CN103396574A - Preparation method of bipolar membrane - Google Patents

Abstract

The invention discloses a preparation method of a bipolar membrane. The preparation method of the bipolar membrane is characterized by comprising the following steps of: (1), preparing a PAMPSLi membrane solution; (2), preparing a PAMPSLi-SA membrane; and (3), preparing a PAMPSLi-SA/mCS bipolar membrane. The preparation method of the bipolar membrane disclosed by the invention is simple and convenient to operate. The bipolar membrane which is obtained by the preparation method disclosed by the invention has the characteristics of being small in membrane impedance, low in working voltage, large in working current density, high in hydrolytic dissociation efficiency, high in ion permeability and the like.

Description

The preparation method of Bipolar Membrane

Technical field

The invention belongs to the solid electrolyte material field, specifically, relate to a kind of preparation method of Bipolar Membrane.

Background technology

Bipolar Membrane (BPM) normally is composited by anionresin layer, cationic exchange layer, is reaction film truly.Under the DC electric field effect, Bipolar Membrane can, by the water decomposition in its middle layer, obtain respectively hydrogen ion and hydroxide ion at anode membrane and cavity block both sides.In recent years, BPM technology and application thereof have obtained rapidly development, aspect the preparation of Organic Acid and Base and recovery, environmental improvement, all are being widely used.How to promote Bipolar Membrane intermediate layer water decomposition, improve water decomposition efficiency, thereby reduction Bipolar Membrane resistance drop and bath voltage have become the focus of current Bipolar Membrane research.

Ionogen base material-solid polymer electrolyte (SPE) as Bipolar Membrane research and comparison hot topic, claim again the ionophore polymkeric substance, being to be composited by polymer main body thing and metal-salt two portions, is a kind of novel solid electrolyte that develops rapidly in recent years.From the seventies, find that first polyoxyethylene (PEO) and an alkali metal salt complex compound have ionic conductivity, an alkali metal salt complex compound ionic conductance in the time of 40-60 ℃ of studying and drawn PEO in 1979 reaches 10 ^-5After S/cm, people are devoted to improve the research of polymer dielectric performance, and it is widely used in to space technology, electronics, photoelectricity, sensor aspect.

And study at present the most widely the polymer dielectric base material mainly contain PMMA, PAN, PVdF and PEO, but mechanical property and chemical property are difficult to reach practical requirement, membrane impedance is large, water decomposition efficiency is low, the iontophoretic injection performance is poor.

The shortcoming of prior art: the Bipolar Membrane impedance is large, ion transmission efficiency is little, water decomposition efficiency is low.

Summary of the invention

For solving above technical problem, the object of the present invention is to provide the preparation method of the Bipolar Membrane that a kind of membrane impedance is little, ion transmission efficiency is high, water decomposition efficiency is high.

Sodium alginate (SA) has good biological degradability, is a kind of environment-friendly polymers.Carry out after modification as Bipolar Membrane anode membrane layer material sodium alginate in laboratory, and experiment shows, after modification, the sodium alginate film has good mechanical property and chemical property.

2-acrylamide-2-methyl propane sulfonic (AMPS) is the acrylamide alkyl sulfonic acid derivative, its structural formula as shown in Figure 1, strong anionic property in molecule, water miscible sulfonic acid group make it have electroconductibility and wetting ability, have given simultaneously the high characteristic of good conductivity, wetting ability of its polymkeric substance.The present invention has synthesized poly-(2-acrylamide-2-methyl propane sulfonic lithium) (PAMPSLi) with water solution polymerization process, with after the SA blend, adopting casting method, has prepared the PAMPSLi-mSA/mCS Bipolar Membrane.2-acrylamide-2-methyl propane sulfonic (AMPS) structural formula is as follows:

And the present invention seeks to realize like this: a kind of preparation method of Bipolar Membrane, its key is to comprise the following steps:

(1) preparation of PAMPSLi film liquid: sodium alginate soln (SA) and polyvinyl alcohol (PVA) blend are made to PVA-SA colloidal sol, PAMPSLi is joined in described PVA-SA colloidal sol, stir, vacuum deaerator, obtain the PAMPSLi film liquid of thickness, the ratio of the amount of substance of described sodium alginate, polyvinyl alcohol and the PAMPSLi that wherein adds is 1:1:1;

(2) preparation of PAMPSLi-SA film: by described PAMPSLi film liquid curtain coating in smooth culture dish, at room temperature air-dry film forming, then soak crosslinked 30min by described air-dry film in ferric chloride Solution, cleaner with distilled water flushing, natural air drying, obtain the PAMPSLi-SA film;

(3) preparation of PAMPSLi-SA/mCS Bipolar Membrane: slowly drip while stirring glutaraldehyde solution in the chitosan acetic acid aqueous solution, the while vacuum deaerator, until viscous fluid occurs, and by this viscous fluid curtain coating on described PAMPSLi-SA film, at room temperature air-dry, make the PAMPSLi-SA/mCS Bipolar Membrane.

