A composition of iron-based mineral material for deep removal of trivalent arsenic from wastewater and its use

Abstract

The application discloses a kind of iron-based mineral deep removal composition of trivalent arsenic in wastewater and application thereof.The composition includes iron-oxidizing bacteria liquid and iron-based mineral;The iron-based mineral includes red mud and pyrite, and the mass ratio of red mud and pyrite is 1:0.9~1.1.The composition is used for deep removal of trivalent arsenic in wastewater, and its process is as follows: after being cultured to logarithmic phase, the iron-oxidizing bacteria is removed by centrifugation, washing and resuspension to obtain iron-oxidizing bacteria liquid;The composition including iron-oxidizing bacteria liquid and iron-based mineral is added to wastewater containing trivalent arsenic to carry out arsenic removal reaction, and after reaction, it is separated to obtain.The composition utilizes the synergistic effect between components, and realizes the oxidation-adsorption-precipitation process of trivalent arsenic in wastewater by one-step method, without adding any strong oxidizing agent for pre-oxidation treatment, especially when the arsenic concentration in wastewater is 20~200mg / L, it has excellent removal effect, and the removal efficiency of trivalent arsenic can reach 90%.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of arsenic removal compositions, specifically to a kind of iron-based mineral composition and its application for deep removal of trivalent arsenic in wastewater, belong to industrial wastewater treatment technical field. BACKGROUND

[0002] Arsenic-containing wastewater generated by mining and mineral processing industry can seriously threaten the safety of human life. Arsenic mainly exists in the form of arsenic (III) and arsenic (V), and the toxicity of arsenic (III) is about 60 times that of arsenic (V). Compared with arsenic (V), arsenic (III) has weaker interaction with most solid surfaces, and it is more difficult to remove arsenic (III) than arsenic (V). Currently, arsenic water purification technologies mainly include flocculation sedimentation, adsorption, membrane separation and ion exchange. Most of these technologies cannot efficiently remove arsenic (III), and generally require pre-treatment of arsenic (III) to be oxidized to arsenic (V). Since O2 in the air has poor oxidation effect on arsenic (III), some strong oxidizing agents such as ozone, hypochlorite, potassium permanganate and hydrogen peroxide are used to oxidize arsenic (III). However, these strong oxidizing agents are expensive and may cause residual chemicals and formation of oxidation byproducts in water. Therefore, it is urgent to explore green, efficient and low-cost As (III) removal technology.

[0003] Red mud is a high-alkaline waste generated in the production process of alumina industry, and the amount of red mud generated per ton of alumina is about 1.0-1.5 tons. Red mud has strong alkalinity and high salt content, and has high risk of pollutant migration. Pyrite is also a mining and metallurgical waste. Pyrite is easily oxidized when exposed to water, air and microbial environment, producing acidic wastewater containing high concentrations of metal ions and sulfates. It poses a significant threat to water and soil, thereby threatening the safety of humans and other organisms. Therefore, how to reasonably utilize red mud and pyrite is one of the urgent tasks faced by the mining and metallurgical industry.

[0004] In recent years, many researchers have focused on red mud and pyrite to remediate arsenic-contaminated water. Red mud can not only adsorb arsenic by forming inner-layer complexes with arsenic, but also fix arsenic through ligand exchange and iron-arsenic co-precipitation. The sulfur ions produced by the dissolution of pyrite can form low-solubility arsenic sulfide with arsenic to remove arsenic from water. However, the existing methods have poor removal effect on arsenic (III). Therefore, it is necessary to explore a new method for efficient treatment of arsenic (III) in acidic water using red mud and pyrite. However, there are few reports on the use of iron-oxidizing bacteria to promote the synergistic treatment of acidic arsenic (III)-containing wastewater by red mud and pyrite. SUMMARY

[0005] In view of the problems in the prior art, a first object of the present application is to provide an iron-based mineral material for deep removal of trivalent arsenic in wastewater, which is prepared from red mud and pyrite, and combined with iron-oxidizing bacteria to realize the oxidation-adsorption-precipitation process of trivalent arsenic in wastewater in one step through the synergistic effect of the components, without adding any strong oxidizing agent for pre-oxidation treatment of trivalent arsenic, and the composition can accommodate a large amount of mining and metallurgical solid waste, and realizes the resource utilization of red mud and the technical purpose of waste treatment by waste during the deep treatment of arsenic-containing wastewater.

