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Rapid oxidative fragmentation of polypropylene with pH control in seawater for preparation of realistic reference microplastics

Scientific Reports 2023 18 citations ? Citation count from OpenAlex, updated daily. May differ slightly from the publisher's own count.
Hisayuki Nakatani, Yuina Ohshima, Taishi Uchiyama, Suguru Motokucho, Anh Dao, Hee‐Jin Kim, Mitsuharu Yagi, Yusaku Kyozuka

Summary

Researchers developed a method to produce realistic reference microplastics by rapidly fragmenting polypropylene through oxidative treatment in seawater with pH control, and characterized the resulting particles using SEM/EDX to confirm their similarity to environmentally weathered microplastics.

Study Type Environmental

Various tiny plastic particles were retrieved from the sea and studied using scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX) analysis to prepare realistic reference microplastics (MP). Most of the MP exhibited a diameter of < 20 × 10-6 m and 0.1-0.2 molar ratios of oxygen to carbon atoms (O/C), indicating that they primarily comprised polyethylene (PE), polypropylene (PP), and polystyrene (PS). It took a long time to reproduce such O/C ratios in standard laboratory weathering methods. For example, degrading of 30 × 30 × 0.060 mm PP film required 75 days for the 0.1 ratio, even with an advanced oxidation process (AOP) using a sulfate radical anion (SO4·-) initiator in distilled water at 65 °C. However, seawater drastically improved the PP degradation performance of AOP under a weak acid condition to achieve the 0.1 ratio of PP film in only 15 days. The combination of seawater and the SO4·- initiator accelerated the degradation process and showed that the MP's size could be controlled according to the degradation time.

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