Extraction Technology Research Articles

A new eco-friendly approach for recovery of iron from copper smelting slag: Using CO2 and Cl2 recycling strategies

Copper smelting slag (CSS) is a by-product of modern copper production. In this study, iron resources were extracted from copper smelting slag using chlorine roasting and magnetic separation techniques for the first time. The results showed that hydrogen could reduce the ferrous chloride on the surface of the pellet to environmentally friendly iron, followed by the complete reduction of the ferrous chloride inside the pellet, thus increasing the metallic iron content in the roasted ore. Finally, the concentrate with a TFe (total iron) mass fraction of 73.41 wt% and iron recovery of 86.50 % was obtained, and XRF, XRD, and XPS analysis showed that iron is mainly enriched in the concentrate, and calcium, silicon, aluminum, and other elements are mainly enriched in the tailing. The innovative addition of recyclable additives in the roasting process not only reduces the production cost but also plays an important role in the current total environmental protection and environmentally sustainable development. Analytical methods such as thermodynamic evaluation, evolutionary trends of key elemental compounds, and molecular simulation were used to fully characterize the complex chemical processes of the chlorination roasting process. This study provides theoretical strategies for the cleaning of CSS and facilitates the industrial implementation of technologies for efficient and economical extraction of iron from CSS.

Recovery of high-purity hydromagnesite from seawater through carbonation using Ca(OH)2

The economic challenges arising from resource depletion and uneven distribution of Mg in land reserves have spurred interest in technologies for Mg extraction from seawater. Thus, this study introduces a novel method to recover high-purity magnesium carbonate, specifically hydromagnesite, from seawater through carbonation using Ca(OH)₂ as an alkali source. A significant achievement of this method is the production of high-purity hydromagnesite despite the presence of large amounts of Ca, realized only through carbonation without the need for expensive additives such as NaOH. Experimental results reveal that the Ca(OH)₂ content predominantly influences the Mg dissolution efficiency during carbonation and the overall Mg recovery rate. Maximizing the efficiency of this technology relies on using an appropriate amount of Ca(OH)₂. Notably, the appropriate amount of OH− supply enhances CO₂ dissolution, facilitating Mg dissolution. Conversely, an excess of Ca(OH)₂ impedes Mg dissolution. The overall Mg recovery rate reaches a peak of 67 %, enabling the recovery of 3.4 kg of hydromagnesite from one ton of seawater. The findings highlight the effectiveness of the proposed technology as a promising and cost-effective method for extracting high-purity Mg from seawater, utilizing Ca(OH)2, previously considered an impurity, as a cost-effective alkali source.

A preliminary study of the temperature-responsive selective extraction performance of hydrogel derived from sulfobetaine methacrylate

BackgroundThe limited extraction selectivity caused by the single extraction selection mechanism of solid phase extraction (SPE) technology is one of the bottlenecks restricting its development. The development of environmentally sensitive materials provides a new opportunity to solve this problem. Based on this, we developed the sulfobetaine methacrylate hydrogel with abundant pore structure, a large number of adsorption sites and especially temperature responsiveness, and used as adsorbent for the extraction of pesticide residues in lychees. ResultsThe new hydrogel adsorbent was prepared by free radical copolymerization with sulfobetaine methacrylate as monomer, and used for the extraction of benzoylurea insecticides from lychees. Interestingly, the hydrogel showed an almost opposite temperature-selective extraction trend for different benzoylurea insecticides with similar structure and polarity, and opposite hydrophilicity, which may be caused by the temperature-sensitive and the special action site of the hydrogel, and the change of the diffusion of aqueous solution. In addition, the analysis method of three hydrophilic benzoylurea insecticides by sulfobetaine methacrylate hydrogel-SPE-HPLC was established. Under optimal conditions, the low limits of detection (0.030 μg L−1) and quantification (0.10 μg L−1), and the wide linear ranges (0.10–50.0 μg L−1) were achieved. Its application in lychee samples were also tested, and the satisfactory results were obtained, with the spiked recoveries from 80.79 % to 108.31 %. SignificanceThis was a great breakthrough in the selective extraction of similar targets. These properties, combined with low-cost, biodegradable raw materials and convenient, green synthesis method make the sulfobetaine methacrylate hydrogel a very promising solid phase adsorbent. Temperature-responsive selective mode can greatly enrich the selective extraction mechanism and promote its development and application in complex actual samples.

