Abstract
Oil spills and oil products destroy terrestrial and marine ecosystems. One solution to this is the use of biosurfactants. Biosurfactants are able to solubilize oil stains in soil and water. The intense reproduction of Eichhornia crassipes leads to a high density, causing obstructions in the waterway. The use of macrophytes for the production of biosurfactants represents the generation of value-added products. In this sense, roots of the plant were collected and they were submitted to several stages of extraction. The surface tension, the Critical Micellar Concentration (CMC) and the emulsification indexes were obtained for the extract. In addition, stability tests and applications of the vegetal extract were used to evaluate the removal of oil in sand and the dispersion of the oil in sea water. The plant extract was characterized by the presence of saponin, and the molecular structure of the biosurfactant was defined. The results showed a yield of 0.5 % of the vegetal extract, a surface tension of 27.57 mN/m and a high emulsification indexes of 65.4 %. Biosurfactant stability tests were performed at different pH, temperature and increasing concentrations of NaCl and they showed a little variation in the surface tension. The CMC of the vegetable biosurfactant was 1.4 g/L with a surface tension of 25.84 mN/m. The concentration of saponin was 1.29 g/L in the vegetal extract. The motor oil percentages removed from the sand by biosurfactant (CMC, 1/2 CMC and 2 times CMC), in the static test in packaged glass columns, were, respectively, 55.02, 57.41 and 68.04 %. The vegetable extract was also able to disperse 100 % of the motor oil into sea water. The biosurfactant was characterized as an unsaturated fatty acid. The tensoactive properties, the results of the petroderivative removal and dispersion experiments clearly demonstrate the feasibility of applying this new vegetable biosurfactant as a biotechnological additive to the remediation processes in environments affected by petroleum derived contaminants.
