Name: determination of carbonyl functional groups in bio-oils by potentiometric titration: the faix method
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Este trabajo fue apoyado por el Departamento de Energía de Estados Unidos bajo el Contrato No. DE-AC36-08GO28308 con el Laboratorio Nacional de Energía Renovable. Financiación proporcionada por la Oficina US DOE de la eficiencia energética y la Oficina de bioenergía tecnologías de energía renovable. El Gobierno de Estados Unidos conserva y el editor, al aceptar el artículo para su publicación, reconoce que el gobierno de Estados Unidos mantiene una licencia no exclusiva, que se haya abonado, irrevocable, mundial de publicar o reproducir el formulario publicado de esta obra, o permitir que otros lo hagan, para los propósitos del gobierno de Estados Unidos.

Precaución: Por favor revise todas las hojas de datos de seguridad de materiales pertinentes (MSDS) antes de empezar. El etanol es inflamable. Todos los procedimientos de manipulación aplicables químicos deben seguirse, así como todos los procedimientos desechables y manejo de residuos aplicables. 1. Soluciones de reactivo <ol><li> Preparar la solución de clorhidrato de hidroxilamina (solución A): Añadir 7,7 g de hidrocloruro de hidroxilamina y 50 ml de agua desionizada a un matraz aforado de 250 ml. Cuando todos los sólidos se han disuelto, diluya hasta la marca con etanol. Esto resulta en una solución de clorhidrato de hidroxilamina 0,55 M en 80% (v / v) de etanol. </li><li> Preparar la solución de trietanolamina (Solución B): Añadir 17,4 ml de trietanolamina a un matraz aforado de 250 ml. Añadir 10 ml de agua, y luego se diluye hasta la marca con etanol. 95% de etanol también se puede utilizar si se omite la adición de agua. Esto resulta en una solución 0,48 M de trietanolamina en 96% (v / v) de etanol </li><li> Preparar el ácido clorhídricosolución. Cualquiera de comprar 0,1 N solución o preparar utilizando 10 ml de HCl concentrado y 1 L de agua. </li></ol> 2. Bio-aceite de toma de muestras y manipulación <ol><li> Asegúrese de que la muestra de aceite esté a temperatura ambiente antes de la extracción de una muestra. Homogeneizar bien (mezcla agitando vigorosamente durante al menos 1 minuto, y una inspección visual de la muestra para asegurar que esté homogéneo. Algunos aceites biológicos pueden requerir mayores tiempos de agitación) bio-aceite para obtener una muestra representativa. </li><li> Para la muestra bio-aceite, utilice 100 a 150 mg de bio-aceite. </li><li> Minimizar la exposición al oxígeno y calor para evitar la degradación de la muestra antes del análisis. </li></ol> 3. Procedimiento Analítico <ol><li> Normalización de la solución de base <ol><li> Dry Na 2 CO 3 patrón primario en un horno a 105 ° C durante la noche para asegurar una muestra seca. Deje que el Na 2 CO 3 se enfríe a temperatura ambiente antes de pesar. </li><li> Pesar 100 a 150 mgde carbonato de sodio a un vaso de valoración, registrar el peso real, agregar una barra de agitación y añadir agua suficiente para cubrir el bulbo del electrodo de pH y la unión. </li><li> Transferir la muestra a un recipiente de valoración, el lavado de los viales de reacción varias veces por separado con etanol y agua en proporciones para hacer una solución final 80% de etanol / agua. Valorar con la solución de ácido usando un titulador automático al punto final. Registre el punto final. El punto final se define como el punto de inflexión en la curva de titulación. </li><li> Repita el proceso dos veces para obtener tres puntos. </li><li> Utilice el valor medio como la normalidad de la solución de ácido. </li></ol></li><li> Preparación de los espacios en blanco de valoración <ol><li> Para un blanco: añadir 0,5 ml de sulfóxido de dimetilo (DMSO) a un vial de 5 ml con una paleta de giro. </li><li> Añadir 2 ml de solución de clorhidrato de hidroxilamina (solución A). </li><li> Añadir 2 ml de solución de trietanolamina (solución B). </li><li> Tapa con fuerza, en lugar precalentado (80 ° C) de calorer bloque o baño de agua y se agita durante 2 horas. </li><li> Valorar con una solución de ácido usando un titulador automático al punto final, y el registro de punto final. </li><li> Para Blank B: Si el ácido mineral se sospecha que es presente en la muestra, añadir 0,5 ml de DMSO a 5 ml vial con una paleta de giro. </li><li> Añadir 2 ml de solución de trietanolamina (solución B). </li><li> Su tapa y agitar a 80 ° C durante 2 horas. </li><li> Transferir la muestra a un recipiente de valoración, el lavado de los viales de reacción varias veces por separado con etanol y agua en proporciones para hacer una solución final 80% de etanol / agua. Valorar con la solución de ácido usando un titulador automático al punto final. Registre el punto