Rising freshwater scarcity in arid regions requires advanced desalination and resource recovery technologies to address brackish water threats to agriculture, drinking water, and ecosystems. Charge-asymmetric Janus nanofiltration (NF) membranes demonstrate significant potential for resource recovery in brackish water treatment, particularly enabling efficient ion-selective separation. However, current models remain limited to qualitative speculation regarding the ion transport mechanisms in Janus membranes, as they fail to incorporate quantitative descriptions of axial charge heterogeneity. Herein, we address this gap by integrating axial charge distribution into the Donnan Steric Pore Model with Dielectric Exclusion (DSPM-DE). A charge-asymmetric Janus membrane (R90-AC) was fabricated by coating a positively charged polyelectrolyte layer onto a commercial NF membrane (R90-SC). The axial-charge-distributed DSPM-DE model reduced prediction deviations for six ions in brackish water systems to < 8%, outperforming conventional models (deviations > 16%). Theoretical simulations revealed an intrinsic electric field (18.87 mV·μm −1 ) within Janus structures, driving anomalous electromigration contributions exceeding 100% for cations and −50% to −20% for anions. This “electrostatic diode” effect was experimentally validated, with Mg 2+ forward flux (2.69 × 10 −2 mol·m −2 ·h −1 ) surpassing reverse flux (2.98 × 10 −3 mol·m −2 ·h −1 ) by nearly an order of magnitude. The study bridges theoretical modeling and practical structure design, offering a robust framework for tailoring charge-asymmetric structures in ion-selective separations.
To address global freshwater scarcity, developing a sustainable and efficient brackish/high salinity water desalination technology is crucial. Solar-driven interfacial evaporation (SIE) systems typically consist of a water-absorbing layer drawing water via capillary action to the interface and a photothermal conversion layer absorbing sunlight to heat the interface. Researchers have focused primarily on designing various photothermal materials to enhance heat generation and evaporation efficiency, while they often overlook the need for all-weather functionality, limiting further advancement of SIE systems. This study introduces a novel basalt fabric-based photo-electrothermal interfacial evaporator for all-weather efficient desalination, integrating photothermal and electrothermal effects to enhance evaporation rates and reduce reliance on sunlight. The basalt fabric is functionalized with polydopamine, carbon nanotubes, and polypyrrole to improve its photothermal properties, and stainless steel mesh 304 is used as an electrothermal layer. Under simulated sunlight (1 sun) and 1.5 V in the laboratory, the evaporation rate of actual brackish water can reach 4.43 kg m −2 h −1 ; under real sunlight and 1.5 V outdoors, the evaporation rate can reach up to 6.37 kg m −2 h −1 . Additionally, due to the well-designed multilayer structure with Janus hydrophilicity gradient distribution, the evaporator exhibits excellent salt resistance and long-term stability, maintaining a daytime evaporation rate above 2.17 kg m −2 h −1 during 120-hour continuous operation without any intervention. The purified water meets the drinking water standards set by the WHO, with significant reductions in ion concentrations and chemical oxygen demand. This study provides a promising approach for efficient and sustainable brackish water purification, offering potential applications in water-scarce regions.
Due to its low energy consumption, capacitive deionization (CDI) is regarded as one of the most promising technologies in brackish water desalination. However, CDI has two drawbacks, namely, low deionization capacity and unavoidable parasitic reactions that limit its further development. Unlike the traditional CDI electrodes that store the ions in the electric double layer capacitors, faradic electrodes store ions at crystallographic sites or between the atomic planes, which could effectively address the issues mentioned above. However, obtaining low-cost faradic electrode materials with a high salt removal capacity for practical applications is still challenging. Here, we report a new material, mesoporous amorphous FePO 4 nanosphere@Graphene (FePO 4 @RGO) synthesized via a one-step hydrothermal method. Electrochemical experiments demonstrate that the formation of a mesoporous structure and covered by graphene can address the drawbacks of pure FePO 4 for electroconductivity and ion diffusion rates. When used in desalination, the novel design enhances the desalination capacity, and the rates increase by 60% (50.13–85.94 mg/g) and 180% (0.079–0.24 mg/g/s), respectively, while energy consumption decreases by 25%. The production cost of the material was calculated, and implies that this material has potential for use in large-scale desalination.
危险品化学品经营许可证（带存储）