Egg-beater like trichomes of water ferns an inspiration in the fabrication of Nanofur for the remediation of oil spills.
Worldwide consumption of oil and petroleum has risen highly and along with this rise in consumption, environmental concerns too have surfaced at large. The greatest environmental concern other than the burning of fuels is the remediation of oil spills and oil in wastewater. Oil on the surface of water bodies is toxic to all living beings. It decreases the availability of oxygen to marine life leading even to death. Chemical dispersion and controlled burning are the most conventional methods for removal of oil from water bodies but are potentially toxic and also cause secondary pollution. Selective absorption of oil with the help of special sorbents has been a recent choice in the removal of oil spills.
Most available sorbents are made of polymeric sponges, fabrics coated with metal or metal oxide, metal meshes, and silicon compounds or nanoparticles. All these methods are with certain limitations such as their absorption capacity, harmful production, usage or disposal issues and often are not cost effective. Most sorbents along with the absorption of oil also tend to absorb water.
Biological treatment of oil spills
Sawdust, aquatic plants, wheat straw and milkweed fibers have been used to absorb oil spills, while they work effectively, they also absorb water. Hydrophobicity is a characteristic of many biological surfaces. Plant and animal surfaces are well known for their waxy outer covering that is hydrophobic in nature and protects against evaporation and damage by water. Studies performed on aquatic floating ferns Salvinia molesta, Pistia stratiotes and Nelumbo nucifera show adaptations that further help the leaves to keep water away and to ensure buoyancy. The leaves have self-cleaning properties and are covered by hairy structures called trichomes. The trichomes are largely present in Salvinia and Pistia and are made of convex cells that are superimposed with nanoscale wax crystals. These trichomes not only repel water but also trap air in them to keep the leave buoyant.
These plants grow in abundance in water bodies and are considered pests but they are nature’s gift for water treatment and are efficient in the removal of heavy metals and other substances. They act as natural oil sorbents and can be employed for treatment of oil spills. The whole leaves of these plants were studies for to determine their oil absorption efficiencies and compared against synthetic oil sorbents available. Salvinia gave the best results and owing to the nature of their trichomes and have been identified as a suitable biological alternative for oil spill remediation.
Bioinspired nanofur material
Researchers at Germany’s Karlsruhe Institute of Technology along with scientists at Bonn University on realizing that Salvinia leaves owed their oleophilic attributes to trichomes on their surface set out to fabricate “nanofur” which is inspired by the structure of the leaves. The egg-beater shaped trichomes of Salvinia did not absorb water due to high surface tension but their waxy coating allowed them to absorb oil. The same principle was applied in the fabrication of nanofur and has been applauded as successful and for the insight gained from nature.
Microstructures of superhydrophobic plant leaves - inspiration for efficient oil spill cleanup materials. Zeiger C, Rodrigues da Silva IC, Mail M, Kavalenka MN, Barthlott W, Hölscher H. Bioinspir Biomim. 2016 Aug 16; 11(5):056003. [PMID:27529805]