Cerium-based adsorbent for treating radioactive waste liquid and preparation method thereof

Abstract

The invention relates to a cerium-based adsorbent for treating radioactive waste liquid and a preparation method of the cerium-based adsorbent. The preparation method comprises the following steps: preparing porous biochar, and performing hydrothermal treatment on the porous biochar and a hydrophilic reagent to prepare a hydrophilic porous biochar matrix; dispersing a cerium source, an iron source and the hydrophilic porous biochar matrix into deionized water to obtain a metal salt solution; the method comprises the following steps: dropwise adding ammonia water into a metal salt solution to obtain a mixed solution with a stable pH value, reacting the mixed solution in a stainless steel autoclave to obtain a product, washing the product to be neutral, and drying and calcining the obtained composite oxide to obtain the cerium-based adsorbent. The composite cerium-based adsorbent with different surface oxygen defects is synthesized through a hydrothermal method by taking oxides of iron and cerium as catalytic activity reagents and taking a hydrophilic porous biological carbon matrix as a carrier, and the surface defects of the composite cerium-based adsorbent are beneficial to generation of relatively stable hydroxyl groups, so that the adsorption activity can be remarkably improved.

Description

Technical Field

[0001] The invention belongs to the technical field of nuclear waste treatment, and particularly relates to a cerium-based adsorbent for treating radioactive waste liquid and a preparation method thereof. Background Art

[0002] During the radioactive decontamination process, the removal and cleaning of radioactive materials generates large amounts of wastewater. This wastewater contains not only radioactive materials but also other hazardous substances, such as heavy metals and chemicals. Due to the unique properties of radioactive materials, their treatment and disposal require specialized equipment and technology to ensure they pose no risk to the environment or human health.

[0003] Common treatment methods include chemical precipitation, ion exchange, and membrane separation, but these methods all have certain limitations, such as low treatment efficiency and high cost. Therefore, the development of efficient and low-cost radioactive decontamination wastewater treatment methods has important practical significance and application value.

[0004] In recent years, the adsorption method has shown significant advantages in treating certain organic matter in wastewater. Its advantage is that it can effectively remove metal ions from wastewater, and can also adsorb ozone ions and difficult-to-degrade organic matter. The adsorption method uses the adsorption properties of the adsorption material to achieve rapid and efficient removal of organic matter, thereby reducing the burden of subsequent treatment processes. At the same time, the ozone method of treating wastewater also has a good effect in degrading organic matter, but the impact of the presence of ozone on the adsorption material cannot be ignored. Ozone has strong oxidizing properties and may destroy the structure of the adsorption material and reduce its adsorption performance. Therefore, when using the ozone method to degrade organic matter, it is necessary to fully consider its impact on the adsorption material and take appropriate measures to mitigate this impact to ensure the long-term stable operation of the adsorption method.

[0005] Patent CN202310763559.9 discloses a method for preparing and optimizing a Ce-based adsorbent for efficient Cr(VI) removal. This method uses a metal organic framework as a precursor and is prepared by calcination. The resulting Ce-based adsorbent has a high specific surface area, and a large number of hydroxyl functional groups are introduced on the surface. After optimization, the content of Ce(III) and oxygen vacancies in the adsorbent increases, further improving the adsorption capacity and reduction capacity of Cr(VI). The prepared Ce-based adsorbent is an environmentally friendly material with the advantages of simple production process, good adsorption performance, wide working pH range, strong stability, and multiple recycling. At the same time, the adsorbent obtained by this invention is applied to the treatment of wastewater containing Cr(VI), which can achieve efficient adsorption of Cr(VI) and reduce highly toxic Cr(VI) to low-toxic Cr(III), which can effectively solve the problem of chromium pollution in water and has great application potential.

