A preparation method and application of zero-valent iron sulfide based on iron sludge in water treatment plant

Abstract

The present invention belongs to the field of resource utilization of solid waste, and specifically relates to a preparation method and application of sulfided zero-valent iron based on iron sludge in a water treatment plant. The preparation method comprises: (1) the iron sludge in the water treatment plant is pretreated to become powder, and the iron sludge powder is modified by sulfur to obtain sulfur-loaded iron sludge; (2) after the reaction, the modified dry iron sludge is obtained after solid-liquid separation and drying; (3) the sulfur-loaded dry iron sludge sample is calcined to 800°C under anaerobic conditions to obtain sulfided nano zero-valent iron. The sulfided nano zero-valent iron prepared by the present invention provides a new path for the resource utilization of iron-containing sludge in water treatment plants. The invention has a simple operation process, a short preparation cycle and low cost. The prepared sulfided nano zero-valent iron can activate the degradation of organic pollutants by catalytic oxidation of molecular oxygen, persulfate and periodate in water, and has good universality in the field of environmental pollutant treatment and has broad market application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of resource utilization of solid waste from water plants and sewage treatment, and in particular to a method for preparing sulfided nano zero-valent iron based on iron sludge from water treatment plants and its application in the field of advanced oxidation removal of organic pollutants. Background Art

[0002] Zero valent iron (ZVI,Fe 0 ) As an environmentally friendly, low-cost and readily available water purification material, it has the characteristics of low reduction potential, large electron storage capacity, good adsorption characteristics and reactivity. In addition, advanced oxidation technology with zero-valent iron as the core has been gradually applied to the removal of pollutants in sewage and wastewater. In particular, the combination of zero-valent iron and oxidants can produce a variety of oxidative active species, which not only significantly improves the removal effect of pollutants, but also broadens the scope of use of zero-valent iron. However, due to the easy agglomeration of the ZVI surface and the formation of an iron oxide or oxyhydroxide passivation layer on the surface, its reactivity decreases.

[0003] Sulfide zero-valent iron (S-Fe 0 ) can slow down the aggregation and surface passivation of ZVI. x The shell is more electronically conductive and active than the iron oxide film, and the sulfide species can promote the conversion of Fe(III) to Fe(II) and improve the recovery of Fe(II). 0 It exhibits relatively rapid dechlorination and defluorination of halogenated organic pollutants. 0 It also exhibits obvious catalytic activity characteristics in the catalytic oxidation system. 0 The iron sulfide (FeS x ) increases the number of electrons and the transfer rate, thereby accelerating its catalytic activity. However, the current synthesis of S-Fe 0 The two main methods are aqueous precipitation and mechanochemical ball milling (also known as solid-solid sulfidation), which consume a lot of energy and increase the preparation cost. Therefore, it is necessary to explore new preparation methods for zero-valent iron sulfide to solve the above technical problems.

[0004] Sludge produced by water treatment plants is a byproduct of drinking water treatment processes and is produced in large quantities. The average global production of sludge from water treatment plants exceeds 3.65×10 6 Tons / year, the annual dry sludge production in my country alone is as high as 1.5-2.4×10 6 Tons, the annual dry sludge production in the UK and Australia is 1.82×10 5 and 2.0×10 5 Tons, New Zealand's annual wet sludge production exceeds 2.98×10 4Tons. Iron sludge in water treatment plants is produced by using iron salts [FeCl3, FeSO4·7H2O, polyferric chloride (PFCl), etc.] as coagulants. It is a byproduct formed in the coagulation / flocculation-sedimentation stage. Its main components are suspended sediment, colloidal particles, natural organic matter, a small amount of algae and bacteria, metal hydroxides, coagulants (such as polyacrylamide) and other water treatment agents (such as powdered activated carbon). Iron sludge has the typical dual attributes of "pollution" and "resource". Conventional treatment and disposal is through landfill after dehydration, which may not only cause secondary pollution of the soil or water environment, but also is not conducive to the resource utilization of the effective ingredients in the iron sludge.

