Method for removing iron-antimony through co-immobilization by applying Fenton fluidized bed

Abstract

The invention relates to the technical field of acid mine wastewater treatment, in particular to a method for removing iron-antimony through co-immobilization by applying a Fenton fluidized bed. The method comprises the following steps: adding a supporter material into a Fenton fluidized bed reactor, adjusting the pH value of wastewater to be treated to 2.5-3.8, pumping the wastewater into the reactor in a continuous flow manner, and starting a fluidized state, so that the expansion rate of the supporter material is 50-200%; the method comprises the following steps: adding a Fenton reagent to the wastewater to be treated, so that the molar ratio of ferrous ions to hydrogen peroxide in the wastewater to be treated is 1: (0.5-5), then carrying out iron ion crystallization reaction on the surface of a supporter, and removing antimony ions in an iron-antimony co-immobilization manner. According to the method, the Fenton reagent ratio of the wastewater to be treated is adjusted, and a supporter material is combined, so that iron-antimony ions in the wastewater to be treated under the acidic condition are removed together, and the problem that iron cations and antimony oxygen-containing anions cannot be synchronously removed in an existing alkalifying precipitation mode is solved.

Description

Technical Field

[0001] The invention relates to the technical field of acid mine wastewater treatment, and in particular to a method for removing iron-antimony by co-immobilization using a Fenton fluidized bed. Background Art

[0002] Acid mine drainage, also known as Acid Mine Drainage (AMD), is a type of wastewater characterized by high acidity, high heavy metal concentration and high sulfate ion concentration. It is usually formed when exposed tailings are dissolved and oxidized by rainwater or runoff during mining or after abandonment. Acid mine drainage, with its high acidity and rich iron ions and other heavy metal ions, is extremely destructive to the natural environment. In the mining of metal minerals and coal resources, the generation and discharge of acid mine drainage has become an environmental issue that cannot be ignored, posing a serious threat to the surrounding ecosystem and watershed health.

[0003] In actual acidic antimony mine wastewater, due to the presence of a large amount of pyrite as a associated mineral, the iron in the wastewater is mostly in the form of divalent iron, and the rate at which divalent iron is oxidized to trivalent iron by air under strongly acidic conditions is very low.

[0004] Conventional treatment methods for acid mine drainage, such as alkali precipitation, mainly use aeration combined with lime neutralization to treat wastewater in order to treat high concentrations of iron and antimony. However, although this method can precipitate and remove iron by providing alkalinity, the large amount of iron sludge generated will become a new hazardous waste, and it will also undergo a series of treatments such as dehydration and transportation, which greatly increases the actual treatment cost. In comparison, the Fenton fluidized bed system has the advantages of high reaction rate, reusability of the support, and low subsequent treatment cost. In addition, antimony ions, as an oxygen-containing anion, are difficult to remove by neutralization precipitation, which makes it difficult to reduce antimony ions in acid mine drainage.

[0005] The support in the Fenton fluidized bed has always been an important factor affecting the efficiency of iron crystallization, but the selection of support materials still faces certain limitations. For example, traditional silicate minerals, such as quartz sand and building sand, have average surface activity, and the iron crystallization efficiency is always at a low level, and the effect of long-term continuous operation is unstable; in addition, laboratory-scale modified materials are expensive and difficult to apply in actual engineering. Summary of the invention

[0006] In order to solve the problem that the existing alkali precipitation method cannot achieve the simultaneous and efficient removal of iron cations and antimony oxygen-containing anions, and the surface activity of the support material in the Fenton fluidized bed is general, the iron crystallization efficiency is always at a low level, and the long-term continuous operation effect is unstable, the purpose of the present invention is to provide a method for the joint immobilization and removal of iron and antimony using a Fenton fluidized bed.

[0007] Iron oxide is a kind of metal material widely existing in nature. Due to its structural similarity, it has a certain promoting effect on iron crystallization. At the same time, iron oxide also has a very high reactivity to antimony. If iron oxide is used as a carrier of Fenton fluidized bed, it will help the two simultaneous processes of iron crystallization and antimony removal.

[0008] On the one hand, the Fenton fluidized bed carries out iron crystallization under acidic conditions. The iron crystal layer formed by the crystallization can also effectively remove antimony as a new iron oxide. As the iron crystallization process continues, it can theoretically support the fixed removal of antimony on the surface of the crystal.

[0009] On the other hand, during the reaction of Fenton's reagent, some iron hydroxide flocs will inevitably be generated. These flocs can act as flocculants to remove part of the antimony in the aqueous solution.

[0010] Therefore, the Fenton fluidized bed has a clear removal mechanism for the two characteristic heavy metals in acid antimony mine wastewater, iron and antimony, so it is feasible to use the Fenton fluidized bed to treat acid antimony mine wastewater.

[0011] To achieve the above objectives, the technical solution of the present invention is as follows.

[0012] The invention provides a method for removing iron-antimony by co-immobilization using a Fenton fluidized bed, comprising the following steps: adding a support material into a Fenton fluidized bed reactor, then adding wastewater to be treated, adjusting the pH of the wastewater to be treated to 2.5-3.8, starting the fluidization state, and making the expansion rate of the support material 50%-200%; adding a Fenton agent into the Fenton fluidized bed reactor, so that the molar ratio of ferrous ions and hydrogen peroxide in the wastewater to be treated staying in the Fenton fluidized bed reactor is 1:0.5-5, then a crystallization reaction of iron ions on the surface of the support occurs, and antimony ions are removed in an iron-antimony co-immobilization manner; the support material is any one of quartz sand, garnet, forsterite, hematite, vanadium-titanium magnetite, magnetite, and goethite.

[0013] The present invention mainly expands the support material under acidic conditions, adjusts the Fenton reagent ratio of the wastewater to be treated, and combines with the support material to cause an iron ion crystallization reaction on the support surface, so that the antimony ions in the wastewater to be treated are removed in an iron-antimony co-immobilization manner, thereby solving the problem that the existing alkali precipitation method cannot achieve simultaneous and efficient removal of iron cations and antimony oxygen-containing anions, and the problem that the surface activity of the support material in the Fenton fluidized bed is general, the iron crystallization efficiency is always at a low level, and the long-term continuous operation effect is unstable.

[0014] Preferably, after adding the Fenton reagent, the concentration ratio of ferrous ions to trivalent antimony ions in the wastewater to be treated in the Fenton fluidized bed reactor is 1mM-2mM:3mg / L-20mg / L. Preferably, 1mM-2mM:5mg / L-20mg / L.

[0015] Preferably, after adding the Fenton reagent, the ferrous ions in the wastewater to be treated that stay in the Fenton fluidized bed reactor are nitrates, sulfates or chlorides of ferrous ions; after adding the Fenton reagent, the trivalent antimony ions in the wastewater to be treated that stay in the Fenton fluidized bed reactor are nitrates, sulfates or chlorides of trivalent antimony. In the present invention, the ferrous ions in the wastewater to be treated after adding the Fenton reagent are mainly derived from the ferrous ions contained in the wastewater to be treated; or the ferrous ions added in the form of the Fenton reagent; or a part of them are derived from the ferrous ions contained in the wastewater to be treated, and the other part is the ferrous ions added in the form of the Fenton reagent.

