Note: This page contains sample records for the topic packed distillation column from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: November 12, 2013.
1

Nonlinear model predictive control of a packed distillation column  

Microsoft Academic Search

A rigorous dynamic model based on fundamental chemical engineering principles was formulated for a packed distillation column separating a mixture of cyclohexane and n-heptane. This model was simplified to a form suitable for use in on-line model predictive control calculations. A packed distillation column was operated at several operating conditions to estimate two unknown model parameters in the rigorous and

Ashutosh A. Patwardhan; Thomas F. Edgar

1993-01-01

2

Scale-up of reactive distillation columns with catalytic packings  

Microsoft Academic Search

The scale-up of reactive distillation columns with catalytic packings requires the knowledge of reaction kinetics, phase equilibrium and packing characteristics. Therefore, pressure drop, liquid holdup and separation efficiency have been determined for the catalytic packing MULTIPAK®. A new hydrodynamic model that describes the countercurrent gas-liquid flow for the whole loading range and considers the influence of the column diameter has

Achim Hoffmann; Christoph Noeres; Andrzej Górak

2004-01-01

3

Distillation Columns with Structured Packings in the Next Decade  

Microsoft Academic Search

The analysis of the history of structured packings allows the conclusion that the inno- vation cycle will become faster. Based on the separation power as an alternative way to represent the performance characteristics an estimate of the next level of what might be the ultimative separa- tion power is given. Regarding the column internals like distributors only slight improvements are

Lothar Spiegel; Werner Meier

2003-01-01

4

Modeling and control of a packed distillation column using artificial neural networks  

Microsoft Academic Search

Artificial neural networks, because they are nets of basis functions, can provide good empirical models of complex nonlinear processes that are useful for many purposes including process control. The modelling of a packed distillation column described here provides an interesting example of complex modeling because the column exhibits a change in the sign of the gain under various operating conditions.

J. C. Macmurray; D. M. Himmelblau

1995-01-01

5

Flooding characteristics of packed columns with high efficiency. [SDC protruded distillation, Podbielniak bronze Helipak, Norton pall ring, Goodloe mesh  

Microsoft Academic Search

Flooding characteristics of four high efficiency column packings, including Scientific Development Co. (SDC) protruded stainless distillation packing, Norton stainless pall rings, Podbielniak bronze Helipak, and Goodloe stainless wire mesh packing were determined experimentally. Two Plexiglas columns (6.35 cm ID and 15.2 cm ID) filled with these packings were operated with countercurrent air and water streams. Pressure drop data were recorded

W. M. Choi; R. C. Michel; J. L. P. Varlet

1976-01-01

6

Counter-current operation of structured catalytically packed distillation columns: pressure drop, holdup and mixing  

Microsoft Academic Search

Structured packed columns, in which the catalyst particles are enclosed within wire gauze envelopes (“sandwiches”) are promising reactor configurations for reactive distillation and hydroconversions. By allowing preferential channels for the gas and liquid phases, counter-current operation is achieved even for millimeter sized catalyst particles without the problem of flooding. This paper reports the results of a comprehensive experimental study of

J. Ellenberger; R. Krishna

1999-01-01

7

Distillation columns containing structured packings: A comprehensive model for their performance. 2: Mass-transfer model  

Microsoft Academic Search

This is the second part of a two-part paper dealing with the fluid mechanics and mass transfer in structured packings for distillation column service. The first part elucidated pressure drop, flooding, and liquid holdup. The second part covers the generation of effective interfacial area and provides a general correlation for predicting the mass-transfer efficiency as a function of surface type,

J. Antonio Rocha; Jose L. Bravo; James R. Fair

1996-01-01

8

Distillation columns containing structured packings: A comprehensive model for their performance. 1. Hydraulic models  

Microsoft Academic Search

A mechanistically-based model has been developed to aid the analysis and design of distillation columns containing structured packings of the corrugated plate type. The model encompasses the important, and related, parameters of liquid holdup, pressure drop, flooding, and mass-transfer efficiency. Since it deals with the countercurrent contacting of liquid with gas or vapor, the model may also be applied to

J. Antonio Rocha; Jose L. Bravo; James R. Fair

1993-01-01

9

Simulating heat and mass transfer in regular distillation column packing  

Microsoft Academic Search

Plane-parallel packing of Mellapack 250X type (without perforations) is considered. Equation systems are given that describe\\u000a the motion and heat and mass transfer in a layer of liquid and vapor. Calculations have been performed on nonstationary heat\\u000a and mass transfer in cells of several types by the use of the STAR-CD software and the subroutines Star-Design and Pro-amm.\\u000a Graphs are

I. A. Arkharov; E. S. Navasardyan

2006-01-01

10

CFD modeling of mass-transfer processes in randomly packed distillation columns  

Microsoft Academic Search

The volume-averaged equations for velocity and concentration fields have been used to simulate the hydrodynamics and mass-transfer processes in randomly packed distillation columns. This approach is regarded as a second-generation computational fluid dynamics (CFD) based model, and a significant departure from the traditional one-dimensional, first-generation models. The model has ability to capture radial and axial variations in flow and mass-transfer

F. H. Yin; C. G. Sun; A. Afacan; K. Nandakumar; K. T. Chuang

2000-01-01

11

CFD modeling of mass-transfer processes in randomly packed distillation columns  

SciTech Connect

The volume-averaged equations for velocity and concentration fields have been used to simulate the hydrodynamics and mass-transfer processes in randomly packed distillation columns. This approach is regarded as a second-generation computational fluid dynamics (CFD) based model, and a significant departure from the traditional one-dimensional, first-generation models. The model has ability to capture radial and axial variations in flow and mass-transfer conditions. The spatial variation of void fraction has been included to take into account the effect of bed structures. The simulation results have been compared with experimental data reported by Fractionation Research, Inc. (FRI) which performed their tests in a 1.22-m-diameter column with a packed bed height of 3.66 m. For validation, the authors have used data obtained with 15.9-, 25.4-, and 50.8-mm metal Pall rings at various operating conditions. Good agreement between CFD predictions and published experimental data has been obtained. This is regarded as an encouraging sign that CFD models can play a useful role in studying separation processes.

Yin, F.H.; Sun, C.G.; Afacan, A.; Nandakumar, K.; Chuang, K.T.

2000-05-01

12

Nonequilibrium cell model for packed distillation columns -- The influence of maldistribution  

SciTech Connect

In this paper the authors present a nonequilibrium model for studying the effects of flow maldistribution in packed columns. The model consists of a set of mass and energy balances along with a set of mass- and energy-transfer correlations. Maldistribution is treated by means of the zone/stage approach, as developed by Zuiderweg et al. Simulations show that, for binary mixtures, packing HETPs are a function of the height of the packing. It should be noted that in some cases the behavior of HETPs is not intuitive, even for binary mixtures. For ternary mixtures, cases were found in which differences in maldistribution patterns can result in substantial differences in column behavior; in some cases completely different column products can be obtained.

Higler, A.; Krishna, R.; Taylor, R.

1999-10-01

13

A novel structured catalyst packing for catalytic distillation of ETBE  

Microsoft Academic Search

Catalytic distillation can offer significant reduction of capital costs in G\\/L\\/S processes that are equilibrium limited. As an alternative to existing catalytic distillation packings, containing bales or pockets of catalyst stacked in (a section of) the distillation column, a novel structured catalyst packing is proposed. The novel packing consists of a common structured distillation packing, on which a binderless film

O. L. Oudshoorn; M. Janissen; W. E. J. van Kooten; J. C. Jansen; H. van Bekkum; C. M. van den Bleek; H. P. A. Calis

1999-01-01

14

Simplified distillation column controls  

SciTech Connect

A simple, energy efficient method of controlling single or double distillation columns for the production of ethyl alcohol is described. The control system is based on a material balance scheme centered around a thermostat actuated control valve to regulate reflux rate and product purity. Column bottom's levels are automatically regulated by vented suction lines on the pump inlets. Methods of minimizing control input variations are used including column insulation, stillage-to-beer heat exchanger, and a steam pressure regulator.

Badger, P.; Pile, R.; Lightsey, G.

1984-01-01

15

THE DISTILLATION OF URANIUM HEXAFLUORIDE AND BROMINE PENTAFLUORIDE IN A 0.5- INCH-DIAMETER PACKED COLUMN  

Microsoft Academic Search

The efficiency of a 0.5 in. dia packed column with 1\\/16 in. nickel ; helices for the separation of the binary system UFâ-- BrFâ was ; investigated. Several distlllations were performed wlth the system ; methylcyclohexane and nheptane for purposes of callbration. For both systems, ; pressure-drop measurements at various flow rates were determined and the flooding ; rates were

Ivins

1962-01-01

16

Flooding Characteristics of Packed Columns with High Efficiency.  

National Technical Information Service (NTIS)

Flooding characteristics of four high efficiency column packings, including Scientific Development Co. (SDC) protruded stainless distillation packing, Norton stainless pall rings, Podbielniak bronze Helipak, and Goodloe stainless wire mesh packing were de...

W. M. Choi R. C. Michel J. L. P. Varlet

1976-01-01

17

A new and applicable method to calculate mass and heat transfer coefficients and efficiency of industrial distillation columns containing structured packings  

Microsoft Academic Search

Most of the methods developed for efficiency estimation of distillation columns were based on the empirical mass transfer and hydraulic relations correlated to laboratory data. Therefore, these methods cannot estimate efficiency of industrial columns with sufficient accuracy. In this paper, a new and applicable method was developed for calculation of efficiency (and mass and heat transfer coefficients) of distillation columns

Hamidreza Sadeghifar; Ali Akbar Safe Kordi

2011-01-01

18

3 HPLC columns and packings  

Microsoft Academic Search

In this chapter on HPLC columns, we are discussing both the surface chemistry of a packing as well as column design and performance. In the section that covers column chemistry, we cover modern options of base materials as well as the commonly used approaches towards the surface chemistry of a packing. Specific subsections are dedicated to the selectivity of reversed-phase

Uwe D. Neue; Bonnie A. Alden; Edward R. Grover; Eric S. Grumbach; Pamela C. Iraneta; Alberto Méndez

2007-01-01

19

Tritium Isotope Separation Using Adsorption-Distillation Column  

SciTech Connect

In order to miniaturize the height of a distillation tower for the detritiation of waste water from fusion reactors, two experiments were conducted: (1) liquid frontal chromatography of tritium water eluting through an adsorption column and (2) water distillation using a column packed with adsorbent particles. The height of the distillation tower depends on the height equivalent to a theoretical plate, HETP, and the equilibrium isotope separation factor, {alpha}{sub H-T}{sup equi}. The adsorption action improved not only HETP but also {alpha}{sub H-T}{sup equi}. Since the adsorption-distillation method proposed here can shorten the tower height with keeping advantages of the distillation, it may bring an excellent way for miniaturizing the distillation tower to detritiate a large amount of waste water from fusion reactors.

Fukada, Satoshi [Kyushu University (Japan)

2005-07-15

20

Optimal design of thermally coupled distillation columns  

Microsoft Academic Search

This paper considers the optimal design of thermally coupled distillation columns and dividing wall columns using detailed column models and mathematical optimization. The column model used is capable of describing both conventional and thermally coupled columns, which allows comparisons of different structural alternatives to be made. Possible savings in both operating and capital costs of up to 30% are illustrated

G. Duennebier; Constantinos C. Pantelides

1999-01-01

21

Correlate the flooding of packed columns a new way  

Microsoft Academic Search

Packed-column pressure-drop and flooding-point prediction has received new attention recently. These publications, like most earlier ones, focus on gas-flow-induced pressure drop, and flooding due to liquid entrainment in the packing. A few years ago, some problems occurred when packing was applied in high-pressure distillation service, such as ethylene and propylene superfractionators. Apparently, the maximum liquid-through-put capacity was lower than predicted

1994-01-01

22

Numerically optimized performance of diabatic distillation columns  

Microsoft Academic Search

Recently, the concept of equal thermodynamic distance (ETD) has been proposed to minimize entropy production in a distillation process using a diabatic column. ETD gives the optimal temperature profile to first-order in N?1, where N is the number of trays. ETD, however, does not generally give the true minimum for distillation columns with few trays. We therefore apply a fully

Markus Schaller; Karl Heinz Hoffmann; Gino Siragusa; Peter Salamon; Bjarne Andresen

2001-01-01

23

Avoid problems during distillation column startups  

Microsoft Academic Search

The startup of a distillation column is the end product of the design process. Indeed, startup is the culmination of the theory and practice of designing the column to meet the process objectives. The author will direct most of this discussion towards column revamps due to their inherent complexity; however, the points apply equally to new columns, as well. The

Sloley

1996-01-01

24

Simplified Design of Batch Reactive Distillation Columns  

Microsoft Academic Search

This work proposes a simplified methodology for the analysis and design of reactive batch distillation columns based on the McCabe-Thiele method for reactive continuous columns and on the concept of a reactive difference point. To extend the application of the concept of a reactive difference point for reactive batch distillation columns, expressions for the McCabe-Thiele operating line and for the

Maria E. Huerta-Garrido; Vicente Rico-Ramirez; Salvador Hernandez-Castro

2004-01-01

25

Study on a Continuous Heat Integrated Distillation Column  

Microsoft Academic Search

A novel continuous heat integrated distillation column called a concentric column has been studied using computer simulation. It is shown that a concentric column is a novel implementation of a thermodynamically reversible distillation column and has a lower energy loss than an ordinary distillation column. Our studies show that a concentric column has reduced column height, since the stripping section

Thomas Glenchur; Rakesh Govind

1987-01-01

26

Optimal design of complex azeotropic distillation columns  

Microsoft Academic Search

Geometric methods are valuable tools for process synthesis and design since they provide designers with intuition and quantitative results. The calculation and graphical representation of azeotropes, residue curves and distillation boundaries provide a wealth of knowledge about the entire composition space. This paper shows how these tools can be used for optimal design of complex azeotropic distillation columns. Two examples

Stanislaw K Wasylkiewicz; Leo C Kobylka; Francisco J. L Castillo

2000-01-01

27

Simulation and control of reactive distillation column  

Microsoft Academic Search

The paper discusses about the application of PID controller and fuzzy controller in reactive distillation column. A generic mathematical model of reactive distillation has been taken for simulation. The PID and fuzzy controllers are designed for the process and then the overall process is controlled by using conventional (PID) and intelligent (fuzzy) controllers separately. Conventional PID controller is used to

Ujjwal Kapoor; Asha Rani; Vijander Singh; J. R. P Gupta

2011-01-01

28

Gas flow distribution in packed columns  

Microsoft Academic Search

The distribution of gas flow over the cross section of packed columns depends on the manner of gas flow feeding, on packing type, packing arrangement, and internal devices in the apparatus body. Various types of gas inlet devices are studied in order to estimate their ability for creation of uniform velocity profiles. The gas flow uniformity is characterized by the

Rumen Darakchiev; Chavdar Dodev

2002-01-01

29

Method for packed column separations and purifications  

SciTech Connect

The invention encompasses a method of packing and unpacking a column chamber. A mixture of a fluid and a matrix material are introduced through a column chamber inlet so that the matrix material is packed within a column chamber to form a packed column. The column chamber having the column chamber inlet or first port for receiving the mixture further has an outlet port and an actuator port. The outlet port is partially closed for capturing the matrix material and permitting the fluid to flow therepast by rotating relative one to the other of a rod placed in the actuator port. Further rotation relative one to the other of the rod and the column chamber opens the outlet and permits the matrix material and the fluid to flow therethrough thereby unpacking the matrix material from the column chamber.

Holman, David A. (Richland, WA); Bruckner-Lea, Cynthia J. (Richland, WA); Brockman, Fred J. (Kennewick, WA); Chandler, Darrell P. (Richland, WA)

2006-08-15

30

Thermal Integration of a Distillation Column Through Side-Exchangers  

Microsoft Academic Search

Thermal integration of a distillation column with the background process through side exchangers (side reboilers\\/condensers) is important for designing an energy-efficient distillation column. Thermal integration of a distillation column through side exchangers also improves the exergetic efficiency of the column. Invariant rectifying and stripping (IRS) curves are employed for thermodynamic analysis of a distillation column. Different configurations for side-exchanger integration

S. Bandyopadhyay

2007-01-01

31

Effects of water on steam rectification in a packed column  

Microsoft Academic Search

The effects of water on steam rectification, i.e., multi-stage saturated steam distillation, were investigated in a packed column. N-octane–p-xylene and 1,3,5-trimethylbenzene–1,2,4-trimethylbenzene were used as test systems. Both binary systems are nearly ideal systems and insoluble in water, thus the effects of water in steam rectification can be clearly and definitely revealed. Such unpolar organic liquid is named as “oil”. The

Qingli Qian; Hongxing Wang; Peng BAI; Guoqing Yuan

2011-01-01

32

A Versatile, Automatic Chromatographic Column Packing Device  

ERIC Educational Resources Information Center

|Describes an inexpensive apparatus for packing liquid and gas chromatographic columns of high efficiency. Consists of stainless steel support struts, an Automat Getriebmotor, and an associated three-pulley system capable of 10, 30, and 300 rpm. (MLH)|

Barry, Eugene F.; And Others

1977-01-01

33

Lattice approaches to packed column simulations  

Microsoft Academic Search

This work presents a review of the findings into the ability of a digitally based particle packing algorithm, called DigiPac, to predict bed structure in a variety of packed columns, for a range of generic pellet shapes frequently used in the chemical and process engineering industries. Resulting macroscopic properties are compared with experimental data derived from both invasive and non-destructive

Richard Caulkin; Xiaodong Jia; Mike Fairweather; Richard A. Williams

2008-01-01

34

Heat Integration in Batch Distillation Column  

NASA Astrophysics Data System (ADS)

A new heat integrated batch distillation column has been configured in this paper. Here the column and reboiler are connected in an annular arrangement and a compressor is positioned between them to maintain the pressure difference. The heat integration is between the rectifying batch column and one concentric reboiler. Ethanol-Water binary system is chosen as an example for the design and analysis of this heat integrated batch distillation column (HIBDiC). In this work, a sensitivity test for selecting the optimal value of the total number of trays and reboiler duty and a thermodynamic feasibility test for its design acceptability has been accomplished. The principal objective of this study is to investigate the influence of compression ratio (CR) on the energy consumption of distillation and to find out the optimal value of CR. Also a comparative analysis of HIBiDC on energy consumption in steady state as well as in dynamic state has been carried out on the basis of its conventional model. The proposed scheme is capable to save the energy up to 50.52% compared to its conventional one by selecting the CR of 1.4 as an optimal value.

Maiti, Debadrita; Jana, Amiya K.; Samanta, Amar Nath

2010-10-01

35

Control of a heat pump assisted distillation column  

Microsoft Academic Search

Based on the basic concepts and techniques involved for automatic control of continuous distillation columns for binary systems, a scheme is proposed for the control of distillation column for the ethanol–water system. Using the established norms for the control of mechanical vapor compression heat pumps, a control scheme is proposed for the heat pump assisted distillation column for the ethanol–water

Ishwar Chandra; Sukumar Devotta

1998-01-01

36

Final Report, Distillation Column Flooding Predictor  

SciTech Connect

The Flooding Predictor is an advanced process control strategy comprising a patented pattern-recognition methodology that identifies pre-flood patterns discovered to precede flooding events in distillation columns. The grantee holds a U.S. patent on the modeling system. The technology was validated at the Separations Research Program, The University of Texas at Austin under a grant from the U. S. Department of Energy, Inventions & Innovation Program. Distillation tower flooding occurs at abnormally high vapor and/or liquid rates. The loss in tray efficiencies is attributed to unusual behavior of liquid inventories inside the column leading to conditions of flooding of the space in between trays with liquid. Depending on the severity of the flood condition, consequences range from off spec products to equipment damage and tower shutdown. This non-intrusive pattern recognition methodology, processes signal data obtained from existing column instrumentation. Once the pattern is identified empirically, it is modeled and coded into the plant's distributed control system. The control system is programmed to briefly "unload" the tower each time the pattern appears. The unloading takes the form of a momentary reduction in column severity, e.g., decrease bottom temperature, reflux or tower throughput. Unloading the tower briefly at the pre-flood state causes long-term column operation to become significantly more stable - allowing an increase in throughput and/or product purity. The technology provides a wide range of value between optimization and flooding. When a distillation column is not running at capacity, it should be run in such a way ("pushed") that optimal product purity is achieved. Additional benefits include low implementation and maintenance costs, and a high level of console operator acceptance. The previous commercial applications experienced 98% uptime over a four-year period. Further, the technology is unique in its ability to distinguish between different flooding mechanisms within the same tower, e.g., liquid and jet flooding.

George E. Dzyacky

2003-05-31

37

Improve distillation-column control design  

SciTech Connect

Steady-state process models have long been used to assist the engineer in designing control strategies for distillation columns. Yet, a large number of industrial columns still operate in manual or with ineffectual controls. So, better control design techniques using steady-state models certainly are needed. In this article, the authors introduced an improved method that already has proven itself on 33 industrial columns. This article deals exclusively with the design of single-point composition controls. The vast majority of columns have one-sided composition specifications. With such specifications, a single-point composition control scheme can keep both top and bottom product compositions at or below limits for a wide range of disturbances. The predominance of one-sided specifications means that the main incentive for dual-point control schemes is achieving energy savings. In most cases, though, the energy savings are small and do not justify the added difficulty of implementing and maintaining dual-point control. Additionally, dual-point schemes often have significantly longer recoveries from upsets due to interactions between the control loops. The design procedure can be best thought of as a general approach rather than a single detailed procedure that covers all cases. The produce must be adapted to each problem because there are many different types of distillation and almost every industrial problem has some unique requirement.

Fruehauf, P.S.; Mahoney, D.P.

1994-03-01

38

Studies on dynamics and control of distillation columns.  

National Technical Information Service (NTIS)

Distillation is an important unit operation in which a given feed is separated into two or more products of different compositions. The separation requires input of relatively large amounts of energy. Improved composition control of distillation columns m...

E. W. Jacobsen

1991-01-01

39

Derivation of Working Equations for Dynamic Simulation of Cryogenic Distillation Column Incorporating Vapor Holdups on Stages within Column.  

National Technical Information Service (NTIS)

If a distillation column has a packed section whose inner diameter is considerably small, a small number of the total theoretical stages, and a condenser whose volume is very large, the vapor holdup in the condenser could be significant in dynamic simulat...

M. Kinoshita

1983-01-01

40

The Distillate Bottoms Control of Distillation Columns: Modeling, Tuning and Robustness Issues  

Microsoft Academic Search

The DB (distillate-bottoms) structure was proposed by Luyben and coworkers on the basis of operators experience for the dual composition control of a distillation column. The DB structure, in regards to a relatively low volatibility and high purity column, has been indicated by the results to possess a better disturbance rejection capability over the conventional DV (distillate-vapor boilup) structure. The

DER-MING CHANG; CHENG-CHING Yu

41

PRESSURE DROPS IN PACKED BUBBLE COLUMNS  

Microsoft Academic Search

Pressure drops were measured for air-water system in a cocurrent, upflow bubble column containing each of four types of packing: Raschig rings, Intalox saddle, open-end screen cylinder and solid cylinder. The ranges of variables studied vary from 0 to0.09m\\/s for gas flow rate, 0 to 0.094 m\\/s for liquid flow rate and 0.475 to 0.976 for bed porosity. The experimental

Q. M. ZHANG; B. H. CHEN

1995-01-01

42

Microbiological desulfurization of column-packed coal  

Microsoft Academic Search

A microbial inoculum was selected to be later employed in the desulfurization of column-packed coal. A percolating liquid at pH 1.5 was used, and the total iron was monitored throughout the process. The results, after 42 days of percolation indicate that elimination of pyritic sulfur achieved a level of 46%, with relatively small changes in the immediate analysis of the

A. Morán; A. Aller; J. Cara; O. Martínez; J. P. Encinas; E. Gómez

1997-01-01

43

Continuous and Batch Distillation in an Oldershaw Tray Column  

ERIC Educational Resources Information Center

|The importance of distillation in the separation field prompts the inclusion of distillation experiments in the chemical engineering curricula. This work describes the performance of an Oldershaw column in the rectification of a cyclohexane/n-heptane mixture. Total reflux distillation, continuous rectification under partial reflux, and batch…

Silva, Carlos M.; Vaz, Raquel V.; Santiago, Ana S.; Lito, Patricia F.

2011-01-01

44

Optimal synthesis of complex distillation columns using rigorous models  

Microsoft Academic Search

The synthesis of complex distillation columns has remained a major challenge since the pioneering work by Sargent and Gaminibanadara that was reported in 1976. In this paper we first provide a review of recent work for the optimal design of distillation of individual columns using tray-by-tray models. We examine the impact of different representations and models, NLP, MINLP and GDP,

Ignacio E. Grossmann; Pío A. Aguirre; Mariana Barttfeld

2005-01-01

45

Internally Heat-Integrated Distillation Columns: A Review  

Microsoft Academic Search

The heat-integrated distillation column to be addressed in this paper is a special distillation column that involves internal heat integration between the whole rectifying and the whole stripping sections. An overview of the research on this process is presented in this work. It covers from the thermodynamic development and evaluations to the practical design and operation investigations for the process.

M. Nakaiwa; K. Huang; A. Endo; T. Ohmori; T. Akiya; T. Takamatsu

2003-01-01

46

Improved operational policies for batch extractive distillation columns  

Microsoft Academic Search

The authors and others have previously developed insights into batch distillation when using a middle vessel batch column. They extended earlier work on reachable product regions for continuous columns to this and other batch column configurations. The work also examined the use of a continuously flowing extractive agent to facilitate the separation of azeotropic mixtures. A middle vessel batch column

Boyd T. Safrit; Arthur W. Westerberg

1997-01-01

47

Future perspectives of using hollow fibers as structured packings in light hydrocarbon distillation  

SciTech Connect

Olefin and paraffin are the largest chemical commodities. Furthermore, they are major building blocks for the petrochemical industry. Each year, petroleum refining, consumes 4,500 TBtu/yr in separation energy, making it one of the most energy-intensive industries in the United States). Just considering liquefied petroleum gas (ethane/propane/butane) and olefins (ethylene and propylene) alone, the distillation energy consumption is about 400 TBtu/yr in the US. Since petroleum distillation is a mature technology, incremental improvements in column/tray design will only provide a few percent improvements in the performance. However, each percent saving in net energy use amounts to savings of 10 TBtu/yr and reduces CO{sub 2} emissions by 0.2 MTon/yr. In practice, distillation columns require 100 to 200 trays to achieve the desired separation. The height of a transfer unit (HTU) of conventional packings is typical in the range of 36-60 inch. Since 2006, we had explored using several non-selective membranes as the structured packings to replace the conventional packing materials used in propane and propylene distillation. We obtained the lowest HTU of < 8 inch for the hollow fiber column, which was >5 times shorter than that of the conventional packing materials. In 2008, we also investigated this type of packing materials in iso-/n-butane distillation. Because of a slightly larger relative volatility of iso-/n-butane than that of propane/propylene, a wider and a more stable operational range was obtained for the iso-/n-butane pair. However, all of the experiments were conducted on a small scale with flowrate of < 25 gram/min. Recently, we demonstrated this technology on a larger scale (<250 gram/min). Within the loading range of F-factor < 2.2 Pa{sup 0.5}, a pressure drop on the vapor side is below 50 mbar/m, which suggests that the pressure drop of hollow fibers packings is not an engineering barrier for the applications in distillations. The thermal stability study suggests that polypropylene hollow fibers are stable after a long time exposure to C{sub 2} - C{sub 4} mixtures. The effects of packing density on the separation efficiency will be discussed.

Yang, Dali [Los Alamos National Laboratory; Orler, Bruce [Los Alamos National Laboratory; Tornga, Stephanie [Los Alamos National Laboratory; Welch, Cindy [Los Alamos National Laboratory

2011-01-26

48

A geometric design method for side-stream distillation columns  

Microsoft Academic Search

A side-stream distillation column may replace two simple columns for some applications, sometimes at considerable savings in energy and investment. This paper describes a geometric method for the design of side-stream columns; the method provides rapid estimates of equipment size and utility requirements. Unlike previous approaches, the geometric method is applicable to nonideal and azeotropic mixtures. Several example problems for

Raymond E. Rooks; Michael F. Malone; Michael F. Doherty

1996-01-01

49

Applying risk assessment principles to a batch distillation column  

Microsoft Academic Search

Some distillation columns in the chemical industry are operated in batch mode with a fairly short operating cycle. At the end of each cycle the columns are cooled and recharged. During the cooling cycle, air will be drawn into the column by the action of a vacuum relief valve. Consequently, for a finite portion of the operating cycle a flammable

John L. Woodward; Michael D. Moosemiller; Robert Chopp

1996-01-01

50

Improved direct and indirect systems of columns for ternary distillation  

SciTech Connect

Separation of a ternary mixture into almost pure components is discussed. Systems of distillation columns, with higher thermodynamic efficiency, are developed from a direct sequence (or indirect sequence) of distillation columns by allowing for two interconnecting streams of the same composition and different enthalpy. This increases the reversibility of distillation in the second column, which results in replacing a portion of the high-temperature boiling duty with a lower-temperature heat in the direct split case. For the indirect split case, the improvement allows a portion of the low-temperature condensing duty to be replaced with a higher-temperature condensation.

Agrawal, R.; Fidkowski, Z.T. [Air Products and Chemicals, Inc., Allentown, PA (United States)

1998-04-01

51

Method and Apparatus for Packed Column Separations and Purifications.  

National Technical Information Service (NTIS)

In one aspect, the invention encompasses a method of packing and unpacking a column chamber. A mixture of a fluid and a matrix material are introduced through a column chamber inlet so that the matrix material is packed within a column chamber to form a p...

C. J. Bruckner-Lea D. A. Holman D. P. Chandler F. J. Brockman

2005-01-01

52

A Twist on Packing Columns for Reversed Phase Liquid Chromatography  

Microsoft Academic Search

Liquid chromatography is one of the most widely used analytical techniques for the separation of complex mixtures. Great advances have been made in the last twenty years in column technology, i.e. stationary phases, but few advances have been made in column packing technology. In this study, two new methods for packing analytical reversed-phase liquid chromatography (RPLC) columns are introduced: radially

J. Paul McCall

2004-01-01

53

A nonequilibrium model for dynamic simulation of tray distillation columns  

Microsoft Academic Search

A nonequilibrium model for the dynamic simulation of distillation columns is described. The nonequilibrium model includes the direct calculation of the rates of mass and energy transfer and is better able to model the actual physical processes occurring on a real distillation tray than is the conventional equilibrium stage model. Example calculations show that heat-transfer limitations and the vapor holdup

Hendrik A. Kooijman; Ross Taylor

1995-01-01

54

Entropy production and exergy loss in experimental distillation columns  

Microsoft Academic Search

Diabatic distillation, i.e. with heat exchangers on all trays, can increase the second law energy efficiency drastically compared to adiabatic distillation. The purpose of this research was to describe the entropy production rate in one adiabatic and one diabatic experimental water\\/ethanol rectifying column by applying the theory of irreversible thermodynamics. As a benchmark for the description, an exergy analysis of

Gelein de Koeijer; Ricardo Rivero

2003-01-01

55

Systems for column-based separations, methods of forming packed columns, and methods of purifying sample components  

Microsoft Academic Search

The invention encompasses systems for column-based separations, methods of packing and unpacking columns and methods of separating components of samples. In one aspect, the invention includes a method of packing and unpacking a column chamber, comprising: a) packing a matrix material within a column chamber to form a packed column; and b) after the packing, unpacking the matrix material from

Oleg B. Egorov; Matthew J. OHara; Jay W. Grate; Darrell P. Chandler; Fred J. Brockman; Cynthia J. Bruckner-Lea

2000-01-01

56

Systems For Column-Based Separations, Methods Of Forming Packed Columns, And Methods Of Purifying Sample Components  

Microsoft Academic Search

The invention encompasses systems for column-based separations, methods of packing and unpacking columns and methods of separating components of samples. In one aspect, the invention includes a method of packing and unpacking a column chamber, comprising: a) packing a matrix material within a column chamber to form a packed column; and b) after the packing, unpacking the matrix material from

Oleg B. Egorov; Matthew J. OHara; Jay W. Grate; Darrell P. Chandler; Fred J. Brockman; Cynthia J. Bruckner-Lea

2006-01-01

57

Systems For Column-Based Separations, Methods Of Forming Packed Columns, And Methods Of Purifying Sample Components  

Microsoft Academic Search

The invention encompasses systems for column-based separations, methods of packing and unpacking columns and methods of separating components of samples. In one aspect, the invention includes a method of packing and unpacking a column chamber, comprising: a) packing a matrix material within a column chamber to form a packed column; and b) after the packing, unpacking the matrix material from

Oleg B. Egorov; Matthew J. OHara; Jay W. Grate; Darrell P. Chandler; Fred J. Brockman; Cynthia J. Bruckner-Lea

2004-01-01

58

Imaging of liquid distribution in reactive distillation packings with a new high-energy x-ray tomograph  

NASA Astrophysics Data System (ADS)

We describe a new, high-energy (420 kV), large-scale (0.45 m in diameter, 4 m in height) x-ray tomograph developed to investigate gas and liquid flow through fixed bed like absorption, distillation and reactive distillation columns. The first results obtained with this set-up on test objects (physical phantoms), such as a cylindrical container filled with water or a large diameter structured metallic packing, validate the technique as a quantitative tool for geometrical measurements. Very detailed two-dimensional (2D) and three-dimensional (3D) images of a 0.09 m diameter KATAPAK-SP 12, a reactive distillation packing, are presented. Quantitative information relative to liquid hold-up distribution may be obtained from tomographic imaging performed on an irrigated column packed with this element.

Toye, D.; Crine, M.; Marchot, P.

2005-11-01

59

Experimental study of wave propagation dynamics of multicomponent distillation columns  

SciTech Connect

Distillation columns with sharp separations exhibit severely nonlinear behavior, which has been known to cause difficulties in column control and design. Such a column is characterized by sharp composition and temperature variations in the column. Previously, the binary distillation case was thoroughly analyzed using a nonlinear wave theory and such an analysis was experimentally validated. For multicomponent distillation, the complicated nonlinear dynamics of the movement and interference of multiple sharp composition variations can be elucidated with a coherent-wave theory developed earlier for general countercurrent separation processes. With a ternary alcohol mixture, the present study has experimentally verified the theory by demonstrating the existence and propagation of constant-pattern coherent waves in a 50-tray stripping column in response to a step disturbance of feed composition, feed flow rate, or reboiler heat supply. The study has also tested the theory's predictions of composition profile, wave velocities, and asymmetric dynamics.

Ting, J.; Helfferich, F.G.; Hwang, Y.L.; Graham, G.K.; Keller, G.E. II

1999-10-01

60

Dual cascade control design for binary distillation columns  

Microsoft Academic Search

In this paper, a linear cascade scheme to control both effluent purities in binary distillation columns with temperature and delayed composition measurements is presented. First, the column input-output behavior is modeled as a set of linear integrators, driven by control inputs and reconstruction load disturbances. This control model yields a linear cascade control scheme with: (i) a purely integral decentralized

Eduardo Castellanos-Sahagún; Jesús Alvarez

2006-01-01

61

Exergetic and economic analysis of an industrial distillation column  

Microsoft Academic Search

In this work, applications of exergy and economic concepts to compression, heat exchange, and separation processes were used for calculation of the irreversibility rate, thermodynamic efficiency, and internal rate of return (IRR) of the profitability. A case study based on a real process, the purification of 1,2- dichloroethane (DCE) in a high-purity distillation column, is presented. This column has the

A. C. B. Araújo; L. G. S. Vasconcelos; M. F. Fossy; R. P. Brito

2007-01-01

62

Efficiencies of trays in cryogenic distillation columns  

NASA Astrophysics Data System (ADS)

This Paper considers the behaviour of the distillation trays in conventional use in cryogenic air separation plants. An earlier study showed that the trays should operate at higher efficiencies than plant experience would indicate. This conclusion was based on the assumption of uniform liquid flow across the trays. In practice, stagnant zones can occur which reduce the efficiency. A study of a small hole-size tray, rectangular in shape, providing uniform flow has confirmed the predictions of the theoretical model by producing high efficiencies. These results, together with those from the earlier study, provide an indication of the benefits of improving the flow behaviour of air separation distillation trays.

Biddulph, M. W.

1986-01-01

63

Temperature cascade control of distillation columns  

SciTech Connect

This paper examines how difficult control tasks are enhanced by introducing secondary measurements, creating control cascades. Temperature is much used as secondary measurement because of cheap implementation and quick and accurate response. Distillation is often operated in this manner due to slow or lacking composition measurements, although the benefits have hardly been investigated closely, especially for multivariable control applications. The authors therefore use distillation as the example when quantifying improvements in interaction and disturbance rejection. They also give analytical expressions for the secondary controller gain. The improvements are reached through simple cascade operation of the control system and require no complicated estimator function.

Wolff, E.A.; Skogestad, S. [Univ. of Trondheim (Norway). Dept. of Chemical Engineering

1996-02-01

64

Perfusion chromatography — characterization of column packings for chromatography of proteins  

Microsoft Academic Search

A Van Deemter equation modeling columns packed with spherical monodisperse perfusive media was utilized to calculate the predicted values of the effective pore diffusivity (Dp) and split ratio (?) of columns packed with POROS® and Oligo R3™ media. The validity of the model was established by calculating consistent values of Dp and ? for lysozyme, ?-chymotrypsinogen A and IgG using

Mark McCoy; Krishna Kalghatgi; Fred E. Regnier; Noubar Afeyan

1996-01-01

65

Air separation process using packed columns for oxygen and argon recovery  

Microsoft Academic Search

This patent describes an improvement in a process for the separation of mixtures, which comprise oxygen, nitrogen, and argon, by cryogenic distillation in an integrated multi-column distillation system of at least three distillation columns, having a higher pressure column, low pressure column and an argon sidearm column. Wherein the argon sidearm column integrally communicates with the low pressure column. Wherein

R. M. Thorogood; D. L. Bennett; R. J. Allam; A. L. Prentice; B. K. Dawson

1989-01-01

66

Mechanistic pressure drop model for columns containing structured packings  

Microsoft Academic Search

A mechanistic model was developed to predict pressure drop and flooding in packed columns equipped with corrugated packing of the regular type. It was developed after considering the interaction of falling liquid film with the gas phase, based on mass- and momentum-conservation equations. Among the most common structured packings, the behavior of the Mellapak and BX types was analyzed. The

E. Brunazzi; Alessandro Paglianti

1997-01-01

67

Temperature–enthalpy curve for energy targeting of distillation columns  

Microsoft Academic Search

The temperature–enthalpy (T–H) diagram of a distillation column at practical near-minimum thermodynamic condition (PNMTC) or the column grand composite curve (CGCC) is a useful representation for energy targeting studies and may be generated from a converged simulation of a base-case column design. The calculation procedure for the CGCC involves determination of the net enthalpy deficit at each stage by generating

Santanu Bandyopadhyay; Ranjan K. Malik; Uday V. Shenoy

1998-01-01

68

Self-Tuning Control of Distillation Columns: Theory and Practice  

Microsoft Academic Search

An experimental evaluation of multivariable self-tuning control algorithms for the simultaneous control of both top and bottom product compositions of a binary distillation column is presented. The study was carried out using an 8-tray, 30.5 cm diameter methanol-water pilot scale column. The column is controlled using an LSI 11\\/03 microcomputer with continuous capacitance analysis of top product composition and with

F. Vagi; R. K. Wood; A. J. Morris; M. Tham

1985-01-01

69

Dynamic and Steady State Behaviour of an Extractive Distillation Column  

Microsoft Academic Search

This project was the second part of a long-term study into the control of an extractive distillation unit. A fifteen stage extractive distillation column was re-built and operated over a range of operating levels. Overhead product acetone composition was limited to approximately 0.94 mole fraction acetone due to tray liquid priming. A steady state simulation was developed to aid in

Dwayne L. ONeill

1975-01-01

70

Minimum-reflux regime of simple distillation columns  

Microsoft Academic Search

A general algorithm for calculating minimum reflux ratios in simple distillation columns used for the separation of ideal\\u000a and nonideal (including azeotropic) homogeneous multicomponent mixtures is proposed. The algorithm deals with various splits:\\u000a direct, indirect, intermediate, and with one distributed component. The algorithm is mathematically rigorous, developed on\\u000a the basis of the geometrical theory of distillation, and makes it possible

R. Yu. Danilov; F. B. Petlyuk; L. A. Serafimov

2007-01-01

71

Kinetic azeotropy and design of reactive distillation columns  

SciTech Connect

The reactive fixed points in the distillation maps of a reactive distillation column (RDC) with kinetically controlled reactions are identified and their role in deciding the design feasibility has been elucidated. The fixed points at which both reaction and distillation vectors have zero magnitudes correspond to the equilibrium fixed point. It is known that the relative positions of these points for the rectifying and stripping sections determine the value of the minimum reflux ratio. However, apart from these fixed points, there are certain fixed points in the distillation map at which, though the reaction and distillation vectors have nonzero magnitudes, they nullify the effects of each other. These points correspond to the kinetic fixed points and have a special significance. Their positions have direct influence on the feasible product composition. A simple example of an ideal ternary system undergoing a reaction 2B {longleftrightarrow} A + c has been illustrated to show the importance of kinetic azeotropy in the design aspects of RDC.

Mahajani, S.M. [Monash Univ., Clayton, Victoria (Australia). Dept. of Chemical Engineering

1999-01-01

72

Improved operational policies for batch extractive distillation columns  

SciTech Connect

The authors and others have previously developed insights into batch distillation when using a middle vessel batch column. They extended earlier work on reachable product regions for continuous columns to this and other batch column configurations. The work also examined the use of a continuously flowing extractive agent to facilitate the separation of azeotropic mixtures. A middle vessel batch column has both an enriching and stripping section and thus both a distillate and bottoms product. In many ways it is just like a traditional continuous column, but the authors feed it by charging a middle tray having a very large holdup (a pot or still) with the initial feed. The work compared running this column with running a batch rectifier for an azeotropic mixture when using an extractive agent. They showed that both are often able in theory to recover all of the distillate component in relatively pure form, with the middle vessel accomplishing this by steering the still pot composition against time through the choice of reflux, reboil, entrainer, and product rates. The middle vessel also requires a much smaller pot, as the authors can continually remove and recycle the extractive agent. In this work the authors show the sensitivity of the separation`s profit to the entrainer flow rate, the operation`s switching times between fractions, and the bottom flow rate policy for an extractive middle vessel batch column. They illustrate with an example problem.

