Supplementary Data
S1:
The methodology from (Bichsel and von Gunten 2000b) for measuring the
concentration of HOI was modified slightly. More details are as follows.
1. Preparation of HOI standard (Urbansky et al. 1997; Wang et al. 1989)
60 mM of ICl2-(aq) (ICl2- + H2O  HOI + H+ + 2Cl-; Kh = 1.06 × 10-6 M3)
- Mixture: 0.32 M HCl + 0.04 M I- + 0.02 M IO3- + 1 M NaCl
2. HOI quenching with 0.5 M phenol
3. Quantification of iodophenols using HPLC
- Mobile phase: mixture of 10 mM formic acid/acetonitrile (60%/40% (v/v)) with flow rate of
1.0 mL min-1
- UV detection: at 231 nm
(9.82 min and 10.70 min for p-iodophenol and o-iodophenol, respectively)
The calibration curves exhibited perfect linearity in different buffer solutions (refer to Fig. S1
below). The method without pH buffers was chosen for the analysis of HOI.
1
25
Iodophenol (M)
20
(c) Borate buffer (pH 8.6)
(b) Phosphate buffer 10 mM (pH 6.9)
(a) Acetate buffer 10 mM (pH 4.1)
o-iodophenol
p-iodophenol
total iodophenol
15
y = 0.999 x
2
R =1
y = 0.979 x
2
R =1
y = 0.987 x
2
R =1
10
5
0
25
(f) 0.1 N HCl
(e) 0.1 N HClO4
(d) 0.1 N phosphoric acid
Iodophenol (M)
20
15
y = 0.978 x
2
R = 0.99
y = 0.987 x
2
R = 0.99
10
y = 0.963 x
2
R = 0.99
5
0
0
5
10
15
20
0
5
HOI (M)
10
15
20
HOI (M)
25
(g) DI ( pH NOT controled )
Iodophenol (M)
20
o-iodophenol
p-iodophenol
total iodophenol
15
y = 1.032 x
2
R =1
10
5
0
0
5
10
15
20
HOI (M)
Fig. S1 Calibration curves of HOI in various buffer solutions.
2
0
5
10
HOI (M)
15
20
S2:
2.0
(b) Iodate
(a) Iodide
0.625 M
1.25 M
2.5 M
5 M
10 M
20 M
Value (S)
1.5
1.0
0.5
0.0
7.5
8.0
8.5
9.0
9.5
10.0 3.5
4.0
4.5
5.0
5.5
Retention time (min)
Retention time (min)
(c) Iodophenol
100
Intensity (mAU)
p-iodophenol
0.625 M
1.25 M
2.5 M
5 M
10 M
20 M
80
60
o-iodophenol
40
20
0
9.0
9.5
10.0
10.5
11.0
11.5
12.0
Retention time (min)
Fig. S2 IC chromatograms of iodide (a), iodate (b) and HPLC chromatograms of
iodophenol (c) for calibration.
3
S3:
(a)
[O3]0 = 41.6 M
[O3]0/[H2O2]0 = 2
[O3]0 = 41.6 M
40
O3 (M)
30
20
DI water
Sand-filtered water
Raw water
10
0
0
2
4
6
8
0
10
2
4
6
8
10
Time (min)
Time (min)
(b)
[O3]0 = 41.6 M
[O3]0/[H2O2]0 = 2
[O3]0 = 41.6 M
40
O3 (M)
30
20
DI water
Sand-filtered water
Raw water
10
0
0
5
10
15
20 0
Time (min)
5
10
15
20
Time (min)
Fig. S3 Depletion of ozone in the presence (a) and absence (b) of iodide ion in DI and natural
waters: [I-]0 = 20 μM; [O3]0 = 41.6 μM; ratio of [O3]0/[H2O2]0 = 2; [pCBA]0 = 1 μM; pH =
7.0 (phosphate buffer = 1 mM).
4
S4:
20
Concentration (M)
-
15
[I ]
[HOI]
[IO3-]
Unknown
10
5
0
0.5
1
2
4
Ratio of [O3]0/[H2O2]0
Fig. S4 Effect of the ozone/hydrogen ratio on the oxidation of I: [I-]0 = 20 μM; [O3]0 =
41.6 μM; ratio of [O3]0/[H2O2]0 = 2; [pCBA]0 = 1 μM; pH = 7.0 (phosphate buffer = 1 mM).
5
S5:
(a) Ozonation
Concentration (M)
20
-
[I ]
[HOI]
[IO3 ]
15
Unknown
10
5
0
pH 4
pH 7
pH 10
(b) Ozone/Hydrogen Peroxide
Concentration (M)
20
[I-]
[HOI]
[IO3 ]
15
Unknown
10
5
0
pH 4
pH 7
pH 10
Fig. S5 Concentrations of residual I- and iodine compounds produced after ozonation of Iunder different pH conditions: [I-]0 = 20 μM; [O3]0 = 41.6 μM; ratio of [O3]0/[H2O2]0 = 2
for the O3/H2O2 system; [pCBA]0 = 1 μM; pH = 7.0 (phosphate buffer = 1 mM).
6
Description:
In ozonation (Fig. S5a), at pH 4, less I was oxidized into IO3 with more production of HOI
compared to pH 7. This observation is due to the slower disproportionation rate of HOI at
lower pH (compare reactions 2 and 3). At pH 10, HOI was not detected with less conversion
of I into IO3, which is attributable to the production of HO2 (the conjugate base of H2O2)
by the accelerated reaction of O3 with OH (reaction S1). H2O2 reacts with HOI (reaction 8),
in which HOI (produced by ozone; reaction 1) is reversed to I. For the same reason, the
O3/H2O2 system produces less HOI.
O3 + OH

O2 + HO2 ( H2O2)
(S1)
In the O3/H2O2 system (Fig. S5b), HOI was not completely decomposed at pH 4, indicating
that HOI is more stable at acidic pH due to its slower disproportionation (reactions 2 and 3)
plus possibly the slower reaction with H2O2 (reaction8); the deprotonate form (OI) should
react with H2O2 much faster.
7
S6:
Removal efficiency (%)
100
(a) Iodide
(b) Iodate
80
60
40
20
0
0.1
0.2
0.5
1.0
5.0
0.1
0.2
0.5
1.0
5.0
-1
-1
Activated carbon (gL )
Activated carbon (gL )
Fig. S6 Removal efficiency of iodide (a) and iodate (b) ions by different doses of activated
carbon: [I-]0 = [IO3-]0 = 20 μM; pH = 7.0 (phosphate buffer = 1 mM); Reaction time = 48 h.
8