[0016] Preferably, the support material is goethite; the particle size of the support material is 16 mesh to 30 mesh.

[0017] Preferably, the amount of the support material added to each liter of wastewater to be treated retained in the Fenton fluidized bed reactor is 20 g / L to 40 g / L.

[0018] Preferably, the pH of the wastewater to be treated is adjusted to 2.8 to 3. Under the initial pH condition, the iron crystallization rate is 94.7% to 95.5%, and a relatively high antimony removal rate is maintained.

[0019] Preferably, the Fenton reagent is at least one of ferrous salt and hydrogen peroxide solution; the concentration of hydrogen peroxide solution is 28% to 30%. Preferably, the molar ratio of ferrous ions to hydrogen peroxide in the wastewater to be treated retained in the Fenton fluidized bed reactor is 1:1 to 3. Preferably, the hydraulic retention time of the wastewater to be treated in the Fenton fluidized bed reactor is 60 min to 120 min.

[0020] Preferably, before the support material is added to the Fenton fluidized bed reactor, the support material is also pretreated. The specific method is: soak the support material in a HCl solution with a pH of 3 to 4 for 10 hours to 12 hours, then soak it in water and ultrasonically treat it for 10 minutes to 30 minutes, then wash it with water to a pH of 7, and dry it to obtain the pretreated support material.

[0021] Beneficial effects of the present invention:

[0022] 1. The present invention mainly expands the support material under acidic conditions, adjusts the Fenton reagent ratio added to the wastewater to be treated, and combines the support material to achieve co-immobilization and removal of iron-antimony in the wastewater to be treated, thereby solving the problem that the existing alkali precipitation method cannot achieve simultaneous and efficient removal of iron cations and antimony oxygen-containing anions, and the surface activity of the support material in the Fenton fluidized bed is general, the iron crystallization efficiency is always at a low level, and the long-term continuous operation effect is unstable.

[0023] 2. The method of the present invention uses natural iron-containing minerals, such as goethite, as carrier materials, which has the advantage of low cost, and adopts Fenton fluidized bed co-crystallization to co-fix and remove antimony and iron, thereby achieving green waste treatment, alleviating the problem of high metal recovery costs in metal wastewater treatment, and has practical engineering application value for sustainable development, providing a new idea for the co-removal of iron and antimony in coexisting water bodies in the environmental field. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of a Fenton fluidized bed reactor provided in one embodiment of the present invention, wherein (a) is a schematic diagram of an internal circulation Fenton fluidized bed reactor; (b) is a schematic diagram of a continuous flow Fenton fluidized bed reactor.

[0025] Figure 2 Figure 1 is the test result diagram of iron crystallization rate and antimony removal rate under different types of carrier conditions. Among them, (a) is the test result diagram of iron crystallization rate; (b) is the test result diagram of antimony removal rate. In the figure, C / C 0 It is the ratio of the dissolved iron concentration corresponding to the running time to the initial dissolved iron concentration.

[0026] Figure 3 The test results of iron crystallization rate and antimony removal rate under different initial pH conditions are shown in Figure 1. (a) is the test result of iron crystallization rate; (b) is the test result of antimony removal rate.

[0027] Figure 4 Figure 2 is a graph showing the existence of Sb(III) and Sb(V) in solution under different pH conditions. (a) is a graph showing the existence of Sb(III) in solution under different pH conditions; (b) is a graph showing the existence of Sb(V) in solution under different pH conditions.

[0028] Figure 5 The test results of iron crystallization rate and antimony removal rate under different Fenton reagent ratios are shown in Figure 1. (a) is the test result of iron crystallization rate; (b) is the test result of antimony removal rate.

[0029] Figure 6The test results of iron crystallization rate and antimony removal rate under different iron-antimony concentration ratios when the ferrous iron concentration is 1 mM are shown in Figure 1. (a) is the test result of iron crystallization rate; (b) is the test result of antimony removal rate.

[0030] Figure 7 The figure shows the test results of iron crystallization rate and antimony removal rate under different iron-antimony concentration ratios when the ferrous iron concentration is 2 mM. Among them, (a) is the test result of iron crystallization rate; (b) is the test result of antimony removal rate.

[0031] Figure 8 The test results of iron crystallization rate and antimony removal rate under different coexisting anion conditions with a concentration of 1 mM are shown in Figure 1. (a) is the test result of iron crystallization rate; (b) is the test result of antimony removal rate.

[0032] Fig. 9 The test results of iron crystallization rate and antimony removal rate under different coexisting anion conditions with a concentration of 10 mM are shown in Figure 1. (a) is the test result of iron crystallization rate; (b) is the test result of antimony removal rate.

[0033] Fig.10 The test results of iron crystallization rate and antimony removal rate under six batches of treatment are shown in Figure 1. The black line is the iron crystallization rate curve; the red line is the antimony removal rate curve.

[0034] Fig.11 Laser particle size analysis diagram of goethite before treatment and six batches of goethite after treatment.

[0035] Fig.12 3D microscope images of goethite before treatment and six batches of goethite after treatment. (a) is a 3D microscope image of goethite before treatment; (b) is a 3D microscope image of goethite after six batches of treatment.

[0036] Fig.13 The SEM images of goethite support before and after batch processing. (a) is the SEM image of goethite before processing; (b) is a partial enlarged image of (a); (c) is the SEM image of goethite after six batches of processing; (d) is a partial enlarged image of (c).

[0037] Fig.14 The mapping map, Fe site map and Sb site map of goethite after six batches of treatment. Among them, (a) is the mapping map; (b) is the Fe site map; (c) is the Sb site map.

[0038] Fig.15The O1s orbital spectrum and Sb 3d orbital spectrum of goethite, goethite after iron crystallization, and goethite after iron and antimony are removed. Among them, (a) is the O1s orbital spectrum and Sb 3d orbital spectrum of goethite; (b) is the O1s orbital spectrum and Sb 3d orbital spectrum of goethite after iron crystallization; (c) is the O1s orbital spectrum and Sb 3d orbital spectrum of goethite after iron and antimony are removed.

[0039] Fig.16 FTIR images of goethite before treatment and six batches of goethite after treatment.

[0040] Fig.17 These are the Raman spectra of goethite before treatment and six batches of goethite after treatment.

[0041] Fig.18 The proposed mechanism for the simultaneous removal of Fe(II) and Sb(III) in the goethite-Fenton fluidized bed system is presented.

[0042] Fig.19 This is a diagram showing the long-term operation of a continuous flow Fenton fluidized bed for treating acidic antimony mine wastewater. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0044] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making any creative work shall fall within the scope of protection of the present invention.

[0045] In the following embodiments of the present invention, the Fenton reagent is ferrous ion and hydrogen peroxide; the Fenton reagent ratio is the molar ratio of ferrous ion and hydrogen peroxide. The hydraulic retention time is the average residence time of the wastewater to be treated in the Fenton fluidized bed reactor.

[0046] Acid mine drainage is the main type of wastewater generated in the mining process, which includes acidic mine water, mining wastewater, mineral processing wastewater, etc. The volume of acid mine drainage generated by mineral mining every year is very large. The indiscriminate discharge and untimely treatment of acid mine drainage will cause serious damage to the ecological environment near the mines.

