A stabilized reductive iron-sulfur-based slurry and its preparation method and application

Abstract

The application discloses a kind of stabilized reducing iron sulfur-based slurry and its preparation method and application, the slurry is organic matter-coagulant-ferrous sulfide nanoparticle suspension, including the following components by mass percentage concentration: the slurry includes the following components by mass percentage concentration: organic matter: 0.5-5%, coagulant: 1-10%, ferrous sulfide nanoparticles: balance.It is prepared as follows: organic matter solution is mixed with ferrous sulfate solution and stirred, then mixed with coagulant solution and stirred, then slowly drop sodium sulfide solution, stirring, so that nano ferrous sulfide particles are formed in mixed solution, then centrifuged, and the supernatant is discarded to obtain the slurry.The slurry of the application can be prepared in a short process and at a low cost, can efficiently and quickly treat hexavalent chromium contaminated water, can be stored at normal temperature and pressure for at least one month without deterioration, has a small dosage, the precipitate after treatment is stable, avoids secondary pollution, and has potential application value.

Description

Technical Field

[0001] This invention relates to a water treatment slurry, its preparation method and application, and more particularly to a stabilized reducing iron-sulfur based slurry, its preparation method and application. Background Technology

[0002] Iron-sulfur based materials have attracted widespread attention due to their excellent reducing properties and broad application potential. These materials have significant application value in water treatment, heavy metal removal, and environmental remediation. Especially in the removal of heavy metals from water, iron-sulfur based materials can effectively remove heavy metal ions such as chromium, cadmium, and lead from water through chemical reduction reactions, reducing their toxicity and bioavailability.

[0003] Traditional iron-sulfur-based materials typically suffer from drawbacks such as complex preparation processes, unstable storage, low iron and sulfur concentrations, and difficulty in large-scale production. Due to the susceptibility of micro / nano particles to oxidation and unstable aggregation, existing research often employs stabilizers (such as silicates, organic complexes, or organic polymers) and dilute solutions to prepare colloids or emulsions. However, the resulting iron-sulfur-based materials have low iron and sulfur content, leading to problems such as high dosage, easy loss, poor durability, and easy rebound of treatment effects during practical applications, severely limiting their application. Compared to other iron-sulfur-based materials, ferrous sulfide (FeS), as a heavy metal stabilizer, contains both ferrous and sulfide ions, exhibiting excellent reducing properties and several unique advantages in water treatment. However, FeS nanoparticles are prone to aggregation and oxidation during practical applications, resulting in a decrease in their ability to reduce and remove pollutants. Therefore, how to modify nano-FeS to enhance its dispersibility, stability, and reactivity, and improve its stability during production and storage, has become a current research hotspot. Loading, embedding, or stabilizing FeS nanoparticles to enhance their antioxidant properties, reducing properties, and stability is a current trend in FeS modification research.

[0004] Existing research on the modification of nano-FeS generally involves two approaches: coating with stabilizers and using supporting materials. Adding stabilizers can form a negatively charged film on the surface of nanoparticles during FeS synthesis, providing strong steric hindrance and electrostatic repulsion, effectively controlling the FeS particle size. Examples include nano-iron materials modified with sodium carboxymethyl cellulose (CMC), sericin, ascorbic acid, and acrylic resin-coated black sugar. Using mineral or carbon-based supporting materials can adjust particle size, enhance particle permeability, and effectively disperse nano-FeS, reducing agglomeration. Examples include biochar used in Chinese patents CN108996710A and CN106966456A, magnesium-based materials used in Chinese patent CN108620047A, and Al2O3 used in (Li Ning et al., 2013). However, all these research findings on modified FeS materials suffer from problems such as low iron and sulfur content, easy oxidation and agglomeration, and low decontamination efficiency, and lack research on storage stability.

[0005] Currently, the following problems still exist in the practical application of modified FeS: (1) The effective component content in the dispersed ferrous sulfide colloid is low, which makes it easy to lose and dilute during the actual application process; (2) The introduced stabilizers or loading materials may cause secondary pollution to the environment, or the stability of the product after reaction is poor, and it is easy to yellow and release pollutants again; (3) Most nano FeS materials have problems such as difficulty in large-scale preparation, difficulty in storage, and short shelf life, which have become bottleneck problems for the large-scale application of FeS. Summary of the Invention

[0006] Purpose of the invention: The purpose of this invention is to provide a stabilized reducing iron-sulfur-based slurry that can reduce FeS oxidation and agglomeration deactivation, increase the reducing iron-sulfur content, and is easy to store.

