## 3 Results and Discussion
### Characterization of AC@SCF Activated Carbon
The sharp bands at 2855 cm\({}^{-1}\) and 2925 cm\({}^{-1}\) correspond to stretching vibration modes of CH\({}_{3}\) and CH\({}_{2}\) groups [44], whereas the broadband at 1650 cm\({}^{-1}\) can be attributed to physically adsorbed water molecules, stretching vibration modes of C=C groups in aromatic rings, and/or to -COO\({}^{-}\) groups [45]. The last band at 1750 cm\({}^{-1}\) in both spectra reveals the presence of ketonic groups C=O that exist in aromatic rings or other organic rings such as those of caffeine [46; 47]. The band at 1250 cm\({}^{-1}\) can be attributed to stretching vibration modes of -C-C-C bridges on ketonic groups and/or deformation vibration modes of O-H bonds in carboxylic groups (-COOH) [45]. On the other hand, in the spectrum of activated carbon AC@SCF, only a few broadbands were observed and the most important were those at 1590 cm\({}^{-1}\) and 1260 cm\({}^{-1}\). \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \(\mathbf{S_{\text{BET}}}\) & \(\mathbf{C_{\text{BET}}}\) & \(\mathbf{S_{\text{BLang}}}\) & \(\mathbf{C_{\text{Lang}}}\) & \(\mathbf{V_{\text{pore}}}\) & \(\mathbf{D^{DFT}_{\text{micro}}}\) & \(\mathbf{V^{D\text{-R}}_{\text{micro}}}\) \\ (**m\({}^{2}\)/g**) & & (**m\({}^{2}\)/g**) & & (**cm\({}^{3}\)/g**) & (**nm**) & (**\% cm\({}^{3}\)/g**) \\ \hline
1372 & \(-\)93 & 1875 & 98 & 0.748 & 0.67/1.2/2 & 86.6 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Pore structure parameters derived from N\({}_{2}\) adsorption–desorption data and classic models. Figure 1: Nitrogen adsorption–desorption data and pore size distributions for Activated Carbon from Spent Coffee (AC@SCF). (**a**): nitrogen sorption hysteresis loop simulated by the CPSM model; (**b**): differential pore volume distribution estimated by the DFT model; (**c**): differential pore volume distribution estimated by the CPSM model in the micro-pore range; (**d**): differential pore volume distribution estimated by the CPSM model in the meso-macro-pore range; (**e**): Dubbinin-Raduskevitch curve fore micropore volume fraction estimation. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \(\mathbf{S_{\text{CPSM}}}\) & \(\mathbf{V^{\text{CFSM}}}\) & \(\mathbf{D^{\text{CFSM}}}\) & \(\mathbf{D^{\text{CFSM}}}\) & \(\mathbf{N_{\text{mean}}}\) & \(\mathbf{D^{\text{CFSM}}}\) & \(\mathbf{D^{\text{CFSM}}}\) & \(\mathbf{D^{\text{CFSM}}}\) & \(\mathbf{\Upsilon}\) \\ (**m\({}^{2}\)/g**) & (**cm\({}^{3}\)/g**) & (**nm**) & (**nm**) & (**nm**) & (**nm**) & (**\% cm\({}^{3}\)/g**) & (**Tortuosity**) \\ \hline
1869 & 0.748 & 1.47 & 3.71 & 1.28/1.6 & 27 & 84.6 & 4.65 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Pore structure parameters derived from Corrugated Pore Structure Model (CPSM) model simulation of the overall N\({}_{2}\) adsorption–desorption hysteresis loop. these bands can be assigned to stretching vibration modes of carbonylic groups (-COO\({}^{-}\)) and C-O bonds that exist in ether and hydroxyl groups, respectively [48; 49]. The Raman spectrum of the activated carbon AC@SCF is presented in Figure 2b. The spectrum exhibited the characteristic peaks of carbon-based materials at 1585 cm\({}^{-1}\) and 1345 cm\({}^{-1}\), corresponding to the well-known G- and D-band vibrations, respectively. The G-band having E\({}_{\text{2g}}\) symmetry derives from the in-plane-bond stretching motion of pairs of sp\({}^{2}\) carbon atoms, both in aromatic rings and conjugated chains, whereas the D band corresponds to lattice breathing mode and has A\({}_{\text{1g}}\) symmetry. The D band only becomes active in the presence of disorder and derives from sp\({}^{2}\) edge plane breathing vibrations [50]. Several factors such as the carbonization degree, clustering of the sp\({}^{2}\) phase, bond disorder, presence of sp\({}^{2}\) rings or chains, sp\({}^{2}\)/sp\({}^{3}\) ratio, porosity, crystallite size distribution, and concentration of amorphous component affect the position and width of D and G bands [50; 51; 52].