CN103551061A - Preparation method of high-negative charge density hollow fiber nanofiltration membrane for removing Cr(VI) from water - Google Patents
Preparation method of high-negative charge density hollow fiber nanofiltration membrane for removing Cr(VI) from water Download PDFInfo
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- CN103551061A CN103551061A CN201310586458.5A CN201310586458A CN103551061A CN 103551061 A CN103551061 A CN 103551061A CN 201310586458 A CN201310586458 A CN 201310586458A CN 103551061 A CN103551061 A CN 103551061A
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- membrane
- hollow fiber
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- nanofiltration membrane
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Abstract
The invention discloses a high-energy electron beam co-irradiation grafting method for preparing a high-negative charge density hollow fiber nanofiltration membrane. The method comprises the following steps: washing a basal membrane to fully remove glycerin molecules from the surface of the membrane and membrane pores, impregnating the treated basal membrane into a mixed solution containing monomers, a cross-linking agent and a polymerization inhibitor, introducing nitrogen for protection, performing co-irradiation under high-energy electron beams, and performing free radical grafting polymerization reaction to graft the monomers to the inner and outer surfaces of the basal membrane to obtain the nanofiltration membrane. Preferably, the mixed solution comprises 0.1-0.5wt% cross-linking agent and 1-3wt% polymerization inhibitor. The prepared nanofiltration membrane has great flux and a good high-valence anion rejection effect, and is practical particularly for the removal of Cr(VI) in wastewater. The high-energy electron beam co-irradiation grafting method is easy to operate and convenient, can be implemented at room temperature, and can be used for large-scale production.
Description
Technical field
The invention belongs to diffusion barrier preparation and field of environment engineering, particularly a kind of employing electron beam mutual radiation crosslinking technology is for the preparation of the method for removing the high negative charge density hollow fiber nanofiltration membrane of Cr (VI) in water.
Background technology
Since 20th century, heavy metal chromium and compound is able to extensive use in fields such as plating, process hides, dyestuff, pigment, organic synthesis, petrochemical industry, timber pressurization making, and the pollution of chromium problem accompanying is with it also more and more serious.Chromium generally exists with Cr VI [Cr (VI)] and two kinds of stable valence states of trivalent chromium [Cr (III)] in water environment.Wherein, Cr (VI) toxicity greatly, easily accumulation in vivo, carcinogenic aberration inducing effect is strong, and ecological environment and health are all caused to very large harm.In < < integrated wastewater discharge standard > > (GB8996-1996) regulation waste water, the highest permission concentration of emission of Cr (VI) is 0.5mg/L; The highest permission concentration of emission of the regulation Cr of world health organization (WHO) (VI) is 0.05mg/L.
NF membrane (Nanofiltration membrane, NF) is a kind of pressure-driven membrane process between counter-infiltration and ultrafiltration, its aperture generally on the whole of nanoscale and most of films or surface with electric charge, there is high ion isolation ability at a low price.Nanofiltration-membrane technique separative efficiency is high, and equipment is simple, without adding chemical agent, pollution-free, is having more application in recent years aspect industrial wastewater containing chromium processing.Chinese patent CN201737793U discloses a kind of mixing electroplating wastewater regeneration device, after pretreatment, adopt the combination of two sections of nanofiltration membrane components and one section of reverse osmosis membrane assembly, for mix the processing of electroplating wastewater containing chromium and other heavy metals etc. containing cyanogen, reduce processing cost, realized higher reclamation rate.In addition, in the technological process of numerous embrane method processing waste water containing chrome such as patent CN103253798A, CN102358644A and CN101318732, NF membrane is all as device core, acting in conjunction based on sieve effect and Dao Nan effect, plays key effect to the removal of Cr (VI) and recycling.The nanofiltration membrane component using in above-mentioned patent mostly is rolled film, for rolled film, hollow-fibre membrane has that loading density is high, specific area is large, resistance to pressure is good, do not need backing material, modular construction is simple and easy to the advantages such as leak detection, but current domestic hollow fiber nanofiltration membrane fails to realize suitability for industrialized production always.Therefore, can prepare on a large scale the hollow fiber nanofiltration membrane that possesses large flux, Cr (VI) ion is there is to high rejection characteristic, be applied in actual industrial sewage treatment technology process, for the raising of economic benefit and operating efficiency, all possess significance.
