PhotoActive tiles: an industrial challenge in the world of photocatalysis.

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) 3,15

B 11 100 95 Ti(IV) 3,25

C 23 100 40 Ti(IV) 3,28

D 11 100

Mix (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

Ab

sorb

ance

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

3477

3693

C

B

3720

3670

A

P25

Wavenumbers (cm-1)

Abso

rban

ce

0.1 a.u.

3640Samples oxidized at 300°C


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


Tests on all TiO2 in powder form: the case of sample A

Pollutant ppm

Acetaldehyde 400 Micro-GC my lab

Acetone 400 Micro-GC my lab

Ethanol 400 Micro-GC my lab

Propyl alcohol 400 GC

Milan Polytechnic – Prof. Diamanti

Toluene 400 Micro-GC my lab

NOx 1 chemiluminescence 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


TiO2 + SiO2-based compound: characterization

Sample

BET

surface

area

m2/g

XRPD

XPS

Ti 2p

eV

pure TiO2

11.0

Pure

anatas

e

458.5

TiO2 + SiO2-

based

compound

2.6

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

Ph

oto

cata

lyti

c

pro

pert

ies

Ph

oto

cata

lytic

p

rop

ertie

s

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


Tiles performance: NOx degradation NOx: 1000 ppb

0 50 100 150 200 250 300 350 4000

10

20

30

40

50

60

70

80

90

100

Kronos

Orosei

Time (min)

Co

nv%

NO

x

-----------------------------------

• 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


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


0

50

100

150

200

250

300

350

400

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


Case history: Milano (Italy)


NO2 inlet valueTim

e t

o r

each

th

e a

nn

ual m

ean

valu

e o

f 4

0 μ

g/m

3

h

10 W/m2

20 W/m2

Tiles performance with real pollution levels

Value fixed in ISO 22197-1


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

PhotoActive tiles: an industrial challenge in the world of photocatalysis.

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