## 3 Results and Discussion
### Prediction of Adsorption Isotherm  
Once all the constants of the adsorption isotherm are determined, they can be used to predict the equilibrium solute concentration, removal efficiency, and required adsorbent quality for any set of experimental conditions. After substituting the initial conditions of the experiment, calculations were performed using Equations (6) and (12) to obtain the removal efficiency predicted by the Langmuir and Freundlich models related to the adsorbent quality. In addition, calculations were performed using Equations (9) and (13) to obtain the adsorbent quality predicted by the Langmuir and Freundlich models related to the removal efficiency. Then, we compared the prediction results with the experimental data and verified whether the error range was reasonable. Table 10 shows the prediction of the adsorbent removal efficiency for high- and low-concentration chlorine pollutants. For high-concentration chlorine pollutants, when the initial solution volume (V) of TCE is 0.1 L, the initial concentration of solute (C\({}_{0}\)) is 10.248 mg L\({}^{-1}\), and the mass (M) of 10 g silica gel is used as the adsorbent. The removal percentages predicted by the Langmuir and Freundlich models are 66.49% and 66.67%, respectively. The TCE removal percentage obtained in the experiment was 67.26%, so the error between the experimental value and the predicted value is 1.15% and 0.88%, respectively. When the initial solution volume is 0.1 L and the initial concentration of PCE is 11.375 mg L\({}^{-1}\), the removal percentages predicted by the two models are 69.53% and 69.86%, respectively. The PCE removal percentage obtained in the experiment was 71.16%, so the errors are 2.29% and 1.83%, respectively. \begin{table}
\begin{tabular}{p{113.8 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt}} \hline \hline
**(a) Silica Gel** & & & & & \\ \hline \hline \multicolumn{5}{c}{**Initial Conditions**} & \multicolumn{5}{c}{**Predicted R (\%)**} \\ \hline \(\mathbf{C_{0}}\) (mg L\({}^{-1}\)) & **M (g)** & **Experimental R (\%)** & **Langmuir Isotherm** & **Error (\%) \({}^{*}\)** & **Freundlich Isotherm** & **Error (\%) \({}^{*}\)** \\ \hline TCE 10.248 & 10 & 67.26 & 66.49 & 1.15 & 66.67 & 0.88 \\ \hline PCE 11.375 & 10 & 71.16 & 69.53 & 2.29 & 69.86 & 1.83 \\ \hline \hline \multicolumn{5}{c}{**Initial Conditions**} & \multicolumn{5}{c}{**Predicted R (\%)**} \\ \hline \(\mathbf{C_{0}}\) (mg L\({}^{-1}\)) & **M (mg)** & **Experimental R (\%)** & **Langmuir Isotherm** & **Error (\%) \({}^{*}\)** & **Freundlich Isotherm** & **Error (\%) \({}^{*}\)** \\ \hline TCE 1.0248 & 10 & 88.73 & 89.06 & 0.38 & 89.03 & 0.34 \\ \hline PCE 1.1375 & 10 & 92.10 & 91.31 & 2.91 & 92.57 & 4.34 \\ \hline \hline \end{tabular}  
* Note: Error = (\(\mid\)Experimental \(-\) Predicted \(\mid\))/Experimental \(\times\) 100%.  
\end{table} 
Table 10: Comparison of removal efficiency (R(%)) predicted by Langmuir and Freundlich isotherms with mass balance to experimental data points obtained from the adsorption of TCE and PCE onto (a) silica gel and (b) activated carbon. The results of the removal percentage of the low-concentration adsorbate show that, when the initial solution volume (V) of TCE is 0.1 L, the initial concentration of solute (C\({}_{0}\)) is 1.0248 mg L\({}^{-1}\), and the mass of activated carbon (M) is 10 mg. The removal percentages predicted by the [PERSON] and Freundlich models are 89.06% and 89.03%, respectively. The TCE removal percentage obtained in the experiment was 88.73%, so the error between the experimental value and the predicted value is 0.38% and 0.34%, respectively. When the initial solution is 0.1 L, and the initial concentration of PCE is 1.1375 mg L\({}^{-1}\), the removal percentages predicted by the two models are 91.31% and 92.57%, respectively. The PCE removal percentage obtained in the experiment was 92.10%, so the error between the experimental value and the predicted value is 2.91% and 4.34%, respectively.