O uso de dióxido de titânio como material fototérmico em sistemas de dessalinização solar

Abstract

Solar desalination is an alternative that consists of separating salts from salty or brackish water using evaporation, as occurs in the natural hydrological cycle. To improve the performance of the desalination plant, studies focused on photothermal materials were explored in order to enhance the heat transfer processes. Among the various photothermal materials, the present study aims to add titanium dioxide (TiO2) to a solar desalination system in order to maximize the production of treated water. Three pyramid-type desalination plants were used, operating simultaneously and continuously. The trays of two of the desalination plants were coated with a photothermal paint, adding a percentage of 2.5% and 5% of TiO2, and the third was coated only with the paint, for comparative purposes. Brackish water was collected at Sítio Comprido- Queimadas-PB. The physicochemical indicators of the water were analyzed before and after the solar desalination process. TiO2 was characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), particle size distribution, surface area, pore volume and mean pore diameter, scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetry (TG). The photothermal paints, with and without TiO2, were characterized by FTIR. In addition, during the experiments, some parameters were monitored: room temperature, solar radiation, wind speed, relative humidity, internal glass temperature and tray temperature, as well as the production of desalinated water. It was concluded that the desalinator that contained the tray coated with 5% TiO2 obtained a higher production of desalinated water compared to the other desalinators. Regarding the quality of the water, after the desalination process, it met the standards established by Ordinance GM/MS nº 888. Therefore, the introduction of TiO2 in the photothermal paint present in the desalination tray resulted in the synergy of the properties of these materials, confirming that TiO2 has adequate characteristics to act as a photothermal material in desalination via solar energy.