final. </li><li> Repita el proceso tres veces para obtener tres puntos. </li></ol></li><li> Validación del método que utiliza un carbonilo Conocido <ol><li> Pesar ~ 100 mg de 4- (benciloxi) benzaldehído (4-BBA) a un vial de 5 ml, registrar el peso real, añadir una paleta de centrifugado. </li><li> Añadir 0,5 ml de DMSO. </li><li> Disolverla muestra en 2 ml de solución de clorhidrato de hidroxilamina (solución A). </li><li> Añadir 2 ml de solución de trietanolamina (solución B). </li><li> Cerrar herméticamente la tapa y se agita a 80 ° C durante 2 horas. </li><li> Transferir la muestra a un recipiente de valoración, el lavado de los viales de reacción varias veces por separado con etanol y agua en proporciones para hacer una solución final 80% de etanol / agua. Valorar con la solución de ácido usando un titulador automático al punto final. Registre el punto final. </li><li> Repetir el proceso tres veces, para obtener tres puntos. </li></ol></li><li> Análisis de Bio-aceite Uso del método <ol><li> Se pesa cerca de 100 mg de la bio-aceite al vial de 5 ml, registrar el peso real y añadir una paleta de centrifugado. </li><li> Añadir 0,5 ml de DMSO. </li><li> Disolver la muestra en 2 ml de solución de clorhidrato de hidroxilamina (solución A). </li><li> Añadir 2 ml de solución de trietanolamina (solución B). </li><li> Cerrar herméticamente la tapa y se agita a 80 ° C durante 2 horas. </li><li> º de transferenciae muestra a un recipiente de valoración, el lavado de los viales de reacción varias veces por separado con etanol y agua en proporciones para obtener una solución final de 80% de etanol / agua. Valorar con la solución de ácido usando un titulador automático al punto final. Registre el punto final. </li><li> Repetir el proceso tres veces, para obtener tres puntos. </li><li> En Blanco C: Si el ácido mineral se sospecha la presencia en la muestra, pesan cerca de 100 mg de la bio-aceite en un vial de 5 ml, se registra el peso y añadir una paleta de centrifugado. </li><li> Añadir 0,5 ml de DMSO. </li><li> Añadir 2 ml de solución de trietanolamina (solución B). </li><li> Su tapa y agitar a 80 ° C durante 2 horas. </li><li> Transferir la muestra a un recipiente de valoración, el lavado de los viales de reacción varias veces por separado con etanol y agua en proporciones para hacer una solución final 80% de etanol / agua. Valorar con la solución de ácido usando un titulador automático al punto final. Registre el punto final. </li><li> Repita el proceso tres veces para obtener tres puntos. </li></ol></li></ol> 4. Cálculos <ol><li> Normalización de la solución de base <ol><li> Calcular la concentración de la solución de ácido (mol / L) mediante la siguiente ecuación. El peso del carbonato de sodio seco en gramos es w 1, la pureza se escribe como una fracción (es decir, 99% es 0,99), y el punto final se encuentra en mL. <img alt="Ecuación 1" src="/files/ftp_upload/55165/55165eq1.jpg" /></li></ol></li><li> Validación del método que utiliza un carbonilo Conocido <ol><li> Calcular la concentración de 4BBA (mol / L) en la muestra usando la siguiente ecuación. El peso de la 4BBA en gramos es W 2, la pureza 4BBA se escribe como una fracción (es decir, 99% es 0,99), la concentración de la solución de ácido (mol / L) es [ácido], el trietanolamina / hidroxilamina • HCl punto final en blanco es EP BA (el valor medio de tres espacios en blanco, en ml), y el punto final es EP (en ml). &lt;br /&gt; <img alt="Ecuación 2" src="/files/ftp_upload/55165/55165eq2.jpg" /></li></ol></li><li> Análisis de biopetroleo <ol><li> Calcular la concentración de carbonilos en aceites biológicos [CO] (mmol / g-bio petróleo) utilizando la siguiente ecuación. El peso de la bio-aceite en gramos es w 3, la concentración de la solución de ácido (mol / L) es [ácido], el trietanolamina / hidroxilamina • punto final en blanco HCl es EP BA (el valor medio de tres espacios en blanco en ml) y el punto final es un EP (en mL). <img alt="Ecuación 3" src="/files/ftp_upload/55165/55165eq3.jpg" /></li></ol></li><li> corrección de ácido NOTA: La presencia de ácidos minerales o ácidos orgánicos con pKa &lt;2 puede causar valores artificialmente bajos carbonilo debido a la reacción del ácido con trietanolamina. <ol><li> Si esto se sospecha, realice los espacios en blanco que se detallan en las secciones 3.2.6 y 3.4.8. El peso de la bio-aceite en la muestra en gramos esw 3, EP es el punto final de la muestra y EP BA es la trietanolamina / blanco hidroxilamina. EP BB es el punto final de Blank B, EP BC es punto final de C en blanco y el peso (g) de aceite usado en C en blanco se w BC: <img alt="Ecuación 4" src="/files/ftp_upload/55165/55165eq4.jpg" /> Para muestras bio-petróleo que contienen principalmente ácido acético, este es un paso innecesario. </li></ol></li></ol>

