Cost-Effective Salt Extraction Photothermal Evaporator for Zero-Liquid Discharge Desalination with Life Cycle Assessment Insights

Water scarcity and environmental degradation represent critical global challenges that demand innovative, sustainable desalination solutions. In this study, we present a salt-extraction photothermal (SEP) evaporator that delivers zero liquid discharge (ZLD) desalination by utilizing interfacial solar-driven evaporation (ISE) and salt crystallization. The SEP achieved an evaporation rate of 2.11 kg m^–2 h^–1 with a salt collection rate of 0.85 kg m^–2 h^–1 from a 20 wt % sea-salt solution, as well as maintaining a high freshwater collection rate of 1.15 kg m^–2 h^–1 during prolonged outdoor tests. This system demonstrates its excellent ZLD capability by efficiently recovering salt ions. Finally, a comprehensive life cycle assessment (LCA) highlighted the SEP’s significant environmental advantages over conventional desalination technologies, with a substantial reduction in carbon emissions and resource depletion. The LCA further emphasized the SEP’s superior sustainability, driven by its low-energy, cost-effective fabrication process, and the efficient recovery of valuable resources. Overall, this work introduces a pioneering approach to ZLD desalination, combining effective resource recovery with a comprehensive LCA framework to demonstrate the long-term environmental benefits of this technology.