CN112960701A

CN112960701A - Schwertmannite for sewage dephosphorization and efficient synthesis method thereof

Info

Publication number: CN112960701A
Application number: CN202110183778.0A
Authority: CN
Inventors: 方迪; 刘兰兰; 周立祥
Original assignee: Nanjing Agricultural University
Current assignee: Nanjing Agricultural University
Priority date: 2021-02-08
Filing date: 2021-02-08
Publication date: 2021-06-15

Abstract

The invention provides a Schneider mineral for sewage dephosphorization and a high-efficiency synthesis method thereof, which comprises the following steps: the oxidation, hydrolysis and mineralization reaction of soluble iron in the acidic mine wastewater are regulated and enhanced by adding a small amount of alkaline substances, and the synthesis efficiency of the Schwerer mineral is greatly improved (the primary mineralization rate is more than 90%). Overcomes the defects of low synthesis efficiency, long process flow and high cost of the Schneider minerals in the prior art. Meanwhile, the schwertmannite synthesized based on alkali regulation and control can generate strong physical and chemical adsorption on phosphorus in the phosphorus-rich sewage, sulfate in a mineral phase can also exchange with phosphate, the phosphorus absorption performance is excellent (the adsorption capacity is 19.9mg/g), and the schwertmannite is a novel sewage phosphorus absorption/phosphorus removal material with an application prospect.

Description

Schwertmannite for sewage dephosphorization and efficient synthesis method thereof

Technical Field

The invention belongs to the technical field of wastewater treatment and resource recovery, and particularly relates to a Schwertmannite mineral for sewage dephosphorization and a high-efficiency synthesis method thereof.

Background

Phosphorus is an indispensable important nutrient element for all organisms and is a non-renewable non-metallic mineral resource. In recent years, due to the increasing demand of agricultural production for phosphate fertilizers and the rapid development of the phosphorus chemical industry, a large amount of phosphorus is lost from the environmental process, and about 80% of phosphorus is discharged along with sewage. This not only causes the problem of water eutrophication to be more severe, but also greatly aggravates the phosphorus crisis caused by the shortage of phosphorite. Therefore, the method for removing or recovering the phosphorus from the phosphorus-rich sewage and realizing the regeneration cycle of the phosphorus-rich sewage has important practical significance for preventing and controlling phosphorus pollution and relieving phosphorus crisis.

The adsorption method is an economic and effective technical way which is simple to operate and can remove and recover phosphorus from sewage, and has good engineering application prospect. Currently, the widely used phosphorus adsorption materials are mainly: modified carbon-based materials, magnetite, double metal hydroxides, ion exchange resins, molecular sieves and the like. Many researches show that although the traditional adsorbing materials can achieve better phosphorus absorption and phosphorus removal effects, the preparation methods, conditions and procedures are mostly severer or more complicated, so that the practical application treatment cost is higher. Therefore, the development of a new sewage dephosphorization material which is cheap, easy to obtain, environment-friendly and efficient is urgently needed.

Schlieren mineral (iron hydroxy sulfate Fe)₈O₈(OH)₆SO₄) Is a waste rich in iron and sulfate which is widely existed in an acid mine waste water environment. In recent years, the Schlemn's mineral serving as a novel environment restoration material is largely used for passivating soil heavy metal and removing toxic pollutants in polluted water, and shows good performanceThe composite material has the effects of adsorbing As (III) and Cr (VI) in water efficiently and degrading organic pollutants such as antibiotics, polycyclic aromatic hydrocarbons, phenol and the like in water as a catalyst of heterogeneous Fenton. In view of the unique surface structure and composition characteristics of schwerer minerals, such as: huge specific surface area, abundant hydroxyl site density, and high concentration of Fe and SO₄And the like, the Schlemn mineral is supposed to have good adsorption and exchange removal performance on phosphate in water, so that the invention provides possibility for inventing a new sewage dephosphorization technology based on the concept of 'treating sewage with waste'.

