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- Fager, Cecilia, 1990, et al.
(författare)
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Correlating 3D porous structure in polymer films with mass transport properties using FIB-SEM tomography
- 2021
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Ingår i: Chemical Engineering Science: X. - : Elsevier BV. - 2590-1400. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Porous polymer coatings are used to control drug release from pharmaceutical products. The coating covers a drug core and depending on the porous structure, different drug release rates are obtained. This work presents mass transport simulations performed on porous ethyl cellulose films with different porosities. The simulations were performed on high spatial resolution 3D data obtained using a focused ion beam scanning electron microscope. The effective diffusion coefficient of water was determined using a diffusion chamber. Lattice Boltzmann simulations were used to simulate water diffusion in the 3D data. The simulated coefficient was in good agreement with the measured coefficient. From the results it was concluded that the tortuosity and constrictivity of the porous network increase with decreasing amount of added hydroxypropyl cellulose, resulting in a sharp decrease in effective diffusion. This work shows that high spatial resolution 3D data is necessary, and that 2D data is insufficient, in order to predict diffusion through the porous structure with high accuracy.
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| 2. |
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| 3. |
- Swapnasrita, Sangita, et al.
(författare)
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Unravelling CO oxidation reaction kinetics on single Pd nanoparticles in nanoconfinement using a nanofluidic reactor and DSMC simulations
- 2021
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Ingår i: Chemical Engineering Science: X. - : Elsevier BV. - 2590-1400. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Steady state catalytic oxidation of CO in nanofluidic channels decorated with Pd nano particles was studied using the Direct Simulation Monte Carlo (DSMC) method. Diffusion, collision, adsorption, desorption and reaction processes are simulated simultaneously. The influence of various adsorption (sticking coefficient, saturation coverage), desorption (activation energy, pre-exponential factor) and reaction (activation barrier) parameters on the final CO2 turnover are determined. These effects are considered to tune DSMC surface reaction model with respect to the experimental results. With DSMC, it was possible to get insights on reactivity of the individual Pd particles and the resulting varying reaction conditions along the channel due to local conversion effects. From the local coverages, the limit of CO:O2 inlet ratio to get maximum CO2 turnover without poisoning the catalyst with CO were determined. The approach paves the way to accurately represent micro- and nanoscale flows at the same system size as that of experiments.
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