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1
AdOxTM
--a Kinetic Model for the Hydrogen Peroxide / UV Process
Ke Li
Shumin Hu
John C. Crittenden
David W. Hand
David R. Hokanson
Portions Presented at AOTs-6 The Sixth Annual Conference onAdvanced Oxidation Technologies for Water and Air Remediation
London, Ontario Canada, June 26-30, 2000
Copyright © 2000-2002. Michigan Technological University. All Rights Reserved.
2
Outline
•AOP Mechanism Behind the Model•Model Validation
•Example Applications
•Some Important Features
•Conclusions
•Looking Forward ...
•Objectives of AdOxTM
3
Objectives of AdOxTM
Understand the chemistry of AOP process Assess the preliminary design and feasibility of
using advanced oxidation processes Plan pilot plant studies and interpret the results Predict the effect of operational parameters and
provide key parameters for process design Trace the destruction of contaminants and the
formation of byproducts, provide valuable information for mechanism study of AOP
4
Outline
•Model Validation
•Example Applications
•Some Important Features
•Conclusions
•Looking Forward ...
•Objectives of AdOxTM
•AOP Mechanism Behind the Model
5
• Photolysis of H2O2:
–Initiation: H2O2 / HO2
- + hv 2HO
–Propagation:H2O2 / HO2
- + HO H2O / OH- + HO2
H2O2 + HO2 / O2
- HO + H2O / OH- + O2
–Termination:HO + HO H2O2
HO + HO2 / O2
- H2O / OH- + O2
HO2 + HO2
/ O2- H2O2 / HO2
- + O2
AOP Mechanism Behind The Model
The 44 reactions considered in the model include the most comprehensive mechanism:
6
• Reactions of organic compound R:R + hv Products
R+ HO Products
• Inorganic Scavengers:HO + CO3
2- / HCO3- CO3
-+OH- / H2O
HO + HPO42- HPO4
- + OH-
• Direct photolysis of target compound– rUV, R1 = -R1I0 fR1(1-e-A)
–A=2.303b ( H2O2 CH2O2 + R1 CR1 + R2 CR2 + S CS + HO2- CHO2-)
– fR1 = 2.303 b R1 cR1 /A
AOP Mechanism Behind The Model
7
• Pseudo-steady-state is not assumed
• pH variation is considered• The influence of Background Organic
Matter is considered:
– absorption of UV light (s) and its influence on the photolysis of target compound and H2O2
BOM + hv – scavenging of hydroxyl radicals
HO + BOM
AOP Mechanism Behind The Model
8
Outline
•AOP Mechanism Behind the Model
•Example Applications
•Some Important Features
•Conclusions
•Looking Forward ...
•Objectives of AdOxTM
•Model Validation
9
Model Validation
The model was validated by comparing model predictions to the following experiments:
• 1,2-dibromo-3-chloropropane (DBCP) in a complete mixed batch reactor (CMBR) (Glaze and Kang, 1989)
• 1-chlorobutane (BuCl) in complete mixed flow reactor (CMFR)
(Liao and Gurol, 1995)
10
Model Validation - Relationship between [H2O2]0 and DBCP pseudo-first-order rate
constant in a CMBR, CT=4 mM, I0=1.04E-6 einsteins/L-s
120
0
20
40
60
80
100
0 1 2 3 4 5 6 7
[H 2O2]0, mM
k 0, D
BC
P, (
10-5
s-1
)
experimental resultAdOx prediction
Glaze et al.'s model prediction
11Fluka Humic Acid as DOC, mg/L
Norm
alized
Con
cen
trati
on
, C
e/C
o
0
0.2
0.4
0.6
0.8
1
0 2 4 6 8 10 12 14
H2O2 , experimental result
BuCl, experimental result
AdOx prediction
Liao et al. 's model prediction
Model Validation - Effect of Humic Acid on BuCl degradation in a CMFR ( [H2O2]0 = 284
mM, [BuCl]0 = 8 mM, t = 7.76 min, CT,CO3 = 4 mM,
pH=7.6, I0 = 2.46 10-4 einsteins/L-min
12
Outline
•AOP Mechanism Behind the Model•Model Validation
•Example Applications
•Conclusions
•Looking Forward ...
