Lecture 4

Question 1

separates the cells from suspension by forcing a fluid through a filtering medium by applying positive pressure to the upstream side of the vacuum to the downstream side

Answer 1

Conventional filtration

• Nutsche Filter
• Continuous rotary vacuum filter

Question 2

Equation: rate of filtration

Answer 2

d Volume of filtrate/d time = (surface area of the filter * pressure difference)/viscosity of the filtrate (resistance of cake + resistance of filter medium)

dVf/dt = A deltap/ mu f (rc + rm)

Question 3

Resistance of cake

Answer 3

resistance of cake=average specific resistance * (mass of solids deposited per volume of filtrate * volume of filtrate/ surface area of the filter)

Question 4

Average specific resistance for compressible cake

Answer 4

average specific resistance = constant dependent (pressure resistance)^cake compressibility

Question 5

the action or process of using a centrifuge, typically to separate fluids of different densities or liquids from solids.

Answer 5

Centrifugation

https://www.ecosia.org/search?addon=chrome&addonversion=6.0.2&q=centrifugation%20definition

Question 6

In continuous separation, for operations at constant centrifuge speed, solids recovery is ________ proportional to the inlet flow rate

Answer 6

inversely

Question 7

In continuous separation, for operations at constant centrifuge speed, flow rate increases as solid recovery _____

Answer 7

decreases

Question 8

In continuous separation, for operations at constant centrifuge speed, flow rate ________ as solid recovery decreases

Answer 8

increases

Question 9

Equal effectiveness for the same centrifuge

Answer 9

Q/ω^2 = Q/ω^2

Question 10

Examples of centrifuges

Answer 10

• Tubular bowl centrifuge
• Continuous decanter centrifuge

Question 12

How centrifuge works

Answer 12

using the principle of sedimentation. Under the influence of gravitational force, substnces separate according to their density

Question 13

relative centrifugal force (RCF) equation

Answer 13

g = (1.118 * 10^-5) R S^2

Avoid centrifugal forces higher than 5000x g

Question 14

method or process for releasing biological molecules from inside a cell

Answer 14

cell disruption

https://en.wikipedia.org/wiki/Cell_disruption

Question 15

2 methods of cell disruption

Answer 15

mechanical and non mechanical

Question 16

Mechanical methods of cell disruption

Answer 16

• ultrasonics
• bead mills
• waring-type blender
• high pressure homogenisation

Question 17

Non mechanical methods

Answer 17

• freezing
• osmotic shock
• chemical solubilsation

Question 18

Application of ultrasonic energy to cell suspensions by a sonicator

Answer 18

ultrasonics

Question 19

mechanical grinding of cell suspensions with grinding media such as glass beads

Answer 19

bead mills

Question 20

homogenisation by stirring blades

Answer 20

waring type blender

Question 21

discharge of pressurised cell suspension flow through valves involving impingement

Answer 21

high pressure homogenisation

Question 22

repeated cycles of freezing and thawing disrupt cells through ice crystal formation. Multiple cycles are necessary for efficient lysis

Answer 22

Freezing

Question 23

Cells exposed to rapid changes in external osmolarity can be injured. THis procedure is typically conducted by first allowing the cells to equilibrate internal and external osmotic pressure in a high sucrose medium, and then rapidly diluting away the sucrose

Answer 23

Osmotic shock

Question 24

Solubilisation of the cell wall by surfactants, alkali or arganic solvents

Answer 24

chemical solubilisation

Question 25

Further separation and purification methods

Answer 25

• Liquid-liquid extraction
• Precipitation
• Ultrafiltration and microfiltration with membranes
• Chromatography
• Distillation
• Adsorption
• Gas stripping

Question 26

Solutes are separated based on their different solubilities in different liquids

Answer 26

Liquid liquid extraction

Question 27

Formation of a separable solid from a solution, by chemical reaction or by changing the temperature, pH or ionic strength to affect the solubility of the compound of interest

Answer 27

Precipitation

Question 28

The pores of ultra filtration membranes can remove particles 0.001-0.1 mu m from fluids. Membranes with a pore size of 0.1-10 mu perform microfiltration

Answer 28

Ultrafiltration and microfiltration with membranes

Question 29

Separate components in a mixture (mobile phase) based on their different rate of movement in a column with adsorbent materials (stationary phase)

Answer 29

Chromatography

Question 30

Utilises the differences of volatilities of components in a mixture. The basic principle is that by heating a mixtire, low boiling point components are concentrated in the vapour phase. By condensing this vapour. more concentrated less volatile compounds are obtained in liquid phase.

Answer 30

Distillation

Question 31

separation technique utilising a large surface area of adsorbent. compounds are adsorbed on the adsorbent depending on their physical and chemical properties.

Answer 31

Adsorption

Question 32

In general ____ particles tend to be adsorbed more due to low diffusivites

Answer 32

bigger

Question 33

In general bigger particles tend to be adsorbed ____ due to low diffusivites

Answer 33

more

Question 34

In general bigger particles tend to be adsorbed more due to ____ diffusivites

Answer 34

low

Question 35

Components with a ____ polarity to the adosrbent surface tend to be adsorbed more

Answer 35

similar

Question 37

Components with a similar polarity to the adosrbent surface tend to be adsorbed ____

Answer 37

less

Question 38

separation technique utilising the differences of volatilities among compounds. The separation efficiency is simply governed by Henry’s Law constant

Answer 38

gas stripping