Gel composition, its preparation method and its application in Fenton oxidation treatment of organic wastewater

Abstract

This invention relates to the field of organic wastewater treatment, and discloses a gel composition, its preparation method, and its application in the Fenton oxidation treatment of organic wastewater. The preparation method of the gel composition includes: (1) preparing a coprecipitate containing Fe and Ce by coprecipitation; (2) mixing the Fe and Ce coprecipitate with a hydrogel solution to obtain material A; (3) mixing ascorbic acid, hydrogen phthalate, and Ce salt in the presence of water to obtain material B; and (4) adding material A to material B for gelation treatment to obtain the gel composition. Introducing the gel composition of this invention into the Fenton reaction system at time T can stabilize Fe... 2+ and Fe 3+ The molar ratio of [specific parameters] rapidly and efficiently improves the COD degradation rate of organic wastewater.

Description

Technical Field

[0001] This invention relates to the field of organic wastewater treatment, specifically to a gel composition, a method for preparing the gel composition, the application of the gel composition in Fenton oxidation treatment of organic wastewater, and a method for Fenton oxidation treatment of organic wastewater. Background Technology

[0002] Fenton oxidation technology uses Fe 2+ The process involves a chain reaction with H2O2 to generate highly oxidizing hydroxyl radicals that degrade pollutants in water. This method is simple; however, the traditional Fenton system... 3+ with Fe 2+ The conversion is thermodynamically limited, resulting in the required Fe 2+ High concentrations of H2O2 can cause significant damage to water quality and equipment.

[0003] Invention CN111732181A discloses a multiphase Fenton reagent that introduces transition metal sulfides as co-catalysts to reduce the dissolution of ferric iron and improve the continuous stability of the system. However, sulfides themselves are difficult-to-treat pollutants, and subsequent pollution problems still need to be addressed.

[0004] Invention CN113087119A discloses a method for promoting Fenton oxidation, which introduces transition metal elements or transition metal alloys as reducing intermediate bridging materials to reduce ferric iron to ferrous iron, thereby improving the reaction rate and efficiency of Fenton oxidation. However, this method is only applicable to organic wastewater with low COD concentration and is not effective for medium- to high-concentration organic wastewater. Summary of the Invention

[0005] The technical problem to be solved by the present invention is the low COD removal rate in the prior art when Fenton oxidation treatment of organic wastewater. The present invention provides a gel composition, a method for preparing the gel composition, the application of the gel composition in the Fenton oxidation treatment of organic wastewater, and a method for the Fenton oxidation treatment of organic wastewater. When the gel composition is used for the Fenton oxidation treatment of organic wastewater, it has the advantage of high COD removal rate.

[0006] To achieve the above objectives, a first aspect of the present invention provides a method for preparing a gel composition, the method comprising:

[0007] (1) A coprecipitate containing Fe and Ce was prepared by coprecipitation method;

[0008] (2) The coprecipitate containing Fe and Ce is mixed with a hydrogel solution to obtain material A;

[0009] (3) In the presence of water, ascorbic acid, hydrogen phthalate and Ce salt are mixed to obtain material B;

[0010] (4) Add material A to material B for gelation treatment to obtain the gel composition.

[0011] A second aspect of the present invention provides a gel composition prepared according to the method described above.

[0012] A third aspect of the present invention provides the use of the gel composition described above in the Fenton oxidation treatment of organic wastewater.

[0013] A fourth aspect of the present invention provides a Fenton oxidation treatment method for organic wastewater, the method comprising: adding ferrous salt and hydrogen peroxide to the organic wastewater to carry out a Fenton reaction, and introducing the gel composition as described above into the Fenton reaction system.

[0014] The inventors discovered that the gel composition prepared by the method described in this invention can slowly adsorb Fe in the Fenton oxidation system. 3+ It is reduced to Fe 2+ The decomposition of hydrogen peroxide continues to generate hydroxyl radicals, maintaining the Fe content within the system. 2+ with Fe 3+ The molar ratio is increased to improve catalytic efficiency, thereby rapidly and effectively increasing the COD degradation rate of organic wastewater.

