Composite functional thallium removal material, preparation method and application thereof

Abstract

This invention provides a composite functionalized thallium removal material, its preparation method, and its applications. The composite functionalized thallium removal material is composed of α-MnO2 nanomaterials, polyethyleneimine, and sodium alginate (SA). The preparation method includes: firstly, synthesizing α-MnO2 nanomaterials with a needle-like structure via a hydrothermal method; secondly, dissolving sodium alginate and polyethyleneimine in water to form a mixed matrix solution; subsequently, uniformly dispersing the α-MnO2 nanomaterials in the above mixed solution to obtain a composite dispersion; finally, adding the composite dispersion dropwise to a calcium chloride solution, using calcium ions for cross-linking and solidification to form microspheres, followed by washing and freeze-drying to obtain the finished product. The composite functionalized thallium removal material of this invention possesses advantages such as high adsorption capacity (≥293 mg / g), fast adsorption rate (reaching equilibrium in 30 min), wide pH adaptability (especially suitable for acidic wastewater), easy separation and recovery, environmentally friendly process, and low cost.

Description

Technical Field

[0001] This invention relates to thallium removal technology, and more particularly to a composite functionalized thallium removal material, its preparation method, and its uses. Background Technology

[0002] Thallium (Tl) is a typical rare and dispersed element with extremely high biotoxicity and accumulative properties, far exceeding that of common heavy metals such as lead, mercury, and cadmium. Thallium ions readily enter the human body through the skin, respiratory tract, and digestive tract, interfering with normal potassium ion metabolism and severely damaging the nervous, digestive, and cardiovascular systems, even leading to hair loss, blindness, paralysis, or death. Since thallium is often found in sulfide deposits in nature, the discharge of thallium-containing wastewater is increasing daily due to the rapid development of non-ferrous metal smelting, coal-fired power generation, cement production, and the chemical industry, posing a serious threat to aquatic ecosystems and human health. Therefore, developing efficient and economical thallium-containing wastewater treatment technologies has become an urgent need in the field of environmental science.

[0003] Currently, the main methods for treating thallium-containing wastewater include chemical precipitation, ion exchange, membrane separation, and adsorption. Among these, adsorption is considered one of the most promising technologies due to its advantages such as simple operation, low cost, and no secondary pollution. However, existing adsorption materials still have significant shortcomings in practical applications: First, thallium in water mainly exists in the form of monovalent thallium Tl(I), whose ionic radius is very close to that of potassium ions (K+), and its hydration energy is low. This results in traditional adsorbents (such as activated carbon and ordinary resins) having weak affinity and poor selectivity for it, making it difficult to achieve efficient removal in the context of complex coexisting ions (especially high concentrations of K+ and Na+). Second, although some modified adsorbents can convert Tl(I) into more easily removable trivalent thallium Tl(III) through oxidation, they often suffer from low oxidant loading, easy loss, or slow oxidation rate, failing to achieve efficient synergy between oxidation and adsorption. Finally, many high-performance nano-adsorbents have defects such as poor mechanical strength, poor regeneration performance, and insufficient stability under acidic or neutral conditions, which limit their application in large-scale engineering water treatment.

[0004] Therefore, there is an urgent need to develop a novel composite adsorbent that combines strong oxidizing power, highly selective chelating sites, and excellent stability to solve the problem of deep purification of low-concentration thallium. Summary of the Invention

[0005] The purpose of this invention is to address the above-mentioned problems by proposing a method for preparing composite functionalized thallium removal materials. This method is simple and low-cost. The composite functionalized thallium removal materials prepared by this method have the advantages of high adsorption capacity (≥293 mg / g), fast adsorption rate (reaching equilibrium in 30 min), wide pH adaptability range (especially suitable for acidic wastewater), easy separation and recovery, environmentally friendly process, and low cost through an "oxidation-chelation" synergistic mechanism.

[0006] It should be noted that, in this invention, unless otherwise specified, the specific meaning of "comprising" in relation to composition and description includes both open-ended meanings such as "comprising," "including," etc., and closed-ended meanings such as "composed of," "consisting of," etc., and similar meanings.