<ol>
	<li>Oasmaa, A., Kuoppala, E., Solantausta, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fast+pyrolysis+of+forestry+residue.+2.+physicochemical+composition+of+product+liquid.">Fast pyrolysis of forestry residue. 2. physicochemical composition of product liquid.</a> Energy Fuels. 17 (2), 433-443 (2003).</li><li>Olarte, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stabilization+of+Softwood-Derived+Pyrolysis+Oils+for+Continuous+Bio-oil+Hydroprocessing.">Stabilization of Softwood-Derived Pyrolysis Oils for Continuous Bio-oil Hydroprocessing.</a> Top. Catal. 59 (1), 55-64 (2016).</li><li>Nicolaides, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> The chemical characterization of pyrolytic oils. , (1984).</li><li>Oasmaa, A., Korhonen, J., Kuoppala, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+approach+for+stability+measurement+of+wood-based+fast+pyrolysis+bio-oils.">An approach for stability measurement of wood-based fast pyrolysis bio-oils.</a> Energy Fuels. 25 (7), 3307-3313 (2011).</li><li>Chen, C. L., Lin, S. Y., Dence, C. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Methods in Lignin Chemistry. , 446-457 (1992).</li><li>Scholze, B., Hanser, C., Meier, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+the+water-insoluble+fraction+from+fast+pyrolysis+liquids+(pyrolytic+lignin)+Part+II.+GPC,+carbonyl+groups,+and+13C-NMR.">Characterization of the water-insoluble fraction from fast pyrolysis liquids (pyrolytic lignin) Part II. GPC, carbonyl groups, and 13C-NMR.</a> J. Anal. Appl. Pyrolysis. 58-59, 387-400 (2001).</li><li>Bayerbach, R., Meier, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+the+water-insoluble+fraction+from+fast+pyrolysis+liquids+(pyrolytic+lignin).+Part+IV:+Structure+elucidation+of+oligomeric+molecules.">Characterization of the water-insoluble fraction from fast pyrolysis liquids (pyrolytic lignin). Part IV: Structure elucidation of oligomeric molecules.</a> J. Anal. Appl. Pyrolysis. 85 (1-2), 98-107 (2009).</li><li>Faix, O., Andersons, B., Zakis, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Determination+of+Carbonyl+Groups+of+Six+Round+Robin+Lignins.">Determination of Carbonyl Groups of Six Round Robin Lignins.</a> Holzforschung. 52, 268-272 (1998).</li><li>Black, S., Ferrell, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Determination+of+Carbonyl+Groups+in+Pyrolysis+Bio-oils+Using+Potentiometric+Titration:+Review+and+Comparison+of+Methods.">Determination of Carbonyl Groups in Pyrolysis Bio-oils Using Potentiometric Titration: Review and Comparison of Methods.</a> Energy Fuels. 30 (2), 1071-1077 (2016).</li><li>Ferrell, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Standardization+of+Chemical+Analytical+Techniques+for+Pyrolysis+Bio-oil:+History,+Challenges,+and+Current+Status+of+Methods.">Standardization of Chemical Analytical Techniques for Pyrolysis Bio-oil: History, Challenges, and Current Status of Methods.</a> Biofuels, Bioprod. Biorefin. 10, 496-507 (2016).</li></ol>

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Curvas de valoración representativos se muestran en la Figura 2. Una valoración testigo, así como una valoración de una muestra de aceite de pirólisis, se muestran. Además, se muestra la primera derivada de la curva de valoración (DPH / dV), que permite un fácil reconocimiento del punto final de la titulación. La tabla de inserción en la Figura 2 muestra los datos por triplicado tanto para el aceite de pirólisis y titulaciones en blanco, con valores medios y las desviaciones ...

