Selective and efficient extraction of cationic dyes from industrial effluents through polymer inclusion membrane

Abstract

• Selective and efficient extraction of cationic dyes. • Initial study by liquid-liquid extraction using EDC as complexing agent. • Synthesis of highly efficient and selective EDC-PIM for extraction of cationic dyes. • A novel, economical, green, robust and easy-to-use PIM-system. • Application of EDC-PIM to real industrial effluents. Cationic dyes are widely used colorants in textile and other related industries. These dyes are highly toxic for marine life and make a major fraction of the industrial effluents. In this study, we report the synthesis of ester derivative of calix[4]arene (EDC) impregnated polymer inclusion membrane (PIM) and employed it for the transfer of cationic dyes between two aqueous phases. EDC forms inclusion complex with cationic dyes having 1:1 M ratio as revealed by the Job’s plot, the log/log plot, and the Benesi-Hildebrand methods while using methylene blue (MB) as a model cationic dye. EDC was used as carrier with cellulose triacetate (CTA) as a base polymer, and 2-nitrophenyl octyl ether (2-NPOE) as a plasticizer for the synthesis of EDC-PIM. Membranes were characterized by Fourier Transform Infrared spectroscopy (FT-IR), Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), Brunauer–Emmett–Teller (BET), and Barrett-Joyner-Halenda (BJH) analysis. The extraction performance of the synthesized PIM was optimized by varying different external parameters including pH of the donor and the acceptor phases, temperature, stirring speed, and concentration of EDC and dye while using MB as a model cationic dye. More than 90% extraction was achieved under optimized conditions which is 4.5-fold more than EDC-free-PIM. The extraction efficiency of the EDC-PIM remained similar after ten consecutive cycles that demonstrates its reusability potential in context of economical industrial applications. Finally, the synthesized EDC-PIM was used for selective extraction of other cationic dyes (basic red and nile blue) at the optimized conditions from the real industrial effluents. The extraction efficiency of the EDC-PIM was reproducible in all cases. The reusability and robustness of the EDC-PIM makes it an excellent candidate for retrieving cationic dyes from the industrial effluents.