Abstract
In this research, the optical properties of a black pigment of mixed Mn-Fe oxides synthesized by the precipitation method dispersed in silicone resin at different concentrations for use as a solar absorber in a two-slope passive solar still were evaluated. The transmittance of different thicknesses of float glass with 0.1% Fe2O3 was also studied for use as a condenser in the construction of the solar still. Regarding the pigments, the absorbance and spectral emittance were evaluated, the floated. With the above information, both the absorbent surface and the condensers were optimized to propose the best design of the solar still. The novel hybrid material used as a selective coating in the still, which corresponds to 2.3% Mn-Fe mixed oxides, exhibited a high solar absorbance of 91.82% and a relatively low infrared thermal emission of less than 57.22%, as well as good stability to the corrosive and hot environment of the solar still, in addition to great durability over time and in real operating conditions. The float glass with the highest transmittance corresponds to a thickness of 3 mm and an average transmittance of 82.57%. The built prototype was characterized by obtaining the temperature profiles of the absorber and condensers, thermal efficiency, production and water quality. The prototype has a thermal efficiency of 29.6%, requiring only energy from the sun for its operation. The water produced by this device becomes an option for human use and consumption in accordance with current official standards, allowing supply in communities that do not have access to drinking water but have access to seawater or waters with high hardness.