Membrane sib cais tshuab tuaj yeem muab faib ua ntau txoj hauv kev nyob ntawm txoj kev ntsuas.
(1) Kev faib tawm los ntawm Extractant
Raws li cov khoom sib txawv yuav tsum tau muab cais tawm, cov txheej txheem sib cais membrane tuaj yeem muab faib ua plaub pawg: purification, concentration, sib cais, thiab rho tawm. Membrane cais cov txheej txheem hauv kev kho dej, qhov twg permeate yog cov khoom, hu ua purification; cov uas qhov retentate yog cov khoom hu ua concentration; cov uas ob qho tib si permeate thiab retentate yog cov khoom hu ua kev sib cais; thiab cov uas siv kev sib xyaw ua ke ntawm cov txheej txheem membrane sib cais nrog ob qhov sib txawv retentate cutoffs kom tau cov khoom nruab nrab ntawm ob qhov kev txiav tawm yog hu ua extraction.
(2) Kev faib tawm los ntawm Membrane Material
Raws li cov khoom siv membrane, semipermeable membrane tuaj yeem muab faib ua cov organic thiab inorganic membranes. Organic membrane cov ntaub ntawv feem ntau suav nrog ntau yam ntaub ntawv polymer xws li polysulfone, polypropylene, polyacrylonitrile, polyvinylidene fluoride, polyethersulfone, cellulose acetate, sulfonated polysulfone, thiab aromatic polyamide;
Inorganic membrane cov ntaub ntawv tau muab faib ua hlau -raws li inorganic membranes xws li hlau thiab hlau oxides, thiab silicate-raws li inorganic membranes xws li ceramics thiab iav.
Organic daim nyias nyias yog yooj yim los npaj, muaj siab membrane ntsiab ntim ratios, yog pheej yig, thiab ua hauj lwm nyob rau hauv tsawg pressures, tab sis raug kev txom nyem los ntawm tsis zoo tshuaj stability, kub tsis kam, mechanical zog, thiab tu tsis kam; inorganic membranes, ntawm qhov tod tes, yog qhov opposite.
Ob qho tib si organic thiab inorganic membrane technologies txuas ntxiv txhim kho lawv cov kev ua tau zoo raws li lawv cov txiaj ntsig zoo, sib zog ua kom dhau ib leeg lub zog. Tam sim no, tsuas yog cov tshuaj tsw qab polyamides ntawm cov ntaub ntawv rov qab osmosis membrane tau mus txog kev tsim khoom lag luam, thaum cov ntaub ntawv ultrafiltration membrane muaj ntau yam.
(3) Kev faib tawm los ntawm kev sib cais Precision
Raws li qhov sib txawv ntawm qhov sib txawv, cov txheej txheem kev sib cais dej hauv dej tuaj yeem muab faib ua kev pom zoo, microfiltration, ultrafiltration, nanofiltration, electrodialysis, thim rov qab osmosis, resin txaj electrodialysis (tseem hu ua EDI lossis electrodeionization), thiab membrane distillation. Microfiltration, ultrafiltration, nanofiltration, thiab thim rov qab osmosis yog tag nrho cov tsav los ntawm lub siab sib txawv ntawm daim nyias nyias, thaum electrodialysis thiab resin txaj electrodialysis yog tsav los ntawm lub peev xwm sib txawv. Microfiltration membranes muaj qhov hnyav molecular txiav ntawm 0.1-1.0 μm thiab kev khiav hauj lwm siab ntawm 0.1-0.2 MPa; ultrafiltration membranes muaj qhov hnyav molecular txiav ntawm 5000-200000 Da thiab kev ua haujlwm siab ntawm 0.1-0.3 MPa; nanofiltration membranes muaj tus nqi desalination ntawm 0-95% thiab kev khiav hauj lwm siab ntawm 0.3-0.6 MPa; rov qab osmosis daim nyias nyias muaj tus nqi desalination ntawm 95.0% -99.9%, qhov tsawg kawg nkaus permeate salinity ntawm kwv yees li 1 mg / L, thiab kev khiav hauj lwm siab ntawm 0.7-7.0 MPa.
Electrodialysis tsim cov dej desalinated uas tsis permeate daim nyias nyias. Qhov tsawg kawg nkaus permeate salinity yog ze rau qhov rov qab osmosis, thiab kev khiav hauj lwm siab yog 0.1-0.2 MPa. Tus nqi desalination tuaj yeem hloov kho nyob rau hauv thaj tsam ntawm 0-98% nyob ntawm txoj kev khiav ntev thiab kev siv tam sim no.