[0006] Patent CN201510725663.4 discloses an ozone catalyst and its preparation method. The catalyst is prepared using natural manganese sand or pyrolusite as raw materials. The catalyst itself contains catalytically active components, manganese dioxide and iron, and no metal elements need to be added, which reduces the production cost of the ozone catalyst. However, the catalyst prepared uses a binder to compound a single manganese-containing raw material. At the same time, physical means such as kneading will cause the product density to increase and the pore size to decrease, which will affect the adsorption rate and catalytic efficiency to a certain extent. Summary of the Invention

[0007] The purpose of the present invention is to provide a cerium-based adsorbent for treating radioactive waste liquid and a preparation method thereof. Iron and cerium oxides are used as catalytically active reagents and a hydrophilic porous biocarbon matrix is ​​used as a carrier. A composite adsorbent with different surface oxygen defects is synthesized by a hydrothermal method. The composite adsorbent has a loose microstructure and excellent macroscopic physical properties, can significantly improve the adsorption activity, and has the advantages of simple process operation, low cost, high efficiency and environmental friendliness.

[0008] To achieve the above objectives, the present invention adopts a technical solution: a method for preparing a cerium-based adsorbent for treating radioactive waste liquid, the method comprising the following steps:

[0009] S1. Preparing porous biochar: first, washing, drying, crushing, and sieving biomass to obtain biomass powder, grinding and mixing the biomass powder with a high-temperature activator in a predetermined ratio, then heating the mixture to a high-temperature pyrolysis temperature at a predetermined heating rate under inert gas protection, maintaining the mixture at the high-temperature pyrolysis temperature for a predetermined period of time, and then naturally cooling the mixture to room temperature. The pyrolysis product is neutralized with a neutralizing agent to neutrality, then washed with deionized water, and dried in an oven to obtain the porous biochar;

[0010] S2. Preparing a hydrophilic porous biochar matrix: mixing the porous biochar with a hydrophilic reagent, and performing a hydrothermal treatment to prepare the hydrophilic porous biochar matrix HBC;

[0011] S3. Preparing a metal salt solution: Weighing a cerium source, an iron source, and the hydrophilic porous biochar matrix at a set molar ratio, dispersing them into deionized water, and stirring them evenly to obtain the metal salt solution;

[0012] S4. Preparation of cerium-based adsorbent: placing the metal salt solution on a magnetic stirrer, adding ammonia water dropwise to a mixed solution with a stable pH value, transferring the mixed solution to a stainless steel autoclave for reaction for a set time; after the reaction product is cooled, washing with distilled water until neutral, drying the obtained composite oxide, calcining the composite oxide for a certain period of time, and then fixing the volume to obtain a cerium-based adsorbent.

[0013] Furthermore, the biomass is selected from one or more of corn stalks, rice husks, kapok or hemp stalks;

[0014] The biomass is washed, dried, crushed, and passed through a 100-200 mesh sieve to obtain biomass powder.

[0015] Furthermore, the high temperature activator is selected from one or a combination of NaOH, KOH, NaHCO3 or KCl.

[0016] Furthermore, the mass ratio of the biomass powder to the high-temperature activator is 1:2 to 2:1.

[0017] Furthermore, the inert gas is nitrogen and / or argon.

[0018] Furthermore, in step S1, the set heating rate is 5-10°C / min.

[0019] Furthermore, the neutralizing agent is selected from one or a combination of hydrochloric acid, nitric acid, and sulfuric acid.

[0020] Furthermore, in step S2, the hydrophilic reagent is selected from one or a combination of ammonium persulfate, sulfuric acid or nitric acid.

[0021] Furthermore, in step S2, the porous biochar and the hydrophilic agent are mixed in a mass ratio of 1:1 to 2:1; and the mass percentage of the hydrophilic agent is 1 to 10%.

[0022] Furthermore, in step S2, the hydrothermal treatment method is: after mixing the porous biochar with a hydrophilic reagent, hydrothermally treat it at 60-80° C. and 0.1-3 MPa for 3-4 hours to obtain the hydrophilic porous biochar matrix.

[0023] Furthermore, the cerium source is Ce(NO3)3·6H2O;

[0024] The iron source is Fe(NO3)3·9H2O and / or FeCl3·6H2O.

[0025] Furthermore, the molar ratio of Fe to Ce in the metal salt solution is 10:1.

[0026] Furthermore, in step S4, the mixed solution is transferred to a stainless steel autoclave and reacted at 180-200° C. and 0.1-3 MPa for 40-50 hours.

[0027] Furthermore, in step S4, the composite oxide is calcined at 500-550° C. for 10-12 hours to obtain a cerium-based adsorbent.

