Surface characteristics of polystyrene microplastics mainly determine their coagulation performances. (January 2023)

• Record Type: Journal Article
• Authors: Yao, Jingjing; Peng, Zhaoxia; Chen, Weifeng; Lin, Qingyuan; Cheng, Mengsi; Li, Haipu; Yang, Ying; Yang, Hui Ying
• Is Part Of: Marine pollution bulletin. Volume 186(2023)
• Publication Date: 2023-01
• Subjects: BET Brunauer-Emmet-Teller -- CI carbonyl index -- EDS Energy-dispersive X-ray spectroscopy -- FT-IR Fourier transform infrared spectroscopy -- MP microplastics -- PA12 poly laurolactam -- PAC polyaluminum chloride -- PAS polyaluminum sulfate -- PE polyethylene -- PET polyethylene terephthalate -- PFS poly ferric sulfate -- PP polypropylene -- PS polystyrene -- SEM scanning electron microscopy -- TG-DTA thermogravimetric analysis-differential thermal analysis -- XPS X-ray photoelectron spectroscopy -- XRD X-ray diffraction; Polystyrene -- Microplastics -- Coagulation -- Surface characteristics -- Aging treatments; Marine pollution -- Periodicals; Marine Biology -- Periodicals; Water Pollution -- Periodicals; Mer -- Pollution -- Périodiques; Publications périodiques; Pollution des mers; Lutte antipollution; Electronic journals; 363.7394
• DOI: 10.1016/j.marpolbul.2022.114347
• Languages: English
• ISSNs: 0025-326X

Abstract

Abstract: In this study, polyaluminum sulfate (PAS) coagulant was selected to evaluate the coagulation performance of polystyrene microplastics. Overall, polystyrene removal efficiency was 90.4 % at the optimal dosage of 7.5 g/L of PAS. In addition to the type of coagulants (e.g. polyaluminum chloride, iron(III) chloride, and polyferric sulfate), surface characteristics such as densities, particle sizes, morphologies, adsorbed substances, and functional groups can also significantly impact the coagulation performance. The coagulation ratios are reduced to (2.6 ± 0.1)% when the densities of microplastics decrease. Aging treatments involving NaOH, H2 SO4, NaClO, CH3 OH, and O3 promoted coagulation, whereas UV and Na2 S2 O3 treatments inhibited (64.1 ± 9.7)% and (79.3 ± 8.0)% of polystyrene removals, respectively. In contrast, Fe(NO3 )3 treatment did not affect the removal ratio. Further characterization of polystyrene before and after coagulation exemplified that the functional groups (CO, CO, and CH) and the rough surfaces of PAS provided adsorption and interception sites for hydrolysis products of the PAS. Graphical abstract: Unlabelled Image Highlights: Coagulant types showed negligible impacts on polystyrene microplastic coagulations. The effect of aged microplastics on coagulations relied on surface characteristics. CO, CO, CH, and rough surfaces contributed to microplastic coagulations. Adsorption and interception of polystyrene to Al(OH)3 and flocs were pronounced.