Method for removing organic complex heavy metal based on AMnO3 / PMS system one-step method and application

Abstract

The invention provides a one-step method for removing organic complex heavy metals based on an AMnO3 / PMS system, which comprises the following steps: mixing perovskite transition metal oxide AMnO3 of which the A-site element is an alkaline earth metal element with a solution containing the organic complex heavy metals, and adding an oxidant PMS to oxidize and break the organic complex heavy metals, free heavy metal ions are released, and meanwhile, the released heavy metal ions are adsorbed and removed. According to the method, based on a heterogeneous advanced oxidation system of PMS, A-site metal elements in a perovskite oxide AMnO3 original material are gradually leached in an advanced oxidation reaction, so that the specific surface area of the material is increased, the surface electronegativity of the material is enhanced and maintained, the activation of the material on PMS and the adsorption of the material on free heavy metals released after complex breaking are greatly improved, and the PMS / AMnO3 composite material is obtained. And the removal effect and the cyclic accumulation removal capacity of the AMnO3 / PMS system on the organic complex heavy metals are obviously promoted. The method is simple, environment-friendly, novel in thought and wide in application range, and has industrial application value.

Description

Technical Field

[0001] This invention belongs to the field of heavy metal treatment technology, specifically relating to a one-step method and application for removing organic complexed heavy metals based on the AMnO3 / PMS system. Background Technology

[0002] Wastewater from industries such as mining and electroplating contains large amounts of organically complexed heavy metals, such as lead ethylenediaminetetraacetate (EDTA-Pb) and EDTA-Ni. These organically complexed heavy metals are highly toxic, highly mobile, easily accumulate, and can remain stable over a wide pH range, posing a serious threat to human health. Therefore, the efficient removal of these heavy metals from wastewater is urgently needed. Due to the strong complexation between heavy metals and organic matter, as well as significant steric hindrance, conventional precipitation and adsorption methods cannot effectively remove them. Therefore, it is usually necessary to first oxidize and break down the complexes, and then use the aforementioned methods to remove the released free heavy metal ions from the water.

[0003] Existing technologies have constructed various composite materials with peroxide activation and heavy metal adsorption capabilities. These materials activate peroxides such as H₂O₂ to oxidize and break down organically complexed heavy metals, while simultaneously adsorbing and removing released free heavy metal ions. To improve the adsorption capacity for free heavy metal ions, researchers often use adsorbents with high specific surface area (SSA) to construct composite materials, such as α-Fe₂O₃@activated biochar, hydrated iron oxide@cation exchange resin, and nano-manganese oxide modified biochar (BC-MnO₃). x However, most of the reported composite materials still face problems such as complex synthesis methods, low pollutant treatment capacity, and easy deactivation. Furthermore, the reactive and adsorption sites in the materials are difficult to balance, which limits their removal of organic complexed heavy metals.

[0004] To improve the removal efficiency of organically complexed heavy metals, existing technologies use template methods to construct porous structures to increase surface-specific negative charge (SSA). However, the template method is cumbersome, and residual templates can affect material properties. Doping with electron-rich elements can enhance the negative charge of the material, but as heavy metal ions accumulate on the material surface, the surface negative charge intensity decreases, which is not conducive to the continuous adsorption of heavy metals. Therefore, there is a need to find simple and effective methods to increase the SSA of materials and enhance and maintain their surface negative charge. Summary of the Invention

[0005] The purpose of this invention is to solve the aforementioned technical problems and provide a one-step method for removing organically complexed heavy metals based on an AMnO3 / PMS system. This method can improve the removal efficiency of organically complexed heavy metals and is simple, has a high pollutant treatment capacity, and is recyclable and not easily deactivated. A second objective of this invention is to provide applications of this method.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] This invention provides a method for removing organically complexed heavy metals based on an AMnO3 / PMS system, comprising the following steps: First, perovskite transition metal oxide AMnO3 is mixed with a solution containing organically complexed heavy metals. Then, persulfate (PMS) is added as an oxidant to oxidize and break down the organically complexed heavy metals, releasing free heavy metal ions. At the same time, the released heavy metal ions are adsorbed and removed. The A-site element in the perovskite transition metal oxide AMnO3 is a reactive alkaline earth metal element.

