Effect of zeolites modification on their adsorption properties

Abstract

Atmospheric air pollution is determined by the functioning of both technogenic and natural sources of pollution. The main anthropogenic sources of pollution are: transport, industrial enterprises, energy facilities and agriculture. In order to select a rational and effective method of atmospheric emissions purification from harmful components, systematic study was carried out to identify the potential of natural zeolites of Georgia. In particular, four samples of zeolite-containing rocks were investigated: analcime, clinoptilolite, phillipsite, mordenite and their modified forms. By means of the chromatographic method of researching the adsorption properties of natural zeolites, the best adsorption capability of mordenite and its modified hydrogen form obtained by two methods towards nitrogen oxides has been revealed. The perspective and profitability of using the hydrogen form of mordenite treated with ammonium in the processes of purification of nitrous gases from exhaust gases is shown, as well as the possibility of using the recovered products (aqueous solutions of ammonium salts) obtained from its regeneration as a nitrogen fertilizer in agriculture. The experimental adsorption purification of the sample (H-mordenite) was carried out in the process of research. The sample was taken from the outlet pipe of the contact apparatus in the ammonia oxidation shop of the nitric acid production enterprise of LLC “Rustavi Azoti”. It has been found that the modified mordenites can be proposed as an environmentally friendly, highly efficient sorbent in the processes of air purification from toxic impurities. Of the two forms of H-mordenite investigated, the adsorption data obtained for NH4+-ion-modified mordenite is approximately 20 % better than the acid-modified form. It should be noted that the use of granulated zeolites (mordenite) in adsorbers with dense packing is very effective. It is also important from the economic point of view that it is possible to reuse spent high-silica sorbents after their regeneration by oxidation method, since such zeolites are resistant to oxidants, such as hydroxyl radicals, ozone, etc., and it is possible to regenerate them without removing them from adsorber.