[0047] Antimony is a toxic element with cumulative and genotoxic properties, which can be converted into organic substances such as dimethylantimony DMSb and trimethylantimony TMSb. Antimony has strong ecotoxicological effects and poses a serious threat to human health. Among them, inorganic antimony compounds have been found to have stronger toxic effects than organic forms, and soluble inorganic antimony can easily bind to internal thiol groups in the human body. In the aquatic environment, Sb(III) and Sb(V) in inorganic form constitute the two main valence states, and the existence of the valence state depends largely on the pH value, Eh value and ionic conditions at the time.

[0048] According to research, iron oxides have a certain promoting effect on iron crystallization due to their structural similarity, and also have a good removal effect on antimony. The divalent iron ions in the Fenton reagent required for the Fenton fluidized bed are the target heavy metal ions waiting to be removed in most acidic mine wastewaters. Therefore, the use of the Fenton fluidized bed to simultaneously remove iron and antimony from acidic antimony mine wastewater has good application potential. However, in the traditional Fenton reaction, a large amount of iron sludge with high water content is often produced. Although iron sludge, as a collection of iron flocs, has a certain removal effect on antimony, the use of iron oxides to adsorb Sb(III) is accompanied by a redox reaction, so that the more toxic Sb(III) is oxidized to the less toxic Sb(V), but the presence of Sb(V) still increases the risk of secondary pollution caused by iron sludge.

[0049] Based on this, the present invention utilizes a support material-Fenton fluidized bed system to simultaneously remove iron ions and trivalent antimony ions from an aqueous solution. The support material is a carrier in a Fenton fluidized bed reactor. The present invention preferably uses goethite as a support material, mainly because the iron oxyhydroxide in goethite has a strong affinity for trivalent antimony ions, and the iron crystal layer generated on the surface of goethite can still effectively remove trivalent antimony ions. In addition, the tiny flocs formed in the Fenton reaction can also combine with the trivalent antimony ions, and some of the tiny flocs can also be deposited on the support material, thereby facilitating separation from the aqueous solution.

[0050] The Fenton fluidized bed reactor of the present invention is selected from an internal circulation Fenton fluidized bed reactor or a continuous flow Fenton fluidized bed reactor. Figure 1 The internal circulation Fenton fluidized bed reactor comprises a reactor body, wherein the reactor body comprises a main reaction zone 101 and an expansion zone 102, wherein the expansion zone 102 is located at the upper end of the main reaction zone 101, and the expansion zone 102 is integrally connected to the main reaction zone 101. Figure 1, the inner diameter of the main reaction zone 101 is 30mm, and the total height of the main reaction zone 101 is 350mm; the inner diameter of the expansion zone 102 is 50mm, and the total volume of the expansion zone 102 is about 310mL. The function of the expansion zone 102 is to intercept a part of the carrier with a smaller particle size to prevent the carrier from entering the magnetic circulation pump. The magnetic circulation pump is an MP-6RZ magnetic circulation pump. A water inlet 103 is provided at the bottom of the main reaction zone 101, and a reflux port 104 is provided on one side wall of the expansion zone 102; the outlet of the magnetic circulation pump 105 is connected to the water inlet 103 of the main reaction zone 101, and the inlet of the magnetic circulation pump 105 is connected to the reflux port 104 of the expansion zone 102. The reflux port 104 and the water inlet 103 are connected to the MP-6RZ magnetic circulation pump through two sections of silicone hoses, and the fluidization effect of the carrier particles is obtained through the head of the magnetic circulation pump 105. A laser perforated plate with a hole diameter of 1 mm is provided near the water inlet 103 in the main reaction zone 101 as a water distribution plate 106. The water distribution plate 106 has a large number of holes, which can reduce the resistance of water flow, and the small hole diameter can prevent a large amount of leakage of the support. The upper side of the water distribution plate 106 is filled with a multi-layer glass bead layer 107, and the upper side of the glass bead layer 107 is filled with a multi-layer support layer 108; the multi-layer glass bead layer 107 mainly plays the role of uniform water distribution and supporting the fluidized support.

[0051] In working conditions, use Figure 2 The continuous flow Fenton fluidized bed reactor shown in the figure can realize continuous flow and stable operation. The continuous flow Fenton fluidized bed reactor includes a main reactor, and the main reactor includes a main reaction section 201 and an expansion section 202. The expansion section 202 is located at the upper end of the main reaction section 201, and the expansion section 202 is integrally connected to the main reaction section 201. Figure 2, the inner diameter of the main reaction section 201 is 50mm, and the total height of the main reaction section 201 is 1400mm; the inner diameter of the expanded reaction section 202 is 80mm, and the total volume of the expanded reaction section 202 is about 2500mL. The function of the expanded reaction section 202 is to intercept a part of the support with a smaller particle size to prevent the support from entering the circulation pump 206. The circulation pump 206 is an MP-15R magnetic circulation pump. The bottom of the main reaction section 201 is provided with a water inlet interface 203, and the side wall of the expanded reaction section 202 is provided with a reflux interface 204 and a water outlet interface 205; the water outlet interface 205 is blocked in the case of backwater, and is opened to take water when it is necessary to measure, that is, the water outlet sampling interface within a certain period of time after the cocrystallization treatment is completed. The outlet of the circulation pump 206 is connected to the water inlet interface 203 of the main reaction section 201, and the inlet of the circulation pump 206 is connected to the reflux interface 204 of the expanded reaction section 202. The reflux interface 204 and the water inlet interface 203 are connected by two sections of silicone hose and MP-15R magnetic circulation pump to obtain the rising flow rate of the support. A dosing port 207 is provided on the side wall of the main reaction section 201 near the expanded reaction section 202. The dosing port 207 is connected to the water inlet pump 208 and the dosing pump 209 respectively. The water inlet pump 208 is used to pump in raw water, and the dosing pump 209 is used to pump in hydrogen peroxide. The outlet of the water inlet pump 208 is connected to the dosing port 207, the first inlet of the water inlet pump 208 is connected to the reflux interface 204 on the side of the middle and upper section of the main reactor, and the second inlet of the water inlet pump 208 is connected to the raw water tank, so that the raw water is mixed with the reflux water and pumped into the main reactor. The outlet of the dosing pump 209 is connected to the dosing port 207, the first inlet of the dosing pump 209 is connected to the water inlet interface 203 at the bottom of the main reactor, and the second inlet of the dosing pump 209 is connected to the dosing tank. The side wall of the main reaction section 201 is also provided with a plurality of inspection ports 210 and a plurality of sampling ports 211 from top to bottom; the bottom of the main reaction section 201 has a supporting area 212 and a filling area 213; the supporting area 212 is located at the lower side of the filling area 213; the supporting area 212 is close to the water inlet interface 203. The filler in the supporting area 212 is glass beads or stones to form multiple glass bead layers or multiple stone layers; the filler in the filling area 213 is a support to form multiple support layers. The side wall of the main reaction section 201 near the filling area is also provided with an inspection port 210.

[0052] The technical solution of the present invention is further described below by means of specific examples. In the following examples, the methods described are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.