Ultrasonic treatment assisted extraction of sunflower protein

Sunflower meal is a promising source of protein, which can be used as a food ingredient in the formulations of meat, flour and confectionery products. Alkaline extraction technology is traditionally used to obtain sunflower protein, but its efficiency can be increased using physical methods: ultrasound, microwave radiation, extraction at high pressure and others. Thу article deals with an application of the ultrasonic treatment for increase of the efficiency of protein extraction from defatted plant material: from the protein fraction of sunflower meal and from sunflower meal. The trial samples for protein extraction were prepared by the preliminary treatment of the samples in the ultrasonic bath for 15 minutes at a frequency of 40 hertz at temperature 24-28° C. The control sample was not subjected to such pretreatment. Then protein was isolated from the raw material by alkaline extraction followed by isoelectric precipitation. The possibility of the protein preparation isolation with a higher crude protein content (93,66% m.f.b) compared to the control sample has been shown. The mass yield of protein was 64% of its content in the raw material. The influence of ultrasonic treatment on the efficiency of protein extraction from raw material with different crude protein content is demonstrated. The results of the study show the feasibility of usage of ultrasound treatment in isolation of sunflower protein. In particular, the crude protein content in the trial protein sample after ultrasonic treatment was increased by 8,23% compared to the control sample. The obtained results demonstrated their consistency when compared to the results of other studies. However, there are only a limited number of studies on the use of ultrasound in the extraction of sunflower derived products.A comparison of the results obtained showed their consistency with the results of other studies. However, there are only a small number of studies on the use of ultrasound in the extraction of sunflower processing products.

Visual Analyses of Hot Spots and Frontiers in Zanthoxylum planispinum Research Based on CiteSpace

Zanthoxylum planispinum is a type of plant with homologous properties in medicine and food, making it well-loved in China. To explore the development of the Z. planispinum field over the past 20 years, its research hotspots and frontier trends were analyzed. This study conducted database-based visualization analyses and knowledge graph analyses using CiteSpace software with data concerning Z. planispinum published in the Chinese National Knowledge Infrastructure and Web of Science databases between 2003 and 2023. Over the last 20 years, the number of Chinese and English publications on Z. planispinum has shown increasing trends. The foci of this research were mainly germplasm resources, cultivation management, seed oil extraction technology, flavonoid extraction technology, and correlation analyses of antioxidant activities. The main research frontiers included the unified standard naming and adaptation mechanisms of Z. germplasm resources, orientation cultivation, functional component extraction, processing technology research and development, and industrial chain construction. The results provide a scientific reference for the high-quality development of the prickly ash industry.

Procedures to evaluate potential of plants as natural food preservatives: Phytochemical characterization, novel extraction technology, and safety evaluation—A comprehensive review

Procedures to evaluate potential of plants as natural food preservatives: Phytochemical characterization, novel extraction technology, and safety evaluation—A comprehensive review

Numerical Simulation of Rock Vibration Response under Ultrasonic High-Frequency Vibration with High Confining Pressure

