Oil sludge thermal residue-based Fe (II)-ZIF composite phosphorus removal agent as well as preparation method and application thereof

Abstract

The invention relates to an oil sludge thermal residue-based Fe (II)-ZIF composite phosphorus removal agent as well as a preparation method and application thereof, and relates to the technical field of wastewater treatment. The preparation method of the oil sludge hot residue-based Fe (II)-ZIF composite phosphorus removal agent comprises the following steps: adding oil sludge hot residues into an HF solution, soaking, filtering to obtain primary treatment residues, washing the primary treatment residues with water until the primary treatment residues are neutral, and drying for later use; mixing the dried primary treatment slag with a 2-methylimidazole solution, and stirring to obtain a primary mixture; an ammonium ferrous sulfate solution and the primary mixture are mixed, stirred and centrifuged, and an obtained solid is an initial target object; the initial target object is subjected to freeze drying, and the oil sludge thermal residue based Fe (II)-ZIF composite phosphorus removal agent is obtained. The oil sludge hot residue-based Fe (II)-ZIF composite phosphorus removal agent which has high adsorption capacity and can adsorb phosphate in water under an acidic condition can be prepared through a low-cost simple process, and recycling of oil sludge hot residue resources is promoted.

Description

Technical Field

[0001] The present application belongs to the technical field of wastewater treatment, and more specifically relates to an oil sludge thermal residue-based Fe(II)-ZIF composite phosphorus removal agent, and a preparation method and use thereof. Background Art

[0002] With the rapid development of industry and the continuous improvement of residents' living standards, phosphorus is widely used as an industrial raw material and a common chemical element in daily life. The discharge of phosphorus into water bodies leads to eutrophication, which has a serious impact on the ecological environment. Therefore, the removal of phosphates in sewage has always been a key issue in the field of environmental protection.

[0003] At present, biological and chemical methods are mainly used to remove phosphate from sewage. The biological method relies on the metabolism of polyphosphate bacteria. By regulating the dissolved oxygen concentration of sewage, it changes the absorption and release function of polyphosphate bacteria microorganisms on phosphate, and removes phosphate from sewage in the form of activated sludge. The chemical method converts phosphate into inorganic compounds through the charge and adsorption bridging effect of metal ions, and then separates it from sewage.

[0004] However, although microbial phosphorus removal is economical, it is affected by ambient temperature and microbial activity, and the phosphorus removal efficiency is low. Although chemical methods can efficiently remove phosphates, they will also produce a large amount of chemical sludge, causing secondary pollution. Therefore, there is an urgent need to develop an environmentally friendly phosphorus removal agent with a high adsorption capacity. Summary of the invention

[0005] In view of the above-mentioned defects and problems of the prior art, the present application develops an oil sludge thermal residue-based Fe(II)-ZIF composite phosphorus removal agent and its preparation method and use.

[0006] The first aspect of the present application provides a method for preparing an oil sludge thermal residue-based Fe(II)-ZIF composite dephosphorizer, comprising the following steps:

[0007] Add the hot residue of the oil sludge into the HF solution, soak, filter, and obtain the primary treatment residue, wash the primary treatment residue with water until it is neutral, and dry for later use;

[0008] The dried primary treatment residue is mixed with a 2-methylimidazole solution and stirred to obtain a primary mixture;

[0009] The ammonium ferrous sulfate solution and the primary mixture are mixed, stirred, and centrifuged to obtain a solid as the initial target product;

[0010] The initial target product is freeze-dried to obtain the oil sludge thermal residue-based Fe(II)-ZIF composite phosphorus removal agent.

[0011] Optionally, the molar ratio of 2-methylimidazole to ammonium ferrous sulfate is (0.01-0.04):0.01.

[0012] Optionally, the concentration of the 2-methylimidazole solution is 0.01-0.04 mol / mL; the concentration of the ammonium ferrous sulfate solution is 0.005-0.03 mol / mL; and the mass of the primary treatment slag is 0.1-0.3 g.

[0013] Optionally, in the HF solution, the volume ratio of HF to water is 1:(0.05-1).

