Síntese de ferrita de níquel por coprecipitação com deposição simultânea em vidro e desenvolvimento de reator fotocatalítico

Abstract

The search for new routes for sustainable fuel production that reduce dependence on fossil fuels, are environmentally friendly, and are economically profitable has fostered studies on photocatalytic processes that enable the production of hydrogen on a large scale and in a safe way, with a high conversion rate and the lowest possible cost. In this context, this work was conducted around the theme seeking to develop a low-cost photocatalytic system and, simultaneously, to understand the process of production and simultaneous deposition of nickel ferrite (NiFe2O4) on soda-lime glass. For this, the coprecipitation method was chosen with simultaneous deposition during the drying and calcination step, which took place at 600 ° C. The 2³ central composite experimental design was to assess the influence of synthesis parameters on the characteristics of the catalyst. The statistical analysis was developed around the independent variables nickel concentration in the reactive solution (1: 2 of Ni: Fe), time at the isotherm of calcination and heating rate, and being analyzed the response variables: crystallite size and microdeformation, obtained through XRD analysis, and optical band gap, of which only the first presented statistical significance through the F test, with the concentration and heating rate having a positive and negative effect on the crystallite size, respectively. The crystallite sizes were calculated considering three equations: Scherrer, Halder-Wagner-Langford, and Williamson-Hall, of which the second had the best R² (0.9847 ± 0.0166) with sizes ranging from 17.40 nm to 28.33 nm, while the optical band gap varied between 1.9644 eV and 2.2374 eV. The macroscopic analysis of the images of the produced photocatalytic plates demonstrated greater homogeneity and quantity of material in those produced in higher concentrations (0.4 mol Ni) when compared to the others, while by scanning electron microscopy the images demonstrated that the crystals apparently have a spherical morphology and the cluster in quadratic structures of a certain height and with a flat surface. The photoreaction system showed functionality in the process for hydrogen production, with the need for improvements in the sealing system, gas extraction and quantification of these.