From a small glass tube liquid was streamed continuously at a velocity of 0.8-2.5m/sec to the absorption chamber filled with carbon dioxide gas of 1 atm. pressure. The diameter of the liquid column was 0.7-0.8mm, and the height was 1.5cm. Accordingly the time of contact of the gas and the liquid was 5/1000-2/100sec. When physical absorption takes place at this liquid surface such as the case of water and carbon dioxide gas, the distribution of carbon dioxide in the liquind will be expressed by the following diffusion equation:
the boundary condition:
the initial condition:
where c: concentration of CO
2 in the liquid, mol/c·c
c
0: saturated concentration of CO
2, mol/c·c
x: distance from the liquid surface, cm
t: time of contact, sec.
D: diffusion coefficient of CO
2 in the liquid, cm
2/sec.
From equations (1) (2) and (3), the mean absorption rate of CO
2 during the time of contact, zero to t sec, will be given:
This theoretical absorption rate were compared with the experimental values, and the satis-factory results were obtained at systems CO
2-water, H
2S-water and SO
2-water.
The oretical absorption rate, with the simultaneous chemical reaction, was obtained from the following equation.
the boundary condition:
the initial condition:
where A: concentration of the solute such as alkali, mol/l
k: reaction velocity coefficient, l/mol. sec
c
0': modified solubility of CO
2, mol/cc
From these equations the mean absorption rate of CO
2 gas during the time of contact, zero to t sec, will be given
where
The absorbing liquids used were aqueous solutions of KOH, NaOH, Na
2CO
3, K
2CO
3, and NH
4OH of several concentrations and at each temperature. Absorption data of CO
2 by these liquids gave very nearly close values with the above mentioned theoretical rate Nm. Reaction velocity coefficient k are
for KOH, k=8000l/mol sec at 25°C
for NaOH, k=3000l/mol sec at 20°C
for NH
4OH, k=150l/mol sec at 25°C
The modified saturated concentration c
0' means the effect of the solute for solubility and expressed by the following experimental quation:
where c
0 is the solubility for pure water and α is a constant for each solute.
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