Solid-liquid Extraction Process Research Articles

Comparison between Two Solid-Liquid Extraction Methods for the Recovery of Steviol Glycosides from Dried Stevia Leaves Applying a Numerical Approach

Stevia rebaudiana Bertoni is a perennial shrub belonging to the Asteraceae family. The leaves contain a mixture of steviol glycosides with extraordinary sweetening properties, among which the most important are stevioside and rebaudioside A. These components have a high sweetening power, which is about 300 times that of sucrose, and a negligible calorie content. However, their extraction and purification are not easy. In this paper, the extraction technique under cyclic pressure, known as rapid solid-liquid dynamic extraction (RSLDE), was compared using a Naviglio extractor (NE) with conventional maceration. The aim was to identify an efficient and economically viable method for obtaining high amounts of steviol glycosides in a short time. Furthermore, a numerical model was set up for the solid-liquid extraction process of value-added compounds from natural sources. Several parameters must be evaluated in relation to the characteristics of the parts of the plant subjected to extraction. Therefore, since diffusion and osmosis are highly dependent on temperature, it is necessary to control the temperature of the extraction system. On the other hand, the final aim of this work was to provide a scientific and quantitative basis for RSLDE. Therefore, the results obtained from stevia extracts using the corresponding mathematical model allowed hypothesizing the application of this model to the extraction processes of other vegetable matrices.

Toward a Distinct and Quantitative Validation Method for Predictive Process Modelling—On the Example of Solid-Liquid Extraction Processes of Complex Plant Extracts

Physico-chemical modelling and predictive simulation are becoming key for modern process engineering. Rigorous models rely on the separation of different effects (e.g., fluid dynamics, kinetics, mass transfer) by distinct experimental parameter determination on lab-scale. The equations allow the transfer of the lab-scale data to any desired scale, if characteristic numbers like e.g., Reynolds, Péclet, Sherwood, Schmidt remain constant and fluid-dynamics of both scales are known and can be described by the model. A useful model has to be accurate and therefore match the experimental data at different scales and combinations of process and operating parameters. Besides accuracy as one quality attribute for the modelling depth, model precision also has to be evaluated. Model precision is considered as the combination of modelling depth and the influence of experimental errors in model parameter determination on the simulation results. A model is considered appropriate if the deviation of the simulation results is in the same order of magnitude as the reproducibility of the experimental data to be substituted by the simulation. Especially in natural product extraction, the accuracy of the modelling approach can be shown through various studies including different feedstocks and scales, as well as process and operating parameters. Therefore, a statistics-based quantitative method for the assessment of model precision is derived and discussed in detail in this paper to complete the process engineering toolbox. Therefore a systematic workflow including decision criteria is provided.

MASS TRANSFER IN SOLID-LIQUID EXTRACTION AT HIGH SOLUTE CONCENTRATIONS

The solid-liquid extraction process and some of its influencing factors such as solid-liquid ratio, temperature and salt initial amount have been investigated. Also, mathematical modeling for mass transfer coefficients calculation was applied. An inert porous solid material (coal), impregnated with 10% and 20% mass NaCl or 15% and 30% mass CaCl2, was used. The leaching was conducted in a fixed bed column, in laminar flow. The CaCl2 impregnated samples were investigated in a column with a height/diameter ratio of 2.5, at 20 C, 30 C, and 40 C and the NaCl samples, in a 4.16 height/diameter ratio column, at 30 C, 40 C, 50 C, 60 C. In both cases, liquid flow rates of 3.8 L/h, 7 L/h, 10.6 L/h, 13.3 L/h were used. An increase of the extraction degree with the washing liquid flow rate (up to 10.6 L/h) indicated that the solid-liquid ratio is a crucial factor. Temperature increase has a positive influence on the extraction degree. At the beginning of the process, the salt quantity extracted from the high salt amount sample, using the lowest water flow rate has a similar value to the one extracted from the low salt amount sample, using the highest flow rate. At larger time values (t > 500 s), the extraction degree dependence on the liquid flow rate is similar for the high and low salt samples. Based on the proposed mathematical model, mean time mass transfer coefficient values k.a were calculated and compared to the experimental obtained data.

