What occurs inside the deionizer during ion exchange?

During ion exchange in a deionizer, the primary process involves the replacement of unwanted ions in the water with hydrogen and hydroxyl ions. This process is essential for purifying water, particularly in hemodialysis, where the quality of water used is crucial for patient safety and treatment efficacy.

In the context of deionization, cation exchange resins are used to remove cations (positively charged ions) from the water and replace them with hydrogen ions. Conversely, anion exchange resins replace anions (negatively charged ions) with hydroxyl ions. The outcome is pure water that is free from various dissolved ionic contaminants, making it suitable for medical use.

The other choices, while they might suggest some aspect of water treatment or filtration, do not accurately describe the specific function and mechanism of ion exchange in deionizers.