Preparation method of carbon-based bulk As(III) oxidation-adsorption material

Abstract

The present application relates to a method for preparing a carbon-based bulk As(III) oxidation-adsorption material, and belongs to the field of inorganic arsenic adsorption technology. A method for preparing a carbon-based bulk As(III) oxidation-adsorption material, the specific steps of which are as follows: taking bamboo stems, immersing them in a stannous chloride and hydrochloric acid solution to obtain a sensitized biomass matrix; immersing the sensitized biomass matrix in a mixed solution of ammonia and silver nitrate to obtain an activated biomass matrix; transferring the activated biomass matrix to a mixed solution of copper ions and a reducing agent to obtain a copper-plated biomass; immersing the copper-plated biomass in a ferrous chloride solution and freeze-drying it to obtain an iron-doped copper hydroxide-modified biomass; transferring the dried iron-doped copper hydroxide-modified biomass to a tubular furnace, pyrolyzing it under inert gas protection to obtain a high-performance carbon-based bulk As(III) oxidation-adsorption material; and efficiently oxidizing and adsorbing arsenite ions.

Description

Technical Field

[0001] The present application relates to a method for preparing a carbon-based bulk As(III) oxidation-adsorption material, belonging to the technical field of inorganic arsenic adsorption. Background Art

[0002] Among numerous arsenic removal technologies, adsorption is widely considered one of the most promising due to its scalability, high efficiency, ease of operation, low cost, and sustainability. Adsorption materials are the core of adsorption arsenic removal technology. Among them, copper-based nanomaterials, particularly copper oxide (CuO), which exhibits a high zero-point charge, excellent electrochemical oxidation resistance, and acid / alkali resistance, are highly effective arsenic adsorbents. Most of the copper active sites can be regenerated and reused using NaOH solution. However, CuO's adsorption performance for highly toxic and highly mobile As(III) is far lower than that for As(V). Therefore, improving the adsorption of highly toxic and highly mobile As(III) by copper-based nanomaterials has become a challenge for those skilled in the art.

[0003] Improving the oxidation performance of copper-based nanoadsorbents, oxidizing As(III) to As(V) and then adsorbing it, is an effective strategy for enhancing the adsorption and removal of arsenite ions. A common solution is to composite copper-based nanoadsorbents with oxidizing components (such as MnO2) to enhance their oxidation performance. However, oxidizing components typically have low adsorption properties, limiting the overall adsorption capacity of the composite. Furthermore, nanoadsorbents exhibit significant advantages in pollutant removal due to their high surface area and abundant active sites. However, nanoparticles are prone to agglomeration, resulting in reduced active site utilization and even the potential for secondary water pollution due to particle leakage. Introducing a high-surface-area matrix material (such as porous carbon or oxide supports) is an effective strategy. Matrix materials not only effectively disperse nanoparticles and increase the exposure of active sites, but also enhance post-saturation recovery performance through optimized material structure design, thereby improving the practicality and environmental safety of the adsorbent material. Therefore, developing copper-based composite nanoadsorbents that combine efficient As(III) oxidation, high adsorption capacity, good dispersibility, and recyclability is of great significance. Summary of the Invention

[0004] To address the issues of low As(III) adsorption efficiency and nanoparticle aggregation and fixation during adsorption, a method for preparing a carbon-based bulk As(III) oxidation-adsorption material is provided. Iron-doped copper oxide is in situ modified on the surface of bulk biochar. Through the interaction between iron and copper ions, As(III) is efficiently oxidized to As(V) and then adsorbed, simultaneously improving the material's oxidation and adsorption properties, thereby effectively increasing As(III) removal efficiency. Furthermore, after saturation with inorganic arsenic adsorption, the material can be recovered by simple filtration and effectively reused.

[0005] This application solves the above technical problems through the following technical solutions:

[0006] A method for preparing a carbon-based bulk As(III) oxidation-adsorption material is characterized in that the bulk As(III) oxidation-adsorption material is obtained by treating biomass as follows. The specific steps are as follows:

[0007] Step 1: Take a 2-3 mm thick bamboo stem, completely immerse it in a 0.1-0.15 mol / L stannous chloride solution and a 60 mL / L hydrochloric acid solution, let it stand for 0.5 h, take it out and rinse it with ultrapure water to obtain a sensitized biomass matrix;

[0008] The amount of reducing ions on the biomass surface can be controlled by controlling the concentration of stannous ions in the sensitizing solution. Too high a concentration will lead to Sn 2+ There are problems such as excessive accumulation on the surface of the biomass matrix, uneven activation, catalytic failure, and easy oxidation of the solution; 2+ When the concentration is insufficient, Ag cannot be effectively reduced. + , causing Ag 0 Insufficient or unevenly distributed activation points prevent copper from being deposited evenly;

