Separation Of Phenolic Compounds Research Articles

A stationary phase of tetraethylene glycol-modified silica for separation of phenolic acids

AbstractSilica, as a stationary phase, has low separation efficiency accompanied by overlapping, broadened, and tailed peaks, so it needs to be modified to improve its efficiency. This study aims to develop a silica-based stationary phase modified by tetraethylene glycol (TEG) to separate phenolic compounds. Silica was modified by a chemical bond between silanol groups on the silica surface and TEG through a 3-glycidyloxypropylmethoxysilane reaction. The modified silica was packed into a capillary column and used to separate simple phenolic compounds consisting of phenol, pyrocatechol, and pyrogallol. A sample of 0.2 µL was injected into the capillary liquid chromatography and the mobile phase employed was acetonitrile 98% with a flow rate of 3 μL min−1. Elution was also done isocratically in this process and detection was carried out at a wavelength of 254 nm. The mixture of simple phenolic compounds was successfully separated in less than 7 min. The asymmetry factor and resolution were 1.43–2.12 and 1.72–5.43 respectively. The number of the theoretical plates ranged from 213 to 7,857. Columns containing Si-TEG stationary phase also separate phenolic compounds, which consist of gallic acid, syringic acid, ferulic acid, and caffeic acid. A sample of 0.2 µL was injected into the capillary liquid chromatography and successfully separated the mixture in less than 12 min. The samples were eluted isocratically using a mixture of methanol and 50 mM phosphate buffer pH 2.5 (8:92) with a flow rate of 3 μL min−1. The phenolic acids compounds were detected at a wavelength of 280 nm. The chromatogram showed four separate peaks. The asymmetry factor and resolution were 1.53–1.63 and 1.14–1.74, respectively, but the number of the theoretical plates was low, ranging from 190 to 796.

Improving the Accuracy of Predictive 2D-LC Optimization Strategies: Incorporation of Simulated Elution Profiles to Account for Injection Band Broadening in Online Comprehensive Two-Dimensional Liquid Chromatography.

Method development in online comprehensive two-dimensional liquid chromatography (LC × LC) requires the selection of a large number of experimental parameters. The complexity of this process has led to several computer-based LC × LC optimization algorithms being developed to facilitate LC × LC method development. One particularly relevant challenge for predictive optimization software is to accurately model the effect of second dimension (2D) injection band broadening under sample solvent mismatch and/or sample volume overload conditions. We report a novel methodology that combines a chromatographic numerical simulation model capable of predicting elution profiles of analytes under conditions where peak distortion occurs with a predictive multiparameter Pareto optimization approach for online LC × LC. Preliminary method optimization is performed using a theoretical model to predict 2D injection profiles, and optimal experimental configurations obtained from the Pareto fronts are then subjected to further optimization using the simulation model. This approach drastically reduces the number of simulations and therefore the computational demand. We show that the optimal experimental conditions obtained in this manner are similar to those obtained using a complete optimization using only the simulation model. Online HILIC × RP-LC separation of phenolic compounds was used to compare experimental data to simulated two- and three-dimensional contour plots. The main advantage of the proposed approach is the ability to predict the formation of split or deformed peaks in the 2D, a significant benefit in online LC × LC method optimization, especially for separation combinations with mismatched mobile phases. A further benefit is that simulated elution profiles can be used for the visualization of predicted two-dimensional chromatograms for method selection.

Fractional condensation of bio-oil vapors from pyrolysis of various sawdust wastes in a bench-scale bubbling fluidized bed reactor

