Chemical pretreatment of Arundo donax L. for second-generation ethanol production

Background: Pretreatment of lignocellulosic biomass is essential for using it as a raw material for chemical and biofuel production. This study evaluates the effects of variables in the chemical pretreatment of the Arundo biomass on the glucose and xylose concentrations in the final enzymatic hydrolysate. Three pretreatments were tested: acid pretreatment, acid pretreatment followed by alkaline pretreatment, and alkaline pretreatment. Results: The amounts of glucose and xylose released by the enzymatic hydrolysis of the Arundo biomass obtained from acid pretreatment ranged from 6.2 to 19.1 g/L and 1.8 to 3.1 g/L, respectively. The addition of alkaline pretreatment led to a higher yield from the enzymatic hydrolysis, with the average glucose concentration 3.5 times that obtained after biomass hydrolysis with an acid pretreatment exclusively. The use of an alkaline pretreatment alone resulted in glucose and xylose concentrations similar to those obtained in the two-step pretreatment: acid pretreatment followed by alkaline pretreatment. There was no significant difference in 5-hydroxymethylfurfural, furfural, or acetic acid concentrations among the pretreatments. Conclusion: Alkaline pretreatment was essential for obtaining high concentrations of glucose and xylose. The application of an alkaline pretreatment alone resulted in high glucose and xylose concentrations. This result is very significant as it allows a cost reduction by eliminating one step.

The optimization of biohydrogen production by bacteria using residual glycerol from biodiesel synthesis.

In this research the production of hydrogen by Klebsiella pneumoniae BLb01 using residual glycerol discharged from a biodiesel fuel production plant was investigated. Klebsiella pneumoniae BLb01 was isolated from a bacteria-rich sludge of an upflow anaerobic sludge blanket reactor (UASB) of a soybean processing plant. A Plackett-Burman design (P-B) and Response Surface Methodology (RSM) were employed to determine the optimal condition for enhanced hydrogen production. The maximal hydrogen production, which was 45.0 mol % and with 98% of glycerol degradation, was achieved with the optimized medium with the following composition: 30 g L(-1) glycerol; 3 g L(-1) yeast ex tract 3 g L(-1) K(2)HPO(4); 1 g L(-1) KH(2)PO(4); temperature 39°C and pH 9.0. These results show the ability of this new strain of effectively converting residual glycerol into value-added energy products.

ESIPT-exhibiting protein probes: a sensitive method for rice proteins detection during starch extraction.

The 2-(4'-isothiocyanate-2'-hydroxyphenyl)benzoxazole dye was successfully applied as label of rice proteins during the alkaline extraction of starch. Direct fluorescence measurements were used to observe the presence of proteins labelled in different steps of rice starch extraction. The results were compared to those obtained with the well-known biuret colorimetric test. Whereas the colorimetric test indicates the absence of protein after the third extraction step, the fluorescence emission of the conjugate could be observed in all extraction steps. The separation of different rice proteins could also be observed.

Preliminary characterization of anhydrous ethanol used in Brazil as automotive fuel.

This work reports preliminary studies on the characterisation of anhydrous ethanol (AEA) used as an automotive fuel mixed with gasoline in Porto Alegre (South Brazil). Pre-concentration of the impurities contained in 1000 ml of AEA was carried on through solid-phase extraction using XAD4 resin. The main compounds in the extract were identified by means of spectral data from the library of the equipment. The concentrate was then fractionated using a preparative liquid chromatographic column filled with activated silica gel and the elution procedure was carried out with, n-hexane, n-hexane-benzene (1:1, v/v) and dichloromethane. Prior to analysis by GC-MS, each fraction was reduced to 1 ml with a gentle stream of nitrogen. Saturated linear hydrocarbons and aromatic hydrocarbons eluted in the first fraction and oxygenated compounds such as aldehydes. ketones and alcohols, eluted in the second one. were the main compounds detected in the sample.