[0028] The present invention also provides a cerium-based adsorbent for treating radioactive waste liquid, which is prepared based on the preparation method of the cerium-based adsorbent for treating radioactive waste liquid. The cerium-based adsorbent is prepared by a hydrophilic porous bio-carbon matrix and ferrous cerium oxide through a hydrothermal method, and the ferrous cerium oxide is carried on the hydrophilic porous bio-carbon matrix to form a composite adsorbent.

[0029] The beneficial effects of the present invention are: using a cerium-based adsorbent for treating radioactive waste liquid and its preparation method provided by the present invention, by preparing porous biochar, the porous biochar and a hydrophilic reagent are hydrothermally treated to prepare a hydrophilic porous biochar matrix; the cerium source, the iron source, and the hydrophilic porous biochar matrix are dispersed in deionized water to obtain a metal salt solution; ammonia water is dripped into the metal salt solution to obtain a mixed solution with a stable pH value, the mixed solution is reacted in a stainless steel autoclave to obtain a product washed to neutrality, and then the obtained composite oxide is dried and calcined to obtain a cerium-based adsorbent. The present invention uses iron and cerium oxides as catalytically active reagents, and a hydrophilic porous biocarbon matrix as a carrier, and synthesizes a composite cerium-based adsorbent with different surface oxygen defects by a hydrothermal method. The defects on its surface help to produce relatively stable hydroxyls, which can significantly improve the adsorption activity. The specific beneficial effects of the present invention are mainly reflected in:

[0030] (1) Using stereostructure synthesis technology, the number and distribution of micropores in the adsorbent matrix are greatly increased under high temperature and high pressure conditions, resulting in a high specific surface area and an adsorption efficiency increase of more than 10%;

[0031] (2) The cerium-based adsorbent is bonded by chemical bonds and hydrogen bonds, which avoids the loss of adsorption during the adsorption process and increases the service life. The adsorption activity of the cerium-based adsorbent remains highly stable during long-term treatment of radioactive waste liquid, and the radioactivity removal rate and the effective service life of the adsorbent are significantly improved.

[0032] (3) Fe doped in the cerium-based adsorbent easily forms mixed crystals with CeO2, increasing the two-phase interface, thereby increasing the surface defects of the adsorbent and forming more oxygen vacancies. It has strong adsorption properties and can enrich radioactive nuclides on the surface, which is beneficial to the adsorption of radioactive nuclides, ozone, and organic matter. At room temperature, ozone can be converted to a high level.

[0033] (4) Iron and cerium raw materials are cheap, widely distributed, and easy to obtain; the steps in the method are scientific and reasonable, complementary, and highly operable, and can quickly configure the adsorbent, effectively adsorb radioactive nuclides, solid organic matter, and ozone, and carry out synergistic decomposition, with little environmental pollution, low cost, high adsorption efficiency, simplified processing technology, saved reagent consumption, and significant effect, and are worthy of promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The present invention is a schematic flow chart of a method for preparing a cerium-based adsorbent for treating radioactive waste liquid according to an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present invention will be further clearly and completely described below in conjunction with the drawings and examples. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0036] At present, there are few patent reports on related cerium oxide-resistant adsorbents at home and abroad. There are a large number of common adsorbents on the market, but at the same time, high-strength silicon-aluminum composites are generally used as carriers for ozone catalysts. However, in the process of removing organic matter from radioactive wastewater in nuclear facilities, the use of conventional adsorbents is expensive, the pore size is smaller than that of carbon-based adsorbents, and the adsorption performance is weak. For organic matter in wastewater, the density is relatively large, and adsorption contact can only be carried out during the stirring process, which is time-consuming and labor-intensive. In addition, the adsorbent needs to have high adsorption capacity for radionuclides to separate a large amount of radionuclides from the wastewater. At this time, specific adsorbents are needed for decontamination and cleaning.

[0037] Furthermore, the disposal of radioactive decontamination waste liquid should also meet specific requirements, including (1) resistance to ozone oxidation; (2) the ability to adsorb radioactive nuclides; (3) no generation of radioactive secondary waste, including radioactive gases, during the catalytic process; and (4) avoidance of halogens as secondary waste.

