Schwertmannite adsorption filter material and preparation, application and regeneration method thereof

Abstract

The invention discloses a Schwertmannite adsorption filter material as well as preparation, application and regeneration methods thereof, and belongs to the field of water pollution treatment. The filter material is prepared by loading Schwertmannite prepared by adopting an alkali neutralization method on the surfaces of solid particles. The Schwertmannite prepared by an alkali neutralization method shows quicker adsorption dynamic characteristics on ferrous iron and trivalent arsenic. After the Schwertmannite is fixed on the surface of zeolite to prepare the granular Schwertmannite adsorption filter material, iron and arsenic in underground water can be efficiently removed, and the granular Schwertmannite adsorption filter material has the advantages of being easy to fix, easy to recycle and regenerate, small in head loss and the like. The invention also discloses a regeneration method of the Schwertmannite adsorption filter material. The regeneration is realized by coating a layer of new Schwertmannite on the outer layer of the used filter material. The regeneration mode does not generate waste liquid, does not influence the subsequent arsenic removal effect, and is safe and environment-friendly.

Description

Technical Field

[0001] This application belongs to the field of water pollution control, specifically relating to a Scheres mineral adsorption filter media and its preparation, application and regeneration methods. Background Technology

[0002] Groundwater is a crucial component of my country's drinking water resources, and arsenic contamination in groundwater poses a serious threat to public health. Compared to As(V), As(III) is more challenging to address due to its high toxicity and mobility. Notably, the co-contamination of Fe(II) and As(III) in groundwater is particularly prominent. This co-contamination mechanism primarily stems from the reductive dissolution of arsenic-containing iron oxides, during which Fe(II) and As(III) are released simultaneously, significantly increasing the complexity of the contamination system. my country's current "Standards for Drinking Water Quality" (GB5749-2022) clearly stipulates that the maximum permissible concentrations of arsenic and iron in drinking water are 10 μg / L and 0.3 mg / L, respectively.

[0003] Among numerous arsenic removal technologies, adsorption is the most widely used method due to its simplicity and low cost. However, traditional adsorbents such as activated alumina and titanium dioxide have limited adsorption capacity for As(III) and Fe(II), making efficient removal difficult. Iron oxides have a strong affinity for both iron and arsenic. Among various iron oxides, Schiele minerals stand out due to their unique ability to exchange SO42-. 2- Its structure and abundant surface groups indicate significant application potential in treating As(III). However, its adsorption kinetics for As(III) remain relatively slow.

[0004] Previously, the applicant disclosed a Scherdler mineral prepared by alkali neutralization in Chinese invention patent publication number CN113385139A. This Scherdler mineral exhibits a significantly increased specific surface area and a greater number of functional groups, resulting in a markedly faster adsorption rate for Cr(VI). Given the similar adsorption mechanisms of As(III) and Cr(VI), this Scherdler mineral possesses the potential for highly efficient treatment of As(III) in groundwater. Simultaneously, the Scherdler mineral has a strong affinity for Fe(II) and can catalytically oxidize Fe(II), thus potentially enabling further improvement in arsenic removal efficiency using Fe(II). However, this synthesized Scherdler mineral is in powder form, while most adsorption processes utilize adsorption columns. Using powdered filter media presents challenges such as increased pressure drop, easy clogging, difficulty in fixation, and regeneration difficulties.

[0005] Furthermore, the traditional alkaline regeneration method for adsorbent materials uses high-concentration alkaline solutions, which pose certain risks, and the resulting high-concentration arsenic wastewater is extremely difficult to treat. More importantly, high-concentration alkaline solutions significantly affect the mineral phase of Schiele minerals, causing them to transform into minerals with higher crystallinity, such as goethite, which are less effective at removing As(III), thus worsening the subsequent arsenic removal effect. Summary of the Invention

[0006] 1. The problem to be solved

[0007] To address the problems of powdered filter media being unsuitable for practical applications and the inherent dangers of traditional alkaline regeneration methods, this application provides a granular Schiele mineral adsorption filter media and its preparation, application, and regeneration methods.