Safrit, B.T.; Westerberg, A.W. [Carnegie Mellon Univ., Pittsburgh, PA (United States)

1997-02-01

73

Experimental results of hydrogen distillation at the low power cryogenic column for the production of deuterium depleted hydrogen  

SciTech Connect

The Deuterium Removal Unit (DRU) has been designed and built at the Petersburg Nuclear Physics Inst. (PNPI) to produce isotopically pure hydrogen with deuterium content less than 1 ppm. The cryogenic distillation column of 2.2 cm inner diameter and 155 cm packing height is the main element of the DRU. Column performances at different hydrogen distillation operating modes have been measured. The height equivalent to theoretical plate (HETP) for the column is 2.2 cm and almost constant over a wide range of vapour flow rates. Deuterium depleted hydrogen with a deuterium content of less than 0.1 ppm was produced in required quantity. (authors)

Alekseev, I.; Fedorchenko, O.; Kravtsov, P.; Vasilyev, A.; Vznuzdaev, M. [Petersburg Nuclear Physics Inst., Leningrad district, Gatchina, 188300 (Russian Federation)

2008-07-15

74

Multivariable control of an energy-integrated distillation column  

SciTech Connect

Distillation columns that have design modifications for the purpose of more efficient-energy utilization are often complex systems which present difficult process control problems. The work discusses the theory and development of several algorithms that offer improved controller responses and operational flexibility. One of the major contributions of this work is the development of methods where the number of manipulated variables exceeds the number of controlled variables. The system is a binary distillation column equipped with an intermediate heat exchanger that partially condenses vapors in the rectifying section of the column. This intermediate condenser allows a portion of the energy expended in the reboiler to be recovered at a useful temperature. The inter-condenser heat duty was examined for use as an extra process control input, used for regulating the distillate and bottoms product compositions, which were the controlled variables. Both conventional energy balance control pairing and material balance pairing were examined in conjunction with the intermediate condenser system. Three different controller algorithms were developed for designing non-square process controllers; a switching MVSISO method, multivariable optimal control, and structural compensation were implemented on a computer simulation of the distillation unit. A second part of the research is the development of accurate low order models for distillation systems. In particular, a reduced order, compartmental modeling approach was investigated for simulation and process control applications. This research identified critical parameters of the compartmental model which affect the accuracy of the resulting low order dynamic model.

Horton, R.R.

1987-01-01

75

An indirect feedforward composition controller for distillation columns  

Microsoft Academic Search

This paper addresses the problem of designing an indirect feedforward controller, also called cascade control, to regulate the product composition of distillation columns to overcome load disturbances. The overall controller is composed of two cascaded controllers. The primary controller is basically a low-gain controller, which uses slow (delayed) composition measurements to provide servo responses (composition control). The secondary controller has

Rosendo Monroy-Loperena; Jose Alvarez-Ramirez

2002-01-01

76

Absorption of NO x in packed column (I)  

Microsoft Academic Search

A mathematical model for an absorption of nitrogen oxides into water in packed column was developed based on the mass-transfer\\u000a coefficient in packed column and the chemical reaction accompanying NO\\u000a x\\u000a absorption produces HNO3 and HNO2 in the liquid phase. The subsequent dissociation of HNO2 in the liquid-phase results in the formation of HNO3 and NO gas, and then this

Hoo Kun Lee; Kwan Sik Chun; Hyun Soo Park; Jong Hyun Cho

1989-01-01

77

The furification process in hydraulic packed-bed wash columns  

Microsoft Academic Search

Hydraulic packed-bed wash columns are continuous solid-liquid separators, which can be applied as the final step in fractional suspension crystallization processes aimed at ultrapurification of organic compounds. In this paper an experimental study and a mathematical model of the purification process in packed-bed wash columns are presented. The developed model can be used to calculate concentration, temperature and porosity profiles

M. Matsuoka

1995-01-01

78

Air dehumidification by triethylene glycol desiccant in a packed column  

Microsoft Academic Search

The performance of an air dehumidifier using triethylene glycol (TEG) as desiccant under hot and humid conditions was investigated. The performance of the dehumidifier was evaluated and expressed in terms of the moisture removal rate and the dehumidifier effectiveness. A packed bed column (dehumidifier) was employed, with low packing density (77 m2\\/m3), to provide direct contact between the air and

Y. H. Zurigat; M. K. Abu-Arabi; S. A. Abdul-Wahab

2004-01-01

79

A geometric design method for side-stream distillation columns  

SciTech Connect

A side-stream distillation column may replace two simple columns for some applications, sometimes at considerable savings in energy and investment. This paper describes a geometric method for the design of side-stream columns; the method provides rapid estimates of equipment size and utility requirements. Unlike previous approaches, the geometric method is applicable to nonideal and azeotropic mixtures. Several example problems for both ideal and nonideal mixtures, including azeotropic mixtures containing distillation boundaries, are given. The authors make use of the fact that azeotropes or pure components whose classification in the residue curve map is a saddle can be removed as side-stream products. Significant process simplifications are found among some alternatives in example problems, leading to flow sheets with fewer units and a substantial savings in vapor rate.

Rooks, R.E.; Malone, M.F.; Doherty, M.F. [Univ. of Massachusetts, Amherst, MA (United States). Dept. of Chemical Engineering

1996-10-01

80

Experimental study of wave propagation dynamics of binary distillation columns  

SciTech Connect

High-purity distillation columns are typically difficult to control because of their severely nonlinear behavior reflected by their sharp composition and temperature profiles. The dynamic behavior of such a column, as characterized by the movement of its sharp profile, was elucidated by a nonlinear wave theory established previously. With binary alcohol mixtures, this study provides an experimental observation of such wave-propagation dynamics of a 40-tray stripping column and a 50-tray fractionation column in response to step disturbances of feed composition, feed flow rate, and reboiler heat supply. These experimental results have verified that the sharp profile in a high-purity column moves as a constant-pattern wave and that the nonlinear wave theory predicts its velocity satisfactorily with very simple mathematics. Results also demonstrate the asymmetric dynamics of the transitions between two steady states.

Hwang, Y.L.; Graham, G.K.; Keller, G.E. II [Union Carbide Corp., South Charleston, WV (United States); Ting, J.; Helfferich, F.G. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Chemical Engineering

1996-10-01

81

A nonequilibrium model for dynamic simulation of tray distillation columns  

SciTech Connect

A nonequilibrium model for the dynamic simulation of distillation columns is described. The nonequilibrium model includes the direct calculation of the rates of mass and energy transfer and is better able to model the actual physical processes occurring on a real distillation tray than is the conventional equilibrium stage model. Example calculations show that heat-transfer limitations and the vapor holdup above the froth cannot be neglected at elevated pressures. Back-computed Murphree tray efficiencies are not constant over time, which implies that the equilibrium model should not be used for dynamic simulations.

Kooijman, H.A.; Taylor, R. [Clarkson Univ., Potsdam, NY (United States). Dept. of Chemical Engineering

1995-08-01

82

A general distillation modeling framework applied to an isotopic distillation column  

Microsoft Academic Search

Being one of the most approached subjects in the field of chemical engineering, a lot of numerical modeling methods for the distillation columns were presented in scientific papers. This means that in order to find a model that would suit a specific process requires a considerable amount of time. This paper will present a general first principle model that aims

Ionut Muntean; Maxim Stuckert; Mihail Abrudean

2011-01-01

83

Capillary electrochromatography using columns packed with a supercritical fluid carrier  

Microsoft Academic Search

Columns for capillary electrochromatography may be prepared by packing reversed phase silica-based material using a supercritical fluid carbon dioxide carrier. Procedures for the in-situ manufacture of frits and UV detection windows, and the wetting of columns are described. The columns were employed in two commercial instruments (and a home-built system), and their properties investigated during the separation of standard mixtures

M. M. Robson; S. Roulin; S. M. Shariff; M. W. Raynor; K. D. Bartle; A. A. Clifford; P. Myers; M. R. Euerby; C. M. Johnson

1996-01-01

84

New materials and packing techniques for micro-HPLC packed capillary columns  

Microsoft Academic Search

Summary  Plastic tubing of polyetheretherketone (PEEK) is used for the preparation of HPLC packed capillary columns. The polymer is\\u000a rigid but not fragile, has great resistance to chemical and physical agents and comes in standard 1\\/16? O.D. These features\\u000a can extend the column lifetime and facilitate the overall employment of HPLC capillary columns. Serial connection of short\\u000a columns is also possible

A. Cappiello; P. Palma; F. Mangani

1991-01-01

85

THE THEORY OF THE NON-STATIONARY BEHAVIOR OF DISTILLATION COLUMNS  

Microsoft Academic Search

In order to be able to control distillation columns in an optimum ; manner, it is necessary to investigate the behavior of the distillation column at ; control intervals. The behavior of a 5- and a 30-stage distillation column was ; investigated for imposed fluctuations of the initiai concentrations. (trauth);

G. Voigt; O. Gebhardt

1962-01-01

86

Comparison of drug substance impurity profiles generated with extended length columns during packed-column SFC  

Microsoft Academic Search

The current study assesses the effect of extending column length during gradient packed column sub\\/supercritical fluid chromatography (PCSFC) experiments on the detection of known and unknown impurities in a drug substance sample. Quantitative drug substance impurity profiles were generated and compared using multiple column PCSFC and HPLC conditions. Also, chromatographic figures of merit were estimated and compared for components of

Daryl A Roston; Saleem Ahmed; Doug Williams; Tom Catalano

2001-01-01

87

Applying risk assessment principles to a batch distillation column  

SciTech Connect

Some distillation columns in the chemical industry are operated in batch mode with a fairly short operating cycle. At the end of each cycle the columns are cooled and recharged. During the cooling cycle, air will be drawn into the column by the action of a vacuum relief valve. Consequently, for a finite portion of the operating cycle a flammable mixture will exist in the column. Here we evaluate the risk posed by such an operation to see if a mitigation measure is justified. We develop a fault tree and estimate the frequency of ignition by all possible ignition sources. By comparing the risk reduction attainable by installing a lightning protection system with that attainable by using an inert blanketing system the lightning protection system is found to be the preferred solution. It provides about the same risk reduction at a lower overall cost. 2 refs., 3 figs., 4 tabs.

Woodward, J.L.; Moosemiller, M.D. [DNV Technica, Columbus, OH (United States)

1996-12-31

88

Fuzzy Control of Distillation Columns with and without Side Streams  

Microsoft Academic Search

\\u000a Besides the classical control theories the method of fuzzy control gains increasing interest. A great number of publications\\u000a deals with this topic describing it as very efficient concept. In this paper the development of control systems based upon\\u000a fuzzy control theory for distillation columns with and without sidestreams is pointed out. The performance of this control\\u000a application is compared to

Chr. Remberg; G. Fieg; G. Wozny; F. N. Fett

89

The second law optimal state of a diabatic binary tray distillation column  

Microsoft Academic Search

A new numerical procedure to minimize the entropy production in diabatic tray distillation columns has been developed. The method was based on a least square regression of the entropy production at each tray. A diabatic column is a column with heat exchangers on all trays. The method was demonstrated on a distillation column separating propylene from propane. The entropy production

A. Røsjorde; S. Kjelstrup

2005-01-01

90

Flooding and Mass Transfer in Goodloe-Packed Columns.  

National Technical Information Service (NTIS)

Flooding and mass transfer experiments were performed with a CO sub 2 -air/water system to examine mass transfer characteristics in Goodloe-packed columns of 6.4 and 15.2-cm ID for removal of radioactive Kr from HTGR off-gas. The flooding experiments veri...

E. I. Chao R. J. Bertolami J. L. P. Varlet G. R. Wilkes

1976-01-01

91

Immobilization of enzymes on polytetrafluoroethylene particles packed in HPLC columns  

Microsoft Academic Search

The use of polytetrafluoroethylene particles packed in short, high performance liquid chromatography columns for the immobilization of enzymes is examined. In particular, lactate dehydrogenase chosen as a model system was investigated with regard to activity and stability when immobilized on polytetrafluoroethylene. (Refs. 7).

Neil. D. Danielson; Richard W. Siergiej

1981-01-01

92

Immobilization of enzymes on polytetrafluoroethylene particles packed in HPLC columns  

SciTech Connect

The use of polytetrafluoroethylene particles packed in short, high performance liquid chromatography columns for the immobilization of enzymes is examined. In particular, lactate dehydrogenase chosen as a model system was investigated with regard to activity and stability when immobilized on polytetrafluoroethylene. (Refs. 7).

Danielson, N.D.; Siergiej, R.W.

1981-08-01

93

Sintered octadecylsilica as monolithic column packing in capillary electrochromatography and micro high-performance liquid chromatography  

Microsoft Academic Search

Fused-silica capillaries were packed with porous 6-?m octadecylated silica microspheres and subjected to thermal treatment in order to obtain a column with porous silica based monolithic packing. After sintering, the monolithic packing was reoctadecylated in situ with dimethyloctadecylchlorosilane. The mechanical strength and stability of the monolithic column were significantly greater than those of conventional columns packed with particulate stationary phase.

Reza Asiaie; Xian Huang; Dell Farnan; Csaba Horváth

1998-01-01

94

Experimental study on pressure drops in a dividing wall distillation column  

Microsoft Academic Search

Previous studies in the fields of process design and process control [1] have shown the potential benefits that can be achieved through the implementation of thermally coupled distillation sequences, in particular, the dividing wall distillation column. The dividing wall distillation column meets important goals of process intensification, including energy savings, reduction in carbon dioxide emissions and miniaturization. In this paper,

Fabricio Omar Barroso-Muñoz; Salvador Hernández; Héctor Hernández-Escoto; Juan Gabriel Segovia-Hernández; Vicente Rico-Ramírez; Rosa-Hilda Chavez

2010-01-01

95

High performance liquid chromatography column packings with deliberately broadened particle size distribution: Relation between column performance and packing structure  

Microsoft Academic Search

The effect of the addition of 25%, 50% and 75% (weight percent, wt%) of larger particles (resp. 3 and 5?m) to a commercial batch of 1.9?m particles has been investigated as an academic exercise to study the effects of particle size distribution on the kinetic performance of packed bed columns in a magnified way. Comparing the performance of the different

Anuschka Liekens; Jeroen Billen; Ron Sherant; Harald Ritchie; Joeri Denayer; Gert Desmet

2011-01-01

96

Temperature effects on nano-LC column packing technology.  

PubMed

We investigated the effect of temperature on the packing procedure of nano-LC columns (up to 50 cm) and on their performance. Several slurries of stationary phase were prepared using different solvent mixtures. Their stability was evaluated at several temperatures: 70°C, 50°C, and room temperature. At the higher temperature (70°C) the suspensions resulted to be stable for a longer time. For each slurry, we compared nano-LC columns packed with ultrasounds at 70°C and at room temperature. All the columns were tested with a standard mixture at 70°C, to reduce the solvent viscosity and the backpressure. Main chromatographic parameters such as the asymmetry factor, As, the reduced plate high, h, pattern in a Van Deemter plot, the total porosity, ?(t), and the permeability, k, were calculated and discussed. One of the nano-LC columns was used to separate a mixture of pesticides in a LC-MS system with an electron ionization LC-MS interface (Direct-EI). From our knowledge, this is the first study on the role of temperature in the efficiency of slurry-packing procedure. PMID:22761136

Leonardis, Irene; Capriotti, Fabiana; Cappiello, Achille; Famiglini, Giorgio; Palma, Pierangela

2012-07-01

97

METHOD TO TEST ISOTOPIC SEPARATION EFFICIENCY OF PALLADIUM PACKED COLUMNS  

SciTech Connect

The isotopic effect of palladium has been applied in different ways to separate hydrogen isotopes for many years. At Savannah River Site palladium deposited on kieselguhr (Pd/k) is used in a thermal cycling absorption process (TCAP) to purify tritium for over ten years. The need to design columns for different throughputs and the desire to advance the performance of TCAP created the need to evaluate different column designs and packing materials for their separation efficiency. In this work, columns with variations in length, diameter and metal foam use, were tested using an isotope displacement method. A simple computer model was also developed to calculate the number of theoretical separation stages using the test results. The effects of column diameter, metal foam and gas flow rate were identified.

Heung, L; Gregory Staack, G; James Klein, J; William Jacobs, W

2007-06-27

98

Tests of isotopic separation efficiency of palladium packed columns  

SciTech Connect

The isotopic effect of palladium has been applied in different ways to separate hydrogen isotopes for many years. At Savannah River Site palladium deposited on kieselguhr (Pd/k) is used in a thermal cycling absorption process (TCAP) to purify tritium for over ten years. The need to design columns for different throughputs and the desire to advance the performance of TCAP created the need to evaluate different column designs and packing materials for their separation efficiency. In this work, columns with variations in length, diameter and metal foam presence were tested using an isotope displacement method. A simple computer model was also developed to calculate the number of theoretical separation stages based on the test results. The effects of column diameter, metal foam presence and gas flow rate were identified. (authors)

Heung, L. K.; Staack, G. C.; Klein, J. E.; Jacobs, W. D. [Savannah River National Laboratory, 773-A, Savannah River Site, Aiken, SC 29808 (United States)

2008-07-15

99

Liquid holdup in columns packed with structured packings: Countercurrent vs. cocurrent operation  

Microsoft Academic Search

An experimental study of the liquid holdup and the liquid holdup axial profile in a square section column with structured packing is carried out. Both cocurrent and countercurrent operations are examined. A conductivity technique to estimate liquid holdups is proposed and calibrated against values measured by the drainage method. Liquid holdups estimated by this technique follow the same trends as

Alejandra Muzen; Miryan C. Cassanello

2005-01-01

100

Faster axial band dispersion in a monolithic silica column than in a particle-packed column.  

PubMed

The contribution of molecular diffusion to peak broadening was studied in a reversed-phase HPLC system, consisting of a monolithic silica C18 column and methanol-water mobile phase. Study on the band broadening effect of holding a solute in a column or elution at very low linear velocity of mobile phase allowed facile determination of the contribution of the molecular diffusion term. Less obstruction against molecular diffusion, or the faster axial band dispersion in a monolithic silica column than in a particle-packed column, was found both in mobile phase and in stationary phase. PMID:16360662

Kobayashi, Hiroshi; Tokuda, Daisuke; Ichimaru, Jun; Ikegami, Tohru; Miyabe, Kanji; Tanaka, Nobuo

2005-12-19

101

LONGITUDINAL MIXING IN PACKED GAS-ABSORPTION COLUMNS  

Microsoft Academic Search

Longitudinal-mixing experiments were conducted in a 2-ft-dia. gas-; absorption column by using tracer-injection techniques. The carrier streams were ; air and water. Empirical Peclet-number correlations are presented for both ; phases, with 1-in. Berl saddles, 1-in. Raschig rings, and 2-in. Raschig rings ; used as packing materials. The extent of mixing was much greater in the liquid ; phase than

W. E. Dunn; T. Vermeulen; C. R. Wilke; T. T. Work

1962-01-01

102

Supercritical fluid chromatography with small particle diameter packed columns  

Microsoft Academic Search

Supercritical fluid chromatography is carried out with 10, 5, and 3 ..mu..m particle diameter packed columns. Reduced plate heights between 2.0 and 3.0 are achieved in the region of the van Deemter minimum. Using polycyclic aromatic hydrocarbons as probe molecules, the relationship of density of supercritical carbon dioxide to log capacity factor was studied between 32 and 100°C. The efficiency

Dennis R. Gere; Robert. Board; Douglass. McManigill

1982-01-01

103

Nitrate removal in zero-valent iron packed columns  

Microsoft Academic Search

Nitrate removal by laboratory and field continuous-flow zero-valent iron (Fe0) packed bed columns was evaluated for different influent water qualities (pH, dissolved oxygen (DO), nitrate concentration) and several months of operation (600–1500 bed volumes (BVs)). In contrast to previous batch experiments with Fe0 where nitrate was stoichiometrically converted to ammonium, only 70% of the applied nitrogen was recovered as nitrate,

Paul Westerhoff; Jennifer James

2003-01-01

104

Platelet retention in columns packed with glass beads  

Microsoft Academic Search

Platelet retention in columns packed with glass beads has been theoretically analyzed in a manner similar to that commonly\\u000a used to describe the behavior of fixed-bed adsorbers. Combining the results of this analysis with experimental observations\\u000a has confirmed that the process of platelet deposition from whole blood onto glass bead surfaces is entirely adsorption controlled.\\u000a In contrast to this finding,

Channing R. Robertson; Ho Nam Chang

1974-01-01

105

Adsorption of Polypropylene and Polyethylene on Liquid Chromatographic Column Packings  

Microsoft Academic Search

A group of zeolites and a 3D nanoporous metal-organic material RPM-1 were tested as column packings for adsorption of isotactic polypropylene and linear polyethylene from dilute solutions. It was found that polyethylene is fully or partially retained from thermodynamically good solvents (1,1,2,2-tetrachloroethylene, 1,4-dimethylbenzene, diphenylether, 1,2-dichlorobenzene and 1,3-dichlorobenzene) at temperatures of 115 °C or 140 °C, when a specific type of

T. Macko; J. F. Denayer; H. Pasch; L. Pan; J. Li; A. Raphael

2004-01-01

106

Comparison of different packing methods for capillary electrochromatography columns  

Microsoft Academic Search

A study was carried out in which 50 ?m I.D. fused-silica capillaries were packed with 3 ?m octadecylsilane bonded silica, from the same batch, by four methods; liquid slurry and carbon dioxide supercritical carrier, each with and without the use of an ultrasonic probe. A neutral test mixture was analysed by capillary column in reversed-phase mode, and the reproducibility of

Stephanie Roulin; Richard Dmoch; Richard Carney; Keith D Bartle; Peter Myers; Melvin R Euerby; Christopher Johnson

2000-01-01

107

High performance liquid chromatography column packings with deliberately broadened particle size distribution: relation between column performance and packing structure.  

PubMed

The effect of the addition of 25%, 50% and 75% (weight percent, wt%) of larger particles (resp. 3 and 5 ?m) to a commercial batch of 1.9 ?m particles has been investigated as an academic exercise to study the effects of particle size distribution on the kinetic performance of packed bed columns in a magnified way. Comparing the performance of the different mixtures in a kinetic plot, it could be irrefutably shown that the addition of larger particles to a commercial batch of small particles cannot be expected to lead to an improved kinetic performance. Whereas the addition of 25 wt% of larger particles still only has a minor negative effect, a significantly deteriorated performance is obtained when 50 or 75 wt% of larger particles are added. In this case, separation impedance number increases up to 200% were observed. Studying the packing structure through computational packing simulations, together with the experimental determination of the external porosity, helped in understanding the obtained results. This showed that small particles tend to settle in the flow-through pores surrounding the larger particles, leading to very high packing densities (external porosities as low as 32% were observed) and also negatively influencing the column permeability as well as the band broadening (because of the broadened flow-through pore size range). PMID:21862028

Liekens, Anuschka; Billen, Jeroen; Sherant, Ron; Ritchie, Harald; Denayer, Joeri; Desmet, Gert

2011-07-24

108

Nonlinear Model Predictive Control of High Purity Distillation Columns for Cryogenic Air Separation  

Microsoft Academic Search

High purity distillation columns are critical unit operations in cryogenic air separation plants that supply purified gases to a number of industries. We have developed a nonlinear model predictive control (NMPC) strategy based on the assumption of full-state feedback for a prototypical cryogenic distillation column to allow effective operation over a wide range of plant production rates. The controller design

Zhongzhou Chen; Michael A. Henson; Paul Belanger; Lawrence Megan

2010-01-01

109

Dividing wall distillation columns for separation of azeotropic mixtures: feasibility procedure and rigorous optimization  

Microsoft Academic Search

In this work, we propose the use of dividing wall distillation columns, DWC, to separate azeotropic mixtures. First, we present a procedure to guarantee the feasibility of the desired split, based on material balances. Once the feasibility is verified, a preliminary design is calculated considering the DWC as an arrangement of three disengaged conventional distillation columns. Then, this design is

Abel Briones-Ramírez; Claudia Gutiérrez-Antonio

2009-01-01

110

Effects of helium on separation characteristics of cryogenic distillation column cascade for fusion reactor  

Microsoft Academic Search

By choosing the cryogenic distillation column cascade developed at Los Alamos National Laboratory, the effects of helium on separation characteristics of the columns are analyzed in a probable case of input and output specifications. Column (2) is mainly affected by the presence of helium. If the helium percentage in the raw fuel input is 1%, the column performance can be

Kinoshita

1984-01-01

111

Short-cut methods for the optimal design of simple and complex distillation columns  

Microsoft Academic Search

New short-cut methods providing optimal design parameters for distillation columns with simple and complex configurations including two-feed and one-feed-one-side-stream columns are presented. The methods assume constant relative volatilities and constant molar flow rates within each distillation section. The design equations are based on the Underwood equations for the calculation of minimum reflux (reboil) ratio, the analytical formulations of the distillation

Chafika Adiche; Alfons Vogelpohl

2011-01-01

112

A novel cross-flow cascade packed column design and simulation  

SciTech Connect

This paper develops a novel cross-flow cascade packed column. The column has a smaller width of packing in the direction of the gas flow and a bigger area for gas flow compared with a conventional cross-flow device with identical column diameter, stage height, and cross-sectional area for the irrigating liquid flows. The performance comparisons of the novel cross-flow cascade packed column with a countercurrent packed column for stripping ethanol from water indicate that the gas-phase pressure drop per theoretical stage in the novel cross-flow column is significantly lower than that in a countercurrent packed column operation under identical conditions. A methodology is developed for modeling the novel nine-stage cross-flow cascade packed column by using the number of transfer unit technique. This method is demonstrated by experimental data on ethanol-water.

Chen, F.; Zhou, R.; Duan, Z.; Liu, Y. [Tsinghua Univ., Beijing (China). Dept. of Chemical Engineering

1999-08-01

113

Comparison of parameters for fine preparative separation of binary mixtures by liquid chromatography on long packed columns and short packed columns included in a recycling scheme  

Microsoft Academic Search

Based on theoretical analysis and calculations, we have compared the parameters for fine preparative separation of binary mixtures by the method of liquid chromatography (LC) on long packed columns and short packed columns included in a recycling scheme. We have established that when the efficiency and separation capacity of the compared systems are the same (separation factor a=1.01425), for identical

M. P. Zabokritskii; V. V. Landau; V. P. Chizhkov

1990-01-01

114

The product composition regions of azeotropic distillation columns. 2. Separability in two-feed columns and entrainer selection  

Microsoft Academic Search

A method to assess the product composition regions for distillation of ternary mixtures in single-feed distillation columns, introduced in the first paper of this series, is generalized to account for the effect of introducing multiple feeds of different trays. The method relies on so-called fixed point curves which are trajectories in the compositions space. These trajectories describe the possible compositions

Oliver M. Wahnschafft; Arthur W. Westerberg

1993-01-01

115

Hydrodynamics of a packed countercurrent column for the gas extraction  

SciTech Connect

The hydraulic capacity of a countercurrent column with gauze packing was examined at pressures between 8 and 30 MPa and temperatures between 313 and 373 K. The systems used were water + carbon dioxide, aqueous surfactant solution + carbon dioxide, and Toco, a substance whose physical properties are roughly similar to those of {alpha}-Tocopherol + carbon dioxide. A distinctive change in the flooding mechanisms from liquid layer flooding to bubble column flooding was observed. The different liquids, water and Toco, showed the same flooding behavior, indicating that the influence of the density on the flooding behavior prevails over the influence of any other physical property of the liquid. The foamability of the surfactant solution decreased significantly with increasing pressure--its influence on the flooding behavior could not be proved. The liquid holdup ranged between 2% and 6%. The dry pressure drop adhered to the Ergun equation.

Stockfleth, R.; Brunner, G.

1999-10-01

116

Axial development and radial non-uniformity of flow in packed columns  

Microsoft Academic Search

Flow inhomogeneity and axial development in low-pressure chromatographic columns have been studied by magnetic resonance imaging velocimetry. The columns studied included (a) an 11.7-mm I.D. column packed with either 50 ?m diameter porous polyacrylamide, or 99 or 780 ?m diameter impermeable polystyrene beads, and (b) a 5-mm I.D. column commercially packed with 10 ?m polymeric beads. The packing methods included

Karthik Raghavan; Stephen J Gibbs

2002-01-01

117

A design method for internal heat integrated distillation columns (iHIDiCs)  

Microsoft Academic Search

Distillation of close-boiling mixtures, such as propylene-propane and ethyl benzene-styrene systems, is an energy intensive process. Vapor recompression (VRC) techniques and heat pumping-assisted columns have been adopted for such applications for their high potential of energy savings. In direct vapor recompression columns, the vapor leaving the top of the distillation column is compressed and then it is condensed in the

Mamdouh Gadalla; Zarko Olujic; Laureano Jiménez Esteller; Gonzalo Guillén-Gosálbez

2007-01-01

118

The Production of Electrochromatography Capillary Columns Using Gas Pressure Powered Dry-Packing Method  

Microsoft Academic Search

This paper introduces a dry-packing method of producing packed capillaries for using in capillary electrochromatography (CEC) or microbore HPLC. Several C18 packing materials with different particle size are studied. We compared the two methods of dry-packing and slurry-packing. The former yields analogous or better efficiency with a simpler apparatus using a shorter packing time. Besides, the columns are very stable

Changqiao Zhang; Chenfu Zhu; Xiuli Lin; Yunhe Wei

2003-01-01

119

A novel process to separate submicron particles from gases — a cascade of packed columns  

Microsoft Academic Search

A novel process using a cascade of packed columns to separate submicron particles from gases with high efficiency is presented. The process is based on the enlargement of the submicron particles by heterogeneous condensation. The particle enlargement as well as the collection of the droplets is achieved in the packed columns. Each column of the cascade is trickled with water

S Heidenreich; U Vogt; H Büttner; F Ebert

2000-01-01

120

Rolled, continuous stationary phase columns from textile fabrics: Optical packing and protein separation  

Microsoft Academic Search

Rolled, continuous stationary phases were constructed by tightly rolling and packing a whole piece of textile woven fabric into a chromatography column. Columns packed in this manner possess important features such as low intraparticle mass transfer and high pressure endurance. These properties, as reflected by a reduction of residence time within a column, show promise in decreasing protein purification costs

Chenghong Li

2001-01-01

121

Techniques for Packing High-Performance Liquid Chromatographic Columns with Porous Microparticles.  

National Technical Information Service (NTIS)

Liquid chromatography columns were packed under pressure by a slurry packing technique using carbon tetrachloride as the dispersing agent. The stationary phases used were the silica gels Lichrosorb SI 60 and SI 100 and Partisil and the aluminas Lichrosorb...

B. Cog C. Gonnet J. L. Rocca

1975-01-01

122

Startup of distillation columns using profile position control based on nonlinear wave model  

SciTech Connect

Startup of distillation columns is a very challenging control problem because of its strong nonlinearity and a wide operating range during the transient period. A nonlinear wave model captures the essential dynamic behavior of the distillation process so that it is possible to deal with the difficulties encountered during startup operation. This paper is concerned with the startup of distillation systems using nonlinear wave model based control developed by Han and Park. This control scheme uses profile positions as controlled variables and is based on the nonlinear wave model by Hwang and generic model control scheme by Lee and Sullivan. It can be applied to a binary or a multicomponent distillation system that can be represented as a pseudobinary. The proposed control scheme is shown by simulation studies to provide a safe and economic startup operation not only for dual composition control of a simple distillation column but also for a complex distillation configuration.

Han, M.; Park, S. [Chungnam National Univ., Taejon (Korea, Republic of). Chemical Engineering Dept.]|[Korea Advanced Inst. of Science and Technology, Taejon (Korea, Republic of). Chemical Engineering Dept.

1999-04-01

123

Thermodynamically equivalent distillation schemes to the Petlyuk column for ternary mixtures  

Microsoft Academic Search

Thermally coupled distillation sequences for ternary separations have been shown to provide significant energy savings with respect to the conventional direct and indirect distillation sequences. Although the Petlyuk column is generally more efficient than the other thermally coupled schemes, its structure creates potential operating problems because of the bi-directional vapour interconnecting streams. In this paper, second law calculations were performed

Salvador Hernández; Juan Gabriel Segovia-Hernández; Vicente Rico-Ramírez

2006-01-01

124

A generalized model for distillation columns—I Model description and applications  

Microsoft Academic Search

AM-A generalized model for the dynamic simulation of distillation columns is presented. The model allows the solution of a wide variety of problems, from open- and closed-loop responses of single (and multiple) columns to operability studies (of feed changeover and start-up operations) and column instability studies (effect of plate hydraulics during transient operations). Results are given for single columns (including

R. GANI; I. T. CAMERONS

1986-01-01

125

Internal heat integrated distillation columns (iHIDiCs)—New systematic design methodology  

Microsoft Academic Search

Distillation of close-boiling mixtures, such as propylene–propane and ethyl benzene–styrene systems, is an energy intensive process. Vapor recompression techniques and heat pumping-assisted columns have been adopted for such applications for their high potential of energy savings. In direct vapor recompression columns, the vapors leaving the top of the column are compressed, and in the reboiler of the same column, these

Mamdouh A. Gadalla

2009-01-01

126

Heat and mass transfer model approach to optimum design of cryogenic air separation plant by packed columns with structured packing  

Microsoft Academic Search

A process simulator for design of a cryogenic air separation plant by packed columns with structured packing was developed by use of our heat and mass transfer model. The heat and mass transfer rates were estimated by correlations which were proposed in our previous work (J. Chem. Eng. Japan 33 (2000) 245). Comparison of the predicted separation performance of a

Nobuaki Egoshi; Hiroshi Kawakami; Koichi Asano

2002-01-01

127

Assessing Safety in Distillation Column Using Dynamic Simulation and Failure Mode and Effect Analysis (FMEA)  

NASA Astrophysics Data System (ADS)

Safety assessment becomes an important activity in chemical industries since the need to comply with general legal requirements in addition to meet safer plant and profit. This paper reviews some most frequently causes of distillation column malfunction. First, analysis of case histories will be discussed for providing guidelines in identifying potential trouble spots in distillation column. A dynamic simulation for operational failure is simulated as the basis for assessing the consequences. A case study will be used from a side stream distillation column to show the implementation of the concept. A framework for assessing safety in the column is proposed using Fault Mode and Effect Analysis (FMEA). Further, trouble-free operation in order to reduce the risk associated with column malfunction is described.

Werner, Suhendra; Fred, Witt; Compart

128

Towards further internal heat integration in design of reactive distillation columns—Part IV: Application to a high-purity ethylene glycol reactive distillation column  

Microsoft Academic Search

In the first three papers of this series, it has been shown that strengthening internal heat integration within a reactive distillation column involving reactions with high thermal effect is really effective for the reduction of utility consumption and capital investment besides the improvement in process dynamics and operation. One important issue that remains unstudied so far is the influences of

Fanghong Zhu; Kejin Huang; Shaofeng Wang; Lan Shan; Qunxiong Zhu

2009-01-01

129

The art and science of forming packed analytical high-performance liquid chromatography columns  

Microsoft Academic Search

Columns of packed particles still are the most popular devices for high-performance liquid chromatography (HPLC) separations because of their great utility, excellent performance and wide variety. However, the forming of packed beds for efficient, stable columns traditionally has been an art where the basics of how to form optimum beds generally was not well understood. The recent development of monolith

J. J. Kirkland; J. J. DeStefano

2006-01-01

130

Influence of liquid redistributors on the mass-transfer efficiency of packed columns  

Microsoft Academic Search

In industrial mass-transfer columns liquid distributors and redistributors are used to mix the liquid after a certain random packing or structured packing height before it is applied to the next bed. The purpose of this is to counter a possible deterioration of the mass-transfer efficiency along the height of the column as a result of wall flow tendency of the

M. Schultes

2000-01-01

131

Removal of Lead in a Fixed-Bed Column Packed with Activated Carbon and Crab Shell  

Microsoft Academic Search

Crab shell particles (Protunus trituberculatus) and activated carbon (Norit 0,8 SUPRA) were used as packing materials in a fixed-bed column. When 1 g crab shell was added in a column packed with 10 g activated carbon, breakthrough occurred at 1500 bed volumes as compared to 380 bed volumes for 10 g activated carbon only. The addition of crab shell particles

Moo-Yeal Lee; Hyun-Jae Shin; Sung Ho Lee; Jong Moon Park; Ji-Won Yang

1998-01-01

132

Direct-contact gas-liquid heat transfer in a packed column  

SciTech Connect

Heat transfer coefficients were measured for the cooling of water or a nonvolatile oil by direct contacting in a packed column. The column contained random packing, and separate measurements were made on a number of different types of packing elements. Volumetric coefficients were correlated by empirical equations as well as by relationships based on a heat transfer/mass transfer analogy. The latter approaches proved effective, and it is concluded that the large body of information on packed column mass transfer rates can be directly useful for predicting heat transfer coefficients for direct-contact exchangers.

Huang, C.C.; Fair, J.R.

1989-01-01

133

APSA: A new cape tool for design and troubleshooting of azeotropic distillation columns  

Microsoft Academic Search

The azeotrope pressure sensitivity analysis (APSA) provides a dependence of compositions and temperatures of azeotropes with respect to changes in pressure. This information can be of critical importance in the design and troubleshooting of real distillation columns, especially when there is a substantial pressure drop in the column. In some cases, this can lead to a switch in topology of

Stanislaw K. Wasylkiewicz

2004-01-01

134

The Influence of Heat Transfer Irreversibilities on the Optimal Performance of Diabatic Distillation Columns  

Microsoft Academic Search

A distillation column with the possibility of heat exchange on every tray (a fully diabatic column) is optimized in the sense of minimizing its total entropy production. This entropy production counts the interior losses due to heat and mass flow as well as the entropy generated in the heat exchangers. It is observed that the optimal heating distribution, i.e. the

M. Schaller; K. H. Hoffmann; R. Rivero; B. Andresen; P. Salamon

2002-01-01

135

Implementation of a reactive dividing wall distillation column in a pilot plant  

Microsoft Academic Search

Based on the knowledge regarding steady state design, optimization and control obtained by using Aspen Plus and Aspen Dynamics process simulators, we have designed and implemented a reactive dividing wall distillation column (DWDC). The column can be used to carry out the equilibrium reaction between ethanol and acetic acid to produce ethyl acetate and water catalyzed by sulfuric acid. The

Rodrigo Sandoval-Vergara; Fabricio Omar Barroso-Muñoz; Héctor Hernández-Escoto; Juan Gabriel Segovia-Hernández; Salvador Hernández; Vicente Rico-Ramírez

2008-01-01

136

Steady States of the Reactor–Distillation Column System for an A + B ? C Reaction  

Microsoft Academic Search

The steady states of the reactor-distillation column recycle system are analyzed for the reaction A + B ? C at various feed compositions. The analysis is performed for an infinite column operated at total reflux. If the lightest component, A, is in excess, the complete conversion of the medium-boiling component, B, is impossible. If reactant B is in excess, there

S. L. Nazanskii; A. V. Solokhin; S. A. Blagov; V. S. Timofeev

2001-01-01

137

Physical characterization and evaluation of HPLC columns packed with superficially porous particles.  

PubMed

Two HPLC columns packed with superficially porous packing material (Kinetex™ 1.7 and 2.6 ?m C18 particles) were evaluated in terms of their physical properties and performance characteristics. These columns were compared to a column packed with a sub-2 ?m totally porous material and to a Halo(TM) column packed with 2.7 ?m C18 superficially porous packing. The columns packed with superficially porous particles displayed a comparably narrower size distribution, which is narrower than the distribution of the totally porous sub-2 ?m particles. Physical characteristics of the Kinetex™ particles were evaluated in terms of surface area, pore diameter, and specific pore volume. Total, external, internal, and shell porosities among the four different columns were evaluated and compared. The specific permeability for the Kinetex™ columns showed values close to those predicted by the Kozeny-Carman equation. All four columns were evaluated in terms of their chromatographic performance and compared using the Knox equation. The columns packed with the 2.6 and 2.7 ?m superficially porous materials showed reduced plate heights below 2, whereas the sub-2 ?m particles showed values of 2.2 and above. PMID:20806238

Baker, Jared S; Vinci, John C; Moore, Amber D; Colón, Luis A

2010-09-01

138

Development of a mathematical model of a packed column for benzene removal from salt solutions  

SciTech Connect

A mathematical model of a packed column was developed to describe the removal of benzene from radioactive salt solutions at the Savannah River Site. The model was developed from existing, generalized mass transfer correlations for randomly dumped packing, and the correlations were adapted for structured packing. Thermophysical data specific to the solutions of interest were incorporated into the model. Verification of the code was completed using operating data from stripping columns at other locations.

Georgeton, G.K.

1989-12-31

139

Development of a mathematical model of a packed column for benzene removal from salt solutions  

SciTech Connect

A mathematical model of a packed column was developed to describe the removal of benzene from radioactive salt solutions at the Savannah River Site. The model was developed from existing, generalized mass transfer correlations for randomly dumped packing, and the correlations were adapted for structured packing. Thermophysical data specific to the solutions of interest were incorporated into the model. Verification of the code was completed using operating data from stripping columns at other locations.

Georgeton, G.K.

1989-01-01

140

Low-order dynamic modeling of cryogenic distillation columns based on nonlinear wave phenomenon  

Microsoft Academic Search

A low-order dynamic model based on nonlinear wave theory is developed for a cryogenic distillation column used for nitrogen purification. By tracking the wave front propagating through the column, a simple mathematical model capable of describing the essential column dynamics is derived. The combined reboiler\\/condenser system is modeled using rigorous mass and energy balances. The low-order model is compared with

Guang-Yan Zhu; Michel A. Henson; Lawrence Megan

2001-01-01

141

LIQUID PHASE DISPERSION IN A PACKED COLUMN WITH COUNTERCURRENT TWO-PHASE FLOW  

Microsoft Academic Search

The axial dispersion in the liquid phase through a packed column was studied with air-water flowing counter-currently in a 10.16?cm inside diameter column packed with Percelain Raschig rings. The dispersion coefficient or Peclet number and mean residence time were calculated by comparing the moments of the responses measured at two points along the column. Effects of gas flow rate (0-0.37

DAE KI CHOE; WON KOOK LEE

1985-01-01

142

Effect of the column length on the characteristics of the packed bed and the column efficiency in a dynamic axial compression column  

Microsoft Academic Search

The axial homogeneity of preparative-scale chromatography columns was studied by measuring the overall properties of similar columns differing only by their lengths. The properties investigated were the packing density, the external porosity, the permeability and the column efficiency. Two different materials were used, one made of large, irregular silica particles compressed under either a high or a low degree of

Joon-Ho Koh; Georges Guiochon

1998-01-01

143

Mass transfer to the wall of a packed and unpacked bubble column operating with Newtonian and non-Newtonian liquids  

Microsoft Academic Search

Mass transfer to the wall of a bubble column is examined, focusing on the influence of the liquid viscosity. The effect of introducing structured packing in the column is analysed by comparing results for the empty column with those of packed column at similar operating conditions. Visual observation allowed detecting of flow transition in the empty column with non-Newtonian fluids;

R. Khamadieva; U. Böhm

2006-01-01

144

Hydrodynamic impact of particle shape in slurry packed liquid chromatography columns.  

PubMed

We report on a series of flow velocity and efficiency profiles, which were measured across the cross section of preparative chromatographic columns packed with different stationary phase materials using computed tomography. It is shown that this non-invasive technique is very useful for visualization of the inner part of a packed column and measurement of the spatial resolved column packing properties. For evaluation of the influence of the particle shape on the velocity distribution and column performance, irregular and spherical reversed phases were studied in detail. The results showed a decreasing velocity towards the column wall most certainly due to a lower permeability. This effect was much less pronounced in the case of spherical particles, indicating a more homogenous packing structure. The influence of the column packing pressure, as a possible measure for improvement of the packing homogeneity was also studied. It was shown that under the same packing conditions spherical particles always lead to a more homogeneous packing. The overall results of this work contribute to the origin of the fact that spherical material is superior to irregular one from the hydrodynamic point of view. PMID:19524930

Lottes, Florian; Arlt, Wolfgang; Minceva, Mirjana; Stenby, Erling H

2009-06-06

145

Performance of tapered column packed-bed bioreactor for ethanol production  

Microsoft Academic Search

A tapered column type of bioreactor system packed with immobilized Saccharomcyes cerevisiae was used to study the bioreactor performance as a function of design and operating variables. The performance of tapered column bioreactor system was found to be better than that of the conventional cylindrical column reactor system for the ethanol fermentation. The new bioreactor design alleviated problems associated with

Haluk Hamamci; Dewey D. Y. Ryu

1987-01-01

146

Effect of Dissolved Oxygen on Removal of Nitrate in Laboratory Columns Packed with Solid Organic Carbon  

Microsoft Academic Search

Effect of dissolved oxygen (DO) on removal of nitrate from groundwater was studied in laboratory columns packed with solid organic carbon. DO was measured at different height in the column to clarify that there were conditions, aerobic and anoxic, in the column. The paper reactor was not more sensitive than the cotton reactor in the DO effect. the cotton denitrification

Jin Zanfang; Jin Mantong; Li Feili; Pan Zhiyan; Wan Yu; Chen Yingxu; Huang Yanhong

2011-01-01

147

Sintered octadecylsilica as monolithic column packing in capillary electrochromatography and micro high-performance liquid chromatography.  

