Separation of nanoplastics from synthetic and industrial wastewater using electrolysis-assisted flotation approach: A green approach for real-time contaminant mitigation

Abstract

Nanoplastics pose a significant global environmental concern, as they can accumulate emerging pollutants and enter the food chain, endangering human health and ecosystems. Wastewater treatment plants (WWTPs) have been identified as the primary source of micro and nanoplastic contamination, necessitating the development of effective removal methods. This study investigates the efficacy of electrolysis-assisted flotation (EF) process for removing nanoplastics from synthetic wastewater, using polystyrene-type nanoparticles synthesized from expanded polystyrene waste (EPS) as representative nanoplastic contaminants. Electrolysis experiments were conducted using parallel aluminium electrodes under low-voltage conditions. The study systematically explores the influence of various process parameters, including electrode spacing, salt concentration, nanoplastics concentration, and applied voltage, on the removal efficiency of nanoplastics. The removal efficiency was evaluated using a turbidity meter and dynamic light scattering technique. The derived count rate (DCR) obtained from dynamic light scattering supplements the nephelometric turbidity units (NTU) and provides a reliable estimate of the nanoplastics sample concentration. Under optimized conditions, with a specified electrolyte concentration and pH of 7.2 ± 0.3, the EF process achieved an impressive removal efficiency of nearly 95 % (94 % per DCR). A notable advantage of the proposed method is forming a foamy layer on top of the reactor when nanoplastics and coagulants are mixed, facilitating easy removal by simple scraping. This study provides valuable insights into developing an eco-friendly and sustainable approach for the large-scale removal of nanoplastics. The results contribute to advancing wastewater treatment strategies and addressing the pressing issue of nanoplastic pollution.