Ionic liquids as a tool for lignocellulosic biomass fractionation

Lignocellulosic biomass composes a diversity of feedstock raw materials representing an abundant and renewable carbon source. In majority lignocellulose is constituted by carbohydrate macromolecules, namely cellulose and hemicellulose, and by lignin, a polyphenilpropanoid macromolecule. Between these biomacromolecules, there are several covalent and non-covalent interactions defining an intricate, complex and rigid structure of lignocellulose. The deconstruction of the lignocellulosic biomass makes these fractions susceptible for easier transformation to large number of commodities including energy, chemicals and material within the concept of biorefinery. Generally, the biomass pre-treatment depends on the final goal in the biomass processing. The recalcitrance of lignocellulose materials is the main limitation of its processing once the inherent costs are excessively high for the conventional pre-treatments. Furthermore, none of the currently known processes is highly selective and efficient for the satisfactory and versatile use, thus, new methodologies are still studied broadly. The ionic liquid technology on biomass processing is relatively recent and first studies were focused on the lignocellulosic biomass dissolution in different ionic liquids (ILs). The dissolution in IL drives to the structural changes in the regenerated biomass by reduction of cellulose crystallinity and lignin content contrasting to the original biomass. These findings provided ILs as tools to perform biomass pre-treatment and the advantageous use of their specific properties over the conventional pre-treatment processes. This review shows the critical outlook on the study of biomass dissolution and changes occurred in the biomass during this process as well as on the influence of several crucial parameters that govern the dissolution and further pre-treatment process. The review of currently known methods of biomass fractionation in IL and aqueous-IL mixtures is also discussed here and perspectives regarding these topics are given as well

Green chemistry and the biorefinery concept

Green Chemistry and Biorefinery concepts are two approaches helping to develop new and more sustainable processes. The implementation of both methodologies impels to fossil-independent future with bioeconomy based on natural feedstock like biowaste and industrial by-products. The development of technologies for valorisation of these resources is a key role of society in the creation of sustainable and more environmentally friendly future

Integrated conversion of agroindustrial residue with high pressure CO2 within the biorefinery concept

Sustainable production of energy and other added-value products from biomass-derived polysaccharides is a key challenge of an efficient biorefinery facility. Most technologies for biomass processing are energy demanding and use significant amounts of chemicals and catalysts. The need to develop a process which is devoid of all these shortcomings associated with conventional processes is emphasized. A new approach is demonstrated for an integrated wheat straw biorefinery using a green technology, highpressure CO2–H2O, to produce oligosaccharides from hemicellulose fraction and to enhance the cellulose digestibility for the enzymatic hydrolysis. Over the range of reaction conditions (130, 215, 225 °C and 0 to 54 bar of CO2), CO2 adds value to the process by in situ formation of carbonic acid that leads to higher dissolution of hemicellulose into xylo-oligosaccharides and xylose and to the use of less energy in comparison with water-only technologies. Without an additional chemical catalyst, high-pressure CO2–H2O out performed hydrothermal reactions and gave much higher total sugars yield for wheat straw (as high as 84% in comparison with 67.4% with auto-hydrolysis at a 10 °C higher temperature). Apart from the results obtained for valorisation of hemicellulose fraction, both chemical and physical effects of CO2 coupled to enzymatic hydrolysis resulted in a glucan conversion to glucose yield of 82%, which consists of 26% improvement over those obtained during auto-hydrolysis. The influence of the high pressure reaction on the processed solid was examined by spectroscopic methods (namely Scanning Electron Microscopy and Fourier Transform Infrared Spectroscopy). The obtained results suggest that the high pressure CO2-based method is a very promising alternative technology allowing integrated biomass processing within the biorefinery concept

Green technologies in the valorization of agrofood wastes in the frame of the biorefinery concept

Food production results in the generation of residues at different step of the production chain. A great part of the residues is generated at the agricultural part of the process. Although some of these residues may have already an application as for example feed or bedding, however more energetically and economically efficient use is desirable. Especially that this kind of residues are low-cost bulky feedstock and renewable carbon source, which can be processed and valorised to produce fine chemicals and bio-based commodities fulfilling the requirement of biorefinery concept. However, considering the globally occurring changes, the valorisation of residues made in the frame of biorefinery concept must be done in the green fashion. This way the broadly understood sustainability and bio-based economy requirements can be satisfy. This work will show some examples of valorisation of food production chain residues using greener methods. The aim of this work is to demonstrate the diverse application methods of ionic liquids and high density fluids in direct integrated valorisation of biomass towards value-added chemicals

