Photocatalytic effect with AEROSIL® fumed silica

Self—cleaning by UV light

Evonik's nanoscaled titanium dioxide products are sold under the trade names AEROXIDE® and AEROPERL® and include the well-known AEROXIDE® TiO2 P25. In terms of photocatalysis, AEROXIDE® TiO2 P25 has been subject of many studies over the years, including its use in wastewater treatment, the reduction of NOx in exhaust gases, and the manufacture of anti-bacterial, self-cleaning or antifogging surfaces. Because of its high photoactivity, AEROXIDE® TiO2 P25 is often recognized as the "gold standard" in photocatalysis.

Evonik's titanium dioxides are excellent photocatalysts. This is due to the very high surface area and the mixed anatase and rutile crystal structure. Now we have enlarged our product portfolio—Evonik provides you not only with the well known AEROXIDE^® TiO₂ P25 but also with water based TiO₂ dispersions and finer titania powder:

AEROXIDE^® and AEROPERL^® for photocatalytic effects
Properties (test methods)	Unit	AEROXIDE^®TiO₂ P25 (powder)	VP TiO₂ P90 (powder)	VP AEROPERL^®P25/20 (granulated)
Specific surface area (BET)	m²/g	50 ± 15	90 ± 20	-
pH in 4% dispersion		3.5 - 4.5	3.2 - 4.5	3.0 - 4.5
Average primary particle size	nm	21	approx. 14	approx. 20
Tamped density* acc. to DIN EN ISO 787/11, Aug. 1983	g/l	approx. 130	approx. 120	approx. 700
Moisture* 2 h at 105°C	wt.%	< 1.5	< 4.0	< 2.5
Ignition loss 2 h at 1000°C, based on material dried for 2 h at 105°C	wt.%	< 2.0	< 3.0	< 2.0
TiO₂content based on ignited material	wt.%	< 99.5	< 99.5	> 99.5

The data represents typical values (no product specification)
* ex plant

AERODISP^® for photocatalytic effects
Properties (test methods)	Unit	AERODISP^®W 740 X	VP Disp. W 2730 X
pH DIN EN ISO 787/9		5-7	6-8
TiO₂content based on ignited material	wt.%	40 ± 1	30 ± 1
Mean aggregat size d-50 value	nm	< 100	< 100
Viscosity measured according DIN EN ISO 3219 at a shear rate of 100 s^-1	mPas	< 1000	< 5000
Density 20°C	g/cm³	1.41	1.28

The data represents typical values (no product specification)