3D porous β-cyclodextrin grafted graphene oxide/sodium alginate superhydrophilic natural polysaccharide-based aerogel for solar steam generation

Abstract

Solar steam generation (SSG) emerges as a paramount technology for efficient and sustainable desalination and wastewater purification. The innovative development of porous aerogel materials for solar steam generation heralds a new era in photothermal materials. In this study, a category of β-cyclodextrin-grafted graphene oxide/sodium anionic polysaccharide alginate composite aerogels (named GO-CD/SA) with solar steam generation behavior and wastewater purification properties is developed. GO-CD/SA demonstrates remarkable properties, including an impressive solar absorption efficiency of approximately 97.4 %, a low thermal conductivity of just 0.124 W m−1 K−1 in a wetted state, and exceptional superhydrophilicity. These attributes collectively contribute to GO-CD/SA achieving an evaporation rate of 1.79 kg m−2 h−1 when utilized with pure water. Furthermore, GO-CD/SA features an abundant three-dimensional porous structure (88.07 % porosity) and superhydrophilic properties that promote the rapid reflux of salt solution between the pore channels. This, in turn, enables excellent salt resistance, with no noticeable salt crystals precipitating during continuous evaporation in 20 % high concentration brine for 6 h. GO-CD/SA also demonstrates outstanding purification capabilities for organic dye wastewater and heavy metal ion wastewater. Therefore, this work combines the advantages of salt tolerance and wastewater treatment, paving the way for the exploration of natural polysaccharide-based photothermal materials.