CN103252178A - Method for improving ion rejection rate of charged nano-filtration membrane - Google Patents
Method for improving ion rejection rate of charged nano-filtration membrane Download PDFInfo
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- CN103252178A CN103252178A CN2013102133022A CN201310213302A CN103252178A CN 103252178 A CN103252178 A CN 103252178A CN 2013102133022 A CN2013102133022 A CN 2013102133022A CN 201310213302 A CN201310213302 A CN 201310213302A CN 103252178 A CN103252178 A CN 103252178A
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Abstract
The invention discloses a chemical treatment method and particularly provides a method for improving the ion rejection rate of a charged nano-filtration membrane by using surface reaction modification. The method comprises the following steps of: compounding one separation layer on a porous supporting membrane by utilizing a water/oil two-phase interface polymerization method to prepare a nano-filtration membrane; after the separation layer is reacted, immediately carrying out reaction modification on the upper surface of the separation layer by utilizing a sulfonic acid derivative solution containing amino to obtain a modified nano-filtration membrane; and finally, rinsing unreacted objects in the modified nano-filtration membrane. The method disclosed by the invention has the advantages that under the precondition of not changing the whole formula and a pore channel structure of the nano-filtration membrane, the surface fixed charge amount and the hydrophily of the nano-filtration membrane are increased at the same time, so that the ion rejection rate of the charged nano-filtration membrane is improved and the water flux is increased.
Description
Technical field
The present invention relates to a kind of chemical treatment method, specifically refer to a kind of ion rejection that improves charged nanofiltration membrane with the method for surface reaction modification.
Technical background
NF membrane is the novel diffusion barrier of the exploitation eighties in 20th century, and its pore diameter range is (about 1nm) between reverse osmosis membrane and milipore filter, is a kind of functional pellicle that allows solvent molecule or some low molecular weight solutes or low price ion to see through.The characteristics of nanofiltration can be summarized as: to organic matter (molecular weight is greater than 200) rejection height, to the rejection height of high valence ion, adjustable to the rejection of monovalention.The application of NF membrane mainly comprises: 1, and the water demineralization of different desalting effects (seawater, surface water, underground water, bitter, industry water); 2, organic the removing of different desalting effects (dyestuff, microorganism, agricultural chemicals etc.) and concentrated (medicine, zymotic fluid).
At present, commercial NF membrane mostly with polysulphone super-filter membrane as supporting layer, carry out the interfacial polymerization of polyamine water and polynary acyl chlorides oil phase in milipore filter upper surface original position, final product is composite nanometer filtering film.Modal water monomer is piperazine, and the oil phase monomer is pyromellitic trimethylsilyl chloride.Usually the oil phase that contains the acyl chlorides molecule during interfacial polymerization is positioned at the upper surface of separating layer, and a large amount of unreacted acid chloride groups cause formed nanofiltration separation layer upper surface to contain highdensity carboxylate radical.Utilize the charge effect of carboxylic acid ion, polypiperazine-amide nanofiltration membrane has high rejection to the high price anion, and monovalent anion is had adjustable rejection.
According to the prediction of Chinese film TIA, the global film market demand will reach 27,000,000,000 dollars in 2015, and wherein Chinese market accounts for more than 10%.Relatively counter-infiltration, that nanofiltration has is cheap, the characteristics of applying flexible, and according to present trend, global NF membrane market in 2015 estimates to reach 400,000,000 dollars, and is expected to replace the part reverse osmosis membrane and uses.
Market demand NF membrane product has controlled salt rejection.Such as, in water for industrial use and desalinization preprocessing technical field, require NF membrane all higher to the rejection of various salt, thereby alleviate the load of follow-up system.The NF membrane that designs a high desalination rate (especially higher NaCl rejection) from film formulation is no doubt feasible, but will spend a large amount of time and financial resources.High monovalention rejection diffusion barrier (such as the low pressure reverse osmosis film) often causes separating layer too fine and close on physical arrangement simultaneously, has a strong impact on its water flux.
The method of patent CN102872733A trial adding m-phenylene diamine (MPD) in water polyamine system has obtained NaCl solution is had the polypiperazine-amide nanofiltration membrane (test pressure is 0.5MPa, and NaCl concentration is 500ppm) of 70% rejection.Yet for dissimilar NF membrane systems, this method does not have the positive evidence of universality.
In sum, press for a kind of pervasive, effective method, on the basis that does not reduce the nanometer filtering film water flux, improve NF membrane to the NaCl removal efficiency.
