# Unlocking the Detoxification of Phenanthrene from Water Using Alkali-Activated Slag Mortar
## 3 Results and Discussions
### Phenanthrene Sorption Performance
#### 3.2.2 Sorption Equilibrium of PHE Using GGBFS and AAS  
To evaluate the maximum PHE sorption capacity of both BFS and AAS, detailed isotherm experiments were conducted at a controlled temperature of 23 \(\pm\) 1 \({}^{\circ}\)C. These experiments aimed to establish the relationship between the equilibrium concentration of PHE in the solution and the amount of PHE sorbed by the materials, ultimately determining the maximum sorption capacity (\(Q_{m}\)) of each sorbent.  
The sorption equilibriums in Figure 4d illustrate an increase in the equilibrium sorption amount with higher concentrations of PHE, indicating the progressive occupation of sorption sites on the sorbents as the availability of PHE in the solution rises. The data from these experiments demonstrated that the sorption capacity of AAS was significantly higher than that of raw GGBFS. The PHE sorption isotherm data were fitted with the Langmuir and Freundlich sorption models, described as Equations (3) and (4). The fitting results of the sorption model for the adsorbents are listed in Table 4.  
The experimental data for ground granulated blast furnace slag (BFS) demonstrated a strong agreement with the [PERSON] sorption isotherm model, yielding high correlation coefficients (r\({}^{2}\) > 0.995), as detailed in Table 4. This indicates that BFS exhibits monolayer sorption properties, where PHE molecules are adsorbed onto a single layer on the sorbent surface [21]. In contrast, alkali-activated slag (AAS) showed a better fit with the Freundlich sorption model, suggesting a multilayer sorption process on a heterogeneous surface [21]. The highest sorption capacity observed for PHE onto AAS from experimental data was 44.0 mg/g. Comparative analysis of sorption capacities, summarized in Table 5, highlights AAS as an efficient sorbent for PHE removal from water. AAS exhibited superior performance compared to various other sorbent materials tested, confirming its efficacy in capturing PHE molecules from aqueous solutions.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Materials**} & \multicolumn{3}{c}{**[PERSON]**} & \multicolumn{3}{c}{**[PERSON]**} \\ \cline{2-7}  & \(Q_{m}\) & \(K_{L}\) & \(\mathbf{r^{2}}\) & \(K_{F}\) & \(n_{F}\) & \(\mathbf{r^{2}}\) \\  & **(mg/g)** & **(L/mg)** & **((m/g)/ \(\mathbf{L/mg)^{1/n}}\)** & \(n_{F}\) & \(\mathbf{r^{2}}\) \\ \hline BFS & 3.79 & 4.691 & 0.990 & 3.436 & 0.435 & 0.922 \\ AAS & 44.00 & 7.823 & 0.959 & 51.61 & 0.456 & 0.983 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Isotherm model parameters for the sorption of PHE.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Material**} & \multirow{2}{*}{\(Q_{e,exp}\) **(mg/g)**} & \multicolumn{2}{c}{**Pseudo-First-Order Model**} & \multicolumn{2}{c}{**Pseudo-Second-Order Model**} \\ \cline{2-7}  & & \(K_{1}\) & & & & \\  & **(1/min)** & \(Q_{e,cal}\) **(mg/g)** & \(\mathbf{r^{2}}\) & \(\mathbf{(g/mg/min)}\) & \(\mathbf{Q_{e,cal}\) **(mg/g)** & \(\mathbf{r^{2}}\)} \\ \hline BFS & 2.36 \(\pm\) 0.58 & 0.007 & 1.833 & 0.771 & 0.064 & 2.450 & 0.974 \\ AAS & 15.2 \(\pm\) 0.11 & 0.123 & 0.531 & 0.530 & 0.247 & 15.2 & 0.957 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Kinetics parameters for PHE sorption on GGBFS and AAS.