Effect of membrane fouling on transport of organic contaminants

摘要

Commercial polyamide nanofiltration (NF),reverse osmosis (RO) and ultra-low pressure RO (ULPRO) membranes (NF-90,NF-200,TFC-HR and XLE) as well as a cellulose triacetate RO membrane (CTA) were employed to investigate the effect of fouling on transport of organic micro-pollutants.Because of the fou-lant precipitation and cake-layer formation,membrane surface characteristics changed considerably in terms of contact angle (an index of hydrophobicity),zeta-potential,functionality and surface morphology - which potentially affected transport of contaminants compared with unfouled (Virgin) membranes.The transport of ionic organic micro-pollutants was hindered as a result of improved Donnan exclusion (electrostatic repulsion).The likely cause was a more negative surface charge as quantified by zeta-potential measurements.Membrane fouling also resulted in an increased adsorption capacity and reduced mass transport through partitioning and diffusion of solutes across the membrane.