The key difference between absorption and stripping is that absorption is the transfer of atoms, molecules, or ions from one material to another, whereas stripping is the transfer of components from a liquid to a vapor stream.
In short, absorption and stripping are two processes that transfer the components and bulk material from one substance to another. However, there are differences in transferring components and the bulk material that captures these components.
CONTENTS
1. Overview and Key Difference
2. What is Absorption
3. What is Stripping
4. Side by Side Comparison – Absorption vs Stripping in Tabular Form
5. Summary
What is Absorption?
Absorption is a chemical process where atoms, molecules or ions enter a bulk phase which is a liquid or a solid material. This process is different from adsorption because, in adsorption, the atoms, molecules, or ions adhere onto the bulk surface, whereas in absorption, atoms, molecules or ions enter into the bulk material. However, the term sorption covers both absorption and adsorption processes, as well as the ion-exchange process.
Figure 01: A Laboratory Absorber
The absorption process refers to a substance being captured and the transformation of energy. In this process, the bulk material that captures the components is absorbent, and the components that are being captured are absorbates. Similarly, in the adsorption process, the corresponding terms are adsorbent and adsorbate.
There are different types of absorption processes, such as chemical absorption and physical absorption. Chemical absorption is an active process, while physical absorption is a non-reactive process. In chemical absorption, the absorbent reacts with the absorbate. This reaction depends on the stoichiometry of the reaction and the concentration of the reactants. In physical absorption, the most common example is the absorption of water by hydrophilic solids. This absorption involves the polar interactions between water and hydrophilic substances.
What is Stripping?
Striping is a chemical process where components are removed from a liquid by a vapour stream. When applying this process in the industry, the liquid stream and vapour stream can have either co-current or countercurrent flows. Usually, a stripping process is performed in either a packed or trayed column.
Figure 02: Bubble Cap Trays
In theory, stripping occurs depending on mass transfer. This technique is important in making the conditions favorable for the component that is going to be transferred into the vapour phase. Also, this process involves an interface of gas-liquid that must be crossed by transferring components. The total amount of components transferred into the vapor is called ‘flux’.
Typically, a stripping process is conducted in trayed towers (named plate columns) and packed columns. It is rarely performed in spray towers, bubble columns, and centrifugal contactors. Among them, the trayed towers contain a vertical column having the flowing liquid from top to bottom. Here, the vapour stream enters from the bottom and exits from the top. These columns contain trays of plates that can force the liquid to flow back and forth horizontally to make the column efficient.
What is the Difference Between Absorption and Stripping?
Absorption and stripping are important chemical processes that have uses in industrial applications. The key difference between absorption and stripping is that absorption is the transfer of atoms, molecules, or ions from one material to another, whereas stripping is the transfer of components from a liquid to a vapor stream.
Below is a summary of the difference between absorption and stripping in tabular form.
Summary – Absorption vs Stripping
Absorption and stripping are two processes that transfer the components from one substance to another. However, the key difference between absorption and stripping is that absorption is the process that transfer atoms, molecules, or ions from one material to another, whereas stripping is the process that transfer the components from a liquid to a vapor stream.
Reference:
1. “Stripping (Chemistry).” Wikipedia, Wikimedia Foundation, 11 Aug. 2020, Available here.
Image Courtesy:
1. “Absorber” By Daniele Pugliesi – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Bubble Cap Trays” By H Padleckas created this image file in the middle of November 2006 for use “Fractionating column” in Wikimedia. – Own work (CC BY-SA 2.5) via Commons Wikimedia