Selective Separation and Preconcentration of Scandium with Mesoporous Silica.

Separation and preconcentration of scandium (Sc) were successfully achieved using a mesoporous silica support that showed good selectivity for this element. Unmodified mesoporous silica materials were used as an extracting medium in a solid-liquid extraction (SLE) process. Selectivity, extraction capacity, kinetics of extraction, and reusability under acidic conditions were investigated. The results demonstrate the potential of unmodified mesoporous silica materials for the selective separation and preconcentration of Sc. As no chelating ligand was grafted on the silica surface, which is often the case for most solid-phase extraction media for metal-ion separation, the experimental data allow us to hypothesize that the accessible silanols on the material surface are responsible for the selective Sc extraction. This interesting feature would drastically decrease the cost of solid-liquid extraction systems by using unmodified mesoporous silica materials. Moreover, a leachate solution obtained from a real rare-earth element ore was used to determine the performances of the proposed materials in a packed column configuration. The maximum Sc adsorption on the silica material surfaces is moderate (1 mg/g), but it is balanced by a great concentration factor (more than 100 times). The extraction performances are potentially promising, both in terms of selectivity and preconcentration, under the acidic conditions tested.

Experimental and simulation study of nylon 6 solid–liquid extraction process

Abstract The solid–liquid extraction process of nylon 6 to eliminate small molecules, i.e., caprolactam (CL), cyclic dimers (CD) and cyclic trimers (CT), is investigated in detail by both batch extraction experiments and numerical simulations. In the batch extraction experiments, due to the small molecules attaching to the polymeric surface, the basic physical mechanism shifts from surface diffusion to internal diffusion as the extraction proceeded. The experimental data are well reproduced by a diffusion model consisting of two distinct steps, characterized as surface diffusion and internal diffusion. Furthermore, based on the established mass transfer mechanism and diffusion model of the two distinct steps, the equilibrium constants and internal diffusion coefficients of CL, CD and CT are acquired. An industrial countercurrent extraction tower is further simulated. It is found that the extraction efficiency of CL can be significantly improved by increasing the temperature at the bottom portion of the tower. The elimination of CD, which can be greatly promoted by a high-concentration CL-water solution, is controlled by mass transfer resistance, whereas the removal of CL is mainly affected by the equilibrium.

Microwave-assisted extraction in dry fruit of andean species Vaccinium meridionale: Experimental conditions on the recovery of total polyphenols

ABSTRACT Due to their nutraceutical properties, the fruits of the species Vaccinium meridionale, which inhabit the Andean region, are of scientific interest. Microwave-assisted extraction has been applied to different vegetal matrices for to extract efficiently polyphenolic compounds. In this work we study in microwave assisted extraction processes, the effect on the extraction of total polyphenols in dried fruits of Vaccinium meridionale, using response surface methodology. The main objective of this research was to analyze the relationships between power, temperature, solid-liquid ratio, time and ethanol concentration in aqueous media on the effectiveness of total polyphenols recovery in dry fruits of Vaccinium meridionale. A central composite design face-centered with three levels for each variable was used: P = 300 - 900 W; T = 70 -110 °C; L:Srat. = 30:1 - 70:1 w/w; t = 5 - 15 min; [EtOH] = 0 - 80%. In this sense, the effect of the input variables on the recovery of total polyphenols, the optimization process for maximum extraction, and the comparison to other solid-liquid extractions in terms of quantity of total polyphenols, are reported. It was found that the significant variables in the extraction process were ethanol concentration, temperature and time; the best yields were obtained in the range [EtOH] = 44 - 49%, T = 110 °C, and t = 10 - 15 min. In terms of quantity, time and consumption of energy, microwave-assisted extraction technique is more efficient than other solid-liquid extraction processes for the extraction of total polyphenols.

