OZONATION OF ETHYLENEDIAMINETETRAACETIC ACID (EDTA) IN AQUEOUS-SOLUTION, INFLUENCE OF PH VALUE AND METAL-IONS

Ozonation of ethylenediaminetetraacetic acid (EDTA) (C = 1 mmol/1, ozone dose 10 mg/min·1) in aqueous solution as a function of pH value (pH 3 and 7) was investigated. At pH 3 ethylenediaminediacetic acid, iminodiacetic acid, nitrilotriacetic acid, glyoxylic-, oxalic-, formic acid, glycine, ammonia, nitrate and H2O2 were identified and their quantities, as a function of ozone consumption, were measured. At pH 7 the same oxidation products, except formic acid and H2O2, are formed. The carbon balance shows that, at pH 3, 84% and, at pH 7, 62-81% of the organic carbon was covered by the identified products. After 100% EDTA-elimination the oxidation products are biodegradable. Whereas the presence of Ca2+ and Cd2+ ions has only little impact on EDTA-elimination, the rate of EDTA degradation is notably reduced by the addition of Fe3+ ions. © 1990.