Heavy metal adsorbent material as well as preparation method and application thereof

Abstract

The invention discloses a heavy metal adsorbent material as well as a preparation method and application thereof, and belongs to the technical field of adsorption materials. The heavy metal adsorbent material comprises the following components in percentage by mass: 10-35% of metal salt, 1-80% of a porous oxide raw material, 0.001-5% of a flocculating agent and 5-65% of an auxiliary material, and is composed of a porous oxide with metal salt deposited in pore channels and a flocculation network coated outside the porous oxide, the auxiliary materials are deposited on the surface and in the pore channels of the heavy metal adsorbent material. According to the adsorbent, in wastewater containing heavy metal ions, stable precipitates are generated through the reaction of anions released by metal salt ionization in pore channels and heavy metal cations in the wastewater, so that the heavy metal ions in the wastewater are efficiently removed. The heavy metal adsorbent material provided by the invention is simple in preparation process, low in cost, non-toxic, environment-friendly, large in adsorption capacity, convenient to recycle and suitable for heavy metal wastewater treatment under different pH conditions, and the heavy metal removal rate can reach 90% or above.

Description

Technical Field

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

[0002] Industries such as battery manufacturing, metal smelting, electroplating, petrochemicals, and glass manufacturing generate large quantities of heavy metal wastewater during their production processes. Heavy metal pollutants are bioaccumulative and difficult to degrade, resulting in irreversible impacts on human health, ecosystems, soil, and crops. For example, accumulation of lead ions in the human body can lead to anemia, impair blood synthesis, and long-term exposure can even cause renal failure. Heavy metal cadmium in water can disrupt fish metabolism and affect their growth and development. Heavy metals in wastewater entering the soil can affect microbial diversity, biomass, and metabolic function. Chromium contamination can inhibit bacterial and fungal growth in the soil and reduce soil enzyme activity, thereby impacting soil ecological functions. Therefore, removing heavy metals from wastewater is crucial for both humans and the environment. Currently, commonly used heavy metal wastewater treatment technologies include chemical precipitation, ion exchange, adsorption, electrolysis, membrane separation, and coagulation and flocculation, but these have inherent limitations. Compared to other treatment technologies, adsorption offers advantages such as simplicity, high efficacy, and wide applicability, making it one of the primary methods for removing heavy metals from water. Patent CN115722206B discloses a composite adsorbent for lead adsorption, as well as its preparation and adsorption methods. The inventors first used zirconium chloride, 2,5-dihydroxyterephthalic acid, and hydrochloric acid as raw materials, reacting them in an autoclave in an 80° oven for 24 hours to obtain UIO-66-(OH)2. UIO-66-(OH)2 and sodium alginate were then mixed to obtain Solution A. Calcium chloride was dissolved in water to prepare Solution B, which was then poured into Solution A and allowed to solidify for one hour to obtain a calcium alginate / UIO-66-(OH)2 composite gel. This composite gel effectively adsorbs lead ions from water. However, the preparation of the adsorbent material described in this patent is cumbersome, the synthesis time is long, the raw materials are expensive, and the adsorption time for lead ions in water is long, making it unsuitable for industrial application. Summary of the Invention

[0003] In view of the defects in the prior art, the present invention provides a heavy metal adsorbent material and a preparation method and application thereof.

[0004] To achieve the above-mentioned purpose of the invention, after research, this application provides the following technical solutions:

[0005] The first aspect of the present application provides a heavy metal adsorbent material, which comprises the following raw materials by total mass:

[0006] 10-35wt% metal salt, 1-80wt% porous oxide raw material, 0.001-5wt% flocculant and 5-65wt% auxiliary material;

[0007] The heavy metal adsorbent material is composed of a porous oxide with metal salts deposited in the pores and a flocculation network coated on the porous oxide. The auxiliary material is deposited on the surface and in the pores of the heavy metal adsorbent material.

[0008] In some embodiments, the metal salt includes one or more of metal chloride, metal bromide, metal iodide, metal sulfide, metal sulfate, metal nitrate, metal carbonate, metal phosphate, and metal chromate;

[0009] and / or; the porous oxide raw material is selected from one or more of tetramethyl silicate, tetraethyl silicate, 3-aminopropyltriethoxysilane, tetrapropyl titanate and tetrabutyl titanate;

[0010] and / or; the flocculant is selected from any one of potassium aluminum sulfate dodecahydrate (alum), ferric chloride, ferrous sulfate, polyferric sulfate, polyaluminum chloride, polyferric sulfate, polyacrylamide chitosan, sodium alginate, guar gum, polyethyleneimine, sodium polystyrene sulfonate, and sodium polyacrylate;

[0011] And / or, the excipients include one or more of potassium aluminum sulfate dodecahydrate (alum), ferric chloride, ferrous sulfate, polyferric sulfate, polyaluminum chloride, polyferric sulfate, polyacrylamide chitosan, sodium alginate, guar gum, polyethyleneimine, sodium polystyrene sulfonate, sodium polyacrylate, aluminum oxide, zinc oxide, boron trioxide, calcium oxide, sodium oxide, potassium oxide, and barium oxide.

[0012] In some embodiments, the excipients include excipients a and b; wherein, excipient a is selected from one or more of aluminum oxide, zinc oxide, boron trioxide, calcium oxide, sodium oxide, potassium oxide, and barium oxide; excipient b is selected from one or more of potassium aluminum sulfate dodecahydrate (alum), ferric chloride, ferrous sulfate, polyferric sulfate, polyaluminum chloride, polyferric sulfate, polyacrylamide chitosan, sodium alginate, guar gum, polyethyleneimine, sodium polystyrene sulfonate, and sodium polyacrylate.

[0013] In some embodiments, the heavy metal adsorbent material is used to remove heavy metal ions from wastewater containing heavy metal ions;

[0014] When the pH value of the wastewater containing heavy metal ions is less than 7, add auxiliary material a and then add auxiliary material b;

[0015] When the pH value of the wastewater containing heavy metal ions is greater than or equal to 7, auxiliary material a is not added and auxiliary material b is directly added.