[0008] Furthermore, the organic complexed heavy metal is any one of EDTA-Pb, EDTA-Cu, EDTA-Cd, or EDTA-Zn.

[0009] Furthermore, the A-site element in the perovskite transition metal oxide AMnO3 is selected from alkaline earth metals Ca, Mg, Sr, or Ba.

[0010] Further, the concentration of the organic complexed heavy metal solution is 0.01~0.1 mmol / L; the amount of perovskite transition metal oxide AMnO3 added is 0.1~1 g / L; and the amount of PMS added is 0.4~1.6 mmol / L.

[0011] Furthermore, the perovskite transition metal oxide AMnO3 is mixed with a solution containing organic complexed heavy metals and then dispersed by ultrasonication. The ultrasonic power is 50~200 W and the ultrasonication time is 2~10 min.

[0012] Furthermore, the initial pH of the solution after mixing the perovskite transition metal oxide AMnO3 with a solution containing organic complexed heavy metals is 4.0~9.0.

[0013] Furthermore, after adding the oxidant PMS, the reaction conditions for the reaction process are as follows: reaction for 1-4 hours under continuous magnetic stirring, magnetic stirring speed of 400-1000 rpm, and reaction temperature of 20-35 °C.

[0014] Furthermore, the perovskite transition metal oxide AMnO3 is prepared by the following steps: S1. Add the hydrates of calcium nitrate, magnesium nitrate, strontium nitrate, or barium nitrate to the solvent along with manganese nitrate, ferric nitrate, and organic acid, and stir until homogeneous. S2. The obtained solution is heated at 60~100℃ for 6~48 h to obtain a homogeneous colloid; S3. The colloid is calcined at 800~1200℃ for 2~6 h to obtain perovskite transition metal oxide AMnO3.

[0015] Further, the organic acid in step S1 is citric acid or acetic acid; the amount of organic acid added is 1 to 4 times the metal ion equivalent; the solvent in step 1 is an alcohol-water mixed solution, and the alcohol is ethylene glycol; the mixing ratio of the alcohol and water is 1:1 to 1:5; the heating rate for calcination in step S1 is 2 to 10 °C / min.

[0016] This invention provides the application of perovskite transition metal oxide AMnO3 and persulfate PMS advanced oxidation system (i.e. AMnO3 / PMS system) in the removal of organically complexed heavy metals. The application involves mixing perovskite transition metal oxide AMnO3 with a solution containing organically complexed heavy metals, then adding the oxidant PMS to oxidize and break down the organically complexed heavy metals, releasing free heavy metal ions. Simultaneously, the released heavy metal ions are adsorbed and removed, achieving a one-step removal of organically complexed heavy metals.

[0017] The beneficial effects of this invention are as follows: (1) The ideas and methods provided by this invention are innovative, easy to operate, and have significant expected effects: Compared with traditional methods that improve surface negative charge or increase SSA by incorporating electron-rich elements or constructing porous structures, the method of constructing surface negative charge and increasing SSA by leaching A-site metal elements from perovskite oxide AMnO3 raw materials has the following advantages: 1) This method is simple to operate and easy to implement in acidic advanced oxidation reactions; 2) The gradual dissolution of A-site metal elements during the reaction process can continuously enhance surface negative charge and increase SSA; 3) This strategy is applicable to a variety of perovskite oxides and may be extended to other materials. This invention demonstrates excellent performance in removing organically complexed heavy metals from water using perovskite transition metal oxide AMnO3 and the PMS advanced oxidation system. This invention provides new ideas for the efficient material design and application methods for removing organically complexed heavy metals.