[0007] A second objective of this invention is to provide a method for preparing the above-mentioned stabilized reducing iron-sulfur based slurry;

[0008] A third objective of this invention is to provide the application of the aforementioned stabilized reducing iron-sulfur based slurry.

[0009] Technical solution: The stabilized reducing iron-sulfur based slurry of the present invention is an organic matter-coagulant-ferrous sulfide nanoparticle suspension; the slurry comprises the following components by mass percentage concentration: organic matter: 0.5-5%, coagulant: 1-10%, ferrous sulfide nanoparticles: balance.

[0010] The organic matter is at least one of humic acid, disodium ethylenediaminetetraacetate, aminotrimethylene phosphonate, ethylenediaminetetramethylene phosphonate, or hydroxymethylene phosphonate; the coagulant is at least one of polyferric sulfate, polyaluminum chloride, polyacrylamide, or dicyandiamide resin organic coagulant; and the ferrous sulfide nanoparticles have a particle size of 500-1000 nm.

[0011] The above-mentioned method for preparing stabilized reducing iron-sulfur based slurry includes the following steps:

[0012] (1) Mix the organic matter solution with the ferrous sulfate solution and stir to fully complex the ferrous ions with the organic matter;

[0013] (2) Mix the coagulant solution with the solution obtained in step (1) and stir to encapsulate the complex of ferrous ions and organic matter in the mixture;

[0014] (3) Add sodium sulfide solution slowly to the mixed solution obtained in step (2) and stir to form nano-ferrous sulfide particles in the mixed solution. Then centrifuge and discard the supernatant to obtain an organic matter-coagulant-ferrous sulfide nanoparticle suspension.

[0015] The volume ratio of the organic matter solution, coagulant, ferrous sulfate solution and sodium sulfide solution is 5:5:2:1-3:3:2:1.

[0016] In step (1), the added organic matter solution has a mass percentage concentration of 0.5-5%, and the added ferrous sulfate solution has a mass percentage concentration of 5-15 mol / L.

[0017] In step (1), the stirring speed is 200-500 rpm and the time is 5-10 min.

[0018] In step (2), the mass percentage concentration of the coagulant solution is 1-10%.

[0019] In step (2), the stirring speed is 200-500 rpm and the time is 5-10 min.

[0020] The ferrous sulfide content in the organic matter-coagulant-ferrous sulfide nanoparticle suspension obtained in step (3) is not higher than 80 g / L and not lower than 40 g / L.

[0021] In step (3), the molar concentration of the added sodium sulfide solution is 5-20 mol / L.

[0022] In step (3), the stirring speed after adding sodium sulfide solution is 200-500 rpm; the time is 5-10 min; and the centrifugation speed is 3000-6000 rpm.

[0023] The above-mentioned stabilized reducing iron-sulfur based slurry is used in the removal of heavy metals from water.

[0024] The application method is as follows: the prepared water heavy metal removal material is added to water containing heavy metal chromium, so that the volume ratio of the two is about 200:1-100:1, and the mixture is stirred at 200-500 rpm for 10-30 minutes. After static sedimentation and solid-liquid separation, chromium in the water is removed; wherein the removal rate of chromium in the water is more than 99.86%.

[0025] Beneficial effects: Compared with the prior art, the present invention achieves the following significant effects:

[0026] (1) The iron-sulfur-based slurry of the present invention reduces the oxidation of ferrous iron by complexing it with organic matter, thereby dispersing ferrous iron and promoting the growth and dispersion of FeS. At the same time, the presence of organic matter changes the amount of charge on the surface of nano-FeS particles, enhancing the spatial resistance and electrostatic repulsion in the suspension system, thereby improving the dispersibility of FeS and preventing agglomeration during the formation of FeS. Furthermore, the combined use of organic matter and flocculant allows most of the ferrous iron to form FeS particles through in-situ reaction and be encapsulated by macromolecules, improving the antioxidant properties of FeS particles. (2) The iron-sulfur-based slurry of the present invention can be stored for a long time, up to one month at room temperature. (2) It can meet the transportation and storage requirements in actual application; (3) Compared with existing iron-sulfur-based materials, the iron-sulfur-based slurry of the present invention has good environmental adaptability and environmental compatibility; (4) The preparation method of the iron-sulfur-based slurry of the present invention is simple, the raw materials are readily available, the process is short, and it does not require complex synthesis equipment and harsh synthesis conditions, making it easy to operate; (5) When the iron-sulfur-based slurry of the present invention is used to treat water bodies polluted with heavy metals, it is easy to disperse quickly in water and the reaction speed is fast, with a chromium removal rate of over 99.86% in the water; (6) When treating water bodies polluted with heavy metals, the process is easy to control, the reaction products are stable, and there is no yellowing or re-release of pollutants. Attached Figure Description

