Use of Superhydrophobic Column Wall for Drag and Dispersion Reduction in Liquid Chromatography
Tamoghna Saha,
Research Scholar,
Indian School of Mines, Dhanbad
Liquid chromatography (HPLC) suffers from two major bottlenecks namely huge pressure drop requiring high pressure for driving flow through the narrow packed columns and axial dispersion effects which affects analytical resolution in between similar components. The two drawbacks can be overcome by introducing slip at the column wall that imparts plug like nature to the flow. A viable option available for inducing slip is to employ superhydrophobic (SH) column walls that have characteristic depression and elevations. When submerged, SH surfaces acquire Cassie Baxter configuration: the depression trap air generating a liquid–air interface, allowing slip during flow. Herein, use of SH wall is explored in narrow packed columns. Experiments involve establishing a gravity driven flow through a tailor made packed superhydrophobic column (7 mm -20 mm) by lining inner wall with lotus leaf. The parameters measured are the enhancement in flow rate and the residence time distribution. Mass flow enhancement of 20-30 % is observed for turbulent flow, suggesting reduced drag. Sharper peaks in RTD and a lower dispersion number (~0.04) for SH column are obtained, suggesting the beneficial role of slip in reducing axial dispersion. The findings provide proof-of-concept of the immense scope of using SH columns in chromatography.
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