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

Abstract

The invention relates to a preparation method of a carbon-based blocky As (III) oxidation-adsorption material, and belongs to the technical field of inorganic arsenic adsorption. The invention relates to a preparation method of a carbon-based blocky As (III) oxidation-adsorption material, which comprises the following specific steps: immersing a bamboo stem into a stannous chloride and hydrochloric acid solution to obtain a sensitized biomass matrix; immersing the sensitized biomass matrix into a mixed solution of ammonia water and silver nitrate to obtain an activated biomass matrix; transferring the activated biomass matrix into a mixed solution of copper ions and a reducing agent to obtain copper-plated biomass; immersing the copper-plated biomass into a ferrous chloride solution, and performing freeze drying to obtain iron-doped copper hydroxide modified biomass; and transferring the dried iron-doped copper hydroxide modified biomass into a tubular furnace, and pyrolyzing under the protection of inert gas to obtain the high-performance carbon-based blocky As (III) oxidation-adsorption material. Arsenious acid ions can be efficiently oxidized and adsorbed.

Description

Technical Field

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

[0002] Among many arsenic removal technologies, the adsorption method is generally considered to be one of the most promising methods due to its strong scalability, high efficiency, simple operation, low cost, and sustainability. The adsorption material is the core of the adsorption arsenic removal technology. Among them, copper-based nanomaterials, especially copper oxide (CuO) with high zero point charge, excellent anti-electrochemical oxidation property, and acid / alkali resistance, is an efficient arsenic adsorbent, and most of the copper active sites can be regenerated by NaOH solution for reuse. However, the adsorption performance of CuO for highly toxic and highly mobile As(III) is much lower than that of As(V). Therefore, how to improve the adsorption of copper-based nanomaterials for highly toxic and highly mobile As(III) has become a problem to be solved by those skilled in the art.

[0003] Improving the oxidation performance of copper-based nano-adsorbents and oxidizing As(III) to As(V) before adsorption is an effective strategy to improve the adsorption and removal of arsenite ions. A common solution is to composite copper-based nano-adsorbents with oxidizing components (such as MnO2) to enhance their oxidation performance. However, the oxidizing components usually have low adsorption performance, resulting in limited overall adsorption capacity of the composite material. In addition, nano-adsorbents show significant advantages in pollutant removal due to their high specific surface area and abundant active sites. However, nanoparticles are prone to agglomeration, resulting in a decrease in the utilization rate of active sites and even possible secondary pollution of water bodies due to particle leakage. Introducing a matrix material with a high specific surface area (such as porous carbon, oxide carrier, etc.) is an effective strategy. The matrix material can not only effectively disperse nanoparticles and improve the exposure of active sites, but also enhance the recovery performance after adsorption saturation by optimizing the material structure design, thereby improving the practicality and environmental safety of the adsorption material. Therefore, it is of great significance to develop a copper-based composite nano-adsorbent with efficient As(III) oxidation, high adsorption capacity, good dispersibility, and recyclability. Summary of the Invention

[0004] In order to solve the problems of low adsorption efficiency of As(III) and aggregation and fixation of nanoparticles during the adsorption process, a preparation method of 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, which can efficiently oxidize As(III) to As(V) through the interaction of iron ions and copper ions and then adsorb it, synchronously improving the oxidation and adsorption performance of the material, thereby effectively improving the removal efficiency of As(III); at the same time, after being saturated with inorganic arsenic adsorption, it can be recycled by simple filtration and effectively regenerated for reuse.

