Preparation method and application of iron-modified montmorillonite

Abstract

The invention relates to the technical field of wastewater treatment, in particular to a preparation method and application of iron modified montmorillonite. The preparation method comprises the following steps: adding montmorillonite into water, carrying out ultrasonic treatment, and then centrifuging to obtain supernate; centrifuging the supernate, and freeze-drying the obtained precipitate to obtain pretreated montmorillonite; dispersing the pretreated montmorillonite in water, adjusting the pH value of the solution to be acidic, and stirring; then adding ferric iron salt, stirring and centrifuging; dispersing precipitates obtained by centrifugation into a ferric iron salt solution, stirring and centrifuging; repeating the steps of dispersing the precipitate obtained by centrifugation into the ferric iron salt solution, stirring and centrifuging; and washing the precipitate obtained by the last centrifugation, and then freeze-drying to obtain the iron modified montmorillonite. The iron-modified montmorillonite can effectively degrade the triazine herbicide simazine, is simple to prepare, wide in raw material source and low in price, and has important significance in removal of refractory pollutant triazine herbicides.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and in particular to a preparation method of iron-modified montmorillonite and application thereof. Background Art

[0002] Simazine belongs to the triazine herbicide, which is a six-membered heterocyclic compound containing three nitrogen atoms. It is widely used because of its low price and obvious weed control effect. Because the compound has a symmetrical structure, is not easily degraded under natural conditions, has a long half-life, and has poor water solubility, it is widely detected in soil and water environments. More importantly, simazine has a strong interference with the human endocrine system and affects the synthesis of steroid hormones. In addition, many plants are not resistant to simazine and easily accumulate simazine from the environment, posing a serious threat to animals, plants and humans. At present, the degradation research of triazine herbicides is mostly focused on atrazine, ignoring other types of triazine herbicides. Therefore, it is necessary to provide an effective removal method for simazine, which has a more stable structure. Summary of the invention

[0003] Based on the above content, the present invention provides a preparation method and application of iron-modified montmorillonite. Using the iron-modified montmorillonite of the present invention as a catalytic material can effectively activate peroxymonosulfate (PMS) to degrade simazine in wastewater, improve the removal rate of simazine, and solve the current problem of low removal rate of simazine.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] One of the technical solutions of the present invention is a method for preparing iron-modified montmorillonite, comprising the following steps:

[0006] Step 1, adding montmorillonite to water for ultrasonic treatment, and then centrifuging to obtain a supernatant; centrifuging the supernatant, and freeze-drying the obtained precipitate to obtain pretreated montmorillonite;

[0007] Step 2, dispersing the pretreated montmorillonite in water and adjusting the pH value of the solution to be acidic and stirring; then adding trivalent iron salt, stirring, and centrifuging; dispersing the precipitate obtained by centrifugation in a trivalent iron salt solution, stirring, and centrifuging; repeating the above steps of dispersing the precipitate obtained by centrifugation in a trivalent iron salt solution, stirring, and centrifuging;

[0008] Step 3, washing the precipitate obtained by the last centrifugation in step 2, and then freeze-drying it to obtain the iron-modified montmorillonite.

[0009] The second technical solution of the present invention is an iron-modified montmorillonite prepared according to the preparation method of the iron-modified montmorillonite.

[0010] The third technical solution of the present invention is the use of the iron-modified montmorillonite in removing triazine herbicides from water.

[0011] A fourth technical solution of the present invention is a method for degrading simazine in water, comprising adding the iron-modified montmorillonite and peroxymonosulfate to wastewater containing simazine for degradation; the concentration of the iron-modified montmorillonite in the wastewater containing simazine is 0-1 mg / mL; the concentration of the peroxymonosulfate in the wastewater containing simazine is 0-5 mM; the concentration of simazine in the wastewater containing simazine is not greater than 10 mg / L; and the pH of the wastewater containing simazine is 3-11.

[0012] The present invention discloses the following technical effects:

[0013] (1) The present invention adopts a simple physical and chemical preparation method to prepare iron-modified montmorillonite, which has simple process conditions, readily available raw materials, low cost and easy storage.

