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Author Shin, E. M. ♦ Senthurchelvan, R. ♦ Munoz, J. ♦ Basak, S. ♦ Rajeshwar, K. ♦ Benglas-Smith, G. ♦ Howell, B. C. III
Sponsorship USDOE
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION ♦ CHEMISTRY ♦ FORMALDEHYDE ♦ PHOTOLYSIS ♦ TITANIUM OXIDES ♦ CATALYTIC EFFECTS ♦ CHLORINATED ALIPHATIC HYDROCARBONS ♦ ULTRAVIOLET RADIATION ♦ CHEMICAL REACTION KINETICS ♦ WASTE PROCESSING ♦ HYDROGEN PEROXIDE ♦ POLLUTION CONTROL
Abstract Formaldehyde (HCHO) was decomposed in UV-irradiated aqueous suspensions of titanium dioxide. Initial HCHO levels in the range 60--1,000 ppm, a nominal TiO{sub 2} dose of 1 g/liter, and a medium-pressure Hg lamp were employed in these experiments. Chemical oxygen demand measurements of the solution before and after photocatalytic treatment revealed the mineralization of HCHO to be complete only for the lower end (<100 ppm) of the concentration range. Direct ultraviolet photolysis of HCHO also occurred, but this pathway had an initial lag unlike the photocatalytic route. In the presence of TiO{sub 2} and ultraviolet irradiation, the direct photolysis route was bypassed and the reaction proceeded dominantly by the photocatalytic route. The kinetics of the photocatalytic oxidation of HCHO were analyzed using several models. The effect of H{sub 2}O{sub 2} addition to the UV/TiO{sub 2} system was also probed as well as the homogeneous ultraviolet H{sub 2}O{sub 2} approach for the treatment of HCHO. The latter exhibited the fastest kinetics for the destruction of HCHO. Finally, the long-term stability and photocatalytic activity of TiO{sub 2} were monitored with two substrates, namely, HCHO and trichloroethylene in two different media: viz. pristine water and a real-life water sample with bicarbonate alkalinity. No degradation in the photocatalyst performance was noted over ten repeat use cycles in either case.
ISSN 00134651
Educational Use Research
Learning Resource Type Article
Publisher Date 1996-05-01
Publisher Place United States
Journal Journal of the Electrochemical Society
Volume Number 143
Issue Number 5


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