The use of lignocellulosic waste as an energy source for substituting fossil fuels has attracted lots of attention, and pyrolysis has been established as an effective technology for this purpose. However, the utilization of bio-oil derived from non-catalytic pyrolysis faces certain constraints, making it impractical for direct application in advanced sectors. This study has focused on overcoming these challenges by employing fractional condensation of pyrolytic vapors at distinct temperatures. The potential of five types of sawdust for producing high-quality bio-oil through pyrolysis conducted with a bench-scale bubbling fluidized bed reactor was investigated for the first time. The highest yield of bio-oil (61.94 wt%) was produced using sample 3 (damaged timber). Remarkably, phenolic compounds were majorly gathered in the 1st and 2nd condensers at temperatures of 200 °C and 150 °C, respectively, attributing to their higher boiling points. Whereas, carboxylic acid, ketones, and furans were mainly collected in the 3rd (−5 °C) and 4th (−20 °C) condensers, having high water content in the range of 35.33%–65.09%. The separation of acidic nature compounds such as acetic acid in the 3rd and 4th was evidenced by its low pH in the range of 4–5, while the pH of liquid collected in the 1st and 2nd condensers exhibited higher pH (6–7). The well-separated bio-oil derived from biomass pyrolysis facilitates its wide usage in various applications, proposing a unique approach toward carbon neutrality. In particular, achieving efficient separation of phenolic compounds in bio-oil is important, as these compounds can undergo further upgrading to generate hydrocarbons and diesel fuel.

Separation of phenolic compounds from fruit processing wastewater using liquid membrane technology: A short review

Phenolic compounds are components of secondary metabolites primarily present in fruits, vegetables and grains. These compounds have gained significant attention from the food, pharmaceutical, and cosmetic industries due to their antioxidant properties, which can provide health benefits to humans. Phenolic compounds can be extracted from natural or secondary sources. Nevertheless, the global focus on sustainability has led industries to consider the recovery of phenolic compounds from secondary sources, such as fruit processing wastewater. Various technologies have been proposed and tested for the removal of phenolic compounds, including solvent extraction, adsorption, distillation, and others. However, the aforementioned methods required additional post-treatment in order to recover phenolic compounds. Liquid membrane (LM) technology has emerged as a highly efficient method for removing and recovering of phenolic compounds from various sources of feed phase due to its simultaneous removal and recovery process, simple operation, low chemical, and energy consumption. The purpose of this short review is to highlight the potential application of LM technology by assessing its effectiveness in the separation of phenolic compounds from fruit processing wastewater. By utilizing LM technology, it is possible to efficiently remove and recover phenolic compounds from fruit processing wastewater, thereby reducing environmental pollution, and enabling sustainable production of these valuable compounds.

Evaluation of stirring rate and pH on phenolic compounds recovery from palm kernel shell heavy phase bio-oil

This study aims to develop an efficient separation method for phenolic compounds derived from the heavy phase of bio-oil produced by the pyrolysis of palm kernel shell. Two variables were investigated during phenolic compound extraction using dichloromethane, i.e., stirring rate and pH of the solution. In both variables, the composition, yield, and distribution coefficient of the extracted phase were investigated. The results showed that the phenolic compounds' extraction favors high stirring rate and it obtained more results at more acidic conditions (lower pH). The best conditions for phenolic compounds were at 300 rpm of stirring rate and pH 4, which resulted in 77.88 % of yield and a 1.13 distribution of coefficient for the total phenols. The findings of this research will contribute to the better separation of phenolic compounds in bio-oil for improving its fuel characteristics as well as producing value-added chemicals.

Novel halogen-free deep eutectic solvents for efficient extraction of phenolic compounds from real coal tar

The separation of phenolic compounds from coal tar is conducive to the manufacture of high value-added phenolic products and the further processing of oil. Herein, three novel halogen-free choline dihydrogen citrate (CDC)-alcohols deep eutectic solvents (DESs) were prepared to extract phenolic compounds from real coal tar. The effects of the critical parameters including components and constituent mole ratio of DESs, mass ratio of DESs to coal tar, temperature, and time on extraction efficiency were systematically investigated. It was demonstrated that the extraction efficiency decreased with the extension of alkyl chain of alcohols. Hence, CDC-ethylene glycol (EG) was selected as the appropriate extractant, and the extraction efficiency reached 89.3% under the optimal conditions. Fourier transform infrared spectra revealed that the hydrogen bond interaction between CDC and EG was the main reason for their formation of DES. Phenolic compounds also had hydrogen bond interactions with DES, which was the main driving force for the separation of phenolic compounds from coal tar by DES. Differential scanning calorimeter results displayed that the CDC-EG had no definite melting point, and its glass transition temperature was significantly lower than the melting point of individual components. The CDC was recovered by using ethyl acetate as the back extraction agent. Moreover, to avoid back extraction operation, phenolic resin gel was prepared by one-pot method, which was expected to be suitable candidate as the precursor for functional carbon materials.