PubMed

Fused-silica capillaries were packed with porous 6-microns octadecylated silica microspheres and subjected to thermal treatment in order to obtain a column with porous silica based monolithic packing. After sintering, the monolithic packing was reoctadecylated in situ with dimethyloctadecylchlorosilane. The mechanical strength and stability of the monolithic column were significantly greater than those of conventional columns packed with particulate stationary phase. The performance of the columns was evaluated in both mu-HPLC and capillary electrochromatography (CEC) of small aromatic compounds and polycyclic aromatic hydrocarbons with 10 mM borate, pH 8.0, in acetonitrile-water mixtures as the mobile phase. Since no untoward bubble formation was observed, CEC could be performed in a CZE unit without the need for pressurizing the monolithic column. The plate efficiency of the monolithic column was similar to that of columns freshly packed with the same particles and was always higher in the CEC than in the mu-HPLC under otherwise identical conditions. The electrosmotic flow (EOF) velocity increased with the acetonitrile content of the eluent in open fused-silica capillaries with octadecylated innerwall and in columns packed with sintered octadecylsilica. In contradistinction, the EOF velocity decreased with the organic strength of the eluent in raw fused-silica capillaries. The opposite trend is attributed to the different effect of changing organic modifier concentration on the accessibility of silanol groups at the raw and octadecylated silica surfaces. PMID:9646482

Asiaie, R; Huang, X; Farnan, D; Horváth, C

1998-05-15

148

Development of a Fritless Packed Column for Capillary Electrochromatography-Mass Spectrometry  

PubMed Central

A novel procedure was developed for the fabrication of a fritless packed column for the coupling of capillary electrochromatography (CEC) to mass spectrometry (MS). The process involved the formation of internal tapers on two separate columns. Once the internal tapers are formed and the columns are packed, the untapered ends of each column were joined together by a commercially available connector. Several advantages of the fritless columns are described. First, the design used here eventually eliminates the need for any frits thus reducing the possibility of bubble formation seen with fritted packed columns. In addition, this is the first report in which the internal tapers are formed at both the inlet and outlet column ends making the fritless CEC-MS column more robust compared to only one report with externally tapered counterparts. Second, a comparison of internally tapered single frit packed CEC-MS (previously developed in our laboratory) column versus fritless CEC-MS column reported here shows that the latter provides better efficiency, suggesting no dead volume with equally good sensitivity and chiral resolution of (±)-aminoglutethimide. The fritless column procedure is universal and was used to prepare a series of columns with a variety of commercially available packing material (mixed mode strong cation exchange, SCX; mixed mode strong anion exchange, SAX; C-18) for the separation and MS detection of short chain non-chromophoric polar amines, long chain nonchromophic anionic surfactant as well as oligomers of non-chromophoric non-ionic surfactants, respectively. The fritless columns showed good intra-day repeatibility and inter-day reproducibility of retention times, chiral and achiral resolutions and peak areas. Very satisfactory column-to-column and operator-to-operator reproducibility was demonstrated.

Bragg, William; Shamsi, Shahab A.

2011-01-01

149

Development of a fritless packed column for capillary electrochromatography-mass spectrometry.  

PubMed

A novel procedure was developed for the fabrication of a fritless packed column for the coupling of capillary electrochromatography (CEC) to mass spectrometry (MS). The process involved the formation of internal tapers on two separate columns. Once the internal tapers are formed and the columns are packed, the untapered ends of each column were joined together by a commercially available connector. Several advantages of the fritless columns are described. First, the design used here eventually eliminates the need for any frits thus reducing the possibility of bubble formation seen with fritted packed columns. In addition, this is the first report in which the internal tapers are formed at both the inlet and outlet column ends making the fritless CEC-MS column more robust compared to only one report with externally tapered counterparts. Second, a comparison of internally tapered single frit packed CEC-MS (previously developed in our laboratory) column versus fritless CEC-MS column reported here shows that the latter provides better efficiency, suggesting no dead volume with equally good sensitivity and chiral resolution of (±)-aminoglutethimide. The fritless column procedure is universal and was used to prepare a series of columns with a variety of commercially available packing material (mixed mode strong cation exchange, SCX; mixed mode strong anion exchange, SAX; C-18) for the separation and MS detection of short chain non-chromophoric polar amines, long chain nonchromophic anionic surfactant as well as oligomers of non-chromophoric non-ionic surfactants, respectively. The fritless columns showed good intra-day repeatability and inter-day reproducibility of retention times, chiral and achiral resolutions and peak areas. Very satisfactory column-to-column and operator-to-operator reproducibility was demonstrated. PMID:22035695

Bragg, William; Shamsi, Shahab A

2011-10-08

150

Heat Transfer Study of Heat-Integrated Distillation Column (HIDiC) Using Simulation Techniques  

NASA Astrophysics Data System (ADS)

Separation processes is largely used in petroleum refining and alcohol industries. Distillation columns consume a huge amount of energy in industrial process. Therefore, the concept of Heat-Integrated Distillation Column (HIDiC) was studied using simulation techniques in order to overcome this drawback. In this configuration the column is composed for two concentric sections called rectifying and stripping. The heat transfer is conducted from the rectifying section (which works at higher pressure and temperature) to the stripping section (which works at lower pressure and temperature) using the heat present in the process and decreasing the energy charge required by the reboiler. The HIDiC column offers great potential to reduce energy consumption compared to conventional columns. However, the complexity of the internal configuration requires the development of rigorous works that enable a better understanding of the column operation. For this reason, techniques of simulation were used through of computational software. The current work presents a heat transfer study in a concentric stage of a HIDiC column. The results obtained by Aspen Plus and CFD simulation showed the internal heat transfer in a concentric tray as a promissory configuration in order to decrease energy consumption in distillation processes.

Pulido, Jeffrey León; Martínez, Edgar Leonardo; Wolf, Maria Regina; Filho, Rubens Maciel

2011-08-01

151

Comparison between random and structured packings for dehumidification of air by lithium chloride solutions in a packed column and their heat and mass transfer correlations  

Microsoft Academic Search

Random and structured packings were compared for their efficiency in dehumidification of air in a packed column using lithium chloride solutions. Experiments were conducted with cross corrugated cellulose and poly(vinyl chloride) (PVC) structured packings, and the results were compared with the data previously obtained for polypropylene Flexi rings and ceramic Berl saddles as random packings. The heat and mass transfer

Tsair-Wang Chung; Tushar K. Ghosh; Anthony L. Hines

1996-01-01

152

Retardation Characteristics of Radionuclides in Geologic Media through Batch and Packed Column Experiments.  

National Technical Information Service (NTIS)

Batch and packed column experiments are performed to investigate the retardation characteristics of radionuclide,i.e, Cs-137 in geologic media. In batch experiment, the effects of important parameters on the sorption of radionuclide in geologic media, suc...

H. H. Park K. W. Han P. S. Han J. O. Lee C. K. Park

1988-01-01

153

The effects of thermodynamic data on the design and operation of distillation columns  

Microsoft Academic Search

The relative importance of various physical properties for distillation-column design and operation is classified. Vapor-liquid equilibrium data have a dominant effect. It is possible to quantify the effect of errors of relative volatility on the uncertainty of the number of stages required for a given simple binary separation problem by using the simplest, so-termed short-cut methods of column design, because

Zeck

1993-01-01

154

Liquid dispersion, gas holdup and frictional pressure drop in a packed bubble column at elevated pressures  

Microsoft Academic Search

The gas holdup, frictional pressure drop and liquid dispersion have been investigated in a packed bubble column at elevated pressures for the air–water system. The bubble column, which had an internal diameter of 0.15m and which was packed with 15mm plastic Pall rings was operated in the semibatch mode. The operating pressures ranged from 0.1 to 0.66MPa. It was found

Peter Therning; Anders Rasmuson

2001-01-01

155

Flooding and mass transfer in Goodloe-packed columns, Part 2. [HTGR  

Microsoft Academic Search

Krypton gas is recovered from HTGR off-gas streams by countercurrent absorption in liquid carbon dioxide. Goodloe stainless steel wire mesh packing was chosen for the absorption columns since the process operates at -20°C and about 20 atm pressure. Flooding points and an overall mass transfer coefficient for Goodloe-packed columns were determined with a carbon dioxide-air-water system for 6.4 and 15.2-cm-ID

J. S. Ayala; B. W. Brian; A. C. Sharon

1977-01-01

156

Impacts of Bleaching and Packed Column Steam Refining on Cocoa Butter Properties  

Microsoft Academic Search

Natural and alkalized cocoa butters were bleached and subsequently steam refined in a continuous packed column at temperatures\\u000a ranging between 160 and 220 °C. None of the processes evaluated gave rise to any detectable formation of trans fatty acids, interesterification or polymerization. For the pressures and steam injection rates used, packed-column steam\\u000a refining required a minimum temperature of 170 °C to achieve

José Vila Ayala; Gijs Calliauw; Imogen Foubert; Koen Dewettinck; Bill Dyer; Wim De Greyt

2007-01-01

157

ABSORPTION OF NO AND SO2 IN FE(II)EDTA SOLUTIONS II. PACKED COLUMN SIMULATION  

Microsoft Academic Search

Two methods were applied in simulating the height of a packed column required for the removal of NO and SO2 by absorption into Fe(II)-EDTA solutions. The first method used a double-stirred cell to simulate a packed column by matching the gas- and liquid-phase mass transfer coefficients of the two device. The second method used the differential mass balance including reaction

SIU-MING YIH; CHYI-WOEI LII

1988-01-01

158

Micro-columns packed with Chlorella vulgaris immobilised on silica gel for mercury speciation  

Microsoft Academic Search

A method has been developed for mercury speciation in water by using columns packed with Chlorella vulgaris immobilised on silica gel. The method involves the retention of CH3Hg+ and Hg2+ in micro-columns prepared by packing immobilised algae in polypropylene tubes, followed by selective and sequential elution with 0.03 and 1.5M HCl for CH3Hg+ and Hg2+, respectively. The adsorption capacity of

P. Tajes-Martínez; E. Beceiro-González; S. Muniategui-Lorenzo; D. Prada-Rodríguez

2006-01-01

159

Operation of a batch distillation column with a middle vessel: experimental results for the separation of zeotropic and azeotropic mixtures  

Microsoft Academic Search

Batch distillation in a column with a middle vessel can avoid many of the disadvantages associated with the regular batch distillation processes. In this paper, we present an experimental investigation of the separation of a zeotropic ternary mixture via total reflux operation and of the separation of an azeotropic binary mixture via batch-wise extractive distillation. Moreover, the results obtained for

M. Warter; D. Demicoli; J. Stichlmair

2004-01-01

160

Packed-Bed Column Flotation of Fine Coal. Part I. Laboratory Tests and Flotation Circuit Design  

Microsoft Academic Search

An advanced packed column (or static tube) flotation system developed at Michigan Technological University offers the potential for sharp separation of fine coal particles from mineral matter and can be readily incorporated into practice for efficient coal processing at reduced costs. The essential element of the system is the packed-bed cell design in combination with a controlled dispersion reagent scheme.A

D. C. YANG

1990-01-01

161

Surface association of motile bacteria and apparent tortuosity values in packed column experiments  

Microsoft Academic Search

Mathematical models used previously to obtain transport parameters from experimental investigations of bacterial transport in packed columns by Olson et al. (2005) yielded apparent tortuosity values that were an order of magnitude higher than expected for packed beds. The association of motile bacteria with solid surfaces of porous media, due to their swimming, contributed to the large apparent tortuosity values

Karthik Narayanaswamy; Roseanne M. Ford; James A. Smith; Erik J. Fernandez

2009-01-01

162

Evaluation of multi-walled carbon nanotubes as gas chromatographic column packing  

Microsoft Academic Search

Purified multi-walled carbon nanotubes (PMWCNTs), activated charcoal and graphitized carbon black (Carbopack B) were used as column packing materials to compare their separation ability and other gas chromatographic behavior for aromatic hydrocarbons, alkanes, halogenated hydrocarbons, alcohols, ketones, esters, and ethers. The results show that PMWCNTs can be an excellent gas chromatographic packing material. Compared to Carbopack B with the same

Quanlong Li; Dongxing Yuan

2003-01-01

163

Optical resolution HPLC column packings carrying penicillin sulfoxide nucleus. Part I. Polymer synthesis and resolution efficiency  

Microsoft Academic Search

Polyacryl or methacrylamides bearing penicillin sulfoxide skeleton were synthesized. The obtained polymers were coated onto macroporous silica gel and the properties of the prepared packings were investigated. The column packing comprising poly(benzyl 1-oxo-6-methacrylaminopenicillanate) was found to resolve various aromatic racemates.

Y. Saotome; T. Miyazawa; T. Endo

1989-01-01

164

Fused-core, sub-2 microm packings, and monolithic HPLC columns: a comparative evaluation.  

PubMed

Three different HPLC column technologies (i.e., monolith, fused-core particles, and sub-2 microm particles) were evaluated, comparing van Deemter plots, speed of analysis, back pressure, and mobile phase consumption. Very high linear velocities (approximately 12 mm/s) were achieved with the monolithic column using modest pressure (110 bar) at the expense of high mobile phase consumption. The minimum plate height of the monolith was similar to that of a 3 microm-particle packed column (i.e., h = 8 microm), operated at optimal linear velocities; the monolithic column showed substantially lower mass transfer dependence, however. The 2.7 microm fused-core packing material yielded efficiencies closer to the sub-2 microm material than to the 3 microm-particle packed column and could be operated at high flow rates. The fused-core column was able to achieve linear velocities similar to those attained on the sub-2 microm column, staying below 620 bar instead of almost near 1030 bar required by the sub-2 microm material. The lack of pH stability of the monolithic column prevented its use to separate basic compounds (i.e., tricyclic antidepressants) at high pH. Best separation of these components at high pH was achieved using the column packed with 1.7 microm hybrid material. PMID:19603389

Brice, Richard W; Zhang, Xin; Colón, Luis A

2009-08-01

165

Integration of reaction and separation in a batch extractive distillation column with a middle vessel  

Microsoft Academic Search

In this work, the integration of reaction and separation in a batch extractive distillation column with a middle vessel\\/reactor is analyzed for azeotrope-forming mixtures. This equipment configuration has the potential to promote complete conversion of reactants and therefore, the main process characteristics are investigated. A mixture showing several azeotropes and suffering an esterification reaction was selected as an academic example.

José Espinosa

2002-01-01

166

Control strategies analysis for a batch distillation column with experimental testing  

Microsoft Academic Search

The dynamic nature and the non-linear behaviour of batch distillation equipment pose challenging control system design when products of constant purity are to be recovered. Several alternative column configurations and operating policies have been studied. However, issues related to the on-line operation of such process have not been properly addressed. The present work describes the investigation with experimental verification of

Ana M Frattini Fileti; Sandra L Cruz; João A. F. R Pereira

2000-01-01

167

Prediction of the Trayed Distillation Column Mass-Transfer Performance by Neural Networks  

Microsoft Academic Search

The sieve-tray distillation column mass-transfer efficiency was successfully modeled using a neural network. The database developed by Garcia and Fair (Ind. Eng. Chem. Res. 2000, 39, 1809) was utilized to train and validate the neural network model. The results indicate that, if the system is similar to the data used to train the neural network, the purely empirical neural network

Eric Olivier; R. Bruce Eldridge

2002-01-01

168

Excess Methanol Recovery in Biodiesel Production Process Using a Distillation Column: A Simulation Study  

Microsoft Academic Search

This paper presents an ASPEN PLUS TM simulation study for excess methanol recovery in continuous biodiesel production process using a distillation column. The feedstock used for biodiesel production was Triolein containing 15% free fatty acid (Oleic Acid). The special attention was devoted to the e ect of di erent alcohol to oil ratio and important design and operating parameters of

Bipro Ranjan Dhar; Kawnish Kirtania

2009-01-01

169

Control of high-purity distillation column using a nonlinear wave theory  

Microsoft Academic Search

A new model-based controller for profile position control of high-purity distillation columns is presented. The controller has been developed by incorporating nonlinear wave model into the generic model control framework. An observer based on the nonlinear wave theory is also proposed to determine the profile position. The performance of the nonlinear control scheme has been tested in simulation experiments of

Myungwan Han

1993-01-01

170

Transient Response of a Distillation Column Plate. Part I. Theory: Five Models and Their Fourier Transforms  

Microsoft Academic Search

Five models are used to describe the transient behavior of the liquid composition on a distillation column bubble cap tray when the liquid composition entering the tray undergoes a composition transient. The assumptions required for the models are discussed. The equations are transformed by the Laplace operator, and the solutions are left in the frequency response form for comparison with

Chester N. Sittel Jr; Gerald T. Fisher

1973-01-01

171

Design considerations for packed columns removing manganese from mining seepage  

Microsoft Academic Search

A field study during 1986 at a reclaimed strip mine are showed that column technology had promise as a low-maintenance, low-cost method of manganese removal and, therefore, design and operation data were needed before proceeding with a pilot plant scale operation. During 1987, three columns were operated in the laboratory to obtain needed design information. Removal efficiency was assessed as

J. A. Gordon; N. S. Chuang; R. P. Wallace

1989-01-01

172

Interfacial areas and gas hold-ups in bubble columns and packed bubble columns at elevated pressures  

Microsoft Academic Search

Interfacial areas and gas hold-ups have been determined at pressures up to 1.85 MPa in a bubble column with a diameter of 85.5 mm and for superficial gas velocities between 1 and 10 cm s?1. In some experiments the bubble column was packed with glass cylinders of length 5.0 mm and diameter 4.0 mm. The interfacial areas were determined by

M. H. Oyevaar; T. de la Rie; Sluijs van der C. L; K. R. Westerterp

1989-01-01

173

Very Short Micro-HPLC Column Packed with Three-Micron Particles  

Microsoft Academic Search

The chromatographic potential of very short fused-silica column (30 mm length) packed with 3-?m particles has been investigated. The results indicate that this kind of micro-column has high applicability for a rapid identification of several samples. This technique also meets the recent demands in HPLC, as low solvent consumption and faster analysis time.

Kiyokatsu Jinno

1984-01-01

174

A particle size distribution analysis of used HPLC column packing material  

Microsoft Academic Search

Particle size distribution analysis and scanning electron microscopy (SEM) were carried out on eight used HPLC columns containing either irregular silica based, spherical silica based or spherical polymer based packing material. Particle size distributions of the used irregular silica based columns were at least bimodat at the outlet ends and either biomodal or log-normal at the inlet ends with regular

T. D. Wilson; D. M. Simmons

1993-01-01

175

Characterisation of RPLC columns packed with porous sub-2 microm particles.  

PubMed

Eight commercially available sub-2 microm octadecyl silane columns (C18 columns) have been characterised by the Tanaka protocol. The columns can be grouped into two groups that display large differences in selectivity and peak shape due to differences in hydrophobicity, degree of surface coverage and silanol activity. Measurements of particle size distributions were made using automated microscopy and electrical sensing zone measurements. Only a weak correlation could be found between efficiency and particle size. Large differences in column backpressure were observed. These differences are not related to particle size distribution. A more likely explanation is differences in packing density. In order to take full advantage of 100-150 mm columns packed with sub-2 microm particles, it is often necessary to employ not only an elevated pressure but also an elevated temperature. A comparison between columns packed with sub-2, 3 and 5 microm versions of the same packing indicates potential method transferability problems for several of the columns due to selectivity differences. Currently, the best alternative for fast high-resolution LC is the use of sub-2 microm particles in combination with elevated pressure and temperature. However, as shown in this study additional efforts are needed to improve transferability as well as column performance. PMID:17639515

Petersson, Patrik; Euerby, Melvin R

2007-08-01

176

RAPID PROCEDURE FOR PREPARATION OF SUPPORT-BONDED CARBOWAX 20M GAS CHROMATOGRAPHIC COLUMN PACKING  

EPA Science Inventory

A rapid and simplified procedure is described for the preparation of support-bonded Carbowax 20M gas chromatographic column packings. The heat treatment process is carried out in a 100-ml volumetric pipet in a conventional gas chromatograph. Using the described procedure, column ...

177

Development of a chiral host system tunable via changes in a 2 1-column packing structure  

Microsoft Academic Search

A tunable chiral host system was developed by the self-assembly of a chiral 21-column structure formed from (1R,2R)-1,2-diphenylethylenediamine and dicarboxylic acid. This host system can include guest molecules by changing the packing of a chiral 21-column enantioselectively.

Yoshitane Imai; Kakuhiro Kawaguchi; Tomohiro Sato; Reiko Kuroda; Yoshio Matsubara

2006-01-01

178

Evaluation of columns packed with shell particles with compounds of pharmaceutical interest  

Microsoft Academic Search

The commercial C18 columns packed with sub-3?m shell particles were tested and compared to a reference UHPLC column, in terms of kinetic performance as well as selectivity, retention capability, peak shape and loading capacity. For this purpose, a set of pharmaceutically relevant molecules was selected, including acidic, neutral and basic drugs. Regarding kinetic performance, hopt values for the shell particles

Joséphine Ruta; Daria Zurlino; Candice Grivel; Sabine Heinisch; Jean-Luc Veuthey; Davy Guillarme

179

Modeling of separation process in a chromatographic column packed with porous adsorbents  

Microsoft Academic Search

The adsorption-desorption process in a chromatographic column is simulated by using a numerical method. There are several process parameters which can affect the breakthrough curves, such as adsorption and desorption rates and mass transfer coefficient between the main solution flow and the particles. Moreover, for the chromatographic columns packed with porous adsorbents, the diffusivity of adsorbates in the porous adsorbents

Georg Fieg; Yan-Ming Gao; Xing Luo

2009-01-01

180

Catalytic hydrogenation in a packed bed bubble column reactor  

Microsoft Academic Search

The cocurrent downflow contactor reactor (CDCR) has been found to give low mass transfer resistances both in slurry and packed bed catalytic operation. The hydrogenation of propan-2-ol solutions of itaconic acid in the range 100–300kPa and 20–70°C and of soyabean oil in the range 100–500kPa and 130–160°C was studied using slurry (5% w\\/w Pd\\/C) and packed bed (3% w\\/w Pd\\/Al2O3

J. M. Winterbottom; Z. Khan; A. P. Boyes; S. Raymahasay

1999-01-01

181

Evaluation of the parameters determining the performance of electrochromatography in packed capillary columns  

Microsoft Academic Search

Electrochromatography is a varient of reversed-phase liquid chromatography performed in capillary columns whereby transport of the eluent is accomplished by applying an electric field across the length of the column. Column-length restrictions arising from resistance to flow encountered with conventional pumping are absent in electrochromatography, allowing separation in capillaries packed with 1.5-?m stationary phases up to 50 cm, thus rendering

Beate Behnke; Edgar Grom; Ernst Bayer

1995-01-01

182

Binary Adsorption in a Fixed-Bed Column Packed with an Ion-Exchange Resin  

Microsoft Academic Search

A mathematical model was adopted to analyze a binary fixed-bed adsorption column packed with an ion-exchange resin. Two pairs of organic compounds, o-cresol-benzoic acid and p-chlorophenol-p-nitrophenol, were employed as the adsorbates. A modified Langmuir isotherm with interaction factors ?i was found suitable for representing the adsorption equilibrium. Scale-up of the binary adsorption column with respect to column length was effective

Run-Tun Huang; Teh-Liang Chen; Hung-Shan Weng

1995-01-01

183

Selection and Optimization Protocols for Attached Growth Biological Packed Columns.  

National Technical Information Service (NTIS)

Topics of discussion include: trade-offs, column characteristics, operating characteristics, solids handling, process selection, operating analysis, and recommendations. The objectives is to design the process to fit the biocolumn rather than to adapt the...

S. F. Roe E. B. Hanf

1982-01-01

184

The setup of an extraction system coupled to a hydrogen isotopes distillation column  

SciTech Connect

Among the most difficult problems of cryogenic distillation one stands apart: the extraction of the heavy fraction. By an optimal design of the cycle scheme, this problem could be avoided. A 'worst case scenario' is usually occurring when the extracted fraction consists of one prevalent isotope such as hydrogen and small amounts of the other two hydrogen isotopes (deuterium and/or tritium). This situation is further complicated by two parameters of the distillation column: the extraction flow rate and the hold-up. The present work proposes the conceptual design of an extraction system associated to the cryogenic distillation column used in hydrogen separation processes. During this process, the heavy fraction (DT, T{sub 2}) is separated, its concentration being the highest at the bottom of the distillation column. From this place the extraction of the gaseous phase can now begin. Being filled with adsorbent, the extraction system is used to temporarily store the heavy fraction. Also the extraction system provides samples for the gas Chromatograph. The research work is focused on the existent pilot plant for tritium and deuterium separation from our institute to validate the experiments carried out until now. (authors)

Zamfirache, M.; Bornea, A.; Stefanescu, I.; Bidica, N.; Balteanu, O.; Bucur, C. [INC-DTCI, ICSIRm. Valcea, Uzinei Street 4, Rm. Valcea (Romania)

2008-07-15

185

Properties of cattle bone powder-coated composite particles as high-performance and open column liquid chromatographic column packings  

Microsoft Academic Search

Cattle bone powder (CBP) from natural resources was employed as a protein adsorbent instead of chemically synthesized hydroxyapatite (HA). Though a small amount of impurities was detected, CBP possessed a crystallinity similar to HA. Using CBP\\/40PE prepared from CBP and polyethylene beads (40 ?m) by dry impact blending as an HPLC column packing, considerable correlation was observed between the elution

Futaba Honda; Hirotaka Honda; Masumi Koishi; Takashi Matsuno

1998-01-01

186

Column-Based Strip Packing Using Ordered and Compliant Containment  

Microsoft Academic Search

The oriented strip packing problem is very important to manufacturing industries: given a strip offixed width and a set of many (? 100) nonconvex polygons with 1, 2, 4, or 8 orientations permittedfor each polygon, find a set of translations and orientations for the polygons that places them withoutoverlapping into the strip of minimum length. Heuristics are given for two

Karen Daniels; Victor J. Milenkovic

1996-01-01

187

Effect of the packing pressure on the performance of C 18 reversed-phase liquid chromatographic columns  

Microsoft Academic Search

Early evidence has shown that HPLC columns packed with a given ODS phase give different performance, related to differences in their packing densities and external porosities. This effect was systematically studied on two groups of ten analytical (10×0.46 cm) columns packed with Kromasil and Zorbax 10 ?m spherical C18, respectively, using chloroform as the slurry solvent and methanol as the

Hong Guan-Sajonza; Georges Guiochona

1996-01-01

188

Pilot plant formaldehyde distillation: experiments and modelling  

Microsoft Academic Search

Despite their industrial importance, only few experimental studies on distillation of aqueous, methanolic formaldehyde solutions are described in the literature. In the present work, for the first time, results from pilot-scale distillation of mixtures of formaldehyde, water, and methanol are presented. The experiments were carried out in a 250mm diameter distillation column equipped with 2m Sulzer BX wire gauze packing.

K. Terelak; S. Trybula; M. Majchrzak; M. Ott; H. Hasse

2005-01-01

189

Capacity and efficiency of reactive distillation bale packing: Modeling and experimental validation  

SciTech Connect

The geometry of catalyst-containing bale packing is characterized in this paper. The calculated packing parameters (specific surface area and void fraction) are employed in conjunction with a model to predict two-phase pressure drop, maximum capacity, and height equivalent to a theoretical plate (HETP). Experimental data obtained in a 5.3-cm (2.1-in.) column, operated at total reflux, are presented for two systems (cyclohexane/n-heptane and acetone/methyl ethyl ketone) at pressures of 138 and 241 kPa (20 and 35 psia). Model predictions for pressure drop and HETP are validated with experimental data obtained under nonreactive conditions. An appropriate procedure for scaleup of HETP and pressure drop, with associated limitations, is also discussed.

Subawalla, H.; Gonzalez, J.C.; Seibert, A.F.; Fair, J.R. [Univ. of Texas, Austin, TX (United States). Separations Research Program

1997-09-01

190

Precision and Accuracy in the Determination of Organics in Water by Fused Silica Capillary Column Gas Chromotography/Mass Spectrometry and Packed Column Gas Chromatography/Mass Spectrometry.  

National Technical Information Service (NTIS)

Two general methods for the identification and measurement of organic compounds in water are compared. One method employs packed column chromatography and the other fused silica capillary column chromatography. The two gas chromatography/mass spectrometry...

J. W. Eichelberger E. H. Kerns P. Olynyk W. L. Budde

1983-01-01

191

Tomographic measurement of liquid hold up and effective interfacial area distributions in a column packed with high performance structured packings  

Microsoft Academic Search

In this paper, we report on the use of a high energy and high resolution X-ray tomograph to visualize and quantify the distribution of liquid hold up and of gas–liquid interfacial area in a 0.1m diameter column filled with MellapakPlus 752.Y packing elements. A standard air–water system at room temperature and atmospheric pressure were used. Tomographic measurements have been carried

S. Aferka; A. Viva; E. Brunazzi; P. Marchot; M. Crine; D. Toye

2011-01-01

192

Design considerations for packed columns removing manganese from mining seepage  

SciTech Connect

A field study during 1986 at a reclaimed strip mine are showed that column technology had promise as a low-maintenance, low-cost method of manganese removal and, therefore, design and operation data were needed before proceeding with a pilot plant scale operation. During 1987, three columns were operated in the laboratory to obtain needed design information. Removal efficiency was assessed as a function of hydraulic loading, mass loading, column depth, and pH. The studies yielded good information which could be expressed by simple models. The mechanisms of manganese removal were also assessed. Both batch and flow-through studies using various microbial poisons were conducted to determine whether the removal is biological or physical-chemical. Batch studies using autoclaving, ethanol, and sodium azide showed that adsorption of manganese was a fist step in the process followed by oxidation. Subsequent studies used smaller diameter columns in a continuous flow mode which were poisoned with sodium azide and operated for a longer period of time to avoid assessing only the adsorption step.

Gordon, J.A.; Chuang, N.S. (Tennessee Technological Univ., Cookeville (USA)); Wallace, R.P. (CH2M Hill, Montgomery, AL (USA))

1989-04-01

193

Performance of new prototype packed columns for very high pressure liquid chromatography.  

PubMed

The reduced heights equivalent to a theoretical plate (HETP) of naphtho[2,3-a]pyrene were measured at room temperature on two sets of new prototype columns designed to be used in very high pressure liquid chromatography (VHPLC). The mobile phase used was pure acetonitrile. The columns are 50, 100, and 150 mm long. Those of the first set are 2.1 mm I.D., those of the second set, 3.0 mm I.D. The performance of these new columns were compared to those of the first generation of VHPLC columns, commercially available in 2.1 mm I.D. The prototype and commercial columns behave similarly at low reduced linear velocities (nu<5), when the heat effects are negligible. At high flow rates, the shorter prototype columns have a twice better efficiency and less steep C-branches than the commercial columns. In contrast, the C-branch of the 150 mm long prototype columns are slightly steeper than those of the commercial columns. The important contribution to the reduced HETP that is due to the heat effects at high flow rates can in part be accounted for by a band broadening model governed by a flow mechanism with the shortest prototype columns. The sole heat effects cannot, however, explain the mediocre reduced HETPs of the 2.1 and 3.0 I.D. 150 mm long prototype columns. It seems that radial heterogeneity of the flow rate of the long prototype columns is significantly larger than that of the short columns. The contribution of the packing heterogeneity adds up to that of the heat effects to yield a poor column efficiency when sub-2 microm are packed into thin, long column tubes. PMID:20060978

Gritti, Fabrice; Guiochon, Georges

2010-01-04

194

Control of high-purity distillation column using a nonlinear wave theory  

SciTech Connect

A new model-based controller for profile position control of high-purity distillation columns is presented. The controller has been developed by incorporating nonlinear wave model into the generic model control framework. An observer based on the nonlinear wave theory is also proposed to determine the profile position. The performance of the nonlinear control scheme has been tested in simulation experiments of high-purity binary distillation columns. Tight control of profile position, which leads to fast stabilization of product compositions, has been achieved. Since the profile position control alone produces a slight offset from the desired product concentration, the composition/profile position cascade system has been used to remove the offset. The control scheme can handle significant disturbances and model-plant mismatch.

Han, Myungwan; Park, Sunwon (KAIST, Taejon (Korea, Republic of))

1993-05-01

195

Design and construction of a packed column simulator operating under atmospheric and reduced pressure  

Microsoft Academic Search

Distillation under reduced pressure for the separation of constituants is considered. To avoid thermic damage in columns, the most important parameters are pressure loss and resistance time. The development of a simulator, enabling the determination of the hydrodynamic parameters with the mixture air-water under different pressures for any given mixture, is carried out. A bibliographic study and a reference study,

Abdelhamid Messaoudene

1989-01-01

196

The effects of thermodynamic data on the design and operation of distillation columns  

SciTech Connect

The relative importance of various physical properties for distillation-column design and operation is classified. Vapor-liquid equilibrium data have a dominant effect. It is possible to quantify the effect of errors of relative volatility on the uncertainty of the number of stages required for a given simple binary separation problem by using the simplest, so-termed short-cut methods of column design, because the results obtained are, practically, the same as those found by more sophisticated methods. The same error in the relative volatility [alpha] leads to a sharply increasing uncertainty in the number of stages required as the value of [alpha] approaches unity.

Zeck, S. (BASF Aktiengesellschaft, Ludwigshafen (Germany))

1993-04-01

197

Fatty acid fractionation by column distillation: Purity, energy consumption and operating conditions  

Microsoft Academic Search

This paper discusses the optimal process conditions for production of individual fatty acids of any desired purity up to higher\\u000a than 99% and describes especially the influences of column internals as well as exchange numbers, reflux ratios and fatty\\u000a acid residence times at distillation temperatures. The new process conditions are characterized by degasification at low temperatures\\u000a followed by efficient dehydration

Hermann Stage

1984-01-01

198

Characterization of Organomagnesium Modified Kel-F Polymers as Column Packings  

Microsoft Academic Search

The reactivity of Kel-F (polychlorotrifluoroethylene) with a variety of Grignard reagents and the HPLC separation capability of these modified packings have been compared. Columns packed with long alkyl (C-8 or C-18) modified Kel-F 6061 supports had poor lifetimes while short alkyl (CH3) modified fluoropolymers did not produce effective separations. Aromatic modified Kel-F 6300 polymers, particularily phenyl supports, were both pressure

N. D. Danielson; S. Ahmed; J. A. Huth; M. A. Targrove

1986-01-01

199

CFD modeling of the effect of absorbent size on absorption performance of a packed bed column  

Microsoft Academic Search

This paper reports a study on the ability of the computational fluid dynamics (CFD) modeling for analyzing the fluid flow\\u000a hydrodynamics and absorption in a packed bed column. The water absorption by silica gel absorbents in an experimental packed\\u000a bed was investigated, and the absorption performance of two different sizes of absorbent was studied. A series of experiments\\u000a were carried

Masoud Rahimi; Mohsen Mohseni

2008-01-01

200

CFD SIMULATION AND EXPERIMENTAL STUDY OF FLOW IN PACKED BUBBLE COLUMNS  

Microsoft Academic Search

The gas holdup in a small-scale packed bubble column with dimensions of 35?mm wide and 10?mm deep was measured for air-water system. The effect of gas flow rate on gas holdup was investigated for various packings such as spheres, Berl saddles, and knitted meshes. In all cases it was found that the gas holdup increases with increasing gas flow rate.

F. H. YIN; J. L. MIDGLEY; A. AFACAN; K. NANDAKUMAR; K. T. CHUANG

2004-01-01

201

Azeotropic distillation in a middle vessel batch column. 1: Model formulation and linear separation boundaries  

SciTech Connect

A mathematical model for the middle vessel batch distillation column (MVC) is developed using the concept of warped time analysis and used to study the qualitative dynamics of the MVC when it is used to separate multicomponent azeotropic mixtures. A limiting analysis is then developed for a MVC with an infinite number of trays, operated under infinite reflux/reboil ratios, under the assumption of linear separation boundaries. It is determined that, under limiting conditions, the distillate product drawn from the MVC is given by the {alpha} limit set of the MVC still pot composition, while the bottoms product drawn from the MVC is given by the {omega} limit set of the MVC still pot composition. The net product composition is determined by taking a convex combination of the two products. The notions of steering the still pot composition, the vector cone of possible motion for the still pot composition, and the equivalency of the MVC to the combined operation of a batch rectifier and a stripper are also explored. The definition of batch distillation regions for the MVC operated at a given value of the middle vessel parameter {lambda}, and the bifurcation of these regions with the variation of {lambda}, are investigated. Lastly, a mathematical model incorporating the concept of warped time is developed for a multivessel column. The MVC can be viewed as a specific case of the multivessel column.

Cheong, W.; Barton, P.I. [Massachusetts Inst. of Tech., Cambridge, MA (United States)

1999-04-01

202

Experimental Analysis on Chemical Dehumidification of Air in a Packed Column by Hygroscopic Salt Solution: Comparison between Structured and Random Packings  

Microsoft Academic Search

This paper presents the experimental tests on chemical dehumidification of air by liquid desiccant carried out in a packed column with the hygroscopic solution H2O\\/LiBr. Two types of absorption columns, namely, random packing consisting of 1 in. Pall Ring elements and a structured column Mellapack 250Y, were tested. The experimental tests are presented in terms of humidity reduction, dehumidification efficiency,

Giovanni A. Longo; Andrea Gasparella

2006-01-01

203

A New Method For Accurate In Situ Concentration Measurements In Packed Columns  

NASA Astrophysics Data System (ADS)

Columns packed with glass beads or quartz sand are commonly used in the laboratory as a model porous medium for groundwater hydrological experiments. In a typical experiment water flows through the packed column in one direction, a chemical, tracer, or colloidal suspension is injected at the influent, and the effluent is sampled at various times and analyzed to determine concentration. Column parameters (e.g., porosity and dispersivity), chemical reactions or dissolution, and hydrodynamic parameters (e.g., interstitial velocity and dispersion) can be determined from effluent concentrations (i.e., break-through curves). This method has two inherent weaknesses. First, for experiments involving seismic or acoustic wave vibration, the packing material can settle, leading to preferential flow paths that develop over time and lead to inconsistent and inaccurate results. Second, measurements of the concentration of a tracer as it flows through the column (in situ) cannot be determined. A new method for accurately measuring in situ conservative tracer and colloid concentrations in packed columns is presented. The method includes fabricating clear sintered glass-bead-packed columns, taking digital photographs of the column under black light, and determining concentrations by measurement of the fluorescence in the photographs using MATLAB's® Image Processing Toolboxâ?¢. The sintering prevents changes in the geometry of the porous medium making it particularly useful for seismic or acoustic vibration experiments. Since fluorescence is measured, the method is limited to fluorescent solute tracers and fluorescent polystyrene microspheres (colloidal suspensions). The method is shown to be as accurate as effluent sampling and allows for accurate in situ measurement of tracer concentrations at multiple times. However, the method is not useful for decaying chemical species since each time must be scaled to the known injected mass.

Thomas, J. M.; Chrysikopoulos, C. V.

2009-04-01

204

Adsorption in columns packed with porous adsorbent particles having partially fractal structures.  

PubMed

A mathematical model is constructed and solved that could describe the dynamic behavior of the adsorption of a solute of interest in single and stratified columns packed with partially fractal porous adsorbent particles. The results show that a stratified column bed whose length is the same as that of a single column bed, provides larger breakthrough times and a higher dynamic utilization of the adsorptive capacity of the particles than those obtained from the single column bed, and the superior performance of the stratified bed becomes especially more important when the superficial velocity of the flowing fluid stream in the column is increased to accommodate increases in the system throughput. This occurs because the stratified column bed provides larger average external and intraparticle mass transfer and adsorption rates per unit length of packed column. It is also shown that increases in the total number of recursions of the fractal and the ratio of the radii between larger and smaller microspheres that make up the partially fractal particles, increase the intraparticle mass transfer and adsorption rates and lead to larger breakthrough times and dynamic utilization of the adsorptive capacity of the particles. The results of this work indicate that highly efficient adsorption separations could be realized through the use of a stratified column comprised from a practically reasonable number of sections packed with partially fractal porous adsorbent particles having reasonably large (i) total number of recursions of the fractal and (ii) ratio of the radii between larger and smaller microspheres from which the partially fractal particles are made from. It is important to mention here that the physical concepts and modeling approaches presented in this work could be, after a few modifications of the model, applied in studying the dynamic behavior of chemical catalysis and biocatalysis in reactor beds packed with partially fractal porous catalyst particles. PMID:23936911

Li, Min; Liapis, Athanasios I

2013-06-01

205

Biosorption of copper by marine algae Gelidium and algal composite material in a packed bed column  

Microsoft Academic Search

Marine algae Gelidium and algal composite material were investigated for the continuous removal of Cu(II) from aqueous solution in a packed bed column. The biosorption behaviour was studied during one sorption–desorption cycle of Cu(II) in the flow through column fed with 50 and 25mgl?1 of Cu(II) in aqueous solution, at pH 5.3, leading to a maximum uptake capacity of ?13

Vítor J. P. Vilar; Cidália M. S. Botelho; José M. Loureiro; Rui A. R. Boaventura

2008-01-01

206

Improved separation of natural oil triglycerides by liquid chromatography using columns packed with 3-?m particles  

Microsoft Academic Search

Very high-resolution separations of triglycerides in various natural oils have been demonstrated by liquid chromatography\\u000a using short columns packed with 3-?m alkyl bonded-phase particles. Analysis times range from 8 to 16 min without prior sample\\u000a clean-up. The primary detector used was a refractive index detector having low dispersive characteristics. Both the high efficiency\\u000a of the columns and the selectivity of

M. W. Dong; J. L. Dicesare

1983-01-01

207

Influence of liquid redistributors on the mass-transfer efficiency of packed columns  

SciTech Connect

In industrial mass-transfer columns liquid distributors and redistributors are used to mix the liquid after a certain random packing or structured packing height before it is applied to the next bed. The purpose of this is to counter a possible deterioration of the mass-transfer efficiency along the height of the column as a result of wall flow tendency of the liquid or to minimize the deterioration of the mass-transfer efficiency as a consequence of maldistribution of the liquid by the liquid distributor located above. However, when planning industrial columns, this influence on the mass-transfer efficiency can only be quantified with some difficulty which is why empirical standard values are mostly used for maximum bed and packing heights. This analysis shows that the height, after which liquid redistribution should take place, depends on numerous further influencing factors. It becomes evident that uneven irrigation of a packing with liquid over the cross section of the column is also a cause for the decline in the mass-transfer efficiency along the packed bed. The resultant decline in the mass-transfer efficiency is influenced, for instance, by the gas/liquid equilibrium behavior of the mixture that is to be separated, by the L/V flow ratio in the rectification, absorption, and desorption columns, by the type of packing used, and by the number of theoretical stages to be executed. A simulation procedure is shown, with whose assistance these factors influencing the mass-transfer efficiency can be recorded quantitatively.

Schultes, M.

