Inorganic salts effect on wheat straw during steam explosion treatment

Wheat straw is an abundant low cost byproduct. Its use is usually limited in litter and cattle feed. In order to better valorize this lignocellulosic biomass in high added value products, a material preliminary fraction should be done. In this study, a steam explosion pretreatment was applied at different pressure 15 and 20 bar with a residence time of 2 min using different solvents (distilled water and salt water 35g/l NaCl). The objective is to investigate the effect of the operating parameters and salts on the extraction yield of different molecules and their degradation products. The results shows that sodium chloride enhanced the hemicellulose and cellulose removal compared to distilled water

The key role of pretreatment for the one-step and multi-step conversions of European lignocellulosic materials into furan compounds.

peer reviewedNowadays, an increased interest from the chemical industry towards the furanic compounds production, renewable molecules alternatives to fossil molecules, which can be transformed into a wide range of chemicals and biopolymers. These molecules are produced following hexose and pentose dehydration. In this context, lignocellulosic biomass, owing to its richness in carbohydrates, notably cellulose and hemicellulose, can be the starting material for monosaccharide supply to be converted into bio-based products. Nevertheless, processing biomass is essential to overcome the recalcitrance of biomass, cellulose crystallinity, and lignin crosslinked structure. The previous reports describe only the furanic compound production from monosaccharides, without considering the starting raw material from which they would be extracted, and without paying attention to raw material pretreatment for the furan production pathway, nor the mass balance of the whole process. Taking account of these shortcomings, this review focuses, firstly, on the conversion potential of different European abundant lignocellulosic matrices into 5-hydroxymethyl furfural and 2-furfural based on their chemical composition. The second line of discussion is focused on the many technological approaches reported so far for the conversion of feedstocks into furan intermediates for polymer technology but highlighting those adopting the minimum possible steps and with the lowest possible environmental impact. The focus of this review is to providing an updated discussion of the important issues relevant to bringing chemically furan derivatives into a market context within a green European context

Extraction et conversion des molécules actives de la biomasse végétale : Utilisation des sels comme catalyseurs et solvants verts

Global awareness of the inevitable depletion of fossil carbon resources, the need to fight climate change, and the reduction of greenhouse gas emissions leads to implementing sustainable alternatives to fossil carbon. The sustainable development strategy is based on biomass integration with good savings and better management. Natural molecules including cellulose, hemicellulose and lignin can be extracted from this biomass and processed to produce energy and biobased products to replace synthetic products. This work fits into the framework of lignocellulosic biomass valorisation and the ecological solvent use, particularly salts, which are among green chemistry principles. First, the entire chemical composition and phytochemical characterisation of agri-food side-products, marine residue, and wild grass feedstock have been evaluated. These residues were classified into three new categories, and their potential as inflows in biorefining operations was studied. Results showed that liquid biofuels and platform chemical production reached more than 2 to 9 million tons annually. Furthermore, the physicochemical changes of pretreated biomasses under hydrothermal conditions combined with inorganic salts were evaluated. Hemicellulose extraction is improved by increasing the salt (NaCl, KI) concentration, reaching 93%. Oligosaccharide and degraded products formation were also increased, reaching 19.7 % and 24 %, respectively. The followed NaOH treatment efficiently extracted cellulose and lignin with high yields and purities. Moreover, it also improved enzyme accessibility for cellulose conversion into glucose by seven times more. Besides, to better understand dehydrated product formation (5-HMF, 2-F, lactic acid, formic acid and levulinic acid) produced from carbohydrates, the monosaccharides D-xylose and D-glucose were dehydrated in seawater and salts solution. The introduction of NaCl (1.19 M) promoted the conversion of D-xylose to 2-F from 28% to 44% compared to deionised water. In seawater, 5-HMF production from D-glucose was raised to 30%, and lactic acid production increased by 10 % for both monosaccharides. Moreover, the potential of DESs solvent for lignocellulosic matrice fractionation and lignin recovery was explored. An ultrafast process comprising microwave-DES combination efficiently extracted lignin with a purity exceeding 70 % in 60 s at 800 W. This research demonstrates the application of green chemistry principles using renewable raw materials, bioprocesses (steam explosion, microwave, hydrothermal reactor) and green catalysts (inorganic and organic salts) to produce safer bioproducts. This work supports the possibility of exploiting Mediterranean biomass, available in huge quantities at low cost and under-exploited, for bioproducts production (fuels, chemicals, and biogas).13. Climate action7. Affordable and clean energy9. Industry, innovation and infrastructure11. Sustainable cities and communitie

