Formic aqueous corrosion

In order to obtain information regarding the composition of these degradation products, aqueous extracts of the lead soaps of the linseed oil fatty acids were analysed, mainly by chromatography. The extracts contained formic acid 46%, azelaic acid 9% and pelargonic acid and its derivatives 27%, the remaining 18% consisting of a mixture of acetic, propionic, butyric, suberic, pimelic and adipic acids. It was shown that whereas the salts of formic acid were corrosive, those of azelaic and pelargonic acid were very efficient inhibitors. 

CHEMICAL PROPERTIES Flammable gas volatile corrosive to carbon steel slowly oxidizes to formic acid react violently with strong oxidizers FP (133°F) AT (300°C for gas, 430°C for aqueous solutions) LFL (7.0%) UFL (73%). 

Films of regenerated cellulose, for example, Cellophane 600, Gel cellophane, Ultracella, grades fine and ultrafine, are used as membranes for organic solvent systems. For aqueous solutions, membranes of cellulose acetate (for example ultrafine filter) or nitrocellulose (collodium) are suitable. Corrosive solvents, such as formic acid, etc., require the use of glass membranes. 

Singh SK, Mukherjee AK, Singh MM (2011) Kinetics of mild steel corrosion in aqueous formic acid solutions. Can Metall Quart 50 186-194... 

The ability of copper salts to dissolve carbon monoxide was first discovered by Leblanc (1850). Early interest in the phenomenon centered around its use in gas analysis for the determination of carbon monoxide. The first aqueous solutions were generally acid and unsuited for use in conventional equipment because they caused severe corrosion. This problem was mitigated by the use of salts of weak acids, such as carbonic and formic, rather than previously used salts of hydrochloric or sulfuric acids. 

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