TiO2/Fe3O4 magnetic nanoparticles as a nano-coagulant/flocculant for removal of calcium fluoride in semiconductor wastewater

Abstract

The recoverable magnetic core-shell TiO2/Fe3O4 and TiO2/SiO2/Fe3O4 nanoparticles were successfully prepared using sol-gel method. This paper aimed to study the effectiveness of TiO2/Fe3O4 and TiO2/SiO2/Fe3O4 Magnetic Nanoparticles (MNPs) as a nano-coagulant/flocculant for the removal of suspended calcium fluoride in semiconductor wastewater, evaluated by their efficiency in reducing the Total Suspended Solids (TSS). Experimental results revealed that with an additional chemically inert interlayer of SiO2, the TiO2/SiO2/Fe3O4 sample demonstrated the highest TSS removal of 99 %. In addition, Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Detector (TED) Microscopy images have shown that the TiO2/SiO2/Fe3O4 sample has an average particle size of 250 nm in a spherical shape, with the chemical composition confirmed using Energy Dispersive X-ray (EDX) and X-ray Diffraction (XRD) confirming that the TiO2 coating is in anatase phase. Lastly, the synthesised TiO2/SiO2/Fe3O4 magnetic nanoparticles demonstrated superparamagnetic properties, which may be used to facilitate the rapid removal of coagulated CaF2 flocs from semiconductor wastewater with the development of a novel electromagnetic separation treatment system, eliminating the need of a traditional gravity sedimentation tank.