Influence of Sodium Hypochlorite Treatment on Pore Size Distribution of Polysulfone/Polyvinylpyrrolidone Membranes

Abstract

This work was focused on the study of hypochlorite treatment on the pore size distribution of membranes. To this end, ultrafiltration membranes from a polysulfone/polyvinylpyrrolidone blend with a sponge-like structure were fabricated and exposed to hypochlorite solutions with different active chlorine concentrations for 4 h at ambient temperature. Liquid–liquid displacement and scanning electron microscopy were employed to study the limiting and surface pores, respectively. After treatment with 50 ppm hypochlorite solution at pH = 7.2, a five-fold increase in water permeance up to 1400 L/(m2·h·bar) was observed, accompanied by a 40% increase in the limiting pore sizes and almost a three-fold increase in the porosity. After 5000 ppm treatment at pH = 11.5, a 40% rise in the maximum limiting pore size and almost a two-fold increase in the porosity and permeance was observed, whereas the mean pore size was constant. Apparently, changes in the membrane structure at pH = 11.5 were connected with polyvinylpyrrolidone (PVP) degradation and wash-out, whereas at lower pH and despite lower active chlorine concentration, this process was coupled with polysulfone (PSf) destruction and removal.

Open-Celled Foams of Polyethersulfone/Poly(N-vinylpyrrolidone) Blends for Ultrafiltration Applications

“…PESU membranes are also preferred for ultrafiltration applications due to their capability to deliver reliable retention values and high porosity [ 33 ]. Some researchers used poly( N -vinylpyrrolidone) (PVP) as a water-soluble ‘pore-opener’ along with poly(arylsulfones) to produce ultrafiltration membranes from solutions in organic solvent [ 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 ]. Therefore, due to the proven application of PESU and PVP in ultrafiltration membranes, we use blends of PESU and PVP in this work.…”

“…As PVP is soluble in a variety of commonly available compounds such as water and aqueous solutions of sodium hypochlorite (NaOCl), a permeable selective layer could be created through the dissolution of PVP. NaOCl is selected due to its proven suitability for post-processing of PESU/PVP membranes [ 33 , 35 , 39 ]. The outer surface in batch foams commonly contains cracks that occur due to the expansion of the sample during foaming.…”

Enhancing biofouling resistance in microfiltration membranes through capsaicin-derivative functionalization

“…7 However, the pretreatments usually could not completely remove the microorganisms, while the residue microbes could multiply and foul the membrane; 8 in addition, the residual chloride could damage the membrane and affect the quality of the effluent. 9 In general, fabricating membranes with built-in antibiofouling properties is a more efficient approach. The most widely adopted strategy to prevent biofouling is to reduce the bacterial adhesion.…”

Fabrication of Polyacrylonitrile UF Membranes by VIPS Method with Acetone as Co-Solvent

“…Membranes with various pore sizes have been developed, depending on the requirements of different applications. There are a few polymeric materials for ultrafiltration and microfiltration membrane preparation, namely polysulfone (PSF) [ 4 , 5 ], polyethersulfone (PES) [ 6 ], cellulose acetate (CA) [ 7 ], poly(vinylidene fluoride) (PVDF) [ 8 ], polypropylene (PP) [ 9 , 10 ], polyacrylonitrile (PAN) [ 11 , 12 , 13 ], and others [ 14 , 15 ].…”