Mass transfer characteristics of citric acid extraction by hollow fiber renewal liquid membrane

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.