Sun and catalysis: The Environmental Photocatalysis · Sun and catalysis: The Environmental...
Transcript of Sun and catalysis: The Environmental Photocatalysis · Sun and catalysis: The Environmental...
1 1 Environmental Nanotechnologies
Sun and catalysis:
The Environmental Photocatalysis
Dr. Eric Puzenat
2 2 Environmental Nanotechnologies
Outline
I – Generality
- definition
- history
II – Principle of heterogeneous photocatalysis
III – Environmental Photocatalysis
- water treatment
- air treatment
- self-cleaning materials
IV - Conclusions
3 3 Environmental Nanotechnologies
The Photocatalysis
Definition : The photocatalysis is the domain of the catalysis for which light is the activation way for the catalyst
Photochemistry :
Study of chemical changes driven by light absorption by matter
The catalysis :
A catalyst is a substance that increases the rate of a chemical reaction without changing the yield and which is unchanged in the final products Example :
-Atmospheric photochemistry
Examples :
-Enzymatic catalysis
-Acido-basic catalysis
4 4 Environmental Nanotechnologies
Photochemistry vs Photocatalysis
R R* h
Photochemical reactions
Products
Photosensitization reactions
P P* h
R R* Products
P : photosensitizer
P P* h
R RA Products
P : photomediator Pd
5 5 Environmental Nanotechnologies
Photocatalytic reactions
Photochemistry vs Photocatalysis
P
P*
h
R
RA
Products
P is not consumed : photocatalyst Pd
RI P is used in an amount lower than stoechiometric, but light is a stoechiometric reagent
6 6 Environmental Nanotechnologies
The Photocatalysis
In homogeneous phase :
For syntheses via photocatalytic C-C bond formation:
- intermolecular addition onto double or triple C-C bonds
- intermolecular addition onto C=X bonds
- intramolecular addition onto C=C bonds
- cycloaddition
- radical coupling
Examples of photocatalyts :
Chloranil Anthraquinone
Ph2CO UO22+
Uranyl *Fagnoni et al, Chem. Rev, (2007), 107, 2725-2756
7 7 Environmental Nanotechnologies
The Photocatalysis
In heterogeneous phase :
Over the last 30 years, photocatalysis is synonymous of heterogeneous photocatalysis i.e. processes consisting in irradiation of a slurry of semiconductor oxide or sulfide powder or other inorganic compounds
Examples of photocatalyts : TiO2
ZnO
CdS
-Degradation of organic pollutants
-Air treatment
-Water treatment
-Self-cleaning materials
-Water splitting for generation of hydrogen as a
fuel
8 8 Environmental Nanotechnologies
Photocatalysis
material
Solid physics
Kinetics and catalysis
Analytical science
electrochemistry
Chemical ingeneering
bv
bcE/eV
h+
e-
h>Eg
C
r = k[KC/(1+KC)]
C0
rC
r = k[KC/(1+KC)]
C0
r
HOOC-CH=CH-COOH
HOOC-CH 2 -CHOH-COOH
CH3 -CHOH-COOH HOOC-CHOH-CHOH-COOH
HOOC-CHOH-COOH
HOOC-CH 2 -CHO
H2 C=CH-COOH
HOOC-CHO
HOOC-CH 2 OH
HOOC-COOH
CH3 -COOH
HCOOH
CH3 -CO-COOH
CH3 -CHO
CO2
TiO 2 -UV
Reaction pathway of the photocatalytic degradation of malic acidin contact with TiO2 at 290 nm.
malic acid
2-hydroxypropanoic acid
propanedioic acid
acetic acid
formic acid oxalic acid
formylmethanoic acid
hydroxyethanoic acid
propenoic acid
2-oxopropanoic acid
3-oxopropanoic acid
butenedioic acid (trans/cis)
acetaldehyde
(1) (2)
(3)
(4)
HOOC-CH 2 -COOH
2-hydroxypropanedioic acid
2,3-dihydroxybutanedioic acid
(lactic acid)
(pyruvic acid)
(malonaldehydic acid)
(malonic acid)
(acrylic acid)
(glycolic acid)
(glyoxylic acid)
(tartaric acid)
(tartronic acid)
(fumaric/maleic acid)
a,b
a,b a,b,c
a
a,b,c
a
a
a
a
a,b,ca
b,e
identification:a: HPLCb: GC/MSc: Capillary electrophoresisd: GCe: LC/MS
c
HOOC-CH=CH-COOH
HOOC-CH 2 -CHOH-COOHHOOC-CH 2 -CHOH-COOH
CH3 -CHOH-COOHCH3 -CHOH-COOH HOOC-CHOH-CHOH-COOH
HOOC-CHOH-COOH
HOOC-CH 2 -CHOHOOC-CH 2 -CHO
H2 C=CH-COOHH2 C=CH-COOH
HOOC-CHO
HOOC-CH 2 OHHOOC-CH 2 OH
HOOC-COOH
CH3 -COOHCH3 -COOH
HCOOH
CH3 -CO-COOHCH3 -CO-COOH
CH3 -CHOCH3 -CHO
CO2CO2
TiO 2 -UVTiO 2 -UV
Reaction pathway of the photocatalytic degradation of malic acidin contact with TiO2 at 290 nm.
