Phenol Yield Research Articles

Green extraction of active ingredients from finger citron using subcritical water and assessment of antioxidant activity

In this study, subcritical water extraction (SWE) was used to extract active compounds, such as total phenols, total flavonoids, and essential oil, from finger citron. Response surface methodology (RSM) was applied to determine the optimal extraction conditions (total phenols: liquid-to-solid ratio (LSR) 40.9 mL/g, extraction time (ET) 2.7 h, subcritical water temperature (SWT) 183 °C; total flavonoids: LSR 38.8 mL/g, ET 2.4 h, SWT 176 °C; essential oil: LSR 42.3 mL/g, ET 2.5 h, SWT 182 °C). Under these conditions, the extraction yields of total phenols, total flavonoids, and essential oil were 45.65 ± 0.21 mg/g, 33.12 ± 0.19 mg/g, and 4.36 %, respectively. The extracts had remarkable antioxidant activity in vitro, especially those from SWE, which outperformed other methods. For the extracts, the IC50 values for 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, 2,2′-Azinobis-(3-ethylbenzthiazoline-6-sulphonat) (ABTS) radical scavenging, and (2-Phenyl-4,4,5,5-tetramethylimidazoline-3-oxide-1-oxyl) (PTIO) radical scavenging were 0.32 mg/mL, 0.05 mg/mL, and 6.14 mg/mL, respectively. Finger citron essential oil (FCEO) was also analyzed by GC-MS and 37 constituents were identified. The major component was D-limonene at 23.59 %. The essential oil extracted by subcritical water also showed notable antioxidant activity, with IC50 values of 0.97 mg/mL, 0.08 mg/mL, and 5.35 mg/mL for DPPH radical scavenging, ABTS radical scavenging, and PTIO radical scavenging, respectively. These findings show that SWE has a promising potential to extract active compounds from natural products and enhance their biological activity.

A novel Cr-doped CdS/ZnO nanocomposite for efficient photocatalytic hydroxylation of benzene to phenol

In this study, Cr-doped CdS/ZnO (Cr-CdS/ZnO) nanocomposites were synthesized for the first time and systematically characterized using different physicochemical methods, such as XRD, SEM, HRTEM, UV-Vis DRS, XPS, PL, EIS and EPR, etc. The photocatalytic activity of the Cr-CdS/ZnO nanocomposites was evaluated for the hydroxylation of benzene to phenol using H2O2 as the oxidant under visible-light irradiation. The impacts of various reaction conditions, including the role of catalyst dosage, solvents and volume ratio of benzene to H2O2 were specifically investigated. Owing to the similar lattice structure and well-matched band positions of CdS and ZnO, generation of electrons and holes by CdS-captured photons, as well as separation and imigration of electrons to ZnO were all realized. Furthermore, Cr-doping favored the formation of a new trapping level in the band gap of the Cr-CdS/ZnO composite, which would not only enhance visible-light absorption capacity, but also inhibit the rapid recombination of photo-generated electron-hole pairs. As a result, an excellent phenol selectivity of 98% with a phenol yield of 11.1% was achieved, which was higher than those of the pristine Cr-CdS, Cr-ZnO and CdS/ZnO. In the end, a rational mechanism for enhanced photocatalytic activity of the synthesized composites under visible-light irradiation was also proposed. The visible-light absorption and remarkably improved photocatalytic performance for benzene hydroxylation enable the potential of Cr-CdS/ZnO nanocomposites for the application of photocatalytic green synthesis of fine chemicals.

Green subcritical water extraction of Mentha x rotundifolia leaves collected in different annuities