[0005] This application solves the above technical problems through the following technical solutions: A method for preparing a carbon-based bulk As(III) oxidation-adsorption material, which is special in that the bulk As(III) oxidation-adsorption material is obtained by treating biomass as follows, and the specific steps are as follows: Step 1, take a bamboo stem with a thickness of 2-3 mm, completely immerse it in a solution of 0.1-0.15 mol / L stannous chloride and 60 mL / L hydrochloric acid, let it stand for 0.5 h, take it out and wash it with ultrapure water to obtain a sensitized biomass matrix; 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 result in Sn 2+ There are many problems such as excessive accumulation on the surface of the biomass matrix, uneven activation, catalytic failure, and easy oxidation of the solution; Sn 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; 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 letting it stand for 15 minutes, taking it out and washing it with ultrapure water to obtain an activated biomass matrix; 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 concentration will result in the deposition of Ag 0 There are too few catalytic points, making it difficult to start subsequent chemical copper plating; Step 3, transferring the activated biomass matrix to a mixed solution with 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 a copper-plated biomass; The thickness of the biomass surface modification layer is controlled by controlling the concentration 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. Step 4: Immerse the copper-plated biomass into a ferrous chloride solution with a concentration of 0.1 - 0.25 mol / L, let it stand for 2 - 8 h, take it out, wash it with ultrapure water, and freeze-dry it for 24 - 48 h to obtain the biomass modified with iron-doped copper hydroxide; By coordinately regulating the concentration of ferrous ions and the impregnation time, the ratio of iron ions to copper ions in the surface modification layer of the biomass can be controlled. Too high or too low a ratio will affect the generation of oxygen vacancies on the material surface, thereby affecting the oxidation effect on As(III); Step 5: Transfer the dried biomass modified with iron-doped copper hydroxide to a tubular furnace, and pyrolyze it at 300 - 500 °C for 1 - 4 h under the protection of an inert gas (Ar) to obtain a high-performance carbon-based bulk As(III) oxidation-adsorption material; by coordinately regulating the pyrolysis temperature and time, the carbonization degree of the biomass and the oxidation degree of the surface-modified active substances can be 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 performance of the material; if the pyrolysis temperature is too high or the time is too long, the biomass matrix will be over-carbonized, the toughness will decrease and the brittleness will increase, and it will be difficult to maintain the bulk shape during use. At the same time, the carbon in the matrix material at high temperature is likely to reduce the metal ions to zero valence, affecting its oxidation and adsorption performance.

[0006] The advantages of the above technical solutions are as follows: In Steps 1 - 3, the biomass is pretreated, and the copper coating is coated on the bamboo surface by 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, ferrous ions are doped into the copper coating layer by oxidation corrosion method to achieve the synergistic effect of ferrous ions and copper ions, generate oxygen vacancies, and efficiently oxidize the difficult-to-adsorb As(III) in water into the easily-adsorbable As(V), thereby improving the adsorption removal capacity and efficiency of the composite material for arsenite ions in water; in Step 5, through one-step pyrolysis method, the carbonization of the biomass matrix and the dehydration process of the surface-coated hydroxide are simultaneously achieved, and a bulk biomass carbon material modified with iron-doped copper oxide nanoparticles is obtained for efficiently oxidizing and adsorbing arsenite pollutants in water.

[0007] Based on the above technical solutions, the inventor makes the following improvements and enhancements to the above technical solutions: Further, in Step 1, the solid-liquid ratio of the sensitization solution to the biomass is 1:10.

[0008] Further, in Step 2, the solid-liquid ratio of the activation solution to the biomass is 1:10.

[0009] Further, in Step 3, the solid-liquid ratio of the copper plating solution to the biomass is 1:40.

[0010] Further, in the step 4, the solid-liquid ratio of the ferrous chloride solution to the biomass is 1:10.

[0011] Further, in the step 5, the heating rate during the pyrolysis process is 5 °C / min.

[0012] The present application has the following beneficial effects: 1. The preparation method of the present application has a simple process, low cost, and is environmentally friendly. It can use waste bamboo biomass and abundant reserves of copper and iron metal raw materials to obtain a carbon-based bulk As(III) oxidation-adsorption material with high activity. This bulk composite material has a macroscopic bulk structure, which can achieve simple filtration recovery and efficient regeneration after adsorption saturation, and realize 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 that the nanoparticle adsorbent may face the release of nanoparticles into the treated water body, reduces the potential damage to the ecosystem and human health, and reduces the water treatment cost.

[0013] 2. The preparation method of the present application coats a copper-plated layer on the surface of the biomass through a chemical reduction method. The coating is tightly connected to the substrate and will not fall off, and is uniformly modified on the surface of the biomass with a complex pore structure.