Carbon dioxide in biomass processing: contributions to the green biorefinery concept

The 21st century is witnessing a huge demand of fossil reserves coupled with a rapid reduction in readily and economically reachable oil feedstocks.The present energy demand is not fulfilled from fossil fuel sources, making the world exposed to geopolitical risk. Furthermore, concerns regarding the security of the supply chain and the environmental impacts have resulted in an ever-increasing shift of global energy policies to seek alternative technologies and sustainable sources of energy, materials, chemicals, and value-added products. Recently, the need for development of an economy based on renewable resources has been recognized by society, and diverse R&D activities have started to be funded to accomplish this aim. However, generation of bioproducts based on sustainable supply chains poses vast challenges for an eco-based economy.The simplest way to provide a supportable supply chain is through the employment of renewable biomass feedstocks, which is the only sustainable option to substitute for fossil fuel resources, as sources of organic compounds over a relatively short time scale and with limitless supply

Agro-food industry residues for biodiesel production: BIOFFA project

The aim of the project BIOFFA is to develop processes for the production of biofuels from residual raw-materials with high free fatty acid (FFA). In technological terms, two distinct approaches, leading to different final products, are being assessed: production of fatty acid methyl esters (FAME) – biodiesel, and hydrogenated oil – H-oil. Different residues available in Portugal, including poultry fat, cattle fat, olive pomace oil and used frying oils, were collected and characterised, and the objectives of the project will be considered to be met if it will be possible to produce mixtures of both biofuels (biodiesel + H-oil) similar to the nowadays commercially available formulas (biodiesel + petro-diesel) with the superior advantages of valorising residues and producing the overall mixture from biological materials

Simple and efficient furfural production from xylose in media containing 1-Butyl-3-Methylimidazolium hydrogen sulfate

The acidic 1-butyl-3-methylimidazolium hydrogen sulfate ([bmim][HSO4]) ionic liquid was explored as both a reaction medium and a catalyst in the furfural production from xylose. Preliminary experiments were carried out at 100–140 °C for 15–480 min in systems containing just xylose dissolved in [bmim][HSO4] in the absence of externally added catalysts. More than 95% xylose conversion was achieved when operating at 120 or 140 °C for 300 and 90 min, respectively; but just 36.7% of the initial xylose was converted to furfural. Operation in biphasic reaction systems (in the presence of toluene, methyl-isobutyl ketone or dioxane as extraction solvents) at 140 °C under selected conditions resulted in improved furfural production (73.8%, 80.3%, and 82.2% xylose conversion to furfural for the cited extraction solvents, respectively)

Insight into the high-pressure CO2 pre-treatment of sugarcane bagasse for a delivery of upgradable sugars

ABSTRACT: This work provides an insight into sugarcane bagasse pre-treatment carried out with greener and more sustainable CO2/H2O system. Temperatures and residence times at a fixed initial CO2 pressure were studied to verify their effects on pre-treatment efficiency with regard to the chemical composition of both water-soluble and water-insoluble fractions as well as to the susceptibility of the latter to enzymatic hydrolysis at high total solids. Also, trends in enzymatic hydrolysis were analysed in function of biomass crystallinity. This work provides an integrated approach in the analysis of upgradable sugars that are released as a result of pre-treatment and enzymatic hydrolysis. At optimal pre-treatment conditions, 17.2 g.L-1 sugars were released in the water-soluble fraction mainly as pentoses in monomeric and oligomeric forms. The enzymatic hydrolysis of solids produced at these pre-treatment conditions gave 76.8 g.L-1 glucose in the substrate hydrolysate. The overall sugar yield delivered in both pre-treatment and enzymatic hydrolysis was 73,9 mol%. These results were compared to the chemical effect of hydrothermal and/or physico-chemical effects of N-2-aided hydrothermal processes and showed that the greener processing of biomass pre-treatment with CO2 is advantageous for the integrated valorisation of industrial residues and delivery of upgradable sugars within the biorefinery concept.info:eu-repo/semantics/publishedVersio

Isospin effects on the energy of vanishing flow in heavy-ion collisions

Using the isospin-dependent quantum molecular dynamics model we study the isospin effects on the disappearance of flow for the reactions of $^{58}Ni$ + $^{58}Ni$ and $^{58}Fe$ +$^{58}Fe$ as a function of impact parameter. We found good agreement between our calculations and experimentally measured energy of vanishing flow at all colliding geometries. Our calculations reproduce the experimental data within 5%(10%) at central (peripheral) geometries