[0007] To achieve the above objectives, the technical solution adopted by this invention is: a method for preparing a composite functionalized thallium removal material, comprising the following steps:

[0008] Step 1: Prepare α-MnO2 nanomaterials;

[0009] Step 2: Dissolve sodium alginate and polyethyleneimine (PEI) in water to form a homogeneous sodium alginate / polyethyleneimine mixed aqueous solution;

[0010] Step 3: Disperse α-MnO2 nanomaterials in a mixed aqueous solution of sodium alginate / polyethyleneimine to obtain a composite dispersion (also known as α-MnO2 / PEI / SA composite dispersion).

[0011] Step 4: Add the composite dispersion dropwise to the calcium chloride solution to form composite hydrogel microspheres by inducing cross-linking with calcium ions. After curing, washing to remove residual ions (including but not limited to calcium ions) and drying, the composite functionalized thallium removal material (also known as α-MnO2 / PEI / SA adsorbent) is obtained.

[0012] Further, step 1 for preparing α-MnO2 nanomaterials includes the following steps: under nitrogen protection, potassium permanganate and manganese sulfate monohydrate are dissolved in water (stirred for 30 min) to obtain a first solution. The first solution is placed in a high-pressure reactor and hydrothermally reacted at 140-180°C for 10-15 hours (preferably at 160°C for 12 hours). After the reaction is completed, the nanomaterials are cooled, separated, washed, and dried to obtain needle-like α-MnO2 nanomaterials.

[0013] Further, the molar ratio of potassium permanganate to manganese sulfate monohydrate is 2.0-3.0:1, and preferably the molar ratio of potassium permanganate to manganese sulfate monohydrate is 2.5:1.

[0014] Furthermore, the total concentration of manganese ions in the first solution is 0.05-0.2 M.

[0015] Further, in step 1, the first solution is placed in a high-pressure reactor lined with polytetrafluoroethylene, and the high-pressure reactor is filled to 60-80%.

[0016] Furthermore, in step 1, the washing process involves sequentially washing with deionized water and ethanol.

[0017] Furthermore, in step 1, the drying temperature is 50-70°C and the drying time is 10-15 hours, with the preferred drying temperature being 60°C and the drying time being 12 hours.

[0018] Furthermore, in step 2, the polyethyleneimine is branched polyethyleneimine.

[0019] Furthermore, in step 2, the molecular weight of the branched polyethyleneimine is 1800~2500.

[0020] Further, in step 2, the mass concentration of sodium alginate in the sodium alginate / polyethyleneimine mixed aqueous solution is 1-5%, preferably 2%; and the mass concentration of polyethyleneimine is 0.2-1.0%, preferably 0.5%.

[0021] Furthermore, in step 3, the mass ratio of the α-MnO2 nanomaterial to sodium alginate is 0.5-2:2.

[0022] Furthermore, in step 3, the dispersion (stirring) time is 2-4 hours, and the dispersion (stirring) temperature is room temperature to 60°C.

[0023] Furthermore, in step 4, the mass concentration of the calcium chloride solution is 1-5%, preferably 2%.

[0024] Furthermore, in step 4, the cross-linking curing time is 1-3 hours, preferably 2 hours.

[0025] Further, in step 4, the step involves washing with deionized water until no calcium chloride residue remains on the surface.

[0026] Furthermore, in step 4, the drying process is freeze drying.

[0027] Furthermore, the freeze-drying pre-freezing temperature is -40°C to -80°C, and the freeze-drying time is 10-15 hours.

[0028] Another objective of this invention is to disclose a composite functionalized thallium removal material, which is prepared using the above-described method.

[0029] Furthermore, the sodium alginate and polyethyleneimine are cross-linked by calcium ions to form a three-dimensional porous hydrogel network; needle-like α-MnO2 nanomaterials are uniformly dispersed in the pores of the three-dimensional porous hydrogel network.

[0030] Furthermore, the needle-like α-MnO2 nanomaterial has a length of 50~300nm and a diameter of 5-50nm.

[0031] Furthermore, the mass ratio of the needle-like α-MnO2 nanomaterial, branched polyethyleneimine, and sodium alginate is 0.5-2:0.5-2:2, with a preferred mass ratio of 1:0.5:2.

[0032] Furthermore, the composite functionalized thallium removal material is spherical or near-spherical with a particle size of 1-3 mm.

[0033] Another object of the present invention discloses the use of a composite functionalized thallium removal material in the adsorption and removal of heavy metal ions in aqueous solutions.

[0034] Furthermore, the heavy metal ions are one or more of thallium ions, mercury ions, lead ions, and zinc ions. It is particularly suitable for adsorbing and removing thallium ions from aqueous solutions.

