Preparation method, product and application of a heterogeneous persulfate activator FeLaO@bentonite

Abstract

The present application relates to a kind of preparation method of heterogeneous persulfate activator FeLaO bentonite, product and application, heterogeneous persulfate activator FeLaO bentonite is doped with rare earth metal La and is supported on carbon modified bentonite, not only help to improve Fe active site quantity, and the synergistic effect between them can enhance the structural stability of activator;Based on the modification of carbon material, the adsorption capacity of bentonite is increased, the material skeleton structure is stable, and can be repeatedly used after high-temperature activation.The present application not only effectively increases specific surface area, but also can effectively avoid the agglomeration of active component, beneficial to stimulate persulfate activator to form more active oxygen species, accelerate the removal of pollutants, especially for the oxidation efficiency of secondary phosphorus is remarkable, effectively promote the removal amount of total phosphorus reaches 100%, and has the characteristics of high efficiency, controllable, and sludge has the value of reuse.

Description

TECHNICAL FIELD

[0001] The present application relates to a preparation method of a heterogeneous persulfate activator FeLaO bentonite, and products and applications thereof, which utilizes intermetallic synergistic effect and immobilization treatment to further improve the activation efficiency of active species, accelerate the removal of total phosphorus in water, and is used in the field of wastewater treatment. BACKGROUND

[0002] Phosphorus is the main source of water eutrophication, if the content of total phosphorus in water exceeds 0.2 mg / L, it will cause excessive proliferation of algae, cause aquatic organisms to suffocate due to lack of oxygen, and seriously damage the balance of the original water body. In addition, aquatic organisms will also decompose and produce toxic and harmful gases such as hydrogen sulfide, which will cause further deterioration of water quality. The comprehensive treatment of phosphorus-containing wastewater is of great importance to the balance of the ecological system and human health.

[0003] At present, the key technology for removing phosphorus is mainly to utilize the chemical precipitation reaction of phosphorus to convert the soluble phosphorus in wastewater into insoluble phosphate precipitate, or to utilize biological phosphorus removal to absorb phosphorus into sludge, but this method has poor stability and is difficult to achieve the first-level discharge standard. However, for electroplating wastewater, the phosphorus therein is mostly in the form of complex state, and the conventional chemical precipitation for removing phosphorus cannot achieve the removal purpose. Studies have shown that the complex-state phosphorus can be first oxidized to generate orthophosphate, and then a precipitant is added to form insoluble substances to realize solid-liquid separation, so as to achieve the goal of total phosphorus removal.

[0004] Advanced oxidation technology is a kind of deep oxidation technology, which can oxidize macromolecular refractory organic matter into low-toxic or non-toxic small molecules by generating hydroxyl radicals with strong oxidizing properties. The generation of free radicals is diverse, which can be generated by electricity, light, ultrasound, catalyst and other ways. In recent years, with the in-depth research, persulfate advanced oxidation technology has attracted widespread attention from researchers. Compared with hydroxyl radicals, sulfate radicals have higher oxidation-reduction potential, longer half-life and wider pH range, and are called alternative technology of hydroxyl radical advanced oxidation technology. The free radicals can be generated by activating peroxymonosulfate (PMS, oxidation-reduction potential is 2.01 V) and peroxodisulfate (PS, oxidation-reduction potential is 1.82 V), and can effectively oxidize and decompose organic pollutants by using its strong oxidizing property. In the past few decades, people have explored many ways to activate PS, among which energy (such as light, heat, ultrasound, electrochemistry and related combinations) activation is the most traditional, but the poor activation efficiency limits its practical application. At present, using catalyst to chemically activate PS is a more economical, faster and more effective strategy than other methods, because it is simple in process, eco-friendly, low in energy consumption and recyclable. For the selection of catalyst, its stability and catalytic activity are the most important consideration factors. Among many catalysts, Fe-based catalysts are favored because of their wide source, low cost and simple process. However, when traditional Fe-based materials are directly used for PS activation, the metal dissolution will cause secondary pollution of water quality and decrease of catalytic activity. Therefore, the application patent enhances the synergistic effect between metal interfaces by doping rare earth La to reduce the dissolution rate of metal and improve the activation efficiency of persulfate activator. At the same time, in order to realize the recycling of the activator, it is fixed on bentonite, which not only can realize fast solid-liquid separation, but also can increase the contact area between pollutants and active components, further improving the oxidation efficiency of total phosphorus. SUMMARY

