| NaA zeolite membrane has excellent dehydration performance for organic solvents,extremely high mechanical strength and chemical stability,and becomes a newpervaporation membrane with great application prospects.Since NaA zeolite membranes were firstly commercialized by Mitsui Co.,Ltd.in 1999,the synthesis technology of NaA zeolite membranes has been developed rapidly,and several companies worldwide have been able to provide commercial NaA zeolite membranes.Currently,NaA zeolite membranes are mainly used in the pervaporation process for separating alcohol/water（sethanol,IPA etc.）Further expanding and deepening the application scope of NaA zeolite membranes has become a research hot spot in related fields.This master thesis report two potential industrial applications of NaA zeolite membranes,namely the purification and reuse of waste N-methyl-2-pyrrolidone（NMP）solutions in the lithium battery industry and treatment and recycling of the waste ethanol mother liquor containing sodium pyruvate in the pharmaceutical industry,and studied the fouling and regeneration of NaA zeolite membrane in the above-mentioned used processes.1.A systematic investigation of dehydration,purification and reuse for the waste N-methyl-2-pyrrolidone（NMP）solution generated in the manufacturing process of lithium ion batteries was carried out using mass produced NaA zeolite membranes in a pervaporation separation route.Firstly,mass produced NaA zeolite membranes were successfully prepared on commercial tubular ceramic supports by the modified“in-situ aging-microwave heating”method.Secondly,the pervaporation performance of NaA zeolite membranes used for NMP dehydration was systematically investigated,and the effects of feed temperature,composition,feed flow rate and membrane downstream pressure on pervaporation dehydration performance were obtained.Thirdly,for the first time,the membrane fouling behavior of NaA zeolite membranes operating in NMP waste solution for a long time was investigated.The results show that the membrane surface cover by the polymeric compound of small organic molecules in the oxidized NMP solution is the main reason for the membrane fouling.Subsequently,the regeneration of the fouled NaA zeolite membranes showed that the NaA zeolite membranes with the normalized flux after fouling（i.e.,total flux of fouled membrane divided by total flux of fresh membrane）higher than 0.5 could be recovered completely after chemical cleaning.Finally,a pilot-scale test of the NMP recovery using the NaA zeolite membrane（effective membrane area of 7.3 m2）was successfully completed at the site of the lithium battery production line of AVIC Lithium Battery（Luoyang）Co.,Ltd..All technical indicators of the refined recycling products（NMP≥99.9%,H2O≤105ppm,chromaticity10 Hz,refractive index 1.4694）fully meet the requirements of the electronic grade NMP for the lithium electronic battery industry.2.A Pervaporation-Crystallization process（PCP）process was developed for simultaneously recovering ethanol and residual sodium pyruvate from the centrifugal mother liquor in the sodium pyruvate production process by using NaA zeolite membranes.Firstly,the pervaporation dehydration performance of NaA zeolite membranes for the ternary system of ethanol/water/sodium pyruvate was investigated.The water content in the permeate was consistently maintained at 100%during test,demonstrating the outstanding separation performance of the NaA zeolite membrane.In addition,it was found that NaA zeolite membrane would be fouled after long-term operation in a solution with high sodium pyruvate content（2 wt.%）and its permeation flux decreased about 30%,resulted from the adsorption and deposition of sodium pyruvate salt on the membrane surface.The fouled NaA zeolite membrane can be completely regenerated by simple deionized water cleaning.Finally,a pilot-scale test for recovery of ethanol and sodium pyruvate by Pervaporation-crystallization process（PCP）using NaA zeolite membranes was carried out in Shanghai Jinli Biopharmaceutical Co.,Ltd.The results showed that the NaA zeolite membrane based PCP process can realize the simultaneous recovery of ethanol solvent and high value-added sodium pyruvate products at low operating temperature.In summary,this master thesis explores the technical feasibility of NaA zeolite membranes in purification and reuse for waste NMP in the lithium battery industry and simultaneous recovery of the solvent and products in the centrifugal mother liquor in the pharmaceutical or fine Chemical industry,and and expands the industrial applications of NaA zeolite membrane. |
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