Step 1: Understanding the Concept:
Membrane separation involves a semi-permeable barrier that allows certain components to pass through while retaining others. For any mass transfer to occur across this barrier, a "driving force" is required.
Step 2: Key Formula or Approach:
The flux ($J$) through a membrane is generally expressed as:
\[ J = L \cdot \Delta F \]
Where $L$ is the permeability and $\Delta F$ is the driving force (pressure, concentration, or electric potential gradient).
Step 3: Detailed Explanation:
Different membrane processes use different driving forces:
Reverse Osmosis / Microfiltration: Driven by pressure difference ($\Delta P$).
Dialysis / Pervaporation: Driven by concentration or chemical potential difference ($\Delta C$).
Electrodialysis: Driven by electrical potential difference.
Step 4: Final Answer:
Membrane processes are driven by concentration or pressure differences.