Solid-liquid extraction ( ionic liquid)
Denifintion
➢ Solid-Liquid Extraction is a solid-liquid contact mass transfer operation in which solute particles are transferred from solid to liquid
➢ Solid-liquid extraction also called Leaching is
➢ Solid-liquid extraction works on the principle of difference in solubility of specified solids in liquids
➢ The liquid used for solid-liquid extraction is called the solvent The Solid which carries solute particles is called an insoluble solid (Inc, 2009)
Ionic liquids (ILs) are recognized as exceptional solvents due to their unique properties, including negligible vapor pressure, high thermal stability, tunable viscosity, and compatibility with both water and organic solvents These characteristics stem from their nature as molten salts that remain liquid below 100°C, typically composed of organic cations such as imidazolium, pyrrolidinium, or tetraalkyl ammonium, combined with inorganic or organic anions like tetrafluoroborate or hexafluorophosphate.
Ionic liquids (ILs) are often referred to as "designer solvents" due to their extensive range of combinations, which results in varying properties such as polarity, hydrophobicity, and viscosity.
Table 1 The structures of the ILs applied in extraction and separation:
Solid- liquid Extraction Process
1.2.1 Principle of Solid Liquid Extraction –
Solid-Liquid Extraction occurs in two steps:
• Contacting solvent and solid to effect a transfer of a solute (leaching)
• The separation of the solution from the remaining solid (washing)
❖ Factors Affect Solid-Liquid Extraction Operation
1 Solid: Solid used for solid-liquid extraction can be porous or nonporous The solute may be distributed on a solid surface or inside pores of solid
Recovering solute from solid surfaces is generally more efficient than extracting it from solid pores, as the latter introduces additional mass transfer resistance for both the solvent and the solute Additionally, the size of solid particles significantly influences the recovery process, with smaller particles allowing for easier and more effective solute recovery compared to larger ones.
2 Solvent: The solvent used for operation is also an important parameter to take into consideration in operation The solvent which contains desirable properties which are listed below is more preferred
3 Temperature: Temperature is also an important parameter in solid-liquid extraction because the solubility of solid particles is also dependent on temperature
4 Mixing: Mixing of solid particles and liquid solvent decides the effectiveness of contact which is also important for parameter solid-liquid extraction More thorough mixing confirms more contact between solid and liquid and this results in higher mass transfer
➢ Solid-liquid extraction there are steps
2 Mixing of solids with solvent Liquid
4 Solvent recovery from overflow and underflow
➢ Solid-liquid phase extraction is achieved through the interaction of three components:
➢ Type of ionlic liquid extraction
This section is thus divided into three parts based on the most frequently employed extraction processes:
Solid-Liquid Extraction Equipment
The Soxhlet extractor is an essential device for liquid-solid extractions, particularly when the target compound has limited solubility in the selected solvent while impurities remain insoluble During the extraction process, solvent vapor ascends through the distillation path into the main chamber and condenser, where it condenses and drips down to fill the chamber This solvent dissolves the desired compound from the solid sample, and once the chamber is nearly full, the siphon empties it, returning the solvent to the round bottom flask to restart the cycle With each repetition, more of the desired compound is extracted, leaving behind insoluble impurities in the thimble, effectively isolating the compound from the sample.
➢ The Soxhlet extractor will run continuously once set up correctly:
➢ Load the sample material containing the desired compound into the thimble
➢ Place the thimble into the main chamber of the Soxhlet extractor
➢ Add the chosen solvent to a round bottom flask and place onto a heating mantle
➢ Attach the Soxhlet extractor above the round bottom flask
➢ Attach a reflux condenser above the extractor, with cold water entering at the bottom and exiting above
➢ Now the apparatus is set up, heat the solvent to reflux and leave to extract for the required amount of time
The extractor, commonly utilized for extracting vegetable oils from seeds, features a series of baskets attached to an endless chain that moves through a vapor-tight chamber Each basket has a perforated wire-mesh bottom, allowing liquids to flow into two sumps that collect the extract streams Solid material is introduced into the top basket of the descending leg, where a partially enriched extract (50% extract) is sprayed onto it As the liquid percolates through the slowly moving basket, it gathers in one of the bottom sumps Fresh extractant is then sprayed onto the top basket of the ascending leg, which also percolates through to collect in the second sump as a 50% extract This counter-current and co-current percolation process occurs in a tower that can reach heights of 15 to 20 meters, with spent solids discharged from the top hopper via a screw conveyor.
This process has the following advantages and disadvantages :
1.Can be integrated into continuous process
3.Final extract is fairly concentrated
1.Cost of equipment is high
2.Large equipment, so maintaining stable optimal thermal profile is difficult
3.Hydraulic conductivity of soaked leaves is low and it impairs percolation Sometimes chanelling through leaf matrix also occurs which also have adverse effect on extraction efficiency
Modern extraction systems utilize a dual-tube design for the efficient extraction of various natural products In this setup, solids are introduced via a feed hopper into a horizontal tube equipped with a slow-moving screw conveyor that transports the material The horizontal tube connects to an angled section where an extractant is introduced through a solvent entry port This countercurrent flow allows the solid to interact with the extractant as it moves through both the horizontal and angled tubes The solid is then elevated in the angled tube, where it is drained and discharged at the end, while the extracted liquid flows out through an outlet at the horizontal section's end For optimal performance, the entire unit can be steam-jacketed to maintain precise temperature control.
