Photo catalytic oxidation of TNT using TiO2-SiO2 nano-composite aerogel catalyst prepared using sol–gel process

The degradation of nitro aromatics like trinitrotoluene (TNT) released in the waste water from explosive process plants is the serious problem due to toxic and explosive nature of TNT. The poor response of TNT to biodegradation enhanced the gravity of the problem. We have demonstrated that high specific surface area TiO2–SiO2 nano-composite aerogel is promising photo catalyst in successful treating of TNT contaminated aqueous solution. The TiO2–SiO2 composite aerogel with nominal content of 20 and 50% TiO2, used as catalyst, were prepared by co-precursor sol–gel method using titanium isopropaxide and tetramethylorthosilicate as source of titania and silica, respectively. The XRD studies confirmed formation of anatase phase of crystalline TiO2 with nano sized crystallites. The TiO2–SiO2 aerogel showed specific surface area of 1,107 and 485 m2/g for the aerogels containing 20 and 50% TiO2, respectively. The 100 ppm TNT solution was treated, in 700 ml capacity reaction vessel, using H2O2 oxidizer and TiO2–SiO2 aerogel catalyst in presence of UV light (8 W UV lamp). Using TiO2–SiO2 (50/50) aerogel with surface area of 485 m2/g, we succeeded to reduce the TOC to 1 ppm within 3.5 h where as using TiO2/SiO2 (20/80) aerogel with surface area of 1,107 m2/g, the TOC was reduced to about only 7 ppm in the same time. It revealed that the combination of high TiO2 content and high specific surface area is an important factor to achieve effective and faster degradation of TNT for complete mineralization.