Mientras pirólisis bio-aceites se componen de una gran variedad de compuestos y grupos funcionales químicos, la cuantificación de los grupos carbonilo es especialmente importante. Carbonilos son conocidos por ser responsable de la inestabilidad de bio-aceite durante el almacenamiento tanto 1 y 2 de procesamiento. El método de valoración que se presenta aquí es una técnica sencilla que se puede cuantificar de manera fiable el contenido total en carbonilo de bio-aceites. Sólo los grupos funcionales aldehído y cetona se cuantifican utilizando este método; grupos de ácidos carboxílicos y lactonas no se cuantifican. Para el análisis de bio-aceites, la cuantificación de grupos carbonilo por titulación tradicionalmente se ha logrado mediante el método de Nicolaides 3. Este método se ha usado comúnmente en la literatura bio-aceite 4, 5, 6, 7. Esto es unsencillo procedimiento en el que los carbonilos se convierten en la oxima correspondiente (véase la Figura 1). El HCl liberado reacciona con piridina para forzar el equilibrio hacia la terminación. El ácido conjugado de piridina se valora con una cantidad conocida de NaOH (reactivo de valoración base). El número de equivalentes de NaOH utilizadas es estequiométricamente equivalente a los moles de carbonilo presente en el bio-aceite. El método Nicolaides, sin embargo, tiene varias limitaciones. Se puede requerir tiempos de reacción más de 48 horas para llegar a su finalización. Esto limita seriamente el flujo de muestras. Se utiliza piridina, que es tóxico. se requieren pesos de muestra de 1 a 2 g. Peso de la muestra utilizada depende de la cantidad de hidroxilamina HCl presente y el contenido de carbonilo de la muestra. Si las estimaciones iniciales del peso de la muestra utilizada son incorrectos, la valoración tiene que ser repetido. Faix et al. 8 desarrollaron un método que ha sido modificado hERE para hacer frente a los problemas del método Nicolaides. La reacción se lleva a cabo a 80 ° C durante 2 horas, lo que aumenta el flujo de muestras. La piridina se ha sustituido con trietanolamina, que es una sustancia menos tóxica. El tamaño de la muestra se puede reducir a 100 a 150 mg. La trietanolamina consume el HCl liberado, conducir la reacción hasta su finalización y la trietanolamina no consumido se valora directamente. Una valoración secundaria de la hidroxilamina es innecesario. La comparación de estos métodos de valoración ha demostrado que el método Nicolaides subestima significativamente el contenido de carbonilo de bio-aceites 9. El método descrito aquí se ha modificado desde el método original 8 a ser más aplicable al análisis de pirólisis bio-aceites. Este método fue desarrollado para el análisis de pirólisis prima aceites biológicos, pero se ha aplicado con éxito a otros tipos de aceites derivados de la biomasa, incluyendo los bio-aceites hidrotratados. Addinalmente, este método se ha utilizado para monitorear los cambios en el contenido de carbonilo durante tanto el envejecimiento como la actualización.

<table><tbody><tr><td>Analytical balance</td><td></td><td></td><td>accurate to 0.1 mg</td></tr><tr><td>dry block heater with magnetic stirrer, or hot water bath with magnetic stirrer</td><td></td><td></td><td></td></tr><tr><td>Automatic titrator</td><td></td><td></td><td>We used a Metrohm Titrando 809 automatic titrator, though other equivalent systems are acceptable</td></tr><tr><td>Deionized water</td><td></td><td></td><td></td></tr><tr><td>Ethanol (reagent grade)</td><td></td><td></td><td>CAS # 64-17-5</td></tr><tr><td>Hydroxylamine hydrochloride&amp;nbsp;</td><td></td><td></td><td>CAS # 5470-11-1</td></tr><tr><td>Triethanolamine&amp;nbsp;</td><td></td><td></td><td>CAS #102-71-6</td></tr><tr><td>Hydrochloric acid (37%)&amp;nbsp;</td><td></td><td></td><td>CAS # 7647-01-0</td></tr><tr><td>Sodium Carbonate (primary standard)&amp;nbsp;</td><td>SigmaAldrich</td><td>223484</td><td></td></tr><tr><td>4-(benzyloxy)benzaldehyde&amp;nbsp;</td><td></td><td></td><td>CAS # 4397-53-9</td></tr><tr><td>Dimethyl sulfoxide</td><td></td><td></td><td>CAS # 67-68-5</td></tr><tr><td>5 mL glass Reacti-vials with solid lid and teflon spinvane</td><td>Thermoscientific</td><td>TS-13223</td><td></td></tr><tr><td>200 mL volumetric flask</td><td></td><td></td><td></td></tr><tr><td>Volumetric or mechanical pipettes</td><td></td><td></td><td></td></tr></tbody></table>

determination of carbonyl functional groups in bio-oils by potentiometric titration: the faix method

Los compuestos de carbonilo presentes en aceites biológicos son conocidos por ser responsable de los cambios de propiedades bio-petróleo durante el almacenamiento y durante la actualización. En concreto, carbonilos provocan un aumento de la viscosidad (a menudo referido como &quot;envejecimiento&quot;) durante el almacenamiento de aceites biológicos. Como tal, el contenido de carbonilo ha sido previamente utilizado como un método de seguimiento de envejecimiento bio-aceite y reacciones de condensación con menos variabilidad que las medidas de viscosidad. Además, los carbonilos son también responsables de la formación de coque en los procesos de mejora de bio-aceite. Dada la importancia de carbonilos en aceites biológicos, métodos analíticos precisos para su cuantificación son muy importantes para la comunidad de bio-aceite. métodos de valoración potenciométrica sobre la base de oximación carbonilo han sido utilizados para la determinación del contenido en carbonilo en la pirólisis bio-aceites. A continuación, presentamos una modificación de los procedimientos tradicionales de oximación carbonilo que se traduce en menos tiempo de reacción, muestra de menor tamaño, mayor precisión y más acccarbonilo determinaciones de ácido úrico. Si bien los métodos de oximación carbonilo tradicional se producen a temperatura ambiente, el método presentado aquí Faix se produce a una temperatura elevada de 80 ° C.

<html> Una curva de valoración típica consiste en un único punto final, como se muestra en la Figura 2. titulaciones típicos tanto para una muestra bio-aceite crudo, y una prueba en blanco, se muestran. A medida que el punto final se encuentra en el punto de inflexión en la curva de valoración; el punto final se puede identificar fácilmente mediante el trazado de la primera derivada de la curva de valoración (que se muestra en el eje derecho, dpH / dV, en la <stro...

