Study of direct drinking water production and sea salt recovery from photothermal conversion based on MWCNTs

The use of solar desalination is expected to solve the problem of water scarcity. Based on this, MWCNTs were loaded on filter paper and assembled into a MWCNTs disc evaporator using cotton threads as water channels in this paper. MCED with different loadings were prepared, and the photothermal conversion performance of MCED was evaluated through experiments. The results showed that the evaporation rate of 0.7-MCED at one solar intensity could reach 1.3134 kg/m2 h; the efficiency of solar separation of vapor and salt was 77.63 %. Meanwhile, after a 7-day evaporation cycle of 0.3-MCED, salt crystallizes at the edge of MCED under light and is recovered by gravity shedding during darkness, and the freshwater collection rate and salt recovery rate are 0.82 kg m−2 h−1 and 38.24 g m−2 h−1, realizing efficient and continuous water collection and salt recovery. In addition, MCED can generate voltage through water evaporation. This work demonstrates a solar evaporator that can be used for continuous seawater desalination as well as salt recovery and power generation, and provides a new direction for the design of photothermal modulation of MWCNTs and solving the salt crystallization problem for solar desalination.