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Abstract: The facilitated transport of Cr(VI) through a bulk liquid membrane (BLM) is investigated, using the commercially available solvent tri-n-butyl phosphate (TBP) as mobile carrier. The influences of the carrier concentration in the liquid membrane phase, the HCl concentration of the feed phase, and the stripping concentration on the mass transfer process are studied. The transport rate of Cr(VI) increases with increasing the TBP concentration and HCl concentration. The increasing of the stripping concentration improves the stripping process until a plateau is reached. A kinetic model is used to describe the Cr(VI) transport behavior, assuming that it obeys the kinetic laws of two consecutive irreversible first-order reactions. The experimental data fits reasonable well with the derived model. The analysis of the accumulation of Cr(VI) in the liquid membrane phase and the discussion of the rate-controlling step under different experimental conditions are carried out. The magnitude of the value of k e and k s is found to be 10−4–10−5 s−1, and is well in agreement with other studies. [Copyright &y& Elsevier]

A better conversion enhancement of esterification between acetic acid and n-butanol was achieved in a catalytically active membrane reactor ( p CAMR) when compared to that in a traditional inert membrane reactor (IMR). This enhancement was attributed to a novel composite catalytically active membrane in which a highly porous catalytic layer was introduced. SEM images showed that the membrane consisted of three layers: the top layer was a highly porous catalytic layer with massive macrovoids and “sponge-like” pores, the middle layer was a dense polyvinyl alcohol selective layer, and the bottom layer was a porous polyethersulfone support layer. The preparation of a highly porous catalytic layer instead of a dense one in the composite membrane greatly decreased the overall mass transfer resistance of the reactor from 6.7 × 10 5 to 5.6 × 10 5 s/m, a value which is even comparable to that of IMR (5.1 × 10 5 s/m) where the additional catalytic layer was absent. The effects of operational parameters on the esterification-pervaporation coupling performance in p CAMR were systematically evaluated. Through a reasonable match between reaction rate and water removal rate, a genuine in-situ water removal at a molecular lever was realized. For comparison, coupling performances in an IMR and a catalytically active membrane reactor with a dense composite membrane ( d CAMR) were also investigated. Results showed that the coupling performance in p CAMR outperformed both IMR and d CAMR due to a combination of much lower overall mass transfer resistance and higher mass transfer driving force for water removal in p CAMR. After 45 h at 85 °C, the acid conversion in p CAMR reached almost completion, an approximately 43% of conversion enhancement was achieved when compared to equilibrium conversion. [ABSTRACT FROM AUTHOR]