Prediction of mass-transfer coefficient for solute transport in porous media (vol 50, pg 1, 2001)

Several previously reported laboratory studies related to transport of solu tes through packed columns were utilized to develop predictive relationship s for mass-transfer rate coefficient. The data were classified into two gro ups: those obtained under rate-limited mass transfer between mobile and imm obile water regions (physical nonequilibrium conditions), and those derived from rate-limited mass transfer between instantaneous and slow sorption si tes (sorption nonequilibrium conditions). The mass-transfer coefficient in all these studies was obtained by fitting breakthrough data to a transport model employing a first-order rate limitations with a "constant" mass-trans fer coefficient, independent of flow conditions. This study demonstrated th at the mass-transfer coefficient in these models is dependent on system par ameters including pore-water velocity, length-scale, retardation coefficien t, and particle or aggregate size. Predictive relationships were developed, through regression analysis. relating mass-transfer coefficient to residen ce time. The developed relationships adequately estimated previously report ed field mass-transfer values. Successful simulations of field desorption d ata reported by Bahr [J. Contain. Hydrol. 4 (1989) 205] further demonstrate the potential applicability of the developed relationships. (C) 2001 Publi shed by Elsevier Science B.V.