Flow Injection Conditions Research Articles

Electrochemical determination of thiethylperazine using semi-graphitized carbon nanofibers-MnO nanocomposite

A new voltammetric method is proposed for high sensitive thiethylperazine (THP) determination, using a glassy carbon electrode modified with semi-graphitized carbon nanofibers/MnO nanocomposite (eCNF/MnO/GC). To the best of our knowledge, this is the first electrochemical assay of THP determination, and the first use of the eCNF/MnO as the electrode modifier. The proposed method using eCNF/MnO/GC is characterized by high repeatability and sensitivity of measurements, with the linearity of THP in the range from 0.05 to 2.2 µmol L−1. The lowest detection limit achieved on the eCNF/MnO/GC electrode for 30 s of preconcentration was 6.3 nmol L−1 THP in 0.05 mol L−1 acetate buffer of pH 5.6. The proposed method was successfully applied to highly sensitive THP determination in complex matrices, such as tablets and plasma with good recovery (98–103%). The RSD value obtained for THP measurement at a concentration of 0.1 µmol L−1 was 1.3%. Amperometric measurements of THP under the flow injection conditions were also performed to indicate the possibility of its fast and accurate determination (103% and 95% for unmodified and modified electrode, respectively), with the duration of single analysis of approx. 30 s.Graphical

Glassy Carbon Electrode Modified with CB/TiO2 Layer for Sensitive Determination of Sumatriptan by Means of Voltammetry and Flow Injection Analysis

Sumatriptan is an organic chemical compound from the tryptamine group. It is used as a medicine for migraine attacks and in the treatment of cluster headaches. In this work, a new voltammetric method is proposed for highly sensitive SUM determination, using glassy carbon electrodes modified with carbon black and titanium dioxide suspension. The novelty of the presented work is the usage of the mixture of carbon black and TiO2 as glassy carbon electrode modifier for the first time for SUM determination. The mentioned sensor was characterized by great repeatability and sensitivity of measurements, which resulted in the obtention of a wide range of linearity and a low detection limit. The electrochemical properties of the CB-TiO2/GC sensor was characterized using the LSV and EIS method. The effect of different factors on the SUM peak, such as supporting electrolyte type, preconcentration time and potential, or influence of interferents, were tested using the square wave voltammetry technique. The linear voltammetric response for the analyte was obtained in the concentration range of 5 nmol L−1 to 150 μmol L−1 with a detection limit of 2.9 nmol L−1 for a preconcentration time of 150 s in the 0.1 mol L−1 phosphate buffer pH 6.0. The proposed method was successfully applied for highly sensitive sumatriptan determination in complex matrices, such as tablets, urine, and plasma, with a good recovery parameter (94–105%). The presented CB-TiO2/GC electrode is characterized by great stability, it was used for 6 weeks without significant changes in the SUM peak current. Amperometric and voltammetric measurements of SUM under the flow injection conditions were also performed to indicate the possibility of its fast and accurate determination with a time of single analysis of approx. 30 s.

A novel angiographic method to estimate arterial blood flow rates using contrast reflux: Effect of injection parameters.

Contrast reflux, which is the retrograde movement of contrast against flow direction, is commonly observed during angiography. Despite a vast body of literature on angiography, the hemodynamic factors affecting contrast reflux have not been studied. Numerous methods have been developed to extract flow from angiography, but the reliability of these methods is not yet sufficient to be of routine clinical use. To evaluate the effect of baseline blood flow rates and injection conditions on the extent of contrast reflux. To estimate arterial flow rates based on measurement of contrast reflux length. Iodinated contrast was injected into an idealized tube as well as a physiologically accurate model of the cervico-cerebral vasculature. A total of 194 high-speed angiograms were acquired under varying "blood" flow rates and injection conditions (catheter size, injection rate, and injection time). The length of contrast reflux was compared to the input variables and to dimensionless fluid dynamics parameters at the catheter-tip. Arterial blood flow rates were estimated using contrast reflux length as well as a traditional transit-time method and compared to measured flow rates. Contrast reflux lengths were significantly affected by contrast injection rate (p < 0.0001), baseline blood flow rate (p= 0.0004), and catheter size (p= 0.04), but not by contrast injection time (p= 0.4). Reflux lengths were found to be correlated to dimensionless fluid dynamics parameters by an exponential function (R2 = 0.6-0.99). When considering the entire dataset in unison, flow estimation errors with the reflux-length method (39% ± 33%) were significantly higher (p= 0.003) than the transit-time method (33% ± 36%). However, when subgrouped by catheter, the error with the reflux-length method was substantially reduced and was significantly lower (14% ± 14%, p < 0.0001) than the transit-time method. Results show correlations between contrast reflux length and baseline hemodynamic parameters that have not been reported previously. Clinically relevant blood flow rate estimation is feasible by simple measurement of reflux length. In vivo and clinical studies are required to confirm these correlations and to refine the methodology of estimating blood flow by reflux.