Separation of phenolic compounds from water by using monoterpenoid and fatty acid based hydrophobic deep eutectic solvents

Nitrophenol-based chemicals are hazardous compounds that negatively impact human health and the environment. These pollutants are used in agriculture as fungicides and pesticides and contribute to groundwater contamination. These compounds are also commonly used for making dyes, rubber materials, and paint coloring. Nitrophenol compounds are known to cause problems with respiratory, ocular, and hematological-related health issues. Due to their environmental and health impacts, the World Health Organization has listed these compounds as one of the most widely observed pollutants that must be addressed. Hydrophobic deep eutectic solvents (HDES) are widely popular for water treatment as they are formed by combining non-toxic, renewable, and biodegradable materials. In this work, three different types of monoterpenoid and fatty acid-based HDES were used in liquid–liquid extraction to remove varying concentrations of 2- and 4-nitrophenol compounds from water. Liquid-liquid extractions were performed at various temperatures and mixing times to optimize the extraction performance. Ultraviolet–visible (UV–Vis) spectrophotometry and mass spectroscopy were utilized to determine and confirm the exaction efficiencies of the various HDES systems. In addition to experimental data, density functional theory (DFT) and classical molecular dynamics (MD) simulations were carried out to study close-range interactions and how HDES and phenolic contaminants interact with each other in the bulk phase. Radial and spatial distribution functions, hydrogen bonding distribution, and energy profiles were studied in detail. The results show high extraction efficiency of up to 95% at short HDES exposure time to contaminated water with both phenolic compounds considered in this work.

Investigation of the extraction ability and mechanism of environmentally friendly ionic liquids for phenol in the model oil

The large number of phenolic compounds contained in coal tar and coal-converted oil seriously increased their cost of processing and transportation difficulties, so methods for efficient separation of phenolic compounds is of great industrial significance. Based on the flexible designability of ionic liquids, hydroxyl functional group that can interact with phenol were introduced into ionic liquid’s cations, eight ionic liquids were synthesized and their separation properties of phenol in model oil (methylbenzene) were studied. Cations of these ionic liquids have a significant influence the phenol extraction efficiency, which follows the order: [Ch]+ > [HEMIM]+. But the anions show a relatively small influence, and the order is: [Pro]- > [Lac]- > [Gly]- > [Ac]-. Other effects such as extraction temperature, molar ratio of phenol to ILs, extraction time and other factors on the extraction efficiency and distribution coefficient were investigated, also the optimum parameters were obtained. Hydroxyl modified ionic liquids showed good extraction performance for phenol, and the choline propionate ionic liquids showed the best separating capacity and were selected as the best extractant. The extraction performance was analyzed by 1H NMR and FT-IR spectra analysis. Hydrogen bond was confirmed to be one of the extraction mechanisms and we found that there was an optimal distance between the cation and anion of ionic liquids to form hydrogen bonds with phenol, also the π-π interaction between imidazole ring and benzene ring in phenol contributed to the extraction. In addition, the ionic liquid showed good recyclability and the regenerated ionic liquids could be reused five times with highly extraction efficiency.

