Preparation method of arsenic removal adsorbent, arsenic removal adsorbent prepared by method and application of arsenic removal adsorbent

Abstract

The invention provides a preparation method of an arsenic removal adsorbent, which comprises the following steps: preparing Bi (OH) 3-BiOOH blended powder, mixing the Bi (OH) 3-BiOOH blended powder with polyacrylonitrile and N, N-dimethylacetamide, dripping into small balls through a ball dripping device, drying, reacting with a mixed solution of CuCl2 and CeCl3, drying, reacting with a saturated tannic acid solution, and drying to obtain the arsenic removal adsorbent. The invention also provides application of the arsenic removal adsorbent in water treatment, especially in adsorption of trivalent arsenic and pentavalent arsenic in wastewater. The arsenic removal adsorbent disclosed by the invention has the advantages of high adsorption rate, high selectivity, high adsorption capacity and high cycle stability on pentavalent arsenic-containing ions and trivalent arsenic-containing ions in a water body, and is simple in synthesis process and beneficial to industrial production, application and popularization.

Description

Technical Field

[0001] This invention relates to arsenic removal adsorbents, and particularly to a method for preparing a high-performance arsenic removal adsorbent, as well as the application of the arsenic removal adsorbent obtained by the method in the field of water treatment. Background Technology

[0002] According to my country's "Standards for Drinking Water Quality" (GB5749-2006), the arsenic content in drinking water should not exceed 0.01 mg / L. Therefore, how to achieve the standard treatment of wastewater with excessive arsenic is one of the current challenges faced by the water treatment industry.

[0003] For water bodies with low to medium concentrations of arsenic exceeding the standard, adsorption is the most economical and effective treatment method. However, existing arsenic adsorbents typically suffer from drawbacks such as low adsorption capacity, slow adsorption rate, poor selectivity, and poor cycle stability. For example, Chinese invention patent application CN 117323958A proposes a method for preparing an arsenic adsorbent. Because this preparation method involves a hydrothermal reaction, requires high-pressure conditions, places very high demands on the reaction equipment, and involves complex synthesis steps, the lanthanide metals used as raw materials are expensive, thus hindering industrialization.

[0004] CN117599748A proposes using heavy metal passivation and stabilization materials as arsenic adsorbents, including iron-carbon micro / nanofibers and CeO2 nanoparticles loaded on the iron-carbon micro / nanofibers. However, this arsenic adsorbent lacks regeneration capability and becomes ineffective after adsorption saturation.

[0005] CN 116139828A discloses a biosorbent that uses corn husks as a substrate, aluminum chloride as a catalyst, and tannic acid as a modifier to achieve hydroxylation of corn husks through grafting. However, the adsorbent has a low adsorption capacity for trivalent arsenic, only 35.55 mg / g.

[0006] CN 118437298A discloses a method for removing arsenic using a carbon-based Fe / La-metal-organic framework composite adsorbent. This method utilizes La doping to form a bimetallic MOF material, which, when combined with activated carbon powder, achieves a larger specific surface area, enhancing its adsorption capacity and application range. It can achieve an arsenic removal rate of 96.17% for wastewater with an arsenic content of 6.82 mg / L. However, the synthesis process of this arsenic adsorbent is complex and costly, making large-scale application difficult.

[0007] CN 118634787A discloses a method for preparing an MS-activated silica gel@FeOOH composite arsenic removal material, which exhibits excellent adsorption capacity for arsenic, with an adsorption capacity of 62.22–181.96 mg / g for trivalent arsenic and 115.93–153.18 mg / g for pentavalent arsenic. However, the prepared material is in powder form, which may lead to difficulties in recovery and powder loss during use.

[0008] Therefore, there is an urgent need in this field for an arsenic removal adsorbent with strong adsorption performance, stable product, recyclability, and mild preparation conditions. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of existing technologies and provide an arsenic removal adsorbent with high adsorption capacity, fast adsorption rate, and good cycle stability by improving the preparation process, so as to meet the needs of water treatment.

[0010] Based on this, the present invention provides a method for preparing an arsenic removal adsorbent, the method comprising the following steps:

[0011] (1) Preparation of Bi(OH)3-BiOOH blend powder

[0012] Weigh solid BiOOH and Bi(OH)3 and mix them thoroughly until a blended powder is obtained in which Bi(OH)3 accounts for 61.7%~76.3% by mass percentage and the balance is BiOOH (i.e., BiOOH accounts for 23.7%-38.3% accordingly).

[0013] (2) Preparation of Bi(OH)3-BiOOH / PAN microspheres

[0014] Weigh out Bi(OH)3-BiOOH blended powder, polyacrylonitrile (PAN), and N,N-dimethylacetamide (DMAC). The total powder consists of Bi(OH)3-BiOOH blended powder and polyacrylonitrile, with polyacrylonitrile accounting for 5%-10% and N,N-dimethylacetamide accounting for 100%-200% by mass percentage. Heat and stir the Bi(OH)3-BiOOH blended powder, polyacrylonitrile, and N,N-dimethylacetamide until they are uniformly mixed to obtain a liquid. Transfer the liquid to a dropping ball device for dropping balls. The resulting balls fall into deionized water for phase inversion. Dry the wet balls to obtain Bi(OH)3-BiOOH / PAN balls with a particle size of 0.5-1 mm.

[0015] (3) Preparation of CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN

[0016] Prepare a mixed solution containing CuCl2 and CeCl3, wherein the molar concentrations of CuCl2 and CeCl3 are the same and are both 1-2 mol / L;

[0017] The Bi(OH)3-BiOOH / PAN beads were thoroughly immersed in a mixed solution of CuCl2 and CeCl3, allowing Cu to... 2+ and Ce 3+ The solution is fully diffused into the pores of Bi(OH)3-BiOOH / PAN microspheres. After solid-liquid separation, the wet microspheres are dried to obtain dry CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN microspheres.

[0018] (4) Preparation of C 76 O 46 H 52-5x Cu(Ⅱ) x Ce(Ⅲ) x / Bi(OH)3-BiOOH / PAN

[0019] Preparation of saturated tannic acid (C 76 O 46 H 52 The solution was adjusted to C using sodium hydroxide solution. 76 O 46 H 52 The pH of the solution is 6.5-7.5;

[0020] Excess solution was sprayed onto dry CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN microspheres until the microspheres were fully wetted, resulting in wet CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN microspheres. 76 O 46 H 52-5x Cu(Ⅱ) x Ce(Ⅲ) x / Bi(OH)3-BiOOH / PAN (4≤x≤8) small spheres, the reaction process is C 76 O 46 H 52 With Cu 2+ and Ce 3+ The reaction forms C 76 O 46 H 52-5x Cu(Ⅱ) x Ce(Ⅲ) x , wet C 76 O 46 H 52-5x Cu(Ⅱ) x Ce(Ⅲ) x The / Bi(OH)3-BiOOH / PAN microspheres were dried to obtain a dried arsenic removal adsorbent.

