REDOX Equilibrium (III)
C.P. Huang
University of Delaware
CIEG 632
1
Content
1.
2.
3.
4.
Electrode Kinetics
Oxidation reactions
Reduction reaction
AOP
2
III.1 Electrode Kinetics
potential
‐-
+
A – e = A+
A + e = A-
3
iRu
Ewk
Power
supply
iRs
E
Auxiliary
electrode
Eaux
Ref
V
Rs
Ewk
I
Working
electrode
Reference
electrode
Eaux
Ru
4
ElectrodeE = EKinetics
Standard free energy
o
E > Eo
(1)nfE
Go,c
nfE

c
G
nfE
Ga
Go,a
O + nE  R
cathodic
Reaction corrdinate
R  O + ne anodic
5
E = Eo
Eapp = Eo +E
O+ne
(1‐)nfE

nfE

tan  = (1‐)nfE/x
tan  = nfE/x

tan /tan = (1‐)/
x
R
 tan  =(1‐) tan
 tan  = tan  – tan 
 = tan /(tan  + tan )
Symmetrical  =0,  =0.5
Otherwise 0 <= <= 0.5
½ <=  <=1
6
 = 0.5
O+ne
 > 0.5
R
 < 0.5
E
7
Electrode Kinetics
kf
O + ne R
kb
K = kf/kb
kf: reduction (cathodic) reaction
kb: oxidation (anodic) reaction
E = Eo – (RT/nF) ln (CR*/CO*)
CR*: bulk phase concentration of O
CO*: bulk phase concentration of R
CO(0,t)= concentration of oxidant at x = 0
and time t
CR(0,t)= concentration of reductant at x = 0
and time t
I = Ic ‐ Ia
8
Forcing a reduction reaction by applying E (Eapp) that is greater or smaller than Eo
E app = Eo ‐ E
Assume Arrhenius equation is applying
At CO*  CR*
E = Eo
kf Co* = kbCoR
kf = kb
o
f
k e
f = F/RT
nFE o RT=
o
b
k e
(1 ) nFE o RT
kfo = kbo = ko
9
f = F/RT
At T=25oC, f =16.9
ko = standard state constant
 = transfer coefficient
10
At E = Eo
Io = Ic = Ia
Io = Exchange current
11
i  ic  ia  0
 1 
d ln 
RT d ln k f RT
 kb   1

F dE
F
dE
vf  vb
k f CO ( 0,t )  k bCR ( 0,t )
 = Transfer coefficient
ln k f  ln CO ( 0,t )  ln k b  ln CR (0, t )
CO ( 0,t ) 
ln k f  ln k b  ln

C
 R ( 0,t ) 
ln k f  ln k b  ln K 

F
E  Eo
RT
α
RT d ln k f
F dE
β  1 α  

RT d lnk b 
F dE
d ln k f d ln k b
E


dE
dE
RT
12
log k
kf (kred)
kb (kox)
E
13
log k
kf
 = =0.5
kb
E
log k
kf
log k
 > 0.5;  <0.5
kf
 < 0.5;  >0.5
kb
kb
E
E
14
v net
I
i


 k f CO ( 0,t )  k bCR ( 0,t )
nFA nF
F ( E  E )
(1 )F ( E E
 o

RT
i  nF k f CO ( 0,t )e RT  k boCR ( 0,t )e

o
k k k
o
o
f
o
b
o
)



at E = Eo
F ( E  E )
(1 )F ( E E


RT
i  nFk o CO ( 0,t )e RT  CR ( 0,t )e

o
o
)



Butler-Volmer Equation
15

i
 CO ( 0,t )e
o
nFk
i
e
o
nFk
nF ( E E o )
i
e
o
nFk
RT
nF ( E E o )
RT
(1   )nF (E  E o )
 CR ( 0,t )e
RT
(1     )nF (E  E o )
 CO ( 0,t )  CR ( 0,t )e
RT
nF ( E E o )
RT
CO ( 0,t )  CR ( 0,t )e
 CO ( 0,t )  CR ( 0,t )e
nF ( E E o )
RT

i
e
o
nFk
nF ( E E o )
RT
nF ( E E o )
RT
For large ko
CO ( 0,t )  CR ( 0,t )e
nF ( E E o )
RT
Nernst equation
16
For large E – Eo = 
(1 ) nF
nF

( E E o )
( E E o ) 

 CR ( 0,t )e RT
i  nFk o CO ( 0,t )e RT



nF

( E E o ) 

i  nFk o CO ( 0,t )e RT



(1 ) nF
( E E o ) 

i  nFk o CR ( 0,t )e RT



  a  b log I
ηc  ac  bc logIc
ηa  aa  ba logIa
Tafel equation
17
Io
 io  nFk oCO* e
A
C C e
*
O
C 
* α
O
*
R
αnF ( E E o )

