| Caprolactam as a raw materical for fiber production must meet the requirement of high purity. It has a complex process for refining including hydrogenation, rectification, extraction, ion-exchange and so on. But they all exist some disadvantages.Hollow fiber renewal liquid membrane is a novel liquid membrane technology, which combines hollow fiber contained liquid membrane with fiber membrane technique. This technology is not only maintaining the advantages of traditional liquid membrane techniques, but also superior to them because of some specific characteristics. In this study, the experiments are carried out by Hollow fiber renewal liquid membrane to refine crude caprolactam.The process stability, one of important characteristics of hollow fiber renewal liquid membrane, and the method for making capped end was experimentally studied by using SO42-as a tracer. The leakage rate of organic membrane between tube side and shell side was measured. Effect of membrane properties, flow velocity and the concentration of tracer anion on the leakage rate were investigated. The experimental results display that the overall leakage rate of hollow fiber renewal liquid membrane is less than0.01%, demonstrating that the stability of hollow fiber renewal liquid membrane is excellent.With benzene/caprolactam solution/water as the experimental system, purification of caprolactam by Hollow Fiber Renewal Liquid Membrane (HFRLM) was carried out in PVDF hollow fiber modules. The influence of different operation conditions in HFRLM process was investigated. The results show that HFRLM can be used for refining crude caprolactam, and the overall mass transfer coefficients are linearly with the1/3power of the velocity of the strip phase. The overall mass transfer coefficients are linearly with the2/3power of the velocity of the feed phase. When the volume ratio of strip phase is1:50, the overall mass transfer performance is better. When the packing factor is small, the overall mass transfer performance is better.In the follow through study, bulk liquid membrane and HFRLM were used together to refine crude caprolactam. The change of conductivity of aqueous solution can be under5μs·cm-1and it achieves the requirement for refining. |
PDF Full Text Request