Which purification method uses a semi-permeable membrane to remove contaminants from water?

Which purification method uses a semi-permeable membrane to remove contaminants from water?

• A. Reverse osmosis
• B. Distillation
• C. Carbon filter
• D. Britta

Answer: (A)

A semi-permeable membrane lets water molecules pass through while blocking larger dissolved substances, and applying pressure to push water through this membrane is what reverse osmosis does. This process effectively removes salts, minerals, and many organic contaminants, producing purified water because the membrane acts as a barrier to dissolved ions while still allowing clean water to pass through. Distillation relies on heating and condensation rather than a membrane, separating components by volatility. A carbon filter traps many chemicals through adsorption, not by membrane separation. A Brita system uses activated carbon and sometimes ion-exchange resins, but it isn’t defined by a membrane-based separation method.

A semi-permeable membrane lets water molecules pass through while blocking larger dissolved substances, and applying pressure to push water through this membrane is what reverse osmosis does. This process effectively removes salts, minerals, and many organic contaminants, producing purified water because the membrane acts as a barrier to dissolved ions while still allowing clean water to pass through. Distillation relies on heating and condensation rather than a membrane, separating components by volatility. A carbon filter traps many chemicals through adsorption, not by membrane separation. A Brita system uses activated carbon and sometimes ion-exchange resins, but it isn’t defined by a membrane-based separation method.