Aim: In this work, the development for the first time of a green and efficient method to obtain bioactive extracts from Mentha x rotundifolia leaves has been investigated. Methods: The efficiency of three techniques [microwave-assisted extraction (MAE), subcritical water extraction (SWE), and ultrasound-assisted extraction (UAE)] was compared in terms of total phenolic content (TPC) and antioxidant activity [1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2’-azino-bis (3-ethylbenzthioazoline-6-sulfonic acid) (ABTS) assays]. Results: Under similar operating conditions, SWE outperformed MAE and UAE for providing M. rotundifolia extracts with improved antioxidant activity. Further in-depth optimization of the SWE method by means of a Box-Behnken experimental design showed 120°C, 5 min, 0.08 g dry sample: 1 mL water and 2 extraction cycles as optimal experimental parameters to provide the maximum yield of phenolics and the highest bioactivity. The application of the developed SWE method to M. rotundifolia leaves collected in different annuities (2014–2017) showed, in general, no significant differences regarding both composition and antioxidant capacity, as expected from plant samples grown in field under drip irrigation conditions. Conclusions: The SWE method here optimized is shown as a sustainable and efficient alternative for providing bioactive M. rotundifolia extracts with application as functional ingredients, natural preservatives, etc. in the food industry, among others.

Biomass catalytic pyrolysis over CaO microspheres: Relationship between the production of bio-oil components and CO2 capture

Biomass catalytic pyrolysis is a promising way for the clean and even “Carbon-Negative” utilization of biomass via the in-situ upgrading bio-oil and reducing the emissions of CO2. In this work, CaO microspheres (CaO-H) prepared via hydrothermal method were used to adsorb CO2 and catalyze the reforming of bio-oil in the pyrolysis process of rice straw (RS) simultaneously. The results showed that CaO-H had the more strong basic sites compared with commercial CaO and thus the better adsorption capacity of CO2 (∼0.5 g/g CaO) at 700 °C and the stronger effect on the generation of bio-oil components and CO2. And strong relationships presented between the formation of CO2 and the composition of bio-oil. The yield of phenols and ketones can be enhanced by 37.17% and 56.76% respectively via the addition of CaO-H at the pyrolysis temperature of 650 °C, companying with the decrease of CO2 yield by 35.13%. It is also inferred that the CO2 reforming of bio-oil and the insertion of CO in CO2 into bio-oil components was strengthened during the biomass pyrolysis over CaO-H especially at the temperature of 650 °C. The possible mechanism of biomass pyrolysis over CaO-H was also proposed.

Gradient Alloyed Quantum Dots for Photocatalytic Lignin Valorization via Proton Coupled Electron Transfer

In the field of photocatalytic lignin valorization, simultaneously fulfilling the requirements of broad light harvesting and strong redox ability has been a key challenge for single binary quantum dot (QD) photocatalyst systems. In order to address the problem, gradient alloyed QDs with funnel-shaped energy structures have been developed. The gradient energy level increases the photon absorption range, while the periphery energy bands at the funnel edge are sufficiently wide to preserve effective redox capacity. In this work, the gradient alloyed QD photocatalyst along with proton donors have been employed in enhancing the efficiency and selectivity of β-O-4 bond cleavage in lignin, realizing yields of target aromatic products phenol and acetophenone to increase up to 70% and 65%, respectively. The mechanism of conversion from the ketone intermediate to target products and how to choose suitable proton donors have been systematically investigated. We propose a proton-coupled electron transfer (PCET) photocatalytic strategy through producing a Cα radical from ketone with the help of acid possessing appropriate bond dissociation free energy (BDFE) and strong electronic transmission facilitating ability. The knowledge acquired in this work is useful for designing photocatalysts and proton donors that can effectively cleave bonds in lignin via the PCET mechanism.

The phenolics, antioxidant activity and in vitro digestion of pomegranate (Punica granatum L.) peels: an investigation of steam explosion pre-treatment.

Pomegranate peels, the main byproduct of pomegranate production, are rich in phenolic compounds that are known for their effective antioxidant properties and have vast application prospects. In this study, steam explosion, an environmentally friendly technique, was applied to pretreat pomegranate peels for phenol extraction. We investigated the effects of explosion pressure, duration, and particle size on the content of total and individual phenolics, and antioxidant activity of pomegranate peels before and after in vitro digestion. The optimal conditions for a steam explosion for pomegranate peels in terms of total phenol content were a pressure of 1.5 MPa, a maintenance time of 90 s, and a particle size of 40 mesh. Under these conditions, pomegranate peel extract presented a higher yield of total phenols, gallic acid, and ellagic acid. However, it also had a lower content of punicalin and punicalagin, compared to the unexploded peels. There was no improvement in the antioxidant activity of pomegranate peels after the steam explosion. Moreover, the content of total phenol, gallic acid, ellagic acid, punicalin, and punicalagin, as well as the antioxidant activity of pomegranate peels, all increased after gastric digestion. Nevertheless, there was a large variation in the pomegranate peel processed by different pressure, duration, and sieve fractions. Overall, this study demonstrated that steam explosion pre-treatment could be an efficient method for improving the release of phenolics, especially gallic acid, and ellagic acid, from pomegranate peels.