[0021] In this invention, the thorough soaking in step (3) is achieved by immersing 1-2 volume parts of Bi(OH)3-BiOOH / PAN microspheres in a mixed solution of 1-2 volume parts of CuCl2 and CeCl3 for 3-6 hours. This step is to allow the Cu... 2 + and Ce 3+ The solution diffuses fully into the pores of Bi(OH)3-BiOOH / PAN microspheres, so the volume ratio of the solid phase to the liquid phase usually does not need to be strictly defined. The solution of the present invention can also be achieved by using an excess of solution or soaking for a longer time.

[0022] The use of excess spray solution in step (4) is to ensure that the Cu in the pellets is within the required concentration. 2+ and Ce 3+ For a complete reaction, a mass ratio of spray solution to dried pellets of 1:1 to 2:1 is usually sufficient to achieve this, allowing C to react completely. 76 O 46 H 52 With Cu 2+ and Ce 3+ The reaction forms C 76 O 46 H 52-5x Cu(Ⅱ) x Ce(Ⅲ) x .

[0023] Optionally, the concentration of the sodium hydroxide solution used in step (4) is 2-4 mol / L.

[0024] Preferably, the drying in steps (3) and (4) is carried out in an oven at 50-70°C. Those skilled in the art can also adjust the required temperature and time for drying as appropriate.

[0025] In this invention, powdered (dry) Bi(OH)3 and BiOOH are commercially available. Typically, the particle size of the commercially available products is 0.2-10 μm, and such a particle size range can be used to implement this invention.

[0026] Those skilled in the art can also prepare powdered (dry) Bi(OH)3 and BiOOH respectively through the following steps (1.1)-(1.2):

[0027] (1.1) Preparation of Bi(OH)3

[0028] 100-150 mol of powdered BiCl3 was added to an enamel-lined reactor, followed by 300-400 L of 1.5-2 mol / L NaOH solution. The mixture was stirred thoroughly until a slurry containing white Bi(OH)3 precipitate was obtained. The slurry was filtered to obtain a white Bi(OH)3 solid filter cake. The filter cake was then thoroughly dried to obtain a dry white Bi(OH)3 block solid.

[0029] In this step, the reaction equation is: BiCl3 + 3NaOH = Bi(OH)3 + 3NaCl

[0030] In step (1.1), preferably, the NaOH solution is added at a rate of 100-200 L / h, the temperature of the NaOH solution is 0-5℃, the filtration method is plate and frame filtration, and the thorough drying is achieved by placing the filter cake in a negative pressure dryer and drying it for 5-10 hours at a temperature of 50-80℃.

[0031] (1.2) Synthesis of Bi(OH)3-BiOOH

[0032] 25%-40% of the dry white Bi(OH)3 blocky solid was taken by mass percentage and dried twice to obtain BiOOH blocky solid. The BiOOH blocky solid was then blended and pulverized with the remaining dry white Bi(OH)3 blocky solid to obtain Bi(OH)3-BiOOH blended powder, wherein Bi(OH)3 accounted for 76.3%-61.7% and BiOOH accounted for 23.7%-38.3% by mass percentage in the blended powder.

[0033] In this step, the reaction equation is: Bi(OH)3 = BiOOH + H2O

[0034] In step (1.2), the particle size of the blend is 0.2-10μm, the secondary drying is achieved by drying at 90-110℃ for 5-10h, the blending and pulverizing is achieved by placing the material in an impact mill, the heating and stirring is achieved by putting the material into a stirring vessel and stirring at 70-95℃ for 3-8h, and the drying is carried out in an oven at 50-70℃.

[0035] The above operating parameters are all conventional choices in this field, and those skilled in the art can also implement specific parameters under appropriate conditions.

[0036] The present invention also provides the application of the arsenic removal adsorbent prepared by the above preparation method in water treatment.

[0037] In particular, the arsenic adsorbent of the present invention can be used to adsorb trivalent and pentavalent arsenic in wastewater.

[0038] This invention utilizes the large number of CN groups contained in PAN. Since the CN groups have lone pairs of electrons and the Bi atoms on Bi(OH)3-BiOOH have empty electron orbitals, there is a strong electrostatic interaction between the Bi atoms and the CN groups, which can make the Bi(OH)3-BiOOH powder bond more firmly to the PAN skeleton. Therefore, PAN as a binder can effectively reduce the powder shedding phenomenon of Bi(OH)3-BiOOH / PAN microspheres.

[0039] In addition, in the preparation of C 76 O 46 H 52-5x Cu(Ⅱ) x Ce(Ⅲ) x During the process of forming the / Bi(OH)3-BiOOH / PAN (4≤x≤8) spheres, adjusting the pH of the saturated tannic acid solution to 6.5-7.5 with sodium hydroxide solution ensures the reaction system remains neutral and prevents acidic C from forming. 76 O 46 H 52 The solution dissolves Bi(OH)3-BiOOH, destroying the core components of the solid-phase raw material. Furthermore, spraying the dried CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN microspheres with tannic acid solution, instead of immersing them in the solution, prevents the effective components of CuCl2-CeCl3 on the microspheres from dissolving into the solution during immersion. This avoids the reduction or loss of effective components on the microspheres, ensuring the final yield of C... 76 O 46 H 52-5x Cu(Ⅱ) x Ce(Ⅲ) x / Bi(OH)3-BiOOH / PAN microspheres.

[0040] This invention uses a CuCl2-CeCl3 mixed solution system as a precipitant for tannic acid, instead of using a single CuCl2 solution or a single CeCl3 solution, because CuCl2... 2+ and Ce 3+ Together with tannic acid (C 76 O 46 H 52 Complexation can improve C 76 O 46 H 52-5x Cu(Ⅱ) x Ce(Ⅲ) x The stability of the precipitate and the reduction of C 76 O 46 H52-5x Cu(Ⅱ) x Ce(Ⅲ) x The solubility of the precipitate in water improves the physicochemical stability of the material, thereby increasing the saturated adsorption capacity and overall adsorption performance of the arsenic adsorbent.

[0041] Therefore, the C of the present invention 76 O 46 H 52-5x Cu(Ⅱ) x Ce(Ⅲ) x The / Bi(OH)3-BiOOH / PAN (4≤x≤8) spherical arsenic removal adsorbent contains a large number of selective adsorption sites on the loaded active ingredient. Experiments have verified that this material effectively removes pentavalent arsenic ions (H2AsO4) from water. - ,HAsO4 2- ) and trivalent arsenic-containing ions (H2AsO3) - This material exhibits advantages such as rapid adsorption rate, high selectivity, high adsorption capacity, and high cycle stability. Furthermore, its synthesis process does not require high temperature and high pressure, making the synthesis steps simple and easy to operate, which is beneficial for the industrial production and application of this arsenic removal material.

[0042] On the other hand, the preparation method of the present invention does not require the use of high temperature and high pressure synthesis methods, but adopts low temperature operation at 50-80℃. The synthesis steps are simple and easy to operate and have low energy consumption, which is conducive to industrial production and application promotion. Attached Figure Description

[0043] Figure 1 This is a flowchart of the preparation method of the present invention;

[0044] Figure 2 C obtained in Example 1 76 O 46 H 12 Photographs and scanning electron microscope images of Cu(Ⅱ)8Ce(Ⅲ)8 / Bi(OH)3-BiOOH / PAN microspheres;

[0045] Figure 3 C obtained in Example 2 76 O 46 H 32 Photographs and scanning electron microscope images of Cu(Ⅱ)4Ce(Ⅲ)4 / Bi(OH)3-BiOOH / PAN microspheres;

[0046] Figure 4 C obtained in Example 3 76 O 46 H 22 Photographs and scanning electron microscope images of Cu(Ⅱ)6Ce(Ⅲ)6 / Bi(OH)3-BiOOH / PAN microspheres. Detailed Implementation

[0047] The following examples are used to explain the technical solutions of the present invention in a non-limiting manner.