[0035] Furthermore, the concentration of heavy metal ions in the aqueous solution is 1~10 mg / L.

[0036] Furthermore, the composite functionalized thallium removal material utilizes the α-MnO2 nanorods to oxidize monovalent thallium in water to trivalent thallium, and then chelates and adsorbs the trivalent thallium through the amino groups of the branched polyethyleneimine and the carboxyl groups of the sodium alginate, thereby achieving synergistic oxidation-adsorption thallium removal.

[0037] Furthermore, the pH value of the thallium-containing wastewater is 2-7, preferably 2-5.

[0038] Furthermore, the dosage of the composite functionalized thallium removal material in thallium-containing wastewater is 0.05-1.5 g / L, preferably 0.2 g / L.

[0039] Furthermore, the adsorption time of the composite functionalized thallium removal material is 30-120 minutes.

[0040] Furthermore, the thallium-containing wastewater also contains one or more cations selected from potassium, sodium, calcium, and magnesium ions, and / or one or more organic compounds selected from fulvic acid, humic acid, and EDTA. Even with the presence of these cations and organic compounds, the highly efficient thallium adsorbent can still selectively adsorb the target heavy metal.

[0041] Furthermore, the composite functionalized thallium removal material has a saturated adsorption capacity for thallium ≥ 293 mg / g. The preferred saturated adsorption capacity is 293-400 mg / g.

[0042] This invention relates to a composite functionalized thallium removal material using sodium alginate hydrogel as a carrier and loading needle-like α-MnO2 as the adsorption functional component. This material combines the oxidative adsorption characteristics of manganese dioxide for the heavy metal thallium with the advantages of the porous structure and abundant polyhydroxyl sites of the hydrogel material, thereby achieving high-capacity adsorption of thallium and making it suitable for the removal of heavy metal thallium from wastewater. Specifically, this invention has the following advantages compared to existing technologies:

[0043] 1) Synergistic effect, high adsorption capacity and fast rate: This invention combines the strong oxidizing properties of α-MnO2 nanorods, the amino chelating sites of branched polyethyleneimine (PEI), and the porous network structure of sodium alginate (SA). α-MnO2 can oxidize the difficult-to-remove monovalent thallium Tl(I) in water in situ to the easily adsorbed trivalent thallium Tl(III), while the active functional groups (-NH2, -COOH, -OH) on the PEI and SA frameworks achieve efficient capture of Tl(III) through electrostatic attraction and coordination. This "oxidation-chelation" synergistic mechanism significantly increases the saturated adsorption capacity of the adsorbent for thallium to 293.28 mg / g, and the adsorption kinetics are rapid, reaching adsorption equilibrium within 30 min.

[0044] 2) Macroscopic shaping, easy separation and recycling with good recyclability: Addressing the problems of easy loss, difficult recycling, and secondary pollution associated with traditional nanopowder adsorbents, this invention utilizes Ca2+-induced ion crosslinking technology to stably load nano-α-MnO2 and PEI into SA hydrogel microspheres. The resulting adsorbent is regularly spherical, exhibits good mechanical strength, is morphologically stable in acidic and neutral water bodies, and is easily separated into solid and liquid phases through simple filtration or sedimentation.

[0045] 3) Strong pH adaptability, filling the gap in acidic wastewater treatment: Traditional thallium removal materials (such as some biochar or ordinary resins) often perform well only under alkaline or neutral conditions, while their efficiency drops sharply in acidic industrial wastewater. The α-MnO2 / PEI / SA adsorbent prepared in this invention benefits from the protonation characteristics of PEI and the chemical stability of α-MnO2, maintaining high efficiency in thallium removal over a wide pH range (especially the acidic range of pH 2-6), effectively solving the technical problem of the difficulty in deep purification of acidic thallium-containing wastewater.

[0046] 4) Raw materials are readily available, the process is environmentally friendly, and it has industrialization potential: The sodium alginate used in this invention is widely available and biodegradable. The preparation process does not require the use of toxic organic solvents, the reaction conditions are mild, and the cost is low.

