A method for promoting hematite treatment of antimony-containing wastewater

Abstract

The invention discloses a method for promoting hematite to treat antimony-containing wastewater, the steps of which include: preparing a solution, mixing a Mn(II) solution and a Sb(V) stock solution, adjusting pH, adding hematite, and separating and recovering. The method for promoting hematite to treat antimony-containing wastewater uses natural hematite as a mineral reaction interface, and by adding manganese ions, manganese oxide is formed on the surface of the hematite, and the manganese oxide can be formed on an aggregate of one or more hematite nanocrystals and grow in different directions, so that Sb(V) is fixed on the hematite, thereby improving the adsorption capacity of hematite to Sb(V), thereby improving the adsorption amount; and by means of electrostatic attraction and surface complexation, the treatment capacity of hematite to antimony-containing wastewater is increased.

Description

Technical Field

[0001] The invention relates to the technical field of water treatment, and in particular to a method for promoting hematite to treat antimony-containing wastewater. Background Art

[0002] China's antimony reserves account for about 52% of the world's total, making it the world's largest antimony producer. In recent years, with the rapid development of industry, the demand for antimony and antimony-containing products has greatly increased. Excessive mining and smelting of antimony mines have caused serious antimony pollution problems in surrounding surface waters, posing a serious threat to human health and ecological security. Some scholars have found that when the total antimony concentration in food is used to calculate the exposure risk, the total amount of antimony ingested by residents through food per day, after bioavailability correction, reaches 1807ng·kg -1 ·d -1 , which is much higher than the reference dose of 400ng·kg recommended by the US Environmental Protection Agency -1 ·d -1 , there is a greater risk of antimony poisoning, and symptoms of antimony poisoning such as headache, dizziness, abdominal pain, constipation and loss of appetite are likely to occur.

[0003] Antimony metal exists in the environment in two oxidation states: Sb(III) and Sb(V). In neutral oxygen-rich surface water, Sb(V) is the main form of occurrence, and the mobility of Sb(V) is higher than that of Sb(III). Sb(V) pollution in surface water poses a serious environmental safety risk. The US Environmental Protection Agency and the European Union have listed antimony as a priority pollutant. The World Health Organization stipulates that the sanitary standard for antimony in drinking water is 20ug / L. The antimony concentration limit in China's "Surface Water Environmental Quality Standard" (GB3838-2002) is 0.005mg / L.

[0004] Although the current treatment methods for antimony-containing wastewater include electrochemical treatment and adsorption, although the electrochemical treatment method can effectively remove Sb(V), the equipment purchase and operation costs are high. The adsorption method uses an adsorbent to adsorb Sb(V). As a traditional adsorbent, natural hematite is difficult to use for metal adsorption due to its stable chemical properties and few reaction sites. The adsorption efficiency of Sb(V) is poor, resulting in a low adsorption amount and difficult regeneration. Summary of the invention

[0005] The purpose of the present invention is to propose a method for promoting hematite to treat antimony-containing wastewater, so as to solve the problem that the existing adsorbent preparation process is complicated, the cost is high, and it is difficult to promote and apply it on a large scale in engineering practice.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for promoting hematite to treat antimony-containing wastewater, comprising the following steps:

[0008] Prepare the solution: dissolve the divalent manganese salt in deionized water and prepare it into a Mn(II) solution according to the ratio; then mix the antimony-containing wastewater and deionized water according to the ratio to form a Sb(V) stock solution;

[0009] Mixing the Mn(II) solution and the Sb(V) stock solution: mixing the Mn(II) solution and the Sb(V) stock solution to form a mixed solution;

[0010] Adjusting pH: detecting the pH value of the mixed solution and adjusting the pH value of the mixed solution to a predetermined range by using an alkaline solution or an acidic solution;

[0011] Add hematite: Add hematite to the mixture;

[0012] Separation and recovery: Separate the hematite and the mixed liquor, and recover the hematite and the mixed liquor separately.