Profiling of Active Compounds of Extract Ethanol, n-Hexane, Ethyl Acetate and Fraction Ethanol of Star Anise (Illicium verum Hook. f.) and Determination of Total Flavonoids, Total Phenolics and Their Potential as Antioxidants

Profiling of chemical compounds on star anise extract and fractions showed the content and looked for active compounds. The main compounds in alkaloids, flavonoids, saponins, phenolics, and triterpenoid forms were identified based on phytochemical screening. FTIR and GC-MS analysis were used to purify the extract and fractions’ main compounds. After analyzing the main components of extract and fractions, a correlation was made between the total phenolic and flavonoid content. The total phenolic content was determined by adding folincalteau complexing solution converted to gallic acid equivalent (GAE), while the total flavonoid content was determined by AlCl3 complexing solution converted to Quercetin Equivalent (QE). The total phenolic yields for extract ethanol, n-hexane fraction, ethyl acetate fraction, and fraction ethanol were obtained at 106.45, 52.30, 93.46, and 148.97 mgGAE/g, respectively. Then the total flavonoid results were 107.45, 58.94, 148.99, 140.01 mgQE/g. The total content of phenolics and flavonoids illustrated the number of active compounds that have a role as free radical scavengers due to their group. Antioxidant activity was tested with 1,1-diphenyl-2-picrylhydrazyl (DPPH) on extracts and fractions, with the best IC50 results obtained in the ethanol fraction 0.416 mg/mL.

Dealkylation properties of alkylphenols over hierarchical ZSM-5 synthesized by desilication with TPAOH

In order to improve the catalytic performance of zeolite catalysts in alkylphenol dealkylation, TPAOH was used to introduce mesoporous structure to ZSM-5 zeolite in weak base NH4OH, and the content and dimension of mesoporous were changed by TPAOH concentration. The catalytic activity and lifetime of hierarchical zeolite were studied. The results showed that the phenol selectivity of hierarchical zeolite was slightly reduced, but the phenol yield was relatively stable. Higher TPAOH concentration expanded the introduced mesoporous structure, resulting in increased complexity of the catalytic products, including a certain amount of cresol, xylene, etc. Due to the mesoporous structure, the catalytic stability of hierarchical zeolite ZSM-5-0.3 was most significantly improved. Compared to commercial ZSM-5, the mixed phenol conversion rate of the first recycle reaction increased from 30.7% to 78.2%. By N2 adsorption-desorption tests, it was clear that coke deposition was located in the micropores of zeolite. The formation of mesoporous shortens the diffusion path of reactants in zeolite and thus reduced the formation of coke deposition. ZSM-5 zeolite still had good dealkylation performance in coal tar, and hierarchical zeolite had more significant catalytic stability.

NaOH solution-assisted pyrolysis of waste polycarbonate for co-production of phenolic compounds and supercapacitor material

A green way for the sustainable utilization of waste polycarbonate (PC) was developed, i.e., NaOH solution-assisted pyrolysis to co-produce phenolic compounds and supercapacitor material. A lab-scale setup was employed for the pyrolysis of PC to explore the regulation effects of NaOH concentration and pyrolytic temperature on the production of phenol and 4-isopropenylphenol (IPP). The yields of phenol and IPP were up to 35.3 wt% and 29.9 wt% at 600 °C and NaOH concentration of 0.5 mol/L, which were much higher than those from pure PC pyrolysis (7.2 wt% and 3.6 wt%). Furthermore, the pyrolytic solid residue was directly subjected to the high-temperature activation to prepare activated carbon, which could be used as a supercapacitor material with an outstanding specific gravimetric capacitance of 182.1 F/g at 1 A/g.

