Solar-driven interfacial evaporation based on double-layer polylactic acid fibrous membranes loading Chinese ink nanoparticles

Abstract Freshwater is a crucial resource for human life existence, diminishing freshwater resources and ever-increasing water demand had sprouted interest in desalination and water recycling. Solar energy has been utilized as an alternative to fossil fuels for energy requirements in water recycling. Efficient photo-thermal conversion materials and evaporation module are indispensable for such systems. In the current study, an innovative double-layer interfacial evaporation module of polylactic acid (PLA) fibrous membrane loaded with Chinese ink nanoparticles is synthesized. Electrospun layer of micro-scale diameter with enhanced hydrophilic properties is employed as water transport layer, while solution of electrospun layer of nano-scale diameter fiber loaded with Chinese ink nanoparticles functioned as evaporation interface. Ideal dispersion of Chinese ink nanoparticles in the PLA nanofiber is ensured with Field Emission Scanning Electron Microscopy (FE-SEM). Experiments with designed evaporation module indicates that double-layer membrane with 2 wt% Chinese ink nanoparticles has achieved an evaporation rate of at 1.29 kg cm−2 h−1 at 81.0% efficiency under simulated sunlight with a illumination intensity of 1 sun (1 sun = 1 kW/m2), which is significantly higher than the pure water and conventional membranes without Chinese ink nanoparticles. The developed fibrous membrane is able to retain its enhanced characteristics even after 20 cycles under same operating conditions during the durability test. The designed evaporation module is a promising candidate for conversion of waste water to clean water.