Biphasic Solvent Research Articles

Dehydration of Xylose and Xylan to Furfural using P‐Zr‐SBA‐15 Catalyst in Aqueous or Biphasic System

AbstractA series of bifunctional P‐Zr‐SBA‐15 catalysts with Lewis acid and Brønsted acid sites were prepared by modifying mesoporous material SBA‐15 with Zr4+ and phosphate group, which were used in the conversion of xylose and xylan into furfural. The structure and acidic characteristics of the catalyst were analyzed by X‐ray diffraction, Fourier transform infrared spectroscopy, N2 adsorption desorption, scanning/transmission electron microscopy, X‐ray photoelectron spectroscopy, thermogravimetric analysis, NH3 temperature programmed desorption, and pyridine adsorption infrared spectroscopy. The effects of different process parameters on the catalytic performance of the catalyst were studied. when using the xylose and xylan as substrates, the furfural yield were 80.3 % and 68.8 % under the optimal conditions in the H2O(NaCl)/toluene (3/3 mL) biphasic solvent system, respectively, and 52.5 % furfural yield was obtained using xylose as substrate in aqueous system. In addition, the catalyst has good thermal stability and easy recovery in the recycling experiment.

Synthesis of chiral salen-MnIII complexes tagged with ionic liquid as recoverable homogeneous catalysts for the oxidative kinetic resolution of (±)-secondary alcohols

New chiral salen ligands tagged with imidazolium based ionic liquids (ILs) were synthesized from the 5-bromopentyl benzoate functionality at C-5 position of salicylaldehyde moiety, N-methylimidazole, and (1R,2R)-1,2-diphenylethane-1,2-diamine/(1R,2R)-cyclohexane-1,2-diamine in 81–92% yields. The chiral salen ligands were further reacted with Mn(OAc)2.4H2O in dry methanol under N2 atmosphere, followed by air oxidation with LiCl to produce the IL tagged chiral salen-MnIII complexes 1(a–c) and 2(a–c) in 79-86% yields. The catalytic activities of these complexes were evaluated in the oxidative kinetic resolution of (±)-1-phenylethanol (8a) with N-bromosuccinimide (NBS) as an oxidizer in biphasic solvent system [H2O - organic solvent (2: 1, v/v)] at 0 °C. The enantioselective oxidation of various (±)-secondary alcohols catalyzed by complex 1c (1 mol%) afforded the chiral secondary alcohols with up to 99% enantiomeric excess and 29.6 krel (selectivity factor) value. The IL tagged chiral salen-MnIII complex 1c was easily recovered with hexane and subsequently reused for five recycles with no significant loss in conversion of (±)-1-phenylethanol (8a) and ee of the resolved product.

Dual-functionalized ionic liquid biphasic solvents with aqueous-lean for industrial carbon capture: Energy-saving and high efficiency

A novel, sustainable, dual-functionalized amino ionic liquid biphasic solvent of 3-(Dimethylamino)-1-propylamine-1,2,4-triazole/poly (ethylene glycol) dimethyl ether/water ([DMAPA][TZ]/NHD/water) was proposed for CO2 capture to reduce the consumption of regeneration energy. Experimental results showed that the CO2 absorption loading of the solvent was 1.95 mol CO2·L−1 solvent at a CO2 partial pressure of 15 kPa. The volume of the CO2-rich phase was 40 vol% of the total volume, with a loading of up to 4.65 mol CO2·L−1 solvent, accounting for approximately 95.4% of the blended CO2 loading in the solvent. The CO2-rich phase could be regenerated by 92.3% in 10 min at 373 K, without the presence of a lean phase. The regeneration efficiency of the solvent was maintained at 83% after 10 adsorption and desorption cycles. The reaction, regeneration, and phase-change mechanism were investigated using 13C NMR and phase composition analysis. CO2 reacted with [DMAPA][TZ] to form two kinds of carbamate during solubilization, and all carbamates could be further hydrolyzed to form HCO3− and CO32−. The solvent effect, phase-change behavior, and CO2 physical dissolution of NHD could promote the absorption and desorption rate and absorption capacity of CO2. The energy consumption for CO2 desorption could be reduced to 1.335 GJ·t−1 CO2, which was 67% lower than that of 30 wt% ethanolamine (3.99 GJ·t−1 CO2), given the lower heat of reaction, specific heat capacity, and solvent loss. Thus, this solvent presents a sustainable strategy for advancing carbon capture technologies.

