This set of Bioseparation Processes Multiple Choice Questions & Answers (MCQs) focuses on “Cross-Current Continuous Extraction using Immiscible Solvents”.
1. What is the significance of given the diagram?
a) Cross current continuous multi stage extraction
b) Batch multi stage extraction
c) Multistage extraction
d) Batch extraction
View Answer
Explanation: The process of extraction in the given diagram is limited by the equilibrium constant and for recovery of the residual solutes from the Raffinate stream, one stage is continued with the further stages and the various multiple stages are formed for the cross current continuous extraction process of various stages.
2. The fresh extracting solvents are added in the stages for the extraction process in the process of cross current extraction?
a) False
b) True
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Explanation: The fresh solvent is fed into the stages at every stage then the extract is obtained at corresponding stages which allows the stream of the extract to combine together in order to obtain the extract from overall stages and removing the Raffinate from the last stage.
3. How can one solve the cross current extraction system in bioseparation?
a) Single stage extraction
b) Batch extraction
c) Multiple stages extraction
d) Multi stage batch extraction
View Answer
Explanation: The cross current extraction process can be solved using multiple stages which includes the initiation of the extraction process with the first stage followed by the obtaining of Raffinate then the extraction of the concentration along with the forwarding of the substitutes of the values.
4. What are the basic assumptions involved in the cross current extraction system?
a) Equilibrium at each stage, same equilibrium for all the stages
b) Equilibrium at each stage
c) Negligible entrainment of other phases
d) Negligible entrainment of other phases, Equilibrium at each stage, same equilibrium for all the stages
View Answer
Explanation: The basic assumptions involved in the cross current extraction system are: the Raffinate as well as the extract streams from each stage are in equilibrium, there is no entrainment of other phase, the same equilibrium relationship holds good for all the stages, i.e. the value of K is independent of solute concentration.
5. What is the equation for concentration of extract applied in the cross current continuous extraction process?
a) CEi = \(\frac{-KC_{Ri-1}}{1 + \lambda_i}\)
b) CEi = \(\frac{KC_{Ri1}}{1 + \lambda_i}\)
c) CEi = \(\frac{KC_{Ri-1}}{1 + \lambda_i}\)
d) CEi = \(\frac{K-C_{Ri-1}}{1 + \lambda_i}\)
View Answer
Explanation: The equation for the cross current continuous extraction process is CEi = \(\frac{KC_{Ri-1}}{1 + \lambda_i}\) where, i is the number of stages, K is the equilibrium constant, CRi-1 is the ith stage of concentration of the Raffinate.
6. What is the equation for the concentration of Raffinate in the cross current extraction system?
a) CRi = \(\frac{-C_{Ri-1}}{1 + \lambda_i}\)
b) CRi = \(\frac{C_{Ri-1}}{1 + \lambda_i}\)
c) CRi = –\(\frac{-C_{Ri-1}}{1 + \lambda_i}\)
d) CRi = \(\frac{-C_{Ri}}{1 + \lambda_i}\)
View Answer
Explanation: The equation for the concentration of Raffinate in the cross current extraction system is CRi = \(\frac{C_{Ri-1}}{1 + \lambda_i}\) where, CRi-1, the concentration of Raffinate is available at the previous stage than the ith stage of the continuous extraction process.
7. What is the significance of λi in the equation CRi = \(\frac{C_{Ri-1}}{1 + \lambda_i}\) used in the cross current extraction system?
a) λi = \(\frac{KQ_{E,1}}{Q_R}\)
b) λi = \(\frac{KQ_{E1}}{Q_R}\)
c) λi = \(\frac{KQ_{E}}{Q_R}\)
d) λi = \(\frac{Q_{E,1}}{Q_R}\)
View Answer
Explanation: The λi in the equation CRi = \(\frac{C_{Ri-1}}{1 + \lambda_i}\) stands for λi = \(\frac{KQ_{E,1}}{Q_R}\) where, it is the extraction factor for ith stage of extraction process.
8. What is the disadvantage of cross current extraction process?
a) Increasing the concentration of driving forces
b) Diminishing the concentration of Raffinate and extract
c) Increasing the concentration of Raffinate and extract
d) Diminishing the concentration of driving forces
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Explanation: The cross current extraction process under the continuous mode of collecting the Raffinate and the extract being obtained by every stage of the extraction process requires some driving forces for the being maintained in the system, but the process does not help in maintaining the driving forces and it diminishes the driving forces.
9. Which process of extraction can overcome the drawback of the cross current extraction process?
a) Batch current extraction
b) Staged counter current extraction
c) Upstaged counter current extraction
d) Downstage counter current extraction
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Explanation: The process of staged counter current over comes the drawback of diminishing the concentrations of the driving forces, it refers to the extraction in the form of chain formed for the counter current cascades.
10. Calculate the extraction factor for the 5th stage of the cross current extraction process, when the partition coefficient is 2.5 and the flow rate of initial solvent is 5.5 m3/s and the flow rate of extracting solvent at 5th stage is 3.5 m3/s.
a) 1.4
b) 1.5
c) 1.6
d) 1.7
View Answer
Explanation: The etxraction factor of 5th stage is λi = \(\frac{KQ_{E,1}}{Q_R}\) = \(\frac{2.5 × 3.5}{5.5}\) = 1.6.
Sanfoundry Global Education & Learning Series – Bioseparation Processes.
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