## 3 Results and Discussion
### Batch Desorption Studies
#### 3.6.2 Detailed Adsorption Studies
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Model** & **Parameter** & **ZDV** & **Phenol** \\ \hline \multirow{3}{*}{Langmuir} & qe (mg g\({}^{-1}\)) & 20.192 & 61.653 \\  & K\({}_{L}\) (L mg\({}^{-1}\)) & 0.400 & 0.007 \\  & R\({}^{2}\) & 0.999 & 0.992 \\ \hline \multirow{3}{*}{[PERSON]} & R\({}_{L}\) & 0.288 & 0.984 \\  & K\({}_{F}\) (mg/g)/(mg/L)\({}^{n}\) & 7.448 & 4.01 \\ \cline{1-1}  & n & 0.331 & 0.535 \\ \cline{1-1}  & R\({}^{2}\) & 0.958 & 0.986 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Investigated isotherm parameters for the adsorption of ZDV and phenol onto biochar/rGO/DES-glycerol. indicating that the Freundlich model may be applied to describe the experimental results. The Freundlich model implies that the pollutant molecules are adsorbed into multilayers on a non-uniform surface that involves several mechanisms, and the adsorption capacity rises endlessly with increasing concentration. As per Table 3, the K\({}_{\rm F}\) values of ZDV and phenol were 7.448 (mg/g)/(mg/L)\({}^{\rm n}\) and 4.01 (mg/g)/(mg/L)\({}^{\rm n}\). Furthermore, the value of n < 1 indicates that the adsorption of ZDV and phenol onto biochar/rGO/DES-glycerol was favorable. Effect of Contact Time and Kinetic Studies  
Tests of the effect of contact time and kinetic experiments were conducted to assess the adsorption rate, efficiency, durability, and mechanisms of the adsorbents. Rapid pollutant removal is critical in wastewater treatment processes. Across all concentrations, the best contact time for biochar/rGO/DES-glycerol to absorb ZDV and phenol was approximately 1 h and 30 min and 60 min, respectively (Figure 10). Due to unoccupied sorption sites on the adsorbent, adsorption of the adsorbate molecules was fast at first, indicating that diffusion might be the regulating element in the pollutant's adsorption process [17] onto biochar/rGO/DES-glycerol. Figure 10: Effect on contact time on (**a**) 10 mg L\({}^{-1}\) ZDV and (**b**) 50 mg L\({}^{-1}\) Phenol by biochar/rGO/DES-glycerol (Conditions: dose = 0.01 g; time = 180 min; speed = 200 rpm). Figure 9: Isotherm plots of (**A**) ZDV and (**B**) phenol. Then the sluggish rate of the flattening observed might be attributed to the controlled-attachment process, as sorption sites had become occupied at this point. Mesoporosity and multiple functional groups on the modified biochar/rGO/DES-glycerol adsorbent are responsible for the exceptionally fast kinetics. The adsorption efficiency was evaluated using kinetic models such as the Pseudo-first-order (PFO), Pseudo-second-order (PSO), and intra-particle diffusion models. The PSO model is commonly used to represent the adsorption of pollutants from aqueous systems in wastewater treatment processes that occur via chemisorption in relation to the number of sites available for the exchange process at the solution-solid interface. It is assumed that there is bimolecular interaction between the adsorbent and the solvent [24]. Table 4 shows the results of fitting experimental data into the models to generate kinetic parameter values. The model that best describes the experimental data was chosen based on its R\({}^{2}\) closest to unity. The results in Table 4 show that PSO best fits the experimental data for the adsorption of ZDV and phenol onto the biochar/rGO/DES-glycerol. The PSO model is commonly used to simulate the adsorption of pollutants from an aqueous system in the wastewater treatment process, which mostly occurs via chemisorption. Compared to the number of sites that may be accessed for the exchange process at the solution-solid interface, PSO assumes that bimolecular contact between the adsorbent and the adsorbate molecules in the solution causes adsorption. The organic pollutant molecules and the adsorbent exchange and share electrons during this process [18].