[0009] Step 2: immersing the sensitized biomass matrix into a mixed solution of 5 mL / L ammonia water and 0.08-0.12 mol / L silver nitrate and allowing it to stand for 15 minutes. After taking it out, it is washed with ultrapure water to obtain an activated biomass matrix;

[0010] The catalytic active sites on the biomass surface can be controlled by controlling the concentration of silver ions in the activation solution. Too high a concentration will result in the generation of Ag 0 The particles are large, the catalytic activity is reduced, the coating is discontinuous, and it is easy to have problems such as partial copper plating failure and poor adhesion; too low a concentration will result in the deposition of Ag. 0 There are too few catalytic sites, making it difficult to initiate subsequent chemical copper plating;

[0011] Step 3: transferring the activated biomass matrix to a mixed solution having a copper ion concentration of 0.04-0.1 mol / L and a reducing agent formaldehyde concentration of 40-60 mL / L, stirring at room temperature at a speed of 300-600 rpm for 1-3 hours, taking it out and washing it with ultrapure water to obtain copper-plated biomass;

[0012] The thickness of the biomass surface modification layer is controlled by controlling the concentrations of copper salt ions and reducing agents. If the concentration is too high, the copper plating layer will be too thick, and the subsequent iron doping process will not be able to completely oxidize the plating layer, resulting in a decrease in the adsorption activity of the final composite material. If the concentration is too low, the copper plating layer will be too thin, and the amount of active substances modified on the biomass surface will decrease, thereby reducing the overall adsorption activity of the composite material.

[0013] Step 4, immersing the copper-plated biomass in a 0.1-0.25 mol / L ferrous chloride solution, allowing it to stand for 2-8 hours, taking it out and washing it with ultrapure water, and freeze-drying it for 24-48 hours to obtain an iron-doped copper hydroxide-modified biomass;

[0014] The ratio of iron ions to copper ions in the biomass surface modification layer is controlled by synergistically regulating the concentration of ferrous ions and the immersion time. Too high or too low a ratio will affect the formation of oxygen vacancies on the material surface, thereby affecting the oxidation effect of As(III).

[0015] Step 5, the dried iron-doped copper hydroxide-modified biomass is transferred to a tubular furnace and pyrolyzed at 300-500°C for 1-4 hours under inert gas (Ar) protection to obtain a high-performance carbon-based bulk As(III) oxidation-adsorption material; by synergistically regulating the pyrolysis temperature and time, the carbonization degree of the biomass and the oxidation degree of the modified active substance are simultaneously controlled. If the pyrolysis temperature or time is too low, the carbonization degree of the biomass matrix will be insufficient, and the dehydration degree of the surface-modified metal hydroxide will be low, affecting the oxidation and adsorption properties of the material; if the pyrolysis temperature is too high or the time is too long, the biomass matrix will be excessively carbonized, the toughness will be reduced and the brittleness will be increased, making it difficult to maintain the block shape during use. At the same time, the carbon in the matrix material at high temperature easily reduces the metal ions to zero valence, affecting its oxidation and adsorption properties.

[0016] The advantages of the above technical solution are: in steps 1 to 3, the biomass is pretreated and a copper coating is coated on the surface of the bamboo by a chemical reduction method, which can achieve in-situ uniform coating and maximize the utilization of the natural three-dimensional pore structure and specific surface area of ​​the biomass; in step 4, iron ions are doped into the copper coating layer by an oxidative corrosion method to achieve a synergistic effect of iron ions and copper ions, generate oxygen vacancies, and efficiently oxidize As(III) that is difficult to adsorb in water into As(V) that is easy to adsorb, thereby improving the adsorption and removal capacity and efficiency of the composite material for arsenite ions in water; in step 5, the carbonization of the biomass matrix and the dehydration process of the surface-coated hydroxide are simultaneously achieved by a one-step pyrolysis method to obtain a block biomass carbon material modified with iron-doped copper oxide nanoparticles, which is used for the efficient oxidation and adsorption of arsenite pollutants in water.

[0017] On the basis of the above technical solution, the inventors have made the following improvements and improvements to the above technical solution:

[0018] Furthermore, in step 1, the solid-liquid ratio of the sensitizing solution to the biomass is 1:10.

[0019] Furthermore, in step 2, the solid-liquid ratio of the activation solution to the biomass is 1:10.

[0020] Furthermore, in step 3, the solid-liquid ratio of the copper plating solution to the biomass is 1:40.

[0021] Furthermore, in step 4, the solid-liquid ratio of the ferrous chloride solution to the biomass is 1:10.

[0022] Furthermore, in step 5, the heating rate during the pyrolysis process is 5°C / min.