[0047] The composite functionalized thallium removal material of this invention has good application prospects and large-scale promotion potential in the field of adsorption and removal of heavy metal ions in aqueous solutions. Attached Figure Description

[0048] Figure 1 The images shown are scanning electron microscope (SEM) images of the composite functionalized thallium removal material before and after adsorption of thallium in Example 1. (a) shows the pure α-MnO2 nanomaterial synthesized by hydrothermal method; (b) shows the α-MnO2 / PEI / SA composite adsorbent loaded with α-MnO2 nanorods; (c) shows the SEM image (scanning size 500 nm) of the α-MnO2 / PEI / SA composite adsorbent after thallium adsorption; and (d) shows the SEM image (scanning size 200 nm) of the α-MnO2 / PEI / SA composite adsorbent after thallium adsorption.

[0049] Figure 2 The X-ray photoelectron spectroscopy (XPS) of the composite functionalized thallium removal material in Example 1 before and after thallium adsorption is shown below. (a) is the high-resolution spectrum of C1s before and after adsorption; (b) is the high-resolution spectrum of N1s before and after adsorption; (c) is the high-resolution spectrum of Mn2p before and after adsorption; (d) is the high-resolution spectrum of Tl4f after adsorption; and (e) is the full XPS spectrum before and after thallium adsorption.

[0050] Figure 3 This is a saturated adsorption capacity diagram of the composite functionalized thallium removal material in Example 1;

[0051] Figure 4 This is a graph showing the time required for the composite functionalized thallium removal material in Example 1 to reach saturated adsorption.

[0052] Figure 5 The graph shows the effect of pH in the aquatic environment on the adsorption of the composite functionalized thallium removal material in Example 1.

[0053] Figure 6 This is an optimization diagram showing the dosage of the composite functionalized thallium removal material in Example 1;

[0054] Figure 7 The graph shows the effect of coexisting cations on the composite functionalized thallium removal material of Example 1.

[0055] Figure 8 The diagram shows the effect of coexisting organic matter on the composite functionalized thallium removal material of Example 1. Detailed Implementation

[0056] The present invention will be further described below with reference to embodiments. The description of the technical features described below is based on representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:

[0057] Unless otherwise stated, all units used in this specification are international standard units, and all numerical values ​​and ranges appearing in this invention should be understood to include systematic errors that are unavoidable in industrial production.

[0058] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0059] In this specification, the numerical range indicated by "above" or "below" refers to the numerical range that includes the stated number.

[0060] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0061] In this specification, the terms "optional" or "optional" are used to indicate the use or omission of certain substances, components, procedures, application conditions, etc.

[0062] In this instruction manual, when "room temperature" or "room temperature" is used, the temperature can be 15-25℃.

[0063] Unless otherwise specified, all reagents or instruments used in this instruction manual are commercially available products.

[0064] Example 1

[0065] This embodiment discloses a composite functionalized thallium removal material, the preparation method of which includes the following steps:

[0066] 1) Synthesis of α-MnO2 nanomaterials: Potassium permanganate (KMnO4) and manganese sulfate monohydrate (MnSO4·H2O) were weighed at a molar ratio of 2.5:1 (e.g., approximately 0.79 g KMnO4 and 0.34 g MnSO4·H2O, the specific mass should be adjusted according to the target yield), and dissolved in 60 mL of deionized water. The mixed solution was magnetically stirred for 30 min under nitrogen protection, and then transferred to a 100 mL high-pressure reactor lined with polytetrafluoroethylene. The reactor was placed in an oven and subjected to a hydrothermal reaction at 160°C for 12 h. After the reaction was completed, the mixture was naturally cooled to room temperature, and the product was centrifuged. It was washed three times alternately with deionized water and anhydrous ethanol, and finally dried in a vacuum drying oven at 60°C for 12 h to obtain needle-like α-MnO2 nanomaterials, which were then ground and used for later use.

[0067] 2) Preparation of sodium alginate / polyethyleneimine-based solution: Prepare a sodium alginate solution containing branched polyethyleneimine (PEI). Weigh 2.0 g of sodium alginate (SA) and 0.5 g of branched polyethyleneimine (PEI) and dissolve them in 100 mL of deionized water. Stir magnetically at 60°C for 3 h until the solids are fully dissolved and dispersed, finally obtaining a clear, viscous, bubble-free homogeneous mixed solution; simultaneously prepare a 2 wt% calcium chloride crosslinking agent solution by weighing 2 g of calcium chloride solid powder and dissolving it in 100 mL of deionized water, stirring until completely dissolved.

