The Effect of Buildup Interactions in Chlorophene Removal from Water Using Polyelectrolyte Multilayer Membranes

Hydrophobic emerging contaminants in aquatic environments pose significant risks to ecosystems and human health. This study investigates the surface interactions governing the rejection of the neutral hydrophobic compound chlorophene (CHP) using poly(ethyleneimine)/poly(styrene sulfonate) (PEI/PSS) layer-by-layer (LbL) coated microfiltration membranes. Membrane–solute interactions were evaluated as a function of solution pH, ionic strength, and feed concentration. CHP rejection was primarily governed by hydrophobic interactions at the membrane surface, with membranes fabricated under alkaline conditions showing superior performance. Optimal rejection and operational stability were achieved for membranes assembled at pH 10 with 0.2 M NaCl, particularly at higher feed concentrations (40 ppm). Micellar-enhanced ultrafiltration modified CHP–membrane interactions through micelle formation above the critical micelle concentration, enabling size-based exclusion. In humic acid (HA) containing systems, enhanced CHP rejection was sustained, with fouling dominated by cake-layer formation. While a 7.5-bilayer membrane achieved complete CHP rejection for up to five filtration cycles and >90% thereafter. A 5-bilayer membrane provided stable and reproducible removal of both CHP in presence of HA and was selected as the optimized configuration. These findings emphasise the critical role of membrane–solute interactions and demonstrate the tunability of LbL-engineered membranes for water treatment applications.​