Abstract Summary (Max 250 words)
New formulation coatings with antimicrobial additives- dispersions of nanoparticles such as titanium dioxide, silica- can be an effective means to minimise the rapid spread of diseases in areas of dense populations (hospitals, schools, in public transport) and difficult-to-clean surfaces. This study was performed with titanium dioxide dispersions (10% w:w in water at pH≈3 - stability shown via zeta potential measurements) used as antimicrobial coating additives with the objectives to determine the kinetics and mechanisms of deagglomeration, dispersion fineness and provide guidelines for process design. Process intensification approach was taken using a batch rotor-stator with different mixer heads and an ultrasonic processor. The dominant mechanism of deagglomeration was erosion and dispersion fineness was defined by the mean aggregate size (~120 nm) regardless of the power input and dispersion method. Deagglomeration kinetics on the other hand was enhanced by increasing the power input. The effect was more prominent with the ultrasonicator and overall, kinetics were significantly faster allowing complete deagglomeration. Detailed quantitative analysis of kinetics will be presented at the Conference, also including comparisons to hydrophilic silica dispersions and agglomerate strength values. The rotor-stator alone could ascertain dispersion homogeneity; with the ultrasonicator an impeller was also required. Final dispersions demonstrated long-term stability. The dispersions were Newtonian with a low viscosity, in contrast to a more complex rheology noted with hydrophilic silica dispersions at a comparable concentration. We will report on final product/coating properties formed with pre-dispersions, partially and fully deagglomerated additives. Finally, recommendations for design and scale-up will be provided.
