Banca de QUALIFICAÇÃO: ALEXANDRE AUGUSTO PAREDES SELVA FILHO

Production of a Biosurfactant for the formulation of an ecological degreaser for use in the treatment of

environments contaminated by petroleum products (BIOGRAXA)

spills; oils; biosurfactant; Starmerella bombicola and biodegreaser.

Spills of fuel and lubricating oils that occur during filling machines, storage tanks and washing equipment are the main causes of the accumulation of petroleum products in the environment. Therefore, the application of natural agents appears as an attractive and efficient solution in this process. Due to their amphipathic structures, biosurfactants solubilize the oil through the formation of small aggregates which disperse in water. In this sense, the surfactant properties of the biosurfactant from the yeast Starmerella bombicola ATCC 222214 were investigated, as well as its stability at different levels of pH, temperature and NaCl concentrations. The ecotoxicity of the surfactant was studied for bioindicators such as Brassica oleracea and Solanum lycopersicum, aiming for its use in the removal of environmental pollutants in sand and seawater, in the inhibition of metallic corrosion and in the formulation of an ecological biodegreaser. The substrate selected for surfactant production contained 2% potato flour, 5% residual canola oil and 0.2% urea in a mineral medium. The selected cultivation conditions were agitation speed of 200 rpm, fermentation time of 180 hours and inoculum size of 5%. The production yield of isolated biosurfactant was 7.714 kg/L and the emulsification rate of the proportion of OCB1 and motor oils (3:1) was 66% and that of just motor oil reached 95%, indicating great affinity of the microbial surfactant for the oils. Stability tests of the microbial surfactant demonstrated little variation in its surface tension for all tested conditions, ranging from 27.14 to 31.08 mN/m. The plant Critical Micellar Concentration (CMC) was 2.0 g/L with a surface tension at that point of 33.26 mN/m. The biosurfactant proved to be practically non-toxic for the bioindicators tested. Furthermore, the surfactant removed 94.39% of hydrophobic contaminants in the environment and effectively inhibited metal corrosion. The surfactant is being evaluated as a component in the formulation of an ecological degreaser capable of quickly cleaning fuel oil residues embedded in parts of industrial equipment. The biosurfactant under study has clearly demonstrated the viability of its application as a biotechnological additive for environmental remediation processes and for maintaining the cleanliness of the industrial environment, improving working conditions for responsible operators, with economic gains for industries in different segments in the country.