Phenol Recovery Research Articles

Optimization of ultrasonic and microwave-assisted extraction with natural deep eutectic solvents for enhanced recovery of phenolics and terpenoids from celery leaves

Optimization of ultrasonic and microwave-assisted extraction with natural deep eutectic solvents for enhanced recovery of phenolics and terpenoids from celery leaves

Efficient Electrocatalytic Hydrodechlorination and Detoxification of Chlorophenols by Palladium-Palladium Oxide Heterostructure.

Electrocatalytic hydrodechlorination is a promising approach for simultaneous pollutant purification and valorization. However, the lack of electrocatalysts with high catalytic activity and selectivity limits its application. Here, we propose a palladium-palladium oxide (Pd-PdO) heterostructure for efficient electrocatalytic hydrodechlorination of recalcitrant chlorophenols and selective formation of phenol with superior Pd-mass activity (1.35 min-1 mgPd-1), which is 4.4 times of commercial Pd/C and about 10-100 times of reported Pd-based catalysts. The Pd-PdO heterostructure is stable in real water matrices and achieves selective phenol recovery (>99%) from the chlorophenol mixture and efficient detoxification along chlorophenol removal. Experimental results and computational modeling reveal that the adsorption/desorption behaviors of zerovalent Pd and PdO sites in the Pd-PdO heterostructure are optimized and a synergy is realized to promote atomic hydrogen (H*) generation, transfer, and utilization: H* is efficiently generated at zerovalent Pd sites, transferred to PdO sites, and eventually consumed in the dechlorination reaction at PdO sites. This work provides a promising strategy to realize the synergy of Pd with different valence states in the metal-metal oxide heterostructure for simultaneous decontamination, detoxification, and resource recovery from halogenated organic pollutants.

Enhancing phenolic compounds recovery from Arnica montana L. flowers through optimized green extraction protocols

Enhancing phenolic compounds recovery from Arnica montana L. flowers through optimized green extraction protocols

Exergy analysis of process configurations for phenol recovery from wastewater

Wastewater with high phenol content, primarily generated by the petrochemical, coal, oil, and gas industries, must be treated before disposal to meet global regulations and prevent environmental harm. Liquid-liquid extraction is a well-studied method employed to address this need. Despite the extensive focus on to energy performance, exergy analysis has not yet been incorporated. Therefore, this study aims to compare four process configurations by integrating an exergetic approach with economic and emissions analyses to quantify thermodynamic efficiency, total annual cost, and CO2 emissions. Process simulations were conducted using Aspen Plus V.12, and the economic analysis was performed using the Aspen Process Economic Analyzer. The input streams of all configurations were 100 ton/h of wastewater containing 275 kg/h of phenol and 266 kg/h of hydroquinone, with pure methyl iso-butyl ketone (MIBK) as the makeup solvent. Extraction and mixing exhibited the lowest exergy destruction, while distillation accounted for approximately 55 % of the total exergy destruction. Configurations that incorporated direct medium-pressure steam input resulted in greater exergy destruction, leading to reduced exergy efficiency, but a lower total annual cost. The most economical configuration was achieved by heat integration of De Dietrich® process with low-pressure steam (C-IE lps), benefiting from exergy analysis insights. The exergy efficiency of this configuration increased from 33 % to 38 %, and the total annual cost decreased by 183 thousand USD per year compared to the initial De Dietrich® process (configuration C). Similarly, CO2 emissions were reduced to the lowest level, reaching 4.87 kg CO2 /h.

Technological Advancements and Prospects for Near-Zero-Discharge Treatment of Semi-Coking Wastewater

This review examines the technological bottlenecks, potential solutions, and future development directions in the treatment and resource utilization of semi-coking wastewater (SCOW) in China. By comprehensively investigating the semi-coking industry and analyzing wastewater treatment research hotspots and existing projects, this study systematically explores the current status and challenges of each treatment unit, emphasizing the necessity for innovative wastewater treatment technologies that offer high efficiency, engineering feasibility, environmental friendliness, and effective resource recovery. This review highlights prospects and recommendations, including the development of novel extractants for phenol and ammonia recovery, a deeper understanding of biological enhancement mechanisms, exogenous bio-enhancement materials, and the creation of cost-effective advanced oxidation process (AOP)-based combined processes. Additionally, it underscores the potential for repurposing SCOW as a valuable resource through appropriate treatment, whether recycling for production or other applications.

