Enhanced naphthalene solubility in the presence of sodium dodecyl sulfate:effect of critical micelle concentration

Surfactants can increase the solubility of non-polar compounds, and have be en applied in areas such as soil washing and treatment of non-aqueous phase liquids (NAPLs). This investigation explored the feasibility of removing v apor phase polycyclic aromatic hydrocarbon (PAH) from gases using an anioni c surfactant. The solubility of vapor phase naphthalene was measured herein using gas chromatograph (GC) with a photon ionization detector (PID). The measurement results indicated that surfactant molecules were not favorable to micelle formation when temperatures increased from 25 degreesC to 50 deg reesC. Regardless of whether solutions were quiescent or agitated, equilibr ium naphthalene apparent solubility increased linearly with surfactant conc entrations exceeding critical micelle concentration (CMC). The pH effects o n naphthalene apparent solubility were small. Agitation increased naphthale ne apparent solubility and lumped mass transfer coefficients. Furthermore, lumped mass transfer coefficients decreased with increasing surfactant conc entration owing to increase in interfacial resistance and viscosity and dec reased spherical micelle diffusion coefficients. Finally, the net absorptio n rate increased because the solubilization effects of micelles exceeded th e reduction effects of mass transfer coefficient above the CMC. The enhance d naphthalene apparent solubility from the addition of surfactant can be ex pressed by an enrichment factor (EF). The EF value of naphthalene for the s urfactant solution at 0.1 M with agitation at 270 rpm relative to quiescent water could reach 18.6. This work confirms that anionic surfactant can imp rove the removal efficiency of hydrophobic organic compound (HOC) from the gas phase. (C) 2001 Elsevier Science Ltd. All rights reserved.