Effect of structure, morphology and chemical composition of Zn-Al, Mg/Zn-Al and Cu/Zn-Al hydrotalcites on their antifungal activity against A. niger

Abstract

Zn-Al, MgZn-Al and CuZn-Al hydrotalcites were prepared by the co-precipitation method, using the conventional hydrothermal crystallization or ultrasonic irradiation methods The samples were characterized by XRD, FT-IR and SEM, which confirmed the formation of a layered double hydroxide phase. Afterwards, the effects of composition and texture of the synthesized samples on their biocidal behavior against A. niger were evaluated by using traditional cultivation techniques. Among the different samples examined, hydrotalcites containing Zn, Zn-Mg and Zn-Cu showed an inhibitory effect on A. niger growth. Samples synthesized by the conventional method showed a greater inhibitory capacity than those synthesized by ultrasonication, but their biocidal activity was mainly determined by the presence of biocidal cations. The biocidal characteristics of zinc and/or copper in conjunction with the alkalinity of these materials were favorable for preventing fungal spread. The ZnAl hydrotalcite, the more eco-friendly material of the analyzed series, showed a good biocide performance, while the best antifungal behavior was observed for copper-containing hydrotalcites.