Use of Ionic Liquids and Deep Eutectic Solvents in Polysaccharides Dissolution and Extraction Processes towards Sustainable Biomass Valorization

Polysaccharides from fruit and vegetable wastes and their food applications: A review

Fruit and vegetables are a great source of nutrients and have numerous health benefits. The fruit and vegetable industry produces enormous amounts of waste such as peels, seeds, and stems. The amount of this waste production has increased, causing economic and environmental problems. Fruit and vegetable wastes (FVWs) have the potential to be recovered and used to produce high-value goods. Furthermore, FVWs have a large variety and quantity of polysaccharides, which makes them interesting to study for potential industrial use. Currently, the investigations on extracting polysaccharides from FVWs and examining how they affect human health are increasing. The present review focuses on polysaccharides from FVWs such as starch, pectin, cellulose, and inulin, and their various biological activities such as anti-inflammatory, anti-tumor, anti-diabetic, antioxidant, and antimicrobial. Additionally, applications as packaging material, gelling agent, emulsifier, prebiotic, and fat replacer of polysaccharides from FVWs in the food industry have been viewed in detail. As a result, FVWs can be reused as the source of polysaccharides, reducing environmental pollution and enabling sustainable green development. Further investigation of the biological activities of polysaccharides from FVWs on human health is of great importance for using these polysaccharides in food applications.

Valorization of Seafood Waste for Food Packaging Development

Packaging plays a crucial role in protecting food by providing excellent mechanical properties as well as effectively blocking water vapor, oxygen, oil, and other contaminants. The low degradation of widely used petroleum-based plastics leads to environmental pollution and poses health risks. This has drawn interest in renewable biopolymers as sustainable alternatives. The seafood industry generates significant waste that is rich in bioactive substances like chitin, chitosan, gelatins, and alginate, which can replace synthetic polymers in food packaging. Although biopolymers offer biodegradability, biocompatibility, and non-toxicity, their films often lack mechanical and barrier properties compared with synthetic polymer films. This comprehensive review discusses the chemical structure, characteristics, and extraction methods of biopolymers derived from seafood waste and their usage in the packaging area as reinforcement or base materials to guide researchers toward successful plastics replacement and commercialization. Our review highlights recent advancements in improving the thermal durability, mechanical strength, and barrier properties of seafood waste-derived packaging, explores the mechanisms behind these improvements, and briefly mentions the antimicrobial activities and mechanisms gained from these biopolymers. In addition, the remaining challenges and future directions for using seafood waste-derived biopolymers for packaging are discussed. This review aims to guide ongoing efforts to develop seafood waste-derived biopolymer films that can ultimately replace traditional plastic packaging.

Deep eutectic solvent (DES)-assisted extraction of pectin from Ficus carica Linn. peel: optimization, partial structure characterization, functional and antioxidant activities

BACKGROUND

The pectin from Ficus carica Linn. (fig) peels is a valuable and recyclable constituent that may bring huge economic benefits. To maximize the utilization of this resource, deep eutectic solvent (DES)-assisted extraction was applied to extract pectin from fig peels, and the extraction process was optimized with response surface methodology.

RESULTS

When DES (choline chloride/oxalic acid = 1:1) content was 168.1 g kg-1, extraction temperature was 79.8 °C, liquid-solid ratio was 23.3 mL g-1, and extraction time was 120 min, the maximum yield of 239.6 g kg-1 was obtained, which was almost twice the extraction of hot water. DES-extracted fig peel pectin (D-FP) exhibited better nature than hot water-extracted fig peel pectin (W-FP) in terms of uronic acid content, particle size distribution, and solubility, but lower molecular weight and esterification degree. D-FP and W-FP had similar infrared spectra and thermodynamic peaks but differed in monosaccharide compositions. D-FP also showed good antioxidant capacities and exhibited better functional activities than W-FP.

CONCLUSION

These results indicated that D-FP was of promising quality being utilized in food or medical industries and the optimal DES-assisted extraction method might be applied as a sustainable process for the effective extraction of bioactive pectin from fig peels with the excellence of low equipment requirements and simple operation. © 2024 Society of Chemical Industry.

Alternative processes to produce chitin, chitosan, and their oligomers

Sustainable recovery of chitin and its derivatives from shellfish waste will be achieved when the industrial production of these polymers is achieved with a high control of their molecular structure, low costs, and acceptable levels of pollution. Therefore, the conventional chemical method for obtaining these biopolymers needs to be replaced or optimized. The goal of the present review is to ascertain what alternative methods are viable for the industrial-scale production of chitin, chitosan, and their oligomers. Therefore, a detailed review of recent literature was undertaken, focusing on the advantages and disadvantages of each method. The analysis of the existing data allows suggesting that combining conventional, biological, and alternative methods is the most efficient strategy to achieve sustainable production, preventing negative impacts and allowing for the recovery of high added-value compounds from shellfish waste. In conclusion, a new process for obtaining chitinous materials is suggested, with the potential of reducing the consumption of reagents, energy, and water by at least 1/10, 1/4, and 1/3 part with respect to the conventional process, respectively.

