Process for the recovery of surfactants

A method for recovering and reusing a surfactant,

• the method comprising the steps of, in an aqueous solution system of liquid, subcritical or supercritical carbon dioxide and an electrolyte, carrying out in the presence of at least one type of surfactant an electrochemical reaction, dehydrating the solution after the reaction, and recovering and reusing surfactant-containing carbon dioxide.

A method for recovering a surfactant,

• the method comprising the steps of washing, drying, or dehydrating a precision machinery component or a semiconductor wafer using a water-carbon dioxide system comprising at least one type of surfactant, water, and liquid, subcritical or supercritical carbon dioxide, and bringing the water-carbon dioxide system into contact with a dehydrating agent.

A method comprising the steps of installing a device for selectively removing a removal target in a circulation line in which circulated is a mixed system comprising carbon dioxide, a carbon dioxide-compatible surfactant and/or a cosolvent, and a removal target;

• circulating the mixed system;
• and selectively removing the removal target that has been incorporated into the surfactant and/or cosolvent.