Eliminating Magnetic Forces from the Surface Tension Measurement of Magnetic Surfactants

Koehler, Emily (2016) Eliminating Magnetic Forces from the Surface Tension Measurement of Magnetic Surfactants. Undergraduate thesis, under the direction of Paul Scovazzo from Chemical Engineering, University of Mississippi.

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Abstract

Surfactants have many applications due to their ability to reduce the surface tension between two phases. Magnetic surfactants, a relatively new form of surfactants, offer the possibility of further controlling a surfactant system by using an external magnetic field to induce alignment on the molecular level. One method of studying a magnetic field’s effect on the magnetic surfactant system involves analyzing the change in surface tension at varied solution concentrations both in and outside a magnetic field. The pendent drop method uses the downward gravitational force on a droplet suspended from a needle to find the surface tension based on the drop’s shape. Previous results with the magnetic surfactant [C16TA]2CoCl2Br2 show an overall decrease in the surface tension of the solution when suspended over a permanent magnet. While this change could point to the surfactant’s molecular realignment, permanent magnets produce a magnetic field gradient that could directionally pull the surfactant towards the magnet, potentially acting as a downward force not accounted for in the pendent drop correlations that only use gravity. This scenario would also result in a calculated surface tension change. We continued the initial investigation by replicating it with the magnetic surfactant C16TAFeCl3Br as well as analyzing its surface tension inside a parallel magnetic field to remove the gradient and eliminate the opportunity for varied effective gravity on the drop. The obtained results match the trend of a surface tension reduction when inside a magnetic field which suggests the idea of induced alignment of the surfactant; however, the data only supports this clearly when using the higher magnetic field levels.

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