[0005] Therefore, the present invention introduces a method for preparing zero-valent iron sulfide from iron sludge in a water treatment plant, and applies it to the removal of organic pollutants in sewage and wastewater, thereby realizing multi-stage utilization of waste, saving raw materials and synthetic preparation costs, and developing resource-saving and environmentally friendly water purification materials, which is of great significance to the core concept of "using waste to treat wastewater". Summary of the invention

[0006] The purpose of the present invention is to solve the problems of raw material cost and energy consumption in the prior art zero-valent iron sulfide preparation process, and to provide a method for preparing zero-valent iron sulfide based on iron sludge in a water treatment plant in combination with the effective components and structural characteristics of iron-containing sludge in a water treatment plant, wherein the method has low production cost and short cycle. The present invention can not only provide a feasible solution for the resource recycling of waste iron sludge in a water treatment plant, but also effectively reduce the raw material cost and energy consumption in the preparation process of zero-valent iron sulfide, and at the same time provide an application method for removing typical organic pollutants in sewage and wastewater.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] One of the purposes of the present invention is to provide a method for preparing sulfided zero-valent iron based on iron sludge in a water treatment plant, comprising the following steps:

[0009] (1) Iron mud in water treatment plants is processed to obtain iron mud powder;

[0010] (2) adding the iron mud powder of step (1) into a sodium sulfide aqueous solution, adjusting the mixed solution to acidity, and thoroughly mixing and stirring to react to obtain sulfur-loaded iron mud;

[0011] The chemical reaction equation that may be involved in step (2) is:

[0012] 2Fe(OH)3+3H2S→2FeS+S 0 +6H2O

[0013] FeO(OH)+3H2S→2FeS+S 0 +4H2O

[0014] 2Fe(III)+S2- →2Fe(II)+S 0

[0015] FeS+S 0 →FeS2

[0016] (3) After the sulfur loading reaction, solid-liquid separation and drying are performed to obtain sulfurized modified dry iron mud;

[0017] (4) The sulfide-modified dry iron mud obtained in step (3) is transferred to a tubular furnace, and calcined and carbonized under anaerobic conditions to finally obtain the sulfide-modified nano zero-valent iron material.

[0018] The chemical reaction equation that may be involved in step (4) is:

[0019] Fe(OH)3+ high temperature carbonization →Fe2O3

[0020] 12Fe(OH)3+C→4Fe3O4+CO2+18H2O

[0021] Fe3O4+2C→3Fe 0 +2CO2

[0022] Furthermore, in step (1), the iron sludge of the water treatment plant is taken from an actual water treatment plant using FeCl3 as a coagulant, and a mud cake is produced after coagulation-precipitation-dehydration-filter pressing, and the iron content of the mud cake is about 20-25%; further, the treatment includes the steps of air drying, grinding, drying, screening and the like to process the mud cake into powder; further, air drying is to air dry the mud cake until the moisture content is not higher than 10%, and drying is to place the ground powder in a 100°C oven for drying for 12 hours; the screening process uses a 200-mesh screen such as a copper mesh, and the grinding uses a quartz mortar.

[0023] Furthermore, in step (2), the amount of iron mud powder added is 3 to 8 g / L based on the volume of the mixed solution; the amount of sodium sulfide added to the mixed solution is calculated as sulfur, and the molar ratio of sulfur to iron in the iron mud powder is 2 to 3:1, and more preferably the sulfur-iron ratio is 2:1 or 3:1; furthermore, the acidity of the mixed solution is H + Counted as H + :Fe molar ratio is 2:1; further, a strong acid solution is added to adjust the acidity of the mixed solution, and the strong acid is preferably hydrochloric acid, sulfuric acid, nitric acid, etc., and the concentration of the acidic solution is H + The concentration is preferably 1 mmol / L.

[0024] Furthermore, in step (2), the mixed solution is placed in a constant temperature stirrer and stirred for 2 hours at a temperature of 20 to 25° C. to complete the sulfur loading reaction; more preferably, the stirring rate is 40 r / min.

