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

Abstract

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.

Removal of Typical Volatile Organic Compounds in Condensed Freshwater by Activated Persulfate during Interfacial Solar Distillation

“…As some of the most prolific VOCs, phenolic compounds deserve the most attention in condensed freshwater due to their high contaminant distillation concentration ratio . Phenolic compounds with different substituent groups such as phenol, p -methylphenol, and p -chlorophenol were selected as the typical VOCs.…”

“…Phenolic compounds with different substituent groups such as phenol, p -methylphenol, and p -chlorophenol were selected as the typical VOCs. Here, the “contaminant’s distillation concentration ratio ( R D , eq )” was used to evaluate the specific contaminant’s concentration in condensed freshwater. The low R D value indicates low contaminant concentration in condensed freshwater where C D and C B are the concentrations of the contaminants in condensed freshwater and the initial simulated seawater, respectively.…”

Recent advances in structural regulation and optimization of high-performance solar-driven interfacial evaporation systems

“…During evaporation, some volatile contaminants will escape, condense, and be collected along with water vapor. Although a few studies proposed that the use of activated carbon with good adsorption capacity as a photothermal material could effectively reduce the content of volatile contaminants in condensates, 78,280 the issue of limited service life caused by adsorption saturation has not yet been resolved. Therefore, there is an urgent need to develop SIE systems for the treatment of water sources containing volatile contaminants.…”

Aerogels in passive solar thermal desalination: a review

“…A study showed that the migration of volatile and semivolatile contaminants from bulk to distilled water during the interfacial solar evaporation process highly depends on compound volatility. 110 This research showed that phenols and similar compounds with high volatilization and condensation rates could easily move to the distillate water side. Adsorption via activated carbon and photothermal oxidation were suggested as promising strategies for ensuring water safety.…”