[0048] In this invention, unless otherwise specified, “:” used to explain proportions means mass ratio and “%” means mass percentage.

[0049] Example 1

[0050] 1. Synthesis of Bi(OH)3

[0051] 100 mol of powdered BiCl3 was added to an enamel-lined autoclave. While stirring, 300 L of a 1.5 mol / L NaOH solution at 0℃ was added at a rate of 100 L / h. After the NaOH solution was added, a white Bi(OH)3 precipitate was formed. Stirring continued for 2 h. The white slurry was then subjected to plate and frame filter press filtration to obtain a white Bi(OH)3 solid filter cake. The white Bi(OH)3 solid filter cake was placed in a negative pressure dryer and dried at 50℃ for 5 h to obtain dry white Bi(OH)3 blocky solid for later use.

[0052] 2. Synthesis of Bi(OH)3-BiOOH

[0053] Take 25% of the total mass of the above-mentioned dry white Bi(OH)3 blocky solid and dry it in a drying oven at 90℃ for 5 hours to obtain BiOOH blocky solid. The BiOOH blocky solid obtained after the heating reaction is then mixed and pulverized with the remaining dry white Bi(OH)3 blocky solid in an impact mill to obtain a uniformly mixed Bi(OH)3-BiOOH blend powder. The particle size of the powder was measured to be 0.2-10 μm, and sampling confirmed that Bi(OH)3 accounted for 76.3% and BiOOH accounted for 23.7%.

[0054] 3. Synthesis of Bi(OH)3-BiOOH / PAN microspheres

[0055] Bi(OH)3-BiOOH blend powder, polyacrylonitrile (PAN), and N,N-dimethylacetamide (DMAC) were mixed in a specific mass ratio. The blend powder and polyacrylonitrile were defined as the total powder, the binder PAN accounted for 5% of the total powder, and the solvent DMAC accounted for 100% of the total powder. All the blend powder, binder PAN, and solvent DMAC were added to a stirred tank and heated to 70°C while stirring for 3 hours. The solution was then transferred to a dropping pelleting device for pelleting. The pellets fell into deionized water for phase inversion. The wet pellets were then transferred to a 50°C oven for drying to obtain Bi(OH)3-BiOOH / PAN pellets with a particle size of 0.5-1 mm.

[0056] 4. Synthesis of CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN

[0057] Prepare a mixed solution of copper chloride and cerium chloride, wherein the molar concentrations of CuCl2 and CeCl3 are the same, both expressed as 1 mol / L. Immerse 100 L of dried Bi(OH)3-BiOOH / PAN microspheres in 100 L of the mixed solution for 3 hours to ensure the CuCl2 concentration in the solution is within the acceptable range. 2+ and Ce 3+ The mixture is fully diffused into the pores of Bi(OH)3-BiOOH / PAN microspheres. The mixture is drained, and the resulting wet microspheres are transferred to an oven at 50°C to dry, thus obtaining dry CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN microspheres.

[0058] 5. C 76 O 46 H 52-5x Cu(Ⅱ) x Ce(Ⅲ) x Synthesis of / Bi(OH)3-BiOOH / PAN

[0059] Preparation of saturated tannic acid (C 76 O 46 H 52 The solution was adjusted to C using a 2 mol / L sodium hydroxide solution. 76 O 46 H 52 The solution with a pH of 6.5 was used as the spray solution. An equal mass of the spray solution to the microspheres was sprayed onto the dry CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN microspheres, allowing C... 76 O 46 H 52 The solution gradually penetrates into the CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN microspheres. Once the CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN microspheres are fully wetted, spraying is stopped, resulting in wet microspheres. The wet microspheres are then dried in a 50℃ oven to obtain dry microspheres.

[0060] The resulting dried spherical material C 76 O 46 H 52-5x Cu(Ⅱ) x Ce(Ⅲ) xThe method for determining and calculating the x-value in / Bi(OH)3-BiOOH / PAN (this method was used in all subsequent examples): Since the amounts of CuCl2 and CeCl3 on the dried CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN microspheres are the same, the method using C... 76 O 46 H 52 When the solution is sprayed onto dry CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN microspheres, since the amount of CuCl2 and CeCl3 is small, while C... 76 O 46 H 52 The solution was in excess, therefore all CuCl2 and CeCl3 reacted with C. 76 O 46 H 52 The reaction yields C 76 O 46 H 52-5x Cu(Ⅱ) x Ce(Ⅲ) x Cu 2+ and Ce 3+ The amounts of substances are the same.

[0061] Accurately measure the mass of the dried CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN microspheres during the above preparation process and record it as m1. The dried CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN microspheres and C 76 O 46 H 52 After the solution has completely reacted, the resulting dry, spherical material C 76 O 46 H 52-5x Cu(Ⅱ) x Ce(Ⅲ) x Let the mass of / Bi(OH)3-BiOOH / PAN be denoted as m2. It can be seen that the mass difference between m2 and m1 is C. 76 O 46 H 52-5x Cu(Ⅱ) x Ce(Ⅲ) x The mass difference between CuCl2 and CeCl3 is expressed as m2-m1. Calculations using molecular formula relationships yield m2-m1 = [76×12+46×16+(52-5x)×1+63.5x+140x]-[(63.5+35.5×2)+(140+35.5×3)]x. Therefore, the value of x can be calculated, confirming that the chemical formula of the substance obtained in this embodiment is C. 76 O 46 H 12Cu(II)8Ce(III)8 / Bi(OH)3-BiOOH / PAN.

[0062] Observed through an electron microscope, such as Figure 2 As shown, the obtained C 76 O 46 H 12 The Cu(II)8Ce(III)8 / Bi(OH)3-BiOOH / PAN microspheres have a very uniform particle size of approximately 0.5-1 mm. The powder in the raw material is encapsulated by the PAN resin, preventing the arsenic adsorbent powder from detaching. Electron microscopy reveals that the PAN resin forms a rich porous structure. This extensive network of pores facilitates the adsorption and elution of arsenic ions, improving ion exchange efficiency and giving the arsenic adsorbent a high adsorption rate and capacity.

[0063] Prepare arsenic-containing wastewater with a total arsenic concentration of 10 mg / L, including 5 mg / L of trivalent arsenic and 5 mg / L of pentavalent arsenic.

[0064] The obtained spherical material was placed in an adsorption column. Arsenic-containing wastewater was introduced into the adsorption column using a bottom-in, top-out method, with an influent flow rate of 30-50 BV / h. Saturation was considered achieved when the arsenic concentration in the adsorption product water exceeded 0.01 mg / L, at which point the influent flow was stopped. The adsorption column was then regenerated using a 0.2-0.5 mol / L NaOH solution. A cyclic regeneration method was employed, with a total regenerant volume of 3 BV, a regeneration flow rate of 1-3 BV / h, and a regeneration time of 0.5-1 h. After regeneration, the next cycle was initiated. Three replicates were performed, and the average value was taken. Commercially available LSC-As-400 arsenic removal resin for water treatment was used as a control.