[0013] The method for promoting hematite treatment of antimony-containing wastewater includes, in the step of adding hematite, the following steps: stirring the mixed solution containing hematite to allow the hematite to fully contact the mixed solution, and maintaining the temperature of the mixed solution containing hematite at a preset temperature.

[0014] In the method for promoting hematite to treat antimony-containing wastewater, the stirring speed is 100-300 rpm / min, and the preset temperature is 15-40°C.

[0015] In the method for promoting hematite treatment of antimony-containing wastewater, in the step of adding hematite, during the stirring period, the pH value detection is repeated at each threshold time interval. When the pH value fluctuates by more than 0.05, the pH value of the mixed solution is maintained within a predetermined range by an alkaline solution or an acidic solution.

[0016] In the method for promoting hematite treatment of antimony-containing wastewater, in the step of adding hematite, the contact time between the hematite and the mixed solution is 115 to 130 hours, and the threshold time is 12 hours.

[0017] In the method for promoting hematite to treat antimony-containing wastewater, the predetermined range of the pH value of the mixed solution is 7.3 to 7.6, the alkaline solution includes one or both of KOH and NaOH, and the acidic solution includes one or both of HNO3 and HCl.

[0018] In the method for promoting hematite to treat antimony-containing wastewater, the concentration of Mn(II) in the mixed solution is 0.5-8.0 mM, and the concentration of Sb(V) in the mixed solution is 0.05-2.0 mM.

[0019] In the method for promoting hematite to treat antimony-containing wastewater, the hematite is in the form of hexagonal flakes, and the hexagonal side length of the hematite is 100-200 nm.

[0020] In the method for promoting hematite to treat antimony-containing wastewater, the dosage of the hematite is 0.1 to 0.9 g / L.

[0021] A technical solution in the present invention can have the following beneficial effects:

[0022] The method for promoting hematite to treat antimony-containing wastewater uses natural hematite as a mineral reaction interface, and forms manganese oxide on the surface of the hematite by adding manganese ions. The manganese oxide can be formed on an aggregate of one or more hematite nanocrystals and grow in different directions, so that Sb(V) is fixed on the hematite, thereby improving the adsorption capacity of hematite for Sb(V), thereby increasing the adsorption amount; and the treatment capacity of hematite for antimony-containing wastewater is increased by electrostatic attraction and surface complexation. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a line graph of the adsorption amount of Sb(V) versus time in Examples 1 to 3 of the present invention;

[0024] Figure 2 is a line graph of the adsorption amount of Sb(V) versus time in Examples 1 and 4 to 6 of the present invention;

[0025] Figure 3 is a line graph of the adsorption amount of Sb(V) versus time in Examples 1 and 7 to 9 of the present invention;

[0026] Figure 4 is a line graph of the adsorption amount of Sb(V) versus time in Examples 1 and 10 to 12 of the present invention;

[0027] Figure 5 This is the SEM image of hematite;

[0028] Figure 6 is a SEM image of hematite particles separated and obtained in Example 2 of the present invention;

[0029] Figure 7 is a SEM image of hematite particles separated and obtained in Example 13 of the present invention;

[0030] Figure 8 is a SEM image of hematite particles separated and obtained in Example 14 of the present invention;

[0031] Fig. 9 is a SEM image of the hematite particles separated and obtained in Example 15 of the present invention;

[0032] Fig.10 is a SEM image of hematite particles separated and obtained in Example 7 of the present invention;

[0033] Fig.11 is a SEM image of hematite particles separated and obtained in Example 8 of the present invention;

[0034] Fig.12 is a SEM image of hematite particles separated and obtained in Example 9 of the present invention;

[0035] Fig.13 is a SEM image of hematite particles separated and obtained in Example 9 of the present invention;

[0036] Fig.14 It is the XPS spectrum of Example 2, Examples 7 to 9, Examples 13 to 15 and a blank control group in the present invention;