Reaction pathway of the photocatalytic degradation of malic acidin contact with TiO2 at 290 nm.
malic acid
2-hydroxypropanoic acid
propanedioic acid
acetic acid
formic acid oxalic acid
formylmethanoic acid
hydroxyethanoic acid
propenoic acid
2-oxopropanoic acid
3-oxopropanoic acid
butenedioic acid (trans/cis)
acetaldehyde
(1) (2)
(3)
(4)
HOOC-CH 2 -COOHHOOC-CH 2 -COOH
2-hydroxypropanedioic acid
2,3-dihydroxybutanedioic acid
(lactic acid)
(pyruvic acid)
(malonaldehydic acid)
(malonic acid)
(acrylic acid)
(glycolic acid)
(glyoxylic acid)
(tartaric acid)
(tartronic acid)
(fumaric/maleic acid)
a,b
a,b a,b,c
a
a,b,c
a
a
a
a
a,b,ca
b,e
identification:a: HPLCb: GC/MSc: Capillary electrophoresisd: GCe: LC/MS
identification:a: HPLCb: GC/MSc: Capillary electrophoresisd: GCe: LC/MS
c
9 9 Environmental Nanotechnologies
1972 : Honda et al. in Nature : H2 production with electrophotocatalysis. First proofs for photocatalytic oxidation of organic compounds in gaseous phase
1996 : first applications of photocatalysis in air and water treatment
History
1960 : - Institut de Recherhce sur la Catalyse Lyon – department of physical-chemistry (S.J. Teichner)
1975-90 : Fondamental studies and interdisciplinarities (catalysis, electro-,photoelectrochemistry, radiochemistry, photochemistry, analytical chemistry) – the domain around the World Pichat,Herrmann in France, Honda, Fujishima, Tsubomura in Japan, Bard in USA, Grätzel in Switzerland, Pelizetti in Italy, Parmon and Zamaraev in USSR). First proofs for photocatalytic oxidation of organic compounds in aqueous phase
2000 maintenant : applications and development of new industrial products
10 10 Environmental Nanotechnologies
- Promotion of electrons from valence band to conduction band via intrinsic absorption of a photon with energy hEg
vb
cb E/eV
h+
e-
h>Eg
Example TiO2
Ti 3d2 4s2 Ti4+ 3d0
O 2p4 O2- 2p6
Conduction band
Valence band Eg=3,2 eV
absorption of photons with wavelenght <380nm
Photon absorption leads to the formation of {e-/h+} pairs called excitons. The recombination between electrons and holes is very fast leading to a short life time for the exciton.
Photocatalysis principle
11 11 Environmental Nanotechnologies
Mobility of the photogenerated charged species (Dr. H. Gerisher (1993))
Charge separation
12 12 Environmental Nanotechnologies
Herrmann, Disdier, Pichat, Chem. Phys. Lett, 108, 6(1984), 618-622
phot
ocon
duc
tivity
abso
rbanc
e
Charge mobility
Photonic of the solids
TiO2 + h absorption [e-;h+]
recombination Neutral center
charge separation
Charge mobility
Cr/TiO2 + h absorption [e-;h+]
recombination Neutral center
charge separation
13 13 Environmental Nanotechnologies
Semiconductor examples
material band gap (eV) (nm)
TiO2 anatase 3.2 388
TiO2 rutile 3 414
ZrO2 3.25 382
ZnO 3.2 388
CeO2 2.95 421
Sb2O4 2.95 421
SnO2 3.5 355
V2O5 2.25 552
WO3 2.8 443
SrTiO3 3.2 388
Fe2O3 2.2 564
CdS 2.4 517
14 14 Environmental Nanotechnologies
e-
h+
F
-F 2
04 r
qqF
r
he
56.0
.
.. 2
2
0
22
ne
nrH
H*
e
2*
0
2
X .rm
mε.