2.Extraction is through immersion method, so hydraulic conductivity is not an issue in extraction stage
4.High concentration of the product in the extract due to countercurrent extraction
1.Hydraulic conductivity may be an issue in the draining stage
2.Precision mechanical parts need high maintenance
1.3.4.Bonotto Extractor the solids during their passage through the unit The design offers the obvious advantages of countercurrent action and continuous solids compaction, but there are possibilities of some solvent loss and feed overflow, and successful operation is limited to light, permeable solids
A somewhat similar but simpler design uses a horizontal screw section for leaching and a second screw in an inclined section for washing, draining, and discharging the extracted solids
In the De Danske Sukkerfabriker, the axis of the extractor is tilted to about 10° from the horizontal, eliminating the necessity of two screws at different angles of inclination
Sugar-beet cossettes are effectively extracted during their upward transport in a vertical tower, utilizing inclined plates or wings attached to an axial shaft This process is enhanced by staggered guide plates along the tower wall, while water fills the shell and flows downward as the beets ascend This setup is utilized in the BMA diffusion tower, ensuring efficient extraction.
Screw-conveyor extractors, previously common for extracting flaked oil seeds, are now largely obsolete due to their damaging effects on the delicate seed flakes, as noted by Schwartzberg.
The tray classifier, similar to the screw-conveyor classifier, operates by raking pulp along the sloped bottom of a tank while solvent flows countercurrent A baffle directs the solvent to the tank's bottom before it overflows, ensuring efficient separation It is essential that the solids are durable enough to withstand the raking process.
1.3.5.Kennedy extraction interial into or from the interior of the solid particles rather than the rate of transfer to or from the surface of particles, the main function of the agitator is to supply unexhausted solvent to the particles while they reside in the tank long enough for the diffusive process to be completed The agitator does this most efficiently if it just gently circulates the solids across the tank bottom or barely suspends them above the bottom
The separation of leached solids from the extract can be achieved through methods such as settling and decantation, as well as using external filters, centrifuges, or thickeners However, a key challenge in this process is the difficulty of separating solids from the extract, compounded by the limitation of batch stirred tanks, which only offer a single equilibrium stage.
Pachuca tanks are large, vertical cylindrical vessels used for batch-leaching ores containing gold, uranium, and other metals Typically measuring 7 meters in diameter and 14 meters in height, these tanks feature a conical bottom section with a 60° angle Air is usually introduced through a central vertical tube, about 46 cm in diameter, which extends from the bottom to just above the liquid surface This air creates significant pulp flow within the tank, facilitating the movement of the material down the tank's outer walls and back into the riser, enhancing the leaching process.
Applications of Solid-Liquid Extraction(Ionic-liquid)
IL-based SLE techniques utilizing pure ionic liquids (ILs), along with their aqueous solutions and IL-methanol/ethanol mixtures, are effective for the extraction and separation of various natural compounds, including alkaloids, terpenoids, flavonoids, phenolics, saponins, and lignans.
➢ The use of IL aqueous solutions on the SLE of
• alkaloids (e.g., glaucine from Glausium flavum)
• galantamine, narwedine, -desmethylgalantamine, and ungiminorine from N the aerial parts of Leucojum aestivum
Ionic liquid-supported solid-liquid extraction of bioactive alkaloids II Kinetics, modeling and mechanism of glaucine extraction from Glaucium flavum Cr
(Ivan Svinyarov, Rozalina Keremedchieva, Milen G Bogdanov, 2016)
All chemicals utilized in this study were sourced from Sigma-Aldrich (FOT, Bulgaria), with organic solvents being of analytical grade and acetonitrile for HPLC analysis classified as chromatographic grade The ionic liquid (IL) employed for extraction, 1-butyl-3-methylimidazolium acesulfamate {[C4C1im][Ace]}, was synthesized, purified, and characterized by the authors following recently published procedures for hydrophilic ILs, with its structure and purity confirmed through 1H and 13C NMR spectral analysis A silver nitrate test indicated no residual chloride anions Aerial parts of the Glaucium flavum Cr plant and a standard sample of glaucine were obtained from the Laboratory of Natural Products at the Bulgarian Academy of Science The plant material was ground and dried under vacuum to reduce moisture content before extraction, with a particle size of 0.25–0.40 mm, and the same batch was consistently used throughout the study.
Glaucine quantification was achieved through reverse phase high-performance liquid chromatography (RPHPLC) using a GBC liquid chromatography system This system included an LC 1100 HPLC pump, a variable LC 1200 UV/Vis detector, an LC 1431 system organizer, and a 20 µL loop injector, with data analysis conducted using N2000 software.
ZORBAX Extend-C18 (150 4.6 mm i.d., 5 lm) was used as an analytical column The mobile phase was a mixture of 0.1% triethylamine aqueous solution and acetonitrile (50:50) delivered at a flow rate of 1 mL/min The
The UV detection wavelength was optimized at 280 nm, where aporphine alkaloids exhibit maximum absorption Each injection volume was set at 20 µL, with the column maintained at ambient temperature Under these conditions, glaucine, the target alkaloid, was successfully baseline separated, showing a symmetrical peak Identification of the peak was confirmed by comparing its retention time with that of a standard solution, and glaucine concentration was calculated using a previously established relationship For analysis, aliquots were diluted with a specific volume of acetonitrile/water mixture to align with the linear range of the standard curve, filtered through a 0.45 µm microporous membrane, and directly injected into the HPLC system All analyses were conducted in triplicate, and the mean value was reported.
