Bio-based Solvents Research Articles

Recovery of β-carotene and astaxanthin from Phaffia rhodozyma biomass using aqueous solutions of cholinium-based ionic liquids

The red yeast Phaffia rhodozyma is a natural source of high-added value carotenoids such as β-carotene and astaxanthin, widely used in the cosmeceutical, chemical, feed/food and pharmaceutical industries. This yeast is characterized by a rigid cell wall mainly composed of biopolymers, being required an appropriate design of downstream processing to recovery these intracellular carotenoids. In this sense, a biocompatible alternative for the selective recovery of β-carotene and astaxanthin from P. rhodozyma cells by using ionic liquids (ILs) was proposed. The performance of different cholinium-based ILs to permeabilize the cell wall and recovery intracellular carotenoids from P. rhodozyma wet biomass was evaluated and the operational conditions were optimized. The recovery yields of β-carotene and astaxanthin increased with the increment of alkyl chain length of the anion (cf., increase of relative hydrophobicity of ILs), being cholinium octanoate [Ch][Oct] the most efficient (50 wt% in water, 45 °C and 60 min). The stability of carotenoids in ILs as well as the mechanisms behind the recoveries have also been investigated. Afterwards, it was developed for the best IL solution an integrative platform for the recycling of the solvents (up to three successive cycles without any make up) and recovery of β-carotene and astaxanthin using bio-based solvents. The results demonstrate the efficiency of cholinium-based ILs for the recovery of β-carotene and astaxanthin (≈ 40% w/w) from P. rhodozyma in one-step extraction, reinforcing the aptitude of ILs for the recovery of intracellular biomolecules from microbial-based biomass.

Dihydrolevoglucosenone as a bio-based catalytic solvent for efficient reductive-transformation of CO2 with amines into formamides and benzothiazoles

• Bio-based solvent dihydrolevoglucosenone was used for conversion of CO 2 with amine. • For the first time, dihydrolevoglucosenone was used for both solvent and catalyst. • The transformation yields of N -methylformanilide are > 94% at 80 °C and 2 MPa. • It is applicable to at least 11 amines and at least 7 aminothiophenols. • It activated the N–H and Si-H bond by solvent effect, thus promoting the reaction. Transformation of CO 2 as the C1 resource to produce value-added chemicals is of great importance to decrease CO 2 emission. In this context, development of green catalytic systems, especially those derived from renewable resources, is highly attractive to make the processes of converting CO 2 more sustainable, which has gained significant interest. In this work, cellulose-derived dihydrolevoglucosenone (DLGO, Cyrene™) was employed as a renewable catalytic solvent to convert CO 2 . DLGO was highly efficient for reductive conversion of CO 2 with amines using PhSiH 3 as the reductant, and various corresponding formamides could be selectively synthesized. Reaction kinetics analysis suggested that DLGO-based catalytic system possessed a higher reaction rate constant and lower apparent activation energy than both GVL and CH 3 CN-based catalytic systems. Furthermore, systematic studies revealed that DLGO with high polarity had strong ability to activate the N–H bond in amines and the Si-H bond in PhSiH 3 by the solvent effect ( i.e. , solvation and polarization), thereby making the catalytic system be highly efficient. This developed biomass-based catalytic system could be expanded to synthesize benzothiazoles from the reductive conversion of CO 2 with aminothiophenols using PhSiH 3 as the reductant. Notably, the DLGO-based system combined CO 2 transformation and biomass utilization, affording it possessing more values of practical applications.

Improved Production of 5-Hydroxymethylfurfural in Acidic Deep Eutectic Solvents Using Microwave-Assisted Reactions.

Hydroxymethylfurfural (5-HMF) is a key platform chemical, essential for the production of other chemicals, as well as fuels. Despite its importance, the production methods applied so far still lack in sustainability. In this work, acidic deep eutectic solvents (DES), acting both as solvent and catalyst, were studied for the conversion of fructose into 5-HMF using microwave-assisted reactions. These solvents were screened and optimized by varying the hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA). The bio-based solvent γ-valerolactone (GVL) was also applied as additive, leading to a boost in 5-HMF yield. Then, a response surface methodology was applied to further optimize operating conditions, such as reaction time, temperature and wt.% of added GVL. The highest 5-HMF yield attained, after optimization, was 82.4% at 130 °C, in 4 min of reaction time and with the addition of 10 wt.% of GVL. Moreover, a process for 5-HMF recovery and DES reuse was developed through the use of the bio-based solvent 2-methyltetrahydrofuran (2-Me-THF), allowing at least three cycles of 5-HMF production with minimal yield losses, while maintaining the purity of the isolated 5-HMF and the efficacy of the reaction media.

