Existing means of concentrating and crystallizing salts in brines are expensive, consume large amounts of energy and produce wastes that are challenging to manage. Solar-driven interfacial evaporation has been proposed as a sustainable, energy-efficient strategy for desalination of high-salinity brines. Recent studies evaluating graphene-oxide (GO) materials for enhanced seawater evaporation have reported significant salt accumulation on the evaporator surface. After the precipitate layer reaches a certain thickness, the salt solids begin to naturally fall off the evaporator due to gravity, presenting the opportunity for collection. Salt harvesting is particularly attractive for inland geographies, where ocean disposal is not feasible and other options are limited by cost and availability. However, the precipitation behavior of complex solutions containing salts of varying solubilities (i.e., calcium carbonate and sulfate versus sodium chloride) is not well understood. To assess the potential for salt separation and recovery, this study is developing a model for brine evaporation and salt precipitation on a GO evaporator with a stalk configuration, with the goal of using it to predict the evolution of brine chemistry and spatial salt deposition during evaporation of groundwater RO brines. The benefits of interfacial evaporation as a passive, solar-driven solution for inland brine evaporation will be evaluated by considering the diverse range of groundwater chemistries encountered in landlocked locations.

Solar-driven interfacial evaporation for inland brine volume reduction with salt harvesting

ACS Spring 2022

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