Solid-liquid Extraction Process Research Articles

Recovery of Strategic Metals from Waste Printed Circuit Boards with Deep Eutectic Solvents and Ionic Liquids

The recycling of metals from waste printed circuit boards (WPCBs) has been presented as a solid–liquid extraction process using two deep eutectic solvents (DESs) and four ionic liquids (ILs). The extraction and separation of Cu(II), Ag(I), and other metals, such as Al(III), Fe(II), and Zn(II), from the solid WPCBs (after the physical, mechanical, and thermal pre-treatments) with different solvents are demonstrated. Two popular DESs were used to recover valuable metal ions: (1) choline chloride + malonic acid, 1:1, and (2) choline chloride + ethylene glycol, 1:2. The extraction efficiencies of DES 1 after two extraction and two stripping stages were only 15.7 wt% for Cu(II) and 17.6 wt% for Ag(I). The obtained results were compared with those obtained with four newly synthetized ILs as follows: didecyldimethylammonium propionate ([N10,10,1,1][C2H5COO]), didecylmethylammonium hydrogen sulphate ([N10,10,1,H][HSO4]), didecyldimethylammonium dihydrogen phosphate ([N10,10,1,1][H2PO4]), and tetrabutylphosphonium dihydrogen phosphate ([P4,4,4,4][H2PO4]). Various additives, such as didecyldimethyl ammonium chloride surfactant, DDACl; hydrogen peroxide, H2O2; trichloroisocyanuric acid, TCCA; and glycine or pentapotassium bis(peroxymonosulphate) bis(sulphate), PHM, were used with ILs during the extraction process. The solvent concentration, quantity of additivities, extraction temperature, pH, and solid/liquid, as well as organic/water ratios, and the selectivity and distribution ratios were described for all of the systems. The utilization of DESs and the new ILs with different additives presented in this work can serve as potential alternative extractants. This will help to compare these extractants, additives, extraction efficiency, temperature, and time of extraction with those of others with different formulas and procedures. The metal ion content in aqueous and stripped organic solutions was determined by the ICP-MS or ICP-OES methods. The obtained results all show that solvent extraction can successfully replace traditional hydrometallurgical and pyrometallurgical methods in new technologies for the extraction of metal ions from a secondary electronic waste, WPCBs.

Strengthening the Attainment of Major Competencies of Program Outcomes through Open-ended Experiment using Statistical Designs

Abstract—Unit operations are very essential part of the chemical engineering and allied disciplines; and hence, basic knowledge about the principles and equipment used for various unit operations is mandatory for process engineer. Unit operations course introduces the foundation of process engineering concepts at the second year of undergraduate program of Bachelor of Engineering in Biotechnology. This course mainly focuses on the most essential unit operations utilized in Chemical and allied process industries such as mass transfer, heat transfer, momentum transfer and mechanical operations. The conventional teaching approach practiced so far in Unit Operations Laboratory course was not so effective in the attainment of certain specific core competencies of Program Outcomes (POs). To tackle this challenge, we introduced a system of classifying laboratory experiments into four distinct categories: Demonstration, Exercise, Structural Inquiry, and Open-ended experiments. These categorized experiments were thoughtfully crafted to target various significant technical and professional outcomes such as Investigations of Complex Engineering Problems, Communication, Life-long learning, Follow of Standard Operating Procedure (SOP) and Good Laboratory Practices (GLP). The evaluation criteria for each type of experiment were aligned with program outcomes, competencies, and performance indicators. This alignment proved highly beneficial in achieving a more precise assessment of program outcomes. This study focuses on implementing an interactive and collaborative learning approach in the Unit Operations laboratory course. of Experiments. More precisely, the study employs Central Composite Design (CCD) and Response Surface Methodology (RSM) concepts to examine how various factors influence the Leaching (Solid-Liquid Extraction) process. The leaching process is most important unit operations used in the extraction of substances from solids. The study helped in addressing several important competencies pertaining to the Program Outcomes- PO-4: Demonstrating the capacity to design, execute experiments, and analyze data; PO-10: Exhibiting effective communication skills; PO-12: Embracing lifelong learning; PSO-13: Adhering to Standard Operating Procedures (SOP) and Good Laboratory Practices (GLP). The assessment of student performance employed a rubric-based approach, and the attainment of program outcomes was documented. It was observed that, open-ended experimental approach, led to the improvements in the attainment of PO’s in terms of competencies and performance indicators. To enhance the teaching-learning process, formal and anonymous feedback was gathered from students to identify areas of improvement and deficiencies. Keywords—Central Composite Design; Collaborative learning; Design of experiments; Open-ended experiment; Program outcome; Response Surface Methodology;