RT
C  C 
nF
( E E o )
RT
* 1
O
C  C 
*
O
C e
*
O

nF
RT
( E E o )
io

nFk o
α
nF
( E E o ) 
 * RT

  CR e



α
nF
o
(
E

E
)


α

CR*
  e RT



C   
* α
O
* 
R
α
* α
R
e

αnF
( E E o )
RT
i o  nFk C
o
ko = standard rate constant
Dependent on number of electron transferred;
αnF
fast when the number of electro transferred is
*

( E E o )



α
C
*
O
RT
CR  *   e
small;
 CO 
Slow when the number of electron transferred
is large.
+
Examples: anodic water oxidation 2H2O = O2 + 4H + 4e
cathodic hydrogen evolution 2H+ + 2e = H2
C   
* α
O
18
At equilibrium; I = 0
CO ( 0,t )  CO*
CR ( 0,t )  CR*
nFk oCO* e
*
O
*
R
C
e
C

αnF
( E E o )
RT
 nFk oCR* e
(1 α )nF
( E E o )
RT
nF
( E E o )
RT
Nernst Equation
19
Polarization curve
nF ( E E )
(1 ) nF ( E E



RT
RT
i  nFk o CO ( 0,t )e
 CR ( 0,t )e

o
)



  C 
* 1
O
i o  nFk C
o
o
* 
R
( E E o )
CO*
RT
e
*
CR
nF

nF
(1 )nF
i  CO ( 0,t )   RT  CO*   CR ( 0,t )  RT  CR*
 *    * e
 *
  * e
i o  CO 
 CR
 CO   CR 



 (1 )

nF
 CR ( 0,t )  (1RT)nF
i  CO ( 0,t )   RT
  * e
  * e
i o  CO 
 CR 
20

i
e
io
nF
RT
e
(1 )nF
RT
Large 

i
e
io
i
e
io
nF
RT
 i  1   nF
ln  

RT
 io 
ex = 1+x
x <<
 F 
i  i o 

 RT 
  RT

Rct 
i
ioF
(1 ) nF
RT

RT
RT
lni  
ln( i o )
1   nF
(1   )nF
  a  b log(i )
21
22
23
C x 0
i
 1
*
C
il
i 
i
 1 
i o  i l ,c
nF

 (1RT)nF
  RT
i
1  e
e

 i 

l ,a 


1 
 RT  1 1
 
 
i  
 nF  i o i l ,c i l ,a 
  i Rct  Rmt ,c  Rmt .a 
24
Measurements of ORP
Electrode kinetics
25
Stumm & Morgan
ORP measurements
Mixed potential
26
Stumm & Morgan
Kinetics of corrosion
V=kcorr[reactants]
kcorr=Aexp(-G*/RT)
G<0 for spontaneous reaction
At T=298.K; P=1atm
Mg+H2O+0.5O2  Mg(OH)2; Go =-596 kJ/mol
Cu+H2O+0.5O2 Cu(OH)2; Go =-119 kJ/mol
Au+1.5H2O+0.75O2Au(OH)3; Go = +66 kJ/mol
Anode: M Mz++ze
Cathode: pH <7 H+ +e H; 2HH2
pH >7 2H2O+O2+4e4OH27
ia<-ic
Q  zFM
Faraday’s law
dQ
dm
I
 zF
dt
dt
J
dm
dt
I  zFJ
28
Polarization
Cu<===> Cu2++2e
i a  i o  Ao e

G *
RT
Polarization: deviation from the equilibrium condition
Combination of anodic polarization and catholic polarization
29
 = total polarization
Anodic polarization, 
Cathodic polarization: (
i a  Ao e
 Ao e
 G * zF
RT
G *

RT
zF
RT
e
ia  ioe
zF
RT
ia  ioe
Let f=zF/RT
 f
30
ln i a  ln i o  fa
 ia 
ln   fa
 io 
 ic 
2.303
c 
log 
(1   )f
 io 
2.303  i a 
a 
log 
f
 io 
a 
2.303 16.91

f

a: Anodic Tafel costant
2.303 16.91
 ia 
a 

a   a log 
f

 io 
a    a log i o   a log i a
 A   a log i a
= 0.03-0.3
c    c log i o   c log i c
 B   c log i c
c 
2.303
16.91

(1   )f (1   )
31
E
Eo (H+,H2)
Evan Diagram
Io,c
2H+ 2e = H2
Er,a
Fe=Fe2+ + 2e
Ecorr
Eo (Fe,Fe2+)
Io,a
Er,c
I
Icorr
E corr Er ,a
icorr  io,a e
βa
E corr Er ,c
icorr  io,c e
βc
32
MMz++ze
c= -100 mv/decade
Mz++ze M
a=100 mv/decade
io=0.01 A/m2
io
33
Diffusion process
Electrode surface
J  D
2
1
Co
1: zero current
2: corrosion proceeds
dC
dx
i  zFJ
dC
dx

