3.1.1. FTIR analysis
The investigation of surface functional groups was carried out using
FTIR analysis for four membranes (i.e. neat polymeric, layer-deposited
nanocomposite and blended nanocomposite membranes), shown in
Fig. 4. A peak at the wave number of 600 cm−1 was observed in iron
oxide nanoparticle spectra (Fig. 4(b)), which belongs to FeO
group of iron oxide [48]. The absence of this peak in the spectrum
of neat polymeric membranes (Fig. 4(a)) along with its presence in
the spectrum of each of the three nanocomposite membranes
(BNM, IPNM, and PPNM) confirms the presence of iron nanoparticles
in the structure of nanocomposite membranes. In addition, the
higher peak intensity for IPNM (Fig. 4(d)) and PPNM (Fig. 4(c))
than BNM (Fig. 4(e)) membrane implies the presence of more nanoparticles on the surface of deposited membranes than that of blended
nanocomposite membranes
The existence of a peak in the range of 3400 cm−1 is related to the
surface hydroxyl group of metal oxides [48] that indicates the presence
of nanoparticles on the surface of nanocomposite membranes and their
hydrophilicity. Furthermore, in the IPNM membrane range, the observable peaks at wave numbers of 1660 and 1548 cm−1 are related to
NC_O and amid CNH groups, respectively [49]. This, in turn, confirms the presence of polyamide layer on the membrane surface. In the
PPNM membrane range, the existing peaks at 3400 and 1600 cm−1
wave numbers are related to hydroxyl and carbonyl of acrylic acid,
respectively [50] and confirm the existence of polyacrylic acid layer on
the membrane surface