Botha, JA, Hunter, TN orcid.org/0000-0003-3922-491X, Johannsmann, D et al. (6 more authors) (2019) Resonance properties of quartz crystal microbalance immersed in high solid content suspensions. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 573. pp. 230-236. ISSN 0927-7757
Abstract
The resonance properties, frequency and half-band-half-width, of a quartz crystal microbalance (QCM) immersed in concentrated suspensions of 16.2 vol% TiO2 are shown to be a function of pH. The overall QCM response is dependent on the complex interactions between the QCM sensor and overlying particle suspension. Atomic force microscopy confirms pH dependent interaction forces between the QCM sensor (gold-coated) and a TiO2 particle: a strong attraction is measured between pH 4–4.5, and the interaction becomes increasingly repulsive at all pH > 6.5. Yield stress measurements of the concentrated TiO2 suspensions also confirm the changing particle-particle interaction strength as the pH is adjusted from acidic to basic conditions. For the chosen system, the total potential energy of interaction (VT) between the sensor-suspension (Au-TiO2) is comparatively stronger than the particle-particle (TiO2-TiO2) interaction; hence the QCM responds to changes in VT sensor-suspension, as verified by the calculated interaction energy between two dissimilar surfaces (Hogg-Healy-Fuerstenau (HHF) theory), and not the suspension yield stress. Slight deviation between the measured QCM responses and the theoretical sphere-plate interaction strength is shown over a narrow pH range and likely corresponds to strengthening particle-particle interactions. Although the suspensions exhibit significant yield strengths, the QCM response can be suitably described by the sensor-suspension contact mechanics of inertial loading. Combined with our previous study [1], the current study confirms the suspension yield strength can only be measured when VT sensor-suspension is attractive and comparatively weaker than VT particle-particle.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2019 Elsevier B.V. All rights reserved. This is an author produced version of a paper published in Colloids and Surfaces A: Physicochemical and Engineering Aspects. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | Quartz crystal microbalance; Suspension; Colloids; Colloidal forces |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Chemical & Process Engineering (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 25 Jun 2019 07:48 |
Last Modified: | 18 Apr 2020 00:38 |
Status: | Published |
Publisher: | Elsevier |
Identification Number: | 10.1016/j.colsurfa.2019.04.043 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:147685 |
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