Co  C 
  zFD
x
i   zFD
x
At C = 0, I = imax
i max
Co
 zFD
x
Imax=il=limiting current
34
35
E1  E o 
0.05915
logCo
z
E2  E o 
0.05915
log C
z
  E 2  E1 
0.05915  C 
log 
z
 Co 
C
i
 1
Co
i max

0.05915 
i
log1 
z
 i max

i  imax





i obs i ai c  i o ef  e (1 )f

36
Mixed potential theory: Evans Diagram
37
A metal M of valance, z, atomic weight, w, and density, D, is being corroded at
io= A/cm2. Derive mm of metal loss per year over 1 m2. The number of
Coulombs passes in one year, icorrx60x60x24x365 = 3.154x107xicorr
1 mol of metal of valance, z, gives zx96494 Coulombs
# of mol per m2 lost per year = (3.154x107x icorr)/(zx96494) = (326.8xicorr)/z
= (326.8xwxicorr)/(1000z) (kg/m2-y)
For copper: io = 0.01 A/m2; z=2. w=63.5; D=8960 kg/m3
Loss =(326.8x63.5x0.01)/(2x1000)=0.104 (kg/m2-y)
Depth loss (mm) = 326.8xwxicorrx1000)/(1000xzxD)=326.8xwxicorr/(zxD)
Depth loss= (326.8x63.5x0.01)/(2x8960) = 0.012 mm/year
38
A metal M of valance, z, atomic weight, w, and density, D, is being corroded at
io= A/cm2. Derive mm of metal loss per year over 1 m2. The number of
Coulombs passes in one year, icorrx60x60x24x365 = 3.154x107xicorr
1 mol of metal of valance, z, gives zx96494 Coulombs
# of mol per m2 lost per year = (3.154x107x icorr)/(zx96494) = (326.8xicorr)/z
= (326.8xwxicorr)/(1000z) (kg/m2-y)
For copper: io = 0.01 A/m2; z=2. w=63.5; D=8960 kg/m3
Loss =(326.8x63.5x0.01)/(2x1000)=0.104 (kg/m2-y)
Depth loss (mm) = 326.8xwxicorrx1000)/(1000xzxD)=326.8xwxicorr/(zxD)
Depth loss= (326.8x63.5x0.01)/(2x8960) = 0.012 mm/year
39
Given:
a= 0.2 V/decade
c= -0.2 V/decade
io=20 mA/m2
a = 0.2V
=log(i/io)
a/a = 1
ia=10io=200mA/m2
c/c = -1
Find:
Iobs
ic=0.10 io=2mA/m2
Iobs=ia-ic = 200-2 =198 mA/m2
40
Passivity:
Certain metals able to withstand corrosion in media where they are thermodynamically
unstable
Chemical passivity:
Iron will dissolve in dilute HNO3 but in concentrate HNO3 a protective film is
formed and dissolution stops
Many other metals and alloys –Ni, Cr, Ta, Al in contact with oxidizing media from
passive film
Certain ions, Cl-, ends to cause breakdown of passivity
41
Electrochemical passivity
As metal is polarized anodically, is rate of dissolution first increases, until a
critical potential is reached, beyond this point, the rate of dissolution
drops sharply
E
3Fe + 3H2O = Fe3O4 + O2 + 12H+ + 12e
Passive film is
nonstoichiometric
oxide which has
high electron
Conductivity;
Electric field in
The film is very slow.
Tras-passive : oxygen evolution;
conversion of possible film to a higher
valance state which is soluble
Fe + H2O = FeO + 2H+ + 2e
Fe=Fe2+ + 2e
Log I (uA/cm2)
42
III.2 Oxidation Reaction
43
44
Stumm & Morgan
d Mn(II )