A novel approach for simultaneous determination of E/Z-fluoxastrobins in vegetables and fruits by UHPLC-DAD

In this work, a novel analytical method was established for simultaneous determination of E-fluoxastrobin and Z-fluoxastrobin in vegetables and fruits. After extracted by acetonitrile, the samples were cleansing with dispersive solid liquid extraction (d-SLE) process, and analyzed by ultra high performance liquid chromatography coupled to diode array detection (UHPLC-DAD). The effectiveness of the optimized method was validated by determining the linearity (R2 > 0.99), sensitivity (limits of quantification of 30 μg/kg), recovery (71.3–113.2%), and precision (relative standard deviations, RSDs ≤ 13.9%) in eight vegetable and fruit samples. The results suggested that this method was simple, reliable, and feasible to determine the residues of E-fluoxastrobin and Z-fluoxastrobin in vegetable and fruit samples, which could be further applied to 160 various vegetable and fruit samples.

Ultrasound‐assisted extraction of polyphenols from potato peels: profiling and kinetic modelling

SummaryUltrasound‐assisted extraction (UAE) at 33 and 42 kHz has been investigated in the extraction of polyphenols from peels of two potato varieties, cream‐skinned Lady Claire (LC) and pink‐skinned Lady Rosetta (LR), commonly used in snack food production. Extraction efficacy between the UAE‐untreated (control) and the UAE‐treated extracts was assessed on the total phenolic content and antioxidant capacities (DPPH and FRAP). Application of UAE showed significantly higher recovery of phenolic compounds compared to solid–liquid extraction process alone. Lower ultrasonic frequency (33 kHz) was more effective in recovering polyphenols compared to 42 kHz ultrasonic treatment. The liquid chromatography‐tandem mass spectrometry revealed that chlorogenic acid and caffeic acid were the most prevalent phenolics in LR peels, whereas caffeic acid was dominant in LC peels. Peleg's equation showed a good correlation (R2 > 0.92) between the experimental values and the predicted values on the kinetics of UAE of phenolic compounds.

Usage of Eucalyptus globulus bark as a raw material for natural antioxidant and fuel source

The concept of clean technology was applied in the traditional process of using Eucalyptus globulus bark as fuel in the pulp and paper industry. The bark was investigated for its potential as a source of antioxidants by the solid–liquid extraction process before being used as fuel source. An experiment was set up to determine its antioxidant capacity and heating value. Volatile components of the extracts were also identified and analyzed by gas chromatography–mass spectrometry. The experimental results suggested that ethanol extraction solution at a ratio of 1:20 yielded the highest content of phenolic compounds (674.19 mg of gallic acid/l) and antioxidant capacity (30.53 ± 1.76 mg/l). We also examined and compared the fuel properties of extracted and unextracted bark, and it was found that the fuel properties of extracted and unextracted bark showed no significant difference. These findings suggested that the bark can be put to a better use by extracting the compounds before being ultimately used as fuel source in the traditional process. This might lead to an alternative process for the pulp and paper industry in which the standard process is maintained to obtain the desired products, with the additional extraction process to obtain high-value compounds.

Comprehensive assessment of reproductive toxicity of dimoxystrobin: No classification warranted

In this work, a novel analytical method was established for simultaneous determination of E-fluoxastrobin and Z-fluoxastrobin in vegetables and fruits. After extracted by acetonitrile, the samples were cleansing with dispersive solid liquid extraction (d-SLE) process, and analyzed by ultra high performance liquid chromatography coupled to diode array detection (UHPLC-DAD). The effectiveness of the optimized method was validated by determining the linearity (R2 > 0.99), sensitivity (limits of quantification of 30 μg/kg), recovery (71.3–113.2%), and precision (relative standard deviations, RSDs ≤ 13.9%) in eight vegetable and fruit samples. The results suggested that this method was simple, reliable, and feasible to determine the residues of E-fluoxastrobin and Z-fluoxastrobin in vegetable and fruit samples, which could be further applied to 160 various vegetable and fruit samples.