[0037] Fig.15 It is the fine spectrum peak diagram of Example 2, Examples 7 to 9, Examples 13 to 15 and the blank control group in the present invention. DETAILED DESCRIPTION

[0038] The technical scheme of the present invention is further illustrated by specific embodiments below. In order to facilitate understanding of the present invention, the present invention is described more comprehensively below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0039] If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in the field or the product instructions are used. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0041] Please refer to Figures 1 to 15 The present invention provides a method for promoting hematite to treat antimony-containing wastewater, comprising the following steps:

[0042] Prepare the solution: dissolve the divalent manganese salt in deionized water and prepare it into a Mn(II) solution according to the ratio; then mix the antimony-containing wastewater and deionized water according to the ratio to form a Sb(V) stock solution;

[0043] Mixing the Mn(II) solution and the Sb(V) stock solution: mixing the Mn(II) solution and the Sb(V) stock solution to form a mixed solution;

[0044] Adjusting pH: detecting the pH value of the mixed solution and adjusting the pH value of the mixed solution to a predetermined range by using an alkaline solution or an acidic solution;

[0045] Add hematite: Add hematite to the mixture;

[0046] Separation and recovery: Separate the hematite and the mixed liquor, and recover the hematite and the mixed liquor separately.

[0047] The surface of hematite contains a large number of oxygen-containing functional groups, such as the triple bond Fe-OH. When Mn(II) and Sb(V) coexist, hematite is negatively charged in the reaction system, which is conducive to the adsorption and enrichment of positively charged Mn(II) through electrostatic attraction. Mn(II) can play a cation bridging role. The positively charged Mn(II) fixed on the surface of hematite can act as an ion bridge to promote hematite to the negatively charged oxygen-containing anion group Sb(OH) 6- At the same time, manganese oxides are formed during the fixation of Mn(II) by hematite, and manganese oxides have a strong affinity for Sb(V). Manganese oxides have a large specific surface area, a high density of surface hydroxyl groups, and a high oxidation potential, which makes them highly reactive to Sb(V).

[0048] The method for promoting hematite to treat antimony-containing wastewater uses natural hematite as a mineral reaction interface, and forms manganese oxide on the surface of the hematite by adding manganese ions. The manganese oxide can be formed on an aggregate of one or more hematite nanocrystals and grow in different directions, so that Sb(V) is fixed on the hematite, thereby improving the adsorption capacity of hematite for Sb(V), thereby increasing the adsorption amount; and the treatment capacity of hematite for antimony-containing wastewater is increased by electrostatic attraction and surface complexation.

[0049] In the prior art, Mn(II) is a divalent manganese ion, Sb(V) is a pentavalent antimony ion, and Sb(III) is a trivalent antimony ion.

[0050] In a specific embodiment of the present invention, the divalent manganese salt is specifically MnCl2·4H2O.

[0051] Specifically, the step of adding hematite further includes the following steps: stirring the mixed solution containing hematite to allow the hematite to fully contact the mixed solution, and maintaining the temperature of the mixed solution containing hematite at a preset temperature.

[0052] By adopting the above structure, the mixed solution containing hematite is stirred to make the hematite fully contact with the mixed solution, so as to accelerate the process of fixing Mn(II) by hematite to increase the content of manganese oxide. At the same time, Mn(II) can be used as an ion bridge on the surface of hematite more quickly to promote the hematite to negatively charged oxygen-containing anion group Sb(OH) 6-The fixation of hematite is achieved, thereby achieving the purpose of enhancing the adsorption capacity of hematite for Sb(V) in the mixed solution.

[0053] The temperature of the mixed solution containing hematite is maintained at a preset temperature, which can ensure the temperature stability of the entire reaction system, which is beneficial to the formation of manganese oxide and the fixation of Sb(V).

[0054] Specifically, the stirring speed is 100-300 rpm / min, and the preset temperature is 15-40°C.

