CN1480248A - A kind of cellulose separation membrane and preparation method thereof - Google Patents

Abstract

A cellulose membrane for separating Co2, SO2 hydrogen sulfide, etc is prepared from N-methyl morpholine oxide (MMNO) and cellulose through proportionally mixing, stirring for dissolving, defoaming to obtain membrane casting liquid, forming liquid membrane on glass plate by doctor blading process, coagulating and slowly drying. Its advantages are high crystallinity, mechanical strength and resistance to high temp, acid and alkali, and good osmotic separation performance.

Description

A kind of separation membrane made from cellulose and preparation method thereof

Technical field

The invention belongs to the technology of preparing and the application direction thereof of polymeric membrane for separation.Specifically be to use the direct dissolving cellulos preparation of N-methyl morpholine oxide (MMNO) solvent casting solution, make separation membrane made from cellulose, be applied to the liquids and gases separation field.

Background technology

Plant cellulose is a renewable resource the abundantest on the earth, belongs to environment-friendly material, makes full use of cellulose and has important practical significance.On chemical constitution, cellulose is the chain-like macromolecule compound that constitutes with the D-glucosyl group, and each glucose basic ring all contains 3 hydroxyls, has good hydrophily and resistance to acids and bases.But because cellulosic polyhydroxy feature has extremely strong hydrogen bond action between cellulosic molecule.Cellulose shows the degree of crystallinity height on the macroscopic view, chemistry, stable physical property, and the feature of glass transition temperature higher (Tg=220 ℃) is heated to 240 ℃ and takes place to decompose and not fusion, and is insoluble to common solvent.Therefore, the cellulose processing system film way by chemical modification always traditionally, be used after changing it into derivative: a kind of method is cellulose to be changed into derivatives such as cellulose ether, ester again, preparation cellulose derivative film, in this field, CAM, nitrocellulose filter and ethyl cellulose etc. have become the product that important application is arranged in the industry of system film; Another kind method is to use chemical method, and cellulose is become the cellulose derivative of solubility, again the regenerated cellulose film that obtains with solvent reclamation such as common cellophane (Cellphane) or regeneration cuprammonium cellulose membrane (Cuprophane) arranged.

These processing procedures narrow down the range of application of cellulose membrane, and application conditions is restricted.As the CAM facile hydrolysis, a little less than the antibiont aggressivity, in use the pH value scope of application there is strict demand (pH4～8); Industrialized so far viscose process prepares artificial silk and cellophane technology, and existing more than 50 year historical cuprammonium process production of cellulose silk and non-woven fabrics craft, all exists chemical method to destroy the shortcoming of the original natural characteristic of cellulose.Instrument is not in the chemical modification process, and degraded, sex change have taken place cellulose, and the degree of polymerization reduces, and degree of crystallinity descends, the mechanical strength variation, and anti acid alkali performance weakens, and exists the serious environmental pollution problem in producing, as the CS in the viscose process technology ₂Can't reclaim with cuprammonium technology in remaining copper to destruction of water quality etc.

US3133132 is known from patent, and immersing gel method is a kind of common method for preparing diffusion barrier.Macromolecule precipitating from homogeneous phase solution is come out the macromolecule casting solution of a homogeneous phase, make it to be divided into two-phase, one is the rich phase of macromolecule, forms the network structure of film; Another is that macromolecule is stingy mutually, forms fenestra.By changing casting solution character and coagulation bath condition, change the mutual mass exchange speed between casting solution and the coagulation bath, the diffusion barrier of preparation different shape, difference in functionality.

From U.S. Pat 2179181 known tertiary amino oxides dissolved celluloses, and can go out cellulosic shaped bodies such as cellulosics such as food pack, casing from this solution solidifies.Method from this solution of the also known manufacturing of patent patent EP0356419.As can be seen, cellulose may be dissolved in the tertiary amino oxides of water content up to 40wt.% and forms solution from these open source literatures.

Known from German patent DE 19750527, the cellulose solution in the tertiary amino oxides by push, solidify, the method for drawing and forming, the diffusion barrier that is used for gas, liquid field that can be made into different shape uses.

Cellulose membrane manufacture method from the known a kind of flat film shape of patent WO9849224, the cellulose solution that dissolves in the moisture tertiary amino oxides is squeezed into diaphragm shapes by the extruding jet nozzle with microscler extrusion slot, enter coagulating bath through behind 0.2～5 times of the air gap longitudinal stretching, the plain planar diaphragm of solidificating fiber, and cross directional stretch becomes the diffusion barrier with certain permeance property once more.Introduced the dialysis performance that this cellulose membrane is used for NaOH solution and NaCl solution: P in this patent _DiffusionNaOH is 2.5 * 10 ^-3～5.9 * 10 ^-3Cm/min, P _DiffusionNaCl is 1.7 * 10 ^-3～5.0 * 10 ^-3Cm/min.