Development and application of metal–organic frameworks and spherical carbon particles for efficient recovery of phenols and oils from coal chemical wastewater: A new full-process adsorption treatment mode

To address the challenges of high energy consumption and low efficiency in recovering phenols and oils from coal chemical wastewater (CCW), this study focused on the design and synthesis of metal–organic frameworks and spherical carbon particle (MOFs/SCP) adsorbents with a high adsorption capacity and ease of desorption. Additionally, a new comprehensive treatment mode named “adsorption-desorption-regeneration-recovery” (ADRR) was developed to efficiently recover phenols and oils from CCW. The results revealed that the ADRR treatment mode maintained high adsorption and desorption efficiencies of MOFs/SCP, which remained consistently above 95 %. Additionally, methanol regeneration reached ∼ 90 %, and the recovery efficiency of phenols and oils was ∼ 83 %. The analysis of the adsorption behavior model indicated that the adsorption of phenols and oils by MOFs/SCP mainly involved monolayer chemical adsorption characterized by spontaneity, heat absorption, and disorder. The dynamic adsorption model exhibited a strong correlative ability to predict and assess the adsorption capacity, rate, equilibrium, and operating parameters. Finally, structural analyses and molecular dynamics simulations revealed that the micro-interaction mechanisms between MOFs/SCP and phenols and oils mainly depended on the distinctive hydrophobic nature and porous adsorption capabilities of MOFs/SCP. These interactions were mainly facilitated by electrostatic interactions, π–π interactions, and hydrogen bonding. The findings of the study are crucial for achieving high-value recovery of phenols and oils from CCW and, promoting the clean and sustainable growth of the coal chemical industry.

Selective Phenolics Recovery from Aqueous Residues of Pyrolysis Oil through Computationally Designed Green Solvent

Selective Phenolics Recovery from Aqueous Residues of Pyrolysis Oil through Computationally Designed Green Solvent

Solid-State Fermentation for Phenolic Compounds Recovery from Mexican Oregano (Lippia graveolens Kunth) Residual Leaves Applying a Lactic Acid Bacteria (Leuconostoc mesenteroides)

The Mexican oregano by-products are a source of bioactive molecules (polyphenols) that could be extracted using solid-state fermentation (SSF). This study fermented the by-products via SSF (120 h) with a lactic acid bacteria (LAB) Leuconostoc mesenteroides. Sequentially, a bioactive and chemical determination was made according to the phenolic content, antioxidant activity (DPPH●/FRAP), bioactive properties (α-amylase inhibition and antimicrobial activity against Escherichia coli), and chemical composition (HPLC-MS). The results showed that the total phenolics and flavonoid content, as well as the antioxidant activity, increased (0.60, 2.55, and 3.01 times, respectively) during the SSF process compared with unfermented material. Also, the extracts showed antimicrobial activity against E. coli and α-amylase inhibition. These inhibitory results could be attributed to bioactive compounds identified via HPLC, such as gardenin B, trachelogenin, ferulic acid, and resveratrol 3-O-glucoside. Therefore, the application of L. mesenteroides under SSF on oregano by-products comprises an eco-friendly strategy for their valorization as raw materials for the recovery of phenolic compounds that could be natural alternatives against synthetic antioxidant and antimicrobial agents, promoting a more circular and sustainable supply system within the oregano industry.

Padina gymnospora biorefinery: coalescing ultrasonic-assisted phenolic recovery and citric acid–mediated alginate extraction

Padina gymnospora biorefinery: coalescing ultrasonic-assisted phenolic recovery and citric acid–mediated alginate extraction

Eco-friendly solvent-based liquid-liquid extraction of phenolic acids from winery wastewater streams