As deep oil and gas resources and Carbon Capture and Storage (CCS) are developed, enhancing drilling efficiency in hard rock formations has emerged as a critical technology in oil and gas extraction. The advancement of ultrasonic, high-frequency vibration rock-breaking technology significantly facilitates efficient rock crushing. When subjected to ultrasonic high-frequency vibrations, the rock’s response is a crucial issue in implementing ultrasonic vibration rock crushing technology. This study employed numerical simulation and theoretical deduction methods, utilizing a multi-physics approach that couples solid mechanics with pressure acoustics. It integrated information on common influencing parameters of ultrasonic generators and reservoir rock properties to establish model parameters, analyze simulation results, and perform theoretical deductions. The research investigated the response patterns of different-sized rock samples under high-frequency ultrasound vibration excitation across various frequencies, amplitudes, and confining pressure conditions. Through the development of a three-dimensional model and the application of principles from solid mechanics and elastoplasticity, the study derived equations that describe the resonance frequencies of rock blocks under confining pressure as functions of relevant rock parameters. The findings indicate that ultrasonic vibrations can effectively induce rock displacement. Under excitation frequency sources, the rock exhibits a natural frequency correlated with the rock sample size. When the excitation frequency approximates the natural frequency, the rock resonates. At this point, the rock’s surface displacement is maximal. The rock undergoes tensile stress, leading to stress concentration that facilitates rock damage and fragmentation. Increasing the excitation amplitude enhances rock crushing, as it amplifies the maximum surface displacement under the same frequency excitation. Confining pressure exerts an inhibitory effect on the rock’s vibration response, but it does not alter the resonance frequency of the rock sample, a fact verified by both numerical simulation and theoretical results. Based on the research findings in this paper, it can help to optimize the parameters of ultrasonic vibration rock breaking in field application to achieve the best rock-breaking effect.

USAGE OF TECHNICAL MEANS FOR ANNULAR GAS EXTRACTION TO INCREASE OIL WELL PRODUCTION

In recent years, the technology of annular gas extraction from wells has become increasingly widespread in the fields in order to improve the working conditions of the submersible pump due to increasing its filling and supply coefficients, as well as increasing depression on the formation. Some types of compressor designs have been developed and put into production, allowing the annular gas extraction from wells and forced injection into the pressure line of the well. One of the most well-known types of compressors is a piston pair driven by a piston from a rocking machine balancer. They were used at oil production facilities in the Orenburg, Ulyanovsk Regions, the Republics of Tatarstan and Bashkortostan, Udmurtia and other regions of the Russian Federation.In the fields of Sheshmaoil LLC, a complex for pumping gas from the annulus of a well and pumping it into the COGS product collection system has found mass usage, allowing gas to be taken from a group of wells and reducing pressure in the annulus to values close to 0.1 MPa. Hydraulic piston compressors, in which gas compression occurs using a high-pressure pump that drives the piston group of the compressor, have been tested.One of the main disadvantages of the developed types of compressors is the insufficient volume and pressure of the compressed gas. The article provides an analysis of the technological parameters of the compressors. As a result of research possible solutions to the problem are worked out.To achieve the largest pumping volumes of separated annular gas, the maximum permissible diameter of the compressor cylinder should not exceed 0.07 m in order to prevent significant resistance exerted by the piston rod on the balancer of the pumping machine.The most suitable region for the effective use of suspended compressors is the Ural-Volga Region at fairly depleted oil fields with at least 60–65 % water cut, oil well flow rate of no more than 10–15 tons/day and a gas factor of no more than 15–20 m3/t . At the fields of Western Siberia, suspended compressors cannot be used due to high flow rates and gas factors. Exceptions may be wells with a water cut of at least 80 % and flow rates of no more than 20–25 tons/day.The KOGS compressor unit, developed and widely implemented at Sheshmaoil Management Company LLC, showed positive results, consisting of an increase in flow rate and additional oil production. For further use of the unit in fields, especially for high-viscosity oil production, as well as operation in winter conditions, it is necessary to increase the maximum gas injection pressure.

Symphytum genus—from traditional medicine to modern uses: an update on phytochemistry, pharmacological activity, and safety

