## 3 Results and Discussion
### Characteristics of the Amine Immobilized GMA-g-NWF and IRP
#### 3.3.3 Adsorption Mechanism  
X-ray photoelectron spectra of the IRP samples after adsorption with Cu ion was analyzed to verify the presence of metal ion into the polymer matrix. Thus, only the IRP samples subjected to XPS analysis. O1s and N1s orbitals were detected in EDA-IRP, DETA-IRP, TETA-IRP, and TEPA-IRP samples. The result obtained showed in Figure 8i-iv. Strong peak was observed at 399.48 eV and 400.37 eV in the N1s and N2s, which indicates primary and secondary amine groups of EDA, DETA, TETA, and TEPA, respectively [40]. The O1s spectrum of EDA-IRP, DETA-IRP, TETA-IRP, and TEPA-IRP samples shows the presence of oxygen bonding as such C-O and C=O at a binding energy of 531.70 and 533.22 eV, originating from the functional monomer, GMA [41]. The O1s spectrum of all IRP samples exhibits a broad distribution at higher binding energy due to the presence of oxygen bonded carbon and Cu concurrently in the IRP samples. The main peak at 531.70 eV attributes to the present of C-O along with binding energy at 530.30 eV indicates the existence of CuO. The XPS performed onto IRP samples had verify the chemical concentration of the samples after adsorption of Cu ion into polymer matrix. Conclusively, clear evidence was obtained on adsorption of Cu ions onto IRP samples which attribute to detection of CuO that allowed carbonyl groups from GMA to bond with.  
Figure 8: _Cont._  
Figure 7: Selectivity ratio of amine immobilized (**a**) GMA-\(g\)-NWF and (**b**) IRP samples versus time at experimental condition of initial Cu concentration: 10 mg/L, adsorbent dose: 0.02 g, temperature: 30 \({}^{\circ}\)C, amine density: 2.0–2.2 mmol/g-ad, stirring speed: 200 rpm and adsorbate volume: 100 mL.  
The local coordination environment of metal ions can be selectively investigated with XAFS spectroscopy [42]. XAFS is also capable of determining distances, the coordination number, and the types of atoms surrounding the metal centers [43]. This XAFS information on metal system could be interpreted by fitting structurally well-characterized model complexes as a reference XAFS experimental data [44]. In this study, XAFS was used to investigate the molecular structure of surface complexes of Cu (II) adsorbed onto both amines immobilized GMA-\(g\)-NWF and IRP samples which had been modified with a different aliphatic amine, EDA, DETA, TETA, and TEPA, respectively. The structural parameters of both amines immobilized GMA-\(g\)-NWF, and IRP complexes were determined from the extended X-ray absorption fine structure (EXAFS) spectra and have been reported in Table 5. The main aim of this analysis was to determine the structural changes in metal complexes after radiation  
Figure 8: XPS spectra of (**i**) EDA-IRP, (**ii**) DETA-IRP, (**iii**) TETA-IRP and (**iv**) TEPA-IRP  
crosslinking process with DVB along with different aliphatic polyamine. Based on the fitting of EXAFS spectra, the Cu-O (at \(\sim\)4.2 A) and Cu-N (at \(\sim\)2.0 A) shells were observed in the Cu (II) adsorbed onto for both amine immobilized GMA-\(g\)-NWF and IRP samples. This observation indicating the formation of inner-sphere complexes on amine immobilized GMA-\(g\)-NWF and IRP samples surfaces. Different fitting values obtained for \(\Delta\)R indicates a similar path for both amines immobilized GMA-\(g\)-NWF and IRP complexes, Cu-O and Cu-N. Moreover, the \(\Delta\)R defined for the two axial Cu-O and Cu-N paths for all the amine immobilized GMA-\(g\)-NWF and IRP complexes. It is clear that Cu-O and Cu-N paths have effective contributions to the experimental EXAFS data. This finding agrees with XPS results of IRP samples as discussed previously. The outcome from this study supported by another study which reported on EXAFS investigation on Cu(II) complexes [10].