阅读说明：本技术 一种包含煤矸石和淀粉的复合高吸水性聚合物及其制备方法 (Composite super absorbent polymer containing coal gangue and starch and preparation method thereof ) 是由 张岩 高平强 张星宇 陈嘉 宁娇 闫涛 于 2019-08-26 设计创作，主要内容包括：本发明提供了一种包含煤矸石和淀粉的复合高吸水性聚合物及其制备方法,该复合高吸水性聚合物由反相悬浮聚合体系进行聚合获得,反相悬浮聚合体系包括水相和油相,水相包括水、淀粉、引发剂、改性煤矸石、交联剂、聚合单体和表面活性剂,水、淀粉、引发剂、改性煤矸石、交联剂、聚合单体和表面活性剂的重量比为(150-250)：(10-20)：(0.08-1.0)：(1-10)：(0.01-0.15)：100：(5-8)；油相与水的体积比为1：(1-5)。本发明添加了成本低廉的淀粉和煤矸石,降低了生产成本,综合性能优良,本发明获得的复合高吸水性聚合物具有良好的吸水性能、保水性能和耐盐性能。(The invention provides a composite super absorbent polymer containing coal gangue and starch and a preparation method thereof, the composite super absorbent polymer is obtained by polymerizing a reversed-phase suspension polymerization system, the reversed-phase suspension polymerization system comprises a water phase and an oil phase, the water phase comprises water, starch, an initiator, modified coal gangue, a cross-linking agent, a polymerization monomer and a surfactant, and the weight ratio of the water to the starch to the initiator to the modified coal gangue to the cross-linking agent to the polymerization monomer to the surfactant is (150-) -250): (10-20): (0.08-1.0): (1-10): (0.01-0.15): 100: (5-8); the volume ratio of the oil phase to the water is 1: (1-5). The invention adds the starch and the coal gangue with low cost, reduces the production cost, has excellent comprehensive performance, and the composite super absorbent polymer obtained by the invention has good water absorption performance, water retention performance and salt resistance.)

1. The preparation method of the modified coal gangue is characterized by comprising the following steps:

a) thermal activation: grinding and sieving the coal gangue, then calcining, pouring the calcined coal gangue into water for quenching, carrying out vacuum filtration and drying; wherein the calcining conditions are as follows: from 45-55 ℃, the temperature is programmed to 530 ℃ and 570 ℃ at the speed of 8-12 ℃/min, the temperature is preserved for 20-40min, then the temperature is raised to 580 ℃ and 820 ℃ at the speed of 8-12 ℃/min, the temperature is preserved for 1.5-2.5h, and the temperature is naturally reduced to 650 ℃;

b) alkali modification: adding the coal gangue dried in the step 1) into a sodium hydroxide aqueous solution, performing reaction by adopting magnetic stirring, performing vacuum filtration, and drying to obtain modified coal gangue; wherein the mass fraction of sodium hydroxide in the sodium hydroxide aqueous solution is 1.5-2.5%, and the volume ratio of the addition amount of the dried coal gangue to the sodium hydroxide aqueous solution is g: l ═ (5-20): (0.8-1.5).

2. A modified coal gangue, characterized by being obtained by the production method according to claim 1.

3. A composite super absorbent polymer, which is obtained by polymerizing a reversed phase suspension polymerization system, wherein the reversed phase suspension polymerization system comprises an aqueous phase and an oil phase, the aqueous phase comprises water, starch, an initiator, the modified coal refuse of claim 2, a cross-linking agent, a polymerization monomer and a surfactant, and the weight ratio of the water, the starch, the initiator, the modified coal refuse, the cross-linking agent, the polymerization monomer and the surfactant is (150-: (10-20): (0.08-1.0): (1-10): (0.01-0.15): 100: (1-10); the oil phase comprises a dispersant, and the volume ratio of the dispersant to the water is 1: (1-5).

