Rapid measurement of photocatalytic oxidation of poly(vinyl chloride) byin situFTIR spectrometry of evolved CO2 (original) (raw)

Materials Science and Technology

Abstract

ABSTRACT The CO2 generated by UV irradiation of unplasticised PVC pigmented with TiO2 was monitored by in situ Fourier transform infrared (FTIR) spectrometry. CO2 was evolved immediately irradiation began (although no HCl was detected) and when irradiation ceased CO2 evolution fell significantly. A comparison of photogeneration of CO2 from unpigmented and pigmented PVC demonstrated that, although a heavily coated TiO2 (R5) did not increase the rate of CO2 formation, lightly coated TiO2 (R3) photocatalysed PVC oxidation to CO2. As expected for a photocatalytic process, the photogeneration of CO2 increased with increased TiO2 loading. The convenience of the FTIR method allowed the increased rate of oxidation with increasing partial pressure of oxygen, or increasing humidity, to be demonstrated. It was also shown that the rate of photocatalytic oxidation varied as the square root of UV intensity. This dependence would result if recombination of UV generated charge carriers controls the rate of photocatalysis.

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