[0014] Optionally, the immersion time of the oil sludge hot residue in the HF solution is more than 0.1 h. Preferably, the immersion time of the oil sludge hot residue in the HF solution is determined by the time when the solution stops generating bubbles.

[0015] Optionally, the preparation method includes at least one of the following features (a)-(d):

[0016] (a) in the step of mixing the dried primary treatment slag with the 2-methylimidazole solution, the stirring speed is 200-600 r / min; the stirring time is 0.5-4h;

[0017] (b) in the step of mixing the ammonium ferrous sulfate solution and the primary mixture, the stirring speed is 200-600 r / min; the stirring time is 1-6 h;

[0018] (c) In the centrifugation step, the rotation speed is 500-4000 r / min and the centrifugation time is 1-30 min.

[0019] (d) The freeze drying temperature in the freeze drying step is -60 to 0°C; the freeze drying time is 0 to 24 hours.

[0020] On the other hand, the present application also provides an oil sludge thermal residue-based Fe(II)-ZIF composite phosphorus removal agent prepared by any of the above preparation methods.

[0021] Optionally, the maximum adsorption capacity of the oil sludge thermal residue-based Fe(II)-ZIF composite dephosphorizer prepared by any of the above preparation methods can reach 190 mg·g -1 -198.3mg g -1 , the total phosphorus content can be less than 0.5mg / L.

[0022] On the other hand, the present application also provides the use of the above-mentioned oil sludge thermal residue-based Fe(II)-ZIF composite phosphorus removal agent in the wastewater treatment process.

[0023] Optionally, the wastewater is the acidic environment of the anaerobic and anoxic units of the sewage biochemical system.

[0024] In summary, this application has the following beneficial effects:

[0025] The oil sludge thermal residue-based Fe(II)-ZIF composite phosphorus remover with high adsorption capacity can be prepared at low production cost through a simple preparation process, and is more suitable for the acidic environment of anaerobic and anoxic units of sewage biochemical systems. The oil sludge thermal residue-based Fe(II)-ZIF composite phosphorus remover can make sewage meet the sewage discharge standard requirement of a total phosphorus content of less than 0.5 mg / L through a combination of physical adsorption and chemical adsorption; and the composite phosphorus remover uses oil sludge thermal residue as raw material, which promotes the reuse of waste resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below.

[0027] Figure 1 This is an XRD characterization diagram of the oil sludge thermal residue-based Fe(II)-ZIF composite phosphorus removal agent prepared according to Example 1 of the present application;

[0028] Figure 2 This is an XPS characterization diagram of the oil sludge thermal residue-based Fe(II)-ZIF composite dephosphorizer prepared according to Example 1 of the present application, wherein: Figure 2 A is the existing form of Fe element in the composite phosphorus removal agent, Figure 2 B is the change before and after the adsorption of P element in the composite phosphorus removal agent.

[0029] Figure 3 This is the FT-IR characterization diagram of the oil sludge thermal residue-based Fe(II)-ZIF composite dephosphorizer prepared according to Example 1 of the present application;

[0030] Figure 4 The adsorption effect of the sludge thermal residue-based Fe(II)-ZIF composite phosphorus removal agent prepared according to Examples 1-3 of the present application is applied to sewage treatment. DETAILED DESCRIPTION

[0031] The present application is further described in detail with reference to the following examples. It should be noted that if no specific conditions are specified in the following examples, the conventional conditions or the conditions recommended by the manufacturer are followed, and the raw materials used in the following examples can be obtained from common commercial sources unless otherwise specified.

[0032] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0033] In this application, "first aspect", "second aspect", "third aspect", etc. are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first", "second", "third", etc. only serve the purpose of non-exhaustive enumeration and description, and it should be understood that they do not constitute a closed limitation on quantity.

[0034] In this application, "optionally", "optional", and "optional" mean optional or dispensable, that is, any one of the two parallel schemes of "yes" or "no". If multiple "options" appear in a technical solution, unless otherwise specified and there is no contradiction or mutual restriction, each "optional" is independent.

[0035] In this application, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0036] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0037] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used in this application and in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The meaning of the term "multiple" in this application is at least two, such as two, three, etc., unless otherwise clearly and specifically limited.

