Black kitchen waste based solar evaporator employing radiative cooling film as difffuse substrate for efficient desalination

Many substances looks black often means that these substance can completely absorb ultraviolet radiation and Visible incident light (UV). Ultraviolet and visible light account for 57 % of the incident energy of the sun. There are many substances that looks black, but have not been paid attention in the field of photothermal interface evaporation. Based on the above discussion, this paper selects the waste black round plastic lunch box and a piece of black garbage bag as solar photothermal materials to make a solar desalination device, and proves that these black garbage can be recycled and reused to make an interface solar evaporator. In this paper, a 2D desalination device with photothermal interface evaporation for solar thermal conversion was successfully fabricated using only black round plastic lunch box as photothermal material and polyester cloth as water delivery channel. In addition, a black garbage plastic bag as the only solar photothermal conversion material has also been reused in the preparation of 3D evaporators. Using the radiation cooling film as the diffuse reflection substrate, the 3D device makes the incident sunlight reflected from the radiation cooling film and polyester cloth to the black garbage plastic bag many times, making the whole evaporation device. It can reabsorb solar incident light many times. After testing, the solar energy absorption rate of the 3D evaporator is as high as 96.6 %, and the steam output is as high as 8.96 kg m−2 h−1.