[0053] In the following embodiments, Fe(II) represents ferrous ion; Sb(III) represents trivalent antimony ion. The raw material corresponding to Fe(II) is ferrous sulfate, with the chemical formula of FeSO 4; The raw material corresponding to Sb(III) is trivalent antimony sulfate, with the chemical formula Sb 2 (SO 4 ) 3 . The Fenton reagent ratio is Fe 2+ and H 2 O 2 The molar ratio of 1mM is 1mmol / L; 1M is 1mol / L. 30wt% hydrogen peroxide is about 9.8mol / L.

[0054] Example 1

[0055] A method for removing iron-antimony by co-immobilization using a Fenton fluidized bed, wherein different carrier materials are selected to co-immobilize and remove iron-antimony using a Fenton fluidized bed reactor. The different carrier materials selected include silicate mineral carrier materials and iron ore carrier materials. The silicate mineral carrier materials are quartz sand, garnet, tourmaline and forsterite; the iron ore carrier materials are hematite, vanadium-titanium magnetite, magnetite, hematite and goethite. The specific method is as follows:

[0056] Step 1, pretreatment of the support material: soak different support materials in a pH=3 HCl solution for 12 hours, then soak them in deionized water and use an ultrasonic cleaner for 30 minutes, and finally wash them with deionized water until the pH of the rinse water is 7 and the rinse water has no obvious color. The support material obtained after rinsing is dried in an electric hot air drying oven at a temperature of 60° to obtain a pretreated support.

[0057] Step 2, preparing simulated wastewater: dissolving ferrous sulfate and trivalent antimony sulfate in water, so that the concentration of ferrous ions in the simulated wastewater is 1 mM, and the concentration of trivalent antimony ions is 10 mg / L.

[0058] Step 3: Place a water distribution plate and glass beads at the bottom of the internal circulation Fenton fluidized bed reactor, and then add the support material from the top of the internal circulation Fenton fluidized bed reactor. The amount of support material added is 40 g / L based on the volume of the added simulated wastewater. Fill the internal circulation Fenton fluidized bed reactor with simulated wastewater and use 0.1 M H 2 SO 4The pH of the simulated wastewater was adjusted to 3 with a solution and / or a 0.1M NaOH solution, the magnetic circulation pump was turned on, the fluidization state was turned on, and the head was adjusted so that the expansion rate of the support was 100%. A 3mM hydrogen peroxide solution was prepared with 30wt% hydrogen peroxide, and a 3mM hydrogen peroxide solution was added from the top of the internal circulation Fenton fluidized bed reactor to adjust the Fenton reagent ratio to 1:3 and start the reaction. During the reaction, samples were taken at different time points: 5min, 15min, 30min, 45min, and 60min, and the samples were pretreated and tested in two ways.

[0059] The first pretreatment method for the sample is: the sample is directly filtered using a 0.22 μm filter membrane, and the residual iron ion concentration is determined using ICP. The removal efficiency obtained is recorded as TR%.

[0060] The second pretreatment method for the sample is: the sample is directly added to the centrifuge tube without filtration, and nitric acid with pH = 1 is added for acidification, and then filtered using a 0.22 μm filter membrane, and the residual iron ion concentration is measured using ICP. The removal efficiency obtained is recorded as CR%.

[0061] Two parallel groups were made for the post-batch experiment, and the data were averaged. The removal efficiency of Fe and Sb in the test solution sampled at different operation times using different types of supports was calculated respectively. The experimental groups under different types of supports were recorded as quartz sand group, garnet group, tourmaline group, forsterite group, hematite group, vanadium titanomagnetite group, magnetite group, hematite group and goethite group.

[0062] like Figure 2 Figure (a) shows the iron removal rate of different supports in the Fenton fluidized bed. The figure shows that the concentration of dissolved iron in hematite and tourmaline increased in the presence of antimony. Among them, the hematite group showed significant iron dissolution at 5 minutes. The tourmaline group gradually dissolved iron, and the dissolved iron concentration was 1.2mM at 60 minutes, which was 1.2 times the initial dissolved iron concentration.

[0063] The goethite support showed excellent iron crystallization effect, reaching 95% in 60 minutes. The above results show that when antimony is present in the influent, the iron crystallization rate of different types of supports is affected differently. The influence of the surface properties of the support on the reaction process needs further exploration.

[0064] like Figure 2Figure (b) shows the antimony removal rates of different supports in the Fenton fluidized bed. It can be seen from the figure that all supports have a certain removal effect on antimony. The worst magnetite and hematite achieved an antimony removal rate of 62% at 60 minutes. Goethite performed best, reaching an antimony removal rate of 98.3% at 60 minutes, indicating that the efficient iron crystallization process of the goethite support can enhance the adsorption and removal of antimony. Therefore, goethite was used as the preferred support in subsequent experiments to investigate the influence of key parameters of the Fenton fluidized bed and the iron-antimony co-removal mechanism.

[0065] Example 2

[0066] A method for removing iron-antimony by co-immobilization using a Fenton fluidized bed, selecting a goethite support, and removing Fe(II) and Sb(III) from an aqueous solution in a goethite-Fenton fluidized bed system by controlling the initial pH. The specific method is as follows:

[0067] Step 1, pretreatment of the support material: select goethite as the support material, soak it in a pH=3 HCl solution for 12 hours, then soak it in deionized water and use an ultrasonic cleaner for 30 minutes, and finally wash it with deionized water until the pH of the rinse water is 7 and the rinse water has no obvious color. The support material obtained after rinsing is dried in an electric hot air drying oven at a temperature of 60° to obtain a pretreated goethite support.

[0068] Step 2, preparing simulated wastewater: dissolving ferrous sulfate and trivalent antimony sulfate in water, so that the concentration of ferrous ions in the simulated wastewater is 1 mM, and the concentration of trivalent antimony ions is 10 mg / L.

[0069] Step 3: The water distribution plate and glass beads are arranged at the bottom of the internal circulation Fenton fluidized bed reactor, and then goethite is added as a support material from the top of the internal circulation Fenton fluidized bed reactor. The amount of goethite added is 40 g / L based on the volume of the simulated wastewater. The simulated wastewater is filled into the internal circulation Fenton fluidized bed reactor, and 0.1 M H 2 SO 4 The pH of the simulated wastewater was adjusted to 2.5, 2.6, 2.8, 3.0, 3.2, 3.4, 36, and 3.8 with 0.1 M NaOH solution and / or 0.1 M NaOH solution. The magnetic circulation pump was turned on, the fluidization state was turned on, and the head was adjusted to make the support expansion rate 100%. A 3 mM hydrogen peroxide solution was added from the top of the internal circulation Fenton fluidized bed reactor to adjust the Fenton reagent ratio to 1:3 and start the reaction. The hydraulic retention time was 60 min.

[0070] During the reaction, samples were taken at regular intervals, and the samples were pretreated and tested according to the method of Example 1.

[0071] like Figure 3Figure (a) shows the change in the iron crystallization rate of the system in the initial pH range of 2.5 to 3.8. The figure shows that when pH = 2.8 or pH = 3.0, the iron crystallization rate reaches 95.5% and 94.7% respectively. In the pH experimental group after pH>3.0, the iron crystallization rate will gradually decrease with the increase of pH. In the experimental group with pH = 3.8, the iron crystallization rate at 60 minutes dropped to 74%. The main reason is that the increase in pH will cause the nucleation direction to move towards homogeneous nucleation, and it is easier to generate Fe(OH) in the solution at this time. 3 Flocs, thereby reducing the crystallization rate of iron.