Update on Chitin and Chitosan from Insects: Sources, Production, Characterization, and Biomedical Applications

Insects, renowned for their abundant and renewable biomass, stand at the forefront of biomimicry-inspired research and offer promising alternatives for chitin and chitosan production considering mounting environmental concerns and the inherent limitations of conventional sources. This comprehensive review provides a meticulous exploration of the current state of insect-derived chitin and chitosan, focusing on their sources, production methods, characterization, physical and chemical properties, and emerging biomedical applications. Abundant insect sources of chitin and chitosan, from the Lepidoptera, Coleoptera, Orthoptera, Hymenoptera, Diptera, Hemiptera, Dictyoptera, Odonata, and Ephemeroptera orders, were comprehensively summarized. A variety of characterization techniques, including spectroscopy, chromatography, and microscopy, were used to reveal their physical and chemical properties like molecular weight, degree of deacetylation, and crystallinity, laying a solid foundation for their wide application, especially for the biomimetic design process. The examination of insect-derived chitin and chitosan extends into a wide realm of biomedical applications, highlighting their unique advantages in wound healing, tissue engineering, drug delivery, and antimicrobial therapies. Their intrinsic biocompatibility and antimicrobial properties position them as promising candidates for innovative solutions in diverse medical interventions.

Cellulose-Based Hydrogels for Wastewater Treatment: A Focus on Metal Ions Removal

The rapid worldwide industrial growth in recent years has made water contamination by heavy metals a problem that requires an immediate solution. Several strategies have been proposed for the decontamination of wastewater in terms of heavy metal ions. Among these, methods utilizing adsorbent materials are preferred due to their cost-effectiveness, simplicity, effectiveness, and scalability for treating large volumes of contaminated water. In this context, heavy metal removal by hydrogels based on naturally occurring polymers is an attractive approach for industrial wastewater remediation as they offer significant advantages, such as an optimal safety profile, good biodegradability, and simple and low-cost procedures for their preparation. Hydrogels have the ability to absorb significant volumes of water, allowing for the effective removal of the dissolved pollutants. Furthermore, they can undergo surface chemical modifications which can further improve their ability to retain different environmental pollutants. This review aims to summarize recent advances in the application of hydrogels in the treatment of heavy metal-contaminated wastewater, particularly focusing on hydrogels based on cellulose and cellulose derivatives. The reported studies highlight how the adsorption properties of these materials can be widely modified, with a wide range of adsorption capacity for different heavy metal ions varying between 2.3 and 2240 mg/g. The possibility of developing new hydrogels with improved sorption performances is also discussed in the review, with the aim of improving their effective application in real scenarios, indicating future directions in the field.

Polysaccharides extraction from Ganoderma lucidum using a ternary deep eutectic solvents of choline chloride/guaiacol/lactic acid

In this study, a purposefully formulated ternary deep eutectic solvents (DESs), consisting of choline chloride, guaiacol, and lactic acid in a molar ratio of 1:1:1, was synthesized for the extraction of polysaccharides from Ganoderma lucidum. The physicochemical properties of the synthesized DESs, including viscosity, density, pH, and hydrogen bonds, were comprehensively examined. Verification of the formation of the ternary DESs was accomplished through Fourier transform infrared and Nuclear magnetic resonance spectroscopies. Subsequently, response surface methodology was applied to optimize crucial parameters for polysaccharide extraction using DESs, resulting in a maximal extraction yield of 94.72 mg/g under the optimized conditions. Cyclic experiments demonstrated the commendable cyclic stability of the DESs, with a recovery rate exceeding 88 %. Furthermore, experiments on monosaccharide composition, molecular weight, and antioxidant activity of the isolated polysaccharides were conducted. Density functional theory was employed to gain insights into the molecular mechanism of polysaccharide extraction by DESs. The findings revealed a triple hydrogen bond interaction and a high binding energy (65.29 kcal/mol) between the DESs and glucose, highlighting their significant contribution to the high extraction effectiveness. This molecular-level understanding underscores the inherent superiority of DESs in the polysaccharide extraction processes, providing valuable insights for future applications in this field.

Maximizing crustaceans (shrimp, crab, and lobster) by-products value for optimum valorization practices: A comparative review of their active ingredients, extraction, bioprocesses and applications

BACKGROUND

The processing of the three major crustaceans (shrimp, lobster, and crab) is associated with inevitable by-products, high waste disposal costs, environmental and human health issues, loss of multiple biomaterials (chitin, protein hydrolysates, lipids, astaxanthin and minerals). Nowadays, these bioresources are underutilized owing to the lack of effective and standardized technologies to convert these materials into valued industrial forms.

AIM OF REVIEW

This review aims to provide a holistic overview of the various bioactive ingredients and applications within major crustaceans by-products. This review aims to compare various extraction methods in crustaceans by-products, which will aid identify a more workable platform to minimize waste disposal and maximize its value for best valorization practices.

KEY SCIENTIFIC CONCEPTS OF REVIEW

The fully integrated applications (agriculture, food, cosmetics, pharmaceuticals, paper industries, etc.) of multiple biomaterials from crustaceans by-products are presented. The pros and cons of the various extraction methods, including chemical (acid and alkali), bioprocesses (enzymatic or fermentation), physical (microwave, ultrasound, hot water and carbonic acid process), solvent (ionic liquids, deep eutectic solvents, EDTA) and electrochemistry are detailed. The rapid development of corresponding biotechnological attempts present a simple, fast, effective, clean, and controllable bioprocess for the comprehensive utilization of crustacean waste that has yet to be applied at an industrial level. One feasible way for best valorization practices is to combine innovative extraction techniques with industrially applicable technologies to efficiently recover these valuable components.

The European Polysaccharide Network of Excellence (EPNOE) research roadmap 2040: Advanced strategies for exploiting the vast potential of polysaccharides as renewable bioresources

Polysaccharides are among the most abundant bioresources on earth and consequently need to play a pivotal role when addressing existential scientific challenges like climate change and the shift from fossil-based to sustainable biobased materials. The Research Roadmap 2040 of the European Polysaccharide Network of Excellence (EPNOE) provides an expert's view on how future research and development strategies need to evolve to fully exploit the vast potential of polysaccharides as renewable bioresources. It is addressed to academic researchers, companies, as well as policymakers and covers five strategic areas that are of great importance in the context of polysaccharide related research: (I) Materials & Engineering, (II) Food & Nutrition, (III) Biomedical Applications, (IV) Chemistry, Biology & Physics, and (V) Skills & Education. Each section summarizes the state of research, identifies challenges that are currently faced, project achievements and developments that are expected in the upcoming 20 years, and finally provides outlines on how future research activities need to evolve.