[0027] Figure 1 The images show the pure ferrous sulfide nanoparticle suspension prepared in Comparative Example 1 and the stabilized reducing iron-sulfur based slurry prepared in Examples 1-3 after being sealed and stored at room temperature for 24 hours.

[0028] Figure 2 The image shows the stabilized reducing iron-sulfur based slurry prepared in Example 3 after being sealed and stored at room temperature for 30 days.

[0029] Figure 3 Scanning electron microscope (SEM) images of the FeS repair agent prepared in Comparative Example 1 and the stabilized reducing iron-sulfur-based slurry prepared in Example 1;

[0030] Figure 4 The graph shows the change in removal rate when the stabilized reducing iron-sulfur based slurry prepared in Example 1 is applied to remove a solution containing 40 mg / L hexavalent chromium. Detailed Implementation

[0031] The present invention will now be described in further detail.

[0032] Example 1

[0033] A stabilized reducing iron-sulfur-based slurry is an organic matter-coagulant-ferrous sulfide nanoparticle suspension. The slurry comprises the following components by mass percentage: organic matter: 0.5%, coagulant: 1%, and ferrous sulfide nanoparticles: 98.5%. The organic matter is humic acid (HA), and the coagulant is polyaluminum chloride (PAC). The preparation method of this slurry includes the following steps:

[0034] (1) Dissolve humic acid, polyaluminum chloride, ferrous sulfate, and sodium sulfide in water to prepare a humic acid solution with a mass percentage of 0.5%, a polyaluminum chloride solution with a mass percentage of 1%, a ferrous sulfate solution with a concentration of 5 mol / L, and a sodium sulfide solution with a concentration of 10 mol / L. Under anaerobic conditions at room temperature, mix the humic acid solution and the ferrous sulfate solution and stir at 500 rpm for 6 min to allow the ferrous ions to fully complex with the humic acid.

[0035] (2) Mix the polyaluminum chloride solution with the solution obtained in step (1) and stir at 400 rpm for 10 min to encapsulate the complex of ferrous ions and humic acid.

[0036] (3) Add sodium sulfide solution slowly to the solution obtained in step (2), stir at 500 rpm for 30 min, centrifuge the mixed solution at 4000 rpm and discard the supernatant to obtain organic matter-coagulant-ferrous sulfide nanoparticle suspension, which is the stabilized reducing iron-sulfur based slurry.

[0037] The volume ratio of humic acid solution: polyaluminum chloride solution: ferrous sulfate solution: sodium sulfide solution is 5:5:2:1.

[0038] The stabilized reducing iron-sulfur-based slurry prepared in Example 1 was applied to treat water containing heavy metal chromium. The specific steps were as follows:

[0039] The stabilized reducing iron-sulfur-based slurry prepared in Example 1 was added to water containing heavy metal chromium, with a volume ratio of approximately 100:1. The mixture was stirred at 300 rpm for 20 minutes to obtain the remediated water body. The concentration of hexavalent chromium in the water containing heavy metal chromium was 40 mg / L.

[0040] The results showed that after 20 minutes, the removal rate of active chromium in the water was 98.31%. Over the following 60 days, the total organic carbon content in the water was less than 4 mg / L, there was no yellowing of the water, the total chromium content was less than 0.56 mg / L, and the total iron content was less than 0.38 mg / L.

