Yu Yang, Zhu Bingxing, Ding Yindi, Zhou Cailing, Ge Shifu
School of Energy and Environment, MOE Key Laboratory of Environmental Medicine Engineering, Southeast University, Nanjing 210096, PR China.
School of Energy and Environment, MOE Key Laboratory of Environmental Medicine Engineering, Southeast University, Nanjing 210096, PR China.
Sci Total Environ. 2023 Nov 25;901:166012. doi: 10.1016/j.scitotenv.2023.166012. Epub 2023 Aug 2.
This study provides an in-depth examination of the role of poly(lactic acid) microplastics (PLA-MPs) during sludge treatment, particularly in relation to organic compound leaching and heavy metal distribution. Through the application of advanced analytical techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermal analysis, and gas chromatography-mass spectrometry (GC-MS), the release of degradation byproducts was quantified, and the effects on organic compound leaching and heavy metal distribution were assessed. Specifically, the results demonstrated that PLA-MPs significantly impacted the hydrolysis reaction, with the pH value descending in pure water as the hydrothermal temperature escalated. At 140 °C, the hydrolysate contained 20.66 % propylene ester and 16.57 % lactic acid. Furthermore, an increase in total organic carbon (TOC) was observed with increasing temperature, with TOC content at 140 °C in water almost doubling from that at 120 °C and 130 °C. With respect to heavy metals, the presence of PLA-MPs influenced the migration of Cr(VI) between solid and liquid phases in sludge. Notably, after 180 °C hydrothermal treatment, the content of Cr(VI) in the liquid phase of sludge with PLA-MPs was 9.72 %, which is higher than that of sludge without PLA-MPs at 5.80 %. These findings underline the need to consider PLA-MPs' influence on organic compound leaching and heavy metal distribution during sludge treatment.
本研究深入探讨了聚乳酸微塑料（PLA-MPs）在污泥处理过程中的作用，特别是在有机化合物浸出和重金属分布方面。通过应用傅里叶变换红外光谱（FTIR）、X射线光电子能谱（XPS）、热分析和气相色谱-质谱联用（GC-MS）等先进分析技术，对降解副产物的释放进行了定量，并评估了其对有机化合物浸出和重金属分布的影响。具体而言，结果表明PLA-MPs对水解反应有显著影响，在纯水中随着水热温度升高pH值下降。在140°C时，水解产物中含有20.66%的丙交酯和16.57%的乳酸。此外，随着温度升高总有机碳（TOC）增加，在140°C水中的TOC含量几乎是120°C和130°C时的两倍。关于重金属，PLA-MPs的存在影响了污泥中Cr(VI)在固液相之间的迁移。值得注意的是，在180°C水热处理后，含有PLA-MPs的污泥液相中Cr(VI)的含量为9.72%，高于不含PLA-MPs的污泥的5.80%。这些发现强调了在污泥处理过程中需要考虑PLA-MPs对有机化合物浸出和重金属分布的影响。
