Ferrihydrite-spent grain solid powder material as well as preparation method and application thereof

Abstract

The invention provides a ferrihydrite-spent grain solid powder material as well as a preparation method and application thereof, and relates to the technical field of removal of arsenic and antimony in a water body. The preparation method comprises the following steps: respectively providing spent grain powder leachate and an iron nitrate nonahydrate solution; dropwise adding the spent grain powder leachate into the iron nitrate nonahydrate solution until the pH value of the obtained mixed solution is 7.2-7.5; wherein the dropwise adding speed is 50mL / h; and carrying out centrifugal treatment, cooling treatment and freeze drying treatment on the mixed solution. The preparation method is simple and easy to operate, the material can be prepared in quantity, and quantitative production is realized. The material can be used for reducing the content of arsenic and antimony in a water body by constructing a barrier zone at the upstream of the water body. According to the barrier belt, the concentration of arsenic and antimony in the water body is remarkably reduced, and water resources and the ecological environment are protected. Complex equipment and operation procedures are not needed, and when the material reaches adsorption saturation, the material is easy to replace, convenient to maintain and manage and wide in application range.

Description

Technical Field

[0001] The present invention relates to the technical field of removing arsenic and antimony from water bodies, and particularly relates to a ferrihydrite-brewers' grains solid powder material, a preparation method and an application thereof. Background Art

[0002] At present, due to the discharge of a large amount of wastewater containing heavy metal ions such as arsenic and antimony during the production processes of industries such as metal manufacturing, electronics, electroplating, chemistry, iron and steel, and non-ferrous metal smelting, the surrounding farmland soil has been seriously polluted, and the survival of animals and plants has been seriously affected. Therefore, the removal of arsenic and antimony pollutants is a very necessary measure at present.

[0003] In the prior art, for arsenic and antimony sewage, the removal methods adopted are: precipitation method, ion exchange method, adsorption method, biological method, membrane separation method, etc. The adsorption method is one of the most important remediation technologies for heavy metal sewage due to its advantages such as quick effect, simple operation, high flexibility, environmental friendliness, less secondary pollution, good economy and sustainability, and is suitable for solving the problem of arsenic and antimony pollution in water bodies. Due to the small particle size, huge specific surface area and high surface activity of ferrihydrite, it usually interacts with arsenic through adsorption and coprecipitation to achieve the fixation of arsenic. At the same time, ferrihydrite is used to adsorb antimony.

[0004] However, in the actual application process, ferrihydrite is easy to transform and agglomerate, which limits its large-scale application. Especially, it is difficult to be widely applied to the removal of arsenic and antimony in water bodies. Summary of the Invention

[0005] The main object of the present invention is to provide a ferrihydrite-brewers' grains solid powder material, a preparation method and an application thereof, aiming to solve the problems in the prior art that the effect of using ferrihydrite to adsorb arsenic and antimony is unstable and it is difficult to be widely applied.

[0006] To achieve the above object, the present invention provides a preparation method of a ferrihydrite-brewers' grains solid powder material, including the steps of:

[0007] Respectively providing a leaching solution of brewers' grains powder and a ferric nitrate nonahydrate solution; the leaching solution of brewers' grains powder includes hydroxyl groups, carboxyl groups, amino groups, silicon element, phosphorus element, sulfur element, calcium element and magnesium element; dropping the leaching solution of brewers' grains powder into the ferric nitrate nonahydrate solution until the pH of the obtained mixed solution is 7.2 - 7.5; wherein, the dropping speed is 50 mL / h; performing centrifugation on the mixed solution, and sequentially performing a temperature reduction treatment at -80°C and a freeze-drying treatment on the obtained solid phase to obtain the ferrihydrite-brewers' grains solid powder material.

[0008] Further, the obtaining method of the leaching solution of brewers' grains powder includes the steps of:

[0009] The spent grains are subjected to drying treatment and crushing treatment in sequence, and then sieved through a 100-mesh sieve to obtain spent grain powder; the spent grain powder is mixed into a 0.1 mol / L calcium hydroxide solution, and subjected to a water bath heating treatment at 100 °C for 1 h to obtain a spent grain powder mixture; after the spent grain powder mixture is cooled to 20 - 30 °C, solid-liquid separation treatment is carried out to obtain the spent grain powder leaching solution.

[0010] Further, the temperature of the drying treatment is 60 °C.

[0011] Further, the method of the solid-liquid separation treatment is to centrifuge the spent grain powder mixture cooled to room temperature at 3000 rPm for 5 min to obtain the spent grain powder leaching solution.

[0012] Further, the mass ratio of ferric nitrate nonahydrate in the ferric nitrate nonahydrate solution, the spent grain powder and calcium hydroxide in the calcium hydroxide solution is 4:3:1 - 2.

[0013] Further, the method of the centrifugation treatment is to centrifuge the mixture at 10000 rPm for 5 min to obtain the solid phase.

[0014] Further, the temperature of the freeze-drying treatment is -100 °C.

[0015] The present invention also provides a ferrihydrite-spent grain solid powder material prepared by the preparation method described in any one of the above.

[0016] The present invention also provides an application of the ferrihydrite-spent grain solid powder material as described above in reducing the contents of arsenic and antimony in water. A barrier zone is constructed upstream of the water body, and the height of the barrier zone is higher than the water flow height of the water body.

[0017] The barrier zone is divided into 5 parts, and the components of each part are, in the water flow direction in sequence, 8 - 10 mesh quartz, 10 - 20 mesh zeolite, the ferrihydrite-spent grain solid powder material as described above, 10 - 20 mesh zeolite and 8 - 10 mesh quartz.

[0018] Further, the length ratio of the 5 parts of the barrier zone is 6:8:6:8:6.

[0019] The beneficial effects achieved by the present invention:

[0020] By simply mixing the spent grain leaching solution and the ferric nitrate nonahydrate solution at a dropping rate of 50 mL / h, and combining centrifugation treatment, cooling treatment and freeze-drying treatment, the present invention can prepare a ferrihydrite-spent grain solid powder material. The preparation method is simple and easy to operate, and can produce a large amount of ferrihydrite-spent grain solid powder materials for quantitative production.

[0021] The ferrihydrite - wheat bran solid powder material provided by the present invention can be applied to reduce the arsenic and antimony contents in water by constructing a barrier zone in the upper reaches of the water body. The barrier zone constructed with the ferrihydrite - wheat bran solid powder material has an adsorption capacity for arsenic and antimony in water as high as 211 mg / g and 235 mg / g respectively, significantly reducing the concentrations of arsenic and antimony in the water body and protecting water resources and the ecological environment. Moreover, the application method is simple, without the need for complex equipment and operation processes. When the ferrihydrite - wheat bran solid powder material reaches adsorption saturation, it is easy to replace, facilitating maintenance and management, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0023] Figure 1 It is the scanning electron microscope (SEM) image of wheat bran in Example 1; wherein, Figure 1 (a) is the SEM image magnified 10,000 times; Figure 1 (b) is the SEM image magnified 5,000 times; Figure 1 (c) is the SEM image magnified 3,000 times;

[0024] Figure 2 It is the scanning electron microscope (SEM) image of the ferrihydrite - wheat bran solid powder material in Example 1; wherein, Figure 2 (a) is the SEM image magnified 370 times; Figure 2 (b) is the SEM image magnified 1,000 times;

[0025] Figure 2 (c) is the SEM image magnified 5,000 times; Figure 2 (d) is the SEM image of different regions magnified 1,000 times; Figure 2 (e) is the SEM image magnified 500 times; Figure 2 (f) is the SEM image magnified 170 times;

