Study Of Mass Transport Characters And Small Test Of Citric Acid Separation Using Hollow Fiber Renewal Liquid Membranes

Hollow fiber renewal liquid membrane (HFRLM) technology has the advantage of high transport efficiency, stability, easily operating, non-secondary-pollution. As a novel liquid membrane technology, HFRLM technology not only keep the advantage of nonequilirium transport like liquid membrane, but also avoid the disadvantage of liquid membrane lose of supported liquid membrane (SLM) and complexity of emulsification liquid membrane (ELM).In this study, citric acid-30% N₂₃₅ /20% octanol /50% kerosene-NaOH was used as experimental system. The effect of mixing mode, velocity of feed phase and stripping phase, feed concentration, stripping concentration, carrier concentration on the mass transfer performance was studied. The results indicated that the overall mass transfer coefficient and mass transfer flux were easily affected by feed velocity, feed concentration, carrier concentration, and were not significantly influenced by stripping velocity, stripping concentration.The feasibility of extraction of citric acid by HFRLM was studied. The mass transfer characteristic of extraction and enrichment of citric acid from diluted solution by HFRLM was studied, and the process experiment was carried out. The result indicated that the circle operation had the good extraction efficiency in the range of operating condition, because the renewal process resulted in a good mass transfer coefficient. The extraction efficiency of citric acid was above 98%, which was better than calcium salt sedimentation method. The concentrated factor of [A³] in stripping phase was above 9．With five-stage HFRLM process, the experimental result indicated that the extraction efficiency was more than 98%.This paper also compared the mass transfer performances between HFRLM and membrane extraction (ME). In the similar condition, the extraction efficiency of HFRLM is over 98%, while the extraction efficiency of ME is only 65%. In case of NaOH as stripping phase, the mass transfer performance was better than Na₂CO₃ as stripping phase.Based on research results, the conclusions were supplied for more studying on mass transfer mechanism and the applying HLRLM technology.