[0055] In a specific embodiment of the present invention, the stirring speed is 100-300 rpm / min, and the preset temperature is 20-25° C. In one embodiment, the mixed solution containing hematite is placed in a reaction container, and the reaction container is placed on a constant temperature shaker for oscillation reaction, and the mixed solution is stirred by oscillation to make the hematite and the mixed solution fully contact.

[0056] Specifically, in the step of adding hematite, during the stirring period, the pH value detection is repeated at each threshold time interval. When the pH value fluctuates by more than 0.05, the pH value of the mixed solution is maintained within a predetermined range by an alkaline solution or an acidic solution.

[0057] By adopting the above steps, the pH value is detected once each time the threshold time is reached, which can ensure that the pH value of the entire reaction system is stable, which is conducive to the formation of manganese oxide and the fixation of Sb(V).

[0058] Specifically, in the step of adding hematite, the contact time between the hematite and the mixed solution is 115 to 130 hours, and the threshold time is 12 hours.

[0059] The above contact time between hematite and the mixed solution is adopted so that hematite can adsorb Sb(V) in the mixed solution as much as possible to improve the ability to treat antimony-containing wastewater. The threshold time is 12 hours, and the pH value is tested every 12 hours to avoid the contact time between hematite and the mixed solution being too long, resulting in changes in pH value and affecting the fixation of Sb(V).

[0060] Specifically, the predetermined range of pH value of the mixed solution is 7.3-7.6, the alkaline solution includes one or both of KOH and NaOH, and the acidic solution includes one or both of HNO3 and HCl.

[0061] When the pH value of the mixed solution is in the range of 7.3 to 7.6, hematite is negatively charged in the reaction system, which is conducive to the adsorption and enrichment of positively charged Mn(II) through electrostatic attraction.

[0062] KOH and NaOH are common alkaline solutions. When the pH value of the mixed solution decreases, KOH or NaOH can be added to return the pH value of the mixed solution to a predetermined range. Similarly, HNO3 and HCl are common acidic solutions. When the pH value of the mixed solution increases, HNO3 and HCl can be added to return the pH value of the mixed solution to a predetermined range. The use of the above alkaline solution and acidic solution can avoid the problem of the reaction of the introduced new ions with Mn(II) and the reduction of the Mn(II) concentration.

[0063] Specifically, the concentration of Mn(II) in the mixed solution is 0.5-8.0 mM, and the concentration of Sb(V) in the mixed solution is 0.05-2.0 mM.

[0064] Specifically, the dosage of the hematite is 0.1 to 0.9 g / L.

[0065] By using the above-mentioned concentrations of Mn(II) solution and Sb(V) stock solution, as well as the dosage of hematite, Sb(V) in antimony-containing wastewater can be effectively treated.

[0066] Specifically, the hematite is in the form of hexagonal flakes, and the hexagonal side length of the hematite is 100-200 nm. The flake-shaped hematite exposes {113} and {001} crystal planes, has a strong affinity with Mn(II), and is conducive to catalytic oxidation of Mn(II) to form manganese oxides.

[0067] Example Group A

[0068] Preparation of solution: dissolving divalent manganese salt in deionized water and preparing a 0.5 mol / LMn(II) solution according to a ratio; then mixing antimony-containing wastewater and deionized water according to a ratio to prepare a 0.05 mol / Sb(V) stock solution;

[0069] Mixing the Mn(II) solution and the Sb(V) stock solution: According to the ratio shown in Table 1, the Mn(II) solution and the Sb(V) stock solution are mixed to form a mixed solution;

[0070] Adjust pH: Check the pH value of the mixed solution and adjust the pH value of the mixed solution to 7.5 with an alkaline solution or an acidic solution;

[0071] Adding hematite: adding 0.5 g / L hematite to the mixed solution; placing the mixed solution containing hematite on a constant temperature shaker, shaking and stirring the mixed solution containing hematite to make the hematite fully contact with the mixed solution, and maintaining the temperature of the mixed solution containing hematite at 25° C., and the shaking speed is 200 rpm / min;

[0072] During the shaking period, the pH value was tested repeatedly every 12 hours. When the pH value fluctuated by more than 0.05, the pH value of the mixed solution was maintained at 7.5 by using KOH, NaOH, HNO3 or HCl.