Kinetics and thermodynamics of the solid-liquid extraction process of total polyphenols, antioxidants and extraction yield from Asteraceae plants

Antioxidants derived from plants are widely used in dietary supplements and have been investigated for the prevention of diseases such as cancer, coronary heart disease and altitude sickness. In order to obtain the highest possible amount of bioactive compounds from plant material, effective extraction procedures are required. One of the most widely used extraction techniques which requires no toxic chemicals is solid-liquid extraction. Mathematical modelling of solid–liquid extraction processes is an important engineering tool in the design process in order to reduce energy, time and chemical reagents consumption. In agreement with that, the aim of this paper was determination of the best suited kinetic model for description of the solid-liquid extraction of bioactive compounds from Asteraceae family plants. In this study, four most common representatives of Asteraceae family were chosen as subjects: camomile (Matricaria recutita L.), dandelion (Taraxacum officinale Web.), marigold (Calendula officinalis) and yarrow (Achillea millefolium L.). Initial extraction rate, extraction capacity, activation energy, Gibbs energy, enthalpy and entropy were determined for all of the four analysed plants. The highest extraction efficiency of total polyphenols content, antioxidants and extraction yield were achieved at the highest extraction temperature of T=80°C for all four plants used in this study. Obtained results for activation enthalpies indicated that the extraction processes were endothermic and Gibbs free energy of activation indicated that they were endergonic and not spontaneous.

Numerical study of different particle size distribution for modeling of solid-liquid extraction in randomly packed beds

Abstract In this paper, the Montan wax extraction as an industrial example for a solid-liquid extraction process is modeled and simulated using 2D and 3D CFD models. Carrying out various simulation studies, the applied particle size distribution of the solid phase is studied concerning its impact on the extraction kinetics and the extraction rates. In the modeling, the solid phase, which is a wax-containing brown coal, is described by establishing 2D models of random packing in cylindrically packed beds. In the study, the applicability of a 2D CFD model is validated against simulation result of a 3D model of a random packing. The random packing of the 2D model considers the same mean particle size with a uniform distribution and a normal distribution, respectively. The simulation result indicates that the extraction rate is greatly increased using the brown coal of a normal particle size distribution, which is a good match with experimental results.

Selective recovery of rosmarinic and carnosic acids from rosemary leaves under ultrasound- and microwave-assisted extraction procedures

Ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE) are currently amongst the foremost green techniques for accelerating extraction processes. Several methods for the efficient recovery of the phenolic compounds from rosemary leaves have so far been proposed, but little data are available on the use of UAE and MAE. The aim of this work is to investigate the efficiency and selectivity of these techniques in recovering fractions of specific phenolic compounds from dried rosemary leaves using solvents that are suitable for food applications. UAE has been carried out by means of a probe system equipped with a titanium horn working at 19.5 kHz (140 W). MAE has been performed in a closed multimode reactor under N 2 (20 bar) at 100 °C. All obtained extracts were dissolved in a defined solvent volume and the solutions were directly analyzed using a combination of the HPLC-DAD-MS and TOF techniques. MAE and UAE in ethanol and acetone dramatically increased phenol yield (more than three times) as compared to more traditional solid–liquid extraction processes. In terms of selectivity, remarkably high rosmarinic acid content (6.8% of the dried extract) was obtained in ethanol under ultrasound (US). Even more impressive is the selectivity of UAE in n -hexane which gave the highest carnosic acid content, up to 13% of the dried extract. In conclusion, non-conventional energy sources and, in particular, high-intensity US have proven themselves to be rapid, efficient, and selective techniques for rosemary leaf extraction and provide fractions with high rosmarinic and carnosic acid contents.