Watch this Scientific Journal Video about Determination of Carbonyl Functional Groups in Bio-oils by Potentiometric Titration: The Faix Method at JoVE.com

Determination of Carbonyl Functional Groups in Bio-oils by Potentiometric Titration: The Faix Method

Here we present a potentiometric titration technique for accurately quantifying carbonyl compounds in pyrolysis bio-oils.

Determinación de carbonilo grupos funcionales en aceites biológicos mediante valoración potenciométrica: El Método Faix

Carbonyl compounds present in bio-oils are known to be responsible for bio-oil property changes upon storage and during upgrading. Specifically, carbonyls ...

determination-carbonyl-functional-groups-bio-oils-potentiometric

Universidad de Cartagena UDEC

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Organic Chemistry

Analytical Chemistry

Chemistry

Unit 1

Aldehydes and Ketones

Complexometric Titration, Precipitation Titration, and Gravimetry

SCIENTISTS IN ACTION

11.0K vistas.  National Renewable Energy Laboratory. Here we present a potentiometric titration technique for accurately quantifying carbonyl compounds in pyrolysis bio-oils.

Video: Determination of Carbonyl Functional Groups in Bio-oils by Potentiometric Titration: The Faix Method

Identification of Fatty Acids in Bacillus cereus

The Bacillus species contain branched chain and unsaturated fatty acids (FAs) with diverse positions of the methyl branch (iso or anteiso) and of the double bond. Changes in FA composition play a crucial role in the adaptation of bacteria to their environment. These modifications entail a change in the ratio of iso versus anteiso branched FAs, and in the proportion of unsaturated FAs relative to saturated FAs, with double bonds created at specific positions. Precise identification of the FA profile is necessary to understand the adaptation mechanisms of Bacillus species.
Many of the FAs from Bacillus are not commercially available. The strategy proposed herein identifies FAs by combining information on the retention time (by calculation of the equivalent chain length (ECL)) with the mass spectra of three types of FA derivatives: fatty acid methyl esters (FAMEs), 4,4-dimethyl oxazoline derivatives (DMOX), and 3-pyridylcarbinyl ester (picolinyl). This method can identify the FAs without the need to purify the unknown FAs.
Comparing chromatographic profiles of FAME prepared from Bacillus cereus with a commercial mixture of standards allows for the identification of straight-chain saturated FAs, the calculation of the ECL, and hypotheses on the identity of the other FAs. FAMEs of branched saturated FAs, iso or anteiso, display a constant negative shift in the ECL, compared to linear saturated FAs with the same number of carbons. FAMEs of unsaturated FAs can be detected by the mass of their molecular ions, and result in a positive shift in the ECL compared to the corresponding saturated FAs.
The branching position of FAs and the double bond position of unsaturated FAs can be identified by the electron ionization mass spectra of picolinyl and DMOX derivatives, respectively. This approach identifies all the unknown saturated branched FAs, unsaturated straight-chain FAs and unsaturated branched FAs from the B. cereus extract.

Identification of Fatty Acids in Bacillus cereus

We propose a protocol to identify fatty acids without the need to purify them. It combines information on the retention times with the mass spectra of three types of fatty acid derivatives: fatty acid methyl esters (FAMEs), 4,4-dimethyl oxazoline derivatives (DMOX), and 3-pyridylcarbinyl esters (picolinyl).

Identificación de los ácidos grasos en la<em&gt; Bacillus cereus</em

The Bacillus species contain branched chain and unsaturated fatty acids (FAs) with diverse positions of the methyl branch (iso or anteiso) and of the ...

Investigación

Bioquímica

A Toolkit to Enable Hydrocarbon Conversion in Aqueous Environments

This work puts forward a toolkit that enables the conversion of alkanes by Escherichia coli and presents a proof of principle of its applicability. The toolkit consists of multiple standard interchangeable parts (BioBricks)9 addressing the conversion of alkanes, regulation of gene expression and survival in toxic hydrocarbon-rich environments.
A three-step pathway for alkane degradation was implemented in E. coli to enable the conversion of medium- and long-chain alkanes to their respective alkanols, alkanals and ultimately alkanoic-acids. The latter were metabolized via the native &beta;-oxidation pathway. To facilitate the oxidation of medium-chain alkanes (C5-C13) and cycloalkanes (C5-C8), four genes (alkB2, rubA3, rubA4and rubB) of the alkane hydroxylase system from Gordonia sp. TF68,21 were transformed into E. coli. For the conversion of long-chain alkanes (C15-C36), theladA gene from Geobacillus thermodenitrificans was implemented. For the required further steps of the degradation process, ADH and ALDH (originating from G. thermodenitrificans) were introduced10,11. The activity was measured by resting cell assays. For each oxidative step, enzyme activity was observed.
To optimize the process efficiency, the expression was only induced under low glucose conditions: a substrate-regulated promoter, pCaiF, was used. pCaiF is present in E. coli K12 and regulates the expression of the genes involved in the degradation of non-glucose carbon sources.
The last part of the toolkit - targeting survival - was implemented using solvent tolerance genes, PhPFD&alpha; and &beta;, both from Pyrococcus horikoshii OT3. Organic solvents can induce cell stress and decreased survivability by negatively affecting protein folding. As chaperones, PhPFD&alpha; and &beta; improve the protein folding process e.g. under the presence of alkanes. The expression of these genes led to an improved hydrocarbon tolerance shown by an increased growth rate (up to 50%) in the presences of 10% n-hexane in the culture medium were observed.
Summarizing, the results indicate that the toolkit enables E. coli to convert and tolerate hydrocarbons in aqueous environments. As such, it represents an initial step towards a sustainable solution for oil-remediation using a synthetic biology approach.