Green extraction of natural antioxidants from white grape waste using bio-renewable solvents and ultrasonic process intensification

Winemaking industry generates significant waste rich in bioactive compounds, particularly phenolic compounds with strong antioxidant properties. Bio-renewable green solvents are promising candidates for the sustainable recovery of such antioxidants. For these reasons, the aim of this study was to evaluate green solvents (alcohols, ethers, esters, and terpenes) for extracting phenolic compounds from white grape waste (WGW). The solid-liquid extraction process was optimized by adjusting parameters like extraction time, temperature, and solid:liquid ratio. Under most favourable conditions, ethanol yielded the highest total phenolic content at 9.43 ± 0.16 mg GAE/g WGW, followed by 2-methyltetrahydrofuran at 7.23 ± 0.08 mg. The total phenolic content of the different WGW fractions (skin and seeds) was also evaluated. The solvent extracts were analyzed by UV–Visible spectrophotometry and chromatographic (HPLC-DAD) methods to characterize the phenolic profile, and the antioxidant capacity was also measured. Alcohols and ethers emerged as the most selective solvents, particularly for catechin and gallic acid. Additionally, successful solvent recycling and antioxidant recovery as a solid fraction were accomplished. Lastly, ultrasound-assisted extraction intensified the process, reducing time and energy consumption. Overall, this work exemplifies the "Circular Bioeconomy" concept, promoting sustainable waste biomass valorization to produce high-value bioproducts in demand by industry and society.

Simulation and Experimental Study of Solid-Liquid Extraction of Coal Tar Residue Based on Different Extractants.

Coal tar residue (CTR) is recognized as a hazardous industrial waste with a high carbon content and coal tar consisting mainly of toxic polycyclic aromatic hydrocarbons (PAHs). The coal tar in CTR can be deeply processed into high-value-added fuels and chemicals. Effective separation of coal tar and residue in CTR is a high-value-added utilization method for it. In this paper, ethyl acetate, ethanol, and n-hexane were chosen as extractants to study the extraction process of coal tar from CTR, considering the mass transfer in the liquid phase outside the CTR particles and the diffusion inside the CTR particles, and a mathematical model of the solid-liquid extraction process of CTR was established based on Fick's second law. First, the mass-transfer coefficients (kf) and effective diffusion coefficients (De) of ethyl acetate, ethanol, and n-hexane in solid-liquid extraction at 35 °C were determined to be 1.54 × 10-5 and 4.99 × 10-10 m2·s-1, 1.14 × 10-5 and 3.57 × 10-10 m2·s-1, and 1.01 × 10-5 and 3.48 × 10-10 m2·s-1, respectively. Furthermore, the simulated values obtained by the model also maintained a high degree of agreement with the experimental results, which indicates the high accuracy prediction of the model. Finally, the model was used to investigate the effects of the solvent-solid ratio, temperature, and stirring speed on the extraction rates with the three extractants. According to the analysis with gas chromatography-mass spectrometry (GC-MS), among the three solvents, n-hexane extracted the highest content of aliphatic hydrocarbons (ALHs), ethyl acetate extracted the highest content of oxygenated compounds (OCs), and ethanol extracted the highest content of aromatic hydrocarbons (ARHs). The model and experimental data can be used to provide accurate predictions for industrial utilization of CTR.

