Absorption and recovery of n-hexane in aqueous solutions of fluorocarbon surfactants

n-Hexane is widely used in industrial production as an organic solvent. As an industrial exhaust gas, the contribution of n-hexane to air pollution and damage to human health are attracting increasing attention. In the present study, aqueous solutions of two fluorocarbon surfactants (FSN100 and FSO100) were investigated for their properties of solubilization and dynamic absorption of n-hexane, as well as their capacity for regeneration and n-hexane recovery by thermal distillation. The results show that the two fluorocarbon surfactants enhance dissolution and absorption of n-hexane, and their effectiveness is closely related to their concentrations in solution. For low concentration solutions (0.01%–0.30%), the partition coefficient decreases dramatically and the saturation capacity increases significantly with increasing concentration, but the changes for both are more modest when the concentration is over 0.30%. The FSO100 solution presents a smaller partition coefficient and a greater saturation capacity than the FSN100 solution at the same concentration, indicating a stronger solubilization for n-hexane. Thermal distillation is a feasible method to recover n-hexane from these absorption solutions, and to regenerate them. With 90 sec heating at 80–85°C, the recovery of n-hexane ranges between 81% and 85%, and the regenerated absorption solution maintains its original performance during reuse. This study provides basic information on two fluorocarbon surfactants for application in the treatment of industrial n-hexane waste gases.

Aqueous solutions of two fluorocarbon surfactants (FSN100 and FSO100) were investigated for their properties of solubilization and dynamic absorption of n-hexane. The relationship between the n-hexane absorption saturation concentration and partition coefficient for the FSO100 and FSN100 solutions is not a linear correlation. For low concentration solutions (0.01%–0.1%), a small decrease of the partition coefficient corresponds to a large increase in the saturation concentration. However, with a further decrease of the partition coefficient (0.1%–1.0% of the absorbent concentration), the increase of the saturated absorption concentration becomes slower. This shows that the dynamic absorption process of n-hexane cannot be fully explained by the partition coefficient and is also influenced significantly by operating conditions.Figure optionsDownload as PowerPoint slide