[0005] In view of the poor activation efficiency of Fe-based persulfate activator, and the metal Fe species dissolved in the recycling of the activator will cause significant decrease of the activation efficiency and also cause secondary pollution of water quality. Therefore, the application promotes the stability by using the synergistic effect between metals, and the introduction of rare earth metal La can also increase the formation of active sites, and promotes the recycling of powder materials under the fixation of modified bentonite, which has great guiding significance for practical application, and the application aims to provide a preparation method of heterogeneous persulfate activator FeLaO@bentonite.

[0006] Still another object of the application is to provide a heterogeneous persulfate activator FeLaO@bentonite product prepared by the above method.

[0007] Still another object of the application is to provide an application of the above product.

[0008] The object of the present application is achieved by the following scheme: a heterogeneous persulfate activator FeLaO@bentonite, which utilizes the doping of rare earth metal La to synergize with Fe species to promote the formation of active sites, and is supported on carbon modified bentonite, which not only effectively increases the specific surface area, but also effectively avoids the agglomeration of active components, is conducive to the formation of more active oxygen species by activating persulfate, and accelerates the removal of pollutants, comprising the following steps:

[0009] A preparation method of a heterogeneous persulfate activator FeLaO@bentonite, characterized by utilizing the doping of rare earth metal La to synergize with Fe species to promote the formation of active sites, and being supported on carbon modified bentonite, comprising the following steps:

[0010] (1) 100 mesh or so of bentonite is placed in a muffle furnace and calcined for 2 h, and after cooling, it is sieved for use;

[0011] (2) C3N4 powder is added to the bentonite, and after grinding and mixing, it is placed in a muffle furnace for calcination treatment, and calcined at 90-150 ℃ for 1-3 h to obtain carbon modified bentonite;

[0012] (3) Under magnetic stirring, Fe(NO3)3·9H2O and La(NO3)3·6H2O are dissolved in deionized water according to a Fe / La molar ratio of 1:(0.1-1), and NaOH is added to adjust the pH to 7-11 to obtain a mixed solution;

[0013] (4) Under a water bath at 60-90 ℃, the carbon modified bentonite is added to the mixed solution of (3), and is fully stirred and mixed, and reacts for 0.5-2 h;

[0014] (5) After the reaction is completed, the product is filtered and washed, and after drying, it is placed in a tube furnace and calcined at 300-500 ℃ for 2-6 h to obtain the FeLaO@bentonite persulfate activator.

[0015] In step (2), the mass ratio of bentonite to C3N4 is 100:(2-10), and the calcination temperature and time are 90-150 ℃ and 1-3 h.

[0016] In steps (2) and (5), the calcination atmosphere is one of N2 or air.

[0017] The present application provides a heterogeneous persulfate activator FeLaO@bentonite obtained according to the above method.

[0018] The present application also provides a heterogeneous persulfate activator FeLaO@bentonite for removing total phosphorus in wastewater.

[0019] The activation degradation performance test of the FeLaO@bentonite activator is carried out in a beaker, 100 mg of the activator is added into 100 mL of 100 mg / L hypophosphite wastewater, 5 mM of potassium peroxodisulfate is added, stirring is carried out for 15 min, the supernatant is taken by centrifugation, a certain amount of CaO is added, stirring is carried out, the pH is adjusted to about 8, the supernatant is taken by centrifugation, the oxidation efficiency of the activator on the hypophosphite is determined, and the removal rate of total phosphorus is calculated.

[0020] The doping of the rare earth metal La not only helps to increase the number of Fe active sites, but also enhances the structural stability of the activator through the synergistic effect between the two. Further, based on the modification of the carbon material, the adsorption capacity of the bentonite is increased, the material skeleton structure is stable, and the material can be repeatedly used after high-temperature activation. Compared with the prior art, the activator disclosed in the application can quickly excite the decomposition of persulfate to produce strong oxidizing active oxygen species, the oxidation efficiency on the hypophosphite is significantly improved, the removal amount of total phosphorus is effectively promoted to 100%, and the activator has the characteristics of high efficiency and controllability.

