Preparation method and application of heavy metal adsorption material

Abstract

The present invention relates to the technical field of environmental heavy metal remediation, specifically disclosing a method for preparing a heavy metal adsorption material and its application. The present invention comprises mixing pretreated arsenic gypsum with straw in a certain proportion, adding an inorganic acid, and co-pyrolyzing the mixture to obtain a heavy metal adsorption material (GBC). The GBC can efficiently adsorb lead (II) in water. This method can simultaneously achieve efficient arsenic removal from the arsenic gypsum and adsorption of lead (II) in water, resulting in an arsenic content of less than 0.63% and a leaching concentration of less than 0.5 mg / L. Furthermore, the GBC achieves a maximum adsorption capacity of 339.97 mg / g for lead (II), which is 9.7 times that of the original biochar (BC). Through a "waste-to-waste" approach, the present invention achieves the synergistic resource utilization of industrial hazardous waste and agricultural solid waste, providing a new approach for the treatment of arsenic-containing solid waste and the remediation of heavy metal pollution.

Description

Technical Field

[0001] The present invention belongs to the technical field of environmental heavy metal treatment, and in particular relates to a preparation method of a heavy metal adsorption material and application thereof. Background Art

[0002] Arsenic, as a highly toxic metal element, is often found in mineral resources such as coal, iron, gold, and copper. Arsenic gypsum (ABG) is a typical hazardous waste generated during the desulfurization process of non-ferrous metal mining and smelting industries. The arsenic in this type of waste is mainly in the form of unstable trivalent (As 3+ ) and pentavalent (As 5+ ) forms, such as arsenate ( ) and arsenic oxide (As2O3, As2O5), whose leaching toxicity far exceeds the limit of the "Hazardous Waste Identification Standard" (GB 5085.3-2007), posing a long-term and serious threat to groundwater and soil ecosystems.

[0003] At present, pyrolysis, wet arsenic removal and solidification / stabilization technologies are still the mainstream disposal processes at home and abroad, and arsenic is immobilized through thermodynamic decomposition or chemical conversion: (1) Pyrolysis arsenic removal relies on high-temperature roasting to volatilize arsenic, but the cost of treating low-arsenic solid waste is high, the arsenic removal rate is low, and the resource value of the product is limited; (2) Although wet arsenic removal can separate arsenic from metal components through acid / alkaline leaching, it has insufficient metal-arsenic separation selectivity and is prone to produce highly toxic gases such as AsH3; (3) Solidification / stabilization technology (such as cement solidification) can temporarily seal arsenic, but it faces the risk of arsenic re-release in the long term. With the gradual improvement of the environmental supervision system and the continuous accumulation of waste slag stockpiles, building a scientific and efficient arsenic-containing solid waste disposal technology system has become a core task to solve the problem of arsenic pollution.

[0004] At the same time, lead, a common heavy metal, poses a serious threat to ecosystems and human health due to its persistence, bioaccumulation, and high toxicity. Traditional treatment technologies include chemical precipitation, which is inefficient for treating low-concentration lead and prone to secondary pollution. Membrane filtration and electrodialysis are expensive, while conventional biochar has an insufficient adsorption capacity (typically less than 50 mg / g), making it difficult to meet practical needs.

[0005] Despite the gradual promotion of technologies such as returning straw to farmland and converting it into feed, resource utilization efficiency still needs to be improved due to limitations such as an imbalance in the carbon-nitrogen ratio and high pretreatment energy consumption. Therefore, to address the multiphase pollution problem of "arsenic-containing solid waste, agricultural straw, and lead-contaminated water bodies," there is an urgent need to develop an innovative technology that can achieve "waste treatment and synergistic resource utilization" by coupling solid waste treatment with the preparation of functional materials. This technology can overcome the bottlenecks of existing technologies, which are high cost, high risk of secondary pollution, and low resource utilization. Summary of the Invention

[0006] The present invention aims to provide a method for preparing a heavy metal adsorption material, which can achieve efficient arsenic removal and simultaneous functionalization of the adsorption material, and provide an economical and efficient solution for the disposal of arsenic-containing solid waste and the remediation of lead pollution in water bodies.

