CN108404881A - A kind of starch base montmorillonite Composite sorbing material of a variety of distribution of charges in surface and preparation method thereof - Google Patents

Abstract

The invention discloses a starch-based montmorillonite composite adsorption material with various charge distributions on the surface and a preparation method thereof, belonging to the technical field of preparation of adsorbents. The method comprises the following steps: (1) configuring starch milk solution; (2) cationizing starch molecules; (3) configuring anion, non-ionic solution; (4) anionizing starch molecules, introducing non-ionic groups; (5) ) Preparation of starch-based montmorillonite composite adsorption materials. Natural starch is modified by amination, phosphorylation, network cross-linking and other molecules, introducing cationic, anionic and non-ionic groups, and distributing various charges on the surface, which has a special molecular structure space effect. And introduce the traditional adsorbent montmorillonite to increase the specific surface area and increase the adsorption capacity. It has the dual adsorption characteristics of anion and cation starch and montmorillonite, and the composite adsorption material is easier to separate after adsorption.

Description

A starch-based montmorillonite composite adsorption material with multiple charge distribution on the surface and its preparation preparation method

technical field

The invention belongs to the technical field of preparation of natural polymer composite materials, and in particular relates to a starch-based montmorillonite composite adsorption material with multiple charge distributions on the surface and a preparation method thereof.

Background technique

Starch, as a renewable resource second only to cellulose, has the characteristics of cheap and easy to obtain, degradable, and can be easily converted into useful derivatives by biochemical methods. For a long time, all countries in the world have attached great importance to the research on the development and utilization of starch resources, especially the preparation of new natural polymer adsorbents by modifying starch has always been a research hotspot for scientific and technological workers. At present, there are many studies on cationic and amphoteric starch in China, but there are few reports on the research on multi-component modified starch that combines cationic, anionic and nonionic starches. In addition, multi-component modified starch adsorption materials also have disadvantages such as large dosage, slow settling speed, and easy loss of active groups after being stored for too long. In order to achieve this function, it is necessary to combine starch-based adsorbent materials with traditional adsorbents, so that the advantages of the two can complement each other and give full play to their respective advantages, so as to achieve better application results.

Contents of the invention

The object of the present invention is to provide a kind of starch-based montmorillonite composite adsorption material with specific molecular structure and multiple charge distribution on the surface and its preparation method.

The purpose of the present invention is achieved through the following technical solutions.

A preparation method of a starch-based montmorillonite composite adsorption material with multiple charge distributions on the surface, comprising the steps of:

(1) Prepare starch milk solution: add starch to water and stir evenly to obtain starch milk solution;

(2) Cationization of starch molecules: Add sodium hydroxide and 3-chloro-2-hydroxypropyltrimethylammonium chloride solution to the starch milk solution obtained in step (1) and stir to react, then centrifuge, filter, wash, Dried to obtain cationized starch;

(3) Prepare anionic and nonionic solution: Dissolve sodium tripolyphosphate (Na ₅ P ₃ O ₁₀ ·H ₂ O) and urea (CO(NH ₂ ) ₂ ) in water to obtain anionic and nonionic solution;

(4) Preparation of anion-cation modified starch: adding the cationized starch in step (2) into the anion-nonionic solution in step (3), stirring evenly, drying and reacting to obtain anion-cation modified starch;

(5) Preparation of starch-based montmorillonite composite adsorption material: Dissolve the anion-cation modified starch in step (4) in water, then add montmorillonite and epichlorohydrin, and react in a water bath until stirring is difficult to obtain starch-based montmorillonite Soil removal composite adsorption material.

Preferably, the mass concentration of the starch milk solution in step (1) is 20%-30%.

Preferably, the amount of NaOH in step (2) is 2% of the starch mass.

Preferably, the dosage relationship between 3-chloro-2-hydroxypropyltrimethylammonium chloride and starch in step (2) is 0.1-0.6 mL/g.