[0065] The saturated adsorption capacity of small spherical materials is calculated as follows: Q = (c 进水 - c 产水 )×V 产水 ÷V 吸附剂 ; where c 进水 and c 产水 The concentrations of arsenic in the influent and product water of the adsorption column are shown in g / L, respectively; V 产水 V represents the volume of adsorbed water produced by the adsorption column, in L; 吸附剂 ν is the column volume of the adsorbent, in L; Q is the volumetric adsorption capacity, in g / L.

[0066] Table 1 shows the C obtained in Example 1. 76 O 46 H 12 A comparison of the adsorption capacity, adsorption rate, and cycling stability of the Cu(Ⅱ)8Ce(Ⅲ)8 / Bi(OH)3-BiOOH / PAN microsphere product and the reference standard (LSC-As-400). Experiments confirmed that C...76 O 46 H 12 The Cu(II)8Ce(III)8 / Bi(OH)3-BiOOH / PAN microsphere product exhibits a saturated adsorption capacity of 9.5 g / L for arsenic ions, significantly higher than the 2.1 g / L of existing arsenic adsorbents, demonstrating the superior performance of the present invention. 76 O 46 H 12 Cu(Ⅱ)8Ce(Ⅲ)8 / Bi(OH)3-BiOOH / PAN microspheres have the advantage of high adsorption capacity and can be used to adsorb trivalent and pentavalent arsenic in water.

[0067] Furthermore, comparing the arsenic concentration in the treated water at an influent flow rate of 20 BV / h, it can be seen that the product of this invention produces a treated water concentration of 0.005 mg / L for arsenic-containing wastewater with an influent arsenic concentration of 10 mg / L, which meets the requirement of 0.01 mg / L for arsenic concentration in China's "Standards for Drinking Water Quality" (GB5749-2022). In contrast, the treated water concentration of the reference standard is 1.2 mg / L, which does not meet the national standard requirement. This demonstrates that the product of this invention has the performance advantage of fast adsorption rate.

[0068] The adsorption capacity decay rate after 500 cycles is compared to that of the control product, which has an adsorption capacity decay rate of 1.4% after 500 cycles, demonstrating that the product of the present invention has the performance advantage of high cycling stability.

[0069] Table 1. Analysis of adsorption capacity and adsorption rate of arsenic adsorbents

[0070] sample Product of this invention Reference Saturated adsorption capacity 9.5g / L 2.1g / L Arsenic concentration in product water at an influent flow rate of 20 BV / h 0.005 mg / L 1.2 mg / L Adsorption capacity decay rate after 500 cycles 1.4% 31.3%

[0071] Example 2

[0072] 1. Synthesis of Bi(OH)3

[0073] 150 mol of powdered BiCl3 was added to an enamel-lined reactor. While stirring, 400 L of a 2 mol / L NaOH solution at 5°C was added at a rate of 200 L / h. After the NaOH solution was added, a white Bi(OH)3 precipitate was formed. Stirring continued for 4 h. The white slurry was then subjected to plate and frame filter press filtration to obtain a white Bi(OH)3 solid filter cake. The white Bi(OH)3 solid filter cake was placed in a negative pressure dryer and dried at 80°C for 10 h to obtain dry white Bi(OH)3 blocky solid for later use.

[0074] 2. Synthesis of Bi(OH)3-BiOOH

[0075] The above-mentioned dry white Bi(OH)3 blocky solid was taken as 40% of its total mass and dried in a drying oven at 110℃ for 10 hours to obtain BiOOH blocky solid. The BiOOH blocky solid obtained after the heating reaction was then mixed and pulverized with the dry white Bi(OH)3 blocky solid in an impact mill to obtain a uniformly mixed Bi(OH)3-BiOOH blended powder with a particle size of 0.2-10 μm, wherein Bi(OH)3 accounted for 61.7% and BiOOH accounted for 38.3%.

[0076] 3. Synthesis of Bi(OH)3-BiOOH / PAN microspheres

[0077] Bi(OH)3-BiOOH blended powder with a particle size of 0.2-10 μm, polyacrylonitrile (PAN), and N,N-dimethylacetamide (DMAC) were mixed at a certain mass ratio, wherein the mass of the binder PAN accounted for 10% of the total powder mass (Bi(OH)3-BiOOH+PAN), and the mass of the solvent DMAC accounted for 200% of the total powder mass (Bi(OH)3-BiOOH+PAN). All of the Bi(OH)3-BiOOH blended powder, PAN, and DMAC were added to a stirred tank and heated to 95℃, then stirred for 8 hours. The solution was transferred to a dropping pelleting device for pelleting. The pellets fell into deionized water for phase inversion. The wet pellets were then transferred to a 70℃ oven for drying to obtain Bi(OH)3-BiOOH / PAN pellets with a particle size of 0.5-1 mm.

[0078] 4. Synthesis of CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN

[0079] Prepare a mixed solution of copper chloride (CuCl2) and cerium chloride (CeCl3), wherein the concentrations of CuCl2 and CeCl3 are the same, both 2 mol / L. Immerse 200 L of dry Bi(OH)3-BiOOH / PAN microspheres with a particle size of 0.5-1 mm in the 200 L mixed solution of CuCl2 and CeCl3 for 6 hours, allowing the CuCl2 to precipitate. 2+ and Ce 3+ The mixture is fully diffused into the pores of Bi(OH)3-BiOOH / PAN microspheres. The mixed solution is drained, and the wet microspheres are transferred to a 70℃ oven for drying to obtain dry CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN microspheres.

[0080] 5. C 76 O 46 H 52-5x Cu(Ⅱ) x Ce(Ⅲ) xSynthesis of / Bi(OH)3-BiOOH / PAN

[0081] Preparation of saturated tannic acid (C 76 O 46 H 52 The solution was adjusted to C using 4 mol / L sodium hydroxide solution. 76 O 46 H 52 The pH of the solution is 7.5. Twice the mass of the spray solution was sprayed onto the dry CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN microspheres, allowing C... 76 O 46 H 52 The solution gradually permeated into the CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN microspheres, resulting in wet microspheres. The wet microspheres were then dried in a 70°C oven. The dried CuCl2 / CeCl3 / Bi(OH)3-BiOOH / PAN microspheres were confirmed to be dry using the same method as in Example 1. 76 O 46 H 32 Cu(Ⅱ)4Ce(Ⅲ)4 / Bi(OH)3-BiOOH / PAN microspheres.

[0082] Figure 3 The images shown are physical photos and scanning electron microscope (SEM) images of the microspheres obtained in Example 2. Similar to Example 1, the microspheres have a uniform particle size of approximately 0.5-1 mm. The powder is coated with PAN resin and is not easily detached. A rich pore structure can be observed under an electron microscope.

[0083] The adsorption properties of the obtained microsphere products were tested using the same method as in Example 1, as shown in Table 2.