A sustainable auto regulating bacterial system for the remediation of oil pollutions was designed using standard interchangeable DNA parts (BioBricks). An engineered E. coli strain was used to degrade alkanes via &beta;-oxidation in toxic aqueous environments. The respective enzymes from different species showed alkane degradation activity. Additionally, an increased tolerance to n-hexane was achieved by introducing genes from alkane-tolerant bacteria.

Un juego de herramientas para la conversión de hidrocarburos en ambientes acuosos

This work puts forward a toolkit that enables the conversion of alkanes by Escherichia coli and presents a proof of principle of its applicability. The ...

Bioingeniería

Analyzing the Photo-oxidation of 2-propanol at Indoor Air Level Concentrations Using Field Asymmetric Ion Mobility Spectrometry

We demonstrate a versatile protocol to be used for determining the effectiveness of photocatalysts in degrading indoor air concentration (ppb) volatile organic carbons (VOCs), illustrating this with a titanium dioxide based catalyst, and the VOC 2-propanol. The protocol takes advantage of field asymmetric ion mobility spectroscopy (FAIMS), an analysis tool that is capable of continuously identifying and monitoring the concentration of VOCs such as 2-propanol and acetone at the ppb level. The continuous nature of FAIMS allows detailed kinetic analysis, and long-term reactions, offering a significant advantage over gas chromatography, a batch process traditionally used in air purification characterization. The use of FAIMS in photocatalytic air purification has only recently been used for the first time, and with the protocol illustrated here, the flexibility in allowing alternative VOCs and photocatalysts to be tested using comparable protocols offers a unique system to elucidate photocatalytic air purification reactions at low concentrations.

A protocol for determining the effectiveness of photocatalysts in degrading indoor air concentration (ppb) model volatile organic carbons such as 2-propanol is described.

Análisis de la foto-oxidación del 2-propanol en el aire interior utilizando espectrometría de movilidad de iones asimétricos de campo nivel de concentración

We demonstrate a versatile protocol to be used for determining the effectiveness of photocatalysts in degrading indoor air concentration (ppb) volatile ...

Química

Original Experimental Approach for Assessing Transport Fuel Stability

The study of fuel oxidation stability is an important issue for the development of future fuels. Diesel and kerosene fuel systems have undergone several technological changes to fulfill environmental and economic requirements. These developments have resulted in increasingly severe operating conditions whose suitability for conventional and alternative fuels needs to be addressed. For example, fatty acid methyl esters (FAMEs) introduced as biodiesel are more prone to oxidation and may lead to deposit formation. Although several methods exist to evaluate fuel stability (induction period, peroxides, acids, and insolubles), no technique allows one to monitor the real-time oxidation mechanism and to measure the formation of oxidation intermediates that may lead to deposit formation. In this article, we developed an advanced oxidation procedure (AOP) based on two existing reactors. This procedure allows the simulation of different oxidation conditions and the monitoring of the oxidation progress by the means of macroscopic parameters, such as total acid number (TAN) and advanced analytical methods like gas chromatography coupled to mass spectrometry (GC-MS) and Fourier Transform Infrared - Attenuated Total Reflection (FTIR-ATR). We successfully applied AOP to gain an in-depth understanding of the oxidation kinetics of a model molecule (methyl oleate) and commercial diesel and biodiesel fuels. These developments represent a key strategy for fuel quality monitoring during logistics and on-board utilization.

Oxidation stability of transport fuels has become a concern for future fuel development. This work presents an original methodology developed by IFP Energies Nouvelles for assessing fuel stability using two different reactors. This methodology was successfully applied to gain an in-depth understanding of the oxidation kinetics and pathways of model molecules and commercial fuels.

Enfoque experimental original para evaluar el transporte de combustible Estabilidad

The study of fuel oxidation stability is an important issue for the development of future fuels. Diesel and kerosene fuel systems have undergone several ...

