Method and system for extracting a solute from a fluid using dense gas and a porous membrane

A method of extracting a flavor or fragrance from a fluid comprising the steps of:

• providing a porous membrane having opposite sides in a module under pressure with said membrane serving as a barrier interface between a fluid and dense CO.sub.2, said membrane is nonselective for said flavor or fragrance;
• passing said fluid and dense CO.sub.2 in opposite directions on said opposite sides of said membrane, where at least one of said fluid and dense CO.sub.2 contains a flavor or fragrance to be extracted and the other one of said fluid and dense CO.sub.2 serves as an extracting medium, said dense CO.sub.2 having a density of at least about 0.5 g/cc, said fluid and dense CO.sub.2 being essentially immiscible in one another so as to provide two phases;
• conducting said method wherein the pressure on both sides of said membrane in said module is essentially the same;
• and
• extracting said flavor or fragrance across said membrane as driven by a concentration gradient of said flavor or fragrance between said fluid and said dense CO.sub.2.

A system for extracting a solute from a fluid or a dense gas, comprising:

• a dense gas supply source;
• a fluid supply source;
• a pressurizable module containing a porous membrane with opposite sides, said module operatively connected to said dense gas and fluid supply sources for receiving from said sources a dense gas on one side of said membrane and a fluid on the opposite side of said membrane, said membrane being nonselective for said solute, said porous membrane serving as a barrier interface between said fluid and said dense gas, at least one of said fluid and dense gas containing a solute to be extracted by a concentration gradient of said solute between said fluid and said dense gas, and the other one of said fluid and dense gas serving as an extracting medium;
• and
• means for recovering said extracted solute.