Modified hydrated oxide adsorbent as well as preparation method and application thereof

Abstract

The invention provides a modified hydrated oxide adsorbent as well as a preparation method and application thereof. The method comprises the following steps: carrying out dehydration polymerization on a first metal hydrated oxide to obtain first metal hydrated oxide particles; the first metal hydrated oxide particles and a second metal ion solution are mixed to form a mixture, and the valence of first metal ions in the first metal hydrated oxide particles is different from the valence of second metal ions in the first metal hydrated oxide particles; and finally, carrying out aging modification on the mixture to obtain the modified hydrated oxide adsorbent. The preparation method provided by the invention does not need additional additives, the process is simple and pollution-free, and the adsorbent can keep high selectivity and high adsorption capacity, so that the preparation method has wide application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical metallurgy, and specifically relates to a modified hydrated oxide adsorbent and a preparation method and application thereof. Background Art

[0002] Vanadium is a metal element that is abundant in the earth's crust. Its content in the earth's crust is as high as 0.3%, generally 0.25% to 0.5%. It is mainly found in metal minerals such as iron, manganese and copper. Therefore, vanadium is one of the most abundant elements in nature. In the production process of the vanadium industry, a large amount of vanadium-containing waste will be generated, such as vanadium-containing wastewater and vanadium slag. If these wastes are not treated, they will not only cause serious pollution to the environment, but also waste precious vanadium resources. For example, vanadium-containing chromium wastewater is more common in the metallurgical and chemical industries. If it is directly discharged without treatment, it will cause serious pollution to the environment. Therefore, strengthening the recycling and utilization of vanadium-containing wastewater and waste is of great significance to ensure the sustainable supply of vanadium resources. For example: due to the low vanadium content of stone coal vanadium ore, the vanadium concentration in its leachate is also low, and enrichment and recovery methods are usually required to extract vanadium resources. Chromite is often accompanied by vanadium components. In the calcium-free roasting and leaching process, vanadium will enter the sodium chromate leaching solution. As an impurity, it will affect the properties of the chromium salt product, so it often needs purification treatment. In summary, it can be seen that it is of great significance to recover vanadium resources from vanadium-containing wastewater, stone coal vanadium leaching solution and sodium chromate leaching solution.

[0003] At present, the main method for recovering vanadium resources from vanadium-containing wastewater, stone coal vanadium leaching solution and sodium chromate leaching solution is chemical precipitation. Chemical precipitation methods generally include the following three methods: the first method is to add a reducing agent to reduce pentavalent vanadium to low-valent vanadium for precipitation, and then oxidize and leach the low-valent vanadium; the second method is to add excess calcium oxide to generate calcium vanadate precipitation, and then carbonate and leach the calcium vanadate precipitation; the third method is to add an adsorbent for selective recovery of vanadium resources.

[0004] Although the above chemical precipitation method can achieve a good effect of recovering vanadium resources, there are some problems: first, the reduction precipitation method is not suitable for precipitating low-valent vanadium from high-concentration sodium chromate leachate; second, although the method of adding excess calcium oxide to precipitate calcium vanadate is effective, the amount of calcium oxide added is often more than 10 times the theoretical amount, and it is only applicable to strong alkaline solutions. In addition, the above two chemical precipitation methods also have problems such as long process flow and low production efficiency, and both have no ion selectivity. This is due to the co-existence of vanadium ions and chromium ions in vanadium-containing wastewater and sodium chromate leachate, which leads to the co-precipitation of vanadium and chromium during the treatment process, thereby producing a large amount of V 5+ / Cr 6+ Hazardous solid waste.

[0005] The adsorption method is currently the most studied. For example, Chinese patents CN111455163A and CN101760651A both use alkaline anion exchange resins to adsorb and recover vanadium when treating acid leaching solution for extracting vanadium from stone coal. Chinese patent CN102337411A also discloses a method for recovering vanadium and chromium from high-chromium and low-vanadium vanadium precipitation wastewater, which specifically uses weakly alkaline or strongly alkaline ion exchange resins to adsorb vanadium and chromium in the wastewater. However, the existing resins for recovering vanadium by adsorption have poor selectivity.

[0006] In order to further improve the adsorption selectivity of vanadium ions, Chinese patent CN116715270A discloses a method for removing impurity ions in sodium dichromate mother liquor by using hydrated chromium oxide, specifically using hydrated chromium oxide to absorb and recover vanadium resources in sodium dichromate crystallization mother liquor; Chinese patent CN113198414A discloses a hydrated chromium oxide adsorbent, specifically using hydrated chromium oxide to adsorb vanadium in sodium chromate leachate. Although hydrated chromium oxide has good adsorption selectivity, its powdered particles need to be stirred, filtered, etc. for adsorption and separation operations, which makes the overall process operation cost high and the degree of automation low. In addition, under the action of mechanical force, the powdered adsorbent may accelerate the transformation and refinement of the crystal form, ultimately reducing its mechanical strength and service life.

[0007] Chinese patent CN102424421A discloses a devanadium bed and a method for devanadiumization of sodium chromate solution, which is to bond chromium hydroxide and glass flake binder to form granules, and finally prepare a granular adsorbent, thereby improving the strength of the adsorbent. This method operates the granular adsorbent in a fixed bed, thereby reducing the operating cost, but the powder particles are coated with polymers, which is not conducive to the further diffusion of the solution into the particles, thereby affecting the adsorption / desorption effect, and the polymer has no selectivity, resulting in poor selectivity of the granular adsorbent.

[0008] Therefore, there is an urgent need to develop a method to improve the strength of the adsorbent and extend its service life while ensuring that the adsorbent has high selectivity and high adsorption capacity. Summary of the invention

[0009] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a modified hydrated oxide adsorbent and its preparation method and application. The adsorbent prepared by the present invention first forms hydrated oxide particles by polymerization, thereby improving the strength of the adsorbent, and stabilizes the material structure by multi-metal mixed precipitation and surface modification of hydrated oxide particles, thereby extending the life of the adsorbent. In addition, the preparation method provided by the present invention does not require external additives, has a simple process and is pollution-free, so that the adsorbent can maintain high selectivity and high adsorption capacity, and therefore has broad application prospects.

[0010] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0011] In a first aspect, the present invention provides a method for preparing a modified hydrated oxide adsorbent, the method comprising the following steps:

[0012] S1. Dehydrating and polymerizing the first metal hydrated oxide to obtain first metal hydrated oxide particles;

[0013] S2. mixing the first metal hydrated oxide particles and the second metal ion solution to form a mixture, wherein the valence of the first metal ion in the first metal hydrated oxide particles is different from the valence of the second metal ion;

[0014] S3. The mixture is subjected to aging modification to obtain the modified hydrated oxide adsorbent.

