@inproceedings{NarraDasguptaAyetal., author = {Narra, Satyanarayana and Dasgupta, Sunanda and Ay, Peter and Zeng, T. and Weller, N.}, title = {Pelletisation of Rye- and Wheat straw with additives}, series = {19th European Biomass Conference and Exhibition, proceedings, ICC Berlin International Congress Center Berlin, Germany, conference 6 - 10 June 2011}, booktitle = {19th European Biomass Conference and Exhibition, proceedings, ICC Berlin International Congress Center Berlin, Germany, conference 6 - 10 June 2011}, publisher = {ETA-Florence Renewable Energies}, address = {Florence}, isbn = {978-88-89407-55-7}, language = {en} } @misc{DasguptaAyKommolketal., author = {Dasgupta, Sunanda and Ay, Peter and Kommolk, Ralf and Su, Xu}, title = {Kinetics of Melt Crystallization of a Sunflower Oil-Based Polyunsaturated Fatty Acid Mixture}, series = {Chemical Engineering \& Technology}, volume = {36}, journal = {Chemical Engineering \& Technology}, number = {7}, issn = {0930-7516}, doi = {10.1002/ceat.201200524}, pages = {1225 -- 1230}, abstract = {Important parameters like supercooling and cooling rates affecting the melt crys- tallization of a polyunsaturated fatty acid (PUFA) mixture obtained from sun- flower oil were investigated and compared via high-resolution polarized-light mi- croscopy. PUFA was thermally characterized in a differential scanning calorimeter and the significant liquid-solid-phase transition temperatures determined were then implemented in the development of specific temperature profiles. Analyzed between two glass slides, induction times were found to decrease with low crystal- lization temperatures and the number of nuclei per unit area increased with high- er supercooling and cooling rates. A comparison between the linear crystal growth rates of pure standards of each of the main fatty acids present in the PUFA mixture and the PUFA mixture itself indicated that the latter is much slower than that of each of its pure components.}, language = {en} } @misc{DasguptaAySchulz, author = {Dasgupta, Sunanda and Ay, Peter and Schulz, Stephanie}, title = {Determination and Comparison of Equilibrium Data of Various Plant-Based Fatty Acid Mixtures}, series = {Chemical Engineering \& Technology}, volume = {37}, journal = {Chemical Engineering \& Technology}, number = {6}, issn = {0930-7516}, doi = {10.1002/ceat.201300630}, pages = {1002 -- 1008}, abstract = {Multistage melt crystallization of a variety of plant-based polyunsaturated fatty acid (PUFA) mixtures was conducted to obtain an overview on their liquid-solid equilibrium behavior. Crystal fraction and mother liquor samples were analyzed at every stage. Phase behavior diagrams at low saturated fatty acid concentrations were investigated in detail as they are of significant technical relevance with respect to efficient depletion of the saturated content from the samples. A high oleic acid content in the PUFA mixtures led to difficulties in depleting the mother liquor from the saturated content by melt crystallization. Thermograms from the differential scanning calorimetry were supplemented with illustrations which allow a novel interpretation of results and verification of conclusions.}, language = {en} } @inproceedings{EckertDasguptaSelgeetal., author = {Eckert, Karl-Andreas and Dasgupta, Sunanda and Selge, Benjamin and Ay, Peter}, title = {Liquid solid phase behavior of ternary fatty acid systems of palmitic, stearic, oleic and linoleic acid}, series = {Book of Abstracts of the 8th Workshop on Fats and Oils as Renewable Feedstock for the Chemical Industry Karlsruhe, March 29-31, 2015}, booktitle = {Book of Abstracts of the 8th Workshop on Fats and Oils as Renewable Feedstock for the Chemical Industry Karlsruhe, March 29-31, 2015}, publisher = {abiosus e.V. Conferences}, address = {Karlsruhe, Germany}, pages = {S. 73}, abstract = {Enrichment of natural unsaturated fractions by melt crystallization processes has already been proved to be effective in prior investigations [1]-[3]. Palmitic, stearic, oleic, linoleic and linolenic acid are the five main fatty acids present in most of these plant based natural oils. There is quite a bit of information about the liquid solid phase behavior of binary mixtures such as palmitic-oleic, stearic-oleic and palmitic-stearic acid mixtures in literature [4]-[6]. Recent investigations have shown phase diagrams of real natural oil based fatty acid systems containing up to 19\% saturated content (11\% stearic acid and 8\% palmitic acid) [7]. Yet, there is hardly any