اصلاح شيميايي سطح غشا تجاري مركب فيلم نازك پلي آميد اسمز معكوس با روشي جديد به وسيله پيوند زني كيتوزان

چكيده انگليسي :

83A Novel Method of Chemical Surface Modification on Commercial Thin Film Composite Polyamide Reverse Osmosis Membrane via Grafting Chitosan Nabeel Atbaie Nabeel atbaie@gmail com Department of chemical engineering Isfahan University of Technology Isfahan 8415683111 Iran Degree M Sc Language Farsi Mahmoud Masoomi mmasoomi@cc iut ac ir Ahmad Moheb ahmad@cc iut ac irAbstractPolyamide reverses osmosis membranes are widely used for desalination of brackish and sea water Membrane fouling is the most important problem facing in reverse osmosis process Surface grafting of thepolyamide membranes has been considered by many researchers to improve the anti fouling properties of themembranes According to the published results it seems that surface modification of the membranes can beconsidered as a potential method of partial or in some cases total elimination of fouling To this aim chitosanwas grafted for the first time on the surface of thin film composite TFC polyamide reverse osmosismembranes Grafting was completed by the reaction between the carboxylic acid groups existing on thesurface of the membrane and the amine groups of chitosan 1 Ethy 3 3 dimethyl amidopropyl carbodii mide EDC was used to induce the carboxylic groups Effects of modification time on the properties of themembrane were investigated by carrying out the grafting process for different times of 1 3 5 6 12 24 36 and 48 hour Maximum grafting density of 0 0525 was achieved for 24 hours grafting Themembranes were characterized by ATR FTIR AFM SEM and contact angel analysis methods The resultsobtained from ATR FTIR analysis showed reduction in the intensity of the peak seen at the wave number of1730 cm 1 attributed to C O stretch of ester group which confirmed grafting of chitosan on the membranesurface AFM analysis revealed that the average surface roughness decreased from 173 9 for the unmodifiedmembrane to 114 3 for the samples modified for 24 hour Decreasing the contact angle to 32 for themembrane modified for 24 hour in comparison with 52 for the virgin membrane proved significant min hydrophilicity enhancement by surface modification SEM analysis showed no significant change inmembrane surface morphology after modification Membrane performance in water flux and NaCl rejectionwas improved by increasing grafting time The maximum flux of 128 was obtained for thesamples modified for 12 hours whereas surface modification for 24 hour caused the maximum salt rejectionof 99 30 The fouling resistance properties of the modified membranes against NaCl and two differentcharged surfactants namely sodium dodecyl sulfate SDS and N Cetyl N N N trimethyl ammoniumbromide were compared with that of unmodified membranes In the case of NaCl it was found that fluxdecline due to the membrane fouling and the flux recovery for the samples modified for 12 hours weresimilar to the original samples For the fouling tests carried out with N Cetyl N N N trimethyl ammoniumbromide it was clearly seen that the samples modified for 24 hours showed better antifouling properties thanthose of the unmodified membrane On the other hand the unmodified membrane showed relatively betterperformance in comparison with the modified samples when they were tested by SDS solutions Finally theantibacterial activity was evaluated with E coli It was found membranes grafted with Chitosan for 24 hourwould reduce the bacterial ratio to less than 97 5 compared to unmodified membrane Key Words Polyamide Reverse osmosis Grafting Chitosan Desalination Fouling Surfactant Antibacterial

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اصلاح شيميايي سطح غشا تجاري مركب فيلم نازك پلي آميد اسمز معكوس با روشي جديد به وسيله پيوند زني كيتوزان