[0023] This application has the following beneficial effects:

[0024] 1. The preparation method of the present application is simple in process, low in cost, and environmentally friendly. It can use waste bamboo biomass and abundant copper and iron metal raw materials to obtain highly active carbon-based block As(III) oxidation-adsorption materials. The block composite material has a macroscopic block structure, which can achieve simple filtration recovery and efficient regeneration after adsorption saturation, thereby realizing recycling; biochar is used as a substrate, which serves as a porous support material to load nanoparticles to prepare a composite adsorption material; it can simultaneously solve the problems of nanoparticle aggregation and fixation; at the same time, it avoids the risk of nanoparticles being released into the treated water body by the nanoparticle adsorbent, reduces the potential damage to the ecosystem and human health, and reduces the cost of water treatment.

[0025] 2. The preparation method of the present application uses a chemical reduction method to coat the biomass surface with a copper layer. The copper layer is tightly connected to the substrate and will not fall off, and is evenly modified on the biomass surface with a complex pore structure.

[0026] 3. The preparation method of the present application introduces iron ions into the copper plating layer through an oxidation-reduction method, simultaneously realizes the doping of iron ions and the oxidation of the copper plating layer, and generates iron-copper metal hydroxide on the surface of the biomass. The iron doping is evenly distributed and the doping amount is controllable. By controlling the ratio of iron ions to copper ions, the amount of oxygen vacancies and the efficiency of active oxygen generation can be controlled, and the difficult-to-adsorb As(III) is efficiently oxidized to easily adsorbed As(V), thereby improving the adsorption capacity and efficiency of the composite material for arsenite ions.

[0027] 4. In the preparation method of the present application, the biocarbon matrix maintains the natural three-dimensional pore structure of bamboo biomass, and the surface-modified metal oxides are tightly combined, which effectively improves the aggregation of active nanoparticles, the utilization rate of adsorption active sites, and promotes the full exposure of active components.

[0028] 5. The preparation method of the present application anchors rice particles on the surface of the block biocarbon matrix through chemical reduction combined with redox doping technology, avoiding the leakage of iron ions and copper ions into the water body during the adsorption process and causing secondary pollution. At the same time, the biocarbon has a certain toughness, which avoids the collapse and dissociation of the macroscopic block structure during use, thereby improving the stability of the adsorbent.

[0029] 6. This application provides a carbon-based, high-performance, bulk As(III) oxidation-adsorption composite material, Fe / CuO@BC, for use in the adsorption and removal of arsenite ion pollutants in water. This adsorption material exhibits excellent oxidation activity, effectively oxidizing As(III) in water to a ratio of up to 40%, as well as rapid adsorption activity, achieving an adsorption capacity of over 90% within 1 hour and an adsorption capacity of 150-200 mg / g at adsorption equilibrium. The composite material's oxidation-adsorption active sites exhibit highly efficient regeneration performance exceeding 95%, retaining over 80% of its arsenite ion adsorption efficiency after five cycles of use. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the SEM image of the copper-plated biochar prepared in Comparative Example 1;

[0031] Figure 2 This is an SEM image of the carbon-based bulk As(III) oxidation-adsorption material prepared in Example 1;

[0032] Figure 3 Optical images of the carbon-based bulk As(III) oxidation-adsorption materials prepared in Examples 1 and 2;

[0033] Figure 4 X-ray diffraction pattern of the carbon-based bulk As(III) oxidation-adsorption material prepared in Example 1;

[0034] Figure 5 This is an X-ray photoelectron spectrum of the carbon-based bulk As(III) oxidation-adsorption material prepared in Example 1 after saturation with As(III);

[0035] Figure 6 Graph showing the adsorption capacity of the composite materials prepared in Example 1 and Comparative Examples 1, 2, and 3 for arsenite ions;

[0036] Figure 7 This is the adsorption isotherm of arsenite ions by the carbon-based bulk As(III) oxidation-adsorption material prepared in Example 1;

[0037] Figure 8 The adsorption efficiency of arsenite ions in the carbon-based bulk As(III) oxidation-adsorption material prepared in Example 1 was analyzed by five recovery and regeneration cycles. DETAILED DESCRIPTION

[0038] The following embodiments, in conjunction with the accompanying drawings, are only intended to illustrate the technical solutions described in the claims and are not intended to limit the scope of protection of the claims.

[0039] Example 1

[0040] A method for preparing a carbon-based bulk As(III) oxidation-adsorption material, wherein bamboo biomass is treated as follows to obtain a bulk composite material, the specific steps being as follows:

[0041] Step (1), washing the discarded bamboo with deionized water, drying the surface moisture, removing surface impurities, and cutting into bamboo slices with a thickness of 2.5 mm; preparing solution A (c(Sn 2+ ) = 0.12 mol / L): Take 1.5 mL of concentrated hydrochloric acid and add it to 23.5 mL of deionized water. Weigh 0.6767 g of stannous chloride dihydrate and add it to the hydrochloric acid solution and stir until completely dissolved. Place 8 pieces of bamboo biomass in solution A and let it stand for 0.5 h. After taking it out, wash it three times with deionized water to obtain the sensitized biomass.