[0007] In order to solve the above technical problems, the technical solution proposed by the present invention is:

[0008] In a first aspect, the present invention provides a method for preparing a heavy metal adsorption material, comprising the following steps:

[0009] A. collecting arsenic gypsum and straw, drying and grinding them respectively, and then mixing them to obtain a first mixture;

[0010] B. adding an inorganic acid to the first mixture and stirring the mixture thoroughly with a stirring device to obtain a second mixture;

[0011] C. Add the second mixture into a high-temperature atmosphere furnace, and under the protection of inert gas, raise the temperature to 450°C-850°C, and pyrolyze at a constant temperature for 120min-300min;

[0012] D. After the co-pyrolysis is completed, wait for the system to cool to below 80°C to obtain the heavy metal adsorption material.

[0013] In some specific embodiments, the arsenic gypsum is a solid waste generated by the metallurgical and chemical industries, and its main elements are O, Ca, S, F, etc., and arsenic is mainly in the form of arsenate (Ca3(AsO4)2, ) and arsenic oxide (As2O3, As2O5).

[0014] The straw can be any one or more mixtures of corn straw, wheat straw, rice straw, sorghum straw and other crop straws. Other crops can be sugarcane, rape straw, peanut straw, sweet potato and potato straw, etc.

[0015] In some specific embodiments, in step A, the arsenic gypsum is dried at a temperature of 105-110° C. for 2-3 hours and passed through an 80-100 mesh sieve; the straw is dried at a temperature of 60-80° C. for 12-24 hours and passed through a 40-60 mesh sieve.

[0016] It should be noted that the straw needs to be pretreated before drying and grinding. The pretreatment includes removing impurities such as dirt and residual leaves on the surface of the straw, and then washing it with deionized water 3-5 times.

[0017] According to the present invention, in some embodiments, the drying temperature of arsenic gypsum is 105°C-110°C, for example, 105°C, 106°C, 107°C, 108°C, 109°C, 110°C, or a range consisting of any two ratios thereof.

[0018] The particle size of the arsenic gypsum is such that it can pass through an 80-mesh sieve to a 100-mesh sieve, for example, an 80-mesh sieve, a 90-mesh sieve, a 100-mesh sieve, or a range consisting of any ratio of two of the above.

[0019] According to the present invention, in some embodiments, the drying temperature of the straw is 60°C-80°C, for example, 60°C, 65°C, 70°C, 75°C, 80°C, or a range consisting of any two ratios thereof.

[0020] The drying temperature of the straw is 12h-24h, for example, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, 21h, 22h, 23h, 24h, or a range consisting of any two ratios of the above.

[0021] The particle size of the straw is such that it can pass through a 40-mesh sieve to a 60-mesh sieve, for example, a 40-mesh sieve, a 50-mesh sieve, a 60-mesh sieve, or a range consisting of any ratio of two of the above.

[0022] Through the above pretreatment of arsenic gypsum and straw, the contact area between arsenic gypsum and straw can be greatly increased, so that the two can fully react.

[0023] In some specific embodiments, the mixing in step A refers to mixing arsenic gypsum and straw in different mass ratios, and the mass ratio of the arsenic gypsum to straw is 1:(1-4).

[0024] In some specific embodiments of the present invention, the mixing mass ratio of the arsenic gypsum and the straw is 1:1, 1:2, 1:3, 1:4, or a range consisting of any two of the above ratios.

[0025] In some specific embodiments, in step B, the inorganic acid can be a mixture of one or more of sulfuric acid, hydrochloric acid, and nitric acid, and the amount of the inorganic acid added is 0-0.8 mL / g. For example, the amount of the inorganic acid added is 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or a range consisting of any two ratios thereof.

[0026] In a second aspect, the present invention also provides a new type of heavy metal adsorption material.

[0027] In some specific embodiments, the arsenic content of the heavy metal adsorption material is 0-2wt%, and the arsenic leaching concentration is 0-0.5 mg / L. After the raw solid arsenic is thermally decomposed to obtain the heavy metal adsorption material, the heavy metal adsorption material meets the requirements of the "General Solid Waste Landfill Pollution Control Standard" (GB 18599-2020), and the ecological risk is reduced from the high risk level (HR) of the raw material arsenic gypsum to the low risk level (LR), completely solving the environmental pollution risks caused by long-term storage of arsenic gypsum.

[0028] In some specific embodiments, the arsenic content is 0-2 wt%, for example, 0, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1.0 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt%, 2.0 wt%, or a range consisting of any two ratios thereof.