3D-printed manifold integrating solid contact ion-selective electrodes for multiplexed ion concentration measurements in urine

Urinalysis is a simple and non-invasive approach for the diagnosis and monitoring of various health disorders. While urinalysis is predominantly confined to clinical laboratories the non-invasive sample collection makes it applicable in wide range of settings outside of central laboratory confinements. In this respect, 3D printed devices integrating sensors for measuring multiple parameters may be one of the most viable approaches to ensure cost-effectiveness for widespread use. Here we evaluated such a system for the multiplexed determination of sodium, potassium and calcium ions in urine samples with ion-selective electrodes based on state of the art octadecylamine-functionalized multi-walled carbon nanotube (OD-MWCNT) solid contacts. The electrodes were tested in the clinically relevant concentration range, i.e. ca. 10−4 - 10−1 mol L−1 and were proven to have Nernstian responses under flow injection conditions. The applicability of the 3D printed flow manifold was investigated through the analysis of synthetic samples and two certified reference materials. The obtained results confirm the suitability of the proposed system for multiplexed ion analysis in urine.

Systematic development of a group quantification method using evaporative light scattering detector for relative quantification of ginsenosides in ginseng products

The determination for the contents of multi-components in ginseng products has come to the fore by demands of in-depth information, but the associated industries confront the high cost of securing pure standards for the continuous quality evaluation of the products. This study aimed to develop a prospective high-performance liquid chromatography-evaporative light scattering detector (HPLC-ELSD) method for relative quantification of ginsenosides in ginseng products without a considerable change from the conventional gradient analysis. We investigated the effects of mobile phase composition and elution bandwidth, which are potential variables affecting the ELSD response in the gradient analysis. Similar ELSD response curves of nine major ginsenosides were obtained under the identical flow injection conditions, and the response increased as the percentage of organic solvent increased. The nine ginsenosides were divided into three groups to confirm the effect of elution bandwidth. The ELSD response significantly decreased in case of the late eluted ginsenoside in the individual groups under the isocratic conditions. With the consideration of the two important effects, stepwise changes of the gradient condition were carried out to reach a group quantification method. The inconsistent responses of the nine ginsenosides were reconstituted to three normalized responses by the stepwise changes of the gradient condition, and this result actualized relative quantification in the individual groups. The availability was confirmed by comparing the ginsenoside contents in a base material of ginseng products determined by the direct and group quantification method. The largest difference in the determination results from the two methods was 8.26%, and the difference of total contents was only 0.91%.

Novel Coated Wires Sensors with Flow-Injection for Potentiometric Determination of Neostigmine in Bulk, Amostigmine and Human Urine

Four types of coated wires sensors (silver, copper, graphite and glassy carbon) are constructed for the determination of neostigmine (Ns) based on the ion-pair associates neostigmine silicotungstate (Ns-ST), neostigmine silicomolybdate (Ns-SM), neostigmine phosphotungstate (Ns-PT), neostigmine phosphomolybdate (Ns-PM), and ion-pairs neostigmine tetraphenylborate (Ns-TPB) in a poly (vinyl chloride) as coated film with a plasticized tricresylphthalate (TCP). The four types sensors are showed a Nernstain slopes ranged from 59-64 mV per decade in batch and 65-70 mV per decade in flow injection conditions (FIA) over a neostigmine concentration ranged from 5.0x10-7-1.0x10-2 M and within the pH range 4.0-11.0. The influences of coated film composition, pH of the Ns and foreign ions on the sensors performance were investigated and were found to be very selective, precise and excellent selectivity. The sensors were successfully applied to the potentiometric determination of neostigmine bromide in pure state, in amostigmine, and human urine. FI analysis and dissolution profile for determination neostigmine were investigated. The data were comparable with official methods for the assay and excellent percentage recovery was obtained.

