CN107308829A - Preparation method for the polylactic acid porous film of anionic dye waste water processing - Google Patents

Abstract

A kind of preparation method of the polylactic acid porous film that is used for anionic dye wastewater treatment, its step mainly is: A, dichloromethane and N,N-dimethylformamide are mixed by the volume ratio of 4-9:1 Solvent, add 15-25 parts by weight of polylactic acid and 0.1-0.4 parts by weight of a strong basic small molecule compound containing polyamino groups into 100 parts by weight of a mixed solvent, and stir in a water bath at 30-38°C until the polylactic acid dissolves , to obtain a mixed solution; B, add 0.6-1.2 parts of heavy amino-containing silane coupling agent to the mixed solution and stir in a water bath at 30-38°C for 0.8-1.3h to obtain a polylactic acid electrospinning solution; C, The polylactic acid electrospinning solution is used as a raw material solution for electrospinning, and is obtained by electrospinning. The porous film prepared by the method has excellent adsorption performance on the anions in the anionic dye wastewater, has a good purification treatment effect on the wastewater, and has a simple preparation process.

Description

Preparation method of polylactic acid porous film for anionic dye wastewater treatment

technical field

The invention relates to a preparation method of a polylactic acid porous film used for anionic dye wastewater treatment.

technical background

Dye wastewater is one of the main harmful industrial wastewater, which mainly comes from the production industry of dyes and dye intermediates. It is composed of the mother liquor of crystallization of various products and intermediates, materials lost during the production process, and sewage from washing the ground. With the continuous growth of the dye industry, its production wastewater has become a major source of water pollution. According to the ionic state of dye molecules dissociated in aqueous solution, the field of environmental engineering is divided into: anionic dyes (such as direct dyes, acid dyes); cationic dyes (such as basic dyes); non-ionic dyes (such as disperse dyes). Among them, the production scale of anionic dyes is large, the discharge of wastewater is large, and the pollution to the environment is large; in order to protect the environment, the wastewater of anionic dyes must be purified.

As a technology for purifying wastewater, electrospinning membrane adsorption method is convenient and efficient, simple to operate, easy to prepare, large in adsorption capacity, and can introduce groups that provide complexation to increase the ability of chemical adsorption. Potential wastewater treatment methods. However, electrospun membranes are used to treat anionic dye wastewater. Due to the small adsorption between electrospun membranes and anionic dyes, the purification treatment effect is poor.

Contents of the invention

The object of the present invention is to provide a kind of preparation method of the polylactic acid porous membrane that is used for the treatment of anionic dye wastewater, the porous membrane prepared by this method has excellent adsorption performance to the anion in the anionic dye wastewater, and the purification treatment effect of wastewater is good; And its preparation process is simple.

The technical scheme that the present invention realizes its object of the invention adopted is, a kind of preparation method of the polylactic acid porous film that is used for anionic dye wastewater treatment, its steps are as follows:

A. Dichloromethane and N,N-dimethylformamide are formulated into a mixed solvent at a volume ratio of 4-9:1, and 15-25 parts by weight of polylactic acid and 0.1-0.4 parts by weight of polyamino-containing The strong basic small molecular compound is added to 100 parts by weight of a mixed solvent, stirred in a water bath at 30-38°C, and stirred until the polylactic acid is completely dissolved to obtain a mixed solution;

B. Add 0.6-1.2 parts by weight of amino group-containing silane coupling agent to the mixed solution and stir in a water bath at 30-38°C for 0.8-1.3 hours to obtain a polylactic acid electrospinning solution;

C. The polylactic acid electrospinning solution is used as the raw material solution for electrospinning, and electrospinning is performed to prepare a polylactic acid porous film.

Compared with prior art, the beneficial effect of the present invention is:

One, the inventive method adopts dichloromethane and N,N-dimethylformamide mixed solvent as the solvent of polylactic acid, and dichloromethane has stronger volatility, can further improve the volatility of mixed solvent, in electrospinning During the continuous spinning process, the solvent evaporates rapidly and exchanges with the water in the air, the fiber solidifies, the water droplets volatilize, and then nanometer-sized holes are formed on the surface of the fiber. At the same time, a large number of holes are also formed when the electrostatic fibers come out and overlap each other. It makes the polylactic acid film form a multi-level pore structure, increases the specific surface area of the material, and promotes the contact and adsorption of the polylactic acid film to the anionic harmful substances of the anionic dye wastewater; the purification effect of the anionic dye wastewater is good.

