Absorption of CO2 by Aqueous NaOH in Packed Column

The absorption of CO2 and the reaction between CO2 and NaOH in the aqueous solution are undertaken by the following steps  

Reaction (Rl) expresses the physical absorption of CO2 by water, accompanied with the evolution of heat of solution Reaction (R2) is known as the ratecontrolling step because reaction (R3) is a proton-transfer reaction and is very faster than reaction (R2). Thus, the absorption of CO2 by aqueous NaOH solution can be regarded as a gas absorption accompanied with second-order reaction (R2), and the overall reaction is represented by (R4). 

The second-order reaction rate constant 2 for C02-Na0H reaction was correlated by Pohorecki [27] as a function of temperature and ionic strengths 4 of aqueous electrolyte solutions as follows  

The model equations are given in Sect. 5.1 the determination of source terms in the modeling equations is similar to Sect. 5.1.2 except the physical parameters should be reevaluated as given in Ref. [9]. 

The object of simulation and verification is a randomly packed column reported by Tontiwachwuthikul et al. [24] the structure of this pilot-scale column has been described in Sect. 5.1.1.3 (2). Twelve sets of experimental data for the absorption of CO2 by NaOH were presented by the authors, among which six sets are taken to check the validity of the present simulated results. 

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