Hollow MTB@Si-TiO2 Microparticles With Hierarchical Porous Structure for Oil–Water Separation With Photocatalytic Self-Cleaning Property

Here, we report that hollow MTB@Si-TiO 2 microparticles with a photo-responsive regeneration property were prepared for reproducible treatment of oily wastewater. Oil solutions of methyl methacrylate (MMA) and butyl methacrylate (BMA, containing oleic acid-modified ferric tetroxide (OA-Fe 3 O 4 )), a photoinitiator, a surfactant and silane-modified TiO 2 nanoparticles served as the middle phase. Aqueous solutions containing glycerol and surfactant were used as the inner and outer phases. Water-in-oil-in-water (W/O/W) emulsion templates were prepared by a microfluidic emulsification method and subsequently polymerized under UV light to form photocatalytic magnetic hollow porous microparticles. The hollow MTB@Si-TiO 2 microparticles exhibit high and stable adsorption performance (6.07 g/g) toward various oil–water mixtures under different conditions. In addition, cyclic oil–water separation experiments demonstrate the excellent photocatalytic regeneration capability of the microparticles and their high removal efficiency for oil and organic dyes (99.05%). Therefore, during oily wastewater treatment, the microparticles can be regenerated while directly degrading pollutants in the wastewater through photocatalysis, thereby avoiding secondary pollution caused by the use of additional solvents.