Supplementary information for

Easily prepared and stablefunctionalized magnetic ordered mesoporous silicafor efficient uranium extraction

WenLu Guo1,2, ChangMing Nie1*, Lin Wang2，ZiJie Li2

Lin Zhu1,2, LiuZheng Zhu2, ZhenTai Zhu3, WeiQun Shi2 LiYong Yuan2*

1School of Chemistry and Chemical Engineering, University of South China, Hengyang 421001, China.

2Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.

3StateKeyLaboratoryofNBCProtectionforCivilian,Beijing102205,China

SI-1 Sorption experiments

The sorption experiments were carried out using the batch method. The initial concentrations of U(VI) varied from 5–200 mg L−1. The pH of solution was adjusted by adding negligible volumes of sodium hydroxide solution or diluted nitric acid solution. In a typical experiment, 4 mg adsorbent was added into either 10 ml multi-ion or 10 mL U(VI) solution test solution in polytetrafluoroethylene-lined screw cap glass tubes (50 ml). The polytetrafluoroethylene-lined screw cap glass tubes were shock in Shaking Water Bath for specified time (t, min) at 20°C, and then the solid phase was magnetically separated from the solution for 360 min at 20°C, the two phases were separated by an external magnet. The control experiment was performed at the same time using the identical U(VI) solution without adsorbent. Before the determination, solutions filtering by needle type filter, and diluted 50 times for the concentration analysis. The concentrations of U(VI) in the solution were determined by UV–Visible spectrometry and the multi-ion were determined by inductively coupled plasma optical emission spectrometer (ICP-OES). All values were measured in duplicate with the uncertainty within 5%.

SI-2 Analytical techniques

The morphologies, sizes of the samples were examined with a field emission scanning electron microscopy (SEM, Hitachi S-4800). Power X-ray diffraction (PXRD) patterns of the materials were obtained on a Bruker D8-Advance X-ray Diffractometer with a Cu Kα radiation (λ=1.5406 Å). Thermogravimetric curve were recorded on a thermal gravimetric analyzer (TGA, TA Instruments, Q500) from 50-800 °C by a heating rate of 5 °C min-1 under air flow for the study of functionalized content of the magnetic materials. Data of fourier transform infrared (FT-IR) spectra of the prepared samples were record on a Bruker Tensor 27 spectrometer with a potassium bromide pellet method. The N2 adsorption experiments were measured at a liquid nitrogen temperature (77K) using a micromeritics ASAP 2020 HD88 instrument. The specific surface area was calculated by the Brunauer–Emmett–Teller (BET) method with prior degassing under vacuum at 120 °C. ZetaPotentials were obtained by Malvern Zetasizer Naw ZS90. For the concentration analysis of U(VI), the UV–Visible spectrometry with arsenazo-III as the chromogenic agent was used at an absorptionwavelength of 656 nm. Inductively coupled plasma optical emission spectrometer (ICP-OES, HORIBA, JY 2000-2) was used to analyze the initial and equilibrium concentration of the ions in the multi-ion solution.

SI-3 Synthesis of MMSN and MMSN10N

SI-4 Effect of pH

Fig. S1 Effect of pH in MMSN, MMSN10N and MMSN20N msorbent/Vsolution=0.4 mg mL-1, [U]initial =100 mg L-1

SI-5 Sorption kinetic study

In order to study the sorption kinetic process, we had use the simplified kinetic model, the pseudo-first-order model[1] and pseudo-second-order model[2] to fit U(VI) sorption kinetics:

The pseudo-first-order equation:

(S1)

The pseudo-second-order equation:

(S2)

Where k1，k2 is the sorption rate constant (min−1 for first-order sorption, g mg−1 min−1 for second-order sorption); t is the contacting time (min); qe is the sorption amount at equilibrium time; qt is the sorption amount at time t. Constants and correlation coefficients were shown in Table S1. It can be seen that the experimental values qe are close to the theoretical qe (cal) values calculated from the pseudo-second-order model. Furthermore, the correlation coefficient (R2>0.99) suggesting that the sorption follows pseudo-second-order model process which means the ordinary type of exchange processes and controlled mainly by diffusion[3] .

