## 3 Results and Discussion
As can be seen in Figure 6a, the strong broad absorption band at 3400 cm\({}^{-1}\) was assigned to the abundant \(-\)OH group on the surface of the CBs. After modification with ZIF-8 and CNTs, a series of absorption bands in the range of 550\(-\)1600 cm\({}^{-1}\) were found in ZIF-8/CNTs/CBs, probably caused by the imidazole ring [32]. In particular, the absorption bands at 425 and 1715 cm\({}^{-1}\) are ascribed to the Zn-N stretching vibration band and the C=N stretching vibration band, respectively, which is consistent with earlier reports [35; 36]. Figure 3: TEM images of ZIF-8/CNTs (**a**) and C ZIF-8/CNTs (**b**). Figure 2: FE-SEM images of CBs (**a,d**), ZIF-8/CNTs/CBs (**b,e**), and C ZIF-8/CNTs/CCBs (**c,f**). The crystalline structures of CBs, ZIF-8/CNTs/CBs, and CZIF-8/CNTs/CCBs were investigated using XRD patterns (Figure 6b). It can be seen that there are three typical diffraction peaks at 14.8\({}^{\circ}\), 16.5\({}^{\circ}\), and 22.9\({}^{\circ}\), which were assigned to the (1-10), (110), and (200) lattice planes of cellulose in the CBs, respectively [37]. The XRD pattern of ZIF-8/CNTs/CBs shows six characteristic peaks at 7.3\({}^{\circ}\), 10.4\({}^{\circ}\), 12.9\({}^{\circ}\), 14.7\({}^{\circ}\), 16.4\({}^{\circ}\), and 18.2\({}^{\circ}\), which can be ascribed to the (011), (002), (112), (022), (013), and (222) lattice planes of ZIF-8, respectively [33]. Moreover, the XRD pattern of CZIF-8/CNTs/CCBs possesses only one weak and broad diffraction peak at 26.1\({}^{\circ}\), corresponding to the (002) lattice plane of the graphite-structure crystallites of CCBs [38]. These XRD results further verify the successful preparation of ZIF-8 on the surface of the CBs. Figure 4: (a) XPS survey spectra of ZIF-8/CNTs/CBs and C ZIF-8/CNTs/CCBs. (b) C 1s, N 1s, O 1s, and Zn 2p\({}^{3}\) spectra of ZIF-8/CNTs/CBs. Figure 5: (a) Images of CBs, ZIF-8/CNTs/CBs, and CZIF-8/CNTs/CCBs EDS elemental analysis spectra. (b) Images of CZIF-8/CNTs/CCBs in EDS elemental mappings. Figure 7a-c shows the water contact angles of CBs, ZIF-8/CNTs/CBs, and CZIF-8/CNTs/CCBs. CBs and ZIF-8/CNTs/CBs show good hydrophilicity, due to the existence of a hydrophilic group. After carbonization, CZIF-8/CNTs/CCBs possessed a superhydrophobic surface with a water contact angle of 152.7\({}^{\circ}\). Interestingly, the water droplet descended and contacted with the surface of CZIF-8/CNTs/CCBs. However, as the water droplet continued to rise, the water droplet and the surface of the CZIF-8/CNTs/CCBs gradually separated, suggesting that the sample had an ultra-low contact-angle lag (Figure 7d). As shown in Figure 8, the absorption capability of the sample was evaluated. CZIF-8/CNTs/CCBs can quickly and completely absorb dichloromethane dyed by Oil Red O from the bottom of the water (Figure 8a). Furthermore, when CZIF-8/CNTs/CCBs contacted n-hexane dyed by Oil Red O on water, it absorbed the n-hexane in seconds (Figure 8b). These results suggest that this material has excellent oleophilic and hydrophobic properties. The oil-water separation performance of the samples was evaluated by measuring the absorption capacities for various oils and organic liquids (Figure 9a,b). CZIF-8/CNTs/CCBs showed absorption capacities \(\mathbf{Q_{1}}\) in the range of 48 to 84 times its original weight for oil and organic liquids. The absorption capacities \(\mathbf{Q_{1}}\) of CCBs were slightly higher than those of CZIF-8/CNTs/CCBs for most of the oils and organic liquids. However, it is worth noting that the absorption capacity \(\mathbf{Q_{2}}\) of CZIF-8/CNTs/CCBs was much higher than that of CCBs. The possible reason for this result is that CCBs become lighter and smaller after carbonization of the CBs. Although the absorption capacity \(\mathbf{Q_{1}}\) of CCBs for oil and organic liquids is relatively higher, the absorption capacity \(\mathbf{Q_{2}}\) is low on account of the low actual adsorption amount. Meanwhile, ZIF-8 and CNTs were loaded into the 3D interconnected network structure of CBs, and the mass of CZIF-8/CNTs/CCBs was relatively high.