**2.5. Phenol photodegradation and adsorption tests**

The LDH, CLDH, TiO<sup>2</sup> I, TiO<sup>2</sup> B, and TiO<sup>2</sup> T precursors and TiO<sup>2</sup> I-LDH, TiO<sup>2</sup> B-LDH, and TiO<sup>2</sup> T-LDH composites were mixed separately with a phenol solution (Baker) (C0 = 10 mg/L). Air was pumped through each mixture to maintain constant agitation, and the solution was stabilized for 20 minutes. Three different conditions were evaluated: (i) under UV light with a UVS-18 EL (λ = 264 nm, 8 w) lamp and in the absence of solid (photolysis), (ii) in the dark without UV irradiation and with the synthesized materials (adsorption), and (iii) under UV light with the presence of the synthesized solids (photocatalysis). The experiments were conducted for 120 minutes at room temperature (20°C) and without external pH variation. The effect of different concentrations of the prepared composites was also evaluated at concentrations of 0.5, 1.0, 1.5, and 2.0 g/L; aliquots were extracted at 0, 5, 10, 30, 50, 80, and 120 minutes during

**Figure 1.** Methodologies for TiO<sup>2</sup> -LDH composite preparation.

the experiments. The phenol concentration was determined by UV-Vis spectrophotometry using the 4-aminoantipyrine method [18]. In order to determine the reuse capacity of the synthesized composites, photodegradation tests were conducted with UV irradiation using the same solid in consecutive rounds. At the end of a photodegradation cycle, the material was recovered from the solution by sedimentation and reused with a new phenol solution until four cycles were completed.