In recent years, by graft polymerization reaction, introduce specific functional group on basement membrane, the functional layer of formation is combined with covalent bond effect between basement membrane, is the effective means of preparing hollow fiber nanofiltration membrane.Early stage patent CN1586702 mainly adopts ultraviolet mutual radiation Graft Method, prepares composite nanometer filtering film, but because ultraviolet irradiation energy is lower, its restricted application.Publication number is to adopt the method for two step low temperature plasma irradiation graftings to prepare nanofiltration membrane with negative electric charge in the patent of CN102068912A, but gained NF membrane is limited to the rejection effect of sodium sulphate, flux is lower, preparation process is complicated simultaneously, is not suitable for large-scale industrial production.Compare with ultraviolet, low temperature plasma irradiation, high-energy electron beam irradiation energy is high, and penetration capacity is strong, strong to the surface active of membrane material; Simultaneous reactions is without additional initator, the reagent such as sensitising agent, and environmental protection, reacts easy to be controlled.Publication number is to carry out graft polymerization reaction after the patent of CN101780377A adopts high-power electron beam pre-irradiation, prepares the good nanofiltration membrane with negative electric charge of cutoff performance and permeance property, but pre-irradiation process relative complex and easily base material is caused to damage.Mutual radiation technical operation is simple, convenient and easy, under room temperature, can complete, and can be used for large-scale industrial production.Utilize high-power electron beam mutual radiation crosslinking technology to prepare the research of hollow fiber nanofiltration membrane less, obtained hollow fiber nanofiltration membrane surfaces externally and internally is successful grafting sulfonic group monomer all, and the research that possesses high negative charge density feature yet there are no.
Summary of the invention
For the deficiencies in the prior art, the object of the invention is to propose a kind of technique simple, react the preparation method of controlled high negative charge density hollow fiber nanofiltration membrane.Gained hollow fiber nanofiltration membrane has good rejection effect to high price anion when having large flux, especially aspect the Cr (VI) in removing waste water, possesses Practical Performance.
The technical scheme that the present invention solves described hollow fiber nanofiltration membrane manufacture method technical problem is, adopt high-power electron beam mutual radiation crosslinking technology, when polymer hollow fiber ultrafiltration membrane surfaces externally and internally is introduced strongly hydrophilic group, adjust membrane pore structure, realize and be clipped to other transformation of nanofiltration level from ultrafiltration level.
It is characterized in that step is as follows:
1. polymer hollow fiber ultrafiltration membrane is soaked to shake to clean to be placed on for 3～5 times in ultra-pure water with ultra-pure water and soak about 24h, fully to remove the glycerol molecule in striping surface and fenestra.
2. to adding in solvent, contain sulfonic monomer, crosslinking agent and polymerization inhibitor, stirring is fully dissolved it, the mass percent concentration that obtains monomer is 3%～30%, the mass percent concentration of crosslinking agent is 0.05%～2%, the mixed solution A that the mass percent concentration of polymerization inhibitor is 0.5%～5%.、
3. the 1st step processing polymer hollow fiber ultrafiltration membrane is immersed in solution A and is packed in polyethylene sealing bag, pass into nitrogen 10～30min, be placed in irradiation under high-power electron beam, electronic beam current intensity is 5～40mA, and irradiation dose is 10～120kGy.The graft copolymer membrane obtaining is placed in to ultra-pure water and soaks 12h～24h and remove unreacted monomer and homopolymers, obtain described high negative charge density hollow fiber nanofiltration membrane.
As a kind of preferred, in described step 2, the described mass percent concentration that adds crosslinking agent is 0.1%～0.5%.
As a kind of preferred, in described step 2, the described mass percent concentration that adds polymerization inhibitor is 1%～3%.
Basement membrane of the present invention is specially a kind of in polysulfones polyether sulfone that molecular cut off is 6,000～30,000Da or polyvinylidene fluoride hollow fiber ultrafiltration membrane.Described solvent can be ethanol water solvent or methanol-water solvent, and the volume ratio of alcohol and water is 1/9～1/1.The described sulfonic monomer that contains can be 2-acrylamide-2-methyl propane sulfonic, sodium p styrene sulfonate or ALS.Described crosslinking agent can be iso-cyanuric acid triallyl ester, trimethylolpropane triacrylate, triallyl cyanogen urea ester or divinylbenzene.Described polymerization inhibitor can be iron ammonium sulfate, ferrous sulfate and copper sulphate.