Fig. S2 (a) Shows linearity between t/qt versus t, an indication of good matching of the experimental kinetics data with pseudo-second-order model; (b) shows linearity between ln(qe-qt) versus t, an indication of not good enough matching of the experimental kinetics data with pseudo-first-order model

Table S1 Kinetics model constants and correlation coefficients for the removal of U(VI)

pseudo-first-order / pseudo-second-order
qe(mg g−1)
58 / k1 (min−1)
1.29×10-2 / R2
0.92 / qe (mg g−1)
155.5 / k2 (g mg−1 min−1)
7.4×10-4 / R2
>0.99

It is known that the sorption process on porous adsorbents is generally described by four stages: bulk diffusion, film diffusion, intraparticle diffusion and sorption on the adsorbents surface[4] . Some of these stages may determine the amount of sorption in the adsorbent and the rate of sorption. Intraparticle diffusion model has been expressed with the equation given by Weber and Morris[5]:

(S3)

Where qt is the sorption amount at time t and kid is the intraparticle diffusion constant (mg g−1 h−1). The plot of qt as a function of t1/2 gives a straight line, from which kid can be acquired.

SI-6 Sorption isotherms study

To verify the sorption type, the batch sorption experiment data were fitted by Langmuir and Freundlich[6] models respectively. From the linear form of these isotherms model, equations can be written as follows:

(S4)

(S5)

where qe is the sorption capacity (mg g-1) at equilibrium time, ce is the equilibrium concentration of U(VI) ions in solution (mgL-1), q0 is the saturated sorption capacity (mg g-1), b is an empirical parameter, kF and n are the Freundlich constants related to the sorption capacity and the sorption intensity, respectively. As we all know, the Langmuir model is an empirical expression used to describe homogeneous monolayer sorption, where sorption activation energy is uniform on the adsorbent surface. The Freundlich model is applicable to a heterogeneous system. Correlation coefficients for the sorption on MMSN10N calculated from Langmuir and Freundlich are listed in Table S2. It can be seen that the sorption results agree well with the Langmuir isotherm with the correlation coefficients >0.99.

Fig. S3 (a) Shows linearity between ce/qe versus ceq, an indication of good matching of the experimental kinetics data with Langmuir model; (b) shows linearity between lnqe versus lnce, an indication of not good enough matching of the experimental kinetics data with Freundlich model

Table S2 Isotherm model constants and correlation coefficients for the removal of U(VI)

Langmuir / Freundlich
q0 (mg g−1)
179.2 / b (L mg−1)
0.5892 / R2
0.99 / KF (mg g−1)
34.9 / n
2.318 / R2
66

SI-7

Fig.S4 Released Fe by HNO3 solutions

SI-8

Table S3 The desorption of U(VI) from MMSN10N

Desorption
[HNO3]a/mol L-1
Efficiency (%)
a Concentration of HNO3in the U( VI)solution / 0.01 0.05 0.1
99% >99% >99%

SI-9 FT-IR characterization

Fig. S5 The FT-IR of adsorbent characterized during the process

SI-10 PXRD characterization

Fig. S6 The low-angle PXRD of sorbent characterized during the process, picture in the right is the low-angle PXRD of desorbed MMSN10N

SI-11 Selectivity Test

Table S4 Compositions of the coexistent ions solution

Coexistent ion / Reagent / Reagent purity
U
Co
Ni
Zn
La
Sm
Sr
Yb
Nd
Gd / UO2(NO3)2·6H2O
Co(NO3)2•6H2O
Ni(NO3)2•6H2O
Zn(NO3)2•6H2O
La(NO3)3•6H2O
Sm(NO3)3•6H2O
Sr(NO3)2
Yb(NO3)3•5H2O
Nd(NO3)3•6H2O
Gd(NO3)3•6H2O / Standard reagent
AR
AR
AR
AR
99.9% metal basis
AR
99.9% metal basis
AR
AR

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