[0016] In some embodiments, the heavy metal adsorbent material comprises the following raw materials, based on total weight: 10-25 wt% metal salt, 30-75 wt% porous oxide raw material, 0.001-5 wt% flocculant, 0-50 wt% auxiliary material a, and 5-15 wt% auxiliary material b. The heavy metal adsorbent material is suitable for treating heavy metal ion-containing wastewater with a pH value less than 7.

[0017] In some preferred embodiments, the heavy metal adsorbent material comprises the following raw materials, based on total weight: 10-22 wt% metal salt, 32-60 wt% porous oxide raw material, 0.001-3 wt% flocculant, 20-32 wt% auxiliary material a, and 5-15 wt% auxiliary material b. The heavy metal adsorbent material is suitable for use in heavy metal ion-containing wastewater with a pH value less than 7.

[0018] In some preferred embodiments, the heavy metal adsorbent material comprises the following raw materials by total mass: 10-35wt% metal salt, 1-80wt% porous oxide raw material, 0.001-5wt% flocculant and 5-65wt% auxiliary material b; the heavy metal adsorbent material is suitable for heavy metal ion-containing wastewater with a pH ≥ 7.

[0019] Preferably, the heavy metal adsorbent material comprises the following raw materials by total mass: 10-30 wt% metal salt, 30-75 wt% porous oxide raw material, 0.001-3 wt% flocculant and 5-50 wt% auxiliary material B. The heavy metal adsorbent material is suitable for heavy metal ion-containing wastewater with a pH of ≥7.

[0020] In some embodiments, the heavy metal adsorbent material is obtained by mixing a 0.1-10 mol / L metal salt solution obtained by dissolving a metal salt in water with a porous oxide raw material and a flocculant, and performing hydrolysis and flocculation reactions to obtain a mixture. The mixture is mixed with auxiliary materials and stirred evenly, and then heated at 30-500°C for 10-600 minutes.

[0021] In some embodiments, the reaction conditions of the hydrolysis and flocculation reaction include: reaction temperature of 0-100° C., stirring speed of 50-500 rpm, and reaction time of 1-600 min.

[0022] In some embodiments, the heating treatment conditions include: a heating temperature of 150-250° C. and a heating time of 60-180 min.

[0023] The second aspect of the present application provides a method for preparing the heavy metal adsorbent material, the preparation method comprising the following steps:

[0024] S1: Weigh the raw materials according to any of the above items;

[0025] S2: adding a metal salt to water and stirring until fully dissolved to obtain a metal salt solution with a concentration of 0.1 to 10 mol / L;

[0026] S3: adding a porous oxide raw material and a flocculant to the metal salt solution, stirring at 0-100° C. and 50-500 rpm for 1-600 min to perform hydrolysis and flocculation reactions, to obtain a mixture consisting of a porous oxide with metal salt deposited in the pores and a flocculation network coated on the outside of the porous oxide;

[0027] S4: adding auxiliary materials to the mixture obtained in step S3, mixing and stirring uniformly to obtain a multilayer network-coated mixture containing metal salts;

[0028] S5: The mixture obtained in step S4 is heated at 30-500° C. for 10-600 min, and then ground evenly to obtain a heavy metal adsorbent material.

[0029] In some embodiments, in step S3, the mixture is stirred at 20-50° C. and a rotation speed of 100-500 rpm for 1-60 min; and / or, in step S5, the mixture is heated at 150-250° C. for 60-180 min.

[0030] The third aspect of the present application provides use of the heavy metal adsorbent material in the treatment of wastewater containing heavy metal ions, wherein the pH value of the wastewater containing heavy metal ions is in the range of 1-10.

[0031] The fourth aspect of the present application provides a method for treating wastewater containing heavy metal ions, and the specific steps of the treatment method include: adding the heavy metal adsorbent material described in any one of the above items into the wastewater containing heavy metal ions, and adding a flocculant to collect the heavy metal adsorbent material after a period of reaction.

[0032] In some embodiments, the heavy metal adsorbent material is added in a mass ratio of 1:(800-1500) to the wastewater containing heavy metal ions.

[0033] Wherein, the heavy metal ions in the wastewater are selected from Pb 2+ 、Hg 2+ 、Cu 2+ 、Zn 2+ 、Ni 2+ 、As 3+ 、As 5+ 、Mn 2+ 、Fe 2 + 、Fe 3+ One or more of the above, with a concentration range of 10-150 mg / L (i.e. 10-150 ppm).

[0034] The beneficial effects of this application include at least:

[0035] (1) The present invention deposits metal salts inside a porous oxide, adds auxiliary materials for multi-layer coating, and then dries the resulting adsorbent material. This preparation method has few steps, simple operation, and low cost.

[0036] (2) When removing heavy metals from wastewater, it is only necessary to put the adsorbent into the wastewater and then add the flocculant after a period of time (such as 30 minutes in the embodiment) to collect the wastewater. The operation time is short, no odor is generated during the adsorption process, the operation is simple, and the recovery is convenient.

[0037] (3) The adsorbent of the present application is non-toxic itself. During use, heavy metal ions form stable compounds with anions dissociated from the metal salt inside the adsorbent, which confines the heavy metal ions to be removed inside the adsorbent and prevents them from entering the water body again, thus preventing secondary pollution.

[0038] (4) The adsorbent of the present application has a high adsorption capacity, the mass ratio of the adsorbent to the wastewater is 1:(800-1500), the heavy metal removal effect is good, and the removal rate is as high as over 90%.

[0039] (5) The maximum adsorption capacity of the adsorbent of this application is that each kilogram of adsorbent can treat 2 tons of wastewater with a lead ion concentration of 100 ppm, and the residual lead ion content in the treated solution is less than 10 ppm. This adsorption effect is 3-5 times that of commonly used activated carbon adsorbents. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a physical picture of the heavy metal adsorbent in Example 1.

[0041] Figure 2 This is a scanning electron microscope (SEM) image of the heavy metal adsorbent of Example 1.