2000-05-01

208

Towards further internal heat integration in design of reactive distillation columns—part I: The design principle  

Microsoft Academic Search

The thermodynamic efficiency of a reactive distillation column involving reactions with a highly thermal effect could sometimes be improved substantially through seeking further internal heat integration between the reaction operation and separation operation. Prudent arrangement of the reactive section and deliberate determination of feed location are the two effective methods that can complement internal heat integration within a reactive distillation

Kejin Huang; Koichi Iwakabe; Masaru Nakaiwa; Atsushi Tsutsumi

2005-01-01

209

Model reduction and optimization of a reactive dividing wall batch distillation column inspired by response surface methodology and differential evolution  

Microsoft Academic Search

Carrying out reaction and separation simultaneously in a reactive dividing wall batch distillation column batch RDWC in the case of ethyl acetate synthesis provides the possibility of separating both products and increasing the equilibrium reaction conversion. Overcoming the known azeotrope conditions, high purity for ethyl acetate and decreasing the batch time compared to simple reactive batch distillation are the advantages

Maysam Safe; Seyed Masoom Khazraee; Payam Setoodeh; Abdolhosein H. Jahanmiri

2012-01-01

210

New Generation of Chromatographic Packings and Columns for Determination of Biologically Active Compounds  

Microsoft Academic Search

Analysis of biologically active substances is particularly important in the pharmaceutical and biomedical area. For separation of polar compounds or complex mixtures by normal (NP) or reversed phase liquid chromatography (RP-HPLC) and\\/or electromigration techniques, it is necessary to apply a new generation of packings and columns with strictly defined properties. It is connected to the definition of chromatographic behavior and

Bogus?aw Buszewski; Sylwia Kowalska; Katarzyna Krupczy?ska

2005-01-01

211

A particle size distribution analysis of stressed HPLC column packing material  

Microsoft Academic Search

A particle size distribution analysis has been completed on three different HPLC column packing materials including silica gel (Si60) and two bonded phases (RP8 and RP18). The stationary phases were subjected to 18 hours stress with 1 N or 3 N KOH and found to have quantitatively different distribution patterns initially, at 13 hours and finally at 18 hours although

T. D. Wilson; D. M. Simmons

1991-01-01

212

Column packings for high performance liquid chromatography: Present state and future development  

Microsoft Academic Search

A short overview of HPLC column packings is presented. The properties of chromatographic carriers and the possibilities to combine the solid matrices with organic polymeric stationary phases are elucidated in detail. The latest achievements and anticipated future developments in the area are outlined.

D. Berek; I. Novák; M. Petro

1994-01-01

213

MODELING OF GAS ABSORPTION ACCOMPANIED BY CHEMICAL REACTION IN DOWNFLOW CO-CURRENT PACKED COLUMNS  

Microsoft Academic Search

A mathematical model is presented for gas absorption accompanied by chemical reaction in downflow cocurrent packed columns. The model incorporates an axial dispersed plug flow for the bulk gas and dynamic liquid phases and a Fickian type equation for the stagnant liquid phase. The reaction is considered to be occurring in both the dynamic and stagnant liquid phases. Numerical simulations

S. A. BEG; M. M. HASSAN; M. S. M. NAQVI

1998-01-01

214

Compact, low energy CO 2 management using amine solution in a packed bubble column  

Microsoft Academic Search

A novel method for removing CO2 from gas streams is described. The carbon dioxide continuous scrubber, CDOCS, takes advantage of the intimate liquid–gas contact afforded in a packed bubble column to both absorb the CO2 from a gas stream, and to regenerate the solution. The design relations and performance of a prototype CDOCS system using amine solution are presented. Over

Susan Krumdieck; Jamie Wallace; Owen Curnow

2008-01-01

215

Oscillatory pressure drops through a woven-screen packed column subjected to a cyclic flow  

Microsoft Academic Search

An experiment has been performed to investigate oscillatory pressure drop characteristics in packed columns (composed of three different sizes of woven screen) subjected to a periodically reversing flow of air. It was found that the oscillatory pressure drop factor increases with the kinetic Reynolds number (Re?)Dh and with the dimensionless fluid displacement (Ao)Dh. Based on 92 experimental runs, correlation equations

T. S. Zhao; P. Cheng

1996-01-01

216

Flooding and Mass Transfer in Goodloe-Packed Columns, Part 2.  

National Technical Information Service (NTIS)

Krypton gas is recovered from HTGR off-gas streams by countercurrent absorption in liquid carbon dioxide. Goodloe stainless steel wire mesh packing was chosen for the absorption columns since the process operates at -20 exp 0 C and about 20 atm pressure. ...

J. S. Ayala B. W. Brian A. C. Sharon

1977-01-01

217

Cotransport of Pseudomonas putida and kaolinite particles through water-saturated columns packed with glass beads  

Microsoft Academic Search

This study is focused on Pseudomonas putida bacteria transport in porous media in the presence of suspended kaolinite clay particles. Experiments were performed with bacteria and kaolinite particles separately to determine their individual transport characteristics in water-saturated columns packed with glass beads. The results indicated that the mass recovery of bacteria and clay particles decreased as the pore water velocity

Ioanna A. Vasiliadou; Constantinos V. Chrysikopoulos

2011-01-01

218

Lead uptake by algae Gelidium and composite material particles in a packed bed column  

Microsoft Academic Search

Biosorption of lead ions was studied in a flow-through column packed with red algae Gelidium and a composite material (industrial algal waste from the agar extraction process immobilized with polyacrylonitrile). Experiments were performed in order to study the effect of important design parameters such as flow rate and influent pH. The breakthrough curves for lead and proton concentrations were obtained

Vítor J. P. Vilar; Cidália M. S. Botelho; Rui A. R. Boaventura

2008-01-01

219

Effect of oxygen on ethanol fermentation in packed-bed tapered-column reactor  

Microsoft Academic Search

In ethanol production with immobilized yeast a major problem is the provision of nutrients to these highly concentrated cells. O2 being one of the nutrients of utmost importance to yeast cells, was fed into a column packed with beads with a cell loading of more than 40 g\\/l. Since addition of large volume of air or O2 to a cylindrical

Haluk Hamamci; Dewey D. Y. Ryu

1988-01-01

220

Scale up studies for the production of biosurfactant in packed column bioreactor  

Microsoft Academic Search

Biosurfactants capable of emulsifying pesticides have great potential to assist in microbial degradation of the pesticides. Solid State Fermentation (SSF) due to several advantages, is one of the efficient ways of producing these surfactants and seldom receives attention for commercial exploitation. In this study, a packed column bioreactor with wheat bran as the raw material and Bacillus subtilis has been

N. K. Veenanadig; M. K. Gowthaman; N. G. K. Karanth

2000-01-01

221

An adhesion model of the axial dispersion in wash columns of packed ice beds  

Microsoft Academic Search

Experimental studies on a packed ice bed wash column, which was used for separating ice from ice slurry in the process of freeze concentration or freeze desalination, showed that the transitional mixing zone at the wash front of the ice bed expanded as the ice particle size decreased. It can be interpreted that the smaller the particle size, the greater

Frank G. F. Qin; Xiaoxi Yang; Minlin Yang

2011-01-01

222

Gradient elution separation and peak capacity of columns packed with porous shell particles  

Microsoft Academic Search

The separation of the tryptic digests of myoglobin and bovine serum albumin were carried out in the gradient elution mode, using water, acetonitrile and TFA as the mobile phase components and columns packed with a new type of shell particles, Halo C18. These particles give very high efficiencies, characterized with an unusually low eddy diffusion contribution and a small mass

Nicola Marchetti; Alberto Cavazzini; Fabrice Gritti; Georges Guiochon

2007-01-01

223

Silica gel and carbon column packings for use in high-performance liquid chromatography  

Microsoft Academic Search

The basic properties of the most important groups of HPLC column packings are briefly compared. The physical properties of totally porous silica and carbon-based sorbents, especially the pecularities of their pore structure, are discussed in more detail. The advantages of the sponge-like sorbent structure over a corpuscular structure are elucidated. The unconventional concept of pellicular sorbents with a thick porous

D. Berek; I. Novák

1990-01-01

224

Nitrate removal from groundwater in columns packed with reed and rice stalks  

Microsoft Academic Search

Nitrate leaching contaminates groundwater. The objective of this study was to determine if reed and rice stalks could enhance denitrification and reduce nitrate leaching into groundwater. Artificial groundwater spiked with nitrate and field groundwater samples were tested in the columns in sand reactors packed with either reed or rice stalks. The maximum nitrate removal rates were determined to be 1.93

Jiazhong Qian; Zhiping Wang; Song Jin; Yong Liu; Tianhu Chen; Paul H. Fallgren

2011-01-01

225

Phosphate removal by column packed blast furnace slag ? II. Practical application of secondary effluent  

Microsoft Academic Search

The phosphate removal by the blast furnace slag was applied to a practical secondary effluent. An automatic calcium ion controller was supplied using the process described in the previous paper(1), and the necessary calcium ion for phosphate removal was supplied by using a calcium feeder column packed with converter slag. The concentration of calcium ion and pH were adjusted at

Wei Min Xie; Xiao Chun Zhang; Tetsuo Kitaide; Hiroshi Sunahara

1987-01-01

226

Atypical silica-based column packings for high-performance liquid chromatography  

Microsoft Academic Search

Column packings widely used for high-performance liquid chromatography (HPLC) mostly are based on porous silica microspheres with certain pore sizes and pore size distributions. Such materials have the most desirable compromise of properties that provide for effective and reproducible separations over a wide range of operating conditions. To provide desired separation characteristics, several manufacturers specially synthesize the silica particles for

J. J Kirkland; F. A Truszkowski; R. D Ricker

2002-01-01

227

Atypical silica-based column packings for high-performance liquid chromatography.  

PubMed

Column packings widely used for high-performance liquid chromatography (HPLC) mostly are based on porous silica microspheres with certain pore sizes and pore size distributions. Such materials have the most desirable compromise of properties that provide for effective and reproducible separations over a wide range of operating conditions. To provide desired separation characteristics, several manufacturers specially synthesize the silica particles for these packings. While such column packing materials have general utility for a wide range of needs, special silica-based particles have been synthesized with different physical conformations for special separation goals. This presentation describes some atypical types of silica-based particles with unique separation properties that enlarge the capabilities of HPLC methods. PMID:12236530

Kirkland, J J; Truszkowski, F A; Ricker, R D

2002-08-01

228

Ultrahigh-pressure liquid chromatography using a 1-mm id column packed with 1.5-microm porous particles.  

PubMed

The evolution of chromatography has led to the reduction in the size of the packing materials used to fabricate HPLC columns. The increase in the backpressure required has led to this technique being referred to as ultrahigh-pressure liquid chromatography (UHPLC) when the column backpressure exceeds 10000 psi (approximately 700 bar). Until recently, columns packed with sub-2-microm materials have generally fitted into two classes; either short (less than 5 cm) columns designed for use on traditional HPLC systems at pressures less than 5000 psi (350 bar), or capillary columns (inner diameters less than 100 microm). By using packing materials with diameters <2 microm to fabricate UHPLC columns, there is an increase in efficiency and a decrease in the analysis time that are directly proportional to the size of the packing material. In order to realize and exploit the increase in efficiency, however, the columns must maintain lengths typically associated with analytical columns (15-25 cm). We have packed 1 mm diameter, 150 mm in length columns with 1.5 microm packing material, and evaluated their performance in UHPLC. The pressure required to achieve optimum linear velocities in plots of plate height versus linear velocity was in the vicinity of 1104 bar (16000 psi). The 1.5 microm particle-packed column was compared with the more traditional 150 mm long analytical columns packed with 3 microm materials. This column showed an efficiency that was approximately twice that observed with the 3 microm packed column and a concomitant reduction in the analysis time, theoretically predicted. PMID:17595956

Anspach, Jason A; Maloney, Todd D; Colón, Luis A

2007-05-01

229

Low surface area carbonized silica obtained by the pyrolysis of dichloromethane: A column packing for adsorption and exclusion chromatography  

Microsoft Academic Search

Carbonized silica has been used as column packing for HPLC. Up to now it has been obtained by the pyrolysis of the vapour of benzene as well as aliphatic and aromatic alcohols. This paper reports on the properties of carbonized silica obtained by the pyrolysis of dichloromethane and used as column packing in HPLC.

A. L. Dawidowicz; A. Gierak; A. Waksmundzki

1983-01-01

230

A Method for Predicting the Performance of Packed Columns Operating with a Reactive Scrubbing Liquid That Control Gaseous Air Pollutants  

Microsoft Academic Search

A method for predicting the performance of packed columns that control gaseous air pollutants has been developed that exploits the advances in both computer software and hardware commonly used by practicing engineers. The solution of the simultaneous partial differential equations that describe the absorption process in packed columns that occurs in the presence of chemical reaction is obtained by converting

Clayton P. Kerr

2002-01-01

231

Liquid phase residence time distribution for a two-phase countercurrent flow in a packed column with a novel internal  

Microsoft Academic Search

The liquid phase residence time distribution (RTD) for gas–liquid countercurrent flow in a packed column with a novel internal was measured by conductivity measurements and an air–water system. The RTD of a liquid tracer is well represented by the ADM and PDE models. At lower gas flow rates, the Peclet number of the liquid in the packed column with the

Yanhui Yuan; Minghan Han; Dezheng Wang; Yong Jin

2004-01-01

232

Packed-Bed Column Flotation of Fine Coal. Part II. Technical — Economic Feasibility and Scale-up Considerations  

Microsoft Academic Search

An economic analysis revealed that the new packed-bed flotation column is superior to conventional flotation cells for reduction of ash and pyritic sulfur. Furthermore, commercial packed-bed flotation columns can be designed on a direct scale-up basis.

D. C. YANG

1990-01-01

233

A column packing for isothermal gas chromatographic analysis of C 1 ?C 5 paraffins and monoolefins and dimethyl ether  

Microsoft Academic Search

An analytical GC method was developed which uses a single packed column consisting of three packings in series prepared with the following liquid phases: dimethyl sulfolane, propylene carbonate, and silver nitrate. This system provides satisfactory resolution of mixtures of C1?C5 hydrocarbons and dimethyl ether obtained when converting methanol to gasoline. Due to the high capacity of the column it is

L. W. Zatorski; A. Cichowlas

1981-01-01

234

Modeling the effects of column packing quality and residence time changes on protein monomer\\/aggregate separation  

Microsoft Academic Search

The packing quality of chromatography columns used for the purification of protein therapeutics is routinely monitored to ensure consistent and reproducible performance. In this work, we used established chromatography models to determine the effect of column packing quality and fluid residence time on the separation of protein therapeutic monomer and aggregate species using a hydrophobic interaction chromatography adsorbent (Phenyl Sepharose

Justin T. McCue; Philip Engel; Jörg Thömmes

2009-01-01

235

Separation characteristics of cryogenic distillation column with a feedback stream for separation of protium and tritium  

SciTech Connect

A mathematical simulation procedure is developed for a single cryogenic distillation column with a feedback stream and a catalytic equilibrator used for protium-tritium (HT) separation. Large errors in calculation of mole fractions of the HT in the two products may occur unless special care is taken. Errors are minimized here by solving a single-variable nonlinear equation using the Newton-Raphson method. Parametric investigations of interest for column design and operation are also presented. One result is that the sidestream location is found to strongly affect column performance, and the optimum location depends strongly on the external feed composition. Further, as the mole percentage of HT in the external feed increases, the flow rate of the sidestream must be increased. Finally the effect of thermodynamic properties of the isotopes and of the decay heat of tritium on static column behavior are examined. Differences in the latent heat of vaporization among the three molecular species (H/sub 2/, HT, and T/sub 2/) are found to be significant. It appears that consideration of the decay heat of tritium and of the nonideality of the H/sub 2/-HT-T/sub 2/ solution is necessary to accurately predict the tritium concentration in the top product of high purity protium, a key output parameter. The usual assumption of equal molal heats and equal molal overflows within the column can lead to error in the reboiler load exceeding +250%.

Masahiro Kinoshita; Yuji Naruse

1982-07-01

236

Continuous aqueous two-phase extraction of human antibodies using a packed column.  

PubMed

The performance of a pilot scale packed differential contactor was evaluated for the continuous counter-current aqueous two-phase extraction (ATPE) of human immunoglobulin G (IgG) from a Chinese hamster ovary (CHO) cells supernatant (CS) enriched with pure protein. Preliminary studies have been firstly performed in order to select the dispersed phase (phosphate-rich or polyethylene glycol 3350 Da (PEG)-rich phase) and the column packing material. The PEG-rich phase has been selected as the dispersed phase and the stainless steel as the preferred material for the column packing bed since it was not wetted preferentially by the selected dispersed phase. Hydrodynamic studies have been also performed, and the experimental results were successfully adjusted to the Richardson-Zaki and Mísek equations, typically used for the conventional organic-aqueous two-phase systems. An experimental set-up combining the packed column with a pump mixer-settler stage showed to have the best performance and to be advantageous when compared to the IgG batch extraction. An IgG recovery yield of 85% could be obtained with about 50% of total contaminants and more than 85% of contaminant proteins removal. Mass transfer studies have revealed that the mass transfer was controlled by the PEG-rich phase. A higher efficiency could be obtained when using an extra pump mixer-settler stage and higher flow rates. PMID:22173005

Rosa, P A J; Azevedo, A M; Sommerfeld, S; Bäcker, W; Aires-Barros, M R

2011-11-30

237

Dynamic catalytic distillation: Advanced simulation and experimental validation  

Microsoft Academic Search

Reactive distillation offers a number of potential advantages, so that many traditional operations are currently being investigated in order to discover further applications of this technology. Increasingly, it is performed in columns with catalytic packings that combine the advantages of normal structured packings and heterogeneous catalysts. Analysis of reactive distillation is difficult due to strong physico-chemical interactions, and it is

L. U. Kreul; A. Górak; C. Dittrich; P. I. Barton

1998-01-01

238

Leaching of terbumeton and terbumeton-desethyl from mini-columns packed with soil aggregates in laboratory conditions  

Microsoft Academic Search

Leaching of terbumeton (TER) and terbumeton-desethyl (TED) from mini-columns packed with natural soil aggregates was investigated. Five soil samples from the Champagne area (France) with different physicochemical parameters were used. The soil samples were hand-packed into a 50mm column in laboratory conditions. An aqueous solution of TER or TED was percolated through the column and collected effluents were analyzed for

A. Conrad; O. Dedourge; R. Cherrier; M. Couderchet; S. Biagianti

2006-01-01

239

Non-invasive measurement of eddy diffusion in very efficient liquid chromatography columns packed with sub-3 ?m shell particles  

Microsoft Academic Search

Mass transfer kinetics in a particular column packed with 2.6?m Kinetex-C18 particles was measured using a series of non-invasive methods. According to the manufacturer, this column was the most efficient one in a lot of 133 columns of the same dimensions, packed with particles of the same batch, with an efficiency about 6% larger than the lot average. The total

Fabrice Gritti; Georges Guiochon

2010-01-01

240

Scrubbing in packed columns of gases from soda-regeneration boiler complexes  

SciTech Connect

The treatment of gases from the soda-regeneration boilers in sulfate cellulose pulping plants is intended for the removal of dust and sulfur dioxide from the gases and for the recovery and utilization of their heat. In this paper the authors investigate the possibility of using columns of KhOLPAK horizontal sheet packings for cleaning the stack gases. The packings consist of sheets of punched and drawn metal arranged at fixed distances in a horizontal configuration. Spray nozzles are used to wet the surface area. Calculations and design parameters are carried out depicting the flow characteristics of the gases and sprays in both counterflow and concurrent flow scrubbers.

Kolev, N.N.; Paskalev, G.P.; Semkov, K.A.; Darakchiev, R.D.

1988-01-01

241

Effect of fouling on the capacity and breakthrough characteristics of a packed bed ion exchange chromatography column  

Microsoft Academic Search

This study examined the impact of fouling with yeast homogenate on capacity and breakthrough performance of an ion exchange packed bed column. Column performance was assessed by analysis of breakthrough curves obtained with BSA as a test protein. The overall impact of fouling on breakthrough performance depended heavily on the level of clarification of the feed stream. Challenging the column

Sun Chau Siu; Helen Baldascini; David C. Hearle; Mike Hoare; Nigel J. Titchener-Hooker

2006-01-01

242

Final Report - Advanced Hydraulic and Mass Transfer Models for Distillation Column Optimization and Design  

SciTech Connect

The project successfully developed a computational fluid dynamics (CFD) based simulation of the hydrodynamics of flow in a commercial structured packing element. This result fulfilled the prime objective of the research program. The simulation utilized commercial CFD code marketed by Fluent Inc. in combination with a novel graphical interface developed by Oak Ridge National Lab. The end product will allow the design of next generation column internals without the need for extensive experimental validation and will expand the fundamental understanding of the vapor-liquid contacting process.

Eldridge, Robert, B.

2005-10-13

243

Distillation  

NSDL National Science Digital Library

Science in its earliest beginnings consisted of a practice called alchemy. Alchemy includes the study of chemistry, biology, astronomy, spirituality, physics, and art. Distillation or experiments in purification of substances may have been a part of the practice of alchemy.

N/A N/A (None;)

2005-12-24

244

Chromatographic Lithium Isotope Separation Using Cubic Antimonic Acid as Column?Packing Material  

Microsoft Academic Search

Ion?exchange chromatographic lithium isotope separation was performed by using granular cubic antimonic acid as column packing material at 50°C. While the single?stage separation factor for the lithium isotopes was 1.0020, independent of the flow rate, HETP was a monotonously increasing function of flow rate both in breakthrough and reverse breakthrough experiments. After 442 cm chromatographic development, the Li atomic fraction increased

Takao Oi; Shinko Takahashi

2005-01-01

245

Liquid dispersion and gas holdup in packed bubble columns at atmospheric pressure  

Microsoft Academic Search

The gas holdup and liquid axial dispersion coefficient are measured in two semibatch packed bubble columns, 0.154 and 0.200m diameter for an air–water system, at atmospheric conditions. It is observed that the one-dimensional dispersion model does not give an accurate description of the tracer concentration profiles from a pulse injection. This is due to convective liquid flows inside the bed

Peter Therning; Anders Rasmuson

2001-01-01

246

Absorption of nitrogen oxides in aqueous solutions in a structured packing pilot column  

Microsoft Academic Search

This study deals with the absorption of dilute nitrogen oxides (NOx) into aqueous solutions of hydrogen peroxide (0.05M) and of sodium hydroxide (2M), at the atmospheric pressure. A pilot column filled with structured the metallic packing Optiflow™ was employed. The feed gas was air containing NOx at concentrations between 121 and 1336Pa and the oxidation degrees were 0.5 and 1.

J. L. de Paiva; G. C. Kachan

2004-01-01

247

Process development of continuous hydrogen production by Enterobacter aerogenes in a packed column reactor  

Microsoft Academic Search

Hydrogen bioproduction from agro-industrial residues by Enterobacter aerogenes in a continuous packed column has been investigated and a complete reactor characterization is presented. Experimental runs carried out at different residence time, liable of interest for industrial application, showed hydrogen yields ranging from 1.36 to 3.02 mmolH2mmolуglucose or, in other words, from 37.5% to 75% of the theoretical hydrogen yield. A

E. Palazzi; B. Fabiano; P. Perego

2000-01-01

248

Adsorption of acrylonitrile and methyl acrylate on activated carbon in a packed bed column  

Microsoft Academic Search

The adsorption equilibrium and dynamics of acrylonitrile (ACN), methyl acrylate (MA) and the ACN-MA mixture on activated carbon\\u000a were investigated in a packed bed column at 40?C. The study indicated that the adsorption isotherms of the pure components belong to the classical Langmuir type; in the\\u000a case of the binary mixture adsorption, the Ideal Adsorption Solution Theory (IAST) could predict

Fengsong Wang; Jun Li; Jiarong Wang; Haoqi Gao

2006-01-01

249

Searching for Measures of Reversibility in Continuous Adsorption through Packed Bed Columns  

Microsoft Academic Search

This work deals with searching for measures of after-process reversibility in continuous adsorption through packed bed columns. A methodology has been designed?developed under the form of an algorithmic procedure including 17 activity stages and 5 decision nodes. An implementation is presented concerning adsorption?desorption of methylene blue on pine sawdust. An Ideal Reversibility Index (IRI) and two Real Rreversibility Indices (RRIs)

Dimitris K. Sidiras

2009-01-01

250

Searching for Measures of Reversibility in Continuous Adsorption through Packed Bed Columns  

Microsoft Academic Search

This work deals with searching for measures of after-process reversibility in continuous adsorption through packed bed columns. A methodology has been designed\\/developed under the form of an algorithmic procedure including 17 activity stages and 5 decision nodes. An implementation is presented concerning adsorption\\/desorption of methylene blue on pine sawdust. An Ideal Reversibility Index (IRI) and two Real Rreversibility Indices (RRIs)

Dimitris K. Sidiras

2009-01-01

251

Biosorption of Cu in a packed bed column by almond shell: optimization of process variables  

Microsoft Academic Search

This paper presents the ability of a low-cost biosorbent, almond shell, to remove Cu(II) ions from aqueous solution. Biosorption capacity of almond shell to removal Cu(II) was studied in a packed bed column. The effect of various parameters, flow rate, initial copper concentration, and mass of biosorbent, was analyzed. A 2 factorial experiment design was carried out to optimize some

Mónica Calero de Hoces; Gabriel Blázquez García; Alicia Ronda Gálvez; Ana Estefanía Álvarez; María Ángeles Martín-Lara

2012-01-01

252

Continuous adsorption of Pt ions in a batch reactor and packed-bed column  

Microsoft Academic Search

Continuous adsorption of platinum (Pt) was performed by using a batch reactor and a packed-bed column system in which amine-treated activated carbon (AC) pellets (Norit RO 0.8) were used as adsorbents. The feed solution (pH 2.0) contained a mixture of Pt and base metal ions (Fe 2+, Cr3+) in chloride media. The central focus of the study was directed at

Henry Kasaini; Richard K. Mbaya

2009-01-01

253

Modeling of chromium (VI) biosorption by immobilized Spirulina platensis in packed column  

Microsoft Academic Search

This study describes biosorption of chromium (VI) by immobilized Spirulina platensis, in calcium alginate beads. Three aspects viz. optimization of bead parameters, equilibrium conditions and packed column operation were studied and subsequently modeled. Under optimized bead diameter (2.6mm), calcium alginate concentration (2%, w\\/v) and biomass loading (2.6%, w\\/v) maximum biosorption was achieved. 140gl?1 loading of optimized beads resulted in 99%

S. V. Gokhale; K. K. Jyoti; S. S. Lele

2009-01-01

254

Determination of sulphate and phosphate by flow-injection analysis using a barium chloranilate packed column  

Microsoft Academic Search

A flow-injection analysis of sulphate using a reaction column packed with barium chloranilate (BaCh) is described. The chloranilate ion released by the reaction is monitored at the isosbestic point (310 nm) of chloranilate. An aqueous solution of 2-propanol (60%) is used as the carrier solution at a flow-rate of 1 ml . min-1. The linear dynamic range of the detection

Minori Kamaya; Kunio Nagashima; Eizen Ishii

1993-01-01

255

Performance characteristics and modeling of carbon dioxide absorption by amines in a packed column  

Microsoft Academic Search

Absorption of carbon dioxide by amines in a packed column was experimentally investigated. The amines employed in the present study were the primary mono-ethanolamine (MEA) and tertiary N-methyldiethanolamine (MDEA), two very popular amines widely used in the industries for gas purification. The CO2 absorption characteristics by these two amines were experimentally examined under various operating conditions. A theoretical model was

Sheng H Lin; Ching T Shyu

1999-01-01

256

Chromate transport through columns packed with surfactant-modified zeolite\\/zero valent iron pellets  

Microsoft Academic Search

Chromate transport through columns packed with zeolite\\/zero valent iron (Z\\/ZVI) pellets, either untreated or treated with the cationic surfactant hexadecyltrimethylammonium (HDTMA), was studied at different flow rates. In the presence of sorbed HDTMA, the chromate retardation factor increased by a factor of five and the pseudo first-order rate constant for chromate reduction increased by 1.5–5 times. The increase in rate

Zhaohui Li; H. Kirk Jones; Pengfei Zhang; Robert S. Bowman

2007-01-01

257

Characteristics of a new HPLC column packed with octadecyl-bonded polymer gel  

Microsoft Academic Search

Summary  The chromatographic efficiency and stability of a new octadecyl-bonded polymer (ODP) gel, developed for reversed phase liquid\\u000a chromatography (RPLC) by substitution of stearate ester groups for the hydroxyl groups of vinyl alcohol copolymer particles,\\u000a were investigated and compared with those of conventional gels. The efficiency of the column packed with the ODP gel was practically\\u000a unaffected by repeated alternating passages

Y. Yanagihara; K. Yasukawa; U. Tamura; T. Uchida; K. Noguchi

1987-01-01

258

A Single Column Packing for The Gas-Liquid Chromatographic Separation of Various Biologically Important Compounds  

Microsoft Academic Search

The use of a single, commercially available column packing, TabsorbR, is described for the g. l. c. separation of a large number of different compounds. The resolution of the homologous members of the following series of compounds was achieved: (1) saturated fatty acids (C1-C18), (2) normal aliphatic saturated dlcarboxylic acids (C2-C14), (3) normal aliphatic saturated alcohols (C1-C24), (4) normal aliphatic

Karl Schmid; Li-Chuang H. Chen

1976-01-01

259

Comparison between the loading capacities of columns packed with partially and totally porous fine particles  

Microsoft Academic Search

The adsorption isotherms of phenol, caffeine, insulin, and lysozyme were measured on two C18-bonded silica columns. The first one was packed with classical totally porous particles (3?m Luna(2)-C18from Phenomenex, Torrance, CA, USA), the second one with shell particles (2.7?m Halo-C18 from Advanced Materials Technology, Wilmington, DE, USA). The measurements were made at room temperature (T=295±1K), using mainly frontal analysis (FA)

Fabrice Gritti; Georges Guiochon

2007-01-01

260

Polymer fractionation using chromatographic column packed with novel regenerated cellulose beads modified with silane  

Microsoft Academic Search

Novel microporous beads with the particle size of about 90?m were prepared, for the first time, from cellulose and konjac glucomannan (RC\\/KGM3) in 1.5M NaOH\\/0.65M thiourea aqueous solution by emulsification method. The microporous beads were then modified with silane to avoid the adsorption of polymers containing hydroxyl groups, coded as RC\\/KGM3-Si. A preparative size-exclusion chromatographic (SEC) column (500mm×20mm) was packed

Xiaopeng Xiong; Lina Zhang; Yifeng Wang

2005-01-01

261

Application of an in-situ thermo-polymerized porous polymer: creation of an on-column frit for a packed capillary HPLC column.  

PubMed

A 3-mm length of a porous monolithic polymer was prepared in a 0.32-mm inner-diameter fused-silica capillary by an in-situ thermo-polymerization method and used as an on-column frit for a packed capillary HPLC column. The on-column frit can resist high pressure up to 400 bar. A 5-microm packing material was packed in the capillary with the on-column frit by a slurry method. At pressure driving mode, separation of samples was performed using the capillary HPLC column. The in-situ frit preparation method has the advantages of easy preparation, easy control of the location of the frit and a mild preparing reaction condition. PMID:17372384

Ma, Jiping; Ding, Mingyu; Xu, Yan; Chen, Lingxin

2007-03-01

262

Azeotropic distillation in a middle vessel batch column. 3: Model validation  

SciTech Connect

A dimensional time model of the middle vessel batch distillation column (MVC) is developed in the ABACUSS process modeling environment, and simulations are conducted to validate the theoretical insights developed for the operation of the MVC based on a warped time model of the MVC. The qualitative dynamics of the MVC operated in the presence of linear separation boundaries are validated via simulations conducted on the ternary azeotropic mixture of acetone, chloroform, and methanol. It is also shown via simulation that the separation results obtained from a column with significant but reasonable amounts of holdup on the trays are not significantly different from a column in which holdup in the trays is assumed to be negligible. Theoretical operating policies for separating the azeotrope of acetone and chloroform using benzene as a batch entrainer are also validated using the ABACUSS model. Finally, the authors explore the advantages and disadvantages of different feasible operating policies for separating a mixture of acetone, benzene, and chloroform completely into its constituent pure components.

Cheong, W.; Barton, P.I. [Massachusetts Inst. of Tech., Cambridge, MA (United States)

1999-04-01

263

Column performance of granular activated carbon packed bed for Pb(II) removal.  

PubMed

The excessive release of lead from lead acid batteries, smelting plant into the environment is a major concern worldwide. Adsorption process is among the most effective techniques for lead removal from wastewater and activated carbon has been widely used as an adsorbent. In this paper an attempt has been made to investigate the adsorption behaviour of Pb(II) from aqueous systems onto granular activated carbon using the batch mode and continuous mode in a packed bed column with more successive service and regeneration. The experiments were performed at constant temperature and dimensions of column and packed bed of granular activated carbon with variation of flows through the bed and concentrations of lead solutions. Breakthrough points were found out for the adsorption of lead on the adsorbent using continuous-flow column operation by varying different operating parameters like hydraulic loading rate from 4 to 16 m(3)/h m(2) and feed concentrates from 20 to 60 mg/l. Granular activated carbon column regeneration using 0.5 M concentration of HNO(3) has been investigated. Results indicate encouraging performance towards removal of Pb(II). PMID:18249492

Dwivedi, Chandra P; Sahu, J N; Mohanty, C R; Mohan, B Raj; Meikap, B C

2008-01-04

264

A temperature programmed evaporation method for exact determination of the amount of stationary phase in chromatographic column packings  

Microsoft Academic Search

A new temperature programmed evaporation method for determination of amount of stationary phase in chromatographic column packings has been developed. The results obtained by testing the method and its applicability have been discussed.

R. N. Nikolov; N. D. Petsev; A. D. Stefanova

1976-01-01

265

Surface association of motile bacteria and apparent tortuosity values in packed column experiments  

NASA Astrophysics Data System (ADS)

Mathematical models used previously to obtain transport parameters from experimental investigations of bacterial transport in packed columns by Olson et al. (2005) yielded apparent tortuosity values that were an order of magnitude higher than expected for packed beds. The association of motile bacteria with solid surfaces of porous media, due to their swimming, contributed to the large apparent tortuosity values evaluated from packed column experiments; a modification of the transport equations to account for surface association yielded tortuosity values that were physically more reasonable. Although it was not possible to uniquely determine values of the kinetic parameters for surface association because of limitations with the experimental methods used by Olson et al., it was possible to constrain the range of values. A theoretical derivation of the mean residence time for swimming bacteria at a surface provided qualitative and quantitative support for including surface association terms in the transport model. This analysis shows that surface association can be a significant factor in modeling bacterial migration, and consideration of bacterial swimming properties such as run lengths and turn angles is important for predicting bacterial transport in saturated granular media typical of groundwater environments.

Narayanaswamy, Karthik; Ford, Roseanne M.; Smith, James A.; Fernandez, Erik J.

2009-07-01

266

Experimental study of a cocurrent upflow packed bed bubble column reactor: pressure drop, holdup and interfacial area  

Microsoft Academic Search

Gas–liquid interfacial areas have been determined by means of chemically enhanced absorption of CO2 into DEA in a packed bed bubble column reactor with an inner diameter of 156 mm. The influence of the gas velocity and particle diameter on the interfacial areas, pressure drops and liquid holdups has been investigated. For both packings the limiting values of the gas

E. J. Molga; K. R. Westerterp

1997-01-01

267

Modified equilibrium-dispersive model for the interpretation of the efficiency of columns packed on core-shell particle  

SciTech Connect

A modified Equilibrium Dispersive (ED) Model is proposed for the modeling of chromatographic processes in columns packed with shell-particle adsorbents and operated under very high pressures. This new model was validated on the basis of experimental results obtained with 2.1 mm x 150 mm columns packed with superficially porous 1.7 {micro}m Kinetex-C{sub 18} particles and with classical columns packed with 1.7 {micro}m BEH-C{sub 18} fully porous particles. The influence of the heat friction on the performance of these columns was analyzed by comparing the experimental and calculated peak profiles. Moreover a theoretical analysis of the influence the solid-core conductivity on the column efficiency was discussed.

Gritti, Fabrice [University of Tennessee, Knoxville (UTK); Kaczmarski, Krzysztof [University of Tennessee and Rzeszow University of Technology, Poland; Guiochon, Georges A [ORNL

2011-01-01

268

Research on the separation properties of empty-column gas chromatography (EC-GC) and conditions for simulated distillation (SIMDIS).  

PubMed

Previous studies have revealed it is possible to separate a high-boiling mixture by gas chromatography in empty fused-silica capillary tubing rather than in columns coated with stationary phase. Chromatographic separation occurs solely on the basis of the different boiling points of the substances separated. The high similarity of such separations to those in classic distillation seems advantageous when gas chromatography is used for simulated distillation. This paper presents results from further research on the separation properties of empty fused silica tubing. The efficiency of this chromatographic system has been examined. The usefulness of such conditions has been studied for simulated distillation, i.e. to determine the boiling-point distribution of complex mixtures, mainly petroleum fractions and products, on the basis of their retention relative to reference substances. The results obtained by use of empty-column gas chromatography (EC-GC) and by use of classical simulated distillation columns have been compared for solutes of different polarity. Studies revealed boiling points determined by EC-GC were more accurate than those obtained by the standard method of simulated distillation. PMID:23925798

Boczkaj, Grzegorz; Kami?ski, Marian

2013-08-08

269

Bacterial Motility and Chemotaxis in Porous Media: Connecting Pore Scale Behavior to Transport in Packed Columns  

NASA Astrophysics Data System (ADS)

Motile species of bacteria are able to swim by the rotation of flagella and move independently of the surrounding fluid velocity. This allows them to sense and respond to chemical gradients and migrate to locations that are beneficial to their growth and survival. We have been interested for some time now in understanding how this independent swimming behavior impacts the fate and transport of bacteria in ground water environments. Through a combination of experiments and mathematical models we have been building a framework in which to relate individual swimming properties of a bacterium measured in a simple bulk aqueous system to migration behavior of a population within a more complex packed column environment. Our experimental studies range from analysis of the trajectories of individual bacteria using a three-dimensional tracking microscope to dispersion of a population within a micromodel of well-defined pore networks to magnetic resonance imaging (MRI) of immunomagnetic-labeled bacteria in static columns. Mathematical models based on an understanding of the swimming behavior at the microscopic scale are used to analyze motility and chemotaxis within a single pore and in packed columns. Effective diffusion and dispersion coefficients which can be used in advection-dispersion equations for macroscopic-scale transport were determined from experimental data and related to theoretical predictions.

Ford, R. M.

2001-12-01

270

Removal of lead in a fixed-bed column packed with activated carbon and crab shell  

SciTech Connect

Crab shell particles (Protunus trituberculatus) and activated carbon (Norit 0.8 SUPRA) were used as packing materials in a fixed-bed column. When 1 g crab shell was added in a column packed with 10 g activated carbon, breakthrough occurred at 1,500 bed volumes as compared to 380 bed volumes for 10 g activated carbon only. The addition of crab shell particles into an activated carbon column resulted in an increased uptake of lead. The dramatic improvement might be attributed to an increase in CO{sub 3}{sup 2{minus}} and OH{sup {minus}} available for binding lead. From the results of SEM, XRD, and FT-IR analyses, the major mechanism of lead removal was based on dissolution of CaCO{sub 3} in the crab shell followed by precipitation of Pb{sub 3}(CO{sub 3}){sub 2}(OH){sub 2(s)} on the surface of activated carbon. The lead uptake increased twofold when the influent lead concentration was increased from 10 to 50 mg/L.

Lee, M.Y.; Shin, H.J.; Yang, J.W. [Korea Advanced Inst. of Science and Technology, Taejon (Korea, Republic of). Dept. of Chemical Engineering; Lee, S.H. [Korea Atomic Energy Research Inst., Taejon (Korea, Republic of); Park, J.M. [Pohang Univ. of Science and Technology (Korea, Republic of). Dept. of Chemical Engineering

1998-05-01

271

Modeling of chromium (VI) biosorption by immobilized Spirulina platensis in packed column.  

PubMed

This study describes biosorption of chromium (VI) by immobilized Spirulina platensis, in calcium alginate beads. Three aspects viz. optimization of bead parameters, equilibrium conditions and packed column operation were studied and subsequently modeled. Under optimized bead diameter (2.6mm), calcium alginate concentration (2%, w/v) and biomass loading (2.6%, w/v) maximum biosorption was achieved. 140 g l(-1) loading of optimized beads resulted in 99% adsorption of chromium (VI) ions from an aqueous solution containing 100 mg l(-1) of chromium (VI). The quantitative chromium (VI) uptake was effectively described by Freundlich adsorption isotherm. The immobilized S. platensis beads were further used in a packed bed column wherein the effects of bed height, feed flow rate, inlet chromium (VI) ion concentration were studied by assessing breakthrough time. The performance data were tested for various models fitting in order to predict scale up-design parameters such as breakthrough time and column height. Results were encouraging. PMID:19493617

Gokhale, S V; Jyoti, K K; Lele, S S

2009-05-14

272

Analysis of the Transfer Function Model of Tray-Type Binary Distillation Columns with Liquid Hydraulic Delay.  

National Technical Information Service (NTIS)

A transfer function model (TFM) in the frequency domain is used to predict that a distillation column system (compositions to terminal flow rate) is a low pass filter with large time constants and low cut-off frequency. Computed results in frequency and t...

J. B. Edwards B. M. Zhou

1983-01-01

273

Chromatographic Removal of Host Cell DNA from Cellular Products Using Columns Packed with Cationic Copolymer Beads  

Microsoft Academic Search

This paper describes a method for selective removal of DNA from various cellular products using columns packed with cross-linked poly(ethyleneimine) (PEI) beads or cross-linked N,N-dimethylaminopropylacrylamide (DMAPAA) beads. Each bead type showed a high DNA-adsorbing activity under experimental conditions of pH 5.0–9.0 and ionic strength of ? = 0.05–0.4. When ?-globulin was present in solution with DNA under physiological conditions (pH 7.2, ?

M. Sakata; M. Nakayama; T. Fujisaki; S. Morimura; M. Kunitake; C. Hirayama

2005-01-01

274

The role of water on the equilibrium of esterification by immobilized lipase packed-bed column reactor  

Microsoft Academic Search

Summary The role of water on the continous synthesis of geranyl esters by immobilized lipase fromHumicola lanuginosa No. 3 was studied in a packed-bed column reactor (PBR) installed with a molecular sieve column for water extraction. The conversion degress by PBR were highly influenced by the water concentration throughout the reaction which acted as a determinant on the reaction equilibrium.

Ibrahim Che Omar; Naomichi Nishio; Shiro Nagai

1988-01-01

275

Packed bed column studies for the removal of Acid blue 92 and Basic red 29 using non-conventional adsorbent  

Microsoft Academic Search

The adsorptive removal of Acid blue 92 and Basic red 29 dyes was achieved using a packed column prepared by Euphorbia antiquorum L activated carbon. The effects of various factors like influent concentration, flow rate and bed height were analysed. The column experiments using Euphorbia antiquorum L activated carbon showed that adsorption efficiency increases with increase in the influent concentration

P Sivakumar; P N Palanisamy

276

Mathematical modeling of biosorption of safranin onto rice husk in a packed bed column using artificial neural network analysis  

Microsoft Academic Search

The study was undertaken to find out a suitable low cost, environmental friendly and highly effective biosorbent to remove safranin dye from wastewater. For this a continuous downward packed bed column experiment was carried out by using rice husk as a biosorbent. The effects of the operational parameters like pH, flow rate, time etc were studied in continuous downward column.

Papita Das Saha; Suman Dutta

2012-01-01

277

Mass transfer mechanism in liquid chromatography columns packed with shell particles: would there be an optimum shell structure?  