Response surface optimization of extraction parameters for enhanced phenolic extraction and antioxidant activity from Cassia fistula flowers

Cassia fistula is a well-known plant species for the medicinal use of it leaves, barks and flowers. It has been identified as a rich source of phenolics which can be attributed to its medicinal properties. However, these phenolics should be extracted appropriately to effectively utilize them in various applications. This study focused on maximizing the extraction yield of total phenolics and total anthocyanins along with maximum 2,2-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity from edible flowers of C.fistula as a function of solid:liquid ratio, ethanol concentration, extraction temperature and time. The data was subjected to response surface methodology and the corresponding second order polynomial models were generated. The results showed that the polynomial models for all responses were significant, did not show lack of fit and presented determination of coefficients above 95%. This indicates the suitability of the models for prediction purposes. Using desirability function, the optimum extraction process parameters to obtain maximum values of all responses was found to be 29.56% ethanol, 1:45 solid to liquid ratio at extraction temperature of 31°C and time 24 minutes. Under these optimal conditions, the experimental values were in close agreement with the predicted values and did not show any significant difference (p<0.05). The identified optimized conditions could be used to extracts phenolics from C.fistula flowers in a cost effective and efficient manner.

Hexaniobate as a Recyclable Solid Base Catalyst to Activate C–H Bonds in Lignin Linkage Boosting the Production of Aromatic Monomers

The targeting cleavage of lignin into value-added aromatic monomers has attracted increasing attention. Although the base-catalyzed depolymerization of lignin has been developed, the use of excess corrosive bases and their poor recyclability limit their industrial implementation. Herein, a catalytic amount of solid base K7HNb6O19 (KNb6) coupled with copper-modified graphitic carbon nitride (Cu/C3N4) shows enhanced catalytic performance for the oxidative cleavage of β-O-4 lignin linkages using molecular oxygen. Due to the synergetic effect between KNb6 and Cu/C3N4, 96% of the β-O-4 ketone model was converted under relatively mild conditions, and phenol (yield: 90%) and other aromatic monomers (yield: 90%) were obtained. Moreover, KNb6–Cu/C3N4 is robust, and its catalytic activity is basically maintained after five cycles. Experimental and theoretical studies (spectroscopic analysis, control experiments, kinetic study, density functional theory calculations, etc.) reveal that the surface basic O atoms of KNb6 can simultaneously activate the Cβ–H bond of β-O-4 ketone to promote the insertion of molecular oxygen, and subsequently, Cu/C3N4 catalyzes the selective cleavage of the Cα–Cβ bond. The catalysts were also active for the oxidative cleavages of other lignin models and oxidized organosolv lignin.

Buckwheat waste depolymerization using a subcritical ethanol solution for extraction of bioactive components: from the laboratory to pilot scale

Buckwheat waste (BW) is rich in bioactive components such as antioxidants and saccharides. To effectively extract these compounds, subcritical ethanol solution treatment (SEST) was conducted from laboratory to pilot scale. Extraction at 80 °C with hot water and ethanol solutions, and at 120 °C with subcritical water and subcritical ethanol solutions were evaluated in laboratory scale. Then, the SEST was scaled up to the pilot level using a batch reactor with a volume scale factor of 1000. Degradation of lignin and dissolution of extractives increased the total phenolics yield. The increase in the temperature led to the degradation of some flavonoid components. Reducing sugars were mainly present as polysaccharides because of the low extraction temperature. Water and ethanol exhibited synergistic effects under subcritical conditions, which resulted in degradation of more lignin and extraction of more bioactive components than hydrothermal extraction, while retaining cellulose and hemicellulose. In the pilot-scale experiment, the total yields of phenolics, flavonoids, and reducing sugars were 29.8 ± 0.1, 13.9 ± 0.5, and 33.9 ± 0.5 g/kg, respectively. The turbidity and Brix values of the liquid samples obtained by SEST were high because of breakdown of the structure of the BW and the dissolution of the bioactive components. Additionally, compared with the laboratory scale, better results were obtained on the pilot scale because of greater feedstock homogeneity and equipment parameters. SEST is a promising approach that could be used on the pilot scale to depolymerize BW and extract bioactive components.