US6019925 is known from patent, and the cellulose solution of use tertiary amino oxides dissolving can be made into plane, tubulose, the dialysis membrane of hollow fiber.

In addition, patent DE19515137 has also introduced a kind of method of making flat film, and this method is at first to make tubular film by nozzle ring, clean and drying after cut off the city planar diaphragm.The characteristics of this method are that the inside of pipe applies air pressure generation effect in the process of making tubular film, and the film tube that makes extruding form is not only being extruded direction in air gap, and laterally all is being stretched.

Summary of the invention

The purpose of this invention is to provide a kind of separation membrane made from cellulose and preparation method thereof, produce separation membrane made from cellulose with N-methyl morpholine oxide (a kind of tertiary amino oxides) as solvent in this method, this method film-forming process is simple, solvent is recyclable, and is pollution-free.

The another object of the present invention separation membrane made from cellulose that said method is prepared is applied to the separation of liquid mixtures such as protein solution separation, haemodialysis, sewage disposal, film absorption, membrane extraction and reclaims,, the separation that is particularly useful for acid, alkaline (polarity) gas such as carbon dioxide, sulfur dioxide, hydrogen sulfide, ammonia is reclaimed.

For achieving the above object, the invention provides a kind of preparation method of separation membrane made from cellulose, its preparation process is as follows:

(1) casting solution preparation: under 80～130 ℃ of temperature, with MMNO and the water of content 83～95wt.%, methyl alcohol, ethanol, isopropyl alcohol, DMF (dimethyl formamide), DMAc (dimethylacetylamide), DMSO (dimethyl sulfoxide (DMSO)), NMP (N-methyl pyrrolidone) make solvent and cellulose mixes, and can select to add proper quantity of antioxidant, also can not add antioxidant, stirring and dissolving, deaeration then, making content of cellulose is the cellulose casting solution of 5～20wt.%.

(2) the casting solution hydrostomia to level and smooth, clean glass plate, with scraper striking certain thickness film on the glass plate of cleaning, symphysis is put into coagulating bath together with glass plate then, obtains the gel state film after immersing gel.

(3) fully clean with clear water after, film is taken off, obtain solid-state cellulose membrane, relative humidity preferred 70%～90% in room temperature, 40%～95% time slow drying of relative humidity.

The present invention uses the cellulosic material of the degree of polymerization＞300 (being preferably 500～3000), its alpha-cellulose content＞85%.In (1) step, can in casting solution, add the gallate lactone antioxidant of 0.01wt.%～1wt.%, can also add the CaCl of 1wt.%～5wt.% ₂, MgCl ₂, MgSO ₄Or NH ₄Cl prevents cellulose oxidative degradation in course of dissolution as antioxidant.Can be according to making water in (2) step, the MMNO solution of 5～50wt.%, methanol solution, ethanolic solution, propyl ester antioxidants such as aqueous isopropanol can also add the CaCl of 1wt.%～5wt.% ₂, MgCl ₂, MgSO ₄Or NH ₄Cl prevents cellulose oxidative degradation in course of dissolution as antioxidant.Can be in (2) step according to making water, the MMNO solution of 5～50wt.%, methanol solution, ethanolic solution, the diffusion barrier of multiple difference in functionalitys such as coagulation bath condition preparation symmetry that aqueous isopropanol etc. are different or the plain film of asymmetrical microporous fibre, ultrafiltration cellulose membrane, nanofiltration cellulose membrane, the plain film of feltwork.

The cellulose membrane that the present invention is prepared, its microporous barrier, milipore filter, NF membrane, dense film can be used for reclaiming as the separation of liquid mixtures such as protein solution separation, haemodialysis, sewage disposal, film absorption, membrane extraction.And the plain film of prepared feltwork can be used for infiltration evaporation, gas separation process, is particularly useful for that carbon dioxide, sulfur dioxide, hydrogen sulfide, ammonia etc. are acid, the separation of alkalescence (polarity) gas is reclaimed.