.em
..r
r
Between the electron and the hole, there is an electrostatic attractive force given by:
r : relative dielectric constant
Using the Bohr model
eV13.6.εm
m
.r.ε2m
.emE
2
e
*
H
2
e
2*
X
*
h
*
e
* m
1
m
1
m
1
Photonic of the solids
15 15 Environmental Nanotechnologies
Eg(eV) rX (Å) EX (meV)
CdS 2.6 5.7 20.8 64
ZnO 3.2 3.7 13.2 155
TiO2 3.2 184 37.8 1.1
Photonic of the solids
16 16 Environmental Nanotechnologies
HETEROGENEOUS CATALYSIS
1) Transfer of the reactants in the fluid phase
2) Adsorption of the reactants at the surface of the catalyst
3) Reaction in the adsorbed phase
4) Desorption of the final products
5) Removal of the final products in the fluid phase
PHOTO CATALYSIS
3.1 Absorption of photons by the solid (no photochemistry)
3.2 Creation of photo-induced electrons and holes
3.3 Electron Transfer Reactions (Ionosorption, charge neutralization, radical formation, surface reactions...)
18 18 Environmental Nanotechnologies
Oxydo-reduction on the surface of irradiated TiO2
E/eV BC
BV
Electron energy E°/ENH (V)
3.2eV
+3
+2
+1
0
HO/OH- (+1.5V)
O2/HO2 (+0.1V)
+3V
-0.2V
Ox/Red A/D
19 19 Environmental Nanotechnologies
TiO2 + h {e-;h+} e- + h+
A + e- A-
Ox + e- Ox-
O2 + e- O2- superoxide anion radical
H2O2 + e- HO- + HO
O3 + e- O2 + O-
D + h+ D+
Red + h+ Red+
hydroxyl radical
H2O + h+ HO + H+
OH- + h+ HO
Oxydo-reduction on the surface of TiO2
20 20 Environmental Nanotechnologies
Photocatalysis principle
h: 400 nm
TiO2
OXIDATIONRed2 Ox2 + ne-
REDUCTIONOx1 + ne- Red1
e-
e-
e-
-
+
Conduction band
O2, acceptors
Eg 3,2 eV(anatase)
Valence band
surface
H2O, donnors
O2
-, HO
2, O
H,R
+
Formation of oxidativespecies on the surface
Degradation of the molecules present near
the surface
h: 400 nm
TiO2
OXIDATIONRed2 Ox2 + ne-
REDUCTIONOx1 + ne- Red1
e-
e-
e-
-
+
Conduction band
O2, acceptors
Eg 3,2 eV(anatase)
Valence band
surface
H2O, donnors
O2
-, HO
2, O
H,R
+
Formation of oxidativespecies on the surface
Degradation of the molecules present near
the surface
21 21 Environmental Nanotechnologies
H2S + 2 O2 SO4
2- + 2 H+
SH- + 2 O2+ SO4
2- + H+ S2- + 2 O2 SO4
2- SO3
2- + 1/2 O2 SO42-
S2O3
2- + 2 O2 + H2O 2 SO42- + 2 H+
NO2
- + 1/2 O2 NO3-
NH4
+ + 1/2 O2 + H2O NO3- + 2 H2O + 2 H+
H3PO3 + 1/2 O2 H3PO4 CN- + 1/2 O2 OCN- [ OCN- + 2 H2O CO3
2- + NH4+]
Compounds degraded by photocatalytic oxidation
Inorganic compounds Organic compounds
alkanes, alcohols, aldehydes, ketones, aromatics,…
Organic compounds + O2 ….. CO2 + H2O
except :
- CH4
- cyanuric acid C3H3N3O3
- fluoro-carbon compounds : C-F
22 22 Environmental Nanotechnologies
(A): mass of catalyst; (B): wavelength; (C): initial concentration of reactant; (D): temperature; (E): radiant flux.
m
mopt
A r
C
r = k[KC/(1+KC)]
C 0
r
EG
λ
B r
EG
80°C 20°C
D log r
Ea = Et -
aQA
Ea = Et
0
Ea = Et + aQP
1/T
r
F
r F r F
1/2
E
Influence of the different physical parameters which govern the reaction rate
23 23 Environmental Nanotechnologies
Titanium dioxide (TiO2)
Loading on earth : 0.44 % (7th element on earth)
- Ilmenite (principal mineral for Ti) oxide (TiO2,FeO,Fe2O3); 30 à 70 % of TiO2.
-Rutile (TiO2): from 93 to 96 % ; other: leucoxene (alterated ilmenite > 90 % of TiO2),
anatase (TiO2), perovskite (CaTiO3).
