title: Preparation of magnetic hierarchically porous microspheres with temperature-controlled wettability for removal of oils.
abstract: A series of monodispersed microspheres with hierarchically porous structures were prepared by microfluidic devices. Phase separation of the silica sol in microdroplets was adopted to construct these structures. The effects of velocity ratios (for both the continuous and the dispersed phases), collection solvents and calcination temperatures were investigated. The diameters of the microspheres were tuned from 148μm to 940μm by adjusting the velocity ratio. Tests revealed that the surface areas and pore volumes of the microspheres can reach 495m2g-1and 0.6068mlg-1, respectively. The macroporous structure can be controlled by the collection solvents, and the wettability of the microspheres is determined by the calcination temperature. A calcination temperature of 450°C leads to a hydrophilic surface property. Fe3O4nanoparticles were added to the silica sol to form magnetic microspheres, and the porous structure was not affected. This kind of hybrid microsphere adsorbs 3.29 times its own weight in toluene. These spheres can adsorb oil on water surfaces, and then be removed from the water with an external magnetic field. The microspheres can be recovered and reused more than 10 times.
authors.affiliation: Department of Chemistry, Dalian University of Technology, Dalian, Liaoning 116024, PR China. Electronic address: taosy@dlut.edu.cn.
authors.forename: Shengyang
authors.initials: S
authors.lastname: Tao
authors.affiliation: Department of Chemistry, Dalian University of Technology, Dalian, Liaoning 116024, PR China. Electronic address: yunzheDing@mail.dlut.edu.cn.
authors.forename: Yunzhe
authors.initials: Y
authors.lastname: Ding
authors.affiliation: Laboratory of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning 116023, PR China. Electronic address: jianglei@dicp.ac.cn.
authors.forename: Lei
authors.initials: L
authors.lastname: Jiang
authors.affiliation: Department of Chemistry, Key Lab of Organic Optoelectronics & Molecular Engineering, Tsinghua University, Beijing 100084, PR China. Electronic address: LGT@mail.tsinghua.edu.cn.
authors.forename: Guangtao
authors.initials: G
authors.lastname: Li
keywords: Microfluidic; Monodispersed microspheres; Removal of oils