[0084] The results show that the arsenic adsorbent C in this embodiment 76 O 46 H 32The Cu(Ⅱ)4Ce(Ⅲ)4 / Bi(OH)3-BiOOH / PAN microsphere product exhibits a saturated adsorption capacity of 9.7 g / L for arsenic ions, significantly higher than the 2.0 g / L of commercially available arsenic adsorbents, demonstrating the superior adsorption capacity of this invention. Furthermore, comparing the arsenic concentration in the treated wastewater at an influent flow rate of 20 BV / h reveals that this invention's product achieves a treated wastewater concentration of 0.003 mg / L for arsenic-containing wastewater with an influent arsenic concentration of 10 mg / L, meeting the Chinese standard for drinking water quality (GB5749-2022) of 0.01 mg / L. In contrast, the commercially available arsenic adsorbent LSC-As-400 has a treated wastewater concentration of 1.4 mg / L, failing to meet the national standard, further demonstrating the superior adsorption rate of this invention. Furthermore, comparing the adsorption capacity decay rate after 500 cycles, it can be seen that the adsorption capacity decay rate of the product of the present invention after 500 cycles is 1.2%, while the adsorption capacity decay rate of the commercially available arsenic adsorbent LSC-As-400 after 500 cycles is 30.1%, proving that the product of the present invention has the performance advantage of high cycle stability.

[0085] Table 2. Analysis of adsorption capacity and adsorption rate of arsenic adsorbents

[0086] sample Product of this invention Reference Saturated adsorption capacity 9.7g / L 2.0g / L Arsenic concentration in product water at an influent flow rate of 20 BV / h 0.003 mg / L 1.4 mg / L Adsorption capacity decay rate after 500 cycles 1.2% 30.1%

[0087] Example 3

[0088] 1. Synthesis of Bi(OH)3

[0089] 125 mol of powdered BiCl3 was added to an enamel-lined reactor. While stirring, 350 L of a 1.75 mol / L NaOH solution at 2.5 °C was added at a rate of 150 L / h. After the NaOH solution was added, a white Bi(OH)3 precipitate was formed. Stirring continued for 3 h. The white slurry was then subjected to plate and frame filter press filtration to obtain a white Bi(OH)3 solid filter cake. The white Bi(OH)3 solid filter cake was placed in a negative pressure dryer and dried at 65 °C for 7.5 h to obtain dry white Bi(OH)3 blocky solid, which was then set aside for later use.

[0090] 2. Synthesis of Bi(OH)3-BiOOH

[0091] 32.5% of the total mass of the above-mentioned dry white Bi(OH)3 blocky solid was placed in a drying oven at 100℃ and dried for 7.5 h to obtain BiOOH blocky solid. The BiOOH blocky solid obtained after the heating reaction was mixed and pulverized with the dry white Bi(OH)3 blocky solid in an impact mill to obtain a uniformly mixed Bi(OH)3-BiOOH blended powder with a particle size of 0.2-10 μm, wherein Bi(OH)3 accounted for 69.1% and BiOOH accounted for 30.9%.

[0092] 3. Synthesis of Bi(OH)3-BiOOH / PAN microspheres

[0093] Bi(OH)3-BiOOH blended powder with a particle size of 0.2-10 μm, polyacrylonitrile (PAN), and N,N-dimethylacetamide (DMAC) were mixed at a certain mass ratio, wherein the binder PAN accounted for 7.5% of the total powder mass (Bi(OH)3-BiOOH+PAN), and the solvent DMAC accounted for 150% of the total powder mass (Bi(OH)3-BiOOH+PAN). All of the Bi(OH)3-BiOOH blended powder, PAN, and DMAC were added to a stirred tank and heated to 82.5℃, then stirred for 5.5 h. The solution was transferred to a dropping pelleting device for pelleting. The pellets fell into deionized water for phase inversion. The wet pellets were then transferred to a 60℃ oven for drying to obtain Bi(OH)3-BiOOH / PAN pellets with a particle size of 0.5-1 mm.

[0094] 4. Synthesis of CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN

[0095] Prepare a mixed solution of copper chloride (CuCl2) and cerium chloride (CeCl3), wherein the concentrations of CuCl2 and CeCl3 are the same, both 1.5 mol / L. Immerse 150 L of dry Bi(OH)3-BiOOH / PAN microspheres with a particle size of 0.5-1 mm in the 150 L mixed solution of CuCl2 and CeCl3 for 4.5 h, allowing the CuCl2 to precipitate. 2+ and Ce 3+ The mixture is fully diffused into the pores of Bi(OH)3-BiOOH / PAN microspheres. The mixed solution is drained, and the wet microspheres are transferred to a 60℃ oven for drying to obtain dry CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN microspheres.

[0096] 5. C 76 O 46 H 52-5x Cu(Ⅱ) x Ce(Ⅲ) x Synthesis of / Bi(OH)3-BiOOH / PAN

[0097] Preparation of saturated tannic acid (C 76 O 46 H 52 The solution was adjusted to C using a 3 mol / L sodium hydroxide solution. 76 O 46 H 52 The solution has a pH of 7.0. The pH of the C solution is 7.0. 76O 46 H 52 The solution was sprayed onto the dry CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN microspheres, allowing C... 76 O 46 H 52 The solution gradually penetrates into the CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN microspheres. Once the CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN microspheres are fully wetted, spraying is stopped, resulting in wet microspheres. The wet microspheres are then placed in a 60℃ oven for drying.

[0098] The dried C was confirmed to be obtained using the same method as in Example 1. 76 O 46 H 52-5x Cu(Ⅱ) x Ce(Ⅲ) x / Bi(OH)3-BiOOH / PAN microspheres.

[0099] Figure 4 Arsenic adsorbent C obtained in Example 3 76 O 46 H 22 The images show the physical product and scanning electron microscope (SEM) images of the Cu(Ⅱ)6Ce(Ⅲ)6 / Bi(OH)3-BiOOH / PAN microspheres. As can be seen from the images, the arsenic adsorbent microspheres have a very uniform particle size, approximately 0.5-1 mm. The arsenic adsorbent powder is coated with PAN resin, preventing it from detaching. Furthermore, the images show that the PAN resin forms a rich, interconnected network of pores, which facilitates the adsorption and elution of arsenic ions, improving ion exchange efficiency and giving the arsenic adsorbent a high adsorption rate and capacity.

[0100] Table 3 shows the arsenic adsorbent C obtained in Example 3. 76 O 46 H 22 A comparison of the adsorption capacity, adsorption rate, and cycle stability of Cu(Ⅱ)6Ce(Ⅲ)6 / Bi(OH)3-BiOOH / PAN microspheres with the competing product LSC-As-400. Arsenic adsorbent C 76 O 46 H 22The Cu(Ⅱ)6Ce(Ⅲ)6 / Bi(OH)3-BiOOH / PAN microsphere product exhibits a saturated adsorption capacity of 10.1 g / L for arsenic ions, significantly higher than the 2.3 g / L of commercially available arsenic adsorbents, demonstrating the superior adsorption capacity of this invention. Furthermore, comparing the arsenic concentration in the treated wastewater at an influent flow rate of 20 BV / h reveals that this invention's product achieves a treated wastewater concentration of 0.002 mg / L for arsenic-containing wastewater with an influent arsenic concentration of 10 mg / L, meeting the Chinese standard for drinking water quality (GB5749-2022) of 0.01 mg / L. In contrast, the commercially available arsenic adsorbent LSC-As-400 produces a treated wastewater concentration of 1.1 mg / L, failing to meet the national standard, further demonstrating the superior adsorption rate of this invention. Furthermore, comparing the adsorption capacity decay rate after 500 cycles, it can be seen that the adsorption capacity decay rate of the product of the present invention after 500 cycles is 0.9%, while the adsorption capacity decay rate of the commercially available arsenic adsorbent LSC-As-400 after 500 cycles is 30.7%, proving that the product of the present invention has the performance advantage of high cycle stability.