Dissolution of Metals (Cu, Fe, Pb, and Zn) from Different Metal-Bearing Species (Sulfides, Oxides, and Sulfates) Using Three Deep Eutectic Solvents Based on Choline Chloride

Nowadays, deep eutectic solvents (DESs) are seen as environmentally friendly alternatives with the potential to replace traditional solvents used in hydrometallurgical processes. Although DESs have been successfully applied in the recovery of metals from secondary sources, there is still innovative potential regarding DESs as green leaching agents applied in the recovery of metals from primary sources like polysulfide ores. This study aimed to evaluate the characteristics of DESs as solvents for some of the main metals present in typical polymetallic concentrates, like Cu, Fe, Pb, and Zn. Thus, three DESs based on choline chloride (ChCl) were prepared: 1:2 ChCl-urea (also known as reline), 1:2 ChCl-ethylene glycol (also known as ethaline), and 1:2 ChCl-glycerol (also known as glyceline). Then, dissolution tests at 30 °C were carried out with these DESs and different metal- (Cu, Fe, Pb, and Zn) bearing compounds (sulfates, oxides, and sulfides). According to the dissolution tests, it was found that the solubility of the studied metals (expressed as g of metal per Kg of DES) was dictated by the bearing species, reaching the dissolution of the metals from sulfates with values as high as two orders of magnitude higher than the metal solubility values for metal oxides and sulfides.

Enhanced dissolution of galactomannan and highly efficient selenium functionalization using ionic liquids with dual roles as solvents and catalysts

Galactomannan stands as a promising heteropolysaccharide, yet its randomly distributed non-linear structures and high molecular mass remain a huge challenge in solubilization and wide range of chemical modifications. This work develops a task specific approach for efficient dissolve of galactomannan in ionic liquids (ILs) by destructing and reconstructing intermolecular/intramolecular hydrogen bonds of galactomannan. Combining density functional theory calculations and experimental results, a reasonable mechanism of polysaccharide dissolution is proposed that the hydrogen bond networks of polysaccharide are broken, thus the hydroxyl groups are fully exposed and activated to facilitate functionalization. In view of the enhanced solubilization, an excellent effect in selenylation of galactomannan is notably improved by employing ILs with dual roles as solvents and catalysts. Typically, the introduction of -SO3H in ILs (SFILs) effectively enhances the protonation ability of selenium donor and thus further improves the functionalization efficiency. Furthermore, a surprising finding is observed that selenium content and average molecular mass of functionalized polysaccharide can be manipulated by the anions-cations synergistic effect which is highly dependent on SFILs acidity strength. This work proposed an integrated and promising strategy for improving the solubilization and functionalization manipulating by ILs, showing a great referential value for the widespread application in polysaccharide-rich resources.

How does ultrasound-assisted ionic liquid treatment affect protein? A comprehensive review of their potential mechanisms, safety evaluation, and physicochemical and functional properties

Proteins are essential to human health with enormous food applications. Despite their advantages, plant and animal proteins often exhibit limited molecular flexibility and poor solubility due to hydrogen bonds, hydrophobic interactions, and ionic interactions within their molecular structures. Thus, there is an urgent need to modify the rigid structure of proteins to enhance their stability and functional properties. Ultrasound-assisted ionic liquid (UA-IL) treatment for developing compound modification and producing proteins with excellent functional properties has received interest. However, no review specifically addresses the interactions between UA-ILs and proteins. Hence, this review focused on recent research advancements concerning the effects and potential reaction mechanisms of UA-ILs on the physicochemical properties (including particle size; primary, secondary, and tertiary structure; and surface morphology) as well as the functionality (such as solubility, emulsifying properties, and foaming ability) of proteins. Moreover, the safety evaluation of modified proteins was also discussed from various perspectives, such as acute and chronic toxicity, genotoxicity, cytotoxicity, and environmental and microbial toxicity. This review demonstrated that UA-IL treatment-induced protein structural changes significantly impact the functional characteristics of proteins. This treatment approach efficiently promotes protein structure stretching and spatial rearrangement through cavitation, thermal effects, and ionic interactions. As a result, the functional properties of modified proteins exhibited an obvious enhancement, thereby bringing more opportunities to utilize modified protein products in the food industry. Potential future directions for protein modification using UA-ILs were also proposed.

Exploitation of lignocellulosic-based biomass biorefinery: A critical review of renewable bioresource, sustainability and economic views