[0042] Step (2), prepare solution B (c (Ag + )=0.1mol / L): 0.125mL of ammonia water was added to 25mL of deionized water, 0.4244g of silver nitrate was weighed and added to the ammonia solution, and stirred until completely dissolved; the biomass sensitized in step (1) was immersed in solution B and allowed to stand for 15min, and then taken out and washed three times with deionized water to obtain the activated biomass;

[0043] Step (3), prepare solution C (c (Cu 2+ )=0.06mol / L): 95mL of deionized water was stirred at 500rpm, and 1.023g of copper chloride dihydrate, 4.233g of potassium sodium tartrate, 0.8g of sodium hydroxide, 0.372g of sodium carbonate and 5mL of formaldehyde were added in sequence. After complete dissolution, the biomass activated in step (2) was immersed in solution C and stirred at 500rpm for 2h. After being taken out, it was washed three times with deionized water to obtain the copper-plated biomass;

[0044] Step (4), prepare solution D: (c(Fe 2+ )=0.12mol / L): Weigh 0.5964g of ferrous chloride tetrahydrate, dissolve it in 25mL of deionized water and ultrasonicate it for 5min, immerse the copper-plated biomass in step (3) into solution D, let it stand for 5h, then wash it three times with deionized water, and freeze-dry it for 36h to obtain the biomass modified with iron-copper hydroxide;

[0045] Step (5), the 8 pieces of iron-copper hydroxide-modified biomass obtained after treatment in step (4) are transferred to a tube furnace, heated to 400°C at a rate of 5°C / min under Ar atmosphere protection, and kept warm for 2 hours to obtain a bulk carbon-based bulk As(III) oxidation-adsorption material.

[0046] Example 2

[0047] A method for preparing a carbon-based bulk As(III) oxidation-adsorption material, wherein bamboo biomass is treated as follows to obtain a bulk composite material, the specific steps being as follows:

[0048] Step (1), washing the discarded bamboo with deionized water, drying the surface moisture, removing surface impurities, and cutting into bamboo slices with a thickness of 2 mm; preparing solution A (c(Sn 2+ ) = 0.1 mol / L): Take 1.2 mL of concentrated hydrochloric acid and add it to 18.8 mL of deionized water. Weigh 0.4513 g of stannous chloride dihydrate and add it to the hydrochloric acid solution and stir until completely dissolved. Place 8 pieces of bamboo biomass in solution A and let it stand for 0.5 h. After taking it out, wash it three times with deionized water to obtain the sensitized biomass.

[0049] Step (2), prepare solution B (c (Ag + )=0.08mol / L): Take 0.1mL of ammonia water and add it to 20mL of deionized water, weigh 0.2718g of silver nitrate and add it to the above ammonia solution, and stir until it is completely dissolved; immerse the biomass after sensitization in step (1) in solution B and let it stand for 15min, take it out and wash it three times with deionized water to obtain the activated biomass;

[0050] Step (3), prepare solution C (c (Cu 2+ )=0.04mol / L): 76mL of deionized water was stirred at 300rpm, and 0.5456g of copper chloride dihydrate, 3.3864g of potassium sodium tartrate, 0.64g of sodium hydroxide, 0.2976g of sodium carbonate and 4mL of formaldehyde were added in sequence. After complete dissolution, the biomass activated in step (2) was immersed in solution C and stirred at 300rpm for 1h. After being taken out, it was washed three times with deionized water to obtain the copper-plated biomass;

[0051] Step (4), prepare solution D (c (Fe 2+ )=0.1mol / L): Weigh 0.3976g of ferrous chloride tetrahydrate, dissolve it in 20mL of deionized water and ultrasonicate it for 5min, immerse the copper-plated biomass in step (3) into solution D, let it stand for 2h, then wash it three times with deionized water, and freeze-dry it for 24h to obtain the iron-copper hydroxide-modified biomass;

[0052] Step (5), the 8 pieces of iron-copper hydroxide-modified biomass obtained after treatment in step (4) are transferred to a tube furnace, heated to 400°C at a rate of 5°C / min under Ar atmosphere protection, and kept warm for 2 hours to obtain a bulk carbon-based bulk As(III) oxidation-adsorption material.

