Limits...
Role of Surface Area, Primary Particle Size, and Crystal Phase on Titanium Dioxide Nanoparticle Dispersion Properties

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Characterizing nanoparticle dispersions and understanding the effect of parameters that alter dispersion properties are important for both environmental applications and toxicity investigations. The role of particle surface area, primary particle size, and crystal phase on TiO2 nanoparticle dispersion properties is reported. Hydrodynamic size, zeta potential, and isoelectric point (IEP) of ten laboratory synthesized TiO2 samples, and one commercial Degussa TiO2 sample (P25) dispersed in different solutions were characterized. Solution ionic strength and pH affect titania dispersion properties. The effect of monovalent (NaCl) and divalent (MgCl2) inert electrolytes on dispersion properties was quantified through their contribution to ionic strength. Increasing titania particle surface area resulted in a decrease in solution pH. At fixed pH, increasing the particle surface area enhanced the collision frequency between particles and led to a higher degree of agglomeration. In addition to the synthesis method, TiO2 isoelectric point was found to be dependent on particle size. As anatase TiO2 primary particle size increased from 6 nm to 104 nm, its IEP decreased from 6.0 to 3.8 that also results in changes in dispersion zeta potential and hydrodynamic size. In contrast to particle size, TiO2 nanoparticle IEP was found to be insensitive to particle crystal structure.

No MeSH data available.


TiO2 (P25) dispersion hydrodynamic diameter as a function of particle mass concentration at constant solution pH of 4 and different solution ionic strengths (0.001–0.1 M).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3211333&req=5

Figure 4: TiO2 (P25) dispersion hydrodynamic diameter as a function of particle mass concentration at constant solution pH of 4 and different solution ionic strengths (0.001–0.1 M).

Mentions: Particle concentration effect was further examined by fixing the solution pH at ~4. Three ionic strengths and five different mass concentrations were tested. As shown in Figure 4, the dispersion hydrodynamic diameter did not decrease with increasing particle surface area once the solution pH was fixed. At low solution IS, the dispersion hydrodynamic size remained similar with increasing particle concentration, because the electrostatic repulsive force helped to prevent agglomeration. At high solution IS, the increased particle number concentration led to enhanced coagulation rates and larger hydrodynamic diameters. At solution IS of 0.1 M and particle mass concentration of 500 μg/ml, the average hydrodynamic diameter was ~2,900 nm (large agglomerates).


Role of Surface Area, Primary Particle Size, and Crystal Phase on Titanium Dioxide Nanoparticle Dispersion Properties
TiO2 (P25) dispersion hydrodynamic diameter as a function of particle mass concentration at constant solution pH of 4 and different solution ionic strengths (0.001–0.1 M).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211333&req=5

Figure 4: TiO2 (P25) dispersion hydrodynamic diameter as a function of particle mass concentration at constant solution pH of 4 and different solution ionic strengths (0.001–0.1 M).
Mentions: Particle concentration effect was further examined by fixing the solution pH at ~4. Three ionic strengths and five different mass concentrations were tested. As shown in Figure 4, the dispersion hydrodynamic diameter did not decrease with increasing particle surface area once the solution pH was fixed. At low solution IS, the dispersion hydrodynamic size remained similar with increasing particle concentration, because the electrostatic repulsive force helped to prevent agglomeration. At high solution IS, the increased particle number concentration led to enhanced coagulation rates and larger hydrodynamic diameters. At solution IS of 0.1 M and particle mass concentration of 500 μg/ml, the average hydrodynamic diameter was ~2,900 nm (large agglomerates).

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Characterizing nanoparticle dispersions and understanding the effect of parameters that alter dispersion properties are important for both environmental applications and toxicity investigations. The role of particle surface area, primary particle size, and crystal phase on TiO2 nanoparticle dispersion properties is reported. Hydrodynamic size, zeta potential, and isoelectric point (IEP) of ten laboratory synthesized TiO2 samples, and one commercial Degussa TiO2 sample (P25) dispersed in different solutions were characterized. Solution ionic strength and pH affect titania dispersion properties. The effect of monovalent (NaCl) and divalent (MgCl2) inert electrolytes on dispersion properties was quantified through their contribution to ionic strength. Increasing titania particle surface area resulted in a decrease in solution pH. At fixed pH, increasing the particle surface area enhanced the collision frequency between particles and led to a higher degree of agglomeration. In addition to the synthesis method, TiO2 isoelectric point was found to be dependent on particle size. As anatase TiO2 primary particle size increased from 6 nm to 104 nm, its IEP decreased from 6.0 to 3.8 that also results in changes in dispersion zeta potential and hydrodynamic size. In contrast to particle size, TiO2 nanoparticle IEP was found to be insensitive to particle crystal structure.

No MeSH data available.