A novel strategy by combining “magnified” matrix solid phase dispersion extraction with high-speed countercurrent chromatography for the rapid and efficient isolation of flavonoids isomers with anti-inflammatory effect from Lindera aggregata (Sims) Kosterm Leaves

A rapid and efficient isolation strategy by combining matrix solid phase dispersion extraction (MSPD) with high-speed countercurrent chromatography (HSCCC) had been proposed in this study for the separation of four flavonoids with anti-inflammatory effect in high edible value plant food, leaves of Lindera aggregata (Sims) Kosterm (L.aggregata-L). MSPD was firstly developed as an efficient extraction methodology to obtain a “clean” extract for the purpose of further isolation of target compounds. Then, two runs of HSCCC isolation were consecutively performed on MSPD extract to purify the target compounds, in which an environmental-friendly biphasic solvent system composed of ethyl acetate-n-butanol-0.05 mol/L of phosphate buffer (pH 3.16) containing 0.05 mol/L of hydroxypropyl-β-cyclodextrin (HP-β-CD) was established for the successful separation of the flavonoids isomers, for the first time. As a result, 21.3 mg of quercetin-3-O-rhamnopyranoside (purity of 96%), 18.7 mg of kaempferol-7-O-α-l-rhamnopyranoside (purity of 89%), 5.5 mg of quercetin-3-O-β-D-glucoside (purity of 90.3%) and 6.4 mg of quercetin-5-O-β-D-glucoside (purity of 86.4%) were obtained from 5 g plant materials. Further cellular assays (RAW264.7 mouse macrophage cells) revealed that the isomers demonstrated good anti-inflammatory activities, of which quercetin-5-O-β-D-glucoside exhibited better anti-inflammatory effect (330% higher than quercetin-3-O-β-D-glucoside at the concentration of 25 μM) but lower cytotoxicity (50% lower than quercetin-3-O-β-D-glucoside at the concentration of 400 μM). In summary, this research indicated a promising isolation strategy of natural compounds which would provide a solid surport for the subsequent further study and development of L. aggregata-L.

Novel monoethanolamine absorption using ionic liquids as phase splitter for CO2 capture in biogas upgrading: High CH4 purity and low energy consumption

Ionic liquid, as a green absorber, could be effectively combined with amine solution to obtain a mixed system that effectively improved the upgrading effect and reduced regeneration energy consumption in the biogas upgrading process. In this work, an aqueous biphasic solvent consisting of 30 wt% monoethanolamine (MEA) and 40 wt% 1-butyl-3-methylimidazolium tetrafluoroborate (BF) was prepared, which had advantages such as excellent biogas upgrading effect, high CO2 recycling loading and low regeneration energy consumption. The effect law of ionic liquid addition to amine solution on biogas upgrading and mass transfer characteristics was comprehensively evaluated through the analysis and prediction of physical parameters, and the excellent biogas upgrading characteristics of the mixed system and the favorable effect of ionic liquid on mass transfer were verified. The solvent effect of the ionic liquid could appropriately lower the energy barrier for the reaction to produce carbamate and improve the CO2 capture effect. The higher polarity of the ionic liquid solvent also provided the driving force for the phase separation and accelerated the phase separation process. The distribution pattern of CO2 loading with time and space was comprehensively studied by using amplified phase separator, covering the whole process variation of phase separation. The important role of intermolecular forces in the phase separation process was discussed, and the important reasons for the occurrence of phase separation in phase separators were explained.