4. The composite superabsorbent polymer of claim 3, wherein the starch is corn starch or soluble starch.

5. The composite superabsorbent polymer of claim 3, wherein the dispersant is n-hexane.

6. The composite superabsorbent polymer of claim 3, wherein the surfactant is selected from one or more of sorbitol glycerin fatty acid, polyglycerin fatty acid ester, glyceraldehyde, and glyceryl oleate.

7. The composite superabsorbent polymer of claim 3, wherein the initiator is selected from one or more of potassium persulfate, sodium persulfate, and ammonium persulfate.

8. The composite superabsorbent polymer of claim 3, wherein the polymeric monomer is acrylic acid or a mixture of acrylic acid and sodium acrylate having a degree of neutralization of 60 to 80 mol%.

9. The composite superabsorbent polymer of claim 3, wherein the crosslinking agent is N, N' -methylenebisacrylamide.

10. A process for the preparation of a composite superabsorbent polymer according to any of claims 3 to 9, characterized in that it comprises the following steps:

1) mixing the starch and the water according to a weight ratio to prepare a starch water solution, gelatinizing, and cooling to 35-45 ℃ to obtain a starch gelatinization liquid;

2) mixing the dispersing agent and the surfactant, performing ultrasonic dispersion to obtain a suspension, adding the suspension into the starch pasting liquid obtained in the step 1), stirring, and introducing inert gas; then adding the initiator, the modified coal gangue, the polymerization monomer and the cross-linking agent in sequence, and heating to 50-70 ℃ under the condition of continuous stirring to perform reversed phase suspension polymerization for 1.5-4 hours to obtain a polymerization product;

3) dehydrating the polymerization product obtained in the step 2), washing with ethanol, filtering and drying to obtain the composite super absorbent polymer.

Technical Field

The invention relates to the technical field of composite super absorbent polymers, in particular to a composite super absorbent polymer containing coal gangue and starch and a preparation method thereof.

Background

The high water absorption polymer is a novel functional polymer material with super water retention capacity and water absorption capacity. The water-absorbing agent can absorb hundreds of times or even thousands of times of water by mass, the absorbed water is not easy to dehydrate after being pressed, and the water-absorbing agent has good market prospect and huge market demand and is widely applied to a plurality of fields such as agriculture and forestry, gardening, sanitation, medicine and the like.

The polyacrylic acid super absorbent polymer has the advantages of strong water absorption capacity, long shelf life and the like, and occupies a leading position in the world super absorbent resin market; however, the problems of high production cost, poor biodegradability, ecological environment pollution and the like are the common defects of the polyacrylic acid super absorbent resin. The composite super absorbent polymer with better comprehensive performance is prepared by compounding inorganic matters, natural high molecular materials and polyacrylic acid super absorbent polymers. Wherein, inorganic minerals such as zeolite, bentonite, kaolin and the like are compounded in the super absorbent polymer, which not only can reduce the cost, but also can effectively improve the gel strength, salt resistance and heat resistance. Polyacrylic acid/kaolin composite super absorbent polymer is prepared by using acrylic acid and kaolin as raw materials and adopting an aqueous solution polymerization method, wherein the highest water absorption capacity of the obtained product is 132 g/g.

Although the research on the composite super absorbent polymer has been made with some results, the research has been mainly focused on clay minerals, and the research on other types of minerals has been very limited. In addition, the liquid absorption performance of the composite super absorbent polymer is improved, but the comprehensive performance of the composite super absorbent polymer is still to be improved and the production cost is high. Therefore, it is necessary to find a super absorbent polymer which is inexpensive and excellent in all the properties such as water absorption property, water retention property and repeated use property.

Disclosure of Invention

In order to solve the defects, the invention provides the composite super absorbent polymer containing the coal gangue and the starch and the preparation method thereof. The composite super absorbent polymer containing starch and coal gangue has good water absorption performance, water retention performance and salt resistance.

In a first aspect, the invention provides a preparation method of modified coal gangue, which comprises the following steps:

a) thermal activation: grinding and sieving the coal gangue, then calcining, pouring the calcined coal gangue into water for quenching, carrying out vacuum filtration and drying.

Preferably, in step a), the sieving is performed using a 200 mesh sieve.