[0101] Table 3. Saturated adsorption capacity and adsorption rate analysis of arsenic adsorbents

[0102] sample Product of this invention Reference Saturated adsorption capacity 10.1g / L 2.3g / L Arsenic concentration in product water at an influent flow rate of 20 BV / h 0.002 mg / L 1.1 mg / L Adsorption capacity decay rate after 500 cycles 0.9% 30.7%

[0103] Comparative Example 1: Investigating the effect of reducing the proportion of Bi(OH)3 in the blended powder on product performance.

[0104] 1. Synthesis of Bi(OH)3:

[0105] 125 mol of powdered BiCl3 was added to an enamel-lined reactor. While stirring, 350 L of a 1.75 mol / L NaOH solution at 2.5 °C was added at a rate of 150 L / h. After the NaOH solution was added, a white Bi(OH)3 precipitate was formed. Stirring continued for 3 h. The white slurry was then subjected to plate and frame filter press filtration to obtain a white Bi(OH)3 solid filter cake. The white Bi(OH)3 solid filter cake was placed in a negative pressure dryer and dried at 100 °C for 7.5 h to obtain a dry white blocky solid, which was then set aside for later use.

[0106] 2. Synthesis of Bi(OH)3-BiOOH

[0107] Take 32.5% of the total mass of the above-mentioned dry white blocky solid and dry it in a drying oven at 100℃ for 7.5 h to obtain BiOOH blocky solid. Put the BiOOH blocky solid obtained after heating reaction and the dry white blocky solid into an impact mill for co-pulverization to obtain a uniformly mixed Bi(OH)3-BiOOH blended powder with a particle size of 0.2-10 μm.

[0108] The resulting blended powder was sampled, dissolved in acid, and the bismuth content was measured. The measurable sample contained 50.6% Bi(OH)3 and 49.4% BiOOH.

[0109] Steps 3-5 are the same as in Example 3.

[0110] The product was confirmed to be C using the same detection method for material quality changes throughout the entire process (same as in Example 1). 76 O 46 H 22 Cu(Ⅱ)6Ce(Ⅲ)6 / Bi(OH)3-BiOOH / PAN

[0111] The adsorption properties of the obtained microsphere products were determined using the same method as in Examples 1-3, as shown in Table 4.

[0112] Because the drying temperature of the white Bi(OH)3 solid filter cake in the negative pressure dryer was increased from 65℃ to 100℃ in step 1, Bi(OH)3 was dehydrated under high temperature conditions, resulting in a low proportion of Bi(OH)3 in the blended powder, which was only 50.6%, ultimately reducing the saturated adsorption capacity of the arsenic adsorbent to 6.3 g / L.

[0113] Table 4. Saturated adsorption capacity analysis of arsenic adsorbents in Example 3 and Comparative Example 1:

[0114] Saturated adsorption capacity of Example 3 10.1g / L Saturated adsorption capacity of Comparative Example 1 6.3g / L

[0115] Comparative Example 2: Investigating the effect of increasing the proportion of Bi(OH)3 in the blended powder on product performance.

[0116] Bi(OH)3 was synthesized following the same steps as in Example 3.

[0117] Take 20% of the total mass of the obtained dry white Bi(OH)3 blocky solid and dry it in a drying oven at 100℃ for 7.5 h to obtain BiOOH blocky solid. The BiOOH blocky solid obtained after the heating reaction and the dry white Bi(OH)3 blocky solid are then mixed and pulverized in an impact mill to obtain a uniformly mixed Bi(OH)3-BiOOH blend powder with a particle size of 0.2-10 μm, wherein Bi(OH)3 accounts for 81.1% and BiOOH accounts for 18.9%.

[0118] Steps 3-5 are the same as in Example 3.

[0119] The product was confirmed to be C using the same detection method for material quality changes throughout the entire process (same as in Example 1). 76 O 46 H 22 Cu(Ⅱ)6Ce(Ⅲ)6 / Bi(OH)3-BiOOH / PAN.

[0120] The adsorption properties of the obtained microsphere products were determined using the same method as in Examples 1-3, as shown in Table 5.

[0121] Because the amount of dry white Bi(OH)3 blocky solid used to prepare BiOOH was reduced in step 2, the proportion of Bi(OH)3 in the resulting Bi(OH)3-BiOOH blend powder was too high, reaching 81.1%, while the proportion of BiOOH was only 18.9%, which is too low. As shown in Table 5, when the proportion of BiOOH in the Bi(OH)3-BiOOH blend powder is too low, the synergistic adsorption sites provided by Bi(OH)3-BiOOH are insufficient, which also leads to a decrease in the saturated adsorption capacity of the arsenic adsorbent to 4.6 g / L.

[0122] Table 5. Saturated adsorption capacity analysis of arsenic adsorbents in Example 3 and Comparative Example 2:

[0123] Saturated adsorption capacity of Example 3 10.1g / L Saturated adsorption capacity of Comparative Example 2 4.6g / L

[0124] Comparative Example 3: Investigating the effect of increasing the proportion of BiOOH in the blended powder on product performance.

[0125] 1. Bi(OH)3 was synthesized using the same steps as in Example 3.

[0126] 2. Synthesis of Bi(OH)3-BiOOH

[0127] Take 45% of the total mass of the obtained dry white Bi(OH)3 blocky solid and dry it in a drying oven at 100℃ for 7.5 h to obtain BiOOH blocky solid. The BiOOH blocky solid obtained after the heating reaction and the dry white Bi(OH)3 blocky solid are then mixed and pulverized in an impact mill to obtain a uniformly mixed Bi(OH)3-BiOOH blended powder with a particle size of 0.2-10 μm, wherein Bi(OH)3 accounts for 56.8% and BiOOH accounts for 43.2%.

[0128] Steps 3-5 are the same as in Example 3.

[0129] After detecting changes in material quality throughout the entire process (using the same method as in Example 1), the product was confirmed to be C. 76 O 46 H 22 Cu(Ⅱ)6Ce(Ⅲ)6 / Bi(OH)3-BiOOH / PAN.

[0130] In this embodiment, the proportion of Bi(OH)3 in the Bi(OH)3-BiOOH blend powder was too high, reaching 56.8%, while the proportion of BiOOH was 43.2%, which was outside the range of 23.7%-38.3%. The adsorption performance of the obtained microsphere products was measured using the same method as in Examples 1-3. As shown in Table 6, when the proportion of BiOOH in the Bi(OH)3-BiOOH blend powder was too low, the synergistic adsorption sites provided by Bi(OH)3-BiOOH were insufficient, resulting in a decrease in the saturated adsorption capacity of the arsenic adsorbent to 3.4 g / L.

