CN104874300A - Chitosan-sulfonated carbon molecular sieve hybrid composite membrane and preparation and application - Google Patents

Abstract

The invention discloses a chitosan-sulfonated carbon molecular sieve hybrid composite membrane. The separation layer is composed of chitosan and sulfonated carbon molecular sieve blended, and the support layer is a porous polymer ultrafiltration membrane. The preparation process of the hybrid composite membrane includes: first, using SBA-15 molecular sieve as a hard template and sucrose as a filler, carbon molecular sieves are synthesized through steps such as roasting, carbonization, and template removal, and then sulfonated in concentrated sulfuric acid solution to prepare sulfonated Carbon molecular sieve; blend the obtained sulfonated carbon molecular sieve with chitosan solution, and stir evenly; add glutaraldehyde for cross-linking reaction; filter and stand for defoaming to obtain a casting solution, which is spin-coated on a polyacrylonitrile ultrafiltration membrane Above, the chitosan/sulfonated carbon molecular composite film was obtained after drying. The invention has the advantages that the preparation process is simple and the raw materials are easy to obtain, and the chitosan-sulfonated carbon molecular sieve hybrid composite membrane of the invention is used for acetone/water liquid separation, showing better flux and separation factor.

Description

Chitosan-sulfonated carbon molecular sieve hybrid composite membrane and its preparation and application

technical field

The invention relates to the preparation and application of a chitosan-sulfonated carbon molecular sieve hybrid composite membrane, which belongs to the technical field of membrane separation.

Background technique

As a widely used organic solvent and production raw material, acetone often has different degrees of water in the production and preparation process, and dehydration purification is a necessary step; at the same time, water is often generated in the reaction in which acetone participates, so the side effects are removed during the reaction. The product water breaks the reaction balance and promotes the reaction. In addition, the dehydration and recovery of the used acetone has important environmental and economic significance. Compared with other traditional dehydration methods, pervaporation technology has the advantages of simple operation, high product purity, small loss of raw materials, no pollution in the process, low energy consumption, and easy coupling. It has obvious technical and economic advantages in production. However, due to the trade-off effect of polymer materials, that is, the flux and selectivity of the membrane increase and decrease, in order to increase the flux and selectivity of the membrane at the same time, increase the hydrophilicity of the membrane and strengthen the water molecules The transfer is the main means to solve its problems. Constructing channels with hydrophilic sites in the membrane can not only increase the water selectivity but also construct channels for the transfer of water molecules. In nature, aquaporin (AQP) is the main way for water to flow in and out of cells, and it is a water-specific channel protein. The study found that the specific selectivity of AQP to water is related to its structure. AQP1 is one of the aquaporins. In addition to the sieving function of the channel orifice, which only allows molecules of the size of water molecules to pass through, the hydrophobic nodes and the minimum hydrophilic sites in the protein channel pipeline allow water molecules to pass through the entire pipeline. The energy barrier is greatly reduced, which promotes the transfer of water molecules.

Inspired by the structure of biological aquaporins, except for the sulfonated site -SO ₃ ^2- in the sulfonated carbon molecular sieve, which is hydrophilic, the rest are hydrophobic and have a two-dimensional structure, forming a straight channel . Doping sulfonated carbon molecular sieves in the membrane constructs hydrophobic channels with hydrophilic sites, uses the sulfonate groups in the channels to improve water selectivity, and uses the hydrophobicity of the channels to reduce the energy barrier of water transfer, thereby improving the membrane performance at the same time. throughput and separation performance.

Contents of the invention

The purpose of the present invention is to provide a chitosan-sulfonated carbon molecular sieve hybrid composite membrane preparation and application. The liquid separation composite membrane prepared by this method is used to separate the mixed solution of acetone and water. The hydrophilicity of the sulfonate group in the sulfonated carbon molecular sieve is used to improve the water selectivity of the membrane, and the hydrophobic channel of the carbon molecular sieve is used to reduce the water transfer rate. Energy barrier to improve water flux. The preparation method is simple and easy to operate, and the inorganic particles are uniformly dispersed in the membrane after ultrasonication, has high thermal stability and mechanical properties, and has important research value in improving the hydrophilicity and strong stability of the organic-inorganic composite membrane. The membrane material that this method makes is used for the pervaporation dehydration of acetone-water mixed system, relatively pure chitosan membrane, because the hydrophilicity of the sulfonate group in the sulfonated carbon molecular sieve and capillary adsorption in the composite membrane have higher Flux and Separation Factors.