Through check, the prepared bear of the present invention electricity hollow fiber nanofiltration membrane surfaces externally and internally is successful grafting sulfonic group all.By adjusting grafting condition, the percent grafting of the NF membrane making is 1.0～20.0mmolm
-2.In temperature, be 25 ℃, operating pressure is 0.4MPa, and under the operating condition that flow velocity is 56L/h, prepared NF membrane pure water flux is 10～50Lm
-2h
-1; To divalent salts Na
2sO
4rejection be 75～98%; Under certain condition, to the rejection of Cr in the aqueous solution (VI), can reach more than 90%, in solution, contain NaCl or Na
2sO
4time, little for the rejection impact of Cr (VI).
The present invention adopts high-power electron beam mutual radiation crosslinking technology, take full advantage of high energy electron beam energy high, penetrability is strong, the advantage strong to the surface active of membrane material, membranous surface activity site is increased, be more conducive to contact with containing sulfonic monomer in alcohol solution, make the strongly hydrophilic monomer of more difficult grafting be grafted to smoothly hydrophobic basement membrane surfaces externally and internally, the monomer using is conveniently easy to get, cheap.Gained hollow fiber nanofiltration membrane possesses the feature of high negative charge density, when having large flux, high price anion is had to good rejection effect, especially aspect the Cr (VI) in removing waste water, possesses Practical Performance.
The specific embodiment
Introduce specific embodiments of the invention below, but the present invention is not subject to the restriction of embodiment.
Embodiment 1.
The ps hollow fiber uf membrane that is 15,000 by molecular cut off is soaked concussion with ultra-pure water and is cleaned to be placed on for 3～5 times and in ultra-pure water, soak about 24h.After cleaning, hollow-fibre membrane being immersed in to 2-acrylamide-2-methyl propane sulfonic mass percent concentration is 5%, iron ammonium sulfate mass percent concentration be 1.5% and the iso-cyanuric acid triallyl ester mass percent concentration ethanol water that is 0.1% in (volume ratio of ethanol and water is 1/4), pass into nitrogen 15min, with high energy electron radiation source beam, basement membrane and monomer solution are carried out to mutual radiation again, irradiation dose is 60kGy, after irradiation finishes, the graft copolymer membrane obtaining being placed in to ultra-pure water soaks 12h～24h and removes unreacted monomer and homopolymers to obtain percent grafting be 2.67mmolm
-2high negative charge density NF membrane.This film is at 25 ℃, 0.4MPa, and under the operating condition of 56L/h, the Na to 1g/L
2sO
4rejection be 84.7%, permeation flux is 33.7Lm
-2h
-1.Under same operation conditions, pH is 9 o'clock, to the rejection of the Cr of 0.1mM (VI), is 93.0%, and permeation flux is 30.2Lm
-2h
-1; In the Cr of 0.1mM (VI) aqueous solution, contain 3mM NaCl time, Cr (VI) rejection is 91.6%, permeation flux is 29.6Lm
-2h
-1.
Embodiment 2.
The ps hollow fiber uf membrane that is 20,000 by molecular cut off is soaked concussion with ultra-pure water and is cleaned to be placed on for 3～5 times and in ultra-pure water, soak about 24h.After cleaning, hollow-fibre membrane being immersed in to 2-acrylamide-2-methyl propane sulfonic mass percent concentration is 10%, iron ammonium sulfate mass percent concentration be 2% and the iso-cyanuric acid triallyl ester mass percent concentration ethanol water that is 0.2% in (volume ratio of ethanol and water is 1/7), pass into nitrogen 15min, with high energy electron radiation source beam, basement membrane and monomer solution are carried out to mutual radiation again, irradiation dose is 80kGy, after irradiation finishes, the graft copolymer membrane obtaining being placed in to ultra-pure water soaks 12h～24h and removes unreacted monomer and homopolymers to obtain percent grafting be 4.68mmolm
-2high negative charge density NF membrane.This film is at 25 ℃, 0.4MPa, and under the operating condition of 56L/h, the Na to 1g/L
2sO
4rejection be 91.7%, permeation flux is 32.3Lm
-2h
-1.Under same operation conditions, pH is 9 o'clock, to the rejection of the Cr of 1mM (VI), is 93.9%, and permeation flux is 29.8Lm
-2h
-1; The Na that contains 1.5mM in the Cr of 1mM (VI) aqueous solution
2sO
4time, Cr (VI) rejection is 93.0%, permeation flux is 26.3Lm
-2h
-1.
