Effect of hydrothermal and mechanochemical treatments on the physicochemical and photocatalytic properties of Zn-Al double hydroxide and compositions based on it

Zn-Al layered double hydroxide (LDH) with Zn/Al ratio 3 has been synthesized by co-precipitation. This LDH has been modified via hydrothermal (HTT) and mechanochemical treatments as well as next calcination at 500 oC. All obtained LDH samples have been studied using XRD, nitrogen adsorption-desorption, UV-Vis and FTIR spectroscopy, potentiometric titration. HTT of LDH in the form of wet gel at 150 oC promotes improving the crystal structure of hydrotalcite and formation of meso-macroporous structure. Destruction of hydrotalcite structure and formation of ZnO in its matrix occurs at higher temperature. Calcined samples are oxide compositions with crystalline ZnO. HTT leads to increase in adsorption ability respect to safranin T and its photocatalytic degradation under visible irradiation. Calcined oxide compositions have maximal photocatalytic activity.