Liquid-liquid chromatography separation of hemp terpenes with repellent properties against Hyalomma marginatum: A multi-methodological approach

Tick-borne diseases raise serious health concerns for both humans and animals. Tick control and disease prevention largely depend on synthetic acaricides and repellents, often incriminated for high toxicity. To find alternative, safe, and efficient agents against ticks, research on plant-based volatile terpenes constitutes a promising direction. This study aimed to separate and identify hemp flower compounds with repellent properties against Hyalomma marginatum (Acari: Ixodidae). Produced by supercritical CO2 extraction under different pressure (100–110 bar) and temperature (40–60 °C) conditions, the hemp extracts were tested in a moving object bioassay. The extract with the highest repellent power was further subjected to batch liquid-liquid chromatography (LLC). The biphasic solvent system (n-heptane/methanol/acetonitrile 10/5/10, v/v/v) for separating the major hemp terpenes was selected by combining the COSMO-RS-based distribution coefficient screening with experimental validation. Bisabolol (>99%), caryophyllene oxide (>98%), and caryophyllene/humulene (3.5/1, w/w, >95% purity) were thus isolated and assessed in the H. marginatum bioassay. The activity of bisabolol (20% w/w in hexane) was comparable to the synthetic repellent DEET at the same concentration. For the large-scale purification of bisabolol, trapping multiple dual mode, a semi-continuous flow-reversal LLC operating mode, was proposed and evaluated. Bisabolol was obtained with a solvent consumption 2.6-times lower and productivity 2.7-times higher than the batch process. In conclusion, using a multi-methodological computer-aided approach, bisabolol was efficiently identified and isolated as a good tick repellent agent from hemp flowers.

A deep eutectic solvent binary-phase system for alkaloid extraction from Chinese herb Evodia lepta residue and its mechanism

Bioactive compound extraction using deep eutectic solvent has the challenges of high solvent viscosity and difficult product separation. In present study, we designed a biphasic deep eutectic solvent (DES) system (levulinic acid–glycerol–K2HPO4 aqueous solution with ethyl acetate phase) to extract alkaloids from the residue of the Chinese herb Evodia lepta. The aqueous phase of DES with low viscosity enabled the mass extraction of alkaloids from plant cells, and the extracted compounds were transferred in situ and concentrated in the hydrophobic ethyl acetate phase. The biphasic extraction reduced the alkaloid accumulation in the aqueous phase and improved the extraction efficiency. The optimal extraction process was the binary system consisting of 20 mL of ethyl acetate and 50 mL of DES of levulinic acid–glycerol with molar ratio of 1.5:1 containing 30% K2HPO4 solution (0.4 g/mL), with a solid-DES ratio of 1:20 g/mL, under the extraction conditions of 40 min, 75 °C. The total alkaloids with highest yield of 757.71 μg/g, 587.45% higher than that achieved using traditional methanol extraction, was transferred to the ethyl acetate phase with selectivity of 72.03, 39.16, and 80.67% for skimmianine, dictamnine, and evodiamine, respectively. The molecular mechanism based on the Density Functional Theory indicated that the present solvent possesses higher capacity of forming hydrogen bonds with alkaloids than other tested solvents. Moreover, evodiamine showed lower binding energy with ethyl acetate, which explained why evodiamine extracted into the aqueous phase transferred quickly to the hydrophobic phase.

A novel binary solid-liquid biphasic functionalized ionic liquids for efficient CO2 capture: Reversible polarity and low energy penalty

