A salt pollution self-cleaning Al based solar desalination evaporator fabricated using a picosecond laser

Abstract

Solar desalination is an environmentally friendly, low cost and sustainable process to obtain clean water. As the solar desalination method with the most potential, the solar-driven interfacial evaporator faces the problems of complex preparation procedures, high costs and low efficiencies when processing the evaporator. Here, an efficient and simple method is proposed to process aluminum (Al) based solar interfacial evaporators by using a picosecond laser (Ps). The effect of scan modes from point to line to plane, light intensity and hole distance on the evaporation rate is systematically studied. Compared with the pristine sample, the results of the nano indentation test indicate that the elastic modulus and hardness of the as-prepared sample have rarely decreased. Furthermore, the reflectivity of the laser treated surface within a wide spectral range from ultraviolet to far infrared is reduced. The evaporation rate at 15 kW m⁻² solar intensity is 10.84 kg m⁻² h⁻¹, and the outdoor evaporation rate can reach 2.325 kg m⁻² h⁻¹ with a solar intensity of 0.95 kW m⁻². Moreover, the as-prepared surfaces show good salt pollution self-cleaning properties. The ion concentrations (Na⁺, K⁺, B³⁺, Mg²⁺ and Ca²⁺ ions) of seawater (Bohai Sea) after desalination are far below the ion concentration limit set by the World Health Organization (WHO) for drinking water. This work provides a fast and simple method for solar desalination, which offers a great opportunity to develop efficient desalination for real world applications.