[0042] Figure 3 This is a transmission electron microscope (TEM) image of the heavy metal adsorbent of Example 1. Figure 3 The black particles in area A are the effective components inside the adsorbent; area B is the protective layer material.

[0043] Figure 4 This is a photo of the heavy metal adsorbent used in Example 1 to treat lead and arsenic wastewater. The test strip pointed to by B shows the concentration of lead ions in the wastewater before treatment (100 ppm), and the test strip pointed to by A shows the concentration of lead ions in the wastewater after treatment (0 ppm).

[0044] Figure 5 Photograph of heavy metal adsorbent collected for adding flocculant to treated wastewater.

[0045] Figure 6 This is a photo of the heavy metal adsorbent of Comparative Example 1; Figure 6 A is a photo of the heavy metal adsorbent sample of Comparative Example 1 prepared without adding auxiliary materials. Figure 6 B is a photo of the water sample after the wastewater was treated with the adsorbent.

[0046] Figure 7 This is a photo of the heavy metal adsorbent of Comparative Example 2, where Figure 7 A is a photo of the heavy metal adsorbent of Comparative Example 2 with 0g of calcium oxide added; Figure 7 B is a photo of the adsorbent treating lead ion wastewater, and C points to the test paper results of the lead ion wastewater after treatment using the lead ion detection paper.

[0047] Figure 8 This is the result of treating lead and arsenic wastewater with the heavy metal adsorbent prepared in Example 13. DETAILED DESCRIPTION

[0048] The preferred embodiments of the present invention will be described in detail below with reference to the examples. It should be understood that the following examples are provided for illustrative purposes only and are not intended to limit the scope of the present invention. Those skilled in the art may make various modifications and substitutions to the present invention without departing from the purpose and spirit of the present invention.

[0049] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods. Unless otherwise specified, the materials, reagents, etc. used in the following examples are all commercially available or prepared according to conventional methods in the art.

[0050] In the prior art, heavy metal adsorbents that are inherently highly toxic or release pungent odors during use can not only cause secondary pollution to the environment but also increase safety risks associated with material use and disposal. To avoid these issues, the raw materials used in this application are less toxic, and the adsorbents do not release toxic or odorous gases during use. The used adsorbents are also easily recyclable, resulting in excellent environmental friendliness.

[0051] The method of the present application uses the porous oxide and flocculation network formed by hydrolysis as the adsorbent carrier, loads the metal salt inside the carrier and further fixes the metal salt by adding auxiliary materials to prepare a heavy metal adsorbent material with a high adsorption capacity. Among them, the metal salt is loaded in the pores (mesopores) of the porous oxide, and the porous oxide and the flocculation network form a multiple network to coat it, while the auxiliary materials further close the pores of the porous oxide. The heavy metal adsorbent material prepared in Example 1 of the present application has a particle size of about 75um, an average pore size of 4.0nm, and a specific surface area of ​​102.5m 2 / g, total pore volume 0.259cm 3 / g.

[0052] During use, the adsorbent is directly added to heavy metal-rich wastewater. The adsorbent's dissociation of anions upon contact with water spontaneously reacts with the heavy metal ions in the wastewater, trapping the heavy metal ions within the adsorbent. The growing precipitate is restricted in its movement by the pores, while the auxiliary materials and flocculation network further hinder the heavy metal ions from returning to the water, ultimately removing the heavy metal ions from the wastewater. Once the adsorbent reaches saturation, the product can be collected by adding a flocculant.

[0053] The present application provides a heavy metal adsorbent material, which comprises the following raw materials by total mass:

[0054] 10-35wt% metal salt, 1-80wt% porous oxide raw material, 0.001-5wt% flocculant and 5-65wt% auxiliary material,

[0055] The heavy metal adsorbent material is composed of a porous oxide with metal salts deposited in the pores and a flocculation network coated on the porous oxide. The auxiliary material is deposited on the surface and in the pores of the heavy metal adsorbent material.

[0056] In some embodiments, the metal salt includes one or more of metal chloride, metal bromide, metal iodide, metal sulfide, metal sulfate, metal nitrate, metal carbonate, metal phosphate, and metal chromate. The metal element includes sodium Na, potassium K, calcium Ca, iron Fe, etc.

[0057] The present application uses metal salts because metal salts produce anions after dissolution, and the anions can produce strong electrostatic interactions with heavy metal cations in wastewater. In subsequent steps, the heavy metal ions enter the mesoporous channels of the adsorbent and react with the anions to form precipitates. The heavy metal ions are confined in the pores of the adsorbent, thereby achieving the purpose of removing heavy metal ions from water.

[0058] Preferably, the metal salt is one or more of metal iodide, metal sulfide, metal sulfate, metal carbonate, metal phosphate, and metal chromate.

[0059] More preferably, the metal salt is a metal sulfide, including at least one of Na2S, K2S, thiourea (CH4N2S), and NH4S.

[0060] Although metal chloride is an option, its effect is inferior to that of metal sulfide. When its corresponding heavy metal adsorbent material is used for wastewater treatment, the lead chloride formed by chloride ions and heavy metal lead ions is slightly soluble in water, which will weaken its adsorption and removal of lead ions. However, the reaction between sulfur ions and lead ions is very active. The solubility of the formed product, lead sulfide, is 6.767×10 per 100mL of water at 20℃. -13 g, is almost insoluble in water and has high stability, so the heavy metal adsorbent material prepared from metal sulfide has a good effect in removing lead ions from wastewater. Other anions, such as iodide ions, also react actively with lead ions, but the solubility of the resulting lead iodide under the same conditions is about 4.4×10 -2 g, although it is relatively low, there is still a very small amount of dissolution, and its stability is not as stable as that of lead sulfide formed by sulfide ions.

[0061] In some embodiments, the porous oxide raw material is selected from one or more of tetramethyl silicate, tetraethyl silicate, 3-aminopropyltriethoxysilane, tetrapropyl titanate, and tetrabutyl titanate. The porous oxide raw material is hydrolyzed to form a porous oxide. The porous oxide not only supports the metal salt, but also provides an environment for the reaction between heavy metal ions and anions in the wastewater to be tested, and confines the formed precipitate within the pores, thereby achieving the purpose of removing heavy metal ions from the water.

