Molecular investigation into the effect of carbon nanotubes interaction with CO2 in molecular separation using microporous polymeric membranes

Abstract

The use of nanofluids has been recently of great interest to separate acidic contaminants such as CO 2. The main objective of this research is to assess the influence of carbon nanotubes (CNTs) addition to distilled water on enhancing the CO 2 molecular separation through a porous membrane contactor (PMC). For this aim, a comprehensive model is developed based on non-wetted and counter-current operational modes to evaluate the principal mass and momentum transport equations in tube, membrane and shell compartments of PMC. Consequently, a CFD-based axisymmetrical simulation is implemented according to finite element technique (FET) to prognosticate the results. It is found from the results that the addition of 0.1 wt% carbon nanotubes (CNTs) particles to water significantly enhances the mass transfer and consequently the CO 2 molecular separation efficiency from 38 to 63.3%. This considerable enhancement can be justified due to the existence of two momentous phenomena including Brownian motion and Grazing effect, which enhance the mass transport of CO 2 molecules in the PMC. Moreover, the effect of CNTs concentration, some membrane's parameters such as number of hollow fibers and porosity and also some module's design parameters including module radius and length on the CO 2 separation performance are investigated in this paper as another highlight of the current work. Sustainable anthropogenic emission of greenhouse contaminants such as CO 2 and its pernicious influence on the atmosphere (i.e., global warming and acid rains) has been a global concern in developed and developing countries 1,2. Globally, it is estimated that several billion tons of CO 2 are being emitted into the atmosphere each year through burning fossil fuels 3. Human's industrial activities are verified to be the main reason for the increase in CO 2 amount and disturbance in atmospheric natural balance. Thus, it is vitally important to develop viable procedures for CO 2 sequestration 4. There are different processes for separation and removal of CO 2 from gas streams which need to be improved to obtain more efficient processes. Traditional techniques such as pressure swing adsorption, bubble columns, venture scrubbers, spray towers, and packed towers have recently been applied to eliminate CO 2 contaminants from gas streams. Apart from the superb advantages of conventional methods, such techniques suffer from disparate difficulties such as high capital/operating costs, risk of liquid overflow, frothing, entrainment, and channeling 5,6. The combination of gas absorption and membrane separation processes formed a modern technique which is known as the membrane gas separation (MGS) system. This technique is able to overcome the

Computational fluid dynamics comparison of prevalent liquid absorbents for the separation of SO2 acidic pollutant inside a membrane contactor

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Intensification of CO2 absorption using MDEA-based nanofluid in a hollow fibre membrane contactor

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