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