information regarding ternary systems as those of palmitic-stearic-oleic and palmitic-stearic-linoleic acids. In this work, synthetic mixtures have been used in order to obtain a complete overview of the liquid solid phase diagrams of these ternary mixtures. To imitate naturally occurring mixtures, a mixture with 1:1 ratio of palmitic stearic acid was prepared. Varying amounts of either oleic or linoleic acids were added to this mixture in order to obtain the entire range required for the phase diagrams. These mixtures were then subjected to a specific profile with a wide temperature range in a Differential Scanning Calorimeter (DSC) so as to record every phase transition. This study successfully concludes that these complex mixtures could be treated as binary mixtures of their saturated and unsaturated contents. This is because there were essentially two main peaks noted in the DSC thermograms. It is to be noted that there was a third peak, assumed to represent the solid transition, in mixtures containing oleic acid. This has already been shown in detail and discussed in prior investigations [6], [7]. Another major discovery was that the solidus line depends on the type of the unsaturated content, that is, the degree of unsaturation, in the mixture.}, language = {en} } @inproceedings{EckertDasguptaAy, author = {Eckert, Karl-Andreas and Dasgupta, Sunanda and Ay, Peter}, title = {Novel techniques to optically characterize melt crystallization kinetics of high oleic sunflower oil based fatty acid mixture}, series = {Book of Abstracts of the 7th Workshop on Fats and Oils as Renewable Feedstock for the Chemical Industry Karlsruhe, March 23-25, 2014}, booktitle = {Book of Abstracts of the 7th Workshop on Fats and Oils as Renewable Feedstock for the Chemical Industry Karlsruhe, March 23-25, 2014}, publisher = {abiosus e.V. Conferences}, address = {Karlsruhe, Germany}, abstract = {The rising applications of enriched unsaturated fatty acid fractions are significantly increasing the need for a cheap method of manufacturing such fractions. Melt crystallization is an established method for purification and enrichment of desired fractions from mixtures [1, 2, 3]. Enrichment of such natural unsaturated fractions by melt crystallization processes has already been proved effective in prior investigations [1, 2]. Since then many analytical and investigative methods have been applied on various natural plant oil based poly-unsaturated fatty acid (PUFA) mixtures to generate the much needed fundamental melt crystallization data [1]. One such method is the use of in-situ polarized light microscopy [1, 4, 5]. Some of the important parameters affecting the melt crystallization of PUFA mixtures are nucleation and crystal growth rate. To be able to observe and visualize these micro-scale phenomena, circular polarized transmitted light microscopy was applied. A tempered chamber (Linkam LS 120) containing the sample between two object slides was placed right within the microscope camera setup (Leica DM RME and Leica DFC 500) with a viewing window. With respect to the transmitted light, the sample was placed between two circular polarized filters such that the system is calibrated for optimal visualization. Unlike linear polarization, in this method every crystal independent of its alignment in the sample, delivers an interference color different from its background. This way, the entire crystal structure could be clearly separated from the melt. Nucleation and crystal growth rate of a high oleic sunflower oil based PUFA was measured using this method at 5K supercooling and 10K/min cooling rate. Growth curves for total crystal area and number of crystals were analyzed and illustrated graphically. A typical S- curve is observed for both the cases starting with a lag phase followed by an exponential growth phase and ending in a saturation phase.