Performance optimization of CO2 mineralization: A comparative study of caustic soda and soda ash as pH-risers under high-pressure reactor
DOI:
https://doi.org/10.31699/IJCPE.2026.2.6Keywords:
CO2; caustic soda; soda ash; mineralization; pH riserAbstract
Aqueous mineral carbonation is one of the most important methods of permanent CO2 sequestration in Carbon Capture, Utilization, and Storage (CCUS). This is carried out using alkaline pH-risers to neutralize the acidity of carbonic acid (H2CO3) to cause a change in the chemical balance to carbonate ions (CO32-). This paper assesses the different sources of alkalinity with special reference to the performance of caustic soda (NaOH) and soda ash (Na2CO3) under industrial circumstances. It has been shown in experiments that caustic soda is the most effective reagent in quick mineralization. It causes a sudden early increase in pH (about 2.0 to 2.5 units per gram) and maintains a very alkaline pH (pH >12), which are critical to the efficiency of CO2 absorption (95.52 %). Moreover, NaOH has a remarkable stability at high pressure and the rate of change in pH (0.3 ΔpH/gm) does not change at the pressure of 65 bars. Soda ash on the other hand is a moderate buffer that reaches its highest pH at approximately 11.6, with an easily lower absorption efficiency of 72.45%. Soda ash performance improves as the pressure is increased to conserve pressure up to 65 bar, thus making it difficult to use it in high-pressure systems. Optimization of the industry shows that the efficiency is maximized within the temperature regime between 40°C and 60°C, where the accelerated reaction rates resulting decrease in the gas solubility. Furthermore, the best mass transfer rate is 300 rpm that minimizes the CO2 bubble size. Though the stoichiometric superiority of caustic soda 1.0 kg does the work of 1.3 kg of soda ash, it presents severe challenges to operation because of its expensive nature, energy-consuming nature, and corrosivity. Soda ash is also still a feasible option in large scale sequestration due to its 30-40 % lower cost and the fact that it is dry and can be transported easily. Finally, a tradeoff between chemical reactivity, mechanical stability, and scalability of the economic side should be made even in the choice of a pH riser.
Received on 12/02/2026
Received in Revised Form on 15/03/2026
Accepted on 16/03/2026
Published on 30/06/2026
References
[1] R.-Y. Chan, Y.-Z. Zeng, C. C. Hou, H.-C. Kuo, and H.-W. Huang, “Experimental study of carbon dioxide capture and mineral carbonation using sodium hydroxide solution,” Journal of Ecological Engineering, vol. 26, no. 1, pp. 30–45, 2025. https://doi.org/10.12911/22998993/195214
[2] F. Wang and D. Dreisinger, “Status of CO2 mineralization and its utilization prospects,” Minerals and Mineral Materials, vol. 1, p. 4, 2022. https://doi.org/10.20517/mmm.2022.02
[3] V. Romanov, Y. Soong, C. Carney, G. E. Rush, B. Nielsen, and W. O’Connor, “Mineralization of Carbon Dioxide: A Literature Review,” ChemBioEng Reviews, vol. 2, no. 4, pp. 231–256, May 2015. https://doi.org/10.1002/cben.201500002
[4] Y. Zhang, S. Long, M. T. Duret, L. A. Bullock, P. Lam, and A. Yang, “Modeling and Feasibility Assessment of Mineral Carbonation Based on Biological pH Swing for Atmospheric CO2 Removal,” ACS Sustainable Chemistry & Engineering, vol. 13, no. 19, pp. 6972–6981, May 2025. https://doi.org/10.1021/acssuschemeng.4c10708
[5] A. Sanna, M. Uibu, G. Caramanna, R. Kuusik, and M. M. Maroto-Valer, “A review of mineral carbonation technologies to sequester CO2,” Chemical Society Reviews, vol. 43, no. 23, pp. 8049–8080, Nov. 2014. https://doi.org/10.1039/C4CS00035H
[6] Q. Wehrung, D. Bernasconi , E. Destefanis, C. Caviglia, A. Colli, F. Michel, A. Pavese and L. Pastero, “Impact of Operational Parameters on the CO2 Absorption Rate and Uptake in MgO Aqueous Carbonation—A Comparison with Ca(OH)2,” Minerals, vol. 15, no. 11, p. 1205, Nov. 2025. https://doi.org/10.3390/min15111205
[7] F. Zeman, “Energy and Material Balance of CO2 Capture from Ambient Air,” Environmental Science & Technology, vol. 41, no. 21, pp. 7558–7563, Nov. 2007. https://doi.org/10.1021/es070874m
[8] J. M. Matter, M. Stute, S.Ó. Snæbjörnsdottir, E. H. Oelkers, S.R. Gislason, E. S. Aradottir, B. Sigfusson, I. Gunnarsson, H. Sigurdardottir, E. Gunnlaugsson, G. Axelsson, H. A. Alfredsson, D. W-Boenisch, K. Mesfin, D. F. de la Reguera Taya, J. Hall, K. Dideriksen, and W. S. Broecker “Rapid carbon mineralization for permanent disposal of anthropogenic carbon dioxide emissions,” Science, vol. 352, no. 6291, pp. 1312–1314, Jun. 2016. https://doi.org/10.1126/science.aad8132
