L. Fernando Bautista

Immobilization strategies for laccase from Trametes versicolor on mesostructured silica materials and the application to the degradation of naphthalene

The oxidation of naphthalene by immobilized laccase from Trametes versicolor has been performed using diverse immobilization strategies on mesostructured silica materials. Laccase was immobilized by physical adsorption on several SBA-15 with different textural properties and by covalent attachment on functionalized SBA-15 prepared by co-condensation method (direct synthesis). The adsorption of laccase was partially reversible and showed some degree of lixiviation. However, covalently attached laccase to aminopropyl and aminobutyl functionalized SBA-15 exhibited important activity for the degradation of naphthalene with, respectively, 35% and 39%wt of removal in 5h. The aminopropyl biocatalyst retained higher activity after repeated uses than the corresponding aminobutyl.

Low-grade oils and fats: Effect of several impurities on biodiesel production over sulfonic acid heterogeneous catalysts

Different lipidic wastes and low-grade oils and fats have been characterized and evaluated as feedstocks for the acid-catalyzed production of FAME. The characterization of these materials has revealed significant contents of free fatty acids, Na, K, Ca, Mg, P, unsaponifiable matter and humidity. Arenesulfonic acid-functionalized SBA-15 silica catalyst has provided yields to FAME close to 80% in the simultaneous esterification-transesterification of the different feedstocks, regardless of their nature and properties, using methanol under the following reaction conditions: 160 °C, 2 h, methanol to oil molar ratio of 30, 8 wt.% catalyst loading, and 2000 rpm stirring rate. Nevertheless, reutilization of the catalyst is compromised by high levels of impurities, especially because of deactivation by strong interaction of unsaponifiable matter with the catalytic sites. The conditioning of these materials by aqueous washing in the presence of cationic-exchange resin Amberlyst-15, followed by a drying step, resulted in a lower deactivation of the catalyst.

Evaluation of the Influence of Multiple Environmental Factors on the Biodegradation of Dibenzofuran, Phenanthrene, and Pyrene by a Bacterial Consortium Using an Orthogonal Experimental Design

For a bioremediation process to be effective, we suggest to perform preliminary studies in laboratory to describe and characterize physicochemical and biological parameters (type and concentration of nutrients, type and number of microorganisms, temperature) of the environment concerned. We consider that these studies should be done by taking into account the simultaneous interaction between different factors. By knowing the response capacity to pollutants, it is possible to select and modify the right treatment conditions to enhance bioremediation.