[0026] Figure 3 It is the comparison chart of the adsorption capacities of the ferrihydrite - wheat bran solid powder material for arsenic and antimony in Example 2; wherein, Figure 3 (a) is the comparison chart of the adsorption capacities of different dosages for As(V); Figure 3 (b) is the comparison chart of the adsorption capacities of different dosages for Sb(V);

[0027] Figure 4SEM images of ferrihydrite in Comparative Example 1; among them, Figure 4 (a) SEM image magnified 2000 times; Figure 4 (b) SEM image magnified 400 times; Figure 4 (c) SEM image magnified 5000 times; Figure 4 (d) SEM image magnified 1000 times;

[0028] Figure 5 Adsorption capacity comparison chart of arsenic and antimony by wheat bran, ferrihydrite, and ferrihydrite - wheat bran solid powder materials in Comparative Example 1; among them, Figure 5 (a) Adsorption capacity comparison chart of As(V) by wheat bran, ferrihydrite, and ferrihydrite - wheat bran solid powder materials; Figure 5 (b) Adsorption capacity comparison chart of Sb(V) by wheat bran, ferrihydrite, and ferrihydrite - wheat bran solid powder materials;

[0029] Figure 6 Schematic diagram of the barrier zone model in Example 3;

[0030] Figure 7 Treatment effect comparison chart of arsenic and antimony by barrier zones with different support materials in Example 3; Figure 7 (a) Removal rate comparison chart of antimony by barrier zones with different support materials; Figure 7 (b) Removal rate comparison chart of arsenic by barrier zones with different support materials;

[0031] Figure 8 Influence comparison chart of pH on the treatment effect of arsenic and antimony by the barrier zone in Example 5; among them, Figure 8 (a) Arsenic concentration comparison chart at different pH values; Figure 8 (b) Arsenic removal rate comparison chart at different pH values;

[0032] Figure 8 (c) Antimony concentration comparison chart at different pH values; Figure 8 (d) Antimony removal rate comparison chart at different pH values;

[0033] Figure 9 Influence comparison chart of influent flow rate on the treatment effect of arsenic and antimony by the barrier zone in Example 5; among them, Figure 9 (a) Arsenic concentration comparison chart at different influent flow rates; Figure 9 (b) Antimony concentration comparison chart at different influent flow rates; Figure 9 (c) Arsenic removal rate comparison chart at different influent flow rates; Figure 9 (d) Antimony removal rate comparison chart at different influent flow rates;

[0034] Figure 10It is the comparison chart of the influence of the influent pollutant concentration on the effects of arsenic and antimony treatment by the barrier belt in Example 5; among them, Figure 10 (a) is the arsenic concentration comparison chart of different influent pollution concentrations; Figure 10 (b) is the antimony concentration comparison chart of different influent pollution concentrations; Figure 10 (c) is the arsenic removal rate comparison chart of different influent pollution concentrations; Figure 10 (d) is the antimony removal rate comparison chart of different influent pollution concentrations;

[0035] Figure 11 It is the schematic diagram of the barrier belt and each sampling point model in Example 6;

[0036] Figure 12 It is the actual photo of the construction of the barrier belt at the waste rock dump site in Example 7;

[0037] Figure 13 It is the comparison chart of arsenic and antimony barrier data in the sewage at the waste rock dump site in Example 7; among them, Figure 13 (a) is the comparison chart of influent arsenic concentration and effluent arsenic concentration; Figure 13 (b) is the comparison chart of influent antimony concentration and effluent antimony concentration; Figure 13 (c) is the comparison chart of arsenic and antimony removal rates;

[0038] Figure 14 It is the actual photo of the construction of the barrier belt at the hillside site in Example 8;

[0039] Figure 15 It is the comparison chart of leachate barrier data at the hillside site in Example 8; among them, Figure 15 (a) is the comparison chart of influent arsenic concentration and effluent arsenic concentration; Figure 15 (b) is the comparison chart of influent antimony concentration and effluent antimony concentration; Figure 15 (c) is the comparison chart of arsenic and antimony removal rates;

[0040] Figure 16 It is the actual photo of the construction of the barrier belt at the rainfall simulation hardened cement ground site in Example 9;

[0041] Figure 17 It is the influence of pH on the removal of arsenic and antimony in the rainfall simulation experiment in Example 9; among them, Figure 17 (a) is the comparison chart of influent arsenic concentration under different pH conditions during rainfall; Figure 17 (b) is the comparison chart of effluent arsenic concentration under different pH conditions during rainfall; Figure 17 (c) is the comparison chart of influent antimony concentration under different pH conditions during rainfall; Figure 17 (d) is the comparison chart of effluent antimony concentration under different pH conditions during rainfall; Figure 17 (e) is the comparison chart of arsenic removal rates under different pH conditions during rainfall; Figure 17(f) is a comparison chart of antimony removal rates under different pH conditions during rainfall;

[0042] Figure 18 It is the influence of rainfall intensity on the removal of arsenic and antimony in the rainfall simulation experiment in Example 9; among them, Figure 18 (a) is a comparison chart of influent arsenic concentrations under different rainfall intensity conditions when pH is 5; Figure 18 (b) is a comparison chart of effluent arsenic concentrations under different rainfall intensity conditions when pH is 5; Figure 18 (c) is a comparison chart of influent antimony concentrations under different rainfall intensity conditions when pH is 5; Figure 18 (d) is a comparison chart of effluent antimony concentrations under different rainfall intensity conditions when pH is 5; Figure 18 (e) is a comparison chart of arsenic removal rates under different rainfall intensity conditions when pH is 5; Figure 18 (f) is a comparison chart of antimony removal rates under different rainfall intensity conditions when pH is 5.

[0043] The realization, functional features and advantages of the object of the present invention will be further described with reference to the accompanying drawings in combination with the embodiments. Specific Embodiments

[0044] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the protection scope of the present invention.

[0045] It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other. It should also be understood that the terms used in the embodiments of the present invention are for the purpose of describing specific specific implementation manners, rather than for limiting the protection scope of the present invention.

[0046] Unless otherwise defined, all technical and scientific terms used in the present invention are the same as those understood by those skilled in the art of the present technology for the prior art and the description of the present invention. Any methods, devices and materials similar or equivalent to the methods, devices and materials described in the embodiments of the present invention can also be used to implement the present invention. When the embodiments give a numerical range, it should be understood that, unless otherwise stated in the present invention, any numerical value between the two endpoints of each numerical range and any one of the two endpoints can be selected. The test methods without specific conditions mentioned in the following embodiments are usually carried out under conventional conditions or according to the conditions recommended by each manufacturer. The materials or reagents required in the following embodiments are commercially available unless otherwise specified.

[0047] In order to solve the problems in the prior art that the effect of using ferrihydrite to adsorb arsenic and antimony is unstable and it is difficult to be applied on a large scale, the present invention provides a preparation method of a ferrihydrite-brewer's grains solid powder material, which includes the steps:

[0048] Provide a brewer's grains powder leaching solution and a ferric nitrate nonahydrate solution respectively; the brewer's grains powder leaching solution includes hydroxyl groups, carboxyl groups, amino groups, silicon element, phosphorus element, sulfur element, calcium element and magnesium element; drop the brewer's grains powder leaching solution into the ferric nitrate nonahydrate solution until the pH of the obtained mixed solution is 7.2-7.5; wherein, the dropping speed is 50 mL / h; perform centrifugation on the mixed solution, and perform a temperature reduction treatment at -80°C and a freeze-drying treatment on the obtained solid phase in sequence to obtain the ferrihydrite-brewer's grains solid powder material.

