A process for removing nitrogen oxides including nitrogen monoxide from a gaseous mixture such as industrial waste gases is provided. The gaseous mixture is contacted, first, with an aqueous solution of a chlorate and, then, with water, an aqueous solution or dispersion of a basic compound or an aqueous alkaline solution or dispersion of a reducing agent.
A process for purifying, by the wet method, fumes containing nitrogen oxides in which nitrogen monoxide is oxidized by an oxidizing agent into nitrogen dioxide which is itself reduced to nitrogen by using the reducing properties of sulfur dioxide present in the fumes and wherein the reduction is effected with the aid of an intermediate agent which prevents the transfer of nitrogen oxides in the form of nitrates to the effluent of the purification process.
The present invention relates to a process for reducing the concentration of NO in a gas, which process comprises: (A) contacting a gas sample containing NO with a gaseous oxidizing agent to oxidize the NO to NO.sub.2 ; (B) contacting the gas sample of step (A) comprising NO.sub.2 with an aqueous reagent of bisulfite/sulfite and a compound selected from urea, sulfamic acid, hydrazinium ion, hydrazoic acid, nitroaniline, sulfanilamide, sulfanilic acid, mercaptopropanoic acid, mercaptosuccinic acid, cysteine or combinations thereof at between about 0.degree. and 100.degree. C. at a pH of between about 1 and 7 for between about 0.01 and 60 sec; and (C) optionally contacting the reaction product of step (A) with conventional chemical reagents to reduce the concentrations of the organic products of the reaction in step (B) to environ-mentally acceptable levels. Urea or sulfamic acid are preferred, especially sulfamic acid, and step (C) is not necessary or performed.
Method for wet cleaning gases to remove low soluble pollutants such as mercury metal and nitrogen monoxide. An oxidizing agent is released from a compound such as a sodium chlorite, injected into a recycle stream being conveyed for dispensing into a scrubber, by a releasing agent, such as finely divided solids in the recycle stream, so that the oxidizing agent becomes available at the time of dispersion into the scrubber to oxidize the pollutants on the surface of droplets dispersed throughout the gases in the scrubber. The resulting oxidized pollutants have increased solubility and are transferred to a scrubbing liquid.