This study proposes liquid-liquid extraction (LLE) for the recovery of phenolic acids from winery wastewater replacing common volatile organic compounds (VOCs) with environmentally friendly solvents. On one hand, terpenes (α-pinene and p-cymene) and terpenoids (eucalyptol and linalool) were selected as green solvents and compared to common VOCs (ethyl acetate or 1-butanol). On the other hand, gallic acid (GA), vanillic acid (VA), syringic acid (SA) and caffeic acid (CA) were selected as phenolic acids to be recovered. The extraction performance was evaluated under different operation conditions: solvent-to-feed ratio, initial concentration of phenolic acids and temperature.This work also evaluated the back-extraction whole process global recovery and solvent regeneration, by means of aqueous NaOH solution. Eucalyptol has shown the highest overall global extraction performance (21.07 % for GA, 93.21 % for VA, 78.79 % for SA, and 80.57 % for CA) and lower water solubility compared to the best performing VOC solvent (1-butanol). Therefore, eucalyptol can be a potential eco-friendly solvent to replace VOCs for sustainable phenolic acid recovery from winery wastewater. Finally, to ensure a clean water stream after the LLE, the traces of solvent were completely removed by electrooxidation with boron-doped diamond anode at a current density of 422.54 A/m2.

Screening factors to affect ultrasound-assisted extraction of (poly)phenols from date palm seeds.

The aim of the current work was to compare the (poly)phenol profile (free, soluble-conjugate, and insoluble-bound) and antioxidant activity of date palm seed flour using different extraction methods (conventional vs. ultrasound-assisted extraction [UAE]) and to determine the most critical variables in the extraction of (poly)phenols through UAE using the Plackett-Burman design experiment. Using the Plackett-Burman design, seven factors, namely, ethanol concentration, liquid:solid ratio (mL/g), sonotrode, amplitude (%), extraction time, extractant pH, and extraction cycle, were studied. After the factors were studied using conventional extraction methods, 23 compounds were quantified, with protocatechuic acid and catechin being the predominant (poly)phenols. Furthermore, the distribution of (poly)phenols within the cell varied, with glycosylated quercetins and caffeoyl shikimic acids predominantly found in free forms. Ultrasound-assisted extraction demonstrated efficiency in extracting free and soluble-conjugate (poly)phenols. However, it showed limitations in extracting insoluble-bound (poly)phenols. Nevertheless, similar amounts of total (poly)phenols were shown after conventional extraction and UAE, that is, 259.69 ± 43.54 and 189.00 ± 3.08mg/100g date seed flour, respectively. The Plackett-Burman design revealed the liquid-solid ratio as a crucial factor affecting (poly)phenol extraction, with higher ratios yielding better results. The sonotrode choice also influenced the extraction efficiency, highlighting that the sonotrode with a smaller diameter but higher displacement amplitude showed the best polyphenol recovery and antioxidant activity values. The nature of (poly)phenols influenced the studied extraction variables differently, emphasizing the complexity of the extraction process. In this line, pure water was sufficient to extract flavan-3-ols after UAE, whereas ethanol was a crucial factor in extracting quercetin. These findings underscore the importance of optimizing extraction methods for maximizing (poly)phenol recovery from date palm seed flour for various applications in food and pharmacology industries.

Natural deep eutectic solvents-based concurrent approach for qualitative and quantitative enhancement of Rosa damascena essential oil and recovery of phenolics from distilled rose petals

In pursuit of adopting environment friendly methodologies to amplify essential oil (EO) yield of industrially important aromatic plants, enrichment of bioactive content in distillation waste, and to establish the recovery process for the enriched product; this study employed natural deep eutectic solvents (NADESs) as cosolvent in the conventional hydro distillation method using Rosa damascena Mill L (Damask rose) petals as biomass. R. damascena is one of the most important species of Rosaceae family known for producing high-valued rose EO [often termed as “liquid gold”] but with very low yield. Herein, nine NADESs were used as cosolvent along with conventional hydro distillation method which led to 1.7 times EO yield enhancement (retention of EO quality as per ISO guidelines) using NADES-4 [choline chloride: glycerol (1:1)] as cosolvent. Further, to sustainably utilize the residue (otherwise waste) left after hydro distillation, hydrolate (aqueous part left in the flask) and spent (dried solid waste) were analyzed with UHPLC to determine targeted phenolics compounds. All the samples (EO, dried hydrolate, and spent) were also evaluated for in-vitro antioxidant activity using DPPH-radical scavenging assay, which revealed that hydrolate obtained by using NADES-5 [choline chloride: glucose (5:1)] showed the highest activity (IC50 0.85 µg/mL) as compared to ascorbic acid (IC50 5.40 µg/mL). Hence, the present study provides a green protocol for enhancing rose EO yield with phenolics-enriched antioxidant byproducts.

