Ana Pardal - Academia.edu (original) (raw)
Papers by Ana Pardal
Coloration Technology, 2001
Although monomethine cyanines and reactive dyes, used mainly for dyeing textile goods, are well s... more Although monomethine cyanines and reactive dyes, used mainly for dyeing textile goods, are well studied, the development of cyanines with groups capable of being bound covalently to a solid support has been largely unexplored. The scope of this study was the synthesis and characterisation of aminocyanines capable of binding to microcrystalline cellulose, through the polyfunctional cross-linking agent cyanuric chloride. In a second approach, the cyanines bound to microcrystalline cellulose in varying amounts were used as specific ligands in affinity chromatography. Two different methods to determine the amount of cyanine linked to the dyed cellulose were used, based on Fourier transform infrared spectroscopy and elemental analysis. The fixation yields of the two different cyanines bound to cellulose were determined.
Coloration Technology, 2002
An isothiocyanato-functionalised cyanine was synthesised, characterised, immobilised on agarose g... more An isothiocyanato-functionalised cyanine was synthesised, characterised, immobilised on agarose gel and the dye-affinity adsorbent ability for purifying some standard proteins (e.g. bovine serum albumin, trypsin and chymotrypsin) was analysed. The influence of mobile phase composition on the chromatographic behaviour of these proteins was also studied. A selective interaction between the studied proteins and the immobilised cyanine was obtained.
Comunicacao apresentada na 18th European Biomass Conference and Exhibition, Lyon (Franca), Maio d... more Comunicacao apresentada na 18th European Biomass Conference and Exhibition, Lyon (Franca), Maio de 2010
Resumos: 3o Simposio em Producao e Transformacao de Alimentos, «Sustentabilidade, Inovacao e Nutr... more Resumos: 3o Simposio em Producao e Transformacao de Alimentos, «Sustentabilidade, Inovacao e Nutricao», Escola Superior de Saude, Instituto Politecnico de Leiria, 2 Junho de 2017
Fuel, 2016
h i g h l i g h t s The presence of co-solvents facilitates the reaction of transesterification. ... more h i g h l i g h t s The presence of co-solvents facilitates the reaction of transesterification. High yield and fast reaction could be obtained at relatively low temperature. The optimum conditions led to biodiesel with 98% ester content. Transesterification kinetics was described by a pseudo first order kinetic model.
Fuel, 2012
The production of methyl esters from soybean transesterification by the use of a microwave flow s... more The production of methyl esters from soybean transesterification by the use of a microwave flow system has been investigated. A household microwave was modified as a biodiesel reactor for continuous transesterification. The effects of temperature at the exit point (50-110°C), the methanol/oil molar ratio (3:1, 6:1, 9:1 and 12:1) and the catalyst concentration (0.5%, 1.0% and 1.5% in weight of KOH) were evaluated. Final temperature depended on the reaction time, on the microwave power and on the reaction composition, mainly the methanol content. The obtained conversion was over 99% of methyl ester content, with a methanol/oil molar ratio of 12:1, a catalyst concentration of 1.0 wt.% and a final temperature of 70°C (this temperature was arisen with 2 min residence time and 200 W of power). In order to compare, the conventional heating systems were also employed in transesterification in homogeneous batch and flow processes. The transesterification reaction under microwave radiation yielded similar results but with very fast heating rates.
Fuel Processing Technology, 2012
In this study, transesterification of rapeseed oil using subcritical methanol conditions was stud... more In this study, transesterification of rapeseed oil using subcritical methanol conditions was studied. The objective of the work was characterizing the methyl esters for its use as biodiesel in compression ignition motors. The variables affecting the methyl ester yield during the transesterification reaction, such as, the catalyst type and content, reaction temperature and pressure, the presence of hexane as co-solvent, the methanol oil molar ratio and the methanol hexane molar ratio were investigated to optimize the reaction conditions. The evolution of the process was followed by gas chromatography, determining the concentration of the methyl esters at different reaction times. The biodiesel was characterized by its density, viscosity, saponification value, iodine value, acidity index and water content, according to ISO norms. High methyl ester yield and fast reaction rate could be obtained even if the reaction pressure was relatively low, which is quite favorable to the production of biodiesel in industry.
