pH ResponsiveNanofiltration Membranes for Sugar Separations.

Nanofiltrationmembranes were surface modified by grafting poly(acrylic acid) (PAA)nanochains using a UV initiated free radical polymerization method.These pH sensitive membranes were then used to separate monosaccharides,disaccharides, and their mixtures from filtration feed streams. Itwas found that pH dramatically affects the flux, rejection, and selectivityusing these modified pH sensitive nanofiltration membranes. Membraneperformance could be enhanced not only by the conformational changesof the grafted surface layer due to protonation and deprotonationof the acid groups on the polymer chains but also from the differentinteractions between the sugar molecules and the neutral PAA chainor its negative conjugate. Classical molecular dynamics (MD) simulationswere conducted to investigate the specific interactions between glucose/sucroseand the neutral/negatively charged PAA chains. The simulation resultsshow that both sugar size and PAA charge affect significantly thesugar-polymer interactions. [ABSTRACT FROM AUTHOR]