Analyses de mémoire à bas cout pour des compilateurs efficaces

This thesis was motivated by the emergence of massively parallel processing and supercomputingthat tend to make computer programming extremely performing. Speedup, the power consump-tion, and the efficiency of both software and hardware are nowadays the main concerns of theinformation systems community. Handling memory in a correct and efficient way is a step towardless complex and more performing programs and architectures. This thesis falls into this contextand contributes to memory analysis and compilation fields in both theoretical and experimentalaspects.Besides the deep study of the current state-of-the-art of memory analyses and their limitations,our theoretical results stand in designing new algorithms to recover part of the imprecisionthat published techniques still show. Among the present limitations, we focus our research onthe pointer arithmetic to disambiguate pointers within the same data structure. We develop ouranalyses in the abstract interpretation framework. The key idea behind this choice is correctness,and scalability: two requisite criteria for analyses to be embedded to the compiler construction.The first alias analysis we design is based on the range lattice of integer variables. Given a pair ofpointers defined from a common base pointer, they are disjoint if their offsets cannot have valuesthat intersect at runtime. The second pointer analysis we develop is inspired from the Pentagonabstract domain. We conclude that two pointers do not alias whenever we are able to build astrict relation between them, valid at program points where the two variables are simultaneouslyalive. In a third algorithm we design, we combine both the first and second analysis, and enhancethem with a coarse grained but efficient analysis to deal with non related pointers.We implement these analyses on top of the LLVM compiler. We experiment and evaluate theirperformance based on two metrics: the number of disambiguated pairs of pointers compared tocommon analyses of the compiler, and the optimizations further enabled thanks to the extraprecision they introduceLa rapidité, la consommation énergétique et l'efficacité des systèmes logiciels et matériels sont devenues les préoccupations majeures de la communauté informatique de nos jours. Gérer de manière correcte et efficace les problématiques mémoire est essentiel pour le développement des programmes de grande tailles sur des architectures de plus en plus complexes. Dans ce contexte, cette thèse contribue aux domaines de l'analyse mémoire et de la compilation tant sur les aspects théoriques que sur les aspects pratiques et expérimentaux. Outre l'étude approfondie de l'état de l'art des analyses mémoire et des différentes limitations qu'elles montrent, notre contribution réside dans la conception et l'évaluation de nouvelles analyses qui remédient au manque de précision des techniques publiées et implémentées. Nous nous sommes principalement attachés à améliorer l'analyse de pointeurs appartenant à une même structure de données, afin de lever une des limitations majeures des compilateurs actuels. Nous développons nos analyses dans le cadre général de l'interprétation abstraite « non dense ». Ce choix est motivé par les aspects de correction et d'efficacité : deux critères requis pour une intégration facile dans un compilateur. La première analyse que nous concevons est basée sur l'analyse d'intervalles des variables entières ; elle utilise le fait que deux pointeurs définis à l'aide d'un même pointeur de base n'aliasent pas si les valeurs possibles des décalages sont disjointes. La seconde analyse que nous développons est inspirée du domaine abstrait des Pentagones ; elle génère des relations d'ordre strict entre des paires de pointeurs comparables. Enfin, nous combinons et enrichissons les deux analyses précédentes dans un cadre plus général. Ces analyses ont été implémentées dans le compilateur LLVM. Nous expérimentons et évaluons leurs performances, et les comparons aux implémentations disponibles selon deux métriques : le nombre de paires de pointeurs pour lesquelles nous inférons le non-aliasing et les optimisations rendues possibles par nos analyse

Analyses de mémoire à bas cout pour des compilateurs efficaces

This thesis was motivated by the emergence of massively parallel processing and supercomputingthat tend to make computer programming extremely performing. Speedup, the power consump-tion, and the efficiency of both software and hardware are nowadays the main concerns of theinformation systems community. Handling memory in a correct and efficient way is a step towardless complex and more performing programs and architectures. This thesis falls into this contextand contributes to memory analysis and compilation fields in both theoretical and experimentalaspects.Besides the deep study of the current state-of-the-art of memory analyses and their limitations,our theoretical results stand in designing new algorithms to recover part of the imprecisionthat published techniques still show. Among the present limitations, we focus our research onthe pointer arithmetic to disambiguate pointers within the same data structure. We develop ouranalyses in the abstract interpretation framework. The key idea behind this choice is correctness,and scalability: two requisite criteria for analyses to be embedded to the compiler construction.The first alias analysis we design is based on the range lattice of integer variables. Given a pair ofpointers defined from a common base pointer, they are disjoint if their offsets cannot have valuesthat intersect at runtime. The second pointer analysis we develop is inspired from the Pentagonabstract domain. We conclude that two pointers do not alias whenever we are able to build astrict relation between them, valid at program points where the two variables are simultaneouslyalive. In a third algorithm we design, we combine both the first and second analysis, and enhancethem with a coarse grained but efficient analysis to deal with non related pointers.We implement these analyses on top of the LLVM compiler. We experiment and evaluate theirperformance based on two metrics: the number of disambiguated pairs of pointers compared tocommon analyses of the compiler, and the optimizations further enabled thanks to the extraprecision they introduceLa rapidité, la consommation énergétique et l'efficacité des systèmes logiciels et matériels sont devenues les préoccupations majeures de la communauté informatique de nos jours. Gérer de manière correcte et efficace les problématiques mémoire est essentiel pour le développement des programmes de grande tailles sur des architectures de plus en plus complexes. Dans ce contexte, cette thèse contribue aux domaines de l'analyse mémoire et de la compilation tant sur les aspects théoriques que sur les aspects pratiques et expérimentaux. Outre l'étude approfondie de l'état de l'art des analyses mémoire et des différentes limitations qu'elles montrent, notre contribution réside dans la conception et l'évaluation de nouvelles analyses qui remédient au manque de précision des techniques publiées et implémentées. Nous nous sommes principalement attachés à améliorer l'analyse de pointeurs appartenant à une même structure de données, afin de lever une des limitations majeures des compilateurs actuels. Nous développons nos analyses dans le cadre général de l'interprétation abstraite « non dense ». Ce choix est motivé par les aspects de correction et d'efficacité : deux critères requis pour une intégration facile dans un compilateur. La première analyse que nous concevons est basée sur l'analyse d'intervalles des variables entières ; elle utilise le fait que deux pointeurs définis à l'aide d'un même pointeur de base n'aliasent pas si les valeurs possibles des décalages sont disjointes. La seconde analyse que nous développons est inspirée du domaine abstrait des Pentagones ; elle génère des relations d'ordre strict entre des paires de pointeurs comparables. Enfin, nous combinons et enrichissons les deux analyses précédentes dans un cadre plus général. Ces analyses ont été implémentées dans le compilateur LLVM. Nous expérimentons et évaluons leurs performances, et les comparons aux implémentations disponibles selon deux métriques : le nombre de paires de pointeurs pour lesquelles nous inférons le non-aliasing et les optimisations rendues possibles par nos analyse