Advantage of the present invention and effect:

The present invention uses the direct dissolving cellulos of N-methyl morpholine oxide and through immersing the separation membrane made from cellulose that gel method prepares different shape, difference in functionality, the reservation that diffusion barrier is more cellulosic natural characteristic.Compare with the regenerated cellulose film that uses xanthates (viscose process technology), cupric ammine complex (cuprammonium process technology) to wait other solvent to make, the separation membrane made from cellulose degree of crystallinity that this method makes increases, heat resistance strengthens, mechanical strength and solvent resistance and acid and alkali resistance performance are good, and admixture of gas is had better permeability and separation performance, and the separation that is particularly useful for sour gas such as carbon dioxide, sulfur dioxide, hydrogen sulfide is reclaimed.And this method MMNO solvent is easy to reclaim, and cost is low, and it is simple, pollution-free that solvent itself reaches whole film-forming process, is " green " technology.

The present invention need not be through derivative in the middle of generating, and directly dissolving cellulos is after immerse the separation membrane made from cellulose that gel method prepares different shape, difference in functionality.

Description of drawings

Fig. 1 is the SEM figure on the prepared cellulose membrane surface of the embodiment of the invention 1;

Fig. 2 is the SEM figure of the prepared cellulose membrane section of the embodiment of the invention 1;

Fig. 3 is the partial enlarged drawing of Fig. 2.

The specific embodiment $P=J\·l=\frac{V\·l}{t\·A\·\mathrm{\Δp}}$ In the formula

A---membrane area, cm ²

J---gas permeation rate,

Cm ³(STP)/(cm ²·s·cmHg)

L---film thickness, cm

P---gas pressure, cmHg

P---gas permeability coefficient,

Cm ³(STP)cm/(cm ²·s·cmHg)

T---the time, s

V---measurement gas volume, cm ³

Liquid permeation flux and rejection working concentration 0.1wt% bovine serum albumin determination of aqueous solution among the embodiment.Liquid permeation flux Q calculates according to the liquid volume that sees through film in the unit interval; Bovine serum albumin concentration is measured with the UV-260 ultraviolet-visible spectrophotometer of Shimadzu.The liquid permeation flux Q of film and be that 67000 bovine serum albumin rejection is calculated by following formula to molecular weight:

Embodiment 1

3.2 gram cellulose (average degree of polymerization ≈ 1000) adds in the MMNO solvent of the moisture 13.3wt.% of 32 grams, and 80 ℃, under nitrogen protection, stir 24hr, filter, deaeration, obtaining concentration is the 10wt.% casting solution.Under 110 ℃, to level and smooth, clean glass plate, use the casting solution hydrostomia scraper in cleaning

3.2 gram cellulose (average degree of polymerization ≈ 1000) adds in the MMNO solvent of the moisture 13.3wt.% of 32 grams, and 80 ℃, under nitrogen protection, stir 24hr, filter, deaeration, obtaining concentration is the 10wt.% casting solution.Under 110 ℃, the casting solution hydrostomia to level and smooth, clean glass plate, is scraped on the glass plate of cleaning with scraper and to be made the thick film of 150 μ m, immerse hydrogel then and solidify 24hr in bathing.Obtain the gel state film after immersing gel, after fully cleaning, room temperature, drying obtains solid-state cellulose membrane under relative humidity 85% condition.The film homogeneous is transparent, and smooth surface smooth (as shown in Figure 1, 2, 3), degree of crystallinity are 57% (calculating according to x-ray diffraction pattern).

Embodiment 2:

Except that the drying condition that uses relative humidity 50%, other implementation step is with embodiment 1.The tensile strength σ of prepared film _b, fracture stretches ε _bThe long 92.4MPa, 4.4% that is respectively.

Embodiment 3:

Except that coagulation bath used the water-bath of 5wt.%MMNO, other preparation process was with embodiment 1.The membrane crystallization degree that obtains is 59% (calculating according to x-ray diffraction pattern).Under 20 ℃, film is soaked in the H of variable concentrations ₂SO ₄Or NaOH solution, soak time is 5 days, takes out the back and cleans to solution with deionized water and be neutral, and is dry then, weigh, its quality Ws, and quality Wo compares before soaking with film.

Solution concentration (wt.%) Ws/Wo * 100%

5??????????????????94～96

H ₂SO ₄

3??????????????????＞99

5??????????????????95～98???NaOH???????????????12?????????????????92～95

18?????????????????91～94

Embodiment 4:

The casting solution preparation method is with implementing 1.Under 110 ℃, the casting solution hydrostomia to level and smooth, clean glass plate, is scraped on the glass plate of cleaning with scraper and to be made the thick film of 150 μ m, vacuumize 3 film gas permeability: P under the room temperature _CO2=129.8 * 10 ^-10Cm ³(STP) cm/ (cm ²ScmHg), P _N2=3.2 * 10 ^-10Cm ³(STP) cm/ (cm ²ScmHg), desired separated factor P _CO2/ P _N2=40.6.