Comparison Between the Kinetics of Conventional Maceration and A Cyclic Pressurization Extraction Process for the Production of Lemon Liqueur Using A Numerical Model

AbstractThe purpose of this study was to compare two extraction processes for the production of lemon liqueur (limoncello)—the traditional maceration of lemon peels and a cyclically pressurized extraction process also known as rapid solid‐liquid dynamic extraction (RSLDE) that uses a Naviglio extractor. To evaluate the extraction efficiency of the two processes, dry matter obtained by the evaporation of the extracts was used to construct kinetics curves. The dry matter was directly proportional to the amount of the active principle (terpenes) extracted and consequently to the total concentration. Alcoholic extracts were analysed by gas chromatography (GC) to monitor the extraction kinetics for major components of the terpene fraction and for minor components of essential oils. Moreover, alcoholic extracts were analysed by UV spectrophotometry to identify the more abundant chemical species, while the organoleptic tests (i.e., a consumer test) performed on the final product (limoncello) provided an indication of the taste of the final product and revealed features undetectable with instrumental analytical techniques. To better understand the phenomenon considered, a numerical simulation was performed to evaluate and compare the matter flow of extractable compounds during the process.Practical ApplicationsThe mathematical model shown in this work is a scientific novelty because it is not reported in the previous literature. Indeed, the curves obtained from the kinetic analysis of the two solid‐liquid extraction procedures were interpolated to obtain a numerical model, which regulated the two extraction processes. Comparison between the kinetics of the extraction procedures showed that the rapid solid‐liquid dynamic extraction (RSLDE) process was 120 times faster than maceration and had a greater efficiency in a short time. Finally, a method proposed to follow the kinetics of the dilution of alcohol by water contained in the peels using the Karl Fisher titration method was important for establishing the alcoholic content of the beverage.

Synthesis and Preparation of Novel Magnetite Nanoparticles Containing Calix[4]arenes With Different Chelating Group Towards Uranium Anions

In this study, four new magnetite nanoparticle containing different chelating groups as ester, amide and azacrown moieties at the lower rim of calix[4]arenes were prepared by the reaction of formylated calix[4]arenes and amino propyl modified magnetite nanoparticles (APTMS-MN). All of the newly synthesized and prepared compounds were characterized by using different analytical techniques such as nuclear magnetic resonance spectroscopy (NMR), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM) and thermogravimetric analyses (TGA). Furthermore, uranium binding abilities of newly prepared magnetite nanoparticles were evaluated by using solid-liquid phase extraction process and obtained results showed that magnetite nanoparticles containing picolinamide units exhibited superior and more efficient extraction percentage for uranium ions at lower pH values.

Extractability of phenolics from spearmint treated with pulsed electric field

The effects of pulsed electric fields (PEF) on the extractability of phenolics from fresh spearmint leaves were studied. The circular tissue slices treated with PEF were subjected to a solid–liquid extraction process and the extracted phenolics were evaluated by measuring total phenolic content (TPC), antioxidant capacity (AC) and antioxidant activity (AA). The results obtained were compared with those of the extractions repeated with freezing/thawing, heat, microwave and solvent treatment.As measured from a conductivity-based tissue disintegration index, the highest disintegration (0.86±0.02) was obtained at a PEF intensity corresponding to 99 pulses of 3kV/cm with a specific energy input of 4102±239J/kg. The extraction with the PEF pre-treatment produced comparable TPC, AC and AA values with the heat and microwave pre-treatments, and a markedly higher AA value than the freezing/thawing. Furthermore, the combined effects of the PEF and other pre-treatments resulted in significant synergism in TPC and AC while showing antagonism in AA properties.

Leaves of Vallisneria Finds Source to Anti Dermatitis: Enriching Wetland Ecosystem

