Adsorption Isotherm and Removal Efficiency. How Are They Related?

Adsorption processes and adsorbent materials are studied in many courses within the fields of chemistry, chemical engineering, environmental science, materials science, and related disciplines. Laboratory experiments are usually run to obtain adsorption isotherms and quantify removal efficiency (or...

Full description

Saved in:
Bibliographic Details
Published in:Journal of chemical education 2024-11, Vol.101 (11), p.5003-5011
Main Authors: Orduz, Angie E., Zanini, Graciela P., Avena, Marcelo J.
Format: Article
Language:English
Subjects:
Activated carbon
Adsorbents
Adsorption
Analgesics
Chemical engineering
Chemical research
Efficiency
Environmental science
Experiments
Isotherms
Laboratory Experiments
Materials science
Organic Chemistry
Science Materials
Surface chemistry
Citations: Items that this one cites
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Adsorption processes and adsorbent materials are studied in many courses within the fields of chemistry, chemical engineering, environmental science, materials science, and related disciplines. Laboratory experiments are usually run to obtain adsorption isotherms and quantify removal efficiency (or adsorption percentage). When analyzing the results, students have sometimes difficulty understanding the relationships between adsorption extent, adsorption isotherm, and removal efficiency. A higher adsorption extent does not necessarily indicate a higher removal efficiency, which can cause confusion. This paper describes a laboratory experiment that is regularly conducted as part of a PhD course on surface and materials chemistry with a thorough discussion of the results. Four adsorption isotherms of paracetamol on activated carbon are analyzed, with the adsorbent dose and initial concentration of paracetamol systematically varied from one isotherm to another. The experimental data and simple isotherm equations clearly demonstrate that adsorption isotherms are independent of the adsorbent dose and the initial concentration of the adsorbing substance, while removal efficiency depends on these parameters. A relationship between the adsorption extent and removal efficiency is presented, showing that the normal trend is for an increase in the adsorption extent to be accompanied by a decrease in the removal efficiency, even though this may seem contradictory. Additionally, a simple method to evaluate an adsorbent performance is proposed using removal efficiency vs dose plots or equilibrium solute concentration vs dose plots.
ISSN:0021-9584
1938-1328
DOI:10.1021/acs.jchemed.4c00828