[0053] Example 3

[0054] A method for preparing a carbon-based bulk As(III) oxidation-adsorption material, wherein bamboo biomass is treated as follows to obtain a bulk composite material, the specific steps being as follows:

[0055] Step (1), washing the discarded bamboo with deionized water, drying the surface moisture, removing surface impurities, and cutting into bamboo slices with a thickness of 3 mm; preparing solution A (c(Sn 2+ ) = 0.15 mol / L): Take 1.8 mL of concentrated hydrochloric acid and add it to 28.2 mL of deionized water. Weigh 1.0153 g of stannous chloride dihydrate and add it to the hydrochloric acid solution and stir until completely dissolved. Place 8 pieces of bamboo biomass in solution A and let it stand for 0.5 h. After taking it out, wash it three times with deionized water to obtain the sensitized biomass.

[0056] Step (2), prepare solution B (c (Ag + )=0.12mol / L): Take 0.15mL of ammonia water and add it to 30mL of deionized water, weigh 0.6115g of silver nitrate and add it to the above ammonia solution, and stir until it is completely dissolved; immerse the biomass after sensitization in step (1) in solution B and let it stand for 15min, take it out and wash it three times with deionized water to obtain the activated biomass;

[0057] Step (3), prepare solution C (c (Cu 2+ )=0.1mol / L): 112.8mL of deionized water was stirred at 600rpm, and 2.046g of copper chloride dihydrate, 3.3864g of potassium sodium tartrate, 0.64g of sodium hydroxide, 0.2976g of sodium carbonate and 7.2mL of formaldehyde were added in sequence. After complete dissolution, the biomass activated in step (2) was immersed in solution C and stirred at 600rpm for 3h. After being taken out, it was washed three times with deionized water to obtain the copper-plated biomass;

[0058] Step (4), prepare solution D (c (Fe 2+ )=0.25mol / L): Weigh 1.4911g of ferrous chloride tetrahydrate, dissolve it in 30mL of deionized water and ultrasonicate it for 5min, immerse the copper-plated biomass in step (3) into solution D, let it stand for 8h, then wash it three times with deionized water, and freeze-dry it for 48h to obtain the biomass modified with iron-copper hydroxide;

[0059] Step (5), the 8 pieces of iron-copper hydroxide-modified biomass obtained after treatment in step (4) are transferred to a tube furnace, heated to 400°C at a rate of 5°C / min under Ar atmosphere protection, and kept warm for 2 hours to obtain a bulk carbon-based bulk As(III) oxidation-adsorption material.

[0060] Example 4

[0061] A method for preparing a carbon-based bulk As(III) oxidation-adsorption material, wherein bamboo biomass is treated as follows to obtain a bulk composite material, the specific steps being as follows:

[0062] Step (1), washing the discarded bamboo with deionized water, drying the surface moisture, removing surface impurities, and cutting into bamboo slices with a thickness of 2.5 mm; preparing solution A (c(Sn 2+ ) = 0.12 mol / L): Take 1.5 mL of concentrated hydrochloric acid and add it to 23.5 mL of deionized water. Weigh 0.6767 g of stannous chloride dihydrate and add it to the hydrochloric acid solution and stir until completely dissolved. Place 8 pieces of bamboo biomass in solution A and let it stand for 0.5 h. After taking it out, wash it three times with deionized water to obtain the sensitized biomass.

[0063] Step (2), prepare solution B (c (Ag + )=0.1mol / L): 0.125mL of ammonia water was added to 25mL of deionized water, 0.4244g of silver nitrate was weighed and added to the ammonia solution, and stirred until completely dissolved; the biomass sensitized in step (1) was immersed in solution B and allowed to stand for 15min, and then taken out and washed three times with deionized water to obtain the activated biomass;

[0064] Step (3), prepare solution C (c (Cu 2+ )=0.06mol / L): 95mL of deionized water was stirred at 500rpm, and 1.023g of copper chloride dihydrate, 4.233g of potassium sodium tartrate, 0.8g of sodium hydroxide, 0.372g of sodium carbonate and 5mL of formaldehyde were added in sequence. After complete dissolution, the biomass activated in step (2) was immersed in solution C and stirred at 500rpm for 2h. After being taken out, it was washed three times with deionized water to obtain the copper-plated biomass;

[0065] Step (4), prepare solution D: (c(Fe 2+ )=0.12mol / L): Weigh 0.5964g of ferrous chloride tetrahydrate, dissolve it in 25mL of deionized water and ultrasonicate it for 5min, immerse the copper-plated biomass in step (3) into solution D, let it stand for 5h, then wash it three times with deionized water, and freeze-dry it for 36h to obtain the biomass modified with iron-copper hydroxide;

[0066] Step (5), the 8 pieces of iron-copper hydroxide-modified biomass obtained after treatment in step (4) are transferred to a tube furnace, heated to 300°C at a rate of 5°C / min under Ar atmosphere protection, and kept warm for 1 hour to obtain a bulk carbon-based bulk As(III) oxidation-adsorption material.