Pig2 Block diagram for the recovery/production of glaucine from plant material by means of ionic liquids
The Soxhlet extraction procedure aimed to quantify the total glaucine content and identify other alkaloids in G flavum Approximately 5 g of dried and milled plant material was subjected to extraction with 200 mL of methanol for 24 hours at normal pressure, with results showing less than 2% variation across duplicate experiments HPLC analysis revealed no significant presence of other aporphine alkaloids, while the glaucine content was determined to be 1.8 wt%, establishing a baseline for subsequent studies.
• Batch extraction of plant material
The IL-supported solid-liquid extraction experiments utilized a 100 mL round-bottom flask with a condenser and internal thermal probe, maintaining a constant temperature of 80°C through a magnetic stirrer with a PEG-400 bath A 1 M [C4C1im][Ace]-aqueous solution was stirred and heated before introducing 2.5 g of milled and dried G flavum plant material for extraction at 200 rpm for approximately 30 minutes Following extraction, the hot extract was filtered into a graduated cylinder, and the residual biomass was washed with fresh 1 M [C4C1im][Ace]-aqueous solution to recover the initial extractant volume To enhance glaucine concentration, the extraction process was repeated nine additional times using the same IL-aqueous solution without interim purification.
A stock solution of 100 mL crude IL-based extract was prepared, containing a glaucine concentration of 3.98 mg/mL, which served as the basis for subsequent recovery studies The residual biomass from these experiments was collected to recover and regenerate the lost ionic liquid (IL) For comparison, a similar extraction procedure was conducted using methanol as the extractant, with the extractions performed for 1 hour under reflux conditions.
• Back-extraction with organic solvents
A preliminary screening was conducted to evaluate the back-extraction capability of various molecular liquids using 15 mL centrifuge tubes The process involved shaking crude extracts with water-immiscible organic solvents, including toluene, ethyl acetate, tert-butylmethyl ether, n-butanol, dichloromethane, and chloroform, in a 2:1 volume ratio Following phase separation, the volumes of each phase were measured, and the glaucine content in the IL-aqueous phase was analyzed as detailed in Section 2.2 The extraction efficiency percentage (EE%) was calculated using Equation (3).
• Glaucine isolation and IL recycling
A 100 mL crude glaucine extract was processed using 50 mL chloroform in a separating funnel, where the aqueous phase was reserved for IL regeneration The chloroform phase underwent two washes with deionized water and hydrobromic acid solution before being dried over sodium sulfate The solvent was evaporated, and the residue was dissolved in ethanol, leading to the precipitation of glaucine hydrobromide salt upon the addition of HBr-ethanolic solution The resulting pink crystals (0.29 g, 60% yield) exhibited a melting point of 233-235 °C, indicating a purity level exceeding 95% Further purity verification was conducted using HPLC, and structural confirmation was performed via NMR analyses The recycling of [C4C1im][Ace] from the residual IL-aqueous phase involved removing water under reduced pressure, dissolving the residue in dry dichloromethane, filtering, and evaporating the organic solvent, resulting in a residue confirmed as [C4C1im][Ace] through NMR and IR analyses.
Pig3 Schematic diagrams of integrated processes based on ILs comprising the extraction and separation of small organic extractable compounds from biomass and further IL recovery and reuse
Microwave-assisted extraction is an effective technique for obtaining natural compounds from raw plant materials This method utilizes microwave energy to heat solvents that contain the samples, facilitating the separation of analytes from the sample matrix into the solvent.
• Microwave extraction allows organic compounds to be extracted more rapidly, with similar or better yield as compared to conventional extraction methods
• Microwave theory: Microwaves are made up of two oscillating perpendicular field’s i.e electric field and magnetic field
Types of microwave extraction method:
This method has been validated with a 1:1 mixture of hexane and acetone across various matrices, including soil, glass fibers, and sand Additionally, other solvent systems may be suitable for microwave extraction, as long as at least one component is capable of absorbing microwave energy.
• Extractant-Free MAE Solvent-free microwave extraction (SFME) is a combination of microwave heating and dry distillation, performed at atmospheric pressure without adding any organic solvent or water
2.2 Principles of Microwave-Assisted Extraction
Microwave-assisted extraction (MAE) utilizes nonionizing electromagnetic waves, with frequencies between 300 MHz and 300 GHz, to disrupt cellular structures in sample matrices This process involves heating molecules through ionic conduction and dipole rotation, which occur simultaneously in both the solvent and the sample, effectively converting microwave energy into thermal energy Ionic conduction generates heat due to the medium's resistance to ion flow, while the movement of dissolved ions leads to molecular collisions as ions change direction with the oscillating electromagnetic field.
The dipolerotation is related to the alternative movement of polar molecules, which try to line up with the electric field (Fig.1 ).
Dipolar polarization (also refereed as orientation polarization) is the most significant heating mechanism in microwave extraction
Fig 1 Polarization and relaxation of dipoles according to the field
➢ Plant cells contain tiny microscopic traces of moisture that serve as the target for microwave heating
➢ The evaporation of moisture present inside the plant cell on heating due to microwave energy generates a great pressure on the cell wall due to swelling of the plant cell
➢ The pressure pushes the cell wall from inside, stretching and ultimately rupturing it This facilitates leaching out of the active constituents from the broken cells
Fig Mass and heat transfer gradients in conventional and microwave-assisted 2 extraction (MAE)
Optimization of the MAE Process
When applying Microwave-Assisted Extraction (MAE), it is crucial to consider various experimental factors that impact its effectiveness Key variables influencing MAE performance include the type of solvent and matrix used, the size and moisture content of the sample, the volume of solvent, microwave power, exposure time, and temperature.
