CN-121988294-A - Coal gasification slag-based porous sponge for uranium ore wastewater treatment and preparation method thereof

Abstract

The invention discloses a coal gasification slag-based porous sponge for uranium ore wastewater treatment and a preparation method thereof, relates to the fields of radioactive wastewater treatment and solid waste recycling, and aims to solve the technical problems of poor adsorption inertia, poor interface stability and insufficient selectivity of the existing coal gasification slag-based material in strong acid uranium ore wastewater. The preparation method comprises the technical key points of preparing an alkali solution, placing coal gas slag in the alkali solution for etching treatment, collecting the treated coal gas slag to obtain solid powder A, grinding and mixing the solid powder A with urea, performing pyrolysis treatment in a nitrogen atmosphere to obtain nitrogen-doped coal gas slag-based porous sponge B, placing the porous sponge B in a mixed acid solution of nitric acid and hydrochloric acid for carboxylation modification to obtain a sponge C with the surface rich in carboxyl groups, and immersing the sponge C in a PEI aqueous solution, wherein PEI is chemically bonded with the sponge through the carboxyl groups on the sponge C to obtain the coal gas slag-based porous sponge.

Inventors

• XIONG CHUAN
• YU JIAQI
• WEI LIGUO
• LV WENDONG
• DONG ZILONG
• Lv Bainian
• GUAN TIANBAO
• FENG ZHIYUAN

Assignees

• 黑龙江科技大学

Dates

Publication Date

20260508

Application Date

20260202

Claims (9)

1. 1. The preparation method of the coal gasification slag-based porous sponge is characterized by comprising the following steps of: Step 1, alkali-induced phase transition and deconstruction pretreatment, namely preparing alkali solution, placing gas slag into the alkali solution for etching treatment, and collecting the treated gas slag to obtain solid powder A; step 2, performing atmosphere induced pore-forming and skeleton in-situ recombination, namely grinding and mixing the solid powder A with urea, and performing pyrolysis treatment in a nitrogen atmosphere to obtain nitrogen-doped gas slag-based porous sponge B; Step 3, double-acid synergistic oxidation and defect site creation, namely placing the porous sponge B into a mixed acid solution of nitric acid and hydrochloric acid for carboxylation modification to obtain a sponge C with the surface rich in carboxyl groups; and 4, interfacial condensation and PEI covalent anchoring, namely immersing the sponge C into PEI aqueous solution, and chemically bonding PEI with the sponge through carboxyl on the sponge C to finally obtain the coal gasification residue-based porous sponge.
2. 2. The method according to claim 1, characterized by the steps of: Step 1, alkali-induced phase transition and deconstruction pretreatment, namely drying gas slag at 60 ℃ for 12 hours to thoroughly remove water, weighing 2g of dried sample, mixing with 200 mL of 5 mol/L NaOH solution prepared, stirring and reacting for 12 hours at 25 ℃, filtering after the reaction is finished, collecting solids, and drying again at 60 ℃ for 12 hours to obtain pretreated black solid powder A; Step 2, performing atmosphere induced pore-forming and skeleton in-situ recombination, namely grinding and mixing the solid powder A obtained in the step 1 with urea according to the mass ratio of 1 (0.5-1.5), and performing programmed temperature rise to 800 ℃ at the temperature rise rate of 5 ℃ per minute under the nitrogen atmosphere and constant-temperature calcination for 2 hours to obtain the nitrogen-doped gas slag-based porous sponge B; Step 3, preparing the porous sponge B obtained in the step 2 of 0.5 g, putting the porous sponge B into a 500 mL mixed acid solution consisting of 14 mol/L concentrated nitric acid of 62.6 mL and 12 mol/L concentrated hydrochloric acid of 42 mL, stirring for 12 hours at 25 ℃ at the rotating speed of 100 rpm, washing the porous sponge B to be neutral by deionized water after the reaction is finished, and drying the porous sponge B at 60 ℃ to obtain the sponge C with the surface rich in carboxyl groups; And 4, interfacial condensation and PEI covalent anchoring, namely weighing the sponge C obtained in the step 3 of 0.2 g, immersing the sponge C in a PEI aqueous solution with the pH of 50 mL and the pH of 6, wherein the concentration of the PEI aqueous solution is (1-4) g/L, reacting for 12 hours at the temperature of 25 ℃ and the rotating speed of 100 rpm, taking out the product after the reaction is finished, fully washing the product by deionized water, and performing freeze drying treatment to finally obtain the coal gasification slag-based porous sponge.
3. 3. The method according to claim 2, wherein the mass ratio of solid powder a to urea in step 2 is 1:1.
4. 4. The method according to claim 2, wherein the mass ratio of solid powder a to urea in step 2 is 1:1.5.
5. 5. A method according to claim 3, characterized in that the concentration of the aqueous PEI solution in step 4 is 1g/L.
6. 6. A method according to claim 3, characterized in that the concentration of the PEI aqueous solution in step 4 is 2g/L.
7. 7. A method according to claim 3, characterized in that the concentration of the aqueous PEI solution in step 4 is 4g/L.
8. 8. A coal gasification slag-based porous sponge, characterized in that it is prepared by the method of claim 1.
9. 9. Use of the coal gasification slag-based porous sponge of claim 8 in the treatment of uranium ore wastewater.

