Extraction Flow Rate Research Articles

Chitosan–Zinc Oxide Nanoparticles Combined with Dispersive Liquid–Liquid Microextraction for the Determination of BTEX in Water Samples

In this study, chitosan–zinc oxide nanoparticles were used as an adsorbent matrix for solid-phase extraction and combined with dispersive liquid–liquid microextraction (SPE–DLLME) for determination of benzene, toluene, ethylbenzene, and xylene isomers (BTEX) in water samples. The eluent of SPE was used as the dispersive solvent of the DLLME for further purification and enrichment of the BTEX prior to gas chromatography-flame ionization detector analysis. The effect of variables, including amount of adsorbent, sample and eluent flow rate, type and volume of extraction and dispersive solvent, salt concentration, and extraction time, was investigated and they were optimized. Under the optimum conditions, good linearity for all BTEX with determination coefficients in the range of 0.9993 < r2 < 0.9997, suitable precision (1.4 % < RSD <1.9 %; where RSD refers to relative standard deviation), and low detection limits (0.5–1.1 µg L–1) were achieved. The current chitosan–zinc oxide nanoparticles SPE–DLLME procedure combines the advantages of SPE and DLLME, and was applied for determination of BTEX in water samples and acceptable recoveries were obtained.

Assessing oral bioaccessibility of trace elements in soils under worst-case scenarios by automated in-line dynamic extraction as a front end to inductively coupled plasma atomic emission spectrometry

A novel biomimetic extraction procedure that allows for the in-line handing of ≥400mg solid substrates is herein proposed for automatic ascertainment of trace element (TE) bioaccessibility in soils under worst-case conditions as per recommendations of ISO norms. A unified bioaccessibility/BARGE method (UBM)-like physiological-based extraction test is evaluated for the first time in a dynamic format for accurate assessment of in-vitro bioaccessibility of Cr, Cu, Ni, Pb and Zn in forest and residential-garden soils by on-line coupling of a hybrid flow set-up to inductively coupled plasma atomic emission spectrometry. Three biologically relevant operational extraction modes mimicking: (i) gastric juice extraction alone; (ii) saliva and gastric juice composite in unidirectional flow extraction format and (iii) saliva and gastric juice composite in a recirculation mode were thoroughly investigated. The extraction profiles of the three configurations using digestive fluids were proven to fit a first order reaction kinetic model for estimating the maximum TE bioaccessibility, that is, the actual worst-case scenario in human risk assessment protocols. A full factorial design, in which the sample amount (400–800mg), the extractant flow rate (0.5–1.5mLmin−1) and the extraction temperature (27–37°C) were selected as variables for the multivariate optimization studies in order to obtain the maximum TE extractability. Two soils of varied physicochemical properties were analysed and no significant differences were found at the 0.05 significance level between the summation of leached concentrations of TE in gastric juice plus the residual fraction and the total concentration of the overall assayed metals determined by microwave digestion. These results showed the reliability and lack of bias (trueness) of the automatic biomimetic extraction approach using digestive juices.

Analysis of <sup>99</sup>Mo Production Capacity in Uranyl Nitrate Aqueous Homogeneous Reactor using ORIGEN and MCNP

99m Tc is a very useful radioisotope in medical diagnostic procedure. 99m Tc is produced from 99 Mo decay. Currently, most of 99 Mo is produced by irradiating 235 U in the nuclear reactor. 99 Mo mostly results from the fission reaction of 235 U targets with a fission yield about 6.1%. A small additional amount is created from 98 Mo neutron activation. Actually 99 Mo is also created in the reactor fuel, but usually we do not extract it. The fuel will become spent fuel which is a highly radioactive waste. 99 Mo production system in the aqueous homogeneous reactor offers a better method, because all of the 99 Mo can be extracted from the fuel solution. Fresh reactor fuel solution consists of uranyl nitrate dissolved in water. There is no separation of target and fuel in an aqueous homogeneous reactor where target and fuel become one liquid solution, and there is no spent fuel generated from this reactor. Simulation of the extraction process is performed while reactor in operation (without reactor shutdown). With an extraction flow rate of 3.6 L/h, after 43 hours of reactor operation the production of 99 Mo is relatively constant at about 98.6 curie/hour. /hour. Received: 11 January 2014; Revised: 18 February 2014; Accepted: 28 February 2014

