A gallery of hydrotalcite-type mesoporous materials with different Mg/Al molar ratios were synthesized by the coprecipitation method. The materials were activated by heat treatment to test their activity in the photodegradation of 2,4,6-trichlorophenol under UV light irradiation. The physicochemical properties of the different synthesized and activated materials were determined using XRD, physical adsorption/desorption of N2, FTIR, SEM, DTA, and TGA. Their banned band energy was determined by UV-Vis to identify their potential to be used as a semiconductor in catalytic photodegradation processes. The results of photodegradation tests of 2,4,6-trichlorophenol showed that hydrotalcites have a high degradation capacity, up to 100% for the catalyst of Mg/Al ratio = 2, with a high mineralization capacity of 80%. The degradation capacity of most of the catalysts tested is mainly due to the presence of holes and the formation of superoxide free radicals, which are the determining species within the degradation mechanism.

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BACKGROUND: The composite materials ZrO 2 /Zn 5 (OH) 6 (CO 3 ) 2 were prepared in only one step by chemical co-precipitation and thermal hydrolysis of urea. ZrO 2 was added at 5, 8 and 10 mol%. The samples were dried at 80 ∘ C and characterized by adsorption-desorption of N 2 isotherms, X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques, and diffuse reflectance (DRS), UV-visible, Fourier-transform infrared (FTIR) and X-ray photoelectron (XPS) spectroscopies. The materials were assessed in the photodegradation of phenol and polychlorinated phenolic molecules under UV-light irradiation. The possible mechanism was discussed from studies that corroborated or discarded the formation of the species •OH, •O 2 − and h + .RESULTS: The addition of ZrO 2 to Zn 5 (OH) 6 (CO 3 ) 2 resulted in a composite material with high photoactivity. The material containing 8 mol% of ZrO 2 (ZnZr-8.0%) was the sample with the best percentages of photodegradation and mineralization. The photodegradation enhancement was achieved partly by an increment in the specific surface area and principally due to localized states originating in the composite interphase which improved charge transfer. XPS study revealed that the ZrO 2 addition increases the oxygen vacancies which enhanced the organic molecule photodegradation via direct hole attack. CONCLUSION: The ZnZr composite system constitutes an excellent alternative for the photodegradation of persistent organic pollutants due to the low cost, high stability and null toxicity of the support Zn 5 (OH) 6 (CO 3 ) 2 .