Primary aerobic biodegradation of linear and oxo alcohol alkylpolyglucosides (APG)

Abstract

Alkylpolyglucosides (APG) prepared on the basis of renewable raw materials have been proven ultimately readily biodegradable. They are completely green surfactants. With the development of the petrochemical industry, APG prepared by oxo alcohol have been widely used recently. They have equal physicochemical properties with those prepared with renewable raw materials, but there is little information about their environmental compatibility. Primary aerobic biodegradability of linear alcohol and oxo alcohol APG was compared in this study. The results showed that oxo APG had similar good blodegradability with linear alcohol APG. In a shaking-flask test, more than 87% APG could be degraded after 21 d and are therefore completely green surfactants. The relationship between structure and biodegradability was studied. The hydrophobic and hydrophilic groups affected their biodegradation. Biodegradability deteriorated with increasing chain length and size of head groups. Branching did not affect their biodegradation. The degradation rate decreased with increasing head group size. Monoglucoside degraded faster than diglucosides, and diglucosides degraded faster than polyglucosides. Accordingly, a potential degradation pathway was proposed. APG were hydrolyzed to alcohol and polysaccharide in the first step, then the alcohol was oxidized to CO₂ and H₂O by β or α oxidation. The polysaccharide was hydrolyzed to glucose, and then the glucose was degraded by a glucose metabolism mechanism. This pathway provided a good explanation of the experiment results.