The present invention is achieved through the following technical scheme, a chitosan-sulfonated carbon molecular sieve hybrid composite membrane, the hybrid composite membrane uses a porous polymer ultrafiltration membrane as a support layer, and uses chitosan and sulfonated carbon The molecular sieve hybrid membrane is the separation layer, and the mass ratio of chitosan and sulfonated carbon molecular sieve is 100:0.5~6. Among them, the sulfonated carbon molecular sieve uses SBA-15 molecular sieve as the template agent and sucrose as the filler. Prepared by calcination, detemplate and sulfonation steps.

The preparation of above-mentioned chitosan-sulfonated carbon molecular sieve hybrid composite membrane comprises the following steps:

Step 1. Preparation of carbon molecular sieve material: using SBA-15 molecular sieve as a hard template, immerse SBA-15 molecular sieve in a solution containing sucrose, 98wt% concentrated sulfuric acid and purified water for casting, wherein, SBA-15 molecular sieve and sucrose The mass ratio of sucrose and 98wt% concentrated sulfuric acid is 1:1.5～2, the mass ratio of sucrose and 98wt% concentrated sulfuric acid is 1:7～10, let stand for 5 hours, dry at 373K for 4 hours, roast at 433K for 6 hours, carry out pre-carbonization to obtain carbonization SBA-15 sample A; then the carbonized SBA-15 sample A made is placed in sucrose, H ₂ SO ₄ and purified water solution for secondary casting, wherein the mass ratio of SBA-15 molecular sieve and sucrose is 1: 0.5～1, the mass ratio of the concentrated sulfuric acid of sucrose and 98wt% is 1:7～10, stand for 5 hours; Roast 5-8 hours at 673-973K under nitrogen protection, obtain carbonized SBA-15 sample B; Will Gained carbonized SBA-15 sample B was dissolved in 40% hydrofluoric acid solution to remove the _SiO2 hard template to obtain a carbon molecular sieve material;

Step 2. Preparation of sulfonated carbon molecular sieve: put the carbon molecular sieve material obtained in step 1 into a stainless steel reaction kettle filled with concentrated sulfuric acid, sulfonate at 120-180°C for 2-8 hours, and use the obtained mixture after sulfonation Suction filtration with deionized water, washing until the filtrate is neutral, and drying to obtain sulfonated carbon molecular sieves;

Step 3, preparing chitosan-sulfonated carbon molecular sieve hybrid composite membrane: using a blending method, stirring a certain mass of sulfonated carbon molecular sieve prepared in step 2 in deionized water for 12 hours, ultrasonicating for 3 to 5 hours, and the cells Crushed for 1 hour, poured into a flask, and then added a certain mass of chitosan with a viscosity of 400mPa·s and a degree of deacetylation of 90.2%, so that the content of chitosan was 2wt%, and the mass of chitosan and sulfonated carbon molecular sieve The ratio is 100:0.5～6, dropwise add a certain amount of acetic acid, so that the content of acetic acid in the solution is 2wt%, stir at room temperature for 6 hours, and then add a certain amount of 2.5wt% glutaraldehyde, so that the unit structure of chitosan The molar ratio of the unit structure to glutaraldehyde is 100:4; cross-link at 30°C for 2 hours to obtain the casting solution; let the casting solution stand still, defoam, spin-coat on the polyacrylonitrile ultrafiltration membrane, and dry at room temperature After 24 hours, the chitosan-sulfonated carbon molecular sieve hybrid composite membrane was prepared.

The above-prepared chitosan-sulfonated carbon molecular sieve hybrid composite membrane is used to separate the mixed solution of acetone and water, the flux is 1.24-1.81kg/m ² h, and the separation factor is 426-832.

