Liq-liq extraction

Question 1

stagewise contact in liq-liq extraction

Answer 1

1. single contact (equal to equilibrium distillation)
2. co-current multiple contact or simple multi-stage contact
3. counter current multi-stage or multiple contact
   - with reflux (equal to fractional distillation)
   -w/out reflux
   - continuous contact (differential contact)

Question 2

relative enrichment of solute in extract phase compared in the raffinate phase after one stage

Answer 2

separation factor

Question 3

defined for a given solute as the solute concentration in the extract phase divided by in the raffinate phase can be obtained in a single stage of contacting

Answer 3

Partition ration, K

Question 4

it is thermodynamic potential of a solvent to extract a certain solute (can be a factor of temperature and composition)

Answer 4

K-value

Question 5

capacity of the extract phase to carry the solute relative to the feed phase

Answer 5

Extraction factor, E

Question 6

extraction factor, E, determines largely the

Answer 6

Theo

Question 7

required solute to transfer from feed to extract phase

Answer 7

N

Question 8

extraction factor, E, is analogous to

Answer 8

stripping factor in distillation

Question 9

the maximum concentration that extract phase can hold for a solute or else the two solvent will not coexist anymore or the solute will precipitate and become the barrier of the two solvents

Answer 9

loading capacity

Question 10

they allow operation with minimal solvent that’s why ideal for economical purpose

Answer 10

higher partition ration (equal or greater than 10)

Question 11

what mutual solubility is ideal?

Answer 11

low

Question 12

The solvent should have little tendency to react with the product to avoid by-products

Answer 12

stability

Question 13

what is the preferred density difference between the solvent and feed phase to get a high liq-liq separation?

Answer 13

0.1 to 0.3 g/mL

Question 14

_____ viscosity is preferred since higher viscosity generally increases mass- transfer resistance and liquid-liquid phase separation difficulty.

Answer 14

Low

Question 15

Preferred ______ values for interfacial tension between the feed phase and the extraction solvent phase generally are in the range of _________.

Answer 15

high, 5 to 25 dyn/cm

Question 16

The economical recovery of solvent from the extract and raffinate is critical to commercial success. Solvent properties should facilitate ______ options for recovery, recycle and storage

Answer 16

low-cost

Question 17

solvent properties

Answer 17

• low cost
• anticipated ambient temperature
• ## low potential for fire and reactive chemistry hazards

Question 18

Solvents that are liquids at all anticipated ambient temperatures are
desirable since they avoid the need for freeze protection and/or thawing of frozen
solvent prior to use.

Answer 18

freezing point

Question 19

Solvents with low potential for fire and reactive chemistry hazards are
preferred as inherently safe solvents. In all cases, solvents must be used with
awareness of potential hazards and in a manner consistent with measures needed
avoid hazards.

Answer 19

Safety

Question 20

Solvents with low mammalian toxicity and good warning properties are desired. Low toxicity and low dermal absorption rate reduce the potential for injury through acute exposure.

Answer 20

Industrial hygiene

Question 21

The solvent must have physical or chemical properties that allow effective control of emissions from vents and other discharge streams.
Preferred properties include low aquatic toxicity and low potential for fugitive
emissions from leaks or spills.

Answer 21

Environmental requirements

Question 22

It is desirable to use as the extraction solvent a material that can serve
a number of purposes in the manufacturing plant. This avoids the cost of storing and handling multiple solvents. It may be possible to use a single solvent for a number of different extraction processes practiced in the same facility, either in different equipment operated at the same time or by using the same equipment in a series of product campaigns.

Answer 22

Multiple uses

Question 23

It is desirable for a solvent to allow the use of common, relatively inexpensive materials of construction at moderate temperatures and pressures.

Answer 23

Materials of construction

Question 24

The solvent should be readily available at a reasonable cost. Considerations include the initial fill cost, the investment costs associated with maintaining a solvent inventory in the plant (particularly when expensive extractants are used), as well as the cost of makeup solvent.

Answer 24

Availability and cost