The renaissances of phyto-medicines lead to a resolute search of potential medicinal plants worldwide. In this perspective, predominantly, terrestrial allelochemistry has been an imperative tool to evaluate the drug potentiality of a plant. However, in aquatic ecosphere, the pharmaceutical evaluation of the aquatic macrophytes is an emerging aspect. Our study seeks to explore the curative traits of the exotic macrophyte, Vallisneria spiralis L. (Hydrocharitaceae), a perennial stoloniferous species and a key ecological community in freshwater wetland ecosystem. It is commonly used as aquarium plant and inhabits both in lentic and lotic environment of tropical and sub-tropical regions worldwide. Being rapid colonizers of aquatic ecosystem, literature study states the leaves of the macrophyte can excrete special function groups that can absorb, filter and precipitate chemical compound of water and through the auxiliary function of the microorganism. Considering these significances, we have extracted the leaf leachates of Vallisneria in 80% ethanol which had been purified by solid-liquid extraction process and further crystallized and subjected to biochemical analysis viz; phenols, flavonoids and tannins followed by antioxidant scavenging and microbial screening. Further the isolated compound was subjected to Mass and Fourier Infra-red Spectrometry. Comprehensively, all the experimental assays infer that Vallisneria leaves contain bioactive compound with mol wt. m/z 359 structured with microbial growth inhibiting functional groups which were found fungicidal against Malassezia globosa - the dandruff causing dermatitis fungus.

Mathematical Model of the Hydrotropic Microwave Assisted Extraction of Anti Malarial Agent from Andrographis Paniculata

The drugs traditionally used to treat uncomplicated malaria have become ineffective, due to the development of drug resistance. It has led to a widespread promotion of artemisinin-based combination therapy (ACT) as a strategy for effective management of Plasmodium falciparum malaria. The main drawback of the ACTs is their high cost. Hence, many phytoconstituents are currently investigated for their antimalarial activity. One of them is andrographolide of Andrographis paniculata (Burm.f.) Wall. A combination of microwave assisted-extraction and the utilization of hydrotrope as the extraction medium is already proved as a potential safe alternative for the separation of andrographolide. Mathematical models of extraction plays a crucial role in basic research of phytoconstituent separation; they are not yet available for hydrotropic-microwave assisted extraction of andrographolide. Therefore, there is a need to conduct a scientific study in this field. The mathematical model is a useful engineering tool for equipment optimization, simulation, design and control, allowing theoretical description of the process and evaluation of the kinetic constant. The aim of this work was to model the kinetics of hydrotropic-microwave assisted extraction of andrographolide. The kinetics of hydrotropic-microwave assisted extraction of andrographolide was studied for two different powers of the microwave extractor (10% and 30%). A second order kinetic model describes the solid liquid extraction process of andrographolide from Andrographis paniculata (Burm.f.) Wall.

Kinetics of the Solid-Liquid Extraction Process of Phenolic Antioxidants and Antioxidant Capacity from Hop (Humulus lupulus L.)

The influence of solvent concentration, pH, temperature, sampler solid ratio, and extraction time on the extractability of total phenolics and antioxidants from hop was investigated. The mechanism of extraction is confirmed to occur in the following steps: first, the dissolution of the phenolic compounds near the particle surface (washing), and second, the diffusion from the solid particles to the bulk of the liquid extract (slow extraction). The process is described mathematically using two concepts of the unsteady diffusion through plant material and Ponomaryov’s empirical equation. The data obtained are used to establish the kinetics and thermodynamics of the extraction process.

Kinetics and thermodynamics of the solid-liquid extraction process of total polyphenols from barley

The influence of the solvent concentration, pH, temperature, sampler solid ratio and extraction time on the extractability of total phenolic compounds from barley was investigated. The most effective solvent (30% aqueous ethanol solution with 5% HCl v/v) was used for modeling the solid-liquid extraction of total polyphenolic compounds at the solid-liquid ratio of 30 mL/g (the ratio of the solvent volume per gram of raw material). Total phenolic compounds in the barley extracts were determined spectrophotometrically using Folin-Ciocalteu method at 760 nm. The content of the phenolic compounds of extracts depends on the extraction conditions applied. The mechanism of the extraction is confirmed to occur in the following steps: first, the dissolution of the phenolic compounds near the particle surface (washing) and second, the diffusion from the solid particles to the bulk of the liquid extract (slow extraction). The process is described mathematically using two concepts of unsteady diffusion through the plant material and Ponomaryov's empirical equations. The data obtained are used to establish the kinetics and thermodynamics of the extraction process.