Banca de DEFESA: ALEXANDRE AUGUSTO PAREDES SELVA FILHO

APPLICATION OF BIOSURFACTANT IN THE TREATMENT OF ENVIRONMENTS CONTAMINATED BY PETRODERIVATIVES, INHIBITION OF CORROSION AND FORMULATION OF ECOLOGICAL DEGREASING (BIOGRAXA)

spills; oils; biosurfactant; Starmerella bombicola; corrosion; degreaser.

Oil spills that occur during tank filling are the main causes of the accumulation of petroleum derivatives in the environment. Thus, the application of natural agents contributes to economic gains for industries and innovation for science. 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 pH levels, temperatures and NaCl concentrations. The ecotoxicity of the surfactant was studied for bioindicators such as Brassica oleracea, Solanum lycopersicum and Artemia salina. In addition, its application in the removal of environmental pollutants in sand and seawater, in the inhibition of metal corrosion and in the formulation of an ecological biodegreaser was evaluated. The medium selected for the production of the surfactant was formulated with 2.0% potato flour, 5.0% residual canola oil and 0.2% urea in mineral medium. The selected culture conditions were agitation speed of 200 rpm, fermentation time of 180 hours and inoculum of 4.0%. The production yield of isolated biosurfactant was 7.714 g/L and the emulsification rate of OCB1 heavy oil and engine oil was 65.55% and 95.0%, respectively, indicating affinity of the microbial surfactant for the oils. The stability tests of the microbial surfactant demonstrated a variation in surface tension from 27.14 to 31.08 mN/m for all conditions tested. The Critical Micellar Concentration (CMC) was 2.0 g/L with a surface tension at that point of 33.26 mN/m. The biosurfactant is composed of 6,6-dimethoxy-octanoic and nonanedioic acids and is nontoxic to the bioindicators tested. Furthermore, the surfactant removed 98.25% and 94.39% of hydrophobic contaminants, respectively, in soil and seawater, acted satisfactorily as a marine bioremediation agent and effectively inhibited metal corrosion, reducing the mass loss of the specimens by 17.38%. The innovative biodegreaser was formulated with the biosurfactant at half the CMC, 10% natural solvent, 1.5% fatty alcohol, 0.7% stabilizing gum, 0.2% preservative and water. This product was able to remove approximately 99% of heavy oil from different surfaces, in addition to presenting long-term stability, reduced toxicity, corrosion inhibition and superior efficiency to commercial degreasers in cleaning metal parts. The tensoactive under study has clearly demonstrated its potential for application as a biotechnological additive for environmental remediation processes and for maintaining the cleanliness of the industrial environment, ensuring efficiency and sustainability in the removal of hydrophobic contaminants, suggesting economic gains for industries in different segments in the country.