[0015] The inventors of this invention have also discovered that using ascorbic acid and potassium hydrogen phthalate simultaneously to prepare a gel composition has a better effect in Fenton oxidation treatment than using them alone, indicating at least that there is a synergistic effect between ascorbic acid and potassium hydrogen phthalate, which makes the gel composition better improve catalytic efficiency. Detailed Implementation

[0016] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0017] The first aspect of the present invention provides a method for preparing a gel composition, the method comprising:

[0018] (1) A coprecipitate containing Fe and Ce was prepared by coprecipitation method;

[0019] (2) The coprecipitate containing Fe and Ce is mixed with a hydrogel solution to obtain material A;

[0020] (3) In the presence of water, ascorbic acid, hydrogen phthalate and Ce salt are mixed to obtain material B;

[0021] (4) Add material A to material B for gelation treatment to obtain the gel composition.

[0022] In step (1), the coprecipitation method can be a conventional coprecipitation method in the art. For example, the coprecipitation method may include: contacting Fe salt, Ce salt, and a precipitant in the presence of water and coprecipitating to obtain the Fe and Ce-containing coprecipitate. Each material can be dissolved in water separately and then mixed, and finally mixed with the precipitant or its solution. After coprecipitation, the obtained material can be subjected to solid-liquid separation (e.g., centrifugation, filtration), and then washed for further processing. Alternatively, the obtained precipitate can be resuspended to prepare a suspension for later use.

[0023] In step (1), the Fe is preferably Fe 2+ That is, the Fe salt can be a conventional divalent ferric salt in the art, such as ferrous sulfate and / or ferrous chloride (which can also exist in the form of hydrates).

[0024] In step (1), Ce is preferably Ce 3+ and / or Ce 4+ Ce is preferred. 4+ That is, the Ce salt can be a trivalent and / or tetravalent cerium salt conventional in the art, such as at least one selected from cerium ammonium nitrate ((NH4)2Ce(NO3)6), cerium ammonium sulfate ((NH4)4Ce(SO4)4), cerium nitrate (Ce(NO3)3) and cerium trichloride (CeCl3) (which may also exist in the form of hydrate, such as CeCl3·7H2O), more preferably cerium ammonium nitrate ((NH4)2Ce(NO3)6) and / or cerium ammonium sulfate ((NH4)4Ce(SO4)4).

[0025] Preferably, in step (1), the molar ratio of Fe to Ce is 1-10, more preferably 1-5, such as 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, and any range between any two values.

[0026] Preferably, based on the total molar amount of Fe and Ce elements, the amount of the precipitant used is 5-25 mol compared to 1 mol of metal element, for example, it can be 5, 10, 15, 20, 25 mol or any range between any two values.

[0027] The precipitant can be a conventional precipitant in the art, and preferably, the precipitant is selected from at least one of urea, ammonia and oxalic acid.

[0028] Preferably, in the coprecipitation system, the total content of Fe and Ce elements is 0.1-5% by weight, for example, it can be 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5% by weight, or any range between any two values.

[0029] Preferably, the conditions for the precipitation reaction include: a temperature of 60-120℃, more preferably 80-100℃; and a time of 6-24h, more preferably 8-12h.

[0030] In step (2), the Fe and Ce coprecipitate is mixed with a hydrogel solution to obtain material A, wherein the Fe and Ce coprecipitate can be added in the form of a suspension. The content of the coprecipitate in the suspension is preferably 40-80% by weight.

[0031] Preferably, in step (2), compared to the total weight of Fe and Ce elements in step (1) by 1 part by weight, the amount of solute used in the hydrogel solution is 0.1-10 parts by weight, for example, it can be 0.1, 0.5, 1, 1.5, 2, 3, 4, 5, 6, 7, 8, 9, 10 parts by weight and any range between any two values, more preferably 0.2-2 parts by weight.

