Treatment of model textile effluents with PAA/CHI and PAA/PEI composite membranes

Composite membranes were developed from polyamide microfiltration membranes by a combination of two cationic (poly (ethyleneimine)-PEI, chitosan-CHI) and an anionic (poly (acrylic acid)-PAA) polyelectrolyte through layer-by-layer (LbL) assembly. The removal efficiency of these membranes was investigated using two model textile effluents, methylene blue (MB) and Coomassie brilliant blue (CBB). The uptake of dye was found to be very much dependent on the type of bilayers. The amount of MB uptake by the multilayer was high with PAA/CHI bilayer and was influenced by the conformation of dye within the multilayer. The initial concentration of CBB decreased from 14.75 to 1.5 mg L− 1 and MB from 14.4 to 2.6 mg L− 1 with 20 bilayer membrane. Alkaline effluent pH resulted in 79.9%, MB and 87.1%, CBB removal. Desorption studies of MB and CBB using 19.5–20 bilayer PAA/PEI and PAA/CHI multilayers showed a pH dependent release. A complete desorption of MB was observed at low pH (pH 3). In the case of CBB, the enhanced desorption takes place at pH 7. COD values showed a significant reduction after treatment with PAA/CHI multilayers.

► Polyamide based composite membranes by self assembly of polyelectrolytes.
► Demonstration of the removal efficiency dependence on the type of bilayers.
► For MB, the amount of dye uptake by the multilayer is high with PAA/CHI bilayer.
► Desorption studies showed a pH dependent release.
► COD values showed a significant reduction after treatment with PAA/CHI multilayers.