Solvent Flow Rate Research Articles

Design and optimization of a semi-continuous high pressure carbon dioxide extraction system for acetic acid

Supercritical fluid extraction with carbon dioxide was performed to extract acetic acid from real and model solutions of cow rumen fluid. Extractions were performed at varying temperature, pressure, solvent flow rate and extraction times for determining the extraction efficiency using a response surface statistical design. Within the range of variables studied, maximum acetic acid recovery of 93% was predicted at 2.0g CO2/min solvent flow rate, 2150psi (14.8MPa), 45°C, and a 5h extraction time using an initial acetic acid concentration of 92.4g/L. A volumetric mass transfer coefficient of 2.848h−1 at 35°C and 1500psi (10.3MPa) was calculated using a two-film linear driving force mass transfer model. The developed statistical model was tested for applicability on an acetic acid-spiked cow rumen fluid giving comparable results to the developed model. Results further showed that higher molecular weight volatile fatty acids such as propionic and butyric acid present in the fluid were preferentially removed before acetic acid extraction.

Imaging of whole zebra fish (Danio rerio) by desorption electrospray ionization mass spectrometry.

To demonstrate the potential use of zebra fish (Danio rerio) as a model vertebrate organism by producing two-dimensional ion images of the whole zebra fish, and being able to distinguish particular areas of interest such as the brain, spinal cord, and stomach region using a desorption electrospray ionization (DESI) ion source coupled to a linear ion trap. Imaging experiments are performed on 45 µm sagittal slices of zebra fish (Danio rerio), which are thaw-mounted onto microscope glass slides. The slides are then analyzed using a solvent of acetonitrile/dimethylformamide (50:50) (ACN/DMF), with a solvent flow rate of 1.5 μL/min; data are acquired in negative ion mode. Raw mass spectrum data files are converted into a readable file for Biomap. The images produced are then analyzed for ion distributions. We are able to create clear, distinct, chemical intensity images of the brain, spinal cord, and stomach based on lipid content as well as bile salt. The identities of these compounds were confirmed by tandem mass spectrometric (MS/MS) experiments and comparisons with literature. Imaging of whole zebra fish is possible using ambient ionization techniques such as DESI. Analyses are fast and reliable. For most of the compounds observed, the identification by MS/MS can be performed directly from the fish tissue sample.

Investigation of the suitability of aqueous sodium glycinate as a solvent for post combustion carbon dioxide capture on the basis of pilot plant studies and screening methods

Post combustion CO2 capture (PCC) through reactive absorption is a promising technology to tackle climate change. The application of new solvents enables a reduction in energy demand. This research work discusses the suitability of aqueous sodium glycinate (NaGly) as a CO2 absorption solvent.Laboratory studies show slow absorption kinetics and moderate CO2 absorption capacities of aqueous NaGly. Results from pilot plant tests at the coal-fired power plant in Dürnrohr, Austria, with 15, 25 and 40wt% NaGly are presented and discussed. Realistic industry conditions were achieved through the use of flue gas from the power plant and the well-conceived dimensions of the test facility. Low energy consumption of aqueous NaGly was mainly predicted by simulations in literature (∼3 GJ/tCO2). The measured energy consumption in the present work is much higher (>5 GJ/tCO2). This represents an increase of 40% with respect to 30wt% monoethanolamine (MEA), not combined with enhanced system extensions. The low predicted optimal solvent flow rate could not be confirmed in the present work. The optimal liquid to gas ratio is in the range of 7–8l/m3.

Extraction of phenolic compounds and anthocyanins from blueberry (Vaccinium myrtillus L.) residues using supercritical CO2 and pressurized liquids

This work explored the potential of subcritical liquids and supercritical carbon dioxide (CO2) in the recovery of extracts containing phenolic compounds, antioxidants and anthocyanins from residues of blueberry (Vaccinium myrtillus L.) processing. Supercritical CO2 and pressurized liquids are alternatives to the use of toxic organic solvents or extraction methods that apply high temperatures. Blueberry is the fruit with the highest antioxidant and polyphenol content, which is present in both peel and pulp. In the extraction with pressurized liquids (PLE), water, ethanol and acetone were used at different proportions, with temperature, pressure and solvent flow rate kept constant at 40°C, 20MPa and 10ml/min, respectively. The extracts were analyzed and the highest antioxidant activities and phenolic contents were found in the extracts obtained with pure ethanol and ethanol+water. The highest concentrations of anthocyanins were recovered with acidified water as solvent. In supercritical fluid extraction (SFE) with CO2, water, acidified water, and ethanol were used as modifiers, and the best condition for all functional components evaluated was SFE with 90% CO2, 5% water, and 5% ethanol. Sixteen anthocyanins were identified and quantified by ultra performance liquid chromatography (UPLC).