[0032] Preferably, the solute content in the hydrogel solution is 1-20% by weight, for example, it can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20% by weight and any range between any two values.

[0033] The raw materials used to prepare the hydrogel solution can be conventional materials in the art that can produce hydrogels, such as at least one selected from agar, alginate (e.g., sodium alginate), gum arabic, gelatin, xanthan gum, guar gum, and carrageenan.

[0034] In step (2), mixing can be carried out by means such as stirring. There is no particular limitation on the mixing time, as long as the materials are mixed evenly. Preferably, the mixing time is 10-30 minutes.

[0035] In step (3), ascorbic acid, hydrogen phthalate, and Ce salt are mixed in the presence of water to obtain material B. There are no particular restrictions on the order of addition of the materials; for example, ascorbic acid and hydrogen phthalate can be added to the Ce salt solution.

[0036] Preferably, in step (3), the content of ascorbic acid in material B is 0.5-5 g / L, for example, it can be 0.5, 1, 2, 3, 4, 5 g / L or any range between any two values.

[0037] Preferably, in step (3), the weight ratio of ascorbic acid to hydrogen phthalate is 1-5, for example, it can be 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5 and any range between any two values.

[0038] Preferably, in step (3), the content of Ce element is 1-20 g / L, for example, it can be 1, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20 g / L and any range between any two values.

[0039] Preferably, the ratio of the total molar amount of Fe and Ce elements in step (1) to the molar amount of Ce element in step (3) is 0.1-4, for example, it can be 0.1, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4 and any range between any two values.

[0040] Preferably, in step (3), the hydrogen phthalate is sodium hydrogen phthalate and / or potassium hydrogen phthalate.

[0041] In step (3), the Ce salt is Ce 3+ Salt and / or Ce 4+ The salt, for example, may be selected from at least one of cerium ammonium nitrate, cerium ammonium sulfate, cerium nitrate and cerium trichloride (which may also exist in the form of hydrate), and may be the same as or different from the cerium salt used for co-precipitation in step (1).

[0042] In step (4), material A is added to material B for gelation treatment to obtain the gel composition. The addition rate can be controlled during the addition process to obtain hydrogel balls.

[0043] In this invention, the gelled material can also be post-processed to obtain the final product. Preferably, the method further includes: subjecting the gelled material to settling, solid-liquid separation, and drying to obtain the gel composition.

[0044] Preferably, the settling time is 20-30 hours.

[0045] The solid-liquid separation method can be a conventional method in the art, such as centrifugation or filtration.

[0046] Preferably, the drying method is one of air drying, oven drying, and vacuum drying.

[0047] Preferably, the drying conditions include a temperature of 40-80°C and a time of 10-24 hours.

[0048] A second aspect of the present invention provides a gel composition prepared according to the method described above.

[0049] A third aspect of the present invention provides the use of the gel composition described above in the Fenton oxidation treatment of organic wastewater.

[0050] The gel composition plays a role in stabilizing Fe in the Fenton oxidation system. 2+ and Fe 3+ The molar ratio promotes the degradation of COD in organic wastewater.

[0051] A fourth aspect of the present invention provides a Fenton oxidation treatment method for organic wastewater, the method comprising: adding ferrous salt and hydrogen peroxide to the organic wastewater to carry out a Fenton reaction, and introducing the gel composition as described above into the Fenton reaction system.

[0052] The gel composition can be introduced into the reaction system at any time point or during any period before the end of the Fenton reaction. Preferably, the gel composition is introduced before and / or during the Fenton reaction, for example, 1-10 minutes after the start of the reaction, preferably 1-5 minutes. The introduction method can be at least one of single addition, multiple additions, and continuous addition. After the gel composition is introduced, it can stabilize the Fe in the reaction system. 2+ and Fe 3+ The molar ratio is such that the stabilization time can be 5-30 minutes after introduction.

[0053] In a preferred embodiment of the present invention, when the gel composition is introduced, Fe in the Fenton reaction system 2+ and Fe 3+ The molar ratio is 0.5-1. In the preferred case, this is more conducive to promoting COD degradation.