[0015] First, the present invention dehydrates and polymerizes the first metal hydrated oxide so that it is compressed and aggregated, and the hydroxyl groups on the surface are partially dehydrated and polymerized to form first metal hydrated oxide particles. During the dehydration polymerization process, abundant mesoporous channels are formed, which provide more active sites for the adsorbent. In addition, new adsorption active sites can be further generated by subsequent treatment methods such as drying / drying or dissolving, thereby improving the strength and adsorption effect of the adsorbent. Secondly, the present invention performs aging and modification treatment on the first metal hydrated oxide particles and the second metal ion solution, so that the surface of the first metal hydrated oxide particles forms a layered structure composed of a partial bimetallic layer, an anion layer and an original surface layer. Among them, the bimetallic layer is mainly formed by replacing part of the first metal ions with the second metal ions, thereby generating new adsorption active sites. It can be seen that the present invention optimizes the layered structure and active sites on the surface of the first metal hydrated oxide particles through surface modification technology, thereby further improving the stability and adsorption effect of the adsorbent, while maintaining its high selectivity and high adsorption capacity.

[0016] Finally, the modified hydrated oxide adsorbent prepared by the present invention can be used for the adsorption and recovery of vanadium resources in vanadium-containing wastewater, stone coal vanadium extraction leaching solution and sodium chromate leaching solution under various conditions (pH value is in the range of 2-12), and the adsorbent can still maintain a good adsorption effect with high adsorption capacity and high selectivity after 10 cycles of adsorption, and the loss of the adsorbent is relatively small.

[0017] Preferably, the method for preparing the first metal hydrated oxide in step S1 comprises: mixing a first metal ion solution and a first alkaline solution for precipitation, and obtaining the first metal hydrated oxide after solid-liquid separation.

[0018] Preferably, the first metal ion solution is a trivalent metal ion solution.

[0019] Preferably, the trivalent metal ion solution includes any one of chromium ion, iron ion or aluminum ion or a combination of at least two thereof, preferably a combination of at least two of chromium ion, iron ion or aluminum ion, and typical but non-limiting examples of the combination include: a combination of chromium ion and aluminum ion, a combination of iron ion and aluminum ion, a combination of chromium ion and iron ion, and a combination of chromium ion, iron ion and aluminum ion, etc. The present invention preferably uses a combination of at least two trivalent metal ions, because it is preferred to use a combination of two or more trivalent metal ions mixed with an alkali solution for precipitation, and homogeneous substitution can occur between trivalent metals during precipitation, thereby destroying the integrity of the hydrated oxide lattice, thereby rapidly hydrolyzing and precipitating to generate disordered, fine, non-crystalline hydrated oxides with a large specific surface area and more active adsorption sites.

[0020] Preferably, the total concentration of trivalent metal ions in the trivalent metal ion solution is 0.01mol / L-1.5mol / L, for example, it can be 0.01mol / L, 0.02mol / L, 0.05mol / L, 0.08mol / L, 0.1mol / L, 0.2mol / L, 0.5mol / L, 0.8mol / L, 1.0mol / L, 1.1mol / L, 1.2mol / L, 1.3mol / L, 1.4mol / L, 1.5mol / L, etc.

[0021] Preferably, the concentration of the first alkali solution is 1mol / L-20mol / L, preferably 5mol / L-15mol / L, for example, it can be 1mol / L, 2mol / L, 4mol / L, 5mol / L, 6mol / L, 8mol / L, 10mol / L, 11mol / L, 13mol / L, 15mol / L, 18mol / L, 20mol / L, etc.

[0022] Preferably, the method of mixing the first metal ion solution and the first alkali solution for precipitation includes adding the first metal ion solution to the first alkali solution, or adding the first alkali solution to the first metal ion solution, or adding the first metal ion solution and the first alkali solution in parallel, preferably adding the first metal ion solution to the first alkali solution.

[0023] Preferably, solid-liquid separation is performed immediately after the mixed precipitation is completed.

[0024] Preferably, the mixed precipitation time is 0.1h-2h, preferably 0.2h-1h, for example, it can be 0.1h, 0.2h, 0.5h, 0.8h, 1h, 1.2h, 1.5h, 1.8h, 2h, etc.

[0025] Preferably, the temperature of the mixed precipitation is 25°C-95°C, preferably 50°C-80°C, for example, it can be 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, etc.

[0026] Preferably, the pH value of the mixed precipitation is 5-14, for example, it can be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, etc.

[0027] Since the disorderly generated non-crystalline hydrate has a large specific surface area and more adsorption active sites, the present invention preferably uses a combination of two or more trivalent metal ions and utilizes the homogeneous replacement phenomenon that occurs when the trivalent metal ions are mixed with alkali solution for precipitation to slow down the formation of crystalline hydrated oxides. This is because the difference in ionic radius will lead to the deterioration of the integrity of the hydrated oxide lattice, thereby inhibiting its crystallization process.

[0028] In the present invention, the preferred method of adding a trivalent metal ion solution to an alkali solution can rapidly cause hydrolysis and precipitation, thereby generating disordered, fine and non-crystalline hydrated oxides. Such non-crystalline hydrates have a large specific surface area and a large number of adsorption active sites, thereby improving their adsorption capacity. In the present invention, by optimizing the temperature, pH value, mixing time of the mixed precipitation, and the synergistic effect of liquid-solid separation and washing immediately after the mixing, the speed of the hydrolysis and precipitation reaction can be further accelerated, and the formation of crystalline hydrates can also be avoided.

[0029] Preferably, the dehydration polymerization method in step S1 includes pressurized dehydration and / or solidification dehydration.

[0030] Preferably, the process of pressurized dehydration includes pressurizing the first metal hydrated oxide for extrusion dehydration, and performing drying treatment after the extrusion dehydration is completed.

[0031] Preferably, the pressure of the pressurized dehydration is not less than 10 MPa, preferably not less than 20 MPa, more preferably not less than 50 MPa, for example, it can be 10 MPa, 12 MPa, 15 MPa, 18 MPa, 20 MPa, 30 MPa, 40 MPa, 50 MPa, 80 MPa, etc.

[0032] Preferably, the drying temperature is 1°C-60°C, for example, 1°C, 2°C, 5°C, 8°C, 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, etc.

[0033] Preferably, the solidification and dehydration process includes solidifying the water crystals in the first metal hydrated oxide and then dissolving and separating them.

[0034] Preferably, the temperature of the solidification dehydration is not higher than 0°C, preferably not higher than -5°C, more preferably not higher than -30°C, for example, it can be -50°C, -45°C, -40°C, -35°C, -30°C, -25°C, -20°C, -15°C, -10°C, -5°C, -2°C, -1°C, 0°C, etc.

[0035] Preferably, the dissolution temperature is 1°C-60°C, for example, 1°C, 2°C, 5°C, 8°C, 10°C, 20°C, 30°C, 40°C, 50°C, 60°C, etc.

