Preparation method and application of nano-nano composite mineral for deeply treating organic phosphorus and inorganic phosphorus in industrial wastewater

Abstract

The invention provides a preparation method and application of a nano-sub-nano composite mineral for deeply treating organic phosphorus and inorganic phosphorus in industrial wastewater, and belongs to the technical field of environmental functional materials. Iron-containing nano minerals, polyacrylonitrile fibers and rare earth nano minerals are used as raw materials, and the composite material is synthesized through the technologies of hydrogen reduction roasting, multi-element wet type ball milling, ultrasonic treatment, 3D printing and the like. After the 3D milli-sub-nano composite mineral is added into a water body, the sub-nano zero-valent rare earth composite mineral and the sub-nano zero-valent iron mineral on the surface and in pore channels of the 3D milli-sub-nano composite mineral can generate active oxygen free radicals to catalyze organic phosphorus to be efficiently converted into inorganic phosphorus. Meanwhile, stable phosphate crystals are rapidly formed through specific binding, the complex minerals can be protonated at low pH to adsorb and bind phosphorus ions through electrostatic force, the efficient phosphorus removal capacity is achieved, interference of different anions, cations and humic acid can be resisted, and a functional environmental engineering material is provided for advanced treatment of industrial wastewater.

Description

Technical Field

[0001] This invention belongs to the field of environmental functional materials technology, specifically relating to a method for preparing and applying a nano-to-micron composite mineral for the deep treatment of organic and inorganic phosphorus in industrial wastewater. Background Technology

[0002] Eutrophication is a serious global environmental problem, and excessive phosphorus levels are a key factor contributing to it. Reducing exogenous phosphorus input is crucial for curbing eutrophication in lakes and reservoirs. Exogenous phosphorus control technologies include coagulation and sedimentation, adsorption, biological treatment, and membrane treatment. Among these, adsorption has received widespread attention due to its simplicity, low cost, and high selectivity. However, organophosphates, especially organophosphates, are not only highly toxic but can also be converted into inorganic orthophosphates, posing a significant risk of eutrophication. Traditional methods often focus only on removing inorganic phosphorus such as orthophosphates, paying less attention to organophosphates. This results in traditional methods failing to effectively remove organophosphates when reducing exogenous phosphorus input, leaving behind a large source of inorganic phosphorus conversion and failing to fundamentally solve the problem of excessive phosphorus levels.

[0003] The complex components present in industrial wastewater, such as anions, cations, and humic acids, significantly interfere with traditional phosphorus removal materials, leading to a substantial decrease in their targeted phosphorus removal efficiency. Taking a typical rare-earth lanthanum composite bentonite material as an example, although this material has a high theoretical capacity for phosphorus adsorption, the high electron density anions (such as F⁻) in industrial wastewater compete with orthophosphate ions for active sites, resulting in a decline in phosphorus removal capacity. Furthermore, pressurized filtration processes are commonly used in industrial water treatment, and traditional materials, due to their high density, are prone to filter clogging and short-circuiting, leading to frequent material replacements and increased operating costs for enterprises. Current methods for preparing environmental functional materials often employ multi-element wet ball milling, ultrasonic treatment, and reduction calcination. While these methods can yield nanoscale or even sub-nanometer-scale active materials, they are susceptible to aggregation due to van der Waals forces and electrostatic interactions, resulting in reduced effective utilization of active sites.

[0004] To address the aforementioned issues, there is an urgent need to develop multi-metal-based composite sub-nano mineral materials that should possess the following characteristics: (1) low density to reduce filter load; (2) high density of surface active sites; and (3) enhanced material dispersibility and suppression of agglomeration through multi-metal synergy. Such materials are expected to improve phosphorus removal efficiency from industrial wastewater, achieve zero discharge of industrial wastewater, and reduce the operating costs of enterprises. Summary of the Invention

[0005] Rare earth minerals are metallic elements that are widely found in nature. They have a strong affinity for phosphates and have been extensively studied in the field of phosphorus removal due to their strong specific adsorption of phosphorus. The specific adsorption of phosphorus by rare earth minerals can form rare earth mineral-phosphate complexes, which still show high efficiency in removing phosphates even at trace levels.

[0006] Polyacrylonitrile (PA) fiber is a fibrous material with good tensile strength and toughness. During the spinning process, it undergoes chemical and physical treatment to form fibers with a fine structure. Compared to traditional steel bars or steel fibers, PA fibers have advantages such as light weight and corrosion resistance. They are chemically stable and exhibit high resistance to inorganic acids, bleaching powder, hydrogen peroxide, and common organic reagents. Furthermore, the nitrile groups abundant on the surface of PA fibers can generate carboxylic acids through hydrolysis and amines through reduction, thus leading to their wide application.

[0007] Furthermore, current research largely focuses on the removal of inorganic phosphorus such as orthophosphate, neglecting organic phosphorus components that can be converted into inorganic phosphorus such as phosphate, resulting in significant loopholes in phosphorus pollution control. In addition, phosphorus removal composite materials face multiple challenges in practical applications: on the one hand, they are susceptible to interference from other ions, affecting phosphorus removal efficiency; on the other hand, high-density phosphorus removal materials easily lead to filter clogging, increasing operation and maintenance costs; simultaneously, the materials themselves are prone to agglomeration, further reducing the utilization rate of active sites. These factors collectively limit the actual effectiveness of phosphorus removal technology and cannot fundamentally solve the problem of excessive phosphorus in industrial wastewater.

[0008] In view of this, the present invention provides a method for preparing nano-to-sub-nanometer composite minerals for the deep treatment of organic and inorganic phosphorus in industrial wastewater. Using rare earth minerals and iron-containing nano-minerals as raw materials, the method employs a hydrogen reducing atmosphere for calcination. Using nano-zero-valent iron / rare earth composite minerals as the bulk nano-mineral material, and adding a grinding aid, the method utilizes a multi-element wet ball milling method to obtain sub-nanometer zero-valent composite minerals. Polyacrylonitrile fibers are used as a carrier to form sub-nanometer zero-valent rare earth minerals and sub-nanometer zero-valent iron minerals with defective, weakly crystalline structures, generating reactive oxygen free radicals. Furthermore, polyacrylonitrile fibers can increase the number of active sites, reduce the density of the composite material, enhance its anti-interference ability in industrial wastewater, and enhance its catalytic hydrolysis ability for organophosphates. This allows for the simultaneous removal of both inorganic and organic phosphorus, fundamentally solving the pollution problem of excessive phosphorus and saving on the additional environmental remediation costs associated with removing organic phosphorus. The pressureless 3D milli- and sub-nano composite minerals prepared by this invention are rich in millimeter, nano, and sub-nano structure pores, which provide more active adsorption centers and interconnected pore structures for ion diffusion. They can also be used to catalyze the hydrolysis of organic phosphorus and simultaneously chelate and adsorb inorganic phosphorus through sub-nano zero-valent rare earth minerals and sub-nano zero-valent iron minerals, which is also a major feature of polyacrylonitrile fibers.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] A method for preparing milli-to-sub-nanometer composite minerals for the deep treatment of organic and inorganic phosphorus in industrial wastewater, comprising the following steps:

[0011] S1. The iron-containing nano-minerals, lanthanum-containing nano-minerals, cerium-containing nano-minerals, neodymium-containing nano-minerals, scandium-containing nano-minerals and yttrium-containing nano-minerals are crushed and sieved respectively, mixed in a certain weight ratio, and then calcined under a reducing atmosphere to obtain nano-zero-valent iron / rare earth composite minerals.

[0012] S2. Using nano-zero-valent iron / rare earth composite minerals as the bulk nano-minerals, wet ball milling is performed in a nano-sand mill with the addition of grinding balls and grinding aids to obtain liquid-phase ball milling products.

[0013] S3. Add polyacrylonitrile fiber to the liquid-phase ball milling product and ultrasonically treat it to obtain a slurry-type polyacrylonitrile sub-nanometer zero-valent composite mineral.

[0014] S4. Using 3D printing technology, slurry-type polyacrylonitrile sub-nanometer zero-valent composite minerals are printed into spherical, sheet, or block products. Then, a certain amount of cement is sprayed on their surface, and after natural curing for a period of time, pressureless 3D milli-sub-nanometer composite minerals are obtained.

[0015] The pressureless 3D milli-to-sub-nano composite minerals prepared in this invention have high defect density and incomplete crystal structures in the sub-nano-scale iron, yttrium, neodymium, scandium, lanthanum, and cerium particles, resulting in higher adsorption energy and stronger reactivity. This makes the iron, yttrium, neodymium, scandium, lanthanum, and cerium sub-nano particles loaded in the pressureless 3D milli-to-sub-nano composite minerals more effective at catalytic hydrolysis of organophosphates. Moreover, unlike the adsorption of organophosphonates, the weakly crystalline iron, yttrium, neodymium, scandium, lanthanum, and cerium sub-nano particles in the pressureless 3D milli-to-sub-nano composite minerals, after catalytic hydrolysis of organophosphonates, produce orthophosphate, the hydrolysis product of which is fixed on the surface of the sub-nano particles of the pressureless 3D milli-to-sub-nano composite minerals. Furthermore, the orthophosphate complexes with iron, yttrium, neodymium, scandium, lanthanum, and cerium to ultimately generate FePO4, LaPO4, CePO4, YPO4, NdPO4, and ScPO4. Meanwhile, the structural pores in the pressureless 3D milli-nano composite minerals facilitate the diffusion of organophosphonates to the interaction sites of iron, yttrium, neodymium, scandium, lanthanum, and cerium, providing spatial conditions for the catalytic hydrolysis and adsorption of organophosphonates.

[0016] The iron, yttrium, neodymium, scandium, lanthanum, and cerium in the pressureless 3D milli- to sub-nanometer composite minerals prepared in this invention are loaded onto millimeter-scale polyacrylonitrile fibers, facilitating morphology control through subsequent precipitation processes. The pore structure of the polyacrylonitrile fibers is unfavorable for the crystal growth of iron, yttrium, neodymium, scandium, lanthanum, and cerium, easily forming a weak crystalline structure with high defect density, thereby enhancing the catalytic hydrolysis of organophosphates into inorganic phosphorus. Furthermore, the pores of the polyacrylonitrile fibers facilitate the diffusion of organophosphates to the interaction sites of iron, yttrium, neodymium, scandium, lanthanum, and cerium, further enhancing the catalytic hydrolysis of organophosphates. Additionally, the accelerated crystal growth rate during preparation easily leads to the formation of small-sized, low-crystallinity, or amorphous iron, yttrium, neodymium, scandium, lanthanum, and cerium particles. In this case, the crystal structure is incomplete, with a high defect density, thus enhancing the catalytic hydrolysis ability of organophosphates.