Use of mass spectrometry as a tool for the search or identification of flavonoids in Urticaceae

Abstract The Urticaceae family, circumscribed within the Rosales, was investigated in this study with an overview of the current literature about phytochemical studies using the Liquid Chromatography coupled to Mass Spectrometry (LC-MS) technique. The aim of this study was to review the secondary metabolites identified in the Urticaeae using LC-MS analysis. A systematic review was performed using Scifinder and ScienceDirect databases. Phenolic substances are the most abundant in the Urticaceae family, especially flavones, phenolic acids, and flavonols. We have shown that flavonoids are important chemotaxonomic markers of the chemical composition of the Urticaeae. Following chemical attributes, the C-glycosylated and O-glycosylated flavones stand out as the main skeletons. Our results revealed the chemical profile and structural variability of micromolecules from each genus of Urticaceae. This approach demonstrates a greater use of reversed-phase and liquid chromatography coupled to a mass spectrometer with a negative mode electrospray ionization (ESI) source. In addition, the mobile phase is usually composed of binary systems and eluted by gradient systems. Finally, this paper presents the identification of molecular ion patterns and fragmentation of chemical markers in Urticaceae, identified and isolated using LC-MS, which has been proven to be a valuable tool in several areas, such as phytochemistry, chemosystematics, and chemophenetics. In conclusion, this review is expected to help identify and separate phenolic compounds from the Urticaceae family.

Separation of m-cresol from model oil by pyridinium-based ionic liquids: COSMO-RS screening, experimental study, and process simulation

The separation of phenolic compounds from low-temperature coal tar is conducive to the rational utilization of resources and environmental protection. In this work, pyridinium-based ionic liquids (ILs) were used as extractants for m-cresol/cumene separation. 70 pyridinium-based ILs formed by 10 cations and 7 anions were screened combining the calculation of the extraction ability of ILs for m-cresol and the mutual solubility of ILs with cumene by COSMO-RS model. The influences of cation and anion structures were studied and further explored by σ-profile and σ-potential. Among 70 ILs, the IL 1-ethyl-pyridinium dicyanamide ([C2py][N(CN)2]) was finally identified. Then [C2py][N(CN)2] was synthesized and used to separate m-cresol from model oil. The influences of stirring time, temperature, IL: model oil mass ratio, and initial m-cresol content on the separation performance of [C2py][N(CN)2] were investigated. The regeneration of [C2py][N(CN)2] was carried out and was characterized by FT-IR. The formation of hydrogen bond between [C2py][N(CN)2] and m-cresol was confirmed by FT-IR. Moreover, the process simulation and optimization were investigated by Aspen Plus based on the NRTL model. For the separation process using [C2py][N(CN)2], products with high recovery ratio (99.97% for m-cresol and 99.99% for cumene) and high mass purity (99.97 wt% for m-cresol and 99.80 wt% for cumene) were obtained. The simulation results could provide a guidance for industrial application.

Highly efficient separation of phenolic compounds from low-temperature coal tar by composite extractants with low viscosity

• Imidazolium IL-solvent composite extractants were applied for separation of phenolic compounds from oil. • The suitable composite extractants were identified by COSMO-RS calculation and viscosity determination. • [Emim][HSO 4 ]:EG (1:2) was selected due to its high phenol extraction efficiency, low oil entrainment, and low viscosity. • The separation mechanism was investigated by σ -profile, σ -potential, and FT-IR. Highly efficient separation of phenolic compounds from low-temperature coal tar (LTCT) is significant in the industry. In this work, composite extractants composed of imidazolium-based ionic liquids (ILs) and solvents were used to separate phenolic compounds from model oil and LTCT. First, the COSMO-RS model was used to screen composite extractants that combined the infinite dilution thermodynamic indexes and liquid–liquid equilibria (LLE) calculations. Meanwhile, the separation mechanism was analyzed by σ -profile and σ -potential. Then, the reliability of the COSMO-RS model was validated by LLE experiments and FT-IR. The viscosity of composite extractants with high separation performance was further determined. Among the composite extractants, 1-ethyl-3-methyl-imidazolium hydrogen sulfate ([emim][HSO 4 ])/ethylene glycol (EG) was selected as the most suitable extractant in the separation process. The m -cresol extraction efficiency and cumene entrainment were 98.1% and 8.3%, respectively, at a [emim][HSO 4 ]:EG molar ratio of 1:2, a temperature of 25 ℃, and a composite extractant: model oil mass ratio of 1:1. Moreover, the viscosity of [emim][HSO 4 ]:EG (1:2) was only 51.8 cP at 25 ℃ and decreased by 95.6% compared with pure [emim][HSO 4 ], which enhanced the mass transfer in the separation process. The [emim][HSO 4 ]:EG (1:2) could be regenerated and reused without significant reduction in separation performance. Finally, [emim][HSO 4 ]:EG (1:2) was applied to separate phenolic compounds from LTCT with a phenol extraction efficiency of more than 99.9% and a neutral oil entrainment of 8.3%, providing a promising prospect for the separation of phenolic compounds.