AbstractWith around 34 recognized species, Symphytum genus (comfrey) has a noteworthy position within the Boraginaceae family. Comfrey species have been empirically used since ancient times as wound-healing and skin-regenerating agents in ulcers, wounds, bone fractures, and rheumatic complaints. This review aims to provide a thorough examination of recent scientific advances and challenges within the Symphytum genus, covering data published between 2013 and 2023. It delivers an updated overview of the taxonomy, ethnopharmacological uses, chemical composition, and pharmacological activities of the genus. Special emphasis is put on molecular identification methods for species taxonomy, emerging extraction technologies for comfrey phytochemicals, metabolomics techniques for mapping chemical complexity, modern bioassay platforms revealing its poly-pharmacology, formulation strategies, and remediation approaches for removal of toxic pyrrolizidine alkaloids (PAs). For instance, recent metabolomic studies employing advanced spectro-chromatographic techniques have revealed a diverse chemical composition of comfrey plants, including polysaccharides, allantoin, benzoic and cinnamic acid derivatives, flavonoids, fatty acids, and unsaturated necine-structure-based PAs. The mechanisms underlying their anti-inflammatory, analgesic, wound-healing, anti-irritant, and osteo-regenerative properties were targeted in modern pharmacological setups. Thus, key compounds like allantoin, rosmarinic acid, globoidnans A and B, rabdosiin, and comfreyn A, have been identified as significant contributors to the anti-inflammatory and wound-healing effects of Symphytum-derived preparations. Despite their well-established clinical use, concerns about PAs-induced toxicity have prompted the development of novel PA remediation strategies, enabling the production of comfrey extracts with enhanced safety profiles that can meet the regulatory standards imposed by authorities.

Extraction of healthy oils from fish viscera by conventional and advanced technologies

Fish viscera is a by-product of fish processing that has limited use as added-value products. The current issue of circular economy to produce recycled and zero waste products, therefore, the utilization of fish viscera for valuable products is important to explore. One of the valuable components of fish viscera is fish oil, which is characterized by being high in polyunsaturated fatty acids (PUFA). The limited exploration of fish viscera for potential utilization requires a comprehensive review of the visceral characteristics of various fish species. This article reviews the nutritional characteristics of various fish viscera, lipid class composition, fish viscera oil characteristics, and various methods of fish viscera oil extraction, both by conventional and advanced technologies. The main contribution of this review is to provide information about fish viscera, their potential as a source of fish oil, and extraction methods which are suitable for various industrial applications and purposes, including health applications for ω-3 fatty acids.

Optimization of Enzymatic Assisted Extraction of Bioactive Compounds from Olea europaea Leaves

Nowadays, the circular economy trend drives researchers in the recovery of various bioactive compounds from agri-food by-products. Enzyme-assisted extraction (EAE) has been shown to be an innovative green technology for the effective extraction of various phytochemicals from agri-food section by-products; therefore, this study aimed to evaluate the application of EAE as green technology to obtain extracts from olive leaves (Olea europaea) for potential industrial production. The used enzymes were Celluclast, Pectinex XXL and Viscozyme L. EAE was conducted under various enzyme dose combinations and an incubation time of 120 min. Obtained extracts were characterized in terms of total polyphenols (TP) and total antioxidant activity (AA). Firstly, the enzyme synergistic effect in the enzymatic extraction of polyphenols was evaluated. TP optimal extraction conditions (468.19 mg GAE (gallic acid equivalent)/L of extract) were achieved after EAE using Pectinex and Viscozyme enzymes (50–50 v/v) and for AA (69.85 AA%). According to the above results, a second experiment investigated the effect of incubation time (min.) and enzyme dose (mL) on the optimal extraction conditions of olive leaves. The final results after optimization were 75% higher than the control sample for the TP content (605.55 mg GAE/L) and 8% higher for the AA (70.14 AA%). These results indicated that EAE is an excellent choice for the green extraction of polyphenols from the olive leaves.

Effects of Green Extraction Methods on Antioxidant and Antimicrobial Properties of Artichoke (Cynara scolymus L.) Leaves

