Lub zog muaj zog npaum li cas yog Nanofiltration Membranes Rau Hnyav Hlau Tshem Tawm?

Heavy metal contaminated water treatment yog ib lub ntsiab lus kub hauv ib puag ncig. Kev tshuaj xyuas tsis ntev los no tau sau tseg cov kev tshawb fawb txog kev ua tiav ntawm nanofiltration membranes hauv kev tshem tawm cov hlau hnyav ions, qhia tias los ntawm cov khoom siv tshiab thiab cov txheej txheem optimization, nanofiltration membrane dej flux tuaj yeem nce ntau dua 3 zaug, thiab tshem tawm tus nqi ntawm ntau yam hlau hnyav xws li Cu²⁺, Pb²⁺, thiab Cd²⁺, thiab Cd² 9% kev kho tau zoo.

Kev kub ntxhov thoob ntiaj teb dej tsis txaus ua rau muaj kev hem thawj rau ntau dua 1.8 billion tus neeg lub neej. Muaj ob lub laj thawj tseem ceeb rau qhov teeb meem no: thawj zaug, dej hiav txwv tso nyiaj rau feem coob ntawm cov dej hauv ntiaj teb no, thaum cov dej tshiab siv tau tsawg; Thib ob, kev tso dej pov tseg ua rau muaj kev ua qias tuaj rau hauv dej tshiab. Txawm hais tias seawater desalination thev naus laus zis tau ua kom muaj kev vam meej nyob rau xyoo tas los no, ntau cov hlau hnyav hnyav (xws li Zn²⁺, Cu²⁺, Fe²⁺, Hg²⁺, Cd²⁺, Pb²⁺, Cr⁶⁺, thiab lwm yam) hauv cov dej khib nyiab tuaj yeem kis cov dej desalinated rau tib neeg lub cev.

Yog li ntawd, kev tsim cov thev naus laus zis rau kev tshem tawm cov kab mob hnyav hnyav los ntawm cov dej qias neeg yog qhov tseem ceeb tshwj xeeb, vim qhov no tuaj yeem ua tiav ob lub hom phiaj: kom tau txais cov dej tshiab thiab rov ua kom muaj txiaj ntsig zoo.

Nanofiltration membranes muaj qhov pore loj ntawm 0.5-2 nm, poob ntawm ultrafiltration membranes (10-}100 nm, siab flux tab sis tsis kam lees) thiab rov qab osmosis membranes (siab rejection tab sis tsawg flux, siab zog noj). Nanofiltration membranes tuaj yeem khaws cov hlau ions hnyav thaum muab cov kev thauj mus los rau cov dej molecules los ntawm nanopores, ua rau lawv siv thev naus laus zis los kho cov dej khib nyiab hnyav hlau.

Separation Mechanisms:

Kev Ntsuas Loj: Raws li qhov sib txawv ntawm lub vojvoog ntawm cov khoom khaws cia thiab cov ntaub ntawv permeated. Nanofiltration membrane pore qhov ntau thiab tsawg yog loj dua li txoj kab uas hla ntawm cov dej molecules (0.4 nm), tab sis piv rau txoj kab uas hla ntawm hydrated hnyav hlau ions, tso cai rau kev sib cais zoo los ntawm kev kho qhov pore loj.

Donnan Repulsion: Raws li cov electrostatic repulsion ntawm ions thiab them daim nyias nyias nto. Hnyav hlau ions feem ntau raug them zoo, yog li qhov zoo ntawm daim nyias nyias yog qhov tsim nyog rau khaws cov pa phem ions.

Tsis tas li ntawd, pH ntawm cov khoom noj muaj txiaj ntsig cuam tshuam rau kev ua haujlwm ntawm daim nyias nyias: ntawm ib sab, nws hloov pauv tus nqi saum npoo thiab qib ntawm tus ntoo khaub lig- txuas ntawm lub network polymer, yog li cuam tshuam rau qhov tsis lees paub thiab permeability; ntawm qhov tod tes, nws cuam tshuam rau lub xeev ntawm cov hlau ions.

Organic Membranes

Organic membranes feem ntau yog npaj siv cov ntaub ntawv polymer, xws li polysulfone, cellulose acetate, polyvinylidene fluoride, polyethersulfone, polydimethylsiloxane, polyethylene, polycarbonate, thiab polyimide. Ntawm cov no, polyamide yog cov khoom siv dav tshaj plaws hauv kev npaj nanofiltration membrane, nthuav tawm kev ua tau zoo hauv seawater desalination.

