What does sorption means in pervaporation

[masuk]

I am little confused about sorption process in pervaporation. Is "Sorption= Adsorption + Absorption" ?

In dehydration process, if water molecules attach to the surface by adsorption then how they enter the polymer matrix or network (by absorption or solutbility effect)?

Also what is the physics behind swelling or the mechanism?

thanks for your time and help.

 

[ibmem]

The separation mechanism of Pervaporation is a solution-diffusion mechanism:

The transport can be divided into 3 steps:
1. - sorption into the membrane at the upstream (feed) side
2. - diffusion through the membrane
3. - desorption into a vapour phase at the downstream (permeate) side

The flux (permeation rate) is a function of solubility and diffusivity of the permeating component only. The driving forces are concentration differences (partial vapour pressure of water for the dehydration). The swelling of the membran will affect the diffusivity.

hope it helps,
ibmem

http://www.ibmem.com

 

[masuk]

Thanks ibmem.............however My question was what is the SORPTION process, physically?

SORPTION =

Also, why swelling[Is this due to Absorption of permeates?] occurs?

I know what is the after effects of swelling.

 

[ibmem]

again not answering "sorption=..." in one word but certainly of interest:

http://www.membrane.nl/serve/theses/matthias/chapter_02.pdf

§2.3 describing the sorption of simple gases in rubbery polymers and also

http://www.membrane.nl/serve/theses/matthias/chapter_04.pdf

page 63 introducing the models describing the sorption behaviour of glassy polymers.

 

[russiangoat]

Hi Masuk,

These definitions from Google...

A surface phenomenon which may be either absorption or adsorption, or a combination of the two; often used when the specific mechanism is not known.
instruct1.cit.cornell.edu/courses/tox607/tox607_glossary.htm

The mechanism of sorption is not specified. May include sorption by surface ie adsorption (chemisorption and physisorption), ionic exchange, surface precipitation (insoluble compounds formed near or at the surface), electrosorption (adsorption due to electrical potential), absorption (sorption by volume) etc.
adsorption.org/awm/ads/Glossary.htm

Hope this helps.