Two, in the raw material liquid of the electrospinning of the inventive method, add the highly basic small molecular compound containing polyamino group and the silane coupling agent containing amino group, make the polylactic acid fiber surface band that electrospinning obtains a large amount of amino groups, realize Cationic modification of polylactic acid fibers. When in use, a large number of amino groups on the surface of polylactic acid fibers are protonated into amino cations in water, and have a strong charge-attractive interaction with anions in anionic dye wastewater, thereby significantly improving the adsorption of polylactic acid fibers to anionic dye wastewater , Purification ability.

Three, the inventive method adopts electrospinning technology as film preparation technique. The method has mild reaction conditions, universal equipment and low preparation cost. The process is simple and controllable, and the fiber structure parameters, such as fiber diameter, interfiber gap size, film porosity, etc., can be adjusted by regulating voltage and other external field effects.

Experiments have proved that the polylactic acid porous film prepared by the present invention has a high adsorption effect on the solution of the anionic dye-Congo red, and the adsorption amount reaches 73.53 mg/g after 48 hours of adsorption.

Further, the polyamino-containing strongly basic small molecular compound of the present invention is one or more mixtures of ethylenediamine, diethylenetriamine, and triethylenetetramine;

The amino group-containing silane coupling agent of the present invention is γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane or aminoethyliminopropylpolydimethylsiloxane.

Experiments prove that:

Adding a specific content of the above-mentioned strong basic small molecule compound containing polyamino groups into the electrospinning solution will not affect the electrostatic polymerization of polylactic acid to form a film, and will be well combined on the surface of polylactic acid fibers, making the surface of polylactic acid fibers Bring plenty of amino.

These amino-containing silane coupling agents, while ensuring to promote the polymerization of polylactic acid to form a film, will also bring a large number of amino groups on the surface of polylactic acid fibers. Furthermore, the adsorption and purification ability of the polylactic acid fiber to anionic dye wastewater is obviously improved.

Furthermore, the electrostatic voltage of the electrospinning of the present invention is 10.78-15.65 kV.

Under this condition, polylactic acid can continuously and stably produce filaments on the electrospinning machine, and promote the volatilization of the solvent during the electrospinning process, thereby preparing a film with a good porous structure.

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

Description of drawings

Fig. 1 is a scanning electron microscope image of a polylactic acid film prepared in Example 1 of the present invention.

Fig. 2 is the adsorption curve of the polylactic acid film prepared in Example 1 and the polylactic acid film prepared in the comparative example to the solution of the anionic dye-Congo red as a function of time.

detailed description

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

Embodiment one

A kind of preparation method of the polylactic acid porous membrane that is used for anionic dye wastewater treatment, its steps are as follows:

A. Dichloromethane and N,N-dimethylformamide are formulated into a mixed solvent at a volume ratio of 5.67:1, and 20 parts by weight of polylactic acid and 0.2 parts by weight of a strong basic small molecule compound containing polyamino groups - Diethylenetriamine was added to 100 parts by weight of the mixed solvent, stirred in a water bath at 36°C, and stirred until the polylactic acid was completely dissolved to obtain a mixed solution;

B. Add 0.9 parts by weight of an amino group-containing silane coupling agent—γ-aminopropyltriethoxysilane to the mixed solution and stir in a water bath at 36°C for 1.2 hours to obtain a polylactic acid electrospinning solution;

C. The polylactic acid electrospinning solution is used as the raw material solution for electrospinning, and electrospinning is performed to prepare a polylactic acid porous film. The electrostatic voltage of electrospinning is 15.65kV.

Fig. 1 is the scanning electron micrograph of the polylactic acid porous film that this example makes. It can be seen from Figure 1 that the polylactic acid porous film prepared in this example has an obvious multi-level pore structure, and the specific surface area of the material is large.