[0006] A second object of the present application is to provide an application of the iron-based mineral material for deep removal of trivalent arsenic in wastewater, which is used for deep removal of trivalent arsenic in wastewater, especially when the concentration of arsenic in the arsenic-containing wastewater is 20-200 mg / L, and has excellent technical effects. The total arsenic removal efficiency of the composition provided by the present application can reach 90%, and the arsenic in the obtained precipitate mainly exists in the form of pentavalent arsenic, avoiding secondary pollution.

[0007] In order to achieve the above technical purpose, the present application provides an iron-based mineral material for deep removal of trivalent arsenic in wastewater, which comprises iron-oxidizing bacteria liquid and iron-based mineral material; the iron-based mineral material comprises red mud and pyrite, and the mass ratio of red mud to pyrite is 1:0.9-1.1.

[0008] The composition provided by the present application can realize the oxidation-adsorption-precipitation process of trivalent arsenic in wastewater in one step, wherein the iron-oxidizing bacteria significantly promote the oxidation and dissolution of pyrite in the system, the renewal of the surface of pyrite promotes the formation of hydroxyl radicals in the solution, the hydroxyl radicals as a strong oxidizing agent oxidize arsenic(III) in the solution to arsenic(V), and arsenic(V) is more easily removed by adsorption than arsenic(III); the alkali in the red mud reacts with hydrogen ions in the arsenic-containing wastewater, the agglomerated red mud particles become dispersed, the specific surface area of the red mud increases, which is more conducive to the adsorption of arsenic in water, in addition, due to the addition of iron-oxidizing bacteria, iron(II) is oxidized to iron(III), and the red mud increases the pH of the wastewater, thereby causing the hydrolysis and precipitation of iron(III) in water, and the hydrolysis product takes the red mud particles as the growth site, thereby further adsorbing arsenic in water.

[0009] As a preferred scheme, the iron-oxidizing bacteria are moderate thermophilic iron-oxidizing bacteria and / or Leptospirillum ferrooxidans.

[0010] As a preferred scheme, the bacterial concentration of the iron-oxidizing bacteria liquid is 3-7 x 10 9 ML.

[0011] As a preferred scheme, the volume-to-mass ratio of the iron-oxidizing bacteria liquid to the iron-based mineral material is 5-15 ml:3-6 g.

[0012] The application further provides a use of the composition of the iron-based mineral material for deeply removing trivalent arsenic in wastewater.

[0013] As a preferred solution, the process for deeply removing trivalent arsenic in wastewater comprises the following steps: culturing the iron-oxidizing bacteria to logarithmic phase, centrifuging, washing and resuspending to obtain an iron-oxidizing bacteria solution; adding the composition comprising the iron-oxidizing bacteria solution and the iron-based mineral material into wastewater containing trivalent arsenic to perform an arsenic removal reaction, and separating to obtain the product after the reaction.

[0014] As a preferred solution, the concentration of trivalent arsenic in the wastewater is 20-200 mg / L.

[0015] As a preferred solution, the particle size of the pyrite in the iron-based mineral material is 38-74 μm.

[0016] As a preferred solution, the 9K culture medium is used in the culturing process of the iron-oxidizing bacteria, and the pH is 1.9-2.1.

[0017] As a preferred solution, the addition amount of the iron-oxidizing bacteria solution in the wastewater is 0.5-1.5%.

