*2.3. Reusability*

Stability and reutilization are important to industrial application [47,48]. The reusability of the TH-2 composite is exhibited in Figure 10. After 5 cycles, the results show that the photoactivity can still achieve 87.9%, indicating the outstanding stability of TH-2. The decrease in catalytic activity may be mainly caused by the loss of surface area and the deposition of byproducts at the surface of the photocatalyst. It can result in the loss of active sites, agglomeration of nanoparticles, and reduction in crystallinity, which has been suggested by previous studies [49,50].

**Figure 10.** Reusability of TH-2 composite to the degradation of MB.

In addition, TiO2/hectorite can be recovered from the mixture only by sedimentation, while P25 is difficult to precipitate due to its strong suspension force, indicating that the composite has good recyclability. It can be concluded that TiO2/hectorite is an excellent catalyst material with stable activity and recoverability.