[0072] like Figure 3 Figure (b) shows the change in the antimony removal rate of the system when the initial pH is in the range of 2.5 to 3.8. There are two key points in the figure that deserve attention. First, the antimony removal rate generally decreases with the increase of pH. For example, the antimony removal rates at pH = 2.5 and pH = 3.8 are 97.7% and 77.3%, respectively. Studies have shown that the adsorption effect of Sb (III) is less affected by pH and has good adsorbability in a wide range, specifically pH = 3 to 12; while Sb (V) can be rapidly adsorbed by iron oxides or iron hydroxides under acidic conditions, and the adsorption effect weakens when the pH increases. This phenomenon may be due to the fact that pH affects the charge state of the support particles and the distribution of heavy metal ion forms in the solution. However, in the embodiment of the present invention, the antimony removal rate is greatly affected by pH, which may indicate that Sb (III) in the Fenton fluidized bed may have been oxidized to Sb (V). Secondly, the adsorption effect of Sb(V) decreases with the increase of pH under acidic conditions, but in the embodiment of the present invention, the pH at which the antimony removal rate is the highest is 2.8, and the antimony removal rate at this time is close to 100%. pH = 2.8 is also the experimental parameter for the optimal efficiency of the iron crystallization process, so the phenomenon of the highest antimony removal rate may be related to the iron crystallization process.

[0073] Figure 4 The main existing forms of Sb(III) and Sb(V) in solution in the pH range of 1 to 7 are shown. Figure 4 It can be seen that the main form of Sb(III) in the solution is Sb(OH) 3 and Sb(OH) 2 + , and with the increase of pH, Sb(OH) 3 The proportion of Sb(OH) 2 + At the same time, as the pH of the solution increases, the positive potential on the surface of the material decreases, but the surface of the material is still positively charged, so Sb(OH) 2+ The reduction of ion ratio can enhance the adsorption effect of Sb(III) within a certain pH range. When the pH of the solution is near neutral or weakly alkaline, the surface of the material tends to be negatively charged, and the existence form of Sb(III) in the solution is almost entirely in the form of molecular Sb(OH) 3 At this time, the effect of pH on Sb(III) is relatively small.

[0074] Sb(V) exists in two main forms in aqueous solution, namely Sb(OH) 6 - and Sb(OH) 5 The reason why the adsorption effect of Sb(V) decreases with the increase of pH is that when pH>3, the main form of Sb(V) in the solution is negatively charged Sb(OH) 6 - Under acidic conditions, the positively charged material on the surface reacts with the negatively charged Sb(OH) 6 - The electrostatic attraction between them is conducive to the removal of Sb(V). As the pH increases, the positive potential on the surface of the material decreases or even turns negative, while Sb(OH) 6 - The proportion of the form of increases with the increase of pH, which leads to the weakening of electrostatic adsorption and even turns into repulsion. - The increase in also leads to its competition with Sb(V) for adsorption sites, thus affecting the adsorption effect of Sb(V).

[0075] Therefore, at pH = 2.8, the Fenton fluidized bed achieved the most efficient removal of iron and antimony, indicating that efficient iron crystallization is beneficial to increasing the surface oxyhydroxy iron content and specific surface area of ​​the goethite support, providing more adsorption and complexation sites for antimony, and there is a certain synergistic relationship between the two.

[0076] Example 3

[0077] A method for removing iron-antimony by co-immobilization using a Fenton fluidized bed, selecting a goethite support, and removing Fe(II) and Sb(III) from an aqueous solution in a goethite-Fenton fluidized bed system by controlling the Fenton reagent ratio. The specific method is as follows:

[0078] Step 1, pretreatment of the support material: select goethite as the support material, and pretreat the goethite support material according to the method of Example 2 to obtain a pretreated goethite support.

[0079] Step 2, preparing simulated wastewater: dissolving ferrous sulfate and trivalent antimony sulfate in water, so that the concentration of ferrous ions in the simulated wastewater is 1 mM, and the concentration of trivalent antimony ions is 10 mg / L.

[0080] Step 3: Place a water distribution plate and glass beads at the bottom of the internal circulation Fenton fluidized bed reactor, and then add goethite as a support material from the top of the internal circulation Fenton fluidized bed reactor. The amount of goethite added is 40 g / L based on the volume of the simulated wastewater. Fill the internal circulation Fenton fluidized bed reactor with simulated wastewater and use 0.1 M H 2 SO 4 The pH of the simulated wastewater was adjusted to 3 with 0.1M NaOH solution and / or 0.1M NaOH solution, the magnetic circulation pump was turned on, the fluidization state was turned on, and the head was adjusted to make the support expansion rate 100%. According to the Fenton reagent ratio of 1:0.5, 1:1, 1:2, 1:3, 1:5, 3mM hydrogen peroxide solution was added from the top of the internal circulation Fenton fluidized bed reactor to adjust the Fenton reagent ratio to 1:0.5, 1:1, 1:2, 1:3, 1:5, and start the reaction. The hydraulic retention time was 60min.

[0081] During the reaction, samples were taken at regular intervals, and the samples were pretreated and tested according to the method of Example 2. Figure 5 When the Fenton reagent ratio is 1:3, the system can achieve the best removal efficiency, at which the iron crystallization rate and antimony removal rate are 94.7% and 93.3% respectively. The Fenton reagent ratio will directly affect the oxidation process of iron. The better the iron crystallization rate of the experimental group, the better the antimony removal efficiency, indicating that the iron crystal layer plays a certain role in promoting the antimony removal process.

[0082] Example 4

[0083] A method for removing iron-antimony by co-immobilization using a Fenton fluidized bed, selecting a goethite support, and removing Fe(II) and Sb(III) from an aqueous solution in a goethite-Fenton fluidized bed system by controlling the iron-antimony concentration ratio. The specific method is as follows:

[0084] Step 1, pretreatment of the support material: select goethite as the support material, and pretreat the goethite support material according to the method of Example 2 to obtain a pretreated goethite support.

[0085] Step 2, preparing simulated wastewater: dissolving ferrous sulfate and trivalent antimony sulfate in water so that the concentration of ferrous ions in the simulated wastewater is 1 mM and 2 mM, and the concentration of trivalent antimony ions is 3 mg / L, 5 mg / L, 10 mg / L, and 20 mg / L, respectively, to obtain simulated wastewater with different iron-antimony concentration ratios.

[0086] Step 3: Place a water distribution plate and glass beads at the bottom of the internal circulation Fenton fluidized bed reactor, and then add goethite support from the top of the internal circulation Fenton fluidized bed reactor. The amount of goethite support added is 40 g / L based on the volume of the background liquid. Fill the reactor with the prepared background liquid with different iron-antimony concentration ratios, and use 0.1 M H 2 SO 4 Solution and / or 0.1M NaOH solution to adjust the wastewater pH to 3, turn on the magnetic circulation pump, start the fluidization state, adjust the head so that the support expansion rate is 100%. 3mM hydrogen peroxide solution is added from the top of the internal circulation Fenton fluidized bed reactor to adjust the Fenton reagent ratio to 1:3, start the reaction, and the hydraulic retention time is 60min.