Online micro-solid-phase extraction based on boronate affinity monolithic column coupled with high-performance liquid chromatography for the determination of monoamine neurotransmitters in human urine

Quantification of monoamine neurotransmitters is very important in diagnosing and monitoring of patients with neurological disorders. We developed an online analytical method to selectively determine urinary monoamine neurotransmitters, which coupled the boronate affinity monolithic column micro-solid-phase extraction with high-performance liquid chromatography (HPLC). The boronate affinity monolithic column was prepared by in situ polymerization of vinylphenylboronic acid (VPBA) and N,N′-methylenebisacrylamide (MBAA) in a stainless capillary column. The prepared monolithic column showed good permeability, high extraction selectivity and capacity. The column-to-column reproducibility was satisfactory and the enrichment factors were 17–243 for four monoamine neurotransmitters. Parameters that influence the online extraction efficiency, including pH of sample solution, flow rate of extraction and desorption, extraction volume and desorption volume were investigated. Under the optimized conditions, the developed method exhibited low limit of detection (0.06–0.80μg/L), good linearity (with R2 between 0.9979 and 0.9993). The recoveries in urine samples were 81.0–105.5% for four monoamine neurotransmitters with intra- and inter-day RSDs of 2.1–8.2% and 3.7–10.6%, respectively. The online analytical method was sensitive, accurate, selective, reliable and applicable to analysis of trace monoamine neurotransmitters in human urine sample.

Enantioseparation of racemic mandelic acid by simulated moving bed chromatography using Chiralcel‐OD column

The chiral separation of the racemic mandelic acid ((R,S)‐MA) by simulated moving bed chromatography with columns packed with Chiralcel‐OD stationary phase is investigated experimentally and numerically. The transport dispersion model combined with the modified Langmuir isotherm was applied to predict the dynamic behaviour and separation performance of the SMB process. The Triangle Theory was used to obtain the complete separation region of the SMB operation. The influences of the switching time, loading, extract flow rate and column configuration on the SMB performance were also studied. The online monitoring system consisting of circular dichroism (CD) and UV detector in series was employed to measure the composition and purity of the extract and raffinate streams. Good agreement between the experimental data and model predictions proved the efficiency and reliability of SMB modelling and the Triangle theory in the design and operation of SMB chromatography. Experimental results show that purity and recovery at extract and raffinate port can reach 99% although not at the same time.

The Optimization of Effective Factors on Mercaptan Extraction by Alkaline Solution

General LPG sweetening method used in Iran's South Pars Gas Complex is Sulfrex liquid-liquid extraction and caustic regeneration processes which uses caustic as alkaline solution to extract mercaptans from propane and butane cuts and also uses LCPS 30 as catalyst to regenerate of exhaust caustic. The authors focused on the extraction section process. Also effect of the main operating variables on mercaptans extraction, including extraction temperature, concentration, flow rate, and amount of caustic as alkaline solution were studied and at the end, according to laboratory results, operational process parameters were optimized and tuned.

Determination of 4-Allyl Resorcinol and Chavibetol from Piper betle Leaves by Subcritical Water Extraction Combined with High-Performance Liquid Chromatography

A method has been developed for the determination of 4-allyl resorcinol and chavibetol from Piper betle leaves using subcritical water extraction combined with high-performance liquid chromatography. Several important parameters, such as effect of extraction temperature, solvent, particle size, flow rate and duration time of extraction were comprehensively optimized. The method showed good linearity in the range of 0.2–30 μg/mL, good correlation coefficients 0.9999 for all studies, acceptable reproducibility (RSD 0.16-5.43, n = 3), low limit of detection (0.1 μg/mL), satisfactory average recoveries of (92.22 to 111.05 %) from subcritical extraction with water with RSDs of 0.31 to 7.96 %whereas, the average recoveries from subcritical extraction with methanol–water ranged from (96.58 to 110.72) with RSDs of 0.79 to 8.09 %. The method exhibit high extraction yield in range of (1.51 to 34.64 % w/w) obtained from subcritical extraction with water whereas for subcritical extraction with methanol–water the yield obtained in range of (2.08 to 9.06 % w/w). It was found that subcritical extraction with water offered improved extraction efficiency in extraction of the target compounds compared to subcritical extraction with methanol–water.