 k o Mn(II )  k Mn(II )MnO2 
dt
slow
Mn(II )  12 O2 
 MnO2 (s )
fast
Mn(II )  MnO2 (s ) 
 Mn(II ).MnO2 (s )
slow
Mn(II ).MnO2 (s )  12 O2 
 2MnO2 (s )
45
Stumm & Morgan
46
Stumm & Morgan
Ozonation
47
Stumm & Morgan
48
Electro-Fenton Oxidation
H+ + O 2
Fe+2
R
e-
H2 O2
Fe+3 + OH
.
R1 . + H 2 O
O2 + 2H + + 2e-
H2 O2
Eo = 0.695 V vs. NHE
(2.24)
O2 + 4H + + 4e-
2H2 O
Eo = 1.229 V vs. NHE
(2.25)
49
III.3 Reduction Reaction
50
51
Indirect perchlorate reduction
e-
Ti2+
Ti
e-
e-
H2O; O2
Ti4+
Ti3+
TiO2(s) H2O; O2
e-
Ti2+
Ti
TiO2(s)
eNO3-
TiO2(s)
Ti3+
NO2-
eNO3-
TiO2(s)
Ti4+
NO2NO2
NO2
NO
NO
(Scheme IV)
e-
Ti2+
Ti
TiO2(s)
e-
TiO2(s)
e-
ClO3-
ClO3- ClO4
ClO2-
ClO2-
ClO2
ClO2
(Schemes II)
ClO-
ClO-
eTi
Ti2+
ClO4-
e-
NH4+
NH4+
Ti4+
Ti3+
ClO4-
N2
N2
eTi3+
TiO2-xClx(s) ClO4
Cl-
Cl-
Ti4+
eTi
-
Ti2O3(s)
Ti2+
NO3-
e-
eTi3+
TiO2-xNx(s) NO3
Ti4+
Ti2O3(s)
52
250
600
200
-
ClO2
Cl- ClO4
ClT
ClO3-
150
100
400
200
50
0
0
2
4
6
8
0
Concentration of ClO3 ,ClT(as Cl,ppb)
Concentration Cl-, ClO2 ,ClO4 (as Cl, ppb)
800
300
Time (hr)
Figure 2 Reduction of perchlorate at ultra-low concentration. Experimental conditions: Perchlorate concentration
= 150 ppb; Supporting electrolyte = 4.5 ppm KClO3; temperature = 25 oC; pH = 7; Anode = Ti; Cathode = Fe;
Voltage applied = 10 V; Current = 10 mA (or current density = 1.9 mA/cm2)
53
Zero Valent Iron (ZVI)
Fe ( 0 )  RX  H   RH  X   Fe 2 
Fe ( 0 )  O 2  2H 2O  2Fe 2   4OH 
Fe ( 0 )  2H 2O  Fe 2   H 2  2OH 
2Fe 2   RX  H   2Fe 3  RH  X 
H 2  RX  RH  H   X 
Anaerobic corrosion: Fe0 + 2H2O → Fe2+ + H2 + 2OHAerobic corrosion: 2Fe0 + O2 + 2H2O → 2Fe2+ + 4OH54
III.4 Advanced Oxidation
55
Oxidation-reduction potentials
Reaction
(Lide et al., 1992)
Eo(volt @25 oC)
F2 + 2e- = 2F-
2.87
OH. + H+ + e- = H2O
2.63
O3 + 2H+ + 2e- = O2 + H2O
2.07
H2O2 + 2H+ + 2e- = 2H2O
1.76
MnO4- + 4H+ + 3e- = MnO2 + 2H2O
1.68
MnO4- + 8H+ + 5e- = Mn2+ + 4H2O
1.49
HOCl + H+ + 2e- = Cl- + H2O
1.49
Cl2 + 2e- = 2 Cl-
1.36
O3 + H2O + 2e- = O2 + 2 OH-
1.24
ClO2 (gas) + e- = ClO2-
1.15
ClO2 (aq.) + e- = ClO2-
0.95
H2O2 + 2H3O + 2e- = 4H2O
0.87
O2 + 2H2O + 4e- = 4OH-
0.40
56
Hydroxyl Radical as an Oxidant
Rate Constants for Hydroxyl
Radical Attack on Aromatic
Compounds (Buxton et al.,
1988).
Rate Constants
Aromatic Compounds
Phenol (pH 6 to 9)
(107 M-1S-1)
Fluorobenzene
1400
1000
Biphenyl
950
Phenylmethanol
840
Benzene
780
Styrene (Ethenylbenzene)
600
Chlorobenzene
550
Iodobenzene
500
Benzoic Acid (pH=3)
430
Nitrobenzene
390
Toluene
300
57
All AOTs
700
600
500
400
300
200
20
08
20
06
20
04
20
02
20
00
19
98
19
96
19
94
19
92
100
0
19
90
Journal Publication
800
O3
O3 +H2O2
O3+UV
H2O2+UV
O3+H2O2+UV
Fenton
Fenton+UV
O3+Fenton
Electro-Fenton
US
O3+US
TiO2
Year
58
19
90
19
91
19
92
19
93
19
94
19
95
19
96
19
97
19
98
19
99
20
00
20
01
20
02
20
03
20
04
20
05
20
06
20
07
20
08
JournalPublication
UV-O3-H2O2 Based AOPs
200
180
160
140
120
100
80
60
40
20
0
H2O2+UV
O3 +H2O2
O3+H2O2+UV
Year
59
All O3-based AOPs