[0017] As a preferred embodiment of the present invention, in step S1 of the preparation method, the iron-containing nano-minerals are selected from limonite, goethite, pyrite, siderite, or hematite; the lanthanum-containing nano-minerals are selected from borosilicate lanthanum ore; the cerium-containing nano-minerals are selected from Nipei stone; the neodymium-containing nano-minerals are selected from neodymium Yellow River ore; the scandium-containing nano-minerals are selected from scandium phosphate; and the yttrium-containing nano-minerals are selected from yttrium silicate beryllium ore. The nano-minerals are crushed and passed through a 220-mesh sieve to obtain nano-mineral powder with a particle size less than 0.075 mm, and mixed in a mass ratio of 5-10:5-10:4-8:1-7:1-6:1-5. The mixture is then calcined in a reducing atmosphere of hydrogen or carbon monoxide at a temperature of 500-1000℃ for 2-5 hours.

[0018] As a preferred technical solution of the present invention, in step S2 of the preparation method, grinding balls made of zirconium oxide (Mohs hardness grade: 6.5-8.5), silicon carbide (Mohs hardness grade: 9.5), and diamond (Mohs hardness grade: 10) with progressively increasing Mohs hardness are selected sequentially for three wet ball milling processes. The mass of the grinding balls added each time is 2-3 times the mass of the bulk nano-minerals. The grinding aid added before the first ball milling includes: 10-30 times the mass of the bulk nano-minerals of water, 0.01-0.03 times the mass of the bulk nano-minerals of dimethyl sulfoxide, and 0.01-0.03 times the mass of the bulk nano-minerals of diethylenetriamine. The first wet ball milling process using zirconia grinding balls with a particle size of 75-100μm takes 12-24 hours at a speed of 1000-2000 r / min. The second wet ball milling process using silicon carbide grinding balls with a particle size of 50-100nm takes 12-24 hours at a speed of 1000-2000 r / min. The third wet ball milling process using diamond grinding balls with a particle size of 5-10nm takes 12-24 hours at a speed of 1000-2000 r / min.

[0019] As a preferred technical solution of the present invention, in step S3 of the preparation method, the mass ratio of the added polyacrylonitrile fiber to the liquid-phase ball milling product is 1:9-12. After the polyacrylonitrile fiber is pulverized, it is passed through a 220-mesh sieve to obtain powder with a particle size of less than 0.075 mm. After addition, it is subjected to ultrasonic treatment at 100-1000W for 12-24 hours to obtain a slurry-type polyacrylonitrile sub-nanometer zero-valent composite mineral. The ultrasonic process further breaks down the sub-nanometer zero-valent composite mineral and allows it to enter the pores of the millimeter-sized polyacrylonitrile fiber.

[0020] As a preferred technical solution of the present invention, in step S4 of the preparation method, cement is sprayed on the surface of the 3D printed product according to the mass ratio of product to cement of 7:3, and then naturally cured for 10-30 days to obtain pressureless 3D milli-nano composite mineral.

[0021] Rare earth minerals exist primarily in the Earth's crust as nano-minerals. As fundamental building blocks of minerals, rare earth elements exist as ionic compounds within mineral lattices, forming essential components of nano-minerals. They also act as impurity elements, dispersing in rock-forming minerals and rare metal minerals through isomorphous substitution. The rare earth elements, yttrium, neodymium, scandium, lanthanum, and cerium, have high ionic charge density and readily hydrolyze to form hydroxide precipitates. The hydroxyl groups of alcohols can coordinate with metal ions, slowing the hydrolysis rate and improving the controllability of the reaction, thus forming a stable solution system. This creates conditions for iron, yttrium, neodymium, scandium, lanthanum, and cerium to enter the millimeter-scale pores of polyacrylonitrile fibers and form weakly crystalline structures with high defect density.

[0022] This invention uses iron-containing nano-minerals, polyacrylonitrile fibers, and rare earth nano-minerals as raw materials. Through hydrogen reduction roasting, multi-element wet ball milling, ultrasound, and 3D printing, a pressureless 3D milli-to-sub-nano composite mineral with a porous structure is synthesized. This achieves the loading of sub-nano zero-valent composite minerals. When the pressureless 3D milli-to-sub-nano composite minerals are added to water, the sub-nano zero-valent composite minerals on their surface and in the pores can quickly and specifically bind with organic and inorganic phosphorus in the water to form stable phosphate crystals. The composite minerals also protonate at low pH and adsorb and bind phosphorus ions by electrostatic force, exhibiting highly efficient phosphorus removal capabilities and resisting interference from different anions, cations, and humic acids.

[0023] The pressureless 3D milli-nano composite mineral prepared by this invention can be used for the simultaneous removal of organic and inorganic phosphorus. After the pressureless 3D milli-nano composite mineral is added into the water, the iron, yttrium, neodymium, scandium, lanthanum, and cerium in its channels quickly combine with the organic and inorganic phosphorus in the industrial wastewater, forming a stable complex through specific binding. The amine groups on the surface will also be protonated at low pH and adsorb organic and inorganic phosphorus by electrostatic force, thus exhibiting a highly efficient and synergistic ability to remove organic and inorganic phosphorus.

[0024] The specific treatment process involves loading pressureless 3D milli-nano composite minerals into a small cup or pressureless filter bed that simultaneously removes organic and inorganic phosphorus. The concentration of organophosphonates in the water to be treated is 1-10 mg / L, and the concentration of inorganic phosphorus is 1-50 mg / L. Competing ions Cl... - NO3 - SO4 2- HCO3 - Cu 2+ The concentrations of humic acid and fulvic acid are controlled at 10-100 mg / L; the pH value is 2-10; the amount of pressureless 3D milli-nano composite minerals added is 0.05 g / L-25 kg / L; the water samples containing organic phosphate esters and inorganic phosphorus are treated under stirring conditions, and after treatment reaction for 10-600 min or hydraulic retention time of 1-10 h, the concentrations of organic phosphorus and inorganic phosphorus in the treated industrial wastewater are both less than 0.02 mg / L.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1. The pressureless 3D milli-to-sub-nanometer composite mineral prepared by this invention is prepared by wet ball milling, which facilitates material synthesis. The obtained pressureless 3D milli-to-sub-nanometer composite mineral has chelating ability, thus exhibiting high adsorption capacity and catalytic degradation ability for organic and inorganic phosphorus. The primary amines on the surface of the pressureless 3D milli-to-sub-nanometer composite mineral are protonated under acidic conditions, exhibiting a positive charge state. They have electrostatic attraction ability for organic and inorganic phosphorus. The sub-nanometer zero-valent rare earth minerals and sub-nanometer zero-valent iron minerals on its surface and in its pores can quickly and specifically bind with organic and inorganic phosphorus in water to form stable phosphate crystals. This composite mineral also protonates at low pH and adsorbs and binds phosphorus ions by electrostatic force, exhibiting a highly efficient ability to simultaneously remove organic and inorganic phosphorus.

[0027] 2. This invention utilizes iron-containing nano-minerals, lanthanum-containing nano-minerals, cerium-containing nano-minerals, neodymium-containing nano-minerals, scandium-containing nano-minerals, and yttrium-containing nano-minerals. These are crushed and passed through a 220-mesh sieve to obtain powders with a particle size less than 0.075 mm. The aforementioned nano-minerals are mixed in a specific mass and subjected to high-temperature reduction calcination in a hydrogen atmosphere. The C, CO, CH4, and H2 generated during thermal decomposition at high temperature can penetrate into the pores of the nano-mineral particles, increasing the reaction rate and degree. Ultimately, the rare earth nano-mineral powder and the iron-containing nano-mineral powder are completely transformed into nano-zero-valent iron composite minerals and nano-zero-valent rare earth composite minerals. The surface-adsorbed water, zeolite water, crystal water, and structural water in the iron-containing nano-minerals and nano-rare earth composite minerals also decompose and vaporize at high temperatures, forming nano-structured rare earth composite minerals and nano-structured zero-valent iron composite minerals. These are porous particulate materials, thus enabling the one-step preparation of nano-zero-valent rare earth composite minerals and nano-zero-valent iron composite minerals.

[0028] 3. Currently, the main method for deep treatment of wastewater containing organophosphorus and inorganic phosphorus is fixed column adsorption, which relies on external pressure to achieve a certain water throughput efficiency. The pressureless 3D milli-to-sub-nanometer composite mineral prepared in this invention is rich in porous sub-nanometer zero-valent composite mineral structures and has a low density. It is not only suitable for fixed column adsorption but can also achieve high water flux and treatment efficiency under pressureless conditions. The pressureless 3D milli-to-sub-nanometer composite mineral is composed of sub-nanometer zero-valent rare earth composite minerals and sub-nanometer zero-valent iron composite minerals. This material has a sub-nanometer porous structure and high activity, and can be used as a catalyst and adsorbent for organophosphorus and inorganic phosphorus. It efficiently removes organophosphorus and inorganic phosphorus simultaneously. The method is simple, easy to operate, and low in cost. It is an environmentally friendly and green pressureless 3D milli-to-sub-nanometer composite mineral that can effectively resist interference from anions, humic acid, fulvic acid, and cations in industrial wastewater, and efficiently removes organophosphorus and inorganic phosphorus simultaneously.

[0029] 4. The pressureless 3D milli-to-sub-nanometer composite mineral prepared by this invention has a pore size of less than 1 nm. Besides its ability to adsorb inorganic phosphorus, it also exhibits the effect of catalytic hydrolysis of organophosphorus, simultaneously removing both inorganic and organic phosphorus. This is achieved by regulating the defect morphology of sub-nanometer zero-valent rare earth minerals and sub-nanometer zero-valent iron minerals to catalytically hydrolyze organophosphorus, especially for organophosphonates, which can be removed simultaneously through catalytic hydrolysis. Simultaneously, the porous nanostructure of polyacrylonitrile fibers allows organophosphonates to diffuse to the activation sites of the sub-nanometer zero-valent rare earth and iron minerals, enhancing the catalytic hydrolysis and adsorption of organophosphorus by these minerals. Polyacrylonitrile fibers not only catalyze the hydrolysis of organophosphonates but also adsorb and remove inorganic phosphorus present in industrial wastewater and generated during hydrolysis, resulting in a synergistic removal of both organic and inorganic phosphorus from industrial wastewater.

[0030] 5. XRD analysis of the pressureless 3D milli-to-sub-nanometer composite minerals prepared in this invention shows that the modified rare earth elements and iron-containing phases have wide and mixed crystal forms, indicating a high defect density and incomplete crystal structure. These rare earth elements and iron phases, with their high defect density and weak crystal structure, are more easily removed by the catalytic hydrolysis of organophosphates. Furthermore, the sub-nanometer-sized zero-valent rare earth minerals and zero-valent iron particles are uniformly dispersed on the surface of polyacrylonitrile fibers, solving the problems of easy agglomeration and deactivation of sub-nanometer zero-valent rare earth minerals and zero-valent iron minerals. Simultaneously, the loading of sub-nanometer zero-valent rare earth minerals and zero-valent iron minerals can be controlled by adjusting the mass ratio of the sub-nanometer zero-valent rare earth minerals and zero-valent iron to the polyacrylonitrile fibers, thereby increasing the number of active sites and improving the adsorption capacity and catalytic hydrolysis ability. Attached Figure Description

[0031] Figure 1 The X-ray diffraction (XRD) spectrum of the pressureless 3D milli-nano composite mineral prepared in Example 1.

