PhotoActive tiles: an industrial challenge in the
world of photocatalysis
Prof. Claudia L. Bianchi
Final remarks
1) Only nanocrystallites TiO2 is active from the photocatalytic point of view ? NO
2) Any «chance» for larger-sized TiO2 ????? YES
Possible alternative to nano-sized TiO2
3) Micro-TiO2 in a construction material: photocatalytic tiles
YESPreservation of the common tiles
propertiesGood results as a photocatalytic materials
C.L. Bianchi, et al. Advances in Materials Science and Engineering, vol. 2012, Article ID 970182, 8 pages, (2012) doi:10.1155/2012/970182
Pigmentary TiO2
Pure anatase, Uncoated surface, Commercially available (not sold as photocatalytic materials), Powder form
Sample
BET (m2/g) XRD
Crystallite size(nm)
XPS TI2p
Band
gap
(eV)P25 50 75:25 20-25 Ti(IV) 3,21
A 12 100 110 Ti(IV) 3,15B 11 100 95 Ti(IV) 3,25C 23 100 40 Ti(IV) 3,28
D 11 100Mix
(micro-sized +
ultrafine)Ti(IV) 3,25
E 11 100 180 Ti(IV) 3,17
C.L. Bianchi, et al., “Pigmentary TiO2: a challenge for its use as photocatalyst in NOx air purification”, Chemical Eng J, 10.1016/j.cej.2014.03.078
I.R. Characterization
IR spectra in the 3900 - 2800 cm-1 spectral region of samples oxidized at 300°C
3800 3600 3400 3200 3000 2800
OH "free"
outgassed RT outgassed 100°C outgassed 200°C oxidized 300°C
36383670
3719
3631
3660
P25
Abs
orba
nce
Wavenumbers (cm-1)
0.1
CH
IR spectra in the 3900 - 2800 cm-1 spectral region of P25, after activation in different conditions
3800 3600 3400 3200 3000 2800
CH
OH "free"
3244
34773693
C
B
3720
3670
A
P25
Wavenumbers (cm-1)
Abso
rban
ce
0.1 a.u.
3640 Samples oxidized at 300°C
Prof. Claudia L. Bianchi
Experimental batch set-ups: NOx and VOC degradation
o UV lamp (320-400 nm)o 1 ppm NOxo T = 30°C o V = 20 l o Relative humidity = 40% o 10 W/m2
o UV lamp (320-400 nm)o 400 ppm VOCo T = 30°C o V = 5 l o Relative humidity = 40% o 30 W/m2
Prof. Claudia L. Bianchi
Tests on all TiO2 in powder form: the case of sample A
Pollutant ppmAcetaldehyd
e 400 Micro-GC my lab
Acetone 400 Micro-GC my labEthanol 400 Micro-GC my lab
Propyl alcohol 400 GC
Milan Polytechnic – Prof. Diamanti
Toluene 400 Micro-GC my labNOx 1 chemiluminescen
ce my lab
NO 0,4 chemiluminescence
Univ Venice - Prof.
Signoretto
• Gas phase• Standard UV-A lamps• 30 W/m2 (except for NO/NOx: 10 W/m2)
EtOH degradation
EtOH degradation: Comparison P25/Kronos 1077 (sample A)
Tiles preparation
Industrial porcelain-grés tiles are manufactured under high pressure by dry-pressing fine processed ceramic raw materials and finally fired at high temperatures (1200 - 1300°C) in a kiln.
Tiles were then treated at high temperature (approx. 680°C) for 80 min and hardly brushed to remove the powder present at the sample surface and not completely stuck.
Photoactive porcelain-grés tiles were subsequently covered at the surface with a mixture of pure anatase micro-TiO2 and a commercial SiO2-based compound.