Obtaining a large amount of Schneider minerals from the acid mine wastewater is the premise for realizing the sewage dephosphorization technical idea. The natural formation process of the Schneider minerals in the acid mine wastewater is slow, so that manual regulation and reinforcement are needed to promote the rapid generation of the Schneider minerals. The existing technical scheme for promoting the synthesis of the Schneider minerals in the acid mine wastewater mainly comprises the following steps: biological synthesis method of inoculating acidophilic iron oxidizing bacteria, and chemical synthesis method of adding hydrogen peroxide. However, from the existing research practice, these two types of methods often face the following technical bottlenecks: low mineral synthesis efficiency (the primary mineralization rate is less than 40 percent), long process flow (the combination with the reduction reaction of zero-valent iron is needed and the cycle repetition is needed for many times), high cost (hydrogen peroxide is a dangerous chemical, the addition amount is large, and sometimes high temperature and high pressure are needed for assistance). These inherent drawbacks greatly limit the large-scale deployment and application of schneider minerals as a potential environmental remediation material. Therefore, there is a need to develop a new method for efficiently synthesizing schrader minerals from acidic mine wastewater.

Disclosure of Invention

1. Solves the technical problem

Aiming at the following technical bottlenecks faced by the existing sewage adsorption dephosphorization: the preparation method, conditions and procedures of the adsorbing material are severer and complicated, and the cost is higher, so the invention provides a cheap and easily obtained novel efficient phosphorus removal material, namely Shi's mineral; furthermore, the invention also provides a novel method for efficiently synthesizing the schlerian mineral by taking the acid mine wastewater as a raw material, and overcomes the defects of low synthesis efficiency, long process flow and high cost of the conventional schlerian mineral.

2. Technical scheme

In order to achieve the purpose, the invention provides the following technical scheme:

the invention provides a method for efficiently synthesizing schwertmannite from acid mine wastewater, which comprises the following steps:

alkali regulation promotes schwertmannite formation: aerating and culturing the filtered acid mine wastewater for a period of time to ensure that Fe²⁺Oxidation to Fe³⁺Then adding a certain amount of alkaline substance while stirring and mixing, adjusting the pH of the system to 2-4, and inducing Fe in the wastewater³⁺Hydrolysis and mineralization reactions occur to produce a yellow-brown solid.

In a preferred scheme, the Schwerner mineral for removing phosphorus from sewage and the efficient synthesis method thereof comprise the following steps: (1) filtering and removing impurities from acid mine wastewater: removing suspended particles in the acid mine wastewater;

(2) synthesizing a Schneider mineral: aerating and culturing the filtered acid mine wastewater for a period of time to ensure that Fe in the wastewater²⁺Oxidation to Fe³⁺Then adding a certain amount of alkaline substance, stirring and mixing, regulating the pH value of the system to 2-4, and inducing Fe in the wastewater³⁺Hydrolysis and mineralization reactions occur to produce a yellow-brown solid.

(3) Collecting Schlempe mineral: and (3) carrying out suction filtration on the yellowish-brown precipitate, washing the yellowish-brown precipitate for 1 to 3 times by using dilute sulfuric acid and deionized water, drying the yellowish-brown precipitate, and grinding the yellowish-brown precipitate through a 100-mesh screen to obtain the schneiderian mineral.

Preferably, the aeration culture time in the step (2) is 1 to 3 days.

In a preferable scheme, the alkaline substance added in the step (2) comprises but is not limited to any one of magnesium oxide, sodium hydroxide, quicklime or potassium hydroxide, the adding dose is 1-5 g/L, the stirring speed is 100-300rpm, and the stirring time is 3-5 h. The sodium hydroxide can be selectively added as flake caustic soda or liquid caustic soda.

In a preferred embodiment, the present invention provides a schlerian mineral synthesized by the above method.

The XRD pattern of the Schneider mineral has characteristic peaks at the positions of 18.24 degrees, 26.26 degrees, 35.16 degrees, 39.49 degrees, 46.53 degrees, 55.29 degrees and 61.34 degrees.

