Abstract
The aim of this study was to compare the solubility of
selected volatile organic compounds in water and silicon oil using the
simple static headspace method. The experimental design allowed
equilibrium achievement within 30 – 60 minutes. Infinite dilution
activity coefficients and Henry’s law constants for various organics
representing esters, ketones, alkanes, aromatics, cycloalkanes and
amines were measured at 303K. The measurements were
reproducible with a relative standard deviation and coefficient of
variation of 1.3x10-3 and 1.3 respectively. The static determined
activity coefficients using shaker flasks were reasonably comparable
to those obtained using the gas liquid - chromatographic technique
and those predicted using the group contribution methods mainly the
UNIFAC. Silicon oil chemically known as polydimethysiloxane was
found to be better absorbent for VOCs than water which quickly
becomes saturated. For example the infinite dilution mole fraction
based activity coefficients of hexane is 0.503 and 277 000 in silicon
oil and water respectively. Thus silicon oil gives a superior factor of
550 696. Henry’s law constants and activity coefficients at infinite
dilution play a significant role in the design of scrubbers for
abatement of volatile organic compounds from contaminated air
streams. This paper presents the phase equilibrium of volatile organic
compounds in very dilute aqueous and polymeric solutions indicating
the movement and fate of chemical in air and solvent. The successful
comparison of the results obtained here and those obtained using
other methods by the same authors and in literature, means that the
results obtained here are reliable.