PubMed

The mass transfer mechanisms in columns packed with old (55 ?m Zipax and 5 ?m Poroshell) and recently commercialized shell particles (2.7 ?m Halo-C(18) and Kinetex-C(18)) were investigated from a physico-chemical point of view. Combining a model of diffusion in heterogeneous packed beds (effective medium theory) with values of the heights equivalent to a theoretical plate (HETPs derived from the first and second central moments of the elution profiles) and of the peak variances provided by the peak parking method, we demonstrate that columns packed with current shell particles perform better than those packed with fully porous particles in resolving low molecular weight compounds because the eddy diffusion term of the van Deemter equation of the former is markedly smaller. The calculation of eddy diffusion in column beds suggests that the smaller A terms are due to smaller trans-column velocity bias in columns packed with shell particles. We also show that the mass transfer of large molecules (e.g., proteins) is faster when the internal volume accessible to the analyte increases. Therefore, it is suggested that shell particles made of concentric layers with average pore sizes increasing with increasing diameter would provide columns with higher efficiency. PMID:21081233

Gritti, Fabrice; Guiochon, Georges

2010-10-28

278

Synthesis and Characterization of a Polymeric Fluorocarbon-Diamine Reversed Phase Weak Anion Exchange Silica HPLC Column Packing  

Microsoft Academic Search

Polymeric fluorocarbon-diamine silica column packings were synthesized by first reacting a copolymer of chlorotrifluoroethylene and vinylidene fluoride (Kel-F 800) with piperazine and then reacting this product with aminopropyl silica. This mixed mode reversed phase-weak anion exchange HPLC column and a hydrocarbon (C-8) weak anion exchange silica HPLC column were compared for the separation of aromatic organic acids. Although the fluorocarbon

N. D. Danielson; J. Wangsa; S. A. Shamsi

1995-01-01

279

Ni(II) ion-imprinted solid-phase extraction and preconcentration in aqueous solutions by packed-bed columns  

Microsoft Academic Search

Solid-phase extraction (SPE) columns packed with materials based on molecularly imprinted polymers (MIPs) were used to develop selective separation and preconcentration for Ni(II) ion from aqueous solutions. SPE is more rapid, simple and economical method than the traditional liquid–liquid extraction. MIPs were used as column sorbent to increase the grade of selectivity in SPE columns. In this study, we have

Arzu Ersöz; R?dvan Say; Adil Denizli

2004-01-01

280

Separation of 2-aminobenzamide labeled glycans using hydrophilic interaction chromatography columns packed with 1.7 ?m sorbent  

Microsoft Academic Search

Separation by hydrophilic interaction chromatography (HILIC) with fluorescence detection utilizing a sub-2?m glycan column for the separation of 2-aminobenzamide (2-AB) labeled N-linked glycans is described. The HILIC column packed with a 1.7?m amide sorbent improves the peak capacity compared to a 3.0?m HILIC column by a similar degree as observed in reversed-phase ultra-performance liquid chromatography (RP-UPLC). The results indicated that

Joomi Ahn; Jonathan Bones; Ying Qing Yu; Pauline M. Rudd; Martin Gilar

2010-01-01

281

Design of steam-stripping columns for removal of volatile organic compounds from water using random and structured packings  

SciTech Connect

Mass-transfer data at different feed and steam rates, using structured and random packings, have been collected to develop a model for the design or analysis of packed columns for stripping of volatile organic compounds (VOCs) from water. The steam-stripping experiments were conducted in a stainless steel column of 0.245-m internal diameter, with 2.8 m of packed section. The packings used were Sulzer BX gauze structured packing, Mellapak 250Y structured packing, 1-in. Flexirings, and 1-in. Fleximax random packing. The VOCs were chloroform (CH{sub 3}Cl) and toluene (C{sub 7}H{sub 8}). The model considers the simultaneous occurrence of mass transfer and hydraulic phenomena with the same expressions for liquid and vapor mass-transfer coefficients and the same expression for effective interfacial area with one constant for each packing. The average deviation for the measured and calculated volumetric mass-transfer coefficient and effective height of packing is 0.29 and 0.23, respectively.

Castillo, J.R.O.D.; Guerrero-Medina, G.; Lopez-Toledo, J.; Rocha, J.A.

2000-03-01

282

Characterization of column packing materials in high-performance liquid chromatography by charge-detection quadrupole ion trap mass spectrometry.  

PubMed

This article reports an application of charge-detection quadrupole ion trap mass spectrometry (CD-ITMS) to characterize the column packing materials in high-performance liquid chromatography (HPLC). Both the mean mass and the mass distribution of the packing materials are obtained and used to calculate the specific surface area of unbonded silica, the carbon load of the bonded silica, and their particle size distributions. The obtained specific surface areas and carbon loads are consistent with those measured independently by nitrogen sorption and elemental analysis respectively, whereas the derived size distributions show better resolution than that measured by a laser particle size analyzer. Furthermore, we evaluate the uniformity of particle size, which is the key parameter for column efficiency of the liquid chromatography by analyzing the mass distribution of the packing materials at the top and bottom of the column. A broader mass distribution, which yields decreased column efficiency, is observed for the column top because of the excessive use of the column. Our results suggest that CD-ITMS can serve as an alternative means for the characterization of the packing materials in HPLC and is potentially useful for column quality control. PMID:21612293

Xiong, Caiqiao; Zhou, Xiaoyu; Chen, Rui; Zhang, Yiming; Peng, Wen-Ping; Nie, Zongxiu; Chang, Huan-Cheng; Liu, Huwei; Chen, Yi

2011-06-14

283

Adsorption in a stratified column bed packed with porous particles having partially fractal structures and a distribution of particle diameters.  

PubMed

Stratified column bed systems whose sections are formed by packing adsorbent particles with a partially fractal structure are proposed and studied. The simulation results clearly show that the breakthrough times and the shape of the breakthrough curves obtained from stratified column beds are significantly larger and sharper than those obtained from conventional columns. The stratified column beds provide, to the designer and user of chromatographic column systems, more degrees of freedom with respect to the number of parameters and variables that could be controlled in the design, construction, and operation of efficient chromatographic adsorption systems. Furthermore, the results suggest that the stratified column beds could provide a higher dynamic adsorptive capacity than conventional columns when it is required to increase the column throughput. PMID:22589155

Li, Min; Liapis, Athanasios I

2012-04-01

284

Enhanced bioethanol dehydration by extractive and azeotropic distillation in dividing-wall columns  

Microsoft Academic Search

The industrial production of anhydrous bioethanol requires energy demanding distillation steps to overcome the azeotropic behavior of ethanol–water mixture. In spite of the recent developments in pervaporation and adsorption with molecular sieves, the large scale production is dominated by extractive and azeotropic distillation as the separation of choice.This study proposes novel distillation technologies for enhanced bioethanol dehydration, by extending the

Anton A. Kiss; David J-. P. C. Suszwalak

285

Geometrical and topological measures for hydrodynamic dispersion in confined sphere packings at low column-to-particle diameter ratios.  

PubMed

At low column-to-particle diameter (or aspect) ratio (d(c)/d(p)) the kinetic column performance is dominated by the transcolumn disorder that arises from the morphological gradient between the more homogeneous, looser packed wall region and the random, dense core. For a systematic analysis of this morphology-dispersion relation we computer-generated a set of confined sphere packings varying three parameters: aspect ratio (d(c)/d(p)=10-30), bed porosity (?=0.40-0.46), and packing homogeneity. Plate height curves were received from simulation of hydrodynamic dispersion in the packings over a wide range of reduced velocities (v=0.5-500). Geometrical measures derived from radial porosity and velocity profiles were insufficient as morphological descriptors of the plate height data. After Voronoi tessellation of the packings, topological information was obtained from the statistical moments of the free Voronoi volume (V(free)) distributions. The radial profile of the standard deviation of the V(free) distributions in the form of an integral measure was identified as a quantitative scalar measure for the transcolumn disorder. The first morphology-dispersion correlation for confined sphere packings deepens our understanding of how the packing microstructure determines the kinetic column performance. PMID:23000179

Khirevich, Siarhei; Höltzel, Alexandra; Seidel-Morgenstern, Andreas; Tallarek, Ulrich

2012-09-02

286

Coupling of a microbore column with a column packed with non-porous particles for fast comprehensive two-dimensional high-performance liquid chromatography  

Microsoft Academic Search

To reduce the analysis time in comprehensive two-dimensional HPLC columns packed with 1.5 ?m non-porous particles were applied in the second dimension. Preservation of the efficiency under coupling conditions was realized by adapting the peak volumes in the first dimension. To achieve this an instrumental set-up was designed and used which combines a micro-column in the first dimension and a

Anja P Köhne; T Welsch

1999-01-01

287

Automated determination of pirlindole enantiomers in plasma by on-line coupling of a pre-column packed with restricted access material to a chiral liquid chromatographic column  

Microsoft Academic Search

A fully automated liquid chromatographic method has been developed for the determination of the enantiomers of pirlindole, an antidepressant drug, in human plasma. The method is based on the use of a pre-column packed with restricted access material (RAM) (LiChrospher ADS RP-4) for sample clean-up coupled to a column containing a cellulose tris-(3,5-dimethylphenylcarbamate) based chiral stationary phase (Chiralcel OD-R) for

P Chiap; A Ceccato; R Gora; Ph Hubert; J Géczy; J Crommen

2002-01-01

288

Monitoring Anaerobic TCE Degradation by Evanite Cultre in Column Packed with TCE-Contaminated Soil  

NASA Astrophysics Data System (ADS)

Trichloroethylene (TCE) is a long-term common groundwater pollutant because the compound with high density is slowly released into groundwater. Physical and chemical remediation processes have been used to clean-up the contaminant, but novel remediation technology is required to overcome a low efficiency of the traditional treatment process. Many researchers focused on biological process using an anaerobic TCE degrading culture, dehalococcoides spp., but it still needs to evaluate whether the process can be applied into field scale under aerobic condition. Therefore, in this work we examined two different types (i.e., Natural attenuation and bioaugmentation) of biological remediation process in anaerobic column packed with TCE-contaminated soil. A TCE degradation by indigenous microorganisms was confirmed by monitoring TCE and the metabolites (c-DCE, VC, ETH). However, TCE was transformed and stoichiometry amount of c-DCE was produced, and VC and ETH was not detected. To test bioaugmentation of Evanite culture containing dehalococcoides spp., Evanite culture was injected into the column and TCE degradation to c-DCE, VC, ETH was monitored. We are evaluating the transport of the Evanite culture in the column by measuring TCE and VC reductases. In the result, the TCE was completely degraded to ETH using hydrogen as electron donor generate by hydrogen-production fermentation from formate.

Ko, J.; Han, K.; Ahn, G.; Park, S.; Kim, N.; Ahn, H.; Kim, Y.

2011-12-01

289

Ammonia removal from compost leachate using zeolite. II. A study using continuous flow packed columns.  

PubMed

Bench-scale packed zeolite columns were set up and operated to investigate the continuous removal of ammonium ions from compost leachate. The effects of hydraulic retention time (HRT), and particle size of the zeolite on the ammonia adsorption capacity were studied. For both the coarse particle and the powdered zeolite columns, higher ammonia removal efficiencies were achieved with longer HRT (i.e., lower influent flow rate) tests. At the same HRT, ammonia removal efficiencies from tests with powdered zeolite were generally 20% higher than tests with the coarse particle zeolite. A HRT of 6 hours was found appropriate for efficient ammonia removal, and an operating capacity of 1.31 mg N/g zeolite was obtained. Over 98% of the ammonia input from the influent was consistently removed for over 5 bed volumes (BV) of compost leachate flowing through the zeolite column. Zeolite proved to have a great potential as a medium for ammonia removal in treating composting leachate. PMID:11599728

Liu, C H; Lo, K V

2001-09-01

290

Direct coupling of packed column supercritical fluid chromatography to continuous corona discharge ion mobility spectrometry.  

PubMed

In this study, packed column supercritical fluid chromatography (SFC) was directly coupled to a continuous corona discharge (CD) ion mobility spectrometer (IMS) with several modifications. The main advantage of the developed detector is its capability to introduce full column effluent up to 2000 mL min(-1) CO(2) gas directly into the IMS cell relative to 40 mL min(-1) CO(2) gas as a maximum tolerance, reported for the previous IMS detectors. This achievement was made possible because of using corona discharge instead of (63)Ni as an ionization source and locating the inlet and outlet of the CO(2) gas in the counter electrode of the CD in opposite direction. In addition, a heated interface was placed between back pressure regulator (BPR) and the IMS cell to heat the output of the BPR for introducing sample as the gas phase into the IMS cell. Furthermore, a make-up methanol flow was introduced between the column outlet and BPR to provide a more uniform flow through the BPR and also to prevent freezing and deposition of the analytes in the BPR. The performance of the SFC-CD-IMS was evaluated by analysis of testosterone, medroxyprogesterone, caffeine, and theophylline as test compounds and figures of merit for these compounds have been calculated. PMID:23261285

Rahmanian, A; Ghaziaskar, H S; Khayamian, T

2012-12-01

291

Silicon Isotope Separation by Distillation of Silicon Tetrafluoride  

Microsoft Academic Search

Silicon isotopes were separated by distilling silicon tetrafluoride in a 150-cm packed column at temperatures of 189–206 K. The data show a reverse isotope effect with heavy isotopes more volatile in this temperature range. At total reflux, the maximum column separations were 0.926 for \\/Si and 0.872 for Si\\/Si. Carbon monoxide was also distilled in the column to obtain an

Thomas R. Mills

1990-01-01

292

Mass transfer resistance in narrow-bore columns packed with 1.7 ? m particles in very high pressure liquid chromatography  

Microsoft Academic Search

Surprisingly, the mass transfer kinetic properties of columns packed with superficially porous particles are markedly different from those of columns packed with fully porous particles. The performances of 2.1mm×150mm columns packed with a new type of sub-2?m particles, the superficially porous 1.7?m Kinetex-C18, and with the classical 1.7?m BEH-C18 fully porous particles were measured and are discussed. The sample was

Fabrice Gritti; Georges Guiochon

2010-01-01

293

Carbon dioxide–air mixtures: mass transfer in recycling packed-bed absorption columns operating under high liquid flow rates  

Microsoft Academic Search

The absorption of carbon dioxide–air mixtures in water in a packed-bed recirculating absorption column with an inner diameter of 0.08m and a length of 1.20m was investigated. A model is derived and numerically solved for recycling packed-bed absorption systems in order to determine the overall mass transfer coefficients. The relationship between the KLa values calculated in this work and the

Vural Evren; Tuncay Ça?atay; Ahmet R. Özdural

1999-01-01

294

Effect of temperature and pH on biological oxidation of antifreeze coolant using a packed column aerator  

Microsoft Academic Search

Simulated wastewater containing 0.75% (v\\/v) antifreeze was treated biologically using a 0.18-m diameter packed column aerator with a 0.4-m higth packed bed of 20-mm polypropylene spheres. Effects of liquid temperature and pH on the biological oxygen demand (BOD?) removal were investigated. All experiments were performed under an air flux of 0.0080 kg.m-².s-¹ and a liquid flux of 14.8 kg.m-².s-¹. An

Syed M Nasir Naqvi

2005-01-01

295

Determination of raclopride in human plasma by on-column focusing packed capillary liquid chromatography–electrospray ionisation mass spectrometry  

Microsoft Academic Search

A packed capillary liquid chromatography–electrospray ionisation mass spectrometry method was developed for the quantitative determination of raclopride in human plasma samples. Plasma samples containing the drug and its isotopically substituted analogue (2H3)raclopride as internal standard were extracted on solid-phase extraction discs, evaporated and reconstituted in a solvent with less elution strength than the mobile phase. Packed capillary columns of 100

Benita H Forngren; Niklas Tyrefors; Karin E Markides; Bengt Långström

2000-01-01

296

Experimental validation of physico-chemical models of effective diffusion in chromatographic columns packed with superficially porous particles  

Microsoft Academic Search

The effective diffusion coefficient of a non-retained compound (uracil) was measured with the peak parking (PP) method for two series (4.6mm×100mm and 2.1mm×100mm) of six replicate columns packed with the same batch of superficially porous 2.6?m Kinetex-C18 particles. The abilities of four different models of effective diffusion in packed beds to account for the experimental data are compared. These models

Fabrice Gritti; Georges Guiochon

2011-01-01

297

Stable isotope fractionations during reactive transport of phosphate in packed-bed sediment columns.  

PubMed

Characterizing reactivity and fate of contaminants in subsurface environments that are isolated from direct visualization is a major challenge. Stable isotopes coupled with concentration could be used as a potential tool to quantitatively analyze the chemical variability of the contaminant during reactive transport processes in the subsurface environment. This study was aimed at determining whether abiotic reactions of phosphate during its transport involve fractionation of oxygen isotopes in phosphate (?(18)Op). It included the effects of solution chemistry and hydrodynamics on ?(18)Op values during phosphate transport through a packed-bed column prepared by using natural sediment collected from the Cape Cod aquifer in Massachusetts. Results show that the isotopic fractionation between effluent and influent phosphate at early stage of transport could be ~1.3‰ at higher flow rates with isotopically-light phosphate (P(16)O4) preferentially retained in the sediment column. This fractionation, however, decreased and became insignificant as more phosphate passed through the column. Mobilization of phosphate initially sorbed onto sediments caused a large kinetic isotopic fractionation with isotopically-light phosphate preferentially remobilized from the sediment column, but over longer time periods, this fractionation decreased and became insignificant as well. These results collectively suggest that abiotic reactive transport processes exert minimal influence on the ?(18)Op composition of subsurface systems. Alternatively, fluctuation in flow rate and subsequent remobilization of phosphate could be detectable through transient changes in ?(18)Op values. These findings extend the burgeoning application of ?(18)Op to identify the different sources and geochemical processes of phosphate in the subsurface environments. PMID:24055952

Jaisi, Deb P

2013-08-28

298

Stable isotope fractionations during reactive transport of phosphate in packed-bed sediment columns  

NASA Astrophysics Data System (ADS)

Characterizing reactivity and fate of contaminants in subsurface environments that are isolated from direct visualization is a major challenge. Stable isotopes coupled with concentration could be used as a potential tool to quantitatively analyze the chemical variability of the contaminant during reactive transport processes in the subsurface environment. This study was aimed at determining whether abiotic reactions of phosphate during its transport involve fractionation of oxygen isotopes in phosphate (?18Op). It included the effects of solution chemistry and hydrodynamics on ?18Op values during phosphate transport through a packed-bed column prepared by using natural sediment collected from the Cape Cod aquifer in Massachusetts. Results show that the isotopic fractionation between effluent and influent phosphate at early stage of transport could be ~ 1.3‰ at higher flow rates with isotopically-light phosphate (P16O4) preferentially retained in the sediment column. This fractionation, however, decreased and became insignificant as more phosphate passed through the column. Mobilization of phosphate initially sorbed onto sediments caused a large kinetic isotopic fractionation with isotopically-light phosphate preferentially remobilized from the sediment column, but over longer time periods, this fractionation decreased and became insignificant as well. These results collectively suggest that abiotic reactive transport processes exert minimal influence on the ?18Op composition of subsurface systems. Alternatively, fluctuation in flow rate and subsequent remobilization of phosphate could be detectable through transient changes in ?18Op values. These findings extend the burgeoning application of ?18Op to identify the different sources and geochemical processes of phosphate in the subsurface environments.

Jaisi, Deb P.

2013-11-01

299

Simulation and analysis of extractive distillation process in a valve tray column using the rate based model  

Microsoft Academic Search

Valve trays are becoming popular in the chemical process industries owing to their flexibility to handle a wide range of vapor\\u000a throughputs. Using the rigorous rate based model, the importance of the non-equilibrium approach is demonstrated for a typical\\u000a extractive distillation process in a Glitsch V-1 valve tray column. Simulation results based on an in-house developed code\\u000a indicated that the

Sasmita Pradhan; Aravamudan Kannan

2005-01-01

300

Packed-column supercritical fluid chromatography: Quantitative determination of uranium without liquid waste generation  

SciTech Connect

A new procedure for the determination of uranium by packed-column supercritical fluid chromatography is proposed. A nonfluorinated chelating agent selective for copper and uranium, the 2,6-diacetylpyridine bis(benzoylhydrazone), has been chosen. We have studied its chromatographic properties on different stationary phases and the influence of the methanol content in the carbon dioxide mobile phase. The separation of the metal compounds was conducted with and without solvent injection. A calibration curve was obtained for uranium in the range of 52-323 ng injected. The accuracy of the method is 0.5%, the repeatability 4%. The same studies were performed with a new compound, diacetyl-2,6 pyridine bis(4-tert-butyl benzoylhydrazone). An increase in retention and efficiency was then observed. 30 refs., 5 figs., 3 tabs.

Martin-Daguet, V. [Commissariat a l`Energie Atomique, Gif sur Yvette (France); Gasnier, P. [Cogema, Bagnols sur Ceze (France); Caude, M. [Ecole Superieure de physique et de Chimie Industrielles de la ville de Paris, Paris (France)

1997-02-01

301

Boron isotope fractionation in liquid chromatography with boron-specific resins as column packing material  

SciTech Connect

Boron-specific resins with n-methyl glucamine as the functional group were used as column packing material of liquid chromatography for boron isotope separation. The shapes of chromatograms in reverse breakthrough experiments were heavily dependent on the pH of the eluents, and there existed a pH value at which a chromatogram of the displacement type was realized nearly ideally. The value of the single-stage separation factor for the boron isotopes varied between 1.010 and 1.022, depending on the temperature and the form of the resins. The existence of the three-coordinate boron species in addition to the four-coordinate species in the resin phase is suggested.

Oi, Takao; Shimazaki, Hiromi; Ishii, Reiko [Sophia Univ., Tokyo (Japan); Hosoe, Morikazu [National Defense Academy, Kanagawa (Japan)

1997-07-01

302

Reparametrized ARX models for predictive control of staged and packed bed distillation columns  

Microsoft Academic Search

This work is aimed at the development of reparametrized ARX type models for high dimensional and distributed parameter systems. To keep data length small while identifying a model with ARX structure, the feasibility of reparametrizing ARX models using the fractional order differential operators and orthonormal basis filters is explored. The identified noise model is further used for developing a novel

M. Muddu; Anuj Narang; Sachin C. Patwardhan

2010-01-01

303

Modeling of the mass-transfer kinetics in chromatographic columns packed with shell and pellicular particles.  

PubMed

The equations of the general rate model of chromatography and those of simple models (the POR, equilibrium-dispersive, and transport-dispersive models) are derived for beds packed with shell particles. Shell particles are made of a solid, nonporous core surrounded by a shell of a porous material that has properties similar to those of the fully porous materials conventionally used in HPLC. These equations have no algebraic solutions, but the moments of the peaks eluted under linear conditions can be calculated, affording the HETP equation for these columns. The discussion of the contribution to the HETP of the mass-transfer resistances shows that shell particles exhibit much lower plate heights for large molecular size compounds (e.g., peptides and proteins) than do fully porous particles, this advantage increasing with decreasing thickness of the shell. In contrast, the efficiencies of columns packed with shell particles and with fully porous particles having the same diameters are nearly the same for low molecular weight compounds. In practice, the gain in efficiency due to the use of shell particles to separate high molecular weight compounds does not depend on the thickness of the shell provided that this thickness does not exceed 30-40% of the particle diameter. For larger thicknesses, it decreases with increasing thickness. Shell particles can also be used in preparative chromatography. For compounds that have a high internal mass-transfer resistance, the gain in efficiency compensates the reduction in sample capacity due to the lower volume of porous adsorbent. For proteins like BSA, the production rate could be doubled. The gain decreases with decreasing mass-transfer resistance, e.g., with decreasing molecular weight. PMID:17492836

Kaczmarski, Krzysztof; Guiochon, Georges

2007-05-11

304

In situ measurements of the static liquid holdup in Katapak- SP 12 TM packed column using X-ray tomography  

Microsoft Academic Search

Static liquid holdup was determined in situ, in a column packed with Katapak-SP12TM elements, using a non-intrusive X-ray tomographic technique. Experiments were performed in a 10cm diameter PVC column with the air–water system. The technique allows a local determination of the various liquid holdup as well as of the capillary height, without dismantling the elements. Results are in good agreement

Michel Crine; Anil K. Saroha; Dominique Toye; Pierre Marchot

2007-01-01

305

Packed-bed columns with dye-affinity microbeads for removal of heavy metal ions from aquatic systems  

Microsoft Academic Search

A dye ligand Cibacron Blue F3GA, was covalently coupled with polyhydroxyethylmethacrylate (PHEMA) microbeads in the 150–200 ?m particle size range. The sorbent carrying 22.3 ?mol Cibacron Blue F3GA per gram of polymer was then used to remove Pb(II), Cd(II), Cu(II) and Zn(II) from aqueous solutions in a packed-bed column system. Heavy metal ion adsorption capacity of the column was investigated

Özgen Saatçilar; Nuray ?atiro?lu; Sema Bekta?; Ömer Genç; Adil Denizli

2002-01-01

306

Determination of effective mass transfer coefficient ( k c ) of patulin adsorption on activated carbon packed bed columns with recycling  

Microsoft Academic Search

In this study, a simple and effective technique for determining overall mass transfer coefficients in fixed bed sorption columns with recycling is presented. The overall mass transfer coefficient (Kc) of patulin for adsorption on activated carbon packed columns were determined at different flow rates. The Kc values increased from 4.74 × 10?2 to 12.96 × 10?2 cm s?1 when the

Mehmet Mutlu; Vural Gökmen

1998-01-01

307

Separation of parent homopolymers from diblock copolymers by liquid chromatography under limiting conditions of desorption 3. Role of column packing  

Microsoft Academic Search

The novel separation method, liquid chromatography under limiting conditions of desorption, LC LCD enables rapid one-step discrimination of both parent homopolymers from diblock copolymers. The low-molecular admixtures\\/impurities can be base-line separated, as well. The general rules for selection of the LC LCD columns are reviewed. Bare silica gel column packings are discussed in detail. Selected examples of separation are presented.

Dušan Berek

2010-01-01

308

Use of a Packed-Column Bioreactor for Isolation of Diverse Protease-Producing Bacteria from Antarctic Soil  

Microsoft Academic Search

Seventy-five aerobic heterotrophs have been isolated from a packed-column bioreactor inoculated with soil from Antarctica. The column was maintained at 10°C and continuously fed with a casein-containing medium to enrich protease producers. Twenty-eight isolates were selected for further characterization on the basis of morphology and production of clearing zones on skim milk plates. Phenotypic tests indicated that the strains were

Nathalie Wery; Ursula Gerike; Ajay Sharman; Julian B. Chaudhuri; David W. Hough; Michael J. Danson

2003-01-01

309

Interaction between titanium and phosphoproteins revealed by chromatography column packed with titanium beads.  

PubMed

The biochemical mechanism behind the strong binding between titanium and living bone has not been fully elucidated, in spite of worldwide clinical application of this phenomenon. We hypothesized that one of the core mechanisms may reside in the interaction between certain proteins in the host tissues and the implanted titanium. To verify the interaction between titanium and proteins, we chose the technique of chromatography in that titanium spherical beads (45 ?m) were packed into a column to obtain a bed volume of 16×50 mm, which was eluted with phosphate buffered saline (PBS) and a straight gradient system made by using PBS and 25 mM NaOH. Fetal calf serum, albumin, lysozyme, casein, phosvitin and dentin phosphoprotein (phosphophoryn) were applied to the column. Most part of albumin and lysozyme eluted with the breakthrough peak, indicating practically no affinity to titanium. Fetal bovine serum also eluted mostly as the breakthrough peak, but distinct retained peak was observed. On the other hand, ?-casein, phosvitin and phosphophoryn exhibited a distinct retained peak separated from the breakthrough peak. We proposed that phosphate groups (phosphoserines) in the major phosphoproteins, ?-casein, phosvitin and phosphophoryn may be involved in the binding of these proteins with titanium. PMID:23023145

Kuboki, Yoshinori; Furusawa, Toshitake; Sato, Masaaki; Sun, Yongkun; Unuma, Hidero; Fujisawa, Ryuichi; Abe, Shigeaki; Akasaka, Tsukasa; Watari, Fumio; Takita, Hiroko; Sammons, Rachel

2012-01-01

310

Transport of viruses through saturated and unsaturated columns packed with sand  

USGS Publications Warehouse

Laboratory-scale virus transport experiments were conducted in columns packed with sand under saturated and unsaturated conditions. The viruses employed were the male-specific RNA coliphage, MS2, and the Salmonella typhimurium phage, PRD1. The mathematical model developed by Sim and Chrysikopoulos (Water Resour Res 36:173-179, 2000) that accounts for processes responsible for removal of viruses during vertical transport in one-dimensional, unsaturated porous media was used to fit the data collected from the laboratory experiments. The liquid to liquid-solid and liquid to air-liquid interface mass transfer rate coefficients were shown to increase for both bacteriophage as saturation levels were reduced. The experimental results indicate that even for unfavorable attachment conditions within a sand column (e.g., phosphate-buffered saline solution; pH = 7.5; ionic strength = 2 mM), saturation levels can affect virus transport through porous media. ?? Springer Science+Business Media B.V. 2008.

Anders, R.; Chrysikopoulos, C. V.

2009-01-01

311

Investigation of carryover of peptides in nano-liquid chromatography/mass spectrometry using packed and monolithic capillary columns.  

PubMed

This article relates on reversed-phase column technology as the main cause of carryover in the LC-MS/MS analysis of proteomics samples. The separation performance and column carryover was investigated using four capillary columns with different morphologies by monitoring the remaining traces of tryptic peptides of bovine serum albumin in subsequent blank LC-MS runs. The following trend in column carryover was observed: capillary column packed with 3?m porous C18 particles?2.7?m fused-core C18 packed column>silica C18 monolith?poly(styrene-co-divinylbenzene) monolith. This is mainly related to the intrinsic properties of the different chromatographic materials, related to surface area and the presence and size of mesopores (stagnant zones where mass transfer is controlled by diffusion). Both isocratic and gradient wash steps with 2-propanol/acetonitrile mixtures were not effective to reduce column carryover. An isocratic wash step using a high acetonitrile percentage or blank gradient reduced carryover with approximately 50%. Nevertheless, it is important to note that effects of column carryover were still observed in a fifth subsequent gradient blank. Although the polymer monolith clearly outperformed the silica materials in terms of carryover, this material exhibited also the lowest loadability, which may be a disadvantage when profiling proteomics mixtures with a broad dynamic range. PMID:23261823

Dolman, Sebastiaan; Eeltink, Sebastiaan; Vaast, Axel; Pelzing, Matthias

2012-11-26

312

COED Transactions, Vol. X, No. 5, May 1978. STAGEF, A Program to Compute the Internal Variables of an Operating Distillation Column.  

ERIC Educational Resources Information Center

|A digital computer program, STAGEF, designed for use with the distillation experiments in a typical undergraduate Chemical Engineering laboratory in Unit Operations is explained. The program enables the student to determine the rate of liquid overflow and vapor boil-up which leaves each tray within the distillation column. The student may also…

Marcovitz, Alan B., Ed.

313

COED Transactions, Vol. X, No. 5, May 1978. STAGEF, A Program to Compute the Internal Variables of an Operating Distillation Column.  

ERIC Educational Resources Information Center

A digital computer program, STAGEF, designed for use with the distillation experiments in a typical undergraduate Chemical Engineering laboratory in Unit Operations is explained. The program enables the student to determine the rate of liquid overflow and vapor boil-up which leaves each tray within the distillation column. The student may also…

Marcovitz, Alan B., Ed.

314

Elucidation of retention mechanisms on hypercrosslinked polystyrene used as column packing material for high-performance liquid chromatography  

Microsoft Academic Search

Establishing of basic retention mechanisms was considered the key target during the development of new column packing materials. To extract, from an appropriate retention data matrix on hypercrosslinked polystyrene Chromalite 5HGN, certain factors that can be brought in an obvious correspondence with known retention mechanisms, the principal component analysis (PCA) was applied. The approach was used to elucidate the adsorption

C. S. Sychov; M. M. Ilyin; V. A. Davankov; K. O. Sochilina

2004-01-01

315

Transport of biocolloids in water saturated columns packed with sand: Effect of grain size and pore water velocity  

Microsoft Academic Search

The main objective of this study was to evaluate the combined effects of grain size and pore water velocity on the transport in water saturated porous media of three waterborne fecal indicator organisms (Escherichia coli, MS2, and ?X174) in laboratory-scale columns packed with clean quartz sand. Three different grain sizes and three pore water velocities were examined and the attachment

Vasiliki I. Syngouna; Constantinos V. Chrysikopoulos

2011-01-01

316

Determination of kinetic parameters in the biosorption of copper(II) on Cladophora sp., in a packed bed column reactor  

Microsoft Academic Search

In this study, the biosorption of copper(II) ions to the green alga Cladophora sp. was investigated in a packed bed column reactor as a function of flow rate and inlet copper(II) concentration. These two parameters affected the external mass transfer and adsorption rates directly. Mass transfer coefficients were determined from the Wakao Equation evaluating the breakthrough curves obtained at different

Z. Aksu; T. Kutsal

1998-01-01

317

Retention Mechanism Studies on Packed Column Supercritical Fluid Chromatography (pSFC) and Related Unified Chromatography Techniques  

Microsoft Academic Search

Packed column SFC (pSFC) has experienced tremendous growth as an analytical technique over the past two decades. Different studies of the retention mechanisms are reviewed to provide a better understanding on the use of supercritical fluids in practical separation science for the general practitioners of pSFC. The importance of various chromatographic parameters is evaluated; different types of retention models are

Yan Wu

2005-01-01

318

Determination of the effective transport coefficients for the separation of binary mixtures of organic compounds into packed thermal diffusion columns  

Microsoft Academic Search

Thermal diffusion in packed columns (TPC) is a process that could be used in the industry of separation, but some phenomenological aspects of this phenomenon are yet to be studied. This paper presents the results from physical investigations confronting experimental data to quantitative tools (analytical solution, computer model). It is shown that the classical approach of TPC with the transport

P. Costesèque

1996-01-01

319

Silver ion chromatography using solid-phase ex- traction columns packed with a bonded-sulfonic acid phase  

Microsoft Academic Search

Commercial solid-phase extraction columns packed with a stationary phase with bonded benzenesulfonic acid groups are readily converted to the silver ion form and can then be used for silver ion chromatography of lipids. To illustrate the utility of such procedures, methyl ester derivatives of fatty acids with zero to six double bonds were separated from each other by a simple

William W. Christie

320

Utilization of the dry impact blending method to prepare irregularly shaped particles for high-performance liquid chromatographic column packings  

Microsoft Academic Search

The use of the dry impact blending method to prepare various materials for HPLC column packings that might otherwise be unsuitable is proposed. Crystalline hydroxyapatite (HA) was adopted as a model of a useful but fragile, irregularly shaped material and was embedded on the surface of polyethylene beads by impact blending. The resulting HA composites were evaluated for the crystallinity

Futaba Honda; Hirotaka Honda; Masumi Koishi

1995-01-01

321

Preparation and evaluation of magnesia-coated silica as column packing material for high-performance liquid chromatography  

Microsoft Academic Search

The preparation of a mixed oxide gel composed of silica and magnesia was attempted by a coating method in order to develop a useful column packing material for liquid chromatography. The physical properties of the gels obtained remained almost the same as those of the native silica gel, but the surface silanol groups and the acid strength both changed, depending

Kazunori Nobuhara; Mikio Kato; Motoshi Nakamura; Masayoshi Takami; Shoji Kaneko

1995-01-01

322

Kinetic investigation of narrow-bore columns packed with prototype sub-2 ?m superficially porous particles with various shell thickness.  

PubMed

The recent successful breakthrough of sub-3 ?m shell particles in HPLC has triggered considerable research efforts toward the design of new brands of core-shell particles. We investigated the mass transfer mechanism of a few analytes in narrow-bore columns packed with prototype 1.7 ?m shell particles, made of 1.0, 1.2, and 1.4 ?m solid nonporous cores surrounded by porous shells 350, 250, and 150 nm thick, respectively. Three probe solutes, uracil, naphthalene, and insulin, were chosen to assess the kinetic performance of these columns. Inverse size exclusion chromatography, peak parking experiments, and the numerical integration of the experimental peak profiles were carried out in order to measure the external, internal, and total column porosities, the true bulk diffusion coefficients of these analytes, the height equivalent to a theoretical plate, the longitudinal diffusion term, and the trans-particle mass transfer resistance term. The residual eddy diffusion term was measured by difference. The results show the existence of important trans-column velocity biases (7%) possibly due to the presence of particle multiplets in the slurry mixture used during the packing process. Our results illustrates some of the difficulties encountered by scientists preparing and packing shell particles into narrow-bore columns. PMID:21872253

Gritti, Fabrice; Omamogho, Jesse; Guiochon, Georges

2011-07-23

323

Comparison of general rate model with a new model—artificial neural network model in describing chromatographic kinetics of solanesol adsorption in packed column by macroporous resins  

Microsoft Academic Search

Herein, two models, the general rate model taking into account convection, axial dispersion, external and intra-particle mass transfer resistances and particle size distribution (PSD) and the artificial neural network model (ANN) were developed to describe solanesol adsorption process in packed column using macroporous resins. First, Static equilibrium experiments and kinetic experiments in packed column were carried out respectively to obtain

Xueling Du; Qipeng Yuan; Jinsong Zhao; Ye Li

2007-01-01

324

Fundamental chromatographic equations designed for columns packed with very fine particles and operated at very high pressures applications to the prediction of elution times and the column efficiencies  

SciTech Connect

The wall temperatures of three Acquity-BEH-C{sub 18}columns (2.1 mm x 50, 100, and 150 mm) and the temperature of the incoming eluent were maintained constant at 289 K, using a circulating water heat exchanger. The retention times and the band broadening of naphtho[2,3-a]pyrene were measured for each column as a function of the flow rate applied. Pure acetonitrile was used as the eluent. The flow rate dependence of neither elution volumes nor bandwidths can be accounted for by classical models of retention and HETP, respectively, since these models assume columns to be isothermal. Because the heat generated by friction of the eluent against the column bed increases with increasing flow rate, the column bed cannot remain isothermal at high flow rates. This heat is evacuated radially and/or longitudinally by convection, conduction, and radiation. Radial and axial temperature gradients are formed, which are maximum and minimum, respectively, when the temperature of the column wall is kept uniform and constant. The retention times that we measured match well with the values predicted based on the temperature distribution along and across the column, which we calculated and on the temperature dependence of the retention for the same column operated isothermally (i.e., at very low flow rate). The rate of band spreading varies along non-isothermal columns, so the HETP can only be defined locally. It is a function of the axial coordinate. A new contribution is needed to account for the radial thermal heterogeneity of the column, hence the radial distribution of the flow velocities, which warps the elution band. A new model, based on the general dispersion theory of Aris, allows a successful prediction of the unusually large bandwidths observed with columns packed with fine particles, operated at high flow rates, hence high inlet pressures.

Gritti, Fabrice [University of Tennessee, Knoxville (UTK); Guiochon, Georges A [ORNL

2008-01-01

325

Fundamental chromatographic equations designed for columns packed with very fine particles and operated at very high pressures. Applications to the prediction of elution times and the column efficiencies.  

PubMed

The wall temperatures of three Acquity-BEH-C18columns (2.1 mm x 50, 100, and 150 mm) and the temperature of the incoming eluent were maintained constant at 289 K, using a circulating water heat exchanger. The retention times and the band broadening of naphtho[2,3-a]pyrene were measured for each column as a function of the flow rate applied. Pure acetonitrile was used as the eluent. The flow rate dependence of neither elution volumes nor bandwidths can be accounted for by classical models of retention and HETP, respectively, since these models assume columns to be isothermal. Because the heat generated by friction of the eluent against the column bed increases with increasing flow rate, the column bed cannot remain isothermal at high flow rates. This heat is evacuated radially and/or longitudinally by convection, conduction, and radiation. Radial and axial temperature gradients are formed, which are maximum and minimum, respectively, when the temperature of the column wall is kept uniform and constant. The retention times that we measured match well with the values predicted based on the temperature distribution along and across the column, which we calculated and on the temperature dependence of the retention for the same column operated isothermally (i.e., at very low flow rate). The rate of band spreading varies along non-isothermal columns, so the HETP can only be defined locally. It is a function of the axial coordinate. A new contribution is needed to account for the radial thermal heterogeneity of the column, hence the radial distribution of the flow velocities, which warps the elution band. A new model, based on the general dispersion theory of Aris, allows a successful prediction of the unusually large bandwidths observed with columns packed with fine particles, operated at high flow rates, hence high inlet pressures. PMID:18775540

Gritti, Fabrice; Guiochon, Georges

2008-08-03

326

Fast and universal HPLC method for determination of permethrin in formulations using 1.8-?m particle-packed column and performance comparison with other column types.  

PubMed

An HPLC method has been developed for the fast separation and quantification of permethrin using C18 column packed with 1.8 µm particles. The method is specific with good resolution to degradation products and to other present components. It has acceptable validation results. The run time is 4.5 min (or may be within 1.6 min is rapid resolution mode) with an organic solvent consumption of 3.6 mL per run. The method has been applied to samples of formulations for various uses: mattress cleaner, shampoo, and veterinary powder. The performance of the applied column is compared with other common column types. The relationships between linear velocity of the mobile phase (u) and resolution factor (Rs), back-pressure (?P), and efficiency (H) are presented. The experimental data shows the advantages of 1.8-µm particle columns to be a significant reduction in solvent consumption (by factor of 4.4 and 1.5) and a reduction in run-time (by factor 4.7 and 1.5), and the weaknesses are a high back-pressure and lower efficiency. Finally, it has been shown that use of 1.8-µm particle packed columns with conventional HPLC systems is possible, but with limitations in mobile phase flow-rate. PMID:22291055

Shishovska, Maja A; Stefova, Marina T

2012-01-01

327

Fast and Universal HPLC Method for Determination of Permethrin in Formulations Using 1.8-um Particle-Packed Column and Performance Comparison with Other Column Types  

PubMed Central

An HPLC method has been developed for the fast separation and quantification of permethrin using C18 column packed with 1.8 µm particles. The method is specific with good resolution to degradation products and to other present components. It has acceptable validation results. The run time is 4.5 min (or may be within 1.6 min is rapid resolution mode) with an organic solvent consumption of 3.6 mL per run. The method has been applied to samples of formulations for various uses: mattress cleaner, shampoo, and veterinary powder. The performance of the applied column is compared with other common column types. The relationships between linear velocity of the mobile phase (u) and resolution factor (Rs), back-pressure (?P), and efficiency (H) are presented. The experimental data shows the advantages of 1.8-µm particle columns to be a significant reduction in solvent consumption (by factor of 4.4 and 1.5) and a reduction in run-time (by factor 4.7 and 1.5), and the weaknesses are a high back-pressure and lower efficiency. Finally, it has been shown that use of 1.8-µm particle packed columns with conventional HPLC systems is possible, but with limitations in mobile phase flow-rate.

Shishovska, Maja A.; Stefova, Marina T.

2012-01-01

328

Reactive dividing wall distillation columns: Simulation and implementation in a pilot plant  

Microsoft Academic Search

We performed steady state and dynamic simulations of a reactive Petlyuk column through an equivalent reactive dividing wall column (RDWDC). In the case of the reaction between ethanol and acetic acid catalyzed by sulfuric acid to produce ethyl acetate and water, we have found that the reactive Petlyuk column can achieve set point changes in two control loops of temperature.

