Efficient Multi-Scale Simulation of Adsorption-Based Processes

Adsorption-based processes play a crucial role in reducing environmental pollution and eliminating harmful substances. Common filter media materials, like activated carbon, zeolites, and metal-organic frameworks, are used to effectively purify fluids and gases for applications ranging from water treatment to air purification. A way to measure and classify the quality of adsorption filter media is to look at breakthrough curves. A breakthrough curve shows the concentration of the adsorbate in the filtrate behind the filter media, and breakthrough occurs in the moment when adsorbate shows up in the filtrate.

In carbon capture, adsorption is vital to trap and store CO₂ emissions from industrial activities and power generation, preventing their release into the atmosphere. The CO₂ may be stored or used in processes like enhanced oil recovery or synthetic fuel production. However, determining breakthrough curves for a specific contaminant often requires time-consuming and costly experimental procedures.

In this context, the use of simulations allows to precisely control experimental parameters such as temperature, pressure, and surface properties to investigate their effects on adsorption behavior – gaining important insights into the microstructure to develop next-generation filter media.

Adsorption, a process whereby molecules or atoms adhere to the surface of a solid or liquid, plays a crucial role in various scientific and industrial applications [2]. This is fundamental to fields such as catalysis, environmental remediation, and material science but also in filtration applications. Furthermore, the significant contribution of anthropogenic CO₂ emissions to the acceleration of climate change has led to the conduction of numerous adsorption studies on carbon capture and sequestration [3,4,5]. It also contributes to the resolution of critical environmental challenges, including water purification and air pollution control.

Filter systems based on absorption technology play an increasing role in the aim to create cleaner environments. They are used in air purification systems to remove harmful gases, volatile organic compounds (VOCs), and particulate matter [6]. In water treatment, they help eliminate contaminants such as pesticides, pharmaceuticals, and heavy metals, ensuring safe drinking water [7,8].

In recent years, the use of packed beds for CO₂ capture has seen significant growth. GeoDict offers the capability to simulate the adsorption process within packed beds, making it highly valuable for carbon capture and storage applications. The resulting model is validated against published experimental results of Coker et al. (2014) for the adsorption of CO₂ on zeolite (Fig. 2).

The novel Adsorption feature of GeoDict uses the specific material properties of the adsorbate and adsorbent combined with the given parameters of the flow of the adsorbate through the adsorbent.

By considering the diffusivity of the adsorbents and, consequently, that of the medium, the precise location of the adsorbate molecules within the 3D voxel structure is determined and used for the computation of the adsorption process. In the next step, the adsorption GeoApp uses given Toth or Langmuir parameters to solve the corresponding equation and compute the mass transfer to the adsorbent surface over time on micro scale.

To simulate the movement of molecules, GeoDict uses an Euler-Lagrange tracer-based simulation that has been in use for several years. The GeoApp also gives the option to vary multiple key adsorption parameters such as temperature, adsorptive concentration, and adsorbent density to fit each individual filter configuration. Finally, GeoDict computes the initial breakthrough and determines the breakthrough curve of the filter under the individual set-up conditions.

[1] Coker, R., Knox, J., Gauto, H., & Gomez, C. (2014, July). Full System Modeling and Validation of the Carbon Dioxide Removal Assembly. In International Conference on Environmental Systems (ICES) 2014 (No. M14-3448).

[2] L. Zhou, Z.G. Qu, L. Chen, W.Q. Tao (2015), Lattice Boltzmann simulation of gas–solid adsorption processes at pore scale level, J. Comp. Physics, Vol 300, pp. 800-813, ISSN 0021-999, https://doi.org/10.1016/j.jcp.2015.08.014.

[3] H.S. Fabian Ramos, Ch. Baliga, A. Rajendran, P.A. Nikrityuk (2024) CFD-based model of adsorption columns: Validation, Chem. Eng. Science, Vol 285, 119606, ISSN 0009-2509, https://doi.org/10.1016/j.ces.2023.119606.

[4] R. Ben-Mansour, M.A. Habib, O.E. Bamidele, M. Basha, N.A.A. Qasem, A. Peedikakkal, T. Laoui, M. Ali (2014), Carbon capture by physical adsorption: Materials, experimental investigations and numerical modeling and simulations – A review, Applied Energy, Vol 161, pp 225-255, ISSN 0306-2619, https://doi.org/10.1016/j.apenergy.2015.10.011.

[5] S. Nanda, S.N. Reddy, S.K. Mitra, J.A. Kozinski (2016), The progressive routes for carbon capture and sequestration. Energy Sci Eng, Vol 4, pp 99-122. https://doi.org/10.1002/ese3.117

[6] K. Wang; J. Nie; H. Huang, F. He (2023) Literature Review on the Indoor Air VOCs Purification Performance of Metal–Organic Frameworks. Sustainability, Vol 15, 12923. https://doi.org/10.3390/su151712923

[7] J. Carratalá-Abril, M.A. Lillo-Ródenas, A. Linares-Solano, D. Cazorla-Amorós (2009), Activated Carbons for the Removal of Low-Concentration Gaseous Toluene at the Semipilot Scale, Industrial & Engineering Chemistry Research, Vol 48 (4), pp 2066-2075, DOI: 10.1021/ie800521s.

[8] A. Bonilla-Petriciolet, D.I. Mendoza-Castillo, H.E. Reynel-Ávila (2017). Adsorption Processes for Water Treatment and Purification, Springer Charm, Springer Int. Publishing AG, https://doi.org/10.1007/978-3-319-58136-1