Fuel Processing Technology, 2010
This work studies the application of KNO3/CaO catalyst in the transesterification reaction of tri... more This work studies the application of KNO3/CaO catalyst in the transesterification reaction of triglycerides with methanol. The objective of the work was characterizing the methyl esters for its use as biodiesel in compression ignition motors. The variables affecting the methyl ester yield during the transesterification reaction, such as, amount of KNO3 impregnated in CaO, the total catalyst content, reaction temperature,
Fuel Processing Technology, 2012
In this work, the preliminary results obtained in the transesterification of castor-oil with meth... more In this work, the preliminary results obtained in the transesterification of castor-oil with methanol in the presence of ultrasonic irradiations, are presented. The fundamental objective was to study the acceleration that the ultrasound causes in the reaction rate. The effect of different operating variables, such as frequency and supplied power dissipation, catalyst (KOH) concentration and methanol oil molar ratio were also investigated. The evolution of the process was followed by gas chromatography, determining the concentration of the methyl esters at different reaction times. The biodiesel was characterized by its density, viscosity, saponification value, iodine value, acidity index, water content, flash point, combustion point, cetane index and cold filter plugging point (CFPP), according to ISO norms. Between these properties, viscosity, the number of cetane and the CFPP do not attain the values established by the standard EN 14214. These circumstances would force to use the castor biodiesel oil mixed with diesel fuel oil, or to add additives in order that the previous properties reach the specified values. High methyl ester yield and fast reaction rate could be obtained, for castor oil transesterification, under ultrasonic conditions, even if the reaction temperature was relatively low. In general, the variables of operation tested exercise a positive effect on the reaction rate, but the obtained final yield (equilibrium) is very similar in all cases.
Coloration Technology, 2001
Although monomethine cyanines and reactive dyes, used mainly for dyeing textile goods, are well s... more Although monomethine cyanines and reactive dyes, used mainly for dyeing textile goods, are well studied, the development of cyanines with groups capable of being bound covalently to a solid support has been largely unexplored. The scope of this study was the synthesis and characterisation of aminocyanines capable of binding to microcrystalline cellulose, through the polyfunctional cross-linking agent cyanuric chloride. In a second approach, the cyanines bound to microcrystalline cellulose in varying amounts were used as specific ligands in affinity chromatography. Two different methods to determine the amount of cyanine linked to the dyed cellulose were used, based on Fourier transform infrared spectroscopy and elemental analysis. The fixation yields of the two different cyanines bound to cellulose were determined.
Coloration Technology, 2002
An isothiocyanato-functionalised cyanine was synthesised, characterised, immobilised on agarose g... more An isothiocyanato-functionalised cyanine was synthesised, characterised, immobilised on agarose gel and the dye-affinity adsorbent ability for purifying some standard proteins (e.g. bovine serum albumin, trypsin and chymotrypsin) was analysed. The influence of mobile phase composition on the chromatographic behaviour of these proteins was also studied. A selective interaction between the studied proteins and the immobilised cyanine was obtained.
Comunicacao apresentada na 18th European Biomass Conference and Exhibition, Lyon (Franca), Maio d... more Comunicacao apresentada na 18th European Biomass Conference and Exhibition, Lyon (Franca), Maio de 2010
Resumos: 3o Simposio em Producao e Transformacao de Alimentos, «Sustentabilidade, Inovacao e Nutr... more Resumos: 3o Simposio em Producao e Transformacao de Alimentos, «Sustentabilidade, Inovacao e Nutricao», Escola Superior de Saude, Instituto Politecnico de Leiria, 2 Junho de 2017
Fuel, 2016
h i g h l i g h t s The presence of co-solvents facilitates the reaction of transesterification. ... more h i g h l i g h t s The presence of co-solvents facilitates the reaction of transesterification. High yield and fast reaction could be obtained at relatively low temperature. The optimum conditions led to biodiesel with 98% ester content. Transesterification kinetics was described by a pseudo first order kinetic model.
