Immobilisation of TiO ₂ films on activated carbon fibres by a hydrothermal method for photocatalytic degradation of toluene

Abstract

To improve the degradation efficiency of TiO 2 for low concentrations of volatile organic compounds, TiO 2 loaded on activated carbon fibres (ACF) was prepared by an impregnation-hydrothermal method. The crystal structure, surface area, dispersion, optical absorption properties, and chemical composition of the TiO 2 /ACF composite materials were characterised by X-ray diffraction, Brunauer−Emmett−Teller analysis, scanning electron microscopy, ultraviolet-visible absorption spectroscopy, and X-ray photoelectron spectroscopy. The influence of the hydrothermal temperature, illumination time, space velocity, and light intensity on the photocatalytic activities of the TiO 2 /ACF composite materials was investigated with toluene as a model pollutant. The results showed that the phase of TiO 2 was anatase, which was dispersed as a thin film on the ACF surface. The crystallinity, dispersion, UV absorption, and hydroxyl group content of TiO 2 increased with an increase of hydrothermal temperature, whereas the photocatalytic activity of TiO 2 /ACF was maximised when the hydrothermal temperature was 180°C. Increases in illumination time, space velocity, and light intensity were beneficial for regeneration of the composite materials. However, the energy efficiency decreased with increased light intensity. The degradation efficiency of toluene reached 40% with reaction conditions of illumination time: 3 h, space velocity: 1400 h −1 , and light intensity: 32 W. This degradation efficiency decreased 3.3% after recycling five times.

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“…This experiment demonstrated another property of TiO 2 ,t hat is, its photocatalytic activity,w hich thereby opened up an ew field of applications. [25] Till now,t itaniumd ioxide is the most photoactive material [26] owing to its oxidizing ability, chemicals tability, and low cost. [27,28] Anatase, rutile, and brookite are the main crystalline phases of TiO 2 .T he three crystalline phases are all made up of an octahedron of oxygen atoms aroundatitanium atom (TiO 6 octahedras) but with different organizationsd epending on the kind of phase.…”

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