[0008] 2. Technical Solution

[0009] To solve the above problems, the technical solution adopted in this application is as follows:

[0010] This application provides a Scherdler mineral adsorption filter media, the outer layer of which is a powdered filter media and the inner layer is a solid particulate matter. The powdered filter media is coated on the surface of the solid particulate matter by a binder. The powdered filter media is Scherdler mineral.

[0011] Furthermore, the mass ratio of the powdered filter material to the solid particles is 1:60-1:80.

[0012] Furthermore, the above-mentioned powdered filter material is Schiele mineral prepared by alkali neutralization, and the preparation steps are as follows: [The text abruptly shifts to a seemingly unrelated topic about Fe content.] 2+ H2O2 was added to the solution, and the pH was adjusted to 2.5-2.7 with alkaline solution every 20-40 minutes. The reaction was shaken, and after the reaction was completed, the mixture was filtered and the precipitate was washed to obtain Schiele mineral.

[0013] Furthermore, the aforementioned adhesive is a neutral silicone structural adhesive.

[0014] Furthermore, the particle size of the aforementioned solid particles is 2-4 mm.

[0015] Furthermore, the aforementioned solid particles are one or more of zeolite, quartz sand, manganese sand, or other particles.

[0016] This application also provides a method for preparing the above-mentioned Scheres mineral adsorption filter material, comprising the following steps: using solid particles as a carrier, coating its surface with a binder, and then mixing it with powdered filter material to uniformly load the powdered filter material on the surface of the solid particles, thereby obtaining Scheres mineral adsorption filter material.

[0017] This application also provides the application of the above-mentioned Schiele mineral adsorption filter media in wastewater treatment.

[0018] Furthermore, the above applications include adding Schiele mineral adsorbent filter media to wastewater containing As(III) and / or Fe(II).

[0019] Furthermore, the above applications include placing Schiele mineral adsorption filter media in an adsorption column.

[0020] This application also provides a method for regenerating the above-mentioned Scherbach mineral adsorption filter media, including the following steps: taking out and drying the used Scherbach mineral adsorption filter media; coating the surface of the Scherbach mineral adsorption filter media with a binder, and then mixing it with new powdered Scherbach mineral, so that the powdered Scherbach mineral is uniformly loaded on the surface of the filter media, thereby obtaining the coated and regenerated Scherbach mineral adsorption filter media.

[0021] Furthermore, in the above regeneration method, the mass ratio of powdered Scherschner mineral to dried Scherschner mineral adsorbent filter media is 1:60-1:80.

[0022] 3. Beneficial effects

[0023] Compared with the prior art, the advantages of this application are as follows:

[0024] (1) The Schiele mineral adsorption filter material is granular and has sufficient hardness to effectively resist water flow impact. It is easy to use in adsorption columns, not easy to clog, easy to recycle, and has low head loss, providing a highly promising solution for groundwater pollution remediation projects.

[0025] (2) This Schiele mineral adsorption filter media not only demonstrates significant effectiveness in the simultaneous removal of iron and arsenic from groundwater, but also enhances the catalytic oxidation of Fe(II), promoting the formation of new iron oxides. These newly formed iron oxides provide more adsorption sites for As(III), further reducing the concentration of arsenic in the effluent and effectively extending the service life of the adsorption column constructed from this filter media.

[0026] (3) The method for regenerating Schiele mineral adsorbent filter media provided in this application successfully solves the problem of treating high-concentration, high-arsenic wastewater, while avoiding the impact of high-concentration alkaline solutions on the Schiele mineral structure and preventing a decline in its arsenic removal capacity. This regeneration method is safe to operate, can significantly reduce potential environmental hazards, and provides a sustainable solution for the treatment of arsenic pollution in groundwater, with significant environmental benefits. Attached Figure Description

[0027] Figure 1 These are images of the Scheringer mineral adsorption filter media, where: (a) is zeolite before loading with Scheringer minerals, and (b) is the Scheringer mineral adsorption filter media after loading with Scheringer minerals.

[0028] Figure 2The image shows the removal effect of an adsorption column constructed with Schiele mineral adsorption filter media on arsenic and iron in groundwater. In the image, (a) is the iron concentration in the effluent and (b) is the arsenic concentration in the effluent.

[0029] Figure 3 This is a comparison chart showing the effects of coating and regenerating the Schiele mineral adsorption filter media with alkaline solution.