[0021] The application has the following advantages:

[0022] (1) The application provides a preparation method and application of a heterogeneous persulfate activator FeLaO@bentonite. The modified porous bentonite is used as a substrate, and a supported FeLaO@bentonite material is synthesized by one-pot method. Through the synergistic effect between the two metals, the formation of active sites is accelerated and the stability of the activator structure is enhanced, metal dissolution is avoided, and the contact area between the pollutants, the activator and the persulfate is increased under the action of the carrier, which is beneficial to promote the activation of the persulfate to produce active oxygen species and shorten the activation reaction time.

[0023] (2) The application provides a heterogeneous persulfate activator FeLaO@bentonite. The layered structure C3N4 is used to modify the bentonite, which not only effectively increases the specific surface area of the bentonite, but also effectively coats the FeLaO active species with the carbon-based material to enhance the structural stability.

[0024] (3) The FeLaO@bentonite activator has a wide source of raw materials, no harm to the environment, a large specific surface area of the activator, and a stable structure, and is a persulfate activation material with excellent performance. DETAILED DESCRIPTION

[0025] The application is further illustrated by the examples.

[0026] In the following examples, the calcination atmosphere is not specified, i.e. the calcination atmosphere is air.

[0027] Example 1

[0028] A heterogeneous persulfate activator FeLaO@bentonite, which utilizes the doping of rare earth metal La to promote the formation of active sites in cooperation with Fe species and is supported on carbon modified bentonite, is prepared by the following steps:

[0029] (1) 100 mesh or so of bentonite is placed in a muffle furnace and calcined for 2 h, and after cooling, it is sieved for use;

[0030] (2) C3N4 powder with a mass ratio of 100:5 is added to the bentonite, and after grinding and mixing, it is placed in a muffle furnace for calcination treatment, calcined at 90°C for 1 h, to obtain carbon modified bentonite;

[0031] (3) Under magnetic stirring, Fe(NO3)3·9H2O and La(NO3)3·6H2O are dissolved in deionized water according to a Fe / La molar ratio of 1:1, and NaOH is added to adjust the pH to 8, to obtain a mixed solution;

[0032] (4) Under a 60°C water bath, carbon modified bentonite is added to the mixed solution of (3) and stirred thoroughly for 2 h;

[0033] (5) After the reaction is completed, the product is filtered and washed, dried, and then placed in a tube furnace for calcination treatment, with N2 as the calcination atmosphere, calcined at 500°C for 2 h, to obtain the FeLaO@bentonite persulfate activator.

[0034] The prepared persulfate activator has a total phosphorus removal rate of 90%.

[0035] Example 2

[0036] A heterogeneous persulfate activator FeLaO@bentonite, which utilizes the doping of rare earth metal La to promote the formation of active sites in cooperation with Fe species and is supported on carbon modified bentonite, is prepared by the following steps:

[0037] (1) 100 mesh or so of bentonite is placed in a muffle furnace and calcined for 2 h, and after cooling, it is sieved for use;

[0038] (2) C3N4 powder with a mass ratio of 100:10 is added to the bentonite, and after grinding and mixing, it is placed in a muffle furnace, calcined at 110°C for 2 h, to obtain carbon modified bentonite;

[0039] (3) Under magnetic stirring, Fe(NO3)3·9H2O and La(NO3)3·6H2O are dissolved in deionized water according to a Fe / La molar ratio of 1:0.5, and NaOH is added to adjust the pH to 9, to obtain a mixed solution;

[0040] (4) Under a water bath, carbon modified bentonite is added to the mixed solution of (3) and stirred thoroughly for 2 h at 80°C;

[0041] (5) After the reaction is completed, the product is filtered, washed, dried, and then placed in a tube furnace for calcination treatment, the calcination atmosphere is N2, and the calcination is performed at 500°C for 2h, to obtain the FeLaO@bentonite persulfate activator.

[0042] The prepared persulfate activator has a total phosphorus removal rate of 100%.