[0032] Figure 2 Scanning electron microscope (SEM) image of the pressureless 3D milli-nano composite mineral prepared in Example 1.

[0033] Figure 3 The X-ray diffraction (XRD) spectrum of the pressureless 3D milli-nano composite mineral prepared in Example 2.

[0034] Figure 4 Scanning electron microscope (SEM) image of the pressureless 3D milli-nano composite mineral prepared in Example 2.

[0035] Figure 5 The X-ray diffraction (XRD) spectrum of the pressureless 3D milli-nano composite mineral prepared in Example 3.

[0036] Figure 6 Scanning electron microscope (SEM) image of the pressureless 3D milli-nano composite mineral prepared in Example 3.

[0037] Figure 7 The image shows the X-ray diffraction (XRD) spectrum of the pressureless 3D milli-nano composite mineral prepared in Example 4.

[0038] Figure 8 Scanning electron microscope (SEM) image of the pressureless 3D milli-nano composite mineral prepared in Example 4.

[0039] Figure 9 Scanning electron microscope (SEM) image of the pressureless 3D milli-nano composite mineral prepared in Example 5.

[0040] Figure 10 Scanning electron microscope (SEM) image of the pressureless 3D milli-nano composite mineral prepared in Example 6.

[0041] Figure 11 The image shows the relevant physical object. Detailed Implementation

[0042] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings.

[0043] Preparation Examples

[0044] Example 1:

[0045] A method for preparing milli-to-sub-nanometer composite minerals for the deep treatment of organic and inorganic phosphorus in industrial wastewater includes the following steps:

[0046] S1. Limonite, lanthanum borosilicate, niobite, neodymium ore, scandium phosphate, and yttrium silicoery are crushed and passed through a 220-mesh sieve to obtain powder with a particle size of less than 0.075 mm. They are then mixed in a mass ratio of 10:9:8:7:6:1 to obtain mixed iron / rare earth nano-mineral powder. The mixed iron / rare earth nano-mineral powder is then calcined at 600℃ under hydrogen for 2 hours to obtain nano-zero-valent iron / rare earth composite mineral.

[0047] S2. 500g of nano-zero-valent iron / rare earth composite mineral was used as the bulk nano-mineral and wet-milled in a nano-sand mill using zirconia grinding balls (particle size 100 μm, total weight 1kg). Distilled water, dimethyl sulfoxide, and diethylenetriamine were added as grinding aids (10kg, 10g, and 10g of the bulk nano-mineral content, respectively). A first wet ball milling was performed for 24 hours at a speed of 1000 r / min to obtain the wet-milled product. The grinding balls were then replaced with silicon carbide grinding balls (particle size 100nm, total weight 1kg), and a second wet ball milling was performed for 24 hours at a speed of 1000 r / min to obtain the second wet-milled product. Replace the grinding balls with diamond grinding balls (particle size 10nm, total weight 1kg), and perform three wet grinding processes. The wet grinding time is 24h and the rotation speed is 1000r / min to obtain the product from the three wet grinding processes.

[0048] S3. Add polyacrylonitrile fiber (crushed and passed through a 220-mesh sieve to obtain powder with a particle size less than 0.075 mm), with a mass ratio of polyacrylonitrile fiber to liquid-phase ball milling product of 1:9. Ultrasonically treat the polyacrylonitrile fiber and liquid-phase ball milling product at an ultrasonic intensity of 100 W for 12 h to obtain a slurry-type polyacrylonitrile sub-nanometer zero-valent rare earth composite mineral.

[0049] S4. The slurry-type polyacrylonitrile sub-nanometer zero-valent rare earth composite mineral is printed into spherical products using 3D printing technology. A certain amount of cement (the mass ratio of product to cement is 7:3) is sprayed onto the surface of the 3D printed mineral product, and it is naturally cured for 10 days to obtain pressureless 3D milli-sub-nanometer composite mineral.

[0050] Example 2:

[0051] A method for preparing milli-to-sub-nanometer composite minerals for the deep treatment of organic and inorganic phosphorus in industrial wastewater includes the following steps:

[0052] S1. Hematite, borosilicate lanthanum ore, niobite, neodymium ore, scandium phosphate, and yttrium silicoery are crushed and passed through a 220-mesh sieve to obtain powder with a particle size of less than 0.075 mm. They are then mixed in a mass ratio of 6:5:4:3:2:1 to obtain mixed iron / rare earth nano-mineral powder. The above mixed nano-iron / rare earth minerals are calcined at 700°C under hydrogen for 3 hours to obtain nano-zero-valent iron / rare earth composite minerals.

[0053] S2. 500g of nano-zero-valent iron / rare earth composite mineral was used as the bulk nano-mineral and wet-milled in a nano-sand mill using zirconia grinding balls (100μm particle size, 1kg total weight). Distilled water, dimethyl sulfoxide, and diethylenetriamine were added as grinding aids (10kg, 10g, and 10g respectively). The first wet-milling process was performed for 12 hours at a speed of 1200 rpm to obtain the first-stage wet-milled product. The grinding balls were then replaced with silicon carbide grinding balls (70nm particle size, 1kg total weight) for a second wet-milling process, which lasted 24 hours at a speed of 1200 rpm to obtain the second-stage wet-milled product. Replace the grinding balls with diamond grinding balls (particle size 5 nm, total weight 1 kg), and perform three wet grinding processes. The grinding time is 24 h and the rotation speed is 1200 r / min to obtain the product from the three wet grinding processes.

[0054] S3. Add polyacrylonitrile fiber (crushed and passed through a 220-mesh sieve to obtain powder with a particle size of less than 0.075 mm), with a mass ratio of polyacrylonitrile fiber to liquid-phase ball milling product of 1:10. Ultrasonically treat the polyacrylonitrile fiber and liquid-phase ball milling product at an ultrasonic intensity of 200 W for 12 h to obtain a slurry-type polyacrylonitrile sub-nanometer zero-valent composite mineral.

[0055] S4. The slurry-type polyacrylonitrile sub-nano zero-valent composite mineral is printed into spherical products using 3D printing technology. A certain amount of cement (the mass ratio of product to cement is 7:3) is sprayed onto the surface of the 3D printed mineral product and naturally cured for 15 days to obtain pressureless 3D milli-sub-nano composite mineral.

[0056] Example 3:

[0057] A method for preparing milli-to-sub-nanometer composite minerals for the deep treatment of organic and inorganic phosphorus in industrial wastewater includes the following steps:

[0058] S1. Pyrite, borosilicate lanthanum ore, niobite, neodymium ore, scandium phosphate, and yttrium silicoery are crushed and passed through a 220-mesh sieve to obtain powder with a particle size of less than 0.075 mm. They are then mixed in a mass ratio of 10:8:5:4:3:2 to obtain mixed iron / rare earth nano-minerals. The mixed nano-iron / rare earth minerals are then calcined at 800°C under hydrogen for 2 hours to obtain nano-zero-valent iron / rare earth composite minerals.

[0059] S2. 500g of nano-zero-valent iron / rare earth composite mineral was used as the bulk nano-mineral and wet-milled in a nano-sand mill using zirconia grinding balls (particle size 100μm, total weight 1kg). Distilled water, dimethyl sulfoxide, and diethylenetriamine were added as grinding aids (10kg, 10g, and 10g respectively). The first wet-milling process was performed for 24 hours at a speed of 1500 rpm, yielding the first-stage wet-milled product. The grinding balls were then replaced with silicon carbide grinding balls (particle size 50nm, total weight 1.5kg), and a second wet-milling process was performed for 24 hours at a speed of 1500 rpm, yielding the second-stage wet-milled product. Replace the grinding balls with diamond grinding balls (particle size 5nm, total weight 1.5kg), and perform three wet grinding processes. The wet grinding time is 24h and the rotation speed is 1500r / min to obtain the product from the three wet grinding processes.

[0060] S3. Add polyacrylonitrile fiber (crushed and passed through a 220-mesh sieve to obtain powder with a particle size less than 0.075 mm), with a mass ratio of polyacrylonitrile fiber to liquid-phase ball milling product of 1:9. Ultrasonically treat the polyacrylonitrile fiber and liquid-phase ball milling product at an ultrasonic intensity of 500 W for 12 h to obtain a slurry-type polyacrylonitrile sub-nanometer zero-valent composite mineral.

[0061] S4. The slurry-type polyacrylonitrile sub-nano zero-valent composite mineral is printed into spherical products using 3D printing technology. A certain amount of cement (the mass ratio of product to cement is 7:3) is sprayed onto the surface of the 3D printed mineral product and naturally cured for 15 days to obtain pressureless 3D milli-sub-nano composite mineral.

[0062] Example 4:

[0063] A method for preparing milli-to-sub-nanometer composite minerals for the deep treatment of organic and inorganic phosphorus in industrial wastewater includes the following steps:

[0064] S1. Siderite, borosilicate lanthanum silicosite, niobite, neodymium ore, scandium phosphate, and beryllium ore are crushed and passed through a 220-mesh sieve to obtain powder with a particle size less than 0.075 mm. These powders are then mixed with iron / rare earth nano-minerals in a mass ratio of 5:8:4:1:1:1 to obtain mixed iron / rare earth nano-mineral powder. This mixed iron / rare earth nano-mineral powder is calcined at 800℃ for 2 hours under hydrogen protection to obtain nano-zero-valent iron / rare earth composite minerals.

[0065] S2. 500g of nano-zero-valent iron / rare earth composite mineral was used as the bulk nano-mineral and wet-milled in a nano-sand mill using zirconia grinding balls (particle size 100μm, total weight 1kg). Distilled water, dimethyl sulfoxide, and diethylenetriamine were added as grinding aids (10kg, 10g, and 10g respectively). A first wet ball milling was performed for 24 hours at a speed of 1700r / min to obtain the wet-milled product. The grinding balls were then replaced with silicon carbide grinding balls (particle size 50nm, total weight 1.5kg) for a second wet ball milling, also for 24 hours at a speed of 1700r / min, to obtain the second wet-milled product. Diamond grinding balls (5 nm in diameter, 1.5 kg in total weight) were used to perform three wet grinding processes. The wet grinding time was 24 h and the rotation speed was 1700 r / min to obtain the product from the three wet grinding processes.

[0066] S3. Add polyacrylonitrile fiber (crushed and passed through a 220-mesh sieve to obtain powder with a particle size less than 0.075 mm), with a mass ratio of polyacrylonitrile fiber to liquid-phase ball milling product of 1:9. Ultrasonically treat the polyacrylonitrile fiber and liquid-phase ball milling product at an ultrasonic intensity of 400 W for 12 h to obtain a slurry-type polyacrylonitrile sub-nanometer zero-valent composite mineral.

[0067] S4. The slurry-type polyacrylonitrile sub-nano zero-valent composite mineral is printed into spherical products using 3D printing technology. A certain amount of cement (the mass ratio of product to cement is 7:3) is sprayed onto the surface of the 3D printed mineral product and naturally cured for 15 days to obtain pressureless 3D milli-sub-nano composite mineral.

