Abiotic and biotic degradation of five aromatic organosilicon compounds in aqueous media: Structure degradability relationships

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Silicones have many applications and are produced in large quantities. Despite their potential toxicity, information on their environmental mineralisation is scarce. Therefore, we investigated a group of five organosilicon compounds (o-MeOC 6H 4SiMe 3 (1), p-MeOC 6H 4SiMe 3 (2), (p-MeOC 6H 4) 2SiMe 2 (3), o-Me 2NC 6H 4SiMe 3 (4) and p-Me 2NC 6H 4SiMe 3 (5)), recently developed to be ‘benign by design’ based on their readily degradable core structure. Five different degradability tests were performed, one assessing hydrolytic and two analysing biological and photolytic stability, respectively. All substances, except (p-MeOC 6H 4) 2SiMe 2 (3), hydrolysed within 24 h to 50% indicating that this is one of the major pathways of their primary elimination. In agreement with previous research, none of the substances was readily biodegradable. In contrast, 100% of p-Me 2NC 6H 4SiMe 3 (5) was primarily eliminated by photolytic and hydrolytic processes. The elimination rates of the other substances ranged from 7% to 64%. Irradiation at shorter wavelengths increased both the extent and speed of photodegradation. Eleven transformation products of p-Me 2NC 6H 4SiMe 3 (5) were detected, all of which were completely eliminated within 64 min of irradiation with a Hg lamp (200–400 nm). The insertion of an electron-donating group on the benzene ring like in p-Me 2NC 6H 4SiMe 3 (5) clearly enhanced photolytic degradability but further research is necessary to achieve truly biodegradable silicones.

Original languageEnglish
Article number122429
JournalJournal of Hazardous Materials
Number of pages15
Publication statusPublished - 15.06.2020

    Research areas

  • Chemistry - Closed Bottle test, Manometric Respirometry Test, Hydrolysis, Photolysis, Transformation product