Nanopartículas De Poli-Ε-Caprolactona Contendo Tbhq: Desenvolvimento, Caracterização E Aplicação / Poli Nanoparticles-Ε-Caprolacton Contents Tbhq: Development, Characterization and Application

Abstract

Devido à composição química, o biodiesel é muito suscetível à oxidação, tornando necessária a adição de antioxidantes que inibem ou retardam esse processo. Entretanto os antioxidantes ficam expostos à condições que podem degradá-los, reduzindo sua eficiência. Dessa forma, o uso de nanoesferas (NE) surge como alternativa para proporcionar a proteção dos mesmos. Neste sentido, o objetivo deste trabalho foi desenvolver NE de poli-ɛ-caprolactona contendo o antioxidante terc-butil-hidroquinona e aplicá-las no biodiesel. O método utilizado na produção das NE foi emulsificação-evaporação do solvente e a estabilidade foi avaliada durante 31 dias na estufa à 30°C, sendo analisados o tamanho, polidispersão, potencial zeta, atividade antioxidante e pH durante o período estudado, além da avaliação do tempo de indução do biodiesel contendo as NE. Após o período analisado, as NE sofreram variações estatisticamente significativas no pH (6,20 para 7,63), potencial zeta (-12,50 mV para-13,83 mV) e a atividade antioxidante (84,4 para 51%). Quanto ao TI, a adição das NE ao biodiesel não resultou em variações significativas.

Antioxidant Activity and Physicochemical Stability of Nanospheres: Evaluation in Vitro and Applied to Biodiesel

“…The homogeneity in the distribution of NE particle sizes is measured by the polydispersion index (IPD), which, for reference, considers values between 0 and 1. Results close to zero indicate greater homogeneity of the system, and results near to 1 re ect a heterogeneous system [12,14]. According to the results of Table 1, the greatest homogeneity was obtained for the TBHQ NE, followed by the NE without active.…”

“…The encapsulation e ciency (EE) was indirectly determined by quantifying non-encapsulated active present in the supernatant after centrifuging a 2 mL aliquot of each NE suspension at 15000 rpm for 50 minutes [12] The actives were quanti ed via Uv -Vis ( Thermo Scienti c Evolution 201) at wavelengths of 287 nm, using a previously prepared calibration curve. To the curve, aqueous solutions of TBHQ were used at concentrations of 2, 4, 6, 10 and 20 mg L − 1 , obtaining R 2 = 0.9991 and y = 0.0199 x + 0.0053.…”

“…The EE of the AA NE solution was determined using an indirect method, in the same way as the TBHQ and under the same conditions [12]. The non-incorporated active was quanti ed via UV -vis at a wavelength of 264 nm.…”

“…Nanospheres ( NE) were prepared using the emulsi cation protocol followed by solvent evaporation, described by Mainardes and Evangelista [11], with modi cation. According to Hagemann and collaborators, the preparation of the emulsion has two phases: organic and the other aqueous [12]. Five formulations of TBHQ nanospheres were performed, and in two of these, the amount of all reagents was multiplied by 3, and added to a 100 mL volumetric ask made up of volume with distilled water.…”