[0068] Example 5:

[0069] A method for preparing milli-to-sub-nanometer composite minerals for the deep treatment of organic and inorganic phosphorus in industrial wastewater includes the following steps:

[0070] S1, goethite, borosilicate lanthanum silicosite, nipeite, neodymium ore, scandium phosphate, and yttrium silicosite were crushed and passed through a 220-mesh sieve to obtain powder with a particle size of less than 0.075 mm. The powder was then mixed with nano-iron / rare earth minerals in a mass ratio of 10:9:8:7:6:5. The nano-iron / rare earth minerals were calcined at 800℃ for 2 hours under hydrogen protection to obtain nano-zero-valent iron / rare earth composite minerals.

[0071] S2. 500g of nano-zero-valent iron / rare earth composite mineral was used as the bulk nano-mineral and subjected to a first wet ball milling process using zirconia grinding balls (particle size 100μm, total weight 1.5kg). Distilled water, dimethyl sulfoxide, and diethylenetriamine were added as grinding aids (10kg, 10g, and 10g respectively). The first wet ball milling process lasted 24 hours at a speed of 2000r / min, yielding the first wet ball milling product. The grinding balls were then replaced with silicon carbide grinding balls (particle size 100nm, total weight 1kg), and a second wet ball milling process was performed for 24 hours at a speed of 2000r / min, yielding the second wet ball milling product. Replace the grinding balls with diamond grinding balls (particle size 10nm, total weight 1kg), and perform three wet grinding processes. The wet grinding time is 24h and the rotation speed is 2000r / min to obtain the product from the three wet grinding processes.

[0072] S3. Add polyacrylonitrile fiber (crushed and passed through a 220-mesh sieve to obtain powder with a particle size less than 0.075 mm), with a mass ratio of polyacrylonitrile fiber to liquid-phase ball milling product of 1:9. Ultrasonically treat the polyacrylonitrile fiber and liquid-phase ball milling product at an ultrasonic intensity of 600 W for 24 h to obtain a slurry-type polyacrylonitrile sub-nanometer zero-valent composite mineral.

[0073] S4. The slurry-type polyacrylonitrile sub-nano zero-valent composite mineral is printed into spherical products using 3D printing technology. A certain amount of cement (the mass ratio of product to cement is 7:3) is sprayed onto the surface of the 3D printed mineral product and naturally cured for 20 days to obtain pressureless 3D milli-sub-nano composite mineral.

[0074] Example 6:

[0075] A method for preparing milli-to-sub-nanometer composite minerals for the deep treatment of organic and inorganic phosphorus in industrial wastewater includes the following steps:

[0076] S1. Limonite, lanthanum borosilicate, niobite, neodymium ore, scandium phosphate, and yttrium silicate are crushed and passed through a 220-mesh sieve to obtain powder with a particle size of less than 0.075 mm. The powder is then mixed with nano-iron / rare earth minerals in a mass ratio of 10:9:8:7:6:4. The mixed powder is then calcined at 900 °C for 4 hours under hydrogen protection to obtain nano-zero-valent iron / rare earth composite minerals.

[0077] S2. 500g of nano-zero-valent iron / rare earth composite mineral was used as the bulk nano-mineral and subjected to a first wet ball milling process using zirconia grinding balls (particle size 100μm, total weight 1kg). Distilled water, dimethyl sulfoxide, and diethylenetriamine were added as grinding aids (10kg, 10g, and 10g respectively). The first wet ball milling was performed for 24 hours at a speed of 2000r / min to obtain the first wet ball milling product. The grinding balls were then replaced with silicon carbide grinding balls (particle size 100nm, total weight 1kg), and a second wet ball milling was performed for 24 hours at a speed of 2000r / min to obtain the second wet ball milling product. Replace the grinding balls with diamond grinding balls (particle size 10nm, total weight 1kg), and perform three wet grinding processes for 24 hours at a speed of 2000r / min to obtain the three wet grinding products.

[0078] S3. Add polyacrylonitrile fiber (crushed and passed through a 220-mesh sieve to obtain powder with a particle size less than 0.075 mm), with a mass ratio of polyacrylonitrile fiber to liquid-phase ball milling product of 1:11. Ultrasonically treat the polyacrylonitrile fiber and liquid-phase ball milling product at an ultrasonic intensity of 600 W for 12 h to obtain a slurry-type polyacrylonitrile sub-nanometer zero-valent composite mineral.

[0079] S4. The slurry-type polyacrylonitrile sub-nano zero-valent composite mineral is printed into spherical products using 3D printing technology. A certain amount of cement (the mass ratio of product to cement is 7:3) is sprayed onto the surface of the 3D printed mineral product and naturally cured for 25 days to obtain pressureless 3D milli-sub-nano composite mineral.

[0080] Figure 1 The X-ray diffraction (XRD) spectrum of the pressureless 3D milli-to-sub-nanometer composite mineral prepared in Example 1 shows that the phases of the sub-nanometer zero-valent rare earth composite mineral and the sub-nanometer zero-valent iron composite mineral have wide and mixed crystal forms, indicating that they have high defect density and incomplete crystal structure. They belong to the rare earth elements and iron elements with weak crystal structure and high defect density. The rare earth elements and iron elements with defect structure are more easily removed by the catalytic hydrolysis of organophosphates.

[0081] Figure 2 SEM images of the pressureless 3D nano-to-sub-nano composite minerals prepared in Example 1; by Figure 2 The SEM images of (AB) show that its microstructure exhibits a stepped structure, a dense aggregate morphology, and stepped aggregate crystals at the edges. Further analysis at higher magnification... Figure 2 (CD) shows that there are a large number of sub-nano particles on its stepped microstructure. This is because these rare earth nanocomposite minerals and iron-containing nanominerals are formed into sub-nano zero-valent iron / rare earth composite mineral particles through hydrogen atmosphere reduction roasting, multi-element wet ball milling, ultrasound, and 3D printing. The wavy structure is the microstructure morphology of polyacrylonitrile fiber, indicating that the sub-nano zero-valent iron / rare earth composite mineral particles are successfully loaded in the pores of polyacrylonitrile fiber.

[0082] Figure 3 The X-ray diffraction (XRD) spectrum of the pressureless 3D milli-to-sub-nanometer composite mineral prepared in Example 2 shows that the phases of the sub-nanometer zero-valent rare earth composite mineral and the sub-nanometer zero-valent iron composite mineral have wide and mixed crystal forms, indicating that they have high defect density and incomplete crystal structure. They belong to the rare earth elements and iron elements with weak crystal structure and high defect density. The rare earth elements and iron elements with defect structure are more easily removed by the catalytic hydrolysis of organophosphates.

[0083] Figure 4 SEM image of the pressureless 3D milli-to-sub-nano composite mineral prepared in Example 2; by Figure 4 (AC) shows that its microstructure exhibits a plate-like morphology, which is characteristic of polyacrylonitrile fibers; Figure 4 (DE) Scattered plate-like and sheet-like microstructures can be observed. This is due to the reaction of nano-rare earth composite minerals and iron-containing nano-minerals in hydrogen reduction roasting, multi-element wet ball milling, ultrasonication, and crushing of polyacrylonitrile fibers. Figure 4 (FH) It can be seen that a large number of sub-nano zero-valent rare earth composite particles and sub-nano zero-valent iron composite particles are loaded on these sheet-like microstructures. The sub-nano zero-valent rare earth composite particles and sub-nano zero-valent iron composite particles are stacked together to form a sub-nano porous structure. It can be seen that polyacrylonitrile fiber can effectively prevent the agglomeration of sub-nano zero-valent rare earth particles and sub-nano zero-valent iron composite particles and improve the activity of pressureless 3D milli-sub-nano composite minerals.

[0084] Figure 5 The X-ray diffraction (XRD) spectrum of the pressureless 3D milli-to-sub-nanometer composite mineral prepared in Example 3 shows that the phases of the sub-nanometer zero-valent rare earth composite mineral and the sub-nanometer zero-valent iron composite mineral have wide and mixed crystal forms, indicating that they have high defect density and incomplete crystal structure. They belong to the rare earth element and iron phase with a weak crystal structure with high defect density. The rare earth element and iron phase with defect structure is more easily removed by the catalytic hydrolysis of organophosphates.

[0085] Figure 6 This is a SEM image of the pressureless 3D nano-to-sub-nano composite mineral prepared in Example 3. Figure 6 (AC) reveals that its microstructure exhibits a dense, blocky aggregate morphology, and these blocky shapes are characteristic of polyacrylonitrile fibers; at higher magnification... Figure 6 As can be seen from the microstructure of the pressureless 3D milli-to-sub-nanometer composite mineral, its dense blocky structure is loaded with a large number of sub-nanometer zero-valent rare earth composite mineral particles and sub-nanometer zero-valent iron composite particles. Analysis suggests that the dense blocky structure is the morphology of polyacrylonitrile fibers, which can effectively prevent the agglomeration of sub-nanometer zero-valent rare earth mineral particles and sub-nanometer zero-valent iron composite particles, thereby improving the activity of the pressureless 3D milli-to-sub-nanometer composite mineral.

[0086] Figure 7 The X-ray diffraction (XRD) spectrum of the pressureless 3D milli-to-sub-nanometer composite mineral prepared in Example 4 shows that the phases of the sub-nanometer zero-valent rare earth composite mineral and the sub-nanometer zero-valent iron composite mineral have wide and mixed crystal forms, indicating that they have high defect density and incomplete crystal structure. They belong to the rare earth elements and iron elements with weak crystal structure and high defect density. The rare earth elements and iron elements with defect structure are more easily removed by the catalytic hydrolysis of organophosphates.

[0087] Figure 8 SEM image of the pressureless 3D milli-to-sub-nanometer composite mineral prepared in Example 4; by Figure 8 (AB) shows that the pressureless 3D milli-to-subnanometer composite mineral contains a large number of fine, flaky subnanometer zero-valent composite mineral particles; from Figure 8 C shows that these tiny, sheet-like morphologies stack together to form sub-nanostructured pores. Figure 8 As can be seen from D, these sheet-like morphologies are loaded with a large number of sub-nanometer zero-valent rare earth particles and sub-nanometer zero-valent iron particles. Polyacrylonitrile fibers can effectively prevent the agglomeration of sub-nanometer zero-valent rare earth particles and sub-nanometer zero-valent iron particles, thereby improving the activity of pressureless 3D milli-sub-nanometer composite minerals.

