What is the Difference Between Filtration and Purification

The main difference between filtration and purification is that filtration is a basic process that mainly removes larger particles or suspended matter. In contrast, purification involves more comprehensive methods to eliminate a wide range of impurities, including dissolved contaminants and microorganisms.

Filtration and purification are two distinct processes used to remove impurities from various substances, such as liquids or gases. While both methods aim to improve the quality of the substance, they differ in their specific mechanisms and the degree of impurity removal.

Key Areas Covered

1. What is Filtration  
      – Definition, Features, Mechanism
2. What is Purification
      – Definition, Features, Mechanism
3. Similarities Between Filtration and Purification
      – Outline of Common Features
4. Difference Between Filtration and Purification
      – Comparison of Key Differences

Key Terms

Filtration, Purification

Difference Between Filtration and Purification - Comparison Summary

What is Filtration

Filtration is a process used to separate solid particles or suspended matter from fluids or gases. It plays a crucial role in improving the quality and purity of substances, ensuring they meet specific standards or requirements.

Filtration relies on the principle of using a porous medium or filter to selectively allow the passage of the desired fluid or gas while trapping and retaining solid particles or impurities. The filter can be composed of different materials, such as paper, cloth, sand, activated carbon, or specialized membranes, depending on the specific application and the size of the particles to be filtered.

Compare Filtration vs Purification - What's the difference?

Figure 1: Filtration

Mechanisms of Filtration

Filtration operates through various mechanisms to achieve separation based on particle size, density, and the interaction between the particles and the filter media.

These mechanisms include:

  • Sieving: This mechanism occurs when particles larger than the filter’s pore size cannot pass through, resulting in their retention and separation from the fluid or gas. Sieving is commonly used in applications where larger solid particles must be removed.
  • Inertial Impaction: When a fluid carrying particles passes through a filter, the particles may be too large or heavy to follow the fluid’s streamline and collide with the filter media, causing them to be trapped and separated. Inertial impaction is effective for particles with high momentum or large size.
  • Interception: In this mechanism, particles smaller than the filter pore size may follow the fluid streamlines but come into contact with the filter media due to their proximity. The particles are intercepted and retained, resulting in separation from the fluid or gas.
  • Diffusion: Smaller particles,e smaller than the filter pores may exhibit Brownian motion, causing them to collide and adhere to the filter media, thus separating them from the fluid or gas stream.

Applications of Filtration

Filtration is essential in various industries for different purposes. In water treatment, it removes contaminants to produce safe drinking water. Air filters improve indoor air quality by capturing airborne particles and pollutants. In the chemical and pharmaceutical sectors, filtration purifies products and separates solids from liquids. The oil and gas industry uses filtration to remove impurities and maintain equipment efficiency.

What is Purification

Purification is a fundamental concept in chemistry that involves separating and removing impurities from substances, allowing for the acquisition of pure compounds. Purification techniques play a crucial role in various aspects of chemistry. It is essential in chemical research as it enables scientists to isolate and study compounds in their purest form. Impurities can affect substances’ physical and chemical properties, making their characterization and analysis challenging.

Researchers can separate mixtures and obtain pure compounds for in-depth study through techniques such as fractional distillation, recrystallization, and chromatography. Pure substances serve as standards for comparison, allowing scientists to accurately elucidate the structure, properties, and reactivity of compounds. Purification also plays a critical role in determining the purity of synthesized or extracted substances, ensuring the reliability of experimental results and enabling the advancement of scientific knowledge.

Filtration vs Purification

Figure 2: Water Purification

In industrial processes, purification is essential for producing high-purity and -quality chemicals, materials, and pharmaceuticals. Many industrial sectors, such as pharmaceuticals, petrochemicals, and food production, rely on purification techniques to meet stringent standards and regulatory requirements. Distillation, filtration, and extraction processes are employed to remove impurities and contaminants from raw materials. This ensures the production of pure and safe products. High-performance liquid chromatography (HPLC) and gas chromatography (GC) techniques are extensively used in quality control laboratories to analyze and verify the purity of manufactured substances. Purification techniques also facilitate the recycling and recovery of valuable materials from waste streams.

Similarities Between Filtration and Purification

  • Both filtration and purification involve the separation of substances based on their physical or chemical properties.
  • The central objective of both filtration and purification is the elimination of impurities.
  • Filtration and purification are employed to enhance the purity of a substance.

Difference Between Filtration and Purification


Filtration is a process of separating solids or suspended particles from a fluid or gas by passing it through a porous medium. Purification is the process of removing impurities or contaminants from a substance or system, typically to improve its quality, safety, or usability.


Moreover, filtration relies on a physical barrier, such as a filter medium or membrane, to trap and retain solid particles or larger contaminants while allowing the fluid or gas to pass through. On the other hand, purification uses various techniques beyond filtration, including separation, extraction, or chemical processes, to selectively remove impurities or convert them into less harmful or undesirable forms.


Filtration is often used as a preliminary step in purification processes to remove coarse impurities before further purification steps. It is primarily concerned with the removal of visible or suspended solids. Purification encompasses a broader range of methods and may include filtration as one of the steps. It addresses the overall removal of impurities, which can be in various forms, such as solids, liquids, gases, dissolved substances, or chemical compounds.


In brief, filtration and purification are two distinct processes used to remove impurities from various substances, such as liquids or gases. Filtration is a basic process that mainly removes larger particles or suspended matter. On the other hand, purification involves more comprehensive methods to eliminate a wide range of impurities, including dissolved contaminants and microorganisms. Thus, this is the main difference between filtration and purification.


1. “Filtration | Definition, Examples, & Processes.” Encyclopedia Britannica.
2. “Water purification | Description, Processes, & Importance.” Encyclopedia Britannica.

Image Courtesy:

1. “FilterDiagram” By Wikiwayman at English Wikipedia (CC BY-SA 3.0) via Commons Wikimedia
2. “Water purification process” By “DensityDesign Integrated Course Final Synthesis Studio” at Polytechnic University of Milan, organized by DensityDesign Research Lab in 2016. Uploaded by Maria Elena Besana – Own work (CC BY-SA 4.0) via Commons Wikimedia

About the Author: Hasini A

Hasini is a graduate of Applied Science with a strong background in forestry, environmental science, chemistry, and management science. She is an amateur photographer with a keen interest in exploring the wonders of nature and science.

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