Antonia Pérez de los Ríos

The effect of ionic liquid media on activity, selectivity and stability of Candida antarctica lipase B in transesterification reactions

Nineteen different 1,3-dialkylimidazolium-based ionic liquids (ILs) were used as reaction media for the synthesis of butyl butyrate by transesterification from vinyl butyrate and 1-butanol catalyzed by Candida antarctica lipase B (CaLB). The reaction was also carried out in hexane as a reference solvent. In all the water-immiscible ILs assayed, the enzymatic activity and selectivity were higher than that obtained in hexane. However, in water-miscible ILs, the activity was lower than in the reference solvent, although they showed >99.99% selectivity. Two solvent properties, hydrophobicity and nucleophilicity, were considered key parameters for analyzing the behavior of CaLB in ILs. In the case of ILs based on the same anion, the synthetic activity was gradually enhanced by increasing cation hydrophobicity. Furthermore, the activity of CaLB was greater in ILs containing anions of lower nucleophilicity. Stability studies indicate that CaLB exhibited greater stability in water-immiscible ILs than in water-miscible ILs.

NUEVOS PROCESOS DE SEPARACIÓN BASADOS EN MEMBRANAS LÍQUIDAS IÓNICAS SOPORTADAS

In this review an overview is given of recent advances in supported membranes based on ionic liquids. Novel processes based on supported liquid membranes have been proposed as effective methods for the selective separation of different chemical species in a wide variety of processes. However, the industrial use of supported liquid membranes based on organic solvents is limited by their relative instability and short lifetime. The use of ionic liquids as a liquid membrane phase could overcome these inconveniences due to their negligible vapour pressure, their greater viscosity and the possibility of minimizing their solubility in the surrounding phases by adequate selection of the cation and anion. The possibility of designing suitable ionic liquids for specific separation problems has also opened up new fields of application of supported ionic liquid membranes.

Organic–Inorganic Membranes Impregnated with Ionic Liquid

The use of ionic liquids (ILs) as fuel cell electrolytes is gaining growing interest. Their application as fuel cell membranes is fairly recent but much progress has been made in this field. Solid or semisolid conductive electrolytes are generally preferred over fluidic materials in these devices, and ILs have shown great potential to fabricate polymer membranes with good mechanical properties and high conductivity. Thus, they could replace conventional perfluorosulfonic acid membranes for operation at low and high temperatures. This chapter focuses on the recent advances in the application of ionic liquid-based polymer membranes for the development of fuel cell technology. Although special attention is paid to proton exchange membranes fuel cells (PEMFCs), other fuel cell types such as alkaline (AFCs) and microbial fuel cells (MFCs) are also covered. The membrane configurations comprised in this work include several ionic liquid–polymer membrane options such as supported and inclusion membranes, polymerizable ionic liquids and ionic liquid–polymer composites. The key factors affecting membrane performance in each case are discussed.

PILAS DE COMBUSTIBLE MIRCROBIANAS: UNA TECNOLOGÍA PROMETEDORA

ABSTRACT: Recent studies show that microbial fuel cells are a potential alternative to fossil fuels. Due to the current energy crisis, this technology has drawn increasing attention from the scientific community. Research efforts have been focused on improving the performance of these devices and reducing their cost, in order to make it possible the feasibility of MFC designs. Promising results have been achieved but much improvement is still needed. This work looks into the latest advances in the MFC field, covering materials, types of substrate, configuration and operating conditions, among other issues. Thanks to these new developments, which are key to understand MFC design and optimization, microbial fuel cells have become increasingly efficient systems. Keywords: microbial fuel cells, electrodes, separator, substrate, operation conditions, MFC models, ionic liquids.

Chapter 11 – Outlook

It was our intention in the 10 previous chapters to provide essential information for a deep understanding of the nature and properties of ionic liquids as well as review modern separation applications that have benefited from ionic liquid technology. Application of ionic liquids in chemical processes has blossomed within the past decade. Interest in these compounds is still increasing rapidly. If we look to the future, it is difficult to predict what will be discovered since science is unpredictable, which makes exciting our work as scientists. From this perspective, in this chapter we answer some questions that can summarize the advantages of using ionic liquids in separation technology and the progress and challenges in this field.

PILAS DE COMBUSTIBLE MICROBIANAS: FACTORES CLAVE PARA SU DISEÑO

RESUMEN: En los ultimos anos, las pilas de combustible microbianas se han convertido en el centro de estudio de numerosas investigaciones debido a la necesidad de encontrar fuentes de energia limpias y eficientes. Los resultados muestran que en un futuro estos sistemas podrian ser la alternativa perfecta a los combustibles fosiles ya que producen electricidad a partir de diferentes tipos de residuos, tales como aguas residuales urbanas, de la industria cervecera o del papel, lo que permite su aprovechamiento. El auge de las energias renovables y las numerosas ventajas que ofrece la tecnologia de pilas de combustible microbianas ha hecho que el estudio de estos sistemas adquiera una notable importancia en la ultima decada, recogiendose en la bibliografia cientifica numerosos estudios encaminados sobre todo a la reduccion de costes de sus componentes y al aumento de la eficacia de estos sistemas. Este trabajo recoge el estado del arte de la tecnologia de pilas de combustible microbianas, haciendo especial hincapie en aspectos tales como tipos de sustratos empleados, componentes de pilas de combustible microbianas (electrodos, membrana, etc.) y nuevas configuraciones Keywords: pilas de combustible microbiana, electrodo, separador, sustrato, condiciones de operacion, liquido ionico, nanomateriales

LA VAINA DEL ALGARROBO COMO NUEVA MATERIA PRIMA PARA LA PRODUCCIÓN DE BIOETANOL

Due to the progressive deplection of fossil energetic sources and the increase in greenhouse gas emissions, new research are focusing in biofuels development mainly these feedstocks which are not competitive with animal or human feeding. In this work, carob pod is suggested as a new feedstock for bioethanol production. A tecno-economic study and life cycle assessment of the production process have been done.