The effect of ferrous sulfate pretreatment on the optimal temperature for production of sugars during autothermal pyrolysis

Fast pyrolysis is a promising technology for producing cellulosic sugars from lignocellulosic biomass. Success in this endeavor requires measures that prevent naturally occurring alkali and alkaline earth metals (AAEM) from breaking pyranose and furanose rings in lignocellulosic biomass. This is especially critical for high ash feedstocks like corn stover and other kinds of herbaceous biomass. Pretreating corn stover with ferrous sulfate converts AAEM into thermally stable salts, which passivates the catalytic activity of these metals and dramatically improves sugar yields. AAEM passivation in combination with autothermal (partial oxidative) operation improves the prospects for intensifying the production of sugars via fast pyrolysis. We hypothesized that pretreated biomass pyrolyzed in the presence of oxygen can substantially influence the temperature dependence of pyrolysis kinetics. We found that autothermal (air-blown) pyrolysis of ferrous sulfate pretreated corn stover achieved maximum sugar yield of 15.6 wt% (biomass basis) at 450 °C, whereas the maximum phenolic oil yield of 9.2 wt% (biomass basis) was reached at 500 °C. Considering these tradeoffs in yields of these highly desirable pyrolysis products, the ideal operating temperature is between 450 and 500 °C. These results suggest that two-stage pyrolysis might allow maximum recovery of both sugars and phenolic oil.

Optimization of low thermal treatments to increase hydrophilic phenols in the Alperujo liquid fraction

Hydrophilic phenols are the main bioactive compounds in alperujo. Among them, 3,4-Dihydroxyphenylglycol (DHPG), Hydroxytyrosol (HT) and Tyrosol (Ty), are the most relevant and deeply studied. These compounds exhibit high antioxidant capacity and a wide range of health benefits as well as technologically promising properties. Given that, their recovery represents an attractive opportunity to valorize this by-product. In this work low thermal treatments were applied to alperujo in order to obtain phenol-enriched liquid fractions. Optimization assays combining different levels of temperature (30 to 90 ºC), time (60 to 180 min) and water content (70 to 90%), followed by response surface methodologies were performed. The results indicated that by applying optimal conditions, is possible to obtain theoretical yields of Total phenols, DHPG, HT and Ty of 2.4, 957.8, 3.4 and 6.4 times greater, respectively, than raw dry alperujo. Interestingly, all the evaluated conditions can be reproduced with low investment in a standard olive oil industry.

Bioactivity of non-extractable phenolics from lemon peel obtained by enzyme and ultrasound assisted extractions

Lemon peel waste constitutes a natural resource for bioactive phenolics with antioxidant, antihypertensive and antidiabetic activities. Bioactivities of non-extractable phenolics from lemon peel obtained by conventional heat-, enzyme-, ultrasound-, and ultrasound-enzyme-assisted extractions were evaluated in comparison with those of extractable phenolics. The antioxidant, angiotensin-I-converting enzyme (ACE), and α-amylase inhibitory activities and phenolic profile of the phenolic fractions were analysed. While the extractable fraction had higher total phenolic content, ascorbic acid content, and antioxidant activity, phenolic profile analysis indicated that the non-extractable fraction contained higher concentrations of phenolics especially hesperidin and hesperetin. The concentrations of hesperidin and hesperetin in the non-extractable fraction were 270.9 mg/100 g dry weight and 415.9 mg/100 g dry weight, respectively, which were about two-fold higher than those present in the extractable fraction. Moreover, ACE and α-amylase inhibitory activities of non-extractable fraction were stronger than those of the extractable fraction. Total phenolic content, total flavonoid content, and antioxidant activity were increased by enzyme and ultrasound treatments compared to those by conventional heat treatment. However, ACE inhibitory activities of all non-extractable fractions were similar while α-amylase inhibitory activity was higher in ultrasound- and ultrasound-enzyme-treated fractions. While ultrasound-assisted extraction slightly improved the yield of non-extractable phenolics, enzyme-assisted extraction yielded two-to four-fold increases in the amounts of phenolic compounds compared to heat-assisted extraction. Non-extractable phenolic fraction from lemon peel was found to have a significant potential as an antihypertensive and antidiabetic agent.