[0038] Therefore, the present invention aims to develop a novel cerium-based adsorbent that can not only adsorb radionuclides in wastewater but also coexist with ozone to synergistically decompose organic matter. Furthermore, the adsorbent should be inexpensive, produce minimal secondary waste, and be capable of efficiently and long-term treatment of radioactive, solid-phase, and recalcitrant organic matter while ensuring the safety of operators.

[0039] The cerium-based adsorbent for treating radioactive waste liquid provided in this embodiment has the following main advantages for disposing radioactive nuclides in radioactive waste water: (1) high adsorption; (2) long life; (3) high nuclide adsorption capacity; (4) safety, environmental protection and non-toxicity; (5) low economic cost; (6) simple and easy-to-control synthesis method; and (7) mass production.

[0040] like Figure 1 As shown, this embodiment provides a method for preparing a cerium-based adsorbent for treating radioactive waste liquid, the method comprising the following steps:

[0041] S1. Preparing porous biochar: first, washing, drying, crushing, and sieving the biomass to obtain biomass powder, thoroughly grinding the high-temperature activator and the biomass powder in a predetermined ratio to uniformly mix them, then heating the mixture to a high-temperature pyrolysis temperature at a predetermined heating rate under inert gas protection, maintaining the mixture at the high-temperature pyrolysis temperature for a predetermined period of time, and then naturally cooling the mixture to room temperature. The pyrolysis product is then neutralized with a specified amount of a neutralizing agent to neutrality, then thoroughly washed with deionized water, and dried in an oven to prepare porous biochar having a high surface area;

[0042] Optionally, the biomass is selected from one or more of corn stalks, rice husks, kapok or hemp stalks.

[0043] Specifically, the biomass is washed, dried, crushed, and passed through a 100-200 mesh sieve to obtain biomass powder.

[0044] Optionally, the high-temperature activator is selected from one or a combination of NaOH, KOH, NaHCO3 or KCl.

[0045] Specifically, the mass ratio of the biomass powder to the high-temperature activator is 1:2 to 2:1.

[0046] Optionally, the inert gas is nitrogen or argon, or a combination of more than one of them.

[0047] Optionally, in step S1, the set heating rate is 5-10°C / min.

[0048] Optionally, the high-temperature pyrolysis temperature is 500-800° C.; and the high-temperature pyrolysis temperature is maintained for 0.5-2 hours.

[0049] Optionally, the neutralizing agent includes the following components: one or a combination of hydrochloric acid, nitric acid, sulfuric acid, etc.

[0050] S2. Preparing a hydrophilic porous biochar matrix: mixing the porous biochar with a certain concentration of a hydrophilic reagent, and performing a hydrothermal treatment to prepare a hydrophilic porous biochar matrix HBC;

[0051] Optionally, in step S2, the hydrophilic reagent is selected from one or a combination of ammonium persulfate, sulfuric acid or nitric acid.

[0052] Optionally, in step S2, the porous biochar and the hydrophilic agent are mixed in a mass ratio of 1:1 to 2:1. The mass percentage of the hydrophilic agent is 1 to 10%.

[0053] Specifically, the hydrothermal treatment method is: after mixing the porous biochar with a hydrophilic reagent, hydrothermally treat it at 60-80° C. and 0.1-3 MPa for 3-4 hours to obtain the hydrophilic porous biochar matrix.

[0054] S3. Preparing a metal salt solution: Weighing a cerium source, an iron source, and the hydrophilic porous biochar matrix at a set molar ratio, dispersing them into deionized water, and stirring them evenly to obtain a metal salt solution containing Fe and Ce at a set molar ratio;

[0055] Optionally, the cerium source is Ce(NO3)3·6H2O.

[0056] Optionally, the iron source is one or a combination of Fe(NO3)3·9H2O, FeCl3·6H2O, etc.

[0057] Optionally, the molar ratio of Fe to Ce in the metal salt solution is 10:1.

[0058] S4. Preparation of a cerium-based adsorbent: placing the metal salt solution on a magnetic stirrer, adding ammonia water dropwise to a mixed solution with a stable pH value, transferring the mixed solution to a stainless steel autoclave for reaction for a set time; after the reaction product is cooled, washing it with distilled water several times until it is neutral, drying the obtained composite oxide in an oven, and then calcining the composite oxide for a certain period of time to obtain a cerium-based adsorbent.