[0087] During the reaction, samples were taken at regular intervals, and the samples were pretreated and tested according to the method of Example 2.

[0088] Depend on Figure 6 and Figure 7 It can be seen that when the influent iron concentration is 1mM, the concentration ratio of Fe(II) and Sb(III) has no obvious effect on the iron crystallization rate and antimony removal rate. Increasing the initial antimony concentration can lead to a slight increase in the antimony removal rate. When the iron concentration is increased to 2mM, the antimony removal rate shows a certain downward trend as the initial antimony concentration decreases. On the one hand, the increase in the influent iron concentration accelerates the reaction rate of the iron crystallization reaction, and there is a certain competition between the antimony on the surface of the support and the iron crystallization process. On the other hand, the increase in the influent iron concentration promotes the formation of a crystal layer on the surface of the support, and the crystal layer will gradually cover the surface of the support. The surface sites of the newly formed crystal layer may be more conducive to the fluidized crystallization of iron.

[0089] Example 5

[0090] A method for removing iron-antimony by co-immobilization using a Fenton fluidized bed, selecting a goethite support, and removing Fe(II) and Sb(III) from an aqueous solution in a goethite-Fenton fluidized bed system by controlling the types and concentrations of different coexisting anions. The specific method is as follows:

[0091] Step 1, pretreatment of the support material: select goethite as the support material, and pretreat the goethite support material according to the method of Example 2 to obtain a pretreated goethite support.

[0092] Step 2, prepare simulated wastewater: dissolve ferrous sulfate and trivalent antimony sulfate in water so that the concentration of ferrous ions in the simulated wastewater is 1mM and the concentration of trivalent antimony ions is 3mg / L; at the same time, adjust the coexisting anion PO 4 3- 、NO 3- 、SO 4 2- , Cl- The concentration of the coexisting anion PO 4 3- 、NO 3- 、SO 4 2- , Cl - The concentration of each was 10 mM, and simulated wastewater with different types and concentrations of coexisting anions was prepared.

[0093] Step 3: Place a water distribution plate and glass beads at the bottom of the internal circulation Fenton fluidized bed reactor, and then add goethite support from the top of the internal circulation Fenton fluidized bed reactor. The amount of goethite added is 40 g / L based on the volume of the simulated wastewater. Fill the reactor with simulated wastewater and use 0.1 M H 2 SO 4 Solution and / or 0.1MNaOH solution to adjust the pH of the simulated wastewater to 3, turn on the magnetic circulation pump, start the fluidization state, and adjust the head so that the support expansion rate is 100%. Add 3mM hydrogen peroxide solution from the top of the internal circulation Fenton fluidized bed reactor to adjust the Fenton reagent ratio to 1:3, start the reaction, and the hydraulic retention time is 60min.

[0094] During the reaction, samples were taken at regular intervals, and the samples were pretreated and tested according to the method of Example 2.

[0095] Common inorganic anions in acid mine drainage were added to simulated wastewater to investigate their effects on the co-removal of iron and antimony in a Fenton fluidized bed. Figure 8 and Fig. 9 In general, the influence of inorganic anions on iron crystallization is as follows: PO 4 3- >NO 3- >SO 4 2- >Cl - ; The degree of influence on antimony removal is: PO 4 3- >SO 4 2- >NO 3 - ≈Cl - ; 1mM low concentration Cl - The iron crystallization rate can be slightly promoted, while the high concentration of 10mM Cl - It does not affect the crystallization-dissolution equilibrium of iron, and has little effect on its crystallization rate and antimony removal rate. 3- 、SO 4 2-At low concentrations, it has almost no effect on the iron crystallization rate. At a high concentration of 10mM, it has a certain inhibitory effect on the iron crystallization rate, reducing the iron crystallization rate from 83.6% to 60%, but the two anions have little effect on the removal rate of antimony. 4 3- Compared with other common inorganic anions, it has a more obvious inhibitory effect on fluidized iron crystallization and antimony removal, and this inhibitory effect increases with the increase of PO 4 3- The effect of 10mM PO 4 3- The concentration can reduce the iron crystallization rate from 83.6% to 38.8%, which can be attributed to PO 4 3- with Fe 3+ The complexing ability of PO4 is strong, and it competitively generates iron phosphate flocs, which are difficult to bond or deposit on the surface of the support. 4 3- The adsorption of antimony is more affected when PO 4 3- When the concentration is 10 mM, the antimony removal rate drops rapidly to below 10%. This is because Cl - 、NO 3- 、SO 4 2- Both of them are mainly complexed by forming outer sphere complexes with the support, while PO 4 3- A stable inner-sphere complex will be formed, occupying the adsorption sites of antimony, thus strongly inhibiting the removal efficiency of antimony.

[0096] Example 6

[0097] A method for removing iron and antimony by co-immobilization using a Fenton fluidized bed, a goethite support was selected, and multiple batches of water inflow experiments were conducted on the goethite-Fenton fluidized bed. The method of Example 2 was followed, and the specific experimental conditions were: the amount of the goethite support was 40 g / L, pH = 3.0, hydrogen peroxide was 3 mM, the amount of ferrous iron added was 1 mM, the amount of trivalent antimony added was 10 mg / L, the support expansion rate was 100%, the support particle size was 16 mesh to 30 mesh, the number of drug additions was 1, and one batch experiment lasted 1 hour.

[0098] like Fig.10 , the antimony removal rate has been very stable for six consecutive batches, always maintained at about 95%. However, the iron crystallization rate showed a gradual downward trend with the continuous increase of antimony loading, from 94.6% in the first batch to 62.4% in the sixth batch, suggesting that it is difficult for iron ions to undergo heterogeneous nucleation and crystallization at the antimony loading sites on the surface of the support crystal layer, and there should be a certain competitive relationship between iron and antimony in the removal process of the support surface sites.

[0099] X-ray fluorescence spectroscopy was performed to analyze the simultaneous removal mechanism of Fe(II) and Sb(III) in the goethite-Fenton fluidized bed system. X-ray fluorescence spectroscopy, the full name of which is X-Ray Fluorescence Spectroscopy, abbreviated as XRF. XRF analysis was performed on the goethite support material after the iron / antimony removal batch treatment, and the results are shown in Table 1.

[0100] Table 1 XRF elemental analysis results of goethite batches before and after treatment

[0101]

[0102]

[0103] From the results in Table 1, it can be seen that after batch processing, the percentage of Fe and Sb elements in the goethite support increased significantly. The mass percentage of Fe element increased from 20.6% to 22.2%, while the mass percentage of Sb element increased from undetectable to 0.2%. This result confirms the simultaneous occurrence of iron crystallization and antimony adsorption processes.

[0104] Laser particle size analysis of the support material before and after the reaction, the results are shown in Fig.11 . After six batches of treatment, the particle size distribution curve of the support particles as a whole shifted to the right, that is, the support particles as a whole underwent a crystal growth process. d(0.5) increased from 607μm to 661μm, and d(0.9) increased from 1151μm to 1303μm. When iron and antimony coexist, the degree of crystal growth on the support surface is low. The reason should be that the iron crystallization process is inhibited by the efficiency of antimony adsorbed on the surface sites.