Experimental studies of regeneration heat duty for CO2 desorption from diethylenetriamine (DETA) solution in a stripper column packed with Dixon ring random packing

The regeneration heat duty (Qreg, kJ/kg CO2) is a critical parameter in the post-combustion CO2 capture process using a chemical solvent. In this study, the Qreg of CO2 desorption from CO2 rich diethylenetriamine (DETA) solutions was experimentally evaluated in a bench-scale stripper column packed with Dixon ring random packing. The experiments were conducted to evaluate Qreg over a solvent flow rate (L) range of 2.92–11.69m3/m2h, amine concentration (C) range of 1.0–4.0kmol/m3 and CO2 cyclic capacity (Δa) range of 0.21–0.79mol/mol. It was found that Qreg was greatly influenced by all the three factors. In addition, a comparison of the regeneration performances between DETA and monoethanolamine (MEA) was performed to evaluate the potential for DETA’s application in the CO2 capture process. The results obtained in this work showed that for regeneration at the same absorption capacity, the heat duty of DETA was lower than that of MEA.

Effect of Solvent Content on the Separation and the Energy Consumption of Extractive Distillation Columns

This article sets out to evaluate the effect of solvent content in the extractive section on the separation efficiency and energy consumption of extractive distillation columns. Contrary to the classical approach, the proposed approach enables a simultaneous evaluation of the effect of the major decision variables (reflux ratio, solvent flow rate, and the number of stages of the extractive section [NSE]). The procedure allows calculating the minimum solvent flow rate for the separation and the minimum specific energy consumption. The results show that the minimum specific energy consumption is obtained for the minimum reflux ratio and not for the minimum solvent flow rate. Moreover, the results show that it is not always the case that a larger NSE results in lower energy consumption. Due to its industrial importance, the dehydration of aqueous mixtures of ethanol using ethylene glycol as solvent has been chosen as a case study.

A study of new absorbent for post-combustion CO2 capture test bed

Capture and storage of post combustion CO2 from fossil fuel power plants is the best technique that can be rapidly and safely employed for the control of greenhouse gas emissions. Test bed studies with highly efficient amine CO2 solvent (KoSol−4) developed by KEPCO Research Institute was performed. For the first time in Korea, evaluation of post-combustion CO2 capture technology to capture 2t-CO2/day from a slipstream of flue gas from a commercial scale coal-fired power station was performed. Based on a chemical absorption/regeneration process with KoSol−4, we have studied the effects of lean solvent flow rate, input location and inter-cooling of absorbent, pressure and temperature of stripper for process optimization. This optimization aimed to reduce the energy for solvent regeneration. The optimum point in flow rate of lean absorbents was 700kg/h in 350Sm3/h flue gas. And the regeneration energy using new solvent was 3.02GJ/t-CO2 in 90% CO2 removal, flue gas temperature of 40°C and stripper pressure of 0.35kgf/cm2. In addition, corrosion rate of the pilot plant were measured in six points. It is the largest as 40.52mpy in the bottom of the stripper tower.