[0018] (2) The method of the present invention is based on the heterogeneous advanced oxidation system of PMS. It utilizes the gradual leaching of A-site metal elements in the perovskite oxide AMnO3 raw material in the advanced oxidation reaction to construct an enhanced material surface negative charge and increase SSA. This greatly improves the material's activation of PMS and the release of free positively charged heavy metal Pb after complex rupture.2+ The adsorption significantly improved the removal efficiency and cumulative removal capacity of the CaMnO3 / PMS system for EDTA-Pb, greatly increasing the recyclability of the material. This achieved the goal of sacrificing Ca to promote the removal of toxic heavy metals, and the adsorbed Pb... 2+ It will not cause secondary pollution due to re-leaching. It is far superior to the removal effect of traditional manganese oxide / PMS systems (such as β-MnO2 / PMS) that do not use this leaching method for EDTA-Pb and the recycling performance of their materials.

[0019] (3) The method of the present invention is simple and easy to implement, applicable to the removal of various organic complex heavy metal pollutants, and suitable for various acidic industrial wastewaters, such as electroplating wastewater, and has potential practical industrial application value. Attached Figure Description

[0020] Figure 1 The XRD diffraction pattern of CaMnO3 with Ca at the A site.

[0021] Figure 2 The effect of the CaMnO3 / PMS system on the removal of organically complexed heavy metal EDTA-Pb.

[0022] Figure 3 The removal effect of CaMnO3 on EDTA-Pb by the system when it is recycled 1-15 times.

[0023] Figure 4 For CaMnO3 in each cycle reaction process Ca 2+ The leaching amount (solid line) and the accumulated Ca after 15 consecutive reaction cycles. 2+ Leaching amount (dashed line).

[0024] Figure 5 The surface electronegativity of CaMnO3 and Ca during the reaction process 2+ The change in leaching amount over time.

[0025] Figure 6 The effect of CaMnO3 addition amount on the removal efficiency of EDTA-Pb in CaMnO3 / PMS system.

[0026] Figure 7 The effect of PMS concentration on the removal of EDTA-Pb by the CaMnO3 / PMS system.

[0027] Figure 8 The effect of initial pH on the removal of EDTA-Pb by the CaMnO3 / PMS system was investigated.

[0028] Figure 9 The effect of CaMnO3 / PMS system on the removal of heavy metals in different organic complex states. Detailed Implementation

[0029] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0030] Unless otherwise specified, all reagents or medicines used in the embodiments of this invention are commercially available. For conditions not specifically stated in the embodiments, conventional conditions or conditions recommended by the manufacturer should be followed. Instruments used, unless otherwise specified by manufacturer, are all commercially available conventional products.

[0031] Example 1 1. Experimental Methods This embodiment explores the possibility of removing organically complexed heavy metal lead EDTA-Pb using the AMnO3 / PMS system.

[0032] (1) Preparation of CaMnO3 materials First, CaMnO3 material with Ca at the A-site was prepared as follows: Calcium nitrate tetrahydrate and manganese nitrate were added to 10 mL of deionized water, with a total molar amount of 4 mmol of metallic Ca and Mn. The ratio of calcium nitrate tetrahydrate to manganese nitrate added in the synthesis of CaMnO3 was 1:1. 8 mmol of citric acid and 2 mL of ethylene glycol were added, and the mixture was stirred at 85 °C to dissolve it into a homogeneous solution. The solution was then placed in an oven at 80 °C for 16 h to obtain a homogeneous colloid. The obtained colloid was transferred to a quartz crucible and placed in a muffle furnace for calcination according to a set program: the temperature was increased to 400 °C at a rate of 2 °C / min and held for 2 h, then increased to 900 °C at a rate of 5 °C / min and held for 3 h. Finally, the temperature was cooled to room temperature at a rate of 5 °C / min. The calcined sample was collected and ground to obtain the CaMnO3 material.