}, language = {en} } @inproceedings{DasguptaAy, author = {Dasgupta, Sunanda and Ay, Peter}, title = {In-situ monitoring and induction time measurements during melt crystallization of plant based fatty acid mixtures in V-form reactor}, series = {6th Workshop on Fats and Oils as Renewable Feedstock for the Chemical Industry Karlsruhe, March 17-19, 2013}, booktitle = {6th Workshop on Fats and Oils as Renewable Feedstock for the Chemical Industry Karlsruhe, March 17-19, 2013}, publisher = {abiosus e.V. Conferences}, address = {Karlsruhe, Germany}, abstract = {Enriched plant based unsaturated fatty acid mixtures are increasingly finding applications in various fields like those of production of bio-fuels and polymerization of epoxy resins. In the case of production of epoxy resins, they are highly advantageous due to the presence of multiple double bonds in the fatty acids which provide opportunities for cross linking by substitution. On the other hand, bio-fuels need raw materials with very low crystallization temperatures. This special property can also be attributed to these enriched unsaturated fractions due to their weak inter-molecular interactions owing to the kink in their structures. Melt crystallization has long been established as an optimal method for purification and enrichment of fractions from mixtures [1,2]. Previous studies have shown promising results with regard to enrichment of unsaturated fractions by melt crystallization processes [1]. Melt crystallization kinetics of two plant based poly-unsaturated fatty acid mixtures have been investigated in this study [3]. A high oleic and a high linoleic fatty acid mixture were chosen for comparison purposes. A V-form reactor was developed for optimal in-situ analysis with the help of the focused beam reflectance measurement (FBRM®, Mettler Toledo Ltd., Switzerland) instrument [3]. Enhanced heat transfer especially to deal with the heat given out during crystallization was enabled through minimal volume of sample, optimized mixing and the special shape of the reactor. Important parameters like induction time, mixing speed, etc have been determined and compared as functions of degree of supercooling and composition of PUFA mixtures. In accordance to theory, the induction times in both the cases decreased with increasing supercooling and mixer speed. On the other hand, the high linoleic fatty acid mixture required much higher supercooling (4.4K to 5.4K) than the high oleic mixture (2.2K to 3.2K) for favorable induction times.}, language = {en} } @inproceedings{DasguptaAy, author = {Dasgupta, Sunanda and Ay, Peter}, title = {Enrichment of unsaturated fractions in a Linseed oil based fatty acid mixture by melt crystallisation}, series = {5th Workshop on Fats and Oils as Renewable Feedstock for the Chemical Industry, Karlsruhe, Germany}, booktitle = {5th Workshop on Fats and Oils as Renewable Feedstock for the Chemical Industry, Karlsruhe, Germany}, pages = {S. 93}, abstract = {Enriched plant based unsaturated fatty acid mixtures are increasingly finding applications in various fields like those of production of bio-fuels and polymerization of epoxy resins. In the case of production of epoxy resins, they are highly advantageous due to the presence of multiple double bonds in the fatty acids which provide opportunities for cross linking by substitution. On the other hand, bio-fuels need raw materials with very low crystallization temperatures. This special property can also be attributed to these enriched unsaturated fractions due to their weak inter-molecular interactions owing to the kink in their structures. Melt crystallization has long been established as an optimal method for purification and enrichment of fractions from mixtures [1,2]. Previous studies have shown promising results with regard to enrichment of unsaturated fractions by melt crystallization processes [1]. Melt crystallization kinetics of two plant based poly-unsaturated fatty acid mixtures have been investigated in this study [3]. A high oleic and a high linoleic fatty acid mixture were chosen for comparison purposes. A V-form reactor was developed for optimal in-situ analysis with the help of the focused beam reflectance measurement (FBRM®, Mettler Toledo Ltd., Switzerland) instrument [3]. Enhanced heat transfer especially to deal with the heat given out during crystallization was enabled through minimal volume of sample, optimized mixing and the special shape of the reactor. Important parameters like induction time, mixing speed, etc have been determined and compared as functions of degree of supercooling and composition of PUFA mixtures. In accordance to theory, the induction times in both the cases decreased with increasing supercooling and mixer speed. On the other hand, the high linoleic fatty acid mixture required much higher supercooling (4.4K to 5.4K) than the high oleic mixture (2.2K to 3.2K) for favorable induction times. References [1] S. Dasgupta, N. Dreiack, P. Ay, presented at the 5th Workshop on Fats and Oils as Renewable Feedstock for the Chemical Industry (Eds: J.O. Metzger, M.A.R. Meier), Karlsruhe 2012 [2] G.F. Arkenbout, Melt Crystallization Technology, Technomic