Ionic liquids (ILs) solid-liquid biphasic solvents for CO2 capture have the advantages of high CO2 loading and low energy consumption, and their phase change behavior was regulated via phase separation agents. However, phase separator agents exhibit bottlenecks in terms of volatility loss and high-rich phase viscosity. A novel “reversible polarity” functionalized ionic liquids (isophorone diamine-imidazole, [IPDAH][Im]) was innovatively proposed in this work, which featured solid-liquid phase change behavior upon CO2 absorption in water in the absence of a phase separation agent. After saturated absorption, CO2 products were enriched into the lower phase and precipitated as a white crystalline powder with 91 % of the total CO2 loading (1.15 mol mol−1) but only 60 % of the total volume. Products after thermal desorption (393.15 K), maintaining 80 % of its initial loading after the sixth regeneration cycle. Based on the results of experimental characterization and theoretical calculation, [IPDAH][Im] possessed reversible polarity, and its initial polarity was consistent with that of water. After absorption, [IPDAH][Im] interacted with CO2 to form products whose polarity diminishes, resulting in the associated phase transition; after desorption, the high polarity is restored. The products existed as ion pairs (ILsCOO−-ILsH+), as evidenced by strong van der Waals interaction, and electrostatic attraction. Strong hydrogen bonding forces between the products and the Hansen solubility parameter, as well as the high lattice energy, led to the self-agglomeration formation of the products in water, resulting in the development of a solid powder product. The heat duty of [IPDAH][Im]–H2O was 1.23 GJ ton−1 CO2, which was approximately 67 % less than that of monoethanolamine (MEA; 3.77 GJ ton−1 CO2), signifying a major potential for application in CO2 capture.

High-throughput isolation of gentiopicroside from Gentiana lutea and the study on its anticancer properties in vitro

The study aims at the isolation of gentiopicroside (GPC) from Gentiana lutea L. root extracts. GPC is a bioactive glycosylated secoiridoid from Gentiana spp. (Gentianaceae) proved to exhibit broad pharmaceutical activities, including anti-inflammatory, hepatoprotective and spasmolytic action. Due to its marked potential, an efficient recovery method of high purity GPC from G. lutea roots was elaborated using the combination of Centrifugal Partition Extraction (CPE) that offers the advantage of industrial scalability, and Preparative High Performance Liquid Chromatography (prep-HPLC) techniques. For this purpose the root hydroalcoholic extract of G. lutea was initially fractionated in a 0.3 L volume CPE column using the biphasic solvent system that was composed of heptane: ethyl acetate: ethanol: water 1:8:3:5 (v/v/v/v) in elution-extrusion mode. As a result, 2.2 g of GPC (purity > 90%) and 0.77 g of GPC-enriched fractions (purity > 80%) were obtained from 31.5 g of the extract within 6 h (5 consecutive CPE fractionations). The following prep-HPLC based purification step increased the quantity and purity of the finally isolated secoiridoid to 2.21 g of > 96% pure GPC. The successful recovery of large amounts of pure GPC enabled the study on the anti-proliferative activity against the following cancer and normal cell lines: lung (A549, NCI-H1299), breast (MCF7, MDA-MB-468), glioblastoma (T98G), rhabdomyosarcoma (TE671), colon (HT-29, DLD-1) cancer cells and normal colon epithelial cells (CCD 841 CoTr). The MTT assay enabled the evaluation of the dose-dependent growth inhibition effect that was evident in all analyzed cancer cell lines, however, TE671 cells were the most sensitive (IC50 = 0.078 mg/mL) and MDA-MB-468 cells were the least sensitive (IC50 = 0.208 mg/mL) to the GPC treatment. The tested compound showed only a weak cytotoxic effect against normal cells (CCD 841 CoTr).

Terminally Phosphorylated Triblock Polyethers Acting Both as Templates and Pore-Forming Agents for Surface Molecular Imprinting of Monoliths Targeting Phosphopeptides.

The novel process reported here described the manufacture of monolithic molecularly imprinted polymers (MIPs) using a terminally functionalized block copolymer as the imprinting template and pore-forming agent. The MIPs were prepared through a step-growth polymerization process using a melamine-formaldehyde precondensate in a biphasic solvent system. Despite having a relatively low imprinting factor, the use of MIP monolith in liquid chromatography demonstrated the ability to selectively target desired analytes. An MIP capillary column was able to separate monophosphorylated peptides from a tryptic digest of bovine serum albumin. Multivariate data analysis and modeling of the phosphorylated and nonphosphorylated peptide retention times revealed that the number of phosphorylations was the strongest retention contributor for peptide retention on the monolithic MIP capillary column.