Preferably, the method of introducing cations on starch in step (2) is to add 3-chloro-2-hydroxypropyl trimethyl with a mass concentration of 69% to the starch milk solution with sodium hydroxide under the action of an electric field of 120-150V ammonium chloride solution. The adding of 3-chloro-2-hydroxypropyltrimethylammonium chloride solution under the action of an electric field of 120V-150v is to place the starch solution in a JY-SPFT type horizontal electrophoresis tank, adjust the voltage to 120v, and slowly add 3 -Chloro-2-hydroxypropyltrimethylammonium chloride solution, make the cation fully contact with the starch molecules.

Preferably, the temperature of the stirring reaction in step (2) is 40-60°C, and the time is 4-7h.

Preferably, the washing in step (2) is to alternately wash the precipitate three times with absolute ethanol and deionized water.

Preferably, in step (3), sodium tripolyphosphate is first added to the water, and then urea is added after fully dissolving; the quality of the sodium tripolyphosphate is 3% to 10% of the starch quality; the quality of the urea is 2% to 6% of the mass.

Preferably, in step (3), the pH of the anionic and nonionic solution is adjusted to 6-7.

Preferably, in step (4), the mass concentration of the starch is adjusted to 25%-35% after adding the cationized starch to the anionic and non-ionic solution. The specific operation of adjusting the mass concentration of starch is to add deionized water according to the powder mass in step (2), so that the mass concentration of starch is 25%-35%.

Preferably, the drying temperature in step (4) is 60°C.

Preferably, the temperature of the reaction in step (4) is 100°C-140°C, and the time is 1-4h.

Preferably, in step (5), montmorillonite with a starch mass of 20%-30% is added, and epichlorohydrin with a starch mass of 1%-2% is added, and the mass of montmorillonite is preferably 20%-20% of the starch mass. 30%

Preferably, the pH of the reaction solution is adjusted to 10 before the water bath reaction in step (5).

Preferably, the temperature of the water bath reaction in step (5) is 60°C-80°C.

The substances for adjusting pH mentioned above are all 0.1mol/L NaOH solution.

The centrifugation mentioned above all adopts L-550 desktop centrifuge, and the centrifugation condition is 5000r/min centrifugation for 5min;

The above-mentioned drying is done in a 101-1 constant temperature oven at 60°C until the water evaporates completely;

The grinding mentioned above all adopts QSB-100 multifunctional pulverizer, and pulverizes to pass through 100-150 sieves.

A starch-based montmorillonite composite adsorption material with various charge distributions on the surface prepared by the above-mentioned preparation method.

Principle of the present invention is as follows:

The principle of natural starch molecular modification: the cationic groups in the multi-component modified starch help to remove the cationic substances in the system that hinder the adsorption of starch, and electrically repel the highly active heterocations in those systems, so that the anionic groups in the starch do not It will be neutralized prematurely; the anionic groups contained in it can adsorb and precipitate with the adsorbed ions; the non-ionic groups play a synergistic role. The reactive groups on the modified starch work together to make the adsorption capacity have a more obvious effect.

Cationization: Cationic starch is prepared by the reaction of cationic alkyl ethers. After starch is treated with 3-chloro-2-hydroxypropyl-trimethyl quaternary ammonium salt, the obtained product has high nitrogen content and high degree of substitution , good flocculation. Therefore, the present invention uses 3-chloro-2-hydroxypropyltrimethylammonium chloride as an etherifying agent to prepare cationic etherified starch with a higher degree of substitution.

Anionization: Starch phosphate is the product of the esterification reaction between the hydroxyl group of the starch molecule and the phosphate, and is an anion-modified starch. Phosphoric acid is a tribasic acid, which can undergo esterification reaction with the hydroxyl groups on C ₂ , C ₃ , and C ₆ in the glucose unit of starch molecules to form starch phosphate mono-, di-, and tri-esters.

Non-ionization: Add urea as a catalyst during the reaction to improve the reaction efficiency. Urea can also form starch carbamate with starch, resulting in cross-linking, which significantly increases the viscosity of starch paste.