Publishing Company Inc., Pennsylvania 1995 [3] S. Xu, Master thesis, Chair of Mineral Processing, Processing of Biogenous Resources, Brandenburg University of Technology, Cottbus 2010}, language = {en} } @misc{DasguptaRettigAy, author = {Dasgupta, Sunanda and Rettig, Florian and Ay, Peter}, title = {Nucleation kinetics during melt crystallization of plant based high oleic and linoleic polyunsaturated fatty acid mixtures}, series = {Crystal Growth \& Design}, volume = {16}, journal = {Crystal Growth \& Design}, number = {2}, issn = {1528-7505}, doi = {10.1021/acs.cgd.5b01432}, pages = {861 -- 866}, abstract = {Nucleation kinetics of high linoleic and high oleic polyunsaturated fatty acid (PUFA) mixtures were investigated during melt crystallization by means of an Focused beam reflectance measurement (FBRM) sensor. Samples were analyzed thermally and chemically in the Differential Scanning Calorimeter (DSC) and Gas Chromatograph (GC) respectively. Investigations showed that a high oleic content in the PUFA mixtures lead to higher induction times, τi. Unlike previous investigations, a clear relation between τi and cooling rates was established. τi increases with increasing cooling rates and decreasing supercooling. Activation energies of nucleation, ∆Gc' were determined by means of the Fisher Turnbull equation wherein ∆Gc' decreases exponentially with increasing supercooling. Investigations and further evaluations conclude that while the plot establishes the effect of supercooling on ∆Gc' , it does not incorporate the effects of molecular diffusion or the cooling rate. Hence, 3D modeling was performed to visualize the combined effects of cooling rate and supercooling on induction time.}, language = {en} } @misc{EckertDasguptaSelgeetal., author = {Eckert, Karl-Andreas and Dasgupta, Sunanda and Selge, Benjamin and Ay, Peter}, title = {Solid liquid phase diagrams of binary fatty acid mixtures - Palmitic/stearic with oleic/linoleic/linolenic acid mixture}, series = {Thermochimica Acta}, volume = {Vol. 630}, journal = {Thermochimica Acta}, issn = {0040-6031}, doi = {10.1016/j.tca.2016.02.008}, pages = {50 -- 63}, abstract = {The solid liquid phase diagrams of binary mixtures of the five main saturated and unsaturated fatty acids present in most edible plant oils have been determined in this paper. These binary mixtures comprise of a saturated fatty acid, either palmitic (C16:0) or stearic (C18:0) and an unsaturated one, oleic (C18:1), linoleic (C18:2) or linolenic (C18:3) acid. Differential scanning calorimetry (DSC) was used to obtain an overview of the solid liquid transition behaviour including the metastable ranges of these mixtures. In order to describe all the phase transformations in these systems, the boundary functions have been determined and compared. Phase diagrams determined, illustrate characteristic behaviour in accordance to literature. This work specifically focuses on to describe the solid liquid transitions of the mixtures and not on every single transition or reaction. This paper contributes to the elucidation of the phase behaviour of these important mixtures which are applied in diverse industries.}, language = {en} } @misc{DasguptaDreiackAy, author = {Dasgupta, Sunanda and Dreiack, Nadine and Ay, Peter}, title = {Melt crystallization kinetics for enrichment of highly unsaturated fatty acid fractions based on Linseed oil}, series = {Journal of Environmental Research And Development}, volume = {11}, journal = {Journal of Environmental Research And Development}, number = {1}, issn = {0973-6921}, pages = {1 -- 6}, abstract = {Naturally occurring plant based fats and oils have a huge potential as renewable resources to synthesize chemically new products apart from being widely used as ingredients in various kind of food and cosmetics. Oils are triglycerides which are basically tri-esters made of glycerol and three fatty acids. The latter finds application on one hand as raw material for the polymerization of epoxy resins whereas on the other in the manufacturing of biodiesel amongst others. Melt crystallization as a method to enrich a fatty acid mixture with higher unsaturated fractions is becoming increasingly established. A polyunsaturated fatty acid mixture with high concentration of linolenic acid (C 18:3) was chosen for this work. This linolenic oil fatty acid rich mixture was subjected to different temperature profiles in order to optimize maximum yield of unsaturated fatty acid in the mother liquor post isothermal centrifugal separation. The influence of the temperature profile on the quality of the desired product was thereby investigated. To examine the exact composition of the resulting product several analytical methods like Differential Scanning Calorimetry (DSC) and Gas Chromatography (GC) were developed and performed. Product compositions with a total saturated content (C16:0 - palmitic acid and C18:0 - stearic acid) of below 3\% was achieved successfully.