Membrane distillation (MD) is a promising method for treating high salinity waters since water vapor pressure is largely independent of salt concentration, making this process less sensitive to salinity then reverse osmosis. MD systems generally operate at high temperatures (~60°C), which impose a high energy cost for water treatment. Recently, nanophotonics-enabled solar membrane distillation (NEMSD), which uses direct sunlight and carbon black-coated membranes to provide localized surface heating on the membrane, was shown as a promising alternative to conventional MD for energy efficient off-grid desalination. In this project, we investigated the scaling propensity of the NESMD system in order to assess its applicability to brackish water with high scaling potential. Our results show that NESMD can resist membrane scaling due to the lower operating temperature in the feed water, which reduce calcium precipitation on the membrane. Low scale formation was confirmed by scanning electron microscopy, elemental analysis of the fouled membrane, and equilibrium speciation modelling. These results highlight the advantages of NESMD beyond energy efficiency for the treatment of high salinity water.

Scaling resistance in nanophotonics-enhanced solar membrane distillation

ACS Fall 2020 Virtual Meeting

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