Dual-Sided Superhydrophobic Laser-Induced Graphene Evaporator for Efficient Desalination and Brine Treatment under...

The immense energy footprint of desalination and brine treatment is a barrier to a green economy. Interfacial evaporation (IE) offers a sustainable approach to water purification by efficient energy conversion. However, conventional evaporators are susceptible to fluctuations in solar radiation and the salinity of handling liquid. The present research is an innovative step toward the fabrication of superhydrophobic laser-induced graphene (LIG) interfacial evaporators for desalination and brine treatment. The fabricated dual-sided superhydrophobic laser-induced graphene (DSLIG) exhibits self-cleaning ability on both sides, enhancing salt rejection capabilities through a lotus effect. This multilayered evaporator comprises a top layer of MPES LIG and a bottom layer of PVDF AR 972 LIG, resulting in superior localized heat generation ability. The engineered surface has undergone performance analysis with DI water and NaCl solutions with concentrations of 3.5-24 wt %. The dual-stacked configuration with coupled solar (one sun)-joule heating (5 V) attained evaporation rates of ∼5 kg m^-2 h^-1 for distilled water and ∼2.2 kg m^-2 h^-1 for a 24 wt % NaCl solution. The remarkable outcome resulted from substantial thermophysical property changes with LIG formation. The DSLIG's bottom concentration gradient promoted salt back diffusion and ceased salt penetration to the top surface. The work can be further extended to treat the desalination brine for sustainable desalination and zero liquid discharge.