Urbanization has driven the demand for fossil fuels, however, the overly exploited resource has caused severe damage on environmental pollution. Biorefining using abundant lignocellulosic biomass is an emerging strategy to replace traditional fossil fuels. Value-added lignin biomass reduces the waste pollution in the environment and provides a green path of conversion to obtain renewable resources. The technology is designed to produce biofuels, biomaterials and value-added products from lignocellulosic biomass. In the biorefinery process, the pretreatment step is required to reduce the recalcitrant structure of lignocellulose biomass and improve the enzymatic digestion. There is still a gap in the full and deep understanding of the biorefinery process including the pretreatment process, thus it is necessary to provide optimized and adapted biorefinery solutions to cope with the conversion process in different biorefineries to further provide efficiency in industrial applications. Current research progress on value-added applications of lignocellulosic biomass still stagnates at the biofuel phase, and there is a lack of comprehensive discussion of emerging potential applications. This review article explores the advantages, disadvantages and properties of pretreatment methods including physical, chemical, physico-chemical and biological pretreatment methods. Value-added bioproducts produced from lignocellulosic biomass were comprehensively evaluated in terms of encompassing biochemical products , cosmetics, pharmaceuticals, potent functional materials from cellulose and lignin, waste management alternatives, multifunctional carbon materials and eco-friendly products. This review article critically identifies research-related to sustainability of lignocellulosic biomass to promote the development of green chemistry and to facilitate the refinement of high-value, environmentally-friendly materials. In addition, to align commercialized practice of lignocellulosic biomass application towards the 21st century, this paper provides a comprehensive analysis of lignocellulosic biomass biorefining and the utilization of biorefinery green technologies is further analyzed as being considered sustainable, including having potential benefits in terms of environmental, economic and social impacts. This facilitates sustainability options for biorefinery processes by providing policy makers with intuitive evaluation and guidance.

Adsorptive Membranes Incorporating Ionic Liquids (ILs), Deep Eutectic Solvents (DESs) or Graphene Oxide (GO) for Metal Salts Extraction from Aqueous Feed

Water scarcity is a significant concern, particularly in arid regions, due to the rapid growth in population, industrialization, and climate change. Seawater desalination has emerged as a conventional and reliable solution for obtaining potable water. However, conventional membrane-based seawater desalination has drawbacks, such as high energy consumption resulting from a high-pressure requirement, as well as operational challenges like membrane fouling and high costs. To overcome these limitations, it is crucial to enhance the performance of membranes by increasing their efficiency, selectivity, and reducing energy consumption and footprint. Adsorptive membranes, which integrate adsorption and membrane technologies, offer a promising approach to address the drawbacks of standalone membranes. By incorporating specific materials into the membrane matrix, composite membranes have demonstrated improved permeability, selectivity, and reduced pressure requirements, all while maintaining effective pollutant rejection. Researchers have explored different adsorbents, including emerging materials such as ionic liquids (ILs), deep eutectic solvents (DESs), and graphene oxide (GO), for embedding into membranes and utilizing them in various applications. This paper aims to discuss the existing challenges in the desalination process and focus on how these materials can help overcome these challenges. It will also provide a comprehensive review of studies that have reported the successful incorporation of ILs, DESs, and GO into membranes to fabricate adsorptive membranes for desalination. Additionally, the paper will highlight both the current and anticipated challenges in this field, as well as present prospects, and provide recommendations for further advancements.

Deep Eutectic Solvents Based on Carboxylic Acids and Glycerol or Propylene Glycol as Green Media for Extraction of Bioactive Substances from Chamaenerion angustifolium (L.) Scop

Chamaenerion angustifolium (L.) Scop. is one of the promising sources of biologically active compounds and a valuable industrial crop. Recently, green extraction methods have become more topical. One of them is the application of deep eutectic solvents (DESs). The aim of this work was the synthesis and characterization of DES consisting of glycerin or propylene glycol with malonic, malic, or citric acids, evaluation of their effectiveness for extracting useful substances from C. angustifolium during ultrasonic extraction, description of kinetics, and optimization of extraction conditions. DESs were obtained and characterized with FTIR. Their effectiveness in the process of ultrasound-assisted extraction of biologically active substances from C. angustifolium was estimated. Kinetic parameters describing the dependence of the total phenolic, flavonoids, and antioxidant content, free radical scavenging of DPPH, and concentration of flavonoid aglycons (myricetin, quercetin, and kaempferol) via time in the range of 5-60 min at 45 °C are obtained. Extraction conditions were optimized with the Box-Behnken design of experiment. The results of this work make it possible to expand the scope of DES applications and serve the development of C. angustifolium processing methods.

A New Method of Extracting Polygonatum sibiricum Polysaccharide with Antioxidant Function: Ultrasound-Assisted Extraction-Deep Eutectic Solvents Method

Polygonatum sibiricum Polysaccharide (PsP) with antioxidant function is the main active component of Polygonatum sibiricum (P.sibiricum). The currently poor extraction yield and extraction methods of PsP cannot meet the application of that in food industrial production. In this research, an ultrasound-assisted extraction-deep eutectic solvents (UAE-DESs) method, which has never been used in the PsP industry, was first used to extract PsP. The extraction conditions were optimized by the response surface method (RSM). Both the extraction yield and antioxidant function were simultaneously considered during the optimization process. The indicators of PsP's level and antioxidant activity in vitro were used to present the extraction yield of the UAE-DESs method, the purity, and the antioxidant effect of PsP. Under the optimal conditions, which included a liquid-solid ratio of 26:1 (mL:g), extraction temperature of 80 °C, ultrasonic time of 51 min, and ultrasonic power of 82 W, the PsP extraction yield could reach (43.61 ± 0.09)%, which was obviously higher than single DESs (33.81%) and UAE (5.83%), respectively, and the PsP appeared favorably antioxidant function. This research proposed an efficient extraction method for PsP, filled the basic research gap, and further improved the development of PsP as a dietary supplement with antioxidant function in the food industry.

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

Nowadays, 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.