}, language = {en} } @misc{EckertDasguptaSelgeetal., author = {Eckert, Karl-Andreas and Dasgupta, Sunanda and Selge, Benjamin and Ay, Peter}, title = {Construction and comparison of solid liquid phase diagrams of binary sat-sat and unsat-unsat fatty acid mixtures comprising two of palmitic/stearic/oleic/linoleic/linolenic acid}, series = {Journal of Environmental Research And Development}, volume = {10}, journal = {Journal of Environmental Research And Development}, number = {4}, issn = {0973-6921}, pages = {10}, abstract = {In this paper, binary phase diagrams of the five main fatty acids present in edible oil based mixtures are shown. While previously the binary systems of one saturated and one unsaturated acid were investigated, in this work the binary mixtures comprise of palmitic (C16:0) and stearic acid (C18:0) or a binary mixture of oleic (C18:1), linoleic (C18:2) or linolenic acid (C18:3). In order to obtain the phase diagrams with all the solid liquid and solid phase transitions, the mixtures were analyzed by means of Differential Scanning Calorimetry (DSC). Phase change boundary functions based on thermodynamic models and experimental values were fitted and compared. The phase diagrams obtained show behaviors in good agreement to literature. The paper contributes to the deeper understanding of the essential phase change effects during industrial crystallization processes.}, language = {en} } @misc{EckertDasguptaSelgeetal., author = {Eckert, Karl-Andreas and Dasgupta, Sunanda and Selge, Benjamin and Ay, Peter}, title = {Novel model for the prediction of SSLE temperatures and crystallization paths of any mixture containing palmitic, stearic, oleic, linoleic and linolenic acid}, series = {Thermochimica Acta}, volume = {652}, journal = {Thermochimica Acta}, issn = {0040-6031}, doi = {10.1016/j.tca.2017.03.015}, pages = {126 -- 140}, abstract = {A mathematical model for the prediction of phase change temperatures and crystallization paths for mixtures consisting of palmitic (P), stearic (S), oleic (O), linoleic (L) and linolenic acid (Ll) in any distribution is presented in this paper. This model is based on the information gathered from modeled ternary phase diagrams, namely PSO, PSL, PSLl and OLLl, that were based on experimental binary phase diagrams of all possible combinations of these fatty acids. These experimental binary phase diagrams were obtained by means of differential scanning calorimetry and mathematical function fitting, within which the eutectic region of binary palmitic/stearic with oleic/linoleic/linolenic acid was investigated in detail. The basic mathematical model used was previously shown in literature which delivered good results for such systems. The importance of the developed model was then justified by investigations on real and composed synthetic fatty acid mixtures, where a high accuracy of the predicted temperatures could be shown for the technically relevant liquidus and solidus temperatures. A satisfying prediction for thermal events below the first solidus line could be reached as well. This work directly contributes to an enhanced understanding of the thermodynamic and kinetic background of such important mixtures applied in diverse products and industries, thereby showing a large optimization potential for crystallization technologies.}, language = {en} } @inproceedings{DasguptaGlaserAy, author = {Dasgupta, Sunanda and Glaser, Claudia and Ay, Peter}, title = {SLE diagram for a high oleic palm oil based fatty acid mixture at low saturated content}, series = {9th Workshop on Fats and Oils as Renewable Feedstock for the Chemical Industry, March 19-21, 2017, Karlsruhe, Germany}, booktitle = {9th Workshop on Fats and Oils as Renewable Feedstock for the Chemical Industry, March 19-21, 2017, Karlsruhe, Germany}, publisher = {Abiosus e.V.}, address = {Oldenburg}, abstract = {Vegetable oils and their derivatives are increasingly replacing mineral oils in their applications.[1,2] Among other constituents in vegetable oil, both saturated and unsaturated fractions are important raw materials. The latter possesses double bonds which can provide as substrates or raw materials for various chemical industries.