[0059] Specifically, in step S4, aqueous ammonia is added dropwise to maintain the pH value of the mixed solution stable at about 10, and then the mixed solution is transferred to a stainless steel autoclave.

[0060] Optionally, the mixed solution is transferred to a stainless steel autoclave and reacted at 180-200° C. and 0.1-3 MPa for 40-50 hours.

[0061] Optionally, the composite oxide is calcined at 500-550° C. for 10-12 hours and then fixed to obtain a cerium-based adsorbent.

[0062] This embodiment provides a method for preparing a cerium-based adsorbent for treating radioactive liquid waste. Using iron and cerium oxides as catalytically active agents and a hydrophilic porous biocarbon matrix as a support, a composite adsorbent with varying surface oxygen defects is synthesized via a hydrothermal method. These surface defects contribute to the generation of relatively stable hydroxyl groups, significantly enhancing adsorption activity. In other words, this embodiment utilizes a stereostructured synthesis technique to significantly increase the number and distribution of micropores in the adsorbent matrix under high temperature and high pressure conditions, resulting in a high specific surface area and an adsorption efficiency improvement of over 10%. The cerium-based adsorbent is chemically bonded, preventing loss during the adsorption process and extending its service life. The Fe doped in the cerium-based adsorbent readily forms mixed crystals with CeO2, increasing the two-phase interface and thus the number of surface defects in the adsorbent, creating more oxygen vacancies. This enhances adsorption performance, enriching radionuclides on the surface and facilitating the adsorption of radionuclides, ozone, and organic matter. High ozone conversion can be achieved at room temperature. Furthermore, iron and cerium raw materials are inexpensive, widely available, and readily available. The various steps in the method are scientific and reasonable, complement each other, and have strong operability. The adsorbent can be quickly prepared, and can effectively adsorb radioactive nuclides, solid organic matter and ozone, and carry out synergistic decomposition. It has low environmental pollution, low cost, high adsorption efficiency, simplified processing technology, saved reagent consumption, and significant effect, and is worthy of promotion and application.

[0063] This embodiment also provides a cerium-based adsorbent for treating radioactive waste liquid, which is prepared using the above-mentioned preparation method of the cerium-based adsorbent for treating radioactive waste liquid. The cerium-based adsorbent is prepared from a hydrophilic porous biocarbon matrix and ferrous cerium oxide by a hydrothermal method, and the ferrous cerium oxide is carried on the hydrophilic porous biocarbon matrix to form a composite adsorbent.

[0064] Specifically, the cerium-based adsorbent has a self-release effect, which saves more than 10% of the adsorbent input.

[0065] The hydrophilic porous biocarbon matrix is ​​based on porous biocarbon with abundant macropores and a wide pore size distribution. Hydrophilic functional groups strengthen the bond between the activated carbon support and Fe2O3 / CeO2 (forming chemical bonds or hydrogen bonds). The active component, ferrous cerium oxide, is firmly bonded to the hydrophilic porous biocarbon matrix, reducing leakage. Furthermore, the Fe doped in the cerium-based adsorbent readily forms mixed crystals with CeO2, increasing the two-phase interface and thus surface defects in the adsorbent. This helps generate relatively stable hydroxyl groups, which in turn creates more oxygen vacancies, enhancing adsorption performance. Furthermore, while ozone can be injected into wastewater, it can also decompose organic matter such as detergents in the wastewater.

[0066] The specific embodiments of the present invention are further described below through examples.

[0067] Example 1: Preparation of Cerium-based Adsorbent A Using the Preparation Method for Treating Radioactive Waste

[0068] S11. Preparation of hydrophilic porous biochar matrix: Wash and dry the biomass corn straw and crush it through a 100-mesh sieve. Grind the high-temperature activator NaOH and the corn straw powder in a mass ratio of 1:1 to make them evenly mixed. Then, heat it to a high-temperature pyrolysis temperature of 600°C at a heating rate of 5°C / min under nitrogen protection, maintain it at the pyrolysis temperature for 1 hour, and then naturally cool it to room temperature. The pyrolysis product taken out is neutralized to neutrality with a certain amount of neutralizing agent 0.1mol / L hydrochloric acid, and then washed thoroughly with deionized water and dried in an oven at 60°C to prepare porous biochar with a high surface area. The porous biochar is mixed with a certain concentration of hydrophilic reagent ammonium persulfate, and hydrothermally treated at 60°C and 0.15MPa for 3 hours to prepare a hydrophilic porous biochar matrix HBC;