Research background. Artichoke leaves, an important waste product of the food industry, have an important antioxidant and antimicrobial capacity. Although there are several studies in the literature to determine their antioxidant and antimicrobial activity, a comparison of green extraction technologies including microwave, ultrasound probe and ultrasound bath methods in relation to the maceration technique has not been performed. Also, several parameters such as the extraction temperature, power, extraction mode and extraction time are important parameters for obtaining targeted compounds in the highest amount. For this reason, we aimed to compare various extraction methods including microwave-assisted extraction, ultrasound-assisted extraction with probe, ultrasound-assisted extraction in a water bath and maceration in terms of extraction parameters for obtaining bioactive compounds from artichoke leaves. Experimental approach. Microwave-assisted extraction at two different power values, ultrasound-assisted extraction with probe in continuous or pulsed mode with two different extraction times each, ultrasound-assisted extraction in a water bath at two different power values with two different extraction times each and maceration with two different times were used for the extraction. The extraction temperature is an important parameter affecting the thermal degradation of bioactive compounds. We used a constant extraction temperature of 50 °C. Total phenolic and total flavonoid content, antioxidant capacity, phenolic compound profile analysis by LC-QTOF-MS and antimicrobial activity by agar diffusion and broth microdilution methods were determined. Results and conclusions. The bioactive compounds were found to be significantly affected by the parameters used in each extraction method. The microwave-assisted extraction method was more efficient than the other extraction methods at both power values. This method also required the shortest extraction time. The ultrasound-assisted probe extraction method was the second most efficient method. The type of process, continuous or pulsed, did not affect the results, but shortening the extraction time led to lower results. A longer extraction time of the ultrasound-assisted extraction in a water bath method led to better results, similar to the ultrasound-assisted probe extraction, regardless of the used power. The extracts were highly effective against many opportunistic and pathogenic microorganisms. Novelty and scientific contribution. This study provides valuable insights into the extraction parameters of different extraction methods to obtain bioactive compounds from artichoke leaves, which could have potential applications in the food and pharmaceutical industries.

Biopolymeric surface modified 96-well plates for equipment-free high-throughput DNA extraction and direct ACK-LAMP colorimetric detection of foodborne pathogen

Ensuring the safety and high quality of food relies on promptly and clearly identifying foodborne diseases, including Salmonella. Nucleic acid testing plays an important role in ensuring food safety. Commercially available high-throughput molecular extraction technologies in-field application is limited as they are reliant on specialized and expensive equipment. The 96-well microplate recycling through biopolymer inner surface coating, was confirmed with FTIR, XRD, and XPS. Once optimized the DNA extraction protocol was equipment-free, user and eco-friendly while reducing sample contamination. Using the biopolymer microplate, the extraction and direct LAMP amplification of Salmonella spp. from milk samples were assessed. The gDNA had an average 260/280 ratio of 1.97, with a DNA yield of 16.88 ± 5.40 μg mL−1 from 9 × 1010 CFU mL−1Salmonella. Subsequently, using acid chrome K we visually detected the presence of Salmonella. The quantity of bacteria was correlated to the increase in the blue intensity of the color indicator. A detection limit of 1.54 CFU mL−1 was achieved with good specificity and sensitivity in an equipment free setting. This study successfully established a 96-well plate-based high-throughput equipment free DNA extraction method. The methods enable the high-throughput extraction and amplification of 96 samples concomitantly within 1hr 30 min corresponding respectively to a total of 1536 and 768 samples within a working day treated by a researcher without the use of specialized and expensive equipment. The polymeric modified microplate was used for high-throughput DNA extraction and direct molecular amplification for pathogen detection. High-throughput DNA extraction no longer requires cumbersome equipment.

Green extraction of agar from Hypnea pannosa seaweed: A comparative study of different techniques and optimization using response surface methodology