Technical-economic evaluation of lipo- and water-soluble fractions from annatto seeds by green technology

PurposeThe objective of this study was to evaluate the technical-economic process efficiency of obtaining simultaneous lipo-soluble (LSF) and water-soluble (WSF) fractions from annatto seeds.Design/methodology/approachThe batches of annatto seeds were submitted to the refrigerated solid-liquid extraction process in four stages: pre-extraction, aqueous extraction, separation by decantation and filtration. After that, LSF and WSF from annatto seeds were obtained. The process efficiency and the quality of LSF and WSF were analyzed in terms of average yield and bioactive compounds (bixin, norbixin, phenolics and flavonoids) and their antioxidant and antimicrobial activities. Furthermore, they were economically evaluated in terms of costs of manufacturing and profitability parameters.FindingsThe process was efficient in terms of overall average yield (LSF = 8.68% and WSF = 2.76%) (w/w) and in terms of quality, mainly with higher average yields of bixin (82.34% in LSF) and norbixin (29.59% in WSF) (w/w). The concentration of bioactive compounds in the fractions promoted an increase in inhibiting free radicals (DPPH* and ABTS*+) and in the ferric-reducing power (FRAP). LSF showed a minimum inhibitory concentration of 0.06 mg mL-1 for S. aureus and 0.13 mg mL-1 for S. Typhimurium and S. Enteritidis. The lowest manufacturing costs were obtained for the LSF due to its higher extraction yield compared to the WSF. Plants on an industrial scale of 100 and 1000 L were considered economically viable, with a return on investment of 5 and 2 years.Originality/valueThus, fractions (WSF and LSF) can be applied as natural additives, as sources of bioactive compounds for nutraceutical and/or pharmaceutical, and in the development of other innovative processes. These results have practical applicability for pharmaceutical and food industry.Highlights Green processing of annatto seeds obtains fractions rich in antioxidant compounds.Efficiently presents a high yield of bixin and other bioactive compounds.Effective in concentrating compounds that inhibit microbial growth.Fractions are more accessible sources of bioactive compounds for isolation.Cost of manufacturing (COM) and profitability are studied.

Kinetic Modelling the Solid–Liquid Extraction Process of Scandium from Red Mud: Influence of Acid Composition, Contact Time and Temperature

Industry represents a fundamental component of modern society, with the generation of massive amounts of industrial waste being the inevitable result of development activities in recent years. Red mud is an industrial waste generated during alumina production using the Bayer process of refining bauxite ore. It is a highly alkaline waste due to the incomplete removal of NaOH. There are several opinions in both the literature and legislation on the hazards of red mud. According to European and national legislation, this mud is not on the list of hazardous wastes; however, if the list of criteria are taken into account, it can be considered as hazardous. The complex processing of red mud is cost-effective because it contains elements such as iron, manganese, sodium, calcium, magnesium, zinc, strontium, lead, copper, cadmium, bismuth, barium and rare earths, especially scandium. Therefore, the selection of an extraction method depends on the form in which the element is present in solution. Extraction is one of the prospective separation and concentration methods. In this study, we evaluated the kinetic modelling of the solid–liquid acid extraction process of predominantly scandium as well as other elements present in red mud. Therefore, three acids (HCl, HNO3 and H2SO4) at different concentrations (10, 20 and 30%) were targeted for the extraction of Sc(III) from solid red mud. Specific parameters of the kinetics of the extraction process were studied, namely the solid:liquid ratio, initial acid concentration, contact time and temperature. The extraction kinetics of Sc(III) with acids was evaluated using first- and second-order kinetic models, involving kinetic parameters, rate constants, saturation concentration and activation energy. The second-order kinetic model was able to describe the mechanism of Sc(III) extraction from red mud. In addition, this study provides an overview on the mechanism of mass transfer involved in the acid extraction process of Sc(III), thereby enabling the design, optimization and control of large-scale processes for red mud recovery.

Solid-liquid extraction for yttrium recovery using porous polymeric resin (XAD-7) functionalized with D2EHPA