[0049] Specifically, place the brewer's grains powder leaching solution (including hydroxyl groups, carboxyl groups, amino groups, silicon element, phosphorus element, sulfur element, calcium element, magnesium element and organic matters, etc.) in an injection pump, and drop it into the ferric nitrate nonahydrate solution at a speed of 50 mL / h, and set a magnetic stirring at 300 rPm. At the same time, insert a pH meter into the solution for measurement until the pH remains at 7.2-7.5, and then turn off the injection pump. Ferrihydrite is synthesized during the mixing process of the brewer's grains powder leaching solution and the ferric nitrate nonahydrate solution; the brewer's grains powder leaching solution can also be used as a surface modifier to inhibit the aggregation of ferrihydrite, and the silicon element and phosphorus element therein can inhibit the transformation of ferrihydrite. Even when it is subsequently applied to reduce the arsenic and antimony content in water, it can play an important role. Perform centrifugation on the mixed solution, place it in a refrigerator at a temperature of -80°C for a temperature reduction treatment for 24 h, and perform a freeze-drying treatment to obtain the ferrihydrite-brewer's grains solid powder material.

[0050] The present invention can obtain the ferrihydrite-brewer's grains solid powder material by simply mixing the brewer's grains leaching solution and the ferric nitrate nonahydrate solution at a dropping speed of 50 mL / h, and combining centrifugation, temperature reduction treatment and freeze-drying treatment. This preparation method is simple and easy to operate, and can obtain a large amount of ferrihydrite-brewer's grains solid powder materials for quantitative production.

[0051] Further, the obtaining method of the brewer's grains powder leaching solution includes the steps:

[0052] The spent grains are subjected to drying treatment and crushing treatment in sequence, and then passed through a 100-mesh sieve to obtain spent grain powder. The spent grain powder is mixed into a 0.1 mol / L calcium hydroxide solution, and subjected to a water bath heating treatment at 100 °C for 1 h to obtain a spent grain powder mixture solution. After the spent grain powder mixture solution is cooled to 20 - 30 °C, solid-liquid separation treatment is carried out to obtain a spent grain powder leachate. Specifically, fresh spent grains are dried in an oven, and the spent grains are initially treated (the first crushing treatment) using a crusher and passed through a 60-mesh sieve. Subsequently, the initially treated spent grains are subjected to ball milling treatment (the second crushing treatment) and passed through a 100-mesh sieve to obtain spent grain powder. Calcium hydroxide is dissolved in water, and then the obtained spent grain powder is added to the calcium hydroxide solution and magnetically stirred for 1 h; and the spent grain - calcium hydroxide mixture is heated and stirred in a 100 °C water bath for 1 h to obtain a spent grain powder mixture solution. Through two crushing treatments, alkali addition, and water bath heating treatment, the activity of the effective components in the spent grains can be improved, their particle size can be reduced, and they can be broken into an amorphous structure. At the same time, the hydroxyl, carboxyl, and amino components in the product are increased, promoting the dissolution of the effective components.

[0053] Further, the temperature of the drying treatment is 60 °C.

[0054] Further, the method of solid-liquid separation is to centrifuge the spent grain powder mixture solution cooled to room temperature at 3000 rPm for 5 min to obtain a spent grain powder leachate. Specifically, the spent grain powder mixture solution cooled to room temperature is placed in a centrifuge and centrifuged at 3000 rPm for 5 min, and the supernatant is taken as the spent grain powder leachate.

[0055] Further, the mass ratio of ferric nitrate nonahydrate in the ferric nitrate nonahydrate solution, the spent grain powder, and calcium hydroxide in the calcium hydroxide solution is 4:3:1 - 2. Preferably, the mass ratio of ferric nitrate nonahydrate:spent grain powder:calcium hydroxide is 4:3:1.4 - 1.5. Under this mass ratio, the adsorption performance of the ferrihydrite-spent grain solid powder material prepared for arsenic and antimony in water is the best. In an optional embodiment, the mass ratio is 4:3:1.48.

[0056] Further, the method of centrifugation is to centrifuge the mixed solution at 10000 rPm for 5 min to obtain a solid phase.

[0057] Further, the temperature of the freeze-drying treatment is -100 °C. Specifically, the solid material after the temperature reduction treatment is placed in a freeze dryer and freeze-dried at -100 °C.

[0058] The present invention also provides a ferrihydrite-spent grain solid powder material prepared by the preparation method of any one of the above.

[0059] The ferrihydrite-brewers' grains solid powder material provided by the present invention can be applied to reduce the arsenic and antimony contents in water by constructing a barrier zone in the upper reaches of the water body. Specifically, the iron hydroxides in the ferrihydrite-brewers' grains solid powder material are protonated, and through electrostatic attraction, ion exchange, outer-sphere complexation, coprecipitation, and inner-sphere complexation with arsenic and antimony in the water body, the arsenic and antimony contents in the water body are reduced. In the ferrihydrite-brewers' grains solid powder material, part of the ferrihydrite is an amorphous or weakly crystalline iron oxyhydroxide (FeOOH·nH2O), which has a high specific surface area and abundant surface hydroxyl groups (-OH). Under acidic or neutral conditions, the hydroxyl groups are protonated to form a positively charged surface (-OH2 + ), enhancing the electrostatic adsorption capacity for As / Sb anions (such as AsO4 3- , Sb(OH) 6- ); while for the brewers' grains part, as a biomass carrier, its porous structure increases the specific surface area of the ferrihydrite-brewers' grains solid powder material. At the same time, it contains organic functional groups (-COOH, -OH) such as cellulose and lignin, which can assist in adsorption through complexation, and prevent particle agglomeration through electrostatic repulsion or steric hindrance, promoting the dispersion of ferrihydrite in the ferrihydrite-brewers' grains solid powder material.

[0060] When the ferrihydrite-brewers' grains solid powder material acts on the water body, the removal of arsenic and antimony in the water body is achieved through the mechanisms of electrostatic attraction, ion exchange, surface complexation, and coprecipitation with arsenic and antimony in the water body. Among them, (1) Electrostatic attraction: The protonated surface (-OH2 + ) combines with As / Sb anions (such as H2AsO 4- , Sb(OH) 6- ) through Coulomb force, especially effective at pH 3 - 7; (2) Ion exchange: The surface hydroxyl groups (-OH - ) on the ferrihydrite are replaced by As / Sb anions. For example:

[0061] Fe-OH + H2AsO 4- →Fe-AsO4 2- + H2O + H+Fe-OH + H2AsO 4- →Fe-AsO4 2- + H2O + H + ; (3)

[0062] Surface complexation: Outer-sphere complexation: As / Sb is adsorbed on the surface through hydrogen bonds or weak coordination, and is easily affected by ionic strength: Inner-sphere complexation: As / Sb directly forms a covalent bond with Fe 3+ (such as Fe-O-As bond), with a stable structure and strong anti-interference ability; (4) Coprecipitation: As / Sb is encapsulated into the amorphous structure during the formation of ferrihydrite, or combines with Fe 3+Generate secondary minerals (such as iron arsenate) to achieve permanent fixation.

[0063] The chemical structures of ferrihydrite (FH) and ferrihydrite - spent grains solid powder material (FH - SG) were respectively confirmed by Fourier transform infrared (FTIR) spectroscopy. It can be seen from the FTIR spectra of both that FH - SG has richer active functional groups (including hydroxyl groups, carboxyl groups, etc.) than FH. It may be that the organic molecules dissolved from the spent grains are adsorbed on the surface of the ferrihydrite part in FH - SG, so that the ferrihydrite part is wrapped by negatively charged organic molecules; it is this protective organic molecular layer that inhibits the particle growth of the ferrihydrite part and prevents particle aggregation through electrostatic repulsion or steric hindrance.