[0043] Example 3

[0044] A heterogeneous persulfate activator FeLaO@bentonite is prepared according to the following steps similar to the steps of Example 1:

[0045] (1) 100-mesh bentonite is placed in a muffle furnace and calcined for 2h, and then sieved after cooling for use;

[0046] (2) C3N4 powder with a mass ratio of 100:10 is added to the bentonite, and after grinding and mixing, the mixture is placed in a muffle furnace and calcined at 110°C for 2h to obtain carbon-modified bentonite;

[0047] (3) Under magnetic stirring, Fe(NO3)3·9H2O and La(NO3)3·6H2O are dissolved in deionized water according to a molar ratio of Fe / La of 1:1, and NaOH is added to adjust the pH to 9 to obtain a mixed solution;

[0048] (4) Under water bath, the carbon-modified bentonite is added to the mixed solution in (3) and stirred at 80°C for 2h;

[0049] (5) After the reaction is completed, the product is filtered, washed, dried, and then placed in a tube furnace for calcination treatment, the calcination atmosphere is N2, and the calcination is performed at 500°C for 2h, to obtain the FeLaO@bentonite persulfate activator.

[0050] The prepared persulfate activator has a total phosphorus removal rate of 100%.

[0051] Example 4

[0052] A heterogeneous persulfate activator FeLaO@bentonite is prepared according to the following steps similar to the steps of Example 1:

[0053] (1) 100-mesh bentonite is placed in a muffle furnace and calcined for 2h, and then sieved after cooling for use;

[0054] (2) C3N4 powder with a mass ratio of 100:2 is added to the bentonite, and after grinding and mixing, the mixture is placed in a muffle furnace and calcined at 100°C for 2h to obtain carbon-modified bentonite;

[0055] (3) Fe(NO3)3·9H2O and La(NO3)3·6H2O were dissolved in deionized water under magnetic stirring according to the Fe / La molar ratio of 1:0.5, and NaOH was added to adjust the pH to 9 to obtain a mixed solution;

[0056] (4) The carbon-modified bentonite was added to the mixed solution in (3) under water bath at 60°C, and was fully stirred and mixed for 0.5 h;

[0057] (5) After the reaction was completed, the product was filtered and washed, and was dried and then placed in a tube furnace for calcination treatment, the calcination atmosphere was air, and the calcination was performed at 350°C for 4 h, and thus the FeLaO@bentonite persulfate activator was obtained.

[0058] The prepared persulfate activator had a total phosphorus removal rate of 87%.

Claims

1. A preparation method of a heterogeneous persulfate activator FeLaO@bentonite, characterized in that, Utilizing the doping of rare earth metal La to promote the formation of active sites in cooperation with Fe species and supporting on carbon modified bentonite, comprising the following steps: (1) bentonite of 100 mesh is placed in a muffle furnace and calcined for 2 h, and after cooling, it is sieved for use; (2) C3N4 powder is added to the bentonite, and the mass ratio of the bentonite and C3N4 is 100: (2-10), after grinding and mixing, it is placed in a muffle furnace and calcined at 90-150 ℃ for 1-3 h to obtain carbon modified bentonite; (3) under magnetic stirring, Fe(NO3)3·9H2O and La(NO3)3·6H2O are dissolved in deionized water according to a Fe / La molar ratio of 1: (0.1-1), and NaOH is added to adjust the pH to 7-11 to obtain a mixed solution; (4) under a water bath at 60-90 ℃, the carbon modified bentonite is added to the mixed solution of (3), and stirred and mixed thoroughly, and reacted for 0.5-2 h; (5) after the reaction is completed, the product is filtered and washed, and after drying, it is placed in a tube furnace and calcined at 300-500 ℃ for 2-6 h to obtain a FeLaO@bentonite persulfate activator.

2. The preparation method of the heterogeneous persulfate activator FeLaO@bentonite according to claim 1, characterized in that, In step (5), the calcination atmosphere is one of N2 or air.

