Avaliação das propriedades fotocatalíticas e antimicrobianas da solução sólida (Mg,Zn)2SnO4 obtida pelo método de Pechini modificado

Abstract

Zinc stannate (Zn2SnO4) and magnesium (Mg2SnO4) spinel were combined in order to obtain a solid solution (Zn(1-x)Mgx)2SnO4 in compositions x= 0; 0.25; 0.50; 0.75 e 1.0, using the modified-Pechini method, in order to evaluate the influence of the Zn2+ ions substitution by Mg2+ones in the spinel lattice for application as photocatalysts and antimicrobial agents. Photocatalysts were characterized by the X-ray Diffraction (XRD), Infrared Spectroscopy (IR), Ultraviolet-visible Spectroscopy (UV-Vis), Raman Spectroscopy, Fotoluminescence Spectroscopy (PL) and surface area measurements (SBET). XRD results showed that the materials presented a high long range order. The substitution between the metals in the crystalline lattice led to the existence of additional Raman modes, infrared band displacements, increase in band gap values and different photoluminescent emission profiles in the visible spectrum, varying the region from lowest to highest energy with the increase in Mg2+ in the structure. Zn2SnO4 presented greater short-range organization. Some parameters were evaluated in the photodiscoloration: catalyst calcination temperature (800 and 900 ° C), different dye concentrations (10, 20 and 40 mg.L-1) and pH (3 and 6). The results showed that the solid solutions presented excellent results. For the intermediate compositions the efficiency can be attributed to its high surface area, reaching 90% in times less than 3 h, even with double the concentration and decrease of the pH of the solution. For Zn2SnO4 it may be related to lower distortion making electron-hole recombination difficult. In relation to the antimicrobial tests, the intermediate compositions were efficient in inhibiting the growth of the bacterial strains against the bacteria Staphylococcus aureus and Escherichia coli, being the Gram negative more sensitive to the inhibitory action of the materials, being able to be attributed to the greater negative surface charge.