Interfacial Solar Distillation for Freshwater Production: Fate of Volatile and Semivolatile Organic Contaminants

Interfacial solar distillation (ISD) is an approach with low cost and low energy demand useful for seawater desalination and freshwater production. However, the commercial potential of ISD for applications such as polluted seawater desalination or industrial wastewater reuse may be hindered by low rejection of volatile and semivolatile contaminants. For the first time, the results of this study showed that the transport (from bulk water (B) to distilled water (D)) of volatile and semivolatile contaminants during the solar desalination process was highly correlated with compound volatility ( R 2 = 0.858). The obtained relationship was verified to be capable of predicting the distillation concentration ratio ( C D / C B,0 ) of different contaminants ( K H = 6.29 × 10 –7 –2.94 × 10 –4 atm·m 3 ·mol –1 ) during the ISD process. Compounds such as phenols, which have relatively high volatilization and condensation rates, deserve the most attention as potential contaminants in the distilled water. Meanwhile, other compounds that are more volatile than phenol condensed less in distilled water. Adding an activated carbon adsorbent or a photothermal oxidant is a promising strategy to effectively mitigate the distillation of contaminants and ensure water safety. These results fill the knowledge gap in understanding the transport of volatile and semivolatile compounds in ISD for the treatment of complex source waters.