[0038] In order to facilitate the description of the technical solution of this application, the following materials and steps are described before starting the experiment of this application:

[0039] (1) The effective substance content of ammonium ferrous sulfate and 2-methylimidazole in the present application is ≥99wt%, and the effective substance content of HF is ≥40wt%.

[0040] (2) The sludge thermal residue in this application is taken from Jingmen Petrochemical General Plant. It is understandable that a large amount of oily sludge (referred to as sludge) is generated during the exploration, development, storage and transportation of oil and gas fields. The sludge pyrolysis residue comes from the pyrolysis process of sludge and is a solid waste rich in metal elements such as iron and aluminum. After the sludge is pyrolyzed, the organic matter in the residue is removed, leaving solid particles mainly composed of metal oxides.

[0041] (4) Fe(II)-ZIF is a zeolite imidazolate framework material. The preparation method of the oil sludge thermal residue-based Fe(II)-ZIF composite dephosphorizer of the present application comprises the following steps:

[0042] Step 1: Add the hot residue of the sludge into the HF solution, soak, filter, obtain the primary treatment residue, wash the primary treatment residue with water until it is neutral, and dry for later use.

[0043] In this step, the volume ratio of HF to deionized water is 1:(0.05-1), for example, the volume ratio of HF to deionized water is 1:0.05, 1:0.1, 1:0.5, 1:0.8 or 1:1; the immersion time of the hot sludge residue in the HF solution is more than 0.1h, for example, 0.5h, 1h, 1.5h, 10h or 11h, preferably, the immersion time of the hot sludge residue in the HF solution is when the solution stops generating bubbles as the timing end point; the mass of the initially treated slag obtained is 0.1-0.3g.

[0044] It should be noted that by immersing the sludge thermal residue in the HF solution, SiO2 in the sludge thermal residue can be effectively removed to increase the specific surface area of ​​the sludge thermal residue. In addition, by adjusting the volume ratio of HF and deionized water in the HF solution, SiO2 in the sludge thermal residue can be removed in the form of SiF4, and at the same time, the specific surface area of ​​the sludge thermal residue is increased.

[0045] Step 2: Mix the dried primary treatment residue with a 2-methylimidazole solution, and stir to obtain a primary mixture.

[0046] In this step, the stirring speed is 200-600r / min; the stirring time is 0.5-4h. For example, the stirring speed may be 200r / min, 250r / min, 300r / min, 400r / min or 500r / min. A low rotation speed cannot make 2-methylimidazole evenly adhere to the pores and surface of the primary treatment slag after drying; and too high a rotation speed will cause the turbulence of the 2-methylimidazole solution to intensify, which is not conducive to the loading of 2-methylimidazole. For another example, the stirring time may be 0.5h, 1h, 2h, 3h or 4h. If the stirring time is too short, 2-methylimidazole cannot be completely adsorbed on the surface and pores of the primary treatment slag after drying; if the stirring time is too long, 2-methylimidazole has already been fully loaded, resulting in an increase in production costs.

[0047] The preparation method of the 2-methylimidazole solution is as follows: dissolve 2-methylimidazole in deionized water to obtain a 2-methylimidazole solution with a concentration of 0.01 to 0.04 mol / mL after the 2-methylimidazole is completely dissolved.

[0048] The inventors found that after the treatment of step 2, the dried primary treatment slag can be evenly attached to its pores and surface by physical adsorption. If the same amount of the dried primary treatment slag is treated, the concentration of 2-methylimidazole is too high, which is easy to cause waste of 2-methylimidazole and increase the residual amount of 2-methylimidazole. In the subsequent step of adding ammonium ferrous sulfate solution, redundant Fe(II)-ZIF will be formed in the pores and surface of the composite dephosphorization agent, thereby blocking the pore structure, resulting in reduced dephosphorization performance and increased production costs.

[0049] Step 3: Mix the ammonium ferrous sulfate solution and the primary mixture, stir, and centrifuge to obtain a solid as the initial target product.