FLAVONOIDS AND LIGNANS FROM THE LEAVES OF NEPETA MULTIFIDA (LAMIACEAE) AND THEIR BIOAC-TIVITY

A perennial plant Nepeta multifida L. (syn. Schizonepeta multifida (L.) Briq.) is one of the most common species of the Lamiaceae family growing in Eastern Siberia and used in traditional oriental medicine. The chemical composition of N. multifida has not been sufficiently studied. Chromatographic separation of phenolic compounds of N. multifida leaves using column chromatography and preparative HPLC resulted in the isolation of sixteen compounds, including a new flavonoid identified as luteolin-7-O-(3′′,6′′-di-O-acetyl)-β-D-glucopyranoside. Known compounds were O-glycosides of luteolin and apigenin, rosmarinic acid, salvianolic acids A and B, and schizotenuin A. Quantitative analysis of N. multifida leaves by HPLC-UV assay showed the high content of rosmarinic acid (8.36–35.71 mg/g), luteolin-7-O-glucuronide (2.03–14.18 mg/g) and schizotenuin A (5.29–9.56 mg/g). The highest level of phenolic compounds was found in the flowering and fruiting phases. Using Ellman’s spectrophotometric method, it was found that N. multifida leaf extract and some compounds had antiacetylcholinesterase activity, and luteolin glycosides being the most active showed the level of concentration of half-maximal enzyme inhibition (IC50) 29.03–58.36 μg/mL. Thus, as a result of the present study, it was found that the leaves of N. multifida contain various groups of phenolic compounds capable of inhibiting the activity of acetylcholinesterase.

Systematic method of screening deep eutectic solvents as extractive solvents for m-cresol/cumene separation

Deep eutectic solvents (DESs) have been widely applied as extractive solvents for the separation of phenolic compounds from low-temperature coal tar (LTCT). However, systematic study of screening suitable DESs from numerous candidates for this separation process is still scarce. In this work, a systematic method of screening promising DESs as extractive solvents is proposed for the separation of m-cresol/cumene, as a representative phenolic compound/neutral oil mixture in LTCT. Experimental data of DES-involved systems are collected from literature to validate the reliability of conductor-like screening model for real solvents (COSMO-RS), which serves as the foundation for thermodynamic calculation and process simulation. Then, the crucial influencing factors for DESs screening (i.e., salt and solvent, and the molar ratio) on the thermodynamic properties are investigated by COSMO-RS. After that, a systematic DESs screening method combining the calculation of infinite dilution thermodynamic properties, the estimation of melting point and viscosity, the calculation of liquid-liquid equilibria, and the evaluation of process performance is proposed. The results indicate that chlorocholine chloride (CChC): acetic acid (AA) (1:2) and choline chloride (ChCl): ethylene glycol (EG) (1:3) are identified as the optimum DESs for m-cresol/cumene separation. Finally, the high separation performances of CChC:AA (1:2) and ChCl:EG (1:3) are confirmed by extraction experiments.