This study aimed to evaluate the optimal method for extracting agar from Hypnea pannosa seaweed and assess its purity and yield. Agar is a hydrocolloid found in red seaweeds and used in various industries such as food, cosmetics, and medicine. Three different extraction methods were employed for this study, namely ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE), and ultrasound microwave-assisted extraction (UMAE), each using varying power levels and extraction times. A central composite Response surface methodology (RSM) design was used to compare these methods. Results showed that UAE had the highest extraction yield at 32.99 %, followed by MAE, UMAE, and conventional methods at 27.04 %, 26.19 %, and 12 %, respectively. Various techniques were used to evaluate agar quality, including spectral analysis (FT-IR), gel strength, viscosity, 3,6 anhydrous L galactose (AG), and sulfate content. Samples treated with ultrasound had higher-quality agar than those treated with other methods, with significantly better gel strength, 3,6 AG content, viscosity, and lower sulfate content. Gel strength was 485.50 ± 4.27 g cm−2, 3,6 AG content was 62.89 ± 2.89 %, viscosity was 48.32 ± 0.03 centipoises and sulfate content was 1.32 ± 0.02 % in UAE. FT-IR analysis confirmed the presence of functional groups in the fingerprint region of identification for polysaccharides in UAE agar. UAE (30 min, 60 % amplitude) was identified as the most viable green extraction technology, offering superior extraction yield and agar quality compared to the other treatments. Using green extraction techniques in obtaining agar has significant implications for the sustainable production of natural products. This research also highlights the potential application of agar in the skincare or pharmaceutical industry, paving the way for developing eco-friendly products. Overall, this study suggests that UAE is an efficient method for extracting agar from H. pannosa and has novel applications in nutraceuticals and cosmeceuticals. Novelty impact statementThe current study presents a comprehensive investigation of the green extraction of agar from Hypnea pannosa seaweed using different techniques, along with optimization through response surface methodology. The novelty of this research lies in its focus on sustainable and eco-friendly extraction methods, which are increasingly gaining importance in the current global scenario. The comparative study on the different techniques used for the extraction of agar provides a critical evaluation of the advantages and limitations of each method. The use of response surface methodology in the optimization process is a noteworthy feature, as it allows for the identification of optimal extraction conditions with greater accuracy and reliability. The findings of this study significantly contribute to the development of sustainable practices in the seaweed industry, and its academic value is undeniable.

Crude Oil Extraction Technology from Organic Waste Resources: A Review

Crude Oil Extraction Technology from Organic Waste Resources: A Review

A Review of Stability of Dam Structures in Coal Mine Underground Reservoirs

Coal has remained the primary component of China’s energy structure, and high-intensity extraction has continued in the central and western coal-producing regions of China. In contrast to the abundant coal resources, water resources have become extremely scarce in these regions, creating a conflict between coal resource extraction and water resource conservation. The coal mine underground reservoir (CMUR), as a typical technology for combined coal and water extraction and water-preserving coal mining, has been applied in numerous mines in central and western China. This effectively alleviates water resource shortages and achieves the goal of water resource conservation. The CMURs utilizes the goaf created by longwall mining as the water storage space. The reservoir dam structure comprises coal pillars, which serve as protective coal pillars in the mining area, and artificial dam structures that filled the gaps between these coal pillars. The stability of the dam structure under the complex stress effects of hydraulic coupling has been identified as the key to maintaining the safe operation of the CMUR. The mechanical properties, stress field, fracture field, and seepage field (“three fields”) change mechanisms, as well as the research results on size optimization of coal pillar dams and artificial dams in CMURs, were systematically reviewed. The core content included the instability and failure mechanisms of dam structures under the comprehensive coupling effects of factors such as dry–wet cycles of mine water, long-term immersion, chemical effects of high-salinity water, dynamic and static loads, and cyclic loads. This paper is considered to have certain reference value for the study of the stability of dam structures in CMURs and to provide some guidance for the safe operation of CMURs.

Increasing the efficiency of stimulation of compacted carbonate reservoirs with acid solutions based on methyl acetate

The development of oil and gas deposits in compacted rocks is a promising area of development in the oil and gas industry. The object of research in this paper is the filtration properties of compacted rocks. To develop such deposits, special extraction technologies are required. Compacted carbonate rocks are easily dissolved by most acids, but for effective use, it is necessary that working solutions have very low viscosity and surface tension coefficient. Special filtration equipment has been developed for the research, which allows pumping various liquids and gases through rock samples and measuring permeability at pressures up to 1,000 bar. To determine the effectiveness of the acid solution, three groups of samples were studied: silty sandstone with clay-carbonate cement with a permeability of 0.2–0.95 mD, compacted organogenic-detrital light gray limestone with a permeability of 0.001–0.004 mD, and organogenic-detrital gray limestone with a permeability of 0.04–0.06 mD. In the course of the study, the stimulation fluid was pumped through the samples at a pressure of 200–300 bar and a temperature of 120 °C. The efficiency was determined by the change in nitrogen permeability of the samples before and after the experiments. In general, the studied stimulation fluid allowed increasing the permeability of rocks up to 3–7 times, depending on the rock and research conditions. The solution retains its reactivity for a long time and, due to its low viscosity and surface tension, penetrates deeply into the rock and significantly increases the well treatment radius compared to conventional acid treatments. The use of the developed acid solution for well stimulation will increase the efficiency of hydrocarbon production from compacted reservoirs without the use of hydraulic fracturing

Extraction of Bioactive Compounds from Wine Lees: A Systematic and Bibliometric Review.