[0050] In this step, the stirring speed is 200-600 r / min and the stirring time is 1-6 h. For example, the stirring speed may be 200 r / min, 250 r / min, 300 r / min, 400 r / min or 500 r / min, and the stirring time may be 1 h, 1.5 h, 2 h, 4 h or 6 h.

[0051] A low rotation speed cannot make the ammonium ferrous sulfate solution uniformly react with the 2-methylimidazole attached to the pores and surface of the dried primary treatment slag to form Fe(II)-ZIF material; a too fast rotation speed is not conducive to the loading of the Fe(II)-ZIF material due to the increased turbulence of the solution.

[0052] If the stirring time is too short, the specific surface area of ​​the Fe(II)-ZIF material formed is small, resulting in a decrease in the ability to adsorb phosphate in water; if the stirring time is too long, the volume of the Fe(II)-ZIF material formed is too large, which easily blocks the pores of the primary treatment slag, causing part of the Fe(II)-ZIF material in the pores to not be fully utilized during the phosphate adsorption process, resulting in a decrease in the phosphate adsorption capacity.

[0053] The preparation method of the ammonium ferrous sulfate solution is as follows: dissolve the ammonium ferrous sulfate in deionized water to obtain an ammonium ferrous sulfate solution with a concentration of 0.005 to 0.03 mol / mL after the ammonium ferrous sulfate is completely dissolved.

[0054] The molar ratio of 2-methylimidazole to ammonium ferrous sulfate is (0.01-0.04):0.01. When the molar ratio of 2-methylimidazole to ammonium ferrous sulfate is appropriate, good Fe(II)-ZIF materials can be obtained.

[0055] During the centrifugation process in this step, the speed of the centrifuge can be 500-4000 r / min, for example, the speed of the centrifuge can be 500 r / min, 550 r / min, 700 r / min, 1100 r / min or 4000 r / min; the centrifugation time can be 1-30 min. For example, the centrifugation time can be 1 min, 3 min, 10 min, 12 min or 30 min.

[0056] Step 4: freeze-drying the initial target product to obtain the oil sludge thermal residue-based Fe(II)-ZIF composite phosphorus removal agent.

[0057] In this step, the freeze drying temperature in the freeze drying step is -60 to 0°C; the freeze drying time is 0-24h. For example, the freeze drying temperature can be -1°C, -12°C, -20.5°C, -35°C or -60°C; the freeze drying time can be 0.1h, 1h, 12h, 21.5h or 24h. If the freeze drying temperature is too high, the Fe(II)-ZIF in the composite dephosphorizer is easily oxidized to Fe(II)-ZIF by air, and the dephosphorization capacity and the applicable solution pH range change significantly; if the freeze drying temperature is too low, the drying effect of the sludge thermal residue-based Fe(II)-ZIF composite dephosphorizer is poor, which affects the normal functioning of the sludge thermal residue-based Fe(II)-ZIF.

[0058] The Fe(II)-ZIF composite phosphorus remover based on thermal residue of sludge prepared by the above steps can realize resource treatment of oily sludge. The Fe(II)-ZIF composite phosphorus remover based on thermal residue of sludge has good phosphorus removal performance and can adsorb phosphate in water in an acidic environment, which is beneficial for the anaerobic and anoxic units in the biochemical system to cooperate with microorganisms to remove phosphate in water. In addition, the Fe(II)-ZIF composite phosphorus remover based on thermal residue of sludge can not only regulate the pore structure of the material, chemically adsorb phosphate in sewage, but also rely on the physical and chemical adsorption of thermal residue of sludge itself to further adsorb phosphate in water, so that the Fe(II)-ZIF composite phosphorus remover based on thermal residue of sludge has the function of physical and chemical adsorption of phosphate at the same time.

[0059] In summary, the oil sludge thermal residue-based Fe(II)-ZIF composite phosphorus removal agent of the present application has the following advantages:

[0060] (1) The composite phosphorus removal agent prepared by resource utilization of oil sludge thermal residue has a high adsorption capacity for phosphate in wastewater, with the maximum adsorption capacity reaching 198.3 mg·g -1 , which can meet the sewage discharge standard requirement of total phosphorus content less than 0.5 mg / L; (2) The composite phosphorus removal agent can adsorb phosphate in water under acidic conditions, and is more suitable for the acidic environment of anaerobic and anoxic units in sewage biochemical systems. (3) The preparation process has the advantages of mild and controllable conditions and low production cost.

