A study of gas diffusion characteristics on a micro porous composite silica ceramic membrane

Nwogu, Ngozi Claribelle; Kajama, Mohammed Nasir; Gobina, Edward

doi:10.1016/j.compstruct.2015.07.121

Cited by 7 publications

(4 citation statements)

References 19 publications

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“…The permeation flux, J , of non-adsorbable gases through a microporous membrane can be described by the well-known Equation (8) [5], where D is the gas diffusion coefficient, ε is the porosity, and τ is the tortuosity. J=DRTΔpLετ…”

Section: Resultsmentioning

confidence: 99%

“…Silica network tuning technology has been developed to improve hydrogen permeability [2,3]. Knudsen diffusion, viscous flow [4], and their combined mechanisms [5] have been well investigated for relatively larger pores from several tens of nanometers to microfiltration (MF) regions. Gas transport mechanisms for subnano-scale pores have been theoretically studied, which has involved pores that range in sizes greater than 0.4 nm where smaller molecules such hydrogen can be separated from larger molecules such as methane, light hydrocarbons, SF 6 , or organic hydrides [6,7,8,9].…”

Section: Introductionmentioning

confidence: 99%

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Molecular Dynamics Simulation Study of Solid Vibration Permeation in Microporous Amorphous Silica Network Voids

et al. 2019

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Microporous silica membranes have silica polymer network voids smaller than 3 Å where only small gas molecules such as helium (2.6 Å) and hydrogen (2.89 Å) can be transported. These silica membranes are highly expected to be available for H2 separation. In order to examine gas permeation mechanisms in the silica polymer network voids, factors such as membrane porous structures, gas diffusivity, and gas permeability were studied via membrane permeation molecular dynamics simulation. The thermal motions of silica membrane constituent atoms were examined according to classic harmonic oscillation potential using a suitable amorphous silica structure and non-equilibrium molecular dynamics (NEMD) simulations of gas permeation. The dynamic model successfully simulated the gas permeation characteristics in an amorphous silica membrane with a suitable Hooke’s potential parameter. The introduction of the oscillative thermal motion of the membrane atoms enhanced gas diffusivity. Helium and hydrogen diffusivity and permeability were analyzed using gas translation (GT) and solid vibration (SV) models. The diffusion distance of gas molecules between adsorption sites was around 5.5–7 Å. The solid-type vibration frequencies of gas molecules in the site were on the order of 1013 and were reasonably smaller for heavier helium than for hydrogen. Both the GT and SV models could explain the temperature dependency of helium and hydrogen gas diffusivities, but the SV model provided a more realistic geometrical representation of the silica membrane. The SV model also successfully explained gas permeability in an actual silica membrane as well as the virtual amorphous silica membrane.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Simulation Study of Solid Vibration Permeation in Microporous Amorphous Silica Network Voids

et al. 2019

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“…2) Ceramic membrane technology is widely applied in water/wastewater purification and as pretreatment in the nanofiltration/reverse osmosis process. 3) Alumina (Al 2 O 3 ), 4) zirconia (ZrO 2 ), 5) titania (TiO 2 ), 6) silica (SiO 2 ), 7) carbon, 8) and zeolite 9) have been mainly investigated as materials for ceramic membranes. The development of membrane manufacturing technology using low-cost ceramic raw materials has also been investigated in an effort to reduce the cost of raw materials and reduce the temperature of the sintering processes (>1,300°C).…”

Section: Introductionmentioning

confidence: 99%

Effect of SiO<sub>2</sub> coating on alumina microfiltration membranes on flux performance in membrane fouling process

Lee

Song

et al. 2019

J. Ceram. Soc. Japan

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Inorganic surface modification was performed using a SiO 2 solgel technique to mitigate the fouling of alumina microfiltration membranes. A positively charged alumina membrane was coated with SiO 2 to generate a negative charge, and as a result, electrostatic repulsion prevented the serious adsorption (or deposition) of model foulants on the membrane. Upon the formation of the SiO 2 layer, small changes in the surface morphology, pore size, and surface roughness were detected. In particular, as the pore size decreased, the pure water permeability gradually decreased. When the membrane fouling was accelerated with model foulants, the highest normalized flux level and the lowest flux decline ratio (%) were observed in the smallest SiO 2 -coated microfiltration membrane (0.1 M SiO 2 ). In summary, the SiO 2 coating contributed to the optimization of the antifouling properties of the ceramic membranes, although the pore size was reduced.

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“…3) Regarding the membrane materials, many studies have focused on new types of inorganic membranes using alumina (Al 2 O 3 ), 4) zirconia (ZrO 2 ), 5) titania (TiO 2 ), 6) and silica (SiO 2 ), 7) as well as carbon 8) and zeolite. 9) Cost-effective raw materials have been also developed to offset the use of expensive raw materials and high-temperature sintering processes (>1300°C).…”

Section: Introductionmentioning

confidence: 99%

Enhanced fouling resistance of organosilane-grafted ceramic microfiltration membranes for water treatment

Lee

Song

et al. 2017

J. Ceram. Soc. Japan

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A facile surface modification technique for imposing antifouling properties on ceramic microfiltration (MF) membranes was developed based on the chemical conjugation of organosilane molecules on ceramics. The ceramic MF membranes (pore size: approximately 0.1¯m) were fabricated using conventional dip coating in an alumina slurry with nano-sized particles. The membranes were subsequently subjected to organosilane grafting with different molar concentrations (25, 50, and 100 mM). The physicochemical analysis of the organosilane-grafted membranes revealed a small decrease in pore size/roughness, which resulted from the new formation of organosilane multilayers (i.e., pore-filling effect). The pure water permeability was also diminished to some extent while exhibiting minimal influence on the permeation flux. Because of the electrostatic repulsion force between the surface-modified MF membranes and the model foulants, serious foulant adsorption followed by flux decline was significantly alleviated. In particular, the lowest organosilane concentration (25 mM) showed the greatest flux performance. This was mostly attributed to the reduced effect of pore-size restriction and electrostatic repulsion forces. We therefore achieved the optimum organosilane-grafting conditions for ceramic MF membranes, which not only minimized the alteration of surface morphology/pore size and hydraulic permeability but also remarkably improved the antifouling properties.

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A study of gas diffusion characteristics on a micro porous composite silica ceramic membrane

Cited by 7 publications

References 19 publications

Molecular Dynamics Simulation Study of Solid Vibration Permeation in Microporous Amorphous Silica Network Voids

Molecular Dynamics Simulation Study of Solid Vibration Permeation in Microporous Amorphous Silica Network Voids

Effect of SiO<sub>2</sub> coating on alumina microfiltration membranes on flux performance in membrane fouling process

Enhanced fouling resistance of organosilane-grafted ceramic microfiltration membranes for water treatment

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