The viscosity of a sample significantly influences its capacity to absorb microwave energy, as it impacts molecular rotation High viscosity limits molecular mobility, hindering the molecules' alignment with the microwave field, which results in a lower dielectric dissipation factor.
In Microwave-Assisted Extraction (MAE), the temperature is influenced by the solvent's microwave absorption capability and the applied microwave power Elevated temperatures typically improve extraction efficiency by increasing the solvent's ability to solubilize target compounds, enhancing diffusivity within the matrix, and facilitating desorption from active sites However, it is crucial to exercise caution when working with thermolabile substances, as high temperatures may lead to their degradation.
• Pressure is a highly influential factor in closed-vessel systems The development of vessels capable of withstanding pressures as high as
41 bar (435 psi) has enabled extraction at very high temperatures, thereby increasing dramatically the extraction efficiency with the consequent decrease of the required exposure time
• The selection of the organic solvents should account for three facts:
1 The microwave-absorbing properties of the solvent (and the ability of the solvent to convert this energy into heat)
2 Preferably the solvent should have a high selectivity toward the analyte of interest excluding unwanted matrix components
3 The interaction of the solvent with the matrix
➢ The MAE process is as follows:
• Generation of tremendous pressure on cell wall
• Leaching out of phyto-constituents
This phenomenon can be intensified if the plant matrix is impregnated with solvents with higher heating efficiency under microwave
Introduction
Microwave-assisted extraction is an effective technique for extracting natural compounds from raw plant materials This method utilizes microwave energy to heat solvents that contain the samples, facilitating the partitioning of analytes from the sample matrix into the solvent.
• Microwave extraction allows organic compounds to be extracted more rapidly, with similar or better yield as compared to conventional extraction methods
• Microwave theory: Microwaves are made up of two oscillating perpendicular field’s i.e electric field and magnetic field
Types of microwave extraction method:
This method has been validated with a 1:1 mixture of hexane and acetone, effectively extracting from matrices like soil, glass fibers, and sand Additionally, other solvent systems could be suitable for microwave extraction, as long as at least one component is capable of absorbing microwave energy.
• Extractant-Free MAE Solvent-free microwave extraction (SFME) is a combination of microwave heating and dry distillation, performed at atmospheric pressure without adding any organic solvent or water
Principles of Microwave-Assisted Extraction
Microwave-assisted extraction (MAE) utilizes nonionizing electromagnetic waves, ranging from 300 MHz to 300 GHz, to disrupt cellular structures within a sample matrix This process involves heating molecules through ionic conduction and dipole rotation, which occur simultaneously in both the solvent and the sample, effectively transforming microwave energy into thermal energy Ionic conduction generates heat as the medium resists ion flow, while the movement of dissolved ions leads to molecular collisions, influenced by the alternating direction of the electric field.
The dipolerotation is related to the alternative movement of polar molecules, which try to line up with the electric field (Fig.1 ).
Dipolar polarization (also refereed as orientation polarization) is the most significant heating mechanism in microwave extraction
Fig 1 Polarization and relaxation of dipoles according to the field
➢ Plant cells contain tiny microscopic traces of moisture that serve as the target for microwave heating
➢ The evaporation of moisture present inside the plant cell on heating due to microwave energy generates a great pressure on the cell wall due to swelling of the plant cell
➢ The pressure pushes the cell wall from inside, stretching and ultimately rupturing it This facilitates leaching out of the active constituents from the broken cells
Fig Mass and heat transfer gradients in conventional and microwave-assisted 2 extraction (MAE)
Optimization of the MAE Process
In the practical application of Microwave-Assisted Extraction (MAE), several experimental factors must be considered to optimize performance for a specific system Key variables influencing MAE include the type of solvent and matrix, sample size and moisture content, solvent volume, microwave power, exposure time, and temperature.
The viscosity of a sample significantly influences its capacity to absorb microwave energy, as it impacts the rotation of molecules High viscosity limits molecular mobility, hindering the alignment of molecules with the microwave field, which consequently results in a lower dielectric dissipation factor.
In Microwave-Assisted Extraction (MAE), the temperature significantly influences the solvent's ability to absorb microwaves and the applied microwave power Generally, elevated temperatures improve extraction efficiency by enhancing the solvent's capacity to solubilize target compounds, increasing its diffusivity into the matrix, and facilitating the desorption of components from active sites However, caution is necessary when working with thermolabile substances, as high temperatures may lead to their degradation.
• Pressure is a highly influential factor in closed-vessel systems The development of vessels capable of withstanding pressures as high as
41 bar (435 psi) has enabled extraction at very high temperatures, thereby increasing dramatically the extraction efficiency with the consequent decrease of the required exposure time
• The selection of the organic solvents should account for three facts:
1 The microwave-absorbing properties of the solvent (and the ability of the solvent to convert this energy into heat)
2 Preferably the solvent should have a high selectivity toward the analyte of interest excluding unwanted matrix components
3 The interaction of the solvent with the matrix.
Microwave extraction process
➢ The MAE process is as follows:
• Generation of tremendous pressure on cell wall
• Leaching out of phyto-constituents
This phenomenon can be intensified if the plant matrix is impregnated with solvents with higher heating efficiency under microwave.