[9] S.-Y. Pan, E. E. Chang, and P.-C. Chiang, “CO2 Capture by Accelerated Carbonation of Alkaline Wastes: A Review on Its Principles and Applications,” Aerosol and Air Quality Research, vol. 12, no. 5, pp. 770–791, 2012. https://doi.org/10.4209/aaqr.2012.06.0149
[10] W. J. J. Huijgen, G. J. Witkamp, and R. N. J. Comans, “Mineral CO2 Sequestration by Steel Slag Carbonation,” Environmental Science & Technology, vol. 39, no. 24, pp. 9676–9682, Nov. 2005. https://doi.org/10.1021/es050795f
[11] N. Nuryoto, H. Heriyanto, R. Rahmayetty, R. Z. Nawwari, S. F. Harrisma, and R. N. T. Bagaskara, “Strategy for Maintaining Environmental Stability: Synthesis CO2 Emission Gases into Sodium Carbonate,” Environmental Research, Engineering and Management, vol. 81, no. 4, pp. 120–130, Dec. 2025. https://doi.org/10.5755/j01.erem.81.4.39917
[12] A.-H. A. Park and L.-S. Fan, “CO2 mineral sequestration: physically activated dissolution of serpentine and pH swing process,” Chemical Engineering Science, vol. 59, no. 22–23, pp. 5241–5247, Nov. 2004. https://doi.org/10.1016/j.ces.2004.09.008
[13] M. F. Gutierrez, H. Lorenz, and P. Schulze, “Carbon-Negative Production of Soda Ash: Process Development and Feasibility Evaluation,” Industrial & Engineering Chemistry Research, vol. 64, no. 23, pp. 11474–11496, Jun. 2025. https://doi.org/10.1021/acs.iecr.5c00483
[14] W. Simanjuntak, S. Sembiring, W. A. Zakaria, and K. D. Pandiangan, “The Use of Carbon Dioxide Released from Coconut Shell Combustion to Produce Na2CO3,” Makara Journal of Science, vol. 18, no. 3, Sep. 2014. https://doi.org/10.7454/mss.v18i3.3717
[15] S. I. Ruiz, R. Janssens, and P. Luis, “Mass and heat transfer study in osmotic membrane distillation-crystallization for CO2 valorization as sodium carbonate,” Separation and Purification Technology, vol. 176, pp. 173–183, Apr. 2017. https://doi.org/10.1016/j.seppur.2016.12.010
[16] S. K. Guchhait, K. K. Yadav, Sunaina, S. khatana, R. K. Saini, Pranay, U. K. Arora, R. Satyakam, R. Bajaj, M. Jha, “Conversion of gaseous effluents of power plant to sodium carbonate: A value-added material for powder detergent,” Cleaner Waste Systems, vol. 3, p. 100042, Dec. 2022. https://doi.org/10.1016/j.clwas.2022.100042
[17] S. Kuliyev, Y. E. Tas, and M. S. Cogenli, “Control of CO2 absorption by NaOH solution using pH, conductivity and titration measurements,” Chemical Problems, vol. 21, no. 2, pp. 123–131, 2023.
[18] S. Ghaffari, S.-M. Andreas, M. F. Gutierrez, H. Lorenz, and P. Schulze, “Sodium Hydroxide-Based CO2 Direct Air Capture for Soda Ash Production Fundamentals for Process Engineering,” Industrial & Engineering Chemistry Research, vol. 62, no. 19, pp. 7566–7579, May 2023. https://doi.org/10.1021/acs.iecr.3c00357
[19] A. A. Dalia and I. E. Mohamed, “Optimization using central composite design for continuous absorption of CO2 gas with green sodium silicate in a packed bed column,” Heliyon, vol. 10, no. 12, p. e32953, Jun. 2024. https://doi.org/10.1016/j.heliyon.2024.e32953
[20] M. H. Alyousef, S. Alshammari, and A. Al-Yaseri, “Synergy of CO2 Mineralization in Produced Water with Enhanced Oil Recovery: An Experimental Study,” Fuel, vol. 382, p. 133694, Feb. 2025. https://doi.org/10.1016/j.fuel.2024.133694
[21] Q. Bennett, K. D. Wolfe, A. Kasick, R. Shaffer, E. Nyamekye, O. M-Cabrera, M. Thackery, S. Oza and J. Trembly, “Semi‐Continuous Ex Situ Carbon Dioxide Mineralization in Produced Water for Calcite Production,” Energy Science & Engineering, vol. 13, no. 7, pp. 3678–3687, Jul. 2025. https://doi.org/10.1002/ese3.70125
[22] S. Alshammari, H. Saleem, D. K. Cha, and S. Ayirala, “CO2 Mineralization in Produced Water: Transforming Waste Brines into a Carbon Sink,” in Middle East Oil, Gas and Geosciences Show (MEOS GEO), SPE, Sep. 2025. https://doi.org/10.2118/227029-MS
[23] B. Zhu, S. Wilson, N. Zeyen, M.J.Raudsepp, A.Zolfaghari, B. Wang, B. J. Roston, K.N.Snihur, K.V. Gunten, A. L. Harrison and D.S. Alessi, “Unlocking the potential of hydraulic fracturing flowback and produced water for CO2 removal via mineral carbonation,” Applied Geochemistry, vol. 142, Jul. 2022. https://doi.org/10.1016/j.apgeochem.2022.105345
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