[0041] Example 2

[0042] A stabilized reducing iron-sulfur-based slurry is an organic matter-coagulant-ferrous sulfide nanoparticle suspension. The slurry comprises the following components by mass percentage: organic matter: 1%, coagulant: 2%, and ferrous sulfide nanoparticles: 97%. The organic matter is disodium ethylenediaminetetraacetate (EDTA·Na2), and the coagulant is polyferric sulfate (PFS). The preparation method of this slurry includes the following steps:

[0043] (1) Dissolve disodium ethylenediaminetetraacetate, polyferric sulfate, ferrous sulfate, and sodium sulfide in water to prepare a 1% (w / w) disodium ethylenediaminetetraacetate solution, a 2% (w / w) polyferric sulfate solution, an 8 mol / L ferrous sulfate solution, and a 12 mol / L sodium sulfide solution. Under anaerobic conditions at room temperature, mix the disodium ethylenediaminetetraacetate solution and the ferrous sulfate solution and stir at 300 rpm for 8 min to allow the ferrous ions to fully complex with the disodium ethylenediaminetetraacetate.

[0044] (2) Mix the polyferric sulfate solution with the solution obtained in step (1) and stir at 200 rpm for 5 min to encapsulate the complex of ferrous ions and disodium ethylenediaminetetraacetate.

[0045] (3) Add sodium sulfide solution slowly to the solution obtained in step (2), stir at 400 rpm for 20 min, centrifuge the mixed solution at 5000 rpm and discard the supernatant to obtain organic matter-coagulant-ferrous sulfide nanoparticle suspension, which is the stabilized reducing iron-sulfur based slurry.

[0046] The volume ratio of disodium ethylenediaminetetraacetate solution: polyferric sulfate solution: ferrous sulfate solution: sodium sulfide solution is 5:5:2:1.

[0047] The stabilized reducing iron-sulfur-based slurry prepared in Example 2 was applied to treat water containing heavy metal chromium. The specific steps are as follows:

[0048] The prepared water heavy metal removal material was added to water containing heavy metal chromium, with a volume ratio of approximately 150:1. The mixture was stirred at 300 rpm for 15 minutes to obtain the remediated water. The concentration of hexavalent chromium in the water containing heavy metal chromium was 50 mg / L.

[0049] The results showed that after 15 minutes, the removal rate of active chromium in the water was 95.94%. Over the following 60 days, the total organic carbon content in the water was less than 6 mg / L, there was no yellowing of the water, the total chromium content was less than 2.03 mg / L, and the total iron content was less than 0.40 mg / L.

[0050] Example 3

[0051] A stabilized reducing iron-sulfur-based slurry is an organic matter-coagulant-ferrous sulfide nanoparticle suspension. The slurry comprises the following components by mass percentage: organic matter: 2%, coagulant: 4%, and ferrous sulfide nanoparticles: 94%. The organic matter is hydroxymethylene phosphonate (HEDP), and the coagulant is polyacrylamide (PAM). The preparation method of this slurry includes the following steps:

[0052] (1) Dissolve hydroxymethylene phosphonate, polyacrylamide, ferrous sulfate, and sodium sulfide in water to prepare a 2% hydroxymethylene phosphonate solution, a 4% polyacrylamide solution, a 10 mol / L ferrous sulfate solution, and a 15 mol / L sodium sulfide solution. Under anaerobic conditions at room temperature, mix the hydroxymethylene phosphonate solution and the ferrous sulfate solution and stir at 200 rpm for 10 min to allow the ferrous ions to fully complex with the hydroxymethylene phosphonate.

[0053] (2) Mix the polyacrylamide solution with the solution obtained in step (1) and stir at 500 rpm for 10 min to encapsulate the complex of ferrous ions and hydroxymethylene phosphonate.

[0054] (3) Add sodium sulfide solution slowly to the solution obtained in step (2), stir at 500 rpm for 30 min, centrifuge the mixed solution at 4000 rpm and discard the supernatant to obtain an organic matter-coagulant-ferrous sulfide nanoparticle suspension, which is the stabilized reducing iron-sulfur based slurry; seal the above slurry and store it at room temperature for 1 month for later use.

[0055] The volume ratio of hydroxymethylene phosphonate solution: polyacrylamide solution: ferrous sulfate solution: sodium sulfide solution is 5:5:2:1.

[0056] The stabilized reducing iron-sulfur-based slurry prepared in Example 3 was applied to treat water containing heavy metal chromium. The specific steps are as follows:

[0057] The prepared stabilized reducing iron-sulfur slurry, which had been left to stand at room temperature for 30 days, was added to water containing heavy metal chromium, with a volume ratio of approximately 150:1. The mixture was stirred at 400 rpm for 15 minutes to obtain the remediated water body. The concentration of hexavalent chromium in the water containing heavy metal chromium was 60 mg / L.