[0054] Preferably, the amount of the gel composition, by weight, is related to the amount of Fe in the ferrous salt. 2+ The dosage ratio is 0.5-10, for example, it can be 0.5, 1, 2, 4, 6, 8, 10, or any range between any two values.

[0055] The organic wastewater can be any conventional organic wastewater in the field, as long as it contains COD. The method for determining COD can refer to the national standard GB / T34500.2-2017 Determination of Chemical Oxygen Demand (COD).

[0056] Preferably, the molar ratio of COD to H2O2 in the organic wastewater is 0.1-10, more preferably 0.2-2, and even more preferably 0.5-1.

[0057] Preferably, the H2O2 reacts with Fe in the divalent iron salt. 2+ The molar ratio is 1-100, preferably 2-50.

[0058] The ferrous salt can be any conventional ferrous salt in this field, and both ferrous salt and hydrogen peroxide are commercially available.

[0059] For specific procedures of the Fenton reaction, please refer to the standard procedures in this field, which will not be elaborated here.

[0060] The present invention will be described in detail below through embodiments.

[0061] In the following examples, the iron content was detected using a UV-1200 spectrophotometer; specifically, the total iron content was detected at a wavelength of 510 nm. 2+ The content was detected at a wavelength of 510 nm by diphenanthroline spectrophotometry; Fe 3+ The content is calculated by subtracting the ferrous iron content from the total iron content.

[0062] Unless otherwise specified, the reagents and materials used in the following examples and comparative examples were all commercially available, and the methods employed were all conventional methods in the art.

[0063] Example 1

[0064] This embodiment illustrates the preparation method of the gel composition and its application in the Fenton oxidation treatment of organic wastewater.

[0065] (1) Preparation of gel composition

[0066] Add 150 mL of FeSO4·7H2O containing 1 g Fe and (NH4)2Ce(NO3)6 containing 1 g Ce to 200 mL of aqueous solution containing 20 g urea. Stir and heat in a 95°C water bath for 8 h. Centrifuge and wash twice to obtain a suspension. Add the suspension to 20 mL of aqueous solution containing 1 g sodium alginate and stir at high speed for 20 min to obtain a mixed gel. Add 0.3 g ascorbic acid and 0.1 g potassium hydrogen phthalate to 250 mL of Ce(NO3)3 aqueous solution containing 3 g Ce and stir until homogeneous to obtain system B. Add the mixed gel dropwise to system B using a syringe to form hydrogel spheres. Let stand for 24 h, wash twice with deionized water, and dry at 60°C for 12 h to obtain the gel composition.

[0067] (2) Fenton reaction of organic wastewater

[0068] The organic wastewater is simulated acetic acid wastewater (COD 2000 mg / L); FeSO4·7H2O and H2O2 are added to it to make the organic wastewater contain 1 g / L FeSO4·7H2O and 2 g / L H2O2, respectively, to carry out Fenton oxidation reaction. The temperature during the reaction process is 25℃.

[0069] Three minutes after the reaction started (total iron content was 200 mg / L, Fe...) 2+ with Fe3+ The contents were 83 mg / L and 117 mg / L, respectively, Fe 2+ with Fe 3+ The molar ratio was 0.7 (referred to as time T). The gel composition prepared in step (1) was added as a catalyst, and the amount of the gel composition was 1 g / L. Then, 20 min after adding the gel composition (referred to as time N), the Fe was measured. 2+ with Fe 3+ The content of Fe was calculated. 2+ with Fe 3+ The molar ratios are shown in Table 1.

[0070] The reaction was stopped after 30 minutes. The COD results and COD removal rate of the acetic acid simulated wastewater are shown in Table 2.

[0071] Example 2

[0072] This embodiment illustrates the preparation method of the gel composition and its application in the Fenton oxidation treatment of organic wastewater.

