Waste Water Engineering Multiple Choice Questions on “Ion Exchange Media Properties – 1”.
1. Amberjet 4400 has a total capacity of ________ in the chlorine form.
a) 0.5 eq/L
b) 1 eq/L
c) 1.5 eq/L
d) 2 eq/L
Answer: c
Clarification: Amberjet 4400 has a total capacity of about 1.5 eq/L in the Cl— form and 1.2 eq/L in the OH— form. The difference in the capacity is due to the swelling of the resin.
2. What is the percentage of swelling between the chlorine and the hydroxide forms?
a) 10%
b) 20%
c) 30%
d) 40%
Answer: c
Clarification: The difference in the total capacity of Amberjet 4400 is just due to resin swelling, it swells by up to 30 % between the Cl— and the OH— form.
3. The number of active groups in a resin sample fluctuates.
a) True
b) False
Answer: b
Clarification: The number of active groups in any of the resin is a constant. When the resin swells up, the density of the active groups decreases. Volume capacity is a measure of active group density.
4. ______ is the value of the sieve opening through which exactly 50 % of the resin volume passes.
a) Mean diameter
b) Effective size
c) Harmonic mean size
d) Uniformity coefficient
Answer: a
Clarification: The value for sieve opening is given by mean diameter. Exactly 50% of the resin volume passes through the mean diameter. It is abbreviated as “d50“.
5. Mean diameter is also called as ______
a) Actual diameter
b) Radius
c) Median diameter
d) Effective size
Answer: c
Clarification: Mean diameter is also called as median diameter. In the language of statistics, it is called the median diameter.
6. What is the percentage of resin volume considered for the mean diameter?
a) 20%
b) 30%
c) 40%
d) 50%
Answer: d
Clarification: The mean diameter is the value of the (theoretical) sieve opening through which exactly 50 % of the resin volume passes, i.e. that retains exactly 50 % of the resin sample.
7. What is the percentage of resin sample that is considered for effective size?
a) 10%
b) 20%
c) 30%
d) 40%
Answer: a
Clarification: The effective size is the value of the sieve opening through which exactly 10 % of the resin sample passes. It is abbreviated as “d10“.
8. Total capacity is the number of exchangeable bi-valent ions.
a) True
b) False
Answer: b
Clarification: Total capacity is the number of active groups i.e., the number of exchangeable monovalent ions. Both volume and dry weight capacity values must be reported.
9. ______ is the number of sites where exchange actually takes place during one cycle.
a) Total capacity
b) Operating capacity
c) Mean capacity
d) Resin capacity
Answer: b
Clarification: Operating capacity is the number of sites where exchange actually takes place during one cycle. Total capacities of new resins are measured for quality control.
10. Which of these is not a result of high moisture content?
a) Fast exchange
b) Good adsorption properties
c) Low total capacity
d) High total capacity
Answer: d
Clarification: The dry weight capacity indicates if a resin has been properly functionalised, irrespective of its water content. Whilst a high total capacity is generally desirable, not all exchange sites are used in a complete ion exchange cycle.
11. Which of these is not a result of low moisture content?
a) low total capacity
b) difficult to regenerate
c) no removal of big ions
d) tendency to fouling
Answer: a
Clarification: The low moisture content leads to the tendency of fouling, difficult to regenerate and there will be no removal of bigger ions.