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<p>The redispersibility of nanostructured TiO₂ powders composed of nanometric crystallites is a critical requirement for industrial applications that rely on stable aqueous suspensions. However, the combined effects of drying routes and surface chemistry on colloidal stabilization remain insufficiently understood. This study provides a systematic evaluation of how three drying methods (oven, microwave, and freeze-drying) combined with acidic (citric acid) or alkaline (2-amino-2-methyl-1-propanol (AMP-95)) surface treatments govern the redispersion behavior and colloidal stability of TiO₂ nanopowders obtained from an industrial aqueous precursor. The materials were characterized by X-ray diffraction (XRD), differential thermal analysis and thermogravimetric analysis (DTA/TGA), scanning electron microscopy (SEM), specific surface area determined by the Brunauer–Emmett–Teller (BET) method, laser diffraction, zeta potential, accelerated stability analysis, and ultraviolet–visible (UV–Vis) spectroscopy. Freeze-drying preserved the primary particle dispersion most effectively, particularly when combined with AMP-95, which shifted the isoelectric point from pH 3.60 to 5.47 and yielded the lowest sedimentation velocity (1.953 µm/s). Oven drying promoted strong agglomeration, while microwave drying produced intermediate behavior. Surface treatments modulated the electrostatic barrier and influenced the apparent optical behavior: AMP-95 increased the band gap (2.71 eV), whereas citric acid reduced it (2.13 eV), suggesting that surface-related effects may have contributed to the observed optical response. These results demonstrate that redispersibility and long-term colloidal stability are jointly controlled by the interplay between drying-induced microstructural compaction and surface-chemistry-driven charge regulation. The findings provide a framework for selecting drying–stabilization pathways tailored to high-performance TiO₂ nanopowders.</p>

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Engineering drying and surface-stabilization pathways to enhance the colloidal performance of redispersible TiO₂ nanopowders

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年6月19日

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  • Guilherme Dias Zarur,
  • Alexandre Zaccaron,
  • Sabrina Arcaro,
  • João Batista Rodrigues Neto

摘要

The redispersibility of nanostructured TiO₂ powders composed of nanometric crystallites is a critical requirement for industrial applications that rely on stable aqueous suspensions. However, the combined effects of drying routes and surface chemistry on colloidal stabilization remain insufficiently understood. This study provides a systematic evaluation of how three drying methods (oven, microwave, and freeze-drying) combined with acidic (citric acid) or alkaline (2-amino-2-methyl-1-propanol (AMP-95)) surface treatments govern the redispersion behavior and colloidal stability of TiO₂ nanopowders obtained from an industrial aqueous precursor. The materials were characterized by X-ray diffraction (XRD), differential thermal analysis and thermogravimetric analysis (DTA/TGA), scanning electron microscopy (SEM), specific surface area determined by the Brunauer–Emmett–Teller (BET) method, laser diffraction, zeta potential, accelerated stability analysis, and ultraviolet–visible (UV–Vis) spectroscopy. Freeze-drying preserved the primary particle dispersion most effectively, particularly when combined with AMP-95, which shifted the isoelectric point from pH 3.60 to 5.47 and yielded the lowest sedimentation velocity (1.953 µm/s). Oven drying promoted strong agglomeration, while microwave drying produced intermediate behavior. Surface treatments modulated the electrostatic barrier and influenced the apparent optical behavior: AMP-95 increased the band gap (2.71 eV), whereas citric acid reduced it (2.13 eV), suggesting that surface-related effects may have contributed to the observed optical response. These results demonstrate that redispersibility and long-term colloidal stability are jointly controlled by the interplay between drying-induced microstructural compaction and surface-chemistry-driven charge regulation. The findings provide a framework for selecting drying–stabilization pathways tailored to high-performance TiO₂ nanopowders.