[0061] It should be noted that the characteristics and advantages described above for the method for preparing the oil sludge thermal residue-based Fe(II)-ZIF composite dephosphorizer are also applicable to the composite dephosphorizer and will not be repeated here.

[0062] Example

[0063] Example 1

[0064] The preparation method of the oil sludge thermal residue-based Fe(II)-ZIF composite phosphorus removal agent is as follows:

[0065] (1) Dissolve 0.025 mol of 2-methylimidazole and 0.01 mol of ammonium ferrous sulfate in 20 mL of deionized water, respectively, to obtain a 2-methylimidazole solution and an ammonium ferrous sulfate solution after they are completely dissolved;

[0066] (2) Add 10 g of hot sludge residue to HF solution (V HF :V 水 =1:1), soak for 12 hours (when the solution stops producing bubbles), wash the primary treatment slag with deionized water until it is neutral, and dry it at 105°C for later use;

[0067] (3) adding 0.2 g of the dried primary treatment slag to 20 mL of 2-methylimidazole solution with a magnetic stirrer at a speed of 400 r / min, and continuing to stir for 1 h to obtain a primary mixture;

[0068] (4) adding 20 mL of ammonium ferrous sulfate solution to the initial mixture, stirring was continued at a stirring speed of 400 r / min for 3 h, and then centrifuged at a speed of 1000 r / min for 20 min. The solid obtained after centrifugation was the initial target product;

[0069] (5) The initial target product was freeze-dried at -60°C for 12 h to obtain an oil sludge thermal residue-based Fe(II)-ZIF composite phosphorus removal agent.

[0070] The operation steps of removing phosphorus from wastewater by using Fe(II)-ZIF composite phosphorus removal agent based on oil sludge thermal residue are as follows:

[0071] Firstly, 0.1 g of Fe(II)-ZIF composite phosphorus remover based on thermal residue of sludge was weighed and added into 1 L of phosphorus-containing wastewater (phosphorus concentration was 4 mg / L), stirred for 1 hour under magnetic stirring conditions, and centrifuged for 15 min to separate the Fe(II)-ZIF composite phosphorus remover based on thermal residue of sludge. The supernatant after centrifugation was taken to determine the phosphorus content in the water.

[0072] Example 2

[0073] The difference from Example 1 is that 0.01 mol of 2-methylimidazole is added in step (1), and the other steps are the same as Example 1.

[0074] Example 3

[0075] The difference from Example 1 is that 0.03 mol of 2-methylimidazole is added in step (1), and the other conditions are the same as in Example 1.

[0076] Comparative Example

[0077] Comparative Example 1

[0078] The difference from Example 1 is that:

[0079] Step (3), mixing 20 mL of the 2-methylimidazole solution prepared in step (1) and 20 mL of the ammonium ferrous sulfate solution, stirring at a stirring speed of 400 r / min for 1 h to obtain a mixed solution;

[0080] Step (4), adding 0.2 g of the dried primary treatment slag to the mixed solution obtained in step (3), stirring at a stirring speed of 400 r / min for 3 h, and then centrifuging at a speed of 1000 r / min for 20 min in a centrifuge, and the solid obtained after centrifugation is the initial target product;

[0081] The remaining steps are consistent with those in Example 1.

[0082] Comparative Example 2

[0083] The difference from Example 1 is that:

[0084] In step (1), 0.1 mol of 2-methylimidazole was added, and the remaining steps were consistent with Example 1.

[0085] Comparative Example 3

[0086] The difference from Example 1 is that:

[0087] In step (1), 0.003 mol of 2-methylimidazole was added, and the remaining steps were consistent with Example 1.

