Question

The ........... is used to remove emulsions, colloids or macro molecules in the range of 0.1 $\mu m$ to 5 nm.

• A. Ultrafiltration
• B. Nanofiltration
• C. Microfiltration
• D. Reverse osmosis

Hint:

Membrane Hierarchy (Descending size): Microfiltration (Bacteria) $\rightarrow$ Ultrafiltration (Proteins) $\rightarrow$ Nanofiltration (Sugars) $\rightarrow$ Reverse Osmosis (Salts).

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
The question asks to identify the specific membrane separation technology based on the size range of the particles it is designed to remove (0.1 \(\mu m\) to 5 nm).

Step 2: Detailed Explanation:

• Membrane separation processes use a semi-permeable barrier to separate components of a mixture based on size, shape, or charge.

• Microfiltration (MF): Operates in the range of 0.1 to 10 \(\mu m\). It is typically used to remove bacteria, fat globules, and large suspended solids.

• Ultrafiltration (UF): Operates in the range of 0.1 \(\mu m\) down to about 2 to 5 nm (or 1,000 to 500,000 Daltons molecular weight cutoff). This matches the range provided in the question. It is effective for removing macromolecules like proteins, large viruses, and colloids.

• Nanofiltration (NF): Operates in the range of 1 to 5 nm. It removes small molecules like sugars, herbicides, and multivalent ions.

• Reverse Osmosis (RO): Has the smallest pore size ($<$ 1 nm) and can remove monovalent ions (salts) and very small organic molecules.

• Given the range 0.1 \(\mu m\) (upper limit) to 5 nm (lower limit), Ultrafiltration is the correct technical classification. It is widely used in the dairy industry for concentrating whey proteins.

Step 3: Final Answer:
Ultrafiltration is used for the removal of particles in the range of 0.1 \(\mu m\) to 5 nm.