[0014] 3. The preparation method of the present application introduces iron ions into the copper-plated layer through an oxidation-reduction method, synchronously realizing the doping of iron ions and the oxidation of the copper coating, generating iron-copper metal hydroxides 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 generation efficiency of reactive oxygen species can be controlled, and the difficult-to-adsorb As(III) can be efficiently oxidized to the easily adsorbed As(V), thereby improving the adsorption capacity and efficiency of the composite material for arsenite ions.

[0015] 4. In the preparation method of the present application, the biochar matrix maintains the natural three-dimensional pore structure of the bamboo biomass, and the surface-modified metal oxides are tightly combined, effectively improving the phenomenon of active nanoparticle aggregation and the utilization rate of adsorption active sites, and promoting the full exposure of active components.

[0016] 5. The preparation method of the present application anchors the rice particles on the surface of the bulk biochar matrix through a chemical reduction combined with an oxidation-reduction doping technique, avoiding the leakage of iron ions and copper ions into the water body during the adsorption process, which causes secondary pollution. At the same time, the biochar has a certain toughness, avoiding the collapse and dissociation of the macroscopic bulk structure during use, and improving the stability of the adsorbent.

[0017] 6. The present application can obtain a carbon-based high-performance bulk As(III) oxidation-adsorption composite material Fe / CuO@BC, which is applied to the adsorption and removal of arsenous acid ion pollutants in water. This adsorption material has excellent oxidation activity, and the proportion of As(III) that can be efficiently oxidized in water reaches 40%. It also has rapid adsorption activity, with an adsorption capacity reaching more than 90% within 1 hour, and the adsorption capacity of the composite material at adsorption equilibrium reaching 150-200 mg / g. The oxidation-adsorption active sites of this composite material have high regeneration performance, reaching more than 95%. After being recycled five times, the adsorption efficiency for arsenous acid ions still remains above 80%. Description of the Drawings

[0018] Figure 1 SEM image of copper-plated biochar prepared for Comparative Example 1; Figure 2 SEM image of the carbon-based bulk As(III) oxidation-adsorption material prepared in Example 1; Figure 3 Optical images of the carbon-based bulk As(III) oxidation-adsorption materials prepared in Examples 1 and 2; Figure 4 X-ray diffraction pattern of the carbon-based bulk As(III) oxidation-adsorption material prepared in Example 1; Figure 5 X-ray photoelectron spectroscopy pattern of the carbon-based bulk As(III) oxidation-adsorption material prepared in Example 1 after being saturated with the adsorption of As(III); Figure 6 Adsorption capacity diagrams of the composite materials prepared in Examples 1, Comparative Examples 1, 2, and 3 for arsenous acid ions; Figure 7 Adsorption isotherm of the carbon-based bulk As(III) oxidation-adsorption material prepared in Example 1 for arsenous acid ions; Figure 8 Adsorption efficiency diagram of the carbon-based bulk As(III) oxidation-adsorption material prepared in Example 1 for arsenous acid ions during five recovery and regeneration cycles. Detailed Embodiments

[0019] The following embodiments in conjunction with the drawings are only used to illustrate the technical solutions recorded in the claims, and are not intended to limit the scope of protection of the claims.

[0020] Example 1 A preparation method of a carbon-based bulk As(III) oxidation-adsorption material, in which bamboo biomass is processed as follows to obtain a bulk composite material. The specific steps are as follows: Step (1), Wash the waste bamboo with deionized water, dry the surface moisture, remove the surface impurities, and cut it into bamboo slices with a thickness of 2.5 mm; Prepare Solution A (c(Sn2+ ) = 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 above 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 taking it out, wash it three times with deionized water to obtain sensitized biomass. Step (2), prepare solution B (c(Ag + ) = 0.1 mol / L): Add 0.125 mL of ammonia water to 25 mL of deionized water. Weigh 0.4244 g of silver nitrate and add it to the above ammonia water solution, stirring until completely dissolved. Immerse the sensitized biomass in step (1) in solution B and let it stand for 15 min. After taking it out, wash it three times with deionized water to obtain activated biomass. Step (3), prepare solution C (c(Cu 2+ ) = 0.06 mol / L): Under a stirring speed of 500 rpm, add 95 mL of deionized water, successively add 1.023 g of copper chloride dihydrate, 4.233 g of potassium sodium tartrate, 0.8 g of sodium hydroxide, 0.372 g of sodium carbonate, and 5 mL of formaldehyde. After complete dissolution, immerse the activated biomass in step (2) in solution C and stir at 500 rpm for 2 h. After taking it out, wash it three times with deionized water to obtain copper-plated biomass. Step (4), prepare solution D: (c(Fe 2+ ) = 0.12 mol / L): Weigh 0.5964 g of ferrous chloride tetrahydrate, dissolve it in 25 mL of deionized water and ultrasonicate for 5 min. Immerse the copper-plated biomass in step (3) in solution D, let it stand for 5 h, then wash it three times with deionized water and freeze-dry for 36 h to obtain biomass modified with iron and copper hydroxides. Step (5), transfer the 8 pieces of biomass modified with iron and copper hydroxides obtained after the treatment in step (4) to a tube furnace. Under the protection of an Ar atmosphere, heat it to 400 °C at a rate of 5 °C / min and keep it at this temperature for 2 h to obtain a bulk carbon-based As(III) oxidation-adsorption material.

