This study explored an intensive
carbon dioxide (CO2) absorption process with aqueous biphasic
absorbents containing
diethylethanolamine (DEEA) and diethylenetriamine (DETA) in a rotating
zigzag bed (RZB). The effects of the absorbent composition on the
phase separation behavior and CO2 absorption performance
were investigated. The dependence of the overall gas-phase volumetric
mass transfer coefficient (K
G
a) and CO2 absorption efficiency on operating conditions
with the DEEA + DETA solution was examined. Experimental results indicated
that over 97% absorbed CO2 was focused on the bottom layer
in the rich solution. The 4 mol/L DEEA + 1 mol/L DETA and 3.5 mol/L
DEEA + 1.5 mol/L DETA solutions had much less volume of the bottom
layer compared to absorbents with other compositions. Moreover, it
was found that the lean solution flow rate, rotational speed of RZB,
and temperature of lean solution had a positive influence on CO2 absorption. The K
G
a and CO2 absorption efficiency in the RZB with the 3.5
mol/L DEEA + 1.5 mol/L DETA solution reached 4.82 kmol/kPa m3 h and 98.7%, respectively, demonstrating an obvious advantage in
CO2 absorption performance compared to the 5 mol/L monoethanolamine
solution. An artificial neural network (ANN) model was established
to predict K
G
a and CO2 absorption efficiency. The predicted data and experimental
results were in good agreement with the deviations generally less
than 10% for K
G
a and
CO2 absorption efficiency. A comparison with a wetted-wall
column revealed that the RZB could achieve higher mass transfer efficiency.
In addition, the mechanism of phase separation in the DEEA + DETA
solution was analyzed. This study demonstrates that the DEEA + DETA
solution could be a viable absorbent for CO2 capture in
RZB.