Keywords

Metalworking Additives, Aminic Antioxidants, Sodium Nitrite, Biocides

The Formation of Colored Compounds from Various Metalworking Additives in the Presence of an Acidified Solution of Sodium Nitrite 

Incidents of the formation of yellow residues have been reported in metalworking shops. A similar situation was reported aboard a naval submarine. A phenolic antioxidant common to those used in metalworking fluids formed a nitrophenol. A formic acid acidified butoxyethoxyethanol/water solution of sodium nitrite method was developed to test the formation of colored compounds with various metalworking additives. Various factors were evaluated to determine what could influence the color formation. The rate was found to be pH dependent. Phenolic and aminic antioxidants formed color compounds. None of the non-phenolic biocides, yellow metal corrosion inhibitors and amines tested formed colored solutions. GC-MS of selected solutions indicated the presence of nitrophenol and quinones in colored solutions and nitrosamine in non-colored solutions with the secondary amines. Nitrous acid forms or catalyzes the formation of colored compounds and forms nitrosamine with secondary amines.

Authors and Company/Institution

Joseph A. Weaver, Jr. and Matthew Hargadon, Hangsterfer's Laboratories, Mantua, NJ