PHOTOLYSIS OF AQUEOUS FORMIC-ACID AT 184.9 NM

Aqueous solutions of formic acid (0.1-2 mM) were irradiated with 184.9 and 253.7 nm light. Experiments were carried out in the presence and absence of dissolved oxygen. The present paper provides new data on th e influence of dissolved oxygen on the formation of byproducts. When o xygen is present, the photodecomposition of formic acid induces the pr oduction of hydrogen peroxide which photolyses and then enhances the r ate of formic acid oxidation. Under such conditions, formic acid is ox idized into CO2. In oxygen-free solutions, hydrogen peroxide is not fo rmed. In the range of formic acid concentrations used, only the 184.9 nm wavelength can give rise to the removal of formic acid. The photoly sis of formic acid leads to the production of carbon monoxide, carbon dioxide, oxalic acid and a product identified by GC/MS as the oxalic a cid formyl ester.