The advantages of the present invention are: the preparation process is simple and controllable, the raw materials are easy to obtain, and the conditions are mild, and the prepared chitosan-sulfonated carbon molecular sieve hybrid composite membrane is used for body separation of acetone/water mixed solution, and the affinity of sulfonate is used to Water-based to improve the water selectivity of the membrane, the hydrophobic pores of carbon molecular sieves are used to reduce the energy barrier of water transfer and improve the water flux. The composite membrane has higher flux and selectivity.

Description of drawings

Fig. 1 is the comparative figure of permeate flux and separation factor of membrane in embodiment and comparative example;

Fig. 2 is the SEM surface figure of the chitosan-sulfonated carbon molecular sieve hybrid composite membrane (membrane 1) that embodiment 1 makes;

Fig. 3 is the SEM surface figure of the chitosan-sulfonated carbon molecular sieve hybrid composite membrane (membrane 2) that embodiment 2 makes;

Fig. 4 is the SEM surface figure of the chitosan-sulfonated carbon molecular sieve hybrid composite membrane (membrane 3) that embodiment 3 makes;

Fig. 5 is the SEM surface figure of the chitosan-sulfonated carbon molecular sieve hybrid composite membrane (membrane 4) that embodiment 4 makes;

Fig. 6 is the SEM surface view of the chitosan composite film (film 5) that comparative example 1 makes.

Detailed ways

The details of the present invention are described below through the examples, and the examples are provided for the convenience of understanding, and are by no means limiting the present invention.

Embodiment 1, prepare chitosan-sulfonated carbon molecular sieve hybrid composite membrane, the steps are as follows:

Preparation of sulfonated carbon molecular sieves: with calcined SBA-15 as a hard template, immerse 1.0g of SBA- ₁₅ in a solution containing 1.25g of sucrose, 0.14g of _H2SO4 and 5g of pure water, and then It was dried at 373K and fired at 433K for 6 hours. Then place the prepared carbon-containing silica in 0.8g sucrose, 90mgH ₂ SO ₄ and 5.0g pure water, heat at 873K for 6 hours under the protection of nitrogen, dissolve it in 40wt.% HF to remove SiO ₂ The hard template was washed with pure water and suction filtered until the filtrate was neutral, and the sample was dried to obtain a carbon molecular sieve. The carbon molecular sieve sample was soaked in 98wt.% concentrated H ₂ SO ₄ solution, hydrothermally treated at 160°C for 6 hours, and the final sample was washed, suction filtered and dried to produce a sulfonated carbon molecular sieve.

Weigh 0.01 g of the prepared sulfonated carbon molecular sieve and dissolve it in 100 ml of deionized water, stir for 12 hours, ultrasonicate for 3 hours, and break the cells for 1 hour. Sugar is added in the above-mentioned mixed solution, makes chitosan content be 2wt%, and the mass ratio of chitosan and sulfonated carbon molecular sieve is 100:0.5, drips the acetic acid solution that 2ml mass fraction is 99.5wt%, makes acetic acid in the solution content of 2wt%, stirring at room temperature for 6h, and then adding 2ml of glutaraldehyde with a mass fraction of 2.5wt%, wherein the molar ratio of the unit structure of chitosan to the unit structure of glutaraldehyde is 100:4, at 30 ° C After 2 hours, the casting solution was left to stand, defoamed, spin-coated on a polyacrylonitrile ultrafiltration membrane, and dried at room temperature for 24 hours to prepare a chitosan-sulfonated carbon molecular sieve hybrid composite membrane (membrane 1). Figure 2 is the SEM surface image of the membrane 1; the hybrid composite membrane is used for pervaporation dehydration in acetone-water mixed system, the permeation flux is 1.24kg/m ² h, and the separation factor is 493.

Embodiment 2, prepare chitosan-sulfonated carbon molecular sieve hybrid composite membrane, the steps are as follows:

The preparation method is basically the same as in Example 1, except that the amount of sulfonated carbon molecular sieve is changed from 0.01g to 0.04g, and the mass ratio of chitosan and sulfonated carbon molecular sieve is 100:2, and finally the shell Polysaccharide-sulfonated carbon molecular sieve hybrid composite membrane (membrane 2), Fig. 3 is the SEM surface figure of this membrane 2; This hybrid composite membrane (membrane 2) is used to separate the acetone-water mixture that water content is 5wt% solution, the permeation flux is 1.71kg/m ² h, and the separation factor is 832.

