Modeling competitive adsorption of molybdate, sulfate, selenate, and selenite using a Freundlich-type multi-component isotherm
Resource
Chemosphere 47 (3): 283-292
Journal
Chemosphere
Journal Volume
47
Journal Issue
3
Pages
283-292
Date Issued
2002
Date
2002
Author(s)
Abstract
This study examined the interactions of MoO42- + SO42-, MoO42- + SeO42-, and MoO42- + SeO32- systems on γ-Al2O3 to better understand the competitive adsorption of these anions in the natural environment. The Freundlich isotherms of anionic adsorption onto γ-Al2O3 in single and binary solutes were also investigated to estimate the competition between these anions. Experimental results indicate that a higher concentration of competitive solute yields a higher efficiency of the competitive solute's prevention of MoO42- adsorption. The most significant result was found in the MoO42- + SeO32- system. The Freundlich isotherm constant (n) increases with the competitive solute concentration. The suitability of a Freundlich-type isotherm, the Sheindorf-Rebuhn-Sheintuch (SRS) equation, and the modified SRS equation in representing the competitive adsorption of MoO42-, SO42-, SeO42-, and SeO32- γ-Al2O3 surface, was also examined. Each set of isotherm data was found to conform to linear SRS expressions, allowing competition coefficients to be derived on a concentration basis for each binary-solute system. The competition coefficient aij and relative affinity coefficients aij can be seen as a way to quantify competitive interactions. The proposed SRS and modified SRS equations are simple mathematical expressions accounting for competitive interactions of anions present in a mixture for the range of concentrations over which each individual component exhibits Freundlich behavior. © 2002 Elsevier Science Ltd. All rights reserved.
Subjects
Anionic adsorption; Binary-solute adsorption; Competition coefficients; Modified SRS equation; Relative affinity coefficients; SRS equation
Other Subjects
Isotherms; Molybdenum compounds; Negative ions; Binary solutes; Adsorption; aluminum; anion; molybdic acid; selenate; sulfate; Adsorption; adsorption; article; binding affinity; calculation; chemical composition; competition; concentration (parameters); model; molecular interaction; solute; thermodynamics
Type
journal article
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