catalytic purification of ... - kokkola material week · kokkola material week • 14th november...
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Laboratory for Environmental Sciences and EngineeringNational Institute of Chemistry, Ljubljana, Slovenia
Catalytic purification of industrial wastewaters
Kokkola Material Week • 14th November 2013
Albin Pintar
Water
to reduce the influence of a variety of pollutants on aquatic environment
life quality (drinking water)
water reuse Energy
to decrease the dependence on fossil fuels
Motivation
Integrated approach to water pollution prevention
COD, BOD5, TOCENERGY BALANCE
CATALYTICDECARBOXYLATION
ADVANCED OXIDATION PROCESSES
ANAEROBIC MICROBIALDIGESTION
Purified water
H2 and/or CH4 richgas mixtures Biogas
Wastewaters Spent activated sludge
Conventional wastewater treatments involve mechanical, biological, physical and chemical processes.
Insufficient treatment of synthetic organic compounds that are either non-biodegradable or toxic.
Introduction of so-called Advanced Oxidation Processes (AOPs) appear to be a promising field of study due to the effective complete mineralization of organic contaminants under mild conditions.
Organic contaminants CO2 + H2O + RCOOH
Conventional wastewater treatment
Advanced Oxidation Processes (AOPs) are chemical oxidation techniques able to produce in-situ reactive free radicals, mainly hydroxyl radicals (HO·) by means of different reacting systems.
HO· is a non selective oxidant that is able to oxidize a wide range of organic molecules.
• Catalytic wet air oxidation (CWAO)• Heterogeneous photocatalysis• Fenton oxidation• Ozonation • Ultrasound oxidation
Advanced Oxidation Processes (AOPs)
... is a liquid-phase reaction between organic material dissolved in water and oxygen
Operating conditions: T = 453 – 588 K, P = 20 – 150 bar
oxidation of organic compounds into CO2 and H2O along withsimpler forms, which are biodegradable
The efficiency of aqueous-phase oxidation can be largely improved by the use of catalysts.
Key points to be solved:
Stability of heterogeneous catalysts
Recycling of homogeneous catalysts
Wet-air oxidation (WAO)
Aqueous BPA sample + O2
CO2 + H2O + RCOOH
Trickle-bed reactorT = 130 - 250 °CP = 10 – 50 bar
catalyst↓ reaction conditions ↑ oxidation capacity↓ reacton time↓ operating costs
Microactivity reference unit
Catalytic wet-air oxidation (CWAO)Catalytic C
Schematic drawing of a simple process for catalytic wet-air oxidation.
CWAO process
PURIFIED WATER
PUMP
GAS
SEPARATOR
TRICKLE-BEDREACTORHEAT
EXCHANGER
WASTEWATER
PREHEATER
AIR
• bacteria Vibrio fischeri [ISO 11348-2, 2007]
• crustacean Daphnia magna[ISO 6341, 1996]
• fish embryos Danio rerio[ISO 15088, 2007]
TOXICITY TESTS
YES ASSAYEstrogenicity determination
• Genetically modified yeast strain Saccharomyces cerevisiae
• SPE (Solid Phase Extraction) with methanol
[ ]blanksamplesample nmAnmAnmAEAactivityasegalactosid )620()620()575()( −−=−β
100(%) ×−−
=blanksampleinitial
blanksampletreated
EAEA
EAEAREA
The following issues should be addressed:
• catalyst stability in hydrothermal operating conditions (leaching of the active ingredient material into the liquid-phase; sintering of the support; agglomeration and/or recrystallization of the active phase)
• coking of the catalyst surface
• catalyst poisoning (e.g., by means of CO evolution)
Development of a catalytic wet-air oxidation process
Catalyst ApplicationActive phase CarrierCu alumina phenol, p-cresolCu alumina, silica chlorophenolsCu-Zn alumina, silica phenolsCu-Mg-La Zn aluminate acetic acidMn alumina phenolMn SR 115 chlorophenolsMn-Ce none poly(ethyleneglycol)Mn-Zn-Cr none industrial wastesCu-Co-Ti-Al cement phenolCo none alcohols, amines, etc.Co-Bi none acetic acidCo-Ce none ammoniaFe silica chlorophenolsRu cerium oxide alcohols, phenol, etc.Ru cerium oxide acetic acidRu titania-zirconia industrial wastesRu-Rh alumina wet oxidized sludgePt titania phenolPt-Pd titania-zirconia industrial wastesPt-Pd-Ce alumina black liquorRu titania black liquor
Summary of reported heterogeneous CWAO research
Heterogeneous photocatalysis
Light source: • UV lamp• Halogen lamp Catalyst suspended or immobilized
Due to the nonstoichiometric nature of these solids, their compositions (appearance of different point defects) depend on oxygen partial pressure.
