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Theoretical relation derived in the last study for calculation of the mass transfer coefficient in the region of not fully developed concentration profile at high Schmidt numbers has been verified experimentally. This experimental study has been devoted to measurements of the rate of benzoic acid dissolution into aqueous solutions of glycerol from the internal surface of the pipe of circular cross section in the range 933 ⪬ Sc ⪬ 225 000 and 5 000 ⪬ Re ⪬ 50 000. It has been possible to explain on basis of the theoretical model, the differences between the data of various authors and to obtain a unified description of the phenomena.

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Various methods have been discussed of experimental measurement of interfacial mass transfer under the turbulent flow in a tube at high values of the Schmidt number. Difficulties and shortcomings have been discussed of the determination of the mass transfer coefficient k∞+, i.e. the quantity necessary for experimental verification of theoretical models. Necessity has been stressed of devising special experiments to further elucidate the mechanism of interfacial heat and mass transfer in the turbulent flow.

It has been shown in the paper that under the turbulence (Re > 104) and at high values of the Schmidt number (Sc > 103), when the principal resistance to mass transfer is concentrated in the laminar layer immediately adhering to the interface, significant instabilities appear induced by the turbulent disturbances in the neighbouring transition layer, or by the discontinuities at the interface. Parameters have been determined characterizing this phenomenon on the basis of experimental data and their values have been compared with the data published in the literature as characteristics of the periodic viscous sublayers.