Separation/Preconcentration System Based on Emulsion-Induced Breaking Procedure for Determination of Cadmium in Edible Oil Samples by Flow Injection-Flame Atomic Absorption Spectrometry

In this work, a new procedure using extraction induced by emulsion breaking (EIEB) procedure has been developed for extraction/preconcentration of cadmium in various edible oils (canola, corn, hazelnut, olive, and sunflower oil) prior to its determination by flow injection (FI) flame atomic absorption spectrometry (FAAS). Five chemical variables (surfactant type, concentration of the surfactant, concentration of the nitric acid, emulsion breaking time, and temperature) were selected as the main factors affecting extraction efficiency, and two variables (sample flow rate and sample volume) were studied for optimizing flow injection conditions. The limits of detection of 1.53 and 1.55 μg L−1 were observed for cadmium when aqueous standard and oil-based standards were added to the samples for calibration, respectively. The linear range of cadmium in aqueous standard was varied in the range of 5.9–94 μg L−1. The precision of the EIEB procedure was obtained as 4.1 % by determination of ten replicates of 2.5 μg L−1 of cadmium, and the preconcentration factor 13.8 was obtained from only 4 mL of edible oil samples. The accuracy of the procedure was performed by comparison with the reference method based on the digestion of samples in a closed-vessel microwave oven and by spiking the samples with the known amounts of the cadmium in the form of oil-based standards. There were no statistical differences between the results obtained with the EIEB procedure and the reference microwave digestion method, and the recoveries were in the range of 97–104 %.

Novel Coated Wires Sensors with Flow-Injection for Potentiometric Determination of Neostigmine in Bulk, Amostigmine and Human Urine

Four types of coated wires sensors (silver, copper, graphite and glassy carbon) are constructed for the determination of neostigmine (Ns) based on the ion-pair associates neostigmine silicotungstate (Ns-ST), neostigmine silicomolybdate (Ns-SM), neostigmine phosphotungstate (Ns-PT), neostigmine phospho molybdate (Ns-PM),and ion-pairs neostigmine tetraphenylborate (Ns-TPB) in a poly (vinyl chloride) as coated film with a plasticized tricresylphthalate (TCP). The four types sensors are showed a Nernstain slopes ranged from 59-64 mV per decade in batch and 65-70 mV per decade in flow injection conditions (FIA) over a neostigmine concentration ranged from 5.0x10-7-1.0x10-2 M and within the pH range 4.0-11.0. The influences of coated film composition, pH of the Ns and foreign ions on the sensors performance were investigated and were found to be very selective, precise and excellent selectivity. The sensors were successfully applied to the potentiometric determination of neostigmine bromide in pure state, in amostigmine, and human urine. FI analysis and dissolution profile for determination neostigmine were investigated. The data were comparable with official methods for the assay and excellent percentage recovery was obtained.

Impact of heat loss and hydrogen enrichment on the shape of confined swirling flames

Shape transitions of swirling flames are often observed in combustion chambers operated at steady flow injection conditions. These transitions may alter pollutant emissions, heat fluxes to the chamber walls or the system stability. In adiabatic combustors, transitions between V and M shapes of swirling flames are controlled by the dynamics of stretched flame elements propagating through the reactants diluted by the burnt products in the outer shear layer of the swirling combustible jet in contact with the hot outer recirculation zone. The impact of H2 concentration in the fuel and of heat loss at the chamber walls modifying the temperature in the outer recirculation zone are analyzed in this study for lean premixed CH4/H2/air flames. Laser induced OH fluorescence in different planes and particle imaging velocimetry are used to determine the probability of V to M shape transitions when the hydrogen concentration or the temperature of the combustor walls are modified. The wall temperatures are determined by laser induced phosphorescence and the temperature in the outer recirculation zone is inferred from thermocouple measurements. It is found that the probability of stabilizing a M flame increases with the H2 concentration in the combustible mixture. For the same laminar burning velocity, the flame featuring a higher extinction limit to strain rate has a higher probability to take a M shape. When combustion is initiated with cold chamber walls, the V to M flame transition probability is reduced compared to a situation with hot walls. During thermal transient and at steady state, it is shown that the temperature of the combustion chamber walls is an important factor controlling these shape transitions due to its impact on the temperature of the burnt gases in the outer recirculation zone. This study confirms that the topology of swirling flames is highly sensitive to heat transfer to the combustion chamber walls.