[0030] Figure 4 This is a graph showing the effect of Fe(II) concentration in groundwater on the volume of an adsorption column constructed with Schiele mineral adsorption filter media to achieve arsenic removal standards.

[0031] Figure 5 These are the cyclic voltammetry curves of Schiele mineral prepared by alkali neutralization in the presence of Fe(II) in the system. Detailed Implementation

[0032] The present application will be further described below with reference to specific embodiments.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the term “and / or” as used herein includes any and all combinations of one or more of the associated listed items.

[0034] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0035] As used herein, the term “about” is used to provide for the flexibility and imprecision associated with a given term, measure, or value. Those skilled in the art can readily determine the degree of flexibility for a particular variable.

[0036] Concentration, amount, and other numerical data may be presented in range format herein. It should be understood that such range format is used solely for convenience and brevity and should be flexibly interpreted to include not only the values ​​explicitly stated as the limits of the range, but also all individual values ​​or subranges encompassed within the range, as if each value and subrange were explicitly stated. For example, a range of values ​​from about 1 to about 4.5 should be interpreted to include not only the explicitly stated limits of 1 to 4.5, but also individual numbers (such as 2, 3, 4) and subranges (such as 1 to 3, 2 to 4, etc.). The same principle applies to ranges that describe only a single value, such as “less than about 4.5,” which should be interpreted to include all the aforementioned values ​​and ranges. Furthermore, this interpretation should apply regardless of the breadth of the range or characteristic described.

[0037] Example 1

[0038] This embodiment provides a Scherschner mineral adsorption filter media and its preparation, application, and regeneration method, specifically including the following steps:

[0039] (1) Preparation of Schönbrunné mineral adsorption filter media: Using 140g of zeolite filter media with a diameter of 2-4mm as a carrier, neutral silicone structural adhesive is first uniformly coated on its surface as a binder. Then, 2g of Schönbrunné mineral prepared by alkali neutralization is thoroughly mixed with the coated zeolite, controlling the mass ratio of Schönbrunné mineral to zeolite to be 1:70 to achieve uniform loading of Schönbrunné mineral on the zeolite surface, thus obtaining the Schönbrunné mineral adsorption filter media, which can be used directly after preparation. The appearance characteristics of the filter media before and after loading are as follows: Figure 1 As shown. The Schiele mineral prepared by the alkali neutralization method is derived from Chinese invention patent publication number CN113385139A. The specific preparation steps are as follows: 80 mM FeSO4 solution is prepared in an Erlenmeyer flask, and 1.5 mL of 30% H2O2 (by mass) is added to the solution. The pH is then adjusted to 2.7 with 5 M NaOH solution every 40 min, and the reaction is carried out on a shaker at 180 rpm / min for 24 h. The product is collected by filtration through a filter membrane, washed with water, and then freeze-dried under vacuum to obtain the Schiele mineral.

[0040] (2) Construction and operation of the adsorption column: An acrylic column with a height-to-diameter ratio of 10 was used, filled with the aforementioned Schiele mineral adsorption filter media, and the filter layer height after filling was 20 cm. The adsorption column was started to treat groundwater, with the filtration rate set at 0.5 m / h and the corresponding residence time at 24 min. The specific water quality composition of the groundwater was as follows: 2 mg / L Fe(II), 150 μg / L As(III), 0.8 mg / L NH4. + -N, 37 mg / L Ca 2+ 9 mg / L Mg 2+ 460 mg / L HCO3 - 10 mg / L SiO3 2- 0.3-0.4 mg / LPO4 3- And the pH is 7.2. For example... Figure 2 As shown, the iron concentration in the treated effluent was consistently below 0.3 mg / L, and the arsenic concentration was consistently below 10 μg / L within 1073 bed volumes. Here, 1073 bed volumes refers to the volume of the treated groundwater being 1073 times the volume of the filter media.

