Permeation Characteristics of the Thin Film of Plamapolymerized Pyridine for Water-Soluble Solutes

Abstract

Permeation characteristics of plasma-polymerized pyridine thin films for water-soluble solutes have been investigated. The rate of salt rejection in reverse osmosis tests was found to be independent of the concentration of the salt solutions while marked decline in water flux was observed with increasing concentration, when the applied pressure was kept constant. The decline of the water flux was attributed mainly to raised osmotic pressure of the sample solution but also to concentration polarization in the vicinity of the filter surface even under the efficient stirring of the salt solution. The polymer film also performed the function of ultrafiltration of organic solutes having various molecular sizes in aqueous media. An approximately 10 Å pore size was derived from the exclusion limit. For smaller organic molecules than the exclusion limit, reverse osmosis separation was again effective if the molecules were ionized in acidic or alkaline media. Concentration of solutions either by reverse osmosis or ultrafiltration using a small filter area was as efficient as a laboratory rotary evaporator.