Preparation and characterization of cellulose fibers from Meghatyrsus maximus: Applications in its chemical derivatives.

Non-wood lignocellulosic fibers have emerged and are becoming increasingly important as an alternative source of cellulose for derivatives, functional materials, and biofuels. This work aimed, to obtain cellulose from Meghatyrsus maximus grass with adequate properties through an alkaline delignification and alkaline hydrogen peroxide bleaching. Meghatyrsus maximus was chemically characterized as lignocellulosic biomass, which consisted of 45.0 %, cellulose, 35.0 % hemicellulose, and 20.0 % lignin. The obtained cellulose was characterized by Fourier transform infrared spectroscopy, X-ray diffraction analysis, thermogravimetric analysis, and scanning electron microscopy. The alpha-cellulose content was 98.50 % with a crystallinity of 61.0 %. The morphological study by scanning electron microscopy images indicates a clean surface and removal of non-cellulosic components present in the initial raw fibers. These results showed that high-quality cellulose was obtained and is comparable to a commercial alpha-cellulose, highlighting Meghatyrsus maximus as an alternative source of lignocellulosic fibers.

Estudio de mezclas de asfaltenos a través de medidas de tensión interfacial / A study of asphaltene mixtures using interfacial tensión measurements

En el presente trabajo se presenta un estudio de mezclas de asfaltenos, empleando Tensión Interfacial (TI). Los pesos moleculares fueron obtenidos a través de la técnica de Osmometría de Presión de Vapor (VPO) en nitrobenceno a 100ºC. Los valores de tensión en la interfase Agua /Tolueno fueron obtenidos en muestras de asfaltenos y en mezclas de ellos en una relación en peso 1:1, a diferentes concentraciones. Los resultados obtenidos sugieren la presencia de agregados heterogéneos entre distintos asfaltenos, por otro lado se evalúa el efecto de un asfalteno con fuerte tendencia a la agregación, de un crudo con problemas de precipitación. Como era de esperarse el asfalteno Cerro Negro mostró mayor actividad interfacial, bajo las condiciones estudiadas. Sin embargo, no es así para el caso de las mezclas, en donde se observa que la presencia de los agregados heterogéneos influye en las propiedades interfaciales de los asfaltenos. Además se reporta un área promedio de 120 A2 por molécula, para los asfaltenos en una interfase agua/tolueno.

Here we present a study of asphaltene mixtures using interfacial tension. Molecular weight values were measuredby VPO in nitrobenzene at 100°C. The IT were measured at the water/toluene interface for asphaltene and asphaltene mixtures at different concentrations in ratios 1:1 of weight. Results suggest the presence of heterogeneous aggregates between different asphaltenes. On the other hand, the effect of an aggregation – prone asphaltene, obtained from a crude oil with precipitation problems was evaluated. As could be expected, Cerro Negro asphaltene showed a higher interfacial activity under the examined conditions. However, this was not the case for the above mixtures where an influence of the heterogeneous aggregates on interfacial properties of asphaltenes was observed. An apparent area of 120 A2 /molecule could be measured at the water/toluene interface.