## 3 Results
### Adsorption Isotherms of PAEs on BG Composites  
Figure 7 shows the isothermal adsorption curves of biochar-graphene composite materials including DMP, DEP, and DBP fitted by the Freundlich model and Langmuir model, respectively. The adsorption capacity of BG composites pyrolyzed at 300 \({}^{\circ}\)C was less than that of BG composites pyrolyzed at 600 \({}^{\circ}\)C. The reason for this phenomenon was the change of specific surface area of biochar. The larger the specific surface area, the stronger the adsorption property of the composite material. The adsorption capacity of biochar-graphene composites to PAEs was absolutely higher than that of biochar at this temperature, indicating that graphene can be used as a potential site to improve adsorption. The isotherms adsorbed by PAEs were characterized by different \(\mathrm{K_{p}}\) values, while the N values adsorbed by a single PAE were not significantly different from each other. Therefore, the Freundlich N value presented a highly nonlinear trend, and the \(\mathrm{K_{r}}\) increased accordingly. The N value of the Freundlich model indicated that the surface of the BG composite was non-uniform, and the higher N value indicated the homogeneous surface with narrow adsorption site distribution. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Phthalate**} & \multirow{2}{*}{ \begin{tabular}{c} **Names of** \\ **Samples** \\ \end{tabular}  } & \multicolumn{3}{c}{ \begin{tabular}{c} **Pseudo First Order** \\ **Dynamic Model** \\ \end{tabular}  } & \multicolumn{3}{c}{\ \begin{tabular}{c} **Pseudo Second Order** \\ **Dynamic Model** \\ \end{tabular}  } & \multicolumn{3}{c}{ \begin{tabular}{c} **Internal Diffusion Model** \\ \end{tabular}  } \\ \cline{3-11}  & & \(\mathbf{Q_{\text{c}}}\)/(mg/g) & \(\mathbf{k_{1}}\)(\(\mathbf{h^{-1}}\)) & \(\mathbf{\tau_{adj}}^{2}\) & \(\mathbf{Q_{\text{c}}}\)/(mg/g) & \(\mathbf{k_{1}}\)(\(\mathbf{h  
In this study, the adsorption properties of biocarbon-graphene composites were discussed and compared with the commonly used adsorbents, which mainly include activated carbon, chitosan, biological adsorbent, clay mineral material, modified corn cob, polymer resin, and other materials. All  
Figure 7: The adsorption curves of DMP, DEP, and DBP were fitted by Freundlich model and Langmuir model, respectively; (**a**) DMP;(**b**) DEP;(**c**) DBP. these adsorbents have abundant pore structure and surface groups to adsorb PAEs. [PERSON] used Wutong to prepare activated carbon. After phosphoric acid modification, the porosity of activated carbon increased, the pore diameter decreased, the specific surface area increased, and the adsorption effect was better than before modification. The specific surface area of biochar prepared by the modified method was 15.9 m\({}^{2}\)g\({}^{-1}\), which was 15 times larger than that of the biochar-graphene composite prepared in this study. In addition, the study revealed that the pH value would affect the adsorption of adsorbent on PAEs. After the study of the adsorption effects under different pH values, it was found that the optimal adsorption effect was obtained when the pH value was 13, and the surface of the modified activated carbon was positively charged, increasing the electrostatic adsorption effect with PAEs [30]. [PERSON] et al. prepared biochar with peanut shell by the oxygen-controlled heating carbonization method. At three preparation temperatures, biochar showed different element contents. The adsorption of the two PAEs conformed to the Freundlich equation as the degree of aromatics increased with the increase of temperature. In this study, the pseudo-two-stage model of adsorption dynamic composite dynamics of biochar-graphite composites were prepared at two different temperatures [31]. [PERSON] et al. successfully prepared a flake biochar nanographene complex, which showed a good adsorption effect on the three PAEs. The main mechanism of adsorption on the three PAEs was different.