Application fieldsPlastics
19%
Paper industry
19%
other
2%
Paints
60%
Catalysis
Photocatalysis
Cosmetics
Pharmacy
Photovoltaîcs
24 24 Environmental Nanotechnologies
Preparation of TiO2 nanoparticles for photocatalysis
Usual precursors
- TiOSO4
- TiOCl2, TiCl4
- alkoxydes de Ti
- Ti
- TiO2
Usual synthesis methods
- Hydrolysis
- Neutralisation/calcination
- Solvothermal/Hydrothermal
- Sol/gel
- Melt salts
Three-dimensional materials (anatase, rutile, brookite…)
25 25 Environmental Nanotechnologies
The different allotropic forms (TiO2)
TiO2(R) : type Ramsdellite
-TiO2(H) : type Hollandite
AnataseRutile
TiO2(B) : type Wadsley
Brookite TiO2(II) : type a-PbO2
a a
TiO2(R) : type Ramsdellite
-TiO2(H) : type Hollandite
AnataseRutile
TiO2(B) : type Wadsley
Brookite TiO2(II) : type a-PbO2
a a
26 26 Environmental Nanotechnologies
Application fields
Photovoltaïcs, photobatteries,
Photoelectrolysis of water.
• Photoelectrochimical properties of TiO2 :
• Photocatalysis with TiO2 :
water treatment (pesticides, dyes,…)
air treatment (VOC …)
self-cleaning materials (glass, concrete,…)
28 28 Environmental Nanotechnologies
Formation mechanism of active species
TiO2 + h h+ + e-
h+ + e- N (+ énergie)
H2O H+ + OH-
OH-(aq) OH-
(ads)
OH-(ads) + h
+ OH radical hydroxyl
O2(g) O2(aq) O2 solubility at 1atm : 1mM
O2(aq) O2(ads)
O2(ads) + e- O2
- radical anion superoxyde
O2- + H+ HO2
radical hydroperoxyl
29 29 Environmental Nanotechnologies
Dismutation of hydroperoxyl radicals
2 HO2 O2 + H2O2
acido-basic equilibrium HO2/O2
-
O2- + H+ HO2
pKa=4,8 Basic medium : O2-
Acidic medium : HO2
1st case : if h254 nm
H2O2 2 OH
2nd case :
H2O2 + e- OH + OH-
Formation mechanism of active species
30 30 Environmental Nanotechnologies
HOOC-CH=CH-COOH
HOOC-CH 2 -CHOH-COOH
CH 3 -CHOH-COOH HOOC-CHOH-CHOH-COOH
HOOC-CHOH-COOH
HOOC-CH 2 -CHO
H 2 C=CH-COOH
HOOC-CHO
HOOC-CH 2 OH
HOOC-COOH
CH 3 -COOH
HCOOH
CH 3 -CO-COOH
CH 3 -CHO
CO 2
TiO 2 -UV
Reaction pathway of the photocatalytic degradation of malic acid
in contact with TiO2 at 290 nm.
malic acid
2-hydroxypropanoic acid
propanedioic acid
acetic acid
formic acid oxalic acid
formylmethanoic acid
hydroxyethanoic acid
propenoic acid
2-oxopropanoic acid
3-oxopropanoic acid
butenedioic acid (trans/cis)
acetaldehyde
(1) (2)
(3) (4)
HOOC-CH 2 -COOH
2-hydroxypropanedioic acid
2,3-dihydroxybutanedioic acid
(lactic acid)
(pyruvic acid)
(malonaldehydic acid)
(malonic acid)
(acrylic acid)
(glycolic acid)
(glyoxylic acid)
(tartaric acid)
(tartronic acid)
(fumaric/maleic acid)
a,b
a,b a,b,c
a
a,b,c
a
a
a
a
a,b,c a
b,e
identification: a: HPLC b: GC/MS c: Capillary electrophoresis d: GC e: LC/MS
c
Malic acid degradation
31 31 Environmental Nanotechnologies
O NO2
CH3
P
CH3O
CH3OS
Fenitrothion
Phosphorothioic acid O,O-dimethyl-O-(3-methyl-4-nitrophenyl) ester
(insecticide, cholinesterase inhibitor)
Photocatalytic degradation of pesticides
32 32 Environmental Nanotechnologies
TIME (MIN)
Inorganic ions formation
Disappearance of fenitrothion
A = TiO2 + UV +air ; B = TiO2 obscurité ; C= UV
O NO2
CH3
P
CH3O
CH3OS
34 34 Environmental Nanotechnologies
Dyes
N N
SO3Na
ORANGE G
O
O
OH
OH
SO3Na
ALISARIN
N N
HOOC
(H3C)2N
METHYL RED
NH2
N N
NH2
SO3NaSO3Na
N N
CONGO RED
S+
N
N(CH3)2
Cl-
(H3C)2N
METHYLENE BLUE
35 35 Environmental Nanotechnologies