The recovery of yttrium is proposed by applying a solid–liquid extraction process using di-2-ethyl hexylphosphoric acid (D2EHPA) as extracting agent. The extracting agents were supported on a macro porous polymeric resin XAD-7 (solid phase). Yttrium ions extraction and discharge tests were performed, firstly from a synthetic aqueous solution of 100 mg/L Y (liquid phase) at 25 °C with stirring. The effects of pH of aqueous solutions bearing yttrium, volume fraction of extracting agents and the solid/liquid (S/L) ratio on the yttrium recovery were studied. The most favorable conditions for yttrium ions extraction are: 20 vol% D2EHPA functionalized resin, pH = 1.5 and an S/L ratio of 10 mg/mL. The discharge of yttrium ions was done under the same conditions of extraction stage, using a 2 mol/L [H2SO4] as stripping solution. Up to 80 % yttrium is extracted, while 75 % yttrium is recovered in the striping solution. In all experiments, the reaction equilibrium is reached after 20 min, and the kinetics for the extraction stage was determined as a second-order model. Also, experiments were carried out to discharge the yttrium-loaded resins, and it has been determined that the best pH value to strip the Y ions is 1.5. Cyclic tests of extraction and discharge for yttrium ions show that the functionalized resin can work at least five cycles without decreasing its efficiency. Finally, the proposed process was tested in a real solution with Y ions from a waste fluorescent lamp powder leached in H2SO4, demonstrating the ability to effectively recover yttrium, separating it from various metals from the studied residue.

Solid-liquid extraction of chlorogenic acid from Eucommia ulmoides Oliver leaves: Kinetic and mass transfer studies

Chlorogenic acid is an important natural active compound in Eucommia ulmoides Oliver leaves. A second-order kinetic model was considered applicable for the solid-liquid extraction process and revealed the positive effects of reducing the particle size, increasing the liquid-solid ratio and temperature on accelerating the extraction rate and increasing the equilibrium yield. An empirical model on the studied variables was developed to predict the extraction process and its feasibility was verified. The activation energy was 19.67 kJ mol−1. The mass transfer process was investigated based on Fick’s second law, where the extraction rate depends on the internal diffusion of the compound and the internal resistance was the main factor affecting the extraction process. Temperature and liquid-solid ratio significantly changed the effective diffusion coefficient and mass transfer coefficient in different ways, and the Biot number was related to the liquid-solid ratio. Overall, these findings provided fundamental datas and theoretical guidances for the extraction of chlorogenic acid.

Enhanced extraction of brominated flame retardants from e-waste plastics

Acrylonitrile butadiene styrene (ABS) is a high utility engineering thermoplastic, abundantly present in waste electronic and electrical goods. The demand for this plastic resin increases continuously with rapid industrial growth across the world. During the recycling of e-waste plastics, it is a common occurrence to find brominated flame retardants, such as Tetrabromobisphenol A (TBBPA) in the plastic. These flame retardants are intentionally added to the plastics as additives. Three processes were investigated to find the optimum solvent/antisolvent combinations, process parameters for the efficient recovery of TBBPA free plastics: microwave assisted extraction (MAE), ultrasound assisted extraction (UAE), and dissolution reprecipitation (DR). Rigorous solvent screening was carried out for both TBBPA and ABS using Hansen Solubility Parameters (HSP), and their interactions with the solvents were investigated with a molecular based Conductor like Screening Model for Realistic Solvents (COSMO-RS) software platform. A 4:1 (v/v) solvent mixture of 1-propanol and heptane was found to be ideal for the solid–liquid extraction process. The optimal extraction conditions (Temperature = 110 – 130 °C, time = 60 to 70 min solid/liquid ratio of 0.025) in MAE were predicted using machine learning based Support Vector Regression (SVR) technique. MAE was found to be superior to UAE and DR processes in terms of quantity and quality of recovered plastics. The maximum extraction efficiencies for TBBPA removal were achieved with MAE, UAE, and DR processes at 95.81%, 93.92%, and 98.15%, respectively. However, the DR process had a relatively lower plastic recovery.

Pulsed electric fields-assisted extraction of valuable compounds from red grape pomace: Process optimization using response surface methodology.