[0073] Separation and recovery: The supernatant and the hematite particles after the reaction are separated by centrifugation. The hematite particles after centrifugation are repeatedly washed with deionized water to remove Mn(II) and Sb(V) free on the hematite. The supernatant is the mixed solution after the reaction.

[0074] Table 1 - Concentrations of Mn(II) and Sb(V) in the mixed solution in each example

[0075]

[0076] Among them, after monitoring the pH value of the suspension every 12 hours, 5 mL of the mixed solution of Examples 1 to 12 was drawn with a syringe, filtered through a 0.45 μm filter membrane, and used to determine the residual concentration of Sb(V) after adsorption. The adsorption amount of Sb(V) was obtained based on the results and plotted into a line graph. The results are shown in Figures 1 to 4 .

[0077] according to Figures 1 to 4 It can be seen that in the binary system of Sb(V) at 0.10 mM, 0.25 mM and 0.50 mM and hematite, equilibrium was reached after 120 h and the adsorption amount of Sb(V) was 6.25 mg·g -1 , 8.76mg·g -1 , 9.08mg·g -1 When Mn(II) and Sb(V) were added simultaneously to the hematite suspension, hematite could adsorb more Sb(V) at all Sb(V) concentrations compared to the system without Mn(II).

[0078] Please refer to Figures 1 to 4 In the presence of 2.0 mM Mn(II), the adsorption amounts of Sb(V) after 120 h were 30.10 mg·g at 0.10 mM, 0.25 mM, and 0.50 mM Sb(V), respectively. -1 , 45.62mg·g -1 and 96.7 mg·g -1 Compared with the adsorption of Sb(V) by hematite alone, the adsorption amount increased by 4.8 times, 5.2 times, and 10.6 times, respectively. This indicates that the presence of Mn(II) greatly promotes the adsorption of Sb(V) by hematite. The higher the concentration of Mn(II), the more obvious the promotion effect: when Mn(II) is 4.0 mM, the adsorption amount of Sb(V) by hematite is 34.6 mg·g -1 、62.0mg·g -1 , 108.7mg·g -1, the adsorption amount increased by 5.5 times, 7.1 times and 11.1 times.

[0079] The hematite particles separated from Examples 2, Examples 7-9 and Examples 13-15 were placed under a scanning electron microscope for morphological characterization. At the same time, hematite was used as a blank control group. The morphologies of the blank control group and the hematite after the reaction were as follows: Figures 5 to 12 shown.

[0080] according to Figures 5 to 12 It can be seen that after reacting with Mn(II) for 120h, a large number of rod-shaped products were generated on the hematite. The formation of this product can be attributed to the manganese oxide formed by the oxidation of Mn on the surface of hematite. And with the increase of Mn concentration, the rod-shaped products become longer and more numerous; please refer to Fig. 9 , the surface of hematite with 4.0mM Mn(II) was completely covered by these rod-shaped products. The distribution of hematite unit particles is relatively dispersed, the aggregation is low, the specific surface area is large, and there are more manganese oxides exposed on the particle surface. Therefore, during adsorption, the iron oxides and the manganese oxides on the particle surface increase the contact and binding sites with Sb(V), thereby improving the adsorption rate.

[0081] The hematite particles separated from Examples 2, 7 to 9 and 14 were used for zeta potential. At the same time, hematite was used as a blank control group. The results are as follows: Fig.13 shown.

[0082] according to Fig.13 It can be seen that when Mn(II) and Sb(V) coexist, in the reaction system, when the pH of hematite is 7.5, it is negatively charged, which is conducive to the adsorption and enrichment of positively charged Mn(II) through electrostatic attraction.

