Food Processing Unit Operations Multiple Choice Questions on “Membrane Separators”.
1. What is pervaporation?
a) Process to separate a volatile liquid from a non-volatile liquid
b) Process to mix a volatile liquid from a non-volatile liquid
c) Process to a evaporate a non-volatile liquid
d) Process to separate water molecules from a non-volatile liquid
Answer: a
Clarification: Pervaporation is a process to separate a volatile from a non-volatile liquid. The driving force is a vacuum on the gaseous side of the membrane. It is a tool for separation of liquid mixtures.
2. Which method is used for removing hardness?
a) Nanofiltration
b) Pervaporation
c) Electrodialysis
d) Reverse Osmosis
Answer: a
Clarification: Nano filtration is used for removing hardness. It removes organic compounds and selected salts at the lower pressure than RO system. It separates at the molecular level, removing all suspended solids and most dissolved solids.
3. Which method is used separation of azeotrope mixtures?
a) Nano filtration
b) Pervaporation
c) Electro dialysis
d) Reverse Osmosis
Answer: b
Clarification: Pervaporation is a process to separate a volatile from a non-volatile liquid. The driving force is a vacuum on the gaseous side of the membrane. It is a tool for separation of liquid mixtures.
4. Which of the following uses aromatic polyamide as membrane?
a) Gas separation
b) Pervaporation
c) Electro dialysis
d) Reverse Osmosis
Answer: d
Clarification: Reverse Osmosis uses aromatic polyamide as membrane where it is used in separation of salts and micro-solutes from solutions.
5. Which of the following statements about electro dialysis are correct?
Statement 1: Cation and anion exchange membrane is used.
Statement 2: The membrane is made of polymers & co-polymers.
a) True, False
b) True, True
c) False, True
d) False, False
Answer: a
Clarification: Cation and anion exchange membrane is used in electro dialysis where the membrane is made of sulfonated cross-linked polystyrene and is used in desalting the water.
6. What is other name for polymeric membrane?
a) Organic membrane
b) Inorganic membrane
c) Cation and anion membrane
d) Neutral charge membrane
Answer: a
Clarification: Polymeric membranes are also known as organic membranes. In order of the coarsest separation to the finest are microfiltration, ultrafiltration, nanofiltration and reverse osmosis.
7. What is flux rate for filters?
a) Ratio of flow to the membrane area
b) Ratio of concentration to the membrane area
c) Ratio of membrane area to the flow of the solution
d) Ratio of viscosity to the membrane area
Answer: a
Clarification: A membrane’s flux is defined as ratio of flow to the membrane area. It is used for calculating scalability. Ultrafiltration membranes are used in the purification of expensive biomolecules.
8. What is membrane processing?
a) Process that concentrates and separates without the use of heat
b) Process that removes dust without the use of heat
c) Process that remove water without the use of heat
d) Process that remove alcohol without the use of heat
Answer: b
Clarification: Membrane processing concentration and separation without the use of heat. Particles are separated on the basis of size of the molecules and shape with the help of pressure gradient and uses semi-permeable membranes.
9. What are cleaning techniques for the removal of membrane fouling?
a) Air flushing and chemical flushing
b) Alcohol flushing and chemical flushing
c) Air flushing and alcohol flushing
d) Air flushing
Answer: a
Clarification: There are various cleaning techniques to remove membrane fouling. These are forward flushing, backward flushing, air flushing and chemical cleaning.
10. Which of the following is used to remove yeast?
a) Nano filtration
b) Micro filtration
c) Electro dialysis
d) Reverse Osmosis
Answer: b
Clarification: Micro filtration is used for removing yeast, E- coli and mist droplets. Reverse Osmosis and nano filtration is used for removing inorganic compounds.