Heavy metal treatment material and preparation and application thereof

Abstract

The application belongs to the field of wastewater treatment, and particularly relates to a preparation method of a heavy metal treatment material. Montmorillonite and hematite are mixed and then calcined in a reducing atmosphere to obtain the heavy metal treatment material. The weight ratio of the montmorillonite to the hematite is 1-9:1, and the temperature in the calcination stage is 300-750 DEG C. The material prepared by the preparation method has excellent removal effects on arsenic, chromium and antimony.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of environmental pollution remediation, and particularly relates to the field of heavy metal treatment materials. BACKGROUND

[0002] Wastewater or soil containing heavy metal ions has become an environmental pollution problem that people pay more and more attention to because of its non-biodegradability and high toxicity. In the past few decades, the discharge of heavy metals in industrial sites has increased significantly, threatening aquatic ecosystems and human health. Unlike organic pollutants, heavy metals cannot be degraded by microorganisms, so they remain unchanged in the environment and accumulate to toxic levels in soil, water and food chains. Once these heavy metals accumulate to a certain extent in the body, they will have a direct impact on the physiological and biochemical functions of the human body. Therefore, it is essential to explore suitable methods to remove heavy metals in actual water bodies. In the natural environment, heavy metal pollutants can only enter the organism from water or soil, accompanied by a change in chemical form, including exchangeable, carbonate-bound, metal-organic complex-bound metals, etc. Long-term accumulation of heavy metals has potential harm to the health of the organism. At present, several methods such as chemical precipitation, ion exchange, electrolysis, oxidation and adsorption have been studied to remove heavy metals in water and wastewater. Adsorption is considered one of the most effective methods for treating heavy metal contaminated water because of its simple operation, low energy consumption, zero secondary pollution, compliance with circular economy and sustainable development requirements. Therefore, it is necessary to develop efficient, environmentally friendly and economical heavy metal adsorbents.

[0003] For the problem of heavy metal treatment, the prior art reports some treatment schemes, for example, the Chinese patent document with publication number CN107803397A discloses a chemical reclamation method for treating heavy metal contaminated on-site soil by using ferromagnetic artificial nodule, which specifically records that the ferromagnetic artificial nodule includes providing a heavy metal adsorbent, such as zeolite, montmorillonite, layered double hydroxide, silicon oxide, aluminum oxide, iron oxide and clock oxide, etc., and also includes being able to provide a ferromagnetic material, such as iron powder, magnetite and magnetic hematite, etc., and mixing the heavy metal adsorbent and the ferromagnetic material. The technology records that the montmorillonite and the magnetic component mixed can be used for adsorption of heavy metals, but the adaptability of the two is not ideal, and the treatment capacity, treatment stability and recycling treatment effect of heavy metals are not ideal. In addition, different heavy metal pollution components have different properties and removal behaviors, and the technical scheme is difficult to play an effective adsorption effect in heavy metal elements such as arsenic, chromium and antimony. SUMMARY

[0004] In view of the deficiencies in the prior art, the first object of the present application is to provide a preparation method of heavy metal treatment material, aiming to obtain a new material with special physicochemical structure characteristics and taking into account excellent removal capacity of arsenic, chromium and antimony, adsorption stability and recycling treatment stability based on the joint synergy of preparation parameters.

[0005] The second object of the present application is to provide the heavy metal treatment material prepared by the preparation method and its application in heavy metal pollutant treatment.

[0006] Although montmorillonite is reported to have a certain heavy metal adsorption capacity, and magnetite has good magnetism, the combination of the two helps to improve the heavy metal adsorption effect, however, the present inventors have found that inappropriate composite process of the two can easily damage the original sheet structure of montmorillonite, in addition, it can also easily encapsulate, solid solution and agglomerate the adsorption sites, making it difficult to truly play the synergistic effect of the two. In addition, different heavy metal pollutants have different properties and different removal behaviors, and inappropriate combination of montmorillonite-iron ore is difficult to truly play a synergistic effect in the removal of arsenic, chromium and antimony, especially for multi-metal systems of arsenic, chromium and antimony, the competition of each metal for the site will further increase the removal difficulty of each other. In view of this problem, the present application has developed the following improved scheme after in-depth research:

[0007] A preparation method of heavy metal treatment material, wherein montmorillonite and hematite are mixed and then calcined in a reducing atmosphere to obtain the heavy metal treatment material.