Turning Food Protein Waste into Sustainable Technologies

For each kilogram of food protein wasted, between 15 and 750 kg of CO₂ end up in the atmosphere. With this alarming carbon footprint, food protein waste not only contributes to climate change but also significantly impacts other environmental boundaries, such as nitrogen and phosphorus cycles, global freshwater use, change in land composition, chemical pollution, and biodiversity loss. This contrasts sharply with both the high nutritional value of proteins, as well as their unique chemical and physical versatility, which enable their use in new materials and innovative technologies. In this review, we discuss how food protein waste can be efficiently valorized not only by reintroduction into the food chain supply but also as a template for the development of sustainable technologies by allowing it to exit the food-value chain, thus alleviating some of the most urgent global challenges. We showcase three technologies of immediate significance and environmental impact: biodegradable plastics, water purification, and renewable energy. We discuss, by carefully reviewing the current state of the art, how proteins extracted from food waste can be valorized into key players to facilitate these technologies. We furthermore support analysis of the extant literature by original life cycle assessment (LCA) examples run ad hoc on both plant and animal waste proteins in the context of the technologies considered, and against realistic benchmarks, to quantitatively demonstrate their efficacy and potential. We finally conclude the review with an outlook on how such a comprehensive management of food protein waste is anticipated to transform its carbon footprint from positive to negative and, more generally, have a favorable impact on several other important planetary boundaries.

Advances in green solvents for production of polysaccharide-based packaging films: Insights of ionic liquids and deep eutectic solvents

The problems with plastic materials and the good film-forming properties of polysaccharides motivated research in the development of polysaccharide-based films. In the last 5 years, there has been an explosion of publications on using green solvents, including ionic liquids (ILs), and deep eutectic solvents (DESs) as candidates to substitute the conventional solvents/plasticizers for preparations of desired polysaccharide-based films. This review summarizes related properties and recovery of ILs and DESs, a series of green preparation strategies (including pretreatment solvents/reaction media, ILs/DESs as components, extraction solvents of bioactive compounds added into films), and inherent properties of polysaccharide-based films with/without ILs and DESs. Major reported advantages of these new solvents are high dissolving capacity of certain ILs/DESs for polysaccharides (i.e., up to 30 wt% for cellulose) and better plasticizing ability than traditional plasticizers. In addition, they frequently display intrinsic antioxidant and antibacterial activities that facilitate ILs/DESs applications in the processing of polysaccharide-based films (especially active food packaging films). ILs/DESs in the film could also be further recycled by water or ethanol/methanol treatment followed by drying/evaporation. One particularly promising approach is to use bioactive cholinium-based ILs and DESs with good safety and plasticizing ability to improve the functional properties of prepared films. Whole extracts by ILs/DESs from various byproducts can also be directly used in films without separation/polishing of compounds from the extracting agents. Scaling-up, including costs and environmental footprint, as well as the safety and applications in real foods of polysaccharide-based film with ILs/DESs (extracts) deserves more studies.

Treatment of Pulp Black Liquor with an Ionic Liquid: Modeling and Optimization by Using Response Surface Methodology and Central Composite Design

In this study, selective extraction towards ionic liquid trihexyltetradecylphosphonium chloride ([P₆₆₆₁₄ ]Cl) of lignin residues, polysaccharides and organic acids present in black liquor (BL), the main principal wastewater of pulping industry was studied. With the objective of finding optimized conditions allowing to extract lignin residues while polysaccharides and organic acids remain in aqueous solution, a design of experiments approach based on a response surface methodology was used. Three continuous factors, namely initial pH varying from 9 to 13.5, dilution of BL varying from 5 to 20 and volumetric ratio of black liquor vs. ionic liquid R_V ., varying from 1 to 19, were investigated. Concentration of lignin residues, polysaccharides and organic acids were measured using Folin-Ciocalteu method, the anthrone method and HPLC, respectively. Results showed that a multi-response optimization led to the extraction of 84.8 % of lignin residues, 66.0 % of polysaccharides, and no extraction of OA under optimised conditions.

Separation of natural compounds using eutectic solvent-based biphasic systems and centrifugal partition chromatography

A study on the formation of ternary biphasic systems composed of heptane, 1-butanol or ethyl acetate and type III or type V deep eutectic solvents based on levulinic acid and choline chloride or thymol was carried. Binodal curves and densities and phase compositions of phases in equilibrium for seven systems are reported. The partition coefficients of six natural compounds, namely quercetin, apigenin, coumarin, β-ionone, retinol, and α-tocopherol, in these systems were measured. Results show that the influence of choline chloride on the partition coefficients is more significant in systems with 1-butanol or ethyl acetate than previously reported for ethanol, and that the separation of natural compounds is worst when using DES containing thymol instead of choline chloride. Based on these partition coefficients, one system composed of heptane, 1-butanol and the DES choline chloride:levulinic acid at molar ratio 1:3 was selected to be applied in centrifugal partition chromatography, and the results obtained confirmed that it allows a good separation of apigenin, coumarin, β-ionone and α-tocopherol.

Characterization of Thermoplastic Starch Plasticized with Ternary Urea-Polyols Deep Eutectic Solvent with Two Selected Fillers: Microcrystalline Cellulose and Montmorillonite

The aim of the study was to prepare and characterize composite materials based on thermoplastic starch (TPS)/deep eutectic solvent (DES). Potato starch was plasticized with ternary DES: urea:glycerol:sorbitol and modified with the selected fillers: microcrystalline cellulose and sodium montmorillonite. Films were prepared via twin-screw extrusion and thermocompression of the extrudates. Then, the physicochemical properties of the TPS films were examined. The ternary DES effectively plasticized the polysaccharide leading to a highly amorphous structure of the TPS (confirmed via mechanical tests, DMTA and XRD analyses). An investigation of the behavior in water (swelling and dissolution degree) and water vapor transmission rate of the films was determined. The introduction of the two types of fillers resulted in higher tensile strength and better barrier properties of the composite TPS films. However, montmorillonite addition exhibited a higher impact than microcrystalline cellulose. Moreover, a cone calorimetry analysis of the TPS materials revealed that they showed better fire-retardant properties than TPS plasticized with a conventional plasticizer (glycerol).

