Supporting Information for

Transcription

1 Supporting Information for Controllable Synthesis of Ca-Mg-Al Layered Double Hydroxides and Calcined Layered Double Oxides for the Efficient Removal of U(VI) from Wastewater Solutions Yidong Zou a,b, Xiangxue Wang b, Fen Wu c, Shujun Yu b, Yezi Hu b, Wencheng Song b, Yunhai Liu a*, Hongqing Wang d, Tasawar Hayat e, Xiangke Wang b,d,e* a School of Chemistry, Biological and Materials Sciences, East China Institute of Technology, Nanchang, , P. R. China b School of Environment and Chemical Engineering, North China Electric Power University, Beijing , P. R. China c School of Materials Engineering, Shanghai University of Engineering Science, P.O. Shanghai, , P.R. China d School of Chemistry and Chemical Engineering, University of South China, 28 Changsheng West Road, Henyang, Hunan , P.R. China e NAAM Research Group, Faculty of Science, ing Abdulaziz University, Jeddah 21589, Saudi Arabia *: Corresponding author. xkwang@ipp.ac.cn (X. Wang); Tel: ; Fax: The SI contains 7 pages with 5 Figures and 6 Tables. 22 S1

2 Materials. Calcium nitrate tetrahydrate (Ca(NO 3 ) 2 4H 2 O), magnesium nitrate hexahydrate (Mg(NO 3 ) 2 6H 2 O), aluminium nitrate nonahydrate (Al(NO 3 ) 3 9H 2 O), sodium nitrate (NaNO 3 ), urea (> 99 %), uranyl nitrate (UO 2 (NO 3 ) 2 ), sodium carbonate (NaCO 3 ), sodium hydroxide (NaOH), and nitric acid (HNO 3, 68%) were obtained from Sinopharm Chemical Reagent Co., Ltd. Milli-Q water (18.25 MΩ cm -1 ) was applied across the whole experiments. Synthesis of Ca-Mg-Al-LDH and Ca-Mg-Al-LDO x Nanomaterials. All the chemicals used in the experiments were purchased in analytic purity and used without any further purification. Ca-Mg-Al-LDH was fabricated by a typically facial-cheap hydrothermal method. Generally, 19.2 g urea, 4.5 g Al(NO 3 ) 3 9H 2 O, 4.1 g Mg(NO 3 ) 2 6H 2 O and 1.9 g Ca(NO 3 ) 2 4H 2 O were slowly added into the 40 ml Milli-Q water mixture solution. The mixture was stirred for 3 h and then sealed in a Teflon-lined stainless-steel autoclave (80 ml capacity) and the autoclave was heated to 140 C and maintained for 36 h, and then setting the temperature at 80 0 C in order to well crystallizate. The Ca-Mg-Al-LDH powder was formed and washed with Milli-Q water (18.25 MΩ cm -1 ) and alcohol for several times, centrifuged and vacuum dried at 60 C overnight. Ca-Mg-Al-LDO x (x: 200, 300, 400, 500 and C) was fabricated by calcination process under different temperatures. Typically, 0.6 g pure Ca-Mg-Al-LDH was fully grinded and mixed, and then added into a uniform porcelain crucible. Using a muffle to calcine the as-prepared Ca-Mg-Al-LDH product at various temperatures, and contained the temperature 3 h, and then the power was washed with Milli-Q water for several times and vacuum dried at 40 C overnight. 46 S2