The massfraction of above-mentioned PAMPSLi is 2%-4%.

The massfraction of above-mentioned sodium alginate soln is 3%; The massfraction of described polyvinyl alcohol is 6%; The massfraction of described ferric chloride Solution is 8.0%; The massfraction of described chitosan acetic acid aqueous solution is 3%; The volume fraction of described glutaraldehyde solution is 0.25%.

Above-mentioned massfraction is that 3% chitosan acetic acid solution is that to be dissolved in massfraction be that 2% acetic acid aqueous solution preparation obtains to chitosan (CS).

Beneficial effect:

The preparation method of a kind of Bipolar Membrane of the present invention, simple to operation, the Bipolar Membrane for preparing has that membrane impedance is little, operating voltage is low, working current density is large, water decomposition efficiency is high, the ion permeability high.

The accompanying drawing explanation

Fig. 1 is the Cross Section Morphology figure of PAMPSLi-SA/mCS Bipolar Membrane;

Fig. 2 is the graphic representation of Bipolar Membrane swelling capacity in acid solution;

Fig. 3 is the H of different films ⁺The graphic representation of penetrating quality;

Fig. 4 is the current-voltage curve figure of Bipolar Membrane.

Embodiment

Embodiment:

One, the preparation of Bipolar Membrane:

(1) preparation of PAMPSLi film liquid: be that 3% sodium alginate soln and massfraction are that 6% polyvinyl alcohol blending makes PVA-SA colloidal sol by massfraction, by massfraction, be respectively that 2% and 4% PAMPSLi joins in described PVA-SA colloidal sol, stir, vacuum deaerator, obtain the PAMPSLi film liquid of thickness, the ratio of the amount of substance of described sodium alginate, polyvinyl alcohol and the PAMPSLi that wherein adds is 1:1:1;

(2) preparation of PAMPSLi-SA film: by described PAMPSLi film liquid curtain coating in smooth culture dish, air-dry film forming at room temperature, then described air-dry film in being 8.0% ferric chloride Solution, massfraction is soaked to crosslinked 30min, clean with distilled water flushing again, natural air drying, obtain 2%PAMPSLi-SA film and 4%PAMPSLi-SA film;

(3) preparation of PAMPSLi-SA/mCS Bipolar Membrane: it is that to obtain massfraction be 3% chitosan acetic acid solution to the preparation of 2% acetic acid aqueous solution that chitosan is dissolved in to massfraction, to slowly dripping while stirring volume fraction during massfraction is 3% chitosan acetic acid aqueous solution, be 0.25% glutaraldehyde solution again, the while vacuum deaerator, until viscous fluid occurs, then by this viscous fluid curtain coating on described 2%PAMPSLi-SA film and 4%PAMPSLi-SA film, at room temperature air-dry, make 2%PAMPSLi-SA/mCS and 4%PAMPSLi-SA/mCS Bipolar Membrane.

The Cross Section Morphology of PAMPSLi-SA/mCS Bipolar Membrane as shown in Figure 1, is double-layer structure by figure PAMPSLi-SA/mCS Bipolar Membrane, and layering is obvious, upper strata is the PAMPSLi-SA film, lower floor is the mCS film, and two retes are in conjunction with closely, and interlayer is seamless and the appearance such as tiny bubble.The intermediate interface layer thickness of film is nanometer scale.

Two, the mensuration of PAMPSLi-SA film loading capacity

(1) measuring method:

By film immersion to be measured in distilled water 24 hours, make it to reach swelling equilibrium, take out, then be immersed in the HC1 solution of 1mol/L, make it to transfer to Hydrogen:

R-Na+HCl→R-H+NaCl (1)

In formula, R represents the skeleton group of film.

