No. ESPR-D-16-02266R2 Supplementary information
Preparation method
Zr-BDC, called UiO-66 in Ref(Chen et al. 2015). Typically, a mixture of zirconium tetrachloride (25 mmol), H2BDC (25 mmol) and hydrochloric acid (HCl, 37%, 25 mmol) in DMF (150 mL) was introduced to a 500 mL Teflon-lined autoclave and heated at 493 K for 16 h. After cooling to room temperature, the white powder was filtered off, washed with DMF, and dried overnight under vacuum at 423 K.
Cr-BDC, named MIL-101(Cr) here(Ahmed et al. 2013). Typically, a mixture of Cr(NO3)3·9H2O (25.0 mmol), H2BDC (25.0 mmol), HF (25.0 mmol) in water (120mL) were heated at 493 K for 8h ,then washed with DMF and ethanol, and dried overnight under vacuum at 423 K.
Fe-BDC, named MIL-53(Fe) here(Gordon et al. 2015). In a typical procedure, FeCl3·6H2O (1 mmol) and H2BDC (1 mmol) were added into DMF (5 mL). After stirred for 10 min, the mixture was heated at 423 K for 2 h in a Teflon-lined stainless steel autoclave. The products are collected by centrifugation at 6000 rpm for 2 min. To remove the solvent, the obtained yellow powder was suspended in distilled water (200 mL) overnight, and then it was centrifuged and dried in vacuum at 333 K for 24 h.
Zn-BDC, named MOF-5 here(Shim et al. 2012). Typically, a mixture of Zn(NO3)2·6H2O (1.189 g) and terephthalic acid (0.332g) were dissolved in DMF (50 mL) under magnetic stirring. After complete dissolution, triethylamine (2.2 mL) was added dropwise under vigorous stirring. After completed adding, continue to stir 30 ~ 45 min, the product was collected by filtration and washed with DMF, and dried at 373K for 3～5 h.
Zn-imidazolate-2-methyl named ZIF-8 here(Wu et al. 2015). A mixture of Zn(NO3)2·6H2O (0.225 g) and 2-methylimidazolate (0.622g ) were dissolved in methanol (23 mL) under ultrasound, the reaction was allowed to proceed at 323 K for 3 h for ZIF-8 crystal growth. Finally, the product was separated by the use of vacuum filtration, and washed with ethanol, then dried at 353K overnight.
Zn-BDC-NH2, named IRMOF-3 here(Wang et al. 2014). A mixture of 2-amino-1,4-benzene dicarboxylate (0.0906g) and Zn(NO3)2·6H2O (0.5950g) were dissolved in 5mL of DMF, respectively. Then the above solution was mixed and ultrasound 5 min. The mixture was introduced in the hydrothermal bomb and was heated to 383 K for 48 h, and then cooled to room temperature. The solid was filtered and thoroughly washed with DMF then dried at 353K for 4h. Three zinc-based MOFs were all placed in a desiccator before use.
Table 3. Textural properties of the MOFs
MOFs / BET surface area (m2/g) / Total pore volume (cm3/g)ZIF-8 / 1310 / 1.3120
MOF-5 / 970 / 0. 410
IRMOF-3 / 965 / 0.1571
UiO-66 / 1188 / 0.4844
MIL-101(Cr) / 1719 / 0.8059
MIL-53(Fe) / 12 / 0.0445
Table 4. Maximum adsorption capacity (qm) of ZIF-8 and other adsorbents for the aqueous phase adsorption of Pb(II).
Entry / Adsorbents qm(mg/g) / References1 / ZIF-8 449.0 / This study
2 / MOF-5 211.0 / This study
3 / IRMOF-3 75.20 / This study
4 / NH2 functional mesoporous silica 89.00 / (Machida et al. 2012)
5 / Coconut-shell carbon 26.50 / (Sekar et al. 2004)
6 / Carbon nanotubes 49.95 / (Li et al. 2002)
7 / Lead(Ⅱ)ion imprinted polymer 19.44 / (Shao et al. 2013)
8 / Fe3O4@SBA-15-NH2 149.2 / (Wang et al. 2015)
Fig.7 the Energy Dispersive Spectrometer of ZIF-8 after adsorption of Pb(II).
References
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