Sorption of triclosan on electrospun fibrous membranes: Effects of pH and dissolved organic matter

Three hydrophobic and polyporous electrospun fibrous membranes (EFMs) were prepared by electrospinning methoxy polyethylene glycol-poly(lactide-co-glycolide) (MPEG-PLGA), poly(d,l-lactide-co-glycolide) (PLGA) and poly(d,l-lactide) (PDLLA). The effects of pH and dissolved organic matter (DOM) on triclosan (TCS) sorption by EFMs in aqueous solution were investigated. The results indicated that hydrogen bonding, hydrophobic and π–π bonding interactions led to fast adsorption, which governed the adsorption rates of TCS onto EFMs. The maximum sorption capacities of MPEG-PLGA, PLGA and PDLLA reached 130, 93 and 99 mg g−1, respectively, which were in positive correlation with their pore volumes and influenced by pore filling processes. The solution pH could significantly influence the TCS sorption by EFMs. In acid condition, protonated TCS facilitated their sorption onto EFMs. No obvious sorption was observed in alkaline condition due to repulsive forces between negatively charged EFMs and deprotonated TCS (pKa = 7.9). The presence of DOM inhibited TCS sorption onto EFMs due to competitive adsorption. The results could be due to the occupation of the adsorption sites and the blockage of the pore entrance by DOM.