Efficient removal of uranium(VI) from aqueous systems by heat-treated carbon microspheres

Xiaofei Zhang,a Jun Wang,a, b, *, Rumin Li,a Qi Liu,a Lei Li,a Jing Yu,a Milin Zhang,a Lianhe Liub

a Key Laboratory of Superlight Material and Surface Technology, Ministry of Education, Harbin Engineering University, Harbin 150001, PR China.

b Institute of Advanced Marine Materials, Harbin Engineering University, 150001, China.

* Corresponding author: Tel.: +86 451 8253 3026; fax: +86 451 8253 3026.

E-mail address:


Figure S1. EDS spectra of carbon microspheres (a), heat-treated carbon microspheres (b) and the adsorption of uranium(VI) on heat-treated carbon microspheres (c).

Figure S2. Pseudo-second-order (A), intra-particle diffusion (B) plots for the removal of uranium(VI) by heat-treated carbon microspheres. Initial uranium concentration 100 mg L-1; pH 6.0; temperature 25_35 °C; amount of heat-treated carbon microspheres 0.01 g.

Figure S3. Adsorption isotherm of heat-treated carbon microspheres for uranium(VI) at different temperatures. pH 6.0; temperature 25_55 °C; amount of heat-treated carbon microspheres 0.01 g.

Figure S4. Relationship curve between ln Kd and 1/T.
Table S1. EDS analysis results of carbon microspheres, heat-treated carbon microspheres, and uranium(VI)-adsorbed-heat-treated carbon microspheres.

Samples / Carbon (Wt. %) / Oxygen (Wt. %) / Uranium (Wt. %)
carbon microspheres / 77.18 / 22.82 / 0
100 °C / 70.92 / 29.08 / 0
200 °C / 68.41 / 31.59 / 0
300 °C / 67.31 / 32.69 / 0
300 °C – U(VI) adsorption / 65.52 / 31.74 / 2.74

Table S2. Kinetic parameters of different models for uranium(VI) ions adsorption onto heat-treated carbon microspheres.

Kinetic models / parameters / 25°C / 35°C
Pseudo-second-order / qe (calc.) (mg L−1) / 93.72 / 126.26
k2 (g mg−1 min−1) / 0.0100 / 0.0104
R2 / 0.98 / 0.99
Intra-particle diffusion / kid (mg g−1 min−1/2) / 26.66 / 25.98
C / 11.39 / 49.74
R2 / 0.99 / 0.92

Table S3. Surface area, pore volume and average pore radius of carbon microspheres and heat-treated carbon microspheres.

Characteristics / carbon microspheres / heat-treated carbon microspheres
Surface area (m2 g-1) / 9.00 / 14.31
Pore volume (cm3 g-1) / 0.018 / 0.022
Average pore radius (nm) / 8.14 / 6.03

Table S4. Composition of the artificial seawater.

Electrolytes / Concentration (mol/kg)
NaCl / 0.4104
Na2SO4 / 0.02824
KCl / 0.00937
MgCl2 / 0.05282
CaCl2 / 0.01028
SrCl2 / 0.00009
KBr / 0.00084
B(OH)3 / 0.00041
NaF / 0.00007
NaHCO3 / 0.00226

Table S5. Adsorption capacity of uranium(VI) on pristine and modified carbon microspheres.

Carbonization temperature (°C) / none / 100 / 200 / 300
Adsorption capacity (mg g-1) / 57.80 ± 1.00 / 73.27 ± 1.93 / 83.61 ± 2.19 / 91.70 ± 1.10

Table S6. Adsorption capacity of different adsorbents for uranium(VI).

Adsorbents / Capacity (mg g−1) / Ref.
Activated carbon (Merck) / 28.30 / Mellah et al.
Activated carbon prepared from charcoal / 28.5 / Kutahyali and Eral
Biochar / 4 / Kumar et al.
Nanoporous carbons functionalized with carboxymethylated polyethyleneimine / 151.5 / Jung et al.
Carboxylate-functionalized poly(hydroxy ethylmethacrylate)-grafted lignocellulosics / 109.6 / Anirudhan et al.
Alumina / 78 / Sylwester et al.
Amorphous silica / 58 / Stamberg et al.
Montmorilonite / 24 / Sylwester et al.
Hematite / 3.36 / Xie et al.
Manganese oxide coated zeolite / 15.1 / Han et al.
Heat-treated carbon microspheres / 92.08 / This work

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