[0029] In some embodiments, the leaching concentration of arsenic is 0-0.5 mg / L, for example, 0, 0.1 mg / L, 0.2 mg / L, 0.3 mg / L, 0.4 mg / L, 0.5 mg / L, or a range consisting of any two ratios thereof.

[0030] In some embodiments, the applicable pH range of the heavy metal adsorption material is between 3-7, for example, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, or a range consisting of any two ratios thereof.

[0031] In some embodiments, the heavy metal adsorption material adsorbs lead (Pb), achieving a maximum adsorption capacity of 339.97 mg / g for Pb(II), a nearly 9.7-fold increase compared to raw corn straw biochar (BC) (approximately 35 mg / g). Its wide pH adaptability (3.0-7.0) covers the common acidic and alkaline environments of natural water bodies and industrial wastewater, and achieves rapid adsorption equilibrium within one hour, far exceeding the 4-6 hours required by traditional adsorption materials (e.g., activated carbon), significantly improving the efficiency of water pollution remediation.

[0032] The third aspect of the present invention provides a heavy metal adsorbent, which includes the preparation method of the heavy metal adsorbent material mentioned in the first aspect, or the heavy metal adsorbent material mentioned in the second aspect. The heavy metal adsorbent can be used in different scenarios such as industrial wastewater treatment, soil remediation, water body remediation, sludge treatment and drinking water purification.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The preparation method and application of the heavy metal adsorption material proposed in the present invention can achieve the simultaneous disposal of arsenic gypsum hazardous waste and straw agricultural waste, abandoning the traditional path of "first treating waste and then producing", and directly "making materials from waste" through the co-pyrolysis process, thereby reducing the cost of hazardous waste disposal (saving 40-50% of the cost compared to the cement solidification method), and at the same time replacing traditional adsorbents (such as commercial activated carbon), achieving the dual benefits of solid waste resource utilization and water pollution remediation. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0036] Figure 1 This is a schematic diagram of the preparation process of heavy metal adsorption materials;

[0037] Figure 2 The microscopic morphology, element proportion and element distribution of heavy metal adsorption materials (GBC);

[0038] Figure 3 is the XRD pattern of heavy metal adsorption material (GBC);

[0039] Figure 4 The adsorption kinetics curves of GBC and BC for Pb(II) are shown in Figure 2. The abscissa (Ce) represents the equilibrium concentration of the adsorbate in the solution when the adsorption reaches equilibrium, and the unit is mg / L. The ordinate (Qe) represents the mass of the adsorbate per unit mass of the adsorbent when the adsorption reaches equilibrium, and the unit is mg / g.

[0040] Figure 5 are the FTIR images before and after BC and GBC adsorption;

[0041] To facilitate understanding of the present invention, the present invention will be described in more comprehensive and detailed form below in conjunction with the accompanying drawings and preferred embodiments. However, the protection scope of the present invention is not limited to the following specific embodiments.

[0042] Unless otherwise defined, all technical terms used hereinafter have the same meanings as those generally understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0043] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods. DETAILED DESCRIPTION

[0044] The present application will be further described below with reference to specific examples. It should be understood that these examples are only used to illustrate the present application and are not intended to limit the scope of the present application.

[0045] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range or the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0046] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0047] Unless otherwise specified, all technical features and optional technical features of the present invention can be combined with each other to form a new technical solution.

[0048] The present invention is described in detail below with reference to the examples, but the implementation and protection of the present invention are not limited thereto. The following examples are only partial examples of the present invention and are not intended to limit the present invention. Where specific techniques or conditions are not specified in the examples, the techniques or conditions described in the literature in this field or the product instructions are used. Where the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be obtained commercially.

[0049] Example 1 Preparation of heavy metal adsorption material by co-pyrolysis of arsenic gypsum and straw

[0050] (1) Raw material pretreatment

[0051] Arsenic gypsum: 100 g of arsenic gypsum (the main element composition and proportion of arsenic gypsum are shown in Table 1) was selected, and the arsenic gypsum was dried (temperature controlled at 105°C, time for 3 hours) and ground (passed through an 80-mesh sieve) to remove impurities and refine the particles.