[0018] As a preferred solution, the addition amount of the iron-based mineral material in the wastewater is 2-6 g / L.

[0019] As a preferred solution, the arsenic removal reaction process is as follows: the reaction is performed at 25-35°C and at a rotation speed of 150-200 r / min for 10-15 days.

[0020] As a preferred solution, the pH of the arsenic removal reaction is 3.9-4.1.

[0021] Compared with the prior art, the technical scheme of the application has the following beneficial technical effects:

[0022] 1) The composition provided by the application uses metallurgical solid waste red mud and pyrite as raw materials, and combines with iron-oxidizing bacteria to realize the oxidation-adsorption-precipitation process of trivalent arsenic in wastewater by using the synergistic effect among the three, without adding any strong oxidizing agent for pre-oxidation treatment of trivalent arsenic, and the composition can absorb a large amount of metallurgical solid waste, so that the resource utilization of red mud is realized in the process of deep treatment of arsenic-containing wastewater, and the technical purpose of waste treatment by waste is achieved.

[0023] 2) The composition is used for deep removal of trivalent arsenic in wastewater, especially when the concentration of arsenic in the wastewater containing arsenic is 20-200 mg / L, and has excellent technical effects. The total arsenic removal efficiency of the composition can reach 90%, and the arsenic in the obtained precipitate mainly exists in the form of pentavalent arsenic, thereby avoiding secondary pollution. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 SEM-EDS images of the red mud and pyrite used in the specific embodiments;

[0025] wherein, Figure 1 (a) is an electron microscope image of the pyrite used in the specific embodiments, Figure 1 (b) is an electron microscope image of the red mud used in the specific embodiments, Figure 1 (c) is an energy spectrum image of the pyrite used in the specific embodiments, Figure 1 (d) is an energy spectrum image of the red mud used in the specific embodiments;

[0026] Figure 2 XRD images of the red mud and pyrite used in the specific embodiments;

[0027] wherein, Figure 2 (a) is an XRD image of the pyrite used in the specific embodiments, Figure 2 (b) is an XRD image of the red mud used in the specific embodiments;

[0028] Figure 3 Variation curves of total arsenic, arsenic(III) proportion, pH, oxidation-reduction potential (ORP), total iron and iron(II) in the solution used in Example 1;

[0029] wherein, Figure 3 (a) is a variation curve of total arsenic in the solution used in the specific embodiment 1, Figure 3 (b) is a variation curve of arsenic(III) proportion in the solution used in the specific embodiment 1, Figure 3 (c) is a variation curve of pH in the solution used in the specific embodiment 1, Figure 3 (d) is a variation curve of oxidation-reduction potential in the solution used in the specific embodiment 1, Figure 3 (e) is a variation curve of total iron in the solution used in the specific embodiment 1, Figure 3 (f) is a variation curve of iron(II) in the solution used in the specific embodiment 1;

[0030] Figure 4 Electron paramagnetic resonance detection results of hydroxyl radicals in Example 1;

[0031] Figure 5X-ray photoelectron spectroscopy (XPS) results of the mixed minerals before and after the reaction in Example 1;

[0032] wherein, Figure 5 (a) is the X-ray photoelectron spectroscopy results of Fe 2p of the mixed minerals before and after the reaction in Specific Example 1, Figure 5 (b) is the X-ray photoelectron spectroscopy results of S 2p of the mixed minerals before and after the reaction in Specific Example 1, Figure 5 (c) is the X-ray photoelectron spectroscopy results of Al 2p of the mixed minerals before and after the reaction in Specific Example 1, Figure 5 (d) is the X-ray photoelectron spectroscopy results of As 3d of the mixed minerals before and after the reaction in Specific Example 1;

[0033] Figure 6 Transmission electron microscopy (TEM) images of the red mud particles in the mixed minerals before and after the reaction in Example 1;

