Surface charge and interfacial potential of titanium dioxide nanoparticles: Experimental and theoretical investigations
Artikel i vetenskaplig tidskrift, 2013

Size dependent surface charging and interfacial potential of titanium dioxide (TiO2) nanoparticles are investigated by experimental and theoretical methods. Commercially available TiO2 (P25) nanoparticles were used for surface charge determinations by potentiometric titrations. Anatase particles, 10 and 22 nm in diameter, were synthesized by controlled hydrolysis of TiCl4, and electrophoretic mobilities were determined at a fixed pH but at increasing salt concentrations. Corrected Debye–Hückel theory of surface complexation (CDH-SC) was modified to model the size dependent surface charging behavior of TiO2 nanoparticles. Experimentally determined surface charge densities of rutile and P25 nanoparticles in different electrolytes were accurately modeled by the CDH-SC theory. Stern layer capacitances calculated by the CDH-SC theory were in good agreement with the values found by the classical surface complexation approach, and the interaction of protons with OH groups is found to be less exothermic than for iron oxide surfaces. Moreover, the CDH-SC theory predicts that the surface charge density of TiO2 nanoparticles of diameter <10 nm is considerably higher than for larger particles, and pH at the point of zero charge (pHPZC) shifts to higher pH values as the particle size decreases. The importance of including the particle size in calculating the zeta potentials from mobilities is demonstrated. Smoluchowski theory showed that 10 nm particles had lower zeta potential than 22 nm particles, whereas a reverse trend was seen when zeta potentials were calculated by Ohshima’s theory in which particle size is included. Electrokinetic charge densities calculated from zeta potentials were found to be only one third of the true surface charge densities.

Anatase

P25

salt titrations

Corrected Debye–Hückel

Surface Complexation

Rutile

Electrokinetic Charge

Electrophoretic Mobility

Zeta Potential

Författare

Jenny Perez-Holmberg

Göteborgs universitet

Elisabet Ahlberg

Göteborgs universitet

Johan Bergenholtz

Göteborgs universitet

Martin Hassellöv

Göteborgs universitet

Zareen Abbas

Göteborgs universitet

Journal of Colloid and Interface Science

0021-9797 (ISSN)

Vol. 407 1 168-176

Ämneskategorier

Kemi

DOI

10.1016/j.jcis.2013.06.015