Embodiment 3, prepare chitosan-sulfonated carbon molecular sieve hybrid composite membrane, the steps are as follows:

The preparation method is basically the same as in Example 1, except that the amount of sulfonated carbon molecular sieve is changed from 0.01g to 0.08g, and the mass ratio of chitosan and sulfonated carbon molecular sieve is 100:4, and finally the shell Polysaccharide-sulfonated carbon molecular sieve hybrid composite membrane (membrane 3), Fig. 4 is the SEM surface figure of this membrane 3; This hybrid composite membrane (membrane 3) is used to separate the acetone-water mixture that water content is 5wt% Solution, the permeation flux is 1.66kg/m ² h, and the separation factor is 710.

Embodiment 4, prepare chitosan-sulfonated carbon molecular sieve hybrid composite membrane, the steps are as follows:

The preparation method is basically the same as in Example 1, except that the amount of sulfonated carbon molecular sieve is changed from 0.01g to 0.12g, and the mass ratio of chitosan and sulfonated carbon molecular sieve is 100:6, and finally the shell Polysaccharide-sulfonated carbon molecular sieve hybrid composite membrane (membrane 4), Fig. 5 is the SEM surface figure of this membrane 4; This hybrid composite membrane (membrane 4) is used to separate the acetone-water mixture that water content is 5wt% Solution, its permeation flux is 1.81kg/m ² h, separation factor is 426.

Comparative example 1, prepare chitosan composite film, the steps are as follows:

2g viscosity is 400mPa · s and the chitosan of degree of deacetylation 90.2% is dissolved in the acetic acid solution that mass concentration is 2wt% at normal temperature, and stirring 6 hours is mixed with the chitosan solution that mass concentration is 2wt%, then Add 2ml mass fraction and be 2.5wt% glutaraldehyde, wherein the unit structure molar ratio of the unit domain glutaraldehyde of chitosan is 100:4, 30 ℃ of cross-linking 2 hours, casting solution is left standstill, except foam, spin-coated on polyacrylonitrile ultrafiltration membrane, and dried at room temperature for 24h to finally make a chitosan composite membrane (membrane 5). The mixed system is dehydrated by pervaporation, the permeation flux is 1.08kg/m ² h, and the separation factor is 484.

In summary, the process of preparing the chitosan-sulfonated carbon molecular sieve hybrid composite membrane is simple, the raw materials are easy to obtain, and the structure is controllable. The prepared chitosan-sulfonated carbon molecular sieve hybrid composite membrane is used for acetone/water mixture Pervaporation dehydration has higher separation performance, and Fig. 1 is a comparative diagram of the permeation flux and separation factor of the membranes in each embodiment and Comparative Example 1. The performance of the chitosan-sulfonated carbon molecular sieve hybrid composite membrane prepared in Example 2 was the best. Compared with the chitosan composite membrane in Comparative Example 1, the flux was increased by 1.58 times, and the separation factor was increased by 1.72 times.

In addition, there is no specific description for the support layer being a polysulfone ultrafiltration membrane, or a sulfonated polysulfone ultrafiltration membrane, or a polyethersulfone ultrafiltration membrane or a polyimide ultrafiltration membrane, because no matter The choice of which of the above specific ultrafiltration membranes has no substantial effect on the performance of the final product.

Although the present invention has been described above in conjunction with the drawings, the present invention is not limited to the above-mentioned specific embodiments, and the above-mentioned specific embodiments are only illustrative, rather than restrictive. Under the inspiration, many modifications can be made without departing from the gist of the present invention, and these all belong to the protection of the present invention.