[0069] S12. Preparation of cerium-based adsorbent: Weigh a certain amount of cerium salt (Ce(NO3)3·6H2O), iron salt (Fe(NO3)3·9H2O) and hydrophilic porous biochar matrix and disperse them in deionized water. Stir evenly to obtain a metal salt solution with a molar ratio of Fe:Ce of 10:1. Then, place the prepared metal salt solution on a magnetic stirrer and slowly add 5 mol / L ammonia water. After the pH value of the mixed solution is kept stable at around 10, transfer 60 mL of the mixed solution to a 100 mL stainless steel autoclave and react at 180°C and 1.5 MPa for 48 hours. After cooling, the reaction product is washed with distilled water several times until it is neutral, and the obtained composite oxide is dried in an oven. Finally, calcined at 500°C for 10 hours to obtain the red HBC / Fe2O3 / CeO2 composite oxide, which is the desired cerium-based adsorbent.

[0070] The composite materials prepared by adding different masses of HBC in Example 1 are marked as 70% HBC / Fe2O3 / CeO2, that is, the mass percentage of the hydrophilic porous biochar matrix HBC in the total amount of cerium salt (Ce(NO3)3·6H2O), iron salt (Fe(NO3)3·9H2O) and hydrophilic porous biochar matrix HBC added in step S12 is 70%.

[0071] Example 2: Ability of Cerium-based Adsorbent A to Treat Solid-Phase Organic Matter

[0072] The main purpose of this Example 2 is to verify the performance of the catalytic effect of the ozone oxidation of organic matter to inorganic matter when ozone is introduced.

[0073] Among them, the dosage of cerium-based adsorbent A is 1g / L, the power of the ozone generator is 3.1-3.2KW, the ozone concentration is 100mg / L; the initial concentration of DTPA is 30mg / L, and the pH value is controlled at 6.5. According to the above ratio, 1.0m 3 The DTPA wastewater was catalytically oxidized for 1 hour, and then samples were taken for online analysis to detect the treatment effect of the DTPA wastewater. The experimental data and treatment effects are shown in Table 1 below:

[0074] Table 1 Experimental data and treatment effects of cerium-based adsorbent A in treating solid organic matter

[0075] Initial concentration mg / L Treatment requirements mg / L Treatment effect mg / L Whether the requirements are met DTPA 30.0 <0.5 mg / L 0.46 yes COD 182.6 <120 mg / L 52.3 yes AES / <2.0 mg / L 0.91 yes

[0076] After testing, when the sewage treatment volume reaches 1.0m 3 / h, when the initial DTPA concentration was 30.0 mg / L, the initial AES concentration was 0.03 mg / L, and the initial COD concentration was 182.6 mg / L, the COD content after treatment was lower than 120 mg / L, the AES concentration was less than 2.0 mg / L, and the DTPA concentration after treatment was less than 0.5 mg / L.

[0077] Example 3: Preparation of Cerium-Based Adsorbent B Using the Preparation Method for Treating Radioactive Waste

[0078] S31. Preparation of hydrophilic porous biochar matrix: Wash and dry the biomass (corn straw) and crush it through a 100-mesh sieve. Grind the high-temperature activator NaOH and corn straw powder in a mass ratio of 1:1 to mix them evenly. Then, heat it to a high-temperature pyrolysis temperature of 600°C at a heating rate of 5°C / min under nitrogen protection, maintain it at the pyrolysis temperature for 1 hour, and then naturally cool it to room temperature. The pyrolysis product taken out is neutralized to neutrality with a neutralizing agent of 0.1 mol / L hydrochloric acid, and then washed thoroughly with deionized water and dried in an oven at 60°C to prepare porous biochar with a high surface area. The porous biochar is mixed with a certain concentration of hydrophilic reagent ammonium persulfate, and hydrothermally treated at 60°C and 0.12MPa for 3 hours to prepare a hydrophilic porous biochar matrix HBC;

