What is the Difference Between Filtration and Reverse Osmosis

The key difference between filtration and reverse osmosis is that filtration uses a filter medium for the separation, whereas reverse osmosis uses a partially permeable membrane for the separation process.

Filtration is an analytical technique for the separation of a solid from a liquid. Reverse osmosis is a method of water purification that uses a partially permeable membrane for separation.

CONTENTS

1. Overview and Key Difference
2. What is Filtration  
3. What is Reverse Osmosis
4. Filtration vs Reverse Osmosis in Tabular Form
5. Summary – Filtration vs Reverse Osmosis

What is Filtration?

Filtration is an analytical technique for the separation of a solid from a liquid. This process helps to remove solids in a fluid via passing the fluid through a barrier that can hold the solid particles via a physical, mechanical, or biological operation. Here, the fluid can be a liquid or a gas. The fluid we get after the filtration is the “filtrate.” The barrier we use for the filtration is the “filter.” It can be a surface filter or a depth filter; either way, it traps solid particles. Most of the time, we use filter paper in the laboratory for filtration.

Generally, filtration is not a complete process that leads to purification. However, it is precise compared to decantation. That is because some solid particles may go through the filter while some fluid may remain on the filter without going to the filtrate. There are various types of filtration techniques, including hot filtration, cold filtration, vacuum filtration, and ultrafiltration.

The major applications of the filtration process include the following:

• To separate liquid and solid in a suspension
• Coffee filter: to separate the coffee from the ground
• Belt filters to separate precious metal during mining
• To separate crystals from the solution during the recrystallization process in organic chemistry
• Furnaces use filtration to prevent the furnace elements from fouling with particulates

What is Reverse Osmosis?

Reverse osmosis is a method of water purification that uses a partially permeable membrane for separation. This method is important for the separation of ions, unwanted molecules, and large particles from drinking water. In this technique, we can use an applied pressure to overcome osmotic pressure (osmotic pressure is a colligative property driven by potential chemical differences of the solvent). Moreover, reverse osmosis is important in removing many types of dissolved and suspended chemical species and biological species such as bacteria from water.

We can use reverse osmosis for both industrial processes and the manufacturing of portable water bottles. During this process, the solute is retained on the pressurized side of the partially permeable membrane while the pure solvent passes through the membrane. The membrane is selective because it does not allow large particles or ions to go through the pores, whereas it allows the small particles to pass freely.

What is the Difference Between Filtration and Reverse Osmosis?

Generally, reverse osmosis is different from filtration in the mechanism of fluid flow. In the reverse osmosis process, the fluid flow occurs through a membrane that is partially permeable. However, in the filtration process, we use a filtration medium. Therefore, the key difference between filtration and reverse osmosis is that filtration uses a filter medium for the separation, whereas reverse osmosis uses a partially permeable membrane for the separation process.

The below infographic presents the differences between filtration and reverse osmosis in tabular form for side by side comparison.

Summary – Filtration vs Reverse Osmosis

Filtration is an analytical technique for the separation of a solid from a liquid. Reverse osmosis is a method of water purification that uses a partially permeable membrane for separation. The key difference between filtration and reverse osmosis is that filtration uses a filter medium for the separation, whereas reverse osmosis uses a partially permeable membrane for the separation process.

Reference:

1. Helmenstine, Anne Marie. “Filtration Definition and Processes (Chemistry).” ThoughtCo, Aug. 27, 2020.

Image Courtesy:

1. “FilterDiagram” By Wikiwayman at English Wikipedia (CC BY-SA 3.0) via Commons Wikimedia
2. “Yen Sun Technology YS-8103RWT 20201101” By Solomon203 – Own work (CC BY-SA 4.0) via Commons Wikimedia