Modeling of Two-Phase Flow and Heat Transfer in Low-Temperature Oxygen-Fuel Spray Process

The low-temperature oxygen-fuel (LTOF) spray is a modification of high velocity oxygen fuel spray. In this process, the high-temperature gas is accelerated to supersonic speed through a Laval nozzle followed by a straight barrel. By injecting room temperature gas into the mixing chamber, the temperature of the gas can be controlled in a range of about 1000-2500 K, so that some oxygen and temperature-sensitive materials, such as titanium and copper, can avoid oxidation or decomposition during the spraying process. The purpose of this paper is to establish a 2-D mathematical model to simulate the supersonic gas dynamics and particles behavior in LTOF process. The temperature and velocity of the flow fields, and the trajectory and heating of in-flight particles are predicted for different operating parameters. The model is validated by experimental data in the literature. Effects of the mixing gas flow rates, particle sizes, and injection conditions on this process were investigated as well.

Purge flow and interface gap geometry influence on the aero-thermal performance of a rotor blade cascade

This paper is focused on the influence of the geometry of an interface seal gap on the aerodynamic and thermal performance of a rotor blade cascade. Tests are performed in a seven-blade cascade of a gas turbine high-pressure subsonic rotor at low Mach number (Ma2is=0.3). To simulate some of the effects of rotation on the seal flow exiting the gap on a linear cascade environment, a number of fins are installed inside the slot, providing the coolant flow with an injection angle in the tangential direction. Tests are carried out at variable blowing conditions and different gap widths. Moreover, the influence of a radial misalignment between stator and rotor platforms is also investigated for variable injection conditions. The 3D flow field is surveyed by traversing a 5-hole miniaturized pressure probe in a downstream plane. Secondary flows velocities, loss coefficient and vorticity distributions are presented for the most relevant test conditions. Film cooling effectiveness distributions on the platform are obtained by Thermochromic Liquid Crystals technique. Results show that engine purge flow injection conditions have to be reproduced in the wind tunnel as close as possible, in order to get the correct blade aero-thermal performance.

Effect of deglycosylation on the mediated electrocatalytic activity of recombinantly expressed Agaricus meleagris pyranose dehydrogenase wired by osmium redox polymer

The effect of deglycosylation of pyranose dehydrogenase (PDH) obtained from Agaricus meleagris (Am) and recombinantly expressed in Pichia pastoris on its electrocatalytic activity was investigated. Glycosylated (gAmPDH) and deglycosylated PDH (dgAmPDH) were immobilised on spectrographic graphite (G) simultaneously with an osmium redox polymer (Os-RP) using poly(ethylene glycol)(400) diglycidyl ether (PEGDGE) as cross-linking agent. The amperometric response to glucose, recorded at G/(Os-RP)-gAmPDH and G/(Os-RP)-dgAmPDH bioelectrodes, was optimised under flow injection conditions concerning the applied potential, enzyme loading, working pH and flow rate. The G/(Os-RP)-dgAmPDH bioelectrode is characterised by better kinetic and electroanalytical parameters compared with the G/(Os-RP)-gAmPDH bioelectrode: (i) a higher value of the maximum catalytic current density, jmax=(146.6±2.6)μAcm−2vs. jmax=(80.9±1.9)μAcm−2; (ii) a lower value of the apparent Michaelis–Menten constant, KMapp=2.4±0.1⁡mMvs. KMapp=7.5±0.3⁡mM; (iii) a higher slope of the linear domain, (43.6±1.1)μAcm−2mM−1vs. (9.74±0.16)μAcm−2mM−1. Additionally, the time dependent decay of the amperometric response to glucose shows a slightly better operational stability for the G/(Os-RP)-dgAmPDH bioelectrode than that for the G/(Os-RP)-gAmPDH. The enzyme deglycosylation induces significant changes in the order of substrate selectivity for gAmPDH and dgAmPDH.

The use of a polymer inclusion membrane for separation and preconcentration of orthophosphate in flow analysis

A highly sensitive flow analysis system has been developed for the trace determination of reactive phosphate in natural waters, which uses a polymer inclusion membrane (PIM) with Aliquat 336 as the carrier for on-line analyte separation and preconcentration. The system operates under flow injection (FI) and continuous flow (CF) conditions. Under optimal FI conditions the system is characterised by a linear concentration range between 0.5 and 1000μgL−1P, a sampling rate of 10h−1, a limit of detection of 0.5μgL−1P and RSDs of 3.2% (n=10, 100μgL−1) and 7.7% (n=10, 10μgL−1). Under CF conditions with 10min stop-flow time and sample solution flow rate of 1.32mLmin−1 the flow system offers a limit of detection of 0.04μgL−1P, a sampling rate of 5h−1 and an RSD of 3.4% (n=5, 2.0μgL−1). Interference studies revealed that anions commonly found in natural waters did not interfere when in excess of at least one order of magnitude. The flow system, operating under CF conditions, was successfully applied to the analysis of natural water samples containing concentrations of phosphate in the low μgL−1P range, using the multipoint standard addition method.