RANGE I – low oxygen concentration fixed-bed oxygen vacancies and conduction-band electrons reactor
RANGE II – moderate oxygen concentration either electrons or holes
RANGE III – high oxygen concentration trickle-bed cation vacancies and valence-band holes reactor
Hydroxyl hydrogen radical abstraction is the rate limiting step. ∴ Range III advantageous.
Electronics of (mixed) metal oxides
A. Pintar, M. Besson and P. Gallezot, Appl. Catal. B, 2001
Initial characterization of paper pulp effluentsInitial characterization of paper pulp effluents
Species in solution D0 effluent E1 effluentColour dark yellow dark brownInitial pH (/) 2.9 10.0IC (mg L-1) 3.9 205TOC (mg L-1) 665 1380COD (g L-1) 1.7 3.7Total solids (g L-1) 4.0 5.6AOX (mg L-1) 24.1 19.6Na+ (g L-1) 0.9 1.3K+ (mg L-1) 29 10NH4+ (mg L-1) < 0.2 < 0.2Ca2+ (mg L-1) 91 22Mg2+ (mg L-1) 19 5Cl- (mg L-1) 534 386NO3- (mg L-1) 14 21NO2- (mg L-1) < 0.02 < 0.02SO42- (mg L-1) 1460 681Stotal (mg L-1) 547 221PO43- (mg L-1) < 5 65
Change of colour of a concentrated alkaline (E1) bleach plant effluent (TOC0: 13 g/l, pH0: 11) obtained during the catalytic wet-air oxidation carried out in the presence of a Ru/TiO2 catalyst. T: 463 K, p(O2): 7.4 bar, ccat.: 5 g/l.
Oxidation of E1 bleach plant effluent in a slurry reactor
reaction time
TOC conversion as a function of time on stream, obtained in the trickle-bed reactor packed with a Ru(3 wt. %)/TiO2 catalyst. Feed solution: (a) D0 effluent; (b) E1 effluent.
Residence time of the liquid-phasein the catalytic bed: 0.6 min
A. Pintar, M. Besson and P. Gallezot, Appl. Catal. B, 2001
0
20
40
60
80
100
0 30 60 90 120 150
TO
Cc
on
ver
sio
n/%
mcat.
: 12.7 g Ru(3 wt. %)/TiO2
cTOC,feed
: 1138 mg/L
a
0
20
40
60
80
100
0 20 40 60 80 100
time on stream/htime on stream/h
mcat.
: 12.7 g Ru(3 wt. %)/TiO2
cTOC,feed
: 1331mg/L
b
TOC conversion as a function of time, obtained over a Ru(3 wt. %)/TiO2 catalyst in the batch-recycle reactor charged with: (a) D0-P1 solution; (b) E1-P1 solution.
A. Pintar, M. Besson and P. Gallezot, Appl. Catal. B, 2001
0
20
40
60
80
100
0 20 40 60 80 100
mcat.
: 12.7g Ru(3 wt. %)/TiO2
cTOC,0
: 131 mg/L
a
time/h time/h
0
20
40
60
80
100
0 20 40 60 80 100
mcat.
: 12.7 g Ru(3 wt. %)/TiO2
cTOC,0
: 156 mg/L
b
CWAO over Ru(3.0 wt. %)/TiO2
Specific surface area (SBET), total pore volume (Vpore), average pore width (dpore) and ruthenium dispersion (DRu) of fresh Ru/TiO2 catalyst samples prepared by the incipient-wetness impregnation method and reduced directly in H2 flow (1 h, 573 K) without previous calcination.
Sample SBET,
m2/g
Vpore,
cm3/g
dpore,
Å
DRu,
%
TiO2 51 0.364 282 -Ru(3.0 wt. %)/TiO2 50 0.344 274 5.4
100 nm
Ru
17β-estradiol (E2)
17β-Estradiol (E2)
• 17β-estradiol (E2) is a natural estrogen hormone produced by human body, mostly women (up to 100 μg per day), but in small amounts also in men (up to 25 μg per day). It is excreted from human body via urine into sewage systems.
• Untreated wastewaters and effluents from wastewater treatment plants are the main sources of surface waters pollution. E2 has been reported to be responsible for around 90 % of the estrogenicity of municipal wastewaters.
