Elliott, LN orcid.org/0000-0002-3025-9123, Behra, JS orcid.org/0000-0002-4809-4822, Hondow, N orcid.org/0000-0001-9368-2538 et al. (5 more authors) (2019) Characterisation of polyphosphate coated aluminium-doped titania nanoparticles during milling. Journal of Colloid and Interface Science, 548. pp. 110-122. ISSN 0021-9797
Abstract
This paper investigates the characterisation of alumina-doped titania nanoparticles, milled under high-shear over time, in the presence of sodium hexametaphosphate (SHMP) dispersant. Transmission electron microscopy (TEM) indicated that prolonged milling times led to the formation of 10 nm particle fines which were electrostatically attracted to larger particles, where no change in the crystal structure was observed. The primary particle size measured by dynamic light scattering (DLS) and TEM were in agreement and showed no change in primary particle size (∼250 nm) with respect to milling time, however, there was a clear reduction in the magnitude of the slow mode decay associated to aggregates. The TiO₂ was found to have an isoelectric point (iep) in the range of pH 3 to 4.5, where an increase in milling time led to a lower pHiep, indicative of an increase in SHMP coverage, which was further supported by an intensification in phosphorus content measured by X-ray fluorescence (XRF). Phosphorus content and zeta potential analysis before and after centrifugal washing showed that SHMP was partially removed or hydrolysed for the longer milled pigment samples, whereas no change was observed for shorter milled samples. Relaxation NMR was also performed, where enhanced relaxation rates at longer milling times were associated partially to increases in surface area and exposure of Al sites, as well as physicochemical changes to SHMP density and structure. It is thought that extended milling times may lead to hydrolysis or other structural changes of the dispersant from the high energy milling conditions, allowing easier removal of SHMP for longer milled pigments.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2019 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). |
Keywords: | NMR relaxometry; polyphosphate dispersant; sodium hexametaphosphate; aluminium-doped TiO2 |
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) |
Funding Information: | Funder Grant number EPSRC EP/K005073/1 EPSRC EP/M028143/1 |
Depositing User: | Symplectic Publications |
Date Deposited: | 09 Apr 2019 10:43 |
Last Modified: | 17 Dec 2024 12:49 |
Status: | Published |
Publisher: | Elsevier |
Identification Number: | 10.1016/j.jcis.2019.04.009 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:144693 |