Valorization of kaffir lime peel through extraction of essential oil and process optimization for phenolic compounds

AbstractBACKGROUNDKaffir lime peel is a food waste which contains good aromatic essential oil and phenolic compounds. Extraction of essential oil from kaffir lime peel is conducted to obtain the extract for using as biological ingredients in various products. After essential oil extraction, kaffir lime peel residue has been remained, and it can be considered as another by‐product. Therefore, it is interesting to evaluate the contents of phenolic compounds in the kaffir lime peel residue to understand the possibility of valorization of kaffir lime peel wastes at a practical level. In this study, extraction of essential oil from fresh kaffir lime peel was conducted by hydrodistillation, and phenolic compounds were extracted from the kaffir lime peel residue by process optimization of an ethanolic extraction method.RESULTSThrough hydrodistillation and gas chromatography–mass spectrometry analysis, essential oil of kaffir lime peel contained terpinene‐4‐ol (19%), β‐pinene (15.8%) and d‐limonene (15.6%) as the major volatile compounds. In extraction of phenolic compounds from kaffir lime peel residue, all investigated parameters had significant linear effects on the yield of phenolic compounds, but no interaction effects among the extraction parameters were observed. Optimal conditions for the extraction were 120 min, 60 °C and 1:20 g mL−1, resulting in phenolic compounds of 8.6 mg GAE g−1 sample. The phenolic compound yield extracted from fresh kaffir lime peel at the optimal conditions was close to that extracted from the kaffir lime peel residue.CONCLUSIONSThrough hydrodistillation, only essential oil was extracted from kaffir lime peel, while phenolic compounds are still remained in the solid residue of the kaffir lime peel at high concentration as the fresh sample. Results of this study are useful for maximizing extraction yield of phenolic compounds from kaffir lime peel. The results of this study also revealed the possibility of maximizing the utilization of kaffir lime peel wastes at the practical stage through extraction of both essential oils and phenolic compounds. © 2023 Society of Chemical Industry (SCI).

Box-Behnken design based optimization of phenolic extractions from Polygonum equisetiforme roots linked to its antioxidant and antibacterial efficiencies

PurposeThePolygonum equisetifomeis a prospective plant source of high protein, unsaturated fatty acids, and useful safe bioactive molecules. Therefore, the aim of this study was to optimize the ultrasonic aqueous extraction of phenols fromP. equisetifomeroots using Box-Behnken design based statistical modeling, and to evaluate the antioxidant and antibacterial efficiencies ofP. equisetifomeroot extracts against pathogenic bacteria.MethodsIn this study, the box-behnken design was used to optimize the extraction of phenols. The extraction temperature (30–70°C), ultrasound assisted extraction (UAE) time (1–9 min), and liquid-solid ratio (35–45 mL/g) were investigated as the factors that influence the phenolic yield (Y1) and their DPPH (1,1-diphenyl-2-picrylhydrazyl) scavenging activity (Y2).ResultsThe optimal conditions for both responses were 50°C, 5 min, and 40 mL/g. At these conditions, Y1 reached its maximum to be 45.321 mg GAE/g dry weight and Y2 to be 120.354 μmol Trolox/g dry weight. TheP. equisetifomeroots contained water soluble phenol, high anthocyanin, and condensed tannins. Interestingly, theP. equisetifomeextracts showed a relation to its antioxidant and antibacterial activities, FRAP (Ferric-reducing/antioxidant power), and ABTS scavenging activity were determined. The morphological and physico-chemical features of the extract were analyzed using SEM-EDX, FT-IR, and minimum inhibitory concentration (MIC) was analyzed against several pathogenic bacteria. The antibacterial activity of the extract showed that the extract is more efficient against Staphylococcus aureus, while theP. equisetifomeextracts showed efficient MIC againstS. aureus, followed by Bacillus cereus.SuggestionsThe relation ofP. equisetifomeextracts to its antioxidant, and antibacterial efficiencies open a new avenue of their potential uses in the food and pharmaceutical industries.