Microwave Assisted Extraction equipment
2.4.1 Soxhlet Extractor the FMASE is identical to a conventional Soxhlet apparatus, except that it affords irradiation with focused microwaves for a preset time during each extraction cycle while fresh extractant is recirculated through the solid sample The operational variables amenable to optimization in the FMASE prototype are irradiation power, irradiation time and number of cycles Unlike a conventional Soxhlet extractor, the microwave-assisted Soxhlet system allows up to 75 85% of the total extractant – volume to be recycled Electrical heating of the extractant, the efficiency of which is independent of its polarity, is also crucial here Moreover, the efficiency is unaffected by the moisture content of the sample
The flask holding the solid material,
The extraction vessel, designed for microwave radiation, features a polytetrafluoroethylene (PTFE)/graphite stir bar that absorbs microwaves and distributes heat, essential for solvents transparent to microwave radiation It includes an inner PTFE support for solid material placement, ensuring separation from residual solvent after extraction A condenser atop the extraction tube, equipped with switching valves, facilitates solvent reflux during microwave irradiation for thorough extraction or concentration of the extract The process begins with the immersion of the sample in n-hexane, followed by microwave heating to the solvent's boiling point, allowing vapors to condense and drip onto the sample The solvent level is then lowered, followed by repeated leaching with fresh solvent, and finally, the solvent is concentrated by reducing its level in the vessel.
Figure 5 (a) Dynamic focused microwave-assisted extractor (b) Experimental setup used to integrate microwave-assisted extraction with the subsequent steps of the analytical process
Dynamic microwave-assisted extractors were developed later than open-vessel systems due to the limitations imposed by high-pressure operations compared to atmospheric pressure The initial design was intricate and specifically required solid samples, leading to the creation of the 'microwave-assisted integrated Soxhlet extractor.' For further information, please refer to the original text by Veggi, P C and Martinez, J.
Meirells, M A A In Microwave-Assisted Extraction for Bioactive Compounds: Theory and Practice; Chemat, F., Cravotto, G., Eds.; Microwave-Assisted
Recent advancements in extraction technology have eliminated the need for a nitrogen bomb by allowing the direct introduction of solid samples, enabling continuous pumping of fresh extractant into the system A new commercial system, the Voyager module, has been developed on the Discover platform to automate and scale up microwave-assisted treatments for both continuous and stop-flow processing This innovative system allows for the same parameters used in the Discover system to be applied when scaling up from milligram quantities to approximately 1 kg, ensuring consistent results Additionally, a dynamic stirring device is incorporated to achieve homogeneous and uniform mixing throughout the process.
1 The device consists of the follows:
2 Extraction device and soild and liqud separator concentration, purification and solvent recovery systems
5 Automatic control and PLC systems
The extraction of traditional Chinese medicine primarily utilizes high-frequency electromagnetic fields In this process, plant granules in a polar solvent absorb the solvent, allowing polar molecules to interact with the microwave electromagnetic field This interaction causes the molecules to absorb microwave energy and become polarized Under the influence of an alternating current high-frequency electromagnetic field, both polar and non-polar molecules undergo repetitive polarization, resulting in vigorous rotation This process occurs at a frequency of 2.45 billion times per second.
The intense collisions and abrasions experienced by plant cells generate significant heat energy, leading to the expansion of liquid bubbles and cell wall rupture This process facilitates the rapid dispersion of the solution due to the increasing temperature Furthermore, the breakdown of cell structures allows for the efficient leaching of valuable contents, achieving the extraction goal Microwave-Assisted Extraction (MAE) is characterized by its energy efficiency, reduced consumption, environmental friendliness, high yield, excellent quality, and enhanced benefits.
Application of MAE
Microwave-assisted extraction has been widely applied for extraction of :
❖ Optimization of Microwave-Assisted Extraction for the Recovery of Bioactive Compounds from the Chilean Superfruit (Aristotelia chilensis (Mol.) Stuntz)
Maqui berry (Aristotelia chilensis) is gaining attention in the food industry due to its health benefits and high commercial value, driven by its bioactive components Researchers developed a microwave-assisted extraction (MAE) method to analyze total phenolic compounds and anthocyanins from maqui, utilizing a Box Behnken experimental design and response surface methodology across 27 experiments The study identified four key factors: methanol percentage, pH, temperature, and solvent volume:sample mass ratio, with temperature and methanol percentage being the most significant for total phenolics and anthocyanins, respectively Optimal MAE conditions were established at 65% MeOH in water at pH 2 and 100 °C for total phenolics, and 60% MeOH in water at pH 2 and 50 °C for anthocyanins, with an extraction time of just 2 minutes The method demonstrated excellent repeatability and intermediate precision, with coefficients of variation below 5%, and was successfully applied to a food product containing maqui.
The extraction methods were developed using commercially available lyophilized maqui as a powder from organic farming (SuperAlimentos, Mundo Arcoíris,
The final extraction method was assessed by analyzing various real samples of maqui, which were available in different formats such as capsules, pills, and lyophilized material Prior to analysis, both the lyophilized maqui sample and the commercial samples were stored at −20 °C in a freezer.
Methanol and formic acid, both of HPLC grade, were sourced from Fisher Scientific in the UK and Scharlab in Spain, respectively Ultra-pure water was obtained using a Milli-Q water purification system provided by EMD Millipore Corporation in Bedford.