[0062] In some embodiments, the flocculant is selected from any one of alum, ferric chloride, ferrous sulfate, polyferric sulfate, polyaluminum chloride, polyferric sulfate, polyacrylamide chitosan, sodium alginate, guar gum, polyethyleneimine, sodium polystyrene sulfonate, and sodium polyacrylate. The addition of the flocculant can effectively prevent leakage of components in the pores and facilitate the removal of heavy metal ions in the wastewater to be tested.

[0063] If no flocculant is added and only the porous oxide generated by hydrolysis is relied upon to load the metal salt, although the metal salt can be loaded into the pores, after the adsorbent is added to the water, the metal salt is easily dissolved and released into the water body, making it difficult for the heavy metal ions to be stably confined in the pores, thereby affecting the adsorption effect. Therefore, the present application introduces a flocculant into the system to form a dense coating network during the heating process. It ensures that heavy metal ions are allowed to pass through the network into the pores to react with anions to form precipitates, and that the leakage of heavy metal ions in the pores is prevented, thereby achieving effective capture and restriction of heavy metal ions in water.

[0064] In some embodiments, the excipients include one or more of alum, ferric chloride, ferrous sulfate, polyferric sulfate, polyaluminum chloride, polyferric sulfate, polyacrylamide chitosan, sodium alginate, guar gum, polyethyleneimine, sodium polystyrene sulfonate, sodium polyacrylate, aluminum oxide, zinc oxide, boron trioxide, calcium oxide, sodium oxide, potassium oxide, and barium oxide.

[0065] In some preferred embodiments, the auxiliary materials include auxiliary materials a and b. The auxiliary material a is selected from one or more of aluminum oxide, zinc oxide, boron trioxide, calcium oxide, sodium oxide, potassium oxide, and barium oxide; and the auxiliary material b is selected from one or more of alum, ferric chloride, ferrous sulfate, polyferric sulfate, polyaluminum chloride, polyferric sulfate, polyacrylamide chitosan, sodium alginate, guar gum, polyethyleneimine, sodium polystyrene sulfonate, and sodium polyacrylate.

[0066] The content of auxiliary material A is adjusted according to the pH value of the water, aiming to tailor the adsorbent to the specific requirements of different wastewaters. The addition of auxiliary material B prevents metal salts from leaking from the porous oxide pores into the water, and also prevents the precipitate of auxiliary material A from leaking into the water. The content of auxiliary material B can be adjusted based on the amount of metal salt loading.

[0067] The addition of auxiliary material a is optional and should be determined based on the pH of the wastewater being treated. For example, when the wastewater pH is 6, auxiliary material a should be added first to adjust the adsorbent's performance and better adapt it to the treatment requirements of different wastewater types. Then, auxiliary material b should be added to form a stable multilayer network coating structure. When the wastewater pH is 7, auxiliary material a can be omitted and auxiliary material b can be used directly.

[0068] In some preferred embodiments, the heavy metal adsorbent material comprises the following raw materials by total mass:

[0069] 10-25wt% of metal salt, 30-75wt% of porous oxide raw material, 0.001-5wt% of flocculant, 0-50wt% of auxiliary material a and 5-15wt% of auxiliary material b.

[0070] In some embodiments, the heavy metal adsorbent material is obtained by mixing a 0.1-10 mol / L metal salt solution obtained by dissolving a metal salt in water with a porous oxide raw material and a flocculant, and performing hydrolysis and flocculation reactions to obtain a mixture, mixing the mixture with auxiliary materials, stirring evenly, and heating the mixture.

[0071] In some embodiments, the hydrolysis and flocculation reaction conditions include: a reaction temperature of 0-100°C, a stirring speed of 50-500 rpm, and a reaction time of 1-600 min. Preferably, the reaction temperature is 20-50°C, the stirring speed is 100-500 rpm, and the reaction time is 1-60 min. More preferably, the hydrolysis and flocculation reactions are carried out at room temperature.

[0072] In some embodiments, the heating treatment conditions include: a heating temperature of 30-500° C. and a heating time of 10-600 min; preferably, the heating temperature is 150-250° C. and the heating time is 60-180 min.

[0073] A method for preparing the heavy metal adsorbent material as described above, the preparation method comprising the following steps:

[0074] S1: Weigh the raw materials according to any of the above items;

[0075] S2: adding a metal salt to water and stirring until fully dissolved to obtain a metal salt solution with a concentration of 0.1 to 10 mol / L;

[0076] S3: adding a porous oxide raw material and a flocculant to the metal salt solution, stirring at 0-100° C. and 50-500 rpm for 1-600 min to perform hydrolysis and flocculation reactions, to obtain a mixture consisting of a porous oxide with metal salt deposited in the pores and a flocculation network coated on the outside of the porous oxide;

[0077] S4: adding auxiliary materials to the mixture obtained in step S3, mixing and stirring uniformly to obtain a multilayer network-coated mixture containing metal salts;

[0078] S5: The mixture obtained in step S4 is heated at 30-500° C. for 10-600 min, and then ground evenly to obtain a heavy metal adsorbent material.

[0079] In some embodiments, the hydrolysis and flocculation reaction is carried out by stirring at 20-50° C. and a rotation speed of 100-500 rpm for 1-60 min in step S3; and / or, the mixture is heated at 50-200° C. for 30-180 min in step S5.

[0080] The use of any of the above-mentioned heavy metal adsorbent materials, or the heavy metal adsorbent material obtained by the above-mentioned preparation method, in the treatment of heavy metal-containing wastewater, wherein the pH value of the heavy metal-containing wastewater is in the range of 1-10.

[0081] A method for treating heavy metal-containing wastewater comprises the following specific steps: adding any of the above-mentioned heavy metal adsorbent materials into the wastewater containing heavy metal ions, adding a flocculant after a period of reaction, and collecting the heavy metal adsorbent material.

