College of Environmental Science and Engineering, State Key Laboratory of Pollution Control and Resource Reuse, Ministry of Education Key Laboratory of Yangtze River Water Environment, Shanghai Institute of Pollution Control and Ecological Security, Tongji University, Shanghai, 200092, China.
College of Environmental Science and Engineering, State Key Laboratory of Pollution Control and Resource Reuse, Ministry of Education Key Laboratory of Yangtze River Water Environment, Shanghai Institute of Pollution Control and Ecological Security, Tongji University, Shanghai, 200092, China.
J Environ Sci (China). 2020 Mar;89:80-89. doi: 10.1016/j.jes.2019.10.011. Epub 2019 Nov 9.
Waste cutting emulsions are difficult to treat efficiently owing to their complex composition and stable emulsified structure. As an important treatment method for emulsions, chemical demulsification is faced with challenges such as low flocs-water separation rates and high sludge production. Hence, in this study, FeO magnetic nanoparticles (MNPs) were used to enhance chemical demulsification performance for treating waste cutting emulsions under a magnetic field. The addition of MNPs significantly decreased the time required to attain sludge-water separation and sludge compression equilibrium, from 210 to 20 min. In addition, the volume percentage of sludge produced at the equilibrium state was reduced from 45% to 10%. This excellent flocculation-separation performance was stable over a pH range of 3-11. The magnetization of the flocculants and oil droplets to form a flocculant-MNP-oil droplet composite, and the magnetic transfer of the composite were two key processes that enhanced the separation of cutting emulsions. Specifically, the interactions among MNPs, flocculants, and oil droplets were important in the magnetization process, which was controlled by the structures and properties of the three components. Under the magnetic field, the magnetized flocculant-MNP-oil droplet composites were considerably accelerated and separated from water, and the sludge was simultaneously compressed. Thus, this study expands the applicability of magnetic separation techniques in the treatment of complex waste cutting emulsions.
废切削乳化液由于其复杂的组成和稳定的乳化结构，难以有效处理。作为乳化液的一种重要处理方法，化学破乳面临着絮体-水分离率低、污泥产量高的挑战。因此，本研究采用 FeO 磁性纳米粒子（MNPs）在磁场下增强化学破乳性能，以处理废切削乳化液。添加 MNPs 可显著缩短达到污泥-水分离和污泥压缩平衡所需的时间，从 210 分钟缩短至 20 分钟。此外，在平衡状态下产生的污泥体积百分比从 45%降低至 10%。这种出色的絮凝-分离性能在 pH 值为 3-11 的范围内稳定。絮凝剂和油滴的磁化形成絮凝剂-MNP-油滴复合物，以及复合物的磁性转移是增强切削乳液分离的两个关键过程。具体而言，MNPs、絮凝剂和油滴之间的相互作用在磁化过程中很重要，而磁化过程受这三种成分的结构和性质控制。在磁场作用下，磁化的絮凝剂-MNP-油滴复合物被显著加速并与水分离，同时污泥被压缩。因此，本研究扩展了磁分离技术在处理复杂废切削乳化液中的适用性。
