CN-122010428-A - Magnetic geopolymer and preparation method and application thereof

Abstract

The invention discloses a magnetic geopolymer and a preparation method and application thereof, and relates to the technical fields of solid waste recycling and wastewater treatment. The preparation method comprises the steps of drying nickel slag, crushing and grinding, adding calcium oxide to regulate alkalinity, heating and melting to obtain nickel slag melt, carrying out water quenching on the nickel slag melt, drying, crushing and screening to obtain magnetic slag micro powder, mixing the magnetic slag micro powder with an alkaline excitant, injecting the magnetic slag micro powder into a mould for constant temperature maintenance, and carrying out demoulding and grinding to obtain the magnetic geopolymer. The magnetic geopolymer prepared by the invention has high adsorption capacity and rapid adsorption kinetics for various heavy metal ions in water, and has excellent magnetic separation performance.

Inventors

• CHEN QIAO
• NI RONG
• Ji Longxue
• Jin Haize
• ZHANG KAIYING
• YANG YANG
• ZHANG TINGHAI

Assignees

• 兰州理工大学

Dates

Publication Date

20260512

Application Date

20260204

Claims (9)

1. 1. A method for preparing a magnetic geopolymer, comprising the steps of: (1) Drying nickel slag, crushing and grinding, adding calcium oxide to adjust the alkalinity to 0.5-0.7, heating to 1500-1550 ℃ under air atmosphere or weak oxidizing atmosphere for melting and preserving heat to obtain nickel slag melt; (2) Quenching the nickel slag melt obtained in the step (1) in water, and drying, crushing and screening to obtain magnetic slag micro powder; or, cooling the nickel slag melt obtained in the step (1) to 1300-1350 ℃ at the temperature of 4-6 ℃ per min, then putting into water for quenching, and drying, crushing and screening to obtain magnetic slag micro powder; (3) Mixing the magnetic slag micropowder obtained in the step (2) with an alkaline activator, injecting into a mould with a preset shape, removing bubbles, maintaining at constant temperature, demolding, and crushing to obtain the magnetic geopolymer, wherein the alkaline activator consists of silica sol, sodium hydroxide and sodium metaaluminate.
2. 2. The method of producing a magnetic geopolymer according to claim 1, wherein in step (1), the heating rate is 5 to 10 ℃ per minute and the holding time is 1 to 2 h.
3. 3. The method of claim 1, wherein in the step (3), the magnetic slag micropowder is mixed with an alkali-activator to obtain a molar ratio of silicon, aluminum and sodium elements of 1-3:1:1.
4. 4. The method of producing a magnetic geopolymer according to claim 1, wherein in step (3), the maintenance is carried out at a constant temperature of 50 to 80 ℃ for 24 to 48 h.
5. 5. A magnetic geopolymer produced by the method of producing a magnetic geopolymer according to any one of claims 1 to 4.
6. 6. The use of the magnetic geopolymer according to claim 5 for the adsorption of heavy metal ions.
7. 7. The use according to claim 6, wherein the magnetic geopolymer is used for adsorbing heavy metal ions in a body of water.
8. 8. The use according to claim 7, wherein the adsorption conditions are normal temperature, ph=3-7, and the magnetic geopolymer input is 0.5-2.0 g/L.
9. 9. A heavy metal ion adsorbent comprising the magnetic geopolymer of claim 5.

Description

Magnetic geopolymer and preparation method and application thereof Technical Field The invention relates to the technical field of solid waste recycling and wastewater treatment, in particular to a magnetic geopolymer and a preparation method and application thereof. Background The nickel slag is solid waste generated in the nickel metallurgy process, 6-16 tons of nickel slag are generated per 1 ton of metallic nickel, the current deposited nickel slag amount in China is over 4000 ten thousand tons, and the nickel slag amount increases at a speed of 200 ten thousand tons each year. The nickel slag contains abundant valuable components such as iron, silicon, magnesium and the like (the total iron content is up to 35% -40%), but long-term stacking occupies a large amount of land, heavy metal ions migrate due to rain leaching, soil and groundwater are polluted, and resource waste and environmental risk are caused. The geopolymer is an inorganic high molecular material formed by activating an aluminosilicate raw material by an alkali excitant, has the advantages of a three-dimensional network structure, high specific surface area, good chemical stability and the like, and has wide application prospects in the fields of adsorption, catalysis, building materials and the like. Industrial solid waste is used for preparing the geopolymer, so that the material cost can be reduced, and the recycling of the solid waste can be realized. Meanwhile, the magnetic adsorption material has the advantages of high separation speed, simplicity and convenience in operation and the like, and is paid attention to in wastewater treatment, and the rapid magnetic separation of the adsorption material can be realized by introducing a magnetic phase into a geopolymer, so that the wastewater treatment efficiency is improved. Currently, there is some research on the use of nickel slag for the preparation of geopolymers. In the prior art, magnetic geopolymer is prepared by doping magnetic particles in the later stage, but the magnetic particles are not tightly combined with a geopolymer matrix, so that the magnetic particles are easy to fall off to cause the attenuation of adsorption performance and magnetic response performance, and meanwhile, magnetite phases naturally contained in nickel slag are not fully utilized, so that the preparation cost of the material is higher. In addition, the research in the prior art focuses on optimizing mechanical properties, so that the research for heavy metal adsorption is less, and the problems of low adsorption capacity, difficult separation, poor magnetic controllability and the like exist. Therefore, the preparation method of the magnetic geopolymer, which utilizes the self magnetic phase of the molten nickel slag, has simple process and excellent adsorption performance and magnetic separation performance, is developed, and has important significance for recycling the nickel slag and treating the heavy metal wastewater. Disclosure of Invention In order to solve the technical problems, the invention aims to provide a magnetic geopolymer, a preparation method and application thereof, wherein magnetite is separated out in situ in a melting process to serve as a magnetic source, the high activity of a quenched glass phase is utilized as a geopolymerization reaction source, the magnetic response performance of a material is regulated and controlled by combining a magnetic enhancer, the magnetic geopolymer is prepared through alkali excitation, and the obtained product has high adsorption capacity and rapid adsorption kinetics for various heavy metal ions in water, has excellent magnetic separation performance, and simultaneously solves the environmental problem of nickel slag storage. The technical scheme for solving the technical problems is as follows, and the preparation method of the magnetic geopolymer comprises the following steps: (1) Drying nickel slag, crushing and grinding, adding calcium oxide to adjust the alkalinity to 0.5-0.7, heating to 1500-1550 ℃ under air atmosphere or weak oxidizing atmosphere for melting and preserving heat to obtain nickel slag melt; (2) Quenching the nickel slag melt obtained in the step (1) in water, and drying, crushing and screening to obtain magnetic slag micro powder; or, cooling the nickel slag melt obtained in the step (1) to 1300-1350 ℃ at the temperature of 4-6 ℃ per min, then putting into water for quenching, and drying, crushing and screening to obtain magnetic slag micro powder; (3) Mixing the magnetic slag micropowder obtained in the step (2) with an alkaline activator, injecting into a mould with a preset shape, removing bubbles, maintaining at constant temperature, demolding, and crushing to obtain the magnetic geopolymer, wherein the alkaline activator consists of silica sol, sodium hydroxide and sodium metaaluminate. The core of the geopolymerization reaction is the dehydration condensation process between aluminosilicate, and silicon and aluminum