Application of bacterial and yeast biosurfactants for enhanced removal and biodegradation of motor oil from contaminated sand

Background This study investigated the potential application of two biosurfactants for enhanced removal capability and biodegradation of motor oil contaminated sand under laboratory conditions. The biosurfactants were produced by the yeast Candida sphaerica and by the bacterium Bacillus sp. cultivated in low-cost substrates. The ability of removing motor oil from soil by the two biosurfactants was identified and compared with that of the synthetic surfactants Tween 80 and Triton X-100. Results Both crude and isolated biosurfactants showed excellent effectiveness on motor oil removal from contaminated sand under kinetic conditions (70-90%), while the synthetic surfactants removed between 55 and 80% of the oil. A contact time of 5-10 min under agitation seemed to be enough for oil removal with the biosurfactants and synthetic surfactants tested. The crude and the isolated biosurfactant from C. sphaerica were able to remove high percentages of motor oil from packed columns (around 90%) when compared to the biosurfactant from Bacillus sp. (40%). For the degradation experiments conducted in motor oil contaminated sand enriched with sugar cane molasses, however, oil degradation reached almost 100% after 90 d in the presence of Bacillus sp. cells, while the percentage of oil degradation did not exceed 50% in the presence of C. sphaerica. The presence of the biosurfactants increased the degradation rate in 10-20%, especially during the first 45 d, indicating that biosurfactants acted as efficient enhancers for hydrocarbon biodegradation. Conclusions The results indicated the biosurfactants enhancing capability on both removal and rate of motor oil biodegradation in soil systems.

Research Progress of Molecular Imprinting Cryogel / 分析化学

Cryogel is a kind of elastic, spongy hydrogel prepared via addition polymerization from monomers or cross-linking reaction from a polymer at a temperature lower than the freezing point of the solvent. Cryogel has been principally used in molecular imprinting cryogel based solid phase extraction in the field of analytical chemistry, which combines both the advantages of high selectivity of the molecular imprinting and the porous structure, high throughput of a cryogel. Molecular imprinting cryogel can be used as the stationary phase in a packed column, a monolith column, or the adsorbent in a separation membrane. A variety of molecules can act as template molecules, including small molecules, macromolecules, a certain fragment of a macromolecule, and even an inorganic ion. Both a simple template and a complex template can be used. When employing more than a molecule ( or an ion) as templates simultaneously, the method is termed as Mixed template. While high abundance components of a complex sample act directly as mixed template, we name the method as Pending template. Further, while an analogue, an isotopic label, or a fragment of the target substance acts as a template, the method is defined as Dummy template. However, the research on cryogel is insufficient and the application of the cryogel is narrow hitherto.