[0036] In the present invention, the free water content of the hydrated oxide generated by the above mixed precipitation is as high as 70% or more. The preferred pressurized extrusion dehydration method is adopted so that the hydrated oxide itself is compressed and aggregated, thereby being able to effectively remove most of the free water in the disordered, fine and non-crystalline hydrated oxide. Under the preferred pressure conditions of the present invention, the hydroxyl part on the surface of the hydrated oxide undergoes dehydration polymerization to form hydrated oxide particles, and abundant mesoporous channels are formed during the dehydration polymerization process. The present invention further removes a small amount of residual water in the mesoporous channels through subsequent air drying or low-temperature drying, so that after the hydrated oxide particles are added with an aqueous solution, water molecules can quickly enter the interior of the particles and generate new adsorption active sites through hydration, thereby improving the strength and adsorption effect of the hydrated oxide particles.

[0037] In the present invention, the disordered, small and non-crystalline hydrated oxides are cured at low temperature, so that most of the free water in them condenses into ice crystals, and the volume of the ice crystals expands, causing the hydrated oxides to be gradually compressed and aggregated. Under the preferred curing temperature conditions of the present invention, the hydroxyl groups on the surface of the hydrated oxide undergo dehydration polymerization to obtain hydrated oxide particles. In this process, dehydration polymerization will form abundant mesoporous channels, thereby increasing the specific surface area and porosity of the adsorbent. Subsequently, the present invention releases free water by dissolving the ice crystals around the hydrated oxide particles and the ice crystals in the mesoporous channels at room temperature. This process not only helps to discharge excess water, but also further improves the strength and adsorption effect of the hydrated oxide particles through the active sites formed by the dissolution of ice crystals.

[0038] Preferably, in step S2, the second metal ions include divalent metal ions.

[0039] Preferably, the divalent metal ions include magnesium ions and / or calcium ions.

[0040] Preferably, the molar ratio of the second metal ion to the first metal ion is (0.1-2):1, preferably (0.2-1):1, for example, it can be 0.1:1, 0.12:1, 0.15:1, 0.18:1, 0.2:1, 0.22:1, 0.25:1, 0.28:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1, etc. The present invention regulates the molar ratio of the second metal ion to the first metal ion so that the surface of the amorphous hydrated oxide particles after aging and modification forms a partial bimetallic layered structure, and the first metal ion on the surface is partially replaced by the second metal ion, thereby inhibiting the conversion reaction of the amorphous hydrate to the crystalline hydrate, thereby improving the stability of the adsorbent, increasing the adsorption active sites and enhancing the adsorption effect of the adsorbent. If the molar ratio of the second metal ion to the first metal ion is low, the bimetallic layered structure will be reduced, and the number of first metal ions in the adsorbent that are partially replaced by the second metal ion will be reduced, so that the effect of inhibiting the conversion of amorphous hydrate to crystalline hydrate will be weakened, resulting in a reduction in the active sites of the adsorbent and a decrease in stability, which ultimately affects the adsorption effect; if the molar ratio of the second metal ion to the first metal ion is high, the first metal ion in the adsorbent will be replaced by a large amount of the second metal, thereby affecting the adsorption effect.

[0041] Preferably, the mixture in step S2 further includes a second alkali solution.

[0042] Preferably, the pH value of the mixture in step S2 is 8-13, for example, it can be 8, 9, 10, 11, 12, 13, etc.

[0043] Preferably, the temperature of the aging modification in step S3 is 40°C-120°C, preferably 50°C-90°C, for example, it can be 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, etc.

[0044] Preferably, the aging modification time in step S3 is 6h-48h, preferably 8h-24h, for example, it can be 6h, 8h, 10h, 12h, 15h, 18h, 20h, 22h, 24h, 28h, 30h, 32h, 34h, 38h, 40h, 42h, 44h, 48h, etc.

[0045] In the present invention, after the amorphous hydrated oxide particles are mixed with a divalent metal ion solution and an alkali solution and subjected to aging modification treatment, part of the trivalent metal ions on the surface of the amorphous hydrated oxide particles are replaced by divalent metal ions to form a partial bimetallic layer, and the bimetallic ions and the alkali solution modify the surface of the amorphous hydrated oxide particles to form a three-layer structure, specifically: the outermost layer is a double metal hydroxide layer composed of trivalent and divalent metal ions, the middle layer is an anion layer such as hydroxide, and the innermost layer is the surface layer of the original hydrated oxide particles. Since part of the trivalent metal ions are replaced by divalent metal ions, the lattice integrity of the crystalline hydrate is further destroyed, thereby adding new adsorption active sites.

[0046] The modified hydrated oxide adsorbent prepared by the present invention not only increases the specific surface area and the number of active sites of the adsorbent, but also enhances its adsorption capacity and stability for pollutants, while maintaining high selectivity and high adsorption capacity, thereby providing an effective solution for water treatment.

[0047] As a preferred technical solution of the present invention, the method comprises the following steps:

[0048] S1. adding a combined solution of at least two trivalent metal ions having a total concentration of 0.01 mol / L-1.5 mol / L to a first alkali solution having a concentration of 5 mol / L-15 mol / L for mixed precipitation, wherein the mixed precipitation time is 0.2 h-1 h, the mixed precipitation temperature is 50 ° C-80 ° C, the mixed precipitation pH value is 5-14, and solid-liquid separation is performed immediately after the mixed precipitation to obtain a trivalent metal hydrated oxide;

[0049] S2. subjecting the trivalent metal hydrated oxide to pressurized dehydration polymerization and / or solidification dehydration polymerization to obtain trivalent metal hydrated oxide particles; wherein the pressurized dehydration process comprises pressurizing the trivalent metal hydrated oxide for extrusion dehydration, the pressure of the pressurized dehydration is not less than 20 MPa, and drying is performed at 1-60°C after the extrusion dehydration is completed; and / or, the solidification dehydration process comprises solidifying the water crystals in the trivalent metal hydrated oxide and then dissolving and separating, the temperature of the solidification dehydration is not higher than -5°C, and the temperature of the dissolution is 1°C-60°C;

[0050] S3. Mix the trivalent metal hydrated oxide particles, the divalent metal ion solution and the second alkali solution to form a mixture with a pH value of 8-13, wherein the molar ratio of the divalent metal ions in the divalent metal ion solution to the trivalent metal ions in the combined solution of the at least two trivalent metal ions is (0.2-1):1; age and modify the mixture at 50°C-90°C for 8h-24h to obtain the modified hydrated oxide adsorbent.

[0051] In the present invention, the mixed precipitation, dehydration polymerization and aging modification process liquids in the above preparation method are subjected to water return treatment.