[0067] Example 5

[0068] A method for preparing a carbon-based bulk As(III) oxidation-adsorption material, wherein bamboo biomass is treated as follows to obtain a bulk composite material, the specific steps being as follows:

[0069] Step (1), washing the discarded bamboo with deionized water, drying the surface moisture, removing surface impurities, and cutting into bamboo slices with a thickness of 2.5 mm; preparing solution A (c(Sn 2+ ) = 0.12 mol / L): Take 1.5 mL of concentrated hydrochloric acid and add it to 23.5 mL of deionized water. Weigh 0.6767 g of stannous chloride dihydrate and add it to the hydrochloric acid solution and stir until completely dissolved. Place 8 pieces of bamboo biomass in solution A and let it stand for 0.5 h. After taking it out, wash it three times with deionized water to obtain the sensitized biomass.

[0070] Step (2), prepare solution B (c (Ag + )=0.1mol / L): 0.125mL of ammonia water was added to 25mL of deionized water, 0.4244g of silver nitrate was weighed and added to the ammonia solution, and stirred until completely dissolved; the biomass sensitized in step (1) was immersed in solution B and allowed to stand for 15min, and then taken out and washed three times with deionized water to obtain the activated biomass;

[0071] Step (3), prepare solution C (c (Cu 2+ )=0.06mol / L): 95mL of deionized water was stirred at 500rpm, and 1.023g of copper chloride dihydrate, 4.233g of potassium sodium tartrate, 0.8g of sodium hydroxide, 0.372g of sodium carbonate and 5mL of formaldehyde were added in sequence. After complete dissolution, the biomass activated in step (2) was immersed in solution C and stirred at 500rpm for 2h. After being taken out, it was washed three times with deionized water to obtain the copper-plated biomass;

[0072] Step (4), prepare solution D: (c(Fe 2+ )=0.12mol / L): Weigh 0.5964g of ferrous chloride tetrahydrate, dissolve it in 25mL of deionized water and ultrasonicate it for 5min, immerse the copper-plated biomass in step (3) into solution D, let it stand for 5h, then wash it three times with deionized water, and freeze-dry it for 36h to obtain the biomass modified with iron-copper hydroxide;

[0073] Step (5), the 8 pieces of iron-copper hydroxide-modified biomass obtained after treatment in step (4) are transferred to a tube furnace, heated to 500°C at a rate of 5°C / min under Ar atmosphere protection, and kept warm for 4 hours to obtain a bulk carbon-based As(III) oxidation-adsorption material.

[0074] The inorganic arsenic adsorption performance test of the obtained carbon-based bulk As(III) oxidation-adsorption material was carried out by the following steps:

[0075] (1) Place the prepared composite oxidation-adsorption material in a blue-capped bottle, add a certain concentration of arsenite ion solution, and shake at a constant temperature;

[0076] (2) Sampling was performed 10–15 times within the interval of 0–360 min, with 1–3 mL of sample taken each time. The concentration of inorganic arsenic in the water samples was measured by atomic fluorescence spectrometry, and the adsorption kinetics was evaluated by fitting the second-order kinetic adsorption model.

[0077] (3) When the initial arsenite ion concentration was in the range of 1 to 50 mg / L, the oxidation-adsorption column was shaken for 360 min, and 1 to 3 mL of the sample was taken. The inorganic arsenic concentration in the water sample was tested by atomic fluorescence spectrometry, and the Langmuir isotherm model was used to fit the isotherm adsorption curve and calculate the adsorption capacity.

[0078] (4) The adsorption-saturated carbon-based bulk As(III) oxidation-adsorption material was collected and then eluted in a blue-capped bottle with a regeneration eluent (0.5 mol / L NaOH solution, 100 mL) for 5 h. After being taken out, it was rinsed with deionized water and freeze-dried for 12 h. It was then transferred to a tube furnace and heated to 400 °C at a rate of 5 °C / min under Ar atmosphere protection and kept warm for 2 h to obtain the regenerated bulk carbon-based bulk As(III) oxidation-adsorption material, which was then used for the next cycle.

[0079] Comparative Example 1

[0080] The comparative composite oxidation-adsorption material was prepared by the following steps:

[0081] Step (1), washing the discarded bamboo with deionized water, drying the surface moisture, removing surface impurities, and cutting into bamboo slices with a thickness of 2.5 mm; preparing solution A (c(Sn 2+ ) = 0.12 mol / L): Take 1.5 mL of concentrated hydrochloric acid and add it to 23.5 mL of deionized water. Weigh 0.6767 g of stannous chloride dihydrate and add it to the hydrochloric acid solution and stir until completely dissolved. Place 8 pieces of bamboo biomass in solution A and let it stand for 0.5 h. After taking it out, wash it three times with deionized water to obtain the sensitized biomass.

