Preparation And Performance Of Magnetically Separable TiO₂Photocatalysts Under Visible Irradiation

Titania (TiO2) is believed to be currently available photocatalytic material, because of its superior photoreactivity, non-toxicity, stability, et al. However, the practical application of TiO2is still limited due to difficulty to separate TiO2particles in process of the treated water. To overcome the problem, titania beads, fiberglass loaded with titania, and encapsulated titania within a zeolite framework have been prepared and used in fixed bed. However,the activity of TiO2photocatalyst is reduced to a considerable extent in the application of these immobilizations because the effective surface area of photocatalysts decreases considerably. On the other hand, the TiO2hold a wide bandgap semiconductor (Eg=3.2eV) and can absorb sunlight is approximately3%-5%in ultraviolet region lead to greatly limits its practical applications. Therefore, the reduction process, shorten time of the preparation have a great significance for practicability of magnetic separation TiO2photocatilyst.In this paper, the core-shell TiO2/CoFe2O4magnetic nano-photocatalysts are prepared via two-step approach. They are prepared by hydrolysis of TiOS04in the presence of the CoFe204magnetic particles. The properties of sample are characterized by VSM、XRD and TEM. The photocatalyst reactivity was evaluated by using methyl orange aqueous solution as simulated contaminants. The results indicated that the TiO2/CoFe2O4composite photocatalytic material show good crystal form and the TiO2and CoFe2O4of the samples exist as anatase phase and spinel structure, respectively. The diameter of the TiO2/CoFe2O4particles is in the range of40nm-50nm and show superparamagnetism. The TiO2/CoFe2O4composite photocatalytic material show highly photocatalytic activity and reuse performance.For reduce the prepare process, shorten time of the preparation of magnetically separable TiO2photocatalysts and well photoreactivity under visible irradiation. In this paper explores the Ti02-CoFe204composite photocatalyst is prepared by one-step method with ultrasound technique using TiCl4, trivalent iron salt and divalent cobalt salts as precursors. The properties of sample are characterized by VSM、XRD、TEM and UV-Vis. The photocatalyst reactivity is evaluated by using methyl orange aqueous solution as simulated contaminants in the sunlight. The results indicat that the TiO2-CoFe2O4composite photocatalyst showed good magnetic properties and the saturation magnetization is212Gs. The TiO2and CoFe2O4of the samples exist as anatase phase and spinel structure, respectively. The diameter of the TiO2-CoFe2O4particles is in the range of40nm-50nm. The spectrum response is from UV to visible region and the absorbance intensity remarkably increased. The photocatalyst test showed highly photocatalytic activity in the sunlight and maintained the activity when it is repeatedly used for3times.