[0064] The present invention also provides an application of the ferrihydrite - spent grains solid powder material as above in reducing the contents of arsenic and antimony in water bodies. A barrier zone is constructed upstream of the water body, and the height of the barrier zone is higher than the water flow height of the water body. Specifically, the height of the set barrier zone is higher than the height of the wastewater to ensure that the wastewater containing arsenic and antimony can all pass through the barrier zone. Preferably, the inlet pH of the barrier zone is adjusted to ≤7. Preferably, the inlet water flow rate of the barrier zone is controlled to be 0.5 m / d. Preferably, before the water body reaches the barrier zone, the water body is pretreated so that the initial concentrations of arsenic and antimony in the water body are both 0.5 mg / L.

[0065] The barrier zone is divided into 5 parts, and the components of each part are in turn 8 - 10 mesh quartz, 10 - 20 mesh zeolite, the ferrihydrite - spent grains solid powder material as above, 10 - 20 mesh zeolite, and 8 - 10 mesh quartz along the water flow direction.

[0066] Specifically, in the ditch where arsenic- and antimony-containing wastewater is discharged, the above-mentioned barrier zone mainly adsorbed by ferrihydrite-brewer's grains solid powder material can be constructed. Before and after the barrier zone, a sieve mesh is used for fixation to prevent the sewage from being washed away. Among them, the quartz part serves as the outermost buffer layer, which can protect the core filler, extend the column life, intercept particulate matters and impurities in the influent water, prevent pollution or blockage; relieve the impact of sudden change in the flow rate of the mobile phase on the filler, and avoid filler collapse or channeling. The zeolite part has structural support and stability to prevent the collapse or channeling of the ferrihydrite-brewer's grains solid powder material part; it can act as a filter layer and prevent the ferrihydrite-brewer's grains solid powder material from flowing out with the leaching solution; through its large pore structure, it helps the water flow to be evenly distributed across the entire cross-section of the soil column, avoiding the phenomenon of "preferential flow" (i.e., the water flow concentrates through local channels); it can also control the water flow rate and play an auxiliary barrier role during the adsorption process of antimony and arsenic. The ferrihydrite-brewer's grains solid powder material part plays a major barrier role in each structure of the barrier zone, and the adsorption contribution rates to antimony and arsenic both exceed 70%. The five parts of the barrier zone composed of quartz, zeolite, and ferrihydrite-brewer's grains solid powder material act synergistically to minimize the arsenic and antimony content in the water body.

[0067] Preferably, before constructing the barrier zone, the surrounding of the drainage ditch is also hardened with cement to further stabilize the barrier zone.

[0068] The barrier zone constructed with the ferrihydrite-brewer's grains solid powder material has an adsorption capacity for arsenic and antimony in the water body as high as 211 mg / g and 235 mg / g respectively, significantly reducing the concentrations of arsenic and antimony in the water body and protecting water resources and the ecological environment. Moreover, this application method is simple, does not require complex equipment and operation processes, and is easy to replace when the ferrihydrite-brewer's grains solid powder material reaches adsorption saturation, facilitating maintenance and management, and has a wide application range.

[0069] Furthermore, the length ratio of the five parts of the barrier zone is 6:8:6:8:6. Specifically, according to the actual operation, when the length ratio of the five parts of the barrier zone is 6:8:6:8:6, the adsorption effect on arsenic and antimony in the water body is the best.

[0070] For a further understanding of the present invention, the following is an example for illustration:

[0071] Example 1

[0072] Preparation of ferrihydrite-brewer's grains solid powder material

[0073] The fresh brewer's grains are dried in an oven at 60 °C, and the brewer's grains are initially processed with a crusher and sieved through a 60-mesh sieve. The brewer's grains are characterized and analyzed, and its scanning electron microscope (SEM) image is as Figure 1 shown; among them, Figure 1(a) is a SEM image of spent grains at 10,000 times magnification; Figure 1 (b) is a SEM image of the spent grains at 5000 times magnification; Figure 1 (c) is a SEM image of the spent grains magnified 3000 times. Figure 1 As can be seen from the figure, the spent grains are mainly blocky in structure. In the subsequent steps, a series of treatments are required to dissolve the biomass inside the spent grains and destroy their crystalline structure into an amorphous structure in order to synthesize ferrihydrite-spent grains solid powder material.

[0074] The spent grains after the initial treatment were then crushed in a ball mill and passed through a 100-mesh sieve to obtain spent grain powder. The spent grain powder was then placed in a 0.1 mol / L calcium hydroxide solution (calcium hydroxide dissolved in water), magnetically stirred at 300 rpm for 2 hours, and then heated in a water bath at 100°C for 1 hour. After the spent grain powder mixture cooled to room temperature, it was centrifuged at 3000 rpm for 5 minutes. The supernatant (spent grain powder extract) was collected and placed in a 50 mL syringe and placed on a syringe pump.

[0075] Ferric nitrate nonahydrate was dissolved in deionized water. The spent grains powder leachate was dripped into the ferric nitrate nonahydrate solution at a rate of 50 mL / h using a syringe pump. A magnetic stirrer was set at 300 rpm (the mass ratio of ferric nitrate nonahydrate: spent grains powder: calcium hydroxide was 4:3:1.48). A pH meter was inserted into the solution and measured until the pH remained between 7.2 and 7.5. The syringe pump was then shut off. The resulting mixture was centrifuged at 10,000 rpm for 5 minutes. The precipitate was then cooled in a -80°C refrigerator for 24 hours. Finally, the mixture was freeze-dried in a -100°C freezer to produce the ferrihydrite-spent grains solid powder.

[0076] The obtained ferrihydrite-spent grains solid powder material was characterized and analyzed, and the scanning electron microscope (SEM) image thereof is shown in FIG. Figure 2 shown; among them, Figure 2 (a) is a SEM image magnified 370 times; Figure 2 (b) is a SEM image magnified 1000 times; Figure 2 (c) is a SEM image magnified 5000 times; Figure 2 (d) SEM images of different areas at 1000 times magnification; Figure 2 (e) is a SEM image magnified 500 times; Figure 2 (f) is a SEM image magnified 170 times. Figure 2It can be seen that for the ferrihydrite-brewer's grains solid powder material, the agglomeration of ferrihydrite is reduced, making the ferrihydrite structure in it more porous, with many pores appearing on the surface, a richer surface active adsorption sites, and better adsorption performance. At the same time, it can be seen that flocs are generated around. At this time, the ferrihydrite-brewer's grains solid powder material may be an amorphous or weakly crystalline material, and the flocs generated around endow it with more surface defects, thus exposing more reaction interfaces, with rich surface active adsorption sites and better adsorption ability for heavy metals.

[0077] Example 2

[0078] The ferrihydrite-brewer's grains solid powder materials prepared in Example 1 with dosages of 0.1 g / L, 0.2 g / L, 0.4 g / L, 0.6 g / L, 0.8 g / L, and 1 g / L were respectively added into 100 mL of arsenic and antimony solutions (both with a concentration of 50 mg / L). The oscillation speed was 300 rpm, and samples were taken at t = 6 h. The results are as Figure 3 shown; among them, Figure 3 (a) is a comparison chart of the adsorption amounts of As(V) at different dosages; Figure 3 (b) is a comparison chart of the adsorption amounts of Sb(V) at different dosages.