Using Capillary Electrophoresis to Quantify Organic Acids from Plant Tissue: A Test Case Examining Coffea arabica Seeds

Carboxylic acids are organic acids containing one or more terminal carboxyl (COOH) functional groups. Short chain carboxylic acids (SCCAs; carboxylic acids containing three to six carbons), such as malate and citrate, are critical to the proper functioning of many biological systems, where they function in cellular respiration and can serve as indicators of cell health. In foods, organic acid content can have significant impact on taste, with increased SCCA levels resulting in a sour or &#34;acid&#34; taste. Because of this, methods for the rapid analysis of organic acid levels are of particular interest to the food and beverage industries. Unfortunately, however, most methods used for SCCA quantification are dependent on time-consuming protocols requiring the derivatization of samples with hazardous reagents, followed by costly chromatographic and/or mass spectrometric analyses. This method details an alternate method for the detection and quantification of organic acids from plant material and food samples using free zonal capillary electrophoresis (CZE), sometimes simply referred to as capillary electrophoresis (CE). CZE provides a cost-effective method for measuring SCCAs with a low limit of detection (0.005 mg/ml). This article details the extraction and quantification of SCCAs from plant samples. While the method provided focuses on measurement of SCCAs from coffee beans, the method provided can be applied to multiple plant-based food materials.

Using Capillary Electrophoresis to Quantify Organic Acids from Plant Tissue: A Test Case Examining Coffea arabica Seeds

This article presents a method for the detection and quantification of organic acids from plant material using free zonal capillary electrophoresis. An example of the potential application of this method, determining the effects of a secondary fermentation on organic acid levels in coffee seeds, is provided.

Utilizando electroforesis capilar para cuantificar ácidos orgánicos a partir de Tejidos Vegetales: Un caso de prueba del examen<em&gt; Coffea arabica</em&gt; Semillas

Carboxylic acids are organic acids containing one or more terminal carboxyl (COOH) functional groups. Short chain carboxylic acids (SCCAs; carboxylic ...

Extraction of Lignin with High &#946;-O-4 Content by Mild Ethanol Extraction and Its Effect on the Depolymerization Yield

Lignin valorization strategies are a key factor for achieving more economically competitive biorefineries based on lignocellulosic biomass. Most of the emerging elegant procedures to obtain specific aromatic products rely on the lignin substrate having a high content of the readily cleavable &#946;-O-4 linkage as present in the native lignin structure. This provides a miss-match with typical technical lignins that are highly degraded and therefore are low in &#946;-O-4 linkages. Therefore, the extraction yields, and the quality of the obtained lignin are of utmost importance to access new lignin valorization pathways. In this manuscript, a simple protocol is presented to obtain lignins with high &#946;-O-4 content by relatively mild ethanol extraction that can be applied to different lignocellulose sources. Furthermore, analysis procedures to determine the quality of the lignins are presented together with a depolymerization protocol that yields specific phenolic 2-arylmethyl-1,3-dioxolanes, which can be used to evaluate the obtained lignins. The presented results demonstrate the link between lignin quality and potential for the lignins to be depolymerized into specific monomeric aromatic chemicals. Overall, the extraction and depolymerization demonstrates a trade-off between the lignin extraction yield and the retention of the native aryl-ether structure and thus the potential of the lignin to be used as the substrate for the production of chemicals for higher-value applications.

Here, we present a protocol to perform ethanol extraction of lignin from several biomass sources. The effect of the extraction conditions on the lignin yield and &#946;-O-4 content are presented. Selective depolymerization is performed on the obtained lignins to obtain high aromatic monomer products.

Extracción de la lignina con alto contenido de β-O-4 por la extracción de etanol suave y su efecto sobre el rendimiento de despolimerización

Lignin valorization strategies are a key factor for achieving more economically competitive biorefineries based on lignocellulosic biomass. Most of the ...

Characterizing Lewis Pairs Using Titration Coupled with In Situ Infrared Spectroscopy

Lewis acid-activation of carbonyl-containing substrates is a fundamental basis for facilitating transformations in organic chemistry. Historically, characterization of these interactions has been limited to models equivalent to stoichiometric reactions. Here, we report a method utilizing in situ infrared spectroscopy to probe the solution interactions between Lewis acids and carbonyls under synthetically relevant conditions. Using this method, we were able to identify 1:1 complexation between GaCl3 and acetone and a highly ligated complex for FeCl3 and acetone. The impact of this technique on mechanistic understanding is illustrated by application to the mechanism of Lewis acid-mediated carbonyl-olefin metathesis in which we were able to observe competitive binding interactions between substrate carbonyl and product carbonyl with the catalyst.

Here, we present a method for the observation of solution interactions between Lewis acids and bases by employing in situ infrared spectroscopy as a detector for titration under synthetically relevant conditions. By examining solution interactions, this method represents a complement to X-ray crystallography, and provides an alternative to NMR spectroscopy.

Caracterización de pares Lewis usando valoración junto con espectroscopia infrarroja in situ

Lewis acid-activation of carbonyl-containing substrates is a fundamental basis for facilitating transformations in organic chemistry. Historically, ...