Fuel, 2012
The production of methyl esters from soybean transesterification by the use of a microwave flow s... more The production of methyl esters from soybean transesterification by the use of a microwave flow system has been investigated. A household microwave was modified as a biodiesel reactor for continuous transesterification. The effects of temperature at the exit point (50-110°C), the methanol/oil molar ratio (3:1, 6:1, 9:1 and 12:1) and the catalyst concentration (0.5%, 1.0% and 1.5% in weight of KOH) were evaluated. Final temperature depended on the reaction time, on the microwave power and on the reaction composition, mainly the methanol content. The obtained conversion was over 99% of methyl ester content, with a methanol/oil molar ratio of 12:1, a catalyst concentration of 1.0 wt.% and a final temperature of 70°C (this temperature was arisen with 2 min residence time and 200 W of power). In order to compare, the conventional heating systems were also employed in transesterification in homogeneous batch and flow processes. The transesterification reaction under microwave radiation yielded similar results but with very fast heating rates.
Fuel Processing Technology, 2012
In this study, transesterification of rapeseed oil using subcritical methanol conditions was stud... more In this study, transesterification of rapeseed oil using subcritical methanol conditions was studied. The objective of the work was characterizing the methyl esters for its use as biodiesel in compression ignition motors. The variables affecting the methyl ester yield during the transesterification reaction, such as, the catalyst type and content, reaction temperature and pressure, the presence of hexane as co-solvent, the methanol oil molar ratio and the methanol hexane molar ratio were investigated to optimize the reaction conditions. The evolution of the process was followed by gas chromatography, determining the concentration of the methyl esters at different reaction times. The biodiesel was characterized by its density, viscosity, saponification value, iodine value, acidity index and water content, according to ISO norms. High methyl ester yield and fast reaction rate could be obtained even if the reaction pressure was relatively low, which is quite favorable to the production of biodiesel in industry.
Fuel Processing Technology, 2010
This work studies the application of KNO3/CaO catalyst in the transesterification reaction of tri... more This work studies the application of KNO3/CaO catalyst in the transesterification reaction of triglycerides with methanol. The objective of the work was characterizing the methyl esters for its use as biodiesel in compression ignition motors. The variables affecting the methyl ester yield during the transesterification reaction, such as, amount of KNO3 impregnated in CaO, the total catalyst content, reaction temperature,
Fuel Processing Technology, 2012
In this work, the preliminary results obtained in the transesterification of castor-oil with meth... more In this work, the preliminary results obtained in the transesterification of castor-oil with methanol in the presence of ultrasonic irradiations, are presented. The fundamental objective was to study the acceleration that the ultrasound causes in the reaction rate. The effect of different operating variables, such as frequency and supplied power dissipation, catalyst (KOH) concentration and methanol oil molar ratio were also investigated. The evolution of the process was followed by gas chromatography, determining the concentration of the methyl esters at different reaction times. The biodiesel was characterized by its density, viscosity, saponification value, iodine value, acidity index, water content, flash point, combustion point, cetane index and cold filter plugging point (CFPP), according to ISO norms. Between these properties, viscosity, the number of cetane and the CFPP do not attain the values established by the standard EN 14214. These circumstances would force to use the castor biodiesel oil mixed with diesel fuel oil, or to add additives in order that the previous properties reach the specified values. High methyl ester yield and fast reaction rate could be obtained, for castor oil transesterification, under ultrasonic conditions, even if the reaction temperature was relatively low. In general, the variables of operation tested exercise a positive effect on the reaction rate, but the obtained final yield (equilibrium) is very similar in all cases.