Question

You have discovered a fabric which when it contains an adsorbent such as activated carbon can
be used to make an overcoat that can protect you from toxic chemicals. In a test of such fabric, a
gas stream containing 8.0 mg/L of carbon tetrachloride (CCl4) was passed through 7.71 g sample
of the fabric at a rate of 1 L/min and the concentration of CCl4 in the gas leaving the fabric was
monitored. The run was continued for 15 min with no CCl4 being detected, after which the CCl4
concentration began to rise. a). How much CCl4 was fed to the system during the first 15 min?
How much was adsorbed? b). Sketch the concentration of CCl4 in the exit as a function time
from t=0 to 30 min. c). Assuming a linear relationship between amount of CCl4 adsorbed and
mass of fabric, what fabric mass would be required if the feed concentration is 5 mg/L, the feed
rate 1.5 L/min and it is desired that no CCl4 leave the fabric earlier than 30 min?

Answer 1

SOLUTION:

(a)

1 min ---------- 1000 mL CCl4

15 min ------ x = 15000 mL CCl4

1 mL ----------- 8.0 mg CCl4

15000 mL ---- x = 120000 mg CCl4

7.71 g adsorbent -------- 120000 mg CCl4

1 g adsorbent ------------- x = 15564.20 mg CCl4/g adsorbent

(b)

(c)

1 min ------------ 1400 mL

30 min ---------- x = 42000 mL

1 mL ------------ 5 mg CCl4

42000 mL ----- x = 210000 mg CCl4

15564.20mg CCl4 ----------- 1 g adsorbent

210000 mg CCl4 ----------------- x = 13.49 g adsorbent

1 g adsorbent ------------- x = 15564.20 mg CCl4/g adsorbent