Development of new methodologies based on ICP techniques for the elemental and isotopic analysis of bioethanol and related samples

• Autores: Carlos Sánchez Rodríguez
• Directores de la Tesis: Jose Luis Todolí Torró (dir. tes.), Charles Philippe Lienemann (codir. tes.)
• Lectura: En la Universitat d'Alacant / Universidad de Alicante ( España ) en 2018
• Idioma: inglés
• Tribunal Calificador de la Tesis: Vicente Hernandis Martínez (presid.), Martín Resano Ezcaray (secret.), Nathalie Schildknecht-Szydlowski (voc.)
• Programa de doctorado: Programa de Doctorado en Ciencias Experimentales y Biosanitarias por la Universidad de Alicante
• Materias:
  • Química
    • Química analítica
• Enlaces
  • Tesis en acceso abierto en: RUA
• Resumen

  • Bioethanol corresponds to ethanol obtained through microorganism-based fermentation of sugars extracted from diverse sources. This product is mainly used as a fuel and it is considered as a renewable energy source. There are two generations of bioethanol, depending on the type of raw material: First-generation bioethanol is obtained from foods such as cereals, beet and sugar cane that contain high concentrations of easily extractable sugars. Although the industrial process used for producing first-generation bioethanol is efficient, both economically and energetically, fuel-food competition phenomenon has been claimed to be a drawback of this product. The second-generation bioethanol (also called lignocellulosic bioethanol), produced using biomass corresponding to non-edible food crop production, appears to overcome the fuel-food competition problem. However, its synthesis involves previous chemical and/or enzymatic hydrolysis steps in order to transform complex sugars into mono and disaccharides. There also exists a third generation of biofuels, based on the use of algae as raw material. However, this is still an emerging technology that has not been industrially implemented yet.

    Bioethanol can be used in its pure form within modified spark-ignition (Flex-Fuel) engines or blended with petroleum distillates at different ratios. Indeed, it acts as an efficient octane-boosting agent, thereby replacing chemical additives such as methyl tert-butyl ether (MTBE). It should be noted that current non-modified engines are compatible with up to E15 (gasoline containing 15% of ethanol).

    This biofuel is considered to be a good candidate to replace the fossil fuels because its combustion lowers the amount of greenhouse gas (GHG) emissions. In the case of first-generation bioethanol, the emission of GHG can be reduced up to a 66% as compared to fossil fuels. Therefore, bioethanol would mitigate some environmental and health problems that can be related with the widespread use of petroleum derivates. These reasons, combined with the fact that, according to some studies, petroleum stocks will be depleted in about 50 years, have led to a significant growing of the bioethanol use and production during the last decades. As a result, the number of studies focused on the development of new production processes, using new raw materials and/or new microorganisms, have also increased considerably.

    Obviously, the growing demand for bioethanol and emerging production technologies should be linked to the development and implementation of new analytical methods to control the quality of these biofuels. However, the official methods of bioethanol analysis incorporated in the current European legislation are limited to some global parameters (e.g., water content, pH, total acidity or conductivity). It is interesting to mention that bioethanol may contain additional organic as well as inorganic compounds, leading to a deterioration of its quality. Regarding organic pollutants, volatile organic compounds (VOCs) should be monitored, among others, due to the negative impact caused by their emission into the atmosphere. Among the inorganic pollutants, metals and metalloids are of particular interest because some of them cause environmental pollution and risks to the human health, even at very low concentrations (levels below ng mL-1). Moreover, some metals and metalloids may cause engine damages.

    Additionally, isotopic analysis of bioethanol could provide valuable information about the kind and the provenance of the raw materials used for its production. It should be noted that studies related with isotope ratios determination in bioethanol have not been reported to date.