[0014] (2) The present invention uses iron-modified montmorillonite with excellent peroxymonosulfate activation performance as a catalyst to degrade simazine, a difficult-to-degrade triazine herbicide in wastewater. During the reaction, oxygen-containing free radicals are generated, thereby efficiently removing simazine from wastewater. After 2 hours of degradation reaction, the degradation efficiency of simazine is as high as 86.3%. It is suitable for the removal of organic pollutants such as triazine herbicides in water bodies and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 This is a scanning electron microscope photograph of the iron-modified montmorillonite prepared in Example 1;

[0017] Figure 2 Fe2p spectra of montmorillonite catalyst before and after iron modification measured by XPS in Example 1;

[0018] Figure 3 The degradation results of simazine in Example 2 are as follows;

[0019] Figure 4 The degradation results of simazine under different anion interferences are shown;

[0020] Figure 5 The degradation results of simazine at different simazine concentrations;

[0021] Figure 6The degradation results of simazine under different pH conditions. DETAILED DESCRIPTION

[0022] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0023] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0024] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0025] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0026] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0027] The toxicity of simazine is mainly exerted by the chlorine atom on the triazine ring. Traditional water treatment processes cannot effectively reduce the toxicity of degradation products, which has prompted the development of new technologies to greatly reduce the toxicity of wastewater after the reaction. At present, the advanced oxidation process based on sulfate is considered to be a very promising technology. Metal ions can effectively activate permonosulfate to produce sulfate free radicals, thereby degrading organic pollutants. Therefore, it is very necessary to utilize montmorillonite, a clay mineral widely present in nature, to modify it with inorganic iron through simple physical and chemical means, and to obtain a cheap and effective catalytic material to activate permonosulfate to degrade simazine, so as to reduce the harm of this type of herbicide to the environment.

[0028] One of the technical solutions of the present invention is a method for preparing iron-modified montmorillonite, comprising the following steps:

[0029] Step 1, adding montmorillonite to water for ultrasonic treatment, and then centrifuging to obtain a supernatant; centrifuging the supernatant, and freeze-drying the obtained precipitate to obtain pretreated montmorillonite;

[0030] Step 2, dispersing the pretreated montmorillonite in water and adjusting the pH value of the solution to be acidic and stirring; then adding trivalent iron salt, stirring, and centrifuging; dispersing the precipitate obtained by centrifugation in a trivalent iron salt solution, stirring, and centrifuging; repeating the above steps of dispersing the precipitate obtained by centrifugation in a trivalent iron salt solution, stirring, and centrifuging;

[0031] Step 3, washing the precipitate obtained by the last centrifugation in step 2, and then freeze-drying it to obtain the iron-modified montmorillonite.

[0032] In a preferred embodiment of the present invention, in step 1, the particle size of the montmorillonite is 200 mesh.

[0033] In a preferred embodiment of the present invention, in step 1, the mass ratio of the montmorillonite to the water is 1:20; the power of the ultrasonic treatment is 40 KHz, and the time is 2 hours.

[0034] In a preferred embodiment of the present invention, in step 1, when preparing the supernatant, the centrifugation conditions are: centrifugation at a centrifugal force of 60g for 10 minutes; when the supernatant is centrifuged, it is centrifuged at a centrifugal force of 3500g for 10 minutes.

[0035] The reason for taking the montmorillonite in the supernatant in step 1 is that the particle size of the montmorillonite in the supernatant is less than 2 microns. Sieving with a 6250-mesh sieve can also obtain montmorillonite with a particle size less than 2 microns, but when sieving with a 6250-mesh sieve, the particle size is too small and the mesh is easily blocked, the operation is inconvenient, and the loss is large under environmental conditions; when using the method of the present invention (centrifuge separation), the operation is simple, and it only needs to set different parameters for centrifugation twice to complete, and the loss is small.

[0036] In a preferred embodiment of the present invention, in step 2, the stirring speed is 300 rpm, the stirring time is 4 hours, and the pH value is 6.8.

[0037] In step 2, the pH value of the solution is adjusted to acidic by adding 0.1 M HCl.

[0038] In a preferred embodiment of the present invention, in step 2, the ferric iron salt is FeCl3·6H2O; the ferric iron salt is added to a concentration of 25-30 g / L in the solution; the stirring rate of the ferric iron salt is 300 rpm, and the stirring time is 8 h; the centrifugal force of the centrifugation after the ferric iron salt is added and stirred is 3500 g, and the centrifugation time is 10 min.