Effect of Supercritical Carbon Dioxide Flow Rate on Extraction Yield, Antioxidant Properties and Morphological Changes of Quercus infectoria Galls

The extraction condition of supercritical carbon dioxide (SC-CO2) extraction was used to extract Quercus infectoria galls, a medicinal plant which rich with bioactive compound, in order to maintain the green environment as well as the quality of the product. The study was performed to investigate the effect of extraction parameter (CO2 flow rate) on Quercus infectoria galls extract using SC-CO2 extraction. Then, the extract was analysed to determine their antioxidant activity and morphological changes of the Quercus infectoria galls before and after the extraction. Hence, three different CO2 flow rate have been investigated which were 2, 3, and 4 mL/min while pressure (P) and temperature (T) were fixed at highest density (P: 30 MPa, T: 40oC). The results obtained from this study showed the solvent flow rate of 2 mL/min give the highest percentage of extraction yield which is 0.37% compared to others. The extracts were screened for possible antioxidant activity by antioxidant activity 2,2-diphenyl-1-picryl hydrazyl (DPPH) assays. In this study, the best result obtained was at flow rate of 3 mL/min with inhibition percentage of 96.97% but it showed insignificant difference with other CO2 flow rates. The change in morphology of the galls was significant when observed using scanning electron microscope (SEM). These results indicated that SC-CO2 extraction could be an alternative method for extraction of antioxidative compound from Q.infectoria galls.

Continuous sample drop flow-based microextraction method as a microextraction technique for determination of organic compounds in water sample

Continuous sample drop flow-based microextraction (CSDF-ME) is an improved version of continuous-flow microextraction (CFME) and a novel technique developed for extraction and preconcentration of benzene, toluene, ethyl benzene, m-xylene and o-xylene (BTEXs) from aqueous samples prior to gas chromatography–flame ionization detection (GC–FID). In this technique, a small amount (a few microliters) of organic solvent is transferred to the bottom of a conical bottom test tube and a few mL of aqueous solution is moved through the organic solvent at relatively slow flow rate. The aqueous solution transforms into fine droplets while passing through the organic solvent. After extraction, the enriched analyte in the extraction solvent is determined by GC–FID. The type of extraction solvent, its volume, needle diameter, and aqueous sample flow rate were investigated. The enrichment factor was 221–269 under optimum conditions and the recovery was 89–102%. The linear ranges and limits of detection for BTEXs were 2–500 and 1.4–3.1µgL−1, respectively. The relative standard deviations for 10µgL−1 of BTEXs in water were 1.8–6.2% (n=5). The advantages of CSDF-ME are its low cost, relatively short sample preparation time, low solvent consumption, high recovery, and high enrichment factor.

Application of copolymer coated frits for solid-phase extraction of poly cyclic aromatic hydrocarbons in water samples

A conducting copolymer of pyrrole and phenol was electrochemically synthesized on steel frits as a sorbent. The applicability of the frit was assessed for the solid-phase extraction of trace amounts of polycyclic aromatic hydrocarbons (PAHs) in aqueous samples followed by HPLC–UV. The coating produced was very adherent and the scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and FTIR spectrum for the coated frit were studied. The effects of various parameters on the efficiency of the solid-phase extraction process, such as the sample loading rate, elution solvent type, salt effect, volume and flow rate of sample and elution solvent were investigated. Under the optimal conditions, the calibration curves were obtained in the range of 0.1–500ngmL−1 (r2>0.98) and the LODs (S/N=3) were obtained in the range of 0.01–0.08ngmL−1. Relative standard deviations (RSDs) for intra- and inter-day precision were 2.7–10.2% and 3.6–11.4%, respectively. The recoveries (8 and 40ngmL−1) ranged from 79% to 115%. The simplicity of experimental procedure, short sample analysis, high extraction efficiency, and the use of low-cost adsorbent show the potential of this method for routine analysis of PAHs in real samples.

Synthesis of zinc oxide nanoparticles–chitosan for extraction of methyl orange from water samples: Cuckoo optimization algorithm–artificial neural network

In this work, zinc nanoparticles–chitosan based solid phase extraction has been developed for separation and preconcentration of trace amount of methyl orange from water samples. Artificial neural network–cuckoo optimization algorithm has been employed to develop the model for simulation and optimization of this method. The pH, volume of elution solvent, mass of zinc oxide nanoparticles–chitosan, flow rate of sample and elution solvent were the input variables, while recovery of methyl orange was the output. The optimum conditions were obtained by cuckoo optimization algorithm. At the optimum conditions, the limit of detections of 0.7μgL−1was obtained for the methyl orange. The developed procedure was then applied to the separation and preconcentration of methyl orange from water samples.

