Height Equivalent To A Theoretical Plate Research Articles

Comparison of the adsorption dynamics of leucyl-leucine enantiomers and glycyl-glycine on Chirobiotic R and Chirobiotic V columns

The adsorption dynamics of the LL- and DD-enantiomers of Leu-Leu and Gly-Gly on a Chirobiotic V column packed with a CSP bearing glycopeptide antibiotic vancomycin was studied and compared with the adsorption dynamics of the same dipeptides on a Chirobiotic R column packed with a CSP with bonded antibiotic ristocetin A. The column efficiencies were essentially different. The heights equivalent to a theoretical plate (HETP) on Chirobiotic R were 2-4 times larger than on Chirobiotic V, and the shape of van Deemter plots, strongly convex-upwards on the former column, demonstrated minor (Leu-Leu) or lacking (Gly-Gly) convexity on the latter column. This difference is attributed to differences in the binding kinetics of dipeptides to the antibiotics, fast for vancomycin and slow for ristocetin A. Since the kinetic C term of the van Deemter equation cannot explain such a large discrepancy in HETP for the same analyte on two columns, and since the A and B terms for the Chirobiotic R column were essentially larger than for the Chirobiotic V column, it is suggested that binding kinetics influences eddy and longitudinal diffusion processes associated with those terms. It is also hypothesized that unusually high values of van Deemter B coefficients occasionally found in chiral chromatography are not experimental artifacts but the manifestation of coupling the effects of slow adsorption kinetics and longitudinal diffusion.

Mass transfer in heap leaching of weathered crust elution deposited rare earth ore with Al2(SO4)3 solution

In order to increase efficiency and avoid NH4+–N pollution in the leaching process of weathered crust elution-deposited rare earth ores, the mass transfer in heap leaching with Al2(SO4)3 solution was simulated with column elution and experimentally optimized. The results indicate that the leaching yield is also up to 99 % for leaching with aluminum sulfate instead of ammonium sulfate. The optimal flow rate is 60 mL/h, the height equivalent to a theoretical plate (HETP) is 1.29 mm correspondingly. The peak value position of RE3+ is 60 mL/h, Fe3+ is 100 mL/h, however, Al3+ is 150 mL/h, and the heap leaching process has kinetic separation effect.

A column screening study: Validation of a RP-LC method for determination of teriflunomide with pentafluorophenyl stationary phase

The research focuses on column screening in order to develop a novel validation method to separate Teriflunomide significantly using comparative and equivalent column selection studies. This gives stationary phase efficiency relative to height equivalent to a theoretical plate (HETP) (>16000) and symmetry factor (<2.0%). After extensive column chemistry and technique development, the advanced Pentafluorophenyl (PFP) column separates halogenated drugs better. Teriflunomide is fluorinated drug, hence PFP is optimal for analysis. For statistical data comparison, the same chromatographic method was developed and transferred to another YMC Pack Pro C18 column that gives almost the same results as PFP column in terms of carbon load, pore size, and surface area. The refined and validated method yielded equivalent results with two stationary phases using a single analysis procedure. Column screening, technique creation, transfer, and validation with comparison studies with correlation coefficients over 0.999 are unique. The statistical data from both columns meets ICH requirements. The sensitive, reliable, robust, and reproducible approach is easy to apply in regular laboratory analysis. Data analysis showed that the validation study with PFP is better (LoD - 0.0015 ppm) for column ageing due to smaller injection volume and amount loaded in the column, shorter run time, and cheaper analysis cost. This research helps with column selection and method transfer with diverse column specifications. With less than 2.0% of RSD, the column screening analytical method validation is linear, precise, accurate, rugged, and efficient.