[0088] Figure 9 This is a SEM image of the pressureless 3D nano-to-subnano composite mineral prepared in Example 5. (Source: [Insert SEM image here]) Figure 9 The SEM images of (AB) reveal its microstructure, exhibiting a sub-nano porous, plate-like morphology with pore sizes <1 nm. Sub-nano zero-valent rare earth minerals and sub-nano zero-valent iron particles are distributed on the surface of the polyacrylonitrile fibers. The high porosity and sub-nano structure facilitate water permeability and the catalytic hydrolysis and adsorption of inorganic phosphorus and organic phosphate ions. Figure 9(CD) shows that the pressureless 3D milli-to-sub-nanometer composite minerals possess sub-nanometer particle size and intergranular porous structure. This indicates that pressureless 3D milli-to-sub-nanometer composite minerals have been successfully synthesized by loading a mixture of goethite, lanthanum borosilicate, niobite, neodymium ore, scandium phosphate, and yttrium silicate iron / rare earth composite minerals into the pores of polyacrylonitrile fibers through reduction roasting, multi-element wet ball milling, water bath ultrasonication, and 3D printing techniques.

[0089] Figure 10 This is a SEM image of the pressureless 3D nano-to-sub-nano composite mineral prepared in Example 6. (Source: [Insert SEM image here]) Figure 10 (AB) shows that its microstructure exhibits sub-nano porous, plate-like morphology with pore sizes <1 nm. Sub-nano zero-valent rare earth composite minerals and sub-nano zero-valent iron composite minerals are loaded as sub-nano particles on the surface and within the internal pores of polyacrylonitrile fibers. The high porosity and sub-nano structure facilitate water permeability and promote the catalytic hydrolysis and adsorption of inorganic and organic phosphorus ions. From... Figure 10 CD reveals pressureless 3D milli-to-sub-nanometer composite minerals with sub-nanometer porous structure characteristics. This indicates that pressureless 3D milli-to-sub-nanometer composite minerals have been successfully synthesized by mixing limonite, lanthanum borosilicate, niobite, neodymium ore, scandium phosphate, and yttrium silicate, and then loading them into the pores of polyacrylonitrile fibers through reduction roasting, wet ball milling, water bath ultrasonication, and 3D printing technology.

[0090] Figure 11 This is a picture of the actual product. (Among them...) Figure 11 A is polyacrylonitrile fiber; Figure 11 B represents a nano-sand mill; Figure 11 CD is the stirring device at the discharge port of the nano-sand mill; Figure 11 E represents the slurry-type polyacrylonitrile sub-nanometer zero-valent composite mineral prepared in Example 1; Figure 11 F represents the slurry-type polyacrylonitrile sub-nanometer zero-valent composite mineral prepared in Example 2; Figure 11 G is the slurry-type polyacrylonitrile sub-nanometer zero-valent composite mineral prepared in Example 3; Figure 11 H represents the slurry-type polyacrylonitrile sub-nano zero-valent composite mineral prepared in Example 4.

[0091] Comparative Example 1:

[0092] Limonite, lanthanum borosilicate, niobite, polyacrylonitrile fiber, neodymium Yellow River ore, scandium phosphate, and yttrium silicate were crushed and passed through a 220-mesh sieve to obtain powder with a particle size of less than 0.075 mm, which were then used as adsorbents.

[0093] Comparative Example 2:

[0094] Limonite, lanthanum borosilicate, nipasite, polyacrylonitrile fiber, neodymium ore, scandium phosphate, and yttrium silicate were crushed and passed through a 220-mesh sieve to obtain powders with a particle size of less than 0.075 mm. These powders were then calcined in air at 600 °C for 2 hours to obtain air-calcined limonite, air-calcined lanthanum borosilicate, air-calcined polyacrylonitrile fiber, air-calcined nipasite, air-calcined neodymium ore, air-calcined scandium phosphate, and air-calcined yttrium silicate, which were then used as adsorbents.

[0095] Comparative Example 3:

[0096] The results were basically the same as Comparative Example 2, except that the roasting atmosphere was changed to N2. The following were obtained after N2 roasting: goethite, lanthanum borosilicate, pyroxene, neodymium ore, polyacrylonitrile fiber, scandium phosphate, and yttrium silicoery, which were then used as adsorbents.

[0097] Comparative Example 4:

[0098] The results were basically the same as Comparative Example 2, except that the roasting atmosphere was changed to H2. The following were obtained after roasting with H2: goethite, lanthanum borosilicate, pyroxene, neodymium ore, polyacrylonitrile fiber, scandium phosphate, and yttrium silicoery, which were then used as adsorbents.

[0099] Comparative Example 5:

[0100] Limonite, lanthanum borosilicate, nipeite, neodymium ore, polyacrylonitrile fiber, scandium phosphate, and yttrium silicate were crushed and passed through a 220-mesh sieve to obtain powder with a particle size of less than 0.075 mm. The powder was then mixed in a mass ratio of 10:9:8:7:6:5:4 and calcined in air at 600°C for 2 hours to obtain an air-calcined nano-iron / rare earth composite mineral.

[0101] Comparative Example 6:

[0102] The results are basically the same as Comparative Example 5, except that the roasting atmosphere is changed to N2 to obtain N2 roasted nano-iron / rare earth composite minerals.

[0103] Comparative Example 7:

[0104] The results are basically the same as Comparative Example 5, except that the roasting atmosphere is changed to H2 to obtain H2 roasted nano-zero-valent iron / rare earth composite minerals.

[0105] Comparative Example 8:

[0106] S1. Limonite, lanthanum borosilicate, niobite, neodymium ore, scandium phosphate, and yttrium silicate are crushed and passed through a 220-mesh sieve to obtain powder with a particle size of less than 0.075 mm. They are then mixed in a mass ratio of 10:9:8:7:6:5 to obtain mixed nano-iron / rare earth mineral powder. The nano-iron / rare earth mineral powder is then calcined at 600℃ under H2 for 2 hours to obtain nano-zero-valent iron / rare earth composite mineral.

[0107] S2. Using 3D printing technology, obtain 3D nano-nano zero-valent composite minerals.

[0108] Comparative Example 9:

[0109] S1. Limonite, borosilicate lanthanum silicosite, niobite, neodymium ore, scandium phosphate, and yttrium silicosite are crushed and passed through a 220-mesh sieve to obtain nano-mineral powder with a particle size of less than 0.075 mm. These nano-mineral powders are then mixed in a mass ratio of 10:9:8:7:6:5 to obtain mixed nano-iron / rare earth mineral powder. The mixed nano-iron / rare earth mineral powder is then calcined in air at 600°C for 2 hours to obtain nano-hematite / rare earth composite mineral.

[0110] S2. Using nano-hematite / rare earth composite mineral as the bulk nano-mineral, wet ball milling was performed in a nano-sand mill. The grinding balls were diamond balls, and the grinding aids were distilled water, dimethyl sulfoxide, and diethylenetriamine (added in the same proportion as in Example 1). One wet ball milling was performed for 24 hours at a rotation speed of 2000 r / min. Finally, polyacrylonitrile fiber (crushed and passed through a 220-mesh sieve to obtain powder with a particle size of less than 0.075 mm) was added. The mass ratio of polyacrylonitrile fiber to liquid-phase ball milling product was 1:9 to obtain a slurry-type polyacrylonitrile nano-composite mineral.

[0111] S3. Using 3D printing technology, 3D nano-nano composite minerals are obtained from slurry-type polyacrylonitrile nanocomposite minerals.

[0112] Comparative Example 10:

[0113] S1. Limonite, lanthanum borosilicate, niobite, neodymium Yellow River ore, scandium phosphate, and yttrium silicate are crushed and passed through a 220-mesh sieve to obtain nano-mineral powder with a particle size of less than 0.075 mm. The powder is then mixed with nano-iron / rare earth mineral powder in a mass ratio of 10:9:8:7:6:5.

[0114] S2. Using nano-iron / rare earth mineral powder as the bulk nano-mineral, wet ball milling is performed in a nano-sand mill. The grinding balls are diamond balls. Distilled water, dimethyl sulfoxide, and diethylenetriamine (addition ratio is the same as in Example 1) are added as grinding aids. The wet ball milling time is 24 hours and the rotation speed is 2000 r / min to obtain the wet ball milled product.

[0115] S3. Add polyacrylonitrile fiber (crushed and passed through a 220-mesh sieve to obtain powder with a particle size less than 0.075 mm), with a mass ratio of polyacrylonitrile fiber to wet ball milling product of 1:9. Ultrasonically treat the polyacrylonitrile fiber and wet ball milling product at an ultrasonic intensity of 500 W for 24 h to obtain a slurry-type polyacrylonitrile nanocomposite mineral.

[0116] S4. Using mineral slurry-polyacrylonitrile nanocomposite minerals as raw materials, 3D printing technology is used to obtain 3D nano-composite minerals.

[0117] Comparative Example 11:

[0118] S1. Limonite, lanthanum borosilicate, niobite, neodymium ore, scandium phosphate, and yttrium silicate are crushed and passed through a 220-mesh sieve to obtain nano-mineral powder with a particle size of less than 0.075 mm. The powder is then mixed with iron / rare earth composite mineral powder in a mass ratio of 10:9:8:7:6:5. The mixed iron / rare earth composite mineral powder is then calcined at 900 °C for 2 hours under nitrogen protection to obtain nanoporous rare earth composite mineral.

[0119] S2. Using nanoporous rare earth composite minerals as the bulk nanominerals, wet ball milling is performed in a nano-sand mill. The grinding balls are diamond balls, and grinding aids, including distilled water, dimethyl sulfoxide, and diethylenetriamine (addition ratio as in Example 1), are added. The wet ball milling time is 24 hours, and the rotation speed of the wet ball mill is 2000 r / min to obtain the wet ball milled product.

[0120] S3. Add polyacrylonitrile fiber (crushed and passed through a 220-mesh sieve to obtain powder with a particle size less than 0.075 mm), with a mass ratio of polyacrylonitrile to wet ball milling product of 1:10. Ultrasonically treat the polyacrylonitrile fiber and wet ball milling product at an ultrasonic intensity of 500 W for 24 h to obtain a slurry-type polyacrylonitrile nanocomposite mineral.

[0121] Comparative Example 12:

[0122] S1. Limonite, lanthanum borosilicate, niobite, neodymium ore, scandium phosphate, and yttrium silicoery are crushed and passed through a 220-mesh sieve to obtain nano-mineral powder with a particle size of less than 0.075 mm. The powder is then mixed with nano-iron / rare earth mineral powder in a mass ratio of 10:9:8:7:6:5. The mixed nano-iron / rare earth mineral powder is then calcined at 900 °C for 2 hours under nitrogen protection to obtain nano-iron / rare earth composite mineral.

[0123] S2. The nano-iron / rare earth composite mineral is used as the bulk nano-mineral and ball-milled in a nano-sand mill. The grinding balls are diamond balls (particle size of 10nm, total weight of 1kg). The dry ball milling time is 24h and the rotation speed is 2000r / min to obtain the nano-composite mineral.

[0124] S3. Using 3D printing technology, 3D nanocomposite minerals are obtained.

