This set of Air Pollution Control Multiple Choice Questions & Answers (MCQs) focuses on “Gaseous Pollutants – Control of Sulphur Dioxide Emissions – Set 3”.
1. Which of the following is not a disadvantage of using activated carbon to adsorb sulphur oxides from emission streams?
a) Attrition of adsorbent
b) Spontaneous combustion
c) Regeneration
d) High operating costs
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Explanation: The continuous use of the adsorbent makes it prone to attrition. Activated carbon is also prone to combustion under certain conditions. Its regeneration also involves the need for high temperature. Thus, leaving high operating costs as the odd one out.
2. What is the speciality of the BF process?
a) The absorbent is more selective
b) The adsorbent is resistant to ignition
c) Activated carbon is not used
d) Metal oxides are used
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Explanation: The BF process uses activated carbon as the adsorbent. The speciality of this process is that the adsorbent is modified to be resistant to ignition and size-reduction. Sulphur dioxide adsorbent is also enhanced.
3. What is unique about the Westvaco process?
a) Used alkalised alumina as adsorbent
b) Uses benzene as adsorbent
c) Uses fluidised bed
d) Uses packed bed
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Explanation: The Westvaco process uses the fluidised bed for the adsorption of sulphur dioxide. The adsorbent used for this process is activated carbon. The carbon acts as a catalyst in the conversion of sulphur dioxide to sulphur trioxide.
4. Which of the following is not used to absorb sulphur dioxide for wet scrubbing?
a) Using activated carbon
b) Using limestone
c) Using magnesium oxide
d) Using sodium sulphite
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Explanation: All the given options are used in different methods for the removal of sulphur dioxide from flue gases. However, activated carbon is an adsorbent used in the dry removal method. The wet scrubbing processes are absorption processes.
5. What is a significant advantage of using magnesium oxide for sulphur dioxide absorption?
a) Produces valuable materials
b) Low operating costs
c) High recovery
d) Low installation costs
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Explanation: When magnesium oxide is used to absorb sulphur dioxide, valuable products can be recovered. The sulphur dioxide recovered is then used to make sulphuric acid or sulphur that may become another income source.
6. Which process produces the second-highest sulphur dioxide emissions?
a) Combustion
b) Smelting
c) Oil refineries
d) Paper mills
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Explanation: Smelting is the second-highest emitter of sulphur dioxide. It is second only to combustion. Smelting of copper, lead, and zinc are examples of high contributors to sulphur dioxide production. It is because of the sulphur content in their ores.
7. Which of the following ore smelting processes is not the top three contributors to sulphur dioxide production?
a) Zinc
b) Lead
c) Titanium
d) Copper
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Explanation: Among the given options, titanium is the odd one out. Smelting operations are the second-largest contributors to sulphur dioxide production. The quantity is large enough to produce sulphuric acid or sulphur byproducts.
8. How much concentration of sulphur dioxide is produced from the contact process, producing sulphuric acid with 98% purity?
a) 500 ppm
b) 1000 ppm
c) 1500 ppm
d) 2000 ppm
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Explanation: The emissions of sulphur dioxide from sulphuric acid production using the contact process is very high. For a plant that uses a single absorber and produces acid at 98% purity, the emissions are about 2000 ppm. This is well above the governmental standards.
9. The sulphur content in crude oil is removed during the pre-treatment stage as it is economical.
a) True
b) False
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Explanation: Sulphur content removal from crude is uneconomical, and therefore, it is not adopted. The sulphurous compounds are complex, and removal is not feasible. Instead, the sulphur compounds are removed from the products.
10. How are complex sulphur compounds removed from heavy oil fractions?
a) Catalytic cracking
b) Washing with aqueous soda
c) Absorption with magnesium oxide
d) Adsorption with activated carbon
View Answer
Explanation: Catalytic cracking is used to remove complex compounds of sulphur from heavy fractions. Washing is used for removing simple sulphur compounds like hydrogen sulphide and mercaptans. The other listed procedures are used to remove sulphur dioxide from flue gases.
Sanfoundry Global Education & Learning Series – Air Pollution Control.
To practice all areas of Air Pollution Control, here is complete set of 1000+ Multiple Choice Questions and Answers.
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