Microwave-assisted deep eutectic solvents/dimethyl sulfoxide system for efficient valorization of sugar bagasse waste into platform chemicals: A biorefinery approach for circular bioeconomy

Effective extraction of larch holocellulose with alkaline deep eutectic solvent and production of furan chemicals with the coordination of temperature-controlled polyoxometalates and metal salt in biphasic system

This study focused on extracting holocellulose from Changbai larch waste, which is rich in hexose and beneficial for furan chemicals production. Various alkaline deep eutectic solvents (DESs) was applied in the extraction of holocellulose. DES composed of lysine (Lys) and 2-aminoethanol (MEA) with strong alkalinity had a superior ability to remove lignin, and the purity of holocellulose could reach 82.7 %. Consequently, a double-acid system formed by a temperature-controlled polyoxometalates catalyst (ChnH3-nPW12, n = 1, 2, 3,) prepared by choline chloride (ChCl) and phosphotungstic acid (H3PW12O40) and different metal salts were used in the hydrolysis of holocellulose to 5-hydroxymethylfurfural (HMF) and 2-furaldehyde (FF) in a two-phase system of water and organic solvent. The yields of HMF and FF reached 43.5 % and 78.2 %, respectively, when ChH2PW12 and AlCl3 were employed under the conditions of 10 mL water/methyl isobutyl ketone (MIBK) (1:9, V:V), 9 h, and 150 °C. ChH2PW12is easy to recycle and can be used up to 5 times. This study offers a novel strategy to retain as much hemicellulose as possible to achieve holocellulose by alkaline DESs, and the one-pot process by the coordination of polyoxometalates and metal salt provides a simultaneous production of high-value furan chemicals from larch waste.

Raw biowaste conversion to high-value compounds for food, cosmetic and pharmaceutical industries

Biowaste valorisation into high-value compounds is one of the main challenges of green chemistry, as chemicals produced from biological sources are identified as key substances in the development of a low-carbon and circular bioeconomy in connection with the transition from fossil to renewable feedstocks. The review summarizes the production of high-value products such as glucose-based chemicals, phenolic compounds and volatile-fatty acids prepared from biomass waste. Biowaste pretreatment methods such as milling, filtration and extraction followed by current non-catalytic methods such as microwave or ultrasound extraction and catalytic methods for the production value-added compounds in the presence of various catalyst types in conventional, nano or enzyme form are listed with a focus on value-added chemicals applied in the food, cosmetic and pharmaceutical industries. The economic feasibility, technical aspects and concept of the biorefinery are briefly mentioned, emphasizing the necessity of life cycle assessment for each bioproduct and technological process. Finally, it provides a future perspective and makes recommendations for potential research strategies, recognizing the importance of utilizing biomass waste for the production of useful compounds as an attractive and environmentally friendly approach whose development should be encouraged. The utilization of biowaste for high-value chemicals production shows high potential, however, there are still many challenges to be resolved throughout the entire production chain, reflecting technological, economic, ecological, sociological and long-term issues.

One-pot, microwave (MW)-assisted production of furfural from almond-, oil-, and wine-derived co-products through biorefinery-based approaches

This work outlines the first microwave (MW)-assisted protocol for the production of biofuel precursor furfural (FF) from the raw agricultural waste almond hull (AH), olive stone (OS), and the winemaking-derived grape stalk (GS), grape marc (GM) and exhausted grape marc (EGM) through a one-pot synthesis process. To enhance the overall yield, a catalytic process was firstly developed from xylose, major constituent of hemicellulose present in lignocellulosic biomass. This method afforded FF with 100 % selectivity, yielding over 85 % in isolated product when using H2SO4, as opposed to a 37 % yield with AlCl3·6H2O, at 150 °C in only 10 min. For both catalysts, the developed methodology was further validated, proving adaptable and efficient in producing the targeted FF from the aforementioned lignocellulosic raw materials. More specifically, the employment of AlCl3·6H2O resulted in the highest selectivity (up to 89 % from GM) and FF yield (42 % and 39 % molar from OS and AH, respectively), maintaining notable selectivity for the latter (61 and 48 % from AH and OS). At this regard, and considering the environmental factor of sustainability, it is important to point out the role of AlCl3·6H2O in contrast to H2SO4, thus mitigating detrimental substances. This study provides an important management of agricultural waste through sustainable practises for the development of potential bio-based chemicals, aligning with Green Chemistry and process intensification principles.