[0025] Furthermore, in step (3), for mixed solutions with sulfur-iron ratios of 1:1 and 1:2, vacuum filtration can be used to achieve solid-liquid separation, using a 0.45 μm polyvinylidene fluoride membrane (PVDF) to obtain a mud cake after filtration; for mixed solutions with sulfur-iron ratios of 2:1 and 3:1, ethanol should be appropriately added, and the volume ratio of ethanol to the mixed solution is preferably 1:1. The solution is allowed to stand for stratification, and then the supernatant is poured out to obtain a high-concentration iron mud.

[0026] Furthermore, in step (3), the drying step is to place the iron mud after solid-liquid separation in an oven at 60-80°C for 12 hours, preferably at 65°C, to finally obtain dry iron mud.

[0027] Furthermore, in step (3), after solid-liquid separation is completed, the precipitate is collected, dried, placed in a drying dish and sealed for storage.

[0028] Furthermore, in step (4), the sample is calcined under the protection of an inert atmosphere; more preferably, the sample is placed in an Al2O3 crucible, and an inert gas is introduced to exhaust oxygen in the tube furnace, and more preferably, the inert gas is at least one of nitrogen, argon, and helium. The gas flow rate during the calcination process is about 60 to 80 mL / min.

[0029] Furthermore, in step (4), calcination is carried out in a tubular furnace, and the tubular furnace program is set as follows: heating rate 8-10°C / min, calcination temperature 800°C, holding time 1.5-2h, followed by natural cooling.

[0030] The present invention provides a method for preparing sulfided zero-valent iron based on iron sludge in a water treatment plant. The polymerized hydroxyl iron [Fe(OH)3 or FeO(OH)] formed during the hydrolysis of iron salts has a large number of hydroxyl functional groups on the surface of the iron sludge, which can be physically adsorbed and chemically co-precipitated with soluble sulfides (such as H2S) in sewage and wastewater to generate FeS x and sulfur (S 0 ), for the preparation of S-Fe 0 Provide natural raw materials. The black powder finally obtained by the present invention is iron mud-based sulfide nano zero-valent iron (S-Fe 0 @C), the size is nano-scale zero-valent iron powder, the particle size is in the range of 200-800nm, and it can be used as an adsorbent or catalyst in catalyzing molecular oxygen and catalyzing persulfate to degrade and remove organic pollutants in sewage and wastewater.

[0031] Another object of the present invention is to provide an application of zero-valent iron sulfide based on iron sludge in a water treatment plant prepared by any of the above-mentioned preparation methods in the field of sewage and wastewater treatment.

[0032] Furthermore, the zero-valent iron sulfide is applied in the field of advanced oxidation removal of organic pollutants; further, the zero-valent iron sulfide is applied as an adsorbent or catalyst in catalyzing molecular oxygen and catalyzing persulfate to degrade and remove organic pollutants in sewage and wastewater.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (1) The composition of iron sludge in water treatment plants is relatively simple, with less toxic and harmful substances. By making full use of its effective components and structural characteristics, waste can be turned into treasure and waste resources can be used for sewage and wastewater treatment, achieving "waste treatment with waste", which has significant economic and environmental benefits.

[0035] (2) The iron mud from water treatment plants used in the present invention has a large output and a wide source, and the preparation method is simple and easy. After a simple sulfurization modification and a one-step calcination method, no complicated chemical reagents and process equipment are required, the cost is low, and it is conducive to large-scale promotion. Carbonization and calcination under anaerobic conditions do not produce CO2, which is conducive to the implementation of the dual carbon plan.

[0036] (3) S-Fe prepared by the present invention 0 @C is zero-valent iron sulfide with a diameter of 200 to 800 nm supported on graphite carbon. It is evenly distributed, has a clear and complete morphology, and has good magnetic characteristics, making it easy to recover.