Biofuels from microalgae biomass: A review of conversion processes and procedures

• Key areas for improvement in microalgae conversion include the nature of catalysts been utilized. Bio-based catalysts should be preferred due to high cost of synthetic catalysts. Methodical limitations such as high equipment cost for process scale-up can prevent research from advancing as it could. • Promising microalgae conversion processes which could be progressed are the use of bio-based solvents and supercritical fluids for biodiesel production, hydrothermal liquefaction for biogas production, microwave-induced pyrolysis for syngas production, and ultrasound/microwave enhanced extraction for bio-oil production. • For future developments, the use of the promising conversion techniques would probably gain the interest of more researchers than at present, considering the merits of same. In other words, more research is expected to evolve in coming years. Achieving the EU 2030 vision of a 15% minimum amount of biofuels utilized in the road transportation require more research on biofuel production from biomass feedstock. To this end, this review study examines the use of green, deep eutectic solvents and direct transesterification approaches for biomass conversion to biofuels. Next, biogas production from anaerobic co-digestion of microalgae biomass is presented. Lastly, the effect of operating conditions, as well as advantages and limitations of several biomass conversion techniques are outlined. Of note, this study presents promising microalgae conversion processes which could be progressed are the use of bio-based solvents and supercritical fluids for biodiesel production, hydrothermal liquefaction for biogas production, microwave-induced pyrolysis for syngas production, and ultrasound/microwave enhanced extraction for bio-oil production. These are based on the possibility of high yield and process economics. We have also enumerated knowledge gaps needed to propel future studies.

L-menthol and thymol eutectic mixture as a bio-based solvent for the “one-pot” synthesis of well-defined amphiphilic block copolymers by ATRP

A bio-based eutectic mixture (EM), composed of L-menthol and thymol was used, for the first time, as solvent for the atom transfer radical polymerization (ATRP) of hydrophobic monomers (methyl acrylate (MA), methyl methacrylate (MMA), 2-(dimethylamino) ethyl methacrylate (DMAEMA), glycidyl methacrylate (GMA)) and hydrophilic monomers (2-hydroxyethyl acrylate (HEA), hydroxyethyl methacrylate (HEMA) and poly(ethylene glycol) methyl ether acrylate (OEOA)). Well-defined homopolymers (1.02 <Ð < 1.47) were obtained using only 225 ppm of copper catalyst and a monomer/EM ratio (v/v) of 0.75. As a proof-of-concept, this new polymerization system allowed the preparation of well-defined amphiphilic block copolymers (ABs) of PMA-b-PHEA-Br, PMA-b-POEOA-Br and PDAMEMA-b-PHEA-Br by “one-pot” supplemental activator and reducing agent (SARA) ATRP, as well as a PMA-b-PHEA-b-PBA-Br triblock copolymer, after chain extension of a PMA-b-PHEA-Br diblock copolymer. The use of a unique solvent system opens a new route for the easy synthesis of ABs, with conditions that can be applied in large scale production.

Valorization of spent coffee grounds by 2-methyloxolane as bio-based solvent extraction. Viable pathway towards bioeconomy for lipids and biomaterials

This study attempts to shed light on the efficacy of the solvent 2-methyloxolane (2-MeOx) as an alternative for hexane in defatting spent coffee grounds (SCG). Higher lipid yields were obtained with the bio-based solvent dry 2-MeOx (13.67%) and water-saturated 2-MeOx (15.84%) compared to hexane oil yield, which is of petroleum origin and is a known neurotoxin. Palmitic acid and linoleic acid were the principal fatty acids identified. The fatty acid profile of coffee oils obtained with hexane, dry 2-MeOx and aqueous 2-MeOx were similar. Lipid hydrolysis was observed in oils extracted with 2-MeOx, which warrants further investigation. The residual caffeine content in the defatted SCG was highest when hexane was used highlighting better solubility of methylxanthine compounds in the solvent 2-MeOx.