[0073] (1) Preparation of gel composition

[0074] Add 150 mL of FeSO4·7H2O containing 0.5 g Fe and (NH4)4Ce(SO4)4 containing 1 g Ce to 200 mL of urea aqueous solution containing 20 g urea. Stir and heat in a 95°C water bath for 8 h. Centrifuge and wash twice to obtain a suspension. Add the suspension to 20 mL of aqueous solution containing 1 g sodium alginate and stir at high speed for 20 min to obtain a mixed gel. Add 0.3 g ascorbic acid and 0.1 g potassium hydrogen phthalate to 250 mL of Ce(NO3)3 aqueous solution containing 3 g Ce and stir until homogeneous to obtain system B. Add the mixed gel dropwise to system B using a syringe to form hydrogel spheres. Let stand for 24 h, wash twice with deionized water, and dry at 60°C for 12 h to obtain the gel composition.

[0075] (2) Fenton reaction of organic wastewater

[0076] Operate according to the method in Example 1.

[0077] The results for time N and the end of the reaction are shown in Table 1 and Table 2, respectively.

[0078] Example 3

[0079] This embodiment illustrates the preparation method of the gel composition and its application in the Fenton oxidation treatment of organic wastewater.

[0080] (1) Preparation of gel composition

[0081] Add 150 mL of FeSO4·7H2O containing 1 g Fe and (NH4)2Ce(NO3)6 aqueous solution containing 1 g Ce to 200 mL of urea aqueous solution containing 15 g urea. Stir and heat in a 95°C water bath for 8 h. Centrifuge and wash twice to obtain a suspension. Add the suspension to 20 mL of aqueous solution containing 1 g sodium alginate and stir at high speed for 20 min to obtain a mixed gel. Add 0.2 g ascorbic acid and 0.1 g potassium hydrogen phthalate to 250 mL of CeCl3 aqueous solution containing 4 g Ce and stir until homogeneous to obtain system B. Add the mixed gel dropwise to system B using a syringe to form hydrogel spheres. Let stand for 24 h, wash twice with deionized water, and dry at 60°C for 12 h to obtain the gel composition.

[0082] (2) Fenton reaction of organic wastewater

[0083] Operate according to the method in Example 1.

[0084] The results for time N and the end of the reaction are shown in Table 1 and Table 2, respectively.

[0085] Example 4

[0086] This embodiment illustrates the preparation method of the gel composition and its application in the Fenton oxidation treatment of organic wastewater.

[0087] (1) Preparation of gel composition

[0088] Add 150 mL of FeSO4·7H2O containing 0.8 g Fe and (NH4)4Ce(SO4)4 containing 1 g Ce to 200 mL of urea aqueous solution containing 18 g urea. Stir and heat in a 95°C water bath for 8 h. Centrifuge and wash twice to obtain a suspension. Add the suspension to 20 mL of aqueous solution containing 2 g sodium alginate and stir at high speed for 20 min to obtain a mixed gel. Add 0.3 g ascorbic acid and 0.2 g potassium hydrogen phthalate to 250 mL of Ce(NO3)3 aqueous solution containing 4 g Ce and stir until homogeneous to obtain system B. Add the mixed gel dropwise to system B using a syringe to form hydrogel spheres. Let stand for 24 h, wash twice with deionized water, and dry at 60°C for 12 h to obtain the gel composition.

[0089] (2) Fenton reaction of organic wastewater

[0090] Operate according to the method in Example 1.

[0091] The results for time N and the end of the reaction are shown in Table 1 and Table 2, respectively.

[0092] Example 5

[0093] This embodiment illustrates the preparation method of the gel composition and its application in the Fenton oxidation treatment of organic wastewater.

[0094] (1) Preparation of gel composition

[0095] The method described in Example 1 is followed, except that in preparing the gel composition, the total amount of Fe and Ce elements remains unchanged in step (1), and the molar ratio of Fe to Ce is 5.

[0096] (2) Fenton reaction of organic wastewater

[0097] Operate according to the method in Example 1.