[0008] The weight ratio of the montmorillonite and the hematite is 1-9:1.

[0009] The temperature of the calcination stage is 300-750 DEG C.

[0010] In view of the problems of difficult to achieve synergistic effect caused by the damage of the original structure, agglomeration and solid solution of the active sites during the combination of montmorillonite and hematite, the present application innovatively mixes the montmorillonite and the hematite and then calcines them together under the atmosphere, and further controls the joint control of the ratio of the two and the temperature of the calcination, so as to unexpectedly achieve the synergistic effect, avoid the damage of the original structure during the combination process, and selectively regulate the phase characteristics of iron to construct rich sites suitable for the treatment of arsenic, chromium and antimony, thereby improving the removal effect of heavy metals, especially arsenic, chromium and antimony, and improving the phase stability of the treatment material, avoiding secondary pollution during the treatment process, and simultaneously improving the recycling treatment capacity.

[0011] In the present application, the synergistic calcination of the components of montmorillonite and hematite and the proportion and temperature control during the treatment process are the key to avoid the damage to the composite stage structure, regulate the physicochemical characteristics, and further improve the removal capacity and stability of arsenic, chromium and antimony. The present application research found that replacing montmorillonite with other similar components, and / or replacing hematite with other iron oxides, and / or the proportion and temperature of the two are not controlled within the range required by the present application, all of which destroy the combined synergy of the process, are not conducive to the maintenance of the composite phase structure, are not conducive to the full construction and exposure of the treatment site, and further are not conducive to the treatment of heavy metals, especially arsenic, chromium and antimony.

[0012] In the present application, the combined synergistic calcination of montmorillonite and hematite is the key to improve the composite synergistic effect of the two. Preferably, the montmorillonite is a calcium-based montmorillonite with a layered structure composed of hydrous aluminosilicate.

[0013] Preferably, the hematite is an oxide mineral of hexagonal system, and the iron content is above 80wt.%.

[0014] In the present application, the synergistic control of the proportion of montmorillonite and hematite helps to solve the problem of damage to the composite structure during the composite process, and can selectively construct and fully expose the treatment site of heavy metals, especially arsenic, chromium and antimony, and further improve the adsorption effect and stability of the prepared treatment agent on heavy metals.

[0015] Preferably, the weight ratio of montmorillonite and hematite is 4-6:1, preferably 4.5-5.5:1. Under the preferred ratio, the process can be further synergized, and the removal capacity of the prepared material on arsenic, chromium and antimony can be further improved.

[0016] In the present application, the montmorillonite and hematite can be combined by known processes, for example, can be mixed by dry or wet ball milling.

[0017] In the present application, the reducing atmosphere is an atmosphere containing hydrogen, preferably a mixture of hydrogen-protection gas;

[0018] Preferably, the protection gas is at least one of nitrogen and inert gas;

[0019] Preferably, in the reducing atmosphere, the content of hydrogen is 5-15V%, preferably 8-12v%.

[0020] During the calcination process, the temperature of the calcination stage is 600-740℃, preferably 680-720℃. Research found that under the preferred temperature, a better synergistic effect can be unexpectedly obtained.

[0021] Preferably, the calcination time is 1-5h, preferably 2-4H.

[0022] Pre-calcination is pre-calcination at a temperature of 150-250 DEG C (further preferably 190-210 DEG C). It is found that the two-stage gradient process of pre-calcination-calcination can unexpectedly further improve the treatment effect, and further improve the treatment capacity of the prepared material, especially the excellent co-treatment effect on arsenic, chromium and antimony.

[0023] Preferably, the pre-calcination time is 1-4 h, and further preferably 1.5-2.5 h.

[0024] The application also provides a heavy metal treatment material prepared by the preparation method.

[0025] In the application, the combination of the preparation method can give the prepared material special physicochemical characteristics, and the special characteristic material prepared by the preparation method can unexpectedly improve the adsorption effect and stability of heavy metals, especially arsenic, chromium and antimony.

[0026] The application also provides a method for removing heavy metals from heavy metal pollutants, which uses the heavy metal treatment material prepared by the preparation method as a treatment agent to remove heavy metals therefrom.

