The present work evaluates and optimizes CO 2 absorption in a bubble column for the Pz-H 2 O−CO 2 system. We analyzed the impact of the different operating conditions on the hydrodynamic and mass-transfer performance. For the optimization of the process, variable conditions were used in the multivariate statistical method of response surface methodology. The central composite design is used to characterize the operating condition to fit the models by the least-squares method. The experimental data were fitted to quadratic equations using multiple regressions and analyzed using analysis of variance (ANOVA). An approved experiment was carried out to analyze the correctness of the optimization method, and a maximum CO 2 removal efficiency of 97.9%, an absorption rate of 3.12 g/min, an N CO 2 of 0.0164 mol/m 2 •s, and a CO 2 loading of 0.258 mol/mol were obtained under the optimized conditions. Our results suggest that Pz concentration, solution flow rate, CO 2 flow rate, and speed of stirrer were obtained to be 0.162 M, 0.502 l/h, 2.199 l/min, and 68.89 rpm, respectively, based on the optimal conditions. The p-value for all dependent variables was less than 0.05, and that points that all three models were remarkable. In addition, the experiment values acquired for the CO 2 capture were found to agree satisfactorily with the model values (R 2 = 0.944−0.999).

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In this work, absorption of CO 2 into a nanofluid of TiO 2 , ZnO, and ZrO 2 in piperazine solution was investigated experimentally in a continuous stirrer bubble column. The dosage range of nanofluids was 0.01 to 0.1 wt% in the experiments. The process parameters, such as nanoparticles type, solid loading, and stirrer speed, were varied to the hydrodynamics and absorption performance, including gas holdup, Sauter mean diameter, CO 2 loading, CO 2 removal efficiency, absorption rate, mass transfer flux, and overall mass transfer coefficients. The results showed that the nanoparticle mass fraction and range of stirrer speed have an optimum value for the above-mentioned performance. The optimum value of TiO 2 , ZnO, and ZrO 2 nanoparticles were 0.05, 0.1, and 0.05 wt%, respectively. The maximum absorption rate of TiO 2 , ZnO, and ZrO 2 compared with that of pure Pz solution was 14.7% (0.05 wt%), 16.6% (0.1 wt%), and 3.7% (0.05 wt%), respectively. Also, with an increase of the stirring speed, the absorption performance increased first up to 200 rpm and then it starts to decrease after 200 rpm. The hydrodynamics studies indicate that the gas hold-ups increase and the Sauter mean diameter decreases in the bubble column with increasing nanoparticles to the base fluid.

In this research, the chemical absorption rate and solubility of carbon dioxide into DEA aqueous solutions were investigated in a stirrer bubble column.