Comprehensive investigation of isotherm, RSM, and ANN modeling of CO2 capture by multi-walled carbon nanotube

Zohreh Khoshraftar; Ahad Ghaemi; Alireza Hemmati

doi:10.1038/s41598-024-55836-6

Comprehensive investigation of isotherm, RSM, and ANN modeling of CO₂ capture by multi-walled carbon nanotube

Sci Rep. 2024 Mar 1;14(1):5130. doi: 10.1038/s41598-024-55836-6.

Authors

Zohreh Khoshraftar¹, Ahad Ghaemi², Alireza Hemmati³

Affiliations

¹ School of Chemical, Petroleum and Gas Engineering, Iran University of Science and Technology, P.O. Box 16765-163, Tehran, Iran. aghaemi@iust.ac.ir.
² School of Chemical, Petroleum and Gas Engineering, Iran University of Science and Technology, P.O. Box 16765-163, Tehran, Iran. zohrehkhoshraftar@gmail.com.
³ School of Chemical, Petroleum and Gas Engineering, Iran University of Science and Technology, P.O. Box 16765-163, Tehran, Iran.

Abstract

Chemical vapor deposition was used to produce multi-walled carbon nanotubes (MWCNTs), which were modified by Fe-Ni/AC catalysts to enhance CO₂ adsorption. In this study, a new realm of possibilities and potential advancements in CO₂ capture technology is unveiled through the unique combination of cutting-edge modeling techniques and utilization of the recently synthesized Fe-Ni/AC catalyst adsorbent. SEM, BET, and FTIR were used to analyze their structure and morphology. The surface area of MWCNT was found to be 240 m²/g, but after modification, it was reduced to 11 m²/g. The modified MWCNT showed increased adsorption capacity with higher pressure and lower temperature, due to the introduction of new adsorption sites and favorable interactions at lower temperatures. At 25 °C and 10 bar, it reached a maximum adsorption capacity of 424.08 mg/g. The optimal values of the pressure, time, and temperature parameters were achieved at 7 bar, 2646 S and 313 K. The Freundlich and Hill models had the highest correlation with the experimental data. The Second-Order and Fractional Order kinetic models fit the adsorption results well. The adsorption process was found to be exothermic and spontaneous. The modified MWCNT has the potential for efficient gas adsorption in fields like gas storage or separation. The regenerated M-MWCNT adsorbent demonstrated the ability to be reused multiple times for the CO₂ adsorption process, as evidenced by the study. In this study, a feed-forward MLP artificial neural network model was created using a back-propagation training approach to predict CO₂ adsorption. The most suitable and efficient MLP network structure, selected for optimization, consisted of two hidden layers with 25 and 10 neurons, respectively. This network was trained using the Levenberg-Marquardt backpropagation algorithm. An MLP artificial neural network model was created, with a minimum MSE performance of 0.0004247 and an R² value of 0.99904, indicating its accuracy. The experiment also utilized the blank spreadsheet design within the framework of response surface methodology to predict CO₂ adsorption. The proximity between the Predicted R² value of 0.8899 and the Adjusted R² value of 0.9016, with a difference of less than 0.2, indicates a high level of similarity. This suggests that the model is exceptionally reliable in its ability to predict future observations, highlighting its robustness.

Keywords: ANN; CO2 adsorption; CVD; Fe–Ni/AC catalyst; Multi-walled carbon nanotube; RSM.