A bioinspired solar evaporator for continuous and efficient desalination by salt dilution and secretion

Water desalination and wastewater treatment via solar photothermal energy conversion are among the most important technologies to address the increasing pressing global water scarcity. Solar energy is the cleanest, most abundant, renewable natural resource available. Herein, we report the development of highly efficient, flexible, low weight, and cost effective Plasmonic Functionalized Cotton (PFC) nanocomposite materials for solar steam generation through the efficient evaporation of surface water pools. The PFC nanocomposites contain metallic nanoparticles that exhibit strong solar absorption followed by non-radiative relaxation causing the absorbed energy to be converted into heat for efficient water evaporation. The chemically modified cotton leads to a partial hydrophobic surface that allows the material to float on the water's surface and provide excellent thermal insulation properties in addition to facile and scalable synthesis. The PFC nanocomposites containing Au and Ag nanoparticles are demonstrated to be among the most efficient solar thermal converters reported to date for solar water desalination. The Au/Ag-PFC fibers exhibit average water evaporation rates of 1.4 and 11.3 kg m-2 h-1 with superb solar thermal efficiencies of up to 86.3% and 94.3% under 1 and 8 sun illumination, respectively. Furthermore, the Au/Ag-PFC fibers display stable evaporation rates over more than 10 repeated evaporation cycles without any performance decline under acidic solution at pH 2 or basic solution at pH 10. The successful application of the Au/Ag-PFC fibers for the removal of organic dyes from contaminated water through the solar steam generation is also demonstrated. The high solar thermal evaporation efficiency, excellent stability and long-time durability make the PFC nanocomposites excellent candidates for applications in seawater desalination and wastewater treatment by solar-steam generation.

Water desalination system via ion immobilization on iron corrosion-based colloids and filtration by kevlar support

Water desalination via solar steam generation is one of the most important technologies to address the increasingly pressing global water scarcity. Materials for solar photothermal energy conversion are highly sought after for their cost savings, environmental friendliness and broad utility in many applications including domestic water heating and solar-driven desalination. Herein, we report the successful development of metal-free, low weight and cost effective functionalized carbonized cotton (CC) fibers for efficient solar water desalination and wastewater treatment. The CC fibers with nearly full solar spectrum absorption, efficient photo-thermal conversion and low-cost could provide excellent alternatives to the high-cost plasmonic-based materials for solar water desalination. We also report on a novel and simple device to mitigate the issues associated with conductive heat loss by utilizing the economically viable carbonized cotton materials as an irradiation surface placed on a low-density polyethylene foam that floats on the surface of seawater. The CC solar steam generation device exhibits average water evaporation rates of 0.9, 6.4 and 10.9 kg m−2 h−1 with impressive solar-to-vapor efficiencies of 59.2, 88.7 and 94.9% under 1, 5 and 8 sun illumination, respectively. Moreover, the device displays excellent durability showing stable evaporation rates over 10 steam generation cycles under 5 sun of solar intensity. Furthermore, the applicability of the CC device for the removal of organic dyes from contaminated water through solar steam generation is also demonstrated. The low-cost, simple design, high solar thermal evaporation efficiency, excellent stability and long-term durability make this CC device a perfect candidate for applications in seawater desalination and wastewater treatment by solar steam generation.

Bio-inspired solar evaporators for stable and efficient desalination of high-salinity brine with zero liquid discharge.

