Efficient removal of nanoplastics from synthetic wastewater using electrocoagulation

Résumé : Nanoplastics are emerging contaminants that have now transformed into a worldwide environmental concern. It is a lesser-known fact that several emerging contaminants, such as bisphenol and perfluoro alkylates adsorbing on micro and nanoplastics, could invade the food chain and cause irreversible damage to human health and the environment. Even though wastewater treatment plants (WWTPs) have been around for a long time, their removal strategy needs to be improved since this is one of the main routes that micro and nanoplastics get into the environment. UV deterioration, mechanical stresses, and biological processes cause plastics to break apart and turn into smaller pieces. They get small enough to be called nanoplastics, i.e. 1 um. We studied the removal of nanoplastics from synthetic wastewater using an electrocoagulation process. We used the polystyrene nanoparticles as nanoplastics synthesized from the expanded polystyrene waste (EPS). For studies on electrocoagulation (EC), aluminium electrodes were used in parallel combination at low voltage conditions. We take advantage of the release of gas bubbles from the process to enable the removal from the top by scraping them off. We studied the influence of various process parameters on removing nanoplastics, such as electrode spacing, salt concentration, and applied voltage. We found that a maximum removal efficiency of more than 95% could be achieved at a specific electrolyte concentration and pH of 7.2 +/- 0.3, illustrating that EC is a successful technique for removing nanoplastic pollutants from the aquatic environment. The advantage of the proposed method is that when nanoplastics and coagulants are mixed, they help make a foamy layer on top of the reactor that can be easily scraped off. The results of this study could serve as baseline information for achieving massive nanoplastics cleanup on a larger scale in an eco-friendly way.