IIT-Bombay researchers develop solar evaporators for desalination

Researchers at the Indian Institute of Technology IITBombay have developed a new material that can facilitate water desalination and help in addressing the growing freshwater crisis in the world reported PTIProfessor Swatantra Pratap Singh and Aiswarya CL from IITBombay have developed the material called the DualSided Superhydrophobic LaserInduced Graphene DSLIG evaporator the institute said on WednesdayThe device addresses multiple shortcomings of earlier evaporators and has the potential for largescale applications This evaporator can be heated by both solar energy and also by electricity ndash known as Joule heating ndash the institute informed according to PTIFreshwater scarcity a significant issue in various parts of the world is expected to intensify in the coming yearsWhile water is abundant on Earths surface only about 3 per cent of it is freshwater and even within that less than 005 per cent is easily accessible and removing salt from seawater and brackish water is seen as one of the solutions to address this problemHowever brine ndash concentrated salt solution ndash from desalination poses a major problem in landlocked places and industries are looking for zero liquid dischargeBy combining both solar and electric heating the material is protected from fluctuationsFluctuations in solar radiation cause temperature variations on the evaporators surface On cloudy days the performance of the interfacial system is halted due to the lack of solar energy Additionally the variation in solar radiation during the day affects the evaporation process with evaporation rates typically peaking around 2 pm when solar intensity is highest Professor Singh explained according to PTIBy combining both solar and electric heating the material is protected from fluctuations in the availability of sunlight When there is less or no sunlight electricity can be used to heat the evaporator and maintain similar temperatures ensuring consistent performance he notedAdditionally DSLIG has a superhydrophobic property which means it can repel water like lotus leavesProf Swatantra Pratap Singh amp Aiswarya C L from IITB have developed a new hydrophobic graphene based material that facilitates water desalination httpstcodxNmLeGeoj pictwittercom5qenRXlwVcmdash IIT Bombay iitbombay April 16 2025Thus superhydrophobic materials reduce the contact area between water droplets and the material surface making droplets roll over them instead of wettingIn desalination applications the superhydrophobic nature of DSLIG helps prevent salt dissolved in water from sticking to the evaporator surface thus maintaining efficiency over timeThe primary goal of our work was to create a superhydrophobic surface exhibiting the lotus effect capable of functioning with both solar and Joule heating added Professor SinghThe researchers fabricated DSLIG by coating a layer of a polymer called polyvinylidene fluoride PVDF on one side of a thin layer of another polymer LIG poly ether sulfone PES Graphene was then engraved on the PVDF polymer side of the material using laserbased engraving technologyLaboratory tests showed DSLIG not only exhibits lotus leaflike behaviour preventing salt deposition and excellent efficiency for desalination under both electric and solar heating but is also very effective in treating extremely concentrated salt solutionsThis made it an ideal candidate for treating salt water discharges from other desalination outlets as well as industrial wastewaterThe researchers also found that the performance of DSLIG improved when multiple evaporators were stacked on top of each otherWith PTI inputsatOptionskeyd0ddb8ef8f1a62a8cdd22fac27fc5ea7formatiframeheight90width728params