College of Environmental and Municipal Engineering, Shandong Jianzhu University, Jinan, China.
Weifang Municipal Public Utilities Management Office, Weifang, China.
Water Environ Res. 2021 May;93(5):693-702. doi: 10.1002/wer.1352. Epub 2020 Dec 13.
Microplastics (MPs) are widely distributed in freshwater and have the following characteristics: small size, strong hydrophobicity, difficult degradation, and easy adsorption of toxic substances. These characteristics pose a potential threat to the environment and human health. In this paper, three common MPs in freshwater were removed by conventional dissolved air flotation (DAF) and positive modification DAF (Posi-DAF). The results showed that the optimal removal efficiency of MPs by conventional DAF was 32%-38% at 0.4-0.5 MPa. This indicated that the adhesion between microbubbles (MBs) and MPs was not ideal when the hydrophilic/hydrophobic interaction was the dominant mechanism. However, the removal efficiency of MPs was increased by 13.6%-33.7% compared with that of conventional DAF after two surface modifiers were used on MBs. This result indicated that in addition to the hydrophilic/hydrophobic interaction, both charge attraction and sweeping had positive effects. PRACTITIONER POINTS: The removal efficiency and mechanism of MPs by posi-DAF were investigated. The characteristics, particle number, and adhesion of microplastics were measured. Conventional DAF was dominated by hydrophilic/hydrophobic interactions. CTAB Posi-DAF was dominated by charge attraction. PDADMAC Posi-DAF was dominated by charge attraction and sweeping.
微塑料（MPs）广泛分布于淡水中，具有体积小、疏水性强、降解难、易吸附有毒物质等特点。这些特性对环境和人体健康构成了潜在威胁。本研究采用常规溶气浮选（DAF）和正电改性溶气浮选（Posi-DAF）去除三种常见的淡水微塑料。结果表明，常规 DAF 在 0.4-0.5 MPa 时对 MPs 的最佳去除效率为 32%-38%，这表明当亲水/疏水性相互作用占主导地位时，微气泡（MBs）与 MPs 之间的粘附不理想。然而，与常规 DAF 相比，两种表面改性剂用于 MBs 后，MPs 的去除效率提高了 13.6%-33.7%。这表明除了亲水/疏水性相互作用外，电荷吸引和扫掠都有积极的影响。
研究了正电改性溶气浮选去除 MPs 的效率和机制。测量了 MPs 的特性、颗粒数和粘附性。常规 DAF 主要受亲水/疏水性相互作用的影响。CTAB 正电改性 DAF 主要受电荷吸引的影响。PDADMAC 正电改性 DAF 主要受电荷吸引和扫掠的影响。
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