Improved micro oil droplet coalescence for oil/water separation by spider silk-like structures

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Separation of dispersed oil from industrial and natural waters has become an increasing worldwide challenge in order to protect the environment and to provide worldwide clean tap water. The established methods for oil droplet elimination involve either harsh conditions, expensive equipment, complex devices, complicated processing steps, high processing cost or long processing time. This study will reveal the structural influence of micro and macro geometry of fiber surfaces on oil sorption und separation from flowing aqueous media. We will analyze the fundamental principles of a local directed transport of oil droplets in water on chemically and topographically structured surfaces. This innovative biomimetic research approach for improved oil coalescence efficiency is derived from the mechanisms of droplet adhesion and coalescence on structured natural surfaces like spider web fibers. Their spindle-knots based beads-on-a-string structure promotes the coalescence of dew water droplets on the fibers. In a unique methodology, the known structure-property-relationships of droplet coalescence in the three-phase-system fiber-air-water will be transferred into the fiber-water-oil system and investigated by theoretical modelling, special fiber spinning, surface and coalescence analysis.Droplet transport (particle movement) under water, the kinetics and thermodynamics of oil droplet attachment to a water-immersed graded fiber structure and subsequent coalescence as well as superimposed pressure differences provide very complex conditions which have not yet been understood in their detailed interaction. For this purpose, the relevant biological models - priority on spider fibers - will be further investigated, models established and the oil absorption mechanism of the structures will be developed. The findings will be technically implemented by transferring the found and calculated fiber surface morphology and chemical compositions in new textile and metallic filter structures for improved coalescence and filter efficiency.