[0034] wherein, Figure 6 (a) is the TEM image of the red mud particles in the mixed minerals before the reaction in Specific Example 1, Figure 6 (b) and 6(c) are the TEM images of the red mud particles in the mixed minerals after the reaction in Specific Example 1. DETAILED DESCRIPTION

[0035] For the purpose of promoting the full understanding of the present application, the application will be described in a more detailed and specific manner in connection with the attached drawings and preferred embodiments. It should be noted that the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0036] Example 1

[0037] The present embodiment provides a composition of an iron-based mineral material for deep removal of trivalent arsenic in wastewater, and uses the composition for deep removal of trivalent arsenic in wastewater, and the specific process is as follows:

[0038] (1) The iron-oxidizing bacteria are aerobically cultured in a 9K culture medium at 30°C and 170 r / min, and the culture medium is composed of (NH4)2SO43.0 g / L, K2HPO4·3H2O 0.5 g / L, MgSO4·7H2O 0.5 g / L, KCl 0.1 g / L, Ca(NO3)20.01 g / L, and FeSO4·7H2O 44.7 g / L. The initial pH of the culture medium is adjusted to 2.0 with 0.1 mol / L dilute sulfuric acid.

[0039] (2) Remove metabolites by filtration through filter paper, and then centrifuge at 10000 r / min and 4℃ for 15 minutes to obtain cell precipitate; wash the original cell precipitate with sterile iron-free 9K medium (pH=2) and centrifuge 3 times again; then dilute the cell precipitate again with sterile iron-free 9K medium (pH=2) to obtain concentrated bacterial solution without metabolites.

[0040] (3) After crushing the pyrite, collect the mineral particles with a particle size range of 38-74 μm through a wet sieve, wash them three times with deionized water, and then place them in a vacuum drying oven (35℃, 0.001 Pa) to dry for 24 hours for later use.

[0041] (4) The arsenic(III) fixation test of pyrite and red mud was carried out in a 250 mL glass conical flask, with 99 mL of 9K basic salt medium and 1 mL of concentrated bacteria added; the initial pH of the bacterial solution was adjusted to pH=2.00±0.05 with 0.1 mol / L dilute sulfuric acid, and then 2 g of solid sample (pyrite / red mud) was added to the conical flask, with the mass ratio of pyrite to red mud set to 1:1. Sodium arsenite was added to make the initial arsenic(III) concentration 200 mg / L. The conical flask was placed in a shaker at 30℃ and 170 r / min for 15 days.

[0042] (5) During the experiment, 300 μL of liquid sample was taken every 2 days, filtered through a 0.45 μm pore size filter membrane, and the total arsenic, arsenic(III), total iron, iron(II), pH value and redox potential in the solution were measured. The results were as follows: Figure 3 As shown.

[0043] Depend on Figure 3 It can be seen that the total arsenic removal efficiency in the experiment reached 88.26%, and arsenic(III) was mainly oxidized to arsenic(V). Within 0-15 days, some pyrite was oxidized and dissolved under the action of oxygen and iron-oxidizing bacteria, and the dissolved iron(II) was oxidized to iron(III) by the iron-oxidizing bacteria; Figure 4 As shown, the renewal catalysis on the pyrite surface generates more hydroxyl radicals, which oxidize arsenic(III) to arsenic(V). As the reaction proceeds, the agglomerated red mud particles gradually disperse, increasing the specific surface area, which is beneficial for arsenic fixation. Furthermore, as... Figure 3 As shown in (c), the presence of red mud raises the solution pH to approximately 4.0, causing iron(III) to precipitate; as Figure 5 As shown, within 0 to 2 days, the aluminum-oxygen bonds and iron-oxygen bonds on the surface of red mud particles mainly participate in the adsorption of arsenic. Subsequently, the hydrolysis products of iron(III) form a shell structure on the surface of the red mud particles as growth sites, and at the same time, they undergo co-precipitation reaction with arsenic(III) and arsenic(V) in the solution, thereby achieving efficient and synergistic fixation of arsenic(III) in the solution.

