†John A. Reif, Jr., Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, New Jersey 07102, United States.
‡Department of Chemical Biological and Pharmaceutical Engineering, New Jersey Institute of Technology, Newark, New Jersey 07102, United States.
ACS Appl Mater Interfaces. 2015 Jun 3;7(21):11677-82. doi: 10.1021/acsami.5b03472. Epub 2015 May 20.
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.
磁分离作为一种很有前途的生物分离技术，在从藻类中提取生物燃料时，面临着回收和再利用磁性剂的挑战。本研究合成了一种硬脂酸（SA）包覆的 Fe3O4-ZnO 纳米复合材料，该复合材料在 UV365 照射下可改变其疏水性。我们的结果表明，随着表面疏水性在 UV365 照射下的转变，磁性纳米复合材料从浓缩的藻类生物质中脱离。这种脱附部分是由 SA 涂层在 UV365 光照下产生的自由基（如•OH）氧化引起的。因此，纳米复合材料表面由疏水性变为亲水性，这大大降低了磁性颗粒和藻类之间的粘附力，正如扩展的德加古林和朗道、维韦和奥弗贝克（EDLVO）理论所预测的那样。这种独特的疏水性转变可能还有许多其他潜在的应用，需要回收、再循环和再利用有价值的纳米材料，以提高可持续性和经济可行性。