Using Biobased Solvents for the Extraction of Phenolic Compounds from Kiwifruit Industry Waste

Using Biobased Solvents for the Extraction of Phenolic Compounds from Kiwifruit Industry Waste

Dihydrolevoglucosenone (Cyrene™) as a versatile biobased solvent for lignin fractionation, processing, and chemistry

Cyrene is a promising and versatile solvent for lignin fractionation, processing and chemistry, for more sustainable processes.

Efficient pretreatment using dimethyl isosorbide as a biobased solvent for potential complete biomass valorization

Efficient pretreatment under mild conditions (120 °C, 60 min) using biobased dimethyl isosorbide for potential complete biomass valorization.

An integrated approach for sustainable valorization of winery wastewater using bio-based solvents for recovery of natural antioxidants

The presence of bioactive compounds in winery waste streams represents a great opportunity to revalue these effluents that constitute a challenging environmental and economic problem. The main objective of this research is to develop an efficient and environmentally friendly liquid-liquid extraction process for the recovery of phenolic antioxidants from winery wastewater. Two bio-based solvents, 2-methyltetrahydrofuran (2-MeTHF) and cyclopentyl methyl ether (CPME), were evaluated as potential extractants along with ethyl acetate (EA) as benchmark organic solvent. Extraction efficiencies were maximized by testing several operation factors such as stirring time, solvent to feed ratio, concentration and alcohol effect. Subsequently, the extracted phenolic compounds were quantified by spectrophotometric (using the Folin-Ciocalteu assay, the flavonoid-aluminum chloride complexation assay and the DPPH free radical assay) and chromatographic (HPLC-DAD) methods. Overall, 2-MeTHF showed the highest extraction efficiency of target antioxidants, yielding up to 96.46% for gallic acid, 87.44% for protocatechuic acid, 80.82% for 4-hydroxybenzoic acid, 92.24% for caffeic acid, 75.18% for vanillic acid and 38.19% for syringic acid. In the interest of full sustainability, the isolation of the phenolic compounds as a solid fraction from the extraction solvent was efficiently accomplished, while the recyclability of 2-MeTHF was successfully demonstrated.

Exergy, economic and environmental analysis of an integrated pressure-swing reactive distillation process for the isobutyl acetate production via methyl acetate transesterification

As a greener bio-based solvent, isobutyl acetate (ISBAC) was widely applied in biorefineries around value-added production for environmental protection and ecological safety. The convention production of ISBAC, which was obtained by the reaction of alcohols and acids, can form by-product water to cause the multiple heterogeneous azeotropes and further enormously increase separation difficulty and production costs. This work adopted the transesterification of methyl acetate (MeAC) from the by-product (typical compositions MM20 (15.64 mol% MeAc, 84.36 mol% MeOH) and MM80 (65 mol% MeAC, 35 mol% MeOH) of polyvinyl alcohol (PVA) manufacture and isobutanol (ISBOH) to product ISBAC to avoid the multiple heterogeneous azeotropes. The ISBAC production by MeAC in MM20 and MM80 reacted with ISBOH adopted reactive distillation (RD) combining pressure-swing to break the limits of chemical equilibrium and azeotrope separation. Furthermore, heat integration, thermal coupling, and heat pump technologies were used to systematically recover waste heat and achieve energy-saving for ISBAC production processes. The exergy, economy, and environment evaluation displayed that the heat integration of MM20 pressure-swing RD was the best attractive process by reducing 19.35% total annual cost (TAC), 34.58% CO2 emissions, and improving 33.16% thermodynamic efficiency. The heat source of the low-pressure column and preheating process feed using top steam of the high-pressure column（heat integration-F） of MM80 pressure-swing RD process was the most promising process due to the decrease of 5.40% in TAC, 16.70% in CO2 emissions and obtained the improvement of 4.50% thermodynamic efficiency comparing with the conventional process.