Embodiment 3.
The ps hollow fiber uf membrane that is 20,000 by molecular cut off is soaked concussion with ultra-pure water and is cleaned to be placed on for 3～5 times and in ultra-pure water, soak about 24h.After cleaning, hollow-fibre membrane being immersed in to 2-acrylamide-2-methyl propane sulfonic mass percent concentration is 15%, iron ammonium sulfate mass percent concentration be 2.5% and the iso-cyanuric acid triallyl ester mass percent concentration ethanol water that is 0.2% in (volume ratio of ethanol and water is 1/9), pass into nitrogen 15min, with high energy electron radiation source beam, basement membrane and monomer solution are carried out to mutual radiation again, irradiation dose is 100kGy, after irradiation finishes, the graft copolymer membrane obtaining being placed in to ultra-pure water soaks 12h～24h and removes unreacted monomer and homopolymers to obtain percent grafting be 9.95mmolm
-2high negative charge density NF membrane.This film is at 25 ℃, 0.4MPa, and under the operating condition of 56L/h, the Na to 1g/L
2sO
4rejection be 94.2%, permeation flux is 21.9Lm
-2h
-1.Under same operation conditions, pH is 9 o'clock, to the rejection of the Cr of 0.1mM (VI), is 96.0%, and permeation flux is 20.8Lm
-2h
-1; In the Cr of 0.1mM (VI) aqueous solution, contain 7mM NaCl time, Cr (VI) rejection is 93.7%, permeation flux is 16.4Lm
-2h
-1.
Embodiment 4.
The ps hollow fiber uf membrane that is 25,000 by molecular cut off is soaked concussion with ultra-pure water and is cleaned to be placed on for 3～5 times and in ultra-pure water, soak about 24h.After cleaning, hollow-fibre membrane being immersed in to 2-acrylamide-2-methyl propane sulfonic mass percent concentration is 10%, iron ammonium sulfate mass percent concentration be 3% and the iso-cyanuric acid triallyl ester mass percent concentration ethanol water that is 0.3% in (volume ratio of ethanol and water is 1/9), pass into nitrogen 15min, with high energy electron radiation source beam, basement membrane and monomer solution are carried out to mutual radiation again, irradiation dose is 80kGy, after irradiation finishes, the graft copolymer membrane obtaining being placed in to ultra-pure water soaks 12h～24h and removes unreacted monomer and homopolymers to obtain percent grafting be 15.25mmolm
-2high negative charge density NF membrane.This film is at 25 ℃, 0.4MPa, and under the operating condition of 56L/h, the Na to 1g/L
2sO
4rejection be 95.5%, permeation flux is 18.6Lm
-2h
-1.Under same operation conditions, pH is 9 o'clock, to the rejection of the Cr of 1mM (VI), is 96.9%, and permeation flux is 17.1Lm
-2h
-1; The Na that contains 3.5mM in the Cr of 1mM (VI) aqueous solution
2sO
4time, Cr (VI) rejection is 94.2%, permeation flux is 13.3Lm
-2h
-1.
Claims (6)
1. for removing a preparation method for the high negative charge density hollow fiber nanofiltration membrane of water Cr (VI), it is characterized in that comprising following steps:
A) polymer hollow fiber ultrafiltration membrane is placed on for 3～5 times in ultra-pure water and soaks about 24h with ultra-pure water immersion concussion cleaning, fully to remove the glycerol molecule in striping surface and fenestra.
B) to adding in solvent, contain sulfonic monomer, crosslinking agent and polymerization inhibitor, stirring is fully dissolved it, the mass percent concentration that obtains monomer is 3%～30%, the mass percent concentration of crosslinking agent is 0.05%～2%, the mixed solution A that the mass percent concentration of polymerization inhibitor is 0.5%～5%.