Superwetting metal-organic frameworks optimized interface for high-performance hydrogen-water isotopic exchange for tritiated water treatment

A metal-organic frameworks (MOFs) modified interface with superhydrophilic and superaerophobic properties was successfully prepared via the solution process for tritiated nuclear wastewater (HTO) treatment. The superwetting performance of the packing surface which facilitated the liquid phase catalytic exchange was discussed in detail for the hydrogen-water isotope exchange reaction. Superhydrophilic property originated from the microporous hydrophilic nature of MOFs resulting in a rapid spreading and phase-transfer process of the tritiated water droplet, and superaerophobic property accompanied by superhydrophilic water thin film favored the effective exchange between gaseous reactants. Computational fluid dynamic (CFD) simulations revealed the influence of contact angle and liquid flow rate on the gas-liquid two-phase interface and catalytic performance. High performance with the lowest height equivalent to a theoretical plate (HETP) and long-term stability is achieved for this superwetting packing, which holds promise for the detritiation of nuclear wastewater with higher performance and stability.

Numerical simulation of binary component separation with perforated-on sheets of the structured packing

In this research work, we proposed a modern structured packing (SP) with perforated sheets with a specific surface area of 860[Formula: see text][Formula: see text]/[Formula: see text], which was determined using numerical techniques. This work aims to evaluate the major characteristics of PACK-860 for instance, height equivalent to a theoretical plate (HETP), dry pressure drop (DPD) and wet pressure drop (WPD). Additionally, the flow construction was defined for specific packing via computational simulation. To evaluate the value of HETP, DPD and WPD, the three-dimensional (3D) computational fluid dynamics (CFD) simulation with the Eulerian–Eulerian (EE) multi-phase method applied in this paper. According to the findings of this research, the performance of the mass transfer (MT), WPD and DPD was enhanced with the perforated-on sheets of packing. Based on the observation, numerical results are consistent well with the theoretical data which reveals the consistency of CFD tools for modeling methods to separation applications.

Evaluation of separation performance for eggshell-based reversed-phase HPLC columns by controlling particle size and application in quantitative therapeutic drug monitoring.

Eggshell-based reversed-phase packing materials were applied to an analytical column for high-performance liquid chromatography. Commercially available eggshell powder was classified by a cyclone system to obtain three types of particles with different diameters (arithmetic mean ± standard deviation: 4.3 ± 3.8, 5.6 ± 3.3, and 9.5 ± 5.5 μm). Sedimentation separation removed tiny particles from each sample, resulting in particles with arithmetic means of 6.6 ± 5.5, 7.3 ± 4.5, and 10.2 ± 5.0 μm, respectively. The unclassified particles and three particle types treated with sedimentation separation were subsequently packed into analytical columns (150 mm × 4.6 mm I.D.), and their separation efficiencies were evaluated by comparing their height equivalent to a theoretical plate (HETP). The column without sedimentation separation exhibited the highest HETP, whereas the columns with sedimentation separation showed better separation efficiency and lower back pressure. The column with the best separation efficiency was applied for the separation of 10 alkylbenzenes and 5 steroids, and all peaks were observed with complete separation (peak resolution: RS > 1.5). Finally, the column was used for quantitative analysis of voriconazole, an azole antifungal agent, and imatinib, a first-generation molecularly targeted drug for cancer treatment, in spiked whole blood. Excellent accuracy (99.1-102.8%) and precision (0.6-1.9%) were observed for the spiked drugs and long-term stability (>3000 column volumes of mobile phase flow) indicated good applicability of the developed eggshell-based column as an analytical column for routine analyses of therapeutic drugs in blood.

Fabrication process development and basic evaluation of eggshell-based column packing material for reversed-phase preparative separation