Chitin and its derivatives: Functional biopolymers for developing bioproducts for sustainable agriculture-A reality?

Chitinous materials (chitin and its derivatives) are obtained from renewable sources, mainly shellfish waste, having a great potential for the development of bioproducts as alternatives to synthetic agrochemicals. Recent studies have provided evidence that the use of these biopolymers can help control postharvest diseases, increase the content of nutrients available to plants, and elicit positive metabolic changes that lead to higher plant resistance against pathogens. However, agrochemicals are still widely and intensively used in agriculture. This perspective addresses the gap in knowledge and innovation to make bioproducts based on chitinous materials more competitive in the market. It also provides the readers with background to understand why these products are scarcely used and the aspects that need to be considered to increase their use. Finally, information on the development and commercialization of agricultural bioproducts containing chitin or its derivatives in the Chilean market is also provided.

Chitin and chitin-based biomaterials: A review of advances in processing and food applications

Chitin is the most abundant natural amino polysaccharide, showing various practical applications owing to its functional properties. However, there are barriers in the development due to the difficulty of chitin extraction and purification, regarding its high crystallinity and low solubility. In recent years, some novel technologies such as microbial fermentation, ionic liquid, electrochemical extraction have emerged for the green extraction of chitin from new sources. Furthermore, nanotechnology, dissolution systems and chemical modification were applied to develop a variety of chitin-based biomaterials. Remarkably, chitin was used in delivering active ingredients and developing functional foods for weight loss, lipid reduction, gastrointestinal health, and anti-aging. Moreover, the application of chitin-based materials was expanded into medicine, energy and the environment. This review outlined the emerging extraction methods and processing routes of different chitin sources and advances in applying chitin-based materials. We aimed to provide some direction for the multi-disciplinary production and application of chitin.

Nanocellulose-Based Polymer Composites Functionalized with New Gemini Ionic Liquids

The manuscript discusses the application of dimeric imidazolium ionic liquids with an aliphatic linker of different lengths, constituting a new class of compounds called gemini, for the modification of renewable materials. This innovative functionalization with the use of ionic liquids made it possible to obtain polymer composite nanomaterials with renewable fillers, which will reduce the consumption of petroleum-based raw materials and also be directly related to the reduction of energy intensity. Renewable filler in the form of nanocellulose modified with ionic liquids, as well as polymer composites with such filler obtained by extrusion and injection molding techniques, were subjected to detailed characterization using techniques like: X-ray diffraction (XRD), Fourier transform spectroscopy (FTIR), dispersion studies (DLS), morphological analysis (SEM), differential scanning calorimetry (DSC), hot-stage polarized light microscopy and characterization of mechanical properties. The use of innovative dimeric ionic liquids proved to be an effective method to carry out efficient functionalization of cellulose. This provided a stable space structure between polysaccharide particles, limiting aggregate formation. It was shown that chemical modification with ionic liquids has a significant effect on the nucleation activity of cellulose fillers and the formation of the supermolecular structure of the polymer matrix, which consequently allowed to obtain polymer composites with excellent strength characteristics and increased flexibility, which will allow to increase their application potential. Innovative ionic liquids have contributed to obtaining green nanomaterials with excellent functional properties, which have not been described in the literature so far.

Chitin, Chitosan, and Nanochitin: Extraction, Synthesis, and Applications

Crustacean shells are a sustainable source of chitin. Extracting chitin from crustacean shells is ongoing research, much of which is devoted to devising a sustainable process that yields high-quality chitin with minimal waste. Chemical and biological methods have been used extensively for this purpose; more recently, methods based on ionic liquids and deep eutectic solvents have been explored. Extracted chitin can be converted into chitosan or nanochitin. Once chitin is obtained and modified into the desired form, it can be used in a wide array of applications, including as a filler material, in adsorbents, and as a component in biomaterials, among others. Describing the extraction of chitin, synthesis of chitosan and nanochitin, and applications of these materials is the aim of this review. The first section of this review summarizes and compares common chitin extraction methods, highlighting the benefits and shortcomings of each, followed by descriptions of methods to convert chitin into chitosan and nanochitin. The second section of this review discusses some of the wide range of applications of chitin and its derivatives.

An integrated deep eutectic solvent-ionic liquid-metal catalyst system for lignin and 5-hydroxymethylfurfural production from lignocellulosic biomass: Technoeconomic analysis

There is an increasing interest in deep eutectic solvent (DES) and ionic liquid (IL) for lignin and 5-hydroxymethylfurfural (HMF) production from lignocellulosic biomass, but their economic costs raise great concerns. In this study, the effects of DES (ZnCl₂-lactic acid)/IL([EMIM]Cl)/metal catalysts (CuCl₂-CrCl₂) recycling time, acetone/water washing volume, HMF yield, and production capacity on total capital investment, annual operating cost, and net present value (NPV) of the refinery were elucidated. Results showed that annual operating cost was highly associated with DES/IL/metal catalysts recycling time as it determined raw materials cost. The HMF MSP of $16453/MT for the base case (ZnCl₂/lactic acid recycling 5 times, acetone/water washing 5 volumes, CuCl₂-CrCl₂-[EMIM]Cl recycling 10 times, HMF yield of 55%, and production capacity of 100 MT/h) was achieved with an IRR of 10%. Sensitivity analysis identified the unit costs of lactic acid and [EMIM]Cl as the dominant contributors to the HMF MSP.