Flow electrochemical biosensors based on enzymatic porous reactor and tubular detector of silver solid amalgam

A flow amperometric enzymatic biosensor for the determination of glucose was constructed. The biosensor consists of a flow reactor based on porous silver solid amalgam (AgSA) and a flow tubular detector based on compact AgSA. The preparation of the sensor and the determination of glucose occurred in three steps. First, a self-assembled monolayer of 11-mercaptoundecanoic acid (MUA) was formed at the porous surface of the reactor. Second, enzyme glucose oxidase (GOx) was covalently immobilized at MUA-layer using N-ethyl-N′-(3-dimethylaminopropyl) carboimide and N-hydroxysuccinimide chemistry. Finally, a decrease of oxygen concentration (directly proportional to the concentration of glucose) during enzymatic reaction was amperometrically measured on the tubular detector under flow injection conditions. The following parameters of glucose determination were optimized with respect to amperometric response: composition of the mobile phase, its concentration, the potential of detection and the flow rate. The calibration curve of glucose was linear in the concentration range of 0.02–0.80mmolL−1 with detection limit of 0.01mmolL−1. The content of glucose in the sample of honey was determined as 35.5±1.0mass % (number of the repeated measurements n=7; standard deviation SD=1.2%; relative standard deviation RSD=3.2%) which corresponds well with the declared values. The tested biosensor proved good long-term stability (77% of the current response of glucose was retained after 35 days).

Plastic Membrane, Carbon Paste and Multiwalled Carbon Nanotube Composite Coated Copper Wire Sensors for Determination of Oxeladin Citrate Using Batch and Flow Injection Techniques

The fabrication and performance characteristics of three novel potentiometric sensors for the determination of oxeladin citrate are described. The proposed sensors include a PVC plastic membrane sensor, a carbon paste sensor and a multiwalled carbon nanotube (MWCNT) composite coated copper wire sensor. The sensors are based on the oxeladin-phosphotungstate ion associate as electroactive material and dibutyl phthalate as solvent mediator. The developed sensors exhibited near nernstian slopes of 58.00 ± 0.22, 55.00 ± 0.69 and 57.8 ± 0.13 mV concentration decade-1 at 25 oC, in the concentration ranges 5.96 × 10-6 - 1.00 × 10-2, 1.96 × 10-5 - 1.00 × 10-2 and 3.98 × 10-6 - 1.00 × 10-2 mol L-1 oxeladin citrate with limits of detection of 4.14 × 10-6, 8.58 × 10-6 and 2.51 × 10-6 mol L-1 oxeladin citrate for plastic membrane, carbon paste and MWCNT composite coated copper wire sensors, respectively. The proposed sensors exhibit good selectivity for oxeladin with respect to a large number of inorganic cations, sugars, amino acids and vitamins. The developed sensors were successfully applied for the potentiometric determination of oxeladin citrate in the pharmaceutical preparation (Paxeladine® capsules) in batch and flow injection conditions. The sensors were also applied for the determination of oxeladin citrate in human urine samples by using the standard addition method.

Potentiometric determination of tolterodine in batch and flow injection conditions

Two new ion-selective electrodes of the plastic membrane type for the determination of Tolterodine (Tol) were prepared. These electrodes depend on the incorporation of the ion-exchangers of the above mentioned drug with phosphotungestic acid (PTA) or Silicotungestic acid (STA) in a PVC matrix. A comparative study is made between the performance characteristics of electrodes containing ion-exchanger in batch and FIA conditions.The usable concentration range of the electrodes was found to be (1.0×10−5–1.0×10−2 and 5.0×10−5–1.0×10−2M) in batch and FIA conditions, respectively. The electrodes have nearly the same usable concentration, pH range and exhibited high selectivity toward Tol in the presence of many inorganic cations and can be used in biological fluids such as urine and plasma. The dissolution profile of the investigated drug as well as its assay in pure and pharmaceutical preparations was performed, and the results were relatively accurate and precise as indicated by the recovery values and coefficients of variation.