[0027] Preferably, the heavy metal is at least one of arsenic, chromium and antimony.

[0028] Preferably, the heavy metal pollutant is at least one of a solid and / or liquid pollutant containing an excessive amount of heavy metals, preferably heavy metal contaminated soil and heavy metal contaminated wastewater.

[0029] Preferably, the amount of the treatment agent used in the removal process is 0.05 g / L or more, and preferably 0.1-2.0 g / L.

[0030] Compared with the prior art, the application has the following advantages:

[0031] The application innovatively mixes montmorillonite and hematite and then performs calcination treatment under the atmosphere, and further controls the ratio of the two and the temperature of calcination, which unexpectedly realizes synergy, avoids the damage of the original structure in the compounding process, and selectively regulates the phase characteristics of iron to construct rich sites suitable for arsenic, chromium and antimony treatment, thereby improving the removal effect of heavy metals, especially arsenic, chromium and antimony. In particular for multi-metal systems, excellent effects can still be obtained. Furthermore, the treatment agent can improve the phase stability of the treatment material, avoid secondary pollution in the treatment process, and simultaneously improve the recycling capacity.

[0032] The material in the present application has little iron dissolution during the reaction, does not cause secondary pollution problem, and has little negative impact on the environment, and is green and environmentally friendly. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 Scanning electron microscope image of the heavy metal treatment material prepared in Example 1.

[0034] Figure 2 X-ray diffraction pattern of the heavy metal treatment material prepared in Example 1.

[0035] Figure 3 X-ray photoelectron spectroscopy of the heavy metal treatment material prepared in Example 1.

[0036] Figure 4 Adsorption removal efficiency graph of the heavy metal treatment material prepared in Example 1 and its raw materials, Comparative Example 1 and Comparative Example 2 on antimony ions.

[0037] Figure 5 Adsorption effect graph of different systems in Example 1 on arsenic, chromium and antimony. DETAILED DESCRIPTION

[0038] The present application is further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the protection scope of the present application is not limited thereby.

[0039] In the following examples of the present application, unless otherwise specified, the materials and instruments used are commercially available, the processes used are conventional processes, the equipment used is conventional equipment, and the data obtained are the average values of two or more repeated experiments.

[0040] In the present application, the montmorillonite can be a conventional natural montmorillonite. As a typical embodiment, the montmorillonite can be a calcium-based montmorillonite.

[0041] In the present application, the hematite can be a hematite concentrate known in the industry. As an implementable enumeration, in the following cases, unless otherwise specified, the content of iron is 85-90 wt.%.

[0042] First part: material preparation

[0043] Example 1

[0044] (1) Mineral pretreatment:

[0045] The natural montmorillonite and hematite were crushed and sieved to obtain montmorillonite and hematite powder.

[0046] (2) Preparation of heavy metal treatment material:

[0047] The two mineral powders obtained in (1) were mixed in a mass ratio of montmorillonite:hematite = 5:1. The mixture was placed in a tube furnace and heated to 200°C (marked as T1) with a hydrogen-argon mixture (hydrogen content of 10v%) as the calcination atmosphere and held for 2 hours (marked as t1); then heated to 700°C (marked as T2) and held at that temperature for 2 hours (marked as t2), and then naturally cooled to room temperature to obtain a material for heavy metal treatment.

[0048] Figure 1 This is a scanning electron microscope (SEM) image of the heavy metal treatment material prepared in Example 1 of the present invention. From... Figure 1 It can be seen that the layered structure of clay minerals is still preserved, the surface is smooth, and the shape is intact.

[0049] Figure 2 This is an X-ray diffraction pattern of the heavy metal treatment material prepared in Example 1 of the present invention. From... Figure 2 It can be seen that the materials used for heavy metal treatment mainly contain SiO2, MgAl2Si3O 10 The main components are derived from clay minerals, and it also contains Fe derived from iron-based minerals. After high-temperature reduction, the iron content increases significantly.

[0050] Figure 3 This is the X-ray photoelectron spectrum of the heavy metal treatment material prepared in Example 1 of the present invention. From... Figure 3 It can be seen that the iron element in materials used for heavy metal treatment is mainly in the form of Fe, Fe3O4, and Fe2+. 2+ and Fe 3+ It exists in the form of oxides, which can effectively improve the performance of adsorbing and reducing heavy metals.

