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How does a diaphragm cell separate chlorine from hydroxide ions?

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A labeled diagram of the chlorine element from the periodic table shows its atomic number 17, symbol Cl, electron configuration, and atomic weight range. The box is shaded green to indicate chlorine is a halogen, with icons for orthorhombic crystal structure, gas state at room temperature, and strong acidity. A key explains the icons and colors used. — chlorine Properties of chlorine.

In the chlor-alkali industry, the diaphragm cell separates chlorine gas from hydroxide ions by interposing a porous diaphragm between the electrodes.12

During the electrolysis of brine, chlorine is produced at the anode, while hydroxide ions and hydrogen gas are generated at the cathode. It is essential to keep these products apart because, if they were to mix, they would react with one another, consuming the chlorine. The porous wall acts as a physical barrier that prevents this contact while still allowing the necessary flow of ions to maintain the electrolytic process.12