Physical and Chemical Changes in Hydrothermally Modified Wood

In this study, the simulation of artificial conditions, containing various chemical additives similar to a bog environment, was hypothesised as a relatively short way to develop a more sustainable wood product with better properties. This study aimed to determine how hydrothermal treatment with different iron additives with and without tannic acid, performed at 100 °C for 75 h, changed the mass and density of wood of different tree species (Pinus sylvestris L., Picea abies (L.) H. Karst., Pseudotsuga menziesii (Mirb.) Franco, Juglans regia L., and Acer platanoides L.); total phenolic compounds in biobased solvents after the hydrothermal processing andiron concentration in different wood layers. We also aimed to determine the wood chemical composition using Fourier-transform infrared technique. The study results showed that the softwood samples were more susceptible to hydrothermal modification than the hardwood samples, indicated by minorly different intensities on infrared spectra. The FTIR results showed bands of hardwood and softwood samples which along with the spectral characterisation of the wood constituents, which can further be utilized for creating a larger FTIR spectral database of wood samples for their identification. The factors with the most significant effect on the hydrothermal modification were tannic acid and inorganic Fe3O2 salt, used as an additive. The results indicated the suitability of inorganic Fe3O2 salt and tannic acid combination applied in this type of modification, because a higher concentration of iron was distributed on the inner and intermediate sublayers of wood samples. The hydrothermal modification approach to anchor tannic acid–Fe macromolecules in wood shown in this study has promising capabilities and may attract interest in the field of wood protection against weathering.

An eco-friendly approach for the recovery of astaxanthin and β-carotene from Phaffia rhodozyma biomass using bio-based solvents

There is a growing demand in the development of environmentally friendly technologies, based on the use of more biocompatible solvents for the recovery of natural bioactive compounds. In this work, the red yeast Phaffia rhodozyma biomass was used as a source of carotenoids to develop an integrative and efficient platform that promotes the recovery of astaxanthin and β-carotene using bio-based solvents (BioSs). The extraction aptitude of pure BioSs was evaluated and compared with the conventional organic method. At this point, the influence of the BioSs molecular structures involved in the extraction procedures were also investigated. Overall, envisaging the industrial application of the process, an integrative platform was proposed for the recovery of astaxanthin/β-carotene from P. rhodozyma biomass and the recycle of the BioSs. The life cycle assessment of the proposed technology using EtOH was evaluated, validating the sustainability of BioSs in the process with environmental impact reduction of 3–12%.

Reactor microbiome enriches vegetable oil with n-caproate and n-caprylate for potential functionalized feed additive production via extractive lactate-based chain elongation

BackgroundBiotechnological processes for efficient resource recovery from residual materials rely on complex conversions carried out by reactor microbiomes. Chain elongation microbiomes produce valuable medium-chain carboxylates (MCC) that can be used as biobased starting materials in the chemical, agriculture and food industry. In this study, sunflower oil is used as an application-compatible solvent to accumulate microbially produced MCC during extractive lactate-based chain elongation. The MCC-enriched solvent is harvested as a potential novel product for direct application without further MCC purification, e.g., direct use for animal nutrition. Sunflower oil biocompatibility, in situ extraction performance and effects on chain elongation were evaluated in batch and continuous experiments. Microbial community composition and dynamics of continuous experiments were analyzed based on 16S rRNA gene sequencing data. Potential applications of MCC-enriched solvents along with future research directions are discussed.ResultsSunflower oil showed high MCC extraction specificity and similar biocompatibility to oleyl alcohol in batch extractive fermentation of lactate and food waste. Continuous chain elongation microbiomes produced the MCC n-caproate (nC6) and n-caprylate (nC8) from l-lactate and acetate at pH 5.0 standing high undissociated n-caproic acid concentrations (3 g L−1). Extractive chain elongation with sunflower oil relieved apparent toxicity of MCC and production rates and selectivities reached maximum values of 5.16 ± 0.41 g nC6 L−1 d−1 (MCC: 11.5 g COD L−1 d−1) and 84 ± 5% (e− eq MCC per e− eq products), respectively. MCC were selectively enriched in sunflower oil to concentrations up to 72 g nC6 L−1 and 3 g nC8 L−1, equivalent to 8.3 wt% in MCC-enriched sunflower oil. Fermentation at pH 7.0 produced propionate and n-butyrate instead of MCC. Sunflower oil showed stable linoleic and oleic acids composition during extractive chain elongation regardless of pH conditions. Reactor microbiomes showed reduced diversity at pH 5.0 with MCC production linked to Caproiciproducens co-occurring with Clostridiumtyrobutyricum, Clostridiumluticellarii and Lactobacillus species. Abundant taxa at pH 7.0 were Anaerotignum, Lachnospiraceae and Sporoanaerobacter.ConclusionsSunflower oil is a suitable biobased solvent to selectively concentrate MCC. Extractive reactor microbiomes produced MCC with improved selectivity and production rate, while downstream processing complexity was reduced. Potential applications of MCC-enriched solvents may include feed, food and biofuels purposes.