Hydrochloric acid and sodium hydroxide, both of analytical grade from Panreac Química S.A.U in Barcelona, Spain, were utilized for pH adjustment To quantify total phenolic compounds, distilled water and Folin–Ciocalteu reagent from Merck KGaA, EMD Millipore Corporation in Darmstadt were employed.
Anhydrous sodium carbonate was sourced from Panreac Química S.A.U in Castellar del Vallés, Barcelona, Spain, while the phenolic compound standard and anthocyanin standard, gallic acid and cyanidin chloride, were obtained from Sigma-Aldrich Chemical Co in St Louis, MO, USA.
Microwave-assisted extraction (MAE) of maqui was performed using a MARS 6 240/50 kit, with approximately 0.5 g of lyophilized sample placed in an extraction vessel The extraction involved adding a specific volume and type of solvent, with controlled variables including methanol percentage (25–50–75%), pH (2–4.5–7), temperature (50–75–100 °C), and solvent volume to sample mass ratios (10:0.5–15:0.5–20:0.5) The procedure included a 3-minute ramp to the target temperature, followed by a 5-minute extraction period, and a 25-minute cooling phase The power was consistently set at 800 W to achieve the desired temperatures After extraction, the mixture was centrifuged twice for 5 minutes at 11,544 × g, with the supernatant transferred to a 25 mL volumetric flask and topped up with the same solvent The final extracts were stored in a freezer for future analysis.
• Determination of Total Phenolic Compounds
The quantification of the total phenolic compounds was carried out using a Helios Gamma (γ) Unicam UV–Vis spectrophotometer (Thermo Fisher Scientific,
The total phenolic compounds in the samples were measured using a modified Folin Ciocalteu (FC) procedure, which involves the reaction of phenolic compounds with a reagent composed of sodium phosphomolybdate and sodium phosphotungstate, resulting in a blue complex that absorbs light at 765 nm This absorbance is directly proportional to the concentration of polyphenols, in accordance with the Lambert–Beer law Prior to spectrophotometric analysis, extracts were filtered using a 0.45 μm nylon syringe filter The FC assay was conducted by combining 250 μL of extract, 12.5 mL of distilled water, 1.25 mL of Folin Ciocalteu reagent, and 5 mL of 20% anhydrous sodium carbonate in a 25 mL volumetric flask, with the final volume adjusted with water Absorbance measurements were taken after 30 minutes at 765 nm, and a calibration curve was established using gallic acid standards ranging from 100 to 2000 mg L, yielding a high correlation coefficient (R² = 0.9998) Results were reported as milligrams of gallic acid equivalent per gram of lyophilized fruit.
Anthocyanins were identified using ultra-performance liquid chromatography (UHPLC) coupled with a quadrupole-time-of-flight mass spectrometer (QToF-MS) (Xevo G2 QToF, Waters Corp., Milford, MA, USA) The separation process was conducted on a reverse phase C-18 analytical column (Acquity UHPLC BEH C18, Waters Corporation, Milford, Massachusetts).
The study utilized a chromatographic analysis method with a column measuring 100 mm × 2.1 mm and a particle size of 1.7 μm, filtering extracts through a 0.22 μm nylon syringe filter The solvents included Milli-Q water acidified with 2% formic acid (solvent A) and pure methanol (solvent B), both of which were degassed and filtered, with a flow rate set at 0.4 mL/min The elution gradient commenced at 15% B and progressed to 95% B over a total run time of 12 minutes, which included 4 minutes for re-equilibration Analyte determination was conducted using an electrospray source in positive ionization mode, with a desolvation gas flow of 700 L/h and a specific desolvation temperature.
500 °C, cone gas flow = 10 L h , source temperature = 150 °C, capillary voltage = −1
The analysis utilized a cone voltage of 20 V and a trap collision energy of 4 eV, operating in full-scan mode with a mass-to-charge ratio (m/z) range of 100 to 1200 The molecular ions [M]+ for the anthocyanins identified in maqui exhibited the following m/z ratios: delphinidin 3-O-sambubioside-5-O-glucoside at 759, delphinidin 3,5-O-diglucoside at 627, cyanidin 3-O-sambubioside-5-O-glucoside at 743, cyanidin 3,5-O-diglucoside at 611, and delphinidin 3-O-sambubioside.
597; delphinidin 3- -glucoside, 465; cyanidin 3- -glucoside, 449 and cyanidin 3-O OO-sambubioside, 581 These anthocyanins are shown in Figer4.
Perstraction
Introduction
Perstraction is an advanced separation technique derived from liquid-liquid extraction, allowing for a broader range of extractants due to the inclusion of a membrane This method enables the use of miscible solutions, exemplified by the effective recovery of ammonia from wastewater through the application of sulfuric acid.
The perstraction technique simplifies the separation process by utilizing a liquid-phase permeate, effectively addressing the challenges of phase dispersion and separation A fundamental form of this method is known as single perstraction or membrane perstraction.
An advantage is minimizing toxic damage to microorganisms or enzymes Nevertheless, perstraction includes problems like expensive membranes, clogging and fouling of membranes
Permeation through a membrane is a unique extraction process involving simultaneous sorption into and desorption out of the extraction phase In this process, the sample, known as the donor phase, contacts one side of the membrane, leading to the extraction of analytes into the membrane material Meanwhile, the permeated analytes are removed by the stripping phase, or acceptor, on the opposite side of the membrane.
