The Halsey isotherm for water contaminant adsorption is fake
Document Type
Article
Publication Date
5-1-2023
Abstract
We present a critique of the Halsey isotherm model (also known as Frenkel-Halsey-Hill), which is used by many researchers to interpret water contaminant adsorption data. We first convert the original Halsey isotherm for gas-phase adsorption to a form appropriate for liquid-phase adsorption. We call this version the ``genuine Halsey isotherm.'' We then show that the Halsey isotherm currently used in water contaminant adsorption research bears only a partial resemblance to the genuine Halsey isotherm. As such, we label the former the ``fake Halsey isotherm.'' We go on to prove that the fake Halsey isotherm is mathematically equivalent to the Freundlich isotherm. Consequently, the modeling results obtained by the fake Halsey isotherm reported in numerous pre-viously published studies have been mostly misleading. Many such reports can be found across a broad spectrum of major journals. Finally, we highlight the data-fitting attributes of the genuine Halsey isotherm. It is shown to be capable of describing adsorption isotherms having types I, II, and III curve shapes.
Keywords
Frenkel-Halsey-Hill, Isotherm misuse, Sigmoid isotherm, Type I isotherm, Type II isotherm, Type III isotherm
Divisions
sch_che
Publication Title
Separation and Purification Technology
Volume
313
Publisher
Elsevier
Publisher Location
RADARWEG 29, 1043 NX AMSTERDAM, NETHERLANDS