Marcelo Vieira Migliorini

Preliminary studies of bio-oil from fast pyrolysis of coconut fibers.

This work studied fast pyrolysis as a way to use the residual fiber obtained from the shells of coconut ( Cocos nucifera L. var. Dwarf, from Aracaju, northeastern Brazil). The bio-oil produced by fast pyrolysis and the aqueous phase (formed during the pyrolysis) were characterized by GC/qMS and GC×GC/TOF-MS. Many oxygenated compounds such as phenols, aldehydes, and ketones were identified in the extracts obtained in both phases, with a high predominance of phenolic compounds, mainly alkylphenols. Eighty-one compounds were identified in the bio-oil and 42 in the aqueous phase using GC/qMS, and 95 and 68 in the same samples were identified by GC×GC/TOF-MS. The better performance of GC×GC/TOF-MS was due to the possibility of resolving some coeluted peaks in the one-dimension gas chromatography. Semiquantitative analysis of the samples verified that 59% of the area on the chromatogram of bio-oil is composed by phenols and 12% by aldehydes, mainly furfural. Using the same criterion, 77% of the organic compounds in the aqueous phase are phenols. Therefore, this preliminary assessment indicates that coconut fibers have the potential to be a cost-effective and promising alternative to obtain new products and minimize environmental impact.

Electrochemical methodology for determination of imidazolium ionic liquids (solids at room temperature) properties: influence of the temperature

A set of six imidazolium ionic liquids (1a–b, 2a–c, 3), that were solids at room temperature, were characterized by electrical impedance spectroscopy to obtain information about their polarization resistance (Rp), conductivity (σ) and charge transfer activation energy (Ea). These experiments were performed at different temperatures in a glass micro-cell, equipped with three platinum electrodes. The observed conductivities were due to charge transfer processes of molecular oxygen at the electrode surface and mass transfer processes within the IL matrix. Higher temperatures resulted for all ionic liquids in increased conductivities. X-Ray diffraction of the ionic liquids 2a–c suggested that a higher degree of supramolecular two-dimensional organization, higher density, is related to an easier oxygen-electrode approximation, lower Ea. Two distinct temperatures ranges were observed. The larger conductivity increases in the higher temperature range were explained by melting (ILs 1–2) and fluxional behavior/reorientation phenomena of the ionic liquids and are due to enhanced oxygen diffusion (IL 3). In general, the understanding of imidazolium ionic liquid electrochemical properties could facilitate the development of new applications.