Principles of Pertraction
Pertraction is a process that extracts both volatile and non-volatile organic compounds from liquids, including water, using non-selective membranes A hydrophobic micro-filtration membrane enhances the contact area between the organic extraction product and the liquid to be purified while preventing the two phases from mixing This eliminates the need for separation, resulting in time and cost savings Additionally, the membrane allows for flexible and independent regulation of the flows for both phases, facilitating process optimization This method enables the efficient contact of small quantities of extractant with large volumes of treated liquids, ensuring compact installations.
Pertraction is a new, non-dispersive membrane based extraction process
Organic components from wastewater can be effectively extracted using a hydrophobic micro-porous hollow fiber membrane This process involves immobilizing the interface between the wastewater and the organic extractant, facilitated by a minimal transmembrane pressure gradient of just 0.1 bar.
Process of perstraction
➢ A pertraction installation consists of one or multiple membrane modules in a series configuration (membranes are normally in a hollow fibre configuration in order to realise maximum membrane surface per volume)
1 The extraction liquid thus flows down one side of the membrane (inner side of hollow fibre) And the wastewater is passed along the other side of the membrane (outer side of hollow fibre)
2 The pores of the membrane are then filled with the organic extraction product
3 The polluted substances diffuse from the wastewater, through the membrane and to the extractant
The extractant can be regenerated using (amongst other things) a vacuum film vaporiser It is possible to reuse the extractant.
Specific advantages and disadvantages
➢ The use of a much lower quantity of extraction product
➢ The ability to work without implementing an often time-consuming phase separation between to- -treated liquid and extractant be
➢ Installations are also very compact and use little energy
➢ The membrane could become polluted if membrane-polluting components are present.
Perstraction equipment
The process utilized for the separation of low molecular weight compounds, including sugars, dissolved minerals, and salts, plays a crucial role in various applications Notably, it is commonly used in the desalination of dairy products and the recovery of hydrolyzed proteins, ensuring the efficient extraction and purification of valuable components.
Applications of Perstraction
➢ Amino acids separation through the charged membrane
➢ Removal of pharmaceuticals from water
➢ Hydrophobic gelganamycin separated from aqueous media
Separation of vanillin by perstraction using hydrophobic ionic liquids as extractant phase: Analysis of mass transfer and screening of ILs via COSMO-RS
Vanillin is a widely used flavoring agent found in pharmaceuticals, food, polymers, and perfumes Despite its popularity, natural sources can only fulfill 1% of the industrial demand, which reaches 20,000 tons annually, with prices soaring to $11,000 per kg To meet this growing demand, vanillin can be synthetically produced from lignin at a significantly lower cost.
The alkaline oxidation of lignin yields byproducts like acetovanillone and guaiacol, which closely resemble vanillin, complicating the extraction process Similarly, the biotechnological pathway produces p-hydroxy benzaldehyde, ferulic acid, and synapil alcohol alongside vanillin, diminishing the efficiency of selective separation With these byproducts constituting about 2% w/w in the aqueous solution, effective extraction methods are crucial for obtaining high-purity vanillin.
Fig.Schematic transfer profile in perstraction membrane
The mass transfer rate of vanillin through a membrane can be effectively described using the resistances-series model, which outlines the various stages of mass transport near the membrane This process involves five key stages: (1) convection of vanillin from the bulk solution through the boundary layer; (2) achieving local thermodynamic equilibrium at the interface between PDMS and the aqueous solution; (3) molecular diffusion of vanillin through the membrane; (4) establishing local thermodynamic equilibrium between the ionic liquid (IL) and PDMS; and (5) convection from the boundary layer into the bulk of the IL phase A comprehensive overview of this mass transfer process is illustrated in Fig 1.
The mass transfer flux of vanillin in an aqueous solution can be represented by the equation N(aq) s = kaq( C(aq) b − C(aq) i ), where N(aq) s indicates the flux in mol⋅m−2 s−1, kaq denotes the mass transfer coefficient in m⋅s−1, and C(aq) b and C(aq) i represent the vanillin concentrations in the bulk solution and at the aqueous-membrane interface, respectively As vanillin diffuses through the aqueous phase towards the membrane, it reaches an equilibrium partitioning defined by the concentration C(m) f in the polymer layer at the aqueous feed side Once dissolved in the polymer layer, vanillin is further transferred through molecular diffusion within the polymer matrix.
Fig Experimental perstraction setup used in this work (1) Ionic liquid, (2)
Aqueous solution, (3) Perstraction module, (4) Peristaltic pumps
ILs 1-butyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl) imide,
The synthesis-grade ionic liquids, [bmim][Tf2N] and [omim][Tf2N], along with 99% pure Vanillin (4-hydroxy-3-methoxybenzaldehyde), were sourced from Merck®, while trihexyl-tetradecyl-phosphonium cyanamide [P6,6,6,14][DCA] was obtained from Iolitec® Polydimethylsiloxane (PDMS) membranes were acquired from Kolm in Chile A synthetic vanillin solution was created by dissolving vanillin in MilliQ water, which has a resistivity of over 18 mΩ⋅cm, sourced from a PureLab Classic system.
