Adsorption vs. Desorption: What's the Difference?
Edited by Harlon Moss || By Janet White || Published on December 22, 2023
Adsorption is the process where molecules adhere to a surface, while desorption is the reverse, where molecules detach from a surface.
Key Differences
Adsorption is a surface phenomenon where atoms, ions, or molecules from a gas, liquid, or dissolved solid adhere to a surface. This process creates a film of the adsorbate (the molecules or atoms being accumulated) on the adsorbent's surface. Desorption, in contrast, is the process where adsorbed substances are released from the adsorbent's surface, effectively reversing adsorption.
The process of adsorption is generally spontaneous and exothermic, reflecting its nature of lowering the system's energy. It involves various forces, like Van der Waals forces or chemical bonds. Desorption, on the other hand, may require energy input to overcome these forces and release the adsorbed material, making it an endothermic reaction in many cases.
Adsorption often occurs when a solid surface is exposed to a concentration of particles or gases, leading to a build-up of material on its surface. This process is crucial in applications like filtration, where impurities are adsorbed onto filter materials. Conversely, desorption is a key step in processes like chromatography, where it helps in separating and analyzing compounds.
The rate and extent of adsorption depend on factors like temperature, pressure, and the nature of the adsorbent and adsorbate. Higher temperatures often reduce the extent of adsorption. In desorption, increasing temperature usually facilitates the detachment of molecules, as it provides the necessary energy for overcoming adsorptive forces.
Adsorption can be classified into physisorption (involving weak Van der Waals forces) and chemisorption (involving stronger chemical bonds). Desorption, accordingly, can be physical or chemical, determined by the nature of the forces involved in the initial adsorption process.
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Comparison Chart
Definition
Accumulation of particles on a surface
Release of particles from a surface
Energy Nature
Usually exothermic (releases heat)
Usually endothermic (absorbs heat)
Process Dependency
Depends on pressure, temperature, nature of adsorbent/adsorbate
Depends on energy input, nature of the bond between adsorbent and adsorbate
Industrial Application
Used in filtration, purification
Used in chromatography, regeneration of adsorbents
Types
Physisorption, Chemisorption
Physical Desorption, Chemical Desorption
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Adsorption and Desorption Definitions
Adsorption
Adsorption is the adhesion of atoms, ions, or molecules from a gas, liquid, or dissolved solid to a surface.
The adsorption of contaminants onto activated carbon filters purifies water.
Desorption
Desorption is the process where adsorbed material is released from a surface.
During desorption, pollutants trapped in water filters are removed for filter regeneration.
Adsorption
Adsorption is the process of a substance concentrating at the interface of two phases.
The adsorption of light particles on heavy oil spills aids in environmental cleanup.
Desorption
It involves removing a substance from a surface to which it has been adsorbed.
Desorption of chemicals from sensor surfaces is essential in resetting electronic noses.
Adsorption
It's a surface-based process where material accumulates on a solid or liquid surface.
Adsorption of dyes on fabric fibers is crucial in textile coloring.
Desorption
Desorption is the opposite of adsorption, where molecules detach instead of attaching.
In chromatography, desorption helps in separating different compounds.
Adsorption
It refers to the binding of molecules or particles to a surface.
The adsorption of enzymes onto solid supports is used in industrial biocatalysis.
Desorption
Desorption refers to breaking the bond between an adsorbate and an adsorbent.
Desorption of oxygen molecules from catalyst surfaces is crucial in chemical reactions.
Adsorption
Adsorption involves the creation of a film of adsorbate on the adsorbent surface.
In gas masks, the adsorption of toxic gases on charcoal layers protects the wearer.
Desorption
It's the release of an adsorbate from an adsorbent surface.
Thermal desorption releases volatile compounds from solid samples in analysis.
Adsorption
The accumulation of gases, liquids, or solutes on the surface of a solid or liquid.
Desorption
To release (something) through pores or interstices.
Adsorption
The adhesion of a liquid or gas on the surface of a solid material, forming a thin film on the surface.
Desorption
To remove (an absorbed or adsorbed substance) from.
Adsorption
The process by which molecules of a substance form a thin film on the surface of a solid. Distinguished from absorption, in which the foreign substance penetrates the body of the absorbing material.
Desorption
The process in which atomic or molecular species leave the surface of a solid and escape into the surroundings; the reverse of absorption or adsorption.
Adsorption
The accumulation of molecules of a gas to form a thin film on the surface of a solid
Desorption
Changing from an adsorbed state on a surface to a gaseous or liquid state
FAQs
What triggers adsorption?
Adsorption occurs due to various forces like Van der Waals forces or chemical bonds.
What is needed for desorption to occur?
Desorption often requires energy input to overcome the forces holding the adsorbate.
What industries use adsorption?
Industries like water treatment, air purification, and chemical processing use adsorption.
Is desorption always desirable in industrial processes?
It depends on the application. In some cases, like filter regeneration, it's essential.
How does temperature affect adsorption?
Generally, increasing temperature decreases the extent of adsorption.
Can desorption be a natural process?
Yes, it can occur naturally, especially when conditions change, like a rise in temperature.
Can all materials that adsorb also desorb?
In most cases, yes, but the ease of desorption depends on the strength of the adsorption bond.
What is adsorption?
Adsorption is the process where molecules adhere to a surface.
What is desorption?
Desorption is the process where molecules detach from a surface.
Can adsorption be selective?
Yes, certain adsorbents are selective to specific adsorbates.
Is adsorption a physical or chemical process?
It can be both, physisorption (physical) involves weak forces, while chemisorption (chemical) involves stronger bonds.
What factors influence the rate of adsorption?
Factors like surface area of the adsorbent, concentration of the adsorbate, and temperature.
Can adsorption be used for purification?
Yes, it's widely used for purifying gases and liquids.
What role does desorption play in chromatography?
Desorption allows the separation of different compounds in chromatography.
Does adsorption require energy?
Generally, adsorption releases energy (exothermic).
Do adsorption and desorption always occur together?
Not always simultaneously, but they are complementary processes.
Can desorption be controlled?
Yes, by adjusting parameters like temperature and pressure.
Are there environmental applications of adsorption?
Yes, in areas like air purification and spill cleanup.
Is desorption always an endothermic process?
Mostly, as it often requires energy to release the adsorbed material.
Are adsorption and desorption reversible processes?
They can be, particularly in cases where the adsorption is physical rather than chemical.
About Author
Written by
Janet WhiteJanet White has been an esteemed writer and blogger for Difference Wiki. Holding a Master's degree in Science and Medical Journalism from the prestigious Boston University, she has consistently demonstrated her expertise and passion for her field. When she's not immersed in her work, Janet relishes her time exercising, delving into a good book, and cherishing moments with friends and family.
Edited by
Harlon MossHarlon is a seasoned quality moderator and accomplished content writer for Difference Wiki. An alumnus of the prestigious University of California, he earned his degree in Computer Science. Leveraging his academic background, Harlon brings a meticulous and informed perspective to his work, ensuring content accuracy and excellence.