Stability of Propolis Phenolics during Ultrasound-Assisted Extraction Procedures.

Propolis has gained popularity in recent years as a potential preventive and therapeutic agent due to its numerous health benefits, which include immune system boosting, blood pressure lowering, allergy treatment, and skin disease treatment. The pharmacological activity of propolis is primarily attributed to phenolics and their interactions with other compounds. Given that phenols account for most of propolis's biological activity, various extraction methods are being developed. The resin-wax composition of the propolis matrix necessitates the development of an extraction procedure capable of breaking matrix-phenol bonds while maintaining phenol stability. Therefore, the aim of this study was to assess the stability of two major groups of phenolic compounds, flavonoids and phenolic acids, in propolis methanol/water 50/50 (v/v) extracts obtained after ultrasound-assisted extraction (USE) under different extraction parameters (extraction time and pH) and heat reflux extraction (HRE). The methodology involved varying the USE parameters, including extraction time (5, 10, and 15 min) and pH (2 and 7), followed by analysis using liquid chromatography-tandem mass spectrometry (LC-MS/MS) to quantify phenolic recoveries. Results revealed that benzoic acid and chlorogenic acid derivatives demonstrated excellent stability across all ultrasound extraction procedures. The recoveries of flavonoids were highly diverse, with luteolin, quercitrin, and hesperetin being the most stable. Overall, neutral pH improved flavonoid recovery, whereas phenolic acids remained more stable at pH = 2. The most important optimization parameter was USE time, and it was discovered that 15 min of ultrasound resulted in the best recoveries for most of the phenols tested, implying that phenols bind strongly to the propolis matrix and require ultrasound to break the bond. However, the high variability in phenol extraction and recovery after spiking the propolis sample shows that no single extraction method can produce the highest yield of all phenols tested. As a result, when working with a complex matrix like propolis, the extraction techniques and procedures for each phenol need to be optimized.

Valorization of Olive Pomace Using Ultrasound-Assisted Extraction for Application in Active Packaging Films.

Bioactive compounds that can be recovered by the solid wastes of the olive oil sector, such as polyphenols, are known for their significant antioxidant and antimicrobial activities with potential application in nutraceutical, cosmetic, and food industries. Given that industrial demands are growing, and the polyphenol market value is ever increasing, a systematic study on the recovery of natural antioxidant compounds from olive pomace using ultrasound-assisted extraction (UAE) was conducted. Single-factor parameters, i.e., the extraction solvent, time, and solid-to-liquid ratio, were investigated evaluating the total phenolic content (TPC) recovery and the antioxidant activity of the final extract. The acetone-water system (50% v/v, 20 min, 1:20 g mL-1) exhibited the highest total phenolic content recovery (168.8 ± 5.5 mg GAE per g of dry extract). The olive pomace extract (OPE) was further assessed for its antioxidant and antibacterial activities. In DPPH, ABTS, and CUPRAC, OPE exhibited an antioxidant capacity of 413.6 ± 1.9, 162.72 ± 3.36 and 384.9 ± 7.86 mg TE per g of dry extract, respectively. The antibacterial study showed that OPE attained a minimum inhibitory activity (MIC) of 2.5 mg mL-1 against E. coli and 10 mg mL-1 against B. subtilis. Hydroxytyrosol and tyrosol were identified as the major phenolic compounds of OPE. Furthermore, active chitosan-polyvinyl alcohol (CHT/PVA) films were prepared using different OPE loadings (0.01-0.1%, w/v). OPE-enriched films showed a dose-dependent antiradical scavenging activity reaching 85.7 ± 4.6% (ABTS) and inhibition growth up to 81% against B. subtilis compared to the control film. Increased UV light barrier ability was also observed for the films containing OPE. These results indicate that OPE is a valuable source of phenolic compounds with promising biological activities that can be exploited for developing multifunctional food packaging materials.

