Preparation of synthetic wood composites using ionic liquids (original) (raw)
Related papers
Ionic liquid—a future solvent for the enhanced uses of wood biomass
European Journal of Wood and …, 2012
Biomass refers to biological materials that can be used as fuel or for the production of chemicals. Globally, ever growing demand of energy and concerns for the environment have prompted researchers to develop convenient and efficient ways for converting wood biomass into valuable chemicals, bio-fuels and useful biomaterials. In this context, ionic liquid has the potential to play a major role. Ionic liquids, considered as green solvents, have been found capable of dissolving wood biomass, and the dissolution process can be enhanced in a number of ways, like heating, microwave treatment, addition of acids etc. The anionic part of ionic liquid plays an important role in this process coupled with hydrogen bond basicity (β) property of ionic liquid, which has a significant effect on wood biomass dissolution. This paper reviews the applications of ionic liquids for the dissolution, fractionation and regeneration of wood biomass. It is also related to the processing of cellulose and wood biomass, preparation of cellulose and wood biomass derivatives and composites.
Dissolution of Wood in Ionic Liquids
Journal of Agricultural and Food Chemistry, 2007
The present paper demonstrates that both hardwoods and softwoods are readily soluble in various imidazolium-based ionic liquids (ILs) under gentle conditions. More specifically, a variety of ionic liquids can only partially dissolve wood chips, whereas ionic liquids such as 1-butyl-3-methylimidazolium chloride and 1-allyl-3-methylimidazolium chloride have good solvating power for Norway spruce sawdust and Norway spruce and Southern pine thermomechanical pulp (TMP) fibers. Despite the fact that the obtained solutions were not fully clear, these ionic liquids provided solutions which permitted the complete acetylation of the wood. Alternatively, transparent amber solutions of wood could be obtained when the dissolution of the same lignocellulosic samples was attempted in 1-benzyl-3-methylimidazolium chloride. This realization was based on a designed augmented interaction of the aromatic character of the cation of the ionic liquid with the lignin in the wood. After dissolution, wood can be regenerated as an amorphous mixture of its original components. The cellulose of the regenerated wood can be efficiently digested to glucose by a cellulase enzymatic hydrolysis treatment. Furthermore, completely acetylated wood was found to be readily soluble in chloroform, allowing, for the first time, detailed proton nuclear magnetic resonance (NMR) spectra and NMR diffusion measurements to be made. It was thus demonstrated that the dissolution of wood in ionic liquids now offers a variety of new possibilities for its structural and macromolecular characterization, without the prior isolation of its individual components. Furthermore, considering the relatively wide solubility and compatibility of ionic liquids with many organic or inorganic functional chemicals or polymers, it is envisaged that this research could create a variety of new strategies for converting abundant woody biomass to valuable biofuels, chemicals, and novel functional composite biomaterials.
Opportunities with Wood Dissolved in Ionic Liquids
ACS Symposium Series, 2010
Biomass represents an abundant carbon-neutral renewable resource for the production of bioenergy and biomaterials. Shifting society's dependence away from petroleum to renewable biomass resources is generally regarded as an important contributor to building up a sustainable society and effective management of greenhouse gas emissions. An ionic liquids-based processing platform for the efficient transformation of lignocellulosic materials into new materials and value-added chemicals has been developed. We have demonstrated that woody lignocellulosic materials are soluble in certain ionic liquids. The first preparation of homogenous wood solutions not only extends the utilization of lignocellulosic materials from heterogenous to homogenous processing conditions, but also creates a variety of new strategies for converting our abundant lignocellulosic biomass to novel value-added bioproducts.
Dissolution and Separation of Wood Biopolymers Using Ionic Liquids
ChemBioEng Reviews, 2015
The majority of the world energy needs have been supplied from petroleum resources. While they are an efficient energy provider, their usage has caused pollution problems that warrant the need to search for efficient and cleaner energy sources. The ever growing global demand of energy and the concerns for the environment have prompted researchers to develop convenient and efficient ways to convert biomass into valuable chemicals, bio-fuels, and useful biomaterials. This review focuses on the applica-tion of ionic liquids for the dissolution of wood biomass and wood-derived compounds. The factors which affect the dissolution of cellulose and lignin in ionic liquids are described as well as the effects of ionic liquids on the physical properties of cellulose. The use of ionic liquids alone or in combination with other co-solvent systems which help in the fractionation of wood biomass are discussed. Additionally, the cost economic aspects of ionic liquid applications are highlighted.
