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Abstract: Hollow fiber renewal liquid membrane (HFRLM), a new liquid membrane technique inspired from surface renewal theory, is used to simultaneously remove and recover copper from acidic wastewater. The commercial extractant, LIX984N, is used as a carrier in liquid membrane phase, kerosene used as a diluent. CuSO4 solutions is used to simulate acidic industrial wastewater, in which the pH is adjusted by dilute H2SO4. The mass transfer mechanisms of the process are investigated. As a carrier-facilitated transport process, the addition of LIX984N in the liquid membrane phase can greatly improve the transport performance; the organic/aqueous stripping volume ratio from 1:10 to 1:7 on lumen side mixture is better in terms of the renewal effect and diffusion resistance. The higher pH in the feed phase (>3) and H2SO4 concentration in the stripping phase around 2.0molL−1 are favorable for the transport process due to the increase of mass transfer driving forces. The mass transfer fluxes increase with increasing flow rates on two sides. The countercurrent cascade experiments show that the HFRLM process could carry out the simultaneous removal and recovery of copper from wastewater successfully. The modeled results based on the surface renewal theory demonstrate a good agreement with experimental data. [Copyright &y& Elsevier]

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]

Abstract: A new liquid membrane technique, hollow fiber renewal liquid membrane (HFRLM), is used for simultaneous extracting and concentrating citric acid from dilute solutions. The organic phase of 30% N235+20% n-octanol+50% kerosene was used as liquid membrane phase, NaOH as stripping phase. Experiments were performed as a function of operation mode, carrier concentration in the organic phase, initial citric acid concentration in the feed phase, NaOH concentration in the stripping phase, etc. The results showed that the HFRLM process was very stable. The transport of citric acid from membrane phase to the stripping phase was the rate-controlling step for this process. The stirred mixture of the stripping phase and the organic phase flowed through the lumen side of the module could provide a higher mass transfer rate. The transport studies with a recycling experiment indicated that HFRLM was a promising recovery method for separation and concentration of compounds from dilute solutions. [Copyright &y& Elsevier]