[0082] Step (2), prepare solution B (c (Ag+ )=0.1mol / L): 0.125mL of ammonia water was added to 25mL of deionized water, 0.4244g of silver nitrate was weighed and added to the ammonia solution, and stirred until completely dissolved; the biomass sensitized in step (1) was immersed in solution B and allowed to stand for 15min, and then taken out and washed three times with deionized water to obtain the activated biomass;

[0083] Step (3), prepare solution C (c (Cu 2+ )=0.06mol / L): 95mL of deionized water was stirred at 500rpm, and 1.023g of copper chloride dihydrate, 4.233g of potassium sodium tartrate, 0.8g of sodium hydroxide, 0.372g of sodium carbonate and 5mL of formaldehyde were added in sequence. After complete dissolution, the biomass activated in step (2) was immersed in solution C and stirred at 500rpm for 2h. After being taken out, it was washed three times with deionized water to obtain the copper-plated biomass;

[0084] Step (4), the 8 pieces of copper-plated biomass obtained after the treatment in step (3) are transferred to a tubular furnace, heated to 400°C at a rate of 5°C / min under Ar atmosphere protection, and kept warm for 2 hours to obtain a bulk copper-modified bio-carbon composite material.

[0085] Comparative Example 2

[0086] The comparative composite oxidation-adsorption material was prepared by the following steps:

[0087] Step (1), washing the discarded bamboo with deionized water, drying the surface moisture, removing surface impurities, cutting into bamboo slices with a thickness of 2.5 mm, taking 8 pieces of bamboo biomass and washing them three times with deionized water for later use;

[0088] Step (2), prepare solution D: (c(Fe 2+ )=0.12mol / L): Weigh 0.5964g of ferrous chloride tetrahydrate, dissolve it in 25mL of deionized water and ultrasonicate it for 5min, immerse the biomass after washing in step (1) in solution D, let it stand for 5h, then wash it three times with deionized water, and freeze-dry it for 36h to obtain the biomass modified with iron hydroxide;

[0089] Step (3), the 8 pieces of iron hydroxide modified biomass obtained after the treatment in step (2) are transferred to a tubular furnace, heated to 400°C at a rate of 5°C / min under Ar atmosphere protection, and kept warm for 2 hours to obtain a bulk iron oxide modified biocarbon composite material.

[0090] Comparative Example 3

[0091] The comparative composite oxidation-adsorption material was prepared by the following steps:

[0092] Step (1), washing the discarded bamboo with deionized water, wiping off the surface moisture, removing surface impurities, cutting into bamboo slices with a thickness of 2.5 mm, taking 8 pieces of bamboo biomass, washing them three times with deionized water, and freeze-drying them for 24 hours to obtain dried biomass;

[0093] Step (2), the 8 pieces of biomass obtained after the treatment in step (1) were transferred to a tubular furnace, heated to 400°C at a rate of 5°C / min under Ar atmosphere protection, and kept warm for 2 hours to obtain a block of biochar material.

[0094] The microstructure of comparative example 1 is shown in the attached figure. Figure 1 As shown in the figure, it can be seen that the copper coating layer grows tightly on the surface of the biomass. At the same time, the biochar maintains the natural three-dimensional pore structure of the bamboo biomass, which is conducive to full contact with the pollutant ions in the water. Figure 2 The microstructure of Example 1 is shown in the figure. It can be seen from the figure that after doping with iron oxide, the copper particles on the surface of the biochar are nanosized, with a particle size of about 50nm, which fully exposes the active sites and oxidizes and adsorbs arsenite ions in water. Figure 3 The optical photographs of Examples 1 and 2 show that the composite material has a macroscopic bulk structure. The results show that by chemical reduction copper plating and iron oxide doping and pyrolysis, a macroscopic bulk and microscopic nanoparticle-modified porous three-dimensional carbon structure composite material can be prepared.

[0095] Attachment Figure 4 The X-ray diffraction pattern of Example 1 (the horizontal axis 2θ represents the diffraction angle (degrees), and the vertical axis Intensity represents the intensity (au)) shows a broad diffraction peak and two sets of strong diffraction peaks. The broad diffraction peak corresponds to amorphous carbon in the biochar matrix, while the two sets of strong diffraction peaks correspond to iron oxide and copper oxide, respectively. The crystal structure characterization results indicate the successful preparation of an iron-doped copper oxide-modified biochar composite.

[0096] Attachment Figure 5 (The horizontal axis is electron binding energy (eV), and the vertical axis is intensity (au)) is the X-ray photoelectron energy spectrum of the As3d orbital after saturation of adsorption of arsenite ions in Example 1. The spectrum can be divided into two fitting peaks, corresponding to pentavalent arsenate ions (accounting for 48.32%) and trivalent arsenite ions (accounting for 51.68%), indicating that about 50% of As(III) is oxidized to As(V) and then adsorbed, indicating that the composite material has excellent oxidation and adsorption properties.