800
O3
O3 +H2O2
O3+UV
O3+H2O2+UV
O3 +US
O3 Fenton
Journal Publication
700
600
500
400
300
200
100
0
0
0
2
2
1
1
0
2
3
3
5
5
7
3
9
9
17
12
4
Year
120
O3 +H2O2
O3+UV
O3+H2O2+UV
O3 +US
O3 Fenton
Journal Publication
100
80
60
40
20
0
0
0
2
2
1
1
0
2
3
3
Year
5
5
7
3
9
9
17
12
4
60
All H2O2-based AOTs
250
Journal Pulication
200
150
100
50
O3 +H2O2
H2O2+UV
O3+H2O2+UV
Fenton
Fenton+UV
Electro-Fenton
US+ H2O2
0
1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008
Year
61
19
90
19
91
19
92
19
93
19
94
19
95
19
96
19
97
19
98
19
99
20
00
20
01
20
02
20
03
20
04
20
05
20
06
20
07
20
08
Journal Publication
19
90
19
91
19
92
19
93
19
94
19
95
19
96
19
97
19
98
19
99
20
00
20
01
20
02
20
03
20
04
20
05
20
06
20
07
20
08
Journal Publication
All Fenton Systems
250
200
150
100
50
40
30
Fenton
Fenton+UV
O3+Fenton
Electro-Fenton
50
0
70
Year
60
Fenton+UV
O3+Fenton
Electro-Fenton
20
10
0
Year
62
Year
20
08
20
06
20
04
600
20
02
1200
20
00
800
19
98
800
19
96
19
92
19
93
19
94
19
95
19
96
19
97
19
98
19
99
20
00
20
01
20
02
20
03
20
04
20
05
20
06
20
07
20
08
19
91
19
90
Number of Publication
1000
19
94
19
92
19
90
Journal Publication
O3 versus H2O2
1200
All O3
All H2O2
All Fenton
600
400
200
0
Year
1000
All O3
All H2O2 + Fenton
400
200
0
63
2008
2007
2006
2005
2004
2003
2002
2001
2000
1999
1998
1997
1996
1995
1994
300
1993
400
1992
1991
1990
Jounal Publication
All TiO2 Systems
600
500
TiO2
TiO2 + H2O2
ALL TiO2
200
100
0
Yera
64
19
90
19
91
19
92
19
93
19
94
19
95
19
96
19
97
19
98
19
99
20
00
20
01
20
02
20
03
20
04
20
05
20
06
20
07
20
08
Journal Publication
Sonochemical processes
45
40
35
30
25
20
15
10
5
0
US
O3+US
US+ H2O2
Year
65
Journal Publication
Irradiation
450
400
350
300
250
200
150
100
50
0
All UV
All US
E Beam
Corna Discharge
1
2
3
4
5
6
7
8
9
10 11 12 13
14 15 16 17
18 19
Year
15
16
17
18
19
20
08
13 14
20
07
12
20
06
11
20
05
10
Year
20
04
9
20
03
8
20
02
7
20
01
6
20
00
5
19
99
4
19
98
3
19
97
2
19
96
1
19
95
0
19
94
10
19
93
20
19
92
30
All US
All UV
19
91
All US
E Beam
Corna Discharge
40
450
400
350
300
250
200
150
100
50
0
19
90
50
Journal Publication
Journal Publication
60
Year
66
Advanced Oxidation Processes
“Advanced
oxidation processes are defined as
those which involve the generation of hydroxyl
radicals in sufficient quantity to affect water
purification.”
William H. Glaze; Joon-Wun Kang; Douglas H. Chapin.
Ozone: Science & Engineering, 9(4): 335-352 (1987). 67
How to Generate .OH?
• Homogeneous systems
– Without irradiation
•
•
•
•
H2O2‐O3
H2O2‐Fe(II)
O3‐OH‐
SCW
– With irradiation
• H2O2‐UV
• O3‐UV
• H2O2‐Fe(II)‐UV
• US
• US‐UV
• US‐H2O2
• e‐Beam; corona discharge
• Heterogeneous systems
– Without irradiation
• Electro‐Fenton
• WAO‐catalyst
– With irradiation
•
•
•
•
•
TiO2‐UV
TiO2‐H2O2‐UV
UV‐electro‐Fenton
US‐Fenton
BiVO4‐visible light
• Photo‐electrochemical
Modified from Huang et al. (1991)
68
x = x0 sin 2ft
P(t) = Pa sin2ft
I= Pa2/2c
I = I0e-21
69
Pm(  1) 