[0039] In a preferred embodiment of the present invention, in step 2, the number of repetitions is 1 to 8 times.

[0040] The reasons for repeating the steps of dispersing the precipitate obtained by centrifugation in a trivalent iron salt solution, stirring and centrifuging 1 to 8 times are as follows: too few repetitions will result in unsaturated iron on the montmorillonite, reducing the removal rate of simazine. More importantly, Fe will be leached during the subsequent activation of PMS, and the low iron loading on the montmorillonite will be unfavorable for the reuse of iron-modified montmorillonite; too many repeated stirring times will cause the montmorillonite to be saturated and unable to continue to adsorb iron, resulting in waste of raw materials.

[0041] In a preferred embodiment of the present invention, in step 2, the concentration of the ferric salt solution is 25-30 g / L, and the solvent is water.

[0042] The present invention does not impose any particular limitation on the amount of water used in step 2, as long as the amount of water can fully and evenly disperse the pretreated montmorillonite and dissolve the trivalent iron salt.

[0043] The purpose of repeating the above steps of dispersing the precipitate obtained by centrifugation in the ferric iron salt solution, stirring and centrifuging in step 2 is to ensure iron saturation (i.e., iron is adsorbed saturated in montmorillonite).

[0044] The present invention does not impose any particular limitation on the freeze-drying parameter settings in step 1 and step 3, and the freeze-drying parameter settings well known to those skilled in the art may be adopted.

[0045] In step 3, the washing is specifically repeated washing with deionized water until no Cl is detected in the supernatant. - until.

[0046] The second technical solution of the present invention is an iron-modified montmorillonite prepared according to the preparation method of the iron-modified montmorillonite.

[0047] The third technical solution of the present invention is the use of the iron-modified montmorillonite in removing triazine herbicides from water.

[0048] In a preferred embodiment of the present invention, the triazine herbicide is simazine.

[0049] A fourth technical solution of the present invention is a method for degrading simazine in water, comprising adding the iron-modified montmorillonite and peroxymonosulfate to wastewater containing simazine for degradation; the concentration of the iron-modified montmorillonite in the wastewater containing simazine is 0-1 mg / mL; the concentration of the peroxymonosulfate in the wastewater containing simazine is 0-5 mM; the concentration of simazine in the wastewater containing simazine is not greater than 10 mg / L; the concentration of simazine in the wastewater containing simazine is 1-10 mg / L; the pH of the wastewater containing simazine is 3-11.

[0050] The catalyst prepared by the invention can effectively degrade the triazine herbicide simazine, the catalyst is simple to prepare, the raw materials are widely available and low in price, and the catalyst is of great significance for removing the triazine herbicide which is a difficult-to-degrade pollutant.

[0051] The technical solutions described in the present invention, unless otherwise specified, are all conventional solutions in the art, and the reagents or raw materials used, unless otherwise specified, are purchased from commercial channels or have been disclosed.

[0052] The peroxymonosulfate used in the embodiment of the present invention is KHSO5 with a mass concentration of 44%±2%.

[0053] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0054] Example 1

[0055] The preparation method of the iron-modified montmorillonite catalytic material of the present invention comprises the following specific steps:

[0056] Step 1, montmorillonite pretreatment: the purchased montmorillonite is passed through a 200-mesh nylon sieve, 50 g of the sieve material is weighed and placed in a beaker, 1 L of deionized water is added and ultrasonicated at room temperature and 40 kHz for 2 h, centrifuged after the ultrasonication, centrifuged at a centrifugal force of 60 g for 10 min, the precipitate is removed and the supernatant is retained, the supernatant is centrifuged in a high-speed centrifuge at 3500 g for 10 min, and the precipitate is dried in a freeze drying oven for 48 h to obtain 17.8 g of pretreated montmorillonite.

[0057] Step 2, the pretreated montmorillonite is redispersed in 1L of deionized water, stirred at 300rpm in a mechanical stirrer for 4h, during which 0.1M HCl is added to adjust the pH of the solution to 6.8 (the purpose of adjusting the pH is to remove organic impurities). Then 27.03g of FeCl3·6H2O is added, stirring is continued for 8h, and centrifuged at a centrifugal force of 3500g for 10min, and the precipitate is redispersed in 1L of deionized water, and 27.03g of FeCl3·6H2O is added (in order to ensure iron saturation, the process of adding FeCl3·6H2O, stirring, and centrifuging needs to be repeated six times).