Inorganic salts effect on wheat straw during steam explosion treatment

Wheat straw is an abundant low cost byproduct. Its use is usually limited in litter and cattle feed. In order to better valorize this lignocellulosic biomass in high added value products, a material preliminary fraction should be done. In this study, a steam explosion pretreatment was applied at different pressure 15 and 20 bar with a residence time of 2 min using different solvents (distilled water and salt water 35g/l NaCl). The objective is to investigate the effect of the operating parameters and salts on the extraction yield of different molecules and their degradation products. The results shows that sodium chloride enhanced the hemicellulose and cellulose removal compared to distilled water

Hydrothermal dehydration of D-glucose and D-xylose in deionized water

The industrial trend is moving toward biobased plateform molecule preparation using biobased-processes integrating into green chemistry discipline. These “building blocks” molecules are intermediate for the synthesis of value-added chemicals. 5-hydroxymethylfurfural (5-HMF) and 2-furfural are two plateform molecules derived from monosaccharides. In order to produce these furanic compounds, xylose and glucose conversion were conducted in hot deionized water, which represent the greenest solvent, at 211°C, 20 bars by means of batch-type reactor. A selected rang of times T1= 1min, T2=15 min , T3=30 min ,T4=45 min and T5 =60 min were investigated. Results shows that at 15 min, the best 5-hydroxymethyl furfural ( 5- HMF) yield is 18,52%, produced by glucose dehydration, then it recorded a stable rate . At the same time 2-furfural was produced from xylose with a yield of 26,71% and didn’t vary significantly over time. A 11, 09 % and 9,67 % yield of Lactic acid (LA) and Fromic Acid (FA) were obtained as a co-product from glucose dehydration and 5.53 % of LA was generated from xylose decomposition

New insights into the production of platform chemicals from biomass using deep eutectic solvents

Platform chemicals are versatile compounds produced from sustainable biomass resources using chemical and/or biological processes. These platform chemicals include C6-sugars, 5-hydroxymethylfurfural / 2-furfural, 2,5-furandicarboxylic acid, levulinic acid, xylitol, and others, that could be used for direct applications, as polymer building blocks or as derivatives for synthesizing commodity chemicals. Production of these platform chemicals through chemical approaches includes hydrothermal but also solvothermal methods or catalyzed reaction paths in organic (monophasic or biphasic) solvents systems. Driven by the quest of sustainability, ionic liquids have thus progressively emerged as strategic and tunable media for the production of these biobased platform molecules in high yields and selectivities. In particular also, deep eutectic solvents (DES) and natural deep eutectic solvents (NADES) were recently proposed as other competitive sustainable alternatives. These stable systems are defined as a particular mixture composition of two or more entities (including a hydrogen-bond acceptor and a hydrogen-bond donor) that becomes liquid at room temperature. Offering the possibility to perform reactions at low temperatures, DES (and NADES) were found as efficient "green" solvents for the production of an array of platform chemicals, minimizing the formation of side-products. The tunable acid character of these deep eutectic systems allows performing some specific reactions without the introduction of Lewis or Bronsted acids. That is particularly the case for the benchmark dehydration of C6 or C5-sugars into 5-hydroxymethylfurfural or 2-furfural (and their rehydration into levulinic acid). This contribution (that includes original results) aims thus to offer an exhaustive overview of the effectiveness of (natural) deep eutectic solvents as viable liquid systems for the production of top valuable platform compounds from renewable biomass.Low Carbon Footprint Materials - BIOMAT3_UL

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