The application of Pulsed electric fields as a mild and easily scalable electrotechnology represents an effective approach to selectively intensify the extractability of bioactive compounds from grape pomace, one of the most abundant residues generated during the winemaking process. This study addressed the optimization of the pulsed electric fields (PEF)-assisted extraction to enhance the extraction yields of bioactive compounds from red grape pomace using response surface methodology (RSM). The cell disintegration index (Z p ) was identified as response variable to determine the optimal PEF processing conditions in terms of field strength (E = 0.5-5 kV/cm) and energy input (WT = 1-20 kJ/kg). For the solid-liquid extraction (SLE) process the effects of temperature (20-50°C), time (30-300min), and solvent concentration (0-50% ethanol in water) on total phenolic content (TPC), flavonoid content (FC), total anthocyanin content (TAC), tannin content (TC), and antioxidant activity (FRAP) of the extracts from untreated and PEF-treated plant tissues were assessed. The phenolic composition of the obtained extracts was determined via HPLC-PDA. Results demonstrated that the application of PEF at the optimal processing conditions (E = 4.6 kV/cm, WT = 20 kJ/kg) significantly enhanced the permeabilization degree of cell membrane of grape pomace tissues, thus intensifying the subsequent extractability of TPC (15%), FC (60%), TAC (23%), TC (42%), and FRAP values (31%) concerning the control extraction. HPLC-PDA analyses showed that, regardless of the application of PEF, the most abundant phenolic compounds were epicatechin, p-coumaric acid, and peonidin 3-O-glucoside, and no degradation of the specific compounds occurred upon PEF application. The optimization of the PEF-assisted extraction process allowed to significantly enhance the extraction yields of high-value-added compounds from red grape pomace, supporting further investigations of this process at a larger scale.

Kinetics modelling of the solid–liquid extraction process of linamarin compounds from cassava leaves assisted by UV-Photobioextractor

Kinetics modelling of the solid–liquid extraction process of linamarin compounds from cassava leaves assisted by UV-Photobioextractor

Short review on mechanical activation in non-metallurgical alumina production

The terms mechano-chemistry and mechanical activation of solid materials were introduced in chemical literature by Ostwald at the beginning of the XX century. Both terms cover a whole range of interconnected phenomena taking place during the mechanical action on solids or their separate parts participating in chemical reactions, phase transitions, mixing and creating composite materials, alloying and crystal growth in the solid state, deformation and changing physical and thermal properties, all of them at low temperature. The common effects of the mechanical activation on solid material are fracturing and reduction of particle sizes, generation of new reactive surfaces, diffusion of atoms of the reactant phase through the product phase, and quite significantly, accumulating energy in crystalline or amorphous structure (enough twists in atomic and molecular networks, tensions in atomic bond and active sites to trigger the nucleation of new phases). Mechanical activation is very used to produce all clean alumina mineralogical phases with uniform particle size dimensions from nano to macro size. Also, mechanical activation may extend the specific surface of some minerals, enhancing the yields in the solid-liquid extraction process. With adequate precursors, all phase transitions from amorphous to alfa α-Al2O3 can be carried out on the same route as in thermally activated alumina, but some other routes, impossible by thermal activation, might be followed. The difference between the two activation ways is that mechanical activation is made at room temperature.

High Efficiency and New Potential of RSLDE: A Green Technique for the Extraction of Bioactive Molecules from Not Completely Exhausted Plant Biomass and Organic Industrial Processing Waste

A product is characterized by low environmental impact if, during the whole process (from extraction of raw materials from solid natural matter to disposal), its negative contribution to environment modification is significantly reduced or eliminated. According to circular economy, it is important to take into consideration other aspects, such as the possibility to improve the efficiency of extraction process by modifying the principle on which it is based and allowing the recovery of not completely exhausted waste, obtaining other active ingredients, and favoring the recycling of normally eliminated materials. The purpose of this work was to propose more efficient and greener alternatives to conventional solid–liquid extraction processes. Major features are the rapidity of the process, extraction at room temperature and high yields. Rapid Solid–Liquid Dynamic Extraction (RSLDE) represents an innovative solid–liquid extraction technology that allows the solid matrices containing extractable substances in an organic or inorganic solvent and their mixtures to be exhausted in shorter time than current techniques. The principle at the basis of this novel process consists of the generation of a negative pressure gradient between the inside and the outside of the solid matrix, which induces the extraction of compounds not chemically linked to the solid matter, being insoluble in the extractant liquid. Therefore, this work focuses on how RSLDE can potentially bring several improvements in the field of solid–liquid extraction, especially for industrial applications.