The extraction of bioactive compounds from wine lees involves a variety of methods, the selection of which is crucial to ensure optimal yields. This systematic review, following PRISMA guidelines and utilizing the Web of Science database, aimed to examine the current state of this field, providing insights for future investigations. The search employed strategies with truncation techniques and Boolean operators, followed by a three-step screening using well-defined eligibility criteria. A bibliometric analysis was conducted to identify authors, affiliations, countries/regions, and research trends. Thirty references were selected for analysis, with Spain standing out as the main source of research on the topic. The majority of studies (66%) focused on the extraction of bioactive compounds from alcoholic fermentation lees, while 33% were directed towards malolactic fermentation lees. Binary mixtures (ethanol-water) were the predominant solvents, with ultrasound being the most used extraction method (31.3%), providing the highest average yields (288.6%) for the various evaluated compounds, especially flavonoids. The potential of wine lees as a source of bioactive compounds is highlighted, along with the need for further research exploring alternative extraction technologies and the combination of methods. Additionally, the importance of "in vitro" and "in vivo" tests to assess the bioactive potential of lees, as well as the use of computational tools to optimize extraction and identify the molecules responsible for bioactive activity, is emphasized.

Effects of ultrasonic-assisted natural deep eutectic solvent on the extraction rate, stability and antifungal ability of polyphenols from Cabernet Sauvignon seeds

Ultrasonic-assisted extraction using a natural deep eutectic solvent (UAE-NADES) is an efficient method for extracting grape seed polyphenols (GSPs). In this study, response surface methodology was used to optimize the extraction of GSPs with UAE-NADES, and the theoretical extraction rate of GSPs was 139.014 mg GAE/g, the actual extraction rate was 135.78 ± 1.3 mg GAE/g. A pseudo-second-order kinetic extraction fitting was established to simulate the extraction process and mechanism (R2 > 0.99). Analysis of antioxidant capacity, Fourier-infrared spectroscopy and scanning electron microscopy revealed that UAE-NADES works synergetically to maintain the stability of extracted GSPs. The results of high-performance liquid chromatography showed that catechin (41.14 mg/g) is the main component of GSPs in the extract. The UAE-NADES extraction of GSPs can inhibit the growth of Alternaria alternata at 0.25 mg GAE/g, while the GSPs extracted by other methods can effectively inhibit the growth of Alternaria alternata at 0.35 mg GAE/g. Thus, this study demonstrates that UAE-NADES is a high-efficiency means of extracting GSPs and, in a wider sense, is a promising extraction technology for the green utilization of waste resources.

Delithiation and lithiation of LiFePO4: Implications for direct Li extraction from synthetic solutions and geothermal brines

The demand for Li is and will be increasing in the future, and the development of a direct Li extraction (DLE) technology from unconventional resources, like geothermal brines, may contribute to a resilient supply in the future. This study investigates the deintercalation from and intercalation of Li in LiFePO4 (LFP) at 25–80 °C, near neutral to acidic pH and the effect of high salinity on the Li extraction performance. The (de-)lithiation is a fully reversible redox process between triphylite and heterosite. Lithium is delithiated from LFP using 0.1 M Na2S2O8 at 42–43 mg/g. The lithiation kinetics increase with temperature, but show a complex relationship to reducing agent (Na2S2O3) concentration. The maximum re-intercalation is achieved in synthetic LiCl + 0.5 M Na2S2O3 solution at 39 mg/g, 25 °C and 7 days, whereas 27 mg/g and 1.3 mg/g Li are intercalated to LFP within 3–4 h in experiments with Bruchsal and synthetic Neustadt-Glewe geothermal brines at 60 °C, respectively. At optimal parameters, >99 % Li are recovered from both geothermal brines in laboratory experiments. This shows that LFP can be used for DLE from geothermal brines under specific conditions in a purely chemical process.