METHOD OF REDUCTION OF CONCENTRATION OF NITRATE AND/OR NITRIC ACID IN AQUEOUS SOLUTIONS Russian patent published in 2004 - IPC

FIELD: reduction of concentration of nitrate and/or nitric acid in aqueous solution. SUBSTANCE: proposed method is known as de-nitration method performed by reaction with formic acid or formaldehyde in presence of heterogeneous catalyst. Solutions to be treated may be formed in processes dealing with processing nuclear fuel, for example nitric acid solutions used for treatment of radioactive wastes, production of explosives and cleaning surfaces. Proposed method includes performing reaction by means of heterogeneous catalyst at the following stages: (a) bringing aqueous solution to be treated in contact with catalyst; (b) heating the reaction mixture obtained at stage (a) to required temperature from 60 to 100 C; (c) addition of formic acid or formaldehyde to reaction mixture; (d) keeping the reaction mixture at said temperature during period of time sufficient for obtaining required final concentration of nitric acid and/or nitrate. EFFECT: enhanced safety; possibility of obtaining complete de- nitration; avoidance of induction period. 15 cl