期刊
POWDER TECHNOLOGY
卷 377, 期 -, 页码 966-973出版社
ELSEVIER
DOI: 10.1016/j.powtec.2020.09.033
关键词
Milling; Heterogeneous particles; Iso-electric point; Surface science
资金
- EPSRC Centre for Doctoral Training in Complex Particulate Products and Processes [EP/L015285/1]
- Venator Ltd.
- UCL [PR16195]
In the stirred wet milling of aluminum-doped TiO2, the pH shift was smaller at 8000 rpm due to a change in milling mechanism. XPS analysis showed a linear correlation between surface alumina content and particle specific surface area. TEM images revealed the presence of ultra-fines coating larger particles, which suppressed the pH shift.
The stirred wet milling of aluminum-doped TiO2 was considered. At milling speeds of 2500-6000 rpm, the pH(i.e.p). shifted from pH 5.7 to pH similar to 8, while at 8000 rpm the shift in pH(i.e.p). was smaller. Milling at 8000 rpm, the reduced milling performance was attributed to a change in the predominant milling mechanism. XPS revealed an approximate linear correlation between the relative surface alumina content (at.%) and particle specific surface area, with the shifting pH(i.e.p). corresponding to the surface alumina. The lower pH(i.e.p). at 8000 rpm was rationalized by high resolution TEM image analysis. Samples milled at 8000 rpm (beyond mill energies used in pigment production) produced a significant quantity of ultra-fines (d(50) << 50 nm) which coated the larger particles. These ultra-fines were predominately titania-like and suppressed the shift in pH(i.e.p). The study confirmed the aluminum-doped TiO2 particles were initially titania surface-rich with bulk alumina increasingly exposed during milling. (C) 2020 The Authors. Published by Elsevier B.V.
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