Table 1 presents the ionic liquids (ILs) utilized in the extraction process, including their abbreviations, cation and anion compositions, and the percentage of water in each IL The selected hydrophobic ILs, such as [bmim][Tf2N] and [omim][Tf2N], were chosen to minimize water permeation through the membrane, as water is the primary component of the feed solution Their selection was based on commercial availability, high purity, and established properties, as noted by Zhang et al The experimental setup, depicted in Fig 2, includes key components such as the ionic liquid, aqueous solution, perstraction module, and peristaltic pumps These ILs were evaluated for their effectiveness in extracting vanillin, focusing on the influence of different cations and anions on extraction performance.
The experimental perstraction setup for vanillin extraction is illustrated in Fig 2, featuring a specially designed flat plate module This system operates with two streams in counter-current mode: the first stream is an aqueous feed solution containing vanillin, while the second stream consists of one of the ionic liquids (ILs) used as the vanillin receiving phase These streams are separated by a polydimethylsiloxane (PDMS) membrane, which has a density of 1200 kg/m³ and is available in two thicknesses, 99 and 160 µm, to evaluate their impact on mass transfer flux The effective surface area for mass transfer provided by the membrane is 152 cm², and it is housed within a poly-based module.
The study investigates the impact of vanillin concentration on transmembrane fluxes using a PMMA membrane module with dimensions of 19 cm in length, 8 cm in width, and 0.3 cm in depth Three concentrations of vanillin—200, 500, and 1000 ppm—were tested in the aqueous feed solution Prior to each perstraction assay, the membrane was acclimatized in the respective solution for six hours to allow for vanillin solubilization These concentrations align with those used in vanillin production via a discontinuous reactor Experimental runs involved recirculating both aqueous feed and ionic liquid over six hours, measuring the decrease in vanillin concentration over time Analysis was conducted using a Waters 600 high-performance liquid chromatography system with a C-18 column and fluorescence flame detector The primary response variable was the instantaneous transmembrane flux (N) of vanillin, measured in mol⋅m−2 s−1, calculated using a specific equation.
Reduction in Butanol Inhibition by Perstraction: Utilization of Concentrated Lactose/Whey Permeate by Clostridium acetobutylicum to Enhance Butanol
Perstraction has been integrated with ABE (acetone butanol ethanol) fermentation to enhance butanol production, addressing the toxicity of butanol to bacteria This technique allows for the immediate removal of butanol from the fermentation environment, mitigating its harmful effects While liquid-liquid extraction (LLE) has been explored for in situ product recovery, its use poses challenges, as the most effective extractants can be toxic to the bacteria and require sterilization before use In contrast, perstraction employs a membrane to separate the fermentation broth from the extractant, thereby avoiding these issues Although perstraction shows promise as a recovery method for ABE fermentation, it remains in the developmental phase.
Clostridium acetobutylicum P262 was preserved as a spore suspension in distilled water at 48°C The study utilized spray-dried sulfuric acid casein whey permeate sourced from the New Zealand Dairy Research Institute in Palmerston.
The medium was prepared by reconstituting it to the required concentration with distilled water and adding 5 g/L of yeast extract from Difco Laboratories, along with additional lactose as needed The pH was adjusted to 5.0 using 1 M NaOH, followed by autoclaving at 121°C, and then cooled under a nitrogen atmosphere to maintain anaerobic conditions Oleyl alcohol was sourced from BDH Chemicals Ltd., and silicone tubing for the membrane was obtained from Elastomer Products Ltd A schematic diagram detailing the process, membrane, and perstractor is available in previous work (Qureshi et al., 1992) The tubing's internal diameter was 3.92 mm, resulting in a membrane area of 0.1130 m², while the oleyl alcohol and extractor remained unsterilized, and the tubing was autoclaved at 121°C for 20 minutes.
Cell concentration in the mixture was measured by optical density method
Gas chromatography was used to determine the concentrations of acetone, butanol, ethanol, acetic acid, and butyric acid, while lactose levels were measured using high-performance liquid chromatography (Ennis and Maddox, 1985) Reactor productivity was assessed by calculating the total ABE produced in grams per liter (gL^-1) divided by fermentation time The yield was expressed as grams of ABE produced per gram of lactose utilized The lactose utilization rate was determined by dividing the lactose consumed (gL^-1) by the corresponding fermentation time Ratios of acids to ABE were computed by dividing the total acids produced (gL^-1) by the total ABE produced (gL^-1) The flux of butanol and ABE through the membrane was calculated by measuring the amount of butanol (in grams) dissolved in oleyl alcohol, divided by the membrane area and the duration of diffusion ABE loss through the tubing was determined by calculating the amount of individual components (or total ABE) over total time, expressed in grams per hour (gh^-1) The total loss of each component was obtained by multiplying the loss rate by the perstraction time, while the overall ABE loss was calculated by summing the losses of acetone, butanol, and ethanol.
A batch fermentation experiment using 60 g/L whey permeate was conducted to evaluate performance, starting with an initial lactose concentration of 48.4 g/L Over a 120-hour period, the fermentation yielded 9.34 g/L of total ABE, achieving a productivity rate of 0.08 g/L/h This process resulted in a lactose utilization of 28.6 g/L, leaving 19.8 g/L of lactose unutilized, primarily due to the toxicity of ABE, particularly butanol (Qureshi et al.).
In a batch reactor using C acetobutylicum, achieving a total ABE concentration of 20 g/L is uncommon Figure 1B illustrates the fluctuations in lactose utilization throughout the fermentation process, with a peak utilization rate of 0.47 g/L/h observed between 56 and 75 hours This fermentation run yielded a solvent production of 0.33, alongside the generation of 0.70 g/L acetic acid and 0.25 g/L butyric acid.