Mass transfer coefficients from pendant water drop measurements in compressed carbon dioxide

摘要

Mass transfer coefficients were determined in the two-phase system of water/compressed carbon dioxide at three temperatures of 297,313 and 335 K,and in the pressure range of 6-25 MPa.Mutual Mass transfer of the two components,water and carbon dioxide was investigated in the binary system,and extraction of phenol from an aqueous droplet by carbon dioxide was studied in a ternary system.In all systems a pendant water drop was formed at the tip of a capillary and was exposed to the quiescent surrounding carbon dioxide for a definite time.To obtain mass transfer coefficients from experimental data,such as drop volume and phenol concentration as a function of contact time,a model was used that divides the transport process into three steps: transport towards the interface,passage through the interface,transport straight away from the interface.Depending on the particular system,only one or two of these steps were considered to have a rate-determining function.