Hemicellulose-Based Hydrogels Present Status and Application Prospects: A Brief Review

Hu, Lisong; Du, Ming; Zhang, Jinping

doi:10.4236/ojf.2018.81002

Cited by 26 publications

(18 citation statements)

References 55 publications

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“…It also challenges the acid fractionation process, currently used in most second-generation ethanol biorefineries, since improved overall ethanol yields were obtained with mild alkaline fractionation followed by enzymatic saccharification [18] and it can reduce the need for expensive equipment to deal with corrosion and severe reaction conditions [17].Besides, lignin and hemicelluloses are extracted under their oligomeric form in alkaline media which represents alternative opportunities of valorization. Hemicelluloses under their polymeric form can form hydrogels thanks to their numerous properties such as adsorption capacity, mechanical strength, hydrophilicity, biodegradability, biocompatibility, transparency, low cost, and non-toxicity which find applications in various fields such as water depollution, food additives, food packaging, cosmetics and pharmaceuticals [19][20][21]. The use of hemicelluloses under their polymeric form is not commercially as advanced as their use under their monomeric form.Unlike hemicelluloses, all current commercial uses of lignin, except the burning and production of synthetic vanillin, take advantage of lignin's polymer and polyelectrolyte properties [22].…”

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“…Besides, lignin and hemicelluloses are extracted under their oligomeric form in alkaline media which represents alternative opportunities of valorization. Hemicelluloses under their polymeric form can form hydrogels thanks to their numerous properties such as adsorption capacity, mechanical strength, hydrophilicity, biodegradability, biocompatibility, transparency, low cost, and non-toxicity which find applications in various fields such as water depollution, food additives, food packaging, cosmetics and pharmaceuticals [19][20][21]. The use of hemicelluloses under their polymeric form is not commercially as advanced as their use under their monomeric form.…”

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Lignocellulosic Biomass Mild Alkaline Fractionation and Resulting Extract Purification Processes: Conditions, Yields, and Purities

2020

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Fractionation of lignocellulose is a fundamental step in the valorization of cellulose, hemicelluloses, and lignin to produce various sustainable fuels, materials and chemicals. Strong alkaline fractionation is one of the most applied processes since the paper industry has been using it for more than a century, and the mineral acid fractionation process is currently the most applied for the production of cellulosic ethanol. However, in the last decade, mild alkaline fractionation has been becoming increasingly widespread in the frame of cellulosic ethanol biorefineries. It leads to the solubilization of hemicelluloses and lignin at various extent depending on the conditions of the extraction, whereas the cellulose remains insoluble. Some studies showed that the cellulose saccharification and fermentation into ethanol gave higher yields than the mineral acid fractionation process. Besides, contrary to the acid fractionation process, the mild alkaline fractionation process does not hydrolyze the sugar polymers, which can be of interest for different applications. Lignocellulosic mild alkaline extracts contain hemicelluloses, lignin oligomers, phenolic monomers, acetic acid, and inorganic salts. In order to optimize the economic efficiency of the biorefineries using a mild alkaline fractionation process, the purification of the alkaline extract to valorize its different components is of major importance. This review details the conditions used for the mild alkaline fractionation process and the purification techniques that have been carried out on the obtained hydrolysates, with a focus on the yields and purities of the different compounds.Clean Technol. 2020, 2 92 (also known as Kraft) processes. These processes induce the dissociation of cellulose fibers from lignin and hemicelluloses by the cooking chemicals [8,9]. Kraft and soda processes rely on alkaline chemicals, the former being mainly used for wood hydrolysis, while the latter is commonly applied to non-wood biomass, such as bagasse, straw, grass or bamboo [9]. In both processes, lignin, low molecular weight hemicelluloses and other extractives from the wood are dissolved in what is called the black liquor [10]. The third process in the papermaking industry is the sulfite process, developed by Tilghman [11]. The wood chips are cooked in a mixture of sulfurous acid and bisulfide ions which dissolve lignin and hemicelluloses [12]. Sulfite pulps account for less than 10% of the total chemical pulp production [13].For decades, the black liquor was burnt to produce steam and electricity. The characterization, fractionation, and recovery of the compounds from black liquor in order to valorize them into materials and chemicals appeared only in the 1980s [14,15]. With the expansion of lignocellulosic biorefineries to produce other materials than paper -energy (liquid fuels like ethanol) and chemical intermediates -and the constraint of limiting the cost of the fractionation step, mild alkaline fractionation gained importance [16,17]. It also challenges the acid fra...