Comparative example one

In order to improve the adsorption performance of the polylactic acid porous film prepared by the present invention, an unmodified pure polylactic acid film was prepared by almost the same process. Its preparation steps are as follows:

Dichloromethane and N,N-dimethylformamide were prepared as a mixed solvent at a volume ratio of 5.67:1, 20 parts by weight of polylactic acid were added to 100 parts by weight of the mixed solvent, and stirred in a water bath at 36°C. Stir until the polylactic acid is completely dissolved to obtain a mixed solution;

The mixed solution is used as a raw material solution for electrospinning, and electrospinning is performed to prepare a polylactic acid porous film. The electrostatic voltage of electrospinning is 15.65kV.

The adsorption curves of the same concentration of Congo red in Example 1 and Comparative Example are shown in Figure 1b. It can be seen that the adsorption performance of the modified polylactic acid fiber in Example 1 is greatly improved compared with the pure polylactic acid fiber in Comparative Example.

Embodiment two:

A kind of preparation method of the polylactic acid porous membrane that is used for anionic dye wastewater treatment, its steps are as follows:

A. Dichloromethane and N,N-dimethylformamide are formulated into a mixed solvent at a volume ratio of 9:1, and 25 parts by weight of polylactic acid and 0.3 parts by weight of a strong basic small molecule compound containing polyamino groups - Diethylenetriamine was added to 100 parts by weight of the mixed solvent, stirred in a water bath at 38°C, and stirred until the polylactic acid was completely dissolved to obtain a mixed solution;

B. Add 1.2 parts by weight of an amino group-containing silane coupling agent—γ-aminopropyltriethoxysilane to the mixed solution and stir in a water bath at 38°C for 1.3 hours to obtain a polylactic acid electrospinning solution;

C. The polylactic acid electrospinning solution is used as the raw material solution for electrospinning, and electrospinning is performed to prepare a polylactic acid porous film. The electrostatic voltage of electrospinning is 14.34kV.

Embodiment three:

A kind of preparation method of the polylactic acid porous membrane that is used for anionic dye wastewater treatment, its steps are as follows:

A. Dichloromethane and N,N-dimethylformamide are formulated into a mixed solvent at a volume ratio of 5.67:1, and 15 parts by weight of polylactic acid and 0.4 parts by weight of a strong basic small molecule compound containing polyamino groups - Diethylenetriamine was added to 100 parts by weight of the mixed solvent, stirred in a water bath at 30°C, and stirred until the polylactic acid was completely dissolved to obtain a mixed solution;

B. Add 0.6 parts by weight of an amino group-containing silane coupling agent—γ-aminopropyltrimethoxysilane to the mixed solution and stir in a water bath at 35°C for 0.8 hours to obtain a polylactic acid electrospinning solution;

C. The polylactic acid electrospinning solution is used as the raw material solution for electrospinning, and electrospinning is performed to prepare a polylactic acid porous film. The electrostatic voltage of electrospinning is 12.21kV.

Embodiment four:

A kind of preparation method of the polylactic acid porous membrane that is used for anionic dye wastewater treatment, its steps are as follows:

A. Dichloromethane and N,N-dimethylformamide are formulated into a mixed solvent at a volume ratio of 4:1, and 22 parts by weight of polylactic acid and 0.2 parts by weight of a strong basic small molecule compound containing polyamino groups - Add ethylenediamine to 100 parts by weight of mixed solvent, stir in a water bath at 38°C, and stir until the polylactic acid is completely dissolved to obtain a mixed solution;

B. Add 1.2 parts by weight of amino-containing silane coupling agent—γ-aminopropyltrimethoxysilane to the mixed solution and stir in a water bath at 38°C for 1.3 hours to obtain a polylactic acid electrospinning solution;

C. The polylactic acid electrospinning solution is used as the raw material solution for electrospinning, and electrospinning is performed to prepare a polylactic acid porous film. The electrostatic voltage of electrospinning is 11.45kV.

