- S1 -

Assessment of bimetallic and trimetallic iron-based system for

persulfate activation: application to sulfamethoxazole degradation

Ghada Ayoub, Antoine Ghauch1

American University of Beirut, Faculty of Arts and Sciences, Department of ChemistryP.O. Box 11-0236 Riad El Solh – 1107-2020 Beirut – Lebanon

Prepared for Chemical Engineering Journal

April 7, 2014

Supplementary Material

6 Pages, 7 Figures

1 Corresponding author. Tel.: +961 1 350 000; fax: +961 1 365 217. E-mail address: antoine.ghauch@aub.edu.lb

- S2 -

Fig. 1S. SEM images of CoFe (a) and AgFe (d) bimetallic systems as presented in Fig. 1. The corresponding X-ray maps of (b) Co (K1), (c) Fe (K1) and (e) Ag (K1) obtained from the two bimetallic systems CoFe and AgFe over the entire shown surface area (a, d). Areas of relatively high Fe concentrations are shown as bright regions in (c) and (f). In (b) less bright spots indicate areas of Co deposition whereas in (e) brighter spots indicate deposition of Ag at the surface of iron particles.

CoKa1 FeKa1

AgKa1 FeKa1Electron image

(b)(a) (c)

(d)

(b) (c)

Electron image

(e) (f)

(a)

29/01/2014 16:34:19

CoKa1

- S3 -

Fig. 2S. SEM images of AgCoFe (a) and CoAgFe (d) trimetallic systems as presented in Fig. 2. The corresponding X-ray maps of (b) Ag (K1), (c) Co (K1) and (d) Fe (K1) obtained from the two trimetallic systems AgCoFe and CoAgFe over the entire shown surface area (a, e). Areas of relatively high Fe concentrations are shown as bright regions in (d) and (h). In (c), (f) and (g) less bright spots indicate areas of Co and primary Ag deposition whereas in (b) brighter spots indicate deposition of Ag at the surface of iron particles as second deposited metal after Co.

(a) (b) (c) (d)

(e) (f) (g) (h)

Electron image

Electron image

FeKa1

FeKa1

AgKa1

AgKa1

CoKa1

CoKa1

- S4 -

Fe0/SMX/PS Fe0 Feeding

Fe2+/SMX/PS Direct Spiking

Fe2+/SMX/PS Sequential spiking

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

Ave

rage

% R

SE

Fig. 3S. Effect of direct vs sequential addition of Fe2+ compared to Fe0 in PS/SMX

solution on average % RSE over 30 min of reaction. Experimental conditions: [SMX]0 =

39.5 M, [Fe2+] = [Fe0] = 2.23 mM, m (Fe0) = 2.5 mg, pHi = 5.63.

Fig. 4S. Effect of bimetallic systems (CoFe and AgFe) and Fe0 on SMX degradation in

PS-free solutions. Experimental conditions: [SMX]0 = 39.5 M, m (Fe0) = m (AgFe) = m

- S5 -

(CoFe) = 2.5 mg (2.23 mM), pHi = 5.63. Error bars represent uncertainty at 95%

confidence level.

0 10 20 30 40 50 600

0.2

0.4

0.6

0.8

1

1.2

Co2+/SMXAg+/SMXFe2+/SMX

Elapsed Time / [min]

[SM

X] /

[SM

X]0

Fig. 5S. Effect of transition metal ions Co2+, Fe2+, and Ag+ on SMX degradation in PS /

H2O free systems. Experimental conditions: [SMX]0 = 39.5 M, [Fe2+], [Co2+ ] = [Ag+ ] =

2.23 mM, pHi = 5.63. Error bars represent uncertainty at 95% confidence level.

Fe

100

CoFe 5:100

AgFe 5:100

AgCoFe 5:5:100

CoAgFe 5:5:100

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1Non-DisturbedDisturbed

Iron Based Systems

kobs

/ ko

bs (F

e)

Fig. 6S. Reactivity of plated and non-plated iron-based systems: vertical bars display the

ratio of k obs measured for each of the amended Fe0 systems to the k obs values measured for

the standalone Fe0 system (Kobs(amended Fe)

K obs (Fe) ).

Traces of non identified

by-products

SMX-Derivative

- S6 -

Fig. 7S. Trace chromatograms of SMX treated in different metallic systems (Fe0, AgFe, and CoAgFe). Chromatograms with CoFe and

AgCoFe and similar to those presented; however, they are not shown for clarity. Experimental conditions: [SMX]0 = 39.5 M, [PS]0 = 1.0

mM, m (Fe0/ AgFe / CoAgFe) = 2.5 mg and m (Fe0) = 100 mg.

SMX

- S7 -