[0125] Comparative Example 13:

[0126] Limonite, lanthanum borosilicate, pyroxene, neodymium ore, scandium phosphate, and yttrium silicate were crushed and passed through a 220-mesh sieve to obtain nano-mineral powder with a particle size of less than 0.075 mm. The above materials were mixed in a mass ratio of 10:9:8:7:6:1. This mixture was then combined with polyacrylonitrile fiber at a 1:9 ratio and added to a three-necked flask. 1 L of distilled water was added to the flask, and the mixture was stirred in a N2 water bath for 20 min. Sodium borohydride (added at a mass five times the mass of the mixture) was added to the flask, and the mixture was stirred in a N2 water bath for 40 min. The resulting precipitate was obtained by vacuum filtration. The precipitate was washed twice with anhydrous ethanol and acetone, and then filtered again. The filtered precipitate was then dried in a vacuum drying oven at 40°C for 24 h to obtain polyacrylonitrile fiber-based nano-zero-valent iron / rare earth composite minerals.

[0127] Comparative Example 14:

[0128] Basically the same as Example 3, except that: only the first wet ball milling is performed in step S2; all other steps are the same.

[0129] Comparative Example 15:

[0130] Basically the same as Example 3, except that: only the first two wet ball milling processes are performed in step S2; all other steps are the same.

[0131] Comparative Example 16:

[0132] Basically the same as Example 3, except that no grinding aid is added during step S2; all other steps are the same.

[0133] Comparative Example 17:

[0134] S1. Hematite, lanthanum borosilicate, pyroxene, neodymium ore, scandium phosphate, and yttrium silicate are crushed and passed through a 220-mesh sieve to obtain powder with a particle size less than 0.075 mm. These powders are then mixed in a mass ratio of 6:5:4:3:2:1 to obtain mixed iron / rare earth nano-mineral powder. The above mixed nano-iron / rare earth minerals are calcined at 700°C under hydrogen atmosphere for 3 hours to obtain nano-zero-valent iron / rare earth composite minerals.

[0135] S2. 500g of nano-zero-valent iron / rare earth composite mineral was used as the bulk nano-mineral and wet-milled in a nano-sand mill using zirconia grinding balls (100μm particle size, 1kg total weight). Water (10kg added) was added as a grinding aid. The first wet-milling process lasted 12 hours at a speed of 1200 rpm, yielding the first-stage product. The grinding balls were then replaced with silicon carbide grinding balls (70nm particle size, 1kg total weight) for a second wet-milling process, lasting 24 hours at 1200 rpm, yielding the second-stage product. Finally, the grinding balls were replaced with diamond grinding balls (5nm particle size, 1kg total weight) for a third wet-milling process, lasting 24 hours at 1200 rpm, yielding the third-stage product.

[0136] S3. The product from the three wet ball milling processes is subjected to ultrasonic treatment with an ultrasonic intensity of 200W and an ultrasonic time of 12h to obtain a slurry-nano zero-valent composite mineral.

[0137] Comparative Example 18:

[0138] The steps are basically the same as those in Comparative Example 17 (S1-S3), except that step S4 is added, in which the slurry-subnanometer zero-valent composite mineral is pyrolyzed and roasted under a nitrogen atmosphere at 600℃ for 3 hours to obtain a nanoporous composite mineral.

[0139] Comparative Example 19:

[0140] The steps are basically the same as those in Comparative Example 17 (S1-S3), except that step S4 is added, in which the slurry-subnanometer zero-valent composite mineral is reduced and roasted in a hydrogen atmosphere at 600°C for 3 hours to obtain porous nano zero-valent composite mineral.

[0141] Comparative Example 20:

[0142] S1. Mix 10g of limonite with an average particle size of 25 nm as the bulk nano-mineral (Mohs hardness of 4-5.5), 10L of water, 20g of potassium borohydride, 12g of mixed rare earth minerals (denoted as grinding aid rare earth minerals, including 5g of borosilicate lanthanum silicospore, 4g of niobite, 1g of neodymium ore, 1g of scandium phosphate and 1g of yttrium silicospore, with an average particle size of 20nm) and 100g of diamond grinding balls (500nm in diameter). Ball mill the mixture once at 2000rpm for 24h under liquid nitrogen protection to obtain a single wet ball milling product.

[0143] S2. The product obtained from the first wet ball milling in step S1 is ultrasonicated at a power of 300W for 24 hours.

[0144] (3) Take out the ultrasonically processed wet ball milling product obtained in step S2 from the ultrasonic machine to obtain a slurry-type nano zero-valent iron / rare earth composite mineral.

[0145] Comparative Example 21:

[0146] S1. Mix 10g of limonite with an average particle size of 50nm (Mohs hardness 4-5.5), 10L of methanol, 12g of mixed nano-rare earth minerals (denoted as: grinding aid nano-rare earth minerals, including 5g of borosilicate lanthanum silicospore, 4g of niobite, 1g of neodymium ore, 1g of scandium phosphate, and 1g of yttrium silicate, with an average particle size of 10nm), and 500g of diamond balls (100nm in diameter). Perform a single wet ball milling at 1000rpm for 24h in a nano-sand mill. Obtain the product from the single wet ball milling.

[0147] S2. The product obtained from the one-time wet ball milling in step S1 was ultrasonically treated with 900W power for 24 hours. Then, it was centrifuged at 20000r / min for 1 hour. The centrifuged product was placed in an oven and dried at 105℃ for 48 hours to obtain nano-iron / rare earth composite minerals.

[0148] S3. The nano-iron / rare earth composite mineral obtained in step S2 is pyrolyzed and roasted under a helium atmosphere at 900℃ for 3 hours to obtain nano-iron / rare earth porous composite mineral.

[0149] Comparative Example 22:

[0150] S1. Mix 20g of limonite with an average particle size of 50 nm (Mohs hardness of 4-5.5), 10L of water, 200g of mixed nano-rare earth minerals (denoted as grinding aid nano-minerals, including 100g of borosilicate lanthanum silicospore, 70g of niobite, 10g of neodymium ore, 10g of scandium phosphate, and 10g of yttrium silicospore, with an average particle size of 25 nm), and 1000g of diamond grinding balls (diameter of 500nm). Perform a single wet ball milling at 2000rpm for 24h to obtain the single wet ball milling product.

[0151] S2. The wet ball milling product obtained in step S1 is ultrasonicated at a power of 900W for 24 hours to obtain the ultrasonicated wet ball milling product.

[0152] S3. The ultrasonically treated wet ball-milled product obtained in step S2 is centrifuged at 16000 rpm for 60 min to obtain nanocomposite minerals. The nanocomposite minerals are then dried in an oven at 105℃ for 24 h.

[0153] S4. The nanocomposite mineral is calcined at 800℃ in a hydrogen atmosphere for 3 hours to obtain nanoporous zero-valent iron / rare earth composite mineral.

[0154] Application Example 1

[0155] An example of the effect of static adsorption of organic and inorganic phosphorus in industrial wastewater is presented, with the following specific operating steps: A solution containing 1 mg / L of organic phosphate, 50 mg / L of inorganic phosphorus, and pH 7 was prepared. 0.3 g / L of the pressureless 3D milli-to-sub-nano composite minerals prepared in Examples 1-6 and the composite nano-mineral materials prepared in Comparative Examples 1-22 were added to the wastewater samples containing inorganic and organic phosphorus. The wastewater samples containing organic phosphate and inorganic phosphorus were treated under stirring conditions, and the removal rates of organic phosphate and inorganic phosphorus in the wastewater were measured after 1 hour of treatment.

[0156] Table 1

[0157] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Inorganic phosphorus removal rate (%) 100 100 100 100 100 100 Removal rate of organophosphates (%) 100 100 100 100 100 100

[0158] Table 1 shows that Examples 1-6 achieved a 100% removal rate for inorganic phosphorus and organophosphates, demonstrating high removal efficiency. This is because the pressureless 3D milli-to-sub-nanometer composite minerals prepared in this invention possess high activity and strong surface effects, exhibiting excellent purification performance in industrial water treatment and showing broad application prospects. Polyacrylonitrile fibers can immobilize sub-nanometer zero-valent rare earth minerals and sub-nanometer zero-valent iron particles through the mesh confinement effect, and have a pre-concentration effect on charged pollutants through the Donnan membrane effect, making them an ideal carrier for preparing pressureless 3D milli-to-sub-nanometer composite minerals. Pressureless 3D milli-to-sub-nanometer composite minerals using polyacrylonitrile fibers as carriers are typically prepared by hydrogen reduction roasting, multi-element wet ball milling, water bath ultrasound, and 3D printing, effectively treating organophosphates and inorganic phosphorus in industrial wastewater.

[0159] Table 2

[0160] Borosilicate Lanthanum Ore goethite Ni Peishi Neodymium Yellow River Mine Scandium phosphate Polyacrylonitrile fiber Silicoberyllium Yttrium Inorganic phosphorus removal rate (%) 53 18 40 32 37 21 51 Removal rate of organophosphates (%) 17 12 21 28 31 19 42

[0161] The natural rare earth mineral samples shown in Table 2, including limonite and polyacrylonitrile fiber (Comparative Example 1), exhibited relatively low activity and low removal efficiency for inorganic phosphorus and organic phosphate esters after unmodification.

[0162] Table 3

[0163] Air-roasted borosilicate lanthanum ore air-roasted limonite Ni Peishi after air roasting Air-baked polyacrylonitrile fibers Neodymium Yellow River ore after air roasting Scandium phosphate after air roasting air-roasted beryllium yttrium ore Inorganic phosphorus removal rate (%) 66 23 52 19 46 41 54 Removal rate of organophosphates (%) 19 15 27 21 32 35 50

[0164] The natural rare earth mineral samples shown in Table 3, limonite and polyacrylonitrile fiber (Comparative Example 2), exhibited relatively low activity after air roasting, with low removal efficiency for inorganic phosphorus and organic phosphate esters. This is because most of the rare earth mineral elements, limonite and polyacrylonitrile fiber, were oxidized after roasting, leading to a decrease in their activity.

[0165] Table 4

[0166] <![CDATA[N2 - Calcined ascharite]]> <![CDATA[Niobium pyrochroite after roasting]]> <![CDATA[Limonite after N2 roasting]]> <![CDATA[Polyacrylonitrile fiber after N2 calcination]]> <![CDATA[Neodymium Huanghe ore after roasting]]> <![CDATA[Scandium phosphate ore after N2 roasting]]> <![CDATA[Neodymium - Yttrium - Beryllium - Silicate after roasting]]> Inorganic phosphorus removal rate (%) 68 59 31 34 49 45 58 Removal rate of organophosphates (%) 23 24 29 27 35 47 50

[0167] The natural rare earth mineral samples shown in Table 4, limonite and polyacrylonitrile fiber (Comparative Example 3), exhibited relatively low activity after nitrogen roasting, resulting in low removal efficiency for inorganic phosphorus and organic phosphate esters. This is because most rare earth mineral elements, limonite and polyacrylonitrile fiber, are converted into elements with low activity after pyrolysis.