[0079] The results show that when the dosage of the ferrihydrite-brewer's grains solid powder material is 0.1 g / L, the adsorption capacities for Sb(V) and As(V) are the highest, and the adsorption capacities for Sb(V) and As(V) are 77.95 mg / g and 99.08 mg / g respectively. When the dosage of the ferrihydrite-brewer's grains solid powder material is increased to 0.2 g / L, 0.4 g / L, 0.6 g / L, and 1 g / L, the adsorption capacities for Sb(V) are 53.025 mg / g, 19.1375 mg / g, 28.37 mg / g, 25.15125 mg / g, and 23.285 mg / g respectively, and the adsorption capacities for As(V) are 84.62 mg / g, 55.9175 mg / g, 41.72 mg / g, 32.1875 mg / g, and 24.81 mg / g respectively. It can be seen from this that the ferrihydrite-brewer's grains solid powder material exhibits excellent adsorption ability for antimony and arsenic, and the highest adsorption capacities for Sb(V) and As(V) are 77.95 mg / g and 99.08 mg / g respectively.

[0080] Comparative Example 1

[0081] The brewer's grains in Example 1, the ferrihydrite-brewer's grains solid powder material (FH-SG) prepared in Example 1, and ferrihydrite (FH) were all added into 100 mL of arsenic and antimony solutions (both with a concentration of 50 mg / L) at a dosage of 0.1 g / L, and the oscillation speed was 300 rpm.

[0082] Among them, the scanning electron microscope (SEM) image of this ferrihydrite is as follows Figure 4 shown; among them, Figure 4 (a) is the SEM image magnified 2000 times; Figure 4 (b) is the SEM image magnified 400 times; Figure 4 (c) is the SEM image magnified 5000 times; Figure 4 (d) is the SEM image magnified 1000 times. It can be seen from Figure 4 that the particle size and shape of this ferrihydrite are non-uniform, and the particles agglomerate together.

[0083] Samples were taken from the above-mentioned various materials at t = 6 h respectively, and the results are as follows Figure 5 shown; among them, Figure 5 (a) is the comparison chart of the adsorption amounts of brewer's grains, ferrihydrite (FH), and ferrihydrite-brewer's grains solid powder material (FH-SG) for As(V); Figure 5 (b) is the comparison chart of the adsorption amounts of brewer's grains, ferrihydrite (FH), and ferrihydrite-brewer's grains solid powder material (FH-SG) for Sb(V).

[0084] The results show that referring to Figure 5 (a), when the dosages of brewer's grains, ferrihydrite (FH), and ferrihydrite-brewer's grains solid powder material (FH-SG) are 0.1 g / L, the adsorption amounts for As(V) can reach 4.46 mg / g, 35.01 mg / g, and 99.08 mg / g respectively. Referring to Figure 5 (b), the adsorption amounts for Sb(V) can reach 10.03 mg / g, 56.53 mg / g, and 77.95 mg / g respectively.

[0085] Example 3

[0086] Determine the support material of the barrier zone

[0087] Quartz, attapulgite, and zeolite were selected as the three support materials, and they were divided into 3 groups. For each group, the support material was first added to the column respectively, then the ferrihydrite-brewer's grains solid powder material prepared in Example 1 was added, and finally the support material was added again. The filling heights were 14 cm for the support material, 6 cm for the ferrihydrite-brewer's grains solid powder material (FH-SG), and 14 cm for the support material. The schematic diagram of the barrier zone model is as follows Figure 6 shown.

[0088] Arsenic and antimony removal experiments were carried out using 3 groups of different barrier zones respectively, and the experimental results are as follows Figure 7 shown; among them, Figure 7 (a) is the comparison chart of the removal rates of 3 groups of different barrier zones for antimony; Figure 7 (b) is the comparison chart of the removal rates of 3 groups of different barrier zones for arsenic.

[0089] The results show that when the reaction time reaches 23 h, the removal rate begins to tend to be balanced. The removal rates of arsenic by quartz + FH-SG, attapulgite + FH-SG, and zeolite + FH-SG are 69.05%, 67.75%, and 90.95% respectively, and the removal rates of antimony by quartz + FH-SG, attapulgite + FH-SG, and zeolite + FH-SG are 21.8%, 20.1%, and 43.1% respectively. In the final stage, when the reaction time reaches the last period of 148 h, the removal rates of arsenic by quartz + FH-SG, attapulgite + FH-SG, and zeolite + FH-SG are 64.5%, 62.2%, and 71.85% respectively, and the removal rates of antimony by quartz + FH-SG, attapulgite + FH-SG, and zeolite + FH-SG are 17.3%, 17.1%, and 33.15% respectively. The data show the removal effects of the three materials on arsenic and antimony: zeolite + FH-SG > quartz + FH-SG > attapulgite + FH-SG. It is speculated that this is because zeolite has a larger specific surface area and exchange capacity. Therefore, zeolite will be selected as the supporting material for the barrier zone model in the subsequent experiments.

[0090] Example 4

[0091] On the basis of Example 3, the length of the supporting material (zeolite), the particle size of the supporting material (zeolite), and the length of FH-SG are determined, and an orthogonal experiment is carried out. The orthogonal experiment table is shown in Table 1; the orthogonal experiment results of arsenic and antimony corresponding to Table 1 are shown in Tables 2 and 3 respectively.

[0092] Table 1 Orthogonal experiment table

[0093]

[0094] Table 2 Orthogonal experiment results and analysis of arsenic

[0095]

[0096] Table 3 Orthogonal experiment results and analysis of antimony

[0097]

[0098]

[0099] The results show (as shown in Tables 2 and 3) that the experimental range: R1 > R2 > R3. Among the three influencing factors, the length of FH-SG has the greatest influence on the arsenic compliance barrier capacity, followed by the length of zeolite, and the influence of zeolite particle size is smaller. Therefore, the optimal barrier scheme for arsenic is FH-SG length 6 cm, zeolite length 8 cm, and zeolite particle size 40 - 80 mesh. The optimal barrier scheme for antimony is FH-SG length 6 cm, zeolite length 6 cm, and zeolite particle size 40 - 80 mesh.

[0100] Example 5

[0101] On the basis of Examples 3 and 4, an exploratory comparative experiment was conducted on the influent pH value corresponding to the barrier zone, the influent arsenic and antimony pollutant concentrations, and the influent flow rate.

[0102] Set up the barrier zone: From the inlet to the outlet of the column, quartz, zeolite, FH-SG material, zeolite, and quartz were filled in sequence.

[0103] The influent solution pH was set at 4, 5, 6, 7, and 8, with five treatments. The arsenic and antimony concentrations were set at 0.5 mg / L, 1 mg / L, 2 mg / L, 5 mg / L, and 10 mg / L, with five treatments. The influent flow rate was set at 0.5 m / d, 1 m / d, 1.5 m / d, 2 m / d, and 3 m / d, with five treatments.

