Produção de material cerâmico incorporado com resíduo de TiO2: estudo das propriedades estruturais, fotocatalíticas e toxicidade

Abstract

The utilization of waste generated in various production chains of goods and services through the development of new materials for construction has proven to be a promising approach to addressing environmental concerns. By incorporating these residues, new products can be developed that meet the expected performance and durability requirements. The primary starting point for projects aiming to utilize these residues safely involves a study of their characteristics. The waste generated during the production of titanium dioxide (TiO2), commonly referred to as Unreacted Ore (URO), presents potential routes for use in the ceramic materials production chain, thus avoiding disposal in industrial landfills. This work aimed to investigate the effect of adding URO on the properties of ceramic blocks. The physical-mechanical and photocatalytic properties of ceramic blocks obtained from the mixture of clay and URO were evaluated after adding 5%, 10%, 15%, and 20% of URO relative to the clay mass. The produced ceramic blocks were assessed for their mechanical properties (linear shrinkage, apparent density, and compressive strength), morphological properties (scanning electron microscopy with energy-dispersive X-ray spectroscopy – SEMEDS), particle size properties (laser granulometry), mineralogical properties (X-ray diffraction – XRD), and chemical properties (Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy – ATR-FTIR). The results indicated that URO did not adversely affect the studied mechanical properties. XRD results revealed no crystalline changes of TiO2 derived from the firing process of blocks from the clay and URO mixture. The addition of URO significantly affected photocatalytic properties (9% increase in resazurin dye degradation). The textural parameter values of the ceramic blocks decreased with URO incorporation, attributed to more efficient particle packing. The surface area decreased from 16.6 to 9.1 m2/g, and pore volume decreased from 0.045 to 0.025 cm3/g for 0% URO to 20% URO samples, respectively. The reduction in textural parameter values favored increased compressive strength, resulting in a 6.5 MPa increase within the tested range. The addition of URO did not significantly affect the physical properties of apparent density and linear shrinkage. The results suggested that adding URO increased Al concentrations in the leachate samples, from 647.64 to 5,128.92 ppb for 0% URO to 20% URO samples, respectively. The presence of leachate and solubilized substances generated from URO had a negative impact on the germination of Lactuca sativa seeds. Based on the obtained results, it can be concluded that the addition of URO, except for the observed toxicity of the produced leachate/solubilized material, does not compromise any fundamental properties of the produced ceramic materials and can be incorporated up to 20% in the process, substituting traditional raw materials.