[0058] Step 3, the precipitate obtained in step 2 is repeatedly washed with deionized water and centrifuged to remove Cl-, and the end point is that no white precipitate is generated when 0.5M silver nitrate solution is added dropwise to the supernatant. Finally, the precipitate is dried in a vacuum freeze drying oven for 48 hours and passed through a 200-mesh nylon sieve to obtain iron-modified montmorillonite.

[0059] Figure 1 is a scanning electron microscope photograph of the iron-modified montmorillonite obtained in Example 1; Figure 1 It can be seen that the iron-modified montmorillonite still maintains its original layered structure, but the structure becomes curled and compact, increasing the adsorption sites.

[0060] Figure 2 The Fe2p spectra of the montmorillonite catalyst before and after iron modification in Example 1 were measured by XPS; Figure 2 It can be seen that the Fe2p spectral response intensity of the iron-modified montmorillonite is significantly higher than that of the original montmorillonite, indicating that Fe is successfully loaded on the montmorillonite.

[0061] Example 2

[0062] This example provides the application of iron-modified montmorillonite in the degradation of simazine in wastewater. The iron-modified montmorillonite prepared in Example 1 is used as a catalyst and peroxymonosulfate is used as an oxidant. The advanced oxidation technology based on sulfate free radicals is used to degrade the difficult-to-degrade simazine wastewater. The specific operation is as follows:

[0063] 0.05g of iron-modified montmorillonite was added to 50mL of simazine wastewater, and 5mM permonosulfate was added after adsorption in a constant temperature water bath oscillator at room temperature for 2h. The pH of the simazine wastewater was 4.6, and the concentration of simazine was 5mg / L. The simazine wastewater was degraded by an advanced oxidation process based on sulfate radicals in a constant temperature water bath oscillator at room temperature. The degradation time was 2h, and samples were taken at different times of the reaction (filtered with a 0.45μm organic filter membrane), and the concentration changes of simazine in the system at different times were determined by high performance liquid chromatography.

[0064] Example 3

[0065] This example provides the application of iron-modified montmorillonite in removing simazine from wastewater. The iron-modified montmorillonite prepared in Example 1 is used as an adsorbent to remove refractory simazine from wastewater based on adsorption technology. The specific operation is as follows:

[0066] 0.05g of iron-modified montmorillonite was added to 50mL of simazine wastewater, and adsorbed in a constant temperature water bath oscillator at room temperature for 2h. The pH of the simazine wastewater was 4.6, and the concentration of simazine was 5mg / L. The simazine wastewater was adsorbed and removed in a constant temperature water bath oscillator at room temperature. The adsorption time was 2h, and samples were taken at different times of the reaction (filtered with a 0.45μm organic filter membrane), and the concentration changes of simazine in the system at different times were determined by high performance liquid chromatography.

[0067] Example 4

[0068] This example provides the application of peroxymonosulfate in the degradation of simazine in wastewater. Peroxymonosulfate is used as an oxidant, and the advanced oxidation technology based on sulfate free radicals is used to degrade the difficult-to-degrade simazine wastewater. The specific operation is as follows:

[0069] 5mM permonosulfate was added to 50mL of simazine wastewater and degraded in a constant temperature water bath oscillator for 2h. The pH of the simazine wastewater was 4.6, and the concentration of simazine was 5mg / L. In a constant temperature water bath oscillator, the simazine wastewater was degraded by an advanced oxidation process based on sulfate free radicals. The degradation time was 2h, and samples were taken at different times of the reaction (filtered with a 0.45μm organic filter membrane), and the concentration changes of simazine in the system at different times were determined by high performance liquid chromatography.

[0070] The analysis results of the above examples 2 to 4 are detailed in Figure 3 (In the figure, iron-modified montmorillonite represents Example 3, PMS represents Example 4, and iron-modified montmorillonite + PMS represents Example 2). After 2 hours of degradation of simazine by permonosulfate activated by iron-modified montmorillonite, the degradation efficiency of simazine is as high as 86.3%, which is much higher than that of the single PMS and iron-modified montmorillonite system. This proves that iron-modified montmorillonite activated permonosulfate has a significant treatment effect on simazine wastewater.