Sau cov dej desalinated dej ntws ntawm electrodialysis nrog anion thiab cation txauv resins ua ib lub txaj txaj electrodialysis. Thaum lub influent salinity nyob rau hauv thaj tsam ntawm 2-5 mg / L, permeate conductivity ntawm resin txaj electrodialysis tuaj yeem khaws cia ntawm qib 10-15 MΩ.
(4) Kev faib tawm los ntawm Membrane Structure
Raws li qhov sib txawv ntawm qhov ntxeem tau thiab tsis yog - cov txheej txheem ntxeem tau, cov txheej txheem sib cais tuaj yeem muab faib ua cov porous daim nyias nyias thiab tuab daim nyias nyias. Porous membranes muaj ib tug loj tus naj npawb ntawm permeable pores, thaum ntom membranes tsis muaj permeable pores.
Raws li qhov sib xws ntawm cov qauv ntawm daim nyias nyias, cov ntaub nyias nyias thiab daim nyias nyias nyias tuaj yeem muab faib ua homogeneous daim nyias nyias thiab heterogeneous daim nyias nyias. Cov qauv membrane ntawm ib homogeneous daim nyias nyias yog sib xws nyob rau hauv ntsug kev taw qhia ntawm daim nyias nyias nto, thaum lub membrane qauv ntawm ib tug heterogeneous daim nyias nyias yog tsis yog -ib tug nyob rau hauv lub ntsug kev taw qhia ntawm daim nyias nyias.
Microfiltration membranes yog porous heterogeneous membranes. Lub pore loj hloov pauv tsis tu ncua thaum permeating daim nyias nyias, thiab kev tuav pov hwm kev ua haujlwm yog txiav txim siab los ntawm qhov nruab nrab qhov pore loj thiab porosity.
Ultrafiltration membranes yog ntxeem tau, heterogeneous membranes. Cov dej pub rau sab ntawm daim nyias nyias muaj cov txheej ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom ntom txheej txheej txheej txheej txheej, ua rau cov pore me me ntawm cov dej pub mis thiab cov pore loj dua ntawm cov dej huv, yooj yim rau cov dej permeability. A typical dense homogeneous membrane is an ion exchange membrane used in electrodialysis, with limited water permeability but extremely high permeability for positive or negative ions.
Aromatic polyamide thim rov qab osmosis daim nyias nyias yog feem ntau heterogeneous ntom daim nyias nyias. Cov membrane no muaj cov thicker, siab -ceev, ntxeem tau cov membrane laminated nrog ib tug nyias nyias txheej ntawm high-ceev permeability, ua tiav ob qho tib si siab permeability thiab siab permeability piv ib txhij.
Dense homogeneous membranes have a uniform structure in all directions and possess high permeability ratios, but due to their low permeability, they are generally not formed independently and are often the dense layer of composite membranes.
(5) Kev faib tawm los ntawm Element Structure
Lub cev membrane yog ib lub tsev ua haujlwm membrane uas tsim los ntawm kev sib txuas ntawm daim ntawv -zoo li los yog filamentous membranes nrog cov khoom siv sib xws. Raws li kev sib txawv ntawm cov qauv, cov ntsiab lus membrane tuaj yeem muab faib ua cov qauv sib txawv xws li phaj, pleated, tubular, hollow, thiab kauv qhov txhab.
Ntau cov qauv membrane muaj lawv tus kheej qhov zoo thiab qhov tsis zoo nyob rau hauv cov nqe lus ntawm cheeb tsam volumetric, ntws qauv, kev txhawb siab, thiab kev tu.
Fine filtration, microfiltration, thiab ultrafiltration membranes tuaj yeem npaj rau hauv cov qauv phaj siv rau hauv cov phaj thiab cov lim lim. Txawm hais tias cov phaj thiab thav duab cov ntxaij lim dej muaj qhov me me volumetric thiab yuav tsum tau hloov cov khoom siv ntawm cov ntaub so ntswg, tsuas yog ua haujlwm tsis tu ncua, cov khoom siv rau kev txhawb nqa membrane thiab dej conduction tsis yog siv pov tseg, ua rau cov khoom siv qis tshaj thaum hloov cov membranes.
Fine filtration thiab microfiltration membranes kuj tuaj yeem npaj rau hauv cov qauv pleated los tsim cov lim pleated. Cov no cia siab rau cov qauv pleated kom nce qhov ntim ntawm thaj tsam thiab siv cov membrane nws tus kheej los tsim cov kev txhawb nqa rov qab thiab cov kav dej. Txawm li cas los xij, hloov pleated membranes nce tus nqi ntawm cov khoom siv.
