CN-122006500-A - Method for preparing porous geopolymer membrane by using fly ash at low cost

Abstract

The invention relates to the technical field of geopolymer film preparation and solid waste gas resource utilization, in particular to a method for preparing a porous geopolymer film by using fly ash with low cost, which comprises the following steps of (1) preparing geopolymer inorganic film aggregate; the invention not only efficiently utilizes the industrial solid waste of the fly ash through the matching of raw material selection, proportioning design and technological parameters, solves the problems of environmental pressure and resource waste caused by stacking, and greatly reduces the preparation cost and industrialization threshold of the porous geopolymer film by virtue of mild preparation conditions, a recyclable mold and a simple and easy-to-operate technological process, but also ensures the tightness and stability of the film assembly through the air tightness detection of the epoxy resin AB adhesive in the encapsulation link and the pressure of 0.20 MPa.

Inventors

• LIU YUHAN
• ZHANG WENJIE
• CHEN HAO

Assignees

• 桂林理工大学

Dates

Publication Date

20260512

Application Date

20260116

Claims (8)

1. 1. A method for preparing a porous geopolymer film by using fly ash at low cost, which is characterized by comprising the following steps: (1) The preparation of geopolymer inorganic membrane aggregate comprises the steps of weighing three raw materials of portland cement, fly ash and silicon dioxide, mechanically stirring for 10-20min at 600rpm, and uniformly mixing to obtain aggregate; (2) The preparation of the geopolymer inorganic membrane slurry comprises the steps of weighing sodium silicate solid with the modulus of 1.5, adding the sodium silicate solid into ultrapure water according to the solid-liquid ratio, heating in a water bath, stirring and dissolving to obtain an alkaline excitant, adding the excitant into the aggregate, and stirring for 15-25min at 1200rpm to obtain the geopolymer slurry; (3) Pouring the geopolymer slurry into a silica gel mold with a stainless steel screen to uniformly cover the geopolymer slurry on the screen and fill the pores of the screen, curing at 25 ℃, defoaming, and demolding to obtain a porous geopolymer inorganic film; (4) And packaging the geopolymer inorganic membrane, namely adhering the cured porous geopolymer inorganic membrane and the membrane end-sealing component through AB glue, standing for more than 24 hours until the glue layer is completely cured, detecting the air tightness of the assembled membrane by adopting air tightness leakage detecting equipment at the detection pressure of 0.20MPa, and repairing and re-detecting the assembled membrane by adopting a local glue supplementing method if an air leakage point exists until the leakage rate is less than or equal to 0.10 percent.
2. 2. The method according to claim 1, wherein the mass fraction ratio of portland cement, fly ash and silica in step (1) is (2-6): 2, the total fraction is 10, and wherein the mass fraction of silica is fixed to 2.
3. 3. The method according to claim 1, wherein the fly ash in step (1) has a particle size distribution in the range of 1.13 to 86.4 μm, portland cement has a particle size distribution in the range of 1 to 50 μm, and silica has 800 mesh powder.
4. 4. The method according to claim 1, wherein the mass of sodium silicate solids in step (2) is 25g-40g, the volume of ultrapure water is 100ml, and the mass fraction of the alkaline activator is 25-40% wt.
5. 5. The method according to claim 1, wherein the mass ratio of the alkali activator to the aggregate in step (2) is 0.55-0.65:1.
6. 6. The method according to claim 1, wherein the curing time in step (3) is 3-7d.
7. 7. The method of claim 1, wherein the AB glue in step (4) is an epoxy-based adhesive.
8. 8. A porous geopolymer membrane produced by the method of any one of claims 1 to 7, wherein the membrane is used for removing wastewater containing copper and cadmium heavy metal ions.

Description

Method for preparing porous geopolymer membrane by using fly ash at low cost Technical Field The invention relates to the technical field of geopolymer membrane preparation and solid waste gas resource utilization, in particular to a method for preparing a porous geopolymer membrane by using fly ash at low cost. Background Along with the advancement of global industrialization, the energy demand continuously rises, and China is taken as the large country of energy consumption, and coal still takes the dominant role in the energy structure. The data show that the coal in 2022 is 56.2% of the total energy consumption, 0.3% of the total energy consumption is increased in the last year, the total coal consumption is more than 54.7% of the global share, the annual coal yield is up to 4.496 hundred million tons, and the annual coal yield is increased by 2.9% in the same ratio. Under the energy supply pattern of coal energy long-term leading, mass solid wastes are generated in the process of mass combustion and utilization, wherein fly ash is the main solid waste discharged in the field of coal consumption such as thermal power generation, and 300kg of fly ash can be discharged per 1 ton of coal on average. The comprehensive utilization rate of the fly ash in China is only about 70%, a large amount of unutilized fly ash can only be treated in an open-air stockpiling mode, so that precious land resources are occupied, the atmosphere, water and soil can be polluted by dust emission, leakage and other ways, potential threat is formed to the ecological environment and human health, and the recycling and efficient utilization of the fly ash becomes an environment and resource problem to be solved urgently. Under the background of increasingly strict environmental protection policies and resource recycling concepts, the development of a fly ash high-value utilization technology becomes an industry research hotspot. The core of the geopolymer is that after the aluminosilicate material (natural minerals, solid wastes or industrial byproducts) is excited by acid or alkaline solution, the internal Si-O tetrahedron and the Al-O tetrahedron are connected through shared O atoms to form a three-dimensional network polymer, so that the geopolymer has excellent properties similar to ceramics, and has the advantages of low cost, high strength, environmental protection and high temperature resistance, and wide application prospect in a plurality of fields. Fly ash is an ideal raw material for preparing geopolymer as an industrial byproduct rich in silicon-aluminum components. The geopolymer crystalline phase prepared from fly ash comprises two parts, one part is the crystalline phase of the fly ash (such as mullite, quartz, feldspar and the like) and the other part is a new phase formed by the reaction of a fly ash glass phase and an alkali excitant (such as zeolite-A and natrolite structure (STS)), the strength is mainly provided by amorphous phase gel, the fly ash geopolymer has excellent hardness and strength thanks to the high polymerization degree and three-dimensional network structure of the gel, and the preparation process is usually carried out at normal temperature or in an environment slightly higher than normal temperature, and the energy consumption is obviously lower than that of the traditional ceramic material. In the field of separation and purification, inorganic membranes are widely applied due to the characteristics of high temperature resistance, long service life and high strength, wherein the traditional inorganic ceramic membrane is one of main stream products, but the membrane material has the defects of high raw material cost, high energy consumption in the preparation process requiring high-temperature sintering, easiness in generating greenhouse gas emission and the like, and the large-scale application of the membrane material in more fields is limited. The fly ash-based geopolymer film is used as a novel inorganic film material, not only inherits the core advantages of the inorganic film, but also effectively overcomes the defects of the traditional inorganic ceramic film by virtue of the low-cost characteristic, mild preparation conditions and environmental protection advantages without greenhouse gas emission of raw materials (fly ash), and becomes an important development direction of the inorganic film field. Meanwhile, the problem of heavy metal pollution caused by industrial wastewater discharge is increasingly remarkable, if the wastewater containing heavy metal ions such as copper, cadmium and the like is directly discharged without effective treatment, the ecological system is seriously damaged, and the heavy metal is easy to be enriched through a food chain to endanger human health. Therefore, the preparation method of the coal ash-based porous geopolymer film has the advantages of simple process, mild condition, low cost and reliable performance, and has important significance in solving the