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Studying the Performance of Membrane Separation System in the Lipase Enzyme Production Process

Koohi, Hamid | 2018

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50583 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Molaei Dehkordi, Asghar; Roosta Azad, Reza; Musavi, Abbas
  7. Abstract:
  8. In this study, the polysulfon ultrafilteration membranes were prepared and applied to concentrate the Lipase enzymes produced in the laboratory and the commercial enzymes of Novozymes Company. Using Design Expert software. The effect of membrane preparation conditions including polysulfone and polyvinylpyrrolidone concentration and the solvent type were investigated. The prepared membranes were characterized by measuring of distilled water flux, enzyme liquor flux, and enzyme activity in permeate and the Retentate flows. The results showed that increasing of polysulfone concentration reduced the flux of distilled water and enzyme activity in permeate and enhanced the enzyme activity in the retentate. The increase in polyvinylpyrrolidone concentration increases the flux of distilled water and enzyme activity in the permeate, however, does not have significantly affect the activity of the enzyme in the retentate. In addition, the type of solvent does not have a significant effect on the results. Comparison of distilled water flux and enzyme liquor flux shows that the presence of the enzyme reduces the permeation flux in all prepared membranes (distilled water flux is in the range of 120-615 L/m2.h and the enzyme liquor flux is 65 L/m2.h). The membrane preparation condition were optimized for the enzyme concentrate. The optimized membrane was prepared to concentrate the enzymatic liquor. Optimized membrane compositions were consisted of 40.71% Dimethylformamide solvent, 38.88% N-Methylpyrrolidone solvent, 20% polysulfone, and 0.48% polyvinylpyrrolidone. SEM images were taken from optimum membrane to compare them with other prepared membranes. The molecular weight cut off measured in optimal membrane confirmed that the molecular weight cut off in higher than 20 kDa. According to enzyme liquor permeation test in optimal membrane, 3% of total enzyme diffused to permeate flow. A 35% enhancement in enzyme activity in retentate flow was observed by 30% removing of water from enzyme liquor. The permeation flux of the enzymatic liquor of the laboratory's production was studied for 6 hr. In the first 20 min, it dropped by about 45%. Washing the membrane with distilled water for 20 min restores the membrane flux completely. For stability analysis, the ratio of activity of concentrated enzyme to the initial enzyme activity was measured. The obtained results showed that the enzyme activity did not decrease significantly over time for one week, however, decreased from 1.28 to 0.6 after one month
  9. Keywords:
  10. Lipase Enzyme ; Stability ; Activity ; Membrane Process ; Membrane Separation ; Anzyme Production ; Enzyme Flux

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