[0097] Attachment Figure 6(The horizontal axis is contact time (min), and the vertical axis is residual concentration of As(III) (mg / g)) are the test results of the adsorption performance of arsenite ions in Example 1 and Comparative Examples 1, 2, and 3. Comparative Example 3 has almost no arsenic adsorption characteristics, while Comparative Examples 1 and 2 have the same As(III) removal trend but poor removal effect. Example 1 quickly removes about 90% of arsenite ions at 1, and the equilibrium concentration is less than 3 mg / L. This shows that the synergistic oxidation effect of iron oxide and copper oxide after doping can effectively improve the removal efficiency of highly toxic arsenite ions. At the same time, kinetic fitting was used for the adsorption results. Example 2 and Comparative Examples 1 and 2 all used a composite pseudo-second-order kinetic model, indicating that their adsorption processes were all chemical adsorption.

[0098] Attachment Figure 7 (The horizontal axis is the initial concentration of As(III) (mg / L), and the vertical axis is the As(III) adsorption capacity (mg / g)) reveals the performance of the bulk Fe / CuO@BC oxidation-adsorption composite material in removing arsenite ions. Example 1 R fitted by the Langmuir model 2 The values ​​are all greater than 0.9, which further verifies its chemical adsorption characteristics, and the fitting results show that its maximum adsorption capacity is 159.3 mg / g.

[0099] Attachment Figure 8 (The horizontal axis represents the regeneration cycle, and the vertical axis represents the As(III) adsorption removal efficiency.) This data demonstrates the stability and recyclability of the carbon-based bulk As(III) oxidation-adsorption material prepared in Example 1 for As(III) removal. After five adsorption and regeneration cycles, the adsorption efficiency remained above 80%, demonstrating excellent cyclic stability.

[0100] The results of the examples show that the present application uses a chemical reduction method and pyrolysis after oxidation to prepare a high-performance carbon-based bulk As(III) oxidation-adsorption material, which can efficiently oxidize As(III) and then adsorb it, effectively improving its adsorption capacity, is easy to recycle, has strong cyclic stability, and has excellent properties such as no secondary water pollution.

[0101] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a carbon-based bulk trivalent arsenic oxidation-adsorption material, characterized in that: The bamboo biomass is processed as follows to obtain a block composite material, and the specific steps are as follows: Step (1), washing the discarded bamboo with deionized water, drying the surface moisture, removing surface impurities, and cutting into bamboo slices with a thickness of 2.5 mm; preparing solution A, wherein c(Sn 2+ ) = 0.12 mol / L: Add 1.5 mL of concentrated hydrochloric acid to 23.5 mL of deionized water, weigh 0.6767 g of stannous chloride dihydrate and add it to the hydrochloric acid solution, stirring until completely dissolved; place 8 pieces of bamboo biomass in solution A and let it stand for 0.5 h. After removal, wash it three times with deionized water to obtain the sensitized biomass; Step (2), prepare solution B, wherein c(Ag + )=0.1mol / L: add 0.125mL of ammonia water to 25mL of deionized water, weigh 0.4244g of silver nitrate and add it to the ammonia solution, stirring until it is completely dissolved; immerse the biomass sensitized in step (1) in solution B and let it stand for 15min, take it out and wash it three times with deionized water to obtain the activated biomass; Step (3), prepare solution C, wherein c(Cu 2+ )=0.06mol / L: 1.023g copper chloride dihydrate, 4.233g potassium sodium tartrate, 0.8g sodium hydroxide, 0.372g sodium carbonate and 5mL formaldehyde were added to 95mL deionized water at a stirring speed of 500rpm. After complete dissolution, the biomass activated in step (2) was immersed in solution C and stirred at 500rpm for 2h. After being taken out, it was washed three times with deionized water to obtain the copper-plated biomass; Step (4), prepare solution D, wherein c(Fe 2+ )=0.12mol / L: Weigh 0.5964g of ferrous chloride tetrahydrate, dissolve it in 25mL of deionized water and ultrasonicate it for 5min. Immerse the copper-plated biomass in step (3) in solution D, let it stand for 5h, then wash it three times with deionized water, and freeze-dry it for 36h to obtain the biomass modified with iron-copper hydroxide; Step (5), the 8 pieces of iron-copper hydroxide-modified biomass obtained after treatment in step (4) are transferred to a tubular furnace, heated to 400°C at a rate of 5°C / min under Ar atmosphere protection, and kept warm for 2 hours to obtain a bulk carbon-based trivalent arsenic oxidation-adsorption material.

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