Abstract: An embodiment of a method for recovering nitric acid from acid pickling solution includes introducing a treating material comprising at least one chemical into a pickling solution comprising free nitric acid. The treating material reacts with at least a portion of the free nitric acid in the pickling solution and produces NOx. A gas stream comprising at least a portion of the NOx is contacted with ozone, thereby forming oxidation products including nitrogen sesquioxide and nitrogen pentoxide. At least a portion of the nitrogen sesquioxide and nitrogen pentoxide is contacted with water, thereby forming nitric acid, and at least a portion of the nitric acid is collected.

Abstract: A method that employs a dilute solution, such as a dilute hydrogen peroxide solution, and concentrates the dilute solution to a yield a concentrated solution. A concentrated solution prepared by the method of the invention is useful as a rocket fuel, a laser fuel and industrial and laboratory chemical reagents.