Membrane diafiltration for enhanced purification of biologically active compounds from goji berries extracts

• The recovery of phenolic compounds from aqueous goji berries extract was investigated. • Three tight ultrafiltration membranes with different cut-off (1, 2.5 and 3.5 kDa) were studied. • Diafiltration was implemented to improve the separation of phenolic compounds from sugars. • Membrane performance was evaluated in terms of productivity and selectivity towards target compounds. • All selected membranes allowed high recovery of phenolic compounds into the retentate. Goji berries represent a valuable source of phenolic compounds with a strong antioxidant and free radical scavenging activity combined to huge quantities of small sugars. This study was aimed at evaluating the potential of three tight ultrafiltration (UF) membranes with molecular weight cut-off (MWCO) from 1.0 to 3.5 kDa in the fractionation of phenolic compounds from sugars in the aqueous extract of dried goji berries. The aqueous extract produced in optimized conditions of water-to-solid ratio and temperature (6.66 mL/g and 65 °C, respectively) was preliminarily clarified by UF in order to remove suspended solids and colloidal particles. A membrane diafiltration (DF) process was developed in order to fractionate phenolic compounds from sugars with selected UF membranes from the clarified extract. The membrane performance was evaluated in terms of productivity and selectivity towards target compounds. All selected membranes allowed high recovery (more than 80%) of phenolic compounds into the retentate. On the other hand, the yield of carbohydrates increased in the permeate by increasing the diafiltration volume. Among the selected membranes, the 2.5 kDa membrane allowed to reduce the concentration of total carbohydrates from 26.5 up to 2.2 g glucose/L (a reduction of 91.7%) in a diafiltration/batch concentration process producing a concentrated extract enriched in phenolic compounds of interest for pharmaceutical or nutraceutical applications.

Extraction and interaction insights for enhanced separation of phenolic compounds from model coal tar using a hydroxyl-functionalized ionic liquid

Phenols are valuable chemicals and widely applied in chemical industry, which have a high content in coal cracking oils. The separation of phenols from coal tar oils is of significance. Usually, the caustic washing technology is adopted in industry, which is environmental unfriendly due to the discharge of a large amount of waste water. This work aims to effectively recover the high-added value phenolic compounds from coal tar oil using m-cresol as a typical phenolic compound by means of a hydroxyl supported ionic liquid N-hydroxyethyl-4-picoline nitrate ([C2OH-4-pic][NO3]). The ionic liquid (IL) ([C2OH-4-pic][NO3]) was synthesized and characterized by 1H NMR. The factors of separation temperature, mass ratio of IL to coal tar model oil, extraction time and coexistent aromatic content in coal tar model oil were investigated. Also, the extraction performance of the prepared IL for the different phenolic components were explored. The separation efficiency (E) of [C2OH-4-pic][NO3] were 98.99% for m-cresol, 98.39% for o-cresol, 98.65% for p-cresol and 99.99% for phenol at 298.15 K with the mass ratio of 1:5 and the extraction time of 30 min. Afterwards, the intermolecular interactions between the IL and m-cresol were investigated by calculating the spatial and radial distribution function, averaged noncovalent interaction and self-diffusivity using molecular dynamics (MD) simulations and the formation of hydrogen bond was validated by FT-IR. The regeneration of [C2OH-4-pic][NO3] was performed and was characterized by 1H NMR. Finally, the separation process was designed based on the above exploration.

Mass transfer kinetics during the extraction of m-cresol from model coal tar using betaine/glycerol deep eutectic solvents

Betaine/glycerol, a common deep eutectic solvent (DES), is an effective extractant used for separating phenolic compounds from model coal tar. Its mass transfer kinetics during extraction is the basis of industrial applications. The physical properties of the model oil and the DES were measured in this study. Then, the modified Lewis cell was used to determine the mass transfer coefficients and extraction rates of the mass transfer kinetics. The effects of the process parameters, including temperature, stirring rate, specific interfacial area, and water quantity of the DES on the kinetics were investigated. In addition, the mechanism of mass transfer kinetics was studied using simulation and experimental studies. The results demonstrate that the physical properties of DES vary greatly with temperature and water quantity, while the physical characteristics of model oil show less variations. The mass transfer coefficient increases and the extraction rate accelerates with increased stirring rate, temperature, and water quantity in the DES. The DES phase functions as the mass transfer resistance area during extraction. An increase in the specific interfacial area did not result in an obvious variation in the mass transfer coefficient, although the extraction rate increased. Finally, results of the simulation and experimental studies showed that the mass transfer kinetics of extraction are controlled by diffusion. Phenolic compounds diffuse from the oil phase into the DES phase and react with DES by forming hydrogen bonds, resulting in the separation of phenolic compounds.