[0131] Table 6. Saturated adsorption capacity analysis of arsenic adsorbents in Example 3 and Comparative Example 3:

[0132] Saturated adsorption capacity of Example 3 10.1g / L Saturated adsorption capacity of Comparative Example 3 3.4g / L

[0133] Comparative Example 4 examines the effect of different adhesives on product performance.

[0134] Steps 1 and 2 are the same as in Example 3.

[0135] 3. Synthesis of Bi(OH)3-BiOOH / PVC microspheres

[0136] Bi(OH)3-BiOOH blended powder with a particle size of 0.2-10 μm, polyvinyl chloride (PVC), and N,N-dimethylacetamide (DMAC) were mixed at a certain mass ratio, wherein the binder PVC accounted for 7.5% of the total powder mass (Bi(OH)3-BiOOH+PVC), and the solvent DMAC accounted for 150% of the total powder mass (Bi(OH)3-BiOOH+PVC). All of the Bi(OH)3-BiOOH blended powder, PVC, and DMAC were added to a stirred tank and heated to 82.5℃, then stirred for 5.5 h. The solution was transferred to a dropping pelleting device for pelleting. The pellets fell into deionized water for phase inversion. The wet pellets were then transferred to a 60℃ oven for drying to obtain Bi(OH)3-BiOOH / PVC pellets with a particle size of 0.5-1 mm.

[0137] Steps 4 and 5 are the same as in Example 3.

[0138] The adsorption performance of the obtained microspheres was determined using the same method as in Examples 1-3, and the results are shown in Table 7. When the binder was replaced by polyacrylonitrile (PAN) with polyvinyl chloride (PVC), the saturated adsorption capacity of the arsenic adsorbent decreased to 7.1 g / L. This is likely because when PAN is used as a binder, it contains a large number of CN groups. CN groups have lone pairs of electrons, while Bi atoms on Bi(OH)3-BiOOH have empty electron orbitals. The strong electrostatic interaction between Bi atoms and CN groups allows the Bi(OH)3-BiOOH powder to bond more firmly to the PAN framework, reducing the shedding of Bi(OH)3-BiOOH / PAN microspheres and thus obtaining better adsorption performance.

[0139] Table 7. Saturated adsorption capacity analysis of arsenic adsorbents in Example 3 and Comparative Example 4:

[0140] Saturated adsorption capacity of Example 3 10.1g / L Saturated adsorption capacity of Comparative Example 4 7.1g / L

[0141] Comparative Example 5: The effect of parameter changes during preparation on product performance

[0142] Steps 1 and 2 are the same as in Example 3.

[0143] 3. Synthesis of Bi(OH)3-BiOOH / PAN microspheres

[0144] Bi(OH)3-BiOOH blended powder with a particle size of 0.2-10 μm, polyacrylonitrile (PAN), and N,N-dimethylacetamide (DMAC) were mixed at a certain mass ratio, wherein the binder PAN accounted for 7.5% of the total powder mass (Bi(OH)3-BiOOH+PAN), and the solvent DMAC accounted for 150% of the total powder mass (Bi(OH)3-BiOOH+PAN). All of the Bi(OH)3-BiOOH blended powder, PAN, and DMAC were added to a stirred tank and heated to 82.5℃, then stirred for 5.5 h. The solution was transferred to a dropping pelleting device for pelleting. The pellets fell into deionized water for phase inversion. The resulting wet pellets were not dried and were used for later use.

[0145] 4. Synthesis of CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN

[0146] Prepare a mixed solution of copper chloride (CuCl2) and cerium chloride (CeCl3), wherein the concentrations of CuCl2 and CeCl3 are the same, both 1.5 mol / L. Immerse 150 L of wet Bi(OH)3-BiOOH / PAN microspheres with a particle size of 0.5-1 mm in the 150 L mixed solution of CuCl2 and CeCl3 for 4.5 h, allowing the CuCl2 to precipitate. 2+ and Ce 3+The mixture is fully diffused into the pores of Bi(OH)3-BiOOH / PAN microspheres. The mixed solution is drained, and the wet microspheres are transferred to a 60℃ oven for drying to obtain dry CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN microspheres.

[0147] Step 5 is the same as in Example 3.

[0148] Compared with Example 3, this example replaces the Bi(OH)3-BiOOH / PAN dry microspheres in Example 3 with Bi(OH)3-BiOOH / PAN wet microspheres, and directly soaks the wet microspheres in a mixed solution of CuCl2 and CeCl3, while keeping other steps unchanged.

[0149] The adsorption performance of the obtained microspheres was determined using the same method as in Examples 1-3. The results, shown in Table 8, indicate that when the dry Bi(OH)3-BiOOH / PAN microspheres were replaced with wet Bi(OH)3-BiOOH / PAN microspheres, the saturated adsorption capacity of the arsenic adsorbent decreased to 1.6 g / L. This is presumably because the synthesis process of the CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN microspheres involves soaking the dry Bi(OH)3-BiOOH / PAN microspheres in a mixed solution of CuCl2 and CeCl3, which facilitates the absorption of more CuCl2 and CeCl3 solution. The wet Bi(OH)3-BiOOH / PAN microspheres reduce the amount of CuCl2 and CeCl3 participating in the reaction, thus affecting the adsorption performance.

[0150] Table 8. Saturated adsorption capacity analysis of arsenic adsorbents in Example 3 and Comparative Example 5:

[0151] Saturated adsorption capacity of Example 3 10.1g / L Saturated adsorption capacity of Comparative Example 5 1.6g / L

[0152] Comparative Example 6: The effect of parameter changes during preparation on product performance

[0153] A method for preparing an arsenic adsorbent, the method comprising:

[0154] Steps 1-3 are the same as in Example 3.

[0155] 4. Synthesis of CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN

[0156] Prepare a mixed solution of copper chloride (CuCl2) and cerium chloride (CeCl3), wherein the concentrations of CuCl2 and CeCl3 are the same, both 1.5 mol / L. Immerse 150 L of dry Bi(OH)3-BiOOH / PAN microspheres with a particle size of 0.5-1 mm in the 150 L mixed solution of CuCl2 and CeCl3 for 4.5 h, allowing the CuCl2 to precipitate.2+ and Ce 3+ The solution is fully diffused into the pores of Bi(OH)3-BiOOH / PAN microspheres. The mixed solution is then drained, and the wet microspheres are left undried for later use.

[0157] 5. C 76 O 46 H 52-5x Cu(Ⅱ) x Ce(Ⅲ) x Synthesis of / Bi(OH)3-BiOOH / PAN

[0158] Preparation of saturated tannic acid (C 76 O 46 H 52 The solution was adjusted to C using a 3 mol / L sodium hydroxide solution. 76 O 46 H 52 The solution has a pH of 7.0. The pH of the C solution is 7.0. 76 O 46 H 52 The solution was sprayed onto the wet CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN microspheres, allowing C... 76 O 46 H 52 The solution gradually penetrated into the CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN microspheres. Once the CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN microspheres were fully wetted, spraying was stopped, yielding a wet C. 76 O 46 H 52-5x Cu(Ⅱ) x Ce(Ⅲ) x / Bi(OH)3-BiOOH / PAN microspheres. Wet C 76 O 46 H 52-5x Cu(Ⅱ) x Ce(Ⅲ) x The / Bi(OH)3-BiOOH / PAN microspheres were dried in an oven at 60℃ to obtain dried C 76 O 46 H 52-5x Cu(Ⅱ) x Ce(Ⅲ) x / Bi(OH)3-BiOOH / PAN microspheres.

