Preparation and characterization of ultrafiltration membranes from PPSU-PES polymer blend for dye removal

Abstract

Membrane engineering is currently classified as an eco-friendly cleaning technology in various fields, especially for wastewater treatment, and its use is increasing due to the growing interest in water environment protection and preservation. In this study, a new approach to improving membrane performance is proposed by using polyethersulfone (PES) as a polymer blend with polyphenylsulfone (PPSU). PPSU-PES ultrafiltration membranes were prepared using the classical phase inversion method to remove dyes from simulated wastewater of the leather tanning industry. Four concentrations of PES were studied (i.e. 0, 4, 5, and 6 wt.%), while keeping the concentration of PPSU constant at 20%. A scanning electron microscope (SEM) and atomic force microscopy (AFM) were used to characterize the surface structure of the cross-section, top, and bottom membranes. It was found that the structural morphology of the membrane varied with the PES concentration. The addition of PES helped significantly decrease the contact angle and increase the porosity of the PPSU/PES/N-methyl-2-pyrrolidinone (NMP) blend membranes by approximately 15.2% and 280%, respectively, and to decrease the thickness of the membrane compared with neat PPSU. The effects of black dye (i.e. acid black 210, MW = 938.017 g mol−1) concentration (i.e. 35, 45, and 65 ppm), feed temperature, and pH on the permeate flux and dye removal were also investigated in this study. It was found that there is a minor effect of the feed temperature and no effect of pH on the permeation flux. Also, it was discovered that the performance of the membranes improved from 5.77 to 27.7 and 3.46 to 19.62 for distilled water and feed solution of 35 ppm, respectively over those prepared from the neat PPSU membrane, while the dye removal was higher than 99.65% for all of the membranes studied.