Claims (4)

1. shitosan-sulfonation carbon molecular sieve hybridization compounding film, it is characterized in that, this hybridization compounding film is using the polymer ultrafiltration membrane of porous as supporting layer, with shitosan and sulfonation carbon molecular sieve hybridized film for separating layer, the mass ratio of shitosan and sulfonation carbon molecular sieve is 100:0.5 ~ 6, and wherein, sulfonation carbon molecular sieve is for template with SBA-15 molecular sieve, take sucrose as filler, mainly through roasting, go template and sulfonation procedure to be prepared from.

2. shitosan-sulfonation carbon molecular sieve hybridization compounding film according to claim 1, it is characterized in that, described supporting layer is the one in polyacrylonitrile ultrafiltration film, polysulphone super-filter membrane, Sulfonated Polysulfone UF Membranes, poly (ether-sulfone) ultrafiltration membrane and polyimides milipore filter, and molecular cut off is 100,000.

3., by a preparation method for shitosan-sulfonation carbon molecular sieve hybridization compounding film described in claim 1, it is characterized in that, comprise the following steps:

Step 1, preparation carbon molecular sieve material: with SBA-15 molecular sieve for hard template, the leaching of SBA-15 molecular sieve is put and casts in the solution of the concentrated sulfuric acid containing sucrose, 98wt% and pure water, wherein, the mass ratio of SBA-15 molecular sieve and sucrose is 1:1.5 ~ 2, the mass ratio of the concentrated sulfuric acid of sucrose and 98wt% is 1:7 ~ 10, leaves standstill 5 hours, drying 4 hours under 373K, roasting 6 hours under 433K, carries out pre-carbonization and obtains carbonization SBA-15 sample A; Again obtained carbonization SBA-15 sample A is placed in sucrose, H ₂sO ₄carry out second casting with in the solution of pure water, wherein, the mass ratio of SBA-15 molecular sieve and sucrose is 1:0.5 ~ 1, and the mass ratio of the concentrated sulfuric acid of sucrose and 98wt% is 1:7 ~ 10, leaves standstill 5 hours; Roasting 5-8 hour under 673-973K under nitrogen protection, obtains carbonization SBA-15 sample B; Gained carbonization SBA-15 sample B is dissolved in the hydrofluoric acid solution of 40wt% and removes SiO ₂hard template, obtained carbon molecular sieve material;

Step 2, preparation sulfonation carbon molecular sieve: the carbon molecular sieve material of step 1 gained is put into the stainless steel cauldron that the concentrated sulfuric acid is housed, sulfonation 2-8 hour at 120 ~ 180 DEG C, by gained mixture deionized water suction filtration after sulfonation terminates, washing, until filtrate is in neutral, drying, obtained sulfonation carbon molecular sieve;

Step 3, prepare shitosan-sulfonation carbon molecular sieve hybridization compounding film: adopt blending method, the sulfonation carbon molecular sieve obtained by step 2 by certain mass stirs 12 hours in deionized water, ultrasonic 3 ~ 5 hours, clasmatosis 1 hour, pour in a flask, the viscosity adding certain mass is again the shitosan of 400mPas deacetylation 90.2%, shitosan content is made to be 2wt%, and the mass ratio of shitosan and sulfonation carbon molecular sieve is 100:0.5 ~ 6, drip the acetic acid of certain mass, the content of acetic acid in solution is made to be 2wt%, stirring at normal temperature 6 hours, and then add the glutaraldehyde of certain mass 2.5wt%, the cellular construction of shitosan and the cellular construction mol ratio of glutaraldehyde is made to be 100:4, 30 DEG C are cross-linked 2 hours, obtain casting solution, casting solution is left standstill, de-bubble, be spun on polyacrylonitrile ultrafiltration film, drying 24 hours under room temperature, obtained shitosan-sulfonation carbon molecular sieve hybridization compounding film.

4. the shitosan preparation method of shitosan described in claim 3-sulfonation carbon molecular sieve hybridization compounding film obtained-sulfonation carbon molecular sieve hybridization compounding film is used for the dehydration of acetone-water mixed system pervaporation, when in acetone-water mixed liquor, water content is 5wt%, the permeation flux of this hybridization compounding film is 1.24 ~ 1.81kg/m ²h, separation factor is 426 ~ 832.