*3.2. Photocatalytic Experiments*

The photocatalytic activity of the LDH, the heterostructured catalysts and the calcined derivates were tested for the photodegradation of 4-NPh and 2 DCP in aqueous solutions. For this, appropriate amounts of catalyst powder were dispersed in the pollutant solution with the initial concentration of 0.025 g/L (of single or mol/mol mixture of pollutants) and a solid/liquid ration at 1 g/L. The solutions were stirred in the dark in order to realize the adsorption–desorption equilibrium between the catalytic surface and the pollutants, until no modification of the UV-vis absorption spectra was observed. Afterwards, the catalyst/pollutants mixtures were irradiated using an UNNASOL US 800 solar simulator, using a Xenon Lamp as a light source reaching 870 W/m2, equipped with UV or Vis block filters. The photocatalytic activity of all catalysts was tested under solar and UV irradiation. The reactions were carried out in a 200 mL reactor with water recirculation in order to avoid the evaporation and to keep the system at a constant volume and temperature. The pollutants' photodegradation profile was monitored by measuring the UV-Vis absorption spectra and by total organic carbon (TOC). TOC of 4-NPh and 2-DCB aqueous solutions were analyzed with a Shimadzu TOC-VCPH (Shimadzu, Kyoto, Japan) analyzer equipped with a NDIR detector, to evaluate the mineralization degree of the organic material. The TOC values were obtained by subtracting IC (inorganic carbon) values from TC (total carbon) values. Removal yield (%) was calculated as: 100 × (*Ao*−*At)/Ao*, where *Ao* and *At* were the absorbance values measured on solutions taken before the illumination (counted at time zero value) and at time *t* from irradiation start, respectively.

The r kinetics analysis was studied by fitting the experimental data on four models: pseudo-first-order model, pseudo-second-order model, Weber intraparticle diffusion model and Elovich model. The corresponding equations and significance of the calculated parameters are given in Table 3.

**Table 3.** Equations of the kinetic models applied in this study.