T max  T


P




0



Pm(  1) 

P max  P


P








T0
P
 {1  Q[( )1/ 3 γ 1] 1}3(γ1)
Tmax
Pmax
Q is the ratio of the resonance amplitude to the
static amplitude of vibration of the bubble
 / (  1)
T0 = ambient temperature
 = ratio of specific heats of the gas
P = pressure in bubble at it’s maximum size
Pm = pressure in the liquid at the moment of
transient collapse
Pmax = maximum pressure in the liquid at the
moment of transient collapse
70
Sonophysics
71
Sonochemistry
200 – 6000 kHz
72
Polycyclic Aromatic Compounds
Compound
Name
Empirical
Formula
Molecular
Structure
Molecular Wt.
(g/mole)
Melting Point
( °C )
Boiling Point
(°C)
Solubility in
Water (mg/l)
log Kow
Specific
gravity
dibenzothiophene
Phenanthrene
benzothiophene
naphthalene
C12H8S
C14H10
C8H6S
C10H8
S
S
184.26
178.22
134.20
128.16
98~100
100
29~32
80.2
332~333
340
221~222
217.9
1.4
1.2*
28~29
30
N/A
4.46
N/A
3.01
N/A
1.025
1.15
1.152
Color
Gray flakes or
powder
colorless
leaflets
colorless
white flakes
or powder
Biological
effects
Toxic
Toxic
Toxic
Toxic
73
pH Controller
Ultrasonic Generator
Ultrasonic probe
1
2
Temperature Controller (Water bath)
1. Sample Port or Thermometer
2. pH probe & Acid/Base lines
74
5.2 kCal/mol
-4.5 kCal/mol
energy intensity = 226 watts/cm2, total volume = 40 mL, pH = 5,
temperature = 25o C, ionic strength = 0.05 M NaClO4
75
Kim et al. Water Research, (2003)
Scan 697 (10.006 min): 222BT120.D
Abundance
Abundance
150
TIC: 222BT120.D
160000
5000
10.25
10.07
150000
OH
4500
140000
4000
130000
S
120000
3500
110000
100000
4-hydroxybenzothiophene
3000
122
121
90000
2500
80000
70000
2000
10.20
60000
9.94
50000
1500
10.00
40000
10.88
30000
6.57
1000
11.04
20000
500
51
10000
0
6.00
6.50
7.00
7.50
8.00
8.50
9.00
9.50
0
m/z-->
10.00 10.50 11.00 11.50
50
63
61
60
69
77
96
93
82
70
80
90
100
110
120
130
140
150
160
Time-->
Abundance
Scan 690 (9.941 min): 222BT120.D
136
Abundance
Scan 327 (6.566 min): 222BT120.D
134
13000
18000
O
12000
16000
11000
S
14000
10000
S
9000
12000
benzothiophene
8000
O
benzothiophene-2,3-dione
10000
108
7000
8000
6000
5000
6000
4000
69
4000
3000
2000
1000
63
51
0
m/z-->
50
58
60
70
82
80
95
90
76
164
92
0
102
100
63
54
108
69
74
82
2000
89
110
120
130
140
150
160
50
60
70
80
90
100
110
120
130
140
150
160
m/z-->
76
170
Scan 723 (10.248 min): 222BT120.D
Abundance
Abundance
150
Scan 703 (10.062 min): 222BT120.D
150
38000
55000
36000
50000
34000
S
32000
45000
30000
28000
40000
OH
26000
24000
121
30000
3-hydroxybenzothiophene
20000
2-hydroxybenzothiophene
35000
S
22000
OH
18000
25000
16000
14000
121
20000
12000
15000
10000
8000
6000
4000
122
10000
78
51
2000
63
96
69
58
84
0
50
60
70
80
89
5000
105111
90
100
110
135
120
130
140
150
0
m/z-->
160
63 69
61
51
50
60
70
77
85
80
96
