Nanoplastics as emerging contaminants: A systematic review of analytical processes, removal strategies from water environments, challenges and perspective

Nanoplastics (NPs) with a size of less than 1 µm have received worldwide attention as an emerging environmental pollutant. Because they are easier for organisms to absorb, they pose higher ecological and health risks than microplastics. Natural water is a significant source of nanoplastics in the environment, and it is important for both human and ecosystem health. The analysis of nanoplastics in waters is still lacking reliable and harmonized methods. Most of the studies successfully identified and removed standard reference nanoplastics from environmental samples, but they were unable to quantify nanoplastics from real field samples. Here, we reviewed studies that measured and removed nanoplastics in environmental waters, such as seawater, rivers, drinking water, wastewater, snow, and so on. Pyrolysis gas chromatography–mass spectrometry (py-GC–MS) and surface-enhanced Raman spectroscopy were two common methods for analyzing nanoplastics in real samples. Mass spectrometry methods are time-consuming and cannot analyze the full nanorange due to particle size restrictions. This approach for measuring nanoplastic mass concentration may involve mistakes and require larger sample quantities. Various strategies for removing nanoplastics, including centrifugation, coagulation, filtration, flocculation, and adsorption, were reviewed. The effectiveness of nanoplastic removal is influenced by parameters such as source, size, type, and purification process. The removal efficiency for nanoplastics is 99 % when combined with filtration and coagulation processes. This study provides basic information for future research on the analysis and removal of nanoplastics from water and wastewater.