Water stable metal-organic framework packed microcolumn for online sorptive extraction and direct analysis of naproxen and its metabolite from urine sample

The metal-organic framework MIL-101 was fabricated in a polyetheretherketone (PEEK) tube as micro-trapping device, and applied to sorptive extraction of naproxen and its metabolite in urine samples. The remarkable water stability of the MIL-101 characterizes the material as being different from other moisture sensitive metal-organic framework. It is therefore suitable for extraction of pharmaceuticals from biological fluids. The adsorption isotherms in aqueous solution showed that the adsorption of naproxen on MIL-101 is endothermic. Additionally, MIL-101 exhibited higher extraction capacity to naproxen than that of C18-bonded silica and multi-walled nanotube. A specially designed in-tube sorptive extraction (ITSE) device endows the extraction process with the characteristic of rapidness, convenience, and easy of conjunction with high performance liquid chromatography (HPLC). Finally the MIL-101 based ITSE method coupled with HPLC and fluorescence detection was applied to analysis of naproxen and 6-O-desmethylnaproxen in urine samples. Parameters that influence the online extraction procedure, including pH of the sample solution, flow rate of extraction, sample volume, desorption solvents and time were investigated. The method is proved to be highly sensitive with the linear range of 0.05–6.0μgL−1 and the limits of detection of 0.034 and 0.011μgL−1 for naproxen and 6-O-desmethylnaproxen, respectively. The recoveries in urine samples were 85.3–98.3% for naproxen and 94.0–97.3% for 6-O-desmethylnaproxen with intra- and inter-day RSDs of 2.7–5.2% and 7.1–8.1%, respectively. Urine samples could be directly subjected to analysis without any additional sample pretreatment. The proposed method was demonstrated an efficient, flexible and versatile extraction tool which is ideally suitable for online conjunction with chromatographic methods.

Flame Atomic Absorption Determination of Gold Ion in Aqueous Samples after Preconcentration Using 9‐Acridinylamine Functionalized γ‐Alumina Nanoparticles

A simple and sensitive solid phase extraction utilizing 9‐acridinylamine functionalized alumina nanoparticles was developed, and their potential use for preconcentration and subsequent determination of gold by flame atomic absorption spectrometry (FAAS) was investigated. A number of parameters, namely, type, concentration, and volume of eluent, pH of the sample solution, flow rate of extraction, and volume of the sample, were evaluated. The effect of a variety of ions on preconcentration and recovery was also investigated. Gold ions were found to be recovered quantitatively at pH 3.0, with 0.1 mol L−1 thiourea in 2 mol L−1 H2SO4 as eluent. The limit of detection (LOD), defined as five times the standard deviation of the blank, was determined to be lower than 13.0 ppb. Under optimum conditions, the accuracy and precision (RSD%) of the method were >98.0 and <1.5%, respectively. To gauge its ability in terms of application to real samples, the proposed method was successfully applied for determination of gold concentration in waste water samples and one soil standard material, and satisfactory results were obtained.

Application of Ionic Liquids in an Online Ultrasonic Assisted Extraction and Solid-Phase Trapping of Rhodiosin and Rhodionin from Rhodiola rosea for UPLC

Ionic liquid-based online ultrasonic assisted extraction (UAE) and solid-phase trapping (SPT) technique was developed to extract selectively rhodiosin and rhodionin from Rhodiola rosea for rapid determination by ultra-performance liquid chromatography. Ionic liquids with different cations and anions were investigated and 1-ethyl-3-methylimidazolium bromide solution was selected as the optimal extractant at concentration of 2.0 mol/L. Some extraction parameters such as ultrasonic power, extraction time, and extractant flow rate were optimized. The optimum separation conditions were as follows: ultrasonic power 360 W, extraction time 25 min, extractant flow rate 0.8 mL/min. The proposed approach was evaluated in comparison with the conventional maceration extraction and regular ultrasonic assisted extraction. UAE and SPT offered short extraction time, remarkable efficiency and low column pressure. Moreover, the proposed method was validated by the recovery and precision. Mean recoveries for rhodiosin and rhodionin were 98.5 and 98 %, respectively. The intra- and inter-day precision (RSD) was 1.59 and 2.98 % for rhodiosin and 1.78 and 2.05 % for rhodionin. UAE and SPT provided a new alternative for preparation of flavonoids compounds from solid sample.

