Hydrolysis and Free Radial Mediated Degradation of Phosphonates

While studying the biodegradation and environmental fate of phosphonates, two almost undocumented nonbiological degradation processes acting on the stable C‐P bond were observed. Under test conditions comparable to the environmental situation, phosphonates in solution are prone to a slow light‐independent hydrolytic cleavage of the C‐P bond(s). The process requires divalent cations, aerobic conditions, and is particularly active on N‐containing phosphonates. Highest hydrolysis rates, up to 1% phosphonate‐P converted to inorganic phosphate per day, were measured with the polyphosphonates. Second, C‐P bonds in all phosphonates can efficiently be cleaved, also with release of orthophosphate, by means of physicochemically generated free radicals. The riboflavin/light and Cu 2+ /H 2 O 2 systems were more efficient than the Fenton reagent (Fe 2+ /H 2 O 2 ) in this respect. Both processes are likely to contribute to the removal of xenobiotic phosphonates in the environment, particularly in the absence of photo‐ and biodegradation.