Intercalation compounding of modified starch and montmorillonite: the basic structural unit of montmorillonite is a layered structure formed by a piece of aluminum-oxygen octahedron sandwiched between two pieces of silicon-oxygen tetrahedron by sharing oxygen atoms. Weak electrical properties, starch with anions and cations can be inserted between the sheets.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

(1) The cationized starch of the present invention can generate amphoteric starch with anion and cation groups through esterification reaction with phosphates. Compared with native starch, it has higher transparency, paste viscosity, and stronger glue Viscosity, stability and flocculation. The combination of anionic and cationic starch can greatly improve the flocculation performance of native starch. In addition, non-ionic urea can form starch carbamate with starch, and at the same time greatly promote the synthesis of starch phosphate and increase the degree of substitution. In addition, the multi-component modified starch can also basically balance the charge of the wastewater treatment system, ensure the adsorption of the target ions, and not affect the Zeta potential in the solution, and the application conditions are relaxed.

(2) The anion-cation modified starch of the present invention is intercalated with montmorillonite, combining the dual advantages of traditional adsorbents and modified starch adsorbents, complementing each other's advantages, having the advantages of large particles, fast sedimentation, and accelerated flocculation speed, and at the same time has the advantages of It has multiple functions such as decolorization, adsorption of heavy metals, and sedimentation of suspended particles.

Description of drawings

Figure 1 is a scanning electron microscope image of native starch.

2 is a scanning electron micrograph of the cationized starch of Example 1.

3 is a scanning electron micrograph of the molecularly modified starch of Example 1.

Fig. 4 is the adsorption effect diagram of the starch-based montmorillonite composite adsorption material of Example 1.

Fig. 5 is the adsorption effect diagram of the starch-based montmorillonite composite adsorption material in Example 2.

Fig. 6 is the adsorption effect diagram of the starch-based montmorillonite composite adsorption material in Example 3.

Detailed ways

In order to better understand the present invention, the present invention will be further described below in conjunction with the examples, but the protection scope of the present invention is not limited to the range indicated by the examples.

Example 1:

The first step is to weigh 200g of corn dry starch into the reactor, add 800g of deionized water, stir evenly, and prepare a starch milk solution with a concentration of 20% by mass.

The scanning electron microscope image of the native starch in this example, magnified 2000 times, is shown in Figure 1. The surface of the unmodified native starch is relatively smooth, and the particles are relatively dispersed.

The second step is to add 4g of NaOH solid to the starch milk solution, stir magnetically, mix evenly, place in the electrophoresis tank, adjust the voltage to 120v, and slowly add 20ml of 3-chloro-2-hydroxy with a mass concentration of 69% under the action of an electric field Propyltrimethylammonium chloride solution, placed in a water bath at 50°C for 4 hours, centrifuged the reacted solution, filtered to remove the supernatant, washed the precipitate three times alternately with absolute ethanol and deionized water, and then The precipitate was dried, ground to a powder, weighed and recorded the powder mass.

The 1000-fold scanning electron microscope image of the cationized starch obtained in this example is shown in Figure 2. It can be seen that grooves appear on some starch granules, which increases the specific surface area of the granules.

The third step is to weigh 20g of sodium tripolyphosphate (Na ₅ P ₃ O ₁₀ H ₂ O) and dissolve it in 50ml of deionized water. After fully dissolving, add 8g of urea (CO(NH ₂ ) ₂ ) to it, mix well, and 0.1mol/L NaOH solution to adjust the pH to 6-7.

The fourth step is to add the intermediate solution obtained in the third step to the dry starch obtained in the second step, stir magnetically, add 400ml of deionized water to adjust the mass concentration of the starch milk solution to 30%, and dry the dry cake at 140°C after drying at 60°C Reaction 2.5h. Alternately wash three times with deionized water and absolute ethanol, dry, and grind into powder to obtain molecularly modified starch.

The scanning electron microscope image of the molecularly modified starch obtained in this example is magnified 500 times as shown in Figure 3. After multi-component modification, due to the non-ionic cross-linking effect, the particles are closely connected to form a polymer with a larger molecular weight. objects, and the grooves on the surface of the particles increased significantly. The change of particle morphology indirectly explains the successful introduction of the three ionic groups. In addition, due to the obvious increase in the micropores on the particle surface and between particles, it is more conducive to the combination of heavy metal ions and starch internal groups to form polymers. precipitation.