Take out membrane sample, be washed with distilled water to neutrality, then with filter paper, carefully suck the moisture of film surface attachment, the quality of accurate weighing membrane sample, obtain the weight in wet base (W of film _wet), be placed in the weighing bottle of constant weight, to put into 100 ℃ of baking ovens and be dried to constant weight, the quality of weighing film, obtain the dry weight (W of film _dry), its water ratio (h) can be calculated as follows:

η=[(W _wet-W _dry)/W _wet]×100% (2)

In formula: η----water ratio (%); W _wet---the weight in wet base (g) of-film; W _dry---the dry weight (g) of-film.

The membrane sample of Hydrogen will be converted to, with filter paper, suck the moisture of film surface attachment, (W) accurately weighs, be placed in the Erlenmeyer flask with grinding port plug of 250mL drying, with 100mL0.1mol/L NaOH standardized solution soaked overnight, get the 10mL steeping fluid, with the HC1 standardized solution titration (take phenolphthalein as indicator) of 0.1mol/L, the total ion exchange capacity IEC of anode membrane can calculate by (3) formula:

$\mathrm{IEC}=\frac{C_{\mathrm{NaOH}}\×10-C_{\mathrm{HCl}}\×V_{\mathrm{HCl}}}{W(1-\mathrm{\η})}\×10---\left(3\right)$

In formula, the total ion exchange capacity of IEC----4%PAMPSLi-SA film (mmol/g); The weight in wet base of W----film (g); The water ratio of η----film (%); C _NaOH, C _HClBe respectively the concentration (mol/L) of NaOH, HCl standardized solution; V _HCl---the titration volume (mL) of-HCl standardized solution.

(2) measurement result: water ratio and the loading capacity of the film that shows as following table 1

The water ratio of table 1 film and loading capacity

Interpretation of result: after adding PAMPSLi, the water ratio of SA film descends, and loading capacity improves.This be due to PAMPSLi contain many hydrophilic-SO ^3-The Li of group and some amount ⁺Thereby, improved wetting ability, water ratio and the loading capacity of SA film.

Three, the mensuration of PAMPSLi-SA/mCS Bipolar Membrane swelling capacity:

(1) measuring method:

With dried wet film weighting method, measure the swelling capacity of Bipolar Membrane: accurately take Bipolar Membrane sample (W ₀), being impregnated in acid solution, hold over night, make its abundant swelling, reaches swelling equilibrium, takes out, and with filter paper, sucks rapidly the moisture of film surface attachment, the weight in wet base of weighing Bipolar Membrane (W), Bipolar Membrane swelling capacity D in acid _SCan calculate by formula (4):

D _s=[(W-W ₀)/W ₀]×100% （4）

(2) result: Bipolar Membrane swelling capacity in the acid solution of different concns changes as shown in Figure 2.As can be seen from Figure 2, the swelling property of PAMPSLi-mSA/mCS BPM is less, H+ concentration lower than the acid solution of 8mol/L in swelling capacity less than 75%, thereby guarantee the stability of its film size and interlayer structure in acid system.

The swelling capacity of Bipolar Membrane increases along with the increase of H+ concentration, and the H+ ion of solution middle and high concentration can make Bipolar Membrane dissociate more hydrophilic radical, as-NH ₂,-COO-,-OH ,-SO ₃H etc., increased widely the quantity of hydrophilic radical in the film, weakened the interaction between macromolecular chain, in film, amorphous phase increases, the reactivity of segment strengthens, and the charged group on molecular chain is unfolded more because the two like magnetic poles repel each other effect becomes molecular chain, thereby has larger free volume, and the swelling capacity of film is increased.

Four, the mensuration of PAMPSLi-SA film hydrogen ion penetrating quality

(1) measuring method: using respectively 2%PAMPSLi-SA film, 4%PAMPSLi-SA film and SA film as the barrier film between anolyte compartment and cathode compartment, using lead electrode as negative electrode and the anode of electric groove, anolyte is the H of 0.5mol/L ₂SO ₄Solution, catholyte are the Na of 1mol/L ₂SO ₄Solution, volume is 200mL, and as power supply, current density is 10mA/cm with galvanostat ², H is carried out in energising ⁺The penetrating quality determination experiment of ion, H in cathode compartment of 10min mensuration ⁺The concentration of ion (take phenolphthalein as indicator, with the NaOH standardized solution titration of 0.01mol/L).

(2) result: the increase of measuring along with the PAMPSLi that adds in the SA film as shown in Figure 3, the H of film ⁺Penetrating quality also increases gradually.This be due in PAMPSLi, contain many hydrophilic-SO ^3-Group and Li ⁺Ion, after adding PAMPSLi, the loading capacity of SA film is improved, H ⁺Ion also obviously improves by the transmitance of PAMPSLi-SA film.