Forecasting the Time Evolution of the Oil Price During Months of Negative Inflation Rate

Mass conservation equation is employed to study the time evolution of the mass of oil in a reservoir, according to the actual mass flow rate of extraction. It is also possible to define the critical mass flow rate of extraction, which is the value exhausting the reservoir in an infinite time. The evolution with time of the price of the resources extracted and sold to the market is investigated in case of no-accumulation and no-depletion of the resources, i.e., when the resources are extracted and sold to the market at the same mass flow rate. The total energy conservation equation is transformed into a money or capital per time conservation equation, which allows to study the price evolution with time, which is dependent on the following parameters. The price evolution with time of the extracted resource is dependent on the parameter PIFE, “Price-Increase Factor of Extracted resource,” which is the difference between the basic interest rate of the capital, e.g., the inflation rate, and the mass flow rate of extraction. The price evolution with time of the sold resource is dependent on the parameter PIFS, “Price-Increase Factor of Sold resource,” which is the difference between the interest rate of the capital, e.g., discount or prime rate, and the mass flow rate of extraction. The parameter CIPS, “Critical Initial Price of Sold resource,” depends on the initial price of the extracted resource, on the interest rate of nonextracted resource, and on the difference between PIFS and PIFE. The parameter CIPES, “Critical Initial Price Extreme of Sold resource,” depends on the initial price of the extracted resource, on the interest rate of nonextracted resource, and PIFS. The time evolution of the oil price during the 8 months of 2009, when the inflation rate was negative, and following the economic crisis of 2008, is investigated introducing a new category of cases, i.e., the negative inflation rate one. The paper presents and discusses the results of the forecasting for different values of the interest rate of the capital, i.e., prime and discount rate, with the conclusion that the present theory can forecast the evolution of the oil price with a reasonable confidence using the prime and the discount rates as extreme limits.

Thermodynamic analysis of pre-drying methods for pre-dried lignite-fired power plant

Lignite is considered to be a competitive energy raw material with very high security of supply viewed from a global angle. However, the utilization of raw lignite faces many thorny issues, such as a low plant thermal efficiency, a high investment in construction of the lignite-fired power plant, etc. Lignite pre-drying seems to be an attractive way to tackle these issues. We have performed a thermodynamic analysis of two pre-drying methods (both boiler flue gas drying and steam drying). Results show that both pre-drying methods can improve the plant thermal efficiency. Nevertheless, the boiler flue gas drying improves the plant thermal efficiency only in the case when the temperature of the dryer exhaust is low enough and the dryer thermal efficiency is high enough. The steam pre-drying has a higher potential in plant thermal efficiency improvement. The flow rate of steam extraction for the steam dryer is much lower than the flow rate of flue gas extraction for flue gas dryer, so we consider that the steam pre-drying is more appropriate for the revamp of the conventional lignite-fired power plant. In addition, we have calculated and analyzed main factors.

Smoke control in case of fire in a large car park: Full-scale experiments

Temperature measurements are presented as obtained in a full-scale experimental campaign on large closed car park fires. Since the main objective of the study is the investigation of the impact of a smoke and heat control (SHC) system with forced mechanical horizontal ventilation on the smoke pattern in case of a car park fire, the desired fire heat release rate (HRR) is imposed by means of well-controlled liquid pool fires. Different parameters are varied: the fire HRR; the smoke extraction flow rate; the flow patterns (through modification of inlet air opening); and the presence (or not) of a transversal beam. Not surprisingly, less smoke back-layering is observed for lower fire HRR and higher smoke extraction rate, the effect of the latter being more important. The exact position of the extraction fans is not essential, when they are not close to the fire source. The impact of the flow pattern is substantial: when smoke is trapped inside a recirculation region, the smoke and heat are not removed effectively. A transversal beam can block the smoke, even for high HRR. The primary effect of jet fans (induction type, 50N) in the study at hand is a local cooling effect, not a significant impact on the global flow pattern. For the cooling effect to be observed, the jet fans must not be in a smoke filled region.