Embodiment five:

A kind of preparation method of the polylactic acid porous membrane that is used for anionic dye wastewater treatment, its steps are as follows:

A. Dichloromethane and N,N-dimethylformamide are formulated into a mixed solvent at a volume ratio of 5.67:1, and 20 parts by weight of polylactic acid and 0.1 part by weight of a strong basic small molecule compound containing polyamino groups - Diethylenetriamine was added to 100 parts by weight of the mixed solvent, stirred in a water bath at 36°C, and stirred until the polylactic acid was completely dissolved to obtain a mixed solution;

B. Add 0.9 parts by weight of an amino group-containing silane coupling agent—γ-aminopropyltriethoxysilane to the mixed solution and stir in a water bath at 36°C for 0.8 hours to obtain a polylactic acid electrospinning solution;

C. The polylactic acid electrospinning solution is used as the raw material solution for electrospinning, and electrospinning is performed to prepare a polylactic acid porous film. The electrostatic voltage of electrospinning is 14.65kV.

Embodiment six:

A kind of preparation method of the polylactic acid porous membrane that is used for anionic dye wastewater treatment, its steps are as follows:

A. Dichloromethane and N,N-dimethylformamide are formulated into a mixed solvent at a volume ratio of 5.67:1, and 20 parts by weight of polylactic acid and 0.4 parts by weight of highly basic small molecule compounds containing polyamino groups - Add ethylenediamine to 100 parts by weight of mixed solvent, stir in a water bath at 33°C, and stir until the polylactic acid is completely dissolved to obtain a mixed solution;

B. Add 0.6 parts by weight of an amino group-containing silane coupling agent—γ-aminopropyltriethoxysilane to the mixed solution and stir in a water bath at 36°C for 0.9 hours to obtain a polylactic acid electrospinning solution;

C. The polylactic acid electrospinning solution is used as the raw material solution for electrospinning, and electrospinning is performed to prepare a polylactic acid porous film. The electrostatic voltage of electrospinning is 10.78kV.

Embodiment seven:

A kind of preparation method of the polylactic acid porous membrane that is used for anionic dye wastewater treatment, its steps are as follows:

A. Dichloromethane and N,N-dimethylformamide are prepared into a mixed solvent at a volume ratio of 5.67:1, and 20 parts by weight of polylactic acid and 0.3 parts by weight of a strong basic small molecule compound containing polyamino groups - Add ethylenediamine and triethylenetetramine in a volume ratio of 1:1 to 100 parts by weight of a mixed solvent, stir in a water bath at 33°C, and stir until the polylactic acid is completely dissolved to obtain a mixed solution;

B. Add 0.9 parts by weight of an amino group-containing silane coupling agent—aminoethyliminopropyl polydimethylsiloxane to the mixed solution, and stir in a water bath at 36° C. for 1 hour to obtain a polylactic acid electrospinning solution;

C. The polylactic acid electrospinning solution is used as the raw material solution for electrospinning, and electrospinning is performed to prepare a polylactic acid porous film. The electrostatic voltage of electrospinning is 12.36kV.

Embodiment eight:

A kind of preparation method of the polylactic acid porous membrane that is used for anionic dye wastewater treatment, its steps are as follows:

A. Dichloromethane and N,N-dimethylformamide are formulated into a mixed solvent at a volume ratio of 5.67:1, and 20 parts by weight of polylactic acid and 0.4 parts by weight of highly basic small molecule compounds containing polyamino groups - Ethylenedienetriamine, triethylenetetramine, and ethylenediamine in a volume ratio of 1:1:1 are added to 100 parts by weight of a mixed solvent, stirred in a water bath at 35°C until the polylactic acid is completely dissolved, get the mixture;

B. Add 0.9 parts by weight of an amino group-containing silane coupling agent—γ-aminopropyltriethoxysilane to the mixed solution and stir in a water bath at 35°C for 1.1 hours to obtain a polylactic acid electrospinning solution;

C. The polylactic acid electrospinning solution is used as the raw material solution for electrospinning, and electrospinning is performed to prepare a polylactic acid porous film. The electrostatic voltage of electrospinning is 15.51kV.

