A study performed using a river water-sediment system found that glutaraldehyde degraded rapidly under both aerobic and anaerobic conditions. In this system, glutaraldehyde was found to partition primarily to the water phase, with a pseudo-first-order half-life of 10.6 hours under aerobic conditions and 7.7 hours under anaerobic conditions (Leung 2001).
Glutaraldehyde was stable in sterilized control samples maintained at pH 5 and 7 for 31 days; however, at pH 9, 30% was degraded, primarily to a cyclicized dimer of glutaraldehyde, 3-formyl-6-hydroxy-2-cyclohexene-1-propanal.
Extrapolated half-lives for abiotic degradation of 508, 102, and 46 days at pH 5, 7, and 9, respectively were calculated.
Under aerobic conditions, glutaraldehyde was found to degrade to glutaric acid and subsequently carbon dioxide, whereas under anaerobic conditions, it was degraded into 5-hydroxypentanal followed by 1,5-pentanediol (Leung 2001).
A second study from the EPA Registration Eligibility Decision (RED) document for glutaraldehyde reported hydrolysis half-lives at 25°C of 628, 394, and 63.8 days at pH 5, 7, and 9, respectively (EPA 2007).
At 70°C, hydrolysis of glutaraldehyde proceeds more rapidly with half-lives of 53, 6.5, and 0.23 days at pH levels of 5, 7, and 9, respectively.
Glutaraldehyde was also photolytically degraded to a small degree in natural sunlight at 25°C. The half-life was calculated to be 195 days. A buffered, aqueous solution at pH 5 was used in the experiment (EPA 2007).