## 3 Results and Discussion
### Characterization of the EGS@APTES-GT Hybrid Adsorbent
#### 3.1.3 Structural Characterization (FTIR and XRD Analysis)  
The FTIR spectrum of the pure expanded glass spheres (EGS), amino-functionalized expanded glass spheres (EGS@APTES) and one with precipitated goethite (EGS@APTES-GT), before and after arsenate and Iprodione adsorption, are presented in Figure 5a.  
Figure 4: Mapping of element concentration distribution at the cross-section of the EGS@APTES-GT sphere (**a**) and iron concentration distribution at the intersection of sphere (**b**).  
The FTIR spectra of EGS (Figure 5a) show the characteristic vibration of the Si-O-Si and Si-O bands around 940 cm\({}^{-1}\) and 775 bands, respectively [42; 43]. The new broad peak at 3200 cm\({}^{-1}\) in the spectrum of EGS modified with APTES and goethite presents the stretching vibrations of the N-H and O-H groups, respectively [45]. In addition, the new bands observed at 2925-2852/1481-1346 and 1564/692 cm\({}^{-1}\) were assigned to the C-H stretching/bending vibrations of the methyl and methylene groups and the N-H bending/deformations of amino groups in EGS@APTES, respectively. The intensity of these peaks decreases with the concomitant appearance of a new peak at 1630 cm\({}^{-1}\), assigned to the bending vibration of the O-H groups in Fe-OH in EGS@APTES-GT.  
The increased intensity of the band at 775 cm\({}^{-1}\) in EGS@APTES-GT/As(V) (Figure 5a) is due to arsenate oxyanion complexation with OH groups at the adsorbent surface by forming an As-O-Fe bond [44]. Further, differences in the peak intensity, peak shifting, and appearance of the peak in the 1420-1355 cm\({}^{-1}\) region indicate different arsenate bonding interactions with surface functionalities. In the FTIR spectrum of EGS@APTES-GT/Iprodione, the appearance of new peaks confirms Iprodione effective removal. The bands in the 1776-1574 cm\({}^{-1}\) region is attributed to different carbonyl groups' (Figure 5a) stretching vibrations from the adsorbed Iprodione structure. The symmetric stretching vibrations of the C=C group in the aromatic ring skeleton appear at 1536 cm\({}^{-1}\), while one located at 1438 cm\({}^{-1}\) was attributed to the pseudo-symmetric N-C=O stretching in the imidazolodine-2,4-dione moiety. The deformation vibrations of the isopropyl group are observed at 1363 cm\({}^{-1}\)[36]. Due to the complexity of the Iprodione structure, the presence of 3,5-dichlorophenyl, 2,4-dioximidazoleidine, carboxamide, and isopropyl functionalities (Figure S1) contributes to the attainment of a different interaction with EGS@APTES-GT surface functionalities. The presence of the dipolar/polarizable structure of 3,5-dichlorophenyl and 2,4-dioximidazoleidine, proton-accepting sites in 2,4-dioximidazoleidine and carboxamide moieties, and proton-donating sites in amide groups and non-polar isopropyl groups contributes to wealth adsorbate/adsorbent interfacial interactions. It is assumed that the electrostatic attraction of the negatively charged species and the positive adsorbent surface plays a dominant role in the adsorption process [48].  
A diffractogram of the prepared hybrid adsorbent is presented in Figure 5b. The analysis results of EGS@APTES-GT confirm the presence of goethite and the \(\alpha\)-FeOOH  
Figure 5: FTIR spectra of EGS, EGS@APTES, and EGS@APTES-GT before and after As(V) and Iprodione adsorption (a), and XRD pattern of EGS@APTES-GT (b).  
phase with peaks at the diffraction angles of 21.1\({}^{\circ}\), 26.3\({}^{\circ}\), 33.2\({}^{\circ}\), 45\({}^{\circ}\), 53.1\({}^{\circ}\), and 59\({}^{\circ}\) as the most apparent, in accordance with JCPDS PDF No. 01-081-0463 [49]. EGS are mainly based on silica crystalline phases, such as quartz.