Embodiment 5:

Except that using 3.2 gram celluloses (average degree of polymerization ≈ 600) as the raw material, other implementation step is with embodiment 4.The degree of crystallinity of prepared film is 57% (calculating according to x-ray diffraction pattern), tensile strength σ _b, fracture stretches ε _bThe long 87.1MPa, 5.4% that is respectively.

Embodiment 6:

Except that add 8.4 gram DMSO in casting solution, other implementation step is with embodiment 4.Its hygrometric state film gas permeability: P under the room temperature _CO2=147.3 * 10 ^-10Cm ³(STP) cm/ (cm ²ScmHg), P _N2=3.4 * 10 ^-10Cm ³(STP) cm/ (cm ²ScmHg), desired separated factor P _CO2/ P _N2=43.3.

Embodiment 7:

Except that using 2.5 gram celluloses (average degree of polymerization ≈ 600) as the raw material, other implementation step is with embodiment 4.The degree of crystallinity of prepared film is 57% (calculating according to x-ray diffraction pattern), tensile strength σ _b, fracture stretches ε _bThe long 76.8MPa, 5.2% that is respectively.

Embodiment 8:

3.2 gram cellulose (average degree of polymerization ≈ 1000), 0.005 gram propyl gallate adds in the MMNO solvent of the moisture 13.3wt.% of 32 grams, 80 ℃, under nitrogen protection, stir 24hr, and filter, deaeration, obtaining concentration is the 10wt.% casting solution.110 ℃ are used salivation method to be equipped with the thick film of about 150 μ m down, vacuumize under the room temperature 4 minutes, immerse gel solidification 24hr in the water-bath then, obtain the gel state film after immersing gel, after fully cleaning, room temperature, drying obtains solid-state cellulose membrane under relative humidity 90% condition.Its degree of crystallinity is 59% (calculating according to x-ray diffraction pattern), tensile strength σ _b, fracture stretches ε _bThe long 133.3MPa, 4.3% that is respectively.Its hygrometric state film gas permeability: P under the room temperature _CO2=137.4 * 10 ^-10Cm ³(STP) cm/ (cm ²ScmHg), P _N2=2.7 * 10 ^-10Cm ³(STP) cm/ (cm ²ScmHg), desired separated factor P _CO2/ P _N2=51.

Embodiment 9:

3.2 gram cellulose (average degree of polymerization ≈ 1000), 0.007 gram propyl gallate adds in the MMNO solvent of the moisture 13.3wt.% of 32 grams, 80 ℃, under nitrogen protection, stir 24hr, and filter, deaeration, obtaining concentration is the 10wt.% casting solution.110 ℃ are used salivation method to be equipped with the thick film of about 150 μ m down, vacuumize under the room temperature 4 minutes, immerse gel solidification 24hr in the water-bath then, obtain the gel state film after immersing gel, after fully cleaning, room temperature, drying obtains solid-state cellulose membrane under relative humidity 85% condition.Its hygrometric state film gas permeability: P under the room temperature _SO2=2200 * 10 ^-10Cm ³(STP) cm/ (cm ²ScmHg), P _H2S=480 * 10 ^-10Cm ³(STP) cm/ (cm ²ScmHg), desired separated factor P _SO2/ P _N2=730, P _H2S/ P _N2=160.

Embodiment 10:

The casting solution preparation method is with embodiment 1.95 ℃ are used down salivation method to be equipped with the thick film of about 150 μ m, immerse gel solidification 24hr in the aqueous isopropanol under the room temperature, obtain the gel state film after immersing gel, after fully cleaning, and room temperature, drying obtains solid-state cellulose membrane under relative humidity 85% condition.Its permeability for liquids can be as follows under the room temperature:

Pressure differential deltap P (kgcm- 2)	Flow Q * 10 5/(cm 3/cm 2·s)	To concentration 0.1wt.%, molecular weight is 67000 bovine serum albumen solution rejection
			????3	????19.4	?????????96.5
????5	????29.4	?????????98.7
			????7	????36.8	?????????99.3
????10	????51.9	?????????98.0
			????20	????70.0	?????????97.4
????30	????77.5	?????????98.0

Embodiment 11:

Except that using 2.5 gram celluloses (average degree of polymerization ≈ 1000) as the raw material, other implementation step is with embodiment 10.Its gas permeability: J under the room temperature _O2=4.2 * 10 ^-4Cm ³(STP)/(cm ²ScmHg), J _N2=4.8 * 10 ^-4Cm ³(STP)/(cm2scmHg), J ₁₁₂=10.3 * 10 ^-4Cm ³(STP)/(cm ²ScmHg).

