Membrane filter
A membrane filter is a matrix with channels which act as a screen and retain particles larger than the filter on the surface of themembrane.
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Can I filter aqueous solutions through a polytetrafluoroethylene (PTFE) hydrophobic membrane?
Yesyoucan,butthemembranerequirespre-wettingwithalcohol(likeIsopropanolorMethanol)toestablishflowwithreasonable pressuredifferentials.Weoftenusea60/40solution(60Isopropanol/40water)toprewetthemembrane....
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What is a membrane filter?
Amembranefilterisamatrixwithchannelswhichactasascreenandretainparticleslargerthanthefilteronthesurfaceofthe membrane.Membranefiltersallowtheretentionofsub-micronparticlesandorganisms. NotethatporeshavenotbeenobservedinROorNFmembranesusingami...
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What is the maximum temperature for the different filter membranes?
Themaximumoperatingtemperaturesforfiltermembranesarelistedbelow. Ceramic-350C PolycarbonateTrackEtch-140C Polyester-140C Nitrocellulose(MCE)-130C Nylon-180C Polyethersulfone(PES)-180C Polypropylene-82C CelluloseAcetate-135C PTFE(Laminated)-1...
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What is hydrophilic vs hydrophobic membrane?
Hydrophilicfilterspossesanaffinityforwaterandcanbewettedwithalmostanyliquid.awidevarietyofhydrophilicmembranes, including: SilverMetal Polyethersulfone(PES) GlassFiber PolycarbonateTrackEtch(PCTE) Polyester(PETE) MixedCelluloseEsters(MCE) Ny...
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What organisms are used to determine pore size?
PoreSize ChallengeOrganism 0.1m Acholeplasmalaidlawii 0.2m Brevundimonasdiminuta 0.45m Serratiamarcescens 0.8m Lactobacillusspecies 1m Candidaalbicans...
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What variables affect the performance of a filter?
Porosity:Theflowrateofamembraneisdirectlyproportionaltotheporosityofamembrane,eg.themorepores,thehighertheflowrate. FilterArea:Thelargerthefilterarea,thefastertheflowrateatagivenpressuredifferentialandthelargertheexpectedfilterthroughput vol...
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How is pore size determined?
Theporesizeofafilter,normallystatedinmicrometers(Jm),isdeterminedbythediameterofaparticlethatisretainedbythefilter. Thisisdeterminedusingachallengeorganismand/orbubblepointtesting....
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How are pore sizes rated?
Aporesizeratingisdeterminedbythediameteroftheparticlethatitcanbeexpectedtoretainwithadefined,highdegreeofefficiency. Theratingisstatedinnominalorabsoluteterms....
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What is the difference between nominal and absolute pore size ratings?
Nominalporesizeratingdescribestheabilityofthefiltertoretainthemajorityoftheparticlesattheratedporesizeandlarger(60-90%). Glassfiberfiltersandscreenfiltersareagoodexampleofnominallyratedfiltration. Absolutesizeratingdescribestheporesizeatwhic...
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What is a KD (kiloDalton)?
KD,orkDistheabbreviationforkiloDaltonandisequalto1,000MolecularWeightCut-Of(MWCO).Asolutionhavingamolecularweight of1,000,000wouldbeequivalentto1,000KD.ThetablelistedbelowgivesageneralrelationshipbetweenkiloDaltontoMicrons (micrometers), Nan...