• E2 is estrogenically active and recognized as an emerging contaminant. It has been shown to elicit negative effects on the endocrine systems of humans and wildlife at very low concentrations.
evaluation of E2 conversion efficiency by estrogenicity test (YES assay)
Cover picture (Acta Chimica Slovenica,59 (2) 2012).
HO
H H
H
CH3
OH
RESULTS
17β-Estradiol (E2)
E2 conversion as a function of time on stream obtained over various catalysts. p(O2): 10.0 bar, Φvol,L: 0.5 ml/min, c(E2)feed: 0.272 mg/l.
SiC TiO2 Ru/TiO2
230 °C200 °C 230 °C200 °C 230 °C200 °C
~ E2 conversion
M. Bistan et al., Catalysis Communications 22 (2012) 74–78
HO
H H
H
CH3
OH
1.0-9.59.5-23.25
23.25-31.532.5-47.75
47.75-56.056-71.75
71.75-79.250
20
40
60
80
100
E2
con
vers
ion
(z=L
),%
Time on stream, h
503 K473 K
0.5-8.758.75-23.25
23.25-31.532.5-47.0
47.0-55.555.5-68.0
68.0-76.250
20
40
60
80
100
E2
con
vers
ion
(z=
L),%
Time on stream, h
503 K473 K
1.0-9.259.25-23.0
23.0-31.532.5-47.0
47.0-55.555.5-68.25
68.25-76.250
20
40
60
80
100
E2
con
vers
ion
(z=
L),%
Time on stream, h
503 K473 K
RESULTS
17β-Estradiol (E2)
Conversion and estrogenicity (REA) of E2 aqueous samples treated by means of CWAO process in the presence of various solids.
Sample Conversion,%
Remained E2,μg/l
REA,%
E2, feed solution / 272 100
blank (ultrapure water) / / 0
1a: E2, SiC, T=473 K 70.0±6.0 81.6 95.2±2.5
1b: E2, SiC, T=503 K 90.0±5.6 27.2 90.4±3.5
2a: E2, TiO2, T=473 K 93.0±2.2 19.0 100
2b: E2, TiO2, T=503 K 100 0 0
3a: E2, Ru(3.0 wt. %)/TiO2, T=473 K 100 0 0
3b: E2, Ru(3.0 wt. %)/TiO2, T=503 K 100 0 0
~ E2 conversion and estrogenicity
M. Bistan et al., Catalysis Communications 22 (2012) 74–78
HO
H H
H
CH3
OH
Bisphenol A (BPA)
• key monomer in production of polycarbonate plastic and epoxy resins• frequently present in industrial wastewaters and landfill leachates (up to 17 mg/l)• organic pollutant• toxic to bacteria, algae, crustacean and fish• estrogenic activity
evaluation of BPA conversion efficiency by toxicity tests (bacteria, crustacean water flea and fish) and estrogenicity test (YES assay)
BPA conversion as a function of time on stream obtained over various catalysts at (a) 473 and (b) 503 K. p(O2): 10.0 bar, Φvol,L: 0.5 ml/min, c(BPA)feed: 20.0 mg/l.
(a)
(b)
Temperature, K 473 503 mcat, g 3.0 Ptot, bar 25.5 38.0 p(O2), bar 10.0
Φ vol,L, ml/min 0.5 L, kg m-2 s-1 0.134 0.132 Φ vol,G, ml/min 60 G, kg m-2 s-1 0.357 0.500
tres,L, min 0.24 0.23
RESULTS
230 °C
200 °C
~ BPA conversion
M. Bistan et al., Ind. Eng. Chem. Res. 2012, 51, 8826–8834
0 10 20 30 40 500
20
40
60
80
100
SiC TiO
2
TiO2, HC reactor
Ru/TiO2
BP
A c
on
ve
rsio
n,
%
Time on stream, h
T: 473 K
0 10 20 30 40 500
20
40
60
80
100
SiC TiO
2
Ru/TiO2
BP
A c
on
ve
rsio
n,
%
Time on stream, h
T: 503 K
TOC conversion as a function of temperature obtained over various catalysts during CWAO of BPA. p(O2): 10.0 bar, Φvol,L: 0.5 ml/min, c(BPA)feed: 20.0 mg/l.
RESULTS ~ TOC conversion
M. Bistan et al., Ind. Eng. Chem. Res. 2012, 51, 8826–8834
Carbon content (measured by means of CHNS analysis) on the surface of fresh and spent catalyst samples used in the CWAO process of BPA. p(O2): 10.0 bar, Φvol,L: 0.5 ml/min, c(BPA)feed: 20.0 mg/l.
