Synthesis and characterization of polymer-clay nanocomposite membranes for micellar enhanced ultrafiltration of synthetic dyes from water

Background

In micellar-enhanced ultrafiltration (MEUF) the aggregates of small dye molecules with surfactant are retained on the membrane surface.

Methods

Sodium montmorillonite (Na-MMT) nano clay particles were incorporated into the growing polymer matrix during the emulsion polymerization of acrylonitrile (AN) with acrylic acid/sodium acrylate (AA/NaAA) at varied comonomer ratios to prepare different nanocomposites. UF membranes were prepared from these composites by phase inversion at varied casting conditions. These casting variables were optimized with a Box-Behnken Design (BBD) of the response surface methodology (RSM) model for a MEUF of 50 mg/L of a cationic dye methylene blue (MB) in the presence of 10 mM of an anionic surfactant sodium dodecyl sulfate (SDS). The polymer and the UF membranes prepared with the optimized composition were also characterized and used for permeation flux and rejection% at varied process conditions. The parameters of resistance series model and micellar efficiency were estimated.

Results

The membrane prepared with the AN:AA-NaAA molar ratio/clay weight%/evaporation time/gel temperature of 5:1/ 1 %/109 s/30 °C and SDS concentration of 10 mM showed an optimized flux/rejection of 555.1 Lm^-2h^-1 /95 % in a cross flow mode at a 3 bar operating pressure . The unfilled membrane with a similar composition showed a flux/rejection of 566.5 Lm^-2h^-1 /93 %.