[0058] The results showed that after 15 minutes, the removal rate of active chromium in the water was 98.73%. Over the following 60 days, the total organic carbon content in the water was less than 7 mg / L, there was no yellowing of the water, the total chromium content was less than 0.16 mg / L, and the total iron content was less than 0.45 mg / L.

[0059] The treatment effects of the iron-sulfur-based slurry of each embodiment on chromium-containing water are shown in Table 1 below. The water quality test and evaluation of the iron-sulfur-based slurry of each embodiment on chromium-containing water after two months (60 days) of treatment are shown in Table 2 below.

[0060] Table 1. Effects of iron-sulfur based slurries on chromium-containing water treatment in each embodiment.

[0061] Cr concentration before addition (mg / L) Cr concentration after addition (mg / L) Removal rate (%) Example 1 40.00 0.56 99.86 Example 2 50.00 2.03 95.94 Example 3 60.00 0.76 98.73

[0062] Table 2. Evaluation of water quality after two months of chromium-containing water treatment using iron-sulfur based slurries from various examples.

[0063] Total organic carbon (mg / L) Total chromium (mg / L) Total iron (mg / L) Example 1 <4 <0.56 <0.38 Example 2 <6 <2.03 <0.40 Example 3 <7 <0.76 <0.45

[0064] As shown in Table 2, the stabilized reducing iron-sulfur-based slurry of the present invention does not cause secondary pollution to water bodies, and the reaction products are stable, with the total chromium and total iron content remaining stable for a long time after remediation.

[0065] Comparative Example 1

[0066] Based on Example 1, the difference is that both humic acid and polyaluminum chloride were replaced with pure water; the volume ratio of ferrous sulfate solution to sodium sulfide solution was 2:1. Unmodified iron-sulfur based slurry was obtained.

[0067] The specific steps for applying unmodified iron-sulfur-based slurry to treat water bodies containing the heavy metal chromium are as follows:

[0068] The newly prepared stabilized reducing iron-sulfur-based slurry was added to water containing heavy metal chromium, with a volume ratio of approximately 100:1. The mixture was stirred at 300 rpm for 30 minutes to obtain the remediated water body. The concentration of hexavalent chromium in the water containing heavy metal chromium was 40 mg / L.

[0069] The results showed that after 30 minutes, the removal rate of active chromium in water was 62.31%. Unmodified iron-sulfur based slurry completely oxidized and deteriorated after being left at room temperature for 3 days.

[0070] like Figure 1 As shown, where, Figure 1 Figure a shows the sedimentation of the ferrous sulfide nanoparticle suspension prepared in Comparative Example 1 12 hours after preparation. Figure 1 Figures b, c, and d show the sedimentation of the stabilized reducing iron-sulfur-based slurries prepared in Examples 1, 2, and 3, respectively, 24 hours after preparation. Figure 1As shown in Figure a, the ferrous sulfide particle suspension prepared in Comparative Example 1 without the addition of organic matter and coagulant showed significant sedimentation and stratification after 24 hours. However, the ferrous sulfide particle suspension prepared with the addition of organic matter did not show significant sedimentation after 24 hours. Figure 1 As shown in b, c, and d.

[0071] The scanning electron microscope image of the ferrous sulfide particles obtained in Comparative Example 1 is shown below. Figure 3 As shown in Figure a, it can be seen that the ferrous sulfide particles prepared without the addition of organic matter and coagulant have uneven particle size. Compared with the ferrous sulfide particles prepared in Example 1 with an average particle size of 500±100nm, there is obvious agglomeration. Figure 3 As shown in b in the figure.

[0072] This invention investigated the stability of the iron-sulfur based slurries prepared in Examples 1-3. The results showed that the iron-sulfur based slurries of this invention can remain stable for at least one month under normal temperature and sealed conditions. Figure 2 The product image shows the iron-sulfur based slurry prepared in Example 1 after being stored in a sealed container at room temperature. This indicates that the organic matter has the effect of dispersing and stabilizing the ferrous sulfide suspension, and the coagulant has the effect of enhancing the antioxidant properties of the ferrous sulfide. However, the ferrous sulfide prepared in Comparative Example 1 agglomerated after 24 hours. Figure 1 As shown in Figure a, this demonstrates that the iron-sulfur based slurry of the present invention has a longer storage time compared to ordinary ferrous sulfide materials.