[0079] S32. Preparation of cerium-based adsorbent: Weigh a certain amount of cerium salt (Ce(NO3)3·6H2O), iron salt (FeCl3·6H2O), and hydrophilic porous biochar matrix and disperse them in deionized water. Stir evenly to obtain a metal salt solution with a molar ratio of Fe:Ce of 10:1. Then, place the prepared metal salt solution on a magnetic stirrer and slowly add 5 mol / L ammonia water. After maintaining the pH value of the mixed solution at a stable level of around 10, transfer 60 mL of the mixed solution to a 100 mL stainless steel autoclave and react at 180°C and 2 MPa for 48 hours. After cooling, the reaction product is washed several times with distilled water until neutral, and the resulting composite oxide is dried in an oven. Finally, calcinate at 500°C for 10 hours to obtain the red HBC / Fe2O3 / CeO2 composite oxide, which is the desired cerium-based adsorbent.

[0080] The composite materials prepared by adding different masses of HBC in Example 3 were marked as 85% HBC / Fe2O3 / CeO2, that is, the mass percentage of the hydrophilic porous biochar matrix HBC in the total amount of cerium salt (Ce(NO3)3·6H2O), iron salt (FeCl3·6H2O) and hydrophilic porous biochar matrix HBC dispersed in deionized water in step S12 was 85%.

[0081] Example 4: Ability of Cerium-based Adsorbent B to Treat Solid-Phase Organic Matter

[0082] The main purpose of this Example 4 is to verify the performance of the cerium-based adsorbent B in catalyzing the inorganicization of organic matter by ozone oxidation when ozone is introduced.

[0083] Among them, the dosage of cerium-based adsorbent B is 1g / L, the power of the ozone generator is 3.1-3.2KW, the ozone concentration is 100mg / L; the initial concentration of EDTA is 30mg / L, and the pH value is controlled at 6.5. According to the above ratio, 1.0m 3 The EDTA wastewater was catalytically oxidized for 1 hour, and then samples were taken for online analysis to detect the treatment effect of the EDTA wastewater. The experimental data and treatment effects are shown in Table 1 below:

[0084] Table 1 Experimental data and treatment effects of cerium-based adsorbent B in treating solid organic matter

[0085] Initial concentration mg / L Treatment requirements mg / L Treatment effect mg / L Whether the requirements are met EDTA 30.0 <1mg / L 0.89 yes COD 198.6 <120 mg / L 47.8 yes AES / <2.0 mg / L 0.85 yes

[0086] After testing, when the sewage treatment volume reaches 1.0m 3 / h, when the initial EDTA concentration was 30.0 mg / L, the initial AES concentration was 0.09 mg / L, and the initial COD concentration was 198.6 mg / L, the COD content after treatment was lower than 120 mg / L, the AES concentration was less than 2.0 mg / L, and the EDTA concentration after treatment was less than 1 mg / L.

[0087] The methods described herein are not limited to the specific embodiments described. The above embodiments are merely illustrative of the present invention, and the present invention may also be implemented in other specific ways or in other specific forms without departing from the gist or essential characteristics of the present invention. Therefore, the embodiments described herein are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is to be determined by the appended claims, and any variations that are equivalent to the intent and scope of the claims are intended to be within the scope of the present invention.

Claims

1. A method for preparing a cerium-based adsorbent for treating radioactive waste liquid, characterized in that: The method comprises the following steps: S1. Preparation of porous biochar: first, wash, dry, crush and sieve the biomass to obtain biomass powder, grind and mix the biomass powder and the high-temperature activator in a predetermined ratio, and then heat the mixture to a high-temperature pyrolysis temperature at a set heating rate under the protection of an inert gas, keep the mixture at the high-temperature pyrolysis temperature for a certain period of time, and then naturally cool the mixture to room temperature. After neutralizing the taken-out pyrolysis product with a neutralizing agent to neutrality, the product is washed with deionized water and dried in an oven to obtain the porous biochar; S2, preparing a hydrophilic porous biochar matrix: mixing the porous biochar with a hydrophilic reagent, and performing a hydrothermal treatment to prepare the hydrophilic porous biochar matrix HBC; S3, preparing a metal salt solution: weighing a cerium source, an iron source, and the hydrophilic porous biochar matrix at a set molar ratio, dispersing them into deionized water, and stirring them evenly to obtain the metal salt solution; S4. Preparation of cerium-based adsorbent: placing the metal salt solution on a magnetic stirrer, dripping ammonia water into a mixed solution to obtain a stable pH value, transferring the mixed solution to a stainless steel autoclave for reaction for a set time; after the reaction product is cooled, washing it with distilled water until it is neutral, drying the obtained composite oxide, calcining the composite oxide for a certain period of time, and then fixing the volume to obtain a cerium-based adsorbent.