[0021] Example 2 A preparation method of a carbon-based bulk As(III) oxidation-adsorption material. After treating bamboo biomass as follows, a bulk composite material is obtained. The specific steps are as follows: Step (1), wash the waste bamboo with deionized water, dry the surface moisture, remove surface impurities, and cut it into bamboo slices with a thickness of 2 mm. Prepare solution A (c(Sn 2+) = 0.1 mol / L): Add 1.2 mL of concentrated hydrochloric acid to 18.8 mL of deionized water. Weigh 0.4513 g of stannous chloride dihydrate and add it to the above hydrochloric acid solution. 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 sensitized biomass; Step (2), prepare solution B (c(Ag + ) = 0.08 mol / L): Add 0.1 mL of ammonia water to 20 mL of deionized water. Weigh 0.2718 g of silver nitrate and add it to the above ammonia water solution. Stir until completely dissolved. Immerse the sensitized biomass in step (1) in solution B and let it stand for 15 min. After taking it out, wash it three times with deionized water to obtain activated biomass; Step (3), prepare solution C (c(Cu 2+ ) = 0.04 mol / L): Under a stirring speed of 300 rpm, add 76 mL of deionized water, successively add 0.5456 g of copper chloride dihydrate, 3.3864 g of potassium sodium tartrate, 0.64 g of sodium hydroxide, 0.2976 g of sodium carbonate, and 4 mL of formaldehyde. After complete dissolution, immerse the activated biomass in step (2) in solution C and stir at 300 rpm for 1 h. After taking it out, wash it three times with deionized water to obtain copper-plated biomass; Step (4), prepare solution D (c(Fe 2+ ) = 0.1 mol / L): Weigh 0.3976 g of ferrous chloride tetrahydrate and dissolve it in 20 mL of deionized water and sonicate for 5 min. Immerse the copper-plated biomass in step (3) in solution D. After standing for 2 h, wash it three times with deionized water and freeze-dry for 24 h to obtain biomass modified with iron and copper hydroxides; Step (5), transfer the 8 pieces of biomass modified with iron and copper hydroxides obtained after step (4) to a tubular furnace. Under the protection of an Ar atmosphere, heat it to 400 °C at a rate of 5 °C / min and hold for 2 h to obtain a bulk carbon-based As(III) oxidation-adsorption material.