[0052]

[0053] Corn stalks: Remove dirt, residual leaves and other impurities from the surface of the corn stalks, wash with deionized water 3-5 times, dry in a drying oven at 75°C to constant weight (about 12 hours), grind, pass through a 40-mesh sieve, and seal for storage.

[0054] (2) Co-pyrolysis process

[0055] Raw material mixing: Arsenic gypsum and straw are mixed in a ratio of 1:2. Sulfuric acid is added to the mixture at an addition amount of 0.4 mL / g. The mixture is fully stirred using a stirring device (speed 100 r / min, time 10 minutes) to allow the sulfuric acid to penetrate evenly and create an acidic environment for the pyrolysis reaction.

[0056] Pyrolysis: The mixture was placed in a high-temperature furnace. Nitrogen (200 mL / min) was introduced for 30 minutes to completely expel air from the furnace and create an inert atmosphere. The temperature was then programmed to 750°C at a rate of 10°C / min, and the pyrolysis was maintained at this temperature for 120 minutes. During this process, the arsenate and arsenic oxide in the arsenic gypsum, under the synergistic effects of sulfuric acid and the reducing atmosphere, underwent volatilization (e.g., formation of gaseous As₂O₃ products) and fixation (partial formation of stable forms such as As₂S₃). The biochar produced by the pyrolysis of corn straw reconstituted with the mineral components of the arsenic gypsum, optimizing the pore structure and surface functional groups of the heavy metal adsorption material.

[0057] Collection of heavy metal adsorption materials: After the pyrolysis is completed, wait for the furnace to cool naturally to below 80°C, take out the heavy metal adsorption material (GBC), and store it in a sealed container.

[0058] Determination of arsenic content in heavy metal adsorption materials (GBC):

[0059] First, accurately weigh 0.05 g of GBC powder and add 10 mL of a mixed acid digestion solution (HNO₃:HF:H₂O₂:HClO₄ = 5:2:2:1). Heat on a hot plate until the solution is clear and transparent, leaving approximately 1 mL of clear solution. The digestion solution is then brought to a volume of 25 mL and filtered through a 0.22 μm filter membrane. Finally, the arsenic concentration in the filtrate is determined using inductively coupled plasma mass spectrometry (ICP-OES).

[0060] Continuous chemical extraction method (BCR method):

[0061] Arsenic in heavy metal adsorption materials is divided into four forms: acetic acid extractable form (F1), reducible form (F2), oxidizable form (F3), and residual form (F4). Residual form arsenic (F4) is tightly bound to the mineral lattice and difficult to release under natural conditions. It has extremely low bioavailability and minimal environmental risk. Therefore, when utilizing arsenic gypsum as a resource, effective measures must be taken to convert unstable arsenic into a stable form (such as the residual form). Reducing its ecological risk is key to achieving the safe use of arsenic gypsum. The specific extraction method and steps are shown in Table 2:

[0062] Table 2 Steps and components in the BCR continuous chemical extraction method

[0063]

[0064] The arsenic content and arsenic form in the heavy metal adsorption material (GBC) after the co-pyrolysis reaction in Example 1 were determined using ICP-OES and BCR continuous extraction methods. It should be further noted that the aforementioned arsenic form refers to the speciation analysis of arsenic contained in the heavy metal material based on the arsenic content. A higher residual arsenic content indicates a more stable heavy metal material. By measuring the arsenic content and the ratio of residual arsenic in the heavy metal material, it is possible to effectively reflect whether the heavy metal adsorption material can effectively utilize resources. The experimental results of Example 1 are shown in Table 3.

[0065] Table 3 Arsenic content and occurrence forms in heavy metal adsorption materials (GBC)

[0066]

[0067] Example 2-5 Experimental data of different proportions of straw addition

[0068] The effects of different straw addition ratios on arsenic removal from arsenic gypsum were investigated. Other steps and parameters were the same as those in Example 1. The experimental results are shown in Table 4.

