Liquid-liquid extraction - 2012

Class date(s):	23 to 26 October 2012
Download video: Link [102 M]
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Download video: Link [119 M]

We start this section by looking at liquid-liquid extraction.

References

Please use these references to read ahead, or for extra background reading on liquid-liquid extraction. In alphabetical order:

• Ghosh, R. "Principles of Bioseparations Engineering", Chapter 7, McMaster (reserve)
• Geankoplis, C.J. "Transport Processes and Separation Process Principles", Chapter 12 in 3rd and 4th edition, McMaster Libraries (reserve)
• Perry's Chemical Engineers' Handbook, Chapter 15, Direct link (McMaster subscription)
• Richardson and Harker, "Chemical Engineering, Volume 2", 5th edition, Chapter 13 ebook
• Schweitzer, "Handbook of Separation Techniques for Chemical Engineers", Chapter 1.9, McMaster library
• Seader, Henley and Roper, "Separation Process Principles", Chapter 8 in 2nd and 3rd edition McMaster Libraries (reserve)

Interesting applications / Enrichment materials

• An article on liquid-liquid extraction which describes the various units available.
• The flowsheet for separating acetic acid from water using ethyl acetate solvent. This flowsheet has the mass flow rates, to help contrast it to distillation.

click to enlarge

Week 8

23 Oct 2012 (08A)

• Slides for class
• Audio and video recording of the class.

25 Oct 2012 (08B)

• Slides for class
• Audio and video recording of the class.

26 Oct 2012 (08C)

• Slides for class
• Audio and video recording of the class.
• Three photos of the board during class

click to enlarge

click to enlarge

click to enlarge

Week 9

30 Oct 2012 (09A)

We will consider single and multiple co-current extraction.

• Slides for class
• Audio and video recording of the class.
• Photo of the board during class

click to enlarge

31 Oct 2012 (09B)

We should be able to wrap up the section by studying counter-current liquid-liquid extraction.

• Slides for class (slides 42 to 59). Please print slides 48 to 54 on large, single pages, to assist your learning.
• Audio and video recording of the class.
• Photo of the board during class

click to enlarge

01 Nov 2012 (09C)

• There will be no formal teaching in class today. You can ask questions about assignment 4, and there will be a tutorial question from assignment 5.

Consider a system for which you have been given the ternary diagram (see slides, p 58). \(A\) = solute, \(S\) = solvent, \(C\) = carrier. The feed, \(F\) enters at 112 kg/hr with composition of 25 wt% solute and 75 wt% carrier.

1. Calculate the flow and composition of the extract and raffinate from:
   • 1st co-current stage, using a pure solvent flow of 50 kg/hr.
   • 2nd co-current stage, with an additional solvent flow of 50 kg/hr.
2. For the overall 2-stage system, find the:
   • overall recovery
   • overall concentration of combined extract streams

The next objective is to have a counter-current system so the raffinate leaving in the \(N^\text{th}\) stage, \(R_N\) has \(y_{R_N} = 0.025\)

1. What is the maximum allowable solvent flow?
2. Explain whether it's possible to achieve an extract stream of \(y_{E_1} = 0.21\)?
3. Show the construction on the ternary diagram for the number of equilibrium stages to achieve \(y_{R_N} = 0.025\), given a solvent flow of 60 kg/hr.
4. Plot on the same axes the concentrations in the extract and raffinate streams.