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Improve Performance of Polyamide Reverse Osmosis Membranes by Crosslinking Treatments

Safaeifakhr, Alireza | 2021

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 54384 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Mousavi, Abbas
  7. Abstract:
  8. Reverse osmosis membranes are one of the most common methods of desalination of water in the world today. In the meantime, aromatic polyamide thin-film composite reverse osmosis membranes have one of the best performances and can be widely used in industry. This project aims to make surface modifications on the made raw membranes and increase the degree of crosslinking to improve the functional properties of the membrane, such as the percentage of salt rejection and the flux of permeate, and the reduction of fouling. For this purpose, polyvinyl alcohol and l-arginine along with maleic anhydride as the crosslinking agent and hexamethylene diisocyanate were used for surface modification of the raw membranes. In this study, in addition to testing the functional properties of the modified membranes, contact angle, Fourier-transform infrared spectroscopy, and scanning electron microscopy tests were performed to investigate and analyze how the structure of the polyamide layer changed. The results of the modification of the raw membrane with l-arginine and maleic anhydride show an increase of about 2% in salt rejection and a 48% increase in the flux of permeate so that the rate of salt rejection arrives at 97.8% and the flux of permeate to 36.2 liters per square meter per hour. The results of the modification of the raw membrane with polyvinyl alcohol and maleic anhydride also show an increase in both the percentage of salt rejection and the flux of permeate so that the percentage of salt rejection arrives at 98.4% and the flux of permeate is higher than 28 liters per square meter per hour. It turns out that both have better functional properties than raw and unmodified membranes. Examination of the contact angle test results of the modified membranes shows an increase in the hydrophilicity of the membrane surface, which can reduce the fouling in the membranes. Also, the analysis of Fourier transform infrared spectroscopy and scanning electron microscopy tests confirmed the success of the modifications
  9. Keywords:
  10. Reverse Osmosis Membrane ; Crosslinking ; Surface Modification ; Polyamides

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