Embodiment 12:

3.6 gram cellulose (average degree of polymerization ≈ 1000), 2.2 gram MgSO ₄, add in the MMNO solvent of the moisture 13.3wt.% of 32 grams, 80 ℃, under nitrogen protection, stir 24hr, filter, deaeration, obtaining concentration is the 11wt.% casting solution.110 ℃ are used salivation method to be equipped with the thick film of about 150 μ m down, vacuumize under the room temperature 4 minutes, immerse gel solidification 24hr in the water-bath then, obtain the gel state film after immersing gel, after fully cleaning, room temperature, drying obtains solid-state cellulose membrane under relative humidity 90% condition.Its hygrometric state film gas permeability: P under the room temperature _CO2=120.4 * 10 ^-10Cm ³(STP) cm/ (cm ²ScmHg), P _N2=2.6 * 10 ^-10Cm ³(STP) cm/ (cm ²ScmHg), desired separated factor P _CO2/ P _N2=46.3.

Embodiment 13:

3.5 gram cellulose (average degree of polymerization ≈ 1000) adds 32 grams and contains in the MMNO solvent of water 8wt.%, methyl alcohol 5wt.%, and 80 ℃, under nitrogen protection, stir 24hr, filter, deaeration, obtaining concentration is the 11wt.% casting solution.Other implementation step is with embodiment 12.The tensile strength σ of prepared film _b, fracture stretches ε _bThe long 92.7MPa, 6.7% that is respectively.

Claims (6)

1. a cellulose separation membrane is characterized in that: use N-methyl morpholine oxide as the direct dissolving cellulose of solvent and make through immersion gel method, the method may further comprise the steps: (1) Preparation of casting solution: at a temperature of 80-130°C, use one or more of MMNO with a content of 83-95wt.% and water, methanol, ethanol, isopropanol, DMF, DMAc, DMSO, NMP mixing to obtain a solvent, mixing with cellulose, stirring to dissolve, and defoaming to prepare a 5-20wt.% cellulose casting solution; (2) Drool the casting solution onto a smooth and clean glass plate, scrape a film with a certain thickness on the clean glass plate with a scraper, then put the glass plate together with the film into the coagulation bath, and soak the gel to obtain gel film; (3) After fully washing with clear water, the membrane is removed, and slowly dried at room temperature and relative humidity of 40% to 95% to obtain a solid cellulose membrane. 2. a kind of preparation method of cellulose separation membrane is characterized in that: take N-methyl morpholine oxide as the direct dissolving cellulose of solvent and make through immersion gel method, and this method comprises the following steps: (1) Preparation of casting solution: at a temperature of 80-130°C, use one or more of MMNO with a content of 83-95wt.% and water, methanol, ethanol, isopropanol, DMF, DMAc, DMSO, NMP mixing to obtain a solvent, mixing with cellulose, stirring to dissolve, and defoaming to prepare a 5-20wt.% cellulose casting solution; (2) Drool the casting solution onto a smooth and clean glass plate, scrape a film with a certain thickness on the clean glass plate with a scraper, then put the glass plate together with the film into the coagulation bath, and soak the gel to obtain gel film; (3) After fully washing with clear water, the membrane is removed, and slowly dried at room temperature and relative humidity of 40% to 95% to obtain a solid cellulose membrane. 3. according to the described cellulose separation membrane of claim 1 or 2 and preparation method thereof, it is characterized in that: an appropriate amount of oxidizing agent can also be added in the casting liquid, namely add the propyl gallate of 0.01wt.%～1wt.%, Or add 1wt.%-5wt.% of CaCl ₂ , MgCl ₂ , MgSO ₄ or NH ₄ Cl as an antioxidant. 4. The cellulose separation membrane and its preparation method according to claims 1 and 2, characterized in that: the cellulose raw material with a degree of polymerization of 500-3000 is used. 5. The cellulose separation membrane according to claim 1, characterized in that: the prepared microporous membrane, ultrafiltration membrane, nanofiltration membrane or compact membrane is used for protein solution separation, hemodialysis, sewage treatment, membrane absorption, membrane Separation and recovery of liquid mixture in extraction. 6. The cellulose separation membrane according to claim 1, characterized in that: the prepared dense cellulose membrane is used for pervaporation, gas separation process, and for carbon dioxide, sulfur dioxide, hydrogen sulfide or ammonia in acidic and alkaline gases Gas separation and recovery.

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