Stable, zero liquid discharge, and highly efficient solar-driven multistage distillation device based on tree-inspired radial water transfer

Emerging solar-driven passive multistage distillation (MSD) devices are considered one of the most promising strategies for environmentally friendly freshwater production, but salt-resistant and stability remain challenges. Here, an MSD device with a well-tolerated salt-resistant structure was designed to control the crystallization location by radial water transfer. The device is capable of producing both freshwater and salt crystals with in-situ zero liquid discharge. For a well-designed 7-stage device, the steady evaporation rate and the salt yield reached 2.21 kg m−2 h−1 and 60 g m−2 h−1 under a 1 kW m−2 light intensity and 3.5 wt% NaCl solution. In particular, the device maintained stable evaporation performance at high brine concentrations of 10 wt%, demonstrating the broad applicability of the strategy. Thus, this novel approach to the stable operation of MSD devices demonstrates a promising option for seawater desalination technology.