[0098] The results for time N and the end of the reaction are shown in Table 1 and Table 2, respectively.

[0099] Example 6

[0100] This embodiment illustrates the preparation method of the gel composition and its application in the Fenton oxidation treatment of organic wastewater.

[0101] (1) Preparation of gel composition

[0102] The method described in Example 1 is followed, except that, when preparing the gel composition, an aqueous solution of cerium nitrate containing 1gCe is used instead of an aqueous solution of (NH4)2Ce(NO3)6 containing 1gCe.

[0103] (2) Fenton reaction of organic wastewater

[0104] Operate according to the method in Example 1.

[0105] The results for time N and the end of the reaction are shown in Table 1 and Table 2, respectively.

[0106] Example 7

[0107] This embodiment illustrates the preparation method of the gel composition and its application in the Fenton oxidation treatment of organic wastewater.

[0108] (1) Preparation of gel composition

[0109] The procedure was performed according to Example 1, except that the amount of sodium alginate used was 4g.

[0110] (2) Fenton reaction of organic wastewater

[0111] Operate according to the method in Example 1.

[0112] The results for time N and the end of the reaction are shown in Table 1 and Table 2, respectively.

[0113] Example 8

[0114] This embodiment illustrates the preparation method of the gel composition and its application in the Fenton oxidation treatment of organic wastewater.

[0115] (1) Preparation of gel composition

[0116] Operate according to the method in Example 1.

[0117] (2) Fenton reaction of organic wastewater

[0118] The procedure is the same as in Example 1, except that the amount of the gel composition used is 0.5 g / L.

[0119] The results for time N and the end of the reaction are shown in Table 1 and Table 2, respectively.

[0120] Example 9

[0121] This embodiment illustrates the preparation method of the gel composition and its application in the Fenton oxidation treatment of organic wastewater.

[0122] (1) Preparation of gel composition

[0123] Operate according to the method in Example 1.

[0124] (2) Fenton reaction of organic wastewater

[0125] The procedure was performed according to Example 1, except that the amount of the gel composition used was 5 g / L.

[0126] The results for time N and the end of the reaction are shown in Table 1 and Table 2, respectively.

[0127] Example 10

[0128] This embodiment illustrates the preparation method of the gel composition and its application in the Fenton oxidation treatment of organic wastewater.

[0129] (1) Preparation of gel composition

[0130] Operate according to the method in Example 1.

[0131] (2) Fenton reaction of organic wastewater

[0132] The procedure was followed as described in Example 1, except that 5 minutes after the start of the reaction (total iron content was 200 mg / L, Fe...) 2+ with Fe 3+ The contents were 75 mg / L and 125 mg / L, respectively, Fe 2+ with Fe 3+ The molar ratio is 0.6, denoted as time T, when the catalyst is added.

[0133] The results for time N and the end of the reaction are shown in Table 1 and Table 2, respectively.

[0134] Example 11

[0135] This embodiment illustrates the preparation method of the gel composition and its application in the Fenton oxidation treatment of organic wastewater.

[0136] (1) Preparation of gel composition

[0137] Operate according to the method in Example 1.

[0138] (2) Fenton reaction of organic wastewater

[0139] The procedure was followed as in Example 1, except that a catalyst was added at the beginning of the reaction.

[0140] The results for time N and the end of the reaction are shown in Table 1 and Table 2, respectively.

[0141] Comparative Example 1

[0142] This comparative example illustrates the case of Fenton oxidation without the addition of a catalyst.

[0143] The procedure was carried out according to the method of Example 1, except that the gel composition was not introduced as a catalyst during the reaction.

[0144] The results for time N and the end of the reaction are shown in Table 1 and Table 2, respectively.

[0145] Comparative Example 2

[0146] This comparative example illustrates the Fenton oxidation process with the addition of a reference catalyst.

[0147] The procedure was carried out according to Example 1, except that an equimolar amount of ascorbic acid was used instead of potassium hydrogen phthalate during the preparation of the gel composition, that is, the amount of ascorbic acid used was 0.39 g (2.19 mmol), and the prepared gel composition was used as a catalyst.

