# 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  
#### 3.3.1 Experimental Design and Analysis of Variance  
Results from the MO adsorption experiments conducted using the ZIF-67@BNT nanocomposite are given in Table 2. The adsorption findings show that the uptake of MO by ZIF-67@BNT is a function of the process parameters. Also, the MO adsorption capacity using ZIF-67@BNT ranges from 38 to 187 mg/g, indicating that the MO removal can be significantly enhanced and optimized by varying the process conditions. Furthermore, among the various RSM-based models generated, the quadratic model fitted well to the noted MO adsorption results using ZIF-67@BNT, as given below (Equation (7)):  
\[\text{adsorption capacity (mg/g)}=2.57351+0.185881\text{A}+0.057277\text{B}+0.115436 \text{C}-0.002436\text{AB}-0.009655\text{A}^{2} \tag{7}\]  
The R\({}^{2}\), adjusted R\({}^{2}\), and predicted R\({}^{2}\) values for the present RSM model were noted to be 0.953, 0.927, and 0.822, respectively. The quadratic model's (Equation (7)) suitability is thus demonstrated by less than 20% difference between the adjusted and predicted R\({}^{2}\) values [59]. This is also supported by the actual and predicted MO removal as given in Figure 8a. Further, some other statistical parameters for the suggested RSM model (Equation (7)) are also provided in Table 3. The ANOVA findings as shown in Table 3, with a \(p\)-value of 0.05 or less, also support the suggested RSM-based model for MO adsorption by ZIF-67@BNT. Furthermore, the Box-Cox plot for total MO removal (Figure 8b), Figure 8c that illustrates that the residuals have a normal distribution, and Figure 8d that reveals an absence of correlation between the run sequence and residuals (as shown by the random dispersion of points in the plot) also support the suggested RSM-based model's (Equation (7)) suitability to predict the MO uptake by the novel ZIF-67@BNT under a varying set of process conditions.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Run**} & **A: Adsorbent** & **B: Methyl** & **C: Time** & **adsorption** \\  & **Dose (mg)** & **Orange (mg/L)** & **(Hours)** & **Capacity (mg/g)** \\ \hline
1 & 15 & 30 & 5 & 82 \\
2 & 5 & 20 & 3 & 89 \\
3 & 15 & 30 & 1 & 46 \\
4 & 10 & 20 & 5 & 105 \\
5 & 10 & 10 & 3 & 62 \\
6 & 5 & 10 & 5 & 84 \\
7 & 10 & 20 & 3 & 85 \\
8 &  
Figure 8: The RSM Model (for MO adsorption by ZIF-67@BNT) check plots. (**a**) Predicted Vs. Actual adsorption capacity, (**b**) Box-Cox plot, (**c**) Normality distribution plot, and (**d**) Residuals Vs. Run plot.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Source**} & \multirow{2}{*}{**Sum of Squares**} & \multicolumn{2}{c}{**Degree of**} & \multirow{2}{*}{**Mean Square**} & \multirow{2}{*}{**F-Value**} & \multirow{2}{*}{**\(p\)-Value**} \\  & & **Freedom (df)** & & & \\ \hline Model & 2.71 & 5 & 0.5424 & 36.79 & \textless{}0.0001 & Significant \\ A: Adsorbent dose & 0.7823 & 1 & 0.7823 & 53.06 & \textless{}0.0001 & \\ B: Methyl Orange & 1.08 & 1 & 1.08 & 73.49 & \textless{}0.0001 & \\ C: Time & 0.5330 & 1 & 0.5330 & 36.15 & \textless{}0.000 & \\ AB & 0.1187 & 1 & 0.1187 & 8.05 & 0.0002 & \\ A\({}^{2}\) & 0.1942 & 1 & 0.1942 & 13.17 & 0.0195 & \\ Residual & 0.1327 & 9 & 0.0147 & & 0.0055 & \\ Core Total & 2.84 & 14 & & & & \\ \hline \hline \end{tabular}
\end{table}
Table 3: The respective statistical parameters for RSM modeling.