2.2. Apparatus
Cadmium and copper concentration was determined by an
AA-680 Shimadzu (Kyoto, Japan) flame atomic absorption spectrometer
(FAAS) in an air–acetylene flame, according to the user’s
manual, provided by the manufacturer. Cadmium and copper
hollow cathode lamp was used as the radiation source withwavelength of 228.8 and 324.8 nm, respectively. The pH was measured
at 25
±
1 ◦C with a digital WTW Metrohm 827 Ion analyzer
(Herisau, Switzerland) equipped with a combined glass–calomel
electrode. A peristaltic pump was obtained from Leybold (Cologne,
Germany) and an adjustable vacuum gauge and controller were
obtained from Analytichem International (Harber City, CA). The
adjustable vacuum gauge allowed the control of the flow rate
during extraction. The CHN analysis was performed on a Thermo
Finnigan Flash EA112 elemental analyzer (Okehampton, UK). IR
spectra were recorded on a Bruker IFS-66 FT-IR spectrophotometer.
BET surface areas measured by nitrogen adsorption technique
using a Micromeritics ASPS 2010 analyzer. Low angle X-ray diffraction
patterns were obtained on a Philips-PW 17C diffractometer
with Cu K radiation. The transmission electron microscopy (TEM)
images were taken on a JEOL JEM-2100F field emission transmission
electron microscope.