Homogenization of Green SiO2 from Rice Husk Burn through Potassium Hydroxide Solid-Liquid Extraction

In the agricultural countries, rice husk is an abundant waste, especially as one of the largest sources of silica (SiO2) production that can be produced. By complete combustion, to about 87% - 97% SiO2 content can be produced from rice husks. Alkaline solution is used as a solvent in the solid-liquid extraction process of rice husk ash. The mass of 10 grams of rice husk ash was weighed for the extraction process added with 80 ml of potassium hydroxide (KOH) solution with 10%, 15% and 20% various concentration for 60 minutes to extract the SiO2 content. The solution was added with 1 N hydrochloric acid (HCl) solution to precipitate the SiO2, after the extraction process was complete. The SiO2 formed is then separated from the rest of the solution by filtration. Next step is the drying process which aims to remove the moisture content of the resulting SiO2. In a systematic study, for 60 minutes the rice husks were soaked and washed using HCl and then heated in a muffle furnace. The results of this study showed that all samples are succeeded in homogenizing SiO2 with a purity close to 90%. Furthermore, through X-Ray Fluorescence (XRF) analysis was proven these results obtained through solid-liquid extraction of KOH from rice husks. Green SiO2, known as biosilica, is useful and has potential in reinforcing compounds, including applications as filler in tires and natural rubber compounds.

Study of Cellulose Extraction from Robusta Coffee Husk Using NaOH Solution

This study reports on manufacturing cellulose from robusta coffee husks through a solid-liquid extraction process. A high yield of cellulose can be achieved by extraction using 3.5% HNO3 at a temperature of 100 oC with a gain of 35.4%. Meanwhile, the extraction process with 4.5% HNO3 at a temperature of 80 oC only achieved a yield of 32.8%. From the results of this study, it can be seen that the smaller the concentration of HNO3 used and the higher the temperature, the greater the yield of cellulose produced. The X-ray diffraction pattern shows high peaks appearing at an angle of 2θ around 22.5o; this area is a typical peak of the cellulose structure. High crystallinity was obtained at a concentration of 3.5% HNO3 at a temperature of 100 oC at 82.47%, while the lowest crystallinity was found at a 5.5% HNO3 concentration at a temperature of 100 oC at 74.27%. The decrease in crystallinity was caused by the high temperature and concentration of HNO3, which caused the acid to penetrate quickly into the cellulose tissue layer and hydrolyze the crystalline regions of cellulose. FT-IR analysis showed a high absorption area at 3314 cm-1 and a low absorption area at 1028 cm-1, typical of Robusta coffee husk cellulose. The absorption located around the 3314 cm-1 bands is a stretch of the –OH group and the absorption in the 1028 cm-1 band is related to the -CH2 group. SEM can show the morphology of cellulose with smaller and uniform crystal dimensions with a scale of 20 µm.

Optimization of Pulsed Electric Fields-Assisted Extraction of Phenolic Compounds From White Grape Pomace Using Response Surface Methodology

This study was focused on the optimization of the pulsed electric fields (PEF)-assisted extraction process using central composite design for response surface methodology from response surface methodology (RSM) with the aim to sustainably intensify the extractability of phenolic compounds from white grape pomace. The cell disintegration index (Zp) was used as response variable to identify the optimal PEF pre-treatment conditions of grape pomace in terms of field strength (E = 0.5–5 kV/cm) and energy input (WT = 1–20 kJ/kg), to be applied prior to the subsequent solid-liquid extraction (SLE) process. for both untreated and PEF-treated samples SLE process was optimized to determine the most effective combination of extraction temperature (20–50°C), extraction time (30–300 min), and solvent concentration (0–100% ethanol in water). Total phenolic content (TPC), flavonoid content (FC), and antioxidant activity (FRAP) of the obtained extracts were determined. The extracted compounds from untreated and PEF-treated samples at the optimal conditions were analyzed via HPLC-PDA analysis. Results revealed that, at a fixed extraction temperature (50°C), the application of PEF at optimal processing conditions (E = 3.8 kV/cm, WT = 10 kJ/kg) prior to SLE has the potential to reduce the solvent consumption (3–12%) and shorten the extraction time (23–103 min) to obtain the same recovery yield of phenolic compounds. Under optimized conditions, the extracts derived from PEF-treated samples showed significantly higher TPC (8%), FC (31%), and FRAP (36%) values, as compared to the control extraction. HPLC analyses revealed that epicatechin, p-coumaric acid, and quercetin were among the main phenolic compounds extracted, and no degradation phenomena occurred due to PEF application.

Pulsed Electric Field-Assisted Extraction of Aroma and Bioactive Compounds From Aromatic Plants and Food By-Products.

