Supplementary materials
for
Adsorption Mechanism of Humic Acid onto Cu/Fe Bimetallic Particles and its Influence on the Reduction of Nitrobenzene in Groundwater
Shuqiong Kong1, Yanxin Wang1, Hongbin Zhan2, 1, Songhu Yuan1, Qinhong Hu1,3*
1State Key Lab of Biogeology and Environmental Geologyand School of Environmental Studies,ChinaUniversity of Geosciences, Wuhan, 430074, P. R. China
2Department of Geology and Geophysics, TexasA&MUniversity, College Station, TX77843, USA
3 Department of Earth and Environmental Sciences, University of Texas at Arlington, Arlington, TX76019, USA
Number of Pages: 10
Number of Tables: 2
Number of Figures: 8
Figure Captions
Fig. S1. Pore Diameter Distributions of (a) bimetallic Cu/Fe(d50 = 93.5 nm); (b) zero-valent iron(d50 = 82.1 nm).
Fig. S2. SEM-EDX spectrum of bimetallic Cu/Fe particles. (a) SEM; (b) EDX
Fig. S3. SEM-EDX spectrum of Fe0 particles. (a) SEM; (b) EDX.
Fig. S4. Reactivity rate constants of HA adsorption on Cu/Fe and Fe0 after surface area normalization.
Fig. S5.Linear regression of KF versuspHfrom HA adsorption by Cu/Fe and Fe0.
Fig. S6.Adsorption isotherms of HA onto (a) Cu/Fe and (b) Fe0 at different pH after surface area normalization.
Fig. S7. Plots of lnK versus 1000/T for adsorption of HA onto Cu/Fe and Fe0.
Fig. S8. Plots of K1 versus HAconcentration for pseudo-first-order kinetics constants of nitrobenzene reduction by Cu/Fe and Fe0.
Fig. S1. Pore diameter distributions of (a) bimetallic Cu/Fe(d50 = 93.5 nm); (b) zero-valent iron(d50 = 82.1 nm).
Fig. S2. SEM (a) and EDX (b) spectra of bimetallic Cu/Fe particles.
Fig. S3. SEM (a) and EDX (b) spectra of Fe0 particles. Note: an additional oxygen peak was detected in the spectrum, which is likely due to the over-oxidation during the sample preparation，and an unmarked gold peak was observed for coating-Au.
Fig. S4. Reactivity rate constants of HA adsorption on Cu/Fe and Fe0 after surface area normalization.
Fig. S5.Linear regression of KF versuspHfrom HA adsorption by Cu/Fe and Fe0.
Fig. S6.Adsorption isotherms of HA onto (a) Cu/Fe and (b) Fe0 at different pH after surface area normalization.
Fig. S7. Plots of lnK versus 1000/T for adsorption of HA onto Cu/Fe and Fe0.
Fig. S8. Plots of K1 versus HAconcentration for pseudo-first-order kinetics constants of nitrobenzene reduction by Cu/Fe and Fe0.
Description of adsorption kinetic models
Two kinetic models,pseudo-first-order and pseudo second-order models(Hameed et al., 2008),were used to investigate the rate of the adsorption process of humic acid onto Cu/Fe and Fe0. The pseudo-first-order model was expressed as:
qt= qe(1 − e−k1t) (1)
and pseudo-second-order modelwas given by:
qt=qe2k2t / (1 + qek2t) (2)
where qe (mg/g) is the amount of adsorbate adsorbed at equilibrium,qt(mg/g) is the amount of adsorbate adsorbed at the timet, k1(1/min) is the rate constant of pseudo-first-order adsorption, and k2(g/mgmin) is the rate constant of pseudo-second-order adsorption. Thelinearized forms of the pseudo-first-order and pseudo-second-ordermodels used in this study are given in Table S1.
Table S1. Pseudo-first-order and pseudo-second-order kinetic rate constants for HA adsorption on Cu/Fe and Fe.
Pseudo-first-order / Pseudo-second-orderqe,exp (mg/g) / k1 / qe,cal(mg/g) / R2 / k2 / qe,cal
(mg/g) / R2
Cu/Fe / 10.22 / 0.114 / 9.85 / 0.8345 / 0.0175 / 10.18 / 0.9564
14.16 / 0.102 / 12.36 / 0.9138 / 0.00734 / 14.21 / 0.9674
16.88 / 0.0875 / 16.33 / 0.9363 / 0.00412 / 16.85 / 0.9952
19.92 / 0.0647 / 19.43 / 0.9524 / 0.00127 / 19.89 / 0.9865
22.14 / 0.0523 / 21.94 / 0.9035 / 0.000832 / 22.11 / 0.9736
23.79 / 0.0412 / 23.35 / 0.9378 / 0.000356 / 23.84 / 0.9423
25.13 / 0.0308 / 24.62 / 0.9261 / 0.000128 / 25.07 / 0.9641
Fe / 6.74 / 0.0326 / 6.53 / 0.8563 / 0.00219 / 6.71 / 0.9875
7.61 / 0.0265 / 7.43 / 0.9237 / 0.00138 / 7.56 / 0.9905
9.13 / 0.0113 / 9.06 / 0.9433 / 0.000845 / 9.11 / 0.9917
10.86 / 0.00836 / 10.64 / 0.8312 / 0.000621 / 10.87 / 0.9924
12.35 / 0.00671 / 12.25 / 0.9435 / 0.000416 / 12.32 / 0.9901
13.29 / 0.00354 / 13.11 / 0.8826 / 0.000279 / 13.28 / 0.9953
14.25 / 0.00184 / 14.09 / 0.8739 / 0.000103 / 14.21 / 0.9775
The adsorption conditions are temperature: 25℃, pH: 6.5, sorbent dosage: 20g/L. The variation of solution pH was less than 0.5 unit during the experiment.
TableS2. Fitting results of isotherms for HA on Cu/Fe and Fe0 at different temperatures.
Sorbent / T (℃) / KF / n / R2Cu/Fe / 5℃ / 5.829 / 2.959 / 0.989
15℃ / 6.094 / 3.126 / 0.994
25℃ / 6.341 / 3.304 / 0.993
35℃ / 6.640 / 3.854 / 0.981
Fe0 / 5℃ / 2.692 / 2.719 / 0.998
15℃ / 3.527 / 3.131 / 0.998
25℃ / 3.676 / 3.427 / 0.999
35℃ / 3.883 / 3.723 / 0.992
Reference
Hameed, B.H., Tan, I.A.W. and Ahmad, A.L., 2008. Adsorption isotherm, kinetic modeling and mechanism of 2,4,6-trichlorophenol on coconut husk-based activated carbon. Chemical Engineering Journal, 144(2): 235-244.
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Corresponding author:State Key Laboratory of Biogeology and Environmental Geology and School of
Environmental Studies, ChinaUniversity of Geosciences, Wuhan, 430074, P. R. China.E-mail: (Y.X. Wang); (Q.H. Hu).