Membrane contactors
And
Study about methods of reduce their wettability problems
Researcher:
Supervisor:
The term "membrane contactor" is used to identify membrane systems that are employed to "keep in contact" two phases, without dispersion of one phase in the other.
What are the MEMBRANE CONTACTORs?
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Membrane contactors
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Membrane contactors do not offer
any selectivity for a particular species.
Membrane contactors simply act as a barrier between the phases involved, by allowing their contact in correspondence of a well defined interfacial area.
Key points about membrane contactors
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Being the two phases separate by the membrane, there is no mix of them and dispersion phenomena do not occur.
The species are transferred from one phase to the other by only diffusion.
The membranes are usually micro porous and symmetric and can be both hydrophobic and hydrophilic.
Key points about membrane contactors
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Membrane contactors how they work?
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Micro porous membrane
Contact line
Membranes used in membrane contactors
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Hydrophobic membrane:
In the case of hydrophobic materials, the membrane can be wetted by non polar phases or filled by gas, while the aqueous/polar phase can not penetrate into the pores.
Membranes used in membrane contactors
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Hydrophilic membranes:
When hydrophilic materials are used, the aqueous/polar phase wets the membrane pores while the non polar/gas phase is blocked at the pore mouth..
Hydrophilic-Hydrophobic membrane:
Two liquid phases can be in contact also by means of a composite hydrophobic-hydrophilic membrane
Composite membranes used in membrane contactors
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Dense-Microporous membrane: A non-porous thin layer coated on the microporous surface that prevents the penetration of the aqueous/polar phase. The non-porous thin layer allows also to enlarge the range of the operating pressures, but, in order to do not increase too much the resistance to the mass transport, it has to be highly permeable for the transferred species.
Composite membranes used in membrane contactors
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Applications of membrane contactors
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Membrane contactors systems
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Well defined and constant interfacial area
High interfacial area in small volumes
Reduced size and weight
No dispersion between phases
No need of phase separation downstream
No flooding, loading, foaming
Wide range of operating flow-rates
Azeotropic mixtures can be easier treated than in conventional units
Flexible, easy in scale-up, control and automatization
And …
Positive aspects of membrane contactors
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Further resistance offered by the membrane
Membrane limited life-time
Membrane fouling
Pre-treatments before the process
Limited operating pressures, based on the breakthrough value
Channeling and bypassing of fluids
Negative aspects of membrane contactors
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Membrane wetting
Phases involved in the process
Membrane type
Membrane Morphology & structure
Operating parameters
Factors affecting the performance of membrane contactors
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Modification of the membrane structure
Use of dense-microporous composite membranes
Modification of the membrane surface
Determine the optimal velocity of phases
Use of additives in liquid phase for increasing surface tension (hydrophobic membranes)
And …
Methods of reduce wettability problems
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Pore size control
Nano composites
To increase the hydrophobicity of the PP membrane , methyl functional group with sol-gel method was added to the polypropylene membrane
Resault:
Modification of membrane surface
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Pure PP membrane
Contact angle=102 degree
Pure PP membrane
Contact angle=157.5 degree
After modification
The effect of gas and liquid velocity in the process of removing carbon dioxide frome methane by hollow fiber membrane contactors
Determine the optimal velocity of phases
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Drioli and Criscuoli and Cursio , Membrane contactors, fundimentals, applications and potentialities, 1st edition
Anil K.Pabby , Syed S.H. Rizvi and Ana Maria Sastre , Handbook of Membrane Separations_ Chemical, Pharmaceutical, Food, and Biotechnological Applications ,CRC Press(2008)
Amirabedi Parya, Yegani Reza and Azimian Masod , Fabrication and characterization of superhydrophobic PP hollow fiber membranes for CO2 absorption in membrane contactors , The 12th international conference on membrane science and technology, Tehran 2015
شهابی ، محبوبه . جداسازی دی اکسید کربن از گاز متان بعنوان مدل گاز طبیعی با استفاده از تماس دهنده های غشایی الیاف نازک توخالی- پایان نامه ی کارشناسی ارشد تبریز: دانشگاه صنعتی سهند
قنواتیان، محمود و قنواتیان، محمد . انتقال جرم در تقطیر غشایی اسمزی ، اولین کنفرانس ملی تکنولوژی های نو در شیمی و مهندسی شیمی . تهران 2013
اکبری، علی و یگانی، رضا. مطالعه ی پارامترهای موثر بر عملکرد تماس دهنده های غشایی الیاف تو خالی برای جداساز دی اکسید کربن از گاز طبیعی – فرآیند نو- پاییز 91 . شماره ی 39
Refrences
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