[0052] In the present invention, the first alkali solution and the second alkali solution used each independently exemplarily include sodium hydroxide solution, sodium carbonate or ammonia water.

[0053] In the present invention, the adsorbent can selectively adsorb vanadate from vanadium-containing wastewater, stone coal vanadium extraction leaching solution and sodium chromate leaching solution, and is also suitable for selective adsorption of anions such as silicate, phosphate and arsenate.

[0054] In a second aspect, the present invention provides a modified hydrated oxide adsorbent, wherein the modified hydrated oxide adsorbent is prepared by the method for preparing a modified hydrated oxide adsorbent according to the first aspect.

[0055] In a third aspect, the present invention provides an application of the modified hydrated oxide adsorbent according to the second aspect, wherein the modified hydrated oxide adsorbent is used for adsorbing and recovering vanadium from any one of vanadium-containing wastewater, stone coal vanadium extraction leaching solution or sodium chromate leaching solution.

[0056] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0057] Compared with the prior art, the present invention provides a method for preparing a modified hydrated oxide adsorbent, and has the following beneficial effects:

[0058] (1) The present invention can effectively regulate the hydrolysis reaction of the first metal ion by optimizing the mixed precipitation conditions, thereby generating a hydrated oxide with disorder, fineness, non-crystalline, large specific surface area and more adsorption active sites.

[0059] (2) The present invention dehydrates and polymerizes the hydrated oxide by preferably pressurized dehydration and / or low-temperature curing to form hydrated oxide particles with abundant mesoporous channels. This process does not introduce other substances, thus avoiding the problems of poor adsorption / desorption effect and poor selectivity that may be caused by the existing binder granulation technology. In addition, the present invention further forms new adsorption active sites by subsequent drying / baking or dissolving, thereby improving the strength and adsorption effect of the adsorbent.

[0060] (3) The present invention forms a layered structure consisting of a double metal layer, an anion layer and an original surface layer by aging the surface of the hydrated oxide particles. The formation of this structure is mainly through the replacement of some trivalent metal ions by divalent metal ions, thereby generating new adsorption active sites. This modification method not only enhances the stability of the adsorbent, but also significantly improves its adsorption effect, and finally obtains an adsorbent with high strength, long life, high adsorption capacity and high selectivity.

[0061] (4) The modified hydrated oxide adsorbent prepared by the present invention can be applied to the adsorption and recovery of vanadium resources in vanadium-containing wastewater, stone coal vanadium extraction leaching solution and sodium chromate leaching solution under various conditions (pH value is in the range of 2-12), and the adsorbent can still maintain a good adsorption effect with high adsorption capacity and high selectivity after 10 cycles of adsorption, and the loss of the adsorbent is relatively small. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 This is a process flow chart of the method for preparing a modified hydrated oxide adsorbent provided in Example 1 of the present invention.

[0063] Figure 2 This is a SEM characterization image of the first metal hydrated oxide particles provided in Example 1 of the present invention.

[0064] Figure 3 This is a SEM characterization image of the modified hydrated oxide adsorbent provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0065] The technical solution of the present invention is further described below by combining the accompanying drawings and specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0066] Example 1

[0067] This embodiment provides a modified hydrated oxide adsorbent and a preparation method thereof, such as Figure 1 As shown, the preparation method comprises the following steps:

[0068] S1. A solution of trivalent chromium ions having a concentration of 0.5 mol / L and trivalent iron ions having a concentration of 0.2 mol / L is added to a sodium hydroxide solution having a concentration of 8 mol / L for mixed precipitation. The mixed precipitation time is 0.5 h, the mixed precipitation temperature is 70 ° C, the mixed precipitation pH value is 9, and the mixed precipitation is immediately separated from the solid and liquid and washed to obtain a first metal hydrated oxide;

[0069] S2. The first metal hydrated oxide is extruded and dehydrated at a pressure of 50 MPa, and after the extrusion and dehydration, it is dried at 30 ° C to obtain a polymerization product such as Figure 2 The first metal hydrated oxide particles shown;

[0070] S3. Mix the first metal hydrated oxide particles, the divalent metal ion solution and the sodium hydroxide solution to form a mixture with a pH value of 9, wherein the divalent metal ion solution is a magnesium ion solution, and the molar ratio of the divalent metal ions in the divalent metal ion solution to the trivalent metal ions in step S1 is 0.5:1; and age and modify the mixture at 90° C. for 15 h to obtain Figure 3 The modified hydrated oxide adsorbent shown is in the form of nano-scale flakes.

[0071] Example 2

[0072] This embodiment provides a modified hydrated oxide adsorbent and a preparation method thereof, the preparation method comprising the following steps:

[0073] S1. A solution of trivalent chromium ions having a concentration of 0.8 mol / L, trivalent iron ions having a concentration of 0.25 mol / L, and trivalent aluminum ions having a concentration of 0.45 mol / L is added to a sodium hydroxide solution having a concentration of 20 mol / L for mixed precipitation. The mixed precipitation time is 0.4 h, the mixed precipitation temperature is 25 ° C, the mixed precipitation pH value is 8, and solid-liquid separation and washing are immediately performed after the mixed precipitation is completed to obtain a first metal hydrated oxide;

[0074] S2. The first metal hydrated oxide is extruded and dehydrated at a pressure of 200 MPa, and after the extrusion and dehydration, it is dried at 5 ° C to obtain a first metal hydrated oxide particle by polymerization;

[0075] S3. Mix the first metal hydrated oxide particles, the divalent metal ion solution and the sodium hydroxide solution to form a mixture with a pH value of 13, wherein the divalent metal ion solution is a calcium ion solution, and the molar ratio of the divalent metal ions in the divalent metal ion solution to the trivalent metal ions in step S1 is 0.1:1; age and modify the mixture at 120°C for 6 hours to obtain the modified hydrated oxide adsorbent.

[0076] Example 3

[0077] This embodiment provides a modified hydrated oxide adsorbent and a preparation method thereof, the preparation method comprising the following steps:

[0078] S1. A sodium hydroxide solution having a concentration of 1 mol / L is added to a solution having a concentration of 0.005 mol / L of trivalent chromium ions and a concentration of 0.005 mol / L of trivalent iron ions to perform mixed precipitation, the mixed precipitation time is 1 h, the mixed precipitation temperature is 95 ° C, the mixed precipitation pH value is 6, and the mixed precipitation is immediately separated from the solid and liquid and washed to obtain a first metal hydrated oxide;

[0079] S2. The first metal hydrated oxide is extruded and dehydrated at a pressure of 10 MPa, and after the extrusion and dehydration, the extrusion and dehydration are dried at 50 ° C to obtain first metal hydrated oxide particles by polymerization;

[0080] S3. Mix the first metal hydrated oxide particles, the divalent metal ion solution and the sodium hydroxide solution to form a mixture with a pH value of 8, wherein the divalent metal ion solution is a combined solution of magnesium ions and calcium ions, and the molar ratio of the divalent metal ions in the divalent metal ion solution to the trivalent metal ions in step S1 is 1:1; age and modify the mixture at 50°C for 24 hours to obtain the modified hydrated oxide adsorbent.

