Proper disposal of industrial brine has been a critical environmental challenge. Zero liquid discharge (ZLD) brine treatment holds great promise to the brine disposal, but its application is limited by the intensive energy consumption of its crystallization process. Here we propose a new strategy that employs an advanced solar crystallizer coupled with a salt crystallization inhibitor to eliminate highly concentrated waste brine. The rationally designed solar crystallizer exhibited a high water evaporation rate of 2.42 kg m⁻² h⁻¹ under one sun illumination when treating real concentrated seawater reverse osmosis (SWRO) brine (21.6 wt%). The solar crystallizer array showed an even higher water evaporation rate of 48.0 kg m⁻² per day in the outdoor field test, suggesting a great potential for practical application. The solar crystallizer design and the salt crystallization inhibition strategy proposed and confirmed in this work provide a low-cost and sustainable solution for industrial brine disposal with ZLD.

With unique water-repellency and self-cleaning properties, superhydrophobic surfaces promise a great potential of anticorrosion for engineered metals. The current study reports a facile and controllable anodization approach to fabricate superhydrophobic CuO nanoneedle array (NNA) films for the enhancement of corrosion resistance of copper substrates. The anodic CuO NNA films were grown on copper foils by electrochemical anodization in an aqueous KOH solution for different anodization times. The morphological features and crystalline structures of the anodic CuO NNA were characterized by SEM-EDS and XRD. The superhydrophobicity on the hierarchical CuO NNA films was achieved by chemical modification with fluoroalkyl-silane (FAS-17). The presence of low surface energy fluorosilanized carbon (–CF_x) groups on the FAS-modified surfaces was ascertained by EDS, XPS and water contact angle analyses. The wetting behaviour of the FAS-modified surfaces was investigated to elucidate the correlation between the static water contact angles, surface roughness, dynamic water contact angle hysteresis, and anodization time. The FAS-modified copper surfaces demonstrated not only the desirable superhydrophobicity with a water contact angle as high as approximately 169° and contact angle hysteresis as low as about 5°, but also substantially improved corrosion resistance in an aqueous NaCl solution (3.5%) with an inhibition efficiency higher than 90%, as revealed by means of Tafel plots and EIS measurements. The stability and durability of the superhydrophobic FAS-modified surfaces were evaluated by observing the change in surface wettability and geometric microstructures as a function of exposure time in an aqueous NaCl solution.

The urgency of addressing water scarcity and exponential population rise has necessitated the use of sustainable desalination for clean water production, while conventional thermal desalination processes consume fossil fuel with brine rejection. As a promising solution to sustainable solar thermal distillation, we report a scalable mangrove-mimicked device for direct solar vapor generation and passive salt collection without brine discharge. Capillarity-driven salty water supply and continuous vapor generation are ensured by anti-corrosion porous wicking stem and multi-layer leaves, which are made of low-cost superhydrophilic nanostructured titanium meshes. Precipitated salt at the leaf edge forms porous patch during daytime evaporation and get peeled by gravity during night when saline water rewets the leaves, and these salt patches can enhance vaporization by 1.6 times as indicated by our findings. The proposed solar vapor generator achieves a stable photothermal efficiency around 94% under one sun when treating synthetic seawater with a salinity of 3.5 wt.%. Under outdoor conditions, it can produce 2.2 L m⁻²of freshwater per day from real seawater, which is sufficient for individual drinking needs. This kind of biomimetic solar distillation devices have demonstrated great capability in clean water production and passive salt collection to tackle global water and environmental challenges.