An Efficient Low-Holdup Laboratory Column

Abstract

DiscussionFrom the graphs presented it is obvious that it is possible to measure the blue color developed with antimony trichloride with accuracy, even though the rate of change in the intensity of color is rapid.An attempt was made to slow down the rate of fading of the blue color through addition of acids, dehydrating agents, or phenols ( 7 ) . Of the materials tried phosphoric acid seemed the most efficient, but its effect was only apparent, since a slight cloudiness developed in the solution that tended to compensate for the fading of the blue color.Fading continued progressively beyond the readings given, although a t a slower rate, but on the more dilute solution was complete in from 5 to 10 minutes.

60-Plate Low-Holdup Laboratory Fractionating Column

“…(13.5 inches). Adding concentric tubes of the diameters and clearances specified by Selker, Burke, and Lankelma (11) gave an . E. T. P. of 15.75 cm.…”

“…Recognition of the great need of efficient columns for the separation of small quantities of material is shown by the development of 70-to 100-plate columns of extremely small holdup, such as those of Stedman (2), Selker, Burke, and Lankelma (11), and Baker, Barkenbus, and Roswell (1).…”

“…per plate, and the Selker-Burke-Lankelma column 0.04 ml. per plate (11). Holdup was determined with stearic acid by the method of Tongberg, Quiggle, and Fenske (13), by the drainage method, and by pouring a known quantity into the top of the warm dry column and measuring the drainable and nondrainable quantities.…”

Theory of Open-Tube Distillation Columns

“…compensating factors whose total for equilibrium operation is zero. Term (a) is due to the existence of a radial concentration gradient; analogous to this is the radial conduction of heat into a cylinder (8). Term (6) is due to the established vertical concentration gradient.…”

Efficient Column Suitable for Vacuum Fractionation

“…E. T. P. values of short and long columns, as indicated by some authors (1, 4, 5, 9), but is perhaps, in a larger measure, due to difficulties of construction, as experienced in this laboratory. Although Selker et al (18) succeeded in constructing a column 5 feet (142.5 cm.) long, ordinarily the difficulties encountered are so serious as to render the use of such columns impracticable, except for short lengths.…”