[0071] Example 5

[0072] This example provides the application of iron-modified montmorillonite in the degradation of simazine in wastewater. The iron-modified montmorillonite prepared in Example 1 is used as a catalyst and peroxymonosulfate is used as an oxidant. The advanced oxidation technology based on sulfate free radicals is used to degrade the difficult-to-degrade simazine wastewater. The specific operation is as follows:

[0073] 0.05g iron-modified montmorillonite and 0.01M sodium chloride were added to 50mL of simazine wastewater, and 5mM permonosulfate was added after adsorption in a constant temperature water bath oscillator at room temperature for 2h, wherein the pH of the simazine wastewater was 4.6, and the concentration of simazine was 5mg / L. Simazine wastewater was degraded by an advanced oxidation process based on sulfate radicals in a constant temperature water bath oscillator at room temperature. The degradation time was 2h, and samples were taken at different times of the reaction (filtered with a 0.45μm organic filter membrane), and the concentration changes of simazine in the system at different times were determined by high performance liquid chromatography.

[0074] Example 6

[0075] This example provides the application of iron-modified montmorillonite in the degradation of simazine in wastewater. The iron-modified montmorillonite prepared in Example 1 is used as a catalyst and peroxymonosulfate is used as an oxidant. The advanced oxidation technology based on sulfate free radicals is used to degrade the difficult-to-degrade simazine wastewater. The specific operation is as follows:

[0076] 0.05g iron-modified montmorillonite and 0.01M sodium sulfate were added to 50mL of simazine wastewater, and 5mM permonosulfate was added after adsorption in a constant temperature water bath oscillator at room temperature for 2h. The pH of the simazine wastewater was 4.6, and the concentration of simazine was 5mg / L. The simazine wastewater was degraded by an advanced oxidation process based on sulfate radicals in a constant temperature water bath oscillator at room temperature. The degradation time was 2h, and samples were taken at different times of the reaction (filtered with a 0.45μm organic filter membrane), and the concentration changes of simazine in the system at different times were determined by high performance liquid chromatography.

[0077] Example 7

[0078] This example provides the application of iron-modified montmorillonite in the degradation of simazine in wastewater. The iron-modified montmorillonite prepared in Example 1 is used as a catalyst and peroxymonosulfate is used as an oxidant. The advanced oxidation technology based on sulfate free radicals is used to degrade the difficult-to-degrade simazine wastewater. The specific operation is as follows:

[0079] 0.05g iron-modified montmorillonite and 0.01M sodium bicarbonate were added to 50mL of simazine wastewater, and 5mM permonosulfate was added after adsorption in a constant temperature water bath oscillator at room temperature for 2h, wherein the pH of the simazine wastewater was 4.6, and the concentration of simazine was 5mg / L. Simazine wastewater was degraded by an advanced oxidation process based on sulfate radicals in a constant temperature water bath oscillator at room temperature. The degradation time was 2h, and samples were taken at different times of the reaction (filtered with a 0.45μm organic filter membrane), and the concentration changes of simazine in the system at different times were determined by high performance liquid chromatography.

[0080] Example 8

[0081] This example provides the application of iron-modified montmorillonite in the degradation of simazine in wastewater. The iron-modified montmorillonite prepared in Example 1 is used as a catalyst and peroxymonosulfate is used as an oxidant. The advanced oxidation technology based on sulfate free radicals is used to degrade the difficult-to-degrade simazine wastewater. The specific operation is as follows:

[0082] 0.05g iron-modified montmorillonite and 0.01M potassium dihydrogen phosphate were added to 50mL of simazine wastewater, and 5mM permonosulfate was added after adsorption in a constant temperature water bath oscillator at room temperature for 2h. The pH of the simazine wastewater was 4.6, and the concentration of simazine was 5mg / L. The simazine wastewater was degraded by an advanced oxidation process based on sulfate radicals in a constant temperature water bath oscillator at room temperature. The degradation time was 2h, and samples were taken at different times of the reaction (filtered with a 0.45μm organic filter membrane), and the concentration changes of simazine in the system at different times were determined by high performance liquid chromatography.

[0083] The processing results of Examples 5 to 8 are as follows Figure 4 As shown (the control group in the figure represents Example 2), by Figure 4 It can be seen that under different anion Cl - 、SO4 2- 、HCO3 - and H2PO4 - Under the influence of , the removal rates of simazine were 90.84%, 78.06%, 97.07% and 81.66% respectively. The above results prove that the iron-modified montmorillonite activated persulfate system can adapt to different anion conditions and still has a good treatment effect on simazine wastewater.