[0105] 3D microscopic analysis of the support material before and after the reaction, the results are shown in Fig.12 .Depend on Fig.12 It can be seen that the surface of the original goethite support is yellow-brown; the surface of the goethite after batch iron / antimony removal is covered with a layer of red substance, indicating that an iron crystal layer is formed on the surface of the goethite after six batches of treatment, and its main component should be goethite, with a chemical composition of α-FeOOH, and red in color. At the same time, it was found that the surface of the support after 6 crystallization batches was not completely covered with iron crystals, mainly because: the iron ion concentration in the multi-batch experiment was not enough to make the entire support surface evenly covered with an iron crystal layer; the uncrystallized position may be the complex position of the antimony oxide anion, where it is difficult to carry out the iron crystallization reaction.

[0106] The results of SEM analysis are shown in Fig.13 The English name of scanning electron microscope is Scanning Electron Microscope, referred to as SEM. Fig.13The microstructure of the iron crystal layer on the surface after batch treatment was clearly observed. However, compared with the SEM image of the goethite support before treatment, the distribution density of the iron crystal layer on the support surface after batch treatment was lower, which was also related to the decrease in the iron crystallization rate during the simultaneous removal of Fe(II) and Sb(III).

[0107] Mapping analysis results are shown in Fig.14 The Chinese name for Mapping analysis is relationship analysis. Fig.14 It can be seen that the distribution of Sb on the surface of the goethite support shows that Sb is not only distributed on the surface sites of the original goethite support, but also on the newly generated crystal layer, which corresponds to the antimony removal mechanism mentioned above. But at the same time, through the Fe site map and the Sb site map, it is found that there are more Sb site binding areas on the goethite surface, and a large number of O sites are exposed around this area instead of Fe sites. This phenomenon shows that the sites complexed with antimony oxygen anions are more difficult to undergo the iron crystallization process, and the iron crystal layer formed during the iron crystallization process can provide complexation sites.

[0108] The results of X-ray photoelectron spectroscopy analysis are shown in Fig.15 The English name of X-ray photoelectron spectroscopy is X-ray Photoelectron Spectroscopy, abbreviated as XPS. Fig.15 The O1s+Sb 3d orbital spectra of the original goethite support, the goethite support after iron crystallization, and the goethite support after the simultaneous removal of iron and antimony are shown. Since the binding energy of the O1s spectrum and the Sb 3d spectrum is highly overlapped, the two need to be separated together. First, the Sb 3d near 540eV is separated. 3 / 2 The peaks of Sb 3d that overlap with O1s are calculated based on the correlation between the peak positions of the Sb 3d double peak orbits. 5 / 2 The peak of O1s can be considered to be contributed by three typical oxygen species. Fig.15 It can be seen that the original goethite and the goethite after iron crystallization do not have Sb 3d peaks near 540eV, while the goethite after the simultaneous removal of iron and antimony has an obvious Sb 3d peak, indicating that antimony is adsorbed and bound on goethite. 3 / 2 The peak intensity is related to the amount of antimony adsorption. Fig.15 Figure (c) shows a higher Sb 3d 3 / 2 The peak intensity also corresponds to the higher antimony removal rate in multiple batch experiments.

[0109] After the peak fitting of Sb 3d, it was found that the peaks of antimony in goethite after the simultaneous removal of iron and antimony were all characteristic peaks of Sb(V), such as 531.0eV and 540.0eV, rather than those of Sb(III), indicating that Sb(III) underwent oxidation reaction in the Fenton fluidized bed system and was converted into Sb(V). The main mechanisms are: first, the rapid oxidation of Sb(III) by hydroxyl radicals generated by the Fenton reaction; second, the goethite surface has a catalytic effect on the oxidation of Sb(III), so that Sb(III) adsorbed on the goethite surface is quickly oxidized by O in the air. 2 Oxidation; thirdly, since the ionic forms of antimony and iron have similar electrode potentials, redox reactions may occur between Sb(III) and Fe(III). In summary, due to the presence of hydroxyl radicals and goethite support in the Fenton fluidized bed system, Sb(III) with high toxicity and low mobility can be rapidly oxidized and detoxified and efficiently removed.

[0110] The results of Fourier transform infrared spectroscopy analysis are shown in Fig.16 The English name of Fourier Transform Infrared Spectroscopy is Fourier Transform Infrared Spectroscopy, or FTIR for short. Fig.16 It was found that the FTIR spectrum of goethite support was at 3428 cm -1 and 1641cm -1 The peak intensity at 3640 cm-1 was significantly reduced after batch experimental treatment. Since the peak intensity is related to the density of the functional groups of the material, it indicates that the free OH groups on the surface of goethite were consumed when adsorbing antimony oxide anions. -1 There is a faint new peak at 780cm, which represents the stretching vibration of the hydroxyl groups in the free water on the surface of the material; and -1 and 624cm -1 The peak intensity at 576, 541 and 464 cm-1 increased significantly. These two characteristic peaks belong to the bending vibration of Fe-OH and the stretching vibration of Fe-O in goethite, respectively. This change can be attributed to the progress of iron crystallization. At the same time, the characteristic adsorption peaks in the fingerprint region before and after treatment increased from 576, 541 and 464 cm-1 to 576, 541 and 464 cm-1. -1 Moved to 579, 542 and 465cm -1 , indicating that the deformation vibration of OH and Fe-O is affected by adsorption, which may be caused by the combination of Sb(V) and hydroxyl groups to form Fe-O-Sb.

[0111] The Raman spectroscopy results are shown in Fig.17 .like Fig.17 , 224cm -1 and 289cm -1 The obvious decrease of the energy band at 406cm -1 and 605cm-1 The slight weakening of the energy band at , can be attributed to the interaction between Fe-OH and Sb(V).

[0112] The mechanism of simultaneous removal of Fe(II) and Sb(III) in goethite-Fenton fluidized bed system Fig.18 As shown. There are three main reaction processes in the whole reaction process, namely redox reaction, iron crystallization process and antimony surface complexation process. Redox reaction mainly refers to the process in which trivalent antimony is oxidized to pentavalent antimony in the system. This process can be attributed to the following three reasons: first, it is due to the rapid oxidation of Sb(III) by hydroxyl radicals, which may be the main oxidation mechanism; second, the surface of goethite is oxidized to O 2 The process of oxidizing Sb(III) has a catalytic effect, which causes the Sb(III) adsorbed on the surface of goethite to be rapidly oxidized. Third, since the ionic forms of antimony and iron have similar electrode potentials, a redox reaction may occur between Sb(III) and Fe(III).

[0113] The iron crystallization process mainly includes two mechanisms, as well as the adsorption and removal of antimony oxide anions on the surface of the iron crystal layer. The surface complexation process of antimony includes the complexation of antimony oxide anions to the surface of goethite as a Fenton fluidized bed support in the form of bidentate mononuclear shared edge complexes and bidentate binuclear shared corner complexes, thereby being removed from the aqueous solution. However, it is worth noting that the complexation of antimony oxide anions will bring additional hydroxyl groups, and it is speculated that the hydroxyl groups after the complexation of antimony oxide anions are difficult to serve as reaction sites in the iron crystallization process.

