Separation procedure

Process for the separation of water from feed mixtures comprising water and formaldehyde which comprises contacting the aforesaid mixture against one side of a polyvinylchloride membrane and withdrawing, at the second side, a vaporous mixture having a higher concentration of water than the aforesaid feed mixture, with the mixture at the second side being maintained at a pressure which is greater than atmospheric, but is less than the pressure at the feed side of the membrane.

Process for the separation of water from feed mixtures comprising water and formaldehyde which comprises contacting the aforesaid mixture against one side of a polyvinylchloride membrane and withdrawing, at the second side, a vaporous mixture having a higher concentration of water than the aforesaid feed mixture, with the mixture at the said second side being maintained at a pressure less than atmospheric, but less than the pressure at the said feed side.

Process for the separation of water from feed mixtures comprising water and formaldehyde which comprises contacting the aforesaid mixture against one side of a polyvinylchloride membrane and withdrawing, at the second side, a vaporous mixture having a higher concentration of water than the aforesaid feed mixture, with the mixture at the second side being maintained at a pressure less than atmospheric, and the pressure at the said feed side being maintained at a pressure greater than atmospheric.