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Show 1990 AFRC Int'l Symposium mechanism by which this system is thought to proceed consists of two different NO reaction paths and is as follows : NOg C12, g C12, aq + H20 HOCl aq + NO aq C12, aq + NOaq NOaq + Claq = NOClaq + H20 3 HN02, aq NOaq C12, aq HOCl + H+ + Cl- HN02, aq + Claq NOClaq + Claq NOClaq HN02, aq + H+ + ClH30+ + N03- + 2 NO (7) (8 ) (9 ) (10 ) (11 ) (12) (13 ) (14) It is concluded that the most important NO reducing reaction in the mechanism is Equation 11. This conclusion is based upon two observations: 1. NO removal efficiency in this system is greater at the lower ranges of pH 2. From the C12 hydrolysis equilibrium, C12, aq is the predominant chlorine species at lower pH This reaction is hypothesized to account for the majority of the +90% removal efficiency seen in the HCl scrubbing trials. The oxidation of NO by HOCl and Cl are perhaps minor reactions in the overall mechanism. Equation 10 has some support in the literature [Ghibaudi, Barker, Benson[1979]. An unfortunate side reaction is the production of the trichloride ion, Equation 6. This reaction consumes the highly reactive C12, aq and, through equilibrium shifts, begins limiting the extent of NO oxidation by that species. Hence, scrubbing with more concentrated brines or acids would result in lower NO removal efficiencies. Analysis of the scrubber solutions in all trials (water, NaCl, HC1) positively identified the presence of N03-, with insignificant levels of N02-' in solution. 100 c: 0 ..-1 .,; 80 ;:l ...... 0 til c: ..-1 60 <II c: ..-1 ~ 0 ...... ..c: 40 () ...... ", .,; 0 .,; 20 ..... 0 '*' Cl 3 0 0 Hydrolysis of Cl 2 in water @ 25°C 2 \ / / \/ t ' tJ ,t / +- ' \ .' +- / \ 4 - -~ / ' HOCl \ 6 pH '1Il11111l1l~"11111IC \ I- OCl \**** * : ~\ )fE. * \ ** \ 8 \ 10 12 Figure 14 -12- |