[0041] (3) Regeneration of Schiele mineral adsorption filter media: When the arsenic concentration in the effluent from the adsorption column exceeded 10 μg / L, the filter media was regenerated by coating. The specific steps are as follows: All Schiele mineral adsorption filter media in the adsorption column were removed and dried at 55℃ for 4 hours; neutral silicone structural adhesive was then coated again on the surface of the dried Schiele mineral adsorption filter media, and 2g of Schiele mineral prepared by the alkali neutralization method was mixed with it to ensure that the new Schiele mineral was uniformly loaded on the surface of the filter media, thus obtaining the coated and regenerated Schiele mineral adsorption filter media. Subsequently, all the filter media were refilled back into the adsorption column, and the adsorption column was restarted to treat the groundwater. The filtration rate was 0.5 m / h, and the corresponding residence time was 24 min. This coating and regeneration process was repeated 3 times. During this process, the removal effect of the adsorption column on arsenic and iron showed high stability. Among them, the bed volume that achieved the arsenic removal standard remained basically constant (see Figure 3 ).

[0042] Example 2

[0043] This embodiment tests the arsenic removal effect of the adsorption filter media under different influent Fe(II) concentrations.

[0044] The preparation of Schiele mineral adsorption filter media and the construction of the adsorption column are described in Example 1.

[0045] The adsorption column was set to operate at a filtration rate of 0.5 m / h, corresponding to a residence time of 24 min. Simulated groundwater was used as the influent, with different Fe(II) concentrations set. The specific composition of this simulated groundwater was: 0-4 mg / L Fe(II) (specifically set to 0, 1, 2, and 4 mg / L), 150 μg / L As(III), and 0.8 mg / L NH4+. + -N, 37 mg / L Ca 2+ 9 mg / L Mg 2+ 460 mg / L HCO3 - 10 mg / L SiO3 2- 0.3-0.4 mg / L PO4 3- The pH was 7.2. Under different influent Fe(II) concentrations, the iron concentration in the treated effluent consistently remained below 0.3 mg / L, and the arsenic concentration was also below 10 μg / L. Figure 4 The concentration of Fe(II) in the influent showed a positive correlation with the bed volume achieving arsenic removal standards; the higher the Fe(II) concentration, the larger the bed volume, meaning that a unit volume of filter media could treat more groundwater. This Scheres mineral adsorption filter media enhanced the catalytic oxidation of Fe(II), promoting the formation of new iron oxides. These newly formed iron oxides provided more adsorption sites for As(III), further reducing the arsenic concentration in the effluent and effectively extending the service life of the adsorption column constructed from this filter media.

[0046] Compared to influent without Fe(II), when the influent Fe(II) concentration is in the range of 1-4 mg / L, the effective bed volume of the adsorption column for arsenic removal increases from 406 to 696-3045, an increase of 71%-650%. Figure 5 Cyclic voltammetry curves revealed that the presence of Schiemann mineral, prepared by the alkali neutralization method, shifted the oxidation peak potential of Fe(II) to lower values. This phenomenon indicates that the Schiemann mineral significantly promotes the oxidation process of Fe(II). Particularly noteworthy is the significant enhancement of the Fe(II) oxidation current in the presence of this Schiemann mineral, which strongly suggests that the mineral facilitates electron transfer during the Fe(II) oxidation process, thus providing favorable conditions for improving the arsenic removal efficiency of the adsorption column.

[0047] Comparative Example 1

[0048] The Scheringer mineral used in this comparative example was prepared without the addition of alkali during the synthesis process. The other steps were the same as in Example 1, as follows:

[0049] (1) Preparation of Schäumann mineral adsorption filter media: Using 140g of zeolite filter media with a diameter of 2-4mm as a carrier, neutral silicone structural adhesive was first uniformly coated on its surface as a binder. Subsequently, 2g of Schäumann mineral prepared without the addition of alkali solution during the synthesis process was mixed with it, so that the Schäumann mineral was uniformly loaded on the surface of the zeolite, thereby obtaining the Schäumann mineral adsorption filter media. The preparation method of Schäumann mineral prepared without the addition of alkali solution during the synthesis process includes the following steps: 80mM Fe(II) solution (using FeSO4 as the iron source) was prepared in an Erlenmeyer flask, 1.5mL H2O2 was added to the Fe(II) solution, and the reaction was carried out on a shaker at 180rpm / min for 24h; the product was collected by filtration through a filter membrane and washed several times, and then freeze-dried under vacuum to obtain Schäumann mineral.