[0033] (2) EDTA Preparation of Pb solution EDTA used in this embodiment Pb was prepared by mixing ethylenediaminetetraacetic acid and lead nitrate in a 1:1 molar ratio and allowing it to stand at room temperature for 48 h to obtain 0.05 mmol / L EDTA. Pb solution was used as the reaction solution for subsequent organic complexed heavy metal reactions.

[0034] (3) The specific experimental steps for removing organic complexed heavy metal Pb (EDTA-Pb) by CaMnO3-activated PMS are as follows: 0.75 g / L CaMnO3 was added to an aqueous solution containing EDTA-Pb (0.05 mmol / L, initial pH approximately 4.0), and ultrasonically vibrated for 3 min to uniformly disperse the material. Stirring was continued for 60 min until EDTA-Pb reached adsorption equilibrium on the material surface. Then, 1.2 mmol / L PMS was added to the suspension to initiate the reaction and the timing was started. The reaction temperature was approximately 25℃, and the reaction time was 60 min.

[0035] (4) Testing of the types of intermediate products and active substances produced by the system Reaction solutions at different reaction times were collected, and macromolecular intermediates and small molecules such as formic acid and acetic acid were detected using ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (HPLC-QTOF) and ion chromatography (IC) to obtain the evolution of intermediates and reveal the oxidation and breakdown process of complexed heavy metals. Electron paramagnetic resonance (EPR) detection, quenching experiments (with the addition of ethanol, tert-butanol, p-benzoquinone, sodium azide, furfuryl alcohol, etc.), and oxidation kinetics of probe compounds (nitrobenzene, benzoic acid, etc.) were used to test the types of active substances generated in the system.

[0036] 2. Experimental Results (1) The preparation results of CaMnO3 material are as follows Figure 1 As shown in the diffraction pattern, the pure phase CaMnO3 material without impurities was successfully synthesized.

[0037] (2) such as Figure 2 As shown, the oxidant PMS alone cannot remove Pb from water in the form of precipitation; CaMnO3 has a certain adsorption effect on EDTA-Pb, reaching adsorption equilibrium within 30-60 min, with a Pb removal rate of approximately 20% in the solution. However, when CaMnO3 and the oxidant PMS are present simultaneously, the concentration of total Pb (including complexed and free states) in the solution decreases rapidly, and the EDTA-Pb removal rate reaches 100% after 30 min of reaction, indicating that the CaMnO3 / PMS system has excellent performance in removing organically complexed heavy metal EDTA-Pb.

[0038] Tests on intermediate products and the types of active substances produced by the system showed that the CaMnO3 / PMS system produced SO4. • HO • O2• ,and 1 The mechanism by which reactive oxygen species such as O2 first oxidize the organic ligands in EDTA-Pb, thereby breaking down the EDTA-Pb complex and releasing free Pb.2+ Free Pb 2+ Adsorbed onto CaMnO3 material, thus achieving the removal of organically complexed heavy metal EDTA-Pb from aqueous solution.

[0039] Example 2 This embodiment investigates the effect of CaMnO3 recycling on the removal of EDTA-Pb and the promoting effect of A-site Ca leaching on the removal of EDTA-Pb in the system.

[0040] 1. Experimental Methods The preparation method of CaMnO3 in this embodiment is the same as that in Example 1. In order to compare and evaluate the efficiency of perovskite oxide CaMnO3 in activating PMS to remove EDTA-Pb and the promoting effect of A-site Ca leaching on the removal of EDTA-Pb, the comparative material β-MnO2 was synthesized by hydrothermal method. The specific method is as follows: 16 mmol of (NH4)2S2O8 and MnSO4·H2O were added to 80 mL of deionized water to dissolve and obtain a homogeneous solution. The solution was transferred to 150 mL of Teflon-lined container, sealed and placed in a stainless steel high-pressure reactor. The reaction was carried out at 140℃ for 12 h. After cooling to room temperature, the obtained sample was filtered, washed and dried to obtain β-MnO2.

