Study Of The Biodegradation Of Polyglycoside Surfactants

Many domestic and foreign scholars have conducted the research on polyglycosides, most of them concentrate on the synthesis process, separation, purification and properties improvement. However, the study of biological degradation of polyglycosides is very little. In addition, there is only the standard method for the primary biodegradation of surfactants in our country, and the detection of the content of glycosides also has some defects. Therefore, it is of great significance to carry out the research of primary and ultimately degradation of polyglycosides.In this thesis, shaking method and closed bottle method were conducted to detect the primary and ultimately biodegradation of the alkyl polyglycosides (APG0810, APG1214, C10APG, OXO-C10APG) and alkylethoxyglucosides (AEG300, AEG050). The experiments were proceeded as follows:adjusting the degradation liquid medium, investigating the factors affecting biodegradation, primary and ultimately biodegradation properties and pathway of polyglycosides.1. Shaking method was adjusted by using the free yeast extract medium, which effectively avoids the determination of the influence of polyglycosides content. At the same time, the free yeast extract medium was also used to test the degradation of other common surfactants. The results showed that the free yeast extract medium had little influence on the degradation performance of various surfactants, thus, it could be applied to the rapid biodegradation test of other surfactants.2. The pH. microbial source and surfactant concentration were investigated to obtain the influence of biodegradation of polyglycosides. It showed that the biodegradation of polyglycosides is the best as using the activated sludge of the wastewater treatment plant as the microbial source, and the pH and the surfactant concentration were confined at 7 and 30 mg/L.3. The primary and ultimately performance biodegradation of alkyl ployglycosides and alkylethoxyglucosides were studied. The results showed that when the degradation lasted to the ninth day, the primary biodegradation degree of both alkyl polyglycosides and alkylethoxyglucosides was up to 90%, and the final biodegradation degree of them was about 70%. The biodegradation performance of alkyl polyglycosides of different carbon chain was evaluated, and it was found that the longer the carbon chain, the easier the biodegradation. The biodegradation of EO for polyglucosides was also analyzed. It can be shown that alkylethoxyglucosides with less EO content were easier to be degraded and the addition of EO had no impact on the biodegradation performance of alkyl polyglucoside and alkylethoxyglucosides with the same carbon chain.4. Degradation intermediates of alkyl polyglycosides were determined by HPLC, and the possible degradation pathway of OXO-C10APG was estimated. The results showed that alkyl polyglycosides was firstly hydrolyzed to alkyl chains and glucose, then glucose and alkyl chains were decomposed by microorganisms in order, and finally they were all broken down into carbon dioxide, water and inorganic salts.