Purification of basic drugs in reversed-phase mode is often difficult, mainly due to adsorption of positively charged compounds to the silica gel-based stationary phase. Since this adsorption can be suppressed under alkaline condition, columns with alkali-resistance are required. In addition, compounds with acid-sensitive structures are sometimes degraded during separation on silica gel-based columns which exhibit acidity due to their surface structure. We prepared an alkali-resistant reversed-phase packing material, Eggshell-PMAcO based on eggshells modified with an amphiphilic copolymer, poly(maleic acid-alt-1-octadecene) (PMAcO). The height equivalent to a theoretical plate (HETP) of the Eggshell-PMAcO column was improved by surface treatment with ammonium acetate buffer (900 mM, pH = 3.7), which is an inexpensive reagent, and the retention behavior for hydrophobic compounds was compared to a typical ODS column based on silica gel, resulting in sufficient selectivity of the eggshell-based column for hydrophobic compounds, as indicated by the ratio of retention factors of pentylbenzene and butylbenzene (Eggshell-PMAcO column: 1.55, ODS column: 1.65). Column temperature-dependent retention behavior of naphthalene was investigated in the temperature range from 25 °C to 45 °C, followed by the calculation of thermodynamic parameters. There was little difference in the standard molar enthalpy (Eggshell-PMAcO: −19.6 kJ/mol, ODS: −21.7 kJ/mol). The absolute value of the standard free Gibbs energy for the Eggshell-PMAcO column was much smaller than that of the ODS column (Eggshell-PMAcO: −0.284 kJ/mol, ODS: −13.0 kJ/mol), indicating that the Eggshell-PMAcO column had a weaker retention strength for naphthalene than the ODS column mainly due to the large difference in the standard molar entropy (Eggshell-PMAcO: −64.9 J/mol K, ODS column: −29.2 J/mol K). The retention capacities for imipramine under neutral (water/methanol) and alkaline (0.1% triethylamine water/methanol) conditions were 0.2 mg and 5 mg, respectively, based on injection mass-dependent HETP, retention factor and symmetry factor. Finally, the prepared column was applied to the purification of a building block for nucleic acid drugs. This study demonstrated that reversed-phase columns, which can be fabricated from eggshells and an amphiphilic copolymer in an inexpensive and eco-friendly way, have the ability to purify basic compounds and acid-sensitive compounds.

Superhydrophilic metal-organic frameworks film modified surface for tritium removal from tritiated heavy water

Tritium extraction from heavy water moderators with catalytic exchange reactions had hydrogen explosion, fire risk, and complicated system design, which restricted the industrial scale usage. Herein, we reported a safer and simpler tritiated heavy water distillation process with metal-organic frameworks (MOFs) modified surface. MOFs with microstructure, microporous pores, and hydrophilic nature showed superhydrophilic properties, which was a benefit to better interface contact properties between water drop, vapor, and packing. High separation efficiency was achieved with height equivalent to a theoretical plate (HETP) of 1.53 cm under optimized operation conditions. Pilot-scale two-column tritiated heavy water distillation system was simulated and optimized based on experimental results with a high separation factor and recovery rate of tritium. This work demonstrates the first attempt at MOFs engineered surface for tritiated heavy water treatment, advancing a new concept in the design of tritiated heavy water distillation with intrinsic safety for industrial applications.

Separation Efficiency Measurements with Non‐Volatile Components and Elevated Feed Viscosities

AbstractCommon mass transfer models for multistage distillation show significant deviations between calculated and experimental height equivalent to a theoretical plate (HETP) values for viscous feed mixtures. This is due to a limited transferability of the available data which were mainly obtained from experiments with inviscid mixtures. Separation efficiency measurements at elevated viscosities can be conducted with polymer‐enhanced test mixtures and require an alternative plant setup. This contribution addresses the development of an improved plant setup suitable to conduct such separation efficiency measurements. General design considerations, simulative feasibility studies, and plant characterization experiments as well as separation efficiency measurements will be discussed.

Extruded monoliths for gas separation processes: Height equivalent to a theoretical plate and pressure drop correlations

AbstractExtruded monoliths are generally adopted in the chemical industry for the advantage of reduced pressure drops at high throughput, but a systematic procedure to evaluate their performance is not readily available. Key performance indicators for a monolith are the height equivalent to a theoretical plate (HETP) and the pressure drop of its channels. This contribution presents for the first time a systematic approach to the analysis of several extruded monoliths of industrial relevance. A procedure to derive the HETP correlation for an arbitrary extruded monolith is presented, and pressure drop correlations from literature are reviewed. The HETP correlations have been validated against three dimensional (3D) numerical simulations. A reduced‐order model is derived from the HETP and is shown to capture the overall dynamics of the 3D simulations with high accuracy without adjustable parameters. Finally, a comparison between the extruded monoliths and packed beds is reported and includes pressure drops.