[0088] Since the structure and performance of the sludge thermal residue-based Fe(II)-ZIF composite dephosphorizer prepared in Examples 1-3 are similar to those of the sludge thermal residue-based Fe(II)-ZIF composite dephosphorizer prepared in Example 1, only the sludge thermal residue-based Fe(II)-ZIF composite dephosphorizer prepared in Example 1 is taken as an example. The XRD characterization results of the sludge thermal residue-based Fe(II)-ZIF composite dephosphorizer prepared in Example 1 are as follows: Figure 1 As shown by Figure 1 It can be seen that the XRD spectra of the oil sludge thermal residue (ae-OSPR), Fe(II)-ZIF and Fe(II)-ZIF / ae-OSPR after acid etching contain the characteristic peaks of ae-OSPR and Fe(II)-ZIF, proving the successful preparation of Fe(II)-ZIF / ae-OSPR.

[0089] The XPS characterization results of the oil sludge thermal residue-based Fe(II)-ZIF composite dephosphorizer prepared in Example 1 are as follows: Figure 2 As shown, Figure 2 A is the existing form of Fe element in the composite phosphorus removal agent, Figure 2 B is the change before and after the adsorption of P element in the phosphorus removal agent. Figure 1 and 2 It can be seen that the dephosphorus remover prepared in Example 1 has good adsorption capacity, Fe(II) is successfully loaded on the surface of the composite dephosphorus remover, and the increase in the intensity of the P element peak after adsorption shows that the dephosphorus remover has an obvious adsorption effect on phosphate.

[0090] The FT-IR characterization results of the oil sludge thermal residue-based Fe(II)-ZIF composite dephosphorizer prepared in Example 1 are as follows: Figure 3 As shown. Figure 3 It can be seen that the oil sludge thermal residue-based Fe(II)-ZIF composite phosphorus remover has more NH functional groups than ae-OSPR and Fe(II)-ZIF, which is beneficial to the adsorption of phosphorus pollutants in water.

[0091] Performance testing

[0092] Determination of the maximum adsorption capacity and total phosphorus content after adsorption of Fe(II)-ZIF composite phosphorus removal agent based on oil sludge thermal residue

[0093] Determination method: The total phosphorus determination is carried out according to the analysis steps in Part VI of GB11893 "Water quality - Determination of total phosphorus - Ammonium molybdate spectrophotometry".

[0094] The adsorption capacity of the oil sludge thermal residue-based Fe(II)-ZIF composite dephosphorizer is calculated based on the initial phosphorus concentration, the residual phosphorus concentration (i.e., the total phosphorus content after adsorption) and the amount of dephosphorizer used. That is, adsorption capacity = (initial phosphorus concentration - residual phosphorus concentration) / amount of dephosphorizer used. The data of the embodiment and comparative example are shown in Table 1:

[0095] Table 1. Data of Examples and Comparative Examples

[0096]

[0097] The above experimental data show that the maximum adsorption capacity of the Fe(II)-ZIF composite dephosphorization agent based on thermal residue of sludge prepared by the preparation method of the present application is relatively high, which helps to efficiently remove phosphorus from wastewater and ensure that the total phosphorus content in the treated wastewater meets the standard. The adsorption effect of the Fe(II)-ZIF composite dephosphorization agent based on thermal residue of sludge prepared in Examples 1-3 for wastewater treatment can be seen in Figure 4 shown.

[0098] According to the data of Example 1 and Comparative Example 1, 2-methylimidazole and ammonium ferrous sulfate need to be separately configured into solutions and then mixed with the dried primary treatment slag in sequence. If the 2-methylimidazole solution and the ammonium ferrous sulfate solution are mixed first, the adsorption performance of the obtained sludge thermal residue-based Fe(II)-ZIF composite dephosphorizer may be poor due to the low content of Fe(II)-ZIF loaded on the sludge thermal residue.

[0099] According to the data of Example 1 and Comparative Examples 2 and 3, a suitable molar ratio of 2-methylimidazole and ammonium ferrous sulfate is helpful for preparing an oil sludge thermal residue-based Fe(II)-ZIF composite phosphorus removal agent with good adsorption performance.

