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Chemisorption and physisorption of alcohols on iron(III) oxide-terminated surfaces from nonpolar solvents.

Salama, Ibrahim, Slavchov, Radomir I, Filip, Sorin V, Clarke, Stuart M (2025) Chemisorption and physisorption of alcohols on iron(III) oxide-terminated surfaces from nonpolar solvents. Journal of colloid and interface science, 685 . pp. 15-28. ISSN 0021-9797. E-ISSN 1095-7103. (doi:10.1016/j.jcis.2025.01.086) (KAR id:108604)

Abstract

The adsorption isotherm of alkanols at the haematite|hydrocarbon interface should reflect both chemisorption (chemically bonded fraction) and physisorption (hydrogen bonded fraction). Quartz crystal microbalance (QCM) and X-ray photoelectron spectroscopy (XPS) have been used for characterization of Fe O |hydrocarbon interfaces with absorbed alcohol. A range of Fe O -terminated surfaces, alkanols, hydrocarbons and temperatures have been investigated. A chemisorption-physisorption Langmuir model (CPL) has been developed to interpret the data. All data show simultaneous physisorption and chemisorption of the alcohol. The CPL analysis reveals variability of the surface chemistry from one sample to another - different fractions of surface sites have been determined for Fe O -coated crystals, Fe O powder, stainless steel-coated crystals etc. However, for a given surface, the fraction of chemisorption sites is stable - it does not change with the alcohol, and changes only slightly with the solvent. The physisorbed alcohol molecules assume configuration normal to the surface, while the chemisorbed molecules assume configuration that is either parallel (high homologues) or normal (low homologues). A transition from normal to parallel orientation has been observed at hexyl. The effects from branching of the alcohol are captured well by CPL. The temperature has been shown to alter both the strength of the physisorption and the fraction of available chemisorption sites.

Item Type: Article
DOI/Identification number: 10.1016/j.jcis.2025.01.086
Uncontrolled keywords: Nonaqueous, Iron oxide, Adsorption, Alcohols, QCM, Chemisorption, XPS
Subjects: Q Science
Q Science > QD Chemistry
Divisions: Divisions > Division of Natural Sciences > Chemistry and Forensics
Funders: BP (United Kingdom) (https://ror.org/01zctcs90)
SWORD Depositor: JISC Publications Router
Depositing User: JISC Publications Router
Date Deposited: 05 Feb 2025 14:28 UTC
Last Modified: 06 Feb 2025 17:17 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/108604 (The current URI for this page, for reference purposes)

University of Kent Author Information

Salama, Ibrahim.

Creator's ORCID: https://orcid.org/0000-0003-4415-0329
CReDIT Contributor Roles: Writing - original draft, Visualisation, Data curation, Investigation, Formal analysis, Methodology
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