[0081] Example 4

[0082] This embodiment provides a modified hydrated oxide adsorbent and a preparation method thereof, the preparation method comprising the following steps:

[0083] S1. A solution of trivalent iron ions having a concentration of 0.6 mol / L and a solution of trivalent aluminum ions having a concentration of 0.4 mol / L are added to a sodium hydroxide solution having a concentration of 5 mol / L for mixed precipitation. The mixed precipitation time is 0.2 h, the mixed precipitation temperature is 50 ° C, the mixed precipitation pH value is 5, and solid-liquid separation and washing are immediately performed after the mixed precipitation is completed to obtain a first metal hydrated oxide;

[0084] S2. The first metal hydrated oxide is extruded and dehydrated at a pressure of 20 MPa, and after the extrusion and dehydration, the first metal hydrated oxide particles are obtained by polymerization;

[0085] S3. Mix the first metal hydrated oxide particles, the divalent metal ion solution and the sodium hydroxide solution to form a mixture with a pH value of 10, wherein the divalent metal ion solution is a combined solution of magnesium ions and calcium ions, and the molar ratio of the divalent metal ions in the divalent metal ion solution to the trivalent metal ions in step S1 is 2:1; age and modify the mixture at 120°C for 8 hours to obtain the modified hydrated oxide adsorbent.

[0086] Example 5

[0087] This embodiment provides a modified hydrated oxide adsorbent and a preparation method thereof, the preparation method comprising the following steps:

[0088] S1. A solution of trivalent chromium ions at a concentration of 0.01 mol / L and trivalent aluminum ions at a concentration of 0.06 mol / L was added to a sodium hydroxide solution at a concentration of 1 mol / L for mixed precipitation. The mixed precipitation time was 0.1 h, the mixed precipitation temperature was 80 ° C, the mixed precipitation pH value was 14, and the mixed precipitation was immediately separated from the solid and liquid and washed to obtain a first metal hydrated oxide;

[0089] S2. The first metal hydrated oxide is extruded and dehydrated at a pressure of 250 MPa, and after the extrusion and dehydration, the extrusion and dehydration are dried to obtain first metal hydrated oxide particles by polymerization;

[0090] S3. Mix the first metal hydrated oxide particles, the divalent metal ion solution and the sodium hydroxide solution to form a mixture with a pH value of 11, wherein the divalent metal ion solution is a magnesium ion solution, and the molar ratio of the divalent metal ions in the divalent metal ion solution to the trivalent metal ions in step S1 is 0.3:1; age and modify the mixture at 25°C for 48 hours to obtain the modified hydrated oxide adsorbent.

[0091] Example 6

[0092] This embodiment provides a modified hydrated oxide adsorbent and a preparation method thereof, the preparation method comprising the following steps:

[0093] S1. A solution of trivalent chromium ions having a concentration of 0.05 mol / L and trivalent iron ions having a concentration of 0.08 mol / L is added to a sodium hydroxide solution having a concentration of 15 mol / L for mixed precipitation. The mixed precipitation time is 2 h, the mixed precipitation temperature is 75 ° C, the mixed precipitation pH value is 10, and solid-liquid separation and washing are performed immediately after the mixed precipitation is completed to obtain a first metal hydrated oxide;

[0094] S2. The first metal hydrated oxide is extruded and dehydrated at a pressure of 100 MPa, and after the extrusion and dehydration, it is dried at 45 ° C to obtain a first metal hydrated oxide particle by polymerization;

[0095] S3. Mix the first metal hydrated oxide particles, the divalent metal ion solution and the sodium hydroxide solution to form a mixture with a pH value of 8.5, wherein the divalent metal ion solution is a magnesium ion solution, and the molar ratio of the divalent metal ions in the divalent metal ion solution to the trivalent metal ions in step S1 is 0.2:1; age and modify the mixture at 80°C for 18 hours to obtain the modified hydrated oxide adsorbent.

[0096] Example 7

[0097] This embodiment provides a modified hydrated oxide adsorbent and a preparation method thereof, the preparation method comprising the following steps:

[0098] S1. adding trivalent chromium ions at a concentration of 0.1 mol / L to a sodium hydroxide solution at a concentration of 10 mol / L for mixed precipitation, the mixed precipitation time is 0.9 h, the mixed precipitation temperature is 50 ° C, the mixed precipitation pH value is 13, and the mixed precipitation is immediately separated from the solid and washed to obtain a first metal hydrated oxide;

[0099] S2. The first metal hydrated oxide is solidified and dehydrated, and then dissolved and separated after solidification and dehydration, the solidification temperature is -100 ° C, the dissolution temperature is 20 ° C, and the first metal hydrated oxide particles are obtained by polymerization;

[0100] S3. Mix the first metal hydrated oxide particles, the divalent metal ion solution and the sodium hydroxide solution to form a mixture with a pH value of 12, wherein the divalent metal ion solution is a calcium ion solution, and the molar ratio of the divalent metal ions in the divalent metal ion solution to the trivalent metal ions in step S1 is 1.2:1; age and modify the mixture at 110°C for 10 hours to obtain the modified hydrated oxide adsorbent.

[0101] Example 8

[0102] This embodiment provides a modified hydrated oxide adsorbent and a preparation method thereof, the preparation method comprising the following steps:

[0103] S1. A 0.9 mol / L ferric iron ion solution is added to a 6 mol / L sodium hydroxide solution for mixed precipitation. The mixed precipitation time is 0.6 h, the mixed precipitation temperature is 60 ° C, the pH value of the mixed precipitation is 12, and the mixed precipitation is immediately separated from the solid and washed to obtain a first metal hydrated oxide.

[0104] S2. The first metal hydrated oxide is solidified and dehydrated, and then dissolved and separated after solidification and dehydration, the solidification temperature is 0°C, the dissolution temperature is 5°C, and the first metal hydrated oxide particles are obtained by polymerization;

[0105] S3. Mix the first metal hydrated oxide particles, the divalent metal ion solution and the sodium hydroxide solution to form a mixture with a pH value of 9.5, wherein the divalent metal ion solution is a calcium ion solution, and the molar ratio of the divalent metal ions in the divalent metal ion solution to the trivalent metal ions in step S1 is 1.5:1; age and modify the mixture at 70°C for 22 hours to obtain the modified hydrated oxide adsorbent.