Photocatalytic decolorization
Methylene blue
0min 15min 30min 55min
S+
N
N(CH3)2
Cl-
(H3C)2N
0min 15min 30min 60min 120min 180min
CONGO
RED
NH2
N N
NH2
SO3NaSO3Na
N N
36 36 Environmental Nanotechnologies
Carbon mineralization
Decolorisation does not mean that there are no more pollutants
mineralisation
decolorisation
37 37 Environmental Nanotechnologies
:
TiO2
Cellulosic
fibers
SiO2
Supported photocatalytic materials
TiO2 Nanoparticles have to be supported on porous materials to avoid filtration
38 38 Environmental Nanotechnologies
Photocatalytic reactors
Cooling
Supported photocatalyst
Stirring
Lamp Supported photocatalyst
Lamp
39 39 Environmental Nanotechnologies
Light on Earth surface
4% of the sunlight : 1 à
4 mW/cm2
Natural solar light sufficient for a significant
photocatalytic activity
40 40 Environmental Nanotechnologies
Solar photoreactors PSA (3 modules en série)
a)
b)
12
OD 48
60º
77
60 60
154
UV
Solar Collector V 1 = 108 L
pump
Tank
c)
a)
b)
12
OD 48
60º
77
60 60
154
UV
Solar Collector V 1 = 108 L
Tank
c)
UV
Solar Collector V 1 = 108 L
Tank
c)
Vtot = 250 L
Application : Water treatment (Alméria, southern Spain)
42 42 Environmental Nanotechnologies
SOLAR PHOTOCATALYSIS: « HELIO-PHOTOCATALYSIS »
Two European Programs on « Water Potabilization by Photocatalysis in Semi-Arid Countries »
Aim : Potabilization of 1m3 water per day by photocatalysis using deposited titania in a robust solar photoreactor.
AQUACAT Project Coordinator Jean-Marie HERRMANN (LACE, France) Europe (France, Spain, Portugal, Switzerland) – North Africa (Egypt, Morocco, Tunisia)
SOLWATER Project Coordinator Julian BLANCO (PSA, Spain) Europe(Spain, Portugal, France, Switzerland, Greece) – Latin America (México, Peru, Argentina)
44 44 Environmental Nanotechnologies
Photocatalysis
material
Solidphysics
Kineticsandcatalysis
Analytical science
electrochemistry
Chemical ingeneering
bv
bcE/eV
h+
e-
h>Eg
C
r = k[KC/(1+KC)]
C0
rC
r = k[KC/(1+KC)]
C0
r
HOOC-CH=CH-COOH
HOOC-CH 2 -CHOH-COOH
CH3 -CHOH-COOH HOOC-CHOH-CHOH-COOH
HOOC-CHOH-COOH
HOOC-CH 2 -CHO
H2 C=CH-COOH
HOOC-CHO
HOOC-CH 2 OH
HOOC-COOH
CH3 -COOH
HCOOH
CH3 -CO-COOH
CH3 -CHO
CO2
TiO 2 -UV
Reaction pathway of the photocatalytic degradation of malic acidin contact with TiO2 at 290 nm.
malic acid
2-hydroxypropanoic acid
propanedioic acid
acetic acid
formic acid oxalic acid
formylmethanoic acid
hydroxyethanoic acid
propenoic acid
2-oxopropanoic acid
3-oxopropanoic acid
butenedioic acid (trans/cis)
acetaldehyde
(1) (2)
(3)
(4)
HOOC-CH 2 -COOH
2-hydroxypropanedioic acid
2,3-dihydroxybutanedioic acid
(lactic acid)
(pyruvic acid)
(malonaldehydic acid)
(malonic acid)
(acrylic acid)
(glycolic acid)
(glyoxylic acid)
(tartaric acid)
(tartronic acid)
(fumaric/maleic acid)
a,b
a,b a,b,c
a
a,b,c
a
a
a
a
a,b,ca
b,e
identification:a: HPLCb: GC/MSc: Capillary electrophoresisd: GCe: LC/MS
c
HOOC-CH=CH-COOH
HOOC-CH 2 -CHOH-COOHHOOC-CH 2 -CHOH-COOH
CH3 -CHOH-COOHCH3 -CHOH-COOH HOOC-CHOH-CHOH-COOH
HOOC-CHOH-COOH
HOOC-CH 2 -CHOHOOC-CH 2 -CHO
H2 C=CH-COOHH2 C=CH-COOH
HOOC-CHO
HOOC-CH 2 OHHOOC-CH 2 OH
HOOC-COOH
CH3 -COOHCH3 -COOH
HCOOH
CH3 -CO-COOHCH3 -CO-COOH
CH3 -CHOCH3 -CHO
CO2CO2
TiO 2 -UVTiO 2 -UV
Reaction pathway of the photocatalytic degradation of malic acidin contact with TiO2 at 290 nm.
