The effects of urea modification and heat treatment on the process of NO2 removal by wood-based activated carbon.

The removal of NO(2) on urea-modified and heat-treated wood-based activated carbons was studied. From the obtained results it was found that these modifications, especially when done at 950 degrees C, have a positive effect on NO(2) adsorption and on the retention of NO (the product of NO(2) reduction by carbon). The presence of moisture in the system enhances the removal of NO(2) but negatively affects the retention of NO. It is possible that the formation of active centers on the carbon surface and some increase in the volume of supermicropores during the high temperature treatment play a significant role in these removal processes. The surface of the carbons was analyzed in terms of the pK(a) distributions. The qualitative and quantitative analyses of the NO(2) adsorption products were carried out by means of FTIR and TA techniques, respectively. The main products found on the carbon surface were the NO(3) and NO(2) species.