Environ Sci Technol. 2015 Jan 20;49(2):1190-6. doi: 10.1021/es5049573.
Magnetophoretic separation is a promising and sustainable technology for rapid algal separation or removal from water. This work demonstrated the application of magnetic magnetite nanoparticles (MNPs) coated with a cationic polymer, polyethylenimine (PEI), toward the separation of Scenedesmus dimorphus from the medium broth. The influences of surface coating, UV irradiation, and magnetic field on the magnetophoretic separation were systematically examined. After PEI coating, zeta potential of MNPs shifted from −7.9 ± 2.0 to +39.0 ± 3.1 mV at a pH of 7.0, which improved MNPs-algae interaction and helped reduce the dose demand of MNPs (e.g., from 0.2 to 0.1 g·g(–1) while the harvesting efficiency (HE) of over 80% remained unchanged). The extended Derjaguin–Landau–Verwey–Overbeek theory predicted a strong attractive force between PEI-coated MNPs and algae, which supported the improved algal harvesting. Moreover, the HE was greater under the UV365 irradiation than that under the UV254, and increased with the irradiation intensity. Continuous application of the external magnetic field at high strength remarkably improved the algal harvesting. Finally, the reuse of MNPs for multiple cycles of algal harvesting was studied, which aimed at increasing the sustainability and lowering the cost.
磁泳分离是一种很有前途且可持续的技术，可用于快速从水中分离或去除藻类。本工作展示了用带正电荷的聚合物聚乙烯亚胺（PEI）包覆的磁性磁铁矿纳米粒子（MNP）在分离二形栅藻中的应用。系统地考察了表面包覆、UV 照射和磁场对磁泳分离的影响。PEI 包覆后，MNP 在 pH 值为 7.0 时的动电位从−7.9 ± 2.0 mV 变为+39.0 ± 3.1 mV，这改善了 MNP-藻类相互作用，有助于减少 MNP 的用量（例如，从 0.2 g·g(–1)减少到 0.1 g·g(–1)，而采收效率（HE）仍保持在 80%以上不变）。扩展的德热那维-朗道-维尔韦尔-奥弗贝克理论预测了 PEI 包覆的 MNP 和藻类之间存在很强的吸引力，这支持了藻类采收效率的提高。此外，在 UV365 照射下的 HE 大于在 UV254 照射下的 HE，并且随着照射强度的增加而增加。连续施加高强度的外部磁场显著提高了藻类的采收效率。最后，研究了 MNP 的重复使用以进行多次藻类采收，这旨在提高可持续性并降低成本。