[0100] Application Examples

[0101] Application test of phosphorus removal agent prepared by resource utilization of sludge in a sewage treatment facility in a certain village in Panjin City. The test was carried out in a sewage treatment facility in a certain village in Panjin City to utilize oily sludge resources to prepare an industrial application of a sludge thermal residue-based Fe(II)-ZIF composite phosphorus removal agent. During the application process, the sludge thermal residue-based Fe(II)-ZIF composite phosphorus removal agent prepared in Example 1 at a dosage of 0.1g / L was added to the inlet pipeline of the sewage treatment facility. The total phosphorus content of the sewage before the application of the phosphorus removal agent was between 3.5-5.5mg / L. After 365 days of field application, it was proved that the total phosphorus content of the sewage was 0.42mg / L. It can be seen that the sludge thermal residue-based Fe(II)-ZIF composite phosphorus removal agent prepared in this application has better treatment indicators for phosphate in sewage.

[0102] It should be understood that the disclosed application is not limited to the specific methods, schemes and materials described, because these can be changed. It should also be understood that the terms used herein are only for the purpose of describing specific implementation schemes, rather than being intended to limit the scope of the application, and the scope of the application is limited only to the appended claims.

[0103] Those skilled in the art will also recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the application described herein. Such equivalents are also intended to be encompassed by the appended claims.

Claims

1. A method for preparing a Fe(II)-ZIF composite dephosphorizer based on oil sludge thermal residue, characterized in that: The steps include: Add the hot residue of the oil sludge into the HF solution, soak, filter, and obtain the primary treatment residue, wash the primary treatment residue with water until it is neutral, and dry for later use; The dried primary treatment residue is mixed with a 2-methylimidazole solution and stirred to obtain a primary mixture; The ammonium ferrous sulfate solution and the primary mixture are mixed, stirred, and centrifuged to obtain a solid as the initial target product; The initial target product is freeze-dried to obtain the oil sludge thermal residue-based Fe(II)-ZIF composite phosphorus removal agent.

2. The preparation method according to claim 1, characterized in that: The molar ratio of the 2-methylimidazole to ammonium ferrous sulfate is (0.01-0.04):0.

01.

3. The preparation method according to claim 2, characterized in that: The concentration of the 2-methylimidazole solution is 0.01-0.04 mol / mL; the concentration of the ammonium ferrous sulfate solution is 0.005-0.03 mol / mL; and the mass of the primary treatment slag is 0.1-0.3 g.

4. The preparation method according to claim 1, characterized in that: In the HF solution, the volume ratio of HF to water is 1:(0.05-1).

5. The preparation method according to claim 1, characterized in that: The immersion time of the oil sludge hot residue in the HF solution is more than 0.1h. Preferably, the immersion time of the oil sludge hot residue in the HF solution is determined by the time when the solution stops generating bubbles.

6. The preparation method according to claim 1, characterized in that: Includes at least one of the following features (a)-(d): (a) in the step of mixing the dried primary treatment slag with the 2-methylimidazole solution, the stirring speed is 200-600 r / min; the stirring time is 0.5-4 h; (b) in the step of mixing the ammonium ferrous sulfate solution and the primary mixture, the stirring speed is 200-600 r / min; the stirring time is 1-6 h; (c) In the centrifugation step, the rotation speed is 500-4000 r / min and the centrifugation time is 1-30 min; (d) The freeze drying temperature in the freeze drying step is -60 to 0°C; the freeze drying time is 0 to 24 hours.

7. The oil sludge thermal residue-based Fe(II)-ZIF composite phosphorus removal agent prepared by the preparation method according to any one of claims 1 to 6.

8. The oil sludge thermal residue-based Fe(II)-ZIF composite phosphorus removal agent according to claim 7, characterized in that: The maximum adsorption capacity can reach 190.5 mg g -1 -198.3mg g -1 , the total phosphorus content can be less than 0.5mg / L.

9. Use of the Ag(I)-based silica adsorbent according to any one of claims 7 to 8 in a wastewater treatment process.

10. The use of the Ag(I)-based silica adsorbent according to claim 9, characterized in that: The wastewater is the acidic environment of the anaerobic and anoxic units of the sewage biochemical system.

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