•Objectives of AdOxTM
•Some Important Features
13
Important Features of AdOxTM
1.0• Model Various Reactor Configurations:
– Completely Mixed Batch Reactor (CMBR)– Completely Mixed Flow Reactor (CMFR)
Completely Mixed Flow Reactor (CMFR)
Completely Mixed Batch Reactor (CMBR)
Q,
C in VR
C e
Q, C e
dCdt ao C a1a (C a r )
(Governing Equation)
V RC e
dC adt
ra (Governing Equation)
14
Features of Current Version AdOxTM 1.0
–Tanks-In-Series (TIS or CMFRs)
– Plug Flow Reactor (PFR)
– Real Reactor (Describe non-ideal mixing with a tanks-in-series model.)
Q,
Cin
VR
Cn
VR
C1
Q,
C1
Q,
Cn-1
Q,
C nR
Cn-1
V
Q,
Cn-2
Q,
Cn-1
n-CMFR:
15
Important Features of AdOxTM
1.0
• Dynamically model multi-component contaminant mixtures (up to 10).
• Model multi-chromatic light sources
(up to 100 wavelength)
• Determine Optimum Operational Parameters:
– Optimum H2O2 Dosage
– UV Light Intensity
– Hydraulic Retention Time
16
Important Features of AdOxTM
1.0
• Determine the influence of water quality :– Alkalinity (Total Inorganic Carbon)– pH
• Includes a database of more than 600 compounds including second-order hydroxyl-radical rate constants
17
Some Important Features• Modeling Different Reactor Configurations
18
Some Important Features• Modeling Multi-chromatic (up to 100) Light Sources
19
Some Important Features• Dye Study Analysis for Tanks-In-Series Model
20
Some Important Features• Database of Second-Order Hydroxyl-Radical
Rate Constants
21
Selection of Optimum [H2O2]0/[DBCP]0 as a function of
Water Quality Parameters
0
50
100
150
200
250
300
350
0 300 600 900 1200 1500[H2O2]0/[DBCP]0
k 0,
DB
CP,
(10-5
s-1)
Io=1.04e-6eins./l-s, TIC=0.01mM, pH7.64
Io=1.04e-6eins./l-s, TIC=0.1mM, pH8.1
Io=1.04e-6eins./l-s, TIC=4mM, pH6.4
Io=1.30e-6eins./l-s, TIC=4mM, pH8.4
Io=1.04e-6eins/l-s, TIC=4mM, pH8.4
Io=0.52e-6eins./l-s, TIC=4mM, pH8.4
22
Influence of CT,CO3 on the pseudo-first-order rate
constant of DBCP and H2O2 ([H2O2]0=1.00 mM, I0
=1.04X10-6 eins./L.s,CTIC=4mM)
0
50
100
150
200
250
300
0 1 2 3 4CT,CO3, mM
k0, D
BCP, o
r k 0
, H
2O
2, (
10-5
s-1
) DBCP, experimental resultDBCP, AdOx prediction
H2O2, AdOx prediction
23
Impact of CT,CO3 on EE/O for the Degradation of DBCP ([H2O2]0=1.00 mM, I0 =1.04X10-6 eins./L.s, CTIC=4mM,
pH=7~8.4)
0
1
2
3
4
5
0 1 2 3 4 5CT,CO3 (mM)
EE/O
(Kw
h/K
gal
lon-o
rder
)
EE/O, experiment results
EE/O, AdOx prediction
24
Impact of pH on Degradation Rate of DBCP and H2O2 (I0 = 1.0410-6 eins./L-s;[H2O2]0 = 1.00mM; CTIC = 4
mM)
0
50
100
150
200
250
300
5 6 7 8 9 10 11pH
k0, D
BCP, o
r k
0, H
2O
2, (
10
-5 s
-1) DBCP, experimental result
DBCP, AdOx prediction
H2O2, AdOx prediction
25
Impact of pH on EE/O for the DBCP Degradation (I0 = 1.0410-6 eins./L-s; [H2O2]0 = 1.00mM; CTIC = 4
mM)
0
2
4
6
8
10
12
14
16
18
5 6 7 8 9 10 11pH
EE
/O(K
wh/
Kga
llon-
orde
r)
EE/O, experiment results
EE/O, AdOx prediction
26
Outline
•Background
•AOP Mechanism Behind the Model•Model Validation
•Example Applications
•Some Important Features
•Conclusions
•Looking Forward ...