Is Golay’s Famous Equation for HETP Still Relevant in Capillary Gas Chromatography? Part 1: A Common View of HETP

In this installment of “GC Connections,” we take a close look at Golay’s famous equation that most people view as relating to height equivalent to a theoretical plate (HETP) to the carrier gas flow rate or average linear gas velocity in a capillary column. We explore the original works of Golay and Keulemans. We also look closely at the original equation, the assumptions involved with its development, and the assumptions (both good and bad) that have been applied to HETP over the years. In part two, we will explore the consequences and relevance of this theory today, with temperature programming, very long (and very short) columns, high pressure drops, and vacuum outlet detectors.

Effect of the polydispersity on the dispersion of polymers through silicas having different morphologies (fully porous and core-shell particles and monoliths)

The effect of the polydispersity of polystyrenes on the dispersion through silicas having different morphologies (fully porous, core-shell particles and monoliths) was investigated. The heights equivalent to a theoretical plate (HETP) of those columns were measured for a small molecule (toluene) and a series of polystyrenes of different sizes in non-adsorbing conditions. The different contributions to the total HETP including polydispersity were determined experimentally. The longitudinal diffusion and the mass transfer resistance term were obtained from peak parking experiments. The eddy dispersion was obtained from models and experiments. The effect of polydispersity on the HETP values (Hpoly) can thus be calculated from the total HETP by substraction of the other contributions. The results were compared to the Knox model which surestimates the Hpoly values for porous and core-shell particles which is usually explained by an overestimation of the polydispersity index (PDI) given by the manufacturer. The PDI of two polymers (P02, Mw= 690 g.mol−1 and P03, Mw=1380 g.mol−1) was verified by liquid chromatography by separating each fraction of the polymer on the silica columns by using adsorbing conditions which are obtained with a mixture of heptane and THF. The PDI obtained are comparable to the PDI given by the manufacturer meaning that the assumptions made by Knox are not entirely valid. A direct method is proposed in this paper in order to determine Hpoly. In this method the excess of spreading as compared with a polymer with only one size corresponding to the average size is studied assuming the polymer size distribution is gaussian. The Hpoly values obtained by the direct method are comparable to the experimental values.

Characterization of a New Structured Packing by Computational Fluid Dynamics

AbstractThe novel wire gauze structured packing PACK‐1300Y with high specific surface area was characterized by computational fluid dynamics. The main features of PACK‐1300Y were investigated including the dry and wet pressure drop as well as the height equivalent to a theoretical plate (HETP). Moreover, the flow structure of this packing was described via numerical simulations. To evaluate the amount of HETP and dry and wet pressure drop, 3D computational fluid dynamic modeling with respect to the Eulerian‐Eulerian multiphase approach was applied. The average relative errors were determined between the findings achieved from computational fluid dynamic simulation and experimental findings for mass transfer efficiency and wet and dry pressure drop, respectively.

Computational Fluid Dynamics Characterization of High‐Capacity Structured Packing

AbstractThe novel wire gauze structured packing, PACK‐860, was characterized by means of numerical methods. The main features of PACK‐860 such as height equivalent to a theoretical plate (HETP) and dry/wet pressure drop were evaluated. The flow structure in this packing was described by numerical simulation. To estimate the amount of HETP and dry/wet pressure drop, three‐dimensional computational fluid dynamics (3D CFD) modeling with the Eulerian‐Eulerian multiphase approach was applied. The average relative errors between the results obtained from CFD simulation and experimental findings for mass transfer efficiency and wet and dry pressure drop were assessed. Numerical observations were found to agree well with the empirical results, proving the reliability of CFD simulations for modeling separation processes.