Inorganic Membranes

Inorganic daim nyias nyias muaj cov tshuaj zoo heev thiab thermal stability thiab tuaj yeem tsim cov qauv pore. Cov ntaub ntawv ceramic, iav, hlau, zeolites, silica, palladium alloys, thiab ob- cov ntaub ntawv seem tau siv rau hauv kev npaj cov ntaub ntawv tsis muaj zog. Ceramic membranes yog tsim los ntawm cov hlau oxides thiab lawv cov derivatives, xws li TiO₂, SiO₂, ZrO₂, thiab Al₂O₃.

Hybrid Matrix Membranes
Hybrid matrix daim nyias nyias muab cov kev daws teeb meem ntawm cov polymers nrog cov permeability zoo heev ntawm nanofiller additives, aiming rau ib txhij txhim kho permeability thiab selectivity. Feem ntau siv additives muaj xws li:

• MOFs: Thaum MOF NH₂-MIL-125(Ti) suav nrog ntawm 0.010 wt%, cov dej permeability nce mus txog 12.2 L·m⁻²·h⁻¹·bar⁻¹, thiab Ni²⁺ rejection tus nqi yog 90.9%.
• COFs: Tom qab kev koom ua ke ntawm hydrophilic triazine-COFs, cov dej ntws mus txog 15 L·m⁻²·h⁻¹·bar⁻¹, thiab Zn²⁺ thiab Pb²⁺ tsis lees paub tus nqi yog 93.8% thiab 92.4%, feem.
• GO (ob - cov khoom siv qhov ntev): Tom qab kev sib xyaw ntawm chitosan rau hauv GO, cov dej ntws mus txog 55 L·m⁻²·h⁻¹, thiab Mn²⁺ tsis lees paub tus nqi yog 85%.
• ZnO nanoparticles: Txhim kho daim nyias nyias hydrophilicity, txo qhov roughness ntawm qhov chaw, thiab txhim kho cov khoom tiv thaiv fouling.

Phase Inversion Method

Txoj kev no, thawj zaug qhia txog kev siv tshuab membrane los ntawm Loeb thiab Sourajan hauv xyoo 1960, tso cai rau ib qho -txoj kev tsim cov txheej txheem xaiv thiab txhawb nqa. Lub membrane microstructure tuaj yeem tswj tau los ntawm kev kho cov polymer concentration, hnyav thiab coagulation da dej hom, additives, thiab tej yam kev mob. Piv txwv li:

• cGO-doped PPSU membrane: Dej permeability tau nce los ntawm 2.1 mus rau 3.5 L·m⁻²·h⁻¹, nrog kev tsis lees paub ntawm 99%, 98%, 82%, 82%, thiab 87% rau H₂AsO₄, HCrO₄⁻, Cd², thiab Cd²⁺ raws.
• CS-EDTA-mGO/PES membrane (magnetic field assisted): Dej flux mus txog 84.2. L·m⁻²·h⁻¹, Pb²⁺ tsis lees paub tus nqi 98.2%, Cd²⁺ tsis lees paub tus nqi 93.6%
• B-Cur nanoparticle/PES membrane: Kev tsis lees paub ntau tshaj 99% rau Fe²⁺, Cu²⁺, Pb²⁺, Mn²⁺, Zn²⁺, thiab Ni²⁺

Interfacial polymerization txoj kev

Interfacial polymerization yog ib qho ntawm feem ntau siv nanofiltration membrane npaj cov txheej txheem. Nws koom nrog rau hauv lub substrate daim nyias nyias nyob rau hauv ib tug aqueous tov uas muaj amine monomers, ua raws li los ntawm kev tiv tauj nws nrog ib tug organic tov uas muaj acyl chloride monomers, tsim ib tug ultrathin polyamide txheej ntawm lub interface. Feem ntau siv monomers yog piperazine thiab trimesoyl chloride.

• COF nanoparticles -doped polyamide membranes: Dej permeability nce 67% (rau 10.8 L·m⁻²·h⁻¹·bar⁻¹), nrog Cu²⁺, Mn²⁺, thiab Pb²⁺ tsis lees paub tus nqi ntawm 98.3%, 98.9%, thiab feem ntau
• BHDA comonomer kev koom tes hauv interfacial polymerization: Cov dej ntws tau nce 2.4 npaug (mus rau 12.9 L·m⁻²·h⁻¹), nrog Cu²⁺, Zn²⁺, thiab Pb²⁺ tsis lees paub tus nqi ntawm 96.5%, 96.2%, thiab 88.4%, ntsig txog.
• Tsawg-kub interfacial polymerization (-15 degree): Membrane thickness txo, thiab dej flux mus txog 19.2. L·m⁻²·h⁻¹·bar⁻¹, tus nqi khaws cia rau Mn²⁺, Cd²⁺, thiab Cu²⁺ yog 97.9%, 87.7%, thiab 93.9%, feem.