[0022] Example 3 A preparation method of a carbon-based bulk As(III) oxidation-adsorption material. After treating bamboo biomass as follows, a bulk composite material is obtained. The specific steps are as follows: Step (1), wash the waste bamboo with deionized water, dry the surface moisture, remove surface impurities, and cut it into bamboo slices with a thickness of 3 mm. Prepare solution A (c(Sn 2+) = 0.15 mol / L): Add 1.8 mL of concentrated hydrochloric acid to 28.2 mL of deionized water. Weigh 1.0153 g of stannous chloride dihydrate and add it to the above 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 taking it out, wash it three times with deionized water to obtain sensitized biomass; Step (2), prepare solution B (c(Ag + ) = 0.12 mol / L): Add 0.15 mL of ammonia water to 30 mL of deionized water. Weigh 0.6115 g of silver nitrate and add it to the above ammonia water solution, stirring until completely dissolved. Immerse the sensitized biomass in step (1) in solution B and let it stand for 15 min. After taking it out, wash it three times with deionized water to obtain activated biomass; Step (3), prepare solution C (c(Cu 2+ ) = 0.1 mol / L): Under a stirring speed of 600 rpm, add 112.8 mL of deionized water, 2.046 g of copper chloride dihydrate, 3.3864 g of sodium potassium tartrate, 0.64 g of sodium hydroxide, 0.2976 g of sodium carbonate, and 7.2 mL of formaldehyde in sequence. After complete dissolution, immerse the activated biomass in step (2) in solution C and stir at 600 rpm for 3 h. After taking it out, wash it three times with deionized water to obtain copper-plated biomass; Step (4), prepare solution D (c(Fe 2+ ) = 0.25 mol / L): Weigh 1.4911 g of ferrous chloride tetrahydrate and dissolve it in 30 mL of deionized water by ultrasonic treatment for 5 min. Immerse the copper-plated biomass in step (3) in solution D, let it stand for 8 h, then wash it three times with deionized water, and freeze-dry it for 48 h to obtain biomass modified with iron copper hydroxide; Step (5), transfer the 8 pieces of biomass modified with iron copper hydroxide obtained after the treatment in step (4) to a tube furnace. Under the protection of an Ar atmosphere, heat it to 400 °C at a rate of 5 °C / min and keep it at this temperature for 2 h to obtain a bulk carbon-based bulk As(III) oxidation-adsorption material.

[0023] Example 4 A preparation method of a carbon-based bulk As(III) oxidation-adsorption material, the bamboo biomass is processed as follows to obtain a bulk composite material, and the specific steps are as follows: Step (1), wash the waste bamboo with deionized water, dry the surface moisture, remove the surface impurities, and cut it into bamboo slices with a thickness of 2.5 mm; prepare solution A (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 above 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 taking it out, wash it three times with deionized water to obtain sensitized biomass; Step (2), prepare solution B (c(Ag + ) = 0.1 mol / L): Add 0.125 mL of ammonia water to 25 mL of deionized water. Weigh 0.4244 g of silver nitrate and add it to the above ammonia water solution, stirring until completely dissolved. Immerse the sensitized biomass in step (1) in solution B and let it stand for 15 min. After taking it out, wash it three times with deionized water to obtain activated biomass; Step (3), prepare solution C (c(Cu 2+ ) = 0.06 mol / L): Under a stirring speed of 500 rpm, add 95 mL of deionized water, successively add 1.023 g of copper chloride dihydrate, 4.233 g of sodium potassium tartrate, 0.8 g of sodium hydroxide, 0.372 g of sodium carbonate, and 5 mL of formaldehyde. After complete dissolution, immerse the activated biomass in step (2) in solution C and stir at 500 rpm for 2 h. After taking it out, wash it three times with deionized water to obtain copper-plated biomass; Step (4), prepare solution D: (c(Fe 2+ ) = 0.12 mol / L): Weigh 0.5964 g of ferrous chloride tetrahydrate, dissolve it in 25 mL of deionized water and ultrasonicate for 5 min. Immerse the copper-plated biomass in step (3) in solution D, let it stand for 5 h, then wash it three times with deionized water and freeze-dry for 36 h to obtain biomass modified with iron and copper hydroxides; Step (5), transfer the 8 pieces of biomass modified with iron and copper hydroxides obtained after step (4) to a tube furnace. Under the protection of an Ar atmosphere, heat it to 300 °C at a rate of 5 °C / min and hold for 1 h to obtain a bulk carbon-based As(III) oxidation-adsorption material.