Summary of the invention
The objective of the invention is to, do not change original NF membrane physical arrangement, keeping SO
4 2-Under the prerequisite of high rejection, improve it to the NaCl removal efficiency, and improve the water flux of NF membrane simultaneously.
The present invention is achieved through the following technical solutions:
On porous support membrane, the compound one deck separating layer of the method for water/oily two-phase interface polymerization, the sulfonic acid solution of using amino-contained at once after the separating layer reaction is to separating layer upper surface reaction modifying, and is at last that the unreacted reactant rinsing in the NF membrane is clean.In the present invention, the compound one deck separating layer of the method for water/oily two-phase interface polymerization is comparatively common a kind of method in the industry.
As preferably, porous support membrane is polysulphone super-filter membrane, and polysulfones layer aperture is between 10～10
4Nm.The preparation method of porous support membrane and membrane structure there is no direct influence to result of the present invention, so the present invention has universality to various commerce or self-control milipore filter.
The water monomer can be polyamine or polyalcohol, and its composition and concentration there is no direct influence to result of the present invention, so the present invention has universality to the NF membrane of different water monomers.
The oil phase monomer must be the molecule that contains high reaction activity, is preferably the molecule that contains acid chloride groups, can be in pyromellitic trimethylsilyl chloride, m-phthaloyl chloride, paraphthaloyl chloride or the 5-isocyanates-isophthaloyl chlorine one or more.Its composition and concentration there is no direct influence to result of the present invention, so the present invention has universality to the NF membrane of different oil phase acyl chlorides monomers.
The oil phase solvent must dissolved monomer and is not caused obvious side reaction, comprises n-hexane, dodecane, normal heptane, Isopar
GDeng.The oil phase choice of Solvent there is no direct influence to result of the present invention, so the present invention has universality to the NF membrane of different oil phase solvents.
During the separating layer interfacial polymerization, the oil phase that contains the acyl chlorides molecule is positioned at the upper surface of separating layer.The mode that interfacial reaction stops is to commercially produce the heating, drying that adopts to handle.After finishing, reaction keep upper surface not contact the environment that can make acyl chlorides lose reactivity.
As preferably, the sulfonic acid of amino-contained is taurine, taurate, N-methyltaurine, methyl tauride, Homotaurine, Homotaurine salt, 2-aminopropanesulfonic acid, 2-aminopropanesulfonic acid salt, 2-aminobenzenesulfonic acid, 2-amino phenyl sulfonyl hydrochlorate, 3-aminobenzenesulfonic acid, 3-amino phenyl sulfonyl hydrochlorate, 4-aminobenzenesulfonic acid or 4-amino phenyl sulfonyl hydrochlorate.Further preferably sodium taurocholate or N-methyltaurine sodium.
As preferably, the solvent of the sulfonic acid solution of amino-contained is water, ethanol/water, methanol, dimethyl sulfoxide (DMSO)/water, N, dinethylformamide/water or N, N-dimethylacetylamide/water; Further preferably dimethyl sulfoxide (DMSO)/water (volume ratio is 1:3～1:6).
As preferably, the mass concentration of reaction modifying solution is 0.5% to saturated.More preferably 10% to saturated.
As preferably, finish time interval to the surface reaction modification less than 2 hours from the separating layer reaction; Consider actual production, more preferably 30～120 seconds.
As preferably, the mode that reaction modifying solution contacts with separating layer is immersion, single face coating, curtain coating, spray.Consider actual production, more preferably single face applies.
As preferably, the time that reaction modifying solution contacts with separating layer is greater than 10 seconds.Consider actual production, more preferably 120～300 seconds.
As preferably, the temperature that reaction modifying solution contacts with separating layer is 0～90 ℃.Consider the boiling point, high temperature of reaction modifying reaction speed, solvent to the NF membrane Effect on Performance, more preferably 25～45 ℃.
The rinsing of unreacted reactant can be with the method for commercially producing after reaction modifying was finished, and its rinsing liquid composition, rinsing temperature and rinse method there is no direct influence to result of the present invention, so the present invention has universality to different NF membrane rinse methods.