[0037] (4) The sulfur doping in the sulfide zero-valent iron prepared by the present invention and the formation of graphite carbon during the calcination process promote the surface conductivity of the zero-valent iron, thereby enhancing the electron transfer rate, having a better removal effect on pollutants in water, and can activate molecular oxygen and persulfate in water to catalyze the oxidation and degradation of organic pollutants. It has good universality in the field of environmental pollutant treatment and has broad market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The XRD characterization diagrams of the iron mud-based ferrosulphur composite materials prepared in Example 1, Example 2 and Comparative Example 3 of the present invention;

[0039] Figure 2 VSM diagrams of samples obtained in Examples 1 and 2 of the present invention;

[0040] Figure 3 The SEM images of the samples obtained in Example 1 and Example 2 of the present invention;

[0041] Figure 4 TEM image of the sample obtained in Example 2 of the present invention;

[0042] Figure 5 The S-Fe prepared in Example 2 of the present invention 0 @C shows the effect of removing TC;

[0043] Figure 6 The S-Fe prepared in Example 2 of the present invention 0 @C shows the effect of TC removal under anaerobic conditions;

[0044] Figure 7 The S-Fe prepared in Example 2 of the present invention 0 @C Schematic diagram of the removal effect of activated PMS on TC. DETAILED DESCRIPTION

[0045] The technical solution of the present invention is further described clearly and completely below through specific embodiments and in combination with the accompanying drawings. It should be noted that the embodiments described in the present invention are implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operation processes are given, but they are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods, and the materials, reagents, etc. used in the examples are all available from commercial sources unless otherwise specified.

[0047] The principle of the present invention is that iron mud is a waste byproduct produced in the water purification process using iron salt as a coagulant, and is mainly composed of hydrolysis product polymerized hydroxyl iron [Fe(OH)3 or FeOOH], colloidal particles, natural organic carbon, etc. Since the surface of iron mud contains a large number of hydroxyl functional groups, it can be used as a natural adsorbent for soluble sulfides (such as H2S) in water, and FeS is generated through physical adsorption and chemical coprecipitation. x and S 0 , which can achieve natural sulfide modification. In addition, iron mud is calcined at high temperature under oxygen-free conditions, and Fe(III) and organic carbon can generate low-valent iron (Fe(II), Fe 0 ) and graphitized carbon, and achieve Fe 0 High proportion of exposure on the graphite carbon surface. The above chemical modification principle is used to prepare sulfide zero-valent iron based on iron sludge.

[0048] Iron mud sample sampling pretreatment analysis:

[0049] The iron sludge from the water treatment plant is dehydrated and filtered to obtain a mud cake with a moisture content of about 70%. After natural air drying, it is crushed and ground, and placed in a 100°C oven for drying for 12 hours. It is then further ground and sieved (200 mesh copper mesh) to obtain the original iron sludge sample, which is stored in a drying dish as the iron sludge in the embodiment.

[0050] Example 1

[0051] A sulfurization modification method based on iron mud in a water treatment plant comprises the following steps:

[0052] Weigh an appropriate amount of Na2S·9H2O solid and prepare a Na2S solution with a concentration of 36 mmol / L using deionized water and place it in a conical flask, weigh 1 g of iron mud and add it to the prepared solution, add an appropriate amount of hydrochloric acid (HCl) with a concentration of 1 mol / L to make the molar ratio of S:Fe:HCl be 2:1:2, and the total volume of the mixed solution be 200 mL, and mix evenly at 25°C with a mechanical stirring speed of 60 r / min for 2 h to fully react to obtain sulfur-loaded iron mud, recorded as S-Fe@C-0 (S:Fe=2:1).

[0053] Comparative Example 1

[0054] The sulfurization modification method in Example 1 was adopted to prepare samples with different sulfur loadings by adjusting the Na2S·9H2O dosage to 9, 18 and 54 mmol / L so that the sulfur-iron ratio was 1:2, 1:1 and 3:1 respectively. The other steps and parameters were the same as in Example 1.

[0055] Comparative Example 2

[0056] After the sulfurization modification of the iron mud is completed in Example 1 and Comparative Example 1, for the mixed solution with a sulfur-iron ratio of 1:1 and 1:2, vacuum filtration is directly used to achieve solid-liquid separation, and a 0.45μm polyvinylidene fluoride membrane (PVDF) is used to complete the filtration to obtain a mud cake. For the mixed solution with a sulfur-iron ratio of 2:1 and 3:1, ethanol with a volume ratio of about 1:1 should be appropriately added, and it should be allowed to stand and stratify, and then the supernatant is poured to obtain a high-concentration iron mud. The obtained iron mud samples are placed in an oven at 65°C for 12 hours to finally obtain sulfur-loaded dry iron mud.

