In reference to surface chemistry, define dialysis.

Explanation

**Step-by-Step Solution:**

1. **Definition of Dialysis**: Dialysis is a purification process used to remove dissolved substances from a colloidal solution.

2. **Process Description**: In dialysis, the process involves the diffusion of small molecules or ions through a suitable membrane.

3. **Role of the Membrane**: The membrane used in dialysis allows only certain small molecules or ions to pass through while retaining the larger colloidal particles in the solution.

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