[0106] Example 9

[0107] This embodiment provides a modified hydrated oxide adsorbent and a preparation method thereof, the preparation method comprising the following steps:

[0108] S1. A 0.3 mol / L trivalent aluminum ion solution was added to a 12 mol / L sodium hydroxide solution for mixed precipitation. The mixed precipitation time was 0.3 h, the mixed precipitation temperature was 55 ° C, the mixed precipitation pH was 11, and the mixed precipitation was immediately separated from the solid and liquid and washed to obtain a first metal hydrated oxide.

[0109] S2. The first metal hydrated oxide is solidified and dehydrated, and then dissolved and separated after solidification and dehydration, the solidification temperature is -175 ° C, the dissolution temperature is 45 ° C, and the first metal hydrated oxide particles are obtained by polymerization;

[0110] S3. Mix the first metal hydrated oxide particles, the divalent metal ion solution and the sodium hydroxide solution to form a mixture with a pH value of 12.5, wherein the divalent metal ion solution is a magnesium ion solution, and the molar ratio of the divalent metal ions in the divalent metal ion solution to the trivalent metal ions in step S1 is 0.4:1; age and modify the mixture at 105° C. for 15 hours to obtain the modified hydrated oxide adsorbent. .

[0111] Example 10

[0112] This embodiment provides a modified hydrated oxide adsorbent and a preparation method thereof, the preparation method comprising the following steps:

[0113] S1. A solution of trivalent chromium ions having a concentration of 0.2 mol / L, trivalent iron ions having a concentration of 0.3 mol / L, and trivalent aluminum ions having a concentration of 0.5 mol / L is added to a sodium hydroxide solution having a concentration of 9 mol / L for mixed precipitation. The mixed precipitation time is 0.7 h, the mixed precipitation temperature is 65 ° C, the mixed precipitation pH value is 7, and the mixed precipitation is immediately separated from the solid and liquid and washed to obtain a first metal hydrated oxide.

[0114] S2. The first metal hydrated oxide is solidified and dehydrated, and then dissolved and separated after solidification and dehydration, the solidification temperature is -195 ° C, the dissolution temperature is 60 ° C, and the first metal hydrated oxide particles are obtained by polymerization;

[0115] S3. Mix the first metal hydrated oxide particles, the divalent metal ion solution and the sodium hydroxide solution to form a mixture with a pH value of 10, wherein the divalent metal ion solution is a calcium ion solution, and the molar ratio of the divalent metal ions in the divalent metal ion solution to the trivalent metal ions in step S1 is 0.75:1; age and modify the mixture at 100°C for 12 hours to obtain the modified hydrated oxide adsorbent.

[0116] Embodiment 11

[0117] This embodiment provides a modified hydrated oxide adsorbent and a preparation method thereof, the preparation method comprising the following steps:

[0118] S1. A solution of trivalent chromium ions having a concentration of 0.1 mol / L, trivalent iron ions having a concentration of 0.02 mol / L, and trivalent aluminum ions having a concentration of 0.4 mol / L is added to a sodium hydroxide solution having a concentration of 10 mol / L for mixed precipitation. The mixed precipitation time is 0.8 h, the mixed precipitation temperature is 70 ° C, the mixed precipitation pH value is 8, and solid-liquid separation and washing are performed immediately after the mixed precipitation is completed to obtain a first metal hydrated oxide;

[0119] S2. The first metal hydrated oxide is solidified and dehydrated, and then dissolved and separated after solidification and dehydration, the solidification temperature is -5°C, the dissolution temperature is 30°C, and the first metal hydrated oxide particles are obtained by polymerization;

[0120] S3. Mix the first metal hydrated oxide particles, the divalent metal ion solution and the sodium hydroxide solution to form a mixture with a pH value of 8, wherein the divalent metal ion solution is a calcium ion solution, and the molar ratio of the divalent metal ions in the divalent metal ion solution to the trivalent metal ions in step S1 is 0.9:1; age and modify the mixture at 60°C for 20 hours to obtain the modified hydrated oxide adsorbent.

[0121] Example 12

[0122] This embodiment provides a modified hydrated oxide adsorbent and a preparation method thereof, the preparation method comprising the following steps:

[0123] S1. A solution of trivalent chromium ions having a concentration of 0.1 mol / L, trivalent iron ions having a concentration of 0.1 mol / L, and trivalent aluminum ions having a concentration of 0.1 mol / L are added to a sodium hydroxide solution having a concentration of 8 mol / L for mixed precipitation. The mixed precipitation time is 0.5 h, the mixed precipitation temperature is 60 ° C, the mixed precipitation pH value is 9, and solid-liquid separation and washing are performed immediately after the mixed precipitation is completed to obtain a first metal hydrated oxide;

[0124] S2. The first metal hydrated oxide is solidified and dehydrated, and then dissolved and separated after solidification and dehydration, the solidification temperature is -30 ° C, the dissolution temperature is 10 ° C, and the first metal hydrated oxide particles are obtained by polymerization;

[0125] S3. Mix the first metal hydrated oxide particles, the divalent metal ion solution and the sodium hydroxide solution to form a mixture with a pH value of 9, wherein the divalent metal ion solution is a calcium ion solution, and the molar ratio of the divalent metal ions in the divalent metal ion solution to the trivalent metal ions in step S1 is 1.75:1; age and modify the mixture at 90°C for 13 hours to obtain the modified hydrated oxide adsorbent.

[0126] Embodiment 13

[0127] The difference between this embodiment and embodiment 1 is that the time of mixing and precipitation in step S1 is 0.05 h, and the rest is the same as embodiment 1.

[0128] Embodiment 14

[0129] The difference between this embodiment and embodiment 1 is that the time of mixing and precipitation in step S1 is 3 hours, and the rest is the same as embodiment 1.

[0130] Embodiment 15

[0131] The difference between this embodiment and embodiment 1 is that the temperature of the mixed precipitation in step S1 is 20° C., and the rest is the same as embodiment 1.

[0132] Example 16

[0133] The difference between this embodiment and embodiment 1 is that the temperature of the mixed precipitation in step S1 is 100° C., and the rest is the same as embodiment 1.

[0134] Embodiment 17

[0135] The difference between this embodiment and embodiment 1 is that the pH value of the mixed precipitation in step S1 is 4, and the rest is the same as embodiment 1.

[0136] Embodiment 18

[0137] The difference between this embodiment and embodiment 1 is that the pH value of the mixed precipitation in step S1 is 16, and the rest is the same as embodiment 1.

[0138] Embodiment 19

[0139] The difference between this embodiment and embodiment 1 is that after the mixed precipitation in step S1 is completed, liquid-solid separation and washing are performed after waiting for 1 hour, and the rest is the same as embodiment 1.

[0140] Embodiment 20

[0141] The difference between this embodiment and embodiment 1 is that the pressure of pressurized dehydration in step S2 is 8 MPa, and the rest is the same as embodiment 1.