3 47 48 Table S1. Relative Elemental Distribution Percentages of EDS analysis for Ca-Mg- Al-LDH, Ca-Mg-Al-LDO 300 and Ca-Mg-Al-LDO 600. Atomic % Ca Mg Al O Ca-Mg-Al-LDH 0.28% 60.60% 13.81% 25.31% Ca-Mg-Al-LDO % 10.91% 23.8% 64.58% Ca-Mg-Al-LDO % 5.13% 34.76% 58.85% Table S2. Relative Contents of Various Elements in Ca-Mg-Al-LDH, Ca-Mg-Al- LDO 300 and Ca-Mg-Al-LDO 600 Charactrized from XPS Analysis. Samples Mg 2p Al 2p Ca 2p3 O 1s C 1s Ca-Mg-Al-LDH 3.20 % % 0.71 % 51.5 % % Ca-Mg-Al-LDO % % 1.36 % % % Ca-Mg-Al-LDO % 18.3 % 1.16 % % % Table S3. Relative Contents of Various Metal-Oxide Bonds in Ca-Mg-Al-LDH, Ca- Mg-Al-LDO 300 and Ca-Mg-Al-LDO 600 Charactrized from XPS Analysis (O 1s Spectrum). Samples Ca-O Al-O Mg-O Peak Contents Peak Contents Peak Contents Ca-Mg-Al-LDH ev 3.54 % ev % ev % Ca-Mg-Al-LDO ev 5.33 % ev % ev % Ca-Mg-Al-LDO ev 8.83 % ev % ev % 56 S3

4 Figure S1. Energy-dispersive spectroscopy (EDS) results of Ca-Mg-Al-LDH (a), Ca-Mg- Al-LDO 300 (b) and Ca-Mg-Al-LDO 600 (c). 60 S4

5 61 62 Figure S2. Distribution coefficients ( d ) of U(VI) on various adsorbents, C [U(VI)initial] = 30 mg/l, ph = 5.0 ± 0.1, I = 0.01 NaNO Table S4. Parameters of Adsorption Isotherms of U(VI) on Ca-Mg-Al-LDH, Ca-Mg- Al-LDO 300 and Ca-Mg-Al-LDO 600 at Three Temperatures (298.15, , and ). Adsorbents Langmuir model Freundlich model Sips model Parameters Ca-Mg-Al-LDH Ca-Mg-Al-LDO 300 Ca-Mg-Al-LDO L (L mg -1 ) C s,max1 (mg g -1 ) R F (mg 1-n L n g -1 ) /n F R S (L g -1 ) a s (L mg -1 ) /n s C s,max2 (mg g -1 ) R S5

6 Figure S3. Linear plots of ln d vs Ce for the adsorption of U(VI) on Ca-Mg-Al-LDH (a), Ca-Mg-Al-LDO 300 (b) and Ca-Mg-Al-LDO 600 (c). Linear plots of ln 0 vs 1/T for the adsorption of U(VI) (d), m/v = 0.1 g/l, ph = 5.0 ± 0.1, I = 0.01 NaNO 3. Table S5. Thermodynamic Parameters of U(VI) Adsorption on Ca-Mg-Al-LDH, Ca- Mg-Al-LDO 300 and Ca-Mg-Al-LDO 600 at Various Temperatures (298.15, , and ). Adsorbents ΔH 0 (kj mol -1 ) ΔS 0 (J mol -1-1 ) ΔG 0 (kj mol -1 ) Ca-Mg-Al-LDH Ca-Mg-Al-LDO Ca-Mg-Al-LDO Figure S4. Pseudo-first order kinetic plots of U(VI) on Ca-Mg-Al-LDH, Ca-Mg-Al- LDO 300 and Ca-Mg-Al-LDO 600. m/v = 0.1 g/l, ph = 5.0 ± 0.1, I = 0.01 NaNO S6

7 Figure S5. Pseudo-second order kinetic plots of U(VI) on Ca-Mg-Al-LDH, Ca-Mg-Al- LDO 300 and Ca-Mg-Al-LDO 600. m/v = 0.1 g/l, ph = 5.0 ± 0.1, I = 0.01 NaNO Table S6. inetic Parameters for U(VI) Adsorption on Ca-Mg-Al-LDH, Ca-Mg-Al- LDO 300 and Ca-Mg-Al-LDO 600. Pseudo-first-order Pseudo-second-order Adsorbents q 1,cal k f (mg g -1 ) (min -1 ) R 2 q 2,cal k s (mg g -1 ) (g mg -1 min -1 ) Ca-Mg-Al-LDH Ca-Mg-Al-LDO Ca-Mg-Al-LDO R 2 S7