Efficient Separation of the Methoxyfuranocoumarins Peucedanin, 8-Methoxypeucedanin, and Bergapten by Centrifugal Partition Chromatography (CPC)

Pure methoxyfuranocoumarins were isolated from a crude petroleum ether extract (CPE; Soxleth extraction efficiency 12.28%) from fruits of Peucedanum tauricum MB. (Apiaceae) by counter-current chromatography in a hydrostatic equilibrium system (centrifugal partition chromatography-CPC). The optimized biphasic solvent system composed of n-heptane-ethyl acetate-methanol-water (5:2:5:2; v/v/v/v) in the ascending mode of elution was used (3 mL/min, 1600 rpm). In the single run, peucedanin (P), 8-methoxypeucedanin (8MP), and bergapten (5MOP) were obtained as pure as 95.6%, 98.1%, and c.a. 100%, respectively. The carefully optimized and developed CPC was effectively transferred from the analytical to the semi-preparative scale (where 20 mg and 150 mg of CPE were loaded, respectively). Identification and quantitative analysis of methoxyfuranocoumarins was carried out in the plant material, in the CPE, and in individual CPC fractions by use of validated high-performance liquid chromatography with diode array detection and mass spectrometry (HPLC-DAD-ESI-MS). For the separation steps, the extraction/isolation recovery was calculated. In this case, CPC proved to be an effective tool for the simultaneous isolation and separation of P, 8MP, and 5MOP from a multicomponent plant matrix, without additional pre-purification steps. The high purity of the obtained plant metabolites makes it possible to consider their use in pharmacological or biological studies.

Orientated inhibition of humin formation in efficient production of levulinic acid from cellulose with high substrate loading: Synergistic role of additives

The main bottleneck in the direct conversion of cellulose to levulinic acid (LA), a promising bio-based platform chemical, lies in the severe formation of humins, especially at high substrate loading (>10 wt%). Herein, we report an efficient catalytic system consisting of a 2-methyltetrahydrofuran/water (MTHF/H2O) biphasic solvent with NaCl and cetyltrimethylammonium bromide (CTAB) as additives for converting cellulose (15 wt%) to LA in the presence of a benzenesulfonic acid catalyst. We show that both NaCl and CTAB accelerated the depolymerization of cellulose and formation of LA. However, NaCl favored the humin formation via degradative condensations, whereas CTAB inhibited humin formation by restraining the routes of both degradative and dehydrated condensations. A synergistic role of NaCl and CTAB on suppressing humin formations is illustrated. The combined use of NaCl and CTAB led to an increased LA yield (60.8 mol%) from microcrystalline cellulose in MTHF/H2O (VMTHF/VH2O = 2/1) at 453 K for 2 h. Moreover, it was efficient for converting cellulose fractioned from several kinds of lignocellulosic biomass, wherein a high LA yield of 81.0 mol% was achieved from wheat straw cellulose. This work presents a new strategy for advancing LA biorefinery by synergistically promoting cellulose depolymerization with orientated inhibition of undesired humin formation.

Catalytic conversion of diformylxylose to furfural in biphasic solvent systems.

Biobased furfural is a sustainable alternative to petrochemical intermediates for bulk chemicals and fuel production. However, existing methods for the conversion of xylose or lignocelluloses in mono-/bi-phasic systems to furfural involve non-selective sugar isolation or lignin condensation, limiting the valorisation of lignocelluloses. Herein, we used diformylxylose (DFX), a xylose derivative that is formed during the lignocellulosic fractionation process with formaldehyde protection, as a substitute for xylose to produce furfural in biphasic systems. Under kinetically optimized conditions, over 76mol% of DFX could be converted to furfural in water-methyl isobutyl ketone system at a high reaction temperature with a short reaction time. Finally, isolation of xylan in eucalyptus wood as DFX with formaldehyde protection followed by converting DFX in a biphasic system gave a final furfural yield of 52mol% (on the basis of xylan in wood), which was more than two times of that without formaldehyde. Combined with the value-added utilization of formaldehyde-protected lignin, this study would enable the full and efficient utilization of lignocellulosic biomass components and further improve the economics of the formaldehyde protection fractionation process.

