Characterisation of polyphosphate coated aluminium-doped titania nanoparticles during milling
| Autor: | Stephen Sutcliffe, Richard A. Bourne, Juliette S. Behra, Timothy N. Hunter, Ali Hassanpour, Laura N. Elliott, Nicole Hondow, John L. Edwards |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: |
Materials science
chemistry.chemical_element 02 engineering and technology 010402 general chemistry 01 natural sciences Dispersant Biomaterials Sodium hexametaphosphate chemistry.chemical_compound Colloid and Surface Chemistry Dynamic light scattering Aluminium Polyphosphate digestive oral and skin physiology technology industry and agriculture food and beverages 021001 nanoscience & nanotechnology 0104 chemical sciences Surfaces Coatings and Films Electronic Optical and Magnetic Materials chemistry Chemical engineering Transmission electron microscopy Particle Particle size 0210 nano-technology |
| ISSN: | 0021-9797 |
| Popis: | 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. Primary particle sizes 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 3–4.5, 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 after washing for longer milled pigments. |
| Databáze: | OpenAIRE |
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