## 3 Results and Discussion  
### Characterization of BCA-Mag/AB  
Figure 1a presents the nitrogen (N\({}_{2}\)) adsorption and desorption isotherms of BCA-Mag/AB. According to the IUPAC classification system, this isotherm curve can be classified as Type II. Hysteresis occurs when the adsorption isotherm does not align with the desorption isotherm, displaying hysteresis loops similar to Type H3. These results indicate that these materials possess mesoporous characteristics. Figure 1b shows that the pore widths fall within the mesoporous range, with the most prominent pore sizes ranging from 2 to 25 nm. The S\({}_{\text{SBET}}\) and V\({}_{\text{Total}}\) values of BCA-Mag/AB were determined to be 455.4 m\({}^{2}\)/g and 0.268 cm\({}^{3}\)/g, respectively. Additional details are available in Table 3. As a general rule, materials with large surface areas tend to have higher adsorption capacities and faster solute diffusion rates compared to those with lower SBET values [17]. Figure 1: (a) N\({}_{2}\) adsorption/desorption plot of BCA-Mag/AB; (b) pore width distribution of BCA-Mag/AB; (c) FTIR spectra; (d) XRD pattern; (e) TGA of BCA-Mag/AB. The changes in the surface functional groups of PP, BCA, BCA-Mag/AB, and BCA-Mag/AB+MB are depicted by the FTIR spectra. As shown in Figure 1c, the absorption peak at approximately 3295 cm\({}^{-1}\) corresponds to the stretching vibrations of the -OH group. The peaks in the range of 2933-2853 cm\({}^{-1}\) are associated with the C-H and -CH\({}_{2}\)- stretching vibration modes found in the structures of xylan, cellulose, and lignin [18]. The peak intensities between 3327 cm\({}^{-1}\) and 2851 cm\({}^{-1}\) in the OP powder show a significant decrease in BCA, indicating water loss and the degradation of -OH and aliphatic compounds due to carbonization. The peak at 1719 cm\({}^{-1}\) in the FTIR spectrum indicates the presence of C=O stretching vibrations associated with carboxyl groups; this band is observed only in OP. The peak at 1603 cm\({}^{-1}\) can be attributed to stretching vibrations associated with carbonyl (C=O) and alkene (C=C) bonds, with this peak being more frequently associated with C=C double bonds [19]. The XRD pattern of powdered PP is shown in Figure 1d, where the crystalline structure is discussed and found to be consistent with findings from a previous study. The peaks in the XRD pattern of PP arise from the crystalline cellulose present in the structure. These peak positions are located at 20 = 15.6\({}^{\circ}\) and 21.4\({}^{\circ}\), which are attributed to the (101) and (200) planes of cellulose, respectively [20]. The presence of low-intensity peaks indicates significant amounts of components such as hemicellulose, amorphous cellulose, pectin, and lignin, reflecting the amorphous nature of the material. In the XRD pattern of BCA, a decrease in the peaks originating from cellulose is observed. The peak detected at 43.3\({}^{\circ}\) is attributed to graphitic-like structures. This suggests a high degree of graphitization in the structure [21]. In the XRD spectrum of BCA-Mag/AB, multiple diffraction peaks are observed at 20 = 35.4\({}^{\circ}\), 53.6\({}^{\circ}\), 57.3\({}^{\circ}\), and 62.5\({}^{\circ}\), corresponding to the (400), (422), (511), and (440) planes of Fe\({}_{3}\)O\({}_{4}\) nanoparticles, respectively (JCPDS: 19-0629) [22]. The results suggest that Fe\({}_{3}\)O\({}_{4}\) nanoparticles have been successfully loaded onto OP-ABC using a method based on the co-precipitation of two iron salts. Thermal behavior was investigated using TGA in the temperature range of 17-800 \({}^{\circ}\)C, as shown in Figure 1e. Four consecutive decomposition stages represent the TGA thermogram of the BCA-Mag/AB nanocomposite. The first stage is associated with the desorption of physically adsorbed water from the surface, occurring between 17 and 190 \({}^{\circ}\)C, with a weight loss of =9.93%.