[0168] Table 5

[0169] <![CDATA[H2 - Calcined inyoite]]> <![CDATA[H2 - Roasted limonite]]> <![CDATA[Niobium Oxide after H2-calcination]]> <![CDATA[Polyacrylonitrile fiber after H2-calcination]]> <![CDATA[Neodymium Huanghe ore after H2-roasting]]> <![CDATA[H2 - Calcined xenotime]]> <![CDATA[H2 - Gadolinite after roasting]]> Inorganic phosphorus removal rate (%) 69 34 62 36 51 49 67 Removal rate of organophosphates (%) 26 26 34 29 33 50 56

[0170] Table 5 shows that the natural rare earth mineral samples, limonite and polyacrylonitrile fiber (Comparative Example 4), exhibited relatively low activity after hydrogen roasting, showing low removal efficiency for inorganic phosphorus and organophosphates. This is because most rare earth elements and iron elements, after hydrogen reduction roasting, formed nano-zero-valent rare earth composite minerals and nano-zero-valent iron composite materials. Compared to Comparative Example 1, their activity was significantly improved; however, they still exhibited low removal efficiency for inorganic phosphorus and organophosphates.

[0171] Table 6

[0172] Comparative Example 5 Comparative Example 6 Comparative Example 7 Comparative Example 8 Comparative Example 9 Comparative Example 10 Comparative Example 11 Comparative Example 12 Comparative Example 13 Inorganic phosphorus removal rate (%) 75 66 57 59 63 39 43 40 51 Removal rate of organophosphates (%) 31 30 41 52 60 38 55 53 56 Comparative Example 14 Comparative Example 15 Comparative Example 16 Comparative Example 17 Comparative Example 18 Comparative Example 19 Comparative Example 20 Comparative Example 21 Comparative Example 22 Inorganic phosphorus removal rate (%) 67 65 68 72 75 79 81 85 89 Removal rate of organophosphates (%) 63 62 66 69 73 76 78 73 70

[0173] Table 6 shows that Comparative Examples 5, 6, and 7 exhibit low removal efficiencies for organophosphates and inorganic phosphorus. Although their activity is improved compared to single-component rare earth minerals, their treatment efficiency is limited. Comparative Examples 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, and 22 also show low removal efficiencies for organophosphates and inorganic phosphorus. Although they lack some key steps compared to Examples 1-6, preventing the formation of pressureless 3D nano-to-nano composite minerals, their treatment efficiency is limited. Comparative Example 13, prepared using a liquid-phase reduction method, is a nano-mineral composite material that is prone to agglomeration, resulting in low removal efficiency for organophosphates and inorganic phosphorus.

[0174] Application Example 2

[0175] An example of the effectiveness of static adsorption of organic and inorganic phosphorus in industrial wastewater is presented, with the specific operating steps as follows: A solution containing 2 mg / L of organic phosphate esters and 10 mg / L of inorganic phosphorus is prepared, along with a solution containing competing ions (Cl). - NO3 - SO4 2- HCO3 - Cu 2+A mixture of humic acid and fulvic acid was prepared, with each interfering ion concentration of 15 mg / L and pH 7. 0.1 g / L of the pressureless 3D nano-nano composite minerals prepared in Examples 1-6 and the composite nano-mineral materials prepared in Comparative Examples 1-22 were added to a water sample containing organic phosphate esters and inorganic phosphorus industrial wastewater. The mixture was stirred and adsorbed at room temperature for 1 h. The supernatant was then taken to measure the concentrations of organic phosphate esters and inorganic phosphorus after the reaction, and the removal rate was calculated.

[0176] Table 7

[0177] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Inorganic phosphorus removal rate (%) 100 100 100 100 100 100 Removal rate of organophosphates (%) 100 100 100 100 100 100

[0178] Table 7 lists the presence of interfering ions Cl. - NO3 - SO4 2- HCO3 - Cu 2+ Humic acid and fulvic acid had no effect on the adsorption performance of the pressureless 3D milli-to-sub-nano composite minerals prepared in Examples 1-6. These results indicate that the pressureless 3D milli-to-sub-nano composite minerals still exhibit strong adsorption performance in the presence of competing ions. Under the same initial conditions, the pressureless 3D milli-to-sub-nano composite minerals have a relatively high adsorption capacity.

[0179] Table 8

[0180] Borosilicate Lanthanum Ore goethite Ni Peishi Polyacrylonitrile fiber Neodymium Yellow River Mine Scandium phosphate Silicoberyllium Yttrium Inorganic phosphorus removal rate (%) 21 14 23 15 26 28 31 Removal rate of organophosphates (%) 19 9 16 11 29 34 38

[0181] Table 8 shows the presence of interfering ions Cl. - NO3 - SO4 2- HCO3 - Cu 2+ Humic acid and fulvic acid significantly affected the adsorption effects of natural rare earth minerals, polyacrylonitrile fibers, and limonite in Comparative Example 1 on organophosphates and inorganic phosphorus. This indicates that the natural rare earth minerals, polyacrylonitrile fibers, and limonite, without modification, have low activity and cannot resist interference from different types of ions in water.

[0182] Table 9

[0183] air-roasted limonite Air-roasted borosilicate lanthanum ore Ni Peishi after air roasting Air-baked polyacrylonitrile fibers Neodymium Yellow River ore after air roasting Scandium phosphate after air roasting air-roasted beryllium yttrium ore Inorganic phosphorus removal rate (%) 28 34 32 11 23 26 29 Removal rate of organophosphates (%) 20 26 31 12 15 17 19

[0184] Table 9 lists the presence of interfering ions Cl. - NO3 - SO4 2- HCO3 - Cu 2+Humic acid and fulvic acid significantly affect the adsorption effects of the air-roasted rare earth nanominerals, air-roasted limonite, and air-roasted polyacrylonitrile fibers prepared in Comparative Example 2 on organic phosphate esters and inorganic phosphorus, and cannot resist interference from different types of ions in water. These results indicate that the composite nanominerals prepared in Comparative Example 2 have weak adsorption performance in the presence of competing ions.

[0185] Table 10

[0186] <![CDATA[Limonite after N2 roasting]]> <![CDATA[N2 - Calcined rhombohedral borosilicate lanthanum ore]]> <![CDATA[Ni-bearing pyrophyllite after roasting]]> <![CDATA[Polyacrylonitrile fiber after N2 roasting]]> <![CDATA[Neodymium Huanghe Ore after roasting]]> <![CDATA[Scandium phosphate ore after N2 roasting]]> <![CDATA[Gadolinite after N2 roasting]]> Inorganic phosphorus removal rate (%) 26 31 36 25 38 30 25 Removal rate of organophosphates (%) 24 11 21 19 12 17 18

[0187] Table 10 lists the presence of interfering ions Cl. - NO3 - SO4 2- HCO3 - Cu 2+ Humic acid and fulvic acid significantly affect the adsorption of organic phosphate esters and inorganic phosphorus by nitrogen-roasted rare earth nanominerals, nitrogen-roasted limonite, and nitrogen-roasted polyacrylonitrile fibers prepared in Comparative Example 3, and cannot resist the interference of different types of ions in water.

[0188] Table 11

[0189] <![CDATA[H2 - Roasted limonite]]> <![CDATA[H2 - Calcined ascharite]]> <![CDATA[Niobium pyrochroite after H2 roasting]]> <![CDATA[H2-Polyacrylonitrile fiber after roasting]]> <![CDATA[Neodymium Huanghe ore after H2-roasting]]> <![CDATA[H2 - Calcined thortveitite]]> <![CDATA[H2 - Gadolinite after roasting]]> Inorganic phosphorus removal rate (%) 28 32 35 28 31 36 37 Removal rate of organophosphates (%) 25 16 23 22 26 34 30

[0190] Table 11 lists the presence of interfering ions Cl. - NO3 - SO4 2- HCO3 - Cu 2+ Humic acid and fulvic acid significantly affect the adsorption of organic phosphate esters and inorganic phosphorus by the rare earth nanominerals, limonite, and polyacrylonitrile fibers prepared by hydrogen roasting in Comparative Example 4, and cannot resist the interference of different types of ions in water.

[0191] Table 12

[0192] Comparative Example 5 Comparative Example 6 Comparative Example 7 Comparative Example 8 Comparative Example 9 Comparative Example 10 Comparative Example 11 Comparative Example 12 Comparative Example 13 Inorganic phosphorus removal rate (%) 14 19 21 12 15 16 10 9 27 Removal rate of organophosphates (%) 17 20 25 18 26 28 31 34 37 Comparative Example 14 Comparative Example 15 Comparative Example 16 Comparative Example 17 Comparative Example 18 Comparative Example 19 Comparative Example 20 Comparative Example 21 Comparative Example 22 Inorganic phosphorus removal rate (%) 29 31 34 37 41 45 51 53 58 Removal rate of organophosphates (%) 33 38 39 42 44 47 49 40 50

[0193] Table 12 shows that Comparative Examples 5, 6, and 7 exhibited low removal efficiencies for organophosphates and inorganic phosphorus in the presence of interfering ions. Although their activity was improved compared to single-component rare earth nanominerals, limonite, or polyacrylonitrile fibers, their treatment efficiency was limited. Comparative Examples 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, and 22 also showed low removal efficiencies for organophosphates and inorganic phosphorus. Although they lacked some key steps compared to Examples 1-6, preventing the formation of pressureless 3D milli-to-sub-nano composite minerals, their treatment efficiency was limited and they could not resist interference from different types of ions in the water. Comparative Example 13, a composite material prepared by liquid-phase reduction, was prone to agglomeration, resulting in low removal efficiency for organophosphates and inorganic phosphorus and an inability to resist interference from different types of ions in the water.

[0194] Application Example 3

[0195] The solution contains 2 mg / L of organic phosphate ester and 1 mg / L of inorganic phosphorus, wherein Cl... - NO3 - SO4 2- HCO3 - Cu 2+ The concentrations of competing ions, namely humic acid and fulvic acid, were controlled at 60 mg / L, and the pH was 7 for industrial wastewater. The pressureless 3D nano-nano composite minerals prepared in Examples 1-6 and the composite nano-mineral materials prepared in Comparative Examples 1-22 were used as filter media, with each filter media weighing 10 kg. These media were loaded into plexiglass filter columns (cylindrical in shape; height 100 cm; inner diameter 5 cm; outer diameter 7 cm). The plexiglass filter columns were not sealed, and the flow rate was controlled by adjusting the liquid level of the mixed solution. The industrial wastewater flowed entirely by gravity. A dynamic adsorption experiment was conducted with a hydraulic retention time of 4 hours. The experiment ran for 10 days, and water samples were taken daily to measure the concentrations of organic phosphates and inorganic phosphorus in the effluent. The average removal rate over the 10-day experiment was calculated.

[0196] Table 13

[0197] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Average removal rate of inorganic phosphorus (%) 100 100 100 100 100 100 Average removal rate of organophosphates (%) 100 100 100 100 100 100

[0198] As shown in Table 13, under the condition of a hydraulic retention time of 4 hours, Examples 1-6 achieved an average removal rate of 100% for organic phosphate esters and inorganic phosphorus after 10 days of operation.