[0044] Example 2

[0045] This example is identical to example 1, except that the pyrite and red mud immobilization of arsenic (III) test was performed in 250 mL glass Erlenmeyer flasks, adding 99 mL of 9K minimal salts medium and 1 mL of concentrated bacteria. The initial pH of the bacteria containing solution was adjusted to pH = 2.00 ± 0.05 with 0.1 mol / L dilute sulfuric acid. Thereafter, 2 g of solid sample (pyrite / red mud) was added to the Erlenmeyer flasks. The mass ratio of pyrite to red mud was set to 1 : 1. Sodium arsenite was added so that the initial arsenic (III) concentration was 100 mg / L. The Erlenmeyer flasks were placed in a shaker at a temperature of 30 °C and a rotation speed of 170 r / min for a test period of 15 days.

[0046] It was detected that for wastewater with pH = 2.0 and arsenic (III) concentration of 100 mg / L, the total arsenic removal efficiency of the composition provided by this example was 87.50%.

[0047] Example 3

[0048] This example is identical to example 1, except that the pyrite and red mud immobilization of arsenic (III) test was performed in 250 mL glass Erlenmeyer flasks, adding 99 mL of 9K minimal salts medium and 1 mL of concentrated bacteria. The initial pH of the bacteria containing solution was adjusted to pH = 2.00 ± 0.05 with 0.1 mol / L dilute sulfuric acid. Thereafter, 2 g of solid sample (pyrite / red mud) was added to the Erlenmeyer flasks. The mass ratio of pyrite to red mud was set to 1 : 1. Sodium arsenite was added so that the initial arsenic (III) concentration was 50 mg / L. The Erlenmeyer flasks were placed in a shaker at a temperature of 30 °C and a rotation speed of 170 r / min for a test period of 15 days.

[0049] It was detected that for wastewater with pH = 2.0 and arsenic (III) concentration of 50 mg / L, the total arsenic removal efficiency of the composition provided by this example was 87.12%.

[0050] Example 4

[0051] This example is identical to example 1, except that the pyrite and red mud immobilization of arsenic (III) test was performed in 250 mL glass Erlenmeyer flasks, adding 99 mL of 9K minimal salts medium and 1 mL of concentrated bacteria. The initial pH of the bacteria containing solution was adjusted to pH = 2.00 ± 0.05 with 0.1 mol / L dilute sulfuric acid. Thereafter, 2 g of solid sample (pyrite / red mud) was added to the Erlenmeyer flasks. The mass ratio of pyrite to red mud was set to 1 : 1. Sodium arsenite was added so that the initial arsenic (III) concentration was 25 mg / L. The Erlenmeyer flasks were placed in a shaker at a temperature of 30 °C and a rotation speed of 170 r / min for a test period of 15 days.

[0052] It was detected that the total arsenic removal efficiency of the composition provided by the embodiment was 82.77% for wastewater with pH=2.0 and arsenic (III) concentration of 25 mg / L.

[0053] Comparative Example 1

[0054] The comparative example was completely identical with Example 1, except that no iron-oxidizing bacteria was added.

[0055] It was detected that the total arsenic removal efficiency of the composition provided by the comparative example was 67.58% for wastewater with pH=2.0 and arsenic (III) concentration of 200 mg / L.

[0056] Comparative Example 2

[0057] The comparative example was completely identical with Example 2, except that no iron-oxidizing bacteria was added.

[0058] It was detected that the total arsenic removal efficiency of the composition provided by the comparative example was 56.23% for wastewater with pH=2.0 and arsenic (III) concentration of 100 mg / L.

[0059] Comparative Example 3

[0060] The comparative example was completely identical with Example 3, except that no iron-oxidizing bacteria was added.

