Assessing the effect of surface modification of polyamide RO membrane by I-DOPA on the short range physiochemical interactions with biopolymer fouling on the membrane

“Theoretical predictions of interaction energies for membrane–biopolymer foulant pairs were used tocompare the fouling tendencies of a virgin commercial polyamide reverse osmosis (RO) membrane witha amino acid 3-(3,4-dihydroxyphenyl)-l-alanine (l-DOPA) coated RO membrane. Lifshitz–van der Waals(LW) and Lewis acid–base (AB) surface tension components of the membranes were determined basedon contact angle results using the van Oss approach. From these values, the LW and AB components of thefree energy of adhesion between membrane and foulants were calculated. Electrostatic (EL) double layerinteraction energies between the membrane and foulants were also estimated using the measured surfacecharge data of the membranes and fouling agents. Bovine serum albumin (BSA) and alginic acid sodiumsalt (alginate) were used as model biopolymers causing membrane fouling. Based on the calculatedadhesion free energies, acid–base interactions were found to have the strongest impact on the adhesionof both BSA and alginate to the either membranes surfaces. It was found that l-DOPA modification hassignificantly lowered acid–base interaction affinity toward the adhesion of both foulants studied. On thebasis of calculated free energies of adhesion, lower fouling tendency of the l-DOPA modified membranewas expected. The accelerated fouling tests indicated a lower flux decline rate for the modified membraneand confirmed the results obtained from theory.”
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(Citaat: Azari, S., Zou, L. Cornelissen, E.R. – Assessing the effect of surface modification of polyamide RO membrane by I-DOPA on the short range physiochemical interactions with biopolymer fouling on the membrane – Colloids and Surfaces B Biointerfaces 120(2014)222-8)