Ageing of polyvinylidene fluoride hollow fiber membranes in sodium hypochlorite solutions
Article dans une revue avec comité de lecture
Author
Date
2016Journal
Journal of Membrane ScienceAbstract
In order to study the effect of cleaning operations on polyvinylidene fluoride (PVDF) hollow fiber membrane stability, ageing of two PVDF based membranes (one is additive free, the other contains hydrophilic additives) in contact with sodium hypochlorite solutions with various pH values has been studied. The aim of this experimental study was to identify the degradation mechanisms and to gain a better understanding of the effect of the (macro)molecular structure changes on the mechanical and functional properties of the membranes. In both membranes, double bond formation, chain scission and crosslinking are observed and all these processes (except crosslinking) are faster in acidified solutions than in natural NaOCl solutions (pH 11.5). It can be deduced that if ionic processes such as dehydrofluorination occur, radical processes resulting from the presence of hypochlorous acid and perhaps its coexistence with the ClO− ion, predominate in acidified solutions. The presence of non-fluorinated aliphatic or cycloaliphatic additives, which are highly reactive with bleach, accelerates chain scission at the expense of crosslinking. In the chosen conditions (135 days in 4000 ppm bleach solutions at 40 °C), PVDF chains are degraded but not enough to induce polymer embrittlement. While in the additive free membrane no significant change of the use properties has been observed, the polymeric additives of the other membrane are completely destroyed, leading to a decrease of the membrane hydrophilicity, but their destruction improves the membrane selectivity by a decrease of the average porosity.
Files in this item
Related items
Showing items related by title, author, creator and subject.
-
Article dans une revue avec comité de lectureLAFARIE, Marie Christine; GRANDIDIER, Jean Claude; OLIVIER, Loic; VERDU, Jacques; CINQUIN, Jacques; COLIN, Xavier (Elsevier, 2010)The present paper presents a review of the main activities carried out within the context of the COMEDI research program, a joint collaboration involving three research teams focusing on the thermo-oxidation behaviour of ...
-
Article dans une revue avec comité de lectureDEFAUCHY, Virginie; LE GAC, Pierre Yves; GUINAULT, Alain; VERDU, Jacques; RECHER, Gilles; DROZDZAK, Renata; RICHAUD, Emmanuel (Elsevier, 2017)The in situ thermal oxidation of thin unstabilized polydicyclopentadiene was studied by TGA to monitor mass gain, and DSC to characterize hydroperoxides concentration. Results were discussed using kinetic analysis, which ...
-
Article dans une revue avec comité de lectureThe hydrolysis of almost ideal networks based on macrodiols of average molar mass about 2 kg mol 1, with L¼18 ester groups per chain is studied. Tensile testing is used to evaluate the crosslink density through the statistical ...
-
Article dans une revue avec comité de lectureOKAMBA-DIOGO, Octavie; VERDU, Jacques; FERNAGUT, François; GUILMENT, Jean; FAYOLLE, Bruno; RICHAUD, Emmanuel (Elsevier, 2014)The present article reports a study of thermal oxidation of unstabilized polyamide 11 films at several temperatures (90–165 °C) under atmospheric pressure and under various oxygen pressures (up to 1.6 MPa) at 110 °C. The ...
-
Article dans une revue avec comité de lectureThermal oxidation in air at atmospheric pressure, in the 80-140 °C temperature range and in oxygen at 100 °C in the 0.02-3 MPa pressure range, of unvulcanized, unstabilized, unfilled polychloroprene (CR) has been characterized ...