Catalyst sample Carbon content, wt. %
SiC fresh 0.03
spenta 0.02
TiO2 fresh 0.11
spent 0.13
spent, HC reactor 0.09
3% Ru/TiO2 fresh 0.07
spent 0.04 aAfter CWAO of BPA carried out at both 473 and 503 K.
RESULTS ~ carbon deposits
M. Bistan et al., Ind. Eng. Chem. Res. 2012, 51, 8826–8834
RESULTS – Toxicity tests
Sample BPA conversion
(%)
Vibrio fischeri, Luminiscence inhibition (%)
Danio rerio, Mortality
(%)
REA (%)
1: BPA, initial sample / 89 80 100 2a: BPA, SiC, 473 K 39 42 100 100 2b: BPA, SiC, 503 K 59 11 100 100 3a: BPA, TiO2, 473 K 88 34 80 0 3b: BPA, TiO2, 503 K 96 0 100 0 4a: BPA, Ru/TiO2, 473 K 100 27 10 0 4b: BPA, Ru/TiO2, 503 K 100 0 0 0
M. Bistan et al., Ind. Eng. Chem. Res. 2012, 51, 8826–8834
1 2a 2b 3a 3b 4a 4b0
20
40
60
80
100
Va
lue
(%
)
Sample
Luminiscence inhibition, V. fischeri
Lethal effects, D. rerio
Relative estrogenic activity
A. Pintar, M. Besson, P. Gallezot, Appl. Catal. B 30 (2001) 123.
Our latest approach: catalyst based on bare TiO2
Moderate catalytic activity in the CWAO process
Inexpensive and environmentally innocuous material
Time necessary to achieve 60 % abatement of TOC in effluents D0 and E1 as a function of titania or zirconia oxides (a), or supported ruthenium catalysts (b).
+ 10 M NaOH
+ H+ or H3O++ H+ or H3O+
(nanotubes)
A2Ti2O5·H2O, A2Ti3O7 or A2Ti4O9·H2O(A = Na)
H2Ti2O5·H2O
TiO2 nanopowder 110 – 150 °C
∆
(anatase, rutile)
Synthesis:
TiO2 nanotubes as a catalyst
Catalyst Crystallite size (nm) BET (m2/g) Vpore (cm3/g)NT / 383 1.41
NT_300 / 348 1.38NT_400 11 165 1.07NT_500 16 117 0.67NT_600 19 95 0.53NT_700 36 49 0.26
(300, 400, 500, 600, 700 °C)
Temperature dependence of TiO2 nanotube (NT) structure and particle size
10 20 30 40 50 60 70 80 90
700 °C
600 °C
500 °C
400 °C
(10
1)
Inte
nsi
ty (
a.u
.)
2θ (CuKα )
NT4 NT4_300 NT4_400 NT4_500 NT4_600 NT4_700
(20
0)
RT300 °C
700°C
• Particle size ↑• BET surface area↓
Temperature dependence of TiO2 nanotube morphology
0 5 10 15 20 25 30 35 40
50
60
70
80
90
100
NT4 NT4_300 NT4_400 NT4_500 NT4_600 NT4_700 P25
x (B
PA
) ou
tlet (
%)
Time on stream (h)
a)
End-product solutions high-performance liquid chromatography (HPLC)
c(BPA)0 = 10 mg/L mcat. = 0.3 gØvol.L = 0.5 ml/min T = 473 KØvol.G = 60 ml/min p(O2) = 10.0 barSuperficial gas flow rate (G) = 0.357 kg m-2 s-1 Superficial liquid flow rate (L) = 0.134 kg m-2 s-1
CWAO experiments
5 -10 times higher activity than commercial TiO2 (Degussa extrudates)
over titanate nanotube based catalystsBisphenol A
Primary steps in the catalytic liquid phase oxidation mechanism:
A structure-reactivity investigation shows that the rate-determining step is activation of an organic molecule by valence-band holes; the reaction occurs via a stepwise oxidation mechanism.
ELECTRONICS OF (MIXED) METAL OXIDESDue to the nonstoichiometric nature of these solids, their compositions (appearance of different point defects) depend on oxygen partial pressure.