[0084] Example 9

[0085] This example provides the application of iron-modified montmorillonite in the degradation of simazine in wastewater. The iron-modified montmorillonite prepared in Example 1 is used as a catalyst and peroxymonosulfate is used as an oxidant. The advanced oxidation technology based on sulfate free radicals is used to degrade the difficult-to-degrade simazine wastewater. The specific operation is as follows:

[0086] 0.05g of iron-modified montmorillonite was added to 50mL of simazine wastewater, and 5mM permonosulfate was added after adsorption in a constant temperature water bath oscillator at room temperature for 2h. The pH of the simazine wastewater was 4.6, and the concentration of simazine was 1mg / L. The simazine wastewater was degraded by an advanced oxidation process based on sulfate radicals in a constant temperature water bath oscillator at room temperature. The degradation time was 2h, and samples were taken at different times of the reaction (filtered with a 0.45μm organic filter membrane), and the concentration changes of simazine in the system at different times were determined by high performance liquid chromatography.

[0087] Example 10

[0088] This example provides the application of iron-modified montmorillonite in the degradation of simazine in wastewater. The iron-modified montmorillonite prepared in Example 1 is used as a catalyst and peroxymonosulfate is used as an oxidant. The advanced oxidation technology based on sulfate free radicals is used to degrade the difficult-to-degrade simazine wastewater. The specific operation is as follows:

[0089] 0.05g of iron-modified montmorillonite was added to 50mL of simazine wastewater, and 5mM permonosulfate was added after adsorption in a constant temperature water bath oscillator at room temperature for 2h. The pH of the simazine wastewater was 4.6, and the concentration of simazine was 2mg / L. The simazine wastewater was degraded by an advanced oxidation process based on sulfate radicals in a constant temperature water bath oscillator at room temperature. The degradation time was 2h, and samples were taken at different times of the reaction (filtered with a 0.45μm organic filter membrane), and the concentration changes of simazine in the system at different times were determined by high performance liquid chromatography.

[0090] Embodiment 11

[0091] This example provides the application of iron-modified montmorillonite in the degradation of simazine in wastewater. The iron-modified montmorillonite prepared in Example 1 is used as a catalyst and peroxymonosulfate is used as an oxidant. The advanced oxidation technology based on sulfate free radicals is used to degrade the difficult-to-degrade simazine wastewater. The specific operation is as follows:

[0092] 0.05g of iron-modified montmorillonite was added to 50mL of simazine wastewater, and 5mM permonosulfate was added after adsorption in a constant temperature water bath oscillator at room temperature for 2h. The pH of the simazine wastewater was 4.6, and the concentration of simazine was 10mg / L. The simazine wastewater was degraded by an advanced oxidation process based on sulfate radicals in a constant temperature water bath oscillator at room temperature. The degradation time was 2h, and samples were taken at different times of the reaction (filtered with a 0.45μm organic filter membrane), and the concentration changes of simazine in the system at different times were determined by high performance liquid chromatography.

[0093] The processing results of Examples 9 to 11 are as follows Figure 5 As shown (in the figure, 1 mg / L, 2 mg / L, 5 mg / L, and 10 mg / L correspond to Example 9, Example 10, Example 2, and Example 11, respectively), by Figure 5 It can be seen that in wastewater with different simazine concentrations, the removal rates of simazine were 86.06%, 86.44%, 86.3% and 49.25%, respectively. The above results prove that the iron-modified montmorillonite activated persulfate system has an excellent treatment effect on low-concentration simazine wastewater.

[0094] Example 12

[0095] This example provides the application of iron-modified montmorillonite in the degradation of simazine in wastewater. The iron-modified montmorillonite prepared in Example 1 is used as a catalyst and peroxymonosulfate is used as an oxidant. The advanced oxidation technology based on sulfate free radicals is used to degrade the difficult-to-degrade simazine wastewater. The specific operation is as follows:

[0096] 0.05g of iron-modified montmorillonite was added to 50mL of simazine wastewater, and 5mM permonosulfate was added after adsorption in a constant temperature water bath oscillator at room temperature for 2h. The pH of the simazine wastewater was 3, and the concentration of simazine was 5mg / L. The simazine wastewater was degraded by an advanced oxidation process based on sulfate free radicals in a constant temperature water bath oscillator at room temperature. The degradation time was 2h, and samples were taken at different times of the reaction (filtered with a 0.45μm organic filter membrane), and the concentration changes of simazine in the system at different times were determined by high performance liquid chromatography.