Fast Pyrolysis of Biomass Residues in a Twin-screw Mixing Reactor

Fast pyrolysis is being increasingly applied in commercial plants worldwide. They run exclusively on woody biomass, which has favorable properties for conversion with fast pyrolysis. In order to increase the synergies of food production and the energetic and/or material use of biomass, it is desirable to utilize residues from agricultural production, e.g., straw. The presented method is suitable for converting such a material on an industrial scale. The main features are presented and an example of mass balances from the conversion of several biomass residues is given. After conversion, fractionated condensation is applied in order to retrieve two condensates &#8212; an organic-rich and an aqueous-rich one. This design prevents the production of fast pyrolysis bio-oil that exhibits phase separation. A two phase bio-oil is to be expected because of the typically high ash content of straw biomass, which promotes the production of water of reaction during conversion.
Both fractionated condensation and the use of biomass with high ash content demand a careful approach for establishing balances. Not all kind of balances are both meaningful and comparable to other results from the literature. Different balancing methods are presented, and the information that can be derived from them is discussed.

A procedure for thermochemical conversion of biomass residues is presented that aims at maximizing the yield of liquid products (fast pyrolysis). It is based on a technology proven on an industrial scale and especially suitable for treating a straw type of biomass.

La pirólisis rápida de residuos de biomasa en un reactor de doble husillo de mezcla

Fast pyrolysis is being increasingly applied in commercial plants worldwide. They run exclusively on woody biomass, which has favorable properties for ...

Fractionation of Lignocellulosic Biomass using the OrganoCat Process

The shift from a petroleum-based to a more sustainable and bio-based economy requires the development of new refinery concepts to maintain the supply of raw materials and energy. For these novel and sustainable biorefinery concepts, it is important to use catalysts and solvents that are aligned with the principles of Green Chemistry. Therefore, the implementation of biogenic alternatives can be a promising solution. The lignocellulose pretreatment and fractionation process presented herein-OrganoCat-is an integrated fractionation of lignocellulose into its main components using biogenic acids such as 2,5-furandicarboxylic acid as catalyst. Hemicelluloses and other non-cellulosic polysaccharides are selectively depolymerized by the diluted acid and dissolved, while the crystalline cellulose remains in the solid pulp. In the presence of a second organic phase consisting of biogenic 2-methyltetrahydrofuran, disentangled lignin is extracted in situ. The process allows for the efficient fractionation of the three main components-lignin, cellulose, and non-cellulosic sugars. This helps to focus on the quality of the lignin, the improvement of enzymatic hydrolysis of the cellulose-enriched pulp, and the mild non-cellulosic sugar extraction with low degradation.

OrganoCat is a method for the pretreatment and fractionation of lignocellulose under mild conditions into lignin, fermentable sugars, and cellulose pulp. In a biogenic, biphasic solvent system of water and 2-methyltetrahydrofuran with 2,5-furancarboxylic acid as catalyst, the OrganoCat products are separated in situ for straightforward product recovery.

Fraccionamiento de biomasa lignocelulósica mediante el proceso OrganoCat

The shift from a petroleum-based to a more sustainable and bio-based economy requires the development of new refinery concepts to maintain the supply of ...

Ultrafast Lignin Extraction from Unusual Mediterranean Lignocellulosic Residues

Pretreatment is still the most expensive step in lignocellulosic biorefinery processes. It must be made cost-effective by minimizing chemical requirements as well as power and heat consumption and by using environment-friendly solvents. Deep eutectic solvents (DESs) are key, green, and low-cost solvents in sustainable biorefineries. They are transparent mixtures characterized by low freezing points resulting from at least one hydrogen bond donor and one hydrogen bond acceptor. Although DESs are promising solvents, it is necessary to combine them with an economic heating technology, such as microwave irradiation, for competitive profitability. Microwave irradiation is a promising strategy to shorten the heating time and boost fractionation because it can rapidly attain the appropriate temperature. The aim of this study was to develop a one-step, rapid method for biomass fractionation and lignin extraction using a low-cost and biodegradable solvent. 
In this study, a microwave-assisted DES pretreatment was conducted for 60 s at 800 W, using three kinds of DESs. The DES mixtures were facilely prepared from choline chloride (ChCl) and three hydrogen-bond donors (HBDs): a monocarboxylic acid (lactic acid), a dicarboxylic acid (oxalic acid), and urea. This pretreatment was used for biomass fractionation and lignin recovery from marine residues (Posidonia leaves and aegagropile), agri-food byproducts (almond shells and olive pomace), forest residues (pinecones), and perennial lignocellulosic grasses (Stipa tenacissima). Further analyses were conducted to determine the yield, purity, and molecular weight distribution of the recovered lignin. In addition, the effect of DESs on the chemical functional groups in the extracted lignin was determined by Fourier-transform infrared (FTIR) spectroscopy. The results indicate that the ChCl-oxalic acid mixture affords the highest lignin purity and the lowest yield. The present study demonstrates that the DES-microwave process is an ultrafast, efficient, and cost-competitive technology for lignocellulosic biomass fractionation.

Deep eutectic solvent-based, microwave-assisted pretreatment is a green, fast, and efficient process for lignocellulosic fractionation and high-purity lignin recovery.

Extracción ultrarrápida de lignina de residuos lignocelulósicos mediterráneos inusuales

Pretreatment is still the most expensive step in lignocellulosic biorefinery processes. It must be made cost-effective by minimizing chemical requirements ...

Determinación de carbonilo grupos funcionales en aceites biológicos mediante valoración potenciométrica: El Método Faix

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