Pilot test of water-lean solvent of 2-(ethylamino) ethanol, 1-methyl-2-pyrrolidinone, and water for post-combustion CO2 capture

Water-lean solvent for post-combustion CO2 capture is promising to significantly reduce regeneration energy. It hasn’t been put into commercial application due to unsolved challenges including water balance issue, increased viscosity, and high volatility. Even though numerous water-lean solvents were developed in laboratory, rare of them were tested in pilot scale. Water-lean solvent of 2-(ethylamino) ethanol (EMEA) dissolving into 1-methyl-2-pyrrolidinone (NMP) and water was tested in a CO2 capture pilot with flue gas rate of 280 m3/h. Effects of liquid/gas ratio and reboiler steam rate on CO2 removal efficiency, regeneration energy, lean/rich heat exchanger performance, and volatile amine emission were investigated. Water-lean EMEA achieved CO2 removal efficiency greater than 90 % and the lowest regeneration energy of 2.3 GJ/tCO2, which is 43 % lower than that of 5 M MEA. Water-lean EMEA showed significantly reduced latent heat, greater CO2 capacity, and lower reaction heat (secondary amino) than aqueous MEA and amine blends. It was found that water-lean EMEA regeneration in stripper had extremely lower lean loading (0.1–0.5 mol CO2/L) than aqueous MEA and amine blends, which enables a faster CO2 absorption rate in absorber and a greater CO2 capacity, but also causes larger volatile amine emission. Volatile amine emission after water wash was 110–380 mg/m3. 13C NMR spectrum suggested amine carbamate dominated CO2 absorption products. Due to that increased viscosity decreases heat transfer coefficient (h), lean/rich heat exchanger temperature difference (ΔT) for water-lean EMEA (6.5–7.5℃) was greater than MEA (3.5-5℃) and amine blends (5-6℃), yet smaller than biphasic solvent (8-9℃). A negative power (-0.614) function relation between h and viscosity was fitted and can be further used to normalize sensible heat.

Oriented Conversion of a LA/HMF Mixture to GVL and FDCA in a Biphasic Solvent over a Ru Single-Atom/Nanoparticle Dual-Site Catalyst

The industrial use of lignocellulose is limited by the copresence of C5 and C6 carbohydrates in this feedstock and the low selectivity of the corresponding catalytic conversion reaction, which collectively result in suboptimal product yields and necessitate energy-intensive purification/separation processes. Herein, we designed a composite dual-site Ru single-atom (SA)/Ru nanoparticle (NP) catalyst for the hydrogenation of levulinic acid (LA) and the oxidation of 5-hydroxymethyl furfural (HMF) in a biphasic solvent (γ-valerolactone (GVL)-saturated aqueous Na2CO3). Ru-SAs activated LA, while Ru-NPs boosted H2 dissociation to promote the hydrogenation of LA to GVL and ensured the efficient oxidation of HMF to 2,5-furandicarboxylic acid (FDCA). The SA/NP site design increased the oriented conversion efficiency of complex substrates, and the alternate hydrogenation–oxidation process ensured the stability of catalyst activity. The biphasic solvent system not only facilitated the mass transfer process but also allowed the spontaneous and non-energy-intensive separation of the produced GVL and FDCA. The obtained results pave the way for the design of SA/NP dual-site catalysts for the one-pot oriented conversion of complex substrates and the facile separation of products.

Mechanistic behaviour of Chlorella vulgaris biofilm formation onto waste organic solid support used to treat palm kernel expeller in the recent Anthropocene

The capacity to maximize the proliferation of microalgal cells by means of topologically textured organic solid surfaces under various pH gave rise to the fundamental biophysical analysis of cell-surface attachment in this study. The substrate used in analysis was palm kernel expeller (PKE) in which the microalgal cells had adhered onto its surface. The findings elucidated the relevance of surface properties in terms of surface wettability and surface energy in relation to the attached microalgal growth with pH as the limiting factor. The increase in hydrophobicity of PKE-microalgae attachment was able to facilitate the formation of biofilm better. The pH 5 and pH 11 were found to be the conditions with highest and lowest microalgal growths, respectively, which were in tandem with the highest contact angle value at pH 5 and conversely for pH 11. The work of attachment (Wcs) had supported the derived model with positive values being attained for all the pH conditions, corroborating the thermodynamic feasibility. Finally, this study had unveiled the mechanism of microalgal attachment onto the surface of PKE using the aid of extracellular polymeric surfaces (EPS) from microalgae. Also, the hydrophobic nature of PKE enabled excellent attachment alongside with nutrients for microalgae to grow and from layer-by-layer (LbL) assembly. This assembly was then isolated using organosolv method by means of biphasic solvents, namely, methanol and chloroform, to induce detachment.