[0068] 3) Preparation of α-MnO2 / PEI / SA composite suspension: Weigh 1.0 g of the α-MnO2 nanomaterial synthesized in step 1) and add it to the sodium alginate / polyethyleneimine mixed solution that has been uniformly dispersed in step 2). Stir magnetically for 3 h at room temperature or 60°C to ensure that the α-MnO2 nanomaterial is fully dispersed and stabilized, thus obtaining a uniform and stable α-MnO2 / PEI / SA composite suspension.

[0069] 4) Cross-linking, curing, and molding: The composite suspension was drawn up using a syringe and fixed onto a syringe pump. A beaker containing a 2wt% calcium chloride solution was placed 20 cm directly below the syringe needle. The syringe pump was started, and the flow rate was controlled at 0.2~2 mL / min to steadily add the suspension dropwise into the calcium chloride solution, utilizing Ca2+-induced ion cross-linking to form microspheres in situ. After the addition was complete, the hydrogel microspheres were allowed to continue to be immersed in the calcium chloride solution for cross-linking for at least 2 hours. The microspheres were then removed, and the surface of the microspheres was repeatedly washed with deionized water to remove residual calcium chloride and unfixed components until the washing solution was neutral and free of chloride ions. Finally, the washed microspheres were pre-frozen in a -80°C freezer for 4 hours, and then dried in a freeze dryer for 12 hours to obtain a porous composite functionalized thallium removal material (α-MnO2 / PEI / SA composite adsorbent).

[0070] Figure 1Scanning electron microscopy (SEM) images and energy-dispersive X-ray spectroscopy (EDS) elemental surface scans of the α-MnO2 / PEI / SA composite adsorbent prepared in Example 1 before and after adsorption of the heavy metal thallium. (a) SEM image of pure α-MnO2 nanomaterials synthesized by hydrothermal method. As can be seen from the image, the material exhibits a uniform needle-like (or rod-like) nanostructure with a smooth surface and uniform size distribution; (b) A magnified view of the surface of the α-MnO2 / PEI / SA composite adsorbent microspheres loaded with α-MnO2 nanorods. It can be clearly observed that the needle-like α-MnO2 nanorods are successfully embedded and uniformly dispersed in the porous network framework of sodium alginate (SA), forming a stable composite structure; (c) (d) is a SEM image of thallium adsorbed by the α-MnO2 / PEI / SA composite adsorbent (scanning size 500 nm); (d) is a SEM image of thallium adsorbed by the α-MnO2 / PEI / SA composite adsorbent (scanning size 200 nm). After adsorption, a significant Tl element signal (purple) appeared on the surface of the material, and the Tl element highly overlapped in spatial distribution with the Mn element (cyan, derived from α-MnO2) and N element (yellow, derived from PEI) in the matrix. This result intuitively confirms that the composite material has successfully achieved efficient capture and enrichment of the heavy metal thallium in water by utilizing the oxidizing property of α-MnO2 and the abundant active sites of PEI / SA.

[0071] Figure 2 The X-ray photoelectron spectra (XPS) of the α-MnO2 / PEI / SA composite adsorbent prepared in Example 1 before and after adsorption of the heavy metal thallium are shown. (a) is the high-resolution spectrum before and after C1s adsorption; (b) is the high-resolution spectrum before and after N1s adsorption; (c) is the high-resolution spectrum before and after Mn2p adsorption; (d) is the high-resolution spectrum of Tl4f after adsorption; and (e) is the full XPS spectrum before and after thallium adsorption. It is evident that the characteristic peaks of thallium were clearly observed after adsorption, proving that the adsorbent material successfully adsorbed thallium. In the high-resolution C1s and N1s spectra, the intensity of the carboxyl peak (O=CO) in the C1s spectrum increased and the binding energy shifted positively after adsorption. The proportion of protonated amino groups (-NH3+) in the N1s spectrum increased significantly, confirming that the carboxyl groups of sodium alginate coordinate with Tl, and that the amino groups of polyethyleneimine effectively captured Tl ions through electrostatic attraction. In the high-resolution spectra of Mn2p and Tl4f, the characteristic peak of Mn4+ weakened after adsorption, while the Mn3+ / Mn2+ peaks strengthened. Simultaneously, the proportion of trivalent thallium (Tl3+) in the Tl spectrum reached approximately 68%, confirming the redox process of α-MnO2 oxidizing Tl+ to Tl3+. The generated Tl³⁺, due to its stronger Lewis acidity, readily forms stable complexes or precipitates with oxygen- and nitrogen-containing functional groups on the material surface. In summary, this composite material achieves efficient and deep removal of thallium through the synergistic effect of α-MnO2 oxidation and the multi-site chelation of PEI / SA.