Deep eutectic solvents: Recent advances in fabrication approaches and pharmaceutical applications

Deep eutectic solvents (DESs) have received increasing attention in the past decade owing to their distinguished properties including biocompatibility, tunability, thermal and chemical stability. Particularly, DESs have joined forces in pharmaceutical industry, not only to efficiently separate actives from natural products, but also to dramatically increase solubility and permeability of drugs, both are critical for the drug absorption and efficacy. As a result, lately DESs have been extensively and practically adopted as versatile drug delivery systems for different routes such as nasal, transdermal and oral administration with enhanced bioavailability. This review summarizes the emerging progress of DESs by introducing applied fabrication approaches with advantages and limitations thereof, and by highlighting the pharmaceutical applications of DESs.

Chitosan: Sources, Processing and Modification Techniques

Chitosan, a copolymer of glucosamine and N-acetyl glucosamine, is derived from chitin. Chitin is found in cell walls of crustaceans, fungi, insects and in some algae, microorganisms, and some invertebrate animals. Chitosan is emerging as a very important raw material for the synthesis of a wide range of products used for food, medical, pharmaceutical, health care, agriculture, industry, and environmental pollution protection. This review, in line with the focus of this special issue, provides the reader with (1) an overview on different sources of chitin, (2) advances in techniques used to extract chitin and converting it into chitosan, (3) the importance of the inherent characteristics of the chitosan from different sources that makes them suitable for specific applications and, finally, (4) briefly summarizes ways of tailoring chitosan for specific applications. The review also presents the influence of the degree of acetylation (DA) and degree of deacetylation (DDA), molecular weight (M_w) on the physicochemical and biological properties of chitosan, acid-base behavior, biodegradability, solubility, reactivity, among many other properties that determine processability and suitability for specific applications. This is intended to help guide researchers select the right chitosan raw material for their specific applications.

Screening ionic liquids for dissolving hemicellulose by COSMO-RS based on the selective model

The utilization of biomass resources has attracted more and more attention due to the consumption of non-renewable resources. Compared with cellulose and lignin, hemicellulose has been less studied. Some ionic liquids (ILs) have been proved to be excellent solvents for lignocellulosic pretreatment. However, screening of more efficient ILs is difficult due to numerous possible ILs. Computational chemistry has been proved effective in solvent screening, but a precise model is indispensable. In this work, we focused on building several appropriate models and selected the most suitable one. According to the structure of hemicellulose, six hemicellulose models were constructed and the mid-dimer of the xylan chain hemicellulose (MDXC) model was proved to be the best compared with the reported experimental results. Based on the MDXC model, 1368 ILs were screened to evaluate their ability to dissolve hemicellulose by Conductor-like Screening Model for Real Solvents (COSMO-RS). The activity coefficient (γ), excess enthalpy (H^E), and σ-profile indicated that the hydrogen-bond (H-bond) played a vital role in the dissolution of hemicellulose. Anions played a more critical role than cations, where small anions with H-bond acceptor groups could enhance the molecular interactions with hemicellulose. This work provided a thermodynamic understanding of hemicellulose and IL solvent systems. It highlights the importance of building appropriate solute models, which may be necessary to predict of the other thermodynamic properties in the future.

High-performance delignification of invasive tree species wood with ionic liquid and deep eutectic solvent for the production of cellulose-based polyelectrolytes

An efficient and eco-friendly process for lignocellulosic biomass fractionation is essential for the production of high value-added bioproducts from biomass. The present work aimed to obtain cellulose-rich materials from the wood of an invasive tree species (Acacia dealbata) using an appropriate choice of ionic liquids (ILs) and deep eutectic solvents (DESs), and of the processing conditions, for the subsequent production of cationic wood-based polyelectrolytes. In the pretreatment step, the 1-butyl-3-methylimidazolium methyl sulfate (IL) + H₂O and choline chloride + imidazole (DES) systems demonstrated a remarkable ability to remove lignin from acacia, reaching up to 92.4 and 90.2% of delignification, respectively. However, the DES pretreatment revealed to be more selective for lignin removal with lower cellulose losses (less than 15%) than the IL treatment (up to 30%) and less cellulose depolymerization. The hemicellulose was also removed but in a lesser extent with the DES treatment. Both systems could provide treated materials with a very high cellulose content (≥89%). Afterwards, cationic polyelectrolytes having a considerable content of quaternary ammonium groups (up to 3.6 mmol g⁻¹) were obtained directly from the IL- and DES-pretreated woods. The treated woods, when used as raw materials for cationization reaction, allow to synthesize water-soluble polyelectrolytes with potential to be applied in wastewater treatment, pharmaceutical or cosmetic products.

Two cellulose-rich materials, with 6–7% of lignin, obtained from A. dealbata pretreatment with an ionic liquid or a deep eutectic solvent were used to produce cationic polyelectrolytes by a two-step reaction with sodium periodate and Girard’s reagent T.

Strengthening Cellulose Nanopaper via Deep Eutectic Solvent and Ultrasound-Induced Surface Disordering of Nanofibers

The route for the preparation of cellulose nanofiber dispersions from bacterial cellulose using ethylene glycol- or glycerol-based deep eutectic solvents (DES) is demonstrated. Choline chloride was used as a hydrogen bond acceptor and the effect of the combined influence of DES treatment and ultrasound on the thermal and mechanical properties of bacterial cellulose nanofibers (BC-NFs) is demonstrated. It was found that the maximal Young’s modulus (9.2 GPa) is achieved for samples prepared using a combination of ethylene glycol-based DES and ultrasound treatment. Samples prepared with glycerol-based DES combined with ultrasound exhibit the maximal strength (132 MPa). Results on the mechanical properties are discussed based on the structural investigations that were performed using FTIR, Raman, WAXD, SEM and AFM measurements, as well as the determination of the degree of polymerization and the density of BC-NF packing during drying with the formation of paper. We propose that the disordering of the BC-NF surface structure along with the preservation of high crystallinity bulk are the key factors leading to the improved mechanical and thermal characteristics of prepared BC-NF-based papers.

