Hello everyone!
I am making polymeric Organic Solvent Nanofiltration(OSN) membranes by phase inversion. I used DMF/1,4-dioxane as solvent/cosolvent, and mixed it with polyimide P84 to make the dope solution. I successfully made stable membranes last year, and the flux and rejection of the membranes are comparable with results from other publishments.
But recently, the flux and the rejection of the membranes changed a lot (higher by several times than before) every time I wanted to repeat the experiments. I have checked every possible reason for this kind of fluctuation during the casting, cross-linking, and conditioning process. But I still couldn't solve it. I am wondering what are the main factors that control the quality of polymer membranes made by phase inversion during the experiment. Or was it due to the poor quality of the chemicals that I bought?
I would be very happy if you could share your experience and kindly give some suggestions.
Thank you very much!
Regards,
Hi Farzin Saffarimiandoab
Thank you very much for your reply!
I cast the membranes on the glass and the thickness hasn't been changed from the very first beginning. So I think they are not the reason that causes this situation probably.
I am thinking about other possible reasons recently
1. I used bath sonication to mix the cast solutions, some vapors may come into the bottle if I don't do it carefully;
2. I didn't dry the polymer (polyimide P84) before the experiments, so some water may exist in the polymer;
3. Maybe I didn't dry the bottles completely before making the dope solution.
I am wondering may one of the above-mentioned reasons has caused bad results. How do you think?
But yeah to compare the SEM cross-section images is a good idea!
Best regards,
Yuewen
I have a question about dioxane 1,4 becuase i don't know the effect of this chemical sovent on polymers, my experiment is about using two polymers : sodium alginate and silk fibroin, i read an article that use deoxane 1.4 and didn't say why, but they did not use any cross linkers like calsium, if any one can help me , i woud appreciate .
Dear Yuewen Jia ,
According to my experience:
1. material grade
2. producer company
3. material form
are so important.
To elaborate, if you use P84 from Chinese and Belgium companies, the results would be different. If you use the powder, granular, or flake forms of polymer, the results would be different.
According to the abovementioned description, be careful about all of the ingredients you are using.
Good luck
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