[0041] The recyclability of the material is an important parameter for evaluating its performance. Each cycle lasted 60 minutes. After the reaction, the material was thoroughly washed with ultrapure water and directly added to the next cycle without any desorption. The specific experimental procedures for each cycle were as follows: 0.75 g / L CaMnO3 or β-MnO2 was added to an aqueous solution containing EDTA-Pb (0.05 mmol / L, initial pH approximately 4.0). The solution was ultrasonically agitated for 3 minutes to ensure uniform dispersion, and then stirred continuously for 60 minutes to allow EDTA-Pb to reach adsorption equilibrium on the material surface. Then, 1.2 mmol / L PMS was added to the suspension to initiate the reaction and the timing was started. The reaction temperature was approximately 25°C, and the reaction time was 60 minutes.

[0042] 2. Experimental Results The experimental results are as follows Figure 3As shown, the CaMnO3 material exhibits excellent recyclability. In the first 11 cycles, the system maintained high performance in removing EDTA-Pb through complex disruption. With further increases in the number of cycles, the reaction rate for total Pb removal slowed down, but within 60 min, the removal rates of dissolved Pb in the 12th, 13th, 14th, and 15th cycles remained as high as 98.7%, 98.9%, 94.2%, and 88.2%, respectively. With increasing cycles, more and more free Pb is released from the EDTA-Pb complex. 2+ Adsorbed on the surface of the material, the Pb content on the material gradually accumulates. Considering the overall efficiency of the cyclic removal of EDTA-Pb, it can be calculated that, under the above reaction conditions, in 15 consecutive cycles, the effect of CaMnO3-activated PMS on the removal of free Pb from the EDTA-Pb complex can be significantly reduced. 2+ The cumulative adsorption and fixation amount is at least 200 mg / g, and the Pb adsorbed on the material is at least 200 mg / g. 2+ It will not be released back into the environment and cause secondary pollution. In contrast, the removal rate of EDTA-Pb by the β-MnO2 / PMS system decreased rapidly with the progress of the cycle reaction. In the first reaction, 100% of EDTA-Pb was removed within 10 minutes. In the second cycle reaction, 42% of Pb was removed after 60 minutes. In the fourth cycle reaction, the removal rate of total Pb in the solution by the β-MnO2 / PMS system was only 18%. Its effect and cumulative amount of EDTA-Pb removal by recycling was about 25 mg / g, which is much lower than the removal effect and cumulative amount of EDTA-Pb in aqueous solution of the CaMnO3 / PMS system in this invention (200 mg / g).

[0043] As shown above, in the first reaction, the β-MnO2 / PMS system exhibits better removal efficiency for EDTA-Pb than the CaMnO3 / PMS system. However, its cumulative removal of EDTA-Pb in subsequent cycles is significantly lower than that of the CaMnO3 / PMS system. Specific surface area (SSA) measurements indicate that the initial SSA of β-MnO2 is 13.2 m². 2 / g, after 4 reactions, its SSA did not change much, while the initial specific surface area of ​​CaMnO3 was 7.5m². 2 / g, after 15 cycles of reaction, its specific surface area increased to 121.4 m². 2 / g, this is due to the continuous leaching of Ca element at site A during the reaction process ( Figure 4 This increases the number of nanopores and amorphous layers in the material's microstructure, expanding the SSA of the material and facilitating the activation of PMS, which in turn oxidizes and breaks down the EDTA-Pb complex and releases free Pb. 2+ The adsorption provides more active sites. On the other hand, the negative charge on the material surface affects the positive charge of Pb.2+ The adsorption of Pb was measured by Zeta potential analysis. The initial surface potential of β-MnO2 was 20 mV. After the first reaction, Pb was adsorbed. 2+ The surface potential of β-MnO2 increases to 40 mV, which is clearly unfavorable for the release of free Pb in subsequent cyclic reactions. 2+ The adsorption of CaMnO3. However, for CaMnO3 materials, as the reaction proceeds, due to the adsorption of Ca... 2+ Continuous leaching ( Figure 5 Its surface electronegativity gradually increases, and Pb is adsorbed in the first reaction. 2+ Even afterward, its surface can still maintain a strong negative charge, which is highly beneficial for the material's ability to handle the released free Pb during the reaction process. 2+ The adsorption of Ca at the A-site in the perovskite structure significantly enhances the efficiency of the AMnO3 / PMS system in one-step oxidation-complexation / adsorption removal of organically complexed heavy metal EDTA-Pb.