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Lignocellulosic Biomass Mild Alkaline Fractionation and Resulting Extract Purification Processes: Conditions, Yields, and Purities

2020

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“…Therefore, hemicellulose‐based hydrogels have been studied for various applications due to the merits of hemicelluloses (e.g., water solubility, functional groups, and branched structure). [ 45 ] For instance, the cyclic freezing–thawing technique has been employed to prepare hemicellulose/polyvinyl alcohol (PVA)/chitin composite hydrogels with high strength. Notably, the repeated cycles, polymer concentration, and reaction time of the freezing–thawing process affect the final properties of hydrogels.…”

Section: Synthesis Of Polysaccharide‐based Hydrogelsmentioning

confidence: 99%

Recent advances in polysaccharide‐based hydrogels for synthesis and applications

Lin

2021

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Hydrogels are three‐dimensional (3D) crosslinked hydrophilic polymer networks that have garnered tremendous interests in many fields, including water treatment, energy storage, and regenerative medicine. However, conventional synthetic polymer hydrogels have poor biocompatibility. In this context, polysaccharides, a class of renewable natural materials with biocompatible and biodegradable properties, have been utilized as building blocks to yield polysaccharide‐based hydrogels through physical and/or chemical crosslinking of polysaccharides via a variety of monomers or ions. These polysaccharide‐derived hydrogels exhibit peculiar physicochemical properties and excellent mechanical properties due to their unique structures and abundant functional groups. This review focuses on recent advances in synthesis and applications of polysaccharide‐based hydrogels by capitalizing on a set of biocompatible and biodegradable polysaccharides (i.e., cellulose, alginate, chitosan, and cyclodextrins [CDs]). First, we introduce the design and synthesis principles for crafting polysaccharide‐based hydrogels. Second, polysaccharide‐based hydrogels that are interconnected via various crosslinking strategies (e.g., physical crosslinking, chemical crosslinking, and double networking) are summarized. In particular, the introduction of noncovalent and/or dynamic covalent interactions imparts polysaccharide‐based hydrogels with a myriad of intriguing performances (e.g., stimuli–response and self‐recovery). Third, the diverse applications of polysaccharide‐based hydrogels in self‐healing, sensory, supercapacitor, battery, drug delivery, wound healing, tissues engineering, and bioimaging fields are discussed. Finally, the perspectives of polysaccharide‐based hydrogels that promote their future design to enable new functions and applications are outlined.

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“…Nevertheless, it has been investigated in applications like gels and films and was shown to be suitable as in emulsions and stabilisers. Several papers have an overview of the current state of the art on hemicellulose-based hydrogels (Hu et al, 2018), and in Konge et al (2018). In their research (Farhat et al, 2017) have used alkaline treatment for hemicellulose extraction from hardwood pulp and partly delignified switchgrass.…”

Section: Hemicellulose Applicationsmentioning

confidence: 99%

Lignocellulosic bio-refinery downstream products in future packaging applications

Karlovits¹

2020

Proceedings - The Tenth International Symposium GRID 2020

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The concept of efficient utilisation of renewable bio-based materials (biomass feedstock) is the driving force in the green transformation to a more sustainable and circular society. Biorefineries or biochemical platforms convert and utilise different sources of biomass into fuels and other beneficial derivates like fibres and other bio-based chemicals. These can be used as building blocks for many potentially useful applications. In this review, we shall describe the current state of the art and trends in the conversion of lignocellulosic feedstock into materials which can be primarily used in packaging applications. The three main constituents (cellulose, hemicellulose and lignin) are being re-engineered into new products with higher added value. The main goal of all these downstream products is that they do not compete with animal feed and food applications. The main downstream products of different kind of transformations are different natural fibres which can be further processed into micro or nano fibrillated state and used for a broad application of fields from ink, adhesive and packaging materials. Also, fibres and its derivates can be bonded successfully into bio-composites or fibre-based foams applications for the protective packaging applications. Hemicellulose, as a second most abundant component, has been researched for applications in adhesives and paper and paperboard coatings. Lignin which is currently utilised as an energy source for the paper industry, has been recently actively researched. Lignin-based biopolymers have a potential to be used in many different applications from additives in the barrier coatings on the packaging to active packaging and even as lignin-based foams. All these applications are currently in the development stages and cover niche market segments, but are expected to grow and to be used in future markets.

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Hemicellulose-Based Hydrogels Present Status and Application Prospects: A Brief Review

Cited by 26 publications

References 55 publications

Lignocellulosic Biomass Mild Alkaline Fractionation and Resulting Extract Purification Processes: Conditions, Yields, and Purities

Lignocellulosic Biomass Mild Alkaline Fractionation and Resulting Extract Purification Processes: Conditions, Yields, and Purities

Recent advances in polysaccharide‐based hydrogels for synthesis and applications

Lignocellulosic bio-refinery downstream products in future packaging applications

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