[0104] The results of the exploratory comparative experiment on the influent pH value corresponding to the barrier zone, the influent arsenic and antimony pollutant concentrations, and the influent flow rate are shown respectively as Figure 8 、 Figure 9 、 Figure 10 shown. Among them, Figure 8 (a) is a comparison chart of arsenic concentrations at different pH values; Figure 8 (b) is a comparison chart of arsenic removal rates at different pH values; Figure 8 (c) is a comparison chart of antimony concentrations at different pH values; Figure 8 (d) is a comparison chart of antimony removal rates at different pH values. Figure 9 (a) is a comparison chart of arsenic concentrations at different influent flow rates; Figure 9 (b) is a comparison chart of antimony concentrations at different influent flow rates;

[0105] Figure 9 (c) is a comparison chart of arsenic removal rates at different influent flow rates; Figure 9 (d) is a comparison chart of antimony removal rates at different influent flow rates. Figure 10 (a) is a comparison chart of arsenic concentrations at different influent pollution concentrations; Figure 10 (b) is a comparison chart of antimony concentrations at different influent pollution concentrations; Figure 10 (c) is a comparison chart of arsenic removal rates at different influent pollution concentrations; Figure 10 (d) is a comparison chart of antimony removal rates at different influent pollution concentrations.

[0106] The results of the pH experiment show that (as Figure 8) Within 414 h, the removal rate of arsenic remained above 95% under all pH conditions. However, when the pH was 3, the removal rate of antimony was higher than 95% only within 100 h and then fluctuated below 95%. Under the condition of pH value 4, the removal rate of antimony was higher than 95% within 250.5 h and then decreased rapidly, reaching the lowest value of 74.09% at 414 h. Under the condition of pH value 5, the removal rate of antimony was higher than 95% within 215.5 h and then decreased rapidly, reaching the lowest value of 76.8% at 414 h. Under the condition of pH value 8, the removal rate of antimony was higher than 95% within 215.5 h and then decreased rapidly, reaching the lowest value of 72.2% at 414 h. Under the conditions of pH values 6 and 7, the removal rate of antimony was higher than 95% within 380 h and then decreased slowly, reaching the lowest values of 93.3% and 92.2% respectively at 414 h. The data indicate that under the condition of pH 6, the barrier zone has the highest removal rate of arsenic and antimony and the best removal effect.

[0107] The experimental results of the influent flow rate show that (as Figure 9 ) For the removal rate of arsenic: when the flow rate V = 0.5 m / d, the removal rate of arsenic was close to 100% continuously until 243.5 h. Subsequently, the removal rate of arsenic began to decrease slowly, and at 367 h, the effluent arsenic concentration reached the lowest value of 98.75%. Under the condition of flow rate V = 3 m / d, the removal rate of arsenic continued to decrease and reached the lowest value at 177 h, with the removal rate of arsenic being 97.24%. Under other flow rate conditions, the removal rate of arsenic fluctuated around 98.75% at each time period. For the removal rate of antimony: when the flow rate V = 0.5 m / d, the removal rate of antimony was higher than 95% within 359 h, and then the removal rate of antimony continued to decrease slowly, reaching the lowest value of 93.27% at 414 h. When the flow rates V = 1 m / d and V = 1.5 m / d, the removal rates of antimony were higher than 95% within 121 h and 104 h respectively, and then the removal rates of antimony decreased rapidly until 177 h, with the removal rates of antimony being 90.84% and 59.55% respectively. Under the conditions of flow rates V = 2 m / d and V = 3 m / d, the removal rates of antimony were lower than 95% at each time period and decreased rapidly starting from 126 h and 0 h respectively, with the lowest values being 71.42% and 33.64% respectively. The data further illustrate that under the condition of flow rate V = 0.5 m / d, the barrier zone has the highest removal rates of arsenic and antimony and the best removal effect.

[0108] The experimental results of the initial concentration show that (as Figure 10):Arsenic removal rate: Under the conditions of initial concentrations C = 0.5 mg / L, C = 1 mg / L, and C = 2 mg / L, from the initial time of 0.167 h to 227 h, the arsenic removal rate fluctuated around 99.7%. However, from 227 h to the final time of 414 h, the arsenic removal rate began to decline slowly, and the lowest arsenic removal rates were 96.89%, 99.409%, and 99.74% respectively. When C = 5 mg / L and C = 10 mg / L, from the initial time to the final time of 265.5 h, the arsenic removal rate continued to decline. The lowest arsenic removal rates were 97.99% and 93.62% respectively. Antimony removal rate: From the initial time to the final time, the antimony removal rate showed a downward trend. At the final time, when C = 0.5 mg / L, C = 1 mg / L, C = 2 mg / L, C = 5 mg / L, and C = 10 mg / L, the antimony removal rates were 92.20%, 92.32%, 94.57%, 72.8%, and 67.95% respectively. The data indicate that: Under the condition of the initial concentration C = 0.5 mg / L, the barrier zone has the highest removal rates for arsenic and antimony and the best removal effect.

[0109] Example 6

[0110] Investigation of the barrier amounts and contribution rates of each section of the barrier zone in Example 5 to arsenic and antimony

[0111] Barrier zone: The filling is the same as that of the columns in Example 5. Sampling points are set at the ends of the materials of each section of the barrier zone, and the effluent is collected regularly. Calculate the adsorption amounts of arsenic and antimony by each section of the material to obtain the contribution rates of each section.

[0112] The barrier zone and the models of each sampling point are as Figure 11 shown, and the barrier amounts and contribution rates of each barrier section to arsenic and antimony are shown in Table 4.

[0113] Table 4 Barrier amounts and contribution rates of each barrier section of the barrier zone to arsenic and antimony

[0114]

[0115] The results show that the arsenic interception amounts of the first three barrier sections are 1.193 mg, 3.225 mg, and 13.636 mg respectively. The antimony interception amounts are 0.967 mg, 3.953 mg, and 13.634 mg respectively. The interception amounts of arsenic and antimony in the last two sections are relatively low, and the barrier amounts of arsenic and antimony are both less than 0.05 mg. Analyzed from the contribution rates of each barrier section, the contribution rate of the third barrier section (FH-SG) is the highest, with the contribution rates to arsenic and antimony being 75.254% and 73.199% respectively. The contribution rate of the second section (zeolite) to arsenic and antimony is 17.796% and 22.222% respectively. The total barrier contribution rate of the first three barrier sections is extremely high, accounting for 99.636% of the arsenic contribution rate and 99.614% of the antimony contribution rate. The results show that in the experiment of reducing the contents of arsenic and antimony in water, the zeolite in the barrier zone plays an auxiliary role; FH-SG plays a major removal role.

[0116] Example 7

[0117] A practical operation experiment on the application of ferrihydrite-wheat bran solid powder material in reducing the contents of arsenic and antimony in water was carried out in a certain antimony mining area in Yiyang City, Hunan Province.

[0118] The site is a waste rock stacking yard after antimony ore beneficiation in the antimony mining area, with a huge amount of waste rock. Its characteristics are as follows: Source of sewage: The seepage water generated by natural precipitation and leaching water converges in the ditches on both sides. Waste rock yard - The initial concentration is extremely high: The initial antimony concentration is between 40 and 80 mg / L, and the initial arsenic concentration is between 0.5 and 1 mg / L. There is arsenic pollution, and the antimony pollution is particularly serious. The influent water volume varies greatly: Due to the different amounts of waste rock generated by the daily industrial production in the mining area and the different natural precipitation amounts, the influent water volume will change greatly. Influent water mode: Due to the large water volume in the waste rock yard, continuous water inflow can be guaranteed, and continuous reaction occurs in the barrier zone. A barrier zone is established in the water flow direction of the waste rock yard sewage, and the specific construction steps are as follows:

[0119] (1) First, a thick plastic film is laid on the outermost layer of the barrier zone to prevent water seepage. Then, a membrane with mesh holes of 20 - 40 meshes is laid on the inlet and outlet parts to prevent the material from being washed away by the water flow.

