# Novel ZIF-67@Bentonite (ZIF-67@BNT) Nanocomposite for Aqueous Methyl Orange Removal
## 3 Results and Discussion
### Analysis of Methyl Orange Adsorption Using ZIF-67@BNT
#### 3.3.4 Post-Analysis of MO Adsorption on ZIF-67@BNT Nanocomposite  
Fourier transform infrared (FTIR) spectra of ZIF-67@BNT before and after methyl orange adsorption were analyzed to investigate the changes in functional groups and interactions involved in the adsorption process. The findings as shown in Figure 14 exhibit the effects of methyl orange adsorption on the nanocomposite's functional groups. The spectrum before adsorption exhibited a broad peak around 3400 cm\({}^{-1}\), corresponding to the stretching vibrations of hydroxyl (-OH) groups, which are typically associated with adsorbed water molecules and surface hydroxyl groups in BNT [69]. Peaks observed from 2900-3100 cm\({}^{-1}\) can be attributed to C-H stretching vibrations from organic components in the ZIF-67 framework [58; 70], while the band around 1600-1700 cm\({}^{-1}\) corresponds to C = O stretching or H-O-H bending vibrations [71]. Additionally, strong peaks in the range of 1000-1500 cm\({}^{-1}\) are characteristic of metal-oxygen (Co-O, Al-O-Si) stretching and bending vibrations from the BNT structure and ZIF-67 framework. The region below 1000 cm\({}^{-1}\) represents metal-ligand interactions, specifically Co-N stretching in ZIF-67 [72; 73]. After methyl orange adsorption, notable spectral changes were observed, confirming the interaction between the adsorbent and the dye molecules. A shift and reduction in the intensity of the hydroxyl (-OH) peak at \(\sim\)3400 cm\({}^{-1}\) suggest possible hydrogen bonding between the dye and surface hydroxyl groups of ZIF-67@BNT [74]. The emergence of new peaks and enhanced intensities in the 1500-1650 cm\({}^{-1}\) region correspond to the aromatic C=C stretching and sulfonate (-SO\({}_{3}\)\({}^{-1}\)) vibrations of methyl orange, indicating its successful attachment to the surface of ZIF-67@BNT [75]. Furthermore, broadening and shifts in the 1000-1200 cm\({}^{-1}\) region suggest interactions between the BNT structure and methyl orange functional groups, likely through electrostatic attractions or coordination interactions with Co\({}^{2+}\) sites in ZIF-67. Additionally, changes in the fingerprint region (below 1000 cm\({}^{-1}\)) indicate modifications in the metal-ligand framework due to adsorption. The observed spectral changes suggest that the adsorption of methyl orange onto ZIF-67@BNT occurs through multiple mechanisms, including electrostatic interactions between the negatively charged sulfonate (-SO\({}_{3-}\)) groups of methyl orange and the positively charged Co\({}^{2+}\) or Al\({}^{3+}\) sites in ZIF-67@BNT and hydrogen bonding between hydroxyl groups of BNT and methyl orange molecules [76].  
These interactions validate the effectiveness of ZIF-67@BNT as an adsorbent for methyl orange, highlighting its potential utility in applications aimed at removing organic dyes from contaminated water. Furthermore, the noted stability and adsorption efficiency support the nanocomposite's reusability and robustness, making it a promising candidate for practical environmental remediation efforts [75].  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline  & & \multicolumn{6}{c}{**Models**} \\ \hline
**Langmuir Adsorption Isotherm** & \multicolumn{6}{c}{**Freundlich**} & \multicolumn{6}{c}{**H**e**e**t**a**t**