93
90
105
100
132
110
120
130
140
150
m/z-->
Scan 718 (10.201 min): 222BT120.D
Abundance
Abundance
150
Scan 808 (11.041 min): 29BT90ND.D
137
5500
12000
5000
HO
OH
4500
10000
8000
S
S
4000
5-hydroxybenzothiophene
3500
OH
2,3-dihydroxybenzothiophene
109
3000
6000
2500
121
2000
166
4000
1500
2000
51
0
m/z-->
50
1000
63
60
69
77
82
96
93
63
118
89
74
500
105
133
134
102
82
0
50
60
70
80
90
100
110
120
130
140
150
50
60
70
80
90
100
110
120
130
140
150
160
m/z-->
77
170
1
ultrasonic energy intensity = 226 watts/cm2,
total volume = 40 mL, pH = 7, C0 = 0.12 mM,
temperature = 25 oC, ionic strength = 0.05 M
NaClO4 (The solid lines are obtained from the
equations
78
Kim et al. Water Research, (2003)
H
+ OH.
S
+ OH.
- H.
H
(step 2)
.
S
(step 1)
benzothiophene
OH
OH
S
3-hydroxybenzothiophene
3-hydroxy-2,3-dihydrobenzothiophene
+ OH.
O
OH
+ 2OH.
-2H.
S
O
(step 4)
benzothiophene-2,3-dione
.
+ OH.
-H.
S
OH
(step 3)
2,3-dihydroxybenzothiophene
OH
OH
S
H
2,3-dihydroxy-2-hydrobenzothiophen
+ OH.
COOH
SO3H
sulfobenzoic acid
O
+OH., O2
OH
OH
2,3-dihydroxybenzene
+ 2OH.
-2H.
O
2,3-quinone
79
O
O
C
COOH
COOH
O
C
H
C
OH
OH
C
H
O
2,3-quinone
muconic acid
H
OH
C
O
acrylic acid
maleic acid
H
H
H
C
C
HO
H
HO
OH
C
CH2
CH2
C
C
C
O
acrylic acid
HO
O
C
H
O
3-hydroxy propionic acid
HO
O
malonic acid
HO
C
O
H
CH2
C
H
C
HO
HO
malonic acid
C
H
C
CO2
C
O
H
+
H
O
acetic acid
H
HO
C
O
+
C
HO
O
H
C
OH
C
H
O
O
+
C
HO
O
C
HO
O
80
acrylic acid
oxalic acid
glyoxylic acid
formic acid
S
benzothiophene
OH
HO
S
4-hydroxybenzothiophene
6-hydroxybenzothiophene
5-hydroxybenzothiophene
S
S
HO
S
OH
7-hydroxybenzothiophene
OH
HO
HO
S
4,5-dihydroxybenzothiophene
S
HO
5,6-dihydroxybenzothiophene
HO
S
OH
6,7-dihydroxybenzothiophene
O
O
O
S
benzothiophene-4,5-dione
HOOC
HOOC
O
S
benzothiophene-5,6-dione
O
S
O
benzothiophene-6,7-dione
HOOC
S
thiophene-maleic acid
HOOC
S
thiophene-maleic acid
HOOC
S
HOOC
thiophene-maleic acid
HO
HO
S
2,3-dihydroxythiophene
O
O
S
thiophene-2,3-dione
CO2, SO32-
81
OH
S
4-hydroxybenzothiophene
HO
S
5-hydroxybenzothiophene
other products
(e.g., ring-cleaved
products)
k4
S
HO
6-hydroxybenzothiophene
S
OH
7-hydroxybenzothiophene
k1
S
k2
OH
2-hydroxybenzothiophene
OH
S
OH
k5
S
OH
O
k6
k7
S
O
other products
(e.g., ring-cleaved
products)
2,3-dihydroxybenzothiophene benzothiophene-2,3-dione
benzothiophene
S
3-hydroxybenzothiophene
k3
other products
82
CBT  CBT ,0 exp(  k A t )
k1CBT ,0
C 4567HXBT 
[exp(  k A t )  exp(  k 4 t )]
( k 4 k A )
k 2CBT ,0
C 23HXBT 
[exp(  k A t )  exp(  k 5 t )]
( k 5 k A )
C 23 OH
k1 = 8.0x10-5 s-1
k2 = 1.9x10-4 s-1
k3 = 0.8x10-4 s-1
kA = 3.5 x 10-4 s-1
k4 = 1.7x10-4 s-1
k5 = 2.0x10-4 s-1
k6 =1.8x10-4 s-1
k7 = 1.6x10-4 s-1
 k k exp(  k t ) k k exp(  k t ) k k exp(  k t ) 
A
A
6

