Supplementary Material
Effect of pH on Cu(II) crystal growth onto the surface of chelating fiber
Young Gun Ko and Ung Su Choia)
Energy Mechanics Center, Korea Institute of Science and Technology, Hwarangno 14-gil, Seongbuk-gu,
Seoul 136-791, Korea
a)Author
1.
to whom correspondence should be addressed. Electronic mail: uschoi@kist.re.kr.
Preparation
of
poly(acryloamidino ethyleneamine) (PAEA) and
poly(acryloamidino
diethylenediamine) (PADD)
PAEA was obtained via the heating of PAN fiber (6 g) with EDA (450 g) and AlCl3·6H2O (20 g) at
110 °C for 2 h with stirring (degree of substitution = 98%, adsorption capacity = 7.8 mequiv/g). Excess
EDA was used as a solvent and reactant. The modified PAN fiber, so obtained, was washed with
distilled water and ethyl alcohol and then dried at 40 °C in vacuo. PADD was obtained in a similar
manner via the heating of PAN fiber (6 g) with DETA (500 g) and AlCl3·6H2O (20 g) at 120 °C for 3 h
with stirring (degree of substitution = 97.2%, adsorption capacity = 11.4 mequiv/g). DETA was used as
a solvent and reactant. The modified PAN fiber, so obtained, was washed with distilled water and ethyl
alcohol and then dried at 40 °C in vacuo.
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2. Analysis
2.1. Fourier transform infrared (FT-IR) spectroscopy
Samples of the PAN fiber, PAEA fiber, and PADD fiber were cut into approximately 1 mm pieces,
blended with KBr, and then pressed into disks for analysis. FT-IR spectroscopy (GX FTIR,
PerkinElmer) was used to analyze these fibers under nitrogen gas purging.
2.2. X-ray photoelectron spectroscopy (XPS)
XPS analyses of the Cu(II) adsorbed PAEA and PADD fibers at various adsorption times were
carried out on a PHI 5800 (Physical Electronics Instruments) with an Al Kα X-ray source (1486.71 eV
of photons) to determine the adsorption of copper atoms on the surfaces of PAEA and PADD. The Xray source was run at a reduced power of 350 W, and the pressure in the analysis chamber was
maintained at less than 10-8 Torr during each measurement. All binding energies were referenced to the
neutral C1s peak at 285 eV to compensate for the surface-charging effects.
2.3. X-ray diffraction (XRD)
The XRD patterns were obtained on a diffractometer (RINT/DMAX 2500, Rigaku, Japan) with a
high-power Cu Kα source operating at 40 kV and 126 mA.
2.4. Field-emission scanning electron microscopy (FE-SEM)
The Cu(II) crystals growth was observed with FE-SEM (S4200, Hitachi) at 15.0 kV.
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2.5. Quantitative analysis of adsorbed Cu(II) ions on PAEA and PADD
pH-adjusted solutions (100 mL) of 10 mM Cu2+ and PAEA (0.1 g) or PADD (0.1 g) were placed in
Erlenmeyer flasks and shaken for 24 h (200 rpm). The metal ion concentrations in the solutions were
back-titrated with an atomic absorption spectrophotometer (SpectrAA-800, Varian). Cu2+ adsorbed
PAEA and PADD were dried at 40 °C in a vacuum oven and analyzed with XPS and XRD. They were
also examined with FE-SEM. The pHs of the solutions were adjusted with 0.1 N HCl and concentrated
HCl.
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3. Experimental Results
Fig. S1. FT-IR spectra of (a) PAN, (b) PAEA, and (c) PADD fibers.
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Fig. S2. Isotherm curves of Cu(II) adsorbed on PAEA and PADD fibers at various (a) times
(concentration of Cu2+: 10 mM) and (b) concentrations (adsorption time: 24 hr).
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Fig. S3. XRD patterns over the course of Cu(OH)2 crystal growth on the surfaces of (a) PAEA and (b)
PADD. The elapsed times were 0 s, 2 min, 4 min, 16 min, 1 h, 4 h, and 20 h. The asterisk indicates
(RNH3)2CuCl4·2H2O (JCPDS no. 25:0262), and the pound sign indicates Cu(OH)2 (JCPDS no.
35:0505).
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Fig. S4. XPS spectra of Cu2p3/2 over the course of Cu(II) crystal growth on the surface of PAEA. The
elapsed times were 0 s, 16 min, 1 h, 4 h, and 20 h.
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