[0073] The iron-sulfur-based slurry of this invention, when applied to the remediation of water bodies contaminated with heavy metals, has the advantages of a short remediation cycle, good heavy metal removal effect, and a simple, mature, and easy-to-implement method. As can be seen from the results of Examples 1-3, the stabilized reducing iron-sulfur-based slurry of this invention can rapidly remove chromium with a removal rate of over 95%, and can avoid secondary pollution, possessing potential for widespread application and being economical and reliable.

[0074] Comparative Example 2

[0075] Based on Example 1, the difference is that polyaluminum chloride is replaced with pure water; the volume ratio of humic acid: ferrous sulfate solution: sodium sulfide solution is 5:2:1 to obtain an iron-sulfur based slurry.

[0076] This iron-sulfur-based slurry was applied to treat water containing chromium. The specific steps were as follows: the newly prepared stabilized reducing iron-sulfur-based slurry was added to water containing chromium at a volume ratio of approximately 100:1, and the mixture was stirred at 400 rpm for 50 minutes to obtain the remediated water. The concentration of hexavalent chromium in the water was 40 mg / L. The results showed that after 50 minutes, the removal rate of active chromium in the water was 71.16%.

[0077] Comparative Example 3

[0078] Based on Example 1, the difference is that humic acid is replaced with pure water; the volume ratio of polyaluminum chloride: ferrous sulfate solution: sodium sulfide solution is 5:2:1 to obtain an iron-sulfur based slurry.

[0079] This iron-sulfur-based slurry was applied to treat water containing chromium. The specific steps were as follows: the newly prepared stabilized reducing iron-sulfur-based slurry was added to water containing chromium at a volume ratio of approximately 100:1, and the mixture was stirred at 400 rpm for 40 minutes to obtain the treated water. The concentration of hexavalent chromium in the water was 45 mg / L. The results showed that after 50 minutes, the removal rate of active chromium in the water was 79.62%.

[0080] Comparative Example 4

[0081] Based on Example 2, the difference is that polyaluminum chloride is replaced with potassium aluminum alum (KAl(SO4)2·12H2O); the volume ratio of humic acid: potassium aluminum alum: ferrous sulfate solution: sodium sulfide solution is 4:4:2:1, and an iron-sulfur based slurry is obtained.

[0082] This iron-sulfur-based slurry was applied to treat water containing chromium. The specific steps were as follows: the newly prepared stabilized reducing iron-sulfur-based slurry was added to water containing chromium at a volume ratio of approximately 150:1, and the mixture was stirred at 300 rpm for 40 minutes to obtain the remediated water. The concentration of hexavalent chromium in the water was 50 mg / L. The results showed that after 40 minutes, the removal rate of active chromium in the water was 65.33%.

[0083] Comparative Example 5

[0084] Based on Example 2, the difference is that the volume ratio of disodium ethylenediaminetetraacetate solution: polyferric sulfate solution: ferrous ammonium sulfate solution: sodium sulfide solution is 15:15:2:1.

[0085] This iron-sulfur-based slurry was applied to treat water containing chromium. The specific steps were as follows: the newly prepared stabilized reducing iron-sulfur-based slurry was added to water containing chromium at a volume ratio of approximately 150:1, and the mixture was stirred at 300 rpm for 60 minutes to obtain the remediated water. The concentration of hexavalent chromium in the water was 50 mg / L. The results showed that after 40 minutes, the removal rate of active chromium in the water was 85.75%.

[0086] Comparative Example 6

[0087] A method for preparing an iron-sulfur based slurry includes the following steps:

[0088] (1) Dissolve cellulose sulfonic acid, polyacrylamide, ferrous sulfate and sodium sulfide in water to prepare a 2% cellulose sulfonic acid solution, a 2% polyacrylamide solution, an 8 mol / L ferrous sulfate solution and a 12 mol / L sodium sulfide solution; mix the cellulose sulfonic acid solution and the ferrous sulfate solution at room temperature and under anaerobic conditions and stir at 400 rpm for 15 min.