Cloud point extraction for the preconcentration of palladium and lead in environmental samples and determination by flow injection flame atomic absorption spectrometry

An online cloud-point extraction (CPE) coupled with flow injection method is developed for the separation and preconcentration of palladium and lead from various matrices using flame atomic absorption spectrometry (FAAS). The method employs the formation of complexes of the metallic species with dimethylglyoxime, which are subsequently entrapped in the micelles of the surfactant Triton X-114, upon increase of the solution temperature to 60°C and loaded into the flow injection system at a flow rate of 4.6 mL min(-1). The surfactant rich-phase was retained in a minicolumn packed with animal wool at pH 6 and eluted with 1.0 mol L(-1) nitric acid in methanol at a flow rate of 1.1 mL min(-1) directly into the nebulizer of the FAAS. The CPE variables and flow injection conditions affecting the analytical performance of the combined methodology was studied and optimized. Under the optimized conditions for 25 mL of preconcentrated solution, the enrichment factors were 51 and 44, and the limit of detections were 1.0 and 1.4 ng mL(-1) for palladium and lead, respectively. Finally, the developed method was applied for the determination of palladium and lead in street dust, soil, radiology waste, catalytic converter, and urban aerosol samples. Cloud-point extraction coupled with flow injection-FAAS was proposed as an effective preconcentration and separation method for Pd and Pb determination in radiology waste, road dust, soil, and urban aerosol samples. The most favorable feature of this method is its much higher selectivity, sensitivity, rapidity, good extraction efficiency, and employs the green chemistry concept, as it does not require the addition of toxic chemicals. In addition, this proposed method gives very low detection limits and good relative standard.

Flow injection catalase activity measurement based on gold nanoparticles/carbon nanotubes modified glassy carbon electrode

Amperometric flow injection method of hydrogen peroxide analysis was developed based on catalase enzyme (CAT) immobilization on a glassy carbon electrode (GC) modified with electrochemically deposited gold nanoparticles on a multiwalled carbon nanotubes/chitosan film.The resulting biosensor was applied to detect hydrogen peroxide with a linear response range 1.0×10−7–2.5×10−3M with a correlation coefficient 0.998 and response time less than 10s. The optimum conditions of film deposition such as potential applied, deposition time and pH were tested and the flow injection conditions were optimized to be: flow rate of 3ml/min, sample volume 75μl and saline phosphate buffer of pH 6.89.Catalase enzyme activity was successfully determined in liver homogenate samples of rats, raised under controlled dietary plan, using a flow injection analysis system involving the developed biosensor simultaneously with spectrophotometric detection, which is the common method of enzymatic assay.

Solid contact sensors for determination of the antihistaminic drug ketotifen fumarate

Reliable potentiometric sensing devices with unique advantages were constructed for determination of ketotifen fumarate (keto-fuma). Five sensors based on Ag, Ag/Ag 2S, Ag/AgCl, graphite and glassy carbon solid beds were constructed. These sensors were constructed based on ketotifen-tetraphenylborate (keto-TPB) as ion pairing material and dibutyl phthalate as solvent mediators. The sensors showed high sensitivity and near nernastian slope in batch and flow injection conditions (FIA). According to the results obtained, the best behavior observed for coated graphite sensor was with slope 60.10 mV/decade, linear range 7.00 × 10 −6 to 1.00 × 10 −2, and limit of detection 3.90 × 10 −7 M. Enhancement of the detection limit of the sensors was done by incorporating potassium tetraphenylborate (KTPB) and graphite in the membrane. The sensors were used for determination of keto-fuma in the pure form as well as its pharmaceutical preparations. It was performed using potentiometric titration and standard addition methods with recoveries of 99.8–101.0 and 97.8–104.0% and relative standard deviations of 0.13–0.80 and 0.61–1.42%, respectively.

SCR 촉매층 형상변화에 따른 침식특성에 관한 수치해석적 연구

The SCR catalyst in coal-fired power plant is eroded by the collision of fly ash on the catalyst surface. However the erosion of SCR catalyst by the collision of fly ash has not been fully studied, especially in terms of fluid dynamics. Hence, in the present study, we focus on the gas and solid flows inside the SCR catalyst duct and their consequent effect on the erosion characteristics. For this purpose, computational fluid dynamics is applied to investigate the two-phase flows and to evaluate the erosion rate for different flow and particle injection conditions. Also, the erosion rate and pressure drop of commonly used square shape are compared with equilateral triangle and hexagon shapes. The pressure drop of SCR catalyst is increased when SCR catalyst surface area per unit volume increases. The erosion rate of SCR catalyst is enhanced when the particle velocity, mass flow rate of particle, particle diameter and cell density of SCR catalyst are increased. From the results, the pressure drop and erosion rate at the catalyst surface can be minimized by reducing cell density of SCR catalyst to decrease particle velocity and number of particle impacts.