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Photocatalytic Degradation of 2,4-Dichlorophenoxyacetic Acid, 4-Chlorophenol, and Oxalic Acid with Simultaneous Hydrogen Production under weak UV Light Illumination
ZHANG Xianghua;LIU Hong*;LI Wenzhao;XU Hengyong
2008, 29 (3):
281-286.
Photocatalytic degradation of three organic pollutants,2,4-dichlorophenoxyacetic acid (2,4-D), 4-chlorophenol (4-CP), and oxalic acid (OA), with simultaneous hydrogen evolution was investigated with weak UV light illumination. The photocatalytic reactions were carried out in 160 ml solutions of the pollutants (1.0 mmol/L) using 1.0%Pt/TiO2 (1.0 g/L) as the catalyst. After2 hillumination, 38.43, 0.05, and 111.35 μmol of hydrogen and 73.80, 4.49, and 175.99 μmol of carbon dioxide were produced. Simultaneously, 83.83% of2,4-D, 36.19% of 4-CP, and 98.81% of OA were removed. These results showed that OA and2,4-D were good electron donors for the photocatalytic hydrogen evolution. On the other hand, under the illumination of a strong UV light source with light intensity 150 times that the weak UV light, more than 90% of2,4-D and 4-CP were removed within 5 min. The amounts of hydrogen produced were 113.02, 38.98, and 191.30 μmol for2,4-D, 4-CP, and OA solutions, respectively, and 195.60, 31.41, and 306.96 μmol of carbon dioxide was also produced. Therefore an appropriate combination of the processes of weak UV light and strong UV light can perform ultimate mineralization of organic pollutants with high hydrogen production and collective carbon dioxide of easy disposal. In this way the pollutants can be removed, and the light energy and chemical energy of the organic pollutants can be transferred to chemical energy in the form of hydrogen.
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