Preferably, in step a), the calcination conditions are: from 45-55 ℃, the temperature is programmed to 530 ℃ and 570 ℃ at the speed of 8-12 ℃/min, the temperature is preserved for 20-40min, then the temperature is raised to 580 ℃ and 820 ℃ at the speed of 8-12 ℃/min, the temperature is preserved for 1.5-2.5h, and the temperature is naturally reduced to 650 ℃.

Preferably, the water is distilled water.

b) Alkali modification: adding the coal gangue dried in the step 1) into a sodium hydroxide aqueous solution, performing reaction by adopting magnetic stirring, performing vacuum filtration, and drying to obtain the modified coal gangue.

Preferably, in step b), the mass fraction of sodium hydroxide in the aqueous sodium hydroxide solution is between 1.5 and 2.5%.

Preferably, in step b), the volume ratio of the addition amount of the dried coal gangue to the sodium hydroxide aqueous solution is g: l ═ (5-20): (0.8-1.5).

Preferably, in step b), the reaction temperature is 20-30 ℃ and the reaction time is 30-60 min.

Preferably, in step b), the temperature of the drying is 70-90 ℃.

In a second aspect, the invention provides a modified coal gangue obtained by the preparation method.

In a third aspect, the present invention further provides a composite super absorbent polymer obtained by polymerizing a reversed-phase suspension polymerization system, wherein the reversed-phase suspension polymerization system comprises an aqueous phase and an oil phase, the aqueous phase comprises water, starch, an initiator, the modified coal gangue as defined in claim 2, a cross-linking agent, a polymerization monomer and a surfactant, and the weight ratio of the water, the starch, the initiator, the modified coal gangue, the cross-linking agent, the polymerization monomer and the surfactant is (150-): (10-20): (0.08-1.0): (1-10): (0.01-0.15): 100: (1-10); the oil phase comprises a dispersant, and the volume ratio of the dispersant to the water is 1: (1-5).

Preferably, the volume ratio of the dispersant to the water is 1: 3.

preferably, the dispersant is n-hexane.

Preferably, the surfactant is selected from one or more of sorbitol glycerol fatty acid, polyglycerol fatty acid ester, glyceraldehyde and glyceryl oleate.

Preferably, the initiator is selected from one or more of potassium persulfate, sodium persulfate and ammonium persulfate.

Preferably, the polymerized monomer is acrylic acid or a mixture of acrylic acid and sodium acrylate having a neutralization degree of 60 to 80 mol%.

Preferably, the cross-linking agent is N, N' -methylenebisacrylamide.

In a fourth aspect, the present invention also provides a method for preparing the composite super absorbent polymer as described above, comprising the steps of:

1) mixing the starch and the water according to a weight ratio to prepare a starch water solution, gelatinizing, and cooling to 35-45 ℃ to obtain a starch gelatinization liquid;

preferably, the starch is corn starch or soluble starch.

Preferably, the mass fraction of starch in the starch water solution is 5-10%.

Preferably, the mass fraction of starch in the starch water solution is 5-8%.

Preferably, the gelatinization temperature is 85-95 ℃, and the gelatinization time is 30-60 min.

2) Mixing the dispersing agent and the surfactant, performing ultrasonic dispersion to obtain a suspension, adding the suspension into the starch pasting liquid obtained in the step 1), stirring, and introducing inert gas to keep the whole reaction process in an inert atmosphere; then adding the initiator, the modified coal gangue, the polymerization monomer and the cross-linking agent in sequence, and heating to 50-70 ℃ under the condition of continuous stirring to perform reversed phase suspension polymerization for 1.5-4h to obtain a polymerization product;

preferably, in step 2), the stirring speed is 200-400 rpm.

Preferably, in step 2), the inert gas is one or more of nitrogen, helium or argon.

3) Dehydrating the polymerization product obtained in the step 2), washing with ethanol, filtering and drying to obtain the composite super absorbent polymer.

In step 3), dehydration is carried out with acetone.

In step 3), the drying temperature is 70-90 ℃.

