Predictive modeling of CO₂ solubility in piperazine aqueous solutions using boosting algorithms for carbon capture...

Carbon dioxide (CO₂) is the main greenhouse gas that drives global warming, climate change, and other environmental issues. CO₂ absorption using amine solvents stands out as one of the most well-known industrial technologies of CO₂ capture. However, accurate prediction of CO₂ absorption in aqueous amine solutions under different operating conditions is crucial for designing an efficient amine scrubbing system in power plants. In this work, CO₂ solubility in aqueous piperazine (PZ) solutions was modeled using 517 experimental data points covering a temperature range of 298 to 373 K, PZ concentration of 0.1 to 6.2 mol/L (M), and CO₂ partial pressure of 0.03 to 7399 kPa. To this end, four robust machine learning algorithms, including gradient boosting with categorical features support (CatBoost), light gradient boosting machine (LightGBM), extreme gradient boosting (XGBoost), and adaptive boosting decision trees (AdaBoost-DT) were utilized. Among the developed models, the CatBoost model presented the highest accuracy with an overall determination coefficient (R²) of 0.9953 and an average absolute relative error of 2.36%. Sensitivity analysis revealed that CO₂ partial pressure had the greatest influence on CO₂ absorption in aqueous PZ solutions, followed by PZ concentration and temperature. Moreover, CO₂ partial pressure positively influenced CO₂ absorption in aqueous PZ solutions, while PZ concentration and temperature exhibited negative effects. Finally, the leverage technique indicated that both the experimental data bank used for modeling and the model's estimates were statistically acceptable and valid showing only 8 points (∼1.5% of total data) as possible suspected data.