[0082] In some embodiments, the flocculant is selected from one or more of alum, ferric chloride, ferrous sulfate, polyferric sulfate, polyaluminum chloride, polyferric sulfate, polyacrylamide chitosan, sodium alginate, guar gum, polyethyleneimine, sodium polystyrene sulfonate, and sodium polyacrylate.

[0083] In some embodiments, the heavy metal adsorbent material is added in a mass ratio of 1:(800-1500) to the wastewater containing heavy metal ions.

[0084] In some embodiments, the heavy metal ions in the heavy metal ion-containing wastewater include Pb 2+ , Hg 2+ , Cu 2+ , Zn 2+ , Ni 2+ , As 3+ , As 5+ , Mn 2+ , Fe 2+ , Fe 3+ One or more of .

[0085] The present invention is further described below with reference to specific examples. These examples are based on the technical solutions of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of the present invention is not limited to the following examples. During the implementation of the present invention, the focus is on achieving efficient adsorption of mercury, lead, copper, cadmium, arsenic, and the like.

[0086] Tetramethyl silicate (TMOS) in the examples is also called methyl orthosilicate.

[0087] Example 1

[0088] Step (1): Add 25 g of Na2S to 250 ml of water and stir at 500 rpm for 10 minutes at room temperature (about 25°C) until it is completely dissolved.

[0089] Step (2): 75 ml (about 77 g) of methyl orthosilicate (TMOS) and 100 ml of a 0.2 g / L polyacrylamide solution were added to the solution simultaneously, and stirred for 10 minutes to obtain a uniform mixture of porous silica loaded with metal salts and a flocculated network. The metal salts were deposited in the pores of the porous silica, and the porous silica was further coated by the flocculated network.

[0090] Step (3): Transfer all the mixture obtained in step (2) into a container and add 50g of calcium oxide and stir for 10 minutes, then add 20g of polyaluminium chloride and continue stirring for 10 minutes.

[0091] Step (4): The solid mixture obtained in step (3) is placed in a high-temperature resistant quartz glass tray and heated in a muffle furnace at 200°C for 2 hours. The mixture is ground evenly to obtain a heavy metal adsorbent material in which the metal salt is deposited in the pores and is coated by the porous oxide and flocculation network. See the actual picture of the heavy metal adsorbent material. Figure 1 .

[0092] In Example 1, because the hydrolysis reaction of step (2) is slightly faster, the product obtained is silica coated with a flocculation network, and the interior of the hydrolyzed silica contains metal salts. Because dehydration treatment has not been carried out at this time, the pores of the silica are initially formed, and mesopores will be formed in the subsequent heating and dehydration stage, and the metal salts will be deposited in the mesopores. The flocculation network and porous silica are physical coating forms. In step (3), the auxiliary material a, calcium oxide, reacts with the water in the mixture to obtain calcium hydroxide, which can play a role in regulating the pH of the wastewater to be treated and also partially plays a role in sealing the pores. The auxiliary material b, polyaluminum chloride, reacts with the remaining water in the mixture to further coat the above product. In the later heating and dehydration step, the auxiliary material b forms a further package on the surface of the adsorbent and inside the pores, which plays a role in sealing the pores and the auxiliary material A. Therefore, the auxiliary materials a and b play a role in sealing the pores together.

[0093] Example 2

[0094] The difference from Example 1 is that in step (1), 35 g of K2S is added to 250 ml of water and stirred at 500 rpm until completely dissolved.

[0095] The other steps are the same as those in Example 1.

[0096] Example 3

[0097] The difference from Example 1 is that in step (1), 24 g of thiourea was added to 250 ml of water and stirred at 500 rpm until all the thiourea was dissolved.

[0098] The other steps are the same as those in Example 1.

[0099] Example 4

[0100] The difference from Example 1 is that in step (1), 22 g of NH4S was added to 250 ml of water and stirred at 500 rpm until it was completely dissolved.

[0101] The other steps are the same as those in Example 1.

[0102] Example 5

[0103] The difference from Example 1 is that in step (2), 75 ml of methyl orthosilicate and 0.5 g of aluminum sulfate are added to the solution at the same time, and after stirring for 10 minutes, a uniform mixture consisting of porous silica loaded with metal salts and a flocculated network coating the porous silica is obtained.

[0104] The other steps are the same as those in Example 1.

[0105] Example 6

[0106] The difference from Example 1 is that in step (2), 75 ml of methyl orthosilicate and 0.5 g of alum are added to the solution at the same time, and after stirring for 10 minutes, a uniform mixture of metal salt-loaded silica and flocculation network is obtained.

[0107] The other steps are the same as those in Example 1.

[0108] Example 7

[0109] The difference from Example 1 is that in step (2), 75 ml of methyl orthosilicate and 0.5 g of polyaluminum chloride are added to the solution at the same time, and after stirring for 10 minutes, a uniform mixture of metal salt-loaded silica and flocculation network is obtained.

[0110] The other steps are the same as those in Example 1.

[0111] Example 8

[0112] The difference from Example 1 is that in step (2), 75 ml of methyl orthosilicate and 0.5 g of starch are added to the solution at the same time, and after stirring for 10 minutes, a uniform mixture of metal salt-loaded silica and flocculation network is obtained.

[0113] The other steps are the same as those in Example 1.

[0114] Example 9

[0115] The difference from Example 1 is that 25 g of calcium oxide is added to the mixture prepared in step (3) and stirred for 10 minutes, and then 20 g of polyaluminum chloride is added and stirred for another 10 minutes.

[0116] The other steps are the same as those in Example 1.

[0117] Example 10

[0118] The difference from Example 1 is that 75 g of calcium oxide was added to the mixture obtained in step (3) and stirred for 10 minutes, and then 20 g of starch was added and stirred for another 10 minutes.

[0119] The other steps are the same as those in Example 1.

[0120] Example 11

[0121] The difference from Example 1 is that in step (4), all the solids in the container are placed in a glass tray and heated in a muffle furnace at 100° C. for 2 hours.