[0051] Depend on Figures 1-3 It is known that the present invention has successfully prepared materials for heavy metal treatment.

[0052] Example 2 -- Scale

[0053] Compared to Example 1, the only difference is the improved weight ratio of montmorillonite and hematite in step 2. The experimental groups are as follows:

[0054] A: The weight ratio of montmorillonite to hematite is 1:1.

[0055] B: The weight ratio of montmorillonite to hematite is 9:1.

[0056] Other operations and processes are the same as in Example 1.

[0057] Example 3 - Calcination Temperature

[0058] Compared to Example 1, the only difference is that the calcination temperature in step 2 is improved. The experimental groups are as follows:

[0059] A: T2 calcination temperature is 400℃, and the holding calcination time is 4h;

[0060] B: T2 calcination temperature is 600℃, and the holding calcination time is 3h;

[0061] Other operations and processes are the same as those in Example 1.

[0062] Example 4

[0063] Compared with Example 1, the only difference is that t1 in step 2 is improved, and the experimental groups are as follows:

[0064] A: t1 treatment time is 0h;

[0065] B: t1 treatment time is 1h;

[0066] Other operations and processes are the same as those in Example 1.

[0067] Comparative Example 1

[0068] Compared with Example 1, the only difference is that in step 2, hematite is not added, and other operations and parameters are the same as those in Example 1, to obtain modified montmorillonite.

[0069] Comparative Example 2

[0070] Compared with Example 1, the only difference is that in step 2, montmorillonite is not added, and other operations and parameters are the same as those in Example 1, to obtain modified hematite.

[0071] Comparative Example 3

[0072] Compared with Example 1, the only difference is that montmorillonite and hematite are modified according to the process of step 2 respectively, and then physically mixed to obtain a physically mixed modified material, that is, the modified montmorillonite of Comparative Example 1 and the modified hematite are physically mixed, and the mass ratio of the montmorillonite raw material for obtaining the modified montmorillonite and the raw material for obtaining the modified hematite is the same as that in Example 1.

[0073] Comparative Example 4:

[0074] Compared with Example 1, the only difference is that in step 2, kaolin of the same weight is used to replace the montmorillonite, and other operations and parameters are the same as those in Example 1.

[0075] Comparative Example 5:

[0076] Compared with Example 1, the only difference is that in step 2, iron sesquioxide of the same iron element weight is used to replace the hematite, and other operations and parameters are the same as those in Example 1.

[0077] Comparative Example 6:

[0078] The difference compared with Example 1 is only that in step 2, the weight ratio of montmorillonite and hematite is 0.5:1, and other operations and parameters are the same as those in Example 1.

[0079] Comparative Example 7:

[0080] The difference compared with Example 1 is only that the calcination temperature of step 2 is changed, and specifically T2 is 900℃, and other operations and parameters are the same as those in Example 1.

[0081] Second part: performance test (application)

[0082] Application Example 1:

[0083] 0.1g of the heavy metal treatment material prepared in Examples 1-4 of the present application and the materials prepared in Comparative Examples 1-7 were respectively added into 100mL of a solution containing 10mg / L Sb(III), 10mg / L Cr(VI) and 10mg / L As(III), and reacted at 25℃ for 120min to complete the adsorption treatment of Sb(III), Cr(VI) and As(III) in the water body.

[0084] The concentration changes of the three heavy metal ions in the solution were measured by an inductively coupled plasma spectrometer to obtain the adsorption efficiency of different materials on the three heavy metal ions of Sb, Cr and As, and the results are shown in Table 1:

[0085] Table 1

[0086]

[0087]

[0088] Figure 4 The fitting graph of the materials of Example 1, the montmorillonite and magnetite raw materials of Example 1, Comparative Example 1 and Comparative Example 2 as the treatment agent for Sb ions.

[0089] Figure 5 The adsorption removal efficiency graph of the heavy metal treatment material of Example 1 on the three heavy metals of antimony, arsenic and chromium in the water body. From Figure 5 It can be seen that under the same reaction conditions after reacting for 120min, the heavy metal treatment material of the present application shows high adsorption capacity on the three heavy metals of antimony, arsenic and chromium. It shows that the heavy metal treatment material of the present application has good catalytic performance and cost control.