In this work, the effect of pulsed electric field (PEF) pre-treatment on the extractability in green solvents (i. e., ethanol–water mixture and propylene glycol) of target aroma and bioactive compounds, such as vanillin from vanilla pods, theobromine and caffeine from cocoa bean shells, linalool from vermouth mixture, and limonene from orange peels, was investigated. The effectiveness of PEF as a cell disintegration technique in a wide range of field strength (1–5 kV/cm) and energy input (1–40 kJ/kg) was confirmed using impedance measurements, and results were used to define the optimal PEF conditions for the pre-treatment of each plant tissue before the subsequent solid–liquid extraction process. The extracted compounds from untreated and PEF-treated samples were analyzed via GC-MS and HPLC-PDA analysis. Results revealed that the maximum cell disintegration index was detected for cocoa bean shells and vanilla pods (Zp = 0.82), followed by vermouth mixture (Zp = 0.77), and orange peels (Zp = 0.55). As a result, PEF pre-treatment significantly enhanced the extraction yield of the target compounds in both solvents, but especially in ethanolic extracts of vanillin (+14%), theobromine (+25%), caffeine (+34%), linalool (+114%), and limonene (+33%), as compared with untreated samples. Moreover, GC-MS and HPLC-PDA analyses revealed no evidence of degradation of individual compounds due to PEF application. The results obtained in this work suggest that the application of PEF treatment before solid–liquid extraction with green solvents could represent a sustainable approach for the recovery of clean labels and natural compounds from aromatic plants and food by-products.

Solid-liquid Extraction of Soluble Carbohydrates from Soybean Meal: an Experimental Study, Kinetics, and Modeling

HIGHLIGHTS SPC is obtained by solid-liquid extraction process with hydroalcoholic solvent. Box-Behnken was applied to evaluate the effect of operational parameters. Soluble carbohydrate extraction from DSM is limited by intraparticle diffusion. Diffusion coefficient of stachyose, raffinose, sucrose, and glucose was estimated.

Kinetic modelling of the solid\u2013liquid extraction process of polyphenolic compounds from apple pomace: influence of solvent composition and temperature

This study aims to assess kinetic modelling of the solid–liquid extraction process of total polyphenolic compounds (TPC) from apple pomace (AP). In this regard, we investigated the effects of temperature and solvent (i.e. water, ethanol, and acetone) on TPC extraction over various periods. The highest TPC yield of 11.1 ± 0.49 mg gallic acid equivalent (GAE)/g db (dry basis) was achieved with a mixture of 65% acetone–35% water (v/v) at 60 °C. The kinetics of the solvent-based TPC extraction processes were assessed via first-order and second-order kinetic models, with an associated investigation of the kinetic parameters and rate constants, saturation concentrations, and activation energies. The second-order kinetic model was sufficient to describe the extraction mechanism of TPC from AP. This study provides an understanding of the mass transfer mechanism involved in the polyphenolic compound extraction process, thus facilitating future large-scale design, optimization, and process control to valorize pomace waste.Graphical

Microwave Pretreatment for the Extraction of Anthocyanins from Saffron Flowers: Assessment of Product Quality.

The potential of saffron flowers as a source of polyphenols, and in particular anthocyanins, for the extraction of bioactive compounds and the production of a cyanic colorant was analyzed. A microwave pretreatment, prior to the conventional solid–liquid extraction process, was proposed as a feasible intensification step. The effectiveness of microwave pretreatment was assessed in terms of increased yield and improved quality of the final product. The operational variables studied were the pretreatment temperature (60–120 °C) and the solid–liquid ratio (0.30–0.50 g/mL). It was found that the addition of the microwave pretreatment to the conventional process allowed one to reduce extraction time by up to 12 times and to greatly improve the characteristics of the final product, using microwave energy densities as low as 0.16–0.54 kJ/mL. The extract quality was evaluated in terms of polyphenol richness (25% increase), product composition (80% of the anthocyanins was delphinidin), antioxidant capacity (boosted by the pretreatment) and color (variations in red and blue hue depending on conditions). To conclude, a microwave pretreatment in which the material is heated to a temperature of 65 °C with a solvent ratio of 0.30 g/mL was selected as the optimum to maximize process efficiency and product quality.