Degradation of water soluble poly(vinyl alcohol) with acoustic and hydrodynamic cavitation: laying foundations for microplastics

Martin Petkovšek (Author), Andrej Kržan (Author), Alenka Šmid (Author), Ema Žagar (Author), Mojca Zupanc (Author)

Abstract

Water-soluble poly(vinyl alcohol) (PVOH) is widely used in the textile and paper industries and in households as detergent pods. In addition to conventional microplastics, water-soluble PVOH poses an environmental threat because it is usually washed down the drain unnoticed and unobstructed. If not treated during wastewater treatment, it enters the aquatic ecosystem in estimated quantities of several thousand tons annually. The present study aims to address the degradation of PVOH on a laboratory scale by acoustic and hydrodynamic cavitation, assisted or not with an oxidative agent. A hydrodynamic cavitation generator, designed with consideration for real-life application, presents an innovative technology adapted for wastewater treatment. The effects of temperature, addition of external oxidant, and methanol as a hydroxyl radical ($^•$OH) scavenger to PVOH solutions were systematically studied. At optimal operating conditions, PVOH molar mass averages significantly decreased (from weight average molar mass of 124 to 1.6 kg mol$^{−1}$ in case of 60 min treatment with hydrodynamic cavitation and addition of external oxidant) with concomitant narrowing of molar mass distribution. The SEC/MALS, FTIR, and $^1$H NMR results show that mechanical degradation of PVOH chains predominates in acoustic cavitation, while chemical effects also play an important role in hydrodynamic cavitation. Findings from this study could serve as model research for the degradation of other carbon-backbone polymers and provide a route to improved ultimate (bio)degradation of functionalized polymers in the environment.

Keywords

cavitation;PVOH;microplastics;degradation;

Data

Language:	English
Year of publishing:	2023
Typology:	1.01 - Original Scientific Article
Organization:	UL FS - Faculty of Mechanical Engineering
UDC:	532.528:678.7
COBISS:	150832899
ISSN:	2059-7037
Views:	384
Downloads:	47
Average score:	0 (0 votes)
Metadata:

Other data

Secondary language:	Slovenian
Secondary keywords:	kavitacija;PVOH;mikroplastika;razgradnja;
Type (COBISS):	Article
Pages:	str. 1-11
Issue:	ǂVol. ǂ6
Chronology:	April 2023
DOI:	10.1038/s41545-023-00248-8
ID:	18799032