In summary, the invention provides a composite super absorbent polymer containing coal gangue and starch and a preparation method thereof, and the invention has the beneficial effects that:

1. the invention utilizes the violent thermal motion of each particle in the microstructure of the coal gangue at high temperature to dehydrate and decompose the components of the coal gangue, breaks through the chemical structure consisting of silicon-oxygen tetrahedron and aluminum-oxygen octahedron in the coal gangue, and leads the coal gangue not to be fully polymerized into long chains, thereby forming a great number of breaking points of free ends. The coal gangue calcined at high temperature contains a large amount of active silicon oxide and aluminum oxide, which are sources of the activity of the coal gangue. And then modifying the activated coal gangue by using NaOH. The coal gangue after high-temperature heat treatment is rich in a large amount of Al₂O₃And SiO₂The substances can interact with NaOH to generate sodium aluminate and sodium silicate, and the sodium aluminate and the sodium silicate have strong adsorbability; in addition, the coal gangue has a certain pore structure and more adsorption sites, and the increase of the adsorption sites can improve the reaction probability of the coal gangue and acrylic acid, so that the polymerization reaction is more sufficient. The invention solves the problem that the solid waste coal gangue is not easy to be compatible with the high polymer material, has important guiding significance for improving the comprehensive performance of the composite material, and lays a foundation for the application of the composite material in soil.

2. The composite super absorbent polymer obtained by the invention is added with starch and coal gangue which have wide raw material sources and low cost, so that the production cost is reduced, the comprehensive performance is excellent, and the application range is wide. The composite super absorbent polymer containing starch and coal gangue has good water absorption performance, water retention performance and salt resistance, and is particularly suitable for the fields of agriculture and forestry, environmental protection, gardens and the like. The invention has the advantages of and the like.

3. The composite super absorbent polymer has the capacity of absorbing distilled water of 400-476g/g at room temperature, the capacity of absorbing normal saline of 35-60g/g in 0.9% normal saline, and the water retention rates of 91.7%, 79.6% and 42.9% respectively after 16h at 25 ℃, 30 ℃ and 45 ℃ and has high water retention.

4. The invention adopts a reversed phase suspension method, optimizes reaction conditions and establishes a composite material preparation technology by investigating the influence of synthesis conditions on the performance of the composite material. The invention adopts the reversed phase suspension polymer system which can keep the reaction system stable within the range of operation conditions, has no adhesion and can be directly filtered for post-treatment operations such as washing, drying and the like. And the organic dispersion medium can be recycled, the reaction process is easy to control, and the method is suitable for industrial production.

Drawings

FIG. 1 is an XRD spectrum of the coal gangue raw powder in example 1.

FIG. 2 is an XRD spectrum of the modified coal gangue obtained in example 1.

FIG. 3 is an XRD spectrum of the composite super absorbent polymer comprising coal refuse and starch obtained in example 2.

FIG. 4 is an infrared image of the raw coal gangue powder of example 1.

FIG. 5 is an infrared image of the modified coal refuse obtained in example 1.

FIG. 6 is an SEM spectrum of the gangue raw powder in example 1.

FIG. 7 is an SEM spectrum of the modified coal gangue obtained in example 1.

FIG. 8 is a morphological diagram of the composite super absorbent polymer containing coal gangue and starch obtained in example 2 before and after swelling in distilled water.

FIG. 9 is a morphological diagram of the composite super absorbent polymer containing coal gangue and starch obtained in example 2 after swelling equilibrium in distilled water.

FIG. 10 is a graph showing swelling properties of the composite super absorbent polymer comprising coal refuse and starch obtained in example 2 in water and physiological saline.

FIG. 11 is a graph showing the water retention properties at 25 ℃ of the composite super absorbent polymer comprising coal refuse and starch obtained in example 2.

FIG. 12 is a graph showing the water retention properties at 30 ℃ of the composite super absorbent polymer comprising coal refuse and starch obtained in example 2.

FIG. 13 is a graph showing the water retention properties at 40 ℃ of the composite super absorbent polymer comprising coal refuse and starch obtained in example 2.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings of the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.