Patent Number: 048246077
Section: description

DETAILED DESCRIPTION OF THE INVENTION The practice of the present invention provides numerous advantages. Thus, in the present invention, the nitric acid containing waste solution and the denitration reagent can be mixed together already at room temperature. The denitration reaction begins at about 75.degree. to 90.degree. C. A certain induction period for the desired reaction, such as occurs in the denitration with glycerin, does not occur in the process according to the present invention. Excess ethyl alcohol from the denitration reagent can be removed from the reaction solution by simple distillation so that subsequent decomposition of a residual quantity, as in the case of formic acid or formaldehyde, with hydrogen peroxide is no longer necessary as for example in other denitration processes to destroy an excess of reagent (e.g. formic acid). An additional increase in th the waste solution, as in the case of the addition of sugar, is also avoided. It has been found that a mole ratio of 0.5 to 1.5 ethyl alcohol to 1.0 nitric acid is sufficient for substantial denitration, preferred 0.5 to 1.0 ethyl alcohol to 1.0 nitric acid. Suitable ranges for the time of heating are 1 to 4 hours and for the heating temperature are 75.degree. to 100.degree. C. The concentration of nitric acid in the starting solution can be between 0.5 and 5 moles/1 or more. The percentage of nitric acid which can be decomposed arises up to ca. 98%. The aqueous waste solutions which are treated can be, for example, a radioactive waste solution containing nitric acid, actinides, fission products and inactive compounds in different concentrations and inactive solutions containing nitric acid and other compounds in different concentrations. The present invention will now be described in greater detail with the aid of the following example which is given by way of illustration to further explain the principles of the invention. This example is merely illustrative and is not to be understood as limiting the scope and underlying principles of the invention in any way. All percentages referred to herein are by weight unless otherwise indicated. EXAMPLE A round bottom flask with an attached cooler, magnetic stirrer, thermometer and mushroom-shaped heater, was employed to denitrate an aqueous nitric acid and salt containing solution. In a first test, the cooler was a Liebig cooler and in a second test, the cooler was a reflux condenser. In each test, a simulated, nitric acid containing waste solution was mixed at room temperature with ethanol (mole ratio HNO.sub.3 /C.sub.2 H.sub.5 OH=1). Then the mixture was heated while being stirred. At approximately 75.degree. to 80.degree. C., gas began to develop and the mixture began to boil. The reaction solution was heated to about 95.degree. to 100.degree. C. and maintained at that temperature. After cooling, the residual acid concentration was determined by titration with sodium hydroxide solution. The composition of the simulated waste solution employed in both tests was as follows: ______________________________________ HNO.sub.3 : 1 mol/l Na: 81 g/l Al, Ca, Cr, Cu, Fe, K, Mg, 24 g/l (total) Mn, Mo, Ni, Ru, Zn, Cs, Sr: nitrate: 251 g/l ______________________________________ The metals were used in the form of their nitrate salts. The results of the two tests are as follows: (a) Cooler: Liebig PA0 Denitration reagent: ethanol PA0 Starting solution: 200 ml simulated waste solution PA0 (b) Cooler: Reflux condenser PA0 Denitration reagent: ethanol PA0 Starting solution: 200 ml simulated waste solution ______________________________________ Time [min] 90 180 240 ______________________________________ % of orig. 73 75.5 78 existing HNO.sub.3 decomposed ______________________________________ ______________________________________ Time [min] 90 180 240 ______________________________________ % of orig. 94.5 95.5 95.5 ______________________________________ It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.