Dip- txheej txheem txheej

Txoj kev dip- txheej txheej yog yooj yim rau kev khiav lag luam, kev lag luam, txuag, pov tseg -dawb, thiab lub zog- zoo. Lub substrate yog immersed nyob rau hauv lub active tshuaj tov thiab tso cai rau sawv ntsug rau ib lub sij hawm ntawm lub sij hawm, ces rub tawm ntawm ib tug ceev ceev, cia cov kuab tshuaj mus rau evaporate thiab tsim ib tug zaj duab xis.

• Qhov zoo them tus ntoo khaub lig- txuas PEI daim nyias nyias (ceramic substrate): Cov dej ntws tau nce ntawm 32 txog 82 L·m⁻²·h⁻¹·bar⁻¹, nrog rau kev tsis lees paub ntawm 99.8% rau Cu²⁺, 96.8% rau As⁵⁶, thiab 97%.
• Cu²⁺ complexed PEI membrane: Water flux 24.8 L·m⁻²·h⁻¹, with rejection rates of >95% rau Cd²⁺, Pb²⁺, Zn²⁺, thiab Ni²⁺.
• PEI/Cu²⁺ pre-complexed membrane: Dej flux 8.1 L·m⁻²·h⁻¹·bar⁻¹, tus nqi tuav rau Zn²⁺, Ni²⁺, thiab Cd²⁺ yog 91.8%, 83.2%, thiab 75.6%, feem.

Surface Modification/Functionalization

Kev hloov kho deg tuaj yeem tsim cov txheej txheem ultrathin ntawm nanofiltration membrane nto, ib txhij txhim kho kev xaiv thiab permeability.

• Triethanolamine-grafted PEI/TMC membrane: Water flux increased by 2 times (to 13.6 L·m⁻²·h⁻¹·bar⁻¹), with a rejection rate of >97% rau Zn²⁺, Cd²⁺, Ni²⁺, thiab Cu²⁺, thiab tsis lees txais tus nqi ntawm 92% rau Pb²⁺.
• CNFs-co-Cs modified PES membrane: Dej flux nce ntawm 4.25 mus rau 13.58 L·m⁻²·h⁻¹·bar⁻¹
• HNTs-DA modified NF270 membrane: Rejection rate of >95% rau Cd²⁺, Pb²⁺, Cu²⁺, Zn²⁺, thiab Ni²⁺.

Nanofiltration membrane tshuab tau ua qhov tseem ceeb hauv kev tshem tawm cov hlau ion hnyav. Los ntawm rationally xaiv cov ntaub ntawv membrane thiab cov txheej txheem npaj, lub microstructure ntawm nanofiltration daim nyias nyias tuaj yeem tswj tau, txhim kho dej flux thiab hnyav hlau ion rejection nqi.

Cov Lus Qhia Txog Kev Txhim Kho Yav Tom Ntej:

• Ion Selectivity: Hauv qhov tiag - dej qias neeg ntiaj teb, ntau cov hlau ions nyob ua ke. Nws yog ib qho tsim nyog los tsim cov nanofiltration daim nyias nyias muaj peev xwm xaiv khaws cov hlau ions tshwj xeeb kom ua tiav ob lub hom phiaj ntawm kev lim dej thiab cov hlau rov qab.
• Membrane Stability: Kev tshawb fawb tam sim no muaj lub voj voog luv luv, thiab kev ua haujlwm ntawm cov membranes feem ntau deteriorates lub sij hawm. Ntxiv ntoo khaub lig-txuas los yog kev taw qhia ntawm ruaj khov inorganic nanoparticles yog xav tau los txhim kho membrane stability.
• Antifouling Performance: Membrane fouling yog ib qho kev sib tw hauv kev siv tshuab membrane. Surface engineering (xws li tsim cov khoom zoo rau cov txheej txheem dej) yog xav tau los txo lossis tiv thaiv cov pa phem adsorption.
• Kev Ua Haujlwm Hom: Feem ntau cov kev tshawb fawb siv cov neeg tuag- kawg pom, tsis quav ntsej qhov teeb meem ntawm cov hlau ion adsorption hauv daim nyias nyias. Cov ntawv thov kev lag luam yuav tsum tau hla - cov qauv ua haujlwm ntws, thiab ntau dua yuav tsum tau them nyiaj rau lub sijhawm ntev - kev ua tau zoo ntawm daim nyias nyias nyob rau hauv hom no.