Cleaner production of flexographic ink by substituting carbon black with biochar

There is growing interest in making printing inks more sustainable, and lowering the overall carbon footprint of the printing industry. A recent surge of research activity has emerged to develop “green” inks with bio-based solvents and binders, but little attention has been given to replacing the pigments that give inks their distinctive color. In this study, flexographic inks were formulated by replacing carbon black with a more sustainable biochar pigment derived from recycled paper, and fast growth cycle wood pulp. Obtained from fossil fuel sources, carbon black imparts high quality black prints, but at a significant environmental cost. Biochar, derived from recycled and renewable resources, has the potential to replace carbon black in many applications. Canceled United States currency stock was pyrolyzed at 1600 °C to produce a black biochar. Eastern White Pine (Pinus strobus) was selected for comparison, and converted to biochar at 550 °C and 1600 °C. Each biochar was functionalized and formulated into a simple ink composition optimized for flexographic printing. Prints exhibiting reflective optical densities exceeding 1.0 with excellent tone reproduction were obtained. Comparable print quality was achieved on both coated and uncoated paper substrates. Although further work would be required to fully optimize a biochar ink to match current print industry standards, a viable pathway for sustainable black ink development with good black density derived from recycled resources has been demonstrated. Our results indicate that it is possible to replace fossil fuel-based carbon black with biomass derived biochar, potentially resulting in cleaner production of flexographic printing inks.

Chemical Recycling of Polyhydroxybutyrate (PHB) into Bio-Based Solvents and Their Use in a Circular PHB Extraction

Two novel protocols for the chemical valorization of polyhydroxybutyrate (PHB) were developed, aiming at the production of two bio-based molecules: methyl 3-hydroxybutyrate (MHB) and methyl 3-methoxybutyrate (MMB). Optimized reaction conditions were applied to pure PHB and PHB inclusions inside bacterial cells as starting materials. MHB was synthesized through a single-step catalytic methanolysis, while MMB was synthesized through a three-step process: thermolytic distillation to give crotonic acid (CA), esterification to give methyl crotonate (MC), and oxa-Michael addition of MeOH. The obtained MHB and MMB were tested as solvents for the recovery of PHB itself both from freeze-dried single strain cultures (SSC) and mixed microbial cultures (MMC) with low to medium contents of PHB (22–57 wt %). High PHB recovery was achieved: up to 96 ± 1% through MHB and up to 98 ± 1% through MMB. Extraction from MMC slurry (with a PHB content of 39% on dry weight) was also performed, recovering 77 ± 2% using MHB and 92 ± 2% using MMB. High purities and excellent molecular weights and polydispersity indexes of extracted PHB were obtained with both MHB and MMB. Solubility in water, octanol/water partition coefficients (log Kow), and aerobic ready biodegradability of both solvents were also evaluated.

Evaluation of bio-based solvents for phenolic acids extraction from aqueous matrices