[0069] Table 4 Arsenic content and occurrence forms in heavy metal adsorption materials (GBC) with different straw addition ratios

[0070]

[0071] The experimental results show that when straw is not added to participate in the thermal co-decomposition reaction, the proportion of the stable form of arsenic (residual state F4) in the heavy metal adsorption material is low (4-5%); when straw is added, the arsenic content in the heavy metal adsorption material decreases, and the proportion of the stable form of arsenic (residual state F4) gradually increases. When the ratio is 1:2, the proportion of the stable form of arsenic (residual state F4) in the heavy metal adsorption material is the highest (34-36%). This example shows that when the ratio of arsenic gypsum to straw reaches 1:2, the optimal arsenic removal effect can be achieved. However, the arsenic content of the heavy metal adsorption material in Examples 3-5 of the present invention is less than 1.67%, the residual arsenic content is greater than 20%, and the arsenic concentration leached from the heavy metal adsorption material is less than 5 mg / L, which meets the limit value (5 mg / L) of the "General Industrial Solid Waste Storage and Disposal Site Pollution Control Standard" (GB 18599-2020), and can achieve the purpose of the invention.

[0072] Examples 6-10 Experimental data of different pyrolysis temperatures

[0073] The effects of different pyrolysis temperatures on the heavy metal adsorption material were investigated. Other steps and parameters were the same as in Example 1. The experimental results are shown in Table 5.

[0074] Table 5 Arsenic content and occurrence forms in heavy metal adsorption materials (GBC) at different pyrolysis temperatures

[0075]

[0076] The experimental results show that the arsenic content in the heavy metal adsorption material gradually decreases with increasing pyrolysis temperature, while the stable form of arsenic (residual F4) in the heavy metal adsorption material increases with increasing pyrolysis temperature. When the pyrolysis temperature reaches 750°C, the proportion of the stable form of arsenic (residual F4) in the heavy metal adsorption material tends to stabilize. Furthermore, when the pyrolysis temperature is between 450°C and 850°C, the residual arsenic content is greater than 20%, and the arsenic concentration leached from the heavy metal adsorption material is less than 5 mg / L, meeting the limit of 5 mg / L in the "Pollution Control Standard for General Industrial Solid Waste Storage and Disposal Sites" (GB 18599-2020), thus achieving the objectives of the present invention.

[0077] Implementation Case 11-14 Experimental Data of Different Acids and Addition Amounts

[0078] The effects of different acids and different addition amounts on arsenic removal from arsenic gypsum were investigated. Other steps and parameters were the same as those in Example 1. The experimental results are shown in Table 6.

[0079] Table 6 Arsenic content and occurrence forms in heavy metal adsorption materials (GBC) with different acid addition amounts

[0080]

[0081] The experimental results show that the arsenic content in the heavy metal adsorption material gradually decreases with increasing acid addition, while the stable arsenic form (residual F4) in the heavy metal adsorption material increases with increasing acid addition. When the acid addition amount is greater than 0.4 mL / g (g is calculated as the mass of arsenic gypsum), the proportion of the stable arsenic form (residual F4) in the heavy metal adsorption material tends to stabilize. The optimal arsenic removal effect is achieved when the acid addition amount is 0.4 mL / g. However, the residual arsenic content of the heavy metal adsorption materials in Examples 12-14 of the present invention is all greater than 20%. The arsenic concentration leached from the heavy metal adsorption material is less than 5 mg / L, meeting the limit of 5 mg / L in the "Pollution Control Standard for General Industrial Solid Waste Storage and Disposal Sites" (GB 18599-2020), thus meeting the objectives of the present invention.

[0082] Examples 15-19 Experimental data of different pyrolysis times

[0083] The effects of different pyrolysis times on arsenic removal from arsenic gypsum were investigated. Other steps and parameters were the same as in Example 1. The experimental results are shown in Table 7.

[0084] Table 7 Arsenic content and occurrence forms in heavy metal adsorption materials (GBC) at different pyrolysis times

[0085]

[0086] The experimental results show that the arsenic content in the heavy metal adsorption material increases with pyrolysis time, while the stable form of arsenic (residual F4) in the heavy metal adsorption material increases with pyrolysis time. When the pyrolysis time is greater than 120 minutes, the value of the stable form of arsenic (residual F4) in the heavy metal adsorption material tends to stabilize with pyrolysis time. However, the arsenic content of the heavy metal adsorption materials in Examples 16-19 of the present invention is less than 2%, the residual arsenic content is greater than 20%, and the arsenic concentration leached from the heavy metal adsorption material is less than 5 mg / L, meeting the limit of 5 mg / L in the "Pollution Control Standard for General Industrial Solid Waste Storage and Disposal Sites" (GB 18599-2020), thus meeting the objectives of the present invention.