2. The method for preparing a cerium-based adsorbent for treating radioactive waste liquid according to claim 1, characterized in that: The biomass is selected from one or more of corn stalks, rice husks, kapok or hemp stalks; The biomass is washed, dried, crushed, and sieved through a 100-200 mesh sieve to obtain biomass powder.

3. The method for preparing a cerium-based adsorbent for treating radioactive waste liquid according to claim 1, characterized in that: The high temperature activator is selected from one or a combination of NaOH, KOH, NaHCO3 or KCl.

4. The method for preparing a cerium-based adsorbent for treating radioactive waste liquid according to claim 1, characterized in that: The mass ratio of the biomass powder to the high-temperature activator is 1:2 to 2:

1.

5. The method for preparing a cerium-based adsorbent for treating radioactive waste liquid according to claim 1, characterized in that: The inert gas is nitrogen and / or argon.

6. The method for preparing a cerium-based adsorbent for treating radioactive waste liquid according to claim 1, characterized in that: In step S1, the set heating rate is 5-10°C / min.

7. The method for preparing a cerium-based adsorbent for treating radioactive waste liquid according to claim 1, characterized in that: The neutralizing agent is selected from hydrochloric acid, nitric acid, sulfuric acid or a combination of several thereof.

8. The method for preparing a cerium-based adsorbent for treating radioactive waste liquid according to claim 1, characterized in that: In step S2, the hydrophilic reagent is selected from one or a combination of ammonium persulfate, sulfuric acid or nitric acid.

9. The method for preparing a cerium-based adsorbent for treating radioactive waste liquid according to claim 1, characterized in that: In step S2, the porous biochar and the hydrophilic agent are mixed in a mass ratio of 1:1 to 2:1; and the mass percentage of the hydrophilic agent is 1 to 10%.

10. The method for preparing a cerium-based adsorbent for treating radioactive waste liquid according to claim 1, characterized in that: In step S2, the hydrothermal treatment method is: after mixing the porous biochar with a hydrophilic reagent, hydrothermally treat it at 60-80°C and 0.1-3MPa for 3-4h to obtain the hydrophilic porous biochar matrix.

11. The method for preparing a cerium-based adsorbent for treating radioactive waste liquid according to claim 1, characterized in that: The cerium source is Ce(NO3)3·6H2O; The iron source is Fe(NO3)3·9H2O and / or FeCl3·6H2O.

12. The method for preparing a cerium-based adsorbent for treating radioactive waste liquid according to claim 1, characterized in that: The molar ratio of Fe to Ce in the metal salt solution is 10:

1.

13. The method for preparing a cerium-based adsorbent for treating radioactive waste liquid according to claim 1, characterized in that: In step S4, the mixed solution is transferred to a stainless steel autoclave and reacted at 180-200° C. and 0.1-3 MPa for 40-50 hours.

14. The method for preparing a cerium-based adsorbent for treating radioactive waste liquid according to claim 1, characterized in that: In step S4, the composite oxide is calcined at 500-550° C. for 10-12 hours to obtain a cerium-based adsorbent.

15. A cerium-based adsorbent for treating radioactive waste liquid, prepared according to the preparation method of the cerium-based adsorbent for treating radioactive waste liquid according to any one of claims 1 to 14, characterized in that: The cerium-based adsorbent is prepared from a hydrophilic porous biocarbon matrix and ferrocerium oxide by a hydrothermal method, and the ferrocerium oxide is carried on the hydrophilic porous biocarbon matrix to form a composite adsorbent.

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