## 2 Materials and Methods
### Porous Carbons Characterization  
The obtained carbons were submitted to N\({}_{2}\) adsorption-desorption isotherms at \(-\)196 \({}^{\circ}\)C (Micromerities ASAP 2010 equipment, Atlanta, GA, USA) for evaluating their surface area and pore volume. Specific surface areas, S\({}_{\text{BET}}\) (BET method), micropore volume, V\({}_{\text{Mic}}\) (t-plot method), and total pore volume, V\({}_{\text{T}}\) (N\({}_{2}\) adsorption at p/p\({}_{0}\) = 0.95) were determined. The mesopore volume (V\({}_{\text{Mes}}\)) was calculated from V\({}_{\text{T}}-V_{\text{Mic}}\). The micropore size distribution was determined with the density functional theory (DFT) (adsorption model for carbon slit-shaped pores), and the mesopore size distribution was determined by using the BJH method. From these results, the carbon with the higher porosity was selected. This carbon sample, coded as ACK, and the commercial carbon, CC, were submitted to additional characterizations:  
1. Elemental analysis--Quantification of C, H, N, and S (Thermo Finnigan-CE Instruments Flash EA 1112 CHNS analyzer, Waltham, MA, USA);
2. Ash content--Residue after combustion at 750 \({}^{\circ}\)C for 6 h in a muffle furnace (ASTM D1762);
3. pH at the point of zero-charge (pH\({}_{\text{PZC}}\))--A series of 6 solutions of NaCl (0.01 mol L\({}^{-1}\), 20 mL) was prepared, and the pH of each solution was adjusted in the range of 2-12 by adding 0.1 M NaOH or 0.1 M HCl. Then, 0.05 g of the carbon was added to  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Sample Name** & **Temperature (\({}^{\circ}\)C)** & **Activation Time (h)** &
\begin{tabular}{c} **Biochar:KOH Mass** \\ **Ratio** \\ \end{tabular} \\ \hline Temperature effect & & & \\ ACK700\_1\_1:1.5 & 700 & 1 & 1:1.5 \\ ACK800\_1\_1:1.5 & 800 & 1 & 1:1.5 \\ \hline Mass ratio effect & & & \\ ACK800\_1\_1:1 & 800 & 1 & 1:1 \\ ACK800\_1\_1:1.5 & 800 & 1 & 1:1.5 \\ ACK800\_1\_1:2 & 800 & 1 & 1:2 \\ \hline Activation time effect & & & \\ ACK800\_1\_1:2 & 800 & 1 & 1:2 \\ ACK800\_2\_1:2 & 800 & 2 & 1:2 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Experimental design for porous carbons synthesis and nomenclature of samples.  
each solution, agitated for 48 h, and the final pH of each solution was measured. The pH\({}_{\text{PZC}}\) was obtained from the plot of pH\({}_{\text{drift}}\) versus pH\({}_{\text{initial}}\);
4. Thermogravimetric analysis (TGA)--Mass loss between 30 and 900 \({}^{\circ}\)C (heating rate of 5 \({}^{\circ}\)C min\({}^{-1}\)) under argon atmosphere (Setaram Labsys EVO, France);
5. Fourier-Transform Infrared Spectroscopy (FTIR)--KBr disk method (Perkin-Elmer Spectrum 1000 Spectrometer, Waltham, MA, USA) in the range of 400-4000 cm\({}^{-1}\) (resolution of 1 cm\({}^{-1}\));
6. X-ray Photoelectron Spectroscopy (XPS)--XPS of the carbon surface was obtained by using the Mg K\(\alpha\) radiation (hv = 1253.6 eV) from an XSAM800 dual anode spectrometer from Kratos. The operation conditions of the XPS analysis were as described in [30]. The detailed regions C 1s, O 1s, N 1s, and S 2p were acquired;
7. Temperature programmed desorption (TPD)--100 mg of each sample was heated to 1100 \({}^{\circ}\)C (heating rate of 5 \({}^{\circ}\)C min\({}^{-1}\)) under a flow rate of 25 cm\({}^{3}\) min\({}^{-1}\) of He. The profiles of CO and CO\({}_{2}\) were obtained with automated AMI-300 equipment (Altamira Instruments) connected to a mass spectrometer (Dymaxion 200, Ametek, PA, USA). Quantification of CO and CO\({}_{2}\) released through calibration at the end of each experiment;
8. Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS)--The morphology and elemental composition of ACK were obtained by using a JEOL 7001F analytical FEG-SEM equipment with an energy-dispersive X-ray spectrometer light element detector attachment.