The Reaction Mechanism And Mass Transfer Kinetics Of NO₂in No Absorbing Into Alkaline Solution

With the grown of nitric oxides （NO_x） emissions from the industrial waste gas in ourcountry, the environmental pollution and ecological destruction caused by NO_xisaggravating, therefore, considering the characteres of NO_xemmsion in our country andeconomical benefit of the industries, studying on the settlement of nitric oxides by wetprocess appears to be an increasingly major theoretical and practical significance. Inpractice, the effect of alkali absorption is conditioned by the NO_xoxidation degree, anddifficult to reach ideal effect. This paper adopts to inject addition of NO₂into the simulatedindustrial waste gas, improve the efficiency of lye on the absorption of NO_xby adjusting thevolume fraction of NO/NO₂ratio, and does systemic research on the mechanism ofabsorption.The effect the various influence factors on the process of absorption in experimentalresearch, the results indicated that the absorption of NO_xhas been increased observably inthe presence of NO₂and the removal efficiency of NO was higher than the removalefficiency of NO₂when the feed concentration of NO_xwas above600×10-6and the NO/NO₂ratio was within the range of0.5to2.0. Furthermore, the results of IC and HPLC analysison the products and SA showed that there were some non-stationary intermediate speciesformed from NO absorption induced by NO₂and significantly, there may be some novelsimilar-catalysis mechanisms in the removal of NO by injecting NO₂into alkaline solution.In this article, the kinetics of mass transfer-absorption of NO and NO₂in the bubblingtower was studied, considering the effect factors of NaOH concentration, NO_xconcentration,the volume fraction of NO/NO₂, temperature and gas velocity on mass transfer andabsorption rate, the experience resulted that enhancement of NaOH concentration wasnonsignificantly useful for the absorption rate, while increasing of NO_xvolume fraction wasbeneficial to mass transfer-absorption rate, and the mass transfer and absorption rate wasexceeding when the NO/NO₂ratio at0.5-2.0, temperature rising was not conducive to masstransfer and absorption, to speed up the gas velocity can enhance mass transfer andabsorption rate to some extent.Based on combine Response Surface Method and Box-Behnken design method, theinvestigation on the interaction of the main factors in the operation and optimize the mainoperating conditions is studied, as to the optimal removal efficiency of NO_x, the optimumoperating conditions were as follows: CNaOH0.36mol·L-1, volume fraction ratio of NO/NO₂ 1.04, gas velocity0.07m·s-1, absorption efficiency of NO_xin bubbling tower is the largest,up to92.5%.