[0057] Example 2

[0058] A carbonization modification method for preparing sulfidized zero-valent iron based on sulfur-doped iron sludge from a water treatment plant comprises the following steps:

[0059] Take 10g of the sulfide-modified iron mud samples with different sulfur-iron ratios in Comparative Example 2 after filtration and drying, place them in an Al2O3 crucible, first introduce nitrogen (N2) to exhaust the air in the tube furnace, then open the tube furnace for calcination, and set the tube furnace program as follows: heating rate 10℃ / min, calcination temperature 800℃, insulation time 2h, and then naturally cool down. The gas flow rate during calcination is about 80mL / min. The black powder obtained after calcination is stored in a sealed centrifuge tube and numbered S-Fe 0 @C-800(S:Fe=1:2)、S-Fe 0 @C-800(S:Fe=1:1)、S-Fe 0@C-800(S:Fe=2:1)、S-Fe 0 @C-800 (S:Fe=3:1), and at the same time, the original iron mud after pretreatment was directly subjected to carbonization modification at 800°C in Example 2 without sulfurization modification in Example 1, and the obtained sample was recorded as Fe 0 @C-800.

[0060] Comparative Example 3

[0061] Take the sulfide-modified iron mud sample obtained when the S:Fe ratio is 2:1 in Example 1, and adopt the carbonization modification method in Example 2. Only by adjusting the insulation setting of the tubular furnace to 400°C and 600°C, respectively, corresponding samples are obtained at different calcination temperatures, and are recorded as S-Fe@C-400 (S:Fe=2:1) ​​and S-Fe@C-600 (S:Fe=2:1). The other step parameters are the same as those in Example 2.

[0062] Test example:

[0063] The S-Fe@C-0 (S:Fe=2:1) ​​prepared in Example 1 and the S-Fe@C-400 (S:Fe=2:1), S-Fe@C-600 (S:Fe=2:1) ​​and S-Fe prepared in Example 2 and Comparative Example 3 were 0 @C-800 (S:Fe=2:1) The crystal structure, magnetic characteristics and micromorphology of the obtained material were characterized and analyzed by XRD, VSM, SEM and TEM. The results are as follows Figures 1 to 4 shown.

[0064] Figure 1 XRD characterization of the crystal structure of the material shows that after the sulfidation modification described in Example 1, the iron mud has a FeS crystal structure and retains the SiO2 component. When the calcination temperature is gradually increased from 400°C to 800°C, a reduction reaction occurs between Fe and organic carbon to gradually generate FeS2 and α-Fe 0 .

[0065] Figure 2 VSM characterizes the magnetic characteristics of the material. From the results, it can be seen that the sample of iron mud modified by sulfurization described in Example 1 has almost no magnetism, while the S-Fe generated by carbonization modification at 800℃ in Example 2 has 0 The @C (S:Fe = 2:1) sample exhibits good magnetic characteristics, with the highest saturation magnetization intensity reaching 25.65emu / g. Under the action of an external magnetic field, it can be easily separated from the aqueous phase, providing convenience for the subsequent recovery or disposal of solid powder.

[0066] Figure 3SEM characterization of the material microstructure, where a is the material characterization of S-Fe@C-0 (S:Fe=2:1) ​​in Example 1, and b is the material characterization of S-Fe 0 @C-800 (S:Fe=2:1) material characterization. The results show that the microscopic surface of the sample obtained after sulfurization modification presents a rough and irregular shape. 0 @C-800 (S:Fe=2:1) sample formed spherical structures with diameters ranging from 200 to 800 nm. Figure 4 (a) TEM characterization of the sample of Example 2 shows that S-Fe 0 The composite formed with the surrounding carbon materials, Figure 4 (b) Obvious graphitic carbon lattice fringes can be seen in high-resolution TEM.