C) the polymer hollow fiber ultrafiltration membrane of processing through step a is immersed in solution A and is packed in polyethylene sealing bag, pass into nitrogen 10～30min, be placed in irradiation under high-power electron beam, electronic beam current intensity is 5～40mA, and irradiation dose is 10～120kGy.The graft copolymer membrane obtaining is placed in to ultra-pure water and soaks 12h～24h and remove unreacted monomer and homopolymers, obtain the described high negative charge density hollow fiber nanofiltration membrane in large aperture.
2. according to claim 1 a kind of for removing the preparation method of the high negative charge density hollow fiber nanofiltration membrane of water Cr (VI), it is characterized in that using basement membrane to be specially molecular cut off be 6, a kind of in the polysulfones of 000～30,000Da, polyether sulfone or polyvinylidene fluoride hollow fiber ultrafiltration membrane.
3. according to claim 1 a kind of for removing the preparation method of the high negative charge density hollow fiber nanofiltration membrane of water Cr (VI), it is characterized in that containing sulfonic monomer can be 2-acrylamide-2-methyl propane sulfonic, sodium p styrene sulfonate or ALS.
4. according to claim 1 a kind of for removing the preparation method of the high negative charge density hollow fiber nanofiltration membrane of water Cr (VI), the preferred mass percent concentration that it is characterized in that the crosslinking agent described in step b is 0.1%～0.5%, and crosslinking agent can be iso-cyanuric acid triallyl ester, trimethylolpropane triacrylate, triallyl cyanogen urea ester or divinylbenzene.
5. according to claim 1 a kind of for removing the preparation method of the high negative charge density hollow fiber nanofiltration membrane of water Cr (VI), the preferred mass percent concentration that it is characterized in that the polymerization inhibitor described in step b is 1%～3%, and polymerization inhibitor can be iron ammonium sulfate, ferrous sulfate and copper sulphate.
6. according to claim 1 a kind of for removing the preparation method of the high negative charge density hollow fiber nanofiltration membrane of water Cr (VI), it is characterized in that described solvent can be ethanol water solvent or methanol-water solvent, the volume ratio of alcohol and water is 1/9～1/1.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104258747A (en) * | 2014-03-04 | 2015-01-07 | 上海大学 | Method for preparing nylon-66 grafted crylic acid by electronic beam pre-irradiation |
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| CN102000511A (en) * | 2010-12-07 | 2011-04-06 | 天津工业大学 | Method for preparing positive charge hollow fiber nanofiltration membrane through surface UV irradiation grafting |
| CN102068912A (en) * | 2010-12-07 | 2011-05-25 | 天津工业大学 | Method for preparing negatively charged nanofiltration membrane through grafting induced after plasma radiation |
| CN102626592A (en) * | 2012-01-12 | 2012-08-08 | 天津工业大学 | Method for preparing hydrophilic PVDF hollow fiber membrane by high energy electron beam mutual irradiation grafting |
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Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
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| US20020161066A1 (en) * | 2000-06-14 | 2002-10-31 | Jean-Christophe Remigy | Method for making a nanofiltration membrane, and resulting membrane |
| CN101115546A (en) * | 2005-02-11 | 2008-01-30 | 保罗·谢勒学院 | A method of preparing a radiation fuel cell membrane with enhanced chemical stability and a membrane electode assembly |
| CN1919747A (en) * | 2006-09-15 | 2007-02-28 | 北京化工大学 | Closed circuit processing technique for chromium-containing wastewater |
| CN102000511A (en) * | 2010-12-07 | 2011-04-06 | 天津工业大学 | Method for preparing positive charge hollow fiber nanofiltration membrane through surface UV irradiation grafting |
| CN102068912A (en) * | 2010-12-07 | 2011-05-25 | 天津工业大学 | Method for preparing negatively charged nanofiltration membrane through grafting induced after plasma radiation |
| CN102626592A (en) * | 2012-01-12 | 2012-08-08 | 天津工业大学 | Method for preparing hydrophilic PVDF hollow fiber membrane by high energy electron beam mutual irradiation grafting |
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| CN104258747A (en) * | 2014-03-04 | 2015-01-07 | 上海大学 | Method for preparing nylon-66 grafted crylic acid by electronic beam pre-irradiation |
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Application publication date: 20140205 |