In a preferred embodiment, the invention provides the application of schwerer minerals to phosphorus adsorption in phosphorus-rich sewage. The schwertmannite prepared by the method can generate strong physical and chemical adsorption to phosphorus in water, and simultaneously sulfate and phosphate in an ore phase can also be exchanged, so that the content of phosphorus in the water is greatly reduced.

The phosphorus-rich sewage comprises phosphorus-containing industrial sewage, sludge liquid, livestock and poultry breeding wastewater and the like, and the specific operation is as follows: adding schlempe mineral into the phosphorus-rich sewage for shake culture.

Preferably, the schneiderian mineral is added into the phosphorus-rich sewage, and the phosphorus-rich sewage is placed into a reciprocating shaking table to be shaken for a period of time, wherein the shaking culture condition of the reciprocating shaking table is that the rotating speed is 100-300rpm, the temperature is 15-35 ℃, and the shaking time is 12-70 h.

Preferably, the addition amount of the Schneider minerals in the water body is not less than 12 g/L.

In the preferred scheme, the step of removing phosphorus in the water body by using Schwerer mineral dephosphorization adsorption comprises the following steps:

adding a certain amount of Schlempe mineral into the phosphorus-rich sewage, oscillating, mixing and culturing at constant temperature for a period of time, wherein the Schlempe mineral can strongly adsorb phosphorus in water physically and chemically, sulfate and phosphate in an ore phase can also exchange, the content of phosphorus in water is greatly reduced, then filtering the filtrate through a 0.45 mu m filter membrane, measuring the content of phosphorus in the filtrate, and calculating the phosphorus adsorption rate and the adsorption capacity of the Schlempe mineral according to the change of concentration.

3. Advantageous effects

Compared with the prior art, the invention has the beneficial effects that:

(1) the novel sewage dephosphorization material, namely the Schneider mineral, provided by the invention has the typical characteristic peak of the Schneider mineral shown by an XRD (X-ray diffraction) spectrum and contains a large amount of-OH and SO shown by an FI-IR spectrum₄ ^2-And Fe-O functional groups; the schlempe mineral synthesized by the method can generate strong physical and chemical adsorption on phosphorus in the phosphorus-rich sewage, and simultaneously sulfate in the mineral phase can also exchange with phosphate, so that the sewage dephosphorization effect is good.

(2) The synthetic raw material of the Schwertmannite provided by the invention is acid mine wastewater, so that the purposes of changing waste into valuable and treating pollution by waste are realized; the method for synthesizing the Schwerner mineral based on alkali regulation and control can improve the one-time mineralization rate of the Schwerner mineral in the acid mine wastewater from 40% to more than 90%, greatly improves the synthesis efficiency, and has the advantages of mild process, convenience in operation, low cost and environmental friendliness.

(3) The synthesized Schneider mineral pair KH₂PO₄The adsorption amount of phosphorus in the solution is up to 19.9mg/g, which is obviously superior to that of the Schlemn mineral prepared by other methods and is 2.8 times of that of the biosynthesized Schlemn mineral, and the chemically synthesized Schlemn mineral has no obvious adsorption to phosphorus.

Drawings

FIG. 1 is a pictorial view of a Schneider mineral prepared in example 1;

FIG. 2 is an SEM-EDS diagram of a Schneider mineral prepared in example 1;

FIG. 3 is a Fourier transform Infrared Spectroscopy (FT-IR) spectrum of the Schneider mineral prepared in example 1;

FIG. 4 is an XRD pattern of the Schneider mineral prepared in example 1 compared to a standard card; wherein, figure a is the XRD pattern of the Schwerner mineral prepared in example 1; figure b is an XRD pattern of a standard card of schlieren mineral;

FIG. 5 shows KH as a function of Schneider minerals prepared in example 1 and prepared by conventional biosynthesis and chemical synthesis₂PO₄Comparing the adsorption capacity of phosphorus in the solution;

FIG. 6 shows the effect of different addition amounts of Schwerner minerals on the adsorption of phosphorus in sludge from sewage plants in example 2.