[0142] Embodiment 21

[0143] The difference between this embodiment and embodiment 1 is that, after the extrusion dehydration in step S2, a drying treatment is performed at 70° C., and the rest is the same as embodiment 1.

[0144] Embodiment 22

[0145] The difference between this embodiment and embodiment 1 is that after the extrusion dehydration in step S2 is completed, the drying treatment is not performed at 30° C., and the rest is the same as embodiment 1.

[0146] Embodiment 23

[0147] The difference between this embodiment and embodiment 7 is that the curing temperature in step S2 is 2° C., and the rest is the same as embodiment 7.

[0148] Embodiment 24

[0149] The difference between this embodiment and embodiment 7 is that the dissolution temperature in step S2 is 70° C., and the rest is the same as embodiment 7.

[0150] Embodiment 25

[0151] The difference between this embodiment and embodiment 7 is that no dissolution treatment is performed in step S2, and the rest is the same as embodiment 7.

[0152] Embodiment 26

[0153] The difference between this embodiment and embodiment 1 is that the molar ratio of the divalent metal ions in the divalent metal ion solution in step S3 to the trivalent metal ions in step S1 is 0.05:1, and the rest is the same as embodiment 1.

[0154] Embodiment 27

[0155] The difference between this embodiment and embodiment 1 is that the molar ratio of the divalent metal ions in the divalent metal ion solution in step S3 to the trivalent metal ions in step S1 is 2.1:1, and the rest is the same as embodiment 1.

[0156] Embodiment 28

[0157] The difference between this embodiment and embodiment 1 is that the pH value of the mixture in step S3 is 7, and the rest is the same as embodiment 1.

[0158] Embodiment 29

[0159] The difference between this embodiment and embodiment 1 is that the pH value of the mixture in step S3 is 14, and the rest is the same as embodiment 1.

[0160] Embodiment 30

[0161] The difference between this embodiment and embodiment 1 is that the temperature of aging modification in step S3 is 30° C., and the rest is the same as embodiment 1.

[0162] Embodiment 31

[0163] The difference between this embodiment and embodiment 1 is that the temperature of aging modification in step S3 is 130° C., and the rest is the same as embodiment 1.

[0164] Embodiment 32

[0165] The difference between this embodiment and embodiment 1 is that the aging modification time in step S3 is 5 hours, and the rest is the same as embodiment 1.

[0166] Embodiment 33

[0167] The difference between this embodiment and embodiment 1 is that the aging modification time in step S3 is 50 hours, and the rest is the same as embodiment 1.

[0168] Comparative Example 1

[0169] The difference between this comparative example and Example 1 is that the processing of step S2 is not performed, and the rest is the same as Example 1.

[0170] Comparative Example 2

[0171] The difference between this comparative example and Example 1 is that the processing of step S3 is not performed, and the rest is the same as Example 1.

[0172] Comparative Example 3

[0173] The difference between this comparative example and Example 1 is that only the process of step S1 is performed, and the processes of step S2 and step S3 are not performed, and the rest are the same as Example 1.

[0174] Comparative Example 4

[0175] The difference between this comparative example and Example 7 is that the processing of step S2 is not performed, and the rest is the same as Example 7.

[0176] Comparative Example 5

[0177] The difference between this comparative example and Example 7 is that the processing of step S3 is not performed, and the rest is the same as Example 7.

[0178] Comparative Example 6

[0179] The difference between this comparative example and Example 7 is that only the processing of step S1 is performed, and the processing of step S2 and step S3 is not performed, and the rest is the same as Example 7.

[0180] The adsorbent prepared in the examples and comparative examples was used to recover vanadium from the vanadium-containing solution. The adsorbent was cycled for adsorption-desorption ten times. The composition of the adsorption stock solution and the adsorption capacity of vanadium and chromium are shown in Table 1:

[0181] Table 1

[0182]

[0183] From Table 1, we can draw the following conclusions:

[0184] (1) Compared with Examples 13 to 19, the first adsorption effect and the ten-time adsorption effect of the modified hydrated oxide adsorbent provided in Example 1 are better than those in Examples 13 to 19. It can be seen that the present invention can effectively regulate the hydrolysis reaction of trivalent metal ions by optimizing the conditions of mixed precipitation, thereby generating hydrated oxides with disorder, small size, non-crystalline, large specific surface area and more adsorption active sites. Specifically, under the synergistic effect of many factors such as regulating the mixed precipitation temperature, the pH value of the mixed precipitation, the mixed precipitation time, and the liquid-solid separation and washing immediately after the mixed precipitation, it is possible to achieve a rapid hydrolysis reaction and avoid the formation of crystalline hydrates, thereby improving the adsorption effect.

[0185] (2) Compared with Examples 20 to 25, the first adsorption effect of the modified hydrated oxide adsorbent provided by Example 1 or Example 7 is better than that of the corresponding adsorbents of Examples 20 to 25, wherein Example 25 has no adsorption effect because the adsorbent cannot be obtained without dissolution treatment. It can be seen that the present invention dehydrates and polymerizes the hydrated oxide by preferably pressurized dehydration and / or low-temperature curing to form hydrated oxide particles with abundant mesoporous channels. The ten-time adsorption effect of Example 1 or Example 7 is slightly lower than the first adsorption effect, which shows that the aging modification technical means provided by the present invention has the effect of improving the stability of the adsorbent.

[0186] (3) Compared with Examples 26 to 33, the first adsorption effect and the ten-time adsorption effect of the modified hydrated oxide adsorbent provided in Example 1 are better than those of the corresponding adsorbents in Examples 26 to 33. It can be seen that the present invention forms a layered structure consisting of a bimetallic layer, an anion layer and an original surface layer by aging and modifying the surface of the hydrated oxide particles, and further regulating the molar ratio range of divalent metal ions and trivalent metal ions and the specific conditions of aging and modification. The formation of this structure is mainly through the replacement of part of the trivalent metal ions by divalent metal ions, thereby generating new adsorption active sites. This modification method not only enhances the stability of the adsorbent, but also significantly improves its adsorption effect.

[0187] (4) Compared with Comparative Examples 1 to 6, the first adsorption effect of the modified hydrated oxide adsorbent provided in Example 1 or Example 7 is better than that of the adsorbent corresponding to Comparative Examples 1 to 6. It can be seen that the technical means of dehydration polymerization, addition of divalent metal ion solution and aging modification provided by the present invention have the effect of improving the adsorption effect of the adsorbent. At the same time, the technical means of adding divalent metal ion solution and aging modification provided by the present invention have the effect of improving the stability of the adsorbent, and the formed hydrated oxide particle adsorbent has the effect of improving the strength of the adsorbent. It can be seen from Comparative Examples 2 to 3 and Comparative Examples 5 to 6 that the present invention preferably adopts a combination of two or more trivalent metal ions and alkali solution for mixed precipitation. During precipitation, homogeneous replacement can occur between the trivalent metals, thereby destroying the integrity of the hydrated oxide lattice, thereby rapidly hydrolyzing and precipitating to generate disordered, small, non-crystalline and large specific surface area hydrated oxides with more active adsorption sites.