[0159] Compared with Example 3, in this example, the CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN microspheres were not dried, and the spray solution was directly sprayed onto the wet microspheres, while other aspects remained unchanged.

[0160] The adsorption performance of the obtained microspheres was determined using the same method as in Examples 1-3. The results, shown in Table 9, indicate that the saturated adsorption capacity of the microspheres in this example decreased to 0.9 g / L. This is presumably because the wet CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN microspheres were not dried before reacting directly with the spray solution, resulting in a reduction in the actual amount of C participating in the reaction. 76 O 46 H 52 When the amount of solution decreases, the reaction becomes incomplete, thus reducing the adsorption performance.

[0161] Table 9. Saturated adsorption capacity analysis of arsenic adsorbents in Example 3 and Comparative Example 6:

[0162] Saturated adsorption capacity of Example 3 10.1g / L Saturated adsorption capacity of Comparative Example 6 0.9g / L

[0163] Comparative Example 7: Effect of changes in complexing solution on product performance

[0164] Steps 1-3 are the same as in Example 3.

[0165] 4. Synthesis of CeCl3 / Bi(OH)3-BiOOH / PAN

[0166] Prepare a 1.5 mol / L cerium chloride (CeCl3) solution. Immerse 150 L of dry Bi(OH)3-BiOOH / PAN microspheres with a particle size of 0.5-1 mm in 150 L of CeCl3 solution for 4.5 h to allow the CeCl3 to mature. 3+ The mixture is fully diffused into the pores of Bi(OH)3-BiOOH / PAN microspheres. The mixed solution is drained, and the wet microspheres are transferred to a 60℃ oven for drying to obtain dry CeCl3 / Bi(OH)3-BiOOH / PAN microspheres.

[0167] Step 5 is the same as in Example 3.

[0168] Compared to Example 3, this example replaces the complexation solution with a single cerium chloride (CeCl3) solution instead of a mixed solution of copper chloride (CuCl2) and cerium chloride (CeCl3).

[0169] The adsorption performance of the obtained microspheres was determined using the same method as in Examples 1-3. The results, shown in Table 10, indicate that the saturated adsorption capacity of the microspheres in this example decreased to 2.2 g / L. The likely reason is that Cu... 2+ and Ce 3+ Together with tannic acid (C 76 O 46 H 52 ) during complexation, C was increased 76 O 46 H 52-5xCu(Ⅱ) x Ce(Ⅲ) x The stability of the precipitate and the reduction of C 76 O 46 H 52-5x Cu(Ⅱ) x Ce(Ⅲ) x The solubility of the precipitate in water improves the physicochemical stability of the material, thereby increasing the saturated adsorption capacity and overall adsorption performance of the arsenic adsorbent.

[0170] Table 10 Saturated adsorption capacity analysis of arsenic adsorbents in Example 3 and Comparative Example 7:

[0171] Saturated adsorption capacity of Example 3 10.1g / L Saturated adsorption capacity of Comparative Example 7 2.2g / L

[0172] In summary, this invention selects an appropriate Bi(OH)3-BiOOH ratio, utilizes the large number of CN groups contained in PAN to obtain a better bonding effect, and uses a CuCl2-CeCl3 mixed solution as a precipitant for tannic acid to improve C. 76 O 46 H 52-5x Cu(Ⅱ) x Ce(Ⅲ) x The stability of the precipitate and the reduction of C 76 O 46 H 52-5x Cu(Ⅱ) x Ce(Ⅲ) x The precipitate's solubility in water ultimately resulted in excellent adsorption properties.

Claims

1. A method for preparing an arsenic removal adsorbent, the method comprising the following steps: (1) preparing Bi(OH)3-BiOOH blended powder weighing solid BiOOH and Bi(OH)3, and mixing them thoroughly until a blended powder is obtained, in which Bi(OH)3 accounts for 61.7% to 76.3% by mass, and the balance is BiOOH; (2) preparing Bi(OH)3-BiOOH / PAN beads weighing Bi(OH)3-BiOOH blended powder, polyacrylonitrile (PAN), and N,N-dimethylacetamide (DMAC), wherein the polyacrylonitrile accounts for 5% to 10% by mass of the total powder, and the N,N-dimethylacetamide accounts for 100% to 200% by mass of the total powder, heating and stirring the Bi(OH)3-BiOOH blended powder, the polyacrylonitrile, and the N,N-dimethylacetamide until they are mixed uniformly to obtain a feed liquid, transferring the feed liquid to a bead dropping device to drop beads, and obtaining wet beads by phase inversion of the beads dropped into deionized water, and drying the wet beads to obtain Bi(OH)3-BiOOH / PAN beads with a particle size of 0.5 to 1 mm; (3) preparing CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN preparing a mixed solution of CuCl2 and CeCl3, wherein the molar concentrations of CuCl2 and CeCl3 are the same and are 1 to 2 mol / L; immersing the Bi(OH)3-BiOOH / PAN beads in the mixed solution of CuCl2 and CeCl3, and drying the wet beads after solid-liquid separation to obtain dried CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN beads; (4) Preparation of C 76 O 46 H 52-5x Cu(II) x Ce(III) x / Bi(OH)3-BiOOH / PAN A saturated tannic acid (C 76 O 46 H 52 ) solution was prepared, and the pH value of the tannic acid solution was adjusted to 6.5-7.5 by using a sodium hydroxide solution to obtain a spraying solution; An excess of the solution is sprayed onto the dry CuCl2-CeCl3 / Bi(OH)3-BiOOH / PAN beads until the beads are fully wetted to obtain wet state C 76 O 46 H 52-5x Cu(Ⅱ) x Ce(Ⅲ) x / Bi(OH)3-BiOOH / PAN beads, wherein 4≤x≤8, and wet state C 76 O 46 H 52-5x Cu(Ⅱ) x Ce(Ⅲ) x / Bi(OH)3-BiOOH / PAN beads are dried to obtain dry arsenic removal adsorbent.

2. The production method according to claim 1, characterized by the immersing in step (3) is achieved by immersing 1 to 2 parts by volume of Bi(OH)3-BiOOH / PAN beads in 1 to 2 parts by volume of the mixed solution of CuCl2 and CeCl3 for 3 to 6 hours.

3. The method of claim 1, wherein The drying in steps (3) and (4) is performed in an oven at 50 to 70°C.

4. The method of claim 1, wherein In step (4), the mass ratio of the spraying solution to the dried beads is 1:1 to 2:

1.

5. The method of claim 1, wherein In step (4), the concentration of the sodium hydroxide solution is 2 to 4 mol / L.

6. The use of the arsenic removal adsorbent prepared by the method of any one of claims 1 to 5 in water treatment.

7. Use according to claim 6, characterized in that The arsenic removal adsorbent is used for adsorbing trivalent arsenic and pentavalent arsenic in wastewater.

Images