[3] Fractionation of these oils or as in our case the Poly-Unsaturated Fatty Acid (PUFA) mixture is required so as to generate favorable compositions according to applications. Generation of Solid Liquid Equilibrium (SLE) phase diagrams for real mixtures is extremely important to enable a thorough understanding of the thermodynamics of the fractionation process of crystallization. The PUFA mixture was fractionated in a multistage scrubbing layer crystallizer. The product was put into a decanter centrifuge so as to fractionate them into mother liqor and crystal fraction. The temperature in the jacket was maintained such that △T< 5K from the liquidus point obtained from the Differential Scanning Calorimeter (DSC) thermal analyses. Each crystallizer was also maintained at a temperature 5K below the previous one. This way a slow and successive cooling of the PUFA was achieved such that probes from different fraction could be obtained. They were analyzed thermally and chemically in the DSC and Gas Chromatography - Flame Ionization Detector (GC-FID) setup respectively.[4] Similar to previous literature as in [5], technically relevant partial SLE diagrams for high oleic palm oil was created by fractionating the mixture in a scrubbed layer crystallizer along with their metastable range were determined.[6]}, language = {en} } @phdthesis{Dasgupta, author = {Dasgupta, Sunanda}, title = {Metastable zone determination and nucleation kinetics during melt crystallization of poly-unsaturated fatty acids}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:co1-opus4-44175}, pages = {228}, abstract = {The range of application of fatty acids is as broad and varied as the diverse kinds of fatty acids themselves, stretching from bulk scale productions as in the case of biodiesel or lubricant manufacturing over consumer or end products like cosmetics, medicinal or nutritional additives to relatively smaller scale specialty chemicals like epoxy resins, insect repellents and so on. The crystallization temperatures of the unsaturated fatty acids are much lower than those of the saturated ones, which is an important and desirable property for raw materials such as in the production of epoxy resins. Separation and purification of these enriched unsaturated fatty acid fractions depending on their applications is mainly performed by two thermal fractionation processes, namely, distillation and crystallization. The potential behind the success of purification of these multi-component organic fatty acid mixtures with the help of melt crystallization, apart from the fact that it is cost effective owing to the obvious reduction of solvent removal and regeneration steps, is that of the relatively large differences in the melting points of the individual fatty acids. A detailed and fundamental understanding of the crystallization especially nucleation kinetics of a variety of vegetable oil based fatty acid mixtures has been provided in this work. It also describes the solid-liquid phase diagrams of these poly-unsaturated mixtures including their metastable zone widths of nucleation and solidification. This theoretical part of this thesis is a detailed resource on the global production and application of vegetable oils and their derivatives. A clear mathematical and physical road map for the application of the Fisher Turnbull model to calculate the enthalpy values starting from the very basic supersaturation equation has been established and extensively explained as well. Nucleation studies have been carried out on various reactor setups in micro-, milli- and liter-scale. It successfully models the induction times of nucleation as a function of supercooling at different cooling rates both in micro and macro scale. 3D modeling of this parameter to see the combined effects of temperature and in turn viscosity have also been successfully implemented on the milliliter scale results, as more of the bulk nucleation phenomenon was observed in the latter. Fisher Turnbull plot and the Gibbs Thompsons model were adjusted and applied to correlate the Gibbs free energy, involved with the rate of nucleation captured by the FBRM™ (Focused Beam Reflectance Measurement) technology. The scope of this measurement technology was also tested in liter scale. The results showed that FBRM technology is applicable when the solution is relatively dilute and does not have too many overlapping crystals.}, language = {en} }