Salvador Hernández; Rodrigo Sandoval-Vergara; Fabricio Omar Barroso-Muñoz; Rodolfo Murrieta-Dueñas; Héctor Hernández-Escoto; Juan Gabriel Segovia-Hernández; Vicente Rico-Ramirez

2009-01-01

329

PREPARATION OF ULTRA-PURE SUCCINONITRILE BY COUNTERCURRENT DISTILLATION FOR CRYSTAL GROWTH  

Microsoft Academic Search

We developed the purification method to produce ultra-pure succinonitrile by multiple countercurrent distillations. The distillation column used was 25?mm in diameter and 110?cm in the packed height with Heli-Pak® packing (0·05” × 0·10” × 0·10”, packing factor+ 960). Typical operational conditions of each stage are as follows: condenser temperature 65 °C, reboiler temperature 160 °C, head pressure 50?m Torr or

YOUN-WOO LEE; RAMAGOPAL ANANTH; WILLIAM N. GILL

1996-01-01

330

Evaluation of a subsurface oxygenation technique using colloidal gas aphron injections into packed column reactors  

SciTech Connect

Bioremediation may be a remedial technology capable of decontaminating subsurface environments. The objective of this research was to evaluate the use of colloidal gas aphron (CGA) injection, which is the injection of micrometer-size air bubbles in an aqueous surfactant solution, as a subsurface oxygenation technique to create optimal growth conditions for aerobic bacteria. Along with this, the capability of CGAs to act as a soil-washing agent and free organic components from a coal tar-contaminated matrix was examined. Injection of CGAs may be useful for remediation of underground coal gasification (UCG) sites. Because of this, bacteria and solid material from a UCG site located in northeastern Wyoming were used in this research. Colloidal gas aphrons were generated and pumped through packed column reactors (PCRS) containing post-burn core materials. For comparison, PCRs containing sand were also studied. Bacteria from this site were tested for their capability to degrade phenol, a major contaminant at the UCG site, and were also used to bioaugment the PCR systems. In this study we examined: (1) the effect of CGA injection on dissolved oxygen concentrations in the PCR effluents, (2) the effect of CGA, H[sub 2]O[sub 2], and phenol injections on bacterial populations, (3) the stability and transport of CGAs over distance, and (4) CGA injection versus H[sub 2]O[sub 2] injection as an oxygenation technique.

Wills, R.A.; Coles, P.

1991-11-01

331

Evaluation of a subsurface oxygenation technique using colloidal gas aphron injections into packed column reactors  

SciTech Connect

Bioremediation may be a remedial technology capable of decontaminating subsurface environments. The objective of this research was to evaluate the use of colloidal gas aphron (CGA) injection, which is the injection of micrometer-size air bubbles in an aqueous surfactant solution, as a subsurface oxygenation technique to create optimal growth conditions for aerobic bacteria. Along with this, the capability of CGAs to act as a soil-washing agent and free organic components from a coal tar-contaminated matrix was examined. Injection of CGAs may be useful for remediation of underground coal gasification (UCG) sites. Because of this, bacteria and solid material from a UCG site located in northeastern Wyoming were used in this research. Colloidal gas aphrons were generated and pumped through packed column reactors (PCRS) containing post-burn core materials. For comparison, PCRs containing sand were also studied. Bacteria from this site were tested for their capability to degrade phenol, a major contaminant at the UCG site, and were also used to bioaugment the PCR systems. In this study we examined: (1) the effect of CGA injection on dissolved oxygen concentrations in the PCR effluents, (2) the effect of CGA, H{sub 2}O{sub 2}, and phenol injections on bacterial populations, (3) the stability and transport of CGAs over distance, and (4) CGA injection versus H{sub 2}O{sub 2} injection as an oxygenation technique.

Wills, R.A.; Coles, P.

1991-11-01

332

Separation of phospholipids from hen egg yolk by short packed silica gel column chromatography.  

PubMed

Short packed silica gel column chromatography has been performed to optimize the production of phosphatidylethanolamine (PE) and phosphatidylcholine (PC) from hen egg yolk with very low or no toxic solvents. The effects of silica type, sample loading amount, dimension of the glass chromatotube, and mobile phase compositions were investigated and high separation efficiency was achieved: gradient elution as 200 mL ethanol followed by 300 mL 95% ethanol to fractionate PE and PC after neutral lipids (NL) removed by 120 mL ethyl acetate, 40 mm silica gel (54 to 74 ?m) bed height of the chromatotube with 22 mm inner dia (ID), and 0.25 g sample loading amount. By this procedure, 3.69 g PE and 2.88 g PC per 100 g egg yolk lipids were obtained, respectively. The refined PE and PC were identified by high-performance liquid chromatography/ultraviolet detector (HPLC-UV) with purity over 96%. The fatty acids in egg yolk revealed that PE and PC characterized higher ratios of n- 6/n- 3 (PE, 7.41; PC, 8.99). 18:2 n- 6 of PC (15.21%) predominated over PE (10.29%), whereas the level of 20:4 n- 6 of PC (8.78%) was lower than PE (15.67%). PMID:22900891

Lei, Lin; Li, Jing; Hu, Jiang-ning; Liu, Rong; Fan, Ya-wei; Tang, Liang; Deng, Ze-yuan

2012-08-17

333

Evaluation of packed column gas chromatography with electron capture detector quantitation for polychlorinated biphenyls  

SciTech Connect

A packed column gas chromatography with electron capture detector (PGC/ECD) technique was developed to analyze samples for polychlorinated biphenyl (PCB) concentration. The goal was to determine whether an alternative technique could achieve better efficiency and accuracy than the method of Webb and McCall. This technique utilizes a table of adjusted relative response factors (ARRFs) derived from the relative retention times (RRTs) and relative response factors (RRFs) found in the literature for all 209 PCBs. Application of this technique requires that retention times observed from one subset of PCB congeners be compared to the literature RRTs from the same set of PCB congeners. The comparison is developed into a least squares linear regression model which estimates the ARRF to use at a given time during an analysis. The ARRF selected is then used to adjust the sample PCB concentration on a peak-by-peak basis. A variety of PCB sample types were analyzed using both the ARRF technique and the Webb and McCall method. Results indicated that the precision and accuracy of the ARRF technique were superior to Webb and McCall.

Turner, S.T. (Midwest Research Inst., Kansas City, MO (USA))

1991-03-01

334

Modeling and simulation of a packed column for NO{sub x} absorption with hydrogen peroxide  

SciTech Connect

The absorption of dilute NO{sub x} gas was studied, at atmospheric pressure, in an industrial column packed with 25-mm plastic Pall rings. The scrubbing liquid was a dilute hydrogen peroxide solution. NO{sub x} removal efficiencies of 75--91% were obtained for gas mixtures with partial pressures of NO{sub x} in the range of 62.8--460 N/m{sup 2}. A model was developed on the basis of equilibrium, chemical reactions, mass transfer in gas and liquid phases, and consideration of HNO{sub 2} and NO oxidation by H{sub 2}O{sub 2} in the liquid phase. The removal efficiencies calculated using this model fairly agreed with the experimental data. The HNO{sub 2} formation in the gas phase largely determines the NO{sub x} absorption rate. Its oxidation by H{sub 2}O{sub 2} improves the NO{sub x} removal. The influences of various parameters in the NO{sub x} removal efficiency are discussed from numerical simulations.

Paiva, J.L. de; Kachan, G.C. [Univ. of Sao Paulo (Brazil). Dept. of Chemical Engineering

1998-02-01

335

Evaluation of bioemulsifier mediated Microbial Enhanced Oil Recovery using sand pack column.  

PubMed

Bacillus licheniformis K125, isolated from an oil reservoir, produces an effective bioemulsifier. The crude bioemulsifier showed 66% emulsification activity (E(24)) and reduced the surface tension of water from 72 to 34 mN/m. It contains substantial amount of polysaccharide, protein and lipid. This bioemulsifier is pseudoplastic non-Newtonian in nature. It forms oil in water emulsion which remains stable at wide range of pH, temperature and salinity. It gave 43+/-3.3% additional oil recovery upon application to a sand pack column designed to simulate an oil reservoir. This is 13.7% higher than that obtained from crude lipopeptide biosurfactants produced by the standard strain, Bacillus mojavensis JF2 and 8.5% higher than hot water spring isolate, Bacillus licheniformis TT42. The increased oil recovery obtained by using the crude bioemulsifier can be attributed to its combined surface and emulsification activity. Its mechanism of oil recovery must be similar to the mechanism exhibited by surfactant-polymer flooding process of chemical enhanced oil recovery. PMID:18625271

Suthar, Harish; Hingurao, Krushi; Desai, Anjana; Nerurkar, Anuradha

2008-06-18

336

Inconsistencies in dynamic models for ill-conditioned plants: Application to low-order models of distillation columns  

SciTech Connect

The paper addresses the problem of obtaining consistent dynamic models for certain ill-conditioned plants like distillation columns. Due to strong interactions there is often a single dominating slow mode (pole) that results in similar first-order responses for all outputs. Typically, models are identified on the basis of fitting individual responses, but unless special care is taken this will result in an inconsistent overall model with the slow pole repeated. It is shown that such models with excessive slow poles, although a reasonable approximation for open-loop dynamics, yield a poor prediction of the closed-loop behavior of the process, in particular under partial control.

Jacobsen, E.W.; Skogestad, S. (Univ. of Trondheim (Norway). Chemical Engineering)

1994-03-01

337

Investigation of the column performance of cadmium(II) biosorption by Cladophora crispata flocs in a packed bed  

SciTech Connect

In this study the biosorption of cadmium(II) ions to dried flocs of Cladophora crispata, a kind of green algae, was investigated in a packed bed column. The cadmium(II) removal performance of the column was investigated as a function of the cadmium(II)-bearing solution flow rate and the inlet cadmium(II) concentration. Removal and total removal percentages of cadmium(II) related to flow volume were determined by evaluating the breakthrough curves obtained at three different flow rates for two different constant inlet concentrations. At the lowest flow rate the effect of inlet cadmium(II) concentration on the column capacity was also investigated. Data confirmed that early saturation and lower cadmium(II) removals were observed at higher flow rates and at higher cadmium(II) concentrations. Column experiments also showed that maximum specific cadmium(II) uptake values of C. crispata flocs were as high as those of other biomass sorbents.

Aksu, Z.; Kutsal, T.; Caglar, A. [Hacettepe Univ., Ankara (Turkey). Chemical Engineering Dept.; Oezer, D.; Oezer, A. [Firat Univ., Elazig (Turkey). Chemical Engineering Dept.

1998-03-01

338

Simultaneous kinetic resolution of chiral propylene oxide and propylene glycol in a continuous reactive distillation column  

Microsoft Academic Search

Traditionally kinetic resolutions are conducted by batch processing to recover one of the desired enantiomers of the racemate, while the product formed by the resolution is discarded due to its low purity. However, chiral materials are economically valuable and simultaneously conducting the reaction and separation, using reactive distillation, allows for both a reactant enantiomer and a product enantiomer to be

Matthew J. Okasinski; Michael F. Doherty

2003-01-01

339

Equilibrium theory and nonlinear waves for reactive distillation columns and chromatographic reactors  

Microsoft Academic Search

A general framework for analyzing and understanding the dynamics of reactive separation processes is developed. The theory is based on the assumption of simultaneous phase and reaction equilibrium. It makes use of transformed concentration variables, which were first introduced by Doherty and co-workers for the steady state design of reactive distillation processes (Proc. Roy. Soc. London A 413 (1987a) 459).

S. Grüner; A. Kienle

2004-01-01

340

Practical comparison of LC columns packed with different superficially porous particles for the separation of small molecules and medium size natural products.  

PubMed

Commercial C(18) columns packed with superficially porous particles of different sizes and shell thicknesses (Ascentis Express, Kinetex, and Poroshell 120) or sub-2-?m totally porous particles (Acquity BEH) were systematically compared using a small molecule mixture and a complex natural product mixture as text probes. Significant efficiency loss was observed on 2.1-mm id columns even with a low dispersion ultra-high pressure liquid chromatography system. The Kinetex 4.6-mm id column packed with 2.6-?m particles exhibited the best overall efficiency for small molecule separations and the Poroshell 120 column showed better performance for mid-size natural product analytes. The Kinetex 2.1-mm id column packed with 1.7-?m particles did not deliver the expected performance and the possible reasons besides extra column effect have been proved to be frictional heating effect and poor column packing quality. Different column retentivities and selectivities have been observed on the four C(18) columns of different brands for the natural product separation. Column batch-to-batch variability that has been previously observed on the Ascentis Express column was also observed on the Kinetex and Poroshell 120 column. PMID:21936054

Yang, Peilin; McCabe, Terry; Pursch, Matthias

2011-09-21

341

Fast CEC-MS using poly(dimethylsiloxane) microinjector, short packed column, and low-sheath-flow interface.  

PubMed

A fast CEC-MS approach based on a microinjector and a short CEC column was developed. Poly(dimethylsiloxane) was used as the substrate for microinjector fabrication. A short capillary column (?5 cm) packed with 5 ?m octadecyl silica particles was inserted into the microinjector. The microinjector CEC device was interfaced to ESI-MS using a low-flow sheath liquid interface. The device delivers the advantages of sample introduction, pre-concentration, elution, and fast analysis as in chip-CEC yet avoids the difficulty of packing stationary material into the chip. The online pre-concentration and CEC-MS analysis capabilities of this device were demonstrated by analysis of a six-triazine mixture. A signal enhancement of 20-99-fold was achieved with a sample loading time of 180 s. PMID:21735549

Chen, Chao-Jung; Wang, Che-Wei; Her, Guor-Rong

2011-07-07

342

Kinetic investigation of narrow-bore columns packed with prototype sub-2 ?m superficially porous particles with various shell thickness  

Microsoft Academic Search

The recent successful breakthrough of sub-3?m shell particles in HPLC has triggered considerable research efforts toward the design of new brands of core-shell particles. We investigated the mass transfer mechanism of a few analytes in narrow-bore columns packed with prototype 1.7?m shell particles, made of 1.0, 1.2, and 1.4?m solid nonporous cores surrounded by porous shells 350, 250, and 150nm

Fabrice Gritti; Jesse Omamogho; Georges Guiochon

2011-01-01

343

Applicability of MCM-41 as column packing in HPLC for the evaluation of aluminum species in partially neutralized aluminum solutions  

Microsoft Academic Search

Separation of Al ionic species in partially neutralized aluminum solution was studied using HPLC technique in order to elucidate the applicability of MCM-41 as promising column packing. Three peaks observed in HPCL chromatogram were assigned to mononuclear aluminum cation (Al(mono)), tridecameric polycation (Al(13)), and polynuclear precursors of Al(OH)3 (Al(poly)) in the order of appearance. Overlapping of the peaks between Al(mono)

Takayoshi Shindo; Hirotaka Kudo; Shigeaki Kitabayashi; Sentaro Ozawa

2003-01-01

344

Removal of pollutant compounds from water supplies using ozone, ultraviolet light, and a counter, current packed column. Master's thesis  

SciTech Connect

Many water pollutants are determined to be carcinogenic and often appear in very low concentrations and still pose a health risk. Conventional water treatment processes cannot remove these contaminants and there is a great demand for the development of alternative removal technologies. The use of ozone and ultraviolet light in a counter current packed column could prove to be an effective treatment process to remove these contaminants.

Kelly, E.L.

1991-01-01

345

Experimental and theoretical analysis of heat and mass transfer in a packed column dehumidifier\\/regenerator with liquid desiccant  

Microsoft Academic Search

This paper presents the experimental tests and the theoretical analysis on the chemical dehumidification of air by a liquid desiccant and desiccant regeneration in an absorption\\/desorption column with random packing.The experimental set-up is fully described together with measurements, procedures, data reduction and accuracy. The experimental tests include dehumidification and desiccant regeneration runs carried out with the traditional hygroscopic salt solutions

G. A. Longo; A. Gasparella

2005-01-01

346

Liquid back-mixing in packed-bubble column reactors: a state-of-the-art correlation  

Microsoft Academic Search

The extent of liquid back-mixing in gas–liquid concurrent upflow packed-bubble column reactors is quantified in terms of an axial dispersion coefficient or its corresponding dimensionless Péclet number. Effects of reactor operating conditions on the axial dispersion coefficient are not properly accounted for by the available literature correlations, wherein most often the Péclet number is expressed solely in terms of the

Lamia Belfares; Miryan Cassanello; Bernard P. A. Grandjean

2001-01-01

347

New correlation for liquid hold-up of sodium citrate buffer solution in a Raschig ring packed column  

Microsoft Academic Search

Dynamic liquid hold-up was measured with an air\\/aqueous sodium citrate buffer solution at 20–40 °C, and an air\\/water system at 23 °C, in a 0.1 m diameter\\/1 m high glass column covered by a heat-isolating vacuum jacket and packed with 0.012 m nominal size ceramic Raschig rings. The superficial gas velocity range was extended to 1.2 m s?1. Experimental results

I. Bágyi; E. Márki; E. Békássy-Molnár

1996-01-01

348

Biodegradation kinetics of ferrous(II) cyanide complex ions by immobilized Pseudomonas fluorescens in a packed bed column reactor  

Microsoft Academic Search

Combined external mass transfer and intrinsic biodegradation effects on the observed biodegradation rate were investigated for ferrous (II) cyanide complex (ferrocyanide) ions removal with calcium–alginate gel immobilized Pseudomonas fluorescens in a packed bed column reactor. Assuming first-order biodegradation kinetics, observed first-order biodegradation rate constants (kp) were calculated at different flow rates. To investigate the effect of external film diffusion on

Arzu Y. Dursun; Zümriye Aksu

2000-01-01

349

Biosorption of Copper and Cadmium in Packed Bed Columns with Live Immobilized Fungal Biomass of Phanerochaete chrysosporium  

Microsoft Academic Search

Biosorption of copper (II) and cadmium (II) by live Phanerochaete chrysosporium immobilized by growing onto polyurethane foam material in individual packed bed columns over two successive cycles of sorption–desorption\\u000a were investigated in this study. Initial pH and concentrations of the metals in their respective solutions were set optimum\\u000a to each of those: 4.6 and 35 mg·l?1 in case of copper and

K. Pakshirajan; T. Swaminathan

2009-01-01

350

Biosorption of lead(II) and cadmium(II) by protonated Sargassum glaucescens biomass in a continuous packed bed column  

Microsoft Academic Search

Biosorption of lead(II) and cadmium(II) from aqueous solutions by protonated Sargassum glaucescens biomass was studied in a continuous packed bed column. The selective uptake of Pb2+ and Cd2+ was investigated in a binary system with initial concentration of 1mM for each metal ion. The selective uptake capacities of Pb2+ and Cd2+ at complete exhaustion point were obtained 1.18 and 0.22mmol\\/g,

Kazem Naddafi; Ramin Nabizadeh; Reza Saeedi; Amir Hossein Mahvi; Forough Vaezi; Kamyar Yaghmaeian; Azar Ghasri; Shahrokh Nazmara

2007-01-01

351

Packed bed column studies for the removal of synthetic dyes from textile wastewater using immobilised dead C. tropicalis  

Microsoft Academic Search

An efficient dye biosorbent was developed for the treatment of textile wastewater by entrapping dead cells of C. tropicalis, within sodium alginate matrix. The biosorbent performance was evaluated in packed bed column with different pH (3 to 6), wastewater strength (25%, 50% 75%), bed height (5cm–15cm) and flow rate (0.5mLmin?1 to 1mLmin?1). pH 5, undiluted wastewater, bed height 15cm and

D. Charumathi; Nilanjana Das

352

Sorption of heavy metals from electroplating effluent using immobilized biomass Trichoderma viride in a continuous packed-bed column  

Microsoft Academic Search

The sorption of heavy metals ions by immobilized Trichoderma viride biomass in a packed-bed column was studied. Fungal biomass T. viride was immobilized to Ca-alginate used for removal of Cr(VI), Ni(II) and Zn(II) ions from synthetic solutions and electroplating effluent. The experiments were conducted to study the effect of important design parameters such as bed height, flow rate and initial

Rajender Kumar; Divya Bhatia; Rajesh Singh; Suman Rani; Narsi R. Bishnoi

2011-01-01

353

Comparison of Packed Beds and Qiagen Columns for Recovering Trace Amounts of B. anthracis DNA from Liquid Suspensions  

Microsoft Academic Search

The goal of this work was to optimize and evaluate LLNL's in-bed amplification technology to improve the level of detection for suspensions containing trace amounts of anthracis DNA. The binding\\/cleaning performance of the packed bed is compared to the conventional commercial approach; Qiagen column cleanup and elution, followed by detection through an ex-situ amplification process. Five liquid suspensions were spiked

K Sorensen; E Arroyo; A Erler; A T Christian; D Camp; E K Wheeler

2006-01-01

354

Alkyl diol silica: restricted access pre-column packings for fast liquid chromatography-integrated sample preparation of biological fluids  

Microsoft Academic Search

A silica-based pre-column packed with a ‘restricted access material’ was used for fully automated solid-phase extraction of drugs and metabolites from untreated biological fluids via a simple valve-switching method. The bifunctional sorbent employed, alkyl diol silica, is characterised by a different chemical modification of the outer surface (diol groups) and the pore surface of the particles (alkyl chains: C4, C8

Christian Schäfer; Dieter Lubda

2001-01-01

355

Uptake of copper (II) ions from acidic aqueous solutions using a continuous column packed with microcapsules containing a ?-hydroxyoximic compound  

Microsoft Academic Search

In this paper, the uptake of Cu(II) ions from an acidic aqueous solution using a continuous column packed with microcapsules containing the chelating extractant LIX-860 N-IC was examined. A simple, economical method was employed to synthesise the microcapsules’ polymeric matrix consisting of an in situ radical polymerisation method followed by the subsequent impregnation of the extractant compound 5-nonylsalicylaldoxime. The microcapsules

C. Araneda; C. Basualto; J. Sapag; C. Tapia; D. Cotorás; F. Valenzuela

356

Packed-bed sorption of copper using spent animal bones: factorial experimental design, desorption and column regeneration  

Microsoft Academic Search

A two-level factorial experimental design method has been proposed to investigate the influence of the operating parameters in a packed-bed adsorption column. This technique has been applied to quantify the influence of bed-depth, influent flow rate, and influent metal concentration on break-through time during the removal of copper from aqueous solutions using spent animal bones. A factorial model has been

Sameer Al-Asheh; Nabil Abdel-Jabar; Fawzi Banat

2002-01-01

357

Practical aspects of fast reversed-phase high-performance liquid chromatography using 3 microm particle packed columns and monolithic columns in pharmaceutical development and production working under current good manufacturing practice.  

PubMed

The potential and limitations of fast reversed-phase high-performance liquid chromatographic separations for assay and purity of drug substances and drug products were investigated in the pharmaceutical industry working under current good manufacturing practice using particle packed columns and monolithic columns. On particle packed columns, the pressure limitation of commercially available HPLC systems was found to be the limiting factor for fast separations. On 3 microm particle packed columns, HPLC run times (run to run) for assay and purity of pharmaceutical products of 20 min could be achieved. As an interesting alternative, monolithic columns were investigated. Monolithic columns can be operated at much higher flow rates, thus allowing for much shorter run times compared to particle packed columns. Compared to particle packed columns, the analysis time could be reduced by a factor up to 6. However, some compounds investigated showed a dramatic loss of efficiency at higher flow rates. This phenomenon was observed for some larger molecules supporting the theory that mass transfer is critical for applications on monolithic columns. At flow rates above 3 ml/min some HPLC instruments showed a dramatic increase in noise, making quantifications at low levels impossible. For very fast separations on monolithic columns, the maximum data acquisition rate of the detector is the limiting factor. PMID:15146913

Gerber, Frederic; Krummen, Markus; Potgeter, Heiko; Roth, Alfons; Siffrin, Christoph; Spoendlin, Christoph

2004-05-21

358

Comparison of LC Columns Packed with 2.6 ?m Core-Shell and Sub2 ?m Porous Particles for Gradient Separation of Antibiotics  

Microsoft Academic Search

The recently introduced Kinetex C18 column packed with core-shell 2.6 ?m particles is declared to provide similar efficiency\\u000a and short analysis as Acquity BEH C18 column with 1.7 ?m porous particles. Unlike Acquity BEH C18 column, Kinetex C18 column\\u000a exhibited lower column backpressure making this column compatible to conventional LC systems. The performance of Kinetex C18\\u000a column (2.1 × 50 mm) and Acquity BEH C18

Tereza Tylová; Zden?k Kameník; Miroslav Flieger; Jana Olšovská

2011-01-01

359

Gas chromatographic separation of hydrogen isotopes on columns packed with alumina, modified alumina and sol-gel alumina.  

PubMed

The stationary phase of alumina adsorbents, prepared by different chemical processes, was used to study the separation behaviour of hydrogen isotopes. Three types of alumina, obtained by conventional hydroxide route alumina coated with silicon oxide and alumina prepared by internal gelation process (IGP), were used as packing material to study the separation of HT and T(2) in a mixture at various temperatures. The conventional alumina and silicon oxide coated alumina resolved HT and T(2) at 77K temperature with different retention times. The retention times on SiO(2) coated columns were found to be higher than those of other adsorbents. However, the column filled with IGP alumina was found to be ideal for the separation of HT and T(2) at 240 K. The peaks were well resolved in less than 5 min on this column. PMID:22169190

Naik, Y P; Gupta, N K; Pillai, K T; Rao, G A Rama; Venugopal, V

2011-11-10

360

Stability of high-performance liquid chromatography columns packed with poly(methyloctylsiloxane) sorbed and radiation-immobilized onto porous silica and zirconized silica  

Microsoft Academic Search

Reversed-phase packing materials were prepared from HPLC silica and from zirconized HPLC silica support particles having sorbed poly(methyloctylsiloxane) (PMOS) as the stationary phase. Portions of zirconized material were subjected to 80 kGy of ionizing radiation. Columns prepared from these packing materials were subjected to 5000 column volumes each of neutral and alkaline (pH 10) mobile phases, with periodic tests to

Lúcio Flávio Costa Melo; Carol H Collins; Kenneth E Collins; Isabel Cristina Sales Fontes Jardim

2000-01-01

361

Forensic analysis of 10 barbiturates in human biological samples using a new reversed-phase chromatographic column packed with 2micrometre porous microspherical silica-gel  

Microsoft Academic Search

A high-performance liquid chromatographic method has been developed for the forensic analysis of 10 frequently used barbiturates (BARs) (allobarbital, amobarbital, barbital, cyclobarbital, hexobarbital, metharbital, pentobarbital, phenobarbital, secobarbital and thiopental) using a recently developed reversed-phase column packed with 2-?m particles. The results show that the new ODS column packing gives higher sensitivity and a shorter analysis time than the conventional ODS

Einosuke Tanaka; Masaru Terada; Kozo Tanno; Shogo Misawa; Choei Wakasugi

1997-01-01

362

Capillary-electrochromatographic separations with copolymeric reversed-stationary phase and ion-exchanger-packed columns  

Microsoft Academic Search

A macroporous, spherical, 7 ?m, polystyrene–divinylbenzene (PS–DVB), reversed-phase adsorbent (PRP-1) was evaluated as a stationary phase for the capillary electrochromatographic (CEC) separation of neutral, acidic, and basic analytes of pharmaceutical interest. Electroosmotic flow (EOF) for a PRP-1 packed capillary is nearly constant over the pH 2 to 10 range and is higher than for a silica-based C18 packed capillary on

Yi Liu; Donald J Pietrzyk

2001-01-01

363

Dehumidification of Air by Aqueous Lithium Chloride in a Packed Column  

Microsoft Academic Search

A packed bed absorber-stripper system has been designed to dehumidify moist air by contact with aqueous solutions of lithium chloride. The packing material used in the study is 1.6 cm (5\\/8 inch) polypropylene Flexi rings, which have a surface to volume ratio of 342 m\\/m (104 ft\\/ft). The absorber is capable of handling air face velocities from 3362.4 to 6746.4

Tsair-Wang Chung; Tushar K. Ghosh; Anthony L. Hines

1993-01-01

364

Polyethylenimine-modified metal oxides for fabrication of packed capillary columns for capillary electrochromatography and capillary liquid chromatography.  

PubMed

The need for novel packing materials in both capillary electrochromatography (CEC) and capillary liquid chromatography (CLC) is apparent and the development towards more selective, application-oriented chromatographic phases is under progress world-wide. In this study we have synthesized new polyethyleneimine (PEI) functionalized Mn(2)O(3), SiO(2), SnO(2), and ZrO(2) particles for the fabrication of packed capillary columns for CEC and CLC. The nanocasting approach was successful for the preparation of functionalized metal oxide materials with a controlled porosity and morphology. PEI functionalization was done using ethyleneimine monomers to create particles which are positively charged in aqueous solution below pH 9. This functionalization allowed the possibility to have both hydrophobic (due to its alkyl chain) and ionic interactions (due to positively charged amino groups) with selected compounds. For comparison aminopropyl-functionalized silica was also synthesized and tested. Both slurry pressure and electrokinetic packing procedures used gave similar results, but fast sedimentation of the material caused some problems during the packing. The high stability and wide pH range of PEI-functionalized SiO(2) material, with potential for hydrophobic and electrostatic interactions, proved to be useful for the CEC and CLC separation of some model acidic and neutral compounds. PMID:21238970

Wiedmer, Susanne K; D'Orazio, Giovanni; Smått, Jan-Henrik; Bourdin, Delphine; Baños-Pérez, Clara; Sakeye, Motolani; Kivilompolo, Maarit; Kopperi, Matias; Ruiz-Jiménez, José; Fanali, Salvatore; Riekkola, Marja-Liisa

2010-12-23

365

Development of soft sensor for neural network based control of distillation column.  

PubMed

The present work is aimed at the design of Levenberg-Marquardt (LM) and adaptive linear network (ADALINE) based soft sensors and their application in inferential control of a multicomponent distillation process. Further the ADALINE sensor is trained online using past measurements, to adapt the changes in the inputs and is termed as dynamic ADALINE (D-ADALINE) sensor. The soft sensors are then used in the control loop to obtain LM based inferential controller (LMIC), ADALINE based inferential controller (ADIC) and D-ADALINE based inferential controller (DADIC) for the process. The performance of dynamic controller is also analyzed for different inputs and sampling intervals. The comparison of results shows the efficient and robust prediction capability of D-ADALINE sensor and hence DADIC proves to be the best controller. PMID:23375672

Rani, Asha; Singh, Vijander; Gupta, J R P

2013-01-30

366

Chromatographic behaviour and comparison of column packed with sub-2 ?m stationary phases in liquid chromatography  

Microsoft Academic Search

In order to reduce the analysis time and maintain good efficiency in liquid chromatography, it is advisable to simultaneously decrease the column length and the particle size of the chromatographic support. Therefore, several manufacturers have developed and commercialized short columns filled with particles that have a diameter smaller than 2?m. The focus of this work was to check the chromatographic

Dao T.-T. Nguyen; Davy Guillarme; Serge Rudaz; Jean-Luc Veuthey

2006-01-01

367

Bilirubin removal from human plasma in a packed-bed column system with dye-affinity microbeads  

Microsoft Academic Search

A dye-ligand, Cibacron Blue F3GA, was covalently coupled with the poly(EGDMA-HEMA) microbeads. The affinity sorbent carrying 16.5 ?mol Cibacron Blue F3GA per gram polymer was then used to remove bilirubin from human plasma in a packed-bed column system. Bilirubin adsorption from human plasma on the unmodified poly(EGDMA-HEMA) microbeads was 0.32 mg\\/g, while much higher adsorption values, up to 24.2 mg\\/g,

Adil Denizli; Mustafa Kocakulak; Erhan Pi?kin

1998-01-01

368

The removal of endotoxins from protein solutions using column packings with aminated poly (?-methyl L-glutamate) spheres  

Microsoft Academic Search

A method is described for the selective removal of endotoxins from various protein solutions using columns packed with aminated poly (?-methyl L-glutamate) (PMLG-NH2) spheres. The PMLG-NH2 adsorbents showed a high adsorbing activity for endotoxins which had an ionic strength of ?=0.05–1.0 and pH 5.0–9.0. The endotoxin-adsorbing capacity per millitre of the wet adsorbent increased from 0.40 to 1.35 mg (E.

C. Hirayama; M. Sakata; S. Morimoto; H. Tachibe; H. Ihara; K. Ohkuma; Y. Miyachi

1995-01-01

369

Application of equilibrium and mass transfer models to dynamic removal of Cr(VI) ions by Chitin in packed column reactor  

Microsoft Academic Search

The dynamic removal of hexavalent chromium by chitin flakes was studied in a packed column reactor. The values of column parameters were predicted as a function of flow rate, bed depth, particle size and inlet metal ion concentration. On evaluating the breakthrough curves, sorption isotherms were obtained and modelled according to the Langmuir, the Redlich–Peterson and the Freundlich models. Kinetic

Ye?im Sa?; Yücel Aktay

2001-01-01

370

Quantitative multi-residue determination of ?-agonists in bovine urine using on-line immunoaffinity extraction-coupled column packed capillary liquid chromatography-tandem mass spectrometry  

Microsoft Academic Search

This report demonstrates the potential of on-line immunoaffinity extraction and coupled column packed capillary liquid chromatography-ion spray tandem mass spectrometry for multi-residue determination of five ?-agonists, clenbuterol, mabuterol, mapenterol, methylclenbuterol, and tolubuterol, in bovine urine using an automated column switching system. Trace enrichment and preliminary sample cleanup was performed on-line using bovine urine diluted with phosphate-buffered saline. The column switching

Jenny Cai; Jack Henion

1997-01-01

371

Mass transfer resistance in narrow-bore columns packed with 1.7 microm particles in very high pressure liquid chromatography.  

PubMed

Surprisingly, the mass transfer kinetic properties of columns packed with superficially porous particles are markedly different from those of columns packed with fully porous particles. The performances of 2.1mmx150mm columns packed with a new type of sub-2microm particles, the superficially porous 1.7microm Kinetex-C(18), and with the classical 1.7microm BEH-C(18) fully porous particles were measured and are discussed. The sample was naphtho[2,3-a]pyrene; the use of different mobile phase compositions allowed a comparison between data measured with retention factors of k(') approximately 2 and k(') approximately 20. The minimum reduced height equivalent to a theoretical plate (HETP) of the two columns were similar, at h(min)=2.0. However, this minimum HETP was observed at a markedly shorter reduced linear velocity for the column packed with totally porous particles, between 5 and 7 for BEH, than for the one packed with shell particles, between 8 and 10 for Kinetex. This result is explained by the combination of (1) a 35% smaller B term for the Kinetex column than for the BEH column, due to the 37% lower porous volume of the former; (2) a larger reduced A term for the Kinetex column (1.6), showing a relatively poorly packed column with significant trans-column velocity biases than for the BEH column (ca. 1.0); and (3) a much lesser dependance of the efficiency on the mobile phase velocity at high velocities for the Kinetex than for the BEH column, when these columns are placed in the oven of the instrument under still-air conditions. The heat friction affects significantly more the efficiency of the BEH column than that of the Kinetex column. This unexpected result is accounted for by the three times smaller heat conductivity of the BEH bed (lambda(BEH) approximately 0.25 W/m/K) than that of the Kinetex bed (lambda(Kinetex) approximately 0.75W/m/K). PMID:20579655

Gritti, Fabrice; Guiochon, Georges

2010-06-09

372

A model for pressure drop in two-phase gas-liquid downflow through packed columns  

Microsoft Academic Search

The nature of the interaction between the flowing phases in a cocurrent gasliquid downflow through packed beds depends on the type of the flow regime. The interaction is poor and geometric in nature in gas-continuous flow and becomes high and dynamic in pulse flow due to gas dispersion, acceleration, and mixing of the liquid in the pulses. Models to calculate

V. G. Rao; A. A. H. Drinkenburg

1985-01-01

373

An analytical solution for air dehumidification by liquid desiccant in a packed column  

Microsoft Academic Search

This paper presents a new analytical solution of heat and mass transfer processes in a packed bed liquid desiccant dehumidifier based on the equilibrium humidity on the interface is assumed to be constant. In order to maintain the partial pressure difference on the interface, a high liquid desiccant flow rate is often applied in the practical absorber. Therefore, for a

Davoud Babakhani; Meysam Soleymani

2009-01-01

374

Aroma compounds produced by Kluyveromyces marxianus in solid state fermentation on a packed bed column bioreactor  

Microsoft Academic Search

Studies were carried out for the production of aroma compounds by Kluyveromyces marxianus grown on cassava bagasse in solid state fermentation using packed bed reactors, testing two different aeration rates. Respirometric analysis was used to follow the growth of the culture. Headspace analysis of the culture by gas chromatography showed the production of 11 compounds, out of which nine were

Adriane B. P. Medeiros; Ashok Pandey; Pierre Christen; Paulo S. G. Fontoura; Renato J. S. de Freitas; Carlos R. Soccol

2001-01-01

375

Design of a selftuning fuzzy control system and the application to a distillation column  

SciTech Connect

A selftuning fuzzy control system was developed for industrial use, with a hierarchical structure of, in the lower loop, an algorithm for feedforward-feedback fuzzy control and, in the upper loop, a learning algorithm for evaluation of the control performance and selftuning of the gain of the feedforward fuzzy control. The function of the selftuning fuzzy controller is to overadjust the gain of the feedback fuzzy controller, using a learning rule which compares the trends in the manipulated variables from the feedforward and feedback controllers. This fuzzy control system was tested in a demethanizer column in an ethylene plant, and was effective for the bottom-temperature control loop, which has, hitherto, been difficult to control.

Hanakuma, Y.; Irizuki, Y; Adachi, M. (Idemitsu Petroleum Co., Ltd., Ichihara (Japan). Technical and Engineering Dept.); Nakanishi, E. (Kobe Univ. (Japan). Dept. of Chemical Engineering)

1994-01-01

376

Protein Loading Capacity and Textural Properties of Column Packings in Reversed-Phase HPLC  

Microsoft Academic Search

The relationship between the textural properties (pore size, pore volume and surface area) of reversed-phase silica gel packings for HPLC and the dynamic loading capacity of large biomolecules was studied by using silica gels manufactured by similar processes. Several silica gels whose unbonded pore diameters range from 100 to 250 A and whose pore volumes range from 1.0 to 1.4

Young S. Kim; Bruce W. Sands; Jonathon L. Bass

1987-01-01

377

Transverse bacterial migration induced by chemotaxis in a packed column with structured physical heterogeneity.  

PubMed

The significance of chemotaxis in directing bacterial migration toward contaminants in natural porous media was investigated under groundwater flow conditions. A laboratory-scale column, with a coarse-grained sand core surrounded by a fine-grained annulus, was used to simulate natural aquifers with strata of different hydraulic conductivities. A chemoattractant source was placed along the central axis of the column to model contaminants trapped in the heterogeneous subsurface. Chemotactic bacterial strains, Escherichia coli HCB1 and Pseudomonas putida F1, introduced into the column by a pulse injection, were found to alter their transport behaviors under the influence of the attractant chemical emanating from the central source. For E. coil HCB1, approximately 18% more of the total population relative to the control without attractant exited the column from the coarse sand layer due to the chemotactic effects of alpha-methylaspartate under an average fluid velocity of 5.1 m/d. Although P. putida F1 demonstrated no observable changes in migration pathways with the model contaminant acetate under the same flow rate, when the flow rate was reduced to 1.9 m/d, approximately 6-10% of the population relative to the control migrated from the fine sand layer toward attractant into the coarse sand layer. Microbial transport properties were further quantified by a mathematical model to examine the significance of bacterial motility and chemotaxis under different hydrodynamic conditions, which suggested important considerations for strain selection and practical operation of bioremediation schemes. PMID:19731698

Wang, Meng; Ford, Roseanne M

2009-08-01

378

Influence of pressure on sorption equilibrium: HPLC column packing-mixed eluent  

Microsoft Academic Search

Pronounced base line perturbations were repeatably observed in LC both in alternating recycling and in backflushing experiments when binary eluents and refractometric detectors were used. The perturbations which we call eigenzones appeared immediately after operating the recycling or the backflushing valve, and their size and shape depended on the nature of both the column filling and the mixed mobile phase

M. Chalányová; T. Macko; J. Kandrá?; D. Berek

1984-01-01

379

Transverse bacterial migration induced by chemotaxis in a packed column with structured physical heterogeneity  

PubMed Central

The significance of chemotaxis in directing bacterial migration towards contaminants in natural porous media was investigated under groundwater flow conditions. A laboratory-scale column, with a coarse-grained sand core surrounded by a fine-grained annulus, was used to simulate natural aquifers with strata of different hydraulic conductivities. A chemoattractant source was placed along the central axis of the column to model contaminants trapped in the heterogeneous subsurface. Chemotactic bacterial strains, Escherichia coli HCB1 and Pseudomonas putida F1, introduced into the column by a pulse injection, were found to alter their transport behaviors under the influence of the attractant chemical emanating from the central source. For E. coli HCB1, approximately 18% more of the total population relative to the control without attractant exited the column from the coarse sand layer due to the chemotactic effects of ?-methylaspartate under an average fluid velocity of 5.1 m/d. Although P. putida F1 demonstrated no observable changes in migration pathways with the model contaminant acetate under the same flow rate, when the flow rate was reduced to 1.9 m/d, approximately 6~10% of the population relative to the control migrated from the fine sand layer towards attractant into the coarse sand layer. Microbial transport properties were further quantified by a mathematical model to examine the significance of bacterial motility and chemotaxis under different hydrodynamic conditions, which suggested important considerations for strain selection and practical operation of bioremediation schemes.

Wang, Meng; Ford, Roseanne M.

2009-01-01

380

The Microbiology of Acid Mine Water Treatment in Packed Bed Columns.  

National Technical Information Service (NTIS)

The present research was undertaken in an effort to identify the agents responsible for the transformation of ferrous iron to the ferric state during application of acid mine water to columns of trickling filter medium located in the bed of a full scale t...

R. F. Unz M. T. Lieberman

1973-01-01

381

A simplified mathematical model of the cryogenic distillation with application to the (13C) isotope separation column  

NASA Astrophysics Data System (ADS)

The isotope (13C) has a widespread application in many fields such as chemistry, physics, medicine, etc. To obtain a high concentration in isotope of interest, in our case (13C), it is used the method of cryogenic distillation of carbon monoxide (CO) which is based on the difference between the vapor pressure of (12C16O) and (13C16O) at the temperature of liquid nitrogen. Isotopic separation plant, used to obtain the isotope (13C), is a complex installation, with many inputs and outputs, rather difficult to control. Due to this reason, from the point of view of automation, it is needed a simplified mathematical model. This model can be determined only with some presumption and simplification assumptions. Using the physical laws, the hydrodynamic part of the process and the mass balance will be described by partial differential equations. In order to design a controller for the column, it is needed a transfer function or a statespace realization of the plant, which is the main contribution of the present work. Implementing this mathematical model will be the key element for describing and understanding the operation of the plant and for future development of process control strategies.

Neaga, A. O.; Festila, C.; Dulf, E. H.; Both, R.; Szelitzky, T.; Gligan, M.

2012-02-01

382

A novel silica-based column packing for reversed-phase HPLC of basic compounds  

Microsoft Academic Search

Summary  A novel bonded phase for reversed-phase HPLC was synthesized in two steps. Octylamine was first reacted with ?-(3,4-epoxycyclohexyl)ethyltrimethoxysilane\\u000a (?-ECTS) and then the intermediate product was coupled onto porous silica. The prepared packing was characterized by elemental\\u000a analysis, solid-state13C NMR and Fourier transform infrared (FT-IR). Chromatographic evaluations were carried out by using a mixture of organic compounds\\u000a including acidic, basic and

Xiaojia Huang; Junde Wang; Xueliang Liu; Zhenhua Shang

2001-01-01

383

Delayed adsorption on slowly accessible stationary phase surfaces in porous liquid chromatographic column packings  

Microsoft Academic Search

Variation in the fractional area of the tailing portion of elution peak in HPLC was analysed over a wide range of mobile phase flow-rates. A slow adsorption-desorption process was found to contribute to solute retention only in the range of column hold-up times by at least two orders of magnitude longer than those usually used in analytical or preparative separation.