[0120] (2) The length, width, and height of the barrier zone are 1.7 m, 0.35 m, and 0.15 m respectively. It consists of 5 parts. According to the proportion and weight in the column experiment (specifically referring to Example 5), the length and weight of each part of the material are as follows: quartz 30 cm, 20.8 kg; zeolite 40 cm, 17.05 kg; FH-SG 30 cm, 3.45 kg; zeolite 40 cm, 17.05 kg; quartz 30 cm, 20.8 kg. When the seepage water flows through the barrier zone, it acts with the active substances in the barrier zone material, and adsorption and precipitation occur, and the heavy metals are intercepted and enter the soil and the surrounding environment. The actual construction picture of the barrier zone at this site is as Figure 12 shown.

[0121] (3) Take the influent and effluent at a frequency of once every 24 hours, and then measure the arsenic and antimony contents in the sewage.

[0122] (4) After detection: The arsenic concentration in the influent is relatively low and fluctuates irregularly around 0.497 mg / L - 0.699 mg / L. The arsenic concentration in the effluent is between 0.005 - 0.04 mg / L, and the arsenic concentration in the effluent is lower than the limit value of the Surface Water Environment Quality Standard (GB 3838 - 2002). However, the antimony concentration in the influent is very high, between 40 mg / L - 70 mg / L. The antimony concentration in the effluent is between 0.3 mg / L - 1.5 mg / L. Overall, the removal rate of arsenic by the barrier belt is between 95.05% - 99.04%, and the removal rate of antimony is between 98.01% - 99.50%. The antimony concentration in the influent is much higher than the arsenic concentration, but the barrier belt has good removal effects on both high-concentration antimony and low-concentration arsenic in the influent. For the specific arsenic and antimony barrier data in the sewage, see Figure 13 ; among them, Figure 13 (a) is a comparison chart of the arsenic concentration in the influent and the arsenic concentration in the effluent; Figure 13 (b) is a comparison chart of the antimony concentration in the influent and the antimony concentration in the effluent; Figure 13 (c) is a comparison chart of the removal rates of arsenic and antimony.

[0123] Example 8

[0124] Conduct a practical experiment on the application of ferrihydrite - wheat bran solid powder material in reducing the arsenic and antimony contents in water bodies in a certain antimony mining area in Yiyang City, Hunan Province

[0125] The site is a hillside around the mining area, and its characteristics are as follows: Source of sewage: Since the site is an antimony mining area, the background values of arsenic and antimony are high. Through natural precipitation, the surface runoff generated washes the arsenic and antimony in the soil down the hillside and converges in the film. Low initial concentration: The initial antimony concentration is between 1 - 4 mg / L, and the initial arsenic concentration is between 0.05 - 0.2 mg / L, and there is antimony pollution. Large variation in influent volume: Sewage is only generated when the natural rainfall is large, and there is no influent at other times. Influent mode: Intermittent influent, with intermittent reaction in the barrier belt. Along the slope of the hillside, a pollution barrier belt is established. When the natural rainfall flows through the barrier belt, it reacts with the active substances in the barrier belt material, and adsorption and precipitation occur, intercepting heavy metals. The specific construction steps are as follows:

[0126] (1) First, lay a thick plastic film on the outermost layer of the barrier belt to prevent water seepage. Then lay a mesh film with a mesh size of 20 - 40 on the influent and effluent parts to prevent the material from being washed away by the water flow.

[0127] (2) The length, width and height of the barrier zone are 1.7 m, 0.35 m and 0.15 m respectively. It consists of 5 parts. According to the proportion and weight in the column experiment (specifically refer to Example 5), the length and weight of the materials for each part are as follows: quartz, 30 cm, 20.8 kg; zeolite, 40 cm, 17.05 kg; FH-SG, 30 cm, 3.45 kg; zeolite, 40 cm, 17.05 kg; quartz, 30 cm, 20.8 kg. When the seepage water flows through the barrier zone, it reacts with the active substances in the barrier zone materials, and adsorption and precipitation occur, so that heavy metals are intercepted and enter the soil and the surrounding environment. The actual construction picture of the barrier zone at this site can be seen in Figure 14 .

[0128] (3) Samples of the influent and effluent were collected according to the weather conditions, and then the arsenic and antimony contents in the sewage were measured.

[0129] After detection: the arsenic concentration in the influent is very low, between 0.05 mg / L and 0.2 mg / L. The arsenic concentration in the effluent is below 0.002 mg / L, and the arsenic concentration in the effluent is far lower than the limit value of the surface water environmental quality standard (GB 3838-2002). At the same time, the antimony concentration in the influent is also relatively low, between 1 mg / L and 4 mg / L, and the antimony concentration in the effluent is only between 0.3 mg / L and 1.5 mg / L. The data shows that the removal rate of arsenic by the barrier zone is between 96.82% and 99.10%, and the removal rate of antimony is between 96.58% and 99.18%. The barrier zone has a good removal effect on low-concentration antimony and arsenic in the influent. The specific barrier data for this site (hillside seepage) can be seen in detail in Figure 15 ; among them, Figure 15 (a) is the comparison chart of the arsenic concentration in the influent and the arsenic concentration in the effluent; Figure 15 (b) is the comparison chart of the antimony concentration in the influent and the antimony concentration in the effluent; Figure 15 (c) is the comparison chart of the removal rates of arsenic and antimony.

[0130] Example 9

[0131] An actual operation experiment on the application of ferrihydrite-brewers' grains solid powder material in reducing the arsenic and antimony contents in water was carried out in a certain antimony mining area in Yiyang City, Hunan Province.

[0132] The site is a hardened cement ground in a mining area, and its characteristics are as follows: Source of sewage: Each time, one ton of new waste antimony ore is placed on the hardened cement ground in the mining area to simulate the ore leaching solution generated by precipitation, which serves as the source of sewage. The generated leaching solution is collected in a trench. Rainfall simulation - Initial concentration: The initial concentration is high and varies greatly. Due to the different amounts of water and pH controlled in rainfall simulation, the initial arsenic and antimony concentrations vary greatly. The initial arsenic concentration is between 0.2 and 12 mg / L, and the initial antimony concentration is between 30 and 100 mg / L. The pH value varies greatly. To explore the experimental requirements of the barrier for pH, we set three experimental groups with pH values of 3, 5, and 7 respectively. Large variation in water inflow: To explore the experimental requirements of the barrier for water volume, we set three experimental groups with rainfall intensities of 20 mm / h, 40 mm / h, and 60 mm / h respectively. And it is continuous water inflow, and there is always water flowing through the antimony and arsenic pollution barrier. Along the water flow direction, a pollution barrier is established, and its actual picture is as Figure 16 shown. The specific construction steps are as follows:

[0133] (1) First, line the outermost layer of the barrier with a thick plastic film to prevent water seepage. Then lay a mesh membrane with a mesh size of 20 - 40 meshes at the inlet and outlet parts to prevent the materials from being washed away by the water flow.

[0134] (2) The length, width, and height of the barrier are 1.7 m, 0.35 m, and 0.15 m respectively. It consists of 5 parts. According to the ratio and weight in the column experiment (specifically refer to Example 5), the lengths and weights of the materials for each part are: quartz 30 cm, 2 <

[0135] (3) Take water samples from the inlet and outlet at a frequency of once every 30 minutes, and then measure the arsenic and antimony contents in the sewage.

