Surface modification of titania nanoparticles by catechol derivative molecules: Preparation of concentrated suspensions

This work focused on the preparation of high solid content suspension from nanosized TiO2 P25 (about 30 nm). Two derivative catechol molecules (Tiron and Dopamine), were used as dispersants to enhance the colloidal stability of the prepared suspensions. Dopamine is a positively charged molecule which was used for the first time as dispersing agent and compared to Tiron, a negatively charged molecule. The effect of the pH and the dispersant percentage on the hydrodynamic size as well as on the surface chemistry of titania was studied in diluted suspension, using dynamic light scattering (DLS) and zeta potential measurements (acoustophoresis). Tiron and Dopamine adsorptions on titania surface were investigated using UV-vis spectrometry and thermo-gravimetric analyses (TGA). It was illustrated, from the rheological behavior, that Tiron and Dopamine decrease dramatically the viscosity of highly concentrated titania suspensions and allow to reach up to 15 vol% and 20 vol% for dopamine and tiron-modified titania suspensions.