The fifth step is to dissolve the anion-cation modified starch obtained in the fourth step in 500ml of deionized water, add 60g of montmorillonite, 2ml of epichlorohydrin, adjust the pH to 10 with 0.1mol/L NaOH solution, react in a water bath at 70°C for 1h, and dry , that is, starch-based montmorillonite composite adsorption material.

The adsorption effect of the composite adsorbent obtained in this example is shown in Figure 4.

Example 2

The first step is to weigh 200g of corn dry starch into the reactor, add 470g of deionized water, stir evenly, and prepare a starch milk solution with a concentration of 30% by mass.

The second step is to add 4g of NaOH solid to the starch milk solution, stir magnetically, mix evenly, place in the electrophoresis tank, adjust the voltage to 135v, and slowly add 120ml of 3-chloro-2-hydroxy with a mass concentration of 69% under the action of an electric field Propyltrimethylammonium chloride solution, reacted in a water bath at 40°C for 7 hours, centrifuged the reacted solution, filtered to remove the supernatant, washed the precipitate three times alternately with absolute ethanol and deionized water, and then washed the precipitate The material was dried, ground to powder, weighed and recorded the powder mass.

The third step is to weigh 6g of sodium tripolyphosphate (Na ₅ P ₃ O ₁₀ ·H ₂ O) and dissolve it in 50ml of deionized water. After fully dissolving, add 12g of urea (CO(NH ₂ ) ₂ ) to it and mix well. Adjust the pH to 6-7 with 0.1mol/L NaOH solution.

The fourth step is to add the intermediate solution obtained in the third step to the dry starch obtained in the second step, stir magnetically, add 400ml of deionized water to adjust the mass concentration of the starch milk solution to 35%, and dry the dry cake at 120°C after drying at 60°C Reaction 1h. Alternately wash three times with deionized water and absolute ethanol, dry, and grind into powder to obtain molecularly modified starch.

The fifth step is to dissolve the anion-cation modified starch obtained in the fourth step in 500ml of deionized water, add 40g of montmorillonite, 3ml of epichlorohydrin, adjust the pH to 10 with 0.1mol/L NaOH solution, react in a water bath at 80°C for 0.5h, and bake dry to obtain the starch-based montmorillonite composite adsorption material.

The adsorption effect of the adsorbent obtained in this embodiment is shown in Figure 5.

Example 3

The first step is to weigh 200g of corn dry starch into the reactor, add 600g of deionized water, stir evenly, and prepare a starch milk solution with a concentration of 25% by mass.

The second step is to add 4g of NaOH solid to the starch milk solution, stir magnetically, mix evenly, place it in the electrophoresis tank, adjust the voltage to 150v, and slowly add 70ml of 3-chloro-2-hydroxypropyl with a mass concentration of 69% under the action of an electric field base trimethylammonium chloride solution, reacted in a water bath at 60°C for 5.5 hours, centrifuged the reacted solution, filtered to remove the supernatant, washed the precipitate three times alternately with absolute ethanol and deionized water, and then washed the precipitate Dry, grind to powder, weigh and record the powder mass.

The third step is to weigh 13g of sodium tripolyphosphate (Na ₅ P ₃ O ₁₀ ·H ₂ O) and dissolve it in 50 ml of deionized water. After fully dissolving, add 4 g of urea (CO(NH ₂ ) ₂ ) to it and mix well. Adjust the pH to 6-7 with 0.1mol/L NaOH solution.

The fourth step is to add the intermediate solution obtained in the third step to the dry starch obtained in the second step, stir magnetically, add 400ml of deionized water to adjust the mass concentration of the starch milk solution to 25%, and dry the dry cake at 100°C after drying at 60°C. 4h. Alternately wash three times with deionized water and absolute ethanol, dry, and grind into powder to obtain molecularly modified starch.