[0044] Example 3 This embodiment investigates the effect of different CaMnO3 addition amounts on the removal of EDTA-Pb by the CaMnO3 / PMS system.

[0045] 1. Experimental Methods The preparation method of CaMnO3 in this embodiment is the same as that in Example 1.

[0046] The specific experimental steps for removing EDTA-Pb by CaMnO3-activated PMS under different CaMnO3 addition conditions are as follows: 0.1, 0.25, 0.5, 0.75, and 1 g / L of CaMnO3 were added to an aqueous solution containing EDTA-Pb (0.05 mmol / L, initial pH approximately 4.0). The solution was ultrasonically agitated for 3 min to ensure uniform dispersion, and then continuously stirred for 60 min to allow EDTA-Pb to reach adsorption equilibrium on the material surface. Then, 1.2 mmol / L of PMS was added to the suspension to initiate the reaction, and timing was started. The reaction temperature was approximately 25℃, and the reaction time was 60 min.

[0047] Results analysis: such as Figure 6As shown, the removal efficiency of EDTA-Pb in the solution increases with the increase of the initial amount of CaMnO3. Under the conditions of EDTA-Pb concentration and PMS concentration of 1.2 mmol / L, as the initial amount of CaMnO3 increases from 0.1 g / L to 0.5 g / L, the removal rate of EDTA-Pb in the system increases from 51% (60 min) to 99% (30 min). When the initial amount of CaMnO3 is further increased to 0.75 g / L and 1 g / L, the removal rate of EDTA-Pb in the system can reach 100% in 10 min.

[0048] Example 4 This embodiment investigates the effect of different PMS concentrations on the removal of EDTA-Pb by the CaMnO3 / PMS system.

[0049] 1. Experimental Methods The preparation method of CaMnO3 in this embodiment is the same as that in Example 1.

[0050] The specific experimental steps for removing EDTA-Pb by CaMnO3-activated PMS under different PMS concentrations are as follows: 0.75 g / L CaMnO3 was added to an aqueous solution containing EDTA-Pb (0.05 mmol / L, initial pH approximately 4.0), and the mixture was ultrasonically agitated for 3 min to ensure uniform dispersion. Stirring was continued for 60 min until EDTA-Pb reached adsorption equilibrium on the material surface. Then, 0.4, 0.8, 1.2, and 1.6 mmol / L PMS were added to the suspension to initiate the reaction, and timing was started. The reaction temperature was approximately 25℃, and the reaction time was 60 min.

[0051] 2. Experimental Results Experimental results are as follows Figure 7 As shown, with an addition of 0.75 g / L CaMnO3, the removal rate of EDTA-Pb in the system first increased and then remained constant with the increase of PMS concentration. This indicates that the number of active sites on the material surface and the concentration of oxidant jointly determine the removal rate of EDTA-Pb in the system.

[0052] Example 5 This embodiment investigates the effect of different initial reaction pH on the removal of EDTA-Pb by the CaMnO3 / PMS system.

[0053] 1. Experimental Methods The preparation method of CaMnO3 in this embodiment is the same as that in Example 1.