Detailed Description

The technical solution of the present invention will be further described with reference to the accompanying drawings in the embodiments of the present invention.

Example 1

The process for efficiently synthesizing the schwertmannite from the acid mine wastewater comprises the following steps:

(1) filtering to remove impurities: acid mine is removed by filtrationSuspended particulate matter in wastewater. The water sample used in this example was taken from acidic mine wastewater discharged from a pyrite smelter in south China, pH 2.72, and soluble iron content 895mg/L, where Fe²⁺The content of SO is 436mg/L₄ ^2-The content is 5200 mg/L.

(2) Alkali-regulated schwerner mineral formation: carrying out aeration culture on the filtered wastewater for 2 days, adding caustic soda flakes (1.5g/L), stirring for 3 hours at 150rpm, measuring the pH of a system to be 3.82, and obtaining a precipitate with the total iron precipitation rate of 98%;

(3) collecting minerals: the resulting precipitate was collected by filtration through a 0.45 μm filter membrane, washed 2 times with dilute sulfuric acid (pH 4.0) and then with deionized water, and dried in a drying oven at 60 ℃ to obtain the desired mineral.

As can be seen from fig. 1, the mineral prepared by the present invention is yellowish brown, powdery. As can be seen by SEM-EDS in FIG. 2, the mineral has a smooth spherical appearance and is rich in Fe/S/O elements. The FI-IR spectrum of FIG. 3 shows that the mineral contains a large amount of-OH and SO₄ ^2-And Fe-O functional groups, both of which are characteristic functional groups of Schneider minerals. The XRD of fig. 4 further verifies that the mineral is schneishi (the characteristic peaks at 18.24 °, 26.26 °, 35.16 °, 39.49 °, 46.53 °, 55.29 °, 61.34 ° correspond exactly to the standard card of schneishi mineral). In summary, the mineral synthesized in the present invention from the acidic mine wastewater to be tested was schneiderian mineral.

Comparative group 1

The Shi mineral synthesized by the comparison group by adopting a biological synthesis method adopts the synthesis method disclosed in the Chinese invention patent application No. 200510094428.8, and the method comprises the following steps:

(1) 300mL of dilute sulfuric acid solution having a pH of 5 was added to the Erlenmeyer flask, followed by 21.6g of FeSO₄·7H₂O and stirring uniformly, inoculating Thiobacillus ferrooxidans LX5 to make its quantity reach 10⁷～10⁸one/mL.

(2) Placing the triangular flask in a reciprocating shaking table, keeping the temperature at 28 ℃, oscillating at 180rpm for 72h, and generating precipitates;

(3) filtering and collecting the generated precipitate with 0.45 μm filter membrane, washing with sulfuric acid solution with pH of 2.0-2.5 for 3 times, washing with deionized water for 3 times, and oven drying at 60 deg.C in constant temperature drying oven to obtain biosynthesized Schneider mineral.

Comparative group 2

The schneishi mineral synthesized by the chemical synthesis method in the comparison group adopts the synthesis method disclosed in the Chinese invention patent application number 201910387492.7, and the method specifically comprises the following steps:

(1) 300mL of a dilute sulfuric acid solution having a pH of 5 was added to an Erlenmeyer flask, followed by 21.6g of FeSO₄·7H₂O and evenly stirred, and then 3.5mL of H with the mass fraction of 30 percent is added₂O₂；

(2) Placing the triangular flask in a reciprocating shaking table, keeping the temperature at 28 ℃, oscillating at 180rpm for 24 hours, and generating precipitates;

(3) filtering and collecting the generated precipitate with 0.45 μm filter membrane, washing with sulfuric acid solution with pH of 2.0-2.5 for 3 times, washing with deionized water for 3 times, and oven drying at 60 deg.C in constant temperature drying oven to obtain chemically synthesized Schneider mineral.

