A dye-based desalinating evaporator independent on solar absorber of excellent optical properties for efficient desalination

Different from traditional organic photothermal composites, dye is a type of nonconducting organic substance that commonly employed to endow fabric cloth with diverse color. Especially, its characterizations of strong adhesion and low-cost remind us the potential application prospect to establish a sustainable desalination system by it. Whereas, through previous investigation, the low absorbance hampered it from efficient utilizing solar energy. Referring to the 3D-cup structure that reported before, herein, an evaporative structure, which even can be assembled by diverse colors of cloth other than black cloth, available to turn diverse colors in to black body cavity was demonstrated in this work. Even after long period of 120 h for desalinating brine with salinity of 10 wt%, the evaporator with EAI index of 7.4 is fabricated to attain a superior broadband absorbance of 98 % and a high steam output of 4.072 kg m−2 h−1, in the function of the mechanism that main working place is transferring from bottom to the wall interface. Besides, the salt deposition forming on the wall of the evaporator can be facilely removed and collected, with the Zero liquid discharge (ZLD) concept being successfully realized by facile regeneration of device. This work demonstrates one other advantage of the 3D-cup shaped structure that enable to transfer multi-color spectrum into full-wavelength solar utilization. This discovery has never been reported before, making it possible to fabricate a solar-vapour evaporator independent on solar absorber of excellent optical properties for efficient desalination. •The low absorbance of commercial low-cost dye hampered it from efficient utilizing solar energy.•A strategy which enables to turn diverse colors into black body cavity was demonstrated.•The evaporator attains a superior broadband absorbance of 98 % and steam output of 4.072 kg m−2 h−1.•Zero liquid discharge (ZLD) concept can be successfully realized by facile regeneration mean.