[0054] The specific experimental steps for removing EDTA-Pb by CaMnO3-activated PMS under different initial reaction pH conditions are as follows: 0.75 g / L CaMnO3 was added to an aqueous solution containing EDTA-Pb (0.05 mmol / L), and the solution was ultrasonically vibrated for 3 min to ensure uniform dispersion. The pH of the solution was adjusted to 4.0, 5.0, 7.0, and 9.0 using HNO3 or NaOH, and the solution was stirred continuously for 60 min to allow EDTA-Pb to reach adsorption equilibrium on the material surface. Then, 1.2 mmol / L PMS was added to the suspension to initiate the reaction and the timing was started. The reaction temperature was approximately 25℃, and the reaction time was 60 min.

[0055] 2. Experimental Results The results are as follows Figure 8 As shown, the initial pH of the solution has little effect on the efficiency of Pb removal by the CaMnO3 / PMS system. This is mainly because the added oxidant PMS itself acidifies the solution; after adding PMS, the actual pH of the reaction solution is maintained at around 3.2. This indicates that the CaMnO3 / PMS system can effectively remove EDTA-Pb from water over a relatively wide pH range.

[0056] Example 6 This embodiment explores the effect of the CaMnO3 / PMS system on removing heavy metals in different organic complex states.

[0057] 1. Experimental Methods The preparation method of CaMnO3 in this embodiment is the same as that in Example 1.

[0058] The specific experimental steps for removing different organic complexed heavy metals by activating PMS with CaMnO3 are as follows: 0.75 g / L CaMnO3 was added to an aqueous solution containing EDTA-Cu, EDTA-Cd, or EDTA-Zn (all at a concentration of 0.05 mmol / L). The solution was ultrasonically vibrated for 3 min to ensure uniform dispersion, and then continuously stirred for 60 min to allow EDTA-Pb to reach adsorption equilibrium on the material surface. Then, 1.2 mmol / L PMS was added to the suspension to initiate the reaction, and the reaction time was started. The reaction temperature was approximately 25℃, and the reaction time was 60 min.

[0059] 2. Experimental Results Experimental results are as follows Figure 9As shown, the CaMnO3 / PMS system exhibited varying removal capabilities for different organically complexed heavy metals. The adsorption capacity of CaMnO3 for EDTA-Cu, EDTA-Cd, or EDTA-Zn was less than 10% (adsorption time 60 min). With the addition of PMS, the system showed high removal rates for different heavy metals in the initial reaction stage. Within 60 min, the removal rates of heavy metals in EDTA-Cu, EDTA-Cd, and EDTA-Zn pollutant solutions (0.05 mM) were 70%, 80%, and 55%, respectively, showing a significant difference in removal efficiency. This is most likely due to the different adsorption capacities of CaMnO3 for different heavy metal ions. Nevertheless, the CaMnO3 / PMS system still maintained a superior removal effect for different organically complexed heavy metals. It is worth noting that appropriately increasing the amount of CaMnO3 added, the concentration of PMS, and extending the reaction time can improve the removal efficiency of the system for EDTA-Cu, EDTA-Cd, or EDTA-Zn.

[0060] Example 7 This embodiment investigates the effect of the AMnO3 / PMS system (where A is one of Mg, Sr, or Ba) on the removal of heavy metals in different organic complex states.

[0061] 1. Experimental Methods The preparation method of AMnO3 in this embodiment is basically the same as that in Example 1, except that calcium nitrate tetrahydrate is replaced with magnesium nitrate, barium nitrate or strontium nitrate.

[0062] The specific experimental steps for removing different organic complexed heavy metals by activating PMS with AMnO3 (where A is one of Mg, Sr, or Ba) are as follows: 0.75 g / L AMnO3 was added to an aqueous solution containing EDTA-Pb (0.05 mmol / L, initial pH approximately 4.0). The solution was ultrasonically vibrated for 3 min to ensure uniform dispersion, and then continuously stirred for 60 min to allow EDTA-Pb to reach adsorption equilibrium on the material surface. Then, 1.2 mmol / L PMS was added to the suspension to initiate the reaction, and the reaction time was started. The reaction temperature was approximately 25℃, and the reaction time was 60 min.

