A process for inhibiting corrosion caused by the presence of chlorine dioxide in apparatus consisting wholly or partly of stainless steel

摘要

Corrosion of apparatus comprising stainless steel components in which clorine dioxide or water-soluble chlorites are used, e.g. apparatus used in the bleaching of textile material, cellulose pulp, flour, oils or fats, is inhibited by introducing into the apparatus a mixture of water vapour and the vapours of nitric acid and an acid volatile in steam. The chlorite or chlorine dioxide may be present in goods contained in the apparatus, e.g. in the bleaching of textile materials with aqueous chlorite solutions, and the acid-water-vapour mixture separately introduced, or goods containing a chlorite and an acid volatile in steam may be present in the apparatus, e.g. in bleaching textiles with acid-chlorite solutions, and the vapour from a boiling nitric acid solution separately introduced, or the apparatus may be used for a process, e.g. of bleaching, oxidizing or disinfecting, wherein chlorine dioxide and the acid-water-vapour mixture are introduced. The acid volatile in steam may be hydrochloric, hydrobromic, formic, acetic, propionic, lactic or keto-butyric acid. The chlorite may be of sodium, potassium or calcium. Reduction of the nitric acid, e.g. with formic acid, may be prevented by the presence of urea or uric acid in the boiling solution from which the nitric acid is evolved. The nitric acid may be liberated in the solution from its salts, using sulphuric or phosphoric acid. Textile fibres, yarns or fabrics of natural or regenerated cellulose, polyesters, polyvinyl chloride, and polyacrylonitrile may be bleached by the process. Examples refer to bleaching flour, sulphite pulp and cotton and viscose rayon materials. Specification 696,967 is referred to.