Dry-Mill Synthesis of Photocatalysts Based on Layered Double Hydroxides

The mechanosynthesis by dry-milling and characterization of layered double hydroxides (LDH) containing Zn2+ in the layer and Cl− as interlayer anion has been investigated. The solids were synthesized by mechanosynthesis, by means of a dry-milling method using a planetary mill. This kind of synthesis is totally ecological as the stoichiometric amounts of reactants have been used to obtain the original solids, so, there was no need for washing or calcination thus avoiding water or atmospheric contamination. To compare results and prove that Cl− is the interlayer anion, a carbonate-LDH has been synthesized by the coprecipitation method. Original solids were calcined at 450 °C to obtain the oxides. Samples were fully characterized and used as catalysts in the paracetamol photodegradation to test the usefulness of these ecologically obtained solids as decontaminants. An assortment of techniques, such as XRD, FT-IR, TG-DTA, and N2 adsorption–desorption isotherms, has been utilized to prove the goodness of the dry-mill method applied. The X-ray diffraction data and the FT-IR and thermal results confirmed that the samples synthesized were hydrotalcites with the Cl− as the interlayer anion. The paracetamol photodegradation tests indicated that the dry milling procedure enhances the reaction.