## 3 Results and Discussion  
### Characterizations of MS/CID/ZrO\({}_{2}\) Composites  
To better observe the microstructure of the MS/CID/ZrO\({}_{2}\) composites, we analyzed MS and MS/CID/ZrO\({}_{2}\) using SEM, and the results are shown in Figure 2. Figure 2a,b display the SEM images of MS, revealing a rough surface structure characterized by layered and stacked granular features. In contrast, Figure 2c,d present the SEM images ofMS/CID/ZrO\({}_{2}\), which exhibits a smoother surface structure. Adjusting the pH to between 3.5 and 4.0 during the solution preparation process is conducive to the formation of very small ZrO\({}_{2}\) nanoparticles (approximately 5-20 nm) [25; 26]. We suggest that this smoother surface resulted from the addition of ZrOCl\({}_{2}\)\(\cdot\)8H\({}_{2}\)O, where the in situ-generated biomimetic ZrO\({}_{2}\) nanoparticles filled the original pores in MS.  
As an essential analytical technique, FTIR spectroscopy was used to identify various functional groups on the surface of the adsorbent. When infrared light interacts with a solid material, the chemical bonds undergo changes in shape, whether through stretching, contracting, or bending. Consequently, regardless of the molecular structure, each functional group tends to absorb infrared light within a specific wavenumber range. Figure 3a presents the FTIR spectra of MS and MS/CID/ZrO\({}_{2}\). A broad peak band between 3650 and 3000 cm\({}^{-1}\) is observed, indicating the formation and alteration of hydrogen bonds. We suggest hydrogen bonding interactions between MS and MS/CID/ZrO\({}_{2}\) are responsible for that [27; 28; 29]. Additionally, the absorption peaks at 3300 cm\({}^{-1}\) and 3383 cm\({}^{-1}\) are attributed to the stretching vibrations of -OH groups. Both MS and ZrO\({}_{2}\) nanoparticles contain abundant -OH groups, and the peak intensity increases after the in situ formation of ZrO\({}_{2}\) nanoparticles [30]. The absorption peaks at 1640 cm\({}^{-1}\) for MS and 1659 cm\({}^{-1}\) for MS/CID/ZrO\({}_{2}\) are associated with the C=O stretching vibrations of carboxyl/carbonyl groups [31], and the peaks at 1530 cm\({}^{-1}\) for both MS and MS/CID/ZrO\({}_{2}\) may correspond to -C=N bonds [32], resulting from the reaction between the amino groups in MS and the aldehyde groups in CID. The absorption peak at 1030 cm\({}^{-1}\) is likely related to C-O bonds [33]. It should be noted that the FTIR spectrum of MS/CID/ZrO\({}_{2}\) reveals a new absorption peak at 573 cm\({}^{-1}\), corresponding to the Zr-O functional group, and confirming the successful biomineralization formation of ZrO\({}_{2}\) nanoparticles on MS [34]. To further confirm the formation of ZrO\({}_{2}\) nanoparticles, XRD analysis was performed on the MS/CID/ZrO\({}_{2}\) composites. As shown in Figure 3b, the XRD pattern exhibits characteristic peaks consistent with the standard XRD pattern of ZrO\({}_{2}\), providing clear evidence for the formation of ZrO\({}_{2}\) nanoparticles within the MS/CID/ZrO\({}_{2}\) composites. Figure 2: SEM images of (**a,b**) MS and (**c,d**) MS/CID/ZrO\({}_{2}\). Considering that chemisorption involves changes in the chemical states of the adsorbed atoms, corresponding shifts in their specific binding energies are observed in the XPS spectra. To study the adsorption mechanism of U(VI) by MS/CID/ZrO\({}_{2}\), we used XPS to analyze the samples before and after the uranium adsorption. The high-resolution spectra of N and O atoms were analyzed using two-component Gaussian-Lorentzian sum functions to confirm the changes in their chemical states (Figure 4a). As shown in Figure 4b, after treating high-fluorine uranium-containing wastewater with MS/CID/ZrO\({}_{2}\), the peaks corresponding to U 4\(\mathrm{f}_{7/2}\) and U 4\(\mathrm{f}_{5/2}\) appear at 382.03 and 391.92 eV [35], respectively, with a spin-orbit splitting of 9.89 eV [36]. This confirms the successful binding of U(VI) onto MS/CID/ZrO\({}_{2}\).