HETP measurement using industrial-scale batch distillation

The height equivalent to a theoretical plate (HETP), representing the mass transfer efficiency, allows designers to determine the packed bed height. In this study, a novel methodology was proposed to evaluate the HETP using an existing industrial-scale batch distillation when designing the height of an industrial-scale continuous distillation column. Specifically, an existing batch distillation used for the reclamation of dichlorodifluoromethane CCl2F2 (R-12 or Freon-12) from a waste refrigerant mixture was employed to determine the HETP value. Prior to the simulation, a literature survey was investigated to determine the suitable property package for simulation. The simulation results were then compared with the experimental data to determine whether REFerence fluid PROPerties can be used as a suitable package for this study. Several batch distillation runs were carried out using industrial structured packing and random packing, which are candidates for the design and optimization of a continuous distillation column in this specific separation. The batch distillation was then rigorously simulated for a comparison with the experimental data, enabling us to calculate the HETP value. The simulated results agreed well with experimental data, demonstrating that the proposed methodology is effective and easy to apply.

Development of Open-Tubular-Type Micro Gas Chromatography Column with Bump Structures.

Gas chromatography (GC) is the chemical analysis technique most widely used to separate and identify gas components, and it has been extensively applied in various gas analysis fields such as non-invasive medical diagnoses, indoor air quality monitoring, and outdoor environmental monitoring. Micro-electro-mechanical systems (MEMS)-based GC columns are essential for miniaturizing an integrated gas analysis system (Micro GC system). This study reports an open-tubular-type micro GC (μ-GC) column with internal bump structures (bump structure μ-GC column) that substantially increase the interaction between the gas mixture and a stationary phase. The developed bump structure μ-GC column, which was fabricated on a 2 cm × 2 cm μ-GC chip and coated with a non-polar stationary phase, is 1.5 m-long, 150 μm-wide, and 400 μm-deep. It has an internal microfluidic channel in which the bumps, which are 150 μm diameter half-circles, are alternatingly disposed to face each other on the surface of the microchannel. The fabricated bump structure μ-GC column yielded a height-equivalent-to-a-theoretical-plate (HETP) of 0.009 cm (11,110 plates/m) at an optimal carrier gas velocity of 17 cm/s. The mechanically robust bump structure μ-GC column proposed in this study achieved higher separation efficiency than a commercially available GC column and a typical μ-GC column with internal post structures classified as a semi-packed-type column. The experimental results demonstrate that the developed bump structure μ-GC column can separate a gas mixture completely, with excellent separation resolution for formaldehyde, benzene, toluene, ethylbenzene, and xylene mixture, under programmed operating temperatures.

Pressure drop behavior and mass transfer properties of a high specific area random type packing in a narrow packed column

In this paper, the comprehensive experimental examinations are conducted to investigate the mass transfer properties of Dixon ring packing. The main aspect of this study is to investigate the characteristics of Dixon ring packing using a narrow packed column. Firstly, the mass transfer properties of the packing were investigated using distillation experiments at total reflux. Afterwards, the pervasive experiments were conducted to plot the generalized pressure drop correlation chart. Finally, the variation of height equivalent to a theoretical plate (HETP) was determined at total reflux operations for various vapour loading factors. Our findings showed that increasing the vapour loading factor up to 0.62 Pa0.5 would eventually decrease the HETP. It was also shown that the further increase in the vapour loading factor results in a sudden increase in the HETP value. According to our findings, the selection of the optimum vapor loading factor would enhance the value of HETP up to more than 57 %.

RpeakChrom: Novel R package for the automated characterization and optimization of column efficiency in high-performance liquid chromatography analysis.