Reaction pathway of the photocatalytic degradation of malic acidin contact with TiO2 at 290 nm.
malic acid
2-hydroxypropanoic acid
propanedioic acid
acetic acid
formic acid oxalic acid
formylmethanoic acid
hydroxyethanoic acid
propenoic acid
2-oxopropanoic acid
3-oxopropanoic acid
butenedioic acid (trans/cis)
acetaldehyde
(1) (2)
(3)
(4)
HOOC-CH 2 -COOHHOOC-CH 2 -COOH
2-hydroxypropanedioic acid
2,3-dihydroxybutanedioic acid
(lactic acid)
(pyruvic acid)
(malonaldehydic acid)
(malonic acid)
(acrylic acid)
(glycolic acid)
(glyoxylic acid)
(tartaric acid)
(tartronic acid)
(fumaric/maleic acid)
a,b
a,b a,b,c
a
a,b,c
a
a
a
a
a,b,ca
b,e
identification:a: HPLCb: GC/MSc: Capillary electrophoresisd: GCe: LC/MS
identification:a: HPLCb: GC/MSc: Capillary electrophoresisd: GCe: LC/MS
c
Photocatalysis
material
Solidphysics
Kineticsandcatalysis
Analytical science
electrochemistry
Chemical ingeneering
bv
bcE/eV
h+
e-
h>Eg
C
r = k[KC/(1+KC)]
C0
rC
r = k[KC/(1+KC)]
C0
r
HOOC-CH=CH-COOH
HOOC-CH 2 -CHOH-COOH
CH3 -CHOH-COOH HOOC-CHOH-CHOH-COOH
HOOC-CHOH-COOH
HOOC-CH 2 -CHO
H2 C=CH-COOH
HOOC-CHO
HOOC-CH 2 OH
HOOC-COOH
CH3 -COOH
HCOOH
CH3 -CO-COOH
CH3 -CHO
CO2
TiO 2 -UV
Reaction pathway of the photocatalytic degradation of malic acidin contact with TiO2 at 290 nm.
malic acid
2-hydroxypropanoic acid
propanedioic acid
acetic acid
formic acid oxalic acid
formylmethanoic acid
hydroxyethanoic acid
propenoic acid
2-oxopropanoic acid
3-oxopropanoic acid
butenedioic acid (trans/cis)
acetaldehyde
(1) (2)
(3)
(4)
HOOC-CH 2 -COOH
2-hydroxypropanedioic acid
2,3-dihydroxybutanedioic acid
(lactic acid)
(pyruvic acid)
(malonaldehydic acid)
(malonic acid)
(acrylic acid)
(glycolic acid)
(glyoxylic acid)
(tartaric acid)
(tartronic acid)
(fumaric/maleic acid)
a,b
a,b a,b,c
a
a,b,c
a
a
a
a
a,b,ca
b,e
identification:a: HPLCb: GC/MSc: Capillary electrophoresisd: GCe: LC/MS
c
HOOC-CH=CH-COOH
HOOC-CH 2 -CHOH-COOHHOOC-CH 2 -CHOH-COOH
CH3 -CHOH-COOHCH3 -CHOH-COOH HOOC-CHOH-CHOH-COOH
HOOC-CHOH-COOH
HOOC-CH 2 -CHOHOOC-CH 2 -CHO
H2 C=CH-COOHH2 C=CH-COOH
HOOC-CHO
HOOC-CH 2 OHHOOC-CH 2 OH
HOOC-COOH
CH3 -COOHCH3 -COOH
HCOOH
CH3 -CO-COOHCH3 -CO-COOH
CH3 -CHOCH3 -CHO
CO2CO2
TiO 2 -UVTiO 2 -UV
Reaction pathway of the photocatalytic degradation of malic acidin contact with TiO2 at 290 nm.