[0122] The other steps are the same as those in Example 1.

[0123] Example 12

[0124] The difference from Example 1 is that in step (4), all the solids in the container are placed in a glass tray and heated in a muffle furnace at 300° C. for 2 hours.

[0125] The other steps are the same as those in Example 1.

[0126] Example 13

[0127] The difference from Example 1 is that 25 g of NH 4 I is added in step (1).

[0128] The other steps are the same as those in Example 1.

[0129] Test Example 1

[0130] In order to verify the structural characteristics of the heavy metal adsorbent prepared in this application, the heavy metal adsorbent prepared in Example 1 was taken as an example, and its microscopic morphology was analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Figure 2 and Figure 3 shown.

[0131] Figure 2 This is the SEM image of the adsorbent, in which the round spherical particles are larger adsorbents, and the other small particles are smaller adsorbents. There is a flocculation network protective layer on the surface of the adsorbent.

[0132] Figure 3 This is a TEM image of the adsorbent. The black particles in region A represent metal salts deposited within the pores; region B represents the porous oxide loaded with the metal salts. The structure demonstrates that the metal salts are effectively embedded within the nanopores of the porous oxide, without significant aggregation or overflow, demonstrating excellent loading uniformity and spatial confinement.

[0133] The BET test results of the adsorbent showed that the average pore size of the heavy metal adsorbent material in Example 1 was 4.0 nm and the specific surface area was 102.5 m 2 / g, total pore volume 0.259cm 3 / g.

[0134] By observing the structure, it can be seen that the metal salt, as the active component, is stably loaded in the rigid pores formed by the porous oxide. The flocculation network forms a dense protective layer on the periphery, which effectively prevents the dissolution of the components in the pores and provides structural support for the subsequent capture and fixation of heavy metal ions.

[0135] Test Example 2

[0136] In this test example, a simulated wastewater treatment experiment was conducted on the heavy metal adsorbent prepared in Example 1. The simulated wastewater was mixed heavy metal wastewater.

[0137] In the experiment, 1g of the heavy metal adsorbent from the example was added to four 1000mL portions of simulated wastewater. The wastewater had a pH of 6 and contained two heavy metal ions, each with an initial concentration of 100ppm (i.e., 100mg / L). After stirring at room temperature for 30 minutes, 5mL of a 0.4g / L polyacrylamide solution was added dropwise and stirring continued for 2 minutes. The test results are shown in Table 1.

[0138] Table 1

[0139]

[0140] It can be seen from Examples 1-7 that the sulfur-containing compounds are loaded in the mesoporous channels. During the wastewater treatment process, they can react with heavy metal ions in the water to form precipitates and deposit inside the channels, thereby reducing the concentration of heavy metal ions in the wastewater. Therefore, various sulfur-containing compounds can achieve the same heavy metal removal effect as sodium sulfide.

[0141] In Example 8, starch is used as the sealing material. Since starch has a certain water solubility, the adsorbent is soaked for a long time when treating wastewater, and part of the starch dissolves in the water, causing the sulfur ions in the pores to leak into the water body, resulting in a reduced removal rate of heavy metal ions and a high concentration of heavy metal ions in the water body.

[0142] The calcium oxide content used in Example 9 is slightly low, which results in a reduced ability of the adsorbent to adjust the pH of the wastewater, ultimately leading to a reduced removal rate of heavy metal ions and a high concentration of residual heavy metal ions in the water.

[0143] The slightly higher amount of calcium oxide added in Example 10 resulted in alkalinity in the water. Hydroxyl ions in the water reacted with heavy metal ions, reducing the amount of heavy metal ions adsorbed by the sulfur ions in the adsorbent. Because hydroxides have a certain solubility, the concentration of heavy metal ions in the wastewater increases over time, resulting in a relatively high residual heavy metal ion concentration and poor heavy metal ion removal efficiency by the adsorbent.

[0144] In Example 11, the adsorbent is dried at 100°C. At this time, some water vapor inside the pores will still not evaporate, resulting in a small amount of water in the pores, and some water will also remain in the polymer material. When the adsorbent is added to the wastewater, the time for the wastewater to enter the pores is slowed down, and the rate of the adsorbent to remove heavy metal ions is reduced, which ultimately leads to a lower heavy metal removal rate in the wastewater and a high concentration of residual heavy metal ions in the wastewater.

[0145] In Example 12, the adsorbent is dried at an excessively high temperature (300°C). At this time, part of the polymer material melts at high temperature and completely closes the mesopores of the adsorbent, causing water to take a longer time to enter the pores of the mesopores. The efficiency of using the adsorbent to remove heavy metal ions is reduced, ultimately resulting in a high residual concentration of heavy metal ions in the water body.

[0146] In summary, the addition of adsorbents can effectively reduce the concentration of heavy metal ions in water. Heavy metal ions are transferred from the water into the adsorbent, forming a precipitate and being retained in the adsorbent's pores. The subsequent addition of a flocculant collects the used adsorbent, thereby reducing the concentration of heavy metal ions in the water. In some examples, the residual ion concentration of heavy metal ions has been reduced to single digits, and the lead ion concentration has been reduced to 1 ppm.

[0147] Figure 4 This is a photo of the heavy metal adsorbent used in Example 1 to treat lead and arsenic wastewater, Figure 4 The test strip pointed by B shows the concentration of lead ions in the wastewater before treatment (100 ppm), and the test strip pointed by A shows the concentration of lead ions in the wastewater after treatment (0 ppm).

[0148] Figure 5 This is a photo of collecting the heavy metal adsorbent after adding flocculant to treat lead and arsenic wastewater using the heavy metal adsorbent in Example 1.

[0149] Figure 8 This is the result of treating simulated wastewater with the heavy metal adsorbent of Example 13.