[0089] (2) Mix the polyacrylamide solution with the solution obtained in step (1) and stir at 400 rpm for 10 min;

[0090] (3) Add sodium sulfide solution slowly to the solution obtained in step (2), stir at 400 rpm for 15 min, centrifuge the mixed solution at 5000 rpm and discard the supernatant to obtain organic matter-coagulant-ferrous sulfide nanoparticle suspension, which is the reducing iron-sulfur based slurry.

[0091] The volume ratio of cellulose sulfonic acid solution: polyacrylamide solution: ferrous sulfate solution: sodium sulfide solution is 10:10:2:1.

[0092] The reducing iron-sulfur-based slurry prepared in Comparative Example 6 was applied to treat water containing chromium. The specific steps were as follows: the prepared water heavy metal removal material was added to the chromium-containing water at a volume ratio of approximately 150:1, and the mixture was stirred at 300 rpm for 60 min to obtain the remediated water. The concentration of hexavalent chromium in the chromium-containing water was 40 mg / L. The results showed that after 15 min, the removal rate of active chromium in the water was 63.55%.

Claims

1. A stabilized reducing iron-sulfur based slurry, characterized in that, The slurry is an organic matter-coagulant-ferrous sulfide nanoparticle suspension; the slurry comprises the following components by mass percentage concentration: Organic matter: 0.5-5%, coagulant: 1-10%, ferrous sulfide nanoparticles: balance; The coagulant is at least one of polyferric sulfate, polyaluminum chloride, polyacrylamide, or dicyandiamide resin organic coagulant. The method for preparing the stabilized reducing iron-sulfur based slurry includes the following steps: (1) Mix the organic matter solution with the ferrous sulfate solution and stir to fully complex the ferrous ions with the organic matter; (2) Mix the coagulant solution with the solution obtained in step (1) and stir to encapsulate the complex of ferrous ions and organic matter; The volume ratio of the organic matter solution, coagulant, ferrous sulfate solution and sodium sulfide solution is 5:5:2:1-3:3:2:1; (3) Add sodium sulfide solution slowly to the mixed solution obtained in step (2), stir, so that ferrous sulfide nanoparticles are formed in the mixed solution, then centrifuge, discard the supernatant, and obtain organic matter-coagulant-ferrous sulfide nanoparticle suspension.

2. The stabilized reducing iron-sulfur based slurry according to claim 1, characterized in that, The organic matter is at least one of humic acid, disodium ethylenediaminetetraacetate, aminotrimethylene phosphonate, ethylenediaminetetraacetate, or hydroxymethylene phosphonate.

3. The stabilized reducing iron-sulfur based slurry according to claim 1, characterized in that, The ferrous sulfide nanoparticles have a particle size of 500-1000 nm.

4. A method for preparing the stabilized reducing iron-sulfur based slurry according to claim 1, characterized in that, Includes the following steps: (1) Mix the organic matter solution with the ferrous sulfate solution and stir to fully complex the ferrous ions with the organic matter; (2) Mix the coagulant solution with the solution obtained in step (1) and stir to encapsulate the complex of ferrous ions and organic matter; The volume ratio of the organic matter solution, coagulant, ferrous sulfate solution and sodium sulfide solution is 5:5:2:1-3:3:2:1; (3) Add sodium sulfide solution slowly to the mixed solution obtained in step (2), stir, so that ferrous sulfide nanoparticles are formed in the mixed solution, then centrifuge, discard the supernatant, and obtain organic matter-coagulant-ferrous sulfide nanoparticle suspension.

5. The method for preparing the stabilized reducing iron-sulfur based slurry according to claim 4, characterized in that, The ferrous sulfide content in the organic matter-coagulant-ferrous sulfide nanoparticle suspension obtained in step (3) is not higher than 80 g / L and not lower than 40 g / L.

6. The method for preparing the stabilized reducing iron-sulfur based slurry material according to claim 4, characterized in that, In step (1), the added organic matter solution has a mass percentage concentration of 0.5-5%, and the added ferrous sulfate solution has a mass percentage concentration of 5-15 mol / L.

7. The method for preparing the stabilized reducing iron-sulfur based slurry material according to claim 4, characterized in that, In step (2), the mass percentage concentration of the coagulant solution is 1-10%.

8. The method for preparing the stabilized reducing iron-sulfur based slurry material according to claim 4, characterized in that, In step (3), the molar concentration of the added sodium sulfide solution is 5-20 mol / L.

9. The application of the stabilized reducing iron-sulfur based slurry of claim 1 in the removal of heavy metals from water.

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