Toshikazu Ohkuma; Akira Dobashi; Shoji Hara

1996-01-01

384

Packed bed column studies on Cr (VI) removal from tannery wastewater by neem sawdust  

Microsoft Academic Search

The removal of Cr (VI) from tannery wastewater by neem sawdust was investigated in a fixed bed column. The experiments were conducted to study the effect of important parameters such as bed depth (5–15cm) and flow rate (5–15mlmin?1). The bed depth service time model (BDST) fit well with the experimental data. The adsorption capacity estimated from the BDST model was

V. Vinodhini; Nilanjana Das

2010-01-01

385

Packed bed column studies on Cd(II) removal from industrial wastewater by macrofungus Pleurotus platypus  

Microsoft Academic Search

The removal of Cd (II) from industrial wastewater by macrofungus Pleurotus platypus was investigated in a fixed bed column. Experiments were conducted to study the effect of important parameters such as bed depth (5–15cm) and flow rate (5–15mlmin?1). The bed depth service time model (BDST) fitted well with the experimental data and the adsorption capacity (N0) estimated from this model

R. Vimala; D. Charumathi; Nilanjana Das

2011-01-01

386

Adsorption of polyethylene standards from decalin on liquid chromatography column packings  

Microsoft Academic Search

Linear polyethylene and isotactic polypropylene standards were injected into columns which contained MFI (SH-300 and silicalite) or faujasite (CBV-780) type zeolites. 1,2,4-Trichlorobenzene, cyclohexanone, 2-ethyl-hexanol, decalin and tetralin were used as mobile phases at 140°C. It was found that polyethylene is fully retained on zeolite SH-300 when decalin is used as a mobile phase. Moreover, polyethylene is partially retained on zeolite

Tibor Macko; Harald Pasch; Joeri F. Denayer

2003-01-01

387

Flooding and mass transfer in Goodloe-packed columns. [For Kr absorption in liquid CO in HTGR off-gas systems  

Microsoft Academic Search

Flooding and mass transfer experiments were performed with a CO-air\\/water system to examine mass transfer characteristics in Goodloe-packed columns of 6.4 and 15.2-cm ID for removal of radioactive Kr from HTGR off-gas. The flooding experiments verified previous correlations for the packing. The plug flow model was selected for calculation of the overall mass transfer coefficient, K\\/sub L\\/a. The correlation for

E. I. Chao; R. J. Bertolami; J. L. P. Varlet; G. R. Wilkes

1976-01-01

388

Performance of tapered-column packed-bed bioreactor used for ethanol production by immobilized yeast cells  

SciTech Connect

The tapered-column packed-bed bioreactor was tested as a solution to the problems of pressure drop and nonuniform flow in immobilized-yeast fermentations. The column operation was simulated using a mathematical model considering the effects of the heterogeneous kinetics, interfacial mass transfer, convective and dispersive flows of the liquid phase. The kinetics of ethanol production by the immobilized Saccharomyces cerevisiae was determined using shake-flask batch cultures. It was found that there is a shift in the metabolism of the yeast used at glucose concentrations of about 2 to 5 g/l, and due to this effect two sets of V/sub m/ and K/sub m/ values are determined. Maximum rate of fermentation was found to be 0.80 and 0.39 g ethanol/g cell/hr, and the affinity constant was found to be 97 and 11 mM in the medium and low glucose concentration regions respectively. The rate of fermentation went through a maximum at about 70 g glucose/l and the substrate inhibition constant was found to be 0.76 M. The product inhibition constant was also tested and was found to be 113 g ethanol/l. The column performance was simulated effectively at low residence times and low ethanol concentrations, however at the larger residence times and product concentrations better agreement was obtained by changing the ethanol inhibition constant to 85 g/l. In another set of experiments the effect of inert gas flow and oxygen gas feed into the tapered-column was tested. Inert gas feed helps increase the conversion only at very small flow rates. The effect of oxygen was positive at all the flow rates tested.

Hamamci, H.

1986-01-01

389

The effects of surfactants and solution chemistry on the transport of multiwalled carbon nanotubes in quartz sand-packed columns.  

PubMed

The effect of different surfactants on the transport of multiwalled carbon nanotubes (MWCNTs) in quartz sand-packed columns was firstly investigated under various conditions. The stable plateau values (Cmax) of the breakthrough curves (BTCs), critical PVs (the number of pore volumes of infusions needed to reach the Cmax), maximum transport distances (Lmax), deposition rate coefficients (kd) and retention rates were calculated to compare the transport and retention of MWCNTs under various conditions. Stability of the MWCNT suspensions as a function of the influencing factors was examined to reveal the underlying mechanism of the MWCNT retention. Results showed that MWCNTs suspended by different surfactants presented different BTCs; the MWCNT transport increased with increasing sand size and MWCNT concentration; high flow velocity was favorable for the MWCNT transport, while high Ca(2+) concentration and low pH were unfavorable for the transport; hetero-aggregation, straining and site blocking occurred during the transport. PMID:23948360

Lu, Yinying; Xu, Xiaopan; Yang, Kun; Lin, Daohui

2013-08-13

390

Preparation and application of an immunoaffinity column based on an antibody with strong affinity and packing material with good stability.  

PubMed

This article describes the production of an anti-citrinin antibody that showed a high affinity constant (Ka) of 6.28 × 10? and good tolerance to organic solvent and low pH, the synthesis of a Cu (II)-embedded polymer that showed strong binding with this antibody and the preparation of packing material for an immunoaffinity column (IAC) that show good stability. Most of the IACs reported either use harsh elution conditions and are used only once or use gentle elution conditions and are reused many times. Here, through the combined use of a strong-affinity antibody and packing material with good stability, high recoveries during clean-up and yet simultaneously good stability of the IAC were successfully achieved. Under optimised conditions of 80% methanol (pH 3), the IACs were used to clean-up the extracts of Monascus colour and red yeast rice samples, followed by HPLC detection. The recoveries of citrinin from spiked samples at levels of 50-200 ?g kg?¹ were in the range of 84-97%. PMID:23710628

Zhang, Hongyan; Wang, Mengmeng; Wang, Yao; Li, Qingling; Zhou, Jianhua; Huo, Feng; Tang, Bo

2013-05-28

391

Comparison of Packed Beds and Qiagen Columns for Recovering Trace Amounts of B. anthracis DNA from Liquid Suspensions  

SciTech Connect

The goal of this work was to optimize and evaluate LLNL's in-bed amplification technology to improve the level of detection for suspensions containing trace amounts of anthracis DNA. The binding/cleaning performance of the packed bed is compared to the conventional commercial approach; Qiagen column cleanup and elution, followed by detection through an ex-situ amplification process. Five liquid suspensions were spiked with B.anthracis DNA in concentration series. These suspensions were: (1) water, (2) water with EDTA, (3) dirty water from carpet extraction, (4) dirty carpet extraction with phosphate buffered saline (PBS) plus 0.1% Tween 20 plus 0.1% gelatin, and (5) a subway aerosol collected in water. Each suspension matrix was spiked with DNA and injected (in replicate) into either Qiagen Microcolumns (using the kit processing instructions) or LLNL's packed bed (using the LLNL in-bed purification and amplification protocol). The process output was assayed by quantitative polymerase chain reaction (QPCR). Table ES-1 shows the level of DNA (pg per 100 uL of input suspension) that resulted in successful amplification for all reactions (X=Y), and the level for which at least one of the reactions was successful (X>0). For each suspension and DNA concentration, there were Y QPCR assays of which X showed successful amplification. LLNL's packed bed technology outperformed Qiagen Microcolumns for all five suspensions, typically by one order of magnitude in both the limit of assured detection (all reactions positive), and the lower limit of detection (some reactions positive).

Sorensen, K; Arroyo, E; Erler, A; Christian, A T; Camp, D; Wheeler, E K

2006-06-23

392

Simultaneous micro steam distillation\\/solvent extraction for the isolation of semivolatile flavor compounds from cinnamon and their separation by series coupled-column gas chromatography  

Microsoft Academic Search

Simultaneous micro steam distillation\\/solvent extraction is an efficient method of extracting semivolatile flavor and fragrance compounds from cinnamon for subsequent separation by series coupled-column gas chromatography. With pentane as the extraction solvent and an extraction time of 1.5 h clean extracts requiring no further sample preparation prior to gas Chromatographic analysis are obtained. It is shown that adulteration of cinnamon

Arya Jayatilaka; Salwa K. Poole; Colin F. Poole; Tina M. P. Chichila

1995-01-01

393

Distillation for alcohol  

Microsoft Academic Search

A new distillation equipment for alcohol which consists mainly of a brief concentrating column a, a concentrating column b, a compressor C to compress alcohol vapor generated in column B and water evaporator D heated by the compressed alcohol vapor is developed and this especially fits for a distillation source of a glue like solution obtained by alcohol fermentation because

T. Kawase; K. Sawai

1983-01-01

394

Transport models for desorption from natural soils packed in flushed columns  

NASA Astrophysics Data System (ADS)

This paper addresses an experimental and theoretical study of sorbed contaminant removal from a column (or reactor) by flushing. This removal may take place by either volatilization or rinsing, and nonlinear sorption is accounted for by employing a Freundlich relationship. A one-dimensional nonequilibrium transport model is proposed which describes the unsteady mass transfer between flushing medium and soil phases in the column, using a linear chemical transfer model. The moving boundary problem is transferred, and a perturbation method is employed to obtain an approximate solution of the governing equations for a small Merkel number Me (this dimensionless number comprises the product of fluid residence time and the mass transfer coefficient). The solution reveals the effect of the various parameters, such as the Freundlich parameter n, on the contaminant transport in fluid phase and decay in solid phase. Applying the model to various experimental data results in values for the overall mass transfer coefficients, which are useful for engineering computations. Furthermore, the model enables the prediction of the initial soil contamination level as well as the parameter n solely from the measured exit contaminant concentrations in the flushing fluid. A thorough comparison of this prediction with the measured soil concentration (prior to the experiments) yields good agreement.

Brouwers, H. J. H.

1999-06-01

395

Packed column supercritical fluid chromatographic separation and estimation of acetaminophen, diclofenac sodium and methocarbamol in pharmaceutical dosage forms.  

PubMed

A reproducible and fast method has been developed for the assay of acetaminophen, methocarbamol, and diclofenac sodium in bulk and drug forms using packed column supercritical fluid chromatography employing internal standard method. The analytes were resolved by elution with supercritical fluid carbon dioxide doped with 11.1% (v/v) methanol on a Shendon-Phenyl (250x4.6 mm) 5 mum column with detection monitored spectrophotometrically at 225 nm. The densities and polarities of the mobile phase were optimised from the effects of pressure, temperature and modifier concentration on chromatograhic figures like retention time (t(R), min), retention factor (k(')) etc. Modifier concentration proved to be the most effective means for changing both retention and selectivity. Calibration data and recovery of the drug from spiked concentrations were determined to assess the viability of the method. The supercritical fluid chromatography (SFC) method was directly compared to an HPLC assay, developed in the laboratory, of the same analytes. With respect to speed and use of organic solvents SFC was found to be superior, while in all other aspects the results were similar to HPLC. The method has been successfully used for the assay of two formulations containing a combination of (A) acetaminophen and methocarbamol and (B) acetaminophen and diclofenac sodium. There was no interference from excipients. The present work validates the recent proposition that supercritical fluid chromatography using CO(2) and modifiers is a viable, faster alternative to reverse phase HPLC. PMID:18967296

Patil, S T; Sundaresan, M; Bhoir, I C; Bhagwat, A M

1998-09-01

396

Theoretical and experimental impact of the bed aspect ratio on the axial dispersion coefficient of columns packed with 2.5 ?m particles.  

PubMed

The impact of the ratio of the column diameter to the average particle size (or bed aspect ratio) on the column performance was investigated from theoretical and experimental viewpoints. The experiments were conducted for two series of 100mm long columns, 2.1, 3.0, and 4.6mm in diameter, packed with 2.5 ?m fully porous particles of Bridge Ethylene Hybrid (BEH) for one series and Charged Surface Hybrid (CSH) for the other. The heights equivalent to a theoretical plate (HETP) of two low molecular weight compounds, uracil (non-retained, k=0) and naphthalene (retained, k=2.5), were determined from the true moments of the recorded peak profiles. The results showed a systematic decrease of the column performance for uracil at high flow velocities with decreasing column inner diameter, in agreement with the theoretical predictions of the variation of the trans-column eddy dispersion HETP term with decreasing bed aspect ratio. This result is consistent with the increasing volume fraction of the wall region of the column, in which the average linear velocity of the mobile phase over a distance of 5 particle diameters from the column wall is about 10% larger than in the bulk center of the column (infinite diameter column). For the retained compound, the discrepancies are levelled out due to the longer average residence time and larger particle diffusivities of retained compounds, which allow a more efficient relaxation of the radial concentration gradients. Further improvements of the performance of the larger I.D. columns (3.0 and 4.6mm I.D.) may be achieved by decreasing the harmful effect of this trans-column velocity bias by injecting and/or collecting the sample molecules in a wide central zone of the column. For 2.1mm I.D. columns, this approach would prove useful only when HPLC instruments providing a lower extra-column band broadening contribution will become available. Finally, the further minimization of the trans-column eddy dispersion HETP term and the design of new, better inlet/outlet column endfitting/frit assemblies requires newer and more accurate models of eddy dispersion in packed columns than those previously provided by Gunn and Giddings and the numerical calculation of band profiles using original functions to account for the distribution and collection of the sample molecules at the inlet and outlet of the column. PMID:23010248

Gritti, Fabrice; Guiochon, Georges

2012-09-12

397

Removal of As(III) in a column reactor packed with iron-coated sand and manganese-coated sand.  

PubMed

The applicability of manganese-coated sand (MCS) and iron-coated sand (ICS) for the treatment of As(III) via oxidation and adsorption processes was investigated. Scanning electron microscopy (SEM) and X-ray diffraction spectroscopy (XRD) were used to observe the surface properties of the coated layer. In the batch adsorption, the adsorption rate of As(V) onto ICS was greater than that of As(III), and ICS showed a greater adsorption capacity for the removal of As(V) than As(III). From a bench-scale column test, a column reactor packed with both MCS and ICS was found to be the best system for the treatment of As(III) due to the promising oxidation efficiency of As(III) to As(V) by MCS and adsorption of As(V) by both MCS and ICS. From these bench-scale results, the treatment of synthetic wastewater contaminated with As(III) was investigated using a pilot-scale filtration system packed with equal amounts (each 21.5 kg) of MCS at the bottom and ICS on the top. The height and diameter of the column were 200 and 15 cm, respectively. As(III) solution was introduced into the bottom of the filtration system, at a speed of 5 x 10(-3)cms(-1), over 148 days. The breakthrough of total arsenic in the mid-sampling (end of the MCS bed) and final-sampling (end of the ICS bed) positions began after 18 and 44 days, respectively, and showed complete breakthrough after 148 days. Although the breakthrough of total arsenic in the mid-sampling position began after 18 days, the concentration of As(III) in the effluent was below 50 microg L(-1) for up to 61 days. This result indicates that MCS has sufficient oxidizing capacity for As(III), and 1 kg of MCS can oxidize 93 mg of As(III) for up to 61 days. When the complete breakthrough of total arsenic occurred, the total arsenic removed by 1 kg of MCS was 79.0 mg, suggesting MCS acts as an adsorbent for As(V), as well as an oxidant for As(III). From this work, a filtration system consisting of both MCS and ICS can potentially be used a new treatment system to simultaneously treat As(III) and As(V). PMID:17570581

Chang, Yoon-Young; Song, Ki-Hoon; Yang, Jae-Kyu

2007-05-10

398

Efficiency gain limits of the parallel segmented inlet and outlet flow concept in analytical liquid chromatography columns suffering from radial transcolumn packing density gradients.  

PubMed

The maximal gain in efficiency that can be expected from the use of the segmented column end fittings that were recently introduced to alleviate the effect of transcolumn packing density gradients has been quantified and generalized using numerical computations of the band broadening process. It was found that, for an unretained compound in a column with a parabolic packing density gradient, the use of a segmented inlet or a segmented outlet allows to eliminate about 60-100% of the plate height contribution (H(tc)) originating from a parabolic transcolumn velocity gradient in a d(c)=4.6 mm column. In a d(c)=2.1 mm column, these percentages change from 10 to 100%. Using a combined segmented in- and outlet, H(tc) can be reduced by about 90-100% (d(c)=4.6 mm column) or 20-100% (d(c)=2.1 mm column). The strong variation of these gain percentages is due to fact that they depend very strongly on the column length and the flow rate. Dimensionless graphs have been established that allow to directly quantify the effect for each specific case. It was also found that, in agreement with one's physical intuition, trans-column velocity profiles that are more flat in the central region benefit more from the concept than sharp, parabolic-like profiles. The gain margins furthermore tend to become smaller with increasing retention and increasing diffusion coefficient. PMID:22939209

Broeckhoven, Ken; Desmet, Gert

2012-08-17

399

Evaluation by respirometry of the degradability of retort water using a shale ash and overburden packed column.  

PubMed

Oil shale processing produces an aqueous wastewater stream known as retort water. The fate of the organic content of retort water from the Stuart oil shale project (Gladstone, Queensland) is examined in a proposed packed bed treatment system consisting of a 1:1 mixture of residual shale from the retorting process and mining overburden. The retort water had a neutral pH and an average unfiltered TOC of 2,900 mg 1(-1). The inorganic composition of the retort water was dominated by NH4+. Only 40% of the total organic carbon (TOC) in the retort water was identifiable, and this was dominated by carboxylic acids. In addition to monitoring influent and effluent TOC concentrations, CO2 evolution was monitored on line by continuous measurements of headspace concentrations and air flow rates. The column was run for 64 days before it blocked and was dismantled for analysis. Over 98% of the TOC was removed from the retort water. Respirometry measurements were confounded by CO2 production from inorganic sources. Based on predictions with the chemical equilibrium package PHREEQE, approximately 15% of the total CO2 production arose from the reaction of NH4+ with carbonates. The balance of the CO2 production accounted for at least 80% of the carbon removed from the retort water. Direct measurements of solid organic carbon showed that approximately 20% of the influent carbon was held-up in the top 20cm of the column. Less than 20% of this held-up carbon was present as either biomass or as adsorbed species. Therefore, the column was ultimately blocked by either extracellular polymeric substances or by a sludge that had precipitated out of the retort water. PMID:16128388

Clarke, W P; Ho, N M; Taylor, M; Coombs, S; Bell, P R; Picaro, T

2005-08-01

400

Relative Transport Behavior of Escherichia coli O157:H7 and Salmonella enterica serovar Pullorum in Packed Bed Column Systems: Influence of Solution Chemistry and Cell Concentration  

Technology Transfer Automated Retrieval System (TEKTRAN)

The influence of solution chemistry and cell concentration on bacterial pathogen transport has been examined using Salmonella pullorum and Escherichia coli O157:H7. A packed bed column was employed to determine the transport behavior and deposition kinetics on real aquifer sand particles over a ran...

401

Preliminary studies on Cr(VI) removal from aqueous solution using grape stalk wastes encapsulated in calcium alginate beads in a packed bed up-flow column  

Microsoft Academic Search

Cr(VI) sorption on 2% grape stalks encapsulated in calcium alginate beads was examined in a continuous packed bed column. The effect of operating parameters as flow rate, inlet metal ions concentration and bed height on the sorption characteristics was investigated. The total amount of metal sorbed, equilibrium uptake and total removal percent of Cr(VI) related to the effluent volumes were

N. Fiol; C. Escudero; J. Poch; I. Villaescusa

2006-01-01

402

Modeling the velocity field of the electroosmotic flow in charged capillaries and in capillary columns packed with charged particles: interstitial and intraparticle velocities in capillary electrochromatography systems  

Microsoft Academic Search

Mass transfer systems based on electrokinetic phenomena (i.e., capillary electrochromatography (CEC)) have shown practical potential in becoming powerful separation methods for the biotechnology and pharmaceutical industries. A mathematical model has been constructed and solved to describe quantitatively the profiles of the electrostatic potential, pressure, and velocity of the electroosmotic flow (EOF) in charged cylindrical capillaries and in capillary columns packed

A. I. Liapis; B. A. Grimes

2000-01-01

403

Axiale Menging in een Extractiekolom Gepakt met Sulzer Statische Mengelementen II (Axial Mixing in an Extraction Column Packed with Sulzer Static Mixing Elements II).  

National Technical Information Service (NTIS)

In this study the axial mixing was investigated in a counter-flow (backflow) liquid-liquid extraction column packed with Sulzer static mixing elements. For this purpose a device was developed with which very specifically and selectively one of the two liq...

R. Weltevrede

1982-01-01

404

Cu2+-imprinted cross-linked chitosan resin as micro-column packing materials for online chemiluminescence determination of trace copper.  

PubMed

The Cu(2+)-imprinted cross-linked chitosan resin was synthesized and the binding characteristic of the resin to Cu(2+) was evaluated. The prepared resin was packed into a micro-glass column and used as micro-separating column. The micro-separating column was connected into the chemiluminescence flow system and placed in front of the window of the photomultiplier tube. Based on the luminol-hydrogen peroxide chemiluminescence system, a flow injection online chemiluminescence method for determination of trace copper was developed and trace Cu(2+) in complex samples was successfully determined. The proposed method improved the shortcomings of chemiluminescence method's poor selectivity. PMID:20629043

Nie, Feng; Hao, Liang; Gao, Mei; Wu, Yingchun; Li, Xinsheng; Yu, Sha

2010-07-13

405

Analysis of Atmospheric Polycyclic Aromatic Hydrocarbons and Nitropolycyclic Aromatic Hydrocarbons in Gas\\/Particle Phases Separately Collected by a High-volume Air Sampler Equipped with a Column Packed with XAD-4 Resin  

Microsoft Academic Search

We developed a sampler for collecting atmospheric polycyclic aromatic hydrocarbons (PAHs) and nitropoly- cyclic aromatic hydrocarbons (NPAHs) by attaching a glass column packed with XAD-4 resin to the gas sampling port of a high-volume air sampler equipped with a filter. When the upper and bottom layers of the column were packed with 64 g and 32 g of XAD-4 resin,

Yuki Araki; Ning Tang; Michihiro Ohno; Takayuki Kameda; Akira Toriba; Kazuichi Hayakawaa

2009-01-01

406

Transport of biocolloids in water saturated columns packed with sand: Effect of grain size and pore water velocity.  

PubMed

The main objective of this study was to evaluate the combined effects of grain size and pore water velocity on the transport in water saturated porous media of three waterborne fecal indicator organisms (Escherichia coli, MS2, and ?X174) in laboratory-scale columns packed with clean quartz sand. Three different grain sizes and three pore water velocities were examined and the attachment behavior of Escherichia coli, MS2, and ?X174 onto quartz sand was evaluated. The mass recoveries of the biocolloids examined were shown to be highest for Escherichia coli and lowest for MS2. However, no obvious relationships between mass recoveries and water velocity or grain size could be established from the experimental results. The observed mean dispersivity values for each sand grain size were smaller for bacteria than coliphages, but higher for MS2 than ?X174. The single collector removal and collision efficiencies were quantified using the classical colloid filtration theory. Furthermore, theoretical collision efficiencies were estimated only for E. coli by the Interaction-Force-Boundary-Layer, and Maxwell approximations. Better agreement between the experimental and Maxwell theoretical collision efficiencies were observed. PMID:22115094

Syngouna, Vasiliki I; Chrysikopoulos, Constantinos V

2011-10-02

407

Quantitative Analysis of Transverse Bacterial Migration Induced by Chemotaxis in a Packed Column with Structured Physical Heterogeneity  

PubMed Central

A two-dimensional mathematical model was developed to simulate transport phenomena of chemotactic bacteria in a sand-packed column designed with structured physical heterogeneity in the presence of a localized chemical source. In contrast to mathematical models in previous research work, in which bacteria were typically treated as immobile colloids, this model incorporated a convective-like chemotaxis term to represent chemotactic migration. Consistency between experimental observation and model prediction supported the assertions that (1) dispersion-induced microbial transfer between adjacent conductive zones occurred at the interface and had little influence on bacterial transport in the bulk flow of the permeable layers and (2) the enhanced transverse bacterial migration in chemotactic experiments relative to nonchemotactic controls was mainly due to directed migration toward the chemical source zone. Based on parameter sensitivity analysis, the results showed that chemotactic parameters determined in bulk aqueous fluid were adequate to predict the microbial transport in our intermediate-scale porous media system. Additionally, the analysis of adsorption coefficient values supported the observation of a previous study that microbial deposition to the surface of porous media might be decreased under the effect of chemoattractant gradients. By quantitatively describing bacterial transport and distribution in a heterogeneous system, this mathematical model serves to advance our understanding of chemotaxis and motility effects in granular media systems and provides insights for modeling microbial transport in in situ microbial processes.

Wang, Meng; Ford, Roseanne M.

2009-01-01

408

Biosurfactant-producing and oil-degrading Bacillus subtilis strains enhance oil recovery in laboratory sand-pack columns.  

PubMed

Microbial Enhanced Oil Recovery (MEOR) technology uses microorganisms and their metabolites to retrieve unrecoverable oil from mature reservoirs. In situ stimulation of biosurfactant-producing and oil-degrading microorganisms reduces the capillary forces retaining the oil inside the reservoir and decreases its viscosity, thus promoting oil flow and consequently production. In this work, a sand-pack column model was designed to simulate oil recovery operations and evaluate mobilization of residual oil by the selected microorganisms. Four different hydrocarbon mixtures and three Bacillus subtilis strains isolated from crude oil samples were used. Additional oil recoveries ranged from 6 to 24% depending on the hydrocarbon mixture and microorganism used. Biosurfactant production was observed with all the microorganisms and hydrocarbon mixtures studied. The oils recovered after incubation with B. subtilis isolates showed a reduction in the percentage of long-chain n-alkanes and lower viscosity when compared with the original oils. The results obtained suggest that stimulation of the selected B. subtilis strains in situ can contribute to mobilize entrapped oil in mature reservoirs. PMID:23911831

Gudiña, Eduardo J; Pereira, Jorge F B; Costa, Rita; Coutinho, João A P; Teixeira, José A; Rodrigues, Lígia R

2013-07-08

409

Biofilm Growth in Porous Media: Validation of three-dimensional characterization of biofilm growth in packed bead columns  

NASA Astrophysics Data System (ADS)

Current understanding of subsurface microbial biofilm formation and the impact on fluid hydrodynamics associated with biofilm growth is limited by our ability to observe the in situ pore-scale geometry of developed biofilms. Biomass distribution in porous media has been observed primarily in two-dimensional systems to date; currently, no high-resolution three-dimensional structural data sets exist for opaque porous media that provide sufficient information about biomass distribution such that the impact on flow and solute transport at the pore-scale can be directly assessed. A new method for resolving high-resolution three-dimensional tomographic images of biofilms in porous media using synchrotron-based x-ray microtomography has been developed. As a part of this method, silver coated, neutrally buoyant microspheres are used to delineate the surface of the biofilm within porous media. Quantitative validation of this method will be presented along with three-dimensional characterization of biofilm growth in packed bead columns. Current and future applications for this imaging method include quantitative experimental validation of mathematical models pertaining to spatial distribution of biofilm and variation in hydrodynamic flow pathways within porous media. Our current research into this area focuses on evaluating microbially mediated co-precipitation of heavy metals in porous media. Results will be presented from new imaging experiments comparing different microbes and varying flow rates to address effects of biofilm type and density on the image quality.

Iltis, G.; Armstrong, R. T.; Jansik, D. P.; Wood, B. D.; Wildenschild, D.

2009-12-01

410

Comparison of general rate model with a new model--artificial neural network model in describing chromatographic kinetics of solanesol adsorption in packed column by macroporous resins.  

PubMed

Herein, two models, the general rate model taking into account convection, axial dispersion, external and intra-particle mass transfer resistances and particle size distribution (PSD) and the artificial neural network model (ANN) were developed to describe solanesol adsorption process in packed column using macroporous resins. First, Static equilibrium experiments and kinetic experiments in packed column were carried out respectively to obtain experimental data. By fitting static experimental data, Langmuir isotherm and Freundlich isotherm were estimated, and the former one was used in simulation coupled with general rate model considering better correlative coefficients. The simulated results showed that theoretical predictions of general rate model with PSD were well consistent with experimental data. Then, a new model, the ANN model, was developed to describe present adsorption process in packed column. The encouraging simulated results showed that ANN model could describe present system even better than general rate model. At last, by using the predictive ability of ANN model, the influence of each experimental parameter was investigated. Predicted results showed that with the increases of particle porosity and the ratio of bed height to inner column diameter (ROHD), the breakthrough time was delayed. On the contrary, an increase in feed concentration, flow rate, mean particle diameter and bed porosity decreased the breakthrough time. PMID:17289066

Du, Xueling; Yuan, Qipeng; Zhao, Jinsong; Li, Ye

2007-01-26

411

Conception et Realisation d'UN Simulateur de Colonne Garnie Fonctionnant Sous Pression Atmospherique et Sous Pression Reduite (Design and Construction of a Packed Column Simulator Operating under Atmospheric and Reduced Pressure).  

National Technical Information Service (NTIS)

Distillation under reduced pressure for the separation of constituants is considered. To avoid thermic damage in columns, the most important parameters are pressure loss and resistance time. The development of a simulator, enabling the determination of th...

A. Messaoudene

1989-01-01

412

Extractive Distillation: A Review  

Microsoft Academic Search

Extractive distillation is more and more commonly applied in industry, and becomes an important separation method in chemical engineering. This paper provides an in?depth review for extractive distillation. Separation sequence of the columns, combination with other separation processes, tray configuration and operation policy are included in process of extractive distillation. Since the solvent plays an important role in the design

Zhigang Lei; Chengyue Li; Biaohua Chen

2003-01-01

413

Adsorptive removal of fluoride from aqueous medium using a fixed bed column packed with Zr(IV) loaded dried orange juice residue.  

PubMed

The potential of the adsorbent prepared from DOJR marketed as cattle food in Japan was identified as an efficient and low cost adsorbent for fluoride using fixed bed column. DOJR was loaded with Zr(IV) ions to develop active adsorption sites for fluoride. Fluoride adsorption performance of column packed with Zr(IV) loaded DOJR was assessed under variable operating conditions such as Zr(IV) loading temperature, initial fluoride concentration, bed depth, initial pH, and flow rate. Breakthrough curve modeling showed that Thomas and bed depth service time (BDST) models were in good agreement with the experimental data. Application of adsorbent investigated in this study to the treatment of actual waste plating solution containing fluoride ion showed successful removal below acceptable standard in Japan using a fixed bed column, hence, Zr(IV)-DOJR can be expected to be a promising candidate for the treatment waste water containing trace amount of fluoride ion in fixed bed column. PMID:23916190

Paudyal, Hari; Pangeni, Bimala; Inoue, Katsutoshi; Kawakita, Hidetaka; Ohto, Keisuke; Alam, Shafiq

2013-07-10

414

Removal of NH4 Ion from NH4Cl Solution Using Clinoptilolite: A Dynamic Study Using a Continuous Packed?Bed Column in Up?Flow Mode  

Microsoft Academic Search

An investigation, in the form of dynamic experiments, was designed to investigate equilibrium and kinetic information for the ammonium ion?exchange of clinoptilolite. The process consisted of a packed?bed column operated in up?flow mode. A number of experiments were carried out at laboratory scale. The total ionic strength was kept constant in all runs, and made to resemble the ionic environment

N. P. Hankins; S. Pliankarom; N. Hilal

2005-01-01

415

Calculation procedure to determine average mass transfer coefficients in packed columns from experimental data for ammonia–water absorption refrigeration systems  

Microsoft Academic Search

The ammonia purification process is critical in ammonia–water absorption refrigeration systems. In this paper, a detailed\\u000a and a simplified analytical model are presented to characterize the performance of the ammonia rectification process in packed\\u000a columns. The detailed model is based on mass and energy balances and simultaneous heat and mass transfer equations. The simplified\\u000a model is derived and compared with

Jaime Sieres; José Fernández-Seara

2008-01-01

416

Investigation of the Combined Effects of External Mass Transfer and Biodegradation Rates on Phenol Removal Using Immobilized P. putida in a Packed-Bed Column Reactor  

Microsoft Academic Search

A quantitative analysis of external mass transfer combined with a biodegradation reaction and correlation of the experiment with theory was performed for phenol removal using calcium-alginate gel-immobilized P. putida in a packed-bed column reactor. Assuming first-order biodegradation kinetics, pseudo first-order biodegradation rate constants (kp) were calculated. To investigate the effect of external film diffusion on the biodegradation rate, various mass

Zümriye Aksu; Gültaç Bülbül

1998-01-01

417

A comparative study for the biosorption characteristics of chromium(VI) on ca?alginate, agarose and immobilized c vulgaris in a continuous packed bed column  

Microsoft Academic Search

A comparative biosorption of chromium(VI) ions to Ca?alginate and agarose biopolymers and immobilized C. vulgaris, a green alga was investigated. The experiments were carried out in a packed bed column operated in a continuous mode, as a function of the flow rate and inlet chromium(VI) ion concentration. The removal percentage of chromium(VI) ions related to the effluent volumes were also

Z. Aksu; G. Egretli; T. Kutsal

1999-01-01

418

On-line solid phase extraction system using PTFE packed column for the flame atomic absorption spectrometric determination of copper in water samples  

Microsoft Academic Search

A new flow injection on-line adsorption preconcentration system adapted to flame atomic absorption spectrometry (FAAS) for copper determination at the ?g l?1 level was developed. Polytetrafluoroethylene (PTFE) turnings packed in a mini-column were used as sorbent material. The copper ammonium pyrrolidine dithiocarbamate (APDC) complex was sorbed on the PTFE turnings, from which it could be eluted on-line instantly by isobutyl

Aristidis N. Anthemidis; George A. Zachariadis; John A. Stratis

2001-01-01

419

Computational study of the band broadening in two-dimensional etched packed bed columns for on-chip high-performance liquid chromatography  

Microsoft Academic Search

The chromatographic performance of several straightforward two-dimensional etched packed bed column lay-outs (equilaterally staggered arrays of, respectively, circular, hexagonal, and diamond-like pillars) has been compared using commercial computational fluid dynamics software. In all cases, the bed porosity was kept at ?=0.4 and a retained component with zone capacity ratio k?=2 was considered. Exploring the use of six different possible characteristic

P. Gzil; J. De Smet; N. Vervoort; H. Verelst; G. V. Baron; G. Desmet

2004-01-01

420

A comparative study using HPLC and packed column supercritical fluid chromatography for the assay of three anti-psychotic dosage forms  

Microsoft Academic Search

A reproducible and selective method was developed for the analysis of three anti-pschycotics, i.e. haloperidol, trifluoperazine and trihexyphenidyl in bulk and dosage forms using packed column supercritical fluid chromatography (SFC). The analytes were resolved by elution with supercritical fluid carbon dioxide doped with 16.67% (v\\/v) methanol containing 0.8% isopropylamine. Parallel studies were performed by HPLC using ion pairing reagent and

Yagnesh P Patela; U. J Dhorda; M Sundaresan

1998-01-01

421

On the extra-column band-broadening contributions of modern, very high pressure liquid chromatographs using 2.1 mm I.D. columns packed with sub-2 ?m particles  

Microsoft Academic Search

The efficiencies of two narrow bore columns (100mm and 50mm×2.1mm) packed with 1.7?m totally porous BEH-C18 particles were measured on two very high pressure liquid chromatographs (Acquity from Waters and 1290 Infinity HPLC System from Agilent) operating at maximum pressures of 1034 and 1200bar, respectively. The probe compounds were a mixture of uracil, acetophenone, toluene, and naphthalene eluted in a

Fabrice Gritti; Georges Guiochon

422

Understand the limitations of air/water testing of distillation equipment  

SciTech Connect

Distillation continues to be a unit operation of major importance--and a dynamic area for technical development. The designs of trays and packings are rapidly evolving, and the application of equipment also is changing. As chemical processes are pushed to become more efficient and lower cost, a general reduction in the traditional values for equipment safety factors are being seen. The net results is that one now has a greater need for a more thorough and fundamental understanding of distillation equipment. One technique to improve the understanding of distillation equipment is air/water testing. Such testing of distillation trays has become very common, and air/water test results for packed columns also are being reported. In this article, the authors will provide some guidance on how to assess the validity of such tests to industrial applications. In addition, they will discuss several possible approaches to test--and develop confidence in--the design of distillation equipment.

Bennett, D.L.; Ludwig, K.A. (Air Products and Chemicals, Inc., Allentown, PA (United States))

1994-04-01

423

Free Boundary Problems in Distillation  

Microsoft Academic Search

Design and scaleup of distillation equipment requires an understanding of the vapor-liquid equilibria as well as an understanding of the column hydraulics. This work focuses on two problems of fluid mechanics important in understanding the behavior of distillation columns: the shapes and stability of dielectric drops in an electric field and the flow patterns on distillation trays. Axisymmetric equilibrium shapes

Frederick Karl Wohlhuter

1992-01-01

424

Distillation and absorption  

SciTech Connect

Two volumes, focusing on dynamics and control, packing, absorption and other mass transfer processes, synthesis and simulation, trays, and vapor liquid equilibria. These volumes are reference sources for distillation and absorption, equipment manufacture, and pharmaceuticals.

Haselden, G.G.

1988-01-01

425

The dynamic behavior of a stratified column bed packed with porous adsorbent particles having partially fractal structures and a nonuniform ligand density distribution.  

PubMed

The dynamic behavior of adsorption in a single column and in stratified column beds packed with porous adsorbent particles having partially fractal structures is studied when all columns have the same total length and the spatial ligand density distribution in the porous microspheres from which the porous adsorbent particles are made, is either uniform or nonuniform and such that the concentration of the immobilized ligands (active sites) increases monotonically from the center of the microspheres to their outer surface. The total number of immobilized ligands in the porous adsorbent particles has the same value whether the spatial ligand density distribution is uniform or nonuniform. The results in this study clearly show that for a given value of the superficial velocity of the flowing fluid stream in the column (for a given value of throughput) the breakthrough time is significantly increased when the radius of the microspheres is decreased, the total number of sections of the stratified column bed is increased, and the spatial ligand density distribution employed in the microspheres is nonuniform. Furthermore, when the superficial velocity of the flowing fluid stream in the column is increased (throughput is increased) the effect that (i) the reduction in the radius of the microspheres and (ii) the increase in the number of sections of the stratified column bed have on providing robust and effective dynamic adsorptive capacity and smaller reductions on the breakthrough time is substantially larger than that realized through the use of the nonuniform ligand density distribution. Similar trends are also observed in the dynamic behavior of adsorption in the systems studied here when the value of the concentration of the adsorbate in the flowing fluid stream entering the column (inlet concentration) has such a high magnitude that the value of the equilibrium concentration of the adsorbate in the adsorbed phase determined from the equilibrium Langmuir isotherm that would correspond to the inlet concentration of the adsorbate in the flowing fluid stream is, for all practical purposes, at its saturation limit. PMID:23225711

Li, Min; Liapis, Athanasios I

2012-12-01

426

Dealcoholized wines by spinning cone column distillation: phenolic compounds and antioxidant activity measured by the 1,1-diphenyl-2-picrylhydrazyl method.  

PubMed

Spinning cone column (SCC) distillation has been shown to be a commercially suitable technique for dealcoholized wine (DW) manufacturing, but there are not enough studies about its influence on the DW quality. So, the effect of this technique on the antioxidant activity (% of remaining 1,1-diphenyl-2-picrylhydrazyl radical) and the phenolic compound composition of red, rose, and white DW, obtained at pilot plant scale, has been analyzed. Nineteen raw wines (RWs) from different grape varieties and five different Spanish viticultural regions have been studied before and after dealcoholization. The total phenolic content, flavonols, tartaric esters, and anthocyanins, was determined by spectrophotometry, while the content of phenolic compounds such as stilbenes (trans- and cis-resveratrol), flavonols (rutin, quercetin, and myricetin), flavan-3-ols [(+)-catechin and (-)-epicatechin], anthocyanins (malvidin 3-glucoside), and non-flavonoids (gallic, caffeic, and p-coumaric acids) was determined by high-performance liquid chromatography (HPLC). The resveratrol contents in red wines were between 1.81 and 34.01 mg/L in RWs and between 2.12 and 39.57 mg/L in DWs, Merlot being the grape producing the RWs and DWs with higher resveratrol content. In general, the percent of remaining DPPH(*) was similar or slightly higher (until 5 units of % of remaining DPPH(*)) in DWs versus RWs. This small difference may be due to removal of SO2 (that is an antioxidant) from RWs during distillation. DWs and RWs show similar contents of the studied phenolic compounds, with a tendency, in some cases, to exhibit increases after dealcoholization, caused by the concentration effect via removal of the ethanol. From this work, we can deduce that SCC distillation is a dealcoholization technique minimally destructive with the wine phenolic compounds. PMID:19588980

Belisario-Sánchez, Yulissa Y; Taboada-Rodríguez, Amaury; Marín-Iniesta, Fulgencio; López-Gómez, Antonio

2009-08-12

427

Synthesis of azeotropic batch distillation separation systems  

Microsoft Academic Search

The sequencing of batch distillation systems, in particular batch distillation columns, can be complicated by the existence of azeotropes in the mixture. These azeotropes can form batch distillation regions where, depending on the initial feed to the batch column, the types of feasible products and separations are limited. It is very important that these distillation regions are known while attempting

Boyd T. Safrit; Arthur W. Westerberg

1997-01-01

428

Transport and transformation of sulfadiazine in soil columns packed with a silty loam and a loamy sand  

Microsoft Academic Search

Concerning the transport of the veterinary antibiotic sulfadiazine (SDZ) little is known about its possible degradation during transport. Also its sorption behaviour is not yet completely understood. We investigated the transport of SDZ in soil columns with a special emphasis on the detection of transformation products in the outflow of the soil columns and on modelling of the concentration distribution

M. Unold; R. Kasteel; J. Groeneweg; H. Vereecken

2009-01-01

429

Mass transfer model for the film countercurrent flow of two liquid phases in a packed bed column 1 Dedicated to Professor K.R. Westerterp on the occasion of his 70th birthday. 1  

Microsoft Academic Search

Previously, the film flow of two liquids in a packed bed column was not very often encountered in industrial practice and was therefore not intensively investigated. Now however, the significance of this kind of flow has increased because of the rapid development of column supercritical extraction, where the film flow is frequently observed. In this study, a mass transfer model

S Wro?ski; E Molga

1998-01-01

430

Silicon isotope separation by distillation of silicon tetrafluoride  

SciTech Connect

Silicon isotopes were separated by distilling silicon tetrafluoride in a 150-cm packed column at temperatures of 189-206 K. The data show a reverse isotope effect with heavy isotopes more volatile in this temperature range. At total reflux, the maximum column separations were 0.926 for {sup 28}Si/{sup 29}Si and 0.872 for {sup 28}Si/{sup 30}Si. Carbon monoxide was also distilled in the column to obtain an estimated number of separating stages. From an estimated HETP of 2 cm for the packing, the volatility of {sup 28}Si is 0.9990 relative to {sup 29}Si and 0.9982 relative to {sup 30}Si. The SiF{sub 4} isotope effect is the largest yet found in distilling silicon compounds, and the effect is opposite that seen for SiH{sub 4}. The magnitude of the isotopic relative volatilities is large enough to consider SiF{sub 4} distillation as a practical method for silicon isotopic enrichment. This effect of higher mass isotopes being more volatile has analogues in isotope effects in SF{sub 4} and BF{sub 3}.

