Solid-liquid Extraction

Question 1

separation techniques

Answer 1

centrifugation
distillation
crystallization
filtration
extraction
chromatography
electrophoresis

Question 2

solid-liquid extraction process

Answer 2

-preparation of extraction material
-separation and recovery of the solvent extraction
-separation and recovery of solvent from extraction residual

Question 3

what is SPE and how does it work

Answer 3

solid phase extraction
solubilised material is passed through a solid medium which traps all the unwanted material and purifies the solution

Question 4

what is raffinate

Answer 4

liquid in which impurities have been removed

Question 5

to improve extraction efficiacy the solvent must be provided with large _______ ________ and ______ ______ pathways

Answer 5

exchange surfaces
diffusion pathways

Question 6

How can large exchange surfaces and short diffusion pathways be achieved

Answer 6

pulverising the solid to be extracted

Question 7

if the solute is ground too small what can happen

Answer 7

agglutination occurs
-makes it difficult for solvent to permeate

Question 8

How can large exchange surfaces and short diffusion pathways be achieved?

Answer 8

pulverizing the solid to be extracted

Question 9

three aspects that make a SCF effective

Answer 9

density similar to liquid
diffusion coefficent higher than liquid
viscosity similar to gas

Question 10

what is solvating power dictated by

Answer 10

density
polarity of SCF

Question 11

how do density and temperature affect power of SCf

Answer 11

power increases with density at a given temp
power increases with temp at a given density

Question 12

what effect does increasing the pressure of SCF

Answer 12

higher solubility due to increase density

Question 13

what can too much pressure do

Answer 13

plateau the increase in solubility due to increased viscosity and reduced diffusivity

Question 14

SCF characteristics

Answer 14

low viscosity
diffusion coefficient between liquid and gas
almost no surface tension
small change in P = large density change = higher solvating power

Question 15

how does an increae in T effect SCF

Answer 15

increase dynamic viscosity therefore diffusivity

Question 16

why id CO2 such a good SCF

Answer 16

best diffusivty
lowest viscosity
reasonable density
-cheapish and safe

Question 17

at what point on a phase diagram does a SCF appear

Answer 17

after critical point

Question 18

how can the fractionation phase be advantageous for SCF

Answer 18

allows unwanted products to be selectively removed
-short-chain fatty acids
-caffeine

Question 19

applications of SCF

Answer 19

-extraction of hops
-remove cholesterol from butter
-perfumes and flavours
-residual monomers and solvent from polymer formulations
-unsaturated fatty acids from fish oils

Question 20

temp and P CO2 becomes a SCF

Answer 20

31 C
72.9 bar

Question 21

how does the dielectric constant affect SCF

Answer 21

affects the solubility of solutes

Question 22

physical properties that change at critical point

Answer 22

-partial molar volume of SCF decreases
-thermal conductivity
-heat capacity

Question 23

describe what modifiers of SCF are

Answer 23

-molecules that cluster around solute molecules
-used in small amounts
-assist in dissolving polar solutes which are not normally highly soluble in SCF CO2

Question 24

frequently used modifiers

Answer 24

methanol
ethanol
propanol

Question 25

what is the hildebrand parameter

Answer 25

measures solvating power

Question 26

what does a high hildebrand parameter mean

Answer 26

wider range of solutes can be dissolved

Question 27

general rule for hildebrand parameter

Answer 27

solubility increases as density and temperature increases

Question 28

if a solute is a liquid where is it drained from?

Answer 28

the bottom of the seperator

Question 29

if the solute is a solid how is it drained?

Answer 29

extraction is halted and the solute is removed from the vessel

Question 30

describe butterfat fractionation

Answer 30

50-60C, 100-250 bar shorter chains are more soluble in SCF -requires multiple stages

Question 31

what is rho in equation

Answer 31

density

Question 32

________of cholesterol increases as ____ increases but ____________ is reduced

Answer 32

solubility rho selectivity

Question 33

real world application examples of SCF

Answer 33

cholesterol pepper oil butterfat fractionation ginger jasmine coffee seed oil

Question 34

how is pepper oil tradiitonally extracted and how much better is SCF

Answer 34

steam distillation of sequiterpenes normal: 26% SCF: 39% @ 40C, 49% @ 60C

Question 35

how is jasmine traditionally extracted

Answer 35

using ethanol

Question 36

what type of organic solvents are used to decaffeinate coffee beans

Answer 36

methylene chloride trichloroethylene ethyl acetate

Question 37

why is methyl chloride bad

Answer 37

has contirbuted to ozone hole

Question 38

describe the swiss water process

Answer 38

soak green beans in hot water strip caffiene using activated charcoal re soak beans in water roast

Question 39

why is de-gumming not required in SCF od seed oils

Answer 39

phospholipids are not co-extracted