[0072] Figure 3 The saturated adsorption capacity of α-MnO2 / PEI / SA prepared in Example 1 is shown. The maximum saturated adsorption capacity of this adsorbent for the heavy metal thallium can reach 293.28 mg / g, and the adsorption process is more in line with the Langmuir adsorption model, with the largest R2.

[0073] Figure 4 The figure shows the time required for the α-MnO2 / PEI / SA composite adsorbent prepared in Example 1 to reach saturation adsorption capacity for different initial thallium concentrations (10, 20, 50 mg / L). The adsorbent undergoes rapid adsorption within the first 30 minutes and then gradually stabilizes. The figure shows that this adsorption process more closely resembles a pseudo-second-order kinetic adsorption process, indicating that chemisorption is the main rate-limiting step in the thallium ion adsorption process using α-MnO2 / PEI / SA.

[0074] Figure 5 The effect of pH in the aquatic environment on the adsorption of the α-MnO2 / PEI / SA composite adsorbent prepared in Example 1 was investigated. Under low pH (2~7) conditions, the adsorbent had a higher adsorption capacity. This was because the high pH (8~11) environment destroyed the stable pore structure of the adsorbent and caused α-MnO2 to dissolve from SA, thus reducing the adsorption effect of the adsorbent.

[0075] Figure 6 To optimize the dosage of the α-MnO2 / PEI / SA adsorbent prepared in Example 1, the initial thallium concentration was controlled at 10 mg / L, pH at 4, and temperature at 25°C. When the adsorbent dosage increased from 0.05 g / L to 1.5 g / L, the thallium removal rate significantly increased from 18.1% to 99.8%, while the thallium adsorption capacity decreased from 36.2 mg / g to 6.65 mg / g. At higher dosages, the increase in Tl removal is due to the increase in binding sites. However, the use of higher dosages weakens the competitive effect between adsorbents. Although the total adsorption capacity increases, the relatively fixed Tl⁺ concentration in the solution reduces the number of ions that can be contacted and captured per unit adsorbent, leading to a decrease in unit adsorption capacity. Considering the cost of adsorbent use and a satisfactory removal rate, 0.2 g / L was selected as the optimal dosage.

[0076] Figure 7 The effect of the presence of cations in the aquatic environment on the adsorption process of the α-MnO2 / PEI / SA adsorbent prepared in Example 1 was investigated. Figure 7To investigate the effect of cations in the aquatic environment on the adsorption process of the α-MnO2 / PEI / SA adsorbent prepared in Example 1, the initial thallium concentration was controlled at 10 mg / L, pH at 4, and temperature at 25 °C. It was found that when the potassium ion concentration increased from 0.001 M to 0.1 M, the adsorption capacity decreased from 16 mg / g to 8 mg / g, exhibiting a significant competitive inhibition effect. This is because potassium ions and thallium ions have similar hydration radii (K+: 1.33 Å) and Tl+: 1.47 Å, leading to competitive entry into the adsorbent material and competition for adsorption sites. The inhibitory effect was more pronounced at a high sodium ion concentration of 0.1 M. This is because exogenous sodium ions may replace sodium ions within the material, causing pore collapse and thus weakening the adsorption effect. In comparison, the inhibition of divalent calcium and magnesium ions is weaker than that of monovalent potassium and sodium ions, but it still has an inhibitory effect. This is due to their higher charge density, which can compete for negative charge sites on the adsorbent surface (such as –COO- and deprotonated -NH2) through stronger electrostatic interactions, thus partially shielding the adsorption channels of Tl+.

[0077] Figure 8 The effect of coexisting organic matter in the aquatic environment on the adsorption process of the α-MnO2 / PEI / SA adsorbent prepared in Example 1 was investigated. Figure 8 To investigate the effect of coexisting organic matter in the aquatic environment on the adsorption process of the α-MnO2 / PEI / SA adsorbent prepared in Example 1, the initial thallium concentration was controlled at 10 mg / L, pH at 4, and temperature at 25 °C. It was found that when the concentrations of HA, FA, and EDTA were 0.1 M, their inhibition effects on thallium reached 42.2%, 36.4%, and 65.3%, respectively, with adsorption reductions of 7.3 mg / g, 6.3 mg / g, and 11.3 mg / g, respectively. The stronger inhibition effect of EDTA stemmed from its formation of a highly stable complex with Tl+, significantly reducing the concentration of free Tl+ and fundamentally blocking its effective contact with the adsorbent.