Green and sustainable techniques to increase the extraction of phenolic compounds from turnip greens by‐products

AbstractThe work was aimed to optimize extraction and recovery of phenolics from turnip greens by‐products using eco‐sustainable techniques based on the use of microwaves, ultrasound, or enzymes and of water as solvent. The optimization of ultrasound‐ and microwave‐assisted extractions was performed using a 4‐factors/3‐levels and a 3‐factors/3‐levels Box–Behnken Design (BBD), respectively and the results of the corresponding trials were fitted to a second order polynomial model. The enzymatic extractions were performed using three different commercial enzymatic preparations, optionally combined with an ultrasound treatment carried out according to the central values of the BBD design. The best results obtained from each green technique were compared with those of the conventional solid–liquid extraction performed with a 70% ethanol aqueous solution. Regarding ultrasounds, the conditions able to maximize the total phenolic concentrations of the extracts (solid–water ratio, 50 g/L; T, 45°C; t, 40 min; power, 24 W) increased the extraction efficiency by about 75% and reduced the extraction times from 2 h to 10 min with respect to the conventional extraction. Concerning microwaves, the optimized conditions (solid‐water ratio, 75 g/L; t, 3 min; power, 160 W) allowed the increase of the extraction efficiency by about 48% and the decrease of the extraction times to just a few minutes. For both techniques, the factor that mainly affected extraction yield and antioxidant activity were “solids‐to‐solvent ratio” and “power,” respectively. According to the results of the enzymatic treatments, the best extraction was that performed with the commercial mix of pectinlyase, polygalacturonase, pectinesterase, and arabinase, which had the same extraction efficiency of microwaves but required longer times (90 min). Furthermore, the combination with ultrasounds did not improve its performances. Extraction technique also affected the phenolic profiles in terms of number and concentration of compounds identified. In conclusion, ultrasounds and microwaves are the best treatments to maximize extraction yield (the first) and minimize extraction time (the second).Practical applicationsThis study presents an approach to the sustainable recovery of phenolics contained in vegetable by‐products that can be adapted to a variety of food waste. It also supplies an overview of the extraction technique efficiency. The industrial adoption of our findings can lead to the following advantages: reduction food waste and/or remove from it compounds that can alter the ecosystem balance; reduction of disposal cost; production of precious ingredients for functional foods/natural cosmetics/natural supplements; obtainment of a new source of income by creating a further activity that can run in parallel with the main production of the company and can serve to diversify investments; improvement of the green image of the company, especially if the energy necessary to the energy needed to power the new process is obtained from renewable sources.

Natural deep eutectic liquid and ultrasound-assisted extraction of milk thistle phenolics and their hepatoprotective activities

IntroductionThe present research describes the utilization of natural deep eutectic solvent in combination with ultrasound for the extraction of milk thistle polyphenols. The extracts obtained under different conditions were evaluated for their in vitro antioxidant activities and hepatoprotective activities in Albino mice (in vivo).MethodsThe extraction parameters involving liquid-to-solid ratio (S/L), ethanol-to-natural deep eutectic solvent ratio (EtOH/DES), extraction time (t), and ultrasound treatment time were investigated and optimized to enhance the recovery of bioactives, their phenolic content, Trolox equivalent antioxidant capacity (TEAC), and radical scavenging capacity (RSC).Results and discussionsThe extraction of milk thistle polyphenols using glucose/citric acid (1:1)-based natural deep eutectic liquid coupled with ultrasound for 1.0 min under an S/L of 6.2, EtOH/DES 9, and extraction time of 120.8 min offered 35.89 ± 2.29 g/100 g of crude extracts, which were three-fold higher than that by conventional solvent extraction (CSE). Each gram of milk thistle extracts thus obtained comprised 377.93 ± 6.17 mg GAE of TPC and exhibited 298.70 ± 3.06 μmol TEAC and 93.16 ± 0.58 percent inhibition of DPPH free radicals. In addition, the administration of milk thistle extracts obtained as given above at 25 mg/Kg body weight in Albino mice significantly (p ≤ 0.05) improved the liver function parameters at the end of treatment (7 days).ConclusionOverall, it was observed that NaDES in combination with medium-level ultrasound energy (700 watt) might work as a sustainable choice to enhance the recovery of bioactive phenolics from milk thistle powder without compromising their antioxidant and hepatoprotective potential.