Phosphorus adsorption experiment

Adsorbing phosphorus: the Schleman mineral obtained in example 1, the Schleman mineral biosynthesized in comparative group 1 and the Schleman mineral chemically synthesized in comparative group 2 were weighed, 75mg each, and 50mL of KH mineral containing phosphorus at a concentration of 30mg/L were added thereto₂PO₄The solution (simulated phosphorus-containing wastewater) was shaken at 20 ℃ and 150rpm for 24 hours, and then passed through a 0.45 μm filter to measure the phosphorus concentration. The amount of adsorption was calculated from the change in the concentration of phosphorus.

The above three groups of Schwertmannite with different sources are used for treating KH₂PO₄The results of the adsorption of phosphorus in the solution are shown in FIG. 5. As can be seen from the figure, the adsorption performance of the Schneider mineral prepared by the invention on phosphorus is obviously superior to that of the Schneider mineral prepared by a biological method and a chemical method, the adsorption capacity of the Schneider mineral prepared by the invention is 2.8 times of that of the biological method and the chemical method, and the chemically synthesized Schneider mineral has no obvious adsorption on phosphorus.

Compared with the Schwerner mineral prepared by the existing biological method and chemical method, the Schwerner mineral obtained by the method not only has more excellent phosphorus adsorption performance, but also does not need to be additionally inoculated with microbial strains in the preparation processAnd adding hazardous chemical H₂O₂And the cost is saved and the environment is protected.

Example 2

The process of efficiently synthesizing the Schneider minerals from the acid mine wastewater and the application of sewage dephosphorization comprise the following steps:

(1) filtering to remove impurities: the water sample used in this example was collected from an acid reservoir downstream of a surface mining plant of a metal mine in Jianghuai region, pH 2.12, dissolved iron content 1260mg/L, SO₄ ^2-The content is 6000mg/L, and suspended particles in the acid mine wastewater are removed by filtration.

(2) Alkali-regulated mineral formation: carrying out aeration culture on the filtered acidic mine wastewater for 3 days, adding magnesium oxide (5g/L), stirring for 5 hours at a stirring speed of 100rpm, determining that the pH value of the system is 2.86, and the total iron precipitation rate is 90%, thus obtaining a precipitate;

(3) collecting minerals: the resulting precipitate was collected by filtration through a 0.45 μm filter, and the precipitate was washed 3 times with a sulfuric acid solution (pH 3.0) and deionized water, dried in a drying oven at 60 ℃, and the sample was preserved.

(4) Adsorbing phosphorus: weighing the obtained mineral 125mg, adding into 50mL KH containing phosphorus with concentration of 100mg/L₂PO₄The solution (simulated phosphorus-containing wastewater) was shaken at 35 ℃ and 300rpm for 12 hours, and then passed through a 0.45 μm filter to measure the phosphorus concentration. According to the concentration change, the adsorption removal rate of the mineral to phosphorus is calculated to be 78%.

Example 3

(1) filtering to remove impurities: the water sample used in this example was collected from the acidic pit water of a certain copper ore smelter in Jianghuai region, pH 1.69, soluble iron content 1600mg/L, SO₄ ^2-The content is 6800mg/L, and suspended particles in the acid mine wastewater are removed by filtration.

(2) Alkali-regulated mineral formation: carrying out aeration culture on the filtered acid mine wastewater for 1 day, adding liquid caustic soda (1.2g/L), stirring for 4 hours at a stirring speed of 300rpm, measuring the pH of a system to be 2.0, and obtaining a precipitate with a total iron precipitation rate of about 92%;

(3) collecting minerals: the resulting precipitate was collected by filtration through a 0.45 μm filter, and the precipitate was washed 3 times with a sulfuric acid solution (pH 2.5) and deionized water, dried in a drying oven at 60 ℃, and the sample was preserved.

(4) In the experiment of adsorbing phosphorus in sludge liquid of a sewage plant by using Shih mineral, the tested phosphorus-containing sewage is sludge supernatant (pH is 2.5, and the phosphorus content is 350mg/L) of a certain sewage plant in Jiangsu province.