Reaction pathway of the photocatalytic degradation of malic acidin contact with TiO2 at 290 nm.
malic acid
2-hydroxypropanoic acid
propanedioic acid
acetic acid
formic acid oxalic acid
formylmethanoic acid
hydroxyethanoic acid
propenoic acid
2-oxopropanoic acid
3-oxopropanoic acid
butenedioic acid (trans/cis)
acetaldehyde
(1) (2)
(3)
(4)
HOOC-CH 2 -COOHHOOC-CH 2 -COOH
2-hydroxypropanedioic acid
2,3-dihydroxybutanedioic acid
(lactic acid)
(pyruvic acid)
(malonaldehydic acid)
(malonic acid)
(acrylic acid)
(glycolic acid)
(glyoxylic acid)
(tartaric acid)
(tartronic acid)
(fumaric/maleic acid)
a,b
a,b a,b,c
a
a,b,c
a
a
a
a
a,b,ca
b,e
identification:a: HPLCb: GC/MSc: Capillary electrophoresisd: GCe: LC/MS
identification:a: HPLCb: GC/MSc: Capillary electrophoresisd: GCe: LC/MS
c
microbiology
46 46 Environmental Nanotechnologies
Treatment of VOCs
Odorous molecules
O C H O
Cancerigen molecules
aldéhyds : HCHO, CH3CHO
aromatics : BTX :benzene, toluene, xylene
nom formule origine
butadione CH3-CO-CO-CH3 beurre rance
diméthyldisulfure CH3-S-S-CH3 chou
furfural lait brûlé
acide valérique CH3-(CH2)3-COOH odeurs corporelles
2-heptanone CH3-CO-(CH2)4-CH3 fromage fort
diméthylamine (CH3)2-NH animaux morts
47 47 Environmental Nanotechnologies
Indoor air treatment for industries
Elimination of odorous nitrogen containing compounds (volatil fatty acids, mercaptans, amines). challenge: very low concentrations (g m-3).
Supported photocatalyts paper + TiO2
Gas flow : 1000 à 3000 m3/h
48 48 Environmental Nanotechnologies
Hospital, restaurants,….
Domestic applications
Bad smells in fridge
49 49 Environmental Nanotechnologies
TiO 2 TiO 2 TiO 2
binder
Activated carbon
Outdoor air treatment
Large volume of air to be treated
Coupling between photocatalysis and adsorption
51 51 Environmental Nanotechnologies
Photoelectrical effect : Superhydrophilicity
*Andrew Mills, Soo-Keun Lee, Journal of Photochemistry and Photobiology A: Chemistry 152 (2002) 233–247.
Photohydroxylation of TiO2 surface
53 53 Environmental Nanotechnologies
A. Mills et al./ Journal of Photochemistry and Photobiology A: Chemistry 160 (2003) 213-224
0 min
Evolution of the hydrophilicity as a function of the UV irradiation time
30 min
15 min
45 min
Photoelectrical effect : Superhydrophilicity
54 54 Environmental Nanotechnologies
Dirt on glass
• Composition : Urban location
• Origins :
Ori
gine
Marine
Continentale
Anthropique
Biogénique
Geochemical origin of the dirt
Marine Continental
Anthropic
Biogenic
Marine Salt (NaCl) , oceanic wind
Biogenic pollens, seeds, microbes
Continental erosion, volcano
Anthropic human activities
55 55 Environmental Nanotechnologies
Sources of organic compounds in urban environment
• Automotives and trucks : alcanes, fatty acids, PAH …
• Industries : alcanes, PAH …
• Dust : alcanes, steranes, PAH, …
• Plant pollutants : alcanes, terpenes, fatty acids …
• Domestic pollutants : PAH, alcanes …
• Cigarette smoke: nicotine, alcanes, aromatics …
56 56 Environmental Nanotechnologies
2.Superhydrophilicity: Formation of a rainwater thin film
which washes away the organic dirt.
Reduction
Oxidation Pollutants degradation at the glass surface
H2O + CO2
O2
H2O
OH + H+
UV (hυ)
O2-, HO2
TiO2
Self
-Cle
an
ing
Gla
ss
Valence band
Conduction band
Eg3,2eV (anatase)
e-
-
+
e-
e-
1.Photocatalytic
degradation
Self-cleaning properties of the glass
=
photocatalysis + superhydrophilicity
57 57 Environmental Nanotechnologies
Examples
V. Roméas et al. / New J. Chem., 23 (1999) 365-373
A. Mills et al./ Journal of Photochemistry and Photobiology A:
Chemistry 160 (2003) 213-224
ActivTM
58 58 Environmental Nanotechnologies
Previous results on Self-Cleaning Glasses
Palmitic acid chosen as a model of fatty acid responsible for stains on glasses Rate of disappearance : 0.6 µmol/h
0
0,5
1
1,5
2
0 2 4 6 8 10 12
t (h)
ac
ide
pa
lmit
iqu
e (
mg
) .
exp 1
exp 2
59 59 Environmental Nanotechnologies
Disappearance rate of CH2 and CH3
• FTIR spectra at different irradiation times :
• Degradation curves : rate expressed in cm-1 min-1
• Signification of the unit ? FTIR areas/min … thickness/min
2979,4 2960 2920 2880 2840 2806,3
0,0377
0,045
0,050
0,055
0,060
0,065
0,070
0,075
0,080
0,085
0,090
0,095
0,100
0,1030
cm-1
A
t0
t + 10’ UV
t + 20’ UV
t + 30’ UV
t + 60’ UV
2979,4 2960 2920 2880 2840 2806,3
0,0377
0,045
0,050
0,055
0,060
0,065
0,070
0,075
0,080
0,085
0,090
0,095
0,100
0,1030
cm-1
A
t0
t + 10’ UV
t + 20’ UV
t + 30’ UV
t + 60’ UV
2980 2960 2920 2880 2840 2800
(cm-1)
% A
bs.
