To observe the changes of the position and the intensity of the
maximum absorption wavelength, the absorbance of CIP and CIP
with Ni(II) solutions at wavelength of 200–700 nm was determined
by an UV–visible spectrophotometer (UV2450, SHIMADZU).
The results are shown in Fig. S1. As can be seen, the maximum
absorption wavelength of CIP was 275 nm, which was consistent
with previous studies [12,15]. With the addition of Ni(II), the
maximum absorption wavelength still maintained at 275 nm.
Thus, the detector wavelength was set at 275 nm. However, the
addition of Ni(II) slightly increased the absorbance at maximum
absorption wavelength, which was attributed to the formation of
complex of CIP–Ni(II). The solution before and after adsorption was
recorded to determined the removal rate and adsorption capacity.
All adsorption data were collected in triplicate.
The concentration of CIP was analyzed by a UV-754 UV/visible
spectrophotometer at the maximum absorption wavelength of
275 nm and Ni(II) by atomic absorption spectrophotometer
(Beijing Purkinje General Instrument Co., China).