Nagaveni K, Sivalingam G, Hegde M S, Madras Giridhar
Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore-560012, India.
Environ Sci Technol. 2004 Mar 1;38(5):1600-4. doi: 10.1021/es034696i.
The photocatalytic degradation of various organics such as phenol, p-nitrophenol, and salicylic acid was carried out with combustion-synthesized nano-TiO2 under UV and solar exposure. Under identical conditions of UV exposure, the initial degradation rate of phenol with combustion-synthesized TiO2 is 2 times higher than the initial degradation rate of phenol with commercial Degussa P-25 TiO2. The intermediates such as catechol (CC) and hydroquinone (HQ) were not detected during the degradation of phenol with combustion-synthesized TiO2, while both the intermediates were detected when phenol was degraded over Degussa P-25. This indicates that the rates of secondary photolysis of CC and HQ occur extremely faster than the rates at which they are formed from phenol and further implies that the primary hydroxylation step is rate limiting for the combustion-synthesized TiO2 aided photodegradation of phenol. The degradation rates of salicylic acid and p-nitrophenol were also investigated, and the rates were higher for combustion-synthesized titania compared to Degussa P-25 TiO2. Superior activity of combustion-synthesized TiO2 toward photodegradation of organic compounds can be attributed to crystallinity, higher surface area, more surface hydroxyl groups, and optical absorption at higher wavelength.
采用燃烧合成的纳米二氧化钛在紫外光和太阳光照射下对苯酚、对硝基苯酚和水杨酸等多种有机物进行光催化降解。在相同的紫外光照射条件下，燃烧合成的二氧化钛对苯酚的初始降解速率比对商业德固赛P-25二氧化钛对苯酚的初始降解速率高2倍。在用燃烧合成的二氧化钛降解苯酚的过程中未检测到儿茶酚（CC）和对苯二酚（HQ）等中间产物，而在用德固赛P-25降解苯酚时这两种中间产物均被检测到。这表明CC和HQ的二次光解速率比它们由苯酚形成的速率快得多，进一步意味着初级羟基化步骤是燃烧合成的二氧化钛辅助光降解苯酚的限速步骤。还研究了水杨酸和对硝基苯酚的降解速率，燃烧合成的二氧化钛的降解速率比德固赛P-25二氧化钛更高。燃烧合成的二氧化钛对有机化合物光降解的优异活性可归因于结晶度、更高的表面积、更多的表面羟基以及在更高波长处的光吸收。