[0150] The ammonium iodide in the heavy metal adsorbent of Example 13 can also be deposited within the pores, reacting with lead ions to form a lead iodide precipitate. However, its effectiveness is inferior to that of the heavy metal adsorbents of Examples 1-7. The reasons for this are: first, the ammonium iodide is deposited in the adsorbent's pores. During the heating and drying phase, some of the ammonium iodide is easily oxidized and lost, resulting in a relatively low level of ammonium iodide deposited in the pores. Second, the lead iodide formed by iodine ions and lead ions in water has a certain solubility in water, causing it to be released back into the aqueous solution. Consequently, the actual amount of iodine ions available to react with heavy metals in the water is relatively low, resulting in fewer heavy metal ions being adsorbed and a relatively high level of heavy metal ions remaining in the water. Partial dissolution of the iodide precipitate in water further increases the amount of heavy metal ions remaining in the water, ultimately resulting in a still-high lead ion content in the treated wastewater. The test strip on the right measures the lead ion concentration in the treated wastewater, indicating approximately 50 ppm remaining.

[0151] After conversion, each kilogram of the heavy metal adsorbent of Example 1 can treat one ton of lead-containing wastewater with a concentration of 100 ppm (mg / L), reducing the concentration to below 1 ppm (mg / L). Further testing by the present applicants has shown that the maximum adsorption capacity of this adsorbent is 2 tons of lead ion wastewater with a concentration of 100 ppm per kilogram of adsorbent, with the residual lead ion content in the treated solution below 10 ppm. This adsorption efficiency is 3-5 times that of commonly used activated carbon adsorbents.

[0152] The above results fully demonstrate that the adsorbent has excellent adsorption performance for heavy metal ions and can effectively remove them from water bodies.

[0153] Test Example 3

[0154] In this test example, an actual wastewater treatment experiment was conducted on the heavy metal adsorbent prepared in Example 1. The actual wastewater was heavy metal wastewater from an enterprise, and had a pH value of 6.

[0155] 1 g of the heavy metal adsorbent of Example 1 was added to 1000 mL of heavy metal wastewater, and after stirring at room temperature for 30 minutes, 5 mL of a 0.4 g / L polyacrylamide solution was added dropwise, and stirring was continued for 2 minutes.

[0156] The test results are shown in Table 2:

[0157] Table 2

[0158] Example 1 <![CDATA[Pb 2+ (mg / L)]]> <![CDATA[Hg 2+ (mg / L)]]> <![CDATA[Cu 2+ (mg / L)]]> <![CDATA[Cd 2+ (mg / L)]]> <![CDATA[As 3+ (mg / L)]]> Before adsorption 105 56 112 75 86 After adsorption 0.2 1.2 1 0.5 0.8

[0159] Comparative Example 1

[0160] This comparative example provides a method for preparing a heavy metal adsorbent material. Except for not performing step (3) in Example 1, the remaining steps are the same as those in Example 1. That is, compared with Example 1, no auxiliary materials are added in this comparative example. The specific preparation method is as follows:

[0161] Step (1): Add 25 g of Na2S to 250 ml of water and stir at 500 rpm for 10 minutes at room temperature (about 25°C) until it is completely dissolved.

[0162] Step (2): 75 ml of methyl orthosilicate (TMOS) and 100 ml of a 0.2 g / L polyacrylamide solution were added to the solution simultaneously, and stirred for 10 minutes to obtain a uniform mixture consisting of porous silica loaded with metal salts and a flocculated network coated on the outside of the porous silica.

[0163] Step (3): The mixture obtained in step (2) is placed in a glass tray and heated in a muffle furnace at 200°C for 2 hours. The mixture is ground evenly to obtain a heavy metal adsorbent material in which the metal salt is deposited in the pores and is coated with porous silica (porous oxide) and a flocculation network.

[0164] in, Figure 6 A is a physical picture of the adsorbent prepared according to the scheme of Comparative Example 1 (i.e., no auxiliary materials are added), Figure 6 B is a comparison of water samples after it was used to treat lead-containing wastewater. Figure 6 As shown in the figure, the adsorbent prepared without adding auxiliary materials showed obvious structural defects and adsorption failure during the wastewater treatment process. This is because the metal salts in the adsorbent pores are easily dissolved after contact with water and then escape into the external environment. Although they can react with heavy metal ions in the water to form precipitates, the precipitates are not effectively confined inside the adsorbent, but are directly released into the water, making it impossible to fix and remove heavy metal ions ( Figure 6 B).

[0165] The preparation method of the present application can flexibly adjust the dosage of auxiliary materials according to the acidity and alkalinity of the wastewater, so that the adsorbent can meet the needs of water bodies with different pH values; secondly, according to the loading amount of the effective components in the adsorbent, the dosage of auxiliary materials can be adjusted to improve the spatial stability of the effective components in the adsorbent and the restriction ability of the adsorbed products on heavy metal ions.

[0166] Comparative Example 2

[0167] This comparative example provides a method for preparing a heavy metal adsorbent material. Except that calcium oxide is not added in step (3), the remaining steps are the same as those in Example 1.

[0168] Step (1) Add 25 g of Na2S to 250 ml of water and stir at 500 rpm for 10 minutes at room temperature (about 25°C) until it is completely dissolved.

[0169] Step (2) 75 ml of methyl orthosilicate (TMOS) and 100 ml of a 0.2 g / L polyacrylamide solution were added to the solution simultaneously, and stirred for 10 minutes to obtain a uniform mixture consisting of porous silica loaded with metal salts and a flocculated network coated on the porous silica.

[0170] Step (3) The mixture obtained in step (2) was transferred into a container and stirred for 10 minutes, and then 20 g of polyaluminium chloride was added and stirred for another 10 minutes.

[0171] Step (4) All the solids in the container are placed in a high-temperature resistant quartz glass tray and heated in a muffle furnace at 200°C for 2 hours. The heavy metal adsorbent material consisting of a porous oxide with metal salts deposited in the pores and a flocculated network is obtained by grinding evenly. Figure 7 .