Application of cuckoo optimization algorithm–artificial neural network method of zinc oxide nanoparticles–chitosan for extraction of uranium from water samples

In this study, a solid phase extraction using the new sorbent (zinc oxide nanoparticles–chitosan) has been developed for preconcentration and determination of trace amount of uranium from water samples. Hybrid modeling of cuckoo optimization algorithm–artificial neural network (COA–ANN) has been employed to develop the model for simulation and optimization of this method. The 1-(2-pyridylazo)-2-naphthol (PAN) was used as chelating agent. The pH, volume of elution solvent, mass of zinc oxide nanoparticles–chitosan, concentration of PAN, flow rate of sample and elution solvent were the input variables, while recovery of uranium was the output. At the optimum conditions, the limit of detections and enrichment factor were 0.5μgL−1 and 125, respectively for the uranium. The developed procedure was then applied to the extraction and determination of uranium from water samples.

Multiwalled‐carbon‐nanotubes‐based matrix solid‐phase dispersion extraction coupled with high‐performance liquid chromatography for the determination of honokiol and magnolol in Magnoliae Cortex

In this paper, multiwalled-carbon-nanotube-based matrix solid-phase dispersion coupled to HPLC with diode array detection was used to extract and determine honokiol and magnolol from Magnoliae Cortex. The extraction efficiency of the multiwalled-carbon-nanotube-based matrix solid-phase dispersion was studied and optimized as a function of the amount of dispersing sorbent, volume of elution solvent, and flow rate of elution solvent, with the aid of response surface methodology. An amount of 0.06 g of carboxyl-modified multiwalled carbon nanotubes and 1.5 mL of methanol at a flow rate of 1.1 mL/min were selected. The method obtained good linearity (r(2) > 0.9992) and precision (RSD < 4.7%) for honokiol and magnolol, with limits of detection of 0.045 and 0.087 μg/mL, respectively. The recoveries obtained from analyzing in triplicate spiked samples were determined to be from 90.23 to 101.10% and the RSDs from 3.5 to 4.8%. The proposed method that required less samples and reagents was simpler and faster than Soxhlet and maceration extraction methods. The optimized method was applied for analyzing five real samples collected from different cultivated areas.

Free Standing Hierarchically-Structured Electrodes for Energy Storage Devices

Fabrication of novel three-dimensional material architectures is essential for successful development of energy storage devices that allow high rate operation along with sufficient energy capacity. We will present our work on development of nanofiber-based hierarchically structured materials for applications in electric double layer capacitors and lithium-based batteries using a simple and scalable electrospinning methodology. As a first step, a comprehensive study on fabrication and structure-control of porous carbon nanofibers exhibiting specific surface areas of >1500 m2/g and multi-levels of pore sizes in the range of micro (<2 nm), meso (<50 nm) and macropores (>50 nm) was conducted. In particular, blends of polyacrylontritrle (PAN) and a sacrificial polymer in dimethyl formamide (DMF) were electrospun into non-woven nanofiber mats with diameters in the range of 200-300 nm. Fast evaporation of solvent (~200 nl/s) and high elongational flow rate (~105 s-1) during electrospinning allowed us to prevent phase separation and develop a co-continuous morphology of PAN and the sacrificial polymer in the nanofibers. Electrospun nanofiber mats were subjected to stabilization and carbonization processes to obtain porous carbon nanofibers (CNFs) as PAN converted to carbon and the sacrificial polymer decomposed out to create intra-fiber pores (Figure 1). These materials exhibit specific surface area of up to 1600 m2/g without any activation process. We exhibit the tunability of the pore sizes within CNFs by varying material composition. These materials were tested as free-standing electrodes (without any binder) for electric double-layer supercapacitors. Our study shows that they exhibit a large specific capacitance (210 F/g and 80 F/cm3), possibly due to the presence of a large fraction of meso-pores (2-4 nm) and macropores (>50 nm) compared to state-of-the-art activated carbons (pores <2 nm), which leads to an increase in the accessible carbon surface, thereby improving specific capacitance. These electrodes exhibit near-ideal rectangular CV curve even at a high scan rate of 2V/s (Figure 2). This again is attributed to the relatively larger pore size in these materials compared to most activated carbons, which allows faster ion transport and charge/discharge. Note that activated carbons often deviate from ideal behavior even at a scan rate of 100 mV/s scan rate.These materials retain 75% performance at a large current density of 20 A g1indicating excellent power handling capability. Preliminary data on use of these hierarchically structured materials for high energy density lithium-based batteries – Lithium-sulfur and Lithium-air, will be presented.