The fifth step is to dissolve the anion-cation modified starch obtained in the fourth step in 500ml of deionized water, add 50g of montmorillonite, 4ml of epichlorohydrin, adjust the pH to 10 with 0.1mol/L NaOH solution, react in a water bath at 70°C for 1.5h, and bake dry to obtain the starch-based montmorillonite composite adsorption material.

The adsorption effect of the adsorbent obtained in this embodiment is shown in Figure 6.

Performance Testing:

The composite adsorption material prepared in Examples 1-3 was tested for performance, and the composite adsorption material was applied to industrial wastewater, and the removal rate of heavy metal ions in the wastewater before and after adsorption was tested. The test results are shown in Figure 4, Figure 5, and Figure 6. Fig. 4 is an adsorption effect diagram of the composite adsorption material obtained in Example 1, Fig. 5 is an adsorption effect diagram of the composite adsorption material obtained in Example 2, and Fig. 6 is an adsorption effect diagram of the composite adsorption material obtained in Example 3. It can be seen from the figure that the removal rates of heavy metals in the three embodiments all reach more than 96%.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, Simplifications should be equivalent replacement methods, and all are included in the protection scope of the present invention.

Claims (10)

1. a kind of preparation method of the starch base montmorillonite Composite sorbing material of a variety of distribution of charges in surface, which is characterized in that packet Include following steps：

（1）Configure starch milk solution：Starch is added to the water, is stirred evenly, starch milk solution is obtained；

（2）The cationization of starch molecule：To step（1）Sodium hydroxide and the chloro- 2- hydroxypropyls of 3- are added in gained starch milk solution Base trimethyl ammonia chloride ammonium salt solution is stirred to react, then is centrifuged, is filtered, washed, is dried, and cationic starch is obtained；

（3）Configure anion non-ionic solution：Sodium tripolyphosphate and urea is soluble in water, obtain anion non-ionic solution；

（4）The preparation of zwitterion Modified Starch：By step（2）Cationic starch be added step（3）Anion it is non-from In sub- solution, reaction is dried after stirring evenly, obtains zwitterion Modified Starch；

（5）The preparation of starch base montmorillonite Composite sorbing material：By step（4）Zwitterion Modified Starch it is soluble in water, then Montmorillonite and epoxychloropropane is added, water-bath obtains starch base montmorillonite Composite sorbing material until stirring difficulty.

2. preparation method according to claim 1, it is characterised in that：Step（2）The middle chloro- 2- Hydroxyproyl Trimethyls chlorinations of 3- The dosage relation of ammonium salt solution and starch is 0.1~0.6mL/g.

3. preparation method according to claim 1, it is characterised in that：Step（2）In cationic processes are introduced on starch For the chloro- 2- Hydroxyproyl Trimethyls chlorinations of 3- are added into the starch milk solution of addition sodium hydroxide under 120-150V electric field actions Ammonium salt solution.

4. preparation method according to claim 1, it is characterised in that：Step（2）The temperature being stirred to react is 40-60 DEG C, time 4-7h.

5. preparation method according to claim 1, it is characterised in that：Step（3）In, tripolyphosphate is first added into water Sodium fully adds urea after dissolving；The quality of the sodium tripolyphosphate is the 3%~10% of starch quality；The matter of the urea Amount is the 2%~6% of starch quality.

6. preparation method according to claim 1, it is characterised in that：Step（4）In, anion is added in cationic starch The mass concentration that cationic starch is adjusted after non-ionic solution is 25%-35%.

7. preparation method according to claim 1, it is characterised in that：Step（4）The temperature of the reaction is 100 DEG C -140 DEG C, the time is 1~4h.

8. preparation method according to claim 1, it is characterised in that：Step（5）In, it is added starch quality 20%-30%'s Montmorillonite, and the epoxychloropropane of starch quality 1%-2% is added.

9. preparation method according to claim 1, it is characterised in that：Step（5）The temperature of the water-bath be 60 DEG C- 80℃。

10. a kind of starch base illiteracy of a variety of distribution of charges in surface made from claim 1-9 any one of them preparation methods De- soil composite adsorbing material.