Co-production of 2,5-dihydroxymethylfuran and furfuralcohol from sugarcane bagasse via chemobiocatalytic approach in a sustainable system

2,5-Dihydroxymethylfuran and furfuryl alcohol serve as versatile building-blocks in pharmaceuticals, polymers, and value-added intermediates. To develop an efficient and sustainable method for their production from biomass, a combined approach using deep eutectic solvent Citric acid:Betaine (CTA:BT) for bagasse catalysis and recombinant E. coli SCFD23 for bioreduction of bagasse-derived 5-hydroxymethylfurfural and furfural was devised. Bagasse was effectively transformed into 5-hydroxymethylfurfural (48 mM) and furfural (14 mM) in CTA:BT (8 wt%)-water at 170 °C for 30 min. Bioreduction of 5-hydroxymethylfurfural and furfural by SCFD23 cell co-expressing formate dehydrogenase and NAD(P)H-dependent aldehyde reductase (SsCR) yielded 2,5-dihydroxymethylfuran (90.0 % yield) and furfuryl alcohol (99.0 % yield) in 6 h, using biomass-derived formic acid, xylose and glucose as co-substrates. Molecular docking confirmed the stable binding and reductase activity of SsCR with the biomass-derived 5-hydroxymethylfurfural and furfural. An efficient and eco-friendly chemobiological approach was applied for co-production of 2,5-dihydroxymethylfuran and furfuryl alcohol from biomass in one-pot two-step reaction.

Highly effective synthesis of 5-hydroxymethylfurfural from lignocellulosic biomass over a green and one-pot reaction in biphasic system

In this study, different types of lignocellulosic biomas were used as substrates for the conversion to 5-HMF via biphasic reaction system that is composed of a reaction phase (aqueous phase) and an extraction phase (organic phase) under the catalysis of various metal salts. Deep eutectic solvents (DESs), ionic liquid [BMIM]Cl, aqueous choline chloride, aqueous betaine hydrochloride, and ethylamine hydrochloride were used as the reaction phase in the combination of dimethyl sulfoxide (DMSO) as organic solvents. The highest yields of 5-HMF obtained from pineapple stems in reactions with DES were 40.98%, 37.26%, and 23.44% for ChCl:Lac, ChCl:OA, and EaCl:Lac, respectively. Moreover, the combination of dimethyl sulfoxide, betaine hydrochloride aqueous solution, and AlCl3·6H2O with the pineapple stem conversion system resulted in a maximum yield of 61.04% ± 0.55% of 5-HMF. This study also demonstrated that AlCl3·6H2O and betaine hydrochloride could be effectively reused four times, which indicates a green and effective process.

Food waste biorefinery towards circular economy in Australia

Staggering amounts of food waste are produced in Australia, and this review provides food waste based biorefinery opportunities in moving towards a circular economy in Australia. The current food waste scenario in Australia including an overview of primary food waste sources, government regulation, and current management practices is presented. The major food waste streams include fruit and vegetable (waste from wine grapes, citrus, apple, potato, and tomato), nuts (almond processing waste), seafood (Fish waste), dairy whey, sugarcane bagasse, and household and businesses. The composition of these waste streams indicated their potential for use in biorefineries to produce value-added products via various pathways combining direct extraction and biological and thermochemical conversion. Finally, the efforts made in Australia to utilize food waste as a resource, as well as the challenges and future directions to promote the development of concrete and commercially viable technologies for food waste biorefinery, are described.

Study on the resourceful reuse in SBS-modified asphalt of waste bagasse fibers based on green modification with tannic acid and FeOOH

Hydrophobic modification of bagasse fibers (BFs) through a green approach can promote its reuse in asphalt and enhance the utilization value of agricultural and forestry waste in road engineering. In contrast to traditional chemical modification, this study reports a new method for the hydrophobic modification of BFs using tannic acid (TA) and the in situ growth of FeOOH nanoparticles (NPs), resulting in FeOOH-TA-BF, which is used to prepare styrene-butadiene styrene (SBS)-modified asphalt. The experimental results show that the surface roughness, specific surface area, thermal stability, and hydrophobicity of the modified BF are improved, which is beneficial for enhancing the interface compatibility with asphalt. Specifically, compared with BF/SBS-modified asphalt, FeOOH-TA-BF/SBS-modified asphalt exhibits 39.21% and 23.26% increase in the elastic modulus G' and viscous modulus G″, respectively, at the optimal dosage of 2.5%, corresponding to 6.15-fold and 7.13-fold increase in the fatigue life at 2.5% and 5.0% strain respectively, and 22.0% improvement in shear resistance performance. In the meantime, 2.5-fold enhancement of the storage stability. Therefore, this study provides a simple, environmentally friendly, and efficient hydrophobic modification method that is of great significance for promoting the resource utilization of solid waste BF.