Effect Of Surfactants On The Henry's Law Constant Of N-Hexane

With the rapid development of industry, large-scale industrial production activities and the use of chemical medicines,large volatile organic compounds (VOCs) waste gas was emitted, which resulted in serious environmental pollution and threatened human health. Relevant volatile organic compounds control and removal technology has became the concern of academic research and development in the industry. Biological filtration technology is emphasized specially due to its low cost and environment friendly.n-Hexane biological removal is intrinsically limited by its hydrophobic nature and low bioavailability. Biofiltration of hydrophobic volatile pollutants such as n-hexane is limited by poor transfer of the pollutants from the gaseous to the liquid biotic phase, where biodegradation occurs. A key process involved in a gas-phase biofilter is the transport of VOCs from the gas phase to the aqueous phase. This process frequently is assumed to be related to vapor-liquid partition coefficients or Henry's law constants. The addition of surfactants could enhance transport and bioavailability of volatile organic compounds (VOCs) and change the gas-liquid equilibrium of VOCs. This study was motivated to explore the feasibility of surfactant enhanced gas-phase biological filtration for hydrophobic volatile organic compounds removal and provide theoretical references and support. In this paper, the effect of four surfactants, sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB), tert-octylphenoxypoly-ethoxyethanol (Triton X-100), polyoxyethylene (20) sorbitan monooleate (Tween 80) and sodium nitrate on the apparent Henry's constant of n-hexane in surfactant solutions were investigated, as well as the effect on extramicellar fraction.The apparent Henry's constants were significantly reduced when the surfactants concentrations exceeded their critical micelle concentrations (CMC's). On a CMC basis, the anionic surfactant SDS has the greatest effect on the apparent Henry's constant of n-hexane, followed by CTAB, Triton X-100, and then Tween 80. At 27℃, On the 6 CMCs, the apparent Henry's constant of n-hexane decreased from 40.7 to 2.4. However, the apparent Henry's constant of n-hexane decreased even more rapidly when Triton X-100, a nonionic surfactant, was added than when the ionic surfactant of SDS or CTAB was added at an identical mass concentration. When the Triton X-100 concentration increased to 3.0 g L-1, the apparent Henry's constant of n-hexane decreased to 6.44. These results suggest that Triton X-100 would be the most suitable candidate among the four surfactants only in solubilization and bioavailability of n-hexane. Sodium nitrate slightly decreased the apparent Henry's constant of n-hexane in surfactant solutions, and could be considered as a cosolvent in surfactant-(n-hexane) solution. In addition, the relationship between apparent Henry's constant and surfactant concentration is been further developed.