Description

Coal gasification slag-based porous sponge for uranium ore wastewater treatment and preparation method thereof Technical Field The invention relates to the technical field of radioactive wastewater treatment and solid waste recycling, in particular to a coal gasification slag-based porous sponge for uranium ore wastewater treatment and a preparation method thereof. Background Along with the rapid development of nuclear energy industry, uranium mining produces a large amount of strong acid uranium-bearing wastewater, and the uranium-bearing wastewater has complex components and strong corrosiveness, and if the uranium-bearing wastewater is improperly disposed, the environment and public health are seriously harmed. Although the adsorption method is simple and convenient to operate and low in cost, the adsorption method still faces two major bottlenecks when treating the wastewater, namely, the deep purification is difficult, the emission limit of 0.3 mg/L in the 'uranium metallurgy radiation protection and radiation environmental protection regulations' (GB 23727-2020) needs to be met, and the material is insufficient in acid resistance, such as active carbon, natural zeolite and the like, is easy to collapse in structure or inactivate functional groups in strong acid, and is difficult to stably adsorb for a long time. Meanwhile, the annual emission amount of the coal gas slag in China reaches 6000 to 8000 ten thousand tons, and a low-value utilization mode of piling or serving as building materials and the like is mainly adopted, so that a new way for high-value resource utilization is urgently required to be opened. Although the uranium-containing wastewater treated by using the gas slag has the potential of treating waste by waste, the direct application of the uranium-containing wastewater is still limited by the following technical difficulties: the technical difficulty is 1 that the silicon aluminum glass phase has structural contradiction of 'deep wall breaking' and 'macroscopic forming' of a porous framework: The gas slag is not a simple carbon ash mixture, and residual carbon crystallites thereof are tightly packed by dense aluminosilicate glass bodies to form an interlocking structure. The intrinsic structure is compact, the specific surface area is low, the surface chemical inertia is basically contradictory with the porous and high-surface-activity structure required by the efficient uranium adsorbent. Meanwhile, the surface of the material lacks functional groups with strong complexing ability on uranyl ions, and the material only depends on weak physical adsorption, so that deep purification cannot be realized. The prior modification technology has the defects that if strong acid/alkali deep etching is adopted to thoroughly break the glass phase (wall breaking), the internal carbon active sites can be exposed, but the inorganic cementing matrix can be damaged, so that the material is pulverized and a self-supporting porous whole can not be formed, and if the binder is introduced to maintain the molding strength, newly opened pores can be blocked, and the specific surface and the reactivity are reduced. Therefore, the key point is how to synchronously realize the deep breaking of the microscopic glass phase and the self-supporting forming of the macroscopic carbon skeleton on the premise of not introducing exogenous components, which is the primary difficult problem of improving the gas slag from loose powder to structural functional materials. Technical difficulty 2. Control contradiction between "interfacial stability anchoring" and "degree of freedom of segment conformation" of organic active layer in strong acid environment: In order to realize the specific identification of uranyl ions, flexible polymers such as Polyethylenimine (PEI) and the like are often introduced for modification. However, in the strongly acidic uranium mine wastewater, the construction of an inorganic-organic composite interface faces the problem that stability and activity are difficult to be compatible, if physical adsorption or low crosslinking modification is adopted, the chain segment conformation is kept free, active sites are fully exposed, but the interface is easy to dissociate under the action of strong acid, so that active components are quickly lost, the cycle life is short, and if a polymer is fixed on the surface of a carrier through high-density chemical crosslinking to enhance acid resistance, the chain segment movement is severely limited, the internal active sites are masked, and the adsorption capacity is remarkably reduced. Therefore, a key challenge is how to construct a stable interface on a rigid backbone that is both resistant to strong acid attack and maintains the freedom of movement of the flexible segments, which is a core bottleneck that pushes the materials toward engineering applications. The technical difficulty is 3 that the ionic competition and mass transfer retardation of trace uran