[0050] (2) The construction and operation of the adsorption column are as described in Example 1. Figure 2 As shown, the iron concentration in the treated effluent consistently exceeded 0.3 mg / L, and the arsenic concentration also consistently exceeded the standard. Compared with this comparative example, it can be seen that the Scherstein mineral prepared by the alkali neutralization method exhibits stronger adsorption kinetics for both As(III) and Fe(II). Therefore, the Scherstein mineral adsorption filter media prepared by the alkali neutralization method is more effective in treating the combined pollution of iron and arsenic in groundwater.

[0051] Comparative Example 2

[0052] In this comparative example, the regeneration method for the Scheres mineral adsorption filter media uses alkaline solution regeneration, and the specific steps are as follows:

[0053] The preparation of Schiele mineral adsorption filter media and the construction and operation of the adsorption column are described in Example 1.

[0054] When the arsenic concentration in the effluent from the adsorption column exceeded 10 μg / L, the filter media was regenerated using alkaline solution, including the following steps: All Schiele mineral adsorption media were removed from the adsorption column and placed in 200 mL of 1M NaOH solution, shaken at 120 rpm / min for 8 hours to ensure complete desorption of the adsorbed arsenic; subsequently, the filter media was washed until neutral and then refilled into the adsorption column. The adsorption column was then restarted for groundwater treatment at a filtration rate of 0.5 m / h and a corresponding residence time of 24 min, with the same water composition as described above. This alkaline regeneration process was repeated three times. During this process, the removal efficiency of the adsorption column for iron remained stable, but the removal efficiency for arsenic gradually deteriorated (see...). Figure 3 Specifically, the effective bed volume (the volume of water that a unit volume of filter media can treat) for arsenic removal gradually decreases, which is due to the high concentration of alkaline solution destroying the structure of Schiele minerals.

Claims

1. A Schiele mineral adsorption filter media, characterized in that, The outer layer is a powdered filter material, and the inner layer is a solid particulate matter. The powdered filter material is coated on the surface of the solid particulate matter with a binder. The powdered filter material is Schiele mineral.

2. The Schiele mineral adsorption filter media according to claim 1, characterized in that, The mass ratio of the powdered filter material to the solid particles is 1:60-1:

80.

3. The Schiele mineral adsorption filter media according to claim 1 or 2, characterized in that, The powdered filter material is Schiele mineral prepared by alkali neutralization. The preparation steps are as follows: [The text abruptly shifts to a different topic] ...Fe-containing... 2+ H2O2 was added to the solution, and the pH was adjusted to 2.5-2.7 with alkaline solution every 20-40 minutes. The reaction was shaken, and after the reaction was completed, the mixture was filtered and the precipitate was washed to obtain Schiele mineral.

4. The Schiele mineral adsorption filter media according to claim 3, characterized in that, The adhesive is a neutral silicone structural adhesive.

5. The Schiele mineral adsorption filter media according to claim 3, characterized in that, The particle size of the solid particles is 2-4 mm.

6. The Schiele mineral adsorption filter media according to claim 5, characterized in that, The solid particles are one or more of zeolite, quartz sand, manganese sand, or other particles.

7. A method for preparing the Schiele mineral adsorption filter media according to any one of claims 1-6, characterized in that, Includes the following steps: Using solid particles as a carrier, a binder is coated on its surface, and then powdered filter media is mixed with it to make the powdered filter media uniformly loaded on the surface of the solid particles, thus obtaining Schiele mineral adsorption filter media.

8. The application of the Schiele mineral adsorption filter media according to any one of claims 1-6 in wastewater treatment.

9. The method for regenerating the Schiele mineral adsorbent filter media according to any one of claims 1-6, characterized in that, Includes the following steps: Remove and dry the used Scheringer mineral adsorption filter media; coat the surface of the Scheringer mineral adsorption filter media with a binder, and then mix it with new powdered Scheringer mineral to make the powdered Scheringer mineral uniformly loaded on the surface of the filter media, thereby obtaining the coated and regenerated Scheringer mineral adsorption filter media.

10. The method for regenerating Schiff mineral adsorption filter media according to claim 9, characterized in that, The mass ratio of the powdered Scherschner mineral to the dried Scherschner mineral adsorption filter media is 1:60-1:80.

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