Determination of flooding gas velocity and liquid hold-up at flooding in packed columns for gas/liquid systems

1990 ◽  
Vol 13 (1) ◽  
pp. 184-196 ◽  
Author(s):  
Jerzy Maćkowiak
Keyword(s):  
Packed Columns ◽  
Gas Velocity ◽  
Liquid Systems

Systematic errors in equilibrium composition of ternary liquid-liquid systems and their effect on the calculated number of theoretical stages of countercurrent extraction

1988 ◽  
Vol 53 (6) ◽  
pp. 1172-1180
Author(s):  
Ján Dojčanský ◽  
Soňa Bafrncová ◽  
Július Surový
Keyword(s):  
Equilibrium Composition ◽  
Systematic Errors ◽  
Liquid Equilibrium ◽  
Countercurrent Extraction ◽  
Liquid Systems ◽  
Equilibrium Concentrations ◽  
Line Slope ◽  
Tie Line ◽  
Calculated Number

The influence of magnitude of systematic errors in the determination of ternary liquid-liquid equilibrium concentrations on the accuracy of the calculated number of theoretical stages of countercurrent extraction is evaluated on using five hypothetical systems differing in the extent of mutual solubility of components, tie-line slope, and type of binodal curve.

Wide-Bore Capillary Gas Chromatographic Determination of Organophosphorus Pesticide Residues in Foods: Interlaboratory Trial

1994 ◽  
Vol 77 (1) ◽  
pp. 92-101
Author(s):  
Charles H Parfitt
Keyword(s):  
Pesticide Residues ◽  
Stationary Phases ◽  
Packed Column ◽  
Capillary Columns ◽  
Packed Columns ◽  
Detector Response ◽  
Official Method ◽  
Methyl Silicone ◽  
Interlaboratory Trial

Abstract Wide-Bore capillary columns are often used as alternatives to traditionally packed columns for gas chromatographic (GC) determination of pesticide residues in foods. Fused silica columns with cross-linked, bonded stationary phases are reproducible, rugged, and easy to use and are substantially more inert than their packed column equivalents. An interlaboratory trial was conducted in 5 U.S. Food and Drug Administration laboratories to determine the practicability of using isothermal wide-bore capillary GC as an alternative to the packed column GC systems used in AOAC Official Methods for determining pesticide residues in foods. Two wide-bore capillary columns with flame photometric detection were evaluated with respect to the following: linearity of detector response; repeatability of response for equal and unequal injection volumes of standard solutions; accuracy of quantitating pesticides in food extracts when the injection volumes or analyte concentrations of the standard solution and the food extract are different; recoveries of 23 pesticides from 5 fortified food extracts, calculated from both duplicate and single injections; and relative retention times. Before shipment, food extracts supplied to participants were fortified with pesticides after preparation and extraction of the foods by Official Method 985.22. The performance of wide-bore capillary columns with cross-linked bonded methyl silicone and methyl phenyl silicone stationary phases was equal or superior to that of the packed columns specified in the Official Method.

Gas-Liquid Chromatographic Determination of TYans-Unsaturation in Fats and Oils on Packed Columns: Effect of Positional Isomers

1978 ◽  
Vol 61 (3) ◽  
pp. 702-708
Author(s):  
Henry B S Conacher ◽  
Jagannath R Iyengar
Keyword(s):  
Fats And Oils ◽  
Chromatographic Determination ◽  
Packed Columns ◽  
Gas Liquid Chromatography ◽  
Positional Isomers ◽  
Tubular Columns ◽  
Acid Isomerization ◽  
Cis And Trans ◽  
Liquid Chromatographic

Abstract Studies in our laboratories indicated that the trans contents of a number of commercial margarines, determined by gas-liquid chromatography (GLC) on a 15 ft column packed with 10% Silar IOC, were approximately 80-85% of those determined by infrared spectroscopy. This is mainly due to overlap of some of the trans positional isomers with the cis positional isomers in the octadecenoate fraction, shown by studies involving determination of the transoctadecenoate content of the margarines by silver ion thin layer chromatography/GLC, and by preparation and study of the GLC behavior of the cis and trans positional isomers of Δ6-, Δ9-, Δ12-, and Δl5-octadecenoates. The last 3 isomers were prepared by hydrazine reduction and nitrous acid isomerization of linoleic and linolenic acids. Since it is possible that longer, more efficient columns might result in better separation of the cis- and traru-octadecenoate isomers, it is recommended that studies be continued on longer packed columns (20 ft) and possibly on support-coated open tubular columns.

Mass Transfer Studies in a Novel Perforated Plate Bubble Column

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
S. Dhanasekaran ◽  
T. Karunanithi
Keyword(s):  
Mass Transfer ◽  
Liquid Velocity ◽  
Bubble Column ◽  
Perforated Plate ◽  
Gas Velocity ◽  
Plate Spacing ◽  
Mass Transfer Studies ◽  
Superficial Gas Velocity ◽  
Superficial Liquid Velocity

This investigation reports the experimental and theoretical results carried out to evaluate the volumetric mass transfer coefficient (kLa) in a novel hybrid rotating and reciprocating perforated plate bubble column. Countercurrent condition is performed. kLa is studied by the absorption of oxygen from air into deoxygenated water at room temperature (27 ± 1°C). Effects of agitation level, superficial gas velocity, superficial liquid velocity and plate spacing on kLa were analyzed and found to be significant. With an increase in agitation level at a constant superficial gas and liquid velocities, the breakage process of gas bubbles starts to be more pronounced and intensive oxygen mass transfer occurs. Hence, kLa increases sharply. kLa increases with an increase in superficial gas velocity, due to higher gas holdup and the enhanced breakup of bubbles. Similarly, kLa increases with an increase in superficial liquid velocity and the effect is found to be significant. When plate spacing is decreased (by increasing the number of plates), it is observed that the kLa increases at higher superficial gas velocity and agitation level. Correlation is developed for the determination of kLa and found to concur with experimental results. This correlation can be used for the determination of kLa for this hybrid column with 95% accuracy within the range of variables investigated in this present study.

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