[0024] Example 5 A preparation method of a carbon-based bulk As(III) oxidation-adsorption material, the bamboo biomass is processed as follows to obtain a bulk composite material, and the specific steps are as follows: Step (1), wash the waste bamboo with deionized water, dry the surface moisture, remove the surface impurities, and cut it into bamboo slices with a thickness of 2.5 mm; prepare solution A (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 above 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 taking it out, wash it three times with deionized water to obtain sensitized biomass; Step (2), prepare Solution B (c(Ag + ) = 0.1 mol / L): Add 0.125 mL of ammonia water to 25 mL of deionized water. Weigh 0.4244 g of silver nitrate and add it to the above ammonia water solution, stirring until completely dissolved. Immerse the sensitized biomass in Step (1) in Solution B and let it stand for 15 min. After taking it out, wash it three times with deionized water to obtain activated biomass; Step (3), prepare Solution C (c(Cu 2+ ) = 0.06 mol / L): Under a stirring speed of 500 rpm, add 95 mL of deionized water, successively add 1.023 g of copper chloride dihydrate, 4.233 g of sodium potassium tartrate, 0.8 g of sodium hydroxide, 0.372 g of sodium carbonate, and 5 mL of formaldehyde. After complete dissolution, immerse the activated biomass in Step (2) in Solution C and stir at 500 rpm for 2 h. After taking it out, wash it three times with deionized water to obtain copper-plated biomass; Step (4), prepare Solution D: (c(Fe 2+ ) = 0.12 mol / L): Weigh 0.5964 g of ferrous chloride tetrahydrate, dissolve it in 25 mL of deionized water and sonicate for 5 min. Immerse the copper-plated biomass in Step (3) in Solution D, let it stand for 5 h, then wash it three times with deionized water and freeze-dry for 36 h to obtain biomass modified with iron and copper hydroxides; Step (5), transfer the 8 pieces of biomass modified with iron and copper hydroxides obtained after Step (4) to a tube furnace. Under the protection of an Ar atmosphere, heat it to 500 °C at a rate of 5 °C / min and hold for 4 h to obtain a bulk carbon-based As(III) oxidation-adsorption material.

[0025] The inorganic arsenic adsorption performance test of the obtained carbon-based bulk As(III) oxidation-adsorption material is carried out through the following steps: (1) Place the prepared composite oxidation-adsorption material in a blue-capped bottle and add a certain concentration of arsenite ion solution, and shake it at a constant temperature; (2) Take samples 10 - 15 times at intervals of 0 - 360 min, each time taking 1 - 3 mL. Use an atomic fluorescence spectrometer to test the concentration of inorganic arsenic in the water sample, and fit it with a second-order kinetic adsorption model to evaluate the adsorption kinetics; (3) In the initial concentration range of arsenite ions from 1 to 50 mg / L, after shaking the oxidation-adsorption column for 360 min, 1 to 3 mL of the sample is taken, and the concentration of inorganic arsenic in the water sample is measured using an atomic fluorescence spectrometer. The Langmuir isothermal model is used for fitting to evaluate its isothermal adsorption curve and calculate the adsorption capacity.

[0026] (4) Collect the carbon-based bulk As(III) oxidation-adsorption material saturated with adsorption, and then perform elution in a blue-capped bottle with a regeneration eluent (0.5 mol / L NaOH solution, 100 mL) for 5 h. After taking it out, rinse it with deionized water and freeze-dry it for 12 h. Then transfer it to a tubular furnace, heat it to 400 °C at a rate of 5 °C / min under Ar atmosphere protection, and keep it at this temperature for 2 h to obtain the regenerated bulk carbon-based As(III) oxidation-adsorption material, which is then used for the next cycle.

[0027] Comparative Example 1 The comparative composite oxidation-adsorption material is prepared through the following steps: Step (1): Wash the waste bamboo with deionized water, dry the surface moisture, remove surface impurities, and cut it into bamboo slices with a thickness of 2.5 mm; prepare Solution A (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 above 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; Step (2): Prepare Solution B (c(Ag + ) = 0.1 mol / L): Add 0.125 mL of ammonia water to 25 mL of deionized water, weigh 0.4244 g of silver nitrate and add it to the above ammonia water solution, and stir until completely dissolved; immerse the sensitized biomass in Step (1) in Solution B and let it stand for 15 min. After taking it out, wash it three times with deionized water to obtain the activated biomass; Step (3): Prepare Solution C (c(Cu 2+ ) = 0.06 mol / L): While stirring 95 mL of deionized water at a speed of 500 rpm, sequentially add 1.023 g of copper chloride dihydrate, 4.233 g of potassium sodium tartrate, 0.8 g of sodium hydroxide, 0.372 g of sodium carbonate, and 5 mL of formaldehyde. After complete dissolution, immerse the activated biomass in Step (2) in Solution C and stir at 500 rpm for 2 h. After taking it out, wash it three times with deionized water to obtain the copper-plated biomass; Step (4): The 8 pieces of copper-plated biomass obtained after being processed in step (3) are transferred into a tube furnace, heated to 400 °C at a rate of 5 °C / min under Ar atmosphere protection, and held for 2 h to obtain a bulk copper-modified biochar composite material.