Lab in a syringe: fully automated dispersive liquid–liquid microextraction with integrated spectrophotometric detection

A new approach for the integration of various analytical steps inside a syringe (Lab in a Syringe) is presented. Fully automated dispersive liquid-liquid microextraction with integrated spectrophotometric detection is carried out in-syringe using a very simple instrumental setup. The lighter-than-water organic droplets released in the extraction step accumulate at the head of the syringe, where two optical fibers are placed on both sides of the syringe, facing each other and enabling the in situ quantification of the extracted compounds. By this, monitoring of the progressively accumulating droplet in the head of the syringe was further possible. In this first report, the developed instrumental setup has been applied to the determination of the dye rhodamine B in water samples and soft drinks. The main parameters influencing the extraction such as the selection of the extractant and disperser solvents, extractant/disperser and organic/water phase ratios, pH of the aqueous phase, extraction flow rates, and extraction time were investigated. Under the selected conditions, rhodamine B was quantified in a working range of 0.023-2 mg L(-1) with a limit of detection of 0.007 mg L(-1). Good repeatability values of up to 3.2% (RSD) were obtained for ten consecutive extractions. The enrichment factor for a 1 mg L(-1) rhodamine B standard was 23, and up to 51 extractions were accomplished in 1 h.

Empirical study of a wind-induced natural ventilation tower under hot and humid climatic conditions

Stack ventilation and wind-induced ventilation are the two main methods for inducing natural ventilation. Stack ventilation by itself cannot create enough air flow to achieve good indoor air quality for building occupants under hot and humid climatic conditions. The low performance of stack ventilation in hot and humid climate is due to the low temperature differences between indoor and outdoor temperature of a building. On the other hand, the wind-induced ventilation method performance is independent of low temperature difference. Therefore, it has potential use to improve the indoor air quality for buildings in the hot and humid climate. This paper examines the wind-induced natural ventilation tower performs under hot and humid climate. The study reveals that the wind-induced ventilation tower has higher extraction airflow rate comparing to other wind ventilators in the market. Analysis shows the wind-induced natural ventilation tower can produce high air changes per hour (ACH) for indoor building environment in the hot and humid climate. Study results also show the wind-induced ventilation tower's extraction flow rate is 10,000m3/h at external wind velocity of 0.1m/s. With the same external wind velocity, it produces average of 57 ACH. The results of this study will be useful for designing wind-induced natural ventilation tower in hot and humid climate.

Smoke control in case of fire in a large car park: CFD simulations of full-scale configurations

Computational Fluid Dynamics (CFD) simulation results are presented of full-scale car park fire experiments with smoke and heat control (SHC) by forced mechanical horizontal ventilation. A well-controlled liquid pool fire heat release rate (HRR) is set as an input parameter. The effect of the SHC system on the smoke movement in fire conditions is examined. The following parameters are varied: fire HRR; smoke extraction flow rate; openings for incoming air (so that different flow patterns have been created); presence of beams. The impact of jet fans (induction type) is also addressed in a number of simulations. The trends observed in the full-scale experimental campaign are well captured and additional insight is provided for the interpretation of the results. The sensitivity of the CFD results to input parameters is highlighted. For a 4MW HRR fire, which is the order of magnitude for a car fire, the required ventilation velocity to limit smoke back-layering in a flat ceiling car park is around 1.1m/s. When beams are present, the average velocity must be higher, particularly for longitudinal beams. If smoke is trapped inside a recirculation region, increasing the smoke extraction rate does not help to remove the smoke.

