Purge and trap method to determine alpha factors of VOC liquid-phase mass transfer coefficients

A theoretical approach and laboratory practice of determining the alpha fac tors of volatile organic compound (VOC) liquid-phase mass transfer coeffici ents are present in this study. Using Purge & Trap Concentrator, VOC spiked water samples are purged by high-purity nitrogen in the laboratory, the VO C liquid-phase mass transfer rate constants under the laboratory conditions are then obtained by observing the variation of VOCs purged out of the wat er with the purge time. The alpha factors of VOC liquid-phase mass transfer coefficients are calculated as the ratios of the liquid-phase mass transfe r rate constants in real water samples to their counterparts in pure water under the same experimental conditions. This direct and fast approach is ea sy to control in the laboratory, and would benefit mutual comparison among researchers, so might be useful for the study of VOC mass transfer across t he liquid-gas interface.