[0090] In conclusion, the heavy metal treatment material has the advantages of high efficiency, low cost, green environmental protection and the like, is a mineral-based composite material with excellent performance, can be widely used for adsorbing and removing heavy metal ions (such as antimony, arsenic and chromium) in the environment, and is environment-friendly, has no toxic and harmful by-products, can be produced on a large scale, has important significance for realizing deep utilization of minerals, and has important significance for application range of the mineral material in the field of environmental remediation.

[0091] The above examples are only preferred embodiments of the present application, and the protection scope of the present application is not limited to the above examples. Any technical scheme falling within the idea of the present application belongs to the protection scope of the present application. It should be pointed out that, for ordinary skilled persons in the art, improvements and refinements without departing from the principles of the present application should also be considered as the protection scope of the present application.

Claims

1. A method of preparing a heavy metal treatment material, characterized by, The montmorillonite and hematite are mixed and then calcined in a reducing atmosphere to obtain the heavy metal treatment material; The weight ratio of the montmorillonite and hematite is 4-6:

1. The temperature of the calcination stage is 600-740℃. The pre-calcination is performed at a temperature of 150-250℃. The heavy metals removed by the heavy metal treatment material are arsenic, chromium and antimony.

2. The method for preparing the heavy metal treatment material as described in claim 1, characterized in that, The montmorillonite is calcium-based montmorillonite with a layered structure of hydrous aluminosilicate.

3. The method for preparing the heavy metal treatment material as described in claim 1, characterized in that, The hematite is an oxide mineral of hexagonal system with an iron content of 80wt.% or more.

4. The method for preparing the heavy metal treatment material as described in claim 1, characterized in that, The weight ratio of the montmorillonite and hematite is 4.5-5.5:

1.

5. The method for preparing the heavy metal treatment material as described in claim 1, characterized in that, The montmorillonite and hematite are mixed by dry or wet ball milling.

6. The method for preparing the heavy metal treatment material as described in claim 1, characterized in that, The reducing atmosphere is an atmosphere containing hydrogen.

7. The method for preparing the heavy metal treatment material as described in claim 6, characterized in that, The reducing atmosphere is a mixture of hydrogen and a protective gas.

8. The method for preparing the heavy metal treatment material as described in claim 7, characterized in that, The content of hydrogen in the reducing atmosphere is 5-15v%.

9. The method for preparing the heavy metal treatment material as described in claim 8, characterized in that, The content of hydrogen in the reducing atmosphere is 8-12v%.

10. The method for preparing the heavy metal treatment material as described in claim 1, characterized in that, The temperature of the calcination stage is 680-720℃.

11. The method for preparing the heavy metal treatment material as described in claim 10, characterized in that, The calcination time is 1-5h.

12. The method for preparing the heavy metal treatment material as described in claim 11, characterized in that, The calcination time is 2-4h.

13. The method for preparing the heavy metal treatment material as described in claim 1, characterized in that, The holding time of the pre-calcination is 1-4h.

14. The method for preparing the heavy metal treatment material as described in claim 1, characterized in that, The holding time of the pre-calcination is 1.5-2.5h.

15. The heavy metal treatment material prepared by the preparation method of any one of claims 1-14.

16. A method for removing heavy metals from heavy metal contaminants, characterized by, The heavy metal treatment material prepared by the preparation method of any one of claims 1-14 is used as a treatment agent for removing heavy metals therefrom. The heavy metals are arsenic, chromium and antimony.

17. The method of removing heavy metals from heavy metal contaminants as claimed in claim 16, wherein, The heavy metal pollutants are solid and / or liquid pollutants containing excessive amounts of heavy metals.

18. The method of removing heavy metals from heavy metal contaminants as claimed in claim 17, wherein, The heavy metal pollutants are at least one of heavy metal contaminated soil and heavy metal contaminated wastewater.

19. The method of removing heavy metals from heavy metal contaminants according to any one of claims 16 to 18, wherein, The amount of the treatment agent used in the removal process is 0.05g / L or more.

20. The method of removing heavy metals from heavy metal contaminants as claimed in claim 19, wherein, The amount of the treatment agent used in the removal process is 0.1-2.0g / L.

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