Methods for recovering a polar solvent from a fluid stream contaminated with at least one polar impurity

A method of removing at least one polar impurity from at least one polar solvent, comprising:

• providing a fluid volume comprising at least one polar solvent and at least one polar impurity;
• contacting the fluid volume with an expanding gas at or near a critical point thereof to form two substantially immiscible phases;
• separating the two substantially immiscible phases;
• and
• reducing at least one of a temperature and a pressure of the expanding gas such that the polar solvent separates from the expanding gas.

A method of recovering a solvent from a fluid volume comprising methanol at least one polar impurity, comprising:

• exposing the fluid volume to carbon dioxide;
• increasing at least one of a temperature and a pressure to form a gas-expanded solvent comprising the methanol and the carbon dioxide and a polar liquid phase comprising the at least one fatty acid;
• removing the polar liquid phase from the gas-expanded solvent;
• and
• reducing the pressure in a range of from about 20 psi and about 30 psi to separate the solvent and the carbon dioxide from the gas expanding solvent.