Photocatalytic Activity of Immobilized Geometries of TiO2

Abstract

Photocatalysts that are used for waste water treatment are often suspended in the waste water during processing and then must be removed from the water after treatment. To reduce the post-degradation expenses and time, separation is facilitated by an immobilization process. The effect of immobilized TiO 2 geometries on the photocatalytic behavior of the photocatalyst is investigated in this work. Powder, fiber, film, and network-shaped TiO 2 nanocatalysts were produced by using different templates. The cellulose fiber and ceramic templates were used as substrates for fiber and film/network geometry production. The products were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) surface area measurement. The photocatalytic performance was determined by methyl orange degradation and cyanide photo-oxidation under ultraviolet irradiation. From the SEM images, the size range of the TiO 2 particles in the film and in the network geometries were 20-60 nm. The nanoparticles had covered the surface of the substrate, uniformly. Removal of the cellulose substrate by heat treatment yielded hollow TiO 2 fibers with diameters of 0.5-1 lm and lengths of 30 lm. The efficiencies of both photocatalytic reactions were obtained in the following order: powder > network > film > fiber geometry. The rate constant of the dye degradation reaction using powder catalyst was 0.0118 min 21 . For network catalyst, it was 0.0083 min 21 . Corresponding results for cyanide disinfection were 0.0055 and 0.0046 min 21 . Although powder samples had higher rate constants, network geometry was preferred due to its higher immobility.

Photocatalytic removal of cyanide and Cr(IV) from wastewater in the presence of each other by using TiO 2 /UV

“…3.1. Photooxidation of CN alone and in the presence of Cr(VI): The mechanism of CN removal depends on electron/hole pairs (e − −h + ) being produced, where the semiconductor particles absorb light energy whose wavelength shall be high enough to surpass the bandgap energy of the semiconductor [1,3]. Within an aqueous medium, the spaces on the surface of the semiconductor (TiO 2 ) will react with water molecules (H 2 O) to produce a hydroxyl radical (OH † ), which can oxidise CN to cyanate (CNO − ).…”

“…The remaining concentration of CN was analysed by 4500-CN D. Titrimetric method according to standard methods for the examination of water and wastewater. Then, the residual CN concentration was calculated using the following equation [1,3]:…”

“…These include generating electron-hole pairs by photonic-excitation of a photocatalyst (i.e. semiconductor) using UV photons [3,8]. TiO 2 has proved to be a promising semiconductor among others for its physical/chemical properties, low cost, chemical stability, and non-toxicity [1,[7][8][9].…”

Photocatalytic performance of rod‐shaped copper oxides prepared by spin coating

“…The variation of the MeO concentration was analysed using UV-Vis spectrophotometer Jenway-6705 at the maximum absorption wavelength registered at 462 nm. The degradation efficiency was calculated from the following equation [8]:…”

“…Therefore, semiconductor photocatalysts provide an acceptable approach to solve environmental problems within degradation of organic contaminants of air or water [7][8][9].…”