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Degradation of water soluble poly(vinyl alcohol) with acoustic and hydrodynamic cavitation: laying foundations for microplastics
npj Clean Water ( IF 11.4 ) Pub Date : 2023-04-28 , DOI: 10.1038/s41545-023-00248-8
Martin Petkovšek, Andrej Kržan, Alenka Šmid, Ema Žagar, Mojca Zupanc

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 1H 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.



中文翻译:

水溶性聚(乙烯醇)的声学和流体动力学空化降解:为微塑料奠定基础

水溶性聚(乙烯醇)(PVOH) 广泛用于纺织和造纸工业以及家用洗涤剂包。除了传统的微塑料外,水溶性 PVOH 还会对环境造成威胁,因为它通常会在不被注意和畅通无阻的情况下被冲进下水道。如果在废水处理过程中不加以处理,估计每年有数千吨进入水生生态系统。本研究旨在通过声学和流体动力学空化在实验室规模上解决 PVOH 的降解问题,辅助或不辅助氧化剂。考虑到实际应用而设计的水动力空化发生器提出了一种适用于废水处理的创新技术。温度、外部氧化剂的添加和甲醇作为羟基自由基的影响(对 PVOH 溶液的 OH) 清除剂进行了系统研究。在最佳操作条件下,PVOH 平均摩尔质量显着降低(在使用流体动力空化和添加外部氧化剂进行 60 分钟处理的情况下,从124 的重均摩尔质量下降到 1.6 kg mol -1 ),同时摩尔质量分布变窄。SEC/MALS、FTIR 和1 H NMR 结果表明,PVOH 链的机械降解在声空化中占主导地位,而化学效应在水动力空化中也起着重要作用。这项研究的结果可以作为其他碳骨架聚合物降解的模型研究,并提供改善环境中功能化聚合物最终(生物)降解的途径。

更新日期:2023-04-28
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