Influences of surface coating, UV irradiation and magnetic field on the algae removal using magnetite nanoparticles

Shijian Ge, Michael Agbakpe, Zhiyi Wu, Liyuan Kuang, Wen Zhang, Xianqin Wang

Research output: Contribution to journalArticlepeer-review

85 Scopus citations


(Figure Presented) 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.

Original languageEnglish (US)
Pages (from-to)1190-1196
Number of pages7
JournalEnvironmental Science and Technology
Issue number2
StatePublished - Jan 20 2015

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • Environmental Chemistry


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