title: Recovering Magnetic Fe3O4-ZnO Nanocomposites from Algal Biomass Based on Hydrophobicity Shift under UV Irradiation.
abstract: Magnetic separation, one of the promising bioseparation technologies, faces the challenges in recovery and reuse of magnetic agents during algal harvesting for biofuel extraction. This study synthesized a steric acid (SA)-coated Fe3O4-ZnO nanocomposite that could shift hydrophobicity under UV365 irradiation. Our results showed that with the transition of surface hydrophobicity under UV365 irradiation, magnetic nanocomposites detached from the concentrated algal biomass. The detachment was partially induced by the oxidation of SA coating layers due to the generation of radicals (e.g., •OH) by ZnO under UV365 illumination. Consequently, the nanocomposite surface shifted from hydrophobic to hydrophilic, which significantly reduced the adhesion between magnetic particles and algae as predicted by the extended Derjaguin and Landau, Verwey, and Overbeek (EDLVO) theory. Such unique hydrophobicity shift may also find many other potential applications that require recovery, recycle, and reuse of valuable nanomaterials to increase sustainability and economically viability.
authors.affiliation: †John A. Reif, Jr., Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, New Jersey 07102, United States.
authors.forename: Shijian
authors.initials: S
authors.lastname: Ge
authors.affiliation: †John A. Reif, Jr., Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, New Jersey 07102, United States.
authors.forename: Michael
authors.initials: M
authors.lastname: Agbakpe
authors.affiliation: †John A. Reif, Jr., Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, New Jersey 07102, United States.
authors.forename: Wen
authors.initials: W
authors.lastname: Zhang
authors.affiliation: †John A. Reif, Jr., Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, New Jersey 07102, United States.
authors.forename: Liyuan
authors.initials: L
authors.lastname: Kuang
authors.affiliation: ‡Department of Chemical Biological and Pharmaceutical Engineering, New Jersey Institute of Technology, Newark, New Jersey 07102, United States.
authors.forename: Zhiyi
authors.initials: Z
authors.lastname: Wu
authors.affiliation: ‡Department of Chemical Biological and Pharmaceutical Engineering, New Jersey Institute of Technology, Newark, New Jersey 07102, United States.
authors.forename: Xianqin
authors.initials: X
authors.lastname: Wang
mesh_terms: D018533:Biomass; D057927:Hydrophobic and Hydrophilic Interactions; D060526:Magnetic Fields; D058185:Magnetite Nanoparticles / Q000737:chemistry* / Q000528:radiation effects; D053761:Nanocomposites / Q000737:chemistry / Q000528:radiation effects; D059027:Recycling / Q000379:methods*; D044444:Scenedesmus / Q000737:chemistry* / Q000302:isolation & purification*; D014466:Ultraviolet Rays; D015034:Zinc Oxide / Q000737:chemistry / Q000302:isolation & purification* / Q000528:radiation effects
chemical_list: D058185:Magnetite Nanoparticles; D015034:Zinc Oxide
keywords: algal harvesting; biofuel; hydrophobicity; magnetic nanoparticles; magnetophoretic separation; microalgae