[0087] Example 20

[0088] Prepare a solution with an initial concentration of 20 mg / L (C0) of Pb(II) using 0.01 mol / L NaNO3 solution as the background electrolyte. Take 30.00 mL of the mother solution into a 50 mL polypropylene centrifuge tube and use microtiter method ( ) The pH of the water was gradually adjusted to 4.0; 0.003 g of GBC adsorbent was quantitatively added (taking the dosage of 1 g / L as an example). After the reaction was completed and high-speed centrifugation was performed (3000 rpm, 20 min), the supernatant was filtered through a 0.45 μm microporous filter membrane, and the residual Pb(Ⅱ) concentration in the liquid phase was determined by ICP-OES to be 0.078 mg / L (C e GBC achieves physical adsorption by virtue of its developed pore structure. Elements such as S and F form precipitation with Pb(II), and Mg 2+ , Ca 2+ It undergoes cation exchange with Pb (II), and oxygen-containing functional groups such as -OH and C=O on the surface complex with Pb (II). Multiple mechanisms synergistically remove Pb (II) efficiently, reaching adsorption equilibrium within 1 hour and a removal rate of over 99%.

[0089] In the adsorption experiment, the removal rate η (%) and adsorption amount Qe (mg / g) of heavy metal adsorption material (GBC) for Pb(Ⅱ) were calculated according to the following formulas (1) and (2):

[0090]

[0091] Where: η: removal rate of Pb(Ⅱ),%;

[0092] C0: initial Pb(Ⅱ) concentration of the solution, mg / L;

[0093] C e : Pb(Ⅱ) concentration at adsorption equilibrium, mg / L.

[0094] At this time, the removal rate of Pb(Ⅱ) by GBC

[0095]

[0096] Where: Q e : adsorption capacity of the adsorbent for Pb(Ⅱ) at adsorption equilibrium, mg / g;

[0097] C0: initial Pb(Ⅱ) concentration of the solution, mg / L;

[0098] C e : Pb(Ⅱ) concentration at adsorption equilibrium, mg / L;

[0099] m: mass of adsorbent, g;

[0100] V: solution volume, L.

[0101] At this time, the adsorption capacity of GBC for Pb(Ⅱ)

[0102] Case Study 21-25 Experimental Results of Pb(II) Removal by Heavy Metal Adsorption Material (GBC) under Different pH Conditions

[0103] The heavy metal (GBC) adsorption material prepared under the conditions of Example 1 was selected for the experiment. At the same time, a solution with an initial concentration of Pb(II) C0 = 20 mg / L was prepared, and a 0.01 mol / L NaNO3 solution was used as the background electrolyte. 30 mL of the mother solution was transferred to a 50 mL polypropylene centrifuge tube and a precision pH meter was used to measure the concentration by microtiter ( The reaction mixture was then gradually adjusted to the target pH (3.0 ± 0.1 to 7.0 ± 0.1). 0.003 g of GBC adsorbent was added quantitatively. After completion of the reaction, the supernatant was centrifuged at high speed (3000 rpm for 20 minutes), and filtered through a 0.45 μm microporous membrane. The residual Pb(II) concentration in the liquid phase was determined by ICP-OES. The results are shown in Table 8.

[0104] Table 8 Pb(II) removal effect of heavy metal adsorption material (GBC) under different pH conditions

[0105]

[0106] As shown in the experimental results in Table 6, when the pH of the water body is in the range of 3-7, the heavy metal adsorption material (GBC) has a comparable removal effect on Pb (II) in the water body, indicating that the heavy metal adsorption material (GBC) provided by the present invention has a wide pH adaptability (3.0-7.0) and can cover the common acidic and alkaline environments of natural water bodies and industrial wastewater, and has broad applicability.

[0107] Examples 26-33 Adsorption Effects of Heavy Metal Adsorbents at Different Initial Pb(II) Concentrations

[0108] The heavy metal adsorbent prepared in Example 1 was selected and Pb 2+ The initial concentrations of the experimental solutions were 10, 20, 40, 80, 100, 200, and 300 mg / L, respectively, and the background electrolyte was 0.01 mol / L NaNO3 solution. 30 mL of the mother solution was transferred to a 50 mL polypropylene centrifuge tube and titrated by microtiter ( ) The pH was gradually adjusted to 4.0; 0.003 g of GBC adsorbent was quantitatively added. After the reaction was completed and high-speed centrifugation (3000 rpm, 20 min), the supernatant was filtered through a 0.45 μm microporous filter membrane, and the residual Pb(Ⅱ) concentration in the liquid phase was determined by ICP-OES. The experimental results are shown in Table 9.

