Patent ID: 8784762

Claim:
A method of treating a gas stream comprising NO x , the method comprising: generating a gas stream comprising NO x from an acid pickling solution in an acid pickling tank, bath, or spray; contacting the gas stream comprising NO x with ozone in a first chamber, thereby forming oxidation products including nitrogen sesquioxide and nitrogen pentoxide; directly following the preceding step, reacting at least a portion of the nitrogen sesquioxide and nitrogen pentoxide with water in the first chamber, thereby forming nitric acid in the first chamber; collecting at least a portion of the nitric acid in a second chamber in direct fluid communication with the first chamber; and recycling the nitric acid from the second chamber into the acid pickling tank, bath, or spray; wherein the gas stream comprising NO x is not treated with a caustic scrubbing solution in a scrubber between generating the gas stream comprising NO x and recycling the nitric acid.