Flexible and Washable CNT-Embedded PAN Nonwoven Fabrics for Solar-Enabled Evaporation and Desalination of Seawater

Abstract

Nanostructured photothermal membranes hold great potential for solar-driven seawater desalination; however, their pragmatic applications are often limited by substantial salt accumulation. To solve this issue, we have designed and prepared flexible and washable carbon-nanotube-embedded polyacrylonitrile nonwoven fabrics by a simple electrospinning route. The wet fabric exhibits a strong photoabsorption in a wide spectral range (350–2500 nm), and it has a photoabsorption efficiency of 90.8%. When coated onto a polystyrene foam, the fabric shows a high seawater evaporation rate of 1.44 kg m–2 h–1 under simulated sunlight irradiation (1.0 kW m–2). With a high concentration of simulated seawater as the model, the accumulation of solid salts can be clearly observed on the surface of the fabric, resulting in a severe decay of the evaporation rate. These salts can be effortlessly washed away from the fabric through a plain handwashing process. The washing process has a negligible influence on the morphology, photoabsorption, and evaporation performance of the fabric, demonstrating good durability. More importantly, a larger fabric can easily be fabricated, and the combination of washable fabrics with various parallel PS foams can facilitate the construction of large-scale outdoor evaporation devices, conferring the great potential for efficient desalination of seawater under natural sunlight.

Salt Mitigation Strategies of Solar‐Driven Interfacial Desalination

“…Therefore, Chen and co‐workers inserted carbon nanotubes into a polyacrylonitrile nonwoven fabric through electrostatic spinning to form a sandwich structure. [ 121 ] The 1−5 µm pores in the formed 3D channel structure promote salt particle dispersion during washing. Due to airtightness, the CNTs do not fall off during washing (Figure 10c).…”

“…Reproduced with permission. [ 121 ] Copyright 2019, American Chemical Society. d) CBCS structure for salt mitigation.…”

Cellular Structured CNTs@SiO2 Nanofibrous Aerogels with Vertically Aligned Vessels for Salt‐Resistant Solar Desalination

“…Most of the recently reported studies can only achieve salt resistance in low salinity seawater (<3.5%) and weak light intensity (1 sun), which is far behind the demands of industrial wastewater (10-20%) and long-term evaporating solar evaporation system (>20%). [24,25] Therefore, it is necessary to design a nanofiber-based solar evaporator with abundant highly interconnected pores to achieve superior salt resistance for efficient and durable solar evaporation.…”

Structure Architecting for Salt‐Rejecting Solar Interfacial Desalination to Achieve High‐Performance Evaporation With In Situ Energy Generation

“…When salt crystals form and accumulate on solar absorbers' surface, the primary method to remove it is physical cleaning, which refers to simple rinsing and washing. [ 88,93,129–133 ] This method is particularly suited for flexible membrane‐type devices as demonstrated in Figure 11b, [ 111 ] which are easy to clean and do not involve heavy intervention work compared to bulk materials.…”