The main functional groups present in both sorbents were
identified by Fourier Transform Infrared (FT-IR) spectrum, which
was recorded on a Mattson 7000 FTIR spectrometer, using KBr
pellets. The spectral range varied from 4000 to 280 cm1. The
structural characteristics of the materials were obtained by
powder X-ray diffraction (XRD) of the dried samples at room
temperature. The spectrum was obtained using a Philips X’Pert Xray
diffractometer equipped with a Cu Ka monochromatic
radiation source, in the range 2u = 3.5–70. The morphological
characteristics were evaluated by Scanning Electron Microscopy
(SEM) using S-4100HITACHI equipment. This system was coupled
with Electron Dispersive Spectroscopy (EDS) allowing the identification
of the most abundant inorganic elements in the samples.
Prior to the SEM analysis, both samples were covered with a thin
layer of carbon and an electron acceleration voltage of 20 kV was
applied. The specific surface area of the particles was determined
with nitrogen adsorption BET measurements performed with a
Gemini V2.0 Micromeritics instrument. The pore size was
calculated from the desorption branch using the Barret–Joyner–
Hallenda method, and the pore volume was evaluated from the
adsorbed amount.