(378p) Molecular Simulations of Carbon-Based Adsorbents/Membrane Materials for Sustainable Processes

According to the Brundtland Report: "Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs." Sustainable development implies the urgent needs to secure clean energy, food and water, known as the energy-food-water nexus. In this presentation, we will focus on some specific examples related to materials for CO₂ capture and for water treatment, as two specific examples to help in developing sustainable processes, either by avoiding the emission of greenhouse gases into the atmosphere or by providing quality water.

Commercial technologies used nowadays for carbon dioxide capture and water treatment face two major challenges: reduce capital costs and increase energy efficiency.[1,2] In the past few decades, porous materials have attracted considerable attention for separation purposes.[3] Common materials that have been extensively studied include zeolite, silica gel, metal-organic frameworks and carbon-based structures [4,5] Among them, carbonaceous materials have been well studied mainly due to their wide availability, low cost, high thermal stability and the possibility of synthesis from numerous carbons based naturally existing or spent materials.[6] Activated carbons, carbon nanotubes and membranes made of graphene or graphene-oxide structures are attractive and versatile materials. They are becoming vital for a wide range of industries, due to their unique structural and chemical properties. The ability to experimentally control adsorbent structural features at the molecular level, and recent progress made on modeling realistic carbon-structures and fluids force fields, enable building predictive models from molecular simulations for novel applications [7], [8]. Little is known about the effect of surface characteristics (e.g., pore size, surface area, density and species of surface groups, etc.) and the topological nature of the connected pore structures on the phase changes for the confined fluids [9]. In this regard, molecular simulations provide a direct route from the properties of interacting molecules to the thermodynamic properties of their bulk phases, and hence, they provide an alternative source of property data, while allow gaining insights into the physical phenomena of the membrane/adsorption process.

Therefore, this contribution is devoted to molecular simulation on carbon-based materials, from building the model to the application in separating fluids. The final goal is to showcase how molecular simulations can be used as a robust, complementary tool to understand and optimize fluid separation processes of industrial relevance. We will present and discuss results from Molecular Dynamics (MD) and Monte Carlo simulations to study separation of multi-component mixtures with virtual activated carbons and multilayer graphene oxide membranes, using realistic operating conditions, also considering the presence of minor components. Improved understanding of the effects of confinement on the equilibrium composition of mixtures, and on adsorption and diffusion rates on complex surfaces, may lead to significant improvements in the industrial processes. We will focus on two specific applications: separation of CO₂ from a flue gas and water desalination, comparing results with experimental data.

This work is part of a collaborative bilateral project between the Korea Advanced Institute of Science and Technology and Khalifa University. Financial support for this work has been provided by Khalifa University through projects CIRA-103, RC2-2018-0024 and RC2-2019-007.

References

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