Efficient water purification and desalination using hydrogel and aerogel solar evaporators based on different carbon materials

• Four kinds of safe and economical gel evaporators were constructed. • The desalination and purification performances of gel evaporators were compared. • CSH shows better evaporation effect than CSA, while GSA is higher than that of GSH. • GSA possesses the best evaporation and purification performance. Interfacial solar evaporation, which utilizes abundant and clean solar energy for wastewater desalination purification, is emerging as an environmental-friendly and energy-efficient technology for producing clean water. In this paper, sodium alginate (SA) gel evaporators based on different carbon materials were proposed. A simple and convenient evaporator was constructed by comparing the network properties of hydrogels and aerogels, as well as the photothermal conversion efficiencies of CNTs and graphene. CNTs-SA-hydrogel (CSH) had higher evaporation rate and better water purification than CNTs-SA-aerogel (CSA), with the evaporation rate of 1.60 kg m -2 h −1 and ion removal rate of 99 %. However, the evaporation performance and desalination efficiency of graphene-SA-aerogel (GSA) were better than those of graphene-SA-hydrogel (GSH). In particular, GSA gave the best performance with a pure water evaporation rate of 1.73 kg m -2 h −1 . Even in a 20 wt% high-salt wastewater, it could generate steam consistently with an evaporation rate of 1.56 kg m -2 h −1 without any significant performance degradation. In addition, it also had outstanding desalination ability and could completely decolorize in organic dyes. Therefore, this study provides a new idea to further promote the rapid development and application of interfacial solar steam generation in desalination and purification of seawater.