Designing salt transmission channel of solar-driven multistage desalination device for efficient and stable freshwater production from seawater

Solar-driven passive multistage distillation (MSD) device provides a new approach for environmentally friendly freshwater production. However, the MSD device easily forms salt crystals on the evaporation surface when treating brine, resulting in performance degradation . Here, we design an MSD device with an effective salt-resistant structure to enable rapid and automatic removal of high-concentration brine by a gravity drive. The structure was optimized by laboratory experiments and simulation. As a result, the stable freshwater production rate of the 4-stage device can reach 1.98 kg m −2  h −1 under a 1 kW m −2 light intensity . In particular, the MSD device can work stably at a high light intensity of 4 kW m −2 with an evaporation rate of 8.26 kg m −2  h −1 , making its freshwater yield more than 1.7 times higher than that of a device without a salt-blocking structure. In summary, we explored a new method for salt removal in MSD devices, which is a meaningful method for long-term seawater desalination .