The GATE Grind

GATE 2023 CH – Question 42

Mass Transfer · Membrane separations · 2 marks · Multiple choice

Which one of the following represents the CORRECT effects of concentration polarization in a reverse osmosis process?

  1. Reduced water flux and reduced solute rejection
  2. Increased water flux and increased solute rejection
  3. Reduced water flux and increased solute rejection
  4. Increased water flux and reduced solute rejection

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Correct answer: (A) Reduced water flux and reduced solute rejection

Explanation

Solute builds up on the membrane surface, so the effective osmotic pressure at the membrane rises and the driving force for the water falls: the water flux is reduced. The higher solute concentration at the surface also increases the solute passage, so the observed rejection is reduced.