[0067] The present invention also provides several applications of iron mud-based zero-valent iron sulfide, which are as follows:

[0068] Application Example 1: Iron mud-based sulfide zero-valent iron removes tetracycline (TC) from water by adsorbing and catalyzing molecular oxygen

[0069] Five groups of 100 mL of TC solution with an initial concentration of 10 mg / L were prepared in a conical flask and placed in a constant temperature water bath to control the reaction temperature at 25°C. The S-Fe 2 O ... 0 15 mg of each @C sample was added to the solution. The experiment was conducted in an open environment, with the shaker speed set at 80 r / min. 2 mL of the sample was taken with a syringe at the specified time point. After filtering through a 0.22 μm membrane, the residual TC concentration after the reaction was quantitatively detected by high performance liquid chromatography. The S-Fe ratios of different sulfur-iron ratios were compared. 0 @C-800 removes the influence of TC in water.

[0070] The results are as follows Figure 5 As shown, S-Fe 0 @C-800 (S:Fe=2:1) has the best TC removal effect, and the TC removal rate is more than 85% in 30 minutes. In addition, sulfur doping has a significant promoting effect on the removal of TC by zero-valent iron, indicating that sulfur doping by sulfurization modification of iron sludge can effectively improve the S-Fe 0 @C has a significant effect on the removal of TC. In addition, Fe may also exist in the system. 0 The corrosion produces physical adsorption of Fe(OH)3 adsorbent and oxidative degradation of free radicals produced by activating molecular oxygen in water.

[0071] The chemical reactions that may be involved in the catalytic molecular oxygen part are:

[0072] 4Fe 0 +3O2+6H2O→4Fe(OH)3

[0073] Fe 0 +O2+2H + →H2O2+Fe 2+

[0074] Fe(II)+H2O2→Fe(III)+ · OH+OH-

[0075] Fe(II)+O2→Fe(III)+ · O2 -

[0076] Fe(II)+ · O2 - +2H + →Fe(III)+H2O2

[0077] Application Example 2: Removal of Tetracycline (TC) from Water by Iron Mud-Based Sulfide Zero-Valent Iron under Nitrogen Stripping Conditions

[0078] Five groups of 100 mL of TC solution with an initial concentration of 10 mg / L were prepared in a conical flask, and the reaction temperature was controlled at 25°C in a constant temperature water bath. Nitrogen was continuously introduced into the conical flask solution to expel the dissolved oxygen in the water, so that the reaction was always carried out under anoxic conditions. The S-Fe 2600 calcined at 800°C with sulfur-iron ratios of 0, 1:2, 1:1, 2:1 and 3:1 obtained in Examples 1 to 2 and Comparative Examples 1 to 2 were taken. 0 15 mg of each @C sample was added to the solution. The experiment was conducted in an open environment, with the shaker speed set at 80 r / min. 2 mL of the sample was taken with a syringe at the specified time point. After filtering through a 0.22 μm membrane, the residual TC concentration after the reaction was quantitatively detected by high performance liquid chromatography. The effects of dissolved oxygen on the S-Fe ratio of different sulfur-iron ratios were compared. 0 @C-800 removes the influence of TC in water.

[0079] The results are as follows Figure 6 As shown in the figure, after nitrogen was introduced to expel dissolved oxygen, the S-Fe 0 The removal effect of @C-800 on TC decreased to varying degrees, especially for S-Fe 0 @C-800 (S:Fe=2:1), the removal rate of TC in 30min dropped from 85% to about 46%. This indicates that dissolved oxygen is S-Fe 0 @C-800 is an important factor in generating free radicals and other active species in the system.

[0080] Application Example 3: Iron mud-based sulfided zero-valent iron catalyzes persulfate to remove tetracycline (TC) from water

[0081] Prepare 5 groups of 100 mL of TC solution with an initial concentration of 10 mg / L in a conical flask and place it in a constant temperature water bath to control the reaction temperature at 25°C. Take the S-Fe@C-0 (S:Fe=2:1) ​​sample in Example 1 and the S-Fe obtained in Example 2. 0 @C-800(S:Fe=2:1) sample and Fe 0 15 mg of each @C-800 sample was added to the solution and stirred evenly; then potassium permonosulfate (PMS) was added at a concentration of 1 mmol / L. The experiment was conducted in an open environment, with the shaker speed set at 80 r / min. 2 mL of the sample was taken at the specified time point using a syringe. After filtering through a 0.22 μm membrane, the residual TC concentration after the reaction was quantitatively detected by high performance liquid chromatography. The uncalcined sulfur-modified sample S-Fe@C-0 (S:Fe=2:1) and the calcined sulfur-modified sample S-Fe 0 @C-800 (S:Fe=2:1) and unsulfur-loaded catalyst sample Fe 0 @The effectiveness of C-800 activated PMS in removing TC from water.