A fundamental challenge in the design of solar evaporators is balancing the conflicting requirements of salt rejection and high evaporation efficiency. Consequently, bioinspired membrane design has emerged as a promising strategy for enhancing solar-driven interfacial water evaporation and desalination. Here, we report a bioinspired asymmetric photothermal membrane that is denoted as Mossene. Its design is inspired by the ecological water-regulation strategies of niche bryophytes. This Mossene membrane integrates dual-layer functionality: a hydrophilic substrate for water transport and retention and a hydrophobic top layer for light absorption and floatation. The lower hydrophilic layer is fabricated by electrospinning polyamide-6 blended with a sulfhydrylated UiO-66 metal-organic framework. This structure enables rapid water uptake, storage, and sustained molecular transport, emulating the function of water-storage cells in bryophyte leaves. The upper hydrophobic layer, composed of multiwalled carbon nanotubes and polyvinylidene fluoride, replicates the surface hydrophobicity and chlorophyll-mimetic light-harvesting characteristics of moss leaves. This design ensures efficient solar absorption and thermal confinement. Under 1 kW m-2 irradiation, the dry surface of Mossene heats from 16 to 109.9 °C within 6 min. When floated on 3.5 wt % NaCl solution, the membrane reaches 78.5 °C in 5 min, demonstrating excellent photothermal conversion. The optimized Mossene membrane (MCM-6.5-0.75) achieves an outstanding water evaporation rate of 1.55 kg m-2 h-1 and an energy conversion efficiency of 97.5%. This study introduces Mossene as a biomimetic photothermal membrane that integrates hierarchical structure, selective wettability, and efficient energy utilization and underscores the potential of next-generation solar evaporators for practical implementation in sustainable water purification.

Marangoni-driven biomimetic salt secretion evaporator

Biomimetic vertically aligned aerogel with synergistic photothermal effect enables efficient solar-driven desalination

Solar-driven interfacial evaporation for clean water generation has drawn significant attention as a promising and environmentally friendly avenue to tackle the global issue of water scarcity. The collected condensate can be free from most pollutants and impurities of diverse undrinkable water sources, such as heavy metals, organic dyes, minerals, and salts. However, when water is contaminated by volatile organic compounds (VOCs), this approach is ineffective because VOCs also evaporate and even can be enriched in the condensate. Here, we demonstrate TiO2-loaded CuO nanowire-covered Cu foam (TiO2-CuO-Cufoam) for efficient solar-driven interfacial evaporation and synchronous removal of VOCs via photocatalytic degradation. The TiO2-CuO-Cufoam nanoarchitecture possesses high solar absorption, quasi-one-dimensional water pathway, super-hydrophilicity for ultrafast water transport, long-term stability, and potential for cost-effective and scalable production for both VOC removal and desalination, meeting World Health Organization potable water standards. Our TiO2-CuO-Cufoam evaporator simultaneously demonstrates high solar evaporation efficiency of 86.6% and efficiency of 80.0% for the removal of VOCs under one sun (i.e., 1 kW m−2). This result may open new opportunities for energy-efficient, clean water generation from real-world water sources using solar energy. Novelty Statement TiO2-loaded CuO nanowire-covered Cu foam (TiO2-CuO-Cufoam) was obtained through the facile and green synthesis process. The TiO2-CuO-Cufoam nanoarchitecture possesses high solar absorption due to surface nanostructuring, quasi-one-dimensional water pathway for localized thermal management, super-hydrophilicity for ultrafast water transport, TiO2-CuO heterojunction for enhanced photodegradation of VOCs without consumption of chemical reagents, long-term stability, and potential for cost-effective and scalable production. The nanoarchitecture is employed for clean water generation from real-world water sources.

Highly efficient solar water evaporation of TiO2@TiN hyperbranched nanowires-carbonized wood hierarchical photothermal conversion material

Polyethersulfone-silica aerogel/ polypyrrole solar evaporation membrane for wastewater treatment and desalination

A review of superhydrophobic and omniphobic membranes as innovative solutions for enhancing water desalination performance through membrane distillation

High salt-resistant and robust MXene@oleylamine/PET composite nonwoven for efficient and long-term solar desalination

Hybrid graphene oxide-graphene membrane for efficient water desalination: Insights from molecular dynamics simulation

Preparation and performance study of scalable high-efficiency solar steam generated system

Solar-assisted fabrication of dimpled 2H-MoS2 membrane for highly efficient water desalination