In ordertoincreasetheunderstandingoftheunderlyingprocessesinorganicsolventnanofiltration (OSN), astudyhasbeenundertakenaimedatclarifyingthesolvent flux behaviourofceramic nanofiltration andultrafiltration membranes.Ceramicmembraneswerechosenfortheirnon-swelling character.Purewaterandavariationof11differentorganicsolventsweremeasuredonaseriesof different ceramicmembraneswithpore-sizediametersrangingfrom0.9nmupto100nm.Toavoidany historical effects,each flux measurementwascarriedoutonanewmembrane. The flux resultswereanalysedinaphenomenologicalway,andacommonverysimplelinear relationship wasobservedbetweentheproductof flux andviscosityofthesolvent,andthetotalHansen solubility parameterofthesolvent.Thelinearrelationshipwasfoundforallmembranes,independentof the membraneporesizeandthemembranematerial.Theslopeofthelinearrelationshipwasfoundto depend exponentiallyonthepore-sizediameterandonthepolarityofthemembranesurface.Thisresult emphasizes theimportanceofviscosityinthesolventtransport,butalsoofthepolaritydifference between membranesurfaceandsolvent.Theverysimple flux modeldeduced,allowsastraightforward prediction ofthe flux ofanysolventorsolventmixture,oncethewater flux ofthemembraneisknown. At thehighpore-sizeend,thephenomenologicalmodelnaturallytransformsintotheviscous-flow or pore-flow behaviourasrequired.Atentativephysicalexplanationofthemodeltakesintoaccountthe presence andextensionofawaterlayeradsorbedtothetotalporesurfaceofthesemembranes. This workalsoshowsthatthewater flux ofahydrophilicmembranegivesagoodindicationofits molecular weightcut-off(MWCO),andthereforeofitsseparationperformanceinwater.
Unravelling the solvent flux behaviour of ceramic nanofiltration and ultrafiltration membranes
2013
Abstract
In ordertoincreasetheunderstandingoftheunderlyingprocessesinorganicsolventnanofiltration (OSN), astudyhasbeenundertakenaimedatclarifyingthesolvent flux behaviourofceramic nanofiltration andultrafiltration membranes.Ceramicmembraneswerechosenfortheirnon-swelling character.Purewaterandavariationof11differentorganicsolventsweremeasuredonaseriesof different ceramicmembraneswithpore-sizediametersrangingfrom0.9nmupto100nm.Toavoidany historical effects,each flux measurementwascarriedoutonanewmembrane. The flux resultswereanalysedinaphenomenologicalway,andacommonverysimplelinear relationship wasobservedbetweentheproductof flux andviscosityofthesolvent,andthetotalHansen solubility parameterofthesolvent.Thelinearrelationshipwasfoundforallmembranes,independentof the membraneporesizeandthemembranematerial.Theslopeofthelinearrelationshipwasfoundto depend exponentiallyonthepore-sizediameterandonthepolarityofthemembranesurface.Thisresult emphasizes theimportanceofviscosityinthesolventtransport,butalsoofthepolaritydifference between membranesurfaceandsolvent.Theverysimple flux modeldeduced,allowsastraightforward prediction ofthe flux ofanysolventorsolventmixture,oncethewater flux ofthemembraneisknown. At thehighpore-sizeend,thephenomenologicalmodelnaturallytransformsintotheviscous-flow or pore-flow behaviourasrequired.Atentativephysicalexplanationofthemodeltakesintoaccountthe presence andextensionofawaterlayeradsorbedtothetotalporesurfaceofthesemembranes. This workalsoshowsthatthewater flux ofahydrophilicmembranegivesagoodindicationofits molecular weightcut-off(MWCO),andthereforeofitsseparationperformanceinwater.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
