A super absorbent resin-based solar evaporator for high-efficient various water treatment

Currently, water treatment has been viewed as an important way to the growing shortage of fresh water. A solar vapor generation device demonstrated enormous potential for desalination, water purification and carbon emission reduction. Nevertheless, the high cost and scalability hurdles of solar evaporators fundamentally restrict the practicality of solar-driven water treatment. In this study, an industrialized sodium polyacrylate (PAANa) super absorbent resin together with commercial carbon nanotubes (CNTs) is used to construct a PAANa-based solar evaporator. Under synergistic effects of high photothermal conversion efficiency, larger actual evaporation area, and reasonable water distribution on the evaporation surface, PAANa-based solar evaporator achieves a high water evaporation rate of 7.47 kg m⁻² h⁻¹ under 1 sun illumination (1 kW m⁻²) and convective flow condition. Notably, many kinds of sewage including dye-containing sewage, seawater, oil-in-water emulsion, and real industrial sewage can be effectively purified by using PAANa-based solar evaporator. Moreover, in arid and water-deficient areas, the PAANa-based evaporator with a strong water extraction capacity can easily capture water from gravel crevices and simultaneously purify it for further use. Significantly, under natural sunlight irradiation, a large-area PAANa-based evaporator (about 415 cm²) provided a sewage treatment capacity of up to 11.93 kg m^{− 2} for a continuous 10 h. This study will offer a new possibility for the industrialization of cost-effective and scalable solar evaporators, which can be used to alleviate the global water resources shortages.