To purify a water soluble polymer from water soluble salts via dialysis, what should be the concentration of the polymer solution to be used inside the dialysis bag. The polymer is sodium polystyrenesulfonate and the possible impurity is NaCl. Thank you in advance for the suggestions/recommendations.
Dear Ranjit De, the following document discusses among many other parameters the effect of the initial concentration. My Regards
https://doi.org/10.1021/acs.macromol.1c01241
Ranjit De
The movement of the polymer and ions through the membrane is determined by Fick's law. Diffusion flux density J, i.e. the amount of polymer, salt, transferred per minute through the membrane surface is determined by the equation:
J=-D ∂c/∂x,
where D is the coefficient of mutual diffusion and water, ∂c/∂x is the concentration gradient of the polymer, salt. The minus sign in the equation indicates that the diffusion of the polymer, salt occurs in the direction of decreasing the concentration of the distributed component, i.e. from vessel 1 to vessel 2.
Mutual diffusion of a polymer depends on its molar mass. The larger the molar mass, the lower will be the diffusion flux of the polymer through the membrane. The greater the salt concentration, the greater the salt concentration gradient.
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