Designing and evaluating superhydrophilic nanofiber mats for catching fog in the atmosphere

Abstract

This project is aimed at developing and characterizing electrospun polyacrylonitrile (PAN) and polyvinyl chloride (PVC) nanofiber mats to effectively catch fresh water from fog in the atmosphere. The demand for fresh water is continually increasing. Approximately 2.8 billion people in the world have at least one month of clean water shortages, and 1.2 billion people lack access to clean drinking water. This problem can be solved effectively utilizing new technologies in a cost-effective manner. It is estimated that the atmospheric fresh water found on the earth is about 8% of the total surface water. Although desalination could create a much higher amount of available freshwater to the world's population, it is a fairly costly, energy-intensive, and time-consuming process. In order to address some of the water scarcity concerns, the electrospinning technique was used to produce superhydrophilic nanofibers to absorb the water in a foggy atmosphere. In this study, PAN and PVC powder were separately blended with polyvinylpyrrolidone (PVP), chitosan, and polyethylene glycol (PEG) at 0, 4, 8, 16, and 32 wt%, and dissolved in dimethylformamide (DMF) and acetone at different ratios (90:10). Prepared solutions were electrospun at different DC voltages, pump speeds and tip-to-collector distances. The produced nanofibers were characterized using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and water contact angle measurements. The fibers were mainly in the nanosize range with uniform shapes and few beads. At higher concentrations (e.g., 16 and 32 wt%) of PVP, PEG, and chitosan, most of the electrospun fibers were superhydrophilic (water contact angle < 5? in 0.5 seconds). Humidifier tests indicated that superhydrophilic fibers collect fog up to 58% of their weight, which indicates that these functional materials can be utilized to catch fog in air in locations where water is scarce.