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 on Advanced Oxidation Technologies for Water and Air Remediation London, Ontario Canada, June 26-30, 2000 Copyright © 2000-2002. Michigan Technological University. All Rights Reserved.

Outline Objectives of AdOxTM AOP Mechanism Behind the Model Model Validation Some Important Features Example Applications Conclusions Looking Forward ...

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

Outline Objectives of AdOxTM AOP Mechanism Behind the Model Model Validation Some Important Features Example Applications Conclusions Looking Forward ...

AOP Mechanism Behind The Model The 44 reactions considered in the model include the most comprehensive mechanism: 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 Reactions of organic compound R: R + hv  Products R+ HO  Products Inorganic Scavengers: HO  + CO32- / 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 Pseudo-steady-state is not assumed pH variation is considered The influence of Background Organic Matter is considered: absorption of UV light (es) and its influence on the photolysis of target compound and H2O2 BOM + hv  scavenging of hydroxyl radicals HO + BOM 

Outline Objectives of AdOxTM AOP Mechanism Behind the Model Model Validation Some Important Features Example Applications Conclusions Looking Forward ...

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)

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 120 100 ) -1 s 80 -5 , (10 60 0, DBCP 40 experimental result k AdOx prediction 20 Glaze et al.'s model prediction 1 2 3 4 5 6 7 [H O ] , mM 2 2

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 0.2 0.4 0.6 0.8 1 2 4 6 8 10 12 14 H2O2 , experimental result BuCl, experimental result AdOx prediction Liao et al. 's model prediction o /C Normalized Concentration, e C Fluka Humic Acid as DOC, mg/L

Outline Objectives of AdOxTM AOP Mechanism Behind the Model Model Validation Some Important Features Example Applications Conclusions Looking Forward ...

Important Features of AdOxTM 1.0 Model Various Reactor Configurations: Completely Mixed Batch Reactor (CMBR) Completely Mixed Flow Reactor (CMFR) Completely Mixed Batch Reactor (CMBR) V R C e dC a dt r = (Governing Equation) Completely Mixed Flow Reactor (CMFR) Q, C in VR e dC dt ao a + 1 (C r - t = ) (Governing Equation)

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.) n-CMFR: Q, C in V R n 1 n-1 n-2

Important Features of AdOxTM 1.0 Determine Optimum Operational Parameters: Optimum H2O2 Dosage UV Light Intensity Hydraulic Retention Time Dynamically model multi-component contaminant mixtures (up to 10). Model multi-chromatic light sources (up to 100 wavelength)

Important Features of AdOxTM 1.0 Includes a database of more than 600 compounds including second-order hydroxyl-radical rate constants Determine the influence of water quality : Alkalinity (Total Inorganic Carbon) pH

Some Important Features Modeling Different Reactor Configurations

Some Important Features Modeling Multi-chromatic (up to 100) Light Sources

Some Important Features Dye Study Analysis for Tanks-In-Series Model

Some Important Features Database of Second-Order Hydroxyl-Radical Rate Constants

Selection of Optimum [H2O2]0/[DBCP]0 as a function of Water Quality Parameters

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)

Impact of CT,CO3 on EE/O for the Degradation of DBCP ([H2O2]0=1 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)

Impact of pH on Degradation Rate of DBCP and H2O2 (I0 = 1.0410-6 eins./L-s;[H2O2]0 = 1.00mM; CTIC = 4 mM)

Impact of pH on EE/O for the DBCP Degradation (I0 = 1. 0410-6 eins Impact of pH on EE/O for the DBCP Degradation (I0 = 1.0410-6 eins./L-s; [H2O2]0 = 1.00mM; CTIC = 4 mM)

Outline Background Objectives of AdOxTM AOP Mechanism Behind the Model Model Validation Some Important Features Example Applications Conclusions Looking Forward ...

Example Applications 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:

Example Application I - Predicted Energy Requirement for an Influent Vinyl Chloride Concentration of 10 g/L(Treatment Objective=2g/L) 3 0.5 1 1.5 2 2.5 5 10 15 20 [H O ] , (mg/L) [H3C2Cl]0=10g/L=1.610-7M=0.16M TOC = 5 mg/L TIC = 8.0 mM pH 7.0 I0 = 1.010-6 eins./L-s Optical length L = 7.5 cm K HO and NOM = 2.0104 (mg/L)-1s-1 The UV-light absorption and direct photolysis of vinyl chloride are ignored (Kw-hour/Kgal-Order) EE/O

Example Application II - Predicted Energy Requirement for an Influent TCE Concentration of 200 g/L (Treatment Objective=5g/L) 3 6 9 20 40 60 80 [H 2 O ] , (mg/L) [TCE]0=200g/L=1.52M=1.5210-6 M TOC = 5 mg/L TIC = 8.0 mM pH 7.0 I0 = 1.010-6 eins./L-s Optical length L = 7.5 cm K HO and NOM = 2.0104 (mg/L)-1s-1 TCE=10M-1 cm-1, the direct photolysis of TCE is ignored. (Kw-hour/Kgal-Order) EE/O

Example Application III - Relationship between EE/O and [H2O2]0/[DBCP]0 -- Impact of operational parameters on process efficiency 0.0 1.0 2.0 3.0 4.0 5.0 300 600 900 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 EE/O, (Kwh/Kgal-Order) Molar Ratio: [H 2 O ] /[DBCP]

Outline Objectives of AdOxTM AOP Mechanism Behind the Model Model Validation Some Important Features Example Applications Conclusions Looking Forward ...

CONCLUSIONS AdOxTM is an easy-to-use tool for the design and mechanistic study of the H2O2/UV process. AdOxTM is capable of simulating the dynamic behavior of the H2O2/UV process for several reactor configurations. AdOxTM can evaluate the impact of process variables on process performance.

CONCLUSIONS AdOxTM is a practical model and considers the impact of background components in the water matrix, non-ideal mixing, and multi-chromatic light sources. AdOxTM is user-friendly with its database, archiving ability and Visual Basic front-end.

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

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).

Contact us... Prof. John C. Crittenden, CenCITT, Michigan Tech, (906)487-2798, E-mail: jcritt@mtu.edu Prof. David W. Hand, CenCITT, Michigan Tech, (906)487-2777, E-mail: dwhand@mtu.edu Ke Li, CenCITT, Michigan Tech, (906)487-3583, E-mail: keli@mtu.edu