2979,4 2960 2920 2880 2840 2806,3
0,0377
0,045
0,050
0,055
0,060
0,065
0,070
0,075
0,080
0,085
0,090
0,095
0,100
0,1030
cm-1
A
t0
t + 10’ UV
t + 20’ UV
t + 30’ UV
t + 60’ UV
2979,4 2960 2920 2880 2840 2806,3
0,0377
0,045
0,050
0,055
0,060
0,065
0,070
0,075
0,080
0,085
0,090
0,095
0,100
0,1030
cm-1
A
t0
t + 10’ UV
t + 20’ UV
t + 30’ UV
t + 60’ UV
2980 2960 2920 2880 2840 2800
(cm-1)
% A
bs.
0,0
0,5
1,0
1,5
2,0
0 10 20 30 40 50 60
Temps d'irradiation UV (min)
Air
e A
S F
TIR
(cm
-1)
Irradiation time (min) F
TIR
SA
are
a
60 60 Environmental Nanotechnologies
alkanes alcohols aldehydes ketones acids
C1 G P,G
C2 G P,G
C3 G G G
C4 G G
C5 G G
C6 G G
C7 G G G G
C8 G G G G
C9 G G P,G
C10 G G P,G
C11 G G P,G
C12 G G P,G
C13 G G G
C14 G G P
C15 G
Photocatalytic degradation of palmitic acid
Identification of several by-products
61 61 Environmental Nanotechnologies
SGG BIOCLEAN® Ordinary float glass photocatalytic self-cleaning glass
64 64 Environmental Nanotechnologies
Self-cleaning concrete/cement
Dives in Misericordia church inRome Police building in Bordeaux
« Cité des Arts et de la musique » in Chambéry
Air France Aéroport Headquarter Roissy Charles de Gaulle
65 65 Environmental Nanotechnologies
The Twelve Principles of Green Chemistry*
* Anastas, P.T.; Warner, J.C.; Green Chemistry: Theory and Practice, Oxford University Press:
New York, 1998, p.30. By permission of Oxford University Press
1. PreventionIt is better to prevent waste than to treat or clean up waste afetr it has been created
2. Atom EconomySynthetic methods should be designed to maximize the incorporation of all materials used in the processinto final product
3. Less Hazardous Chemical SynthesesWherever practicable, synthetic methods should be designed to use and generate substances that possesslittle or no toxicity to human health and environment
4. Designing Safer ChemicalsChemical products should be designed to effect their desired function while minimizing their toxicity
5. Safer Solvents and AuxiliariesThe use of auxiliary substances (e.g., solvents, separation agents, etc.) should be made unnecessarywherever possible and innocuous when used.
6. Design for Energy EfficiencyEnergy requirements of chemical processes should be recognize for their environmental and economicimpacts and should be minimized. If possible, synthetic methods should be conducted at ambienttemperature and pressure
66 66 Environmental Nanotechnologies
The Twelve Principles of Green Chemistry*
7. Use Of Renewable FeedstocksA raw material or feedstock should be renewable rather than depleting whenever technically and economicallypracticable.
8. Reduce DerivativesUnnecessary derivatization (use of blocking groups, protection/deprotection, temporary modification ofphysical/chemical processes) should be minimized or avoided if possible, because such steps require additionalreagents and can generate waste
9. CatalysisCatalytic reagents (as selective as possible) are superior to stoichiometric reagents
10. Design for degradationChemical products should be designed so that at the end o ftheir function they break down into innocuousdegradation products and do not persist in the environment
11. Real-time analysis for Pollution PreventionAnalytical methodologies need to be further developed to allow for real-time, in-process monitoring and control prior to the formation of hazardous substances
12.Inherently Safer Chemistry for Accident Prevention
Substances and the form of a substance used in a chemical process should be chosen to minimize the potentialfor chemical accidents, including releases, expolsions, and fires
* Anastas, P.T.; Warner, J.C.; Green Chemistry: Theory and Practice, Oxford University Press: New
York, 1998, p.30. By permission of Oxford University Press