[0114] Example 8

[0115] A method for removing iron-antimony by co-fixation using a Fenton fluidized bed, based on the optimization of key process parameters, uses a continuous flow Fenton fluidized bed reactor to remove iron-antimony co-crystallization from simulated wastewater. According to the method of Example 2, the optimized key process parameters are: goethite is used as the support material, the dosage of the support material is 60g / L, the pH of the simulated wastewater is 3.0, and the hydraulic retention time is 60min. Operation parameters: raw water pump flow rate Q 1 =41.67ml / min, 100mM hydrogen peroxide dosing pump flow rate Q 2 =2.24ml / min.

[0116] Long-term operation Fig.19 As shown, a total of 52 cycles were run for 7 days. The operation period can be divided into three stages: the startup period, which is the main stage for the formation of an iron crystal layer on the surface of goethite; the parameter control period, which explores the effect of the Fenton reagent ratio on the iron crystallization process and the antimony removal process, and the stable operation period using three reagent ratios of 1:1, 1:2 and 1:3. During this stage, iron and antimony ions were stably and effectively removed. Fig.19In the start-up period of the first 15 cycles, the iron crystallization rate will show a significant attenuation with the increase in the number of treatment batches, which is attributed to the site competition effect between iron ions and antimony oxide anions. In the parameter control period, the Fenton reagent ratios of 1:1 and 1:2 are not enough to completely oxidize Fe(II) and Sb(III) in the influent, resulting in a significant decrease in the iron crystallization rate and antimony removal rate, and ferrous iron was detected in the effluent. This verifies that the iron crystal layer has the ability to remove antimony oxide anions in water. After 24 cycles, the entire continuous flow device entered a stable operation period. During this stage, the antimony removal rate maintained a good stability, basically maintained at 100%, and there was no obvious downward trend in more than 20 cycles, indicating that the goethite-Fenton fluidized bed system has a good and stable removal effect on antimony in actual AMD. After the fluctuations in the first two stages, the iron crystallization rate was basically stable in the range of 64% to 74% during the stable operation period, indicating that the high concentration of antimony in the wastewater will inhibit the crystallization of iron to a certain extent. It is speculated that the oxyhydroxide formed by the iron fluidization crystallization can provide more surface hydroxyl groups for continuous iron ion crystallization and can also serve as the adsorption and immobilization sites of antimony. However, the sites on the crystal layer that fix antimony will hardly serve as the sites for the iron fluidization crystallization. A preliminary economic analysis of the whole set of treatment process showed that the total cost is 2 yuan / m 3 Within this range, it has good technical and cost competitive advantages in the field of acidic antimony mine wastewater treatment.

[0117] In summary, the rules for the simultaneous removal of Fe(II) and Sb(III) in the goethite-Fenton fluidized bed system are as follows: First, by comparing nine support materials, it was found that the Fenton fluidized bed with goethite as the support material can achieve the efficient removal of both Fe(II) and Sb(III) ions, with both the iron crystallization rate and the antimony removal rate being higher than 90%. Secondly, by investigating the effects of pH, Fenton reagent ratio, influent concentration, ionic strength and coexisting anions on the simultaneous removal of iron and antimony, combined with the characterization of the goethite support before and after multiple batches of reactions, it was found that there are three main chemical processes for the co-removal of iron and antimony, namely the oxidation of Sb(III), the crystallization of Fe(III) and the surface complex adsorption of Sb(V); at the same time, there is a competitive relationship between the fluidized crystallization of iron and the adsorption and complexation of antimony. Finally, the hydroxyl group combined with antimony cannot serve as a site for iron crystallization due to steric hindrance or reaction energy barriers, resulting in a decrease in the iron crystallization rate. Most inorganic anions have little effect on the simultaneous removal of iron / antimony, while PO 4 3- The inhibitory effect is obvious. 4 3- When the concentration was 10 mM, the antimony removal rate dropped rapidly to below 10%.

[0118] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for removing iron and antimony by co-fixation using a Fenton fluidized bed, characterized in that: The following steps are involved: Adding a support material into a Fenton fluidized bed reactor, then adding wastewater to be treated, adjusting the pH of the wastewater to be treated to 2.5-3.8, and starting the fluidization state in a continuous flow manner to make the expansion rate of the support material 50%-200%; A Fenton agent is added into the Fenton fluidized bed reactor so that the molar ratio of ferrous ions to hydrogen peroxide in the wastewater to be treated in the Fenton fluidized bed reactor is 1:0.5-5, and then a crystallization reaction of iron ions on the surface of the support occurs, and antimony ions are removed in a manner of iron-antimony co-immobilization; The support material is any one of quartz sand, garnet, forsterite, hematite, vanadium-titanium magnetite, magnetite and goethite.

2. The method for removing iron and antimony by co-fixation using a Fenton fluidized bed according to claim 1, characterized in that: After the Fenton reagent is added, the concentration ratio of ferrous ions to trivalent antimony ions in the wastewater to be treated retained in the Fenton fluidized bed reactor is 1 mM to 2 mM: 3 mg / L to 20 mg / L.

3. The method for removing iron and antimony by co-fixation using a Fenton fluidized bed according to claim 2, characterized in that: After the Fenton reagent is added, the ferrous ions in the wastewater to be treated that remain in the Fenton fluidized bed reactor are nitrates, sulfates or chlorides of ferrous ions; After the Fenton reagent is added, the trivalent antimony ions in the wastewater to be treated remaining in the Fenton fluidized bed reactor are nitrates, sulfates or chlorides of trivalent antimony.

4. The method for removing iron-antimony by co-fixation using a Fenton fluidized bed according to claim 1, characterized in that: The support material is goethite; the particle size of the support material is 16 mesh to 30 mesh.

5. The method for removing iron and antimony by co-fixation using a Fenton fluidized bed according to claim 1 or 3, characterized in that: The amount of the support material added to each liter of wastewater to be treated retained in the Fenton fluidized bed reactor is 20 g / L to 40 g / L.

6. The method for removing iron and antimony by co-fixation using a Fenton fluidized bed according to claim 1, characterized in that: Adjust the pH of the wastewater to be treated to 2.5-3.

8.

7. The method for removing iron-antimony by co-fixation using a Fenton fluidized bed according to claim 1, characterized in that: The Fenton agent is at least one of ferrous salt and hydrogen peroxide solution.

8. The method for removing iron and antimony by co-fixation using a Fenton fluidized bed according to claim 1, characterized in that: The molar ratio of ferrous ions to hydrogen peroxide in the wastewater to be treated retained in the Fenton fluidized bed reactor is 1:0.5-3.

9. The method for removing iron and antimony by co-fixation using a Fenton fluidized bed according to claim 1, characterized in that: The hydraulic retention time of the wastewater to be treated in the Fenton fluidized bed reactor is 60 minutes to 120 minutes.

10. The method for removing iron and antimony by co-fixation using a Fenton fluidized bed according to claim 1, characterized in that: Before adding the support material to the Fenton fluidized bed reactor, the support material is pretreated, and the specific method is: The support material is soaked in a HCl solution with a pH of 3 to 4 for 10 to 12 hours, then soaked in water and ultrasonically treated for 10 to 30 minutes, then washed with water until the pH is 7, and dried to obtain a pretreated support material.

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