[0199] Table 14

[0200] goethite Borosilicate Lanthanum Ore Ni Peishi Polyacrylonitrile fiber Neodymium Yellow River Mine Scandium phosphate Silicoberyllium Yttrium Average removal rate of inorganic phosphorus (%) 11 14 18 10 12 10 23 Average removal rate of organophosphates (%) 7 17 19 9 21 24 27

[0201] As shown in Table 14, the natural rare earth nanomineral samples, limonite and polyacrylonitrile fiber (Comparative Example 1), have relatively low activity and low average removal rates for inorganic phosphorus and organic phosphate esters after unmodification.

[0202] Table 15

[0203] air-roasted limonite Air-roasted borosilicate lanthanum ore Ni Peishi after air roasting Air-baked polyacrylonitrile fibers Neodymium Yellow River ore after air roasting Scandium phosphate after air roasting air-roasted beryllium yttrium ore Average removal rate of inorganic phosphorus (%) 11 21 25 14 27 29 21 Average removal rate of organophosphates (%) 15 17 19 10 24 13 11

[0204] The natural rare earth mineral samples shown in Table 15, limonite and polyacrylonitrile fiber (Comparative Example 2), exhibited relatively low activity after air roasting, with a low average removal rate for inorganic phosphorus and organic phosphate esters. This is because most of the rare earth elements, limonite and polyacrylonitrile fiber, were oxidized after roasting.

[0205] Table 16

[0206] <![CDATA[Limonite after N2 roasting]]> <![CDATA[N2 - Calcined inyoite]]> <![CDATA[Ni-bearing pyrophyllite after roasting]]> <![CDATA[Polyacrylonitrile fiber after N2 roasting]]> <![CDATA[Neodymium Huanghe ore after roasting]]> <![CDATA[Scandium phosphate ore after N2 roasting]]> <![CDATA[Gadolinite after N2 roasting]]> Average removal rate of inorganic phosphorus (%) 15 23 20 18 21 17 11 Average removal rate of organophosphates (%) 12 16 13 17 11 10 9

[0207] The natural rare earth mineral samples shown in Table 16, limonite and polyacrylonitrile fiber (Comparative Example 3), exhibited relatively low activity after nitrogen roasting, with low average removal efficiency for inorganic phosphorus and organic phosphate esters. This is because most rare earth elements, iron elements and polyacrylonitrile fiber become less active after pyrolysis.

[0208] Table 17

[0209] <![CDATA[H2 - Roasted limonite]]> <![CDATA[H2 - Calcined inyoite]]> <![CDATA[Niobium pyrochroite after H2 roasting]]> <![CDATA[H2-Polyacrylonitrile fiber after roasting]]> <![CDATA[Neodymium Huangheite after H2-roasting]]> <![CDATA[H2 - Calcined xenotime]]> <![CDATA[H2 - Gadolinite after roasting]]> Average removal rate of inorganic phosphorus (%) 20 21 20 25 22 26 24 Average removal rate of organophosphates (%) 18 7 10 18 13 15 18

[0210] The natural rare earth nanomineral samples shown in Table 17, including limonite and polyacrylonitrile fiber (Comparative Example 4), exhibited relatively low activity and low average removal efficiency for inorganic phosphorus and organophosphates after hydrogen calcination. This is because most rare earth elements, limonite, and polyacrylonitrile fiber, after hydrogen reduction calcination, formed nano-zero-valent rare earth minerals, nano-zero-valent iron composite minerals, and porous carbon composite materials. Relatively speaking, their activity was significantly improved, but their average removal rate remained limited.

[0211] Table 18

[0212] Comparative Example 5 Comparative Example 6 Comparative Example 7 Comparative Example 8 Comparative Example 9 Comparative Example 10 Comparative Example 11 Comparative Example 12 Comparative Example 13 Average removal rate of inorganic phosphorus (%) 8 10 14 9 13 11 8 7 26 Average removal rate of organophosphates (%) 13 15 20 6 21 16 25 23 17 Comparative Example 14 Comparative Example 15 Comparative Example 16 Comparative Example 17 Comparative Example 18 Comparative Example 19 Comparative Example 20 Comparative Example 21 Comparative Example 22 Average removal rate of inorganic phosphorus (%) 18 20 23 31 35 38 40 43 45 Average removal rate of organophosphates (%) 28 27 19 29 30 32 33 36 38

[0213] Table 18 shows that Comparative Examples 5, 6, and 7 had low average removal rates of organophosphates and inorganic phosphorus. Although their activity was improved compared to single-component rare earth nanominerals, limonite, and polyacrylonitrile fibers, their average removal rates were limited. Comparative Examples 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, and 22 also had low average removal rates of organophosphates and inorganic phosphorus. Although they lacked some key steps compared to Examples 1-6, preventing the formation of pressureless 3D nano-nano composite minerals, their treatment efficiency was limited. Comparative Example 13, a composite material prepared by liquid-phase reduction, was prone to agglomeration, resulting in a low average removal rate of organophosphates and inorganic phosphates.

Claims

1. A method for preparing a nano-to-sub-nanometer composite mineral for the deep treatment of organic and inorganic phosphorus in industrial wastewater, characterized in that, The steps are as follows: S1. The iron-containing nano-minerals, lanthanum-containing nano-minerals, cerium-containing nano-minerals, neodymium-containing nano-minerals, scandium-containing nano-minerals and yttrium-containing nano-minerals are crushed and sieved respectively, mixed in a certain weight ratio, and then calcined under a reducing atmosphere to obtain nano-zero-valent iron / rare earth composite minerals. S2. Using nano-zero-valent iron / rare earth composite minerals as the bulk nano-minerals, wet ball milling is performed in a nano-sand mill with the addition of grinding balls and grinding aids to obtain liquid-phase ball milling products. S3. Add polyacrylonitrile fiber to the liquid-phase ball milling product and ultrasonically treat it to obtain a slurry-type polyacrylonitrile sub-nanometer zero-valent composite mineral. S4. Using 3D printing technology, slurry-type polyacrylonitrile sub-nanometer zero-valent composite minerals are printed into spherical, sheet, or block products. Then, a certain amount of cement is sprayed on their surface, and after natural curing for a period of time, pressureless 3D milli-sub-nanometer composite minerals are obtained.

2. The preparation method according to claim 1, characterized in that, In step S1, the iron-containing nanominerals are selected from limonite, goethite, pyrite, siderite, or hematite; the lanthanum-containing nanominerals are selected from borosilicate lanthanum ore; the cerium-containing nanominerals are selected from Nipei stone; the neodymium-containing nanominerals are selected from neodymium Yellow River ore; the scandium-containing nanominerals are selected from scandium phosphate ore; and the yttrium-containing nanominerals are selected from yttrium silicate beryllium ore.

3. The preparation method according to claim 1, characterized in that, In step S1, the particles are crushed through a 220-mesh sieve to obtain nano-mineral powder with a particle size of less than 0.075 mm. The nano-mineral powders are mixed in a mass ratio of 5-10:5-10:4-8:1-7:1-6:1-5.

4. The preparation method according to claim 1, characterized in that, In step S1, the reducing atmosphere is hydrogen or carbon monoxide, the calcination temperature is 500-1000℃, and the calcination time is 2-5h.

5. The preparation method according to claim 1, characterized in that, In step S2, grinding balls made of zirconium oxide (Mohs hardness grade: 6.5-8.5), silicon carbide (Mohs hardness grade: 9.5), and diamond (Mohs hardness grade: 10) with progressively increasing Mohs hardness are selected sequentially for three wet ball milling processes. The mass of the grinding balls added each time is 2-3 times the mass of the nano-minerals in the substrate. The grinding aid added before the first ball milling includes: 10-30 times the mass of water in the substrate nano-minerals, 0.01-0.03 times the mass of dimethyl sulfoxide in the substrate nano-minerals, and 0.01-0.03 times the mass of diethylenetriamine in the substrate nano-minerals.

6. The preparation method according to claim 5, characterized in that, In step S2, a primary wet ball milling process using zirconia grinding balls with a particle size of 75-100 μm takes 12-24 hours at a rotation speed of 1000-2000 r / min to obtain an intermediate product from the primary wet ball milling process; a secondary wet ball milling process using silicon carbide grinding balls with a particle size of 50-100 nm takes 12-24 hours at a rotation speed of 1000-2000 r / min to obtain an intermediate product from the secondary wet ball milling process; and a tertiary wet ball milling process using diamond grinding balls with a particle size of 5-10 nm takes 12-24 hours at a rotation speed of 1000-2000 r / min to finally obtain the wet ball milling product.

7. The preparation method according to claim 1, characterized in that, In step S3, the mass ratio of the added polyacrylonitrile fiber to the liquid-phase ball milling product is 1:9-12. After the polyacrylonitrile fiber is pulverized, it is passed through a 220-mesh sieve to obtain powder with a particle size of less than 0.075 mm. After addition, it is ultrasonically treated at 100-1000W for 12-24 hours to obtain a slurry-type polyacrylonitrile sub-nanometer zero-valent composite mineral. The ultrasonic process further breaks down the sub-nanometer zero-valent mineral and allows the sub-nanometer zero-valent composite mineral to enter the pores of the millimeter-sized polyacrylonitrile fiber.

8. The preparation method according to claim 1, characterized in that, In step S4, cement is sprayed onto the surface of the 3D printed product at a mass ratio of 7:3 between the product and cement, and then naturally cured for 10-30 days to obtain pressureless 3D milli-nano composite minerals.

9. The application of the nano-to-sub-nano composite minerals prepared by the method according to any one of claims 1-8 in the deep treatment of organic and inorganic phosphorus in industrial wastewater, characterized in that, When pressureless 3D milli-nano composite minerals are added to industrial wastewater, they generate active oxygen free radicals, which catalyze the efficient conversion of organic phosphorus into inorganic phosphorus. The iron, yttrium, neodymium, scandium, lanthanum, and cerium in the pores rapidly combine with the inorganic phosphorus in the water, forming a stable complex through specific binding. The amine groups on the surface also protonate at low pH and adsorb organic and inorganic phosphorus by electrostatic force, thus exhibiting a highly efficient and synergistic ability to remove organic and inorganic phosphorus.

10. The application as described in claim 9, characterized in that, Pressureless 3D milli-to-sub-nano composite minerals are loaded into beakers or pressureless filter beds for simultaneous removal of organic and inorganic phosphorus. The concentration of organophosphonates in the industrial wastewater to be treated is 1-10 mg / L, and the concentration of inorganic phosphorus is 1-50 mg / L. Competing ions Cl... - NO3 - SO4 2- HCO3 - Cu 2+ The concentrations of humic acid and fulvic acid are controlled at 10-100 mg / L; the pH value is 2-10; the amount of pressureless 3D milli-nano composite minerals added is 0.05 g / L-25 kg / L; the water samples containing organic phosphate esters and inorganic phosphorus are treated under stirring conditions, and the solutions after treatment reaction for 10-600 min are measured; or the hydraulic retention time is 1-10 h, and the solution is filtered through a pressureless filter bed, and the concentrations of organic phosphorus and inorganic phosphorus in the treated solution are both less than 0.02 mg / L.

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