Janus M, Choina J, Morawski A W
Szczecin University of Technology, Department of Sanitary Engineering, al. Piastów 50, 70-310 Szczecin, Poland.
J Hazard Mater. 2009 Jul 15;166(1):1-5. doi: 10.1016/j.jhazmat.2008.11.024. Epub 2008 Nov 18.
New vis active photocatalyst was obtained by the modification of commercial anatase TiO2 (Police, Poland) in pressure reactor in an ammonia water atmosphere at 100 degrees C for 4h. The photocatalytic activity of new material was tested during three azo dyes decomposition: monoazo (Reactive Read), diazo (Reactive Black) and poliazodye (Direct Green). Obtained photocatalyst had new bands at 1430-1440 cm(-1) attributed to the bending vibrations of NH(4)(+) and at 1535 cm(-1) associated with NH(2) groups or NO(2) and NO. UV-vis/DR spectra of photocatalyst had also insignificant decrease in visible region. Fluorescence technique was used for studying the amount of hydroxyl radicals produced on TiO2 surface during visible light irradiation. The hydroxyl radicals produced react with coumarin present in the solution to form 7-hydroxycoumarin which has fluorescent capacity. Photocatalytic activity of modified TiO2 was compared with commercial titanium dioxide P25 (Degussa, Germany). The photocatalytic activity of TiO2/N was higher than that of unmodified material and P25 under visible light irradiation. The ability for dye adsorption (Reactive Red) on photocatalyst surface was also tested. Unmodified TiO2 and P25 has isotherm of adsorption by Freundlich model, and nitrogen-modified TiO2 by Langmuir model. The presence of nitrogen at the surface of TiO2 significantly increased adsorption capacity of TiO2 as well as OH radicals formation under visible radiation.
新型可见光活性光催化剂是通过在压力反应器中，于100℃的氨水气氛下对商用锐钛矿型TiO₂（波兰警察公司）进行4小时改性而制得的。在三种偶氮染料分解过程中测试了新材料的光催化活性：单偶氮染料（活性红）、双偶氮染料（活性黑）和多偶氮染料（直接绿）。所获得的光催化剂在1430 - 1440 cm⁻¹处有新的谱带，归因于NH₄⁺的弯曲振动，在1535 cm⁻¹处与NH₂基团或NO₂和NO相关。光催化剂的紫外 - 可见漫反射光谱在可见光区域也有不明显的下降。采用荧光技术研究了TiO₂表面在可见光照射下产生的羟基自由基的量。产生的羟基自由基与溶液中存在的香豆素反应形成具有荧光能力的7 - 羟基香豆素。将改性TiO₂的光催化活性与商用二氧化钛P25（德国德固赛公司）进行了比较。在可见光照射下，TiO₂/N的光催化活性高于未改性材料和P25。还测试了光催化剂表面对染料（活性红）的吸附能力。未改性的TiO₂和P25符合Freundlich模型的吸附等温线，而氮改性的TiO₂符合Langmuir模型。TiO₂表面氮的存在显著提高了TiO₂的吸附能力以及可见光辐射下OH自由基的形成。