The raising method of charged nanofiltration membrane ion rejection among the present invention, namely under the prerequisite that does not change NF membrane integral formula and pore passage structure, realize strengthening surperficial fixed charge simultaneously and increase hydrophily by this method, thereby improve charged nanofiltration membrane to the rejection (mainly being anion) of ion and increase water flux.Mainly be to keep the bigger ion of hydration radius (as SO
4 2-Deng) rejection the time, further improve charged nanofiltration membrane to the less ion of hydration radius (as Cl
-Deng) rejection, and improve the water flux of NF membrane.Method is to contain the acid chloride groups molecule as the composite nanometer filtering film of monomer, after the separating layer reaction is finished, to continue with the sulfonic acid solution of amino-contained separating layer to be carried out reaction modifying.
Other beneficial effects: the present invention can effectively improve the water flux of NF membrane, and simple to operate, and processing cost is cheap, realizes at production line easily.
The specific embodiment
Below the specific embodiment of the present invention is specified:
Following examples provide the method for charged nanofiltration membrane reaction modifying, and film properties changes before and after the reaction modifying.Following embodiment only is provided as explanation and non-limiting the present invention.
Used porous support membrane is commercial polysulphone super-filter membrane in following examples, and the PS membrane date of manufacture is to testing the date less than 30 days.
Used water is the polyamine aqueous solution in following examples; Used oil phase is the alkane solution of polynary acyl chlorides.The step of two-phase interface reaction is: apply water at porous support membrane earlier, treat water stainly to apply oil phase again after drying substantially, further react and drying in baking oven at last.The sulfonic acid solution of amino-contained carries out the in-situ surface reaction modifying after the interfacial reaction.
Two main aspects of the performance evaluation of composite nanometer filtering film are salt rejection and water fluxes under certain condition, and the sulfonic acid solution of amino-contained carries out the film properties variation afterwards of in-situ surface reaction modifying.The test pressure that composite nanometer filter membrane separating property and water flux evaluation are adopted in following examples is 1.0MPa, and the concentrated stream amount is 2L/min, and environment temperature is 25 ℃, and dense water pH value is 6.5～7.5, and dense water salinity is 2000ppm.
The salt rejection is defined as the difference of dense water and the concentration of producing water divided by dense water concentration in following examples.
Water flux is defined as the aquifer yield that in above-mentioned test process unit interval sees through the unit are composite nanometer filtering film in following examples.
A kind of method that improves charged nanofiltration membrane ion rejection, on porous support membrane, the compound one deck separating layer of the method for water/oily two-phase interface polymerization prepares NF membrane, sulfonic acid solution with amino-contained carries out reaction modifying to the separating layer upper surface at once after the separating layer reaction, obtain the modification NF membrane, at last that the unreacted reactant rinsing in the modification NF membrane is clean; It is described that the separating layer upper surface is carried out reaction modifying is to contact with the sulfonic acid solution of amino-contained just reacting the NF membrane of finishing.
Embodiment 1
Modification in the last table refers to the mass concentration 10% sodium taurocholate aqueous solution different NF membrane (the used polynary acyl chlorides monomer difference of oil phase) be carried out performance comparison (25 ℃ of the reaction modifying temperature of surface reaction modification front and back composite nanometer filtering film; reaction modifying time 5min, single face applies).The result shows that for the composite nanometer filtering film of the polynary acyl chlorides of difference, after through sodium taurocholate aqueous solution surface modification, ion rejection and the water flux of composite nanometer filtering film all have certain lifting.Be example with pyromellitic trimethylsilyl chloride as the system of polynary acyl chlorides monomer, the composite nanometer filtering film after the modification rises to 86% to the rejection of NaCl by original 75%, to Na
2SO
4Rejection keep being stable at 98.5%.Simultaneously, each individual system is through also corresponding improve of its water flux after the sodium taurocholate aqueous solution surface modification.For sectional interest, the composite nanometer filtering film before the modification is to Na
2SO
4Rejection lower, through after the modification because the increase of water flux, its Na
2SO
4Also corresponding raising of rejection.
Embodiment 2
Last table is the performance comparison (single face applies for 25 ℃ of reaction modifying temperature, reaction modifying time 5min) that the sulfonic acid solution (the solute mass concentration is 10%) with different amino-containeds carries out surface reaction modification front and back composite nanometer filtering film.The result shows through the ion rejection of the composite nanometer filtering film behind the sulfonic acid solution modification of various amino-containeds and water flux all certain lifting.Under the condition of present embodiment, the effect of taurine, sodium taurocholate and N-methyltaurine sodium is better.