Investigation of phenolic compounds recovery from brewery wastewater with coupled membrane and adsorption process

Recovery of phenolic compounds from food-processing by-products represents an interest for various industrial sectors. The potential of a coupled ultrafiltration and adsorption or ion exchange resin process was analyzed to recover phenolic compounds from a brewery liquid residue. Ultrafiltration yielded a 95% removal of turbidity-causing compounds without significant modification of the chemical composition of brewery by-products. After a pH optimization step, ten different macroporous resins, including MN202, SP700, HP2MGL, LXA8302, LWT510, XAD16N, FPX66, WA20, WA30 and SCAV4, were screened for phenolic compounds sorption. Resins were selected through a multi-step batch test procedure according to their performance in phenolic compounds adsorption capacity, phenolic compounds selectivity compared to carbohydrates and price. The strong base resin SCAV4 with OH- counter ion showed the highest adsorption capacity, 35.4 ± 0.8 mg·gdryresin−1, with selective sorption of phenolic compounds. Higher temperatures of 48 °C improved the adsorption and desorption performances of LXA8302 and SCAV4 resins, compared to 25 °C. Up to 70% of phenolic compounds were desorbed from adsorption resin with adequate solvent.

Production of cost-competitive bioethanol and value-added co-products from distillers' grains: Techno-economic evaluation and environmental impact analysis

Here, Baijiu distillers' grains (BDGs) were employed in biorefinery development to generate value-added co-products and bioethanol. Through ethyl acetate extraction at a 1:6 solid–liquid ratio for 10 h, significant results were achieved, including 100 % lactic acid and 92 % phenolics recovery. The remaining BDGs also achieved 99 % glucan recovery and 81 % glucan-to-glucose conversion. Simultaneous saccharification and fermentation of remaining BDGs at 30 % loading resulted in 78.5 g bioethanol/L with a yield of 94 %. The minimum selling price of bioethanol varies from $0.149–$0.836/kg, contingent on the co-product market prices. The biorefinery processing of one ton of BDGs caused a 60 % reduction in greenhouse gas emissions compared to that of the traditional production of 88 kg corn-lactic acid, 70 kg antioxidant phenolics, 234 kg soybean protein, and 225 kg corn-bioethanol, along with emissions from BDG landfilling. The biorefinery demonstrated a synergistic model of cost-effective bioethanol production and low-carbon emission BDGs treatment.

Semi-batch extraction of phenolic compounds from Rosmarinus officinalis: Kinetic study and dimensionless modeling

A transient and one-dimensional mathematical model with two partial differential equations is developed to simulate the extraction of de-oiled rosemary plant in a vertical fixed-bed reactor. The effect of the dimensionless numbers which appear in the final governing equations (Peclet and Damköhler numbers) is studied. The influence of solvent composition, solid particle size and temperature is also investigated. The process is controlled by internal diffusion effects, with the smallest particle size exhibiting the smallest internal diffusion coefficient. Among the different solvents, 80% ethanol shows the highest total phenolics recovery. The antiradical activity is also enhanced by increasing the temperature and the smaller particle size leads to an improvement in the extraction selectivity. Peclet number has a small effect on the results, while Damköhler number strongly affects the process. An increase in bed porosity causes a significant increase in the internal diffusion time.

Enzyme-Assisted Coextraction of Phenolics and Polysaccharides from Padina gymnospora.

Brown seaweed is a promising source of polysaccharides and phenolics with industrial utility. This work reports the development of a green enzyme-assisted extraction method for simultaneously extracting polysaccharides and phenolics from the brown seaweed Padina gymnospora. Different enzymes (Cellulast, Pectinex, and Alcalase), individually and in combination, were investigated, with Alcalase alone showing the highest efficiency for the simultaneous extraction of polysaccharides and phenolics. Yields from Alcalase-assisted aqueous extraction were higher than those obtained using either water alone or conventional ethanol extraction. Alcalase-assisted extraction was subsequently optimized using a response surface methodology to maximize compound recovery. Maximal polysaccharide and phenolic recovery was obtained under the following extraction conditions: a water-to-sample ratio of 61.31 mL/g, enzyme loading of 0.32%, temperature of 60.5 °C, and extraction time of 1.95 h. The extract was then fractionated to obtain alginate-, fucoidan-, and phenolic-rich fractions. Fractions exhibited potent 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity with IC50 values of 140.55 µg/mL, 126.21 µg/mL, and 48.17 µg/mL, respectively, which were higher than those obtained from conventional extraction methods. The current work shows that bioactive polysaccharides and phenolics can be obtained together in high yield through a single aqueous-only green and efficient Alcalase-assisted extraction.