Ionic liquids as media for biomass processing: opportunities and restrictions
The present study provides insight into the dissolution behavior of renewable materials in ionic liquids. Beech, spruce and rye straw were dissolved in 1-ethyl-3-methylimidazolium acetate as the ionic liquid of choice, which is currently one of the most frequently used cation-anion combinations among ionic liquids for biomaterial processing. The dissolution was followed by selective precipitation of cellulose, hemicelluloses, and lignin. The obtained lignin was analyzed with Curie-point pyrolysis gas chromatography/mass spectrometry (Cu-Py-GC/MS) and the separated cellulose/hemicellulose fractions with gel permeation chromatography (GPC). Time dependence of the dissolution process was studied on rye straw, eucalyptus kraft pulp and beech sulfite pulp. The results show a changing dissolution profile over time, which is due to progressing degradation of the cellulose in the ionic liquid.
Polymers, 2020
Ionic liquids have shown great potential in the last two decades as solvents, catalysts, reaction media, additives, lubricants, and in many applications such as electrochemical systems, hydrometallurgy, chromatography, CO2 capture, etc. As solvents, the unlimited combinations of cations and anions have given ionic liquids a remarkably wide range of solvation power covering a variety of organic and inorganic materials. Ionic liquids are also considered “green” solvents due to their negligible vapor pressure, which means no emission of volatile organic compounds. Due to these interesting properties, ionic liquids have been explored as promising solvents for the dissolution and fractionation of wood and cellulose for biofuel production, pulping, extraction of nanocellulose, and for processing all-wood and all-cellulose composites. This review describes, at first, the potential of ionic liquids and the impact of the cation/anion combination on their physiochemical properties and on thei...
Green Chemistry, 2007
The bulk of the cellulose currently employed by industry is isolated from wood through Kraft pulping, a process which traditionally involves a barrage of environmentally detrimental chemicals and is undeniably 'non-green.' In this report we present a simple and novel alternative approach for the processing of lignocellulosic materials that relies on their solubility in solvent systems based on the ionic liquid (IL) 1-n-butyl-3-methylimidazolium chloride ([C 4 mim]Cl). Dissolution profiles for woods of different hardness are presented, making emphasis on the direct analysis of the cellulosic material and lignin content in the resulting liquors by means of conventional 13 C NMR techniques. We also show that cellulose can be readily reconstituted from the IL-based wood liquors in fair yields by the addition of a variety of precipitating solvents. Spectroscopic and thermogravimetric studies indicate that the polysaccharide obtained in this manner is virtually free of lignin and hemicellulose and has characteristics that are comparable to those of pure cellulose samples subjected to similar processing conditions.
2010
Cellulose is one of the most abundant biological and renewable materials in the world. The application of cellulose is widely distributed among various industries such as fiber, paper, pharmaceutical, membrane, polymer and paint. However, the utilization of cellulose or cellulosic materials has not been developed entirely because of its poor solubility in common organic solvents. Ionic liquids (ILs) are relatively new family of solvents for dissolution of cellulose. They are organic salts contain only cations and anions with low melting temperature, which make them suitable for the solubilization of cellulose. Moreover, ILs are non-volatile, non-toxic, non-flammable and thermally and chemically stable. Cellulose dissolved in ILs can be regenerated with anti-solvents as water, ethanol and acetone. In this study, both the dissolution and regeneration of hardwood and softwood dissolving pulps with and from two ILs ([C mim + ]CH 3 COOand [C4mim + ]Cl-) were investigated. Furthermore, the impact of treating cellulose with ILs was also evaluated by using different analytical techniques, such as size exclusion chromatography (SEC), thermal gravimetric analysis (TGA) and scanning electron microscopy (SEM).