Characterization of chromatographic columns using the traditional van Deemter method is limited by the necessity of calculating extra-column variance, issue particularly relevant when modeling asymmetrical peaks eluted from monolithic columns. A novel R package that implements Parabolic Variance Modified Gaussian approach for accurate peak modeling, van Deemter equation and two alternatives approaches, based on van Deemter, has been developed to calculate the height equivalent to a theoretical plate (HETP). To assess package capabilities conventional packed reverse-phase and monolithic HPLC columns were characterized. Peaks eluted from the monolithic column showed a high value of factor asymmetry due, in part, to the contribution of extra-column factors. Such deviation can be circumvented by the two alternatives approaches implemented in the R-package. Furthermore, increased values of eddy diffusion and mass transfer kinetics terms in HETP were observed for the packed column, while accuracy was below 9% in all cases. These results showed the usefulness of the R-package for both modeling chromatographic peaks and assessing column efficiency. The RpeakChrom package could become a helpful tool for testing new stationary phases during column development and to evaluate column during its lifetime. This R tool is freely available from CRAN (https://CRAN.R-project.org/package=RpeakChrom).

Recovery of mono-ethylene glycol by distillation and the impact of dissolved salts evaluated through simulation of field data

This study was conducted to investigate the operation of a packed distillation column and analyse its performance during the separation of mono-ethylene glycol from water. The column was designed and constructed by the Curtin Corrosion Engineering Industry Centre (CCEIC) and operated in collaboration with a reputable oil company to generate experimental field data. A secondary investigation was then performed into the impacts of dissolved salts within the rich MEG feed upon the purity of the lean MEG product. It was observed through application of the FUG shortcut distillation design equations that six equilibrium stages were required to attain the experimental separations reported under continuous operation of the column. It was further determined that the packing utilised within the column had a Height Equivalent to a Theoretical Plate (HETP) of approximately 0.34 m when no dissolved salts were present corresponding to an estimated packing height of approximately 1.7 m.The impact of dissolved salts upon the performance of the column was evident through lower lean MEG purities observed during experimental operation of the column in comparison to salt free trials. The reduction in column performance was reaffirmed by Aspen HYSYS and Aspen Plus simulations of the field data, where salt trials resulted in lean MEG purities noticeably less than corresponding salt free experimental trials and simulated predictions. Overall, it was observed that the presence of dissolved salts during operation led to a reduction in MEG mass fraction of the final lean MEG product by on average 7.2%. The impact of dissolved salts on lean MEG purity was successfully predicted by Aspen Plus simulation with an average accuracy of 1.61% through the inclusion of monovalent salt cations using the ELECNRTL equation of state with modified binary parameters. The reduction in lean MEG purity was attributed to boiling point elevation of the MEG-Water solution and the impact of the dissolved salts on the systems vapour liquid equilibrium.

Impact of straight, unconnected, radially-oriented, and tapered mesopores on column efficiency: A theoretical investigation

Superficially porous particles (SPPs) can be prepared from a pseudomorphic transformation (PMT) which produces straight, unconnected, and radially-oriented mesopores (ROMs). ROMs can be either both ends open in fully porous particles (FPPs) or one-end-closed in SPPs. The impact of ROMs on the longitudinal diffusion (B/u), solid–liquid mass transfer resistance (Csu), and on the eddy dispersion (A(u)) height equivalent to a theoretical plate (HETP) of 3D randomly packed columns was investigated based on theoretical viewpoints. Torquato's theory of effective diffusion in packed beds (B term), Giddings’ coupling theory of eddy dispersion (A term), and Giddings’ generalized nonequilibrium theory (Cs term) are applied to make predictions. First, it is found that the A term is nearly independent on the internal structure of the particle. Secondly, in the absence of flow, infinitely narrow and both ends open (no constriction effect) ROMs induce an internal hindrance factor of 23 regarding diffusion along the axial direction. Experimental data reveal that one-end-closed and 80Å wide ROMs in SPPs lead to a measurable internal hindrance factor of 27 regarding diffusion in the porous shell. Thirdly, above the optimum speed, the Cs coefficient is dependent on the geometry (cylinders, cones, etc.) of the ROMs: when ROMs are conical in SPPs, Cs is expected to decrease by 80% with respect to cylindrical ROMs. From an application perspective, PMT-SPPs prepared with narrow ROMs are well suited for the analysis of small molecules at or below optimum speed (lowest B term) while PMT-SPPs made of wide and conical ROMs are ideal for the analysis of large molecules above optimum speed (smallest Cs term).