Nonlinear liquid-liquid chromatography: Beyond a constant distribution coefficient

Liquid-liquid chromatography (LLC) is a technique in which the separation of mixture components is achieved due to their different distribution between the two phases of a pre-equilibrated biphasic solvent system. In this work, the LLC operation in the nonlinear range of the distribution isotherm was systematically examined for the first time. The influence of the feed concentration on the elution profiles of a model component (cannabidiol, CBD) was studied in three LLC units of different types and sizes ranging from ∼20 mL to ∼2 L. A series of pulse injections with CBD concentrations varying from 1 to 300 mg/mL was performed with n-hexane/methanol/water 5/4/1 (v/v/v) in descending mode (lower phase as the mobile phase). The elution profiles were simulated using the equilibrium-cell model and an anti-Langmuir-like equation for describing the CBD distribution equilibria. The distribution equilibria equation parameters were fitted to the CBD elution profiles using the peak fitting method. The model was validated and provided good predictions of the CBD elution profiles in the entire concentration range for all three LLC units.

Efficient Co-Production of Xylooligosaccharides and Glucose from Vinegar Residue by Biphasic Phenoxyethanol-Maleic Acid Pretreatment

A new biphasic organic solvent, phenoxyethanol-maleic acid, was carried out to pretreat and fractionate vinegar residue into glucan, xylan and lignin under mild conditions. Additional effects of key factors, temperature and phenoxyethanol concentration, on vinegar residue, were evaluated. Under the biphasic system (0.5% maleic acid, 60% phenoxyethanol), 140 °C cooking vinegar residue for 1 h, 80.91% of cellulose retention in solid residue, 75.44% of hemicellulose removal and 69.28% of lignin removal were obtained. Optimal identified conditions resulted in maximum XOS of 47.3%. Then, the solid residue was enzymatically digested with a glucose yield of 82.67% at 72 h with the addition of 2.5 g/L bovine serum albumin. Finally, the residue was characterized by SEM, FTIR, XRD and BET analysis. This work demonstrated the phenoxyethanol-maleic acid pretreatment yielded XOS, fermentable sugar, and lignin with high processibility.

Fractionation of lignin from rice straw using an acidified biphasic solvent system

To obtain lignin from lignocellulosic biomass, phenoxyethanol (EPH) was employed to construct a biphasic solvent system. The concentration of EPH in this biphasic solvent system was first studied to determine a pretreatment condition for fractionation of lignin. Then, the fractionation of lignin from rice straw was performed under the conditions of temperature 130 °C, cooking time 60 min and sulfuric acid concentration 0.1 M, in 70 % aqueous EPH solvent system. The results showed that 50.97 %, 49.52 % or 82.02 % of the removed lignin with the purity of 89.04 %, 91.30 % or 84.76 % was regenerated from EPH liquor using dimethyl carbonate (DMC), dimethoxymethane (DMM) or diethyl ether (DE) as precipitant, respectively. Additionally, the weight-average molecular weight (Mw) and dispersity index (Đ) of the regenerated lignin decreased to 4247–4809 g/mol and 1.26–1.60 compared with that of the original lignin (5654 g/mol and 4.78). Finally, the compositional and structural characteristics of lignin, e.g., molecular weight and molecular structure, were also investigated by DSC, HSQC and elemental analysis.

Recent advances in biomass pretreatment using biphasic solvent systems

The complexity and recalcitrance of lignocellulosic biomass seriously hinder its subsequent conversion to liquid fuels.