[0148] The results for time N and the end of the reaction are shown in Table 1 and Table 2, respectively.

[0149] Comparative Example 3

[0150] This comparative example is used to illustrate the Fenton oxidation treatment with the addition of a reference catalyst.

[0151] The procedure was carried out according to Example 1, except that an equimolar amount of potassium hydrogen phthalate was used instead of ascorbic acid during the preparation of the gel composition, that is, the amount of potassium hydrogen phthalate was 0.45 g (2.19 mmol), and the prepared gel composition was used as a catalyst.

[0152] The results for time N and the end of the reaction are shown in Table 1 and Table 2, respectively.

[0153] Comparative Example 4

[0154] This comparative example is used to illustrate the Fenton oxidation treatment of the reference catalyst.

[0155] The procedure was carried out according to Example 1, except that, in the preparation of the gel composition, an equimolar amount of oxalic acid was used instead of potassium hydrogen phthalate, and the prepared gel composition was used as a catalyst.

[0156] The results for time N and the end of the reaction are shown in Table 1 and Table 2, respectively.

[0157] Comparative Example 5

[0158] This comparative example is used to illustrate the Fenton oxidation treatment of the reference catalyst.

[0159] (1) Preparation of gel composition

[0160] Add 150 mL of FeSO4·7H2O containing 1 g Fe, (NH4)2Ce(NO3)6 containing 1 g Ce, and Ce(NO3)3 containing 3 g Ce to 200 mL of urea aqueous solution containing 20 g urea. Stir and heat in a 95°C water bath for 8 h. Centrifuge and wash twice to obtain a suspension. Add the suspension to 20 mL of aqueous solution containing 1 g sodium alginate and stir at high speed for 20 min to obtain a mixed gel. Add 0.3 g ascorbic acid and 0.1 g potassium hydrogen phthalate to 250 mL of aqueous solution and stir evenly to obtain system B. Add the mixed gel dropwise to system B using a syringe to form hydrogel spheres. Let stand for 24 h, wash twice with deionized water, and dry at 60°C for 12 h to obtain the gel composition.

[0161] (2) Fenton reaction of organic wastewater

[0162] Perform the operation according to the method in Example 1.

[0163] The results for time N and the end of the reaction are shown in Table 1 and Table 2, respectively.

[0164] Table 1

[0165]

[0166]

[0167] Table 2

[0168]

[0169]

[0170] The results above show that, by adopting the technical solution of the present invention, under the conditions of reaction temperature 25℃, FeSO4·7H2O dosage of 1g / L, H2O2 dosage of 10g / L, time T of 3min, and addition of 1g / L of catalyst, the COD of acetic acid simulated wastewater can be effectively degraded, the COD value is reduced from 2000mg / L to 187mg / L, and the removal rate reaches 90.7%, achieving good technical results.

[0171] Comparative Example 1 used the same Fenton oxidation catalyst and conditions as the Examples, but without the catalyst promoter prepared in this invention. The corresponding time N was Fe. 2+ with Fe 3+ The molar ratio decreases sharply, resulting in poor Fenton oxidation effect.

[0172] A comparison of Example 1 with Comparative Examples 2 and 3 shows that, compared to using either alone, the simultaneous use of ascorbic acid and potassium hydrogen phthalate to prepare the gel composition has a better effect in Fenton oxidation treatment. This indicates at least that there is a synergistic effect between ascorbic acid and potassium hydrogen phthalate, which enables the gel composition to better improve catalytic efficiency.

