Question

Membrane filters remove particles mainly by _______

• A. Size exclusion
• B. Chemical reaction
• C. Adsorption
• D. Sedimentation

Hint:

Membrane filters mainly work by size exclusion: particles larger than the pore size are retained, while smaller particles pass through.

Answer 1

The Correct Option is A

Concept:
Membrane filtration is a filtration technique in which particles are separated from fluids by passing the fluid through a membrane with very small pores.

Step 1: Principle of membrane filtration.
The pores of the membrane have a fixed size. Particles larger than the pore size cannot pass through the membrane and are retained on the surface or within the membrane.

Step 2: Meaning of size exclusion.
Size exclusion means separation based on particle size. Smaller particles or molecules pass through the pores, while larger particles are blocked.

Step 3: Why other options are incorrect.
Chemical reaction is not the main principle because membrane filters do not normally remove particles by reacting chemically with them.
Adsorption may occur to some extent, but it is not the main mechanism.
Sedimentation occurs due to gravity, but membrane filtration works due to pore size and pressure difference.

Step 4: Final answer.
Thus, membrane filters remove particles mainly by size exclusion. \[ \boxed{\text{Size exclusion}} \]