[0109] Table 9 Pb(II) removal effect of heavy metal adsorbent (GBC) under different initial Pb(II) concentration conditions

[0110]

[0111] The present invention simultaneously disposes of arsenic gypsum hazardous waste and corn straw agricultural waste through co-pyrolysis treatment, thus achieving "waste treatment with waste". Under the conditions of a straw addition ratio of 1:2, a sulfuric acid addition amount of 0.4 mL / g, a pyrolysis temperature of 750°C, and a pyrolysis time of 120 min, the arsenic content in arsenic gypsum dropped from 6.11% to below 0.63%, and the arsenic leaching concentration was ≤0.5 mg / L, meeting the "General Solid Waste Landfill Pollution Control Standard" (GB 18599-2020). The ecological risk was reduced from the high risk (HR) of the original arsenic gypsum to the low risk level (LR), completely solving the environmental pollution hazards of long-term storage of arsenic gypsum; the prepared GBC had a maximum adsorption capacity of Pb(II) of 339.97 mg / g, which was nearly 9.7 times higher than that of the original corn straw biochar (BC, about 35 mg / g), and showed good performance in the pH range of 3.0-7.0. Adsorption equilibrium can be reached in 1 hour, which is far superior to traditional adsorption materials (such as activated carbon), achieving the dual benefits of solid waste resource utilization and water pollution remediation.

[0112] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any form. Therefore, any simple modifications, equivalent variations, and modifications to the above embodiments that do not depart from the technical solution of the present invention and are based on the technical essence of the present invention shall fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing a heavy metal adsorption material, characterized in that: The following steps are involved: A. collecting arsenic gypsum and straw, drying and grinding them respectively, and then mixing them to obtain a first mixture; B. adding an inorganic acid to the first mixture and stirring the mixture thoroughly with a stirring device to obtain a second mixture; C. Add the second mixture into a high-temperature atmosphere furnace, and under the protection of inert gas, raise the temperature to 450°C-850°C, and pyrolyze at a constant temperature for 120 min-300 min; D. After the co-pyrolysis is completed, the system is cooled to below 80°C to obtain the heavy metal adsorption material; The inorganic acid in step B includes at least one of sulfuric acid, hydrochloric acid, and nitric acid; The main elements in the arsenic gypsum include Ca, S, and F.

2. The preparation method according to claim 1, characterized in that In step (A), the arsenic gypsum is dried at a temperature of 105-110° C. for 2-3 hours and passed through an 80-100 mesh sieve; the straw is dried at a temperature of 60-80° C. for 12-24 hours and passed through a 40-60 mesh sieve.

3. The preparation method according to claim 1, characterized in that The mass ratio of the mixture of arsenic gypsum and straw in step (A) is 1: (1-4).

4. The preparation method according to claim 1, characterized in that The straw includes at least one of corn straw, wheat straw, rice straw, sorghum straw and other crop straws.

5. The preparation method according to claim 1, characterized in that In step (B), the amount of the inorganic acid added is 0.2 mL / g-0.8 mL / g.

6. A heavy metal adsorption material, characterized in that: The method is obtained by the preparation method described in any one of claims 1 to 5.

7. The heavy metal adsorption material according to claim 6, characterized in that The pH applicable range of the heavy metal adsorption material is 3-7.

8. The heavy metal adsorption material according to claim 6, characterized in that The adsorption capacity of the heavy metal adsorption material is 35 mg / g to 380 mg / g, the arsenic content is lower than 0-2 wt%, and the arsenic leaching concentration is 0-0.5 mg / L.

9. The heavy metal adsorption material according to claim 6, characterized in that: The heavy metal is lead.

10. Use of a heavy metal adsorption material as a heavy metal adsorbent, characterized in that: The invention comprises a heavy metal adsorption material prepared by the preparation method according to any one of claims 1 to 5 or a heavy metal adsorption material according to any one of claims 6 to 9.

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