Mills, T.R. (Los Alamos National Lab., NM (USA))

1990-03-01

431

Volatile Components of Milk Fat Steam Distillates Identified by Gas Chromatography and Mass Spectrometry[1] and [2  

Microsoft Academic Search

Yacuum steam distillates of buttcroil, fresh raw cream, fresh pasteurized cream, and pasteurized stored cream were ana- lyzed by packed column and open-tubular colunm gas chromatography in conjunc- tion with ms~ss spectrometry. High-tem- perature (210 C) distillations of different butteroils yielded over 120 volatile com- pounds. Identification (or tentative identi- fication) of more than 100 of these com- pounds was

T. J. Siek; R. C. Lindsay

1968-01-01

432

Entrance effect and gas-film mass-transfer coefficient in a large-diameter packed column  

Microsoft Academic Search

The effects of the bed height and the entrance section below the packing support on mass transfer in a 1.2-m diameter packed bed of 50-mm ceramic Intalox saddles were investigated under various gas flow rates from 1,957 to 7,828 kg\\/h {sm_bullet}m² and liquid flow rates from 12,200 to 46,700 kg\\/h {sm_bullet}m². The entrance effect accounted for 17% of the overall

H. D. Doan; M. E. Fayed

2000-01-01

433

Hybrid Sargassum-sand sorbent: A novel adsorbent in packed column to treat metal-bearing wastewaters from inductively coupled plasma-optical emission spectrometry.  

PubMed

Laboratory batch and column experiments were carried out to examine the efficiency of algal-based treatment technique to clean-up wastewaters emanating from inductively coupled plasma-optical emission spectrometry (ICP-OES). Chemical characterization revealed the extreme complexity of the wastewater, with the presence of 14 different metals under very low pH (pH = 1.1), high conductivity (6.98 mS/cm), total dissolved solid (4.46 g/L) and salinity (3.77). Batch experiments using Sargassum biomass indicated that it was possible to attain high removal efficiencies at optimum pH of 4.0. Efforts were also made to continuously treat ICP-OES wastewater using up-flow packed column. However, swelling of Sargassum biomass leads to stoppage of column. To address the problem, Sargassum was mixed with sand at a ratio of 40: 60 on volume basis. Remarkably, the hybrid Sargassum-sand sorbent showed very high removal efficiency towards multiple metal ions with the column able to operate for 11 h at a flow rate of 10 mL/min. Metal ions such as Cu, Cd, and Pb were only under trace levels in the treated water until 11 h. The results of the treatment process were compared with trade effluent discharge standards. Further the process evaluation and cost analysis were presented. PMID:23947707

Vijayaraghavan, K; Joshi, U M

2013-01-01

434

Cumene by catalytic distillation  

SciTech Connect

Catalytic distillation, a combination of catalytic reaction and distillation in a single column, has several advantages when used in a process to make cumene from benzene and propylene. An extremely high purity cumene is obtained in high yield. The catalytic distillation principle was used in an earlier process to make MTBE. A unit, started up up in Houston refinery in 1981, operated successfully for four years. Since then, three other MTBE units of this design have gone into service.

Shoemaker, J.D.; Jones, E.M. Jr.

1987-06-01

435

Comparative study of HPLC column packings for the separation of aromatic and polar compounds in fossil fuel liquids  

Microsoft Academic Search

This paper reports a study on normal phase high performance liquid chromatography (HPLC) separations of aromatic and polar compounds using the following packing materials: Nucleosil NOâ; Nucleosil NHâ; Nucleosil CN; Nucleosil SA; Lichrosorb Si-5; Lichrosorb Al-5; and TSK 111. The retention data of model aromatic compounds on each stationary phase are summarized. The largest factor (K') was obtained by using

A. Matsunaga; S. Kusayanagi

1981-01-01

436

Copolymer of Di (methacryloyloxymethyl) naphthalene and divinylbenzene as a column packing for high-performance liquid chromatography  

Microsoft Academic Search

A new porous polyaromatic ester packing was synthetized for high performance liquid chromatography. The relationship between retention and chain length of the members of homologous series of alkylbenzenes, N-alkylanilines, alkylarylethers, alkylbenzoates and alkylarylketones on this new stationary phase using different eluents was investigated. Using the alkylarylketone scale the retention indices of the homologues and test compounds were calculated. The results

B. Gawdzik; J. Gawdzik; U. Czerwi?ska-Bil

1988-01-01

437

Entrance effect and gas-film mass-transfer coefficient in a large-diameter packed column  

SciTech Connect

The effects of the bed height and the entrance section below the packing support on mass transfer in a 1.2-m diameter packed bed of 50-mm ceramic Intalox saddles were investigated under various gas flow rates from 1,957 to 7,828 kg/h {sm_bullet}m{sup 2} and liquid flow rates from 12,200 to 46,700 kg/h {sm_bullet}m{sup 2}. The entrance effect accounted for 17% of the overall water vapor transferred from moist air to a calcium chloride solution in the tower, regardless of the packing height. For a 0.91-m high bed, the average mass-transfer coefficient was directly proportional to the gas rate and was proportional to the liquid rate to the power of 0.24. For a 1.8-m high bed, the average mass-transfer coefficient was proportional to the gas rate to the power of 0.89 and appeared to be independent of the liquid rate. The height of a transfer unit (HTU) for 50-mm ceramic Intalox saddles remained relatively constant under various gas rates used in the present study. The HTU was about 0.5 m for the short bed and 0.8 m for the tall bed.

Doan, H.D.; Fayed, M.E.

2000-04-01

438

On-line extraction of polymers, oligomers, additives and monomers by multiple solvents on packed HPLC columns  

Microsoft Academic Search

Extraction of monomers, additives, oligomers, and polymers from a blend is very time consuming and labor intensive. Now by use of a special guard column and multi-solvent gradient liquid chromatograph (HPLC), the extraction and analysis can be performed in one step.

W. J. Staal; PJCH Cools; A. M. van Herk; A. L. German

1993-01-01

439

Mathematical Models of Absorption of Poorly Soluble Gas in Co-Current Packed Bed Column under Periodically Changing Conditions  

Microsoft Academic Search

An eight-parameter mathematical model of absorption of poorly soluble gas in co-current column with interfacial mass transfer under transient conditions has been for- mulated. The model describes the liquid stream by axially dispersed plug flow with stag- nant and dynamic zones and the gas stream by axially dispersed model. The result of the model solution has the form of four

H. Vychodilová; V Jiøièný

440

Hydraulic Mass-Exchange Characteristics of a Rectification Column with Spiral-Prismatic Packing in Krypton and Xenon Purification Processes  

Microsoft Academic Search

The technology of krypton and xenon purification in modern installations making high-purity products is based on low-temperature rectification of multicomponent mixtures (MCMs). The economic efficiency of the purification processes is determined to a considerable extent by the sophistication of the rectification column design. Years of experience from the production of inert gases show that the best results in this regard

A. M. Arkharov; M. Yu. Savinov; V. L. Bondarenko; A. S. Bronshtein

2003-01-01

441

Optical resolution HPLC column packings carrying penicillin sulfoxide nucleus. Part III. Radical copolymers and their optical resolution efficiency  

Microsoft Academic Search

A methacrylamide carrying penicillin sulfoxide skeleton, benzyl 1-oxo-6-methacrylaminopenicillanate, was copolymerized with methyl methacrylate. The optical resolution efficiency of the columns comprising the obtained copolymers was investigated using a high-performance liquid chromatography system. A copolymer incorporated by 27mol% of methyl methacrylate showed higher chirality recognition capability than the homopolymer, which suggests that the introduction of methyl methacrylate contributes to enriching desired

Y. Saotome; T. Miyazawa; T. Endo

1989-01-01

442

Decolorization of Reactive Red K-2BP wastewater in fixed-bed column system packed sponge iron  

Microsoft Academic Search

The decolorization of Reactive Red K-2BP wastewater with sponge iron in a fixed-bed column system was evaluated at different influent water qualities (pH, dye concentration), particle diameter of sponge iron and filtrate rate. The decolorization efficiencies at influent pH of 6 were superior to those at influent pH of 5 and 7.5. The decolorization efficiency decreased with increments of filtration

Yan Wang; Mengchun Gao; Yandun Wang; Zichao Wang; Heng Yu

2010-01-01

443

Fast analysis of isoflavones by high-performance liquid chromatography using a column packed with fused-core particles  

Microsoft Academic Search

The recent development of fused-core technology in HPLC columns is enabling faster and highly efficient separations. This technology was evaluated for the development of an fast analysis method for the most relevant soy isoflavones. A step-by-step strategy was used to optimize temperature (25–50°C), flow rate (1.2–2.7mL\\/min), mobile phase composition and equilibration time (1–5min). Optimized conditions provided a method for the

N. Manchón; M. D’Arrigo; A. García-Lafuente; E. Guillamón; A. Villares; A. Ramos; J. A. Martínez; M. A. Rostagno

2010-01-01

444

Methanol Distillation Optimization  

Microsoft Academic Search

Michigan BioDiesel, LLC of Bangor, Michigan has called for an analysis of their methanol distillation process. The goal of this project was to determine the current operating parameters of the column and suggest improvements to the operation of the column in order to maximize the amount of methanol recovered as product and minimize the amount of waste. It was also

Kristen L. Bellmer; Scott Sherrod

2011-01-01

445

Relationship between the particle size distribution of commercial fully porous and superficially porous high-performance liquid chromatography column packings and their chromatographic performance.  

PubMed

The separation efficiency and kinetics of several commercial HPLC particle types (both fully porous and superficially porous) have been investigated using a pharmaceutical weakly basic N-containing compound as a test molecule. A strong trend between the particle size distribution (PSD) of the particles and the typically employed "goodness of packing"-parameters was observed. The relative standard deviation of the PSD of the tested particles ranged between 0.05 and 0.2, and in this range, a near linear relationship between the A-term constant, the h(min)-value and the minimal separation impedance was found. The experimental findings hence confirm the recent observations regarding the relationship between the narrow PSD of the recently commercialized porous-shell particles and their superior efficiency and kinetic performance. The outcome also suggests that the performance of the current generation of fully porous particle columns could be significantly improved if the PSD of these particles could be reduced. PMID:20870241

Cabooter, D; Fanigliulo, A; Bellazzi, G; Allieri, B; Rottigni, A; Desmet, G

2010-09-21

446

Control of a fractional distillation process  

SciTech Connect

In a fractional distillation process in which a heating fluid and waste heat stream are utilized to supply heat to a fractional distillation column and in which the heat supplied from the waste heat stream is not controllable, control of the liquid level in the fractional distillation column is accomplished by manipulating the flow rate of the heating fluid so as to maintain a desired liquid level until such time as the flow rate of the heating fluid becomes zero at which time the flow rate of the external reflux to the fractional distillation column is manipulated to maintain a desired liquid level in the fractional distillation column. A switching of control of the liquid level provides a means by which an uncontrollable heat input may be provided to the fractional distillation column without losing control of the liquid level in the fractional distillation column.

Skraba, F.W.; Tuck, L.

1983-03-22

447

Limit Cycles in Homogeneous Azeotropic Distillation  

Microsoft Academic Search

In spite of significant nonlinearities even in the simplest model, the distillation literature generally takes for granted that distillation columns display relatively simple dynamic behavior. For example, although widely observed in chemical reactors, any instances of periodic oscillations have not yet been associated with models of distillation columns. In this paper we study the steady-state and dynamic behavior of the

Moonyong Lee; Cornelius Dorn; George A. Meski; Manfred Morari

1999-01-01

448

Characterization of Column Packings in Normal-Phase Liquid Chromatography. II. Retention Behavior of Fat-Soluble Vitamins in Amino and Cyano-Propyl Bonded Silica Gel and Binary Solvent Systems  

Microsoft Academic Search

As continuation of our study on the characterization of column packings in normal-phase HPLC analysis, the retention indices of ten fat-soluble vitamins on aminopropyl and cyanopropyl bonded silica columns were systematically estimated using binary solvents containing ethyl acetate (EtOAc), tetrahydrofuran (THF) or 2-propanol (PrOH) in n-hexane. A linear relationship between the logarithm of the capacity ratio and that of the

Tatsuhiko Ando; Yoshiyuki Nakayama; Shoji Hara

1989-01-01

449

On-line preconcentration and determination of nickel and zinc in natural water samples by flow injection–flame atomic absorption spectrometry using PTFE-turnings for column packing  

Microsoft Academic Search

A rapid, sensitive and low cost, time-based flow injection atomic absorption spectrometric method was described for the determination of nickel and zinc upon on-line preconcentration on a micro-column packed with polytetrafluoroethylene-turnings material. The metals formed on-line complexes with ammonium pyrrolidine dithiocarbamate from acidified solutions (pH 2.0) in the flow manifold and retained in the column. The preconcentrated elements were subsequently

Aristidis N. Anthemidis; George A. Zachariadis; John A. Stratis

2010-01-01

450

Sorption of Pb(II) onto a mixture of algae waste biomass and anion exchanger resin in a packed-bed column.  

PubMed

Sorption of Pb(II) was studied by using a biosorbent mixture of algae waste biomass and Purolite A-100 resin in a packed-bed column. Mixing these two components was done to prevent the clogging of the column and to ensure adequate flow rates. Increasing of solution flow rate and initial Pb(II) concentration make that the breakthrough and saturation points to be attained earlier. The experimental breakthrough curves were modeled using Bohart-Adams, Thomas and Yoon-Nelson models, and the parameters for all these models were calculated. A regeneration efficiency of 98% was achieved using 0.1 mol L(-1) HCl and not significant changes in lead uptake capacity after three biosorption/desorption cycles were noted. The biosorbent mixture was able to remove Pb(II) from synthetic wastewater at pH 5.0 and flow rate of 3.5 mL min(-1), and the obtained effluent has better quality characteristics. The biosorbent mixture it is suitable for a continuous system for large-scale applications. PMID:23262014

Bulgariu, Dumitru; Bulgariu, Laura

2012-11-07

451

Ammonia removal from wastewaters using natural Australian zeolite. 2. Pilot-scale study using continuous packed column process  

SciTech Connect

A pilot-scale process was designed and operated to investigate the continuous removal of ammonia from sewage using natural zeolite from Australia. The process consisted of a fixed-bed ion-exchange system operated in the downflow mode. Evaluation of the pilot process was initially undertaken for ammonia removal from tap water spiked with ammonium chloride to provide performance data in the absence of competing cations. The performance of the pilot process was then assessed using sewage as feed. Breakthrough curves were constructed for a range of treatment flow rates. Existing models for packed bed performance were shown to be able to predict the breakthrough behavior of the process. The results of a study are presented that show that Australian natural zeolite, clinoptilolite, may be successfully employed in a fixed-bed ion-exchange process to achieve high ammonia removal efficiencies from aqueous solution at rates commensurate with sand filtration. The rate of uptake of ammonium by the zeolite is sufficient to support a continuous high rate process.

Cooney, E.L.; Booker, N.A.; Shallcross, D.C.; Stevens, G.W.

1999-10-01

452

Catalytic distillation extends its reach  

SciTech Connect

Since the early 1980s, catalytic distillation processes have been selected by more than a hundred operators for various applications. Since such a unit performs both reaction and distillation simultaneously, a combined column can replace a separate, fixed-bed reactor and distillation column, thereby eliminating equipment and reducing capital costs. And, compared to the conventional approach, catalytic distillation may also improve other factors, such as reactant conversion, selectivity, mass transfer, operating pressure, oligomer formation and catalyst fouling. The constant washing of the catalyst by liquid flowing down the column and the distillation of high-boiling foulants results in extended catalyst life. Four selective hydrogenation applications of catalytic distillation are discussed: Butadiene selective hydrogenation combined within an MTBE unit; Pentadiene selective hydrogenation; C{sub 4} acetylene conversion; and Benzene saturation.

Rock, K.; McGuirk, T. [Catalytic Distillation Technologies, Houston, TX (United States); Gildert, G.R. [Catalytic Distillation Technologies, Pasadena, TX (United States)

1997-07-01

453

Investigation related to hydrogen isotopes separation by cryogenic distillation  

SciTech Connect

Research conducted in the last fifty years has shown that one of the most efficient techniques of removing tritium from the heavy water used as moderator and coolant in CANDU reactors (as that operated at Cernavoda (Romania)) is hydrogen cryogenic distillation. Designing and implementing the concept of cryogenic distillation columns require experiments to be conducted as well as computer simulations. Particularly, computer simulations are of great importance when designing and evaluating the performances of a column or a series of columns. Experimental data collected from laboratory work will be used as input for computer simulations run at larger scale (for The Pilot Plant for Tritium and Deuterium Separation) in order to increase the confidence in the simulated results. Studies carried out were focused on the following: - Quantitative analyses of important parameters such as the number of theoretical plates, inlet area, reflux flow, flow-rates extraction, working pressure, etc. - Columns connected in series in such a way to fulfil the separation requirements. Experiments were carried out on a laboratory-scale installation to investigate the performance of contact elements with continuous packing. The packing was manufactured in our institute. (authors)

Bornea, A.; Zamfirache, M.; Stefanescu, I.; Preda, A.; Balteanu, O.; Stefan, I. [INC-DTCI-ICSI Rm. Valcea, str.Uzinei, Nr.4, 240050 (Romania)

2008-07-15

454

Modelling reactive distillation  

Microsoft Academic Search

The design and operation issues for reactive distillation systems are considerably more complex than those involved for either conventional reactors or conventional distillation columns. The introduction of an in situ separation function within the reaction zone leads to complex interactions between vapor–liquid equilibrium, vapor–liquid mass transfer, intra-catalyst diffusion (for heterogeneously catalysed processes) and chemical kinetics. Such interactions have been shown

R. Taylor; R. Krishna

2000-01-01

455

Flooding characteristics of Goodloe packing  

Microsoft Academic Search

Experimental flooding data for the countercurrent flow of air and water in a 7.62-cm-diam glass column filled with Goodloe packing were compared with a correlation reported by the packing manufacturer. Flooding rates observed in this study were as low as one-half those predicted by the correlation. Rearranging the packing by inverting the column and removing some packing segments yielded results

J. M. Begovich; J. S. Watson

1976-01-01

456

Determination of kinetic parameters in the biosorption of Cr (VI) on immobilized Bacillus cereus M(1)(16) in a continuous packed bed column reactor.  

PubMed

Due to technological advancement, environment suffers from untreated toxic heavy metal bearing effluent coming from different industries. Chromium (VI) is one of those heavy metals having adverse impact on ecological balance, human, and plant health because of its carcinogenic properties. Biosorption is presented as an alternative to traditional technologies which are costly and inefficient for treatment of industrial wastes containing low amount of heavy metals. In this study, bioremediation of Cr (VI) ions by immobilized Bacillus cereus M(1) (16) was investigated in a laboratory scale packed bed up-flow column reactor. The effect of important parameters, such as the inlet flow rate, influent concentration, and effective bed height, has been studied. External mass transfer, surface adsorption, and intrabead mass transfer were also studied to conclude the rate limiting step for removal of Cr (VI) and to determine the process parameters which are important for biosorption optimization. The external mass transfer coefficient was calculated at different flow rates (6.51 x 10(-2) to 7.58 x 10(-2) cm/min). Using the model, the surface adsorption rate constant (k(ad)) and the intrabead mass transfer coefficient (k (i)) were predicted as 0.0267 x 10(-3) and 0.7465 x 10(-3) l/g/min, respectively. Both are much lower than the external mass transfer coefficient (k(e)). The surface adsorption phenomenon is acting as the rate-limiting step due to its high resistance for removal of Cr (VI). PMID:19333567

Maiti, Soumen K; Bera, Debabrata; Chattopadhyay, Parimal; Ray, Lalitagauri

2009-03-31

457

Synthesis of separation systems for azeotropic mixtures: Preferred distillation region  

Microsoft Academic Search

An algorithm for automatic generation of sequences of distillation columns and decanters for separation of azeotropic mixtures has been developed where distillation boundaries can be crossed by moving them with pressure change, by exploring curvatures of distillation boundaries or by liquid-liquid splits in decanters. Based on a broad knowledge of distillation regions and distillation boundaries for the separated mixture, open-loop

Stanislaw K. Wasylkiewicz

2006-01-01

458

Kinetics and effectiveness of catalyst for synthesis of methyl tert-butyl ether in catalytic distillation  

SciTech Connect

The macrokinetics and intrinsic kinetics were measured for synthesis of methyl tert-butyl ether (MTBE) within the catalyst bed packed in a special way in an industrialized catalytic distillation column. The corresponding kinetic equations for forward and backward reactions were obtained. The variation of total effectiveness factor of the catalyst considering the diffusion in the catalyst pocket and within a granule of catalyst with reaction temperature and diameter of the pocket was calculated from the results measured. It was indicated that the effect of the catalyst packed in this way could not be revealed under the present operation condition.

Xu, X.; Zheng, Y.; Zheng, G. [Tianjin Univ. (China). Dept. of Chemical Engineering

1995-07-01

459

Evaluation of monolithic and sub 2 microm particle packed columns for the rapid screening for illicit drugs--application to the determination of drug contamination on Irish euro banknotes.  

PubMed

A study comparing recently available 100 x 3 mm id, 200 x 3 mm id monolithic reversed-phase columns with a 50 x 2.1 mm id, 1.8 microm particle packed reversed-phase columns was carried out to determine the most efficient approach (using traditional van Deemter analysis and a modern kinetic plot approach) for the rapid screening of samples for 16 illicit drugs and associated metabolites. A plot of column backpressure versus plate number (N) showed a significant advantage of using the monolithic phases, with the 20 cm monolithic column exhibiting a maximum 15,000 plates at a column backpressure of approximately 70 bar, compared to approximately 7000 plates at 150 bar for the 5 cm 1.8 microm particle packed column. Optimum linear velocities were found to be 0.40 mm s(-1), 0.52 mm s(-1) and 0.98 mm s(-1) for the three above columns, respectively. The 20 cm monolithic column was subsequently applied to the separation and determination of illicit drug contamination on Irish euro banknotes, using methanol extraction followed by LC-MS/MS. Method performance data showed that the new LC-MS/MS method was significantly more sensitive than previous GC-MS/MS based methods for this application, with detection limits in the pg note(-1) region, based upon a 20 microL standard injection. All of the notes examined tested positive for trace quantities of cocaine, with benzoylecgonine detected on 12 of the 45 notes sampled. Traces of heroin were also detected on three of the 45 notes. PMID:17325753

Bones, Jonathan; Macka, Mirek; Paull, Brett

2007-01-08

460

Effect of parallel segmented flow chromatography on the height equivalent to a theoretical plate. I-performance of 4.6mm×30mm columns packed with 3.0?m Hypurity-C18 fully porous particles.  

PubMed

The mass transfer kinetics in short and wide 4.6mm×30mm columns packed with 3.0?m Hypurity-C18 fully porous particles were measured for three different configurations of the inlet sample distribution and outlet sample collection: (1) both the inlet and outlet column endfittings are standard, (2) the inlet endfitting is standard while the outlet endfitting allows parallel segmentation of the exiting flow between a central and a peripheral region across the column diameter, and (3) both the inlet and outlet endfittings allow a parallel segmentation of the flow entering and exiting the column, respectively. The total reduced heights equivalent to a theoretical plate (HETP) were carefully measured, using the first and second central moments of the elution band profiles, obtained by its accurate numerical integration. The longitudinal diffusion term was measured at the lowest experimental reduced velocity applied. The solid-liquid mass transfer resistance was estimated from measurements of the intra-particle diffusivity using the Torquato's model of effective diffusion in packed beds. The trans-channel and short-range interchannel eddy diffusion HETP terms were taken from data obtained by solving numerically the Navier-Stokes equations and simulating advective-diffusive transport in computer-generated random sphere packings. The results clearly show that the trans-column eddy diffusion HETP term can account for up to 85% of the total intrinsic HETP (corrected for extra-column contributions) of the standard columns. Parallel segmented flow chromatography can reduce this contribution by half at high velocities, by eliminating most of the baseline peak tailing. This holds true irrespective of the retention factor of the analyte. It was found also that segmenting the inlet/outlet flow increases detection sensitivity by 25-50% for peaks with large to small retention factors, respectively. In practice, the advantage of parallel segmented flow chromatography in gradient elution (thin peak widths) is essentially limited by post-column bandspreading and diffusion in the dwell volume of the instrument used. Analyst should minimize post-column bandspreading (caused by connectors and detection cell volume) and synchronize the eluent composition in the peripheral and central inlet ports of the column, by using two separate pumps with appropriate dwell volumes. PMID:23706347

Gritti, Fabrice; Guiochon, Georges

2013-04-27

461

Complex binary distillation  

SciTech Connect

This procedure extends the McCabe-Thiele diagram to columns having multiple feeds, one or more side-products, one or more points of heat removal or addition, and any combination of these. Although derived for binary systems, the procedure can be adapted for multicomponent distillation.

Kister, H.Z.

1985-01-21

462

Network modeling of the convective flow and diffusion of molecules adsorbing in monoliths and in porous particles packed in a chromatographic column.  

PubMed

A cubic lattice network of interconnected pores was constructed to represent the porous structure existing in a monolith (continuous bed) or in a column packed with porous chromatographic particles. Expressions were also constructed and utilized to simulate, through the use of the pore network model, the intraparticle interstitial velocity and pore diffusivity of adsorbate molecules in porous chromatographic particles or in monoliths under retained and unretained conditions. The combined effects of steric hindrance at the entrance to the pores and frictional resistance within the pores, as well as the effects of pore size, pore connectivity, nT, of the porous network, molecular size of adsorbate and ligand (active site), and the fractional saturation of adsorption sites (ligands), have been considered. The results for the adsorption systems studied in this work, indicate that the obstruction effects on the intraparticle interstitial velocity, due to (a) the thickness of the immobilized layer of active sites and (b) the thickness of the adsorbed layer, are small and appear to be insignificant when they are compared with the very significant effect that the value of the pore connectivity, nT, has on the magnitude of the intraparticle interstitial velocity. The effective pore diffusion coefficient of the adsorbate molecules was found to decline with increasing molecular size of ligand, with increasing fractional saturation of the active sites or with diminishing pore size, and with decreasing pore connectivity, nT. The results also show that the magnitude of the interstitial fluid velocity is many times larger than the diffusion velocity of the adsorbate molecules within the porous adsorbent particles. Furthermore, the results clearly show that the intraparticle interstitial velocity and the pore diffusivity of the adsorbate increase significantly as the value of the pore connectivity, nT, of the porous medium increases. The results of this work indicate that the pore network model and the expressions presented in this work, could allow one, for a given porous adsorbent, adsorbate, ligand (active site), and interstitial column fluid velocity, to determine in an a priori manner the values of the intraparticle interstitial velocity and pore diffusivity within the monolith or within the porous adsorbent particles as the fractional saturation of the active sites changes. The values of these transport parameters could then be employed in the macroscopic models that could predict the dynamic behavior, scale-up, and design of chromatographic systems. The theoretical results could also have important implications in the selection of a ligand as well as in the selection and construction of an affinity porous matrix. PMID:10480225

Meyers, J J; Liapis, A I

1999-08-01

463

Rapid temperature-programmed separation of carbon monoxide and carbon dioxide on a packed capillary column in gas chromatography: application to the evaluation of photocatalytic activity of TiO2.  

PubMed

Carbon monoxide (CO) and carbon dioxide (CO2) were determined in a conventional capillary gas chromatography-flame ionization detector (GC-FID) by introducing a packed-capillary column and a methanizer. Due to good compatibility with rapid temperature-programmed operation of the packed capillary column, several volatile compounds, including CO and CO2, were rapidly eluted along with satisfactory resolution and sample loading capacity. The limit of quantifications of CO and CO2 were 5 and 3 ppm, respectively, with an injection volume of 0.5 mL. The developed system was then successfully applied to evaluating the photocatalytic decomposition of volatile organic compounds on titanium dioxide (TiO2). PMID:23749137

Ueta, Ikuo; Mizuguchi, Ayako; Tani, Kazue; Kawakubo, Susumu; Saito, Yoshihiro

2013-01-01

464

Simultaneous on-line preconcentration and determination of trace metals in environmental samples by flow injection combined with inductively coupled plasma mass spectrometry using a nanometer-sized alumina packed micro-column  

Microsoft Academic Search

A flow injection (FI) on-line preconcentration procedure by using a nanometer-sized alumina packed micro-column coupled to inductively coupled plasma mass spectrometry (ICP-MS) was described for simultaneous determination of trace metals (V, Cr, Mn, Co, Ni, Cu, Zn, Cd and Pb) in the environmental samples. The effects of pH value, sample flow rate, preconcentration time, and interfering ions on the preconcentration

Jun Yin; Zucheng Jiang; Gang Chang; Bin Hu

2005-01-01

465

The adsorption of copper (II) by Z. ramigera immobilized on Ca-alginate in packed bed columns: a dynamic approach by stimulus-response technique and evaluation of adsorption data by moment analysis  

Microsoft Academic Search

In this study, CuII adsorption by Z. ramigera immobilized on Ca-alginate was investigated in a packed bed column test circuit using a stimulus-response technique. The mathematical model was described and solved using “parameter estimation by cybernetic moment technique”, and the adsorption rate constant of CuII ions on Z. ramigera immobilized on Ca-alginate was calculated. The Péclet numbers, which reflect the

Mehmet Mutlu; Ye?im Sa?; Tülin Kutsal

1997-01-01

466

The adsorption of copper(II) by Z. ramigera immobilized on Ca-alginate in packed bed columns: a dynamic approach by stimulus-response technique and evaluation of adsorption data by moment analysis  

Microsoft Academic Search

In this study, CuII adsorption by Z. ramigera immobilized on Ca-alginate was investigated in a packed bed column test circuit using a stimulus-response technique. The mathematical model was described and solved using “parameter estimation by cybernetic moment technique”, and the adsorption rate constant of CuII ions on Z. ramigera immobilized on Ca-alginate was calculated. The Péclet numbers, which reflect the

Mehmet Mutlu; Ye?im Sa; Tülin Kutsal

1997-01-01

467

Rapid high performance liquid chromatography method development with high prediction accuracy, using 5 cm long narrow bore columns packed with sub-2 ?m particles and Design Space computer modeling  

Microsoft Academic Search

Many different strategies of reversed phase high performance liquid chromatographic (RP-HPLC) method development are used today. This paper describes a strategy for the systematic development of ultrahigh-pressure liquid chromatographic (UHPLC or UPLC) methods using 5cm×2.1mm columns packed with sub-2?m particles and computer simulation (DryLab® package). Data for the accuracy of computer modeling in the Design Space under ultrahigh-pressure conditions are

Szabolcs Fekete; Jen? Fekete; Imre Molnár; Katalin Ganzler

2009-01-01

468

Distillation stability using passivity and thermodynamics  

Microsoft Academic Search

Distillation is one of the most important unit operations in the chemical process industry. The stability of distillation systems has always been difficult to determine due to the nonlinear natural of the unit operation. Previous work in the area has had limited success and no theory has been able to show the stability criteria for a general multicomponent distillation column.

Duncan P. Coffey; B. Erik Ydstie; Chad A. Farschman

2000-01-01

469

Chromatographic distillation in petroleum product quality control  

Microsoft Academic Search

The extreme differences in the distillation temperatures of petroleum products are responsible for the existence of several standard methods for determining the distillation curves. In this paper, the feasibility was demonstrated of determining these curves on various petroleum products by chromatographic distillation, using the same procedure and the same apparatus in all cases. Mixtures were separated in a capillary column

G. G. Kholostova; G. S. Shimonaev; M. O. Burova

1988-01-01

470

Molten salt extractive distillation process for zirconium-hafnium separation  

Microsoft Academic Search

This patent describes an improvement in a process for zirconium-hafnium separation. It utilizes an extractive distillation column with a mixture of zirconium and hafnium tetrachlorides introduced into a distillation column having a top and bottom with hafnium enriched overheads taken from the top of the column and a molten salt solvent circulated through the column to provide a liquid phase,

D. F. McLaughlin; R. A. Stoltz

1989-01-01

471

The adsorption of CO(2)/H(2)O/N(2) on 5A zeolite and silica gel in a packed column in one and two-dimensional flows  

NASA Astrophysics Data System (ADS)

The purpose of this work is to develop a computer model that simulates the dynamic behavior of a Four-Bed Molecular Sieves (4-BMS) system. The system will be installed on the International Space Station for removal of CO 2/H2O/N2 on four beds that consist of 5A zeolite, 13X zeolite, and Silica gel. Due to the complexity of the actual 4-BMS, separately packed columns of 5A and Silica gel were built and tested using the model results to obtain the mass and heat transfer coefficients necessary for the development of the 4-BMS. This work begins by introducing the adsorption/desorption process in a packed column. The formulation of the simplest model of adsorption in a packed bed is developed assuming that Darcy's law. In this model, the mass and heat transport gradients are assumed to vary only in the axial direction, i.e., one-dimensional flow. The results of temperature and mass transfer breakthrough of one-dimensional flow are compared with the test results for adsorption of CO2/N2 and CO2/H2O/N2 on 5A zeolite. In the packed column near the wall boundary, the velocity decreases due to the viscous forces and the porosity increases exponentially. This near-wall region of higher porosity results in the channeling of fluid close to the wall surface. This channeling causes an early solute breakthrough relative to the center of the column. In order to accommodate the effect of porosity variation on the breakthrough, a two-dimensional model of the packed column is developed. The results of two-dimensional flow are compared with the test results for adsorption of CO2/N2 and CO2/H 2O/N2 on 5A zeolite. This work also investigates the dynamics of H2O adsorption on Silica gel material. A one-dimensional flow of a packed column bed is developed with the assumption that Darcy's law governs the momentum transport. The results of both models are compared with the test results for adsorption of H 2O/N2 on Silica gel. Finally, a computer model based on the obtained parameters of independent bench testing is developed to simulate the actual 4-BMS. The cyclical results of each bed of 4-BMS are presented to show the required time to reach the steady state operation. The experimental results from the laboratory scale-fixed bed adsorber are quantitatively consistent with the one-dimensional model at the center of the bed. The average concentration from the bed obtained from test results deviates from the column center concentration appreciably. This indicates the strong effects of porosity variation along the radial direction of the bed on the temperature, concentration, and velocity profile. The two-dimensional model not only accurately predicts the concentration and temperature profile at the column center, but it also predicts the average concentration reasonably well.

Mohamadinejad, Habib

472

Design of processes with reactive distillation line diagrams  

SciTech Connect

On the basis of the transformation of concentration coordinates, the concept of reactive distillation lines is developed. It is applied to study the feasibility of a reactive distillation with an equilibrium reaction on all trays of a distillation column. The singular points in the distillation line diagrams are characterized in terms of nodes and saddles. Depending on the characterization of the reactive distillation line diagrams, it can be decided whether a column with two feed stages is required. On the basis of the reaction space concept, a procedure for identification of reactive distillation processes is developed, in which the reactive distillation column has to be divided into reactive and nonreactive sections. This can be necessary to overcome the limitations in separation which result from the chemical equilibrium. The concentration profile of this combined reactive/nonreactive distillation column is estimated using combined reactive/nonreactive distillation lines.

Bessling, B. [BASF Ludwigshafen (Germany). Engineering Research and Development; Schembecker, G.; Simmrock, K.H. [Univ. of Dortmund (Germany). Dept. of Chemical Engineering

1997-08-01

473

Organic and inorganic selenium speciation in environmental and biological samples by nanometer-sized materials packed dual-column separation/preconcentration on-line coupled with ICP-MS.  

PubMed

A novel, fast, and cheap nonchromatographic method for direct speciation of dissolved inorganic and organic selenium species in environmental and biological samples was developed by flow injection (FI) dual-column preconcentration/separation on-line coupled with ICP-MS determination. In the developed technique, the first column packed with nanometer-sized Al(2)O(3) could selectively adsorb the inorganic selenium [Se(IV), Se(VI)], and the retained inorganic selenium could be eluted by 0.2 mol l(-1) NaOH, while the organic Se [selenocystine (SeCys(2)) and selenomethionine (Se-Met)] was not retained. On the other hand, the second column packed with mesoporous TiO(2) chemically modified by dimercaptosuccinic acid (DMSA) could selectively adsorb Se(IV) and SeCys(2) and barely adsorb Se(VI) and Se-Met. When the sample solution was passed through the column 1, separation of inorganic selenium and organic selenium could be achieved first. Then, the effluent from column 1 was successively introduced into the column 2 and the speciation of organic selenium could be attained due to the different adsorption behaviors of Se-Met and SeCys(2) on DMSA modified TiO(2). After that, the eluent from column 1 contained Se(IV), and Se(VI) was adjusted to desired pH and injected into column 2, and the speciation of Se(IV) and Se(VI) could also be realized thanks to their different retention on column 2. The parameters affecting the separation were investigated systematically and the optimal separation conditions were established. The detection limits obtained for Se(IV), Se(VI), Se-Met and SeCys(2) were 45-210 ng l(-1) with precisions of 3.6-9.7%. The proposed method has been successfully applied for the speciation of dissolved inorganic and organic selenium in environmental and biological samples. In order to validate the methodology, the developed method was also applied to the speciation of selenium in certified reference material of SELM-1 yeast, and the determined values were in good agreement with the certified values. PMID:17994643

Huang, Chaozhang; Hu, Bin; He, Man; Duan, Jiankun

2008-03-01

474

Effect of parallel segmented flow chromatography on the height equivalent to a theoretical plate II - Performances of 4.6mm×30mm columns packed with 2.6?m Accucore-C18 superficially porous particles.  

PubMed

The reduced trans-column (or long-range eddy dispersion) height equivalent to a theoretical plate (HETP) of short and wide 4.6mm×30mm columns packed with 2.6?m Accucore-C18 superficially porous particles was measured under conventional (no split flow) and parallel segmented (outlet and inlet) flow chromatography. The overall reduced HETP was derived from the true moments of the recorded concentration profiles. The longitudinal diffusion HETP term was measured at a very small flow rate (0.05mL/min). The solid-liquid mass transfer resistance was derived from the shell diffusivity, using the composite Garnett-Torquato model of effective diffusion in a heterogeneous system made of a dense packing of core-shell particles immersed in a continuous matrix (the eluent). The trans-channel and short-range interchannel eddy dispersion HETP terms were assumed to be equal to the calculated h data after solving the Navier-Stokes equation and simulating the advection-diffusion transport process. Experimental results confirmed that the optimum efficiency of these short columns was increased by a factor of about two. The ratio of the detection sensitivities on the PSFC stream and on a regular stream increased from 1 to 1.45 when the retention factor decreases from about 10 to 0.5. These phenomena are due to a strong reduction of the trans-column eddy dispersion HETP term. The system loses about 60% of the sample mass when only outlet skimming is carried out when the flow rate ratio of 55% is applied, as was done in this work. It loses about 50% of the sample when inlet/outlet segmentation is applied. In gradient elution, the peak capacity is increased by only 15%, due to post-column band spreading, which should imperatively be minimized when the outlet flow is split. PMID:24050598

Gritti, Fabrice; Guiochon, Georges

2013-09-03

475

Recovery of volatile aroma components from aqueous waste streams using an activated carbon column  

Microsoft Academic Search

The solid phase adsorption of aroma components depleted from essential oils and drained with the condensed water water during the distillation of aromatic plants onto granular activated carbon (GAC) is reported. A mini-column packed with laboratory-prepared activated carbon, derived from pistachio shells, which were previously treated with H3PO4 and pyrolysed at 500 °C, was used. Three aromatic waste waters (peppermint, lemongrass,

Amr E. Edris; Badie S. Girgis; Hoda H. M. Fadel

2003-01-01

476

Separation of azeotropic mixtures by batch distillation using an entrainer  

Microsoft Academic Search

Batch Distillation is an efficient unit operation which allows the separation of a multicomponent mixture into its components in a single column. However, the separation of azeotropic mixtures via distillation is quite complex because at the azeotrope liquid and gas have the same composition and, therefore, the driving force for distillation disappears. A systematical presentation of batch distillation processes for

R. Düssel; J. Stichlmair

1995-01-01

477

Importance of the selection of feed tray location on the optimum design of a heterogeneous azeotropic distillation column with p-xylene feed impurity  

Microsoft Academic Search

In the production of aromatic acid, such as terephthalic acid, tiny amounts of one reactant (in this study, p-xylene) may also enter into the acetic acid dehydration column through the feed stream. In this work, the process design flowsheets with and without this tiny impurity are both considered. For the case with this tiny impurity in the feed stream, a

I-Lung Chien; Hao-Yeh Lee; Tang-Kai Gau; Hsiao-Ping Huang

2006-01-01

478

Comparison of Commercial Column Types in Liquid Chromatography  

Microsoft Academic Search

Several commercially available liquid chromatographic column types have been experimentally evaluated. A conventionally-sized column containing 5 ?m packing, a microbore column containing 10 ?m packing, a column containing 3 ?m packing, and two short, wide-bore columns containing 5 ?m packing were compared at optimum velocity (van Deemter minimum) and at twice the optimum velocity where possible. All columns contained reversed-phase

R. W. McCoy; R. E. Pauls

1982-01-01

479

Azeotropic distillation  

Microsoft Academic Search

Recent and ongoing research in the distillation of nonideal mixtures is reviewed focusing on advances in the methodologies for the synthesis, design, analysis and control of separation sequences involving homogeneous and heterogeneous azeotropic towers. Maps of residue curves and distillation lines are examined, as well as geometric methods for the synthesis and design of separation sequences, trends in the steady-state

Soemantri Widagdo; Warren D. Seider

1996-01-01

480

Treatment of chlorinated solvents by nitrogen-fixing and nitrate-supplied methane oxidizers in columns packed with unsaturated porous media  

SciTech Connect

This study compares the feasibility of employing nitrogen-fixing and nitrate-supplied methane-oxidizing cultures grown in unsaturated porous media to degrade cis-1,2-dichloroethylene (cDCE) and trichloroethylene (TCE) in gas streams. Both nitrate-supplied and nitrogen-fixing columns degraded TCE completely at a gaseous concentration of 0.7 mg/L for 8--10 days. However, when columns were supplied with 4% CH{sub 4} and 10% O{sub 2}, nitrate-supplied columns were not able to recover after degrading TCE at a gaseous concentration of 0.13 mg/L for 7 days. In contrast, nitrogen-fixing columns recovered after degrading 0.13--0.4 mg/L TCE for 3--10 days and were capable of repeatedly degrading TCE at gaseous concentrations of 0.03--0.14 mg/L TCE for 3--10 days and were capable of repeatedly degrading TCE at gaseous concentrations of 0.03--0.14 mg/L during long-term intermittent operation that was punctuated by appropriate microbial recovery periods. Both nitrate-supplied and nitrogen-fixing columns were capable of degrading cDCE at concentrations of 0.7--1.0 mg/L for 5--10 days, but only the nitrogen-fixing columns recovered from cDCE exposure. The operating period for columns treating a mixture of TCE and cDCE was significantly shorter than that for treatment of TCE or cDCE alone. Several operating curves were developed to facilitate comparisons between operating conditions and to aid in predicting chlorinated solvent removals in such systems. Nitrogen-fixing columns consistently outperformed nitrate-supplied columns, and columns inoculated with a mixed culture outperformed those inoculated with Methylosinus trichosporium OB3b for TCE removal but not for cDCE removal.

Chu, K.H.; Alvarez-Cohen, L.

2000-05-01

481

Method for packing chromatographic beds  

DOEpatents

Column chromatography beds are packed through the application of static force. A slurry of the chromatography bed material and a non-viscous liquid is filled into the column plugged at one end, and allowed to settle. The column is transferred to a centrifuge, and centrifuged for a brief peri