Characterization of Titanium (IV) Oxide Nanoparticles Loaded onto Activated Carbon for the Adsorption of Nitrogen Oxides Produced from the Degradation of Nitrocellulose

Abstract

The stability and performance of nitrate ester-based energetic materials may be compromised by their degradation, which is primarily promoted by the NOx. To overcome this issue, the typical approach is the addition of stabilizers to the original formulation of the energetic materials. However, this is not always suitable, particularly if pure materials are needed. Thus, this work presents a new method consisting of capturing the released NOx on activated carbons impregnated with TiO2 nanoparticles. The principle is to perform the oxidation of NOx to HNO3 by photocatalysis in presence of TiO2. Consequently, four different activated carbons are prepared by chemical activation with ZnCl2 and H3PO4 to achieve diverse textural and functional properties. They are subjected to impregnation with 1 wt. % of TiO2. Hence, they are thoroughly characterized by means of nitrogen sorption isotherms, Fourier transform infrared spectroscopy and X-ray fluorescence. Afterwards, their efficiency under different light conditions is assessed through the capture of NOx evolved from the accelerated degradation of nitrocellulose quantified by Bergmann-Junk test. The quantity of captured NOx is determined by ion chromatography. The results show that a combination of a micro and mesoporous material with low surface functions is the optimal criterion to achieve the desired deposition rate of TiO2. This is obtained by the heat-treated activated carbon synthetized using H3PO4. In addition, more than 60% of the released NOx are efficiently captured by the prepared materials under ultraviolet light, corresponding to 0.0723 mmol of NOx per gram of impregnated activated carbon.