Improved micro oil droplet coalescence for oil/water separation by spider silk-like structures
Lightweight Construction, Textile Technology
Final Report Abstract
The research work in the project led to the following scientific results: The analysis of the biological model, web (capture-silk) of cribellate spider, revealed the dynamic interaction between the highly puffed elastic nanofibers and the periodic spindle-knots with water droplets. - The dynamics of the directed motion of droplets on a surface with geometric gradients in another fluid medium were studied in detail, modeled numerically, and the derived formulas were validated with experiments. - The developed theoretical model allowed the calculation of the time-dependent movement of droplets as a function of system-relevant parameters such as the geometric properties (length of the filament, half-apex angle and contact angle) and the wetting and viscoelastic properties of the two fluids. - Based on the theoretical findings, new material structures for oil extraction could be calculated and fabricated by 3D printing, dip- and spray-coating and electrospinning. - The electrospinning process was used to develop two types of membranes with spindle-knotted fibers: (i) underwater oleophilic and (ii) underwater superoleophobic. - The separation effect of oil droplets in water by the electrospun filter media with spindle-knotted fibers could be predicted with good accuracy using the developed theoretical model. - To quantify the separation efficiency of the filter membranes in oil/water separation, a test stand with the new separation processes and a corresponding filter housing was designed, built and used. - A new measurement and evaluation method were developed to evaluate the dynamic contact angle of fibers with a spindle-knot structure. The knowledge gained thus extends the basic knowledge on bionic, new materials with geometric gradients for the separation of oil-in-water emulsion. The developed numerical models allow the calculation of the geometric gradients of the fibers of the filter medium, which enable effective fluid separation. The aim is to achieve rapid coalescence of the fine oil droplets on the filter medium in order to force the oil to rise rapidly for subsequent mechanical separation from the water. Applications of the new findings include functional surfaces with droplet transport phenomena such as for the treatment of oily water mixtures, water collection systems, and microfluidic devices operated with one or more fluids.
Publications
- 2020. Bionics/Biomimetic in Textile Research. Journal of Textile Engineering and Fashion Technology, 2(1), 6-7
Stegmaier, T., Aliabadi, M., von Arnim, V., Kaya, C., Sarsour, J., and Gresser, G.
- 2021. A novel method for measuring dynamic contact angles of fibers with spindle‐knots. Journal of Applied Polymer Science, 138(28), p.app50673
Aliabadi, M., Konrad, W., Stegmaier, T., von Arnim, V., Kaya, C., Liu, Y., Zhan, B., Wang, G. and Gresser, G.
(See online at https://doi.org/10.1002/app.50673)