[0061] It was detected that the total arsenic removal efficiency of the composition provided by the comparative example was 70.50% for wastewater with pH=2.0 and arsenic (III) concentration of 50 mg / L.

[0062] Comparative Example 4

[0063] The comparative example was completely identical with Example 4, except that no iron-oxidizing bacteria was added.

[0064] It was detected that the total arsenic removal efficiency of the composition provided by the comparative example was 60.55% for wastewater with pH=2.0 and arsenic (III) concentration of 25 mg / L.

[0065] Comparative Example 5

[0066] The comparative example was completely identical with Example 1, except that no pyrite and iron-oxidizing bacteria was added.

[0067] It was detected that the total arsenic removal efficiency of the composition provided by the comparative example was 28.08% for wastewater with pH=2.0 and arsenic (III) concentration of 200 mg / L.

[0068] Comparative Example 6

[0069] This comparative example is identical to Example 1, except that no pyrite is added.

[0070] It was detected that for wastewater with pH = 2.0 and arsenic (III) concentration of 200 mg / L, the total arsenic removal efficiency of the composition provided by this comparative example was 1.63%.

[0071] Comparative Example 7

[0072] This comparative example is identical to Example 1, except that no red mud and iron-oxidizing bacteria are added.

[0073] It was detected that for wastewater with pH = 2.0 and arsenic (III) concentration of 200 mg / L, the total arsenic removal efficiency of the composition provided by this comparative example was 48.748%.

[0074] Comparative Example 8

[0075] This comparative example is identical to Example 1, except that no red mud is added.

[0076] It was detected that for wastewater with pH = 2.0 and arsenic (III) concentration of 200 mg / L, the total arsenic removal efficiency of the composition provided by this comparative example was 2.25%.

Claims

1. An iron-based mineral composition for deep removal of trivalent arsenic from wastewater, characterized in that: The composition comprises iron-oxidizing bacteria solution and iron-based mineral materials; the iron-based mineral materials comprise red mud and pyrite, and the mass ratio of the red mud to the pyrite is 1:0.9-1.1; The iron-oxidizing bacteria are moderate thermophilic iron-oxidizing bacteria and / or Leptospirillum ferrooxidans; The concentration of the iron-oxidizing bacteria is 3-7×10 9 The volume / mass ratio of the iron-oxidizing bacteria to the iron-based mineral material is 5-15 ml:3-6 g. The process for deeply removing trivalent arsenic from wastewater comprises the following steps: culturing the iron-oxidizing bacteria to the logarithmic phase, centrifuging, washing and resuspending to obtain the iron-oxidizing bacteria solution; adding the composition comprising the iron-oxidizing bacteria solution and the iron-based mineral materials into the wastewater containing trivalent arsenic to perform the arsenic removal reaction, and separating after the reaction to obtain the product. The concentration of the trivalent arsenic in the wastewater is 20-200 mg / L; the particle size of the pyrite in the iron-based mineral materials is 38-74 μm; the temperature of the arsenic removal reaction is 25-35 ℃, and the pH is 3.9-4.

1.

2. The composition of claim 1, wherein the composition is an iron-based mineral composition for deep removal of trivalent arsenic from wastewater. The iron-oxidizing bacteria are cultured by using 9K culture medium.

3. The composition of claim 1, wherein the composition is an iron-based mineral composition for deep removal of trivalent arsenic from wastewater. The adding amount of the iron-oxidizing bacteria solution in the wastewater is 0.5-1.5%, and the adding amount of the iron-based mineral materials in the wastewater is 2-6 g / L.

4. The composition of claim 1, wherein the composition is an iron-based mineral composition for deep removal of trivalent arsenic from wastewater. The arsenic removal reaction is performed at a rotating speed of 150-200 r / min for 10-15 days.

5. The composition of claim 1, wherein the composition is an iron-based mineral composition for deep removal of trivalent arsenic from wastewater. The pH of the iron-oxidizing bacteria culture is 1.9-2.1.

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