In the current context of a growing demand for environmentally friendly technologies, this study aims to evaluate and develop an efficient liquid–liquid extraction procedure of phenolic acid antioxidants from aqueous environments using bio-based solvents. Due to their abundance in industrial effluents and their importance for human health, a better understanding of how the molecular structures of phenolic antioxidants impact their recovery for pharmaceutical and fine chemical applications is required. Following the principles established by Green Chemistry, the use of eco-friendly solvents including 2-methyltetrahydrofuran (2-MeTHF), cyclopentyl methyl ether (CPME) and D-limonene (LIM) was evaluated in comparison with the conventional organic solvent, ethyl acetate (EA), for liquid–liquid extraction of nine representative phenolic acids: five hydroxybenzoic acids and four hydroxycinnamic acids. The distribution of the target compounds in each phase after the extraction process was obtained by UV–Visible spectrophotometry. The highest extraction yields, up to 100%, were obtained with 2-MeTHF, followed by the conventional solvent EA and CPME. On the contrary, LIM showed the lowest extraction efficiencies. The effect of the molecular structures of the compounds involved in the extraction process was analysed. In addition, the recyclability of 2-MeTHF in consecutive extraction cycles was demonstrated. Overall, a simple and more environmentally friendly liquid–liquid extraction process was developed for the recovery of hydroxybenzoic and hydroxycinnamic acids, while providing insights into the behaviour of the extraction process of phenolic acids using more sustainable solvents.

Ambient-Pressured Acid-Catalysed Ethylene Glycol Organosolv Process: Liquefaction Structure-Activity Relationships from Model Cellulose-Lignin Mixtures to Lignocellulosic Wood Biomass.

Raising the awareness of carbon dioxide emissions, climate global warming and fossil fuel depletion has renewed the transition towards a circular economy approach, starting by addressing active bio-economic precepts that all portion amounts of wood are valorised as products. This is accomplished by minimizing residues formed (preferably no waste materials), maximizing reaction productivity yields, and optimising catalysed chemical by-products. Within framework structure determination, the present work aims at drawing a parallel between the characterisation of cellulose–lignin mixture (derived system model) liquefaction and real conversion process in the acidified ethylene glycol at moderate process conditions, i.e., 150 °C, ambient atmospheric pressure and potential bio-based solvent, for 4 h. Extended-processing liquid phase is characterized considering catalyst-transformed reactant species being produced, mainly recovered lignin-based polymer, by quantitative 31P, 13C and 1H nuclear magnetic resonance (NMR) spectroscopy, as well as the size exclusion- (SEC) or high performance liquid chromatography (HPLC) separation for higher or lower molecular weight compound compositions, respectively. Such mechanistic pathway analytics help to understand the steps in mild organosolv biopolymer fractionation, which is one of the key industrial barriers preventing a more widespread manufacturing of the biomass-derived (hydroxyl, carbonyl or carboxyl) aromatic monomers or oligomers for polycarbonates, polyesters, polyamides, polyurethanes and (epoxy) resins.

Selective Extraction of Piceatannol from Passiflora edulis by-Products: Application of HSPs Strategy and Inhibition of Neurodegenerative Enzymes.

Passiflora edulis by-products (PFBP) are a rich source of polyphenols, of which piceatannol has gained special attention recently. However, there are few studies involving environmentally safe methods for obtaining extracts rich in piceatannol. This work aimed to concentrate piceatannol from defatted PFBP (d-PFBP) by means of pressurized liquid extraction (PLE) and conventional extraction, using the bio-based solvents selected with the Hansen solubility parameters approach. The relative energy distance (Ra) between solvent and solute was: Benzyl Alcohol (BnOH) < Ethyl Acetate (EtOAc) < Ethanol (EtOH) < EtOH:H2O. Nonetheless, EtOH presented the best selectivity for piceatannol. Multi-cycle PLE at 110 °C was able to concentrate piceatannol 2.4 times more than conventional extraction. PLE exhibited a dependence on kinetic parameters and temperature, which could be associated with hydrogen bonding forces and the dielectric constant of the solvents. The acetylcholinesterase (AChE) and lipoxygenase (LOX) IC50 were 29.420 μg/mL and 27.682 μg/mL, respectively. The results reinforce the demand for processes to concentrate natural extracts from food by-products.

A green and efficient method for one-step synthesis of novel oxazolo[3,2-c]pyrimidine derivatives in lactic acid

A new method for one-step synthesis of oxazolo[3,2-c] pyrimidine core and its derivatives has been developed in inexpensive and green bio-based solvent lactic acid without any additional catalysts and additives. Density functional theory calculations located the reaction pathway and identified the intermolecular nucleophilic addition step to be the rate-limiting step. By this method, twenty new oxazolo[3,2-c] pyrimidine derivatives were synthesized in high yield and characterized by spectroscopic analysis and X-ray diffraction.