3. The preparation method of the heterogeneous persulfate activator FeLaO@bentonite according to claim 1 or 2, characterized in that, Prepared according to the following steps: (1) bentonite of 100 mesh is placed in a muffle furnace and calcined for 2 h, and after cooling, it is sieved for use; (2) C3N4 powder is added to the bentonite, and the mass ratio of the bentonite and C3N4 is 100:5, after grinding and mixing, it is placed in a muffle furnace and calcined at 90 ℃ for 1 h to obtain carbon modified bentonite; (3) under magnetic stirring, Fe(NO3)3·9H2O and La(NO3)3·6H2O are dissolved in deionized water according to a Fe / La molar ratio of 1:1, and NaOH is added to adjust the pH to 8 to obtain a mixed solution; (4) under a water bath at 60 ℃, the carbon modified bentonite is added to the mixed solution of (3), and stirred and mixed thoroughly for 2 h; (5) after the reaction is completed, the product is filtered and washed, and after drying, it is placed in a tube furnace and calcined, the calcination atmosphere is N2, and calcined at 500 ℃ for 2 h to obtain a FeLaO@bentonite persulfate activator.

4. The preparation method of the heterogeneous persulfate activator FeLaO@bentonite according to claim 1 or 2, characterized in that, Prepared according to the following steps: (1) bentonite of 100 mesh is placed in a muffle furnace and calcined for 2 h, and after cooling, it is sieved for use; (2) C3N4 powder is added to the bentonite, and the mass ratio of the bentonite and C3N4 is 100:10, after grinding and mixing, it is placed in a muffle furnace and calcined at 110 ℃ for 2 h to obtain carbon modified bentonite; (3) under magnetic stirring, Fe(NO3)3·9H2O and La(NO3)3·6H2O are dissolved in deionized water according to a Fe / La molar ratio of 1:0.5, and NaOH is added to adjust the pH to 9 to obtain a mixed solution; (4) under a water bath, the carbon modified bentonite is added to the mixed solution of (3), and stirred and mixed thoroughly at 80 ℃ for 2 h; (5) after the reaction is completed, the product is filtered and washed, and after drying, it is placed in a tube furnace and calcined, the calcination atmosphere is N2, and calcined at 500 ℃ for 2 h to obtain a FeLaO@bentonite persulfate activator.

5. The preparation method of the heterogeneous persulfate activator FeLaO@bentonite according to claim 1 or 2, characterized in that, Prepared according to the following steps: (1) 100 mesh bentonite was placed in a muffle furnace and calcined for 2 h, and then sieved after cooling; (2) C3N4 powder with a mass ratio of 100:10 was added to the bentonite, and after grinding and mixing, it was placed in a muffle furnace and calcined at 110°C for 2 h to obtain carbon-modified bentonite; (3) Under magnetic stirring, Fe(NO3)3·9H2O and La(NO3)3·6H2O were dissolved in deionized water according to a Fe / La molar ratio of 1:1, and NaOH was added to adjust the pH to 9 to obtain a mixed solution; (4) Under water bath, the carbon-modified bentonite was added to the mixed solution in (3) and stirred at 80°C for 2 h; (5) After the reaction was completed, the product was filtered and washed, dried, and then calcined in a tube furnace, with air as the calcination atmosphere, at 400°C for 4 h to obtain the FeLaO@bentonite persulfate activator.

6. The preparation method of the heterogeneous persulfate activator FeLaO@bentonite according to claim 1 or 2, characterized in that, Prepared according to the following steps: (1) 100 mesh bentonite was placed in a muffle furnace and calcined for 2 h, and then sieved after cooling; (2) C3N4 powder with a mass ratio of 100:2 was added to the bentonite, and after grinding and mixing, it was placed in a muffle furnace and calcined at 100°C for 2 h to obtain carbon-modified bentonite; (3) Under magnetic stirring, Fe(NO3)3·9H2O and La(NO3)3·6H2O were dissolved in deionized water according to a Fe / La molar ratio of 1:0.5, and NaOH was added to adjust the pH to 9 to obtain a mixed solution; (4) 60°C Under water bath, the carbon-modified bentonite was added to the mixed solution in (3) and stirred for 0.5 h; (5) After the reaction was completed, the product was filtered and washed, dried, and then calcined in a tube furnace, with air as the calcination atmosphere, at 350°C for 4 h to obtain the FeLaO@bentonite persulfate activator.

7. A heterogeneous persulfate activator FeLaO@bentonite, characterized in that Prepared according to the method of any one of claims 1-6.

8. The use of the heterogeneous persulfate activator FeLaO@bentonite according to claim 7 in the removal of total phosphorus from wastewater.