Poly (3-hydroxybutyrate) (P(3HB)) is the most studied thermoplastic biopolymer belonging to the polyhydroxyalkanoate (PHA) family, the main features of which include rapid biodegradability and biocompatibility. The bioplastic recovery process is an important step during production and can directly influence the characteristics of PHAs. However, more efficient methods for the production of P(3HB) are necessary to make it economically viable. The aim of the present study was to improve the standard, chloroform-based, extraction step for the recovery of P(3HB). The polymer was produced using a Ralstonia solanacearum strain. The following parameters were improved in the recovery process: heating time, separation method (filtration or liquid-liquid phase separation), biomass state (fresh or dry cell concentrate) and the solvent:biomass ratio. By improving the chemical extraction of P(3HB) we recovered 98% of the cumulative polymer and reduced the heating time by 75%. Furthermore, we improved the separation process and developed an extraction solution that was faster and more economical.

O presente trabalho teve como objetivo determinar a adequabilidade de três amostras de biopolímero xantana (Xa 06, Xa 82 e Xa 106) e uma clairana como viscosificantes de fluidos de perfuração de poços de petróleo, comparando com uma amostra de xantana comercial, Xanvis®. Foram realizadas análises reológicas, determinados os conteúdos de acetil, piruvato e íons Na+ K+ e Ca2+, e avaliada a capacidade viscosificante segundo norma específica da Petrobras. Os conteúdos de grupos acetil e piruvato para as xantanas e clairana diferiram significativamente entre si, mas foram compatíveis com valores preconizados ou citados na literatura concernente. Com relação ao conteúdo de íons, a xantana comercial apresentou quantidade de cálcio superior, as amostras Xa 06, Xa 82 e Xa 106 tiveram maior teor de potássio e a clairana maior teor de sódio. A viscosidade e a viscoelasticidade da amostra de xantana comercial foram superiores às demais amostras analisadas. Na análise como viscosificante para fluidos de perfuração as amostras de xantana comercial e Xa 106 atingiram os requisitos estabelecidos para os parâmetros n, K e força gel da norma Petrobras N-2605. Com a interpretação conjunta dos resultados obtidos pode-se inferir que apenas as xantanas Xanvis® e Xa 106 apresentam características adequadas à utilização como viscosificante em fluido de perfuração de petróleo. As demais amostras possuem características reológicas adequadas à utilização como espessantes ou estabilizantes em outros segmentos industriais, como em alimentos, tintas e cosméticos.

The aim of this study was to determine the suitability of three xanthans (Xa 06, Xa 82 and Xa 106) and a clairana biopolymer for use as drilling fluid thickeners and comparing them against a commercial sample, Xanvis®. Rheological analyses were performed to determine the acetyl, pyruvate and Na+ K+ and Ca2+ ion content and their thickening ability, according to Petrobras guidelines. The pyruvate and acetyl group content for the xanthans and the clairana biopolymer differed significantly, but they were consistent with the recommended values or those previously cited in the literature. With regard to the ion content, the commercial xanthan contained higher amounts of calcium, while Xa 06, Xa 82 and Xa 106 samples contained higher potassium levels and clairana had a higher sodium level. The viscosity and viscoelasticity of the commercial xanthan sample were higher than for the other samples. In the viscosity analysis of drilling fluids, Xanvis® and Xa 06 met the required parameters for n, K and gel strength (Petrobras regulation N-2605). In an analysis of the results obtained, only Xanvis® and Xa 106 presented the desired characteristics for use as drilling fluid thickeners. The other samples presented adequate rheological characteristics for use as thickeners and stabilizers in many industrial applications, such as food, paints and cosmetics.

Foi realizado um estudo teórico da transferência de hidreto entre o cátion 1-adamantila e isopentano, usando a teoria do funcional da densidade em nível PBE1PBE/6-31G(d,p). Os resultados indicaram que há formação de um íon carbônio como intermediário, que é mais estável que os complexos de van der Waals entre os íons carbênios e os alcanos. Os fatores entrópicos são bastante importantes e sobrepujam o termo entálpico à temperatura ambiente.

A density functional teory study of the hydride transfer between 1-adamantyl cation and isopentane has been performed at the PBE1PBE/6-31G(d,p) theoretical level. The results indicate that a carbonium ion is involved as intermediate and is more stable than the van der Waals complexes between the carbenium ions and the alkanes. Entropic factors are important and overcome the enthalpic term at room temperature.