Embodiment nine:

A kind of preparation method of the polylactic acid porous membrane that is used for anionic dye wastewater treatment, its steps are as follows:

A. Dichloromethane and N,N-dimethylformamide are formulated into a mixed solvent at a volume ratio of 9:1, and 22 parts by weight of polylactic acid and 0.4 parts by weight of a strong basic small molecule compound containing polyamino groups - Add triethylenetetramine to 100 parts by weight of a mixed solvent, stir in a water bath at 35°C, and stir until the polylactic acid is completely dissolved to obtain a mixed solution;

B. Add 1 part by weight of an amino group-containing silane coupling agent—aminoethyliminopropyl polydimethylsiloxane to the mixed solution, and stir in a water bath at 35°C for 1.1 hours to obtain a polylactic acid electrospinning solution ;

C. The polylactic acid electrospinning solution is used as the raw material solution for electrospinning, and electrospinning is performed to prepare a polylactic acid porous film. The electrostatic voltage of electrospinning is 14.56kV.

Embodiment ten:

A kind of preparation method of the polylactic acid porous membrane that is used for anionic dye wastewater treatment, its steps are as follows:

A. Dichloromethane and N,N-dimethylformamide are prepared into a mixed solvent at a volume ratio of 4:1, and 20 parts by weight of polylactic acid and 0.4 parts by weight of a strong basic small molecule compound containing polyamino groups - Add triethylenetetramine to 100 parts by weight of a mixed solvent, stir in a water bath at 35°C, and stir until the polylactic acid is completely dissolved to obtain a mixed solution;

B. Add 1.1 parts by weight of an amino group-containing silane coupling agent—aminoethyliminopropyl polydimethylsiloxane to the mixed solution, and stir in a water bath at 35°C for 1.3 hours to obtain a polylactic acid electrospinning solution ;

C. The polylactic acid electrospinning solution is used as the raw material solution for electrospinning, and electrospinning is performed to prepare a polylactic acid porous film. The electrostatic voltage of electrospinning is 13.36kV.

Embodiment eleven:

A kind of preparation method of the polylactic acid porous membrane that is used for anionic dye wastewater treatment, its steps are as follows:

A. Dichloromethane and N,N-dimethylformamide are formulated into a mixed solvent at a volume ratio of 9:1, and 22 parts by weight of polylactic acid and 0.3 parts by weight of a strong basic small molecule compound containing polyamino groups - Ethylenedienetriamine, triethylenetetramine, and ethylenediamine in a volume ratio of 1:0.5:1 are added to 100 parts by weight of a mixed solvent, stirred in a water bath at 37°C until the polylactic acid is completely dissolved, get the mixture;

B. Add 0.9 parts by weight of an amino group-containing silane coupling agent—aminoethyliminopropyl polydimethylsiloxane to the mixed solution, and stir in a water bath at 37°C for 0.9 hours to obtain a polylactic acid electrospinning solution ;

C. The polylactic acid electrospinning solution is used as the raw material solution for electrospinning, and electrospinning is performed to prepare a polylactic acid porous film. The electrostatic voltage of electrospinning is 13.39kV.

Claims (3)

1. a kind of preparation method of the polylactic acid porous film that is used for anionic dye wastewater treatment, its steps are as follows: A. Dichloromethane and N,N-dimethylformamide are formulated into a mixed solvent at a volume ratio of 4-9:1, and 15-25 parts by weight of polylactic acid and 0.1-0.4 parts by weight of polyamino-containing The strong basic small molecular compound is added to 100 parts by weight of a mixed solvent, stirred in a water bath at 30-38°C, and stirred until the polylactic acid is completely dissolved to obtain a mixed solution; B. Add 0.6-1.2 parts by weight of amino group-containing silane coupling agent to the mixed solution and stir in a water bath at 30-38°C for 0.8-1.3 hours to obtain a polylactic acid electrospinning solution; C. The polylactic acid electrospinning solution is used as the raw material solution for electrospinning, and electrospinning is performed to prepare a polylactic acid porous film. 2. a kind of preparation method of the polylactic acid porous film that is used for anionic dye wastewater treatment according to claim 1, is characterized in that: The highly basic small molecular compound containing polyamino groups is one or more mixtures of ethylenediamine, diethylenetriamine, and triethylenetetramine; The amino group-containing silane coupling agent is γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane or aminoethyliminopropylpolydimethylsiloxane. 3. A method for preparing a polylactic acid porous film for anionic dye wastewater treatment according to claim 1, characterized in that: the electrostatic voltage of the electrospinning is 10.78-15.65kV.