Ob lub phaj thiab pleated daim nyias nyias qhia tus yam ntxwv ntawm kev ua haujlwm puv - ntws. Lawv cov teeb meem tshwm sim muaj xws li qhov tsis muaj peev xwm ua kom tsis tu ncua ntawm qhov loj thiab tsis muaj peev xwm los ntxuav. Vim lawv cov cuab yeej siv yooj yim thiab kev ua haujlwm yooj yim, lawv feem ntau yog siv rau hauv me me - nplai, qis- cov txheej txheem kev ua qias tuaj hauv qhov chaw kho dej.
Tubular daim nyias nyias tuaj yeem yog microfiltration, ultrafiltration, nanofiltration, lossis txawm tias rov qab osmosis daim nyias nyias, ua haujlwm nyob rau hauv lub siab nrog ib txoj kab uas hla ntawm 10-15 hli. Tubular daim nyias nyias tsis tuaj yeem thim rov qab, muaj thaj tsam me me, cov cuab yeej siv siab, thiab cov cuab yeej siv qis; Txawm li cas los xij, lawv tuaj yeem ua tau zoo rau pem hauv ntej- ntxuav, ua rau lawv tsim nyog rau kev kho cov siab -viscosity, siab- cov kua dej turbidity thiab cov qauv membrane zoo heev rau kev pub noj tshwj xeeb thiab kev kho dej khib nyiab.
Hollow filtration membranes tuaj yeem yog microfiltration, ultrafiltration, nanofiltration, lossis thim rov qab osmosis, nrog cov kab nruab nrab ntawm 25 txog 1200 μm thiab sab nraud ntawm 50 txog 2000 μm.
Hollow filtration membranes tuaj yeem muab faib ua lub siab sab hauv thiab sab nrauv siab raws li cov kev taw qhia siab. Internal siab membranes muaj ib tug me me volumetric cheeb tsam thiab cov av qis dua - tuav lub peev xwm, yog ib qho yooj yim rau hydraulically flush, thiab muaj kev xav tau siab rau cov dej zoo. Lawv tuaj yeem ua haujlwm hauv cross-flow lossis puv-flow hom. Sab nraud siab membranes muaj ib tug loj volumetric cheeb tsam thiab ntau dua av- tuav lub peev xwm, tsis yooj yim rau hydraulically flush, muaj qis dua cov kev cai rau pub dej zoo, thiab feem ntau ua hauj lwm nyob rau hauv tag nrho - ntws hom, ua rau nws nyuaj rau tsim cross- ntws.
Hollow filtration membranes tuaj yeem muaj qhov chaw siab heev, tsis sib xws los ntawm lwm cov qauv membrane, thiab muaj kev ua tau zoo rau pem hauv ntej thiab rov qab ua haujlwm.
Vim tias tsis muaj zog txhua yam ntawm cov hollow membrane fibers, fiber ntau breakage yog ib qho teeb meem loj, thiab fiber ntau breakage tus nqi nyob rau hauv ib lub sij hawm ua hauj lwm los ua ib qho tseem ceeb qhia txog membrane lifespan.
Yob-cov qauv membrane feem ntau yog siv rau nanofiltration thiab thim rov qab osmosis membranes, thiab nyob rau hauv xyoo tas los no, kauv-up ultrafiltration membranes kuj tau tshwm sim. Cov qauv no muaj thaj tsam nruab nrab ntawm qhov ntim thiab qhov zoo xws li kev ua haujlwm siab ua haujlwm, cov dej tsis zoo yuav tsum tau muaj, muaj peev xwm fouling loj, yooj yim hla- ntws, thiab muaj peev xwm ua rau pem hauv ntej flushing.
Tus ntoo khaub lig- ntu ntawm cov dej pub dej ntws hauv ib qho kauv- li daim nyias nyias tuaj yeem suav tau tias yog ib txoj kab ncaj nraim ntawm qhov siab sib xws. Cov qauv no tso cai rau cov fouling hauv zos thiab muaj peev xwm fouling siab; Txawm li cas los xij, nws tsis yog yooj yim kom ua tiav cov txiaj ntsig zoo hauv txhua qhov chaw, ua rau nws yooj yim rau qhov chaw fouling.
Tsis tas li ntawd, kauv-cov ntaub ntawv sib xyaw tsis tuaj yeem rov qab ntxuav, ua rau muaj kev tu tsis zoo. Kev ua tau zoo degradation vim membrane fouling yog ib qho teeb meem loj rau kauv -cov qauv, thiab cov qib ntawm kev ua tau zoo degradation nyob rau hauv ib lub sij hawm ua hauj lwm los ua ib qho tseem ceeb qhia txog membrane lifespan.