A new combination approach of CI jet and QESD to formulate pH-susceptible amorphous solid dispersions

A new combination approach of quasi-emulsion solvent diffusion (QESD) and confined impinging jet (CIJ) technologies was utilized to formulate pH-susceptible amorphous solid dispersions (ASDs) of a poorly soluble investigational compound (BI906) of Boehringer Ingelheim Pharmaceuticals. The objective of this study was to formulate small-size pH-susceptible ASDs of BI906 to enhance its dissolution and solubility. A design of experiment approach was utilized to study the influence of critical parameters: antisolvent-to-solvent ratio, stabilizer concentration, polymer-to-drug ratio and flow rate of solvent. The critical quality attributes of the pH-susceptible solid dispersions (SDs) were crystallinity, particle size, drug loading and dissolution. The particle size of SDs was dependent on the antisolvent-to-solvent ratio, polymer-to-drug ratio and solvent flow rate. An increase in the solvent flow rate and antisolvent-to-solvent ratio resulted in smaller particle size of SDs. It was observed that the drug crystallinity and drug release were dependent on the polymer-to-drug ratio. The formulations containing a polymer-to-drug ratio of 6:1 were amorphous and showed superior pH dependent in vitro drug release performance. This study demonstrates that this new combination approach is feasible to formulate small-size pH-susceptible ASDs and it can be applied to other poorly soluble drugs to enhance in vitro dissolution and solubility.

Preparation and Optimization of N-Acetylcysteine Nanosuspension through Nanoprecipitation: An Artificial Neural Networks Study

Nanosuspensions, as a promising strategy to improve the solubility and bioavailability of poorly water soluble drugs, have been widely investigated in recent years. However, no comprehensive work so far has detailed the effect of independent processing/formulation parameters on the quality of the prepared nanosuspension. In the present study, the relations between solvent flow rate, stirring rate of antisolvent and surfactant concentration (i.e., inputs) on size, and polydispersity index (PDI) (i.e., outputs) of an N-acetylcysteine nanosuspension were investigated using artificial neural networks (ANNs). The response surfaces, generated as 3D graphs after ANNs modeling, demonstrated that all the three factors have a reverse effect on size and PDI. The dominant factor appeared to be the concentration of surfactant. Overall, it was found that the optimum formulation (i.e., minimum size and PDI value) is obtained at high values of surfactant concentration, solvent flow rate, and stirring rate (i.e., >0.9 mg/ml and 120 ml/h and 500 rpm, respectively).

Supercritical Fluid Extraction of Swietenia mahagoni Seed: Antioxidant and Antimicrobial Activities

Swietenia mahagoni seeds have been used as folk medicine for a treatment of hypertension, malaria and diabetes. This research was conducted to obtain extracts from the Swietenia mahagoni using supercritical fluid extraction (SFE) with pure CO2 solvent, in order to evaluate the high- pressure method in terms of process yield and biological activity. The various conditions namely flow rate of CO2 were set up at 2, 3, and 4 ml/min; at constant pressures (P) and temperature (T). The sample extracts obtained by SFE with CO2 flow rate of 4 ml/min showed the highest percentage yield (19.67%) compared to the others. The antioxidant potential of the extracts was evaluated by the DPPH method and Folin- Ciocalteu method. The solvent flow rate of 2 ml/min gave the lowest percentage of yield, but good results in antioxidant activity and total phenolic content. The antimicrobial activity of the extracts against Gram-positive (Bacillus subtilis, Staphylococcus aureus) and Gram-negative (Escherichia coli) was evaluated based on the inhibition zone using disc diffusion assay. These results ensured that Swietenia mahagoni seed extract had inhibitory effects on the growth of Bacillus subtilis, Staphylococcus aureus and Escherichia coli at concentration of 100 mg/ml.