 C BT ,0  2 5
 2 5
 2 5
 ( k 6 k A )( k 5 k A ) ( k 6 k A )( k 5 k A ) ( k 6 k A )( k 5 k A ) 
k 6k 5 exp( k 5 t)
CBT 23DN
k 6k 5 exp( k 2 t)


CBT ,0
(k 5  k 2 )(k 6  k 2 )(k 7  k 2 ) (k 5  k 2 )(k 6  k 5 )(k 7  k 5 )

k 5 (k 5  k 2 ) exp( k 6 t)
k 6k 5 exp( k 7 t)

(k 5  k 2 )(k 6  k 2 )(k 6  k 5 )(k 7  k 6 ) (k 5  k 2 )(k 6  k 2 )(k 6  k 5 )(k 7  k 2 )

k 6k 5 exp( k 7 t)
k 5 (k 5  k 2 ) exp( k 7 t)

(k 5  k 2 )(k 6  k 2 )(k 6  k 5 )(k 7  k 5 ) (k 5  k 2 )(k 6  k 2 )(k 6  k 5 )(k 7  k 6 )
83
C_BT
C_23HXBT
C_4567HXBT
C_BT23DN
sum of 3 intermediates
Carbon M. B.
[ CO ], 8x1 Molar
0.00012
Concentration (Molar)
0.0001
8 10
-5
6 10
-5
4 10
-5
2 10
-5
2
0
0
1
2
3
4
5
6
7
3
Time (10 sec)
ultrasonic energy intensity = 226 watts/cm2, total volume = 40 mL, pH = 7, C0
= 0.12 mM, temperature = 25 oC, ionic strength = 0.05 M NaClO4 (The solid 84
lines are obtained from the equations
DBPs: Trihalomethanses
85
-11.42 kCal/mol
7.2 kCal/mol
-6.95 kCal/mol
3.23 kCal/mol
-6.95 kCal/mol
3.23 kCal/mol
-5.21 kCal/mol
3.23 kCal/mol
chloroform > dichlorobromomethane >
dibromochloromethane >
bromoform.
Kim et al 2001
ultrasonic energy intensity = 226 watts/cm2, total volume = 40 mL, C0 = 3.7 M, pH = 7,
temperature = 25oC, ionic strength = 0.05M NaClO4.
86
Residual BOD: Humic Substabce
HO
O
OH
OH
OH
O
O
COOH
O
OH
HO
OH
COOH
(A)
O
O
HO
HO
C
OH
O
C
O
C
OH
O
C
OH
OH
O
C
OH
C
OH
O
C
O
H
OH
O
H
O
C
OH
OH
C
HO
O
HO
C
HO
C
O
O
H
O
O
O
HO
C
OH
C
C
C
OH
O
C
OH
O
OH
H
O
O
OH
HO
O
O
O
C
O
OH
C
OH
C
C
OH
O
O
C
C
HO
C
OH
O
OH
O
H
OH
OH
OH
(B)
Schnitzer et al., (1972); Paciollar et al., (1999).
87
Experimental Conditions: ultrasonic energy intensity = 283 watts/cm2, total volume = 10 mL, C0 = TOC
10 mg/L, pH0 = 7, temperature = 25 oC, ionic strength = 0.05 M NaClO4.
Kim et al 2000
88
ultrasonic energy intensity = 283 watts/cm2, total volume = 10 mL, H2O2 10mM, pH0 7, C0 = TOC 10 mg/L,
temperature = 25 oC, ionic strength = 0.05 M NaClO4.
Kim et al 2000
89
Cryptosporidium parvum
Fayer,. et al, (1990).
90
-9.17 kCal/mol
7.94 kCal/mol
91
Huang and Myoda, ((2007)
92
Semiconductor
Conduction Band
Conduction Band
Conduction Band
Band gap
Valance Band
Valance Band
Conductor
Valance Band
Semiconductor
Insulator
h
Reduction Reaction
O + electrons → R + by product
e.g. 2H++2e-→H2
e-
Conduction Band
Oxidation Reaction
Recombination,
(release of thermal energy)
Valance Band
h+
R + holes → O + by product
e.g. 2H2O + 4h+ →O2+4H+
Photocatalysis
93
TiO2/Ti-Pt
(a) at 2.5 V in the dark;
(b)-(e) at 0, 0.5, 1.5, and 2.5 V under UV
illumination, respectively.
(a) E-H2O2;
(b) E-H2O2/UV;
(c) TiO2 PEC;
(d) E-H2O2/TiO2 PEC.
Li et al. ES&T, 2005
94
Hoe et al. Science of Total Environment. 2009
95
C-doped TiO2
Band gap of TiO2 (3.0
to 3.2 eV);
Solar spectrum
constrains only 4~5%
UV
Zhou et al. App. Cata. B: Environ. 2010
96
[2,4-DCP] = 0.06 mM; Chamber (A) pH = 11, Chamber (B) pH = 2; λ = 350 nm; 0.1
M Na2SO4 as electrolyte
Zhou et al. App. Cata. B: Environ., 2010
97
Fenton Reagents
Fe2+ + H2O2 → Fe3+ + OH− + OH• (1) chain initiation
OH• + H2O2 → HO2• +H2O (2) chain propagation
Fe3+ + •HO2 → Fe2+ + H+ + O2 (3) chain propagation
Fe2+ + •HO2 → Fe3+ + HO2− (4) termination
Fe2+ + OH•→ Fe3+ + OH− (5) termination
(Mn+) + H2O2 → (Mn+1) + OH− + OH•
Fe2+ + H2O2 = FeO2+ + H2O (7)
FeO2+ + H2O2 = Fe2+ + H2O + O2 (8)
Fe2+ + OH•→ Fe3+ + OH−
(9)
Fe3+ + OH• → FeOH3+ (10)
98
Photochemical reactions
99
Stumm & Morgan
100
Stumm & Morgan

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