[0082] The results are as follows Figure 7 As shown in the figure, the catalytic activity of iron mud modified by sulfurization alone for PMS is poor, and the removal rate of TC is less than 50% at 30 min. When the iron mud is not loaded with sulfur, the Fe 0 @C-800, the removal rate of TC by catalytic PMS was only about 65% after 10 min of reaction. In comparison, S-Fe 0 @C-800 (S:Fe=2:1) activated PMS has a TC removal rate of up to 99% in the same time. The results show that sulfur-doped zero-valent iron has a significant promoting effect on the catalytic activity of PMS, and high-temperature carbonization modification is the main factor to generate Fe 0 It is a key step in enhancing catalytic performance.

[0083] The above-described embodiments are only preferred solutions of the present invention and are not intended to limit the present invention in any form. Other variations and modifications are possible without exceeding the technical solutions described in the claims.

Claims

1. A method for preparing sulfided zero-valent iron based on iron sludge in a water treatment plant, characterized in that: The following steps are involved: (1) Iron mud in water treatment plants is processed to obtain iron mud powder; (2) adding the iron mud powder of step (1) to the sodium sulfide aqueous solution, adjusting the mixed solution to acidity, and fully mixing and stirring to react to obtain sulfur-loaded iron mud; the amount of iron mud powder added is 3 to 8 g / L based on the volume of the mixed solution; the amount of sodium sulfide added to the mixed solution is calculated as sulfur, and the molar ratio of sulfur to iron in the iron mud powder is 2 to 3:1; (3) After the sulfur loading reaction, solid-liquid separation and drying are performed to obtain sulfurized modified dry iron mud; (4) The sulfide-modified dry iron mud obtained in step (3) is transferred to a tubular furnace, and calcined and carbonized under oxygen-free conditions to finally obtain a sulfide nano zero-valent iron material; the calcination temperature is 800°C.

2. The method for preparing sulfided zero-valent iron based on iron mud in a water treatment plant according to claim 1, characterized in that: In step (1), the iron sludge of the water treatment plant is taken from an actual water treatment plant using FeCl3 as a coagulant, and the mud cake produced after coagulation-precipitation-dehydration-filter pressing has an iron content of 20-25%.

3. The method for preparing sulfided zero-valent iron based on iron sludge in a water treatment plant according to claim 1, characterized in that: In step (1), the processing includes air drying, grinding, drying and screening.

4. The method for preparing sulfided zero-valent iron based on iron sludge in a water treatment plant according to claim 1, characterized in that: The acidity of the mixture is H + H + The molar ratio of iron is 2:

1.

5. The method for preparing sulfided zero-valent iron based on iron sludge in a water treatment plant according to claim 1, characterized in that: In step (2), the mixed solution is placed in a constant temperature mixer and stirred at a temperature of 20 to 25° C. for 2 h.

6. The method for preparing sulfided zero-valent iron based on iron sludge in a water treatment plant according to claim 1, characterized in that: In step (3), drying is performed by placing the iron mud after solid-liquid separation in an oven at 60-80°C for drying.

7. The method for preparing sulfided zero-valent iron based on iron sludge in a water treatment plant according to claim 1, characterized in that: In step (4), the sample is calcined under the protection of an inert gas, and the flow rate of the inert gas during the calcination process is 60 to 80 mL / min.

8. The method for preparing sulfided zero-valent iron based on iron sludge in a water treatment plant according to claim 1, characterized in that: In step (4), the calcination heating rate is 8-10°C / min, the heat preservation time is 1.5-2h, and then the temperature is naturally cooled.

9. Application of zero-valent iron sulfide based on iron sludge in a water treatment plant prepared by the preparation method according to any one of claims 1 to 8 in the field of sewage and wastewater treatment.

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