[0188] In addition, the adsorbent provided by the present invention can be used to adsorb and recover vanadium from different types of vanadium-containing wastewater, stone coal vanadium extraction leachate and sodium chromate leachate, and can be adsorbed 10 times in a pH range of 2-12, and the adsorbent can maintain high adsorption capacity and high selective adsorption effect. In addition, the adsorbent has the characteristics of small loss, high strength, good adsorption stability and long service life, specifically, the adsorption capacity of V2O5 is not less than 125mg / g, the adsorption V2O5 / Cr mass ratio is greater than 35, and the loss of ten cycles of adsorption is not more than 0.05%.

[0189] In summary, the adsorbent of the present invention first forms hydrated oxide particles by polymerization, thereby improving the strength of the adsorbent, and stabilizes the material structure by multi-metal mixed precipitation and surface modification of hydrated oxide particles, thereby extending the life of the adsorbent. In addition, the preparation method provided by the present invention does not require external additives, has a simple process and is pollution-free, so that the adsorbent can maintain high selectivity and high adsorption capacity, and therefore has broad application prospects.

[0190] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing a modified hydrated oxide adsorbent, characterized in that: The method comprises the following steps: S1. Dehydrating and polymerizing the first metal hydrated oxide to obtain first metal hydrated oxide particles; S2. mixing the first metal hydrated oxide particles and the second metal ion solution to form a mixture, wherein the valence of the first metal ion in the first metal hydrated oxide particles is different from the valence of the second metal ion; S3. The mixture is subjected to aging modification to obtain the modified hydrated oxide adsorbent.

2. The method according to claim 1, characterized in that The method for preparing the first metal hydrated oxide in step S1 includes: mixing a first metal ion solution and a first alkaline solution for precipitation, and obtaining the first metal hydrated oxide after solid-liquid separation.

3. The method according to claim 2, characterized in that The first metal ion solution is a trivalent metal ion solution; Preferably, the trivalent metal ion solution comprises any one of chromium ions, iron ions or aluminum ions or a combination of at least two thereof, preferably a combination of at least two thereof; Preferably, the total concentration of trivalent metal ions in the trivalent metal ion solution is 0.01 mol / L-1.5 mol / L; Preferably, the concentration of the first alkali solution is 1 mol / L-20 mol / L, preferably 5 mol / L-15 mol / L.

4. The method according to claim 2 or 3, characterized in that: The method of mixing the first metal ion solution and the first alkali solution for precipitation includes adding the first metal ion solution to the first alkali solution, or adding the first alkali solution to the first metal ion solution, or adding the first metal ion solution and the first alkali solution in parallel, preferably adding the first metal ion solution to the first alkali solution; Preferably, solid-liquid separation is performed immediately after the mixed precipitation is completed; Preferably, the mixing precipitation time is 0.1h-2h, preferably 0.2h-1h; Preferably, the temperature of the mixed precipitation is 25°C-95°C, preferably 50°C-80°C; Preferably, the pH value of the mixed precipitation is 5-14.

5. The method according to any one of claims 1 to 4, characterized in that The dehydration polymerization method in step S1 includes pressurized dehydration and / or solidification dehydration; Preferably, the process of pressurized dehydration includes pressurizing the first metal hydrated oxide for extrusion dehydration, and performing drying after the extrusion dehydration is completed; Preferably, the pressure of the pressurized dehydration is not less than 10 MPa, preferably not less than 20 MPa, and more preferably not less than 50 MPa; Preferably, the temperature of the drying treatment is 1°C-60°C; Preferably, the solidification and dehydration process includes solidifying the water crystals in the first metal hydrated oxide and then dissolving and separating them; Preferably, the curing and dehydration temperature is not higher than 0°C, preferably not higher than -5°C, more preferably not higher than -30°C; Preferably, the dissolving temperature is 1°C-60°C.

6. The method according to any one of claims 1 to 5, characterized in that In step S2, the second metal ion includes a divalent metal ion; Preferably, the divalent metal ions include magnesium ions and / or calcium ions; Preferably, the molar ratio of the second metal ion to the first metal ion is (0.1-2):1, preferably (0.2-1):1; Preferably, the mixture in step S2 further includes a second alkali solution; Preferably, the pH value of the mixture in step S2 is 8-13.

7. The method according to any one of claims 1 to 6, characterized in that: The aging and modification temperature in step S3 is 40°C-120°C, preferably 50°C-90°C; Preferably, the aging and modification time in step S3 is 6h-48h, preferably 8h-24h.

8. The method according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: S1. adding a combined solution of at least two trivalent metal ions having a total concentration of 0.01 mol / L-1.5 mol / L to a first alkali solution having a concentration of 5 mol / L-15 mol / L for mixed precipitation, wherein the mixed precipitation time is 0.2 h-1 h, the mixed precipitation temperature is 50 ° C-80 ° C, the mixed precipitation pH value is 5-14, and solid-liquid separation is performed immediately after the mixed precipitation to obtain a trivalent metal hydrated oxide; S2. subjecting the trivalent metal hydrated oxide to pressurized dehydration polymerization and / or solidification dehydration polymerization to obtain trivalent metal hydrated oxide particles; wherein the pressurized dehydration process comprises pressurizing the trivalent metal hydrated oxide for extrusion dehydration, the pressure of the pressurized dehydration is not less than 20 MPa, and drying is performed at 1-60°C after the extrusion dehydration is completed; and / or, the solidification dehydration process comprises solidifying the water crystals in the trivalent metal hydrated oxide and then dissolving and separating, the temperature of the solidification dehydration is not higher than -5°C, and the temperature of the dissolution is 1°C-60°C; S3. Mix the trivalent metal hydrated oxide particles, the divalent metal ion solution and the second alkali solution to form a mixture with a pH value of 8-13, wherein the molar ratio of the divalent metal ions in the divalent metal ion solution to the trivalent metal ions in the combined solution of the at least two trivalent metal ions is (0.2-1):1; age and modify the mixture at 50°C-90°C for 8h-24h to obtain the modified hydrated oxide adsorbent.

9. A modified hydrated oxide adsorbent, characterized in that: The modified hydrated oxide adsorbent is prepared by the method for preparing a modified hydrated oxide adsorbent according to any one of claims 1-8.

10. Use of the modified hydrated oxide adsorbent according to claim 9, characterized in that: The modified hydrated oxide is used for adsorption and recovery of vanadium from any one of vanadium-containing wastewater, stone coal vanadium extraction leaching solution or sodium chromate leaching solution.

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