[0078] Example 2

[0079] This embodiment discloses a composite functionalized thallium removal material. The preparation method of this material is basically the same as that of Example 1, except that the mass of α-MnO2 added to the sodium alginate hydrogel in step 3 is 0.5g.

[0080] In this embodiment, the composite functionalized thallium removal material has an adsorption capacity of 168.7 mg / g for the heavy metal thallium. Compared with most adsorbent materials, which have an adsorption capacity of only 0~100 mg / g, the adsorbent material prepared in this example has achieved a very good adsorption effect.

[0081] Example 3

[0082] This embodiment discloses a composite functionalized thallium removal material. The preparation method of this material is basically the same as that of Example 1, except that the mass of α-MnO2 added to the sodium alginate hydrogel in step 3 is 2g. The composite functionalized thallium removal material of this embodiment has an adsorption capacity of 177.5mg / g for the heavy metal thallium, and has a good adsorption effect.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a composite functional thallium-removal material, characterized in that, Includes the following steps: Step 1: Preparation of α-MnO2 nanomaterials; Step 2: Dissolve sodium alginate and polyethyleneimine in water to form a homogeneous sodium alginate / polyethyleneimine mixed aqueous solution; Step 3: Disperse α-MnO2 nanomaterials in a mixed aqueous solution of sodium alginate / polyethyleneimine to obtain a composite dispersion; Step 4: Add the composite dispersion dropwise to the calcium chloride solution to form composite hydrogel microspheres by inducing cross-linking with calcium ions. After curing, washing and drying, the composite functionalized thallium removal material is obtained.

2. The preparation method of the composite functionalized thallium removal material according to claim 1, characterized in that, Step 1: Preparation of α-MnO2 nanomaterials includes the following steps: Under nitrogen protection, potassium permanganate and manganese sulfate monohydrate are dissolved in water to obtain a first solution. The first solution is placed in a high-pressure reactor and subjected to hydrothermal reaction at 140-180 °C for 10-15 hours. After the reaction is completed, the nanomaterials are cooled, separated, washed, and dried to obtain needle-like α-MnO2 nanomaterials.

3. The preparation method of the composite functionalized thallium removal material according to claim 2, characterized in that, The molar ratio of potassium permanganate to manganese sulfate monohydrate is 2.0-3.0:1; And / or, the total concentration of manganese ions in the first solution is 0.05-0.2 M; And / or, the filling degree of the high-pressure reactor is 60-80%; And / or, the washing is a sequential washing with deionized water and ethanol; And / or, the drying temperature is 50-70 °C and the drying time is 10-15 hours.

4. The preparation method of the composite functionalized thallium removal material according to claim 1, characterized in that, In step 2, the polyethyleneimine is branched polyethyleneimine; And / or, in the sodium alginate / polyethyleneimine mixed aqueous solution, the mass concentration of sodium alginate is 1-5%; and the mass concentration of polyethyleneimine is 0.2-1.0%.

5. The preparation method of the composite functionalized thallium removal material according to claim 1, characterized in that, In step 3, the mass ratio of the α-MnO2 nanomaterial to sodium alginate is 0.5-2:2; And / or, the dispersion time is 2-4 hours, and the dispersion temperature is room temperature to 60 °C.

6. The preparation method of the composite functionalized thallium removal material according to claim 1, characterized in that, In step 4, the mass concentration of the calcium chloride solution is 1-5%; And / or, the crosslinking curing time is 1-3 hours; And / or, the washing is a deionized water wash; And / or, the drying is freeze-drying.

7. A composite functionalized thallium removal material, characterized in that, It is prepared by the method described in any one of claims 1-6.

8. Use of the composite functionalized thallium removal material of claim 7 in the field of adsorption and removal of heavy metal ions in aqueous solution.

9. The use according to claim 8, characterized in that, The heavy metal ions are one or more of thallium ions, mercury ions, lead ions, and zinc ions.

10. The use according to claim 8, characterized in that, When using composite functionalized thallium removal materials to treat thallium-containing wastewater: the pH value of the thallium-containing wastewater is 2-7; And / or, the dosage of the composite functionalized thallium removal material in thallium-containing wastewater is 0.05-1.5 g / L; And / or, the adsorption time of the composite functionalized thallium removal material is 30-120 minutes.

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