Polyetherimide nanofiltration membranes modified by interfacial polymerization for treatment of textile dyes wastewater

Abstract

Azo dyes are the major type of textile dye in the world, owing to their stability to light, microbial degradation, and physical degradation due to washing. However, these properties also lead to problematic removal or degradation of azo dyes that pollute the water body. In this research, nanofiltration (NF) thin film composite (TFC) membranes based on polyetherimide (PEI) polymer are utilized to remove an azo-based dye from a simulated textile wastewater, namely Reactive Black 5 (RB5). PEI is firstly dissolved by using N-methyl-2 pyrollidone (NMP) as solvent, combined with acetone as a non-solvent, and converted to be membranes via phase inversion method. The created membrane will be further modified by interfacial polymerization (IP) method using trimesoyl chloride (TMC) and m-phenylene diamine (MPD) as precursors of acyl chloride and amine, immersed in two immiscible liquids of hexane and water, respectively. This method fabricates a new selective layer composed of tightly-packed nylon-like polyamide layer that might improve the separation performance. Membranes from polymeric dope solution of PEI/acetone/NMP 15/65/20 (w/w) were employed due to acceptable flux and rejection, compared to other formulations. They were then modified by using IP method (0.05% TMC in hexane and 1.5% MPD in water) to create PEI-TFC membranes. The PEI-TFC membranes exhibited fluxes around 0.01 L m-2 h-1 psi-1, with rejection of RB5 dyes up to 90%, which suggested the successful IP method on the PEI membranes. SEM and FTIR were carried out for comprehending the reasons behind the improved separation performance, and they revealed that the TFC nylon-like selective layer was successfully developed, from both physical and chemical perspectives, respectively. The fabrication of NF TFC membranes might open some new roads for environmental application of membranes in Indonesia.