[0083] The hematite particles separated from Examples 2, Examples 7 to 9 and Example 14 were subjected to X-ray photoelectron spectroscopy analysis. At the same time, hematite was used as a blank control group. The results are as follows: Fig.14 and Fig.15 shown.

[0084] according to Fig.14 and Fig.15 It can be seen that Sb(V) and Mn(II) exist at the same time, and the characteristic peaks of Sb 3d and Mn 2p appear on the hematite after the reaction. With the increase of Mn(II) concentration, the intensity of Sb 3d characteristic peak increases, which proves that the presence of Mn(II) promotes the adsorption of Sb(V) by hematite, and the greater the concentration of Mn(II), the more obvious the promotion effect. From the fine spectrum of Sb 3d ( Fig.15 ) we can see that the 3d 3 / 2It appears at a binding energy of 539.9 eV, indicating that the Sb fixed on hematite is pentavalent and no redox reaction occurs during the Sb(V) fixation process.

[0085] The technical principle of the present invention is described above in conjunction with specific embodiments. These descriptions are only for explaining the principle of the present invention and cannot be interpreted as limiting the scope of protection of the present invention in any way. Based on the explanations herein, those skilled in the art can associate other specific embodiments of the present invention without creative work, and these equivalent variations or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A method for promoting hematite to treat antimony-containing wastewater, characterized in that: The following steps are involved: Prepare the solution: dissolve the divalent manganese salt in deionized water and prepare it into a Mn(II) solution according to the ratio; then mix the antimony-containing wastewater and deionized water according to the ratio to form a Sb(V) stock solution; Mixing the Mn(II) solution and the Sb(V) stock solution: mixing the Mn(II) solution and the Sb(V) stock solution to form a mixed solution; Adjusting pH: detecting the pH value of the mixed solution and adjusting the pH value of the mixed solution to a predetermined range by using an alkaline solution or an acidic solution; Add hematite: Add hematite to the mixture; Separation and recovery: Separate the hematite and the mixed liquor, and recover the hematite and the mixed liquor separately.

2. A method for promoting hematite treatment of antimony-containing wastewater according to claim 1, characterized in that: The step of adding hematite also includes the following steps: stirring the mixed solution containing hematite to allow the hematite to fully contact the mixed solution, and maintaining the temperature of the mixed solution containing hematite at a preset temperature.

3. A method for promoting hematite treatment of antimony-containing wastewater according to claim 2, characterized in that: The stirring speed is 100-300 rpm / min, and the preset temperature is 15-40°C.

4. The method for promoting hematite treatment of antimony-containing wastewater according to claim 1, characterized in that: In the step of adding hematite, during the stirring period, the pH value detection is repeated at each threshold time interval. When the pH value fluctuates by more than 0.05, the pH value of the mixed solution is maintained within a predetermined range by using an alkaline solution or an acidic solution.

5. A method for promoting hematite treatment of antimony-containing wastewater according to claim 4, characterized in that: In the step of adding hematite, the contact time between the hematite and the mixed solution is 115 to 130 hours, and the threshold time is 12 hours.

6. The method for promoting hematite treatment of antimony-containing wastewater according to claim 1, characterized in that: The predetermined range of pH value of the mixed solution is 7.3-7.6, the alkaline solution includes one or both of KOH and NaOH, and the acidic solution includes one or both of HNO3 and HCl.

7. The method for promoting hematite treatment of antimony-containing wastewater according to claim 1, characterized in that: The concentration of Mn(II) in the mixed solution is 0.5-8.0 mM, and the concentration of Sb(V) in the mixed solution is 0.05-2.0 mM.

8. The method for promoting hematite treatment of antimony-containing wastewater according to claim 1, characterized in that: The dosage of the hematite is 0.1-0.9 g / L.

9. The method for promoting hematite treatment of antimony-containing wastewater according to claim 1, characterized in that: The hematite is in the shape of hexagonal flakes, and the hexagonal side length of the hematite is 100-200 nm.

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