[0063] 2. Experimental Results AMnO3 with A being Mg, Sr, or Ba all exhibit some adsorption activity for EDTA-Pb, reaching adsorption equilibrium within 30–60 min, with a Pb removal rate of approximately 10–20% in the solution. However, when AMnO3 and the oxidant PMS are present simultaneously, the removal rate of EDTA-Pb in the solution reaches 100% with increasing reaction time, indicating that the AMnO3 / PMS system possesses the ability to remove organically complexed heavy metal EDTA-Pb.

[0064] 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 the solutions. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention based on the understanding of the present invention, without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A one-step method for removing organically complexed heavy metals based on an AMnO3 / PMS system, characterized in that, Including the following steps: After mixing perovskite transition metal oxide AMnO3 with a solution containing organically complexed heavy metals, oxidant PMS is added to oxidize and break down the organically complexed heavy metals, releasing free heavy metal ions, and simultaneously adsorbing and removing the released heavy metal ions; the A-site element in the perovskite transition metal oxide AMnO3 is a reactive alkaline earth metal element.

2. The method according to claim 1, characterized in that, The organic complexed heavy metal is any one of EDTA-Pb, EDTA-Cu, EDTA-Cd, or EDTA-Zn.

3. The method according to claim 1, characterized in that, The A-site element in the perovskite transition metal oxide AMnO3 is selected from alkaline earth metals Ca, Mg, Sr, or Ba.

4. The method according to claim 1, characterized in that, The concentration of the organic complexed heavy metal solution is 0.01~0.1 mmol / L; the amount of perovskite transition metal oxide AMnO3 added is 0.1~1 g / L; and the amount of PMS added is 0.4~1.6 mmol / L.

5. The method according to claim 1, characterized in that, The perovskite transition metal oxide AMnO3 is mixed with a solution containing organic complexed heavy metals and then dispersed by ultrasonication. The ultrasonic power is 50~200 W and the ultrasonication time is 2~10 min.

6. The method according to claim 1, characterized in that, The initial pH of the solution after mixing the perovskite transition metal oxide AMnO3 with a solution containing organic complexed heavy metals is 4.0~9.

0.

7. The method according to claim 1, characterized in that, After adding the oxidant PMS, the reaction conditions are as follows: reaction for 1-4 hours under continuous magnetic stirring, magnetic stirring speed of 400-1000 rpm, and reaction temperature of 20-35℃.

8. The method according to claim 3, characterized in that, The perovskite transition metal oxide AMnO3 is prepared by the following steps: S1. Add the hydrates of calcium nitrate, magnesium nitrate, strontium nitrate, or barium nitrate to the solvent along with manganese nitrate, ferric nitrate, and organic acid, and stir until homogeneous. S2. The obtained solution is heated at 60~100℃ for 6~48 h to obtain a homogeneous colloid; S3. The colloid is calcined at 800~1200℃ for 2~6 h to obtain perovskite transition metal oxide AMnO3.

9. The method according to claim 8, characterized in that, The organic acid in step S1 is citric acid or acetic acid; the amount of organic acid added is 1 to 4 times the metal ion equivalent; the solvent in step 1 is an alcohol-water mixed solution, and the alcohol is ethylene glycol; the mixing ratio of the alcohol and water is 1:1 to 1:5; the heating rate for calcination in step S1 is 2 to 10 °C / min.

10. The application of the perovskite transition metal oxide AMnO3 and PMS advanced oxidation system in the removal of organically complexed heavy metals, characterized in that, The perovskite transition metal oxide AMnO3 is mixed with a solution containing organically complexed heavy metals, and then the oxidant PMS is added to oxidize and break down the organically complexed heavy metals, releasing free heavy metal ions. At the same time, the released heavy metal ions are adsorbed and removed, thus achieving a one-step removal of organically complexed heavy metals.

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