•Objectives of AdOxTM
27
Electrical Energy per Order (EE/O)– The electrical energy (in kilowatt hours)
required to reduce the concentration of a pollutant by one order of magnitude for 1000 U.S. gallons of water. For a CMBR:
EE / OP (t / 3600) 3785
V log(C / C )
2.42P
VkKwh / Kgallon order
0 e
0
( )
Example Applications
28
3
0
0.5
1
1.5
2
2.5
0 5 10 15 20[H2O2]0, (mg/L)
•[H3C2Cl]0=10g/L=1.610-7M=0.16M•TOC = 5 mg/L •TIC = 8.0 mM•pH 7.0•I0 = 1.010-6 eins./L-s•Optical length L = 7.5 cm•K HO and NOM = 2.0104 (mg/L)-1s-1
•The UV-light absorption and direct photolysis of vinyl chloride are ignored
Example Application I - Predicted Energy Requirement for an Influent Vinyl Chloride
Concentration of 10 g/L(Treatment Objective=2g/L)
EE/O
(Kw
-hou
r/K
gal-
Ord
er)
29
EE/O
(Kw
-hou
r/K
gal-
Ord
er)
0
3
6
9
0 20 40 60 80
[H2O2]0, (mg/L)
•[TCE]0=200g/L=1.52M=1.5210-6 M•TOC = 5 mg/L•TIC = 8.0 mM•pH 7.0•I0 = 1.010-6 eins./L-s•Optical length L = 7.5 cm•K HO and NOM = 2.0104 (mg/L)-1s-1
TCE=10M-1 cm-1, the direct photolysis of TCE is ignored.
Example Application II - Predicted Energy Requirement for an Influent TCE Concentration
of 200 g/L (Treatment Objective=5g/L)
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Example Application III - Relationship between EE/O and [H2O2]0/[DBCP]0
-- Impact of operational parameters on process efficiency
Molar Ratio: [H2O2]0/[DBCP] 0
EE/O
, (K
wh
/Kg
al-
Ord
er)
0.0
1.0
2.0
3.0
4.0
5.0
0 300 600 900 1200 1500
Io=1.04e-6eins./L-s, Carbonate=0.01mM, pH7.64
Io=1.04e-6eins./L-s, Carbonate=0.1mM, pH8.1
Io=1.04e-6eins./L-s, Carbonate=4mM, pH6.4
Io=1.30e-6eins./L-s, Carbonate=4mM, pH8.4
Io=1.04e-6eins/L-s, Carbonate=4mM, pH8.4
Io=0.52e-6eins./L-s, Carbonate=4mM, pH8.4
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Outline
•AOP Mechanism Behind the Model•Model Validation
•Example Applications
•Some Important Features
•Conclusions•Looking Forward ...
•Objectives of AdOxTM
32
CONCLUSIONS• AdOxTM is an easy-to-use tool for the
design and mechanistic study of the
H2O2/UV process.
• AdOxTM can evaluate the impact of process variables on process performance.
• AdOxTM is capable of simulating the
dynamic behavior of the H2O2/UV process
for several reactor configurations.
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CONCLUSIONS
• AdOxTM is user-friendly with its database, archiving ability and Visual Basic front-end.
• AdOxTM is a practical model and considers the impact of background components in the water matrix, non-ideal mixing, and multi-chromatic light sources.
34
Looking Forward...
• More processes options– Models of other AOP technologies
such as the H2O2/O3 and UV/O3
• Byproduct prediction– Generate the reaction pathway and
predict the fate of possible byproducts
• More informative database– More compounds – photochemical properties
35
Further Reading
Crittenden, J.C., Hu, Sh., Hand D.W., and Green S.A., "A Kinetic Model for H2O2/UV
Process in a Completely Mixed Batch Reactor," Water Research, 33(10), 2315-2328 (1999).
36
Contact us...
Prof. John C. Crittenden, CenCITT, Michigan Tech, (906)487-2798, E-mail: [email protected]
Prof. David W. Hand, CenCITT, Michigan Tech, (906)487-2777, E-mail: [email protected]
Ke Li, CenCITT, Michigan Tech, (906)487-3583, E-mail: [email protected]