Design and Application of Magnetic Photocatalysts for Water Treatment. The Effect of Particle Charge on Surface Functionality

Abstract

Core-interlayer-shell Fe 3 O 4 /SiO 2 /TiO 2 , CoFe 2 O 4 /SiO 2 /TiO 2 and BaFe 12 O 19 /SiO 2 /TiO 2 magnetic photocatalysts were obtained. A water-in-oil microemulsion system with suitable surfactants was used for functionalization of the magnetic core with silica interlayer and TiO 2 -based photocatalyst. Uncoated and coated particles were characterized by electrophoretic measurements, X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), specific surface area (BET) measurements, diffuse reflectance spectroscopy (DRS) and vibrating sample magnetometer (VSM) analysis. The pH of the solution and corresponding zeta potential was found to be essential for appropriate formation of ferrite core/silica interlayer/TiO 2 shell nanocomposite, since the electrical charge controls interactions during functionalization of the magnetic core particles. Thus, the development of multilayer structure in the isoelectric point (IEP) region enhanced adhesion of ferrite, silica and titania particles. The obtained Fe 3 O 4 /SiO 2 /TiO 2 , CoFe 2 O 4 /SiO 2 /TiO 2 and BaFe 12 O 19 /SiO 2 /TiO 2 nanocomposites revealed superparamagnetic behavior. The decomposition rate of phenol and carbamazepine allowed to estimate their photocatalytic activity. Progress of photocatalytic mineralization of organic compounds was evaluated by total organic carbon (TOC) measurements. Photocatalytic activity measured in four subsequent cycles showed good reusability as no loss of efficiency of phenol degradation was observed.

Influence of cobalt addition and calcination temperature on the physical properties of BaFe12O19 hexaferrites nanoparticles

“…Samples possess spherical together with hexagonal shaped grains. Similar morphology was observed for Barium hexaferrite with diameter 50-70 nm by Jurek et al[41]. Also, it is noticed that the…”

Morphology- and Crystalline Composition-Governed Activity of Titania-Based Photocatalysts: Overview and Perspective

“…Therefore, a mechanically stable core has been proposed, such as magnetic Fe 3 O 4 , which additionally allows the fast and easy separation of photocatalysts after reactions in the magnetic field [109][110][111]. However, the photoreaction between a core and a shell might result in the instability of the photocatalyst (e.g., dissolution of iron), and thus an insulator interlayer has been applied by Zielinska-Jurek et al between a magnetic core and titania shell, as shown in Figure 6 [110].…”

“…Core-interlayer-shell NPs composed of Fe3O4 (core), SiO2 (interlayer), and TiO2 (shell): (a) Nanostructure scheme; and (b) Mapping of Fe3O4, SiO2, and TiO2 in Fe3O4/SiO2/TiO2) photocatalyst prepared by the microemulsion method (Fe-red, Si-green, and Ti-blue); adapted from[110]. Copyright 2017 Creative Commons Attribution.…”

UV-Vis-Induced Degradation of Phenol over Magnetic Photocatalysts Modified with Pt, Pd, Cu and Au Nanoparticles

“…In this regard, the introduction of a silica intermediate passive layer could prevent an injection of charge carriers from titania shell into the iron oxide core and the subsequent leaching of iron ions into the solution [ 5 ]. The functionalization of the magnetic core consisting of magnetite [ 6 ], maghemite [ 7 ], hematite [ 8 ], CoFe 2 O 4 [ 9 ], ZnFe 2 O 4 spinel ferrites [ 10 ], BaFe 12 O 19 hexagonal ferrites [ 9 ], bimetallic nanoparticles of Fe-Ni, Co-Fe, Mn-Zn, Ni-Cu-Zn [ 11 , 12 ] with TiO 2 and intermediate SiO 2 passive layer has recently been investigated.…”