Destruction of polypropylene packings in a nitrosol solution

This technical report involves the use of urea to neutralize nitrosol. The nitrosol is a solution of sulfuric acid with a concentration 78–80% and a low concentration of nitric acid. Polypropylene is used as packing in an absorption column, where the emission of SO2 and NOx (components of the products of combustion) produced from a coal-fired boiler are reduced. The effect of nitric acid on polypropylene at high temperatures was noticed. It was observed that the nitric acid in the nitrosol caused the polypropylene packing to be ineffective and therefore decreasing the efficiency of the absorption process. Experiments were run to determine the possibility of using urea and other chemicals to reduce the concentration of nitric acid in the nitrosol without reducing the strength of the sulfuric acid in the nitrosol. Different amounts of urea were added to a 250 ml of the sulfuric acid–nitric acid mixture and the concentration of NO3 in each sample was measured. The results indicate that the concentration of nitric acid in the sulfuric acid–nitric acid mixture decreases as the amount of urea added increased.