Thermodynamics of volatile organic compounds in PDMS by simple modified headspace method

An improved and modified experimental apparatus for the simple headspace technique was developed and modified for the determination of Henry's law constants and infinite dilution activity coefficients of VOC in silicon oil. The experimental design confirmed that equilibrium can be achieved within a reasonable time period. Infinite dilution activity coefficients and Henry's law constants for various organics representing esters, ketones, alkanes, aromatics, cycloalkanes, and amines were studied at 303 K. The static determined activity coefficients using shaker flasks were comparable to those obtained using the gas liquid-chromatographic technique. Based on thermodynamic knowledge, Henry's law constant and activity coefficients at infinite dilution played a very crucial role in the design of scrubbers for abatement of VOC from contaminated air streams. In most separation processes, this was the most difficult and expensive part of separation. The greatest deviation from ideal behavior was shown. Infinite dilution studies were also crucial in obtaining high purity products. This is an abstract of a paper presented at the 8th World Congress of Chemical Engineering (Montréal, Quebec, Canada 8/23-27/2009).