Gas–liquid membrane contactor for ethylene/ethane separation by aqueous silver nitrate solution

Separation of light olefin from paraffin having the same carbon number is one of the most energy intensive separations in petrochemical processes, which uses very long distillation columns with very high number of trays. This is attributed to the very small differences in the relative volatilities. The purpose of this work is to study the absorption performance of a home-made PVDF hollow fiber membrane fabricated using thermally induced phase separation method. Separation of ethylene from an ethylene–ethane gas mixture, using a hollow fiber membrane based absorption–desorption system with aqueous silver nitrate as absorption solvent, and to enhance separation process with a purchased polypropylene hollow fiber membrane module used for stripping purposes. Experiments on the absorption of ethylene from ethylene–ethane mixture, into silver nitrate solutions were performed. The effects of initial ethylene concentration in feed gas, silver nitrate concentration in the inlet solvent, liquid and gas flow rates were investigated. Results reveal that ethylene/ethane separation factor increases with silver nitrate concentration and liquid flow rates. A two dimensional mathematical model was developed for this purpose. Model predictions were validated with experimental data. Model predictions were in good agreement with experimental results.

SIMULTANEOUS DETERMINATION OF FIVE MAJOR CONSTITUENTS IN THE EFFECTIVE FRACTIONS OF HUANGQICHIFENG MEDICINAL BROTH, BY UPLC-MS/MS

An UPLC method coupled with tandem quadrupole mass spectrometry (MS/MS) was established for the simultaneous quantitative analysis of five major constituents in the effective fractions of Huangqichifeng Medicinal Broth (EFHQCF), namely paeoniflorin (PA), prim-O-glucosylcimifugin (PR), ononin (ON), calycosin (CA), and formononetin (FO). The analytes were analyzed on an ACQUITY BEH C18 VanGuard precolumn and an ACQUITY UPLC BEH C18 column using gradient elution. The mobile phase A was ammonium acetate (10 mM) in water containing 0.2% acetic acid (v/v); mobile phase B was ammonium acetate (10 mM) in methanol containing 0.2% acetic acid (v/v). The solvent flow rate was 0.25 mL/min. The retention times of PA, PR, ON, CA, and FO were 9.9 min, 18.2 min, 26.6 min, 30.6 min, and 35.7 min, respectively. The investigated compounds were detected by MS/MS using a negative ion multiple reaction monitoring mode for the simultaneous quantitative detection. The limits of detection ranged from 0.001 ug/mL to 0.043 µg/mL, and the limits of quantitation varied from 0.003 µg/mL to 0.148 µg/mL. Moreover, the linearities (r 2 > 0.999) and recoveries (from 96.34% to 104.75%) were acceptable. Therefore, the present study suggested that this UPLC-MS/MS method should be reliable and could be used to control the quality of EFHQCF.

Determination of Supercritical Carbon Dioxide Extraction Parameters for Quercus infectoria Galls and the Effects on Extraction Yield and Antioxidant Activity

Currently, finding alternative ways of extracting medicinal plant gain more interest from the researchers. Quercus infectoria, a medicinal plant, is rich with bioactive compound being extracted using supercritical carbon dioxide (SC-CO2) extraction which helps to maintain the quality of the product as well as green environment. CO2 is widely used as solvent due to moderate critical conditions, nontoxic and easily removed from the products. This work was performed to determine the optimum extraction parameters of SC-CO2 extraction and their effects on the total phenolic content and antioxidant activity of Q.infectoria extract. Hence, two different parameters have been investigated which were extraction time and CO2 flow rate (2, 3, 4 ml/min) while pressure (P) and temperature (T) were fixed at highest density (P = 30 MPa, T = 40oC). The results obtained from this study show that the solvent flow rate of 2 ml/min gives the highest percentage of yield (0.3652%) and the complete extraction of the sample was achieved at 80 minutes. Better quality of the extract was shown at 2 ml/min as resulted in high amount of phenolic compound in the extract presented as gallic acid equivalent (GAE) (2.04×102 mg GAE/g sample). The extracts were screened for possible antioxidant activity by 2,2-diphenyl-1-picryl hydrazyl (DPPH) free radical scavenging assays. In this study, the best result obtained for antioxidant activity was at flow rate of 3 ml/min with inhibition percentage of 96.97%.