Performance of functionalized ionic liquid with double chemical sites for separating phenolic compounds: mechanism and liquid-liquid behavior studies

Ionic liquids (ILs) are recognized as green solvents in separation field. Many studies have found that the hydrogen bond between anions and solutes plays an important role during the separation process, while the cations in ILs do not. In this work, a functionalized [OHEmim][NO3], 1-hydroxyethyl-3-methylimidazole nitrate, with double chemical sites, is designed for the separation of phenolic compounds (phenol, o-, m-, p-cresol). The hydroxyl group is introduced into the cation as a chemical site. Meanwhile, the anion is also a chemical site. Thus, both the anion and the cation can interact with phenolic compounds. To verify this view, the separation performance of the IL was evaluated by mechanism analysis and liquid-liquid equilibrium behavior. Then, the σ-profiles, bond length, and interaction energy between [OHEmim][NO3] and phenolic compounds are calculated and compared with [Emim][NO3]. The liquid-liquid equilibrium (LLE) data of n-hexane + (phenol, o-, m-, p-cresol) + [OHEmim][NO3] ternary systems were determined. The separation coefficient (S) and distribution coefficient (D) were calculated to evaluate the extraction performance. Non-random two liquid (NRTL) model was adopted to correlate the experimental data, which can provide basic data and parameters for the extraction process design.

Isobaric Vapor–Liquid Equilibria of Binary Systems Containing Cyclohexane for the Separation of Phenolic Compounds from Biomass Fast Pyrolysis Oils

Isobaric Vapor–Liquid Equilibria of Binary Systems Containing Cyclohexane for the Separation of Phenolic Compounds from Biomass Fast Pyrolysis Oils

Effect of pretreatment by supercritical fluids on antioxidant activity of protein hydrolyzate from quinoa (Chenopodium quinoa Willd.).

The effect of two pretreatments on the antioxidant activity was evaluated in quinoa protein hydrolysate, using supercritical CO2 extraction and ethanol as cosolvent, this type of pretreatment was compared to a conventional petroleum ether extraction method without recovery of bioactive compounds. The extractions were carried out at a temperature of 55°C and a pressure of 23 MPa using ethanol (7–8 g quinoa/100 ml); the CO2 mass flow was 35 g/min, the extraction time was 240 min and the particle size was 500 µm, enzyme COROLASE® 7089 was applied for enzymatic hydrolysis, finally ABTS test assessed antioxidant activity. A significant effect was found on the degree of hydrolysis (23.93%) and antioxidant activity (1,181.64 μmol TE/g protein) compared to a conventional method (24.33%) and (1,448.84 μmol TE/g protein). In conclusion, our results suggest that the use of supercritical CO2 and the addition of ethanol as cosolvent are the interesting green technology, to recovery oil and separate phenolic compounds prior to enzymatic hydrolysis to avoid interference with biological activities from quinoa protein hydrolysates, and shows highest antioxidant activity to be incorporate in food products.

Minimizing aromatics entrainment in dephenolization of coal-based liquids by deep eutectic solvents

Reducing the aromatics entrainment during coal-based liquids dephenolization has been investigated by deep eutectic solvents (DESs) as designed. Results showed that aromatics with a chain alkyl group were more easily entrained and phenolic compounds promoted the transfer of aromatics from oil to DESs. Among the DESs investigated, ChCl–glycerol was the best for separation of phenolic compounds from coal-based liquids, having a lower aromatics entrainment. Although adding H2O to ChCl–glycerol reduced the aromatics entrainment, simultaneously suppressed the phenol removal efficiency. A narrow boiling range of phenol oil fraction was benefit for phenols extraction with lower aromatics entrainment. The O–H…π and C–H…π among aromatics and phenolic compounds and/or DESs contributed for the aromatics entrainment, and compounds with specific structures were bound to be entrained.