[0028] Comparative Example 2 The comparative composite oxidation-adsorption material is prepared through the following steps: Step (1): The waste bamboo is washed with deionized water, the surface moisture is wiped dry, the surface impurities are removed, cut into bamboo slices with a thickness of 2.5 mm, and 8 pieces of bamboo biomass are washed three times with deionized water and reserved. Step (2): Prepare solution D: (c(Fe 2+ ) = 0.12 mol / L): Weigh 0.5964 g of ferrous chloride tetrahydrate, dissolve it in 25 mL of deionized water and ultrasonicate for 5 min. Immerse the biomass washed in step (1) into solution D, let it stand for 5 h, then wash it three times with deionized water and freeze-dry for 36 h to obtain the biomass modified with iron hydroxide. Step (3): The 8 pieces of biomass modified with iron hydroxide obtained after being processed in step (2) are transferred into a tube furnace, heated to 400 °C at a rate of 5 °C / min under Ar atmosphere protection, and held for 2 h to obtain a bulk iron oxide-modified biochar composite material.

[0029] Comparative Example 3 The comparative composite oxidation-adsorption material is prepared through the following steps: Step (1): The waste bamboo is washed with deionized water, the surface moisture is wiped dry, the surface impurities are removed, cut into bamboo slices with a thickness of 2.5 mm, and 8 pieces of bamboo biomass are washed three times with deionized water and freeze-dried for 24 h to obtain dry biomass. Step (2): The 8 pieces of biomass obtained after being processed in step (1) are transferred into a tube furnace, heated to 400 °C at a rate of 5 °C / min under Ar atmosphere protection, and held for 2 h to obtain a bulk biochar material.

[0030] The microscopic structure diagram of Comparative Example 1 is as shown in the appendix Figure 1 As shown. It can be seen from the figure that the copper single-element coating layer grows closely on the surface of the biomass. At the same time, the biochar maintains the natural three-dimensional pore structure of bamboo biomass, which is beneficial to the full contact with pollutant ions in water. Appendix Figure 2 This is the microscopic structure diagram of Example 1. It can be seen from the figure that after doping with iron oxide, the copper particles on the surface of the biochar are nano-sized, with a particle size of about 50 nm, fully exposing the active sites and oxidizing-adsorbing arsenous acid ions in water. Appendix Figure 3Optical photographs of Examples 1 and 2. As can be seen from the figures, the composite material has a macroscopic bulk structure. The results show that a composite material with a macroscopic bulk and microscopically nanoparticle-modified porous three-dimensional carbon structure can be prepared by chemical reduction copper plating and doping with pyrolyzed iron oxide.

[0031] Attached Figure 4 (The abscissa 2θ is the diffraction angle (degree), and the ordinate Intensity is the intensity (a.u.)) is the X-ray diffraction pattern of Example 1. There is a broad diffraction peak and two sets of strong diffraction peaks in the pattern. The broad diffraction peak is amorphous carbon in the biochar matrix; the two sets of strong diffraction peaks correspond to iron oxide and copper oxide respectively. The results of crystal structure characterization indicate that a biochar composite material modified with iron-doped copper oxide has been successfully prepared.

[0032] Attached Figure 5 (The abscissa is the electron binding energy (eV), and the ordinate is the intensity (a.u.)) is the X-ray photoelectron spectroscopy of the As 3d orbital after Example 1 is saturated with arsenite ion adsorption. This spectrum can be divided into two fitting peaks, corresponding to pentavalent arsenate ion (accounting for 48.32%) and trivalent arsenite ion (accounting for 51.68%) respectively, indicating that about 50% of As(III) is oxidized to As(V) before adsorption, indicating that the composite material has excellent oxidation and adsorption properties at the same time.