[0172] like Figure 7 As shown, A is a physical picture of the adsorbent prepared without adding calcium oxide, and B is a photo of the adsorbent used to test lead-containing wastewater (pH 6, lead ion concentration 100ppm). The treated wastewater appears clear and colorless. Figure 7 Area C in B is the lead ion detection paper testing the wastewater in the glass bottle after treatment, which shows clear and colorless. The test paper shows dark yellow, indicating that the lead ions in the wastewater have not been completely removed, and the remaining lead ion concentration is about 50-75ppm.

[0173] Because the comparative example does not add auxiliary material a (such as calcium oxide) according to the pH of the wastewater to be tested, the ability of the adsorbent to adjust the pH of the wastewater is reduced, which ultimately leads to a reduced removal rate of heavy metal ions and a high concentration of residual heavy metal ions in the water.

[0174] It should be noted that the specific parameters or some reagents in the above embodiments are specific embodiments or preferred embodiments under the concept of the present invention, and are not intended to limit the present invention; those skilled in the art can make adaptive adjustments within the concept and protection scope of the present invention.

Claims

1. A heavy metal adsorbent material, characterized in that: The heavy metal adsorbent material comprises the following raw materials by total mass: 10-35wt% metal salt, 1-80wt% porous oxide raw material, 0.001-5wt% flocculant and 5-65wt% auxiliary material; The heavy metal adsorbent material is composed of a porous oxide with metal salts deposited in the pores and a flocculation network coated on the porous oxide. The auxiliary material is deposited on the surface and in the pores of the heavy metal adsorbent material.

2. The heavy metal adsorbent material according to claim 1, characterized in that The metal salt includes one or more of metal chloride, metal bromide, metal iodide, metal sulfide, metal sulfate, metal nitrate, metal carbonate, metal phosphate, and metal chromate; and / or; the porous oxide raw material is selected from one or more of tetramethyl silicate, tetraethyl silicate, 3-aminopropyltriethoxysilane, tetrapropyl titanate and tetrabutyl titanate; and / or; the flocculant is selected from any one of polyacrylamide, aluminum sulfate, potassium aluminum sulfate dodecahydrate (alum), polyaluminum chloride, ferric chloride, ferrous sulfate, polyferric sulfate, polyferric sulfate, sodium alginate, guar gum, polyethyleneimine, sodium polystyrene sulfonate, and sodium polyacrylate; And / or, the excipients include one or more of potassium aluminum sulfate dodecahydrate (alum), ferric chloride, ferrous sulfate, polyferric sulfate, polyaluminum chloride, polyferric sulfate, polyacrylamide chitosan, sodium alginate, guar gum, polyethyleneimine, sodium polystyrene sulfonate, sodium polyacrylate, aluminum oxide, zinc oxide, boron trioxide, calcium oxide, sodium oxide, potassium oxide, and barium oxide.

3. The heavy metal adsorbent material according to claim 1 or 2, characterized in that: The auxiliary materials include auxiliary materials a and b; wherein, auxiliary material a is selected from one or more of calcium oxide, aluminum oxide, zinc oxide, boron trioxide, sodium oxide, potassium oxide, and barium oxide; auxiliary material b is selected from one or more of polyaluminum chloride, potassium aluminum sulfate dodecahydrate (alum), ferric chloride, ferrous sulfate, polyferric sulfate, polyferric sulfate, polyacrylamide chitosan, sodium alginate, guar gum, polyethyleneimine, sodium polystyrene sulfonate, and sodium polyacrylate.

4. The heavy metal adsorbent material according to claim 3, characterized in that: The heavy metal adsorbent material comprises the following raw materials based on total mass: 10-25 wt% of metal salt, 30-75 wt% of porous oxide raw material, 0.001-5 wt% of flocculant, 0-50 wt% of auxiliary material a and 5-15 wt% of auxiliary material b.

5. The heavy metal adsorbent material according to claim 1, characterized in that: The heavy metal adsorbent material is prepared by mixing a 0.1-10 mol / L metal salt solution obtained by dissolving a metal salt in water with a porous oxide raw material and a flocculant, and performing hydrolysis and flocculation reactions to obtain a mixture. The mixture is then mixed with auxiliary materials and stirred uniformly, and then heated at 30-500° C. for 10-600 minutes.

6. The heavy metal adsorbent material according to claim 5, characterized in that: The reaction conditions of the hydrolysis and flocculation reaction include: reaction temperature of 0-100°C, stirring speed of 50-500 rpm, and reaction time of 1-600 min; And / or, the conditions of the heat treatment include: a heating temperature of 150-250° C. and a heating time of 60-180 min.

7. The method for preparing the heavy metal adsorbent material according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: S1: weighing the raw materials according to any one of claims 1 to 6; S2: Add metal salt to water and stir until fully dissolved to obtain a metal salt solution with a concentration of 0.1-10 mol / L; S3: adding a porous oxide raw material and a flocculant to the metal salt solution, stirring at 0-100° C. and 50-500 rpm for 1-600 min to perform hydrolysis and flocculation reactions, to obtain a mixture consisting of a porous oxide with metal salt deposited in the pores and a flocculation network coated on the outside of the porous oxide; S4: adding auxiliary materials to the mixture obtained in step S3, mixing and stirring uniformly to obtain a multilayer network-coated mixture containing metal salts; S5: The mixture obtained in step S4 is heated at 30-500° C. for 10-600 min, and then ground evenly to obtain a heavy metal adsorbent material.

8. Use of the heavy metal adsorbent material according to any one of claims 1 to 6 or the heavy metal adsorbent material obtained by the preparation method according to claim 7 in the treatment of wastewater containing heavy metal ions, characterized in that: The pH value of the heavy metal ion-containing wastewater ranges from 1 to 10.

9. A method for treating wastewater containing heavy metal ions, characterized in that: The specific steps of the treatment method include: adding the heavy metal adsorbent material according to any one of claims 1 to 6 into wastewater containing heavy metal ions, and adding a flocculant to collect the heavy metal adsorbent material after a period of reaction.

10. The use according to claim 8 or 9, characterized in that: The heavy metal adsorbent material is added in a mass ratio of 1:(800-1500) to the wastewater containing heavy metal ions.

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