RANGE I – low oxygen concentration fixed-bed oxygen vacancies and conduction-band electrons reactor
RANGE II – moderate oxygen concentrationeither electrons or holes
RANGE III – high oxygen concentration trickle-bedcation vacancies and valence-band holes reactor
Hydroxyl hydrogen radical abstraction is the rate limiting step. Range III is advantageous.
separation of charges by heat supply
The number of active sites (valence-band holes) increases with time (due to high oxygen concentration/pressure), until dynamic equilibrium between phases in the catalyst layer is established (~ 20 h).
0 5 10 15 20 25 30 35 40
50
60
70
80
90
100
NT4 NT4_300 NT4_400 NT4_500 NT4_600 NT4_700 P25
x (B
PA
) ou
tlet (
%)
Time on stream (h)
a)
Catalyst TOC conversion (%)
TiO2_RT 42
TiO2_300 64
TiO2_400 61
TiO2_500 58
TiO2_600 69
TiO2_700 47
CWAO experimentsover titanate nanotube
based catalysts
40
300 ml of 10 mg/l BPA solution, liquid flow
rate: 0.5 ml/min
0.3 g of catalyst (S4_600)
CARBON CONTENT ON CATALYST:
0.17 wt. %
(Carbon content on catalyst S4_600 before CWAO: 0.17 wt. %)
Introduction of recycle
acetic acid, formic acid and p-hydroxyacetophenone (p-HAP)
Sequential and continuous CWAO (a) / BR (b) system
0 100 200 300 400 500 600 7000
1
2
3
4
0
20
40
60
80
100
Time, min
TOC,
mg
L-1
X, %
() acetic acid () formic acid () p-HAP() TOC
Bioassays – toxicity and estrogenicity evaluation
Zebrafish Danio rerioCrustacea Daphnia magna Algae Desmodesmus subspicatus Bacteria Vibrio fischeri
Bioassays – toxicity and estrogenicity evaluation
210 °C
Schematic drawing of a simple process for catalytic wet-air oxidation.
CWAO process
PURIFIED WATER
PUMP
GAS
SEPARATOR
TRICKLE-BEDREACTORHEAT
EXCHANGER
WASTEWATER
PREHEATER
AIR
2
A. Pintar and J. Levec, J. Catal., 1992
Phenol and TOC conversion as a function of time on stream obtained over (a) Ru(1.5 wt. %)/TiO2 and (b) Ru(3.0 wt. %)/TiO2 catalysts. p(O2): 10.0 bar, Φvol,L: 1.0 ml/min, c(C6H5OH)feed: 1.0 g/l.
(a)
(b)
0 20 40 60 800.0
0.2
0.4
0.6
0.8
1.0
0.0
0.2
0.4
0.6
0.8
1.0
x(T
OC
) ou
tle
t, /
Time on stream, h
x(C
6H5O
H) o
utl
et,
/
IIIIIIIVV
T [K]:453433453473493
I II III IV V
0 20 40 60 80 100 1200.0
0.2
0.4
0.6
0.8
1.0
0.0
0.2
0.4
0.6
0.8
1.0IVIIIII
x(T
OC
) ou
tle
t, /
Time on stream, h
I
x(C
6H5O
H) o
utl
et,
/
T [K]:453483493473
IIIIIIIV
DISAPPEARANCE RATE EXPRESSION
”Liquid-full” fixed-bed reactor
• based on the Langmuir-Hinshelwood kinetic formulation• equilibrium model pollutant and dissociative oxygen adsorption processes
on different active sites
2 2
* 1/ 2 1/ 2poll. O poll. O
poll.poll. poll.
Based on the Langmuir-HinsheEquilibrium model pollutant and dissociative oxygen
ads
lwood kinetic formulation
or
k K K C C r
1 K C=
+
ption processes on different active sites
(-rpoll.)exp.·106, mol/(gcat.·h)
Experimental vs. predicted acetic acidconcentration-time profiles - Ru/TiO2
(Kraft bleach plant effluent – Pintar et al., Appl. Catal. B, 2004)
Experimental vs. predictedTOC concentration-time profiles - Ru/TiO2
(Kraft bleach plant effluent – Pintar et al., Appl. Catal. B, 2004)
Taylored made heterogeneous catalysts for enhanced removal of emerging pollutants
Nanostructured catalysts (new synthesis routes)
Catalyst stability in hydrothermal conditions
Bioassays for determination of toxicity and estrogenicity
Production of energy and value-added chemicals from organically polluted water
Take home messages
Members of theLaboratory for Environmental Sciences and Engineering at NIC
Slovenian Research AgencyCentre of Excellence “Low Carbon Technologies“
Competence Center “Sustainable and Innovative Civil Engineering“
Acknowledgements