75, 300, 600 and 900mg of Schlemm's mineral are weighed into a 100mL Erlenmeyer flask, 50mL of sludge liquid is added, shaking is carried out at 100rpm for 70h under the condition of 15 ℃, and the phosphorus concentration is measured by a 0.45 mu m filter membrane. The adsorption rate was calculated from the change in the concentration of phosphorus. As can be seen from FIG. 6, when the addition amount of the Schneider mineral is more than 12g/L, the adsorption removal rate of phosphorus in the sludge liquid can be more than 82% in 24 h.

Example 4

The schlerian mineral to be tested was the mineral sample prepared in example 2, and the phosphorus-containing wastewater to be tested was obtained from biogas slurry (pH 8.21, phosphorus content 182mg/L) of fecal sewage obtained from a certain livestock and poultry farm in Jiangsu province after anaerobic digestion treatment.

And (3) filtering biogas slurry to remove impurities: and filtering with filter paper to remove suspended particles in the biogas slurry.

Adsorbing phosphorus in the biogas slurry by using Schwerer minerals: 450mg of Schneider mineral is weighed and added into 50mL of the biogas slurry, the mixture is oscillated at 150rpm for 24h under the condition of 28 ℃, the sampling is carried out, the mixture is filtered through a 0.45 mu m filter membrane, and the phosphorus concentration is measured. The adsorption removal rate of phosphorus in the biogas slurry is 93% by calculation.

The present invention and its embodiments have been described above schematically, without limitation, and what is shown in the drawings is only one of the embodiments of the present invention, and the actual structure is not limited thereto. Therefore, if the person skilled in the art receives the teaching, without departing from the spirit of the invention, the person skilled in the art shall not inventively design the similar structural modes and embodiments to the technical solution, but shall fall within the scope of the invention.

Claims

1. A method for efficiently synthesizing Schwertmannite from acid mine wastewater is characterized by comprising the following steps:

alkali-regulated mineral formation: aerating and culturing the filtered acid mine wastewater for a period of time to enable Fe²⁺Oxidation to Fe³⁺Then adding a certain amount of alkaline substance while stirring and mixing, adjusting the pH of the system to 2-4, and adjusting the Fe in the wastewater³⁺Hydrolysis and mineralization reactions occur to produce a yellow-brown solid.

2. The method for efficiently synthesizing schrader minerals from acidic mine wastewater according to claim 1, wherein: the aeration culture time is 1-3 days.

3. The method for efficiently synthesizing schrader minerals from acidic mine wastewater according to claim 2, wherein: the added alkaline substance comprises any one of magnesium oxide, sodium hydroxide, quicklime or potassium hydroxide, the adding dose is 1-5 g/L, the stirring speed is 100-300rpm, and the stirring time is 3-5 h.

4. The method for efficiently synthesizing schrader minerals from acidic mine wastewater according to claim 3, wherein: the method also comprises the following steps of (1) filtering and removing impurities: and filtering to remove suspended particles carried by the acidic mine wastewater.

5. The schlerian mineral prepared by the method for efficiently synthesizing the schlerian mineral from the acid mine wastewater, which is prepared by any one of claims 1 to 4.

6. The schneiderian mineral of claim 5, characterized in that: the XRD pattern of the Schneider mineral has characteristic peaks at the positions of 18.24 degrees, 26.26 degrees, 35.16 degrees, 39.49 degrees, 46.53 degrees, 55.29 degrees and 61.34 degrees.

7. Use of the schneiderian mineral of claim 5 or 6 as an adsorbent for phosphorus removal from wastewater.

8. Use according to claim 7, characterized in that: adding schlempe mineral into the phosphorus-rich sewage for shaking culture at the rotation speed of 100-300rpm at the temperature of 15-35 ℃ for 12-70 h.

9. Use according to claim 8, characterized in that: the phosphorus-rich sewage comprises phosphorus-containing industrial sewage, sludge liquid of a sewage treatment plant and livestock and poultry breeding wastewater.

10. Use according to claim 9, characterized in that: the addition amount of the Schneider minerals in the water body is not less than 12 g/L.