Mass transfer study of phenolic compound liquid-liquid extraction process from bio-oil of coffee shell pyrolysis product

Coffee shells are one of the potential renewable materials used in the pyrolysis process to produce bio-oil. However, the amount of phenolic compounds, which is roughly 36.74%, is one of the primary drawbacks of using coffee shell bio-oil as a fuel source. Only a little amount of research has been done on the mass transfer modeling and phenomena of phenol extraction from coffee shell bio-oil. The objectives of this study are to identify the best extraction circumstances, ascertain the empirical correlation of total mass transfer, and produce the empirical correlation of Sherwood number, which can be used to characterize the role of variables in this mass transfer process. The ratio of impeller diameter to tank diameter and the Sherwood number, as well as Reynolds, Schmidt, Weber, dispersed phase holdup, were studied as dimensionless numbers. This study used liquid–liquid extraction process at the temperature of 50 ℃, with chloroform–methanol 80% as a solvent with ratio of 2:1 v/v and use bio-oil to solvent ratio of 1:1 v/v. The extraction time has an interval of 30 min (20, 50, 80, 110 min), with varied impeller diameter (3.5 cm and 4 cm), vessels diameter (9 cm and 10 cm) and mixing speed (250 rpm, 300 rpm, 350 rpm). According to the findings, the greatest phenol yield was obtained at impeller diameter 3.5 cm, tank diameter 9 cm, and mixing speed 300 rpm, with a distribution coefficient of 0.848. The results demonstrate that the maximum overall mass transfer coefficient is 4.096 × 10-4 m/s and that the liquid diffusivity is 1.7965 × 10-9 m2/s. The equation model from this study could be applied to a liquid–liquid extraction process that is scaled up to extract more phenolic compounds from the the produced bio-oil.

Phytochemicals Recovery from Grape Pomace: Extraction Improvement and Chemometric Study.

In the last 20 years, an increased interest has been shown in the application of different types and combinations of enzymes to obtain phenolic extracts from grape pomace in order to maximize its valorization. Within this framework, the present study aims at improving the recovery of phenolic compounds from Merlot and Garganega pomace and at contributing to the scientific background of enzyme-assisted extraction. Five commercial cellulolytic enzymes were tested in different conditions. Phenolic compound extraction yields were analyzed via a Design of Experiments (DoE) methodology and a second extraction step with acetone was sequentially added. According to DoE, 2% w/w enzyme/substrate ratio was more effective than 1%, allowing a higher total phenol recovery, while the effect of incubation time (2 or 4 h) variation was more enzyme-dependent. Extracts were characterized via spectrophotometric and HPLC-DAD analyses. The results proved that enzymatic and acetone Merlot and Garganega pomace extracts were complex mixtures of compounds. The use of different cellulolytic enzymes led to different extract compositions, as demonstrated using PCA models. The enzyme effects were observed both in water enzymatic and in the subsequent acetone extracts, probably due to their specific grape cell wall degradation and leading to the recovery of different molecule arrays.

Selective hydrogenolysis of lignin in the presence of Ni3Fe1 alloy supported on zirconium phosphate

Lignin is a promising renewable starting material for various value-added petrochemicals and high-quality fuels. However, current techniques for utilization of this natural aromatic biopolymer are challenging by the poor selectivity of desired products and the serious char formation. In this study, we provide a novel and efficient approach for selective hydrogenolysis of lignin using the cost-effective catalyst of Ni3Fe1 nanoparticles supported on zirconium phosphates. 77.0 % of lignin is converted, yielding 19.6 % monophenols, whereas, the formation of biochar is insignificant (1.7 %) at the conditions of 260 °C for 5 h in a 2.0 MPa hydrogen. Importantly, 42.1 % of these obtained monophenols are identified to be a versatile bulk chemical of para ethyl phenol (yield of 8.2 %), because of the selective cleavage of the p-coumaryl units of the lignin. The results of catalyst characterization further reveal that the formation of Ni3Fe1 nanoparticle facilitates the breakage of the specific structure of lignin and suppresses the phenolic oligomer's recondensation, which consequently enhance the lignin hydrogenolysis and char inhibition. These insights unveil that the production of bulk chemicals from sustainable resources is realizable through the rational design of catalytic processes, which substantially increase the economic feasibility of biomass biorefinery.