Antimicrobial modifications of poly(ether sulfone) membrane

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2016
Doğru, Esra Nur
Fouling on a membrane is one of the major problems of liquid filtration systems. To solve this problem, physical treatments and modifications are applied on membranes. Biofouling is the most severe form of fouling, which is due to biofilms of microorganisms in a matrix of extracellular polymers they secrete. Biofilm formation has been attacked by periodic cleaning of membrane, disinfection of feed, and surface modification. In this study, we proposed an antimicrobial surface modification to prevent biofilm formation by killing the microorganisms and inhibiting their growth. Poly(ether sulfone) (PES) based polymeric membrane was improved by chemical modification via N-halamines. N-halamines are amine structures covalently bonded to halogens. In our study chlorine was used as halogen. Oxidative chlorine (Cl+) and proton (H+) are in an equilibrium in an N-halamine. N-halamine compounds release chlorine to a medium, and the chlorine damages the cell structure of microorganisms and kills them. In the course of this study, the modified polymers were characterized by ATR FTIR and NMR spectrometers, which confirmed the aimed structures were obtained. The membrane performances were examined with pure water permeance measurement. The membrane morphologies were imaged by SEM. The antimicrobial activities of the membranes were examined on Gram-negative (Escherichia coli BL21) and Gram-positive (Bacillus subtilis) model organisms. It was observed that the chlorinated membranes showed biocidal activity, whereas chlorine-free membranes did not affect the growth of the bacteria on agar. Then, the N-halamine stability on the membranes were studied in pure water and bacterial medium (E.coli BL21) to predict the biocidally active span of the membranes. It was observed that increasing chlorine amount on the membrane in low bacterial concentration increases the antimicrobial effective time.

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Citation Formats
E. N. Doğru, “Antimicrobial modifications of poly(ether sulfone) membrane,” M.S. - Master of Science, Middle East Technical University, 2016.