Embodiment 3
Last table is the performance (25 ℃ of reaction modifying temperature, reaction modifying time 5min, single face coating) of carrying out composite nanometer filtering film after the surface reaction modification with the different concentration of taurine sodium water solution.The result shows that sodium taurocholate aqueous solution mass concentration is greater than 10% best results.
Embodiment 4
Last table is the performance (reaction modifying time 5min, single face applies) with sodium taurocholate aqueous solution composite nanometer filtering film after carrying out the surface reaction modification under the different temperatures of mass concentration 10%.The result shows the best results of modification temperature between 25～45 ℃.
Embodiment 5
Last table is the performance (single face coating) of sodium taurocholate aqueous solution composite nanometer filtering film after carrying out different time surface reaction modification under 25 ℃ of mass concentration 10%.The result shows that modification time reaches stable substantially greater than 120 seconds post-modification effects.
Claims (6)
1. method that improves charged nanofiltration membrane ion rejection, it is characterized in that: on porous support membrane, the compound one deck separating layer of the method for water/oily two-phase interface polymerization prepares NF membrane, sulfonic acid solution with amino-contained carries out reaction modifying to the separating layer upper surface at once after the separating layer reaction, obtain the modification NF membrane, at last that the unreacted reactant rinsing in the modification NF membrane is clean; The method of described water/oily two-phase interface polymerization is to apply water at porous support membrane earlier, treats to apply oil phase again after water stain the drying; It is described that the separating layer upper surface is carried out reaction modifying is to contact with the sulfonic acid solution of amino-contained just reacting the NF membrane of finishing.
2. a kind of method that improves charged nanofiltration membrane ion rejection according to claim 1, it is characterized in that, described oil phase is the organic solution that contains the acid chloride groups molecule, the material that wherein contains the acid chloride groups molecule is one or more mixing in pyromellitic trimethylsilyl chloride, m-phthaloyl chloride, paraphthaloyl chloride or the 5-isocyanates-isophthaloyl chlorine, and solvent is n-hexane, dodecane, normal heptane or Isopar
GWater is that polyamine or polyalcohol are the aqueous solution of monomer; The oil phase that contains the acid chloride groups molecule during interfacial polymerization is positioned at the upper surface of separating layer.
3. a kind of method that improves charged nanofiltration membrane ion rejection according to claim 1, it is characterized in that the sulfonic acid of described amino-contained is taurine, taurate, N-methyltaurine, methyl tauride, Homotaurine, Homotaurine salt, 2-aminopropanesulfonic acid, 2-aminopropanesulfonic acid salt, 2-aminobenzenesulfonic acid, 2-amino phenyl sulfonyl hydrochlorate, 3-aminobenzenesulfonic acid, 3-amino phenyl sulfonyl hydrochlorate, 4-aminobenzenesulfonic acid or 4-amino phenyl sulfonyl hydrochlorate; Solvent in the sulfonic acid solution of amino-contained is water, ethanol/water, methanol, dimethyl sulfoxide (DMSO)/water, N, dinethylformamide/water or N, N-dimethylacetylamide/water; The mass concentration of solute is 0.5% to saturated in the sulfonic acid solution of amino-contained.
4. a kind of method that improves charged nanofiltration membrane ion rejection according to claim 3 is characterized in that, the sulfonic acid of described amino-contained is sodium taurocholate or N-methyltaurine sodium; Solvent is dimethyl sulfoxide (DMSO)/water in the sulfonic acid solution of amino-contained, and its volume ratio is 1:3～1:6; The solute mass concentration is 10% to saturated in the sulfonic acid solution of amino-contained.
5. a kind of method that improves charged nanofiltration membrane ion rejection according to claim 1 is characterized in that, finishes time interval to the surface reaction modification less than 2 hours from separating layer reaction; The mode of contact is immersion, single face coating, curtain coating or spray; The time of contact was greater than 10 seconds; The contact temperature of surface reaction modification is 0～90 ℃.
6. a kind of method that improves charged nanofiltration membrane ion rejection according to claim 5 is characterized in that, from separating layer reaction finish to the time interval of surface reaction modification be 30～120 seconds; The mode of contact is that single face applies; The time of contact is 120～300 seconds; The contact temperature of surface reaction modification is 25～45 ℃.
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| CN113244794A (en) * | 2021-05-11 | 2021-08-13 | 燕山大学 | Preparation method of nanofiltration membrane for intercepting nitrate and resource utilization of concentrated solution |
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Application publication date: 20130821 |