[0033] Attached Figure 6 (The abscissa is the contact time (min), and the ordinate is the residual concentration of As(III) (mg / g)) are the results of the performance test for the adsorption 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 a poor removal effect. Example 1 quickly removes about 90% of the arsenite ions in 1 minute, and the equilibrium concentration is lower than 3 mg / L. It 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 is used for the adsorption results. Example 2 and Comparative Examples 1 and 2 all conform to the pseudo-second-order kinetic model, indicating that their adsorption processes are all chemical adsorption.

[0034] Attached Figure 7 (The abscissa is the initial concentration of As(III) (mg / L), and the ordinate is the adsorption capacity of As(III) (mg / g)) reveals the performance of the bulk Fe / CuO@BC oxidation-adsorption composite material for removing arsenite ions. The R values of Example 1 fitted by the Langmuir model 2 are all greater than 0.9, further verifying its chemical adsorption characteristics, and the maximum adsorption amount obtained from the fitting results is 159.3 mg / g respectively.

[0035] Attached Figure 8(The abscissa is the cyclic regeneration period, and the ordinate is the As(III) adsorption and removal efficiency) reveals the stability and recyclability of the carbon-based bulk As(III) oxidation-adsorption material prepared in Example 1 for the removal of As(III). After five adsorption and regeneration cycles, the adsorption performance still remains above 80%, indicating its good cyclic stability.

[0036] The results of the examples show that the present application uses a chemical reduction method and pyrolyzes 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, being easy to recycle, having strong cyclic stability, and having excellent properties such as no secondary water pollution.

[0037] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a carbon-based bulk As(III) oxidation-adsorption material, characterized in that, The biomass is processed as follows to obtain a bulk As(III) oxidation-adsorption material. The specific steps are as follows: Step 1: Take bamboo stems with a thickness of 2 - 3 mm and completely immerse them in a solution containing 0.1 - 0.15 mol / L stannous chloride and 60 mL / L hydrochloric acid solution, and let them stand for 0.5 h. After taking them out, wash them with ultrapure water to obtain a sensitized biomass matrix; Step 2: Immerse the sensitized biomass matrix in a mixed solution containing 5 mL / L ammonia water and 0.08 - 0.12 mol / L silver nitrate, and let it stand for 15 min. After taking it out, wash it with ultrapure water to obtain an activated biomass matrix; Step 3: Transfer the activated biomass matrix to a mixed solution with a copper ion concentration of 0.04 - 0.1 mol / L and a reducing agent formaldehyde concentration of 40 - 60 mL / L, and stir at a speed of 300 - 600 rpm at room temperature for 1 - 3 h. After taking it out, wash it with ultrapure water to obtain a copper-plated biomass; Step 4: Immerse the copper-plated biomass in a 0.1 - 0.25 mol / L ferrous chloride solution, let it stand for 2 - 8 h. After taking it out, wash it with ultrapure water and freeze-dry it for 24 - 48 h to obtain a biomass modified with iron-doped copper hydroxide; Step 5: Transfer the dried biomass modified with iron-doped copper hydroxide to a tube furnace and pyrolyze it at 300 - 500 °C for 1 - 4 h under the protection of an inert gas to obtain a high-performance carbon-based bulk As(III) oxidation-adsorption material.

2. The preparation method of the carbon-based bulk As(III) oxidation-adsorption material according to claim 1, wherein, In the above Step 1, the solid-liquid ratio of the sensitization solution to the biomass is 1:

10.

3. The preparation method of the carbon-based bulk As(III) oxidation-adsorption material according to claim 1, characterized in that, In the above Step 2, the solid-liquid ratio of the activation solution to the biomass is 1:

10.

4. The preparation method of the carbon-based bulk As(III) oxidation-adsorption material according to claim 1, characterized in that, In the above Step 3, the solid-liquid ratio of the copper-plating solution to the biomass is 1:

40.

5. The preparation method of the carbon-based bulk As(III) oxidation-adsorption material according to claim 1, wherein, In the above Step 4, the solid-liquid ratio of the ferrous chloride solution to the biomass is 1:

10.

6. The preparation method of the carbon-based bulk As(III) oxidation-adsorption material according to claim 1, wherein In the above Step 5, the heating rate during the pyrolysis process is 5 °C / min.

Images