Which of the following methods is used to increase oxygen concentration by selectively pulling it from the air?

The method that effectively increases oxygen concentration by selectively pulling it from the air is semipermeable membrane technology. This approach utilizes membrane filters that allow certain gases to pass through while blocking others. In the context of oxygen concentration, the semipermeable membrane is designed to favor oxygen molecules over nitrogen and other components in the air.

By applying pressure on one side of the membrane or using a concentration gradient, oxygen can be separated and enriched as it passes through the membrane, while nitrogen and other gases remain on the feed side. This process is advantageous in various applications, such as in medical settings where a higher concentration of oxygen is required for patients.

In contrast, molecular sieve technology relies on the physical adsorption of gas molecules within a solid structure designed to trap specific gases. Vacuum distillation and electrolysis are processes that either fractionate liquid gases based on boiling points or break down compounds into their elemental components, neither of which specifically enhances oxygen concentration from ambient air in the same selective manner as semipermeable membranes do.