Multi-scale analysis of hypochlorite induced PES/PVP ultrafiltration membranes degradation

Abstract

International audienceIn drinking water production plants, the use of oxidants such as sodium hypochlorite during in-place cleanings may impair the membrane integrity and radically impact the ultrafiltration process efficiency, leading to potential contamination of the permeate water with pathogens. This study investigates the effects of hypochlorite exposure on the properties of a commercially available UF hollow fiber. Mechanical performances and water permeability appeared to be greatly affected by the contact with hypochlorite. Monitoring them olecular changes by X-rayphoto electron spectroscopy (XPS), attenuated total reflectance infraredspectroscopy (ATR-IR), size exclusion chromatography (SEC) and VITA-mode atomic forcemicroscopy (VITA-AFM) revealed high stability of the main polymer constituting the membrane (i.e. polyethersulfone (PES)) and very high reactivity of the additive (i.e. poly (N-vinyl pyrrolidone (PVP)) towards immersion in aqueous sodium hypochlorite solution with maximal reaction rate for neutral to slightly basic pH. Correlation of those results unexpectedly leads to the conclusion that the over all membrane properties changes are governed by the additive fate

Influence of PVP content on degradation of PES/PVP membranes: Insights from characterization of membranes with controlled composition

“…Membrane filtration processes are now widely used in environmental applications (water and wastewater treatment), and in a number of industries including agri-food and 3 biotechnology industries. The relatively low manufacturing cost of polymeric membranes together with the easy processing of large-area membranes have led to a dominant position of polymeric membranes worldwide.…”

“…The relatively low manufacturing cost of polymeric membranes together with the easy processing of large-area membranes have led to a dominant position of polymeric membranes worldwide. Among the many polymers used as membrane materials, polyethersulfone (PES, see figure 1) is widely used to synthesize microfiltration and ultrafiltration membranes as PES has both excellent chemical and thermal resistances over a wide range of pH (from 1 to 13) [1][2][3]. However, PES is relatively hydrophobic and therefore additives such as polyvinylpyrrolidone (PVP, see figure 1) are usually blended with PES (without covalent bounds between the two polymers), in order to increase the membrane hydrophilicity.…”

“…Sodium hypochlorite is one of the most widely-used disinfecting/cleaning agents owing to its high efficiency and low cost [8][9][10]. However, it is well known that sodium hypochlorite has a strong impact on membranes properties such as structure [2,11,12], surface charge [2,13,14] and chemical composition [3,10,13,15], which directly impacts their filtration performance and their mechanical strength as well [3,15,16].…”

Multi-stage Mass Spectrometry of Poly(vinyl pyrrolidone) and Its Vinyl Succinimide Copolymer Formed upon Exposure to Sodium Hypochlorite

“…S5). Beyond the secondary fragment ions (two water losses for [II 7 +Na] + , Fig. S6) or the absence of fragment ions (for c 4 ) which highlight the di ering nature of the terminations (two hydroxyisopropyl groups or no end-groups, respectively), the main dissociation pathway still consists in the release of the pyrrolidone pendant group (85.1 Da) regardless of the end-groups.…”

“…4) Such chemical cleaning is not inconsequential and turns out to be deleterious for the membrane, ultimately leading to its degradation. Numerous studies have dealt with the ageing of PVP exposed to sodium hypochlorite [5][6][7][8] under various conditions (e.g. pH, concentration, exposure time…) and proposed several degradation routes and degradation products based on physico-chemical characterization such as infrared spectroscopy or electrochemistry.…”