Spinning band distillation is a technique used to separate liquid mixtures which are similar in boiling points. When liquids with similar boiling points are
distilled
Distillation, also classical distillation, is the process of separating the component substances of a liquid mixture of two or more chemically discrete substances; the separation process is realized by way of the selective boiling of the mixt ...
, the vapors are mixtures, and not pure compounds.
Fractionating column
A fractionating column or fractional column is equipment used in the distillation of liquid mixtures to separate the mixture into its component parts, or fractions, based on their differences in volatility. Fractionating columns are used in small ...
s help separate the mixture by allowing the mixed vapors to cool, condense, and vaporize again in accordance with
Raoult's law
Raoult's law ( law) is a relation of physical chemistry, with implications in thermodynamics. Proposed by French chemist François-Marie Raoult in 1887, it states that the partial pressure of each component of an ideal mixture of ''liquids'' is ...
. With each condensation-vaporization cycles, the vapors are enriched in a certain component. A larger surface area allows more cycles, improving separation.
Spinning band distillation takes this concept one step further by using a spinning helical band made of an inert material such as metal or
Teflon
Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene, and has numerous applications because it is chemically inert. The commonly known brand name of PTFE-based composition is Teflon by Chemours, a spin-off from ...
to push the rising vapors and descending condensate to the sides of the column, coming into close contact with each other. This speeds up equilibration and provides for a greater number of condensation-vaporization cycles.
Applications
Spinning band distillation may sometimes be used to recycle waste solvents which contain different solvents, and other
chemical compound
A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...
s.
See also
*
Spinning cone
References
* B/R Instrument Corporation
Spinning Band Distillation accessed 27 Oct, 2006.
* B/R Instrument Corporation
accessed 27 Oct 2006.
* Marshall Space Flight Center
Accessed 27 Oct 2006.
{{Distillation
Distillation
Separation processes
Laboratory equipment
Chemical equipment