Bianchi, Capucci et al., CCC, 36 (2013) 116
Patent - EP2443076
Tiles name: White Ground ActiveTM
1077 by Kronos(sample A)
Amount of TiO2 on the tiles = 1.1 g/m2
Prof. Claudia L. Bianchi
TiO2 + SiO2-based compound: characterization
Sample
BET surface area m2/g
XRPDXPSTi 2peV
pure TiO2
11.0
Pure anatas
e 458.5
TiO2 + SiO2-based
compound2.6
Pure anatas
e 458.4
Prof. G. Cerrato – Turin University
Final material properties:• hardness • lack of porosity• vitrified surface • durability
Kindergarten «Il bruco» - L’Aquila (Italy)
Mirafiori Motor Village – Torino (Italy)
Self-cleaning performance
Oleic acid degradation(ISO 27448-1)
Decolorationof dyes put in contact with
the tilesAntibacterial activity
(ISO 27447)performed by Artest
Modena-Italy
De-pollutant
Methylen blue degradation in
water(ISO 10678)
NOx degradation in both batch and
plug-flow reactors
Phot
ocat
alyt
ic
prop
erti
esPhotocatalytic
properties
PHOTOCATALYSIS: MAKES IT DIFFICULT FOR DIRT TO DEPOSIT
Modification of Surface Hydrophilic Properties
Common porcelain Photocatalytic porcelain gres tile gres tile
Contact angle measurements
Prof. S. Biella – Milan Polytechnique
Prof. Claudia L. Bianchi
Tiles performance: NOx degradation NOx: 1000 ppb
0 50 100 150 200 250 300 350 4000
102030405060708090
100
KronosOrosei
Time (min)
Conv
% N
Ox
-----------------------------------
• Amount of TiO2 on the tiles during the photocatalytic test: 0,004 g
• Amount of TiO2 in powder form during the photocatalytic test: 0,04g
• Time to reach 80% NOx degradation with the tiles during the photocatalytic test: 360 min
• Time to reach 80% NOx degradation with TiO2 in powder form during the photocatalytic test: 36 min
Prof. Claudia L. Bianchi
WHO guidelines for NO2
Based on this we can conclude that all the measurements performed on White Ground Active (WGA) tiles, carried out strictly following the ISO rules which recommend 1000 ppb of NO2 (equal to 1880 µg/ m3), show a pollutant concentration significantly higher than the limits set by the EU Directive.
Limit values (Annex XI e XII to the European Directive 2008/ 50/ CE)
Annual limit value (NO2) 40 µg/m3 equal to 21,27 ppb Hourly limit value (NO2) (not to be exceeded more than 18 times in any calendar year )
200 µg/m3 equal to 106,36 ppb
Annual critical level for the (NOx) protection of vegetation and natural ecosystems
30 µg/m3 equal to 15,95 ppb
Alert threshold (NO2) 400 µg/m3 equal to 212,72 ppb
Prof. Claudia L. Bianchi
050
100150200250300350400
020406080100120140160180200
Hong KongDaily mean values
NO
x
NO
2
01/11/2011 – 31/12/2011
Case History: Hong Kong
NO2 Annual limit value
Values on the graph in μg/m3
NO2 Hourly limit value
Prof. Claudia L. Bianchi
Case history: Milano (Italy)
Prof. Claudia L. Bianchi
NO2 inlet valueTim
e to
reac
h th
e an
nual
mea
n va
lue
of 4
0 μg
/m3
h
10 W/m2
20 W/m2
Tiles performance with real pollution levels
Value fixed in ISO 22197-1
Prof. Claudia L. Bianchi
Final remarks
• Interesting photocatalytc performance of all microsized samples in gas phase.
• Nano-TiO2 shows always the best results towards the photodegradation of both NOx, but with levels of real pollutions, powdered nano and micro-sized TiO2 seems to show similar photodegradation results.
• Photocatalytic tiles are now an industrial reality. Photocatalytic tiles, commercially available, combine porcelain-grés material features and photocatalytic properties.
• features