Hierarchical structured PVA-PLA nanofibrous membrane with water-chestnut-like surface morphology for water harvesting

In order to solve the problem that there is no clean water to drink in many parts of the world, researchers are trying to explore some unconventional strategies to take water from nature, such as fog collection. Herein, we constructed a hydrophilic/hydrophobic composite membrane with unique surface morphology by electrospinning as a new collection system. The surface layer is composed of water chestnut-like PVA particles, and the bottom layer is composed of directional polylactic acid fibers. The force acting on the droplets moving between the needle and the collector is studied in detail to explain the formation mechanism of water chestnut-like PVA particles. The small droplets formed by low concentration PVA solution are mainly affected by gravity electric field force. Due to the gradual volatilization of solvent, the decrease of concentration easily leads to the generation of beads. Due to the poor volatility of water, droplets continue to flow downward under the action of gravity and form water chestnut-like particles. When collecting fog, the area of water chestnut particles is larger than that of fibers, which make water droplets condense faster, and directional polylactic acid then conveys the collected fog water. Taking advantage of the synergistic cooperation of two regions, the surface can collect water with the collecting efficiency as high as 57 mg cm-2 h-1. There is no doubt that these functional composite membranes will provide a new idea for developing a new way to solve the global water shortage problem.

Automated summary

Researchers are exploring unconventional strategies to collect clean water from nature, such as fog collection using a hydrophilic/hydrophobic composite membrane. The unique surface morphology of the membrane, composed of water chestnut-like PVA particles, plays a key role in improving collecting efficiency and may offer a new solution to the global water shortage problem.