Five, the mensuration of the bath voltage of PAMPSLi-SA/mCS Bipolar Membrane and current density relation curve

(1) measuring method:

Using the barrier film of Bipolar Membrane to be measured (2%PAMPSLi-SA/mCS Bipolar Membrane, 4%PAMPSLi-SA/mCS Bipolar Membrane) between cathode compartment and anolyte compartment, 1mol/L Na is injected respectively in chamber in yin, yang the two poles of the earth ₂SO ₄Solution 250mL, (apparent electrode area is as 2cm as yin, yang the two poles of the earth take lead ²), use galvanostat, measure the variation relation of yin, yang two interpolar bath voltages with current density.Under the same conditions, measure between chamber, yin, yang the two poles of the earth without the bath voltage in the barrier film situation and current density relation curve.Under certain current density, the difference that has or not yin, yang two interpolar bath voltages in the barrier film situation that records reduces.

(2) result:

As shown in Fig. 4 and table 2, as shown in Figure 4: the operating voltage of negative and positive two interpolar electrolyzers increases along with the increase of current density.The operating voltage of electrolyzer order from small to large is 4%PAMPSLi-SA/mCS Bipolar Membrane<2%PAMPSLi-SA/mCS Bipolar Membrane.When current density is 30mAcm ^-1The time, 4%PAMPSLi-mSA/mCS BPM is only 4.8V.

As shown in Table 2: when the addition of PAMPSLi is 4%, current density is 105mAcm ^-1The time, the IR of PAMPSLi-SA/mCS BPM falls and only is 2.0V.Visible, PAMPSLi adds in the SA film can obviously reduce the membrane impedance of Bipolar Membrane, thereby the IR that has reduced Bipolar Membrane falls and bath voltage, has improved the working efficiency of electric groove.

Under the different current densities of table 2, the IR of different Bipolar Membrane falls

Six, sum up

In sum: will gather (2-acrylamide-2-methyl propane sulfonic lithium) and prepare the PAMPSLi-SA/mCS Bipolar Membrane with the SA blend, and characterize with the Bipolar Membrane of the methods such as scanning electron microscope to preparation.Experimental result shows, after in the SA film, adding PAMPSLi, and the loading capacity of film and H ⁺Ion transmission increases, and when the addition of PAMPSLi is 4%, current density is 105mAcm ^-1The time, the IR of PAMPSLi-mSA/mCS BPM falls and only is 2.0V, and membrane impedance is reduced greatly.

Claims (4)

1. the preparation method of a Bipolar Membrane is characterized in that comprising the following steps:

(1) preparation of PAMPSLi film liquid: sodium alginate soln and polyvinyl alcohol blending are made to PVA-SA colloidal sol, PAMPSLi is joined in described PVA-SA colloidal sol, stir, vacuum deaerator, obtain the PAMPSLi film liquid of thickness, the ratio of the amount of substance of described sodium alginate, polyvinyl alcohol and the PAMPSLi that wherein adds is 1:1:1;

(2) preparation of PAMPSLi-SA film: by described PAMPSLi film liquid curtain coating in smooth culture dish, at room temperature air-dry film forming, then soak crosslinked 30min by this air-dry film in ferric chloride Solution, cleaner with distilled water flushing, natural air drying, obtain the PAMPSLi-SA film;

(3) preparation of PAMPSLi-SA/mCS Bipolar Membrane: slowly drip while stirring glutaraldehyde solution in the chitosan acetic acid aqueous solution, the while vacuum deaerator, until viscous fluid occurs, and by this viscous fluid curtain coating on described PAMPSLi-SA film, at room temperature air-dry, make the PAMPSLi-SA/mCS Bipolar Membrane.

2. the preparation method of Bipolar Membrane according to claim 1, it is characterized in that: the massfraction of described PAMPSLi is 2%-4%.

3. the preparation method of described Bipolar Membrane according to claim 1 and 2, it is characterized in that: the massfraction of described sodium alginate soln is 3%; The massfraction of described polyvinyl alcohol is 6%; The massfraction of described ferric chloride Solution is 8.0%; The massfraction of described chitosan acetic acid aqueous solution is 3%; The volume fraction of described glutaraldehyde solution is 0.25%.

4. the preparation method of Bipolar Membrane according to claim 3 is characterized in that: described massfraction is that 3% chitosan acetic acid solution is that to be dissolved in massfraction be that 2% acetic acid aqueous solution preparation obtains to chitosan.

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