[0173] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing a gel composition, characterized in that, The method includes: (1) A coprecipitate containing Fe and Ce was prepared by coprecipitation method; (2) The coprecipitate containing Fe and Ce is mixed with the hydrogel solution to obtain material A; (3) In the presence of water, ascorbic acid, hydrogen phthalate and Ce salt are mixed to obtain material B; (4) Add material A to material B and perform gelation treatment to obtain the gel composition; In step (1), the molar ratio of Fe to Ce is 1-10. In step (2), the amount of solute used in the hydrogel solution is 0.1-10 parts by weight, compared to the total weight of Fe and Ce elements in step (1) of 1 part by weight. In step (3), the content of ascorbic acid in material B is 0.5-5 g / L, the content of Ce element is 1-20 g / L, and the weight ratio of ascorbic acid to hydrogen phthalate is 1-5. The ratio of the total molar amount of Fe and Ce in step (1) to the molar amount of Ce in step (3) is 0.1-4.

2. The method according to claim 1, wherein, The solute content in the hydrogel solution is 1-20% by weight.

3. The method according to claim 1, wherein, In step (1), the Fe is Fe 2+ , and / or In step (1), Ce is Ce 3+ and / or Ce 4+ ; In step (2), the raw materials used to prepare the hydrogel solution are selected from at least one of agar, alginate, gum arabic, gelatin, xanthan gum, guar gum, and carrageenan; and / or In step (3), the hydrogen phthalate is sodium hydrogen phthalate and / or potassium hydrogen phthalate; and / or In step (3), the Ce salt is Ce 3+ Salt and / or Ce 4+ Salt.

4. The method according to claim 3, wherein, In step (1), Ce is Ce 4+ .

5. The method according to claim 1, wherein, The coprecipitation method includes: contacting Fe salt, Ce salt and precipitant in the presence of water and coprecipitating to obtain the coprecipitate containing Fe and Ce.

6. The method according to claim 5, wherein, Based on the total molar amount of Fe and Ce elements, the amount of the precipitant used is 5-25 mol compared to 1 mol of metal elements.

7. The method according to claim 5, wherein, The precipitant is selected from at least one of urea, ammonia and oxalic acid.

8. The method according to claim 5, wherein, In the coprecipitation system, the total content of Fe and Ce elements is 0.1-5% by weight.

9. The method according to claim 1, wherein, The conditions for the coprecipitation method include: a temperature of 60-120℃ and a time of 6-24h.

10. The method according to claim 9, wherein, The conditions for the coprecipitation method include: a temperature of 80-100℃ and a time of 8-12h.

11. The method according to claim 1, wherein, The method further includes: allowing the gelled material to stand, separating the solid and liquid components, and drying it to obtain the gel composition.

12. The method according to claim 11, wherein, The settling time is 20-30 hours.

13. The method according to claim 11, wherein, The drying method is one of air drying, oven drying, and vacuum drying.

14. The method according to claim 11, wherein, The drying conditions include a temperature of 40-80℃ and a time of 10-24h.

15. The gel composition prepared by the method according to any one of claims 1-14.

16. The use of the gel composition of claim 15 in the Fenton oxidation treatment of organic wastewater.

17. A Fenton oxidation treatment method for organic wastewater, characterized in that, The method includes: adding ferrous salt and hydrogen peroxide to organic wastewater to carry out a Fenton reaction, and introducing the gel composition of claim 15 into the Fenton reaction system.

18. The method according to claim 17, wherein, The gel composition is introduced before and / or during the Fenton reaction.

19. The method according to claim 17, wherein, When the gel composition is introduced, in the Fenton reaction system, Fe 2+ and Fe 3+ The molar ratio is 0.5-1; and / or By weight, the amount of the gel composition used is related to the amount of Fe in the ferrous salt. 2+ The dosage ratio is 0.5-10.

20. The method of claim 17, wherein, The molar ratio of COD to H2O2 in the organic wastewater is 0.1-10; and / or The H2O2 and Fe in the divalent iron salt 2+ The molar ratio is 1-100.

21. The method according to claim 20, wherein, The molar ratio of COD to H2O2 in the organic wastewater is 0.2-2; and / or The H2O2 and Fe in the divalent iron salt 2+ The molar ratio is 2-50.

22. The method according to claim 21, wherein, The molar ratio of COD to H2O2 in the organic wastewater is 0.5-1.

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