Natural Polymers-Based Materials: A Contribution to a Greener Future

Natural polymers have emerged as promising candidates for the sustainable development of materials in areas ranging from food packaging and biomedicine to energy storage and electronics. In tandem, there is a growing interest in the design of advanced materials devised from naturally abundant and renewable feedstocks, in alignment with the principles of Green Chemistry and the 2030 Agenda for Sustainable Development. This review aims to highlight some examples of the research efforts conducted at the Research Team BioPol4fun, Innovation in BioPolymer-based Functional Materials and Bioactive Compounds, from the Portuguese Associate Laboratory CICECO–Aveiro Institute of Materials at the University of Aveiro, regarding the exploitation of natural polymers (and derivatives thereof) for the development of distinct sustainable biobased materials. In particular, focus will be given to the use of polysaccharides (cellulose, chitosan, pullulan, hyaluronic acid, fucoidan, alginate, and agar) and proteins (lysozyme and gelatin) for the assembly of composites, coatings, films, membranes, patches, nanosystems, and microneedles using environmentally friendly strategies, and to address their main domains of application.

Development of cellulose-based polymeric structures using dual functional ionic liquids

Carboxylate ionic liquids (ILs) combining benzethonium (BE) and didecyldimethylammonium (DDA) as cations have been explored to be used for the first time as dual functional solvents for microcrystalline cellulose (MCC) dissolution and, subsequently development of polymeric structures. Considering that some ILs can remain in the polymeric structures after phase inversion, these ILs can offer advantages such as antibacterial/antimicrobial response and ability to disrupt H-bonds. In this context, all tested ILs have been able to dissolve MCC up to a concentration of 4% (w/w), resulting in different polymeric structures, such as gel-like or films, depending on the type of IL and the ratio between MCC and IL. Furthermore, FTIR spectroscopy showed that some IL remains in the polymeric structures, which can enhance their application in the biomedical field.

Production of rayon fibres from cellulosic pulps: State of the art and current developments

The increasing demand for cellulosic fibres is continuously driven by the growing earth population and requirements of the textile industry. The annual cotton production of ca. 25 million tons is no longer enough to meet the market demands. This market gap of cellulosic fibres is progressively filled by regenerated cellulosic fibres derived from the dissolving pulp. The conventional industrial process of viscose production is far from being environmentally friendly due to the use of hazardous reagents. Alternatively, new trends in the production of regenerated fibres are related to the direct dissolution of cellulose in appropriate environmentally sound recyclable solvents, allowing high quality rayon fibres. This article reviews the sources of dissolving pulps used for the production of viscose and its quality parameters related to the performance of viscose production. The prospective cellulose regeneration processes, both commercialized and under development, are reviewed regarding current and future developments in the area.

Robust superbase-based emerging solvents for highly efficient dissolution of cellulose

The development of robust solvent systems for cellulose dissolution is of significant importance for cellulose utilization and transformation. Herein, six kinds of novel superbase-based solvents were designed by a combination of 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) with pyridine N-oxide (PyO) or 2-picoline-N-oxide (PiO) for dissolution of cellulose. It was observed that the prepared superbase-based solvents (denoted as DBN-PyO-x and DBN-PiO-4) could efficiently dissolve cellulose at mild temperatures (<80 °C). The chemical structure of the prepared superbase-based solvents and the molar ratio of the components significantly affected the solubility of cellulose, and DBN-PyO-4 showed the best performance with a cellulose solubility of 14.1 wt% 70 °C. The systematic study revealed that the good performance of the prepared superbase-based solvents on cellulose dissolution resulted from the synergistic effect of their ability to form hydrogen bonds and their polarizability.

Lignocellulosic biomass pretreatment by deep eutectic solvents on lignin extraction and saccharification enhancement: A review

Biomass recalcitrance hinders efficient utilization of lignocellulosic biomass, making pretreatment process a crucial step for successful biorefinery process. Pretreatment processes have been developed for processing biomass, while technical obstacles including intensive energy requirement, high operational cost, equipment corrosions resulted from currently applied techniques promote the development of new pretreatment process for biomass. The deep eutectic solvent (DES) has been recognized as a promising solvent for biomass pretreatment, although the DES application toward biomass is still in its nascent stage. This review summarized the current researches using DES for biomass pretreatment, focusing particularly on lignin extraction and saccharification enhancement of lignocellulosic biomass. The mechanisms for biomass fractionation using DES as agents are introduced. Prospect and challenge were outlined.

Spherical Cellulose Micro and Nanoparticles: A Review of Recent Developments and Applications

Cellulose, the most abundant natural polymer, is a versatile polysaccharide that is being exploited to manufacture innovative blends, composites, and hybrid materials in the form of membranes, films, coatings, hydrogels, and foams, as well as particles at the micro and nano scales. The application fields of cellulose micro and nanoparticles run the gamut from medicine, biology, and environment to electronics and energy. In fact, the number of studies dealing with sphere-shaped micro and nanoparticles based exclusively on cellulose (or its derivatives) or cellulose in combination with other molecules and macromolecules has been steadily increasing in the last five years. Hence, there is a clear need for an up-to-date narrative that gathers the latest advances on this research topic. So, the aim of this review is to portray some of the most recent and relevant developments on the use of cellulose to produce spherical micro- and nano-sized particles. An attempt was made to illustrate the present state of affairs in terms of the go-to strategies (e.g., emulsification processes, nanoprecipitation, microfluidics, and other assembly approaches) for the generation of sphere-shaped particles of cellulose and derivatives thereof. A concise description of the application fields of these cellulose-based spherical micro and nanoparticles is also presented.