[0136] (4) Detection shows that when the pH is 3, the influent arsenic concentration can reach 2 - 12 mg / L. When the pH is 5 and 7, the influent arsenic concentration is 0.11 mg / L - 0.51 mg / L, which is much lower than the case when the pH is 3. Although the influent arsenic concentrations under different pH values vary greatly, the effluent arsenic concentrations vary little, and all concentrations are lower than 0.015 mg / L, far lower than the limit value of the Surface Water Environment Quality Standard (GB 3838 - 2002). The influent antimony concentration under each pH condition is very high, up to 30 - 100 mg / L. However, after the treatment by the barrier zone, the effect is remarkable. The effluent antimony concentration is reduced to 0.49 - 2.2 mg / L. Generally speaking, the removal rate of antimony by the barrier zone is between 95.08% and 99.88%, and the removal rate of arsenic is between 96.22% and 98.98%. pH has a great influence on the influent arsenic concentration and a small influence on the influent antimony concentration. However, this barrier zone has good removal effects on both antimony and arsenic regardless of the high or low concentrations of antimony and arsenic or the change of the influent pH value. For the specific arsenic and antimony barrier data in the rain sewage under different pH conditions, see Figure 17 ; among which, Figure 17 (a) is a comparison chart of the influent arsenic concentration under different pH conditions during rainfall; Figure 17 (b) is a comparison chart of the effluent arsenic concentration under different pH conditions during rainfall; Figure 17 (c) is a comparison chart of the influent antimony concentration under different pH conditions during rainfall; Figure 17 (d) is a comparison chart of the effluent antimony concentration under different pH conditions during rainfall; Figure 17 (e) is a comparison chart of the arsenic removal rate under different pH conditions during rainfall; Figure 17 (f) is a comparison chart of the antimony removal rate under different pH conditions during rainfall.

[0137] Refer to Figure 18, under each rainfall intensity condition (20 mm, 40 mm, 60 mm), when the pH is 5, the influent arsenic concentration in each period is relatively low, all between 0.1 mg / L and 0.7 mg / L. After being treated by the barrier belt, the effluent arsenic concentration is only 0.005 - 0.025 mg / L, far lower than the limit value of the Surface Water Environment Quality Standard (GB 3838 - 2002). However, the influent antimony concentration is very high, and with the increase of rainfall intensity, the influent antimony concentration becomes higher and higher. When the rainfall intensity is 60 mm, the influent antimony concentration is the highest, fluctuating around 80 mg / L, and can reach up to 120 mg / L at most. When the rainfall intensity is 40 mm, the influent antimony concentration fluctuates around 50 mg / L, and can reach up to 70 mg / L at most. When the rainfall intensity is 20 mm, the influent antimony concentration is the lowest, fluctuating around 30 mg / L, and can reach up to 40 mg / L at most. After being treated by the barrier belt, the effluent antimony concentration decreases rapidly. And the effluent antimony concentration also increases with the increase of rainfall intensity. When the rainfall intensity is 60 mm, the effluent antimony concentration is the highest, fluctuating around 1.5 mg / L. When the rainfall intensity is 40 mm, the effluent antimony concentration fluctuates around 0.75 mg / L. When the rainfall intensity is 20 mm, the effluent antimony concentration fluctuates around 0.5 mg / L. Generally speaking, the removal rate of the barrier belt for arsenic is between 95.08% and 98.53%, and the removal rate for antimony is between 96.23% and 99.25%. Rainfall intensity has a great influence on the influent and effluent antimony concentrations, and has a relatively small influence on the influent and effluent arsenic concentrations. However, this barrier belt shows good removal effects on both arsenic and antimony under three different rainfall conditions. Among them, Figure 18 (a) is a comparison chart of influent arsenic concentrations under different rainfall intensity conditions when the pH is 5; Figure 18 (b) is a comparison chart of effluent arsenic concentrations under different rainfall intensity conditions when the pH is 5; Figure 18 (c) is a comparison chart of influent antimony concentrations under different rainfall intensity conditions when the pH is 5; Figure 18 (d) is a comparison chart of effluent antimony concentrations under different rainfall intensity conditions when the pH is 5; Figure 18 (e) is a comparison chart of arsenic removal rates under different rainfall intensity conditions when the pH is 5; Figure 18 (f) is a comparison chart of antimony removal rates under different rainfall intensity conditions when the pH is 5.

[0138] In summary, Examples 7, 8, and 9 illustrate that the barrier belt can not only adapt to high-concentration antimony and arsenic environments, but also adapt to acidic and neutral environments with relatively low pH values, and can also adapt to different rainfall intensity environments. It further shows that the barrier belt can adapt to the complex environment of mining areas and has good shock resistance.

[0139] In summary, in the above technical solutions of the present invention, the above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structural transformation made under the technical concept of the present invention by using the content of the specification and drawings of the present invention, or any direct / indirect application in other related technical fields is included in the patent protection scope of the present invention.

Claims

1. A preparation method of a ferrihydrite-brewers' grains solid powder material, characterized in that, Including the steps: Providing a leaching solution of brewer's grains powder and a ferric nitrate nonahydrate solution respectively; the leaching solution of brewer's grains powder includes hydroxyl groups, carboxyl groups, amino groups, silicon element, phosphorus element, sulfur element, calcium element and magnesium element; Dropping the leaching solution of brewer's grains powder into the ferric nitrate nonahydrate solution until the pH of the obtained mixed solution is 7.2 - 7.5; wherein, the dropping speed is 50 mL / h; Centrifuging the mixed solution, and sequentially performing a cooling treatment at -80 °C and a freeze-drying treatment on the obtained solid phase to obtain the ferrihydrite-brewer's grains solid powder material.

2. The preparation method according to claim 1, wherein The obtaining method of the leaching solution of brewer's grains powder includes the steps: Performing a drying treatment and a crushing treatment on brewer's grains in sequence, and passing through a 100-mesh sieve to obtain brewer's grains powder; Mixing the brewer's grains powder into a 0.1 mol / L calcium hydroxide solution, and performing a water bath heating treatment at 100 °C for 1 h to obtain a brewer's grains powder mixed solution; After the brewer's grains powder mixed solution is cooled to 20 - 30 °C, performing a solid-liquid separation treatment to obtain the leaching solution of brewer's grains powder.

3. The preparation method according to claim 2, wherein, The temperature of the drying treatment is 60 °C.

4. The preparation method according to claim 2, wherein The way of the solid-liquid separation treatment is to centrifuge the brewer's grains powder mixed solution cooled to room temperature at 3000 rPm for 5 min to obtain the leaching solution of brewer's grains powder.

5. The preparation method according to claim 2, characterized in that, The mass ratio of ferric nitrate nonahydrate in the ferric nitrate nonahydrate solution, the brewer's grains powder and calcium hydroxide in the calcium hydroxide solution is 4:3:1 - 2.

6. The preparation method according to claim 1, wherein The way of the centrifuging treatment is to centrifuge the mixed solution at 10000 rPm for 5 min to obtain the solid phase.

7. The preparation method according to claim 1, wherein The temperature of the freeze-drying treatment is -100 °C.

8. A ferrihydrite-brewer's grains solid powder material prepared by the preparation method according to any one of claims 1 - 7.

9. Use of the ferrihydrite-brewer's grains solid powder material as described in claim 8 in reducing the arsenic and antimony contents in water bodies, characterized in that, Constructing a barrier zone upstream of the water body, and the height of the barrier zone is higher than the water flow height of the water body; The barrier zone is divided into 5 parts, and the components of each part are 8 - 10 mesh quartz, 10 - 20 mesh zeolite, the ferrihydrite-brewer's grains solid powder material according to claim 8, 10 - 20 mesh zeolite and 8 - 10 mesh quartz in sequence along the water flow direction.

10. The application according to claim 9, characterized in that, The length ratio of the 5 parts of the barrier zone is 6:8:6:8:6.

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