A double-pinch criterion for regenerative Rankine cycles

A double-pinch criterion for closed feedwater heaters (FWH) of regenerative Rankine cycles is presented. The FWHs are modeled as counter-current heat exchangers. Thus, two potential pinch positions in the FWH exist: (i) at the exit of the bleed (drain) and (ii) at the onset of condensation. For a given heat duty in the FWH, feed inlet temperature and flowrate, the extraction flowrate and pressure should be chosen to achieve the same minimal approach temperature at the two potential pinch points. An analytical proof is given for a fixed pinch value for the case that the drain enters the condenser, based on weak assumptions. Additionally, the criterion is numerically demonstrated for fixed pinch value and for fixed heat exchanger area using the most common configurations: drain to condenser, drain to deaerator, and drain cascaded to next FWH. A similar criterion is developed for the case that the drain is pumped (upwards or downwards) and mixed with the feedwater. The double pinch criterion simplifies the optimization procedure and results in significant efficiency increase for fixed heat exchanger area. For numerical reasons it is advisable to use the pressure as the optimization variable and calculate the heat duty and mass flowrate.

Application of magnetic extractant for the removal of hexavalent chromium from aqueous solution in high gradient magnetic separator

In this paper, we proposed a simple, rapid and continuous method of solvent extraction for hexavalent chromium from aqueous solution in high gradient magnetic separator. We constructed the theoretical modeling of the extraction and introduced the original so-called “magnetic extractant”. The feasibility of extraction using this method was verified by the experiments. The static force analysis and force balance of the magnetic extractant in separator were studied. The extraction efficiency of magnetic extractant and the porosity in separator were related to the accumulation radius. By the mathematical derivation, the accumulation radius was determined by magnetic susceptibilities of the magnetic extractant, intensity of the background magnetic field and wire radius. The influences of the designs of ferromagnetic filler in separator, types of diluent, pH values of Cr (VI) feed solution, the extractant concentration, flow rate, and temperature of Cr (VI) solution in separator were investigated. The results showed that extraction efficiency increased with the decrease of pH value and flow rate of Cr (VI) aqueous solution, and increased with the increase of TBP concentration and temperature. Under the optimum conditions, the proposed method obtained a high extraction capacity with continuous extraction process of 6h and 1800ml Cr (VI) aqueous solution.

Sorbentless cryogenic needle trap device for the extraction of organic volatile compounds

We report on a simple, rapid, and efficient method for the extraction of volatile organic compounds (VOCs; including methanol, tetrahydrofuran, 2-hexanone and benzene) from air and solid samples. The system is based on the use of a laboratory-made syringe as the extractor. The needle of the syringe is placed in a chamber cooled by liquid nitrogen. The tip of the needle is placed in the headspace of a vial containing the sample. The headspace components then are circulated with a pump to pass the needle, and this results in freeze-trapping of the VOCs on the inner surface of the needle. The circulation of the headspace components is continued for 15 min, and the syringe is then removed and placed in a GC injector. The effects of volume of the sample vial, headspace flow rate, temperature and time of extraction and desorption were optimized. The overall time for sampling and analysis is 80%) and a good sample transfer efficiency into the GC column due to the absence of a sorbent inside the needle. No carry-over was observed after 30 s desorption at 260 °C. An external standard method was used for quantitative analysis. The relative standard deviation values are below 10% and the limits of detection range from 1.3 to 4.6 ng g−1.

SEPARATING PLASMA AND BLOOD CELLS BY DIELECTROPHORESIS IN MICROFLUIDIC CHIPS

In this paper, a dielectrophoretic (DEP) micro separator is studied for plasma-blood separation. DEP forces created by non-uniform electric fields are used as deflected forces to deplete blood cells from side walls at a given inlet flow rate ( Qin ). Then one can extract plasma through a microchannel on side wall at certain extraction flow rate ( Qp ). In this experiment, saline isotonic solution is chosen as dilute solution for whole blood. The minimum dilute ratio (whole blood: saline dilute) is found to be 1:3 for DEP to substantially deplete blood cells from side walls. Exraction of plasma from whole blood sample by DEP force is also investigated. Experimental results show blood cells do not enter side channel by DEP force at inlet flow rate Qin =0.5 μ1/ min when plasma extract flow rates is Qp ≤ 0.3 μ1/ min . By calculating pure plasma extraction volume fraction, the efficiency in current experiment can reach as high as 20% if dilute ratio 1:3 of whole blood sample is considered.