which positively correlated with the octanol–water partition coefficient (log K_ow) of antibiotics. In general, the adsorption process of antibiotics on (nano)microplastics is mainly governed by membrane-diffusion and distribution mechanisms, and hydrophobic interactions regulate the adsorption process.