[0097] Example 13

[0098] The only difference from Example 12 is that the pH of the simazine wastewater is 7.

[0099] Embodiment 14

[0100] The only difference from Example 12 is that the pH of the simazine wastewater is 9.

[0101] Embodiment 15

[0102] The only difference from Example 12 is that the pH of the simazine wastewater is 11.

[0103] The processing results of Examples 12 to 15 are as follows Figure 6 As shown (in the figure, pH 3, 4.6, 7, 9, and 11 correspond to Example 12, Example 2, Example 13, Example 14, and Example 15, respectively), by Figure 6 It can be seen that in simazine wastewater with different pH values, the removal rates of simazine were 96.28%, 86.3%, 84.59%, 75.89% and 72.5%, respectively. The above results prove that the iron-modified montmorillonite activated persulfate system has an excellent treatment effect on simazine in acidic solution.

[0104] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for preparing iron-modified montmorillonite, characterized in that: The following steps are involved: Step 1, adding montmorillonite to water for ultrasonic treatment, and then centrifuging to obtain a supernatant; centrifuging the supernatant, and freeze-drying the obtained precipitate to obtain pretreated montmorillonite; Step 2, dispersing the pretreated montmorillonite in water and adjusting the pH value of the solution to be acidic and stirring; then adding trivalent iron salt, stirring, and centrifuging; dispersing the precipitate obtained by centrifugation in a trivalent iron salt solution, stirring, and centrifuging; repeating the above steps of dispersing the precipitate obtained by centrifugation in a trivalent iron salt solution, stirring, and centrifuging; Step 3, washing the precipitate obtained by the last centrifugation in step 2, and then freeze-drying it to obtain the iron-modified montmorillonite.

2. The method for preparing iron-modified montmorillonite according to claim 1, characterized in that: In step 1, the particle size of the montmorillonite is 200 meshes.

3. The method for preparing iron-modified montmorillonite according to claim 1, characterized in that: In step 1, the mass ratio of the montmorillonite to the water is 1:20; the power of the ultrasonic treatment is 40 KHz, and the time is 2 hours.

4. The method for preparing iron-modified montmorillonite according to claim 1, characterized in that: In step 1, when preparing the supernatant, the centrifugal conditions are: centrifugation at a centrifugal force of 60g for 10 minutes; when centrifuging the supernatant, centrifugation at a centrifugal force of 3500g for 10 minutes.

5. The method for preparing iron-modified montmorillonite according to claim 1, characterized in that: In step 2, the stirring speed is 300 rpm, the stirring time is 4 h, and the pH value is 6.

8.

6. The method for preparing iron-modified montmorillonite according to claim 1, characterized in that: In step 2, the ferric iron salt is FeCl3·6H2O; the ferric iron salt is added to a concentration of 25-30 g / L in the solution; the stirring rate of the ferric iron salt is 300 rpm, and the stirring time is 8 hours; the centrifugal force of the centrifugation after the ferric iron salt is added and stirred is 3500 g, and the centrifugation time is 10 minutes; the number of repetitions is 1 to 8 times; the concentration of the ferric iron salt solution is 25-30 g / L, and the solvent is water.

7. The iron-modified montmorillonite prepared according to the preparation method according to any one of claims 1 to 6.

8. Use of the iron-modified montmorillonite as claimed in claim 7 in removing triazine herbicides from water.

9. The use according to claim 8, characterized in that: The triazine herbicide is simazine.

10. A method for degrading simazine in water, characterized in that: Adding the iron-modified montmorillonite and permonosulfate described in claim 7 to the wastewater containing simazine for degradation; the concentration of the iron-modified montmorillonite in the wastewater containing simazine is 0-1 mg / mL; the concentration of the permonosulfate in the wastewater containing simazine is 0-5 mM; the concentration of simazine in the wastewater containing simazine is not more than 10 mg / L; the pH of the wastewater containing simazine is 3-11.

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