CN113461131B

CN113461131B - Preparation method and application of heavy metal and organic matter composite sewage purifying agent

Info

Publication number: CN113461131B
Application number: CN202110741449.3A
Authority: CN
Inventors: 许晓明; 胡国峰; 陈堃; 蒋庆肯; 姜明明; 向浩; 刘子豪; 邵雁; 刘颖
Original assignee: China City Environment Protection Engineering Ltd
Current assignee: China City Environment Protection Engineering Ltd
Priority date: 2021-07-01
Filing date: 2021-07-01
Publication date: 2022-06-07
Anticipated expiration: 2041-07-01
Also published as: CN113461131A

Abstract

The invention provides a preparation method of a heavy metal and organic matter composite sewage purifying agent, which comprises the following steps: firstly, mixing pyrite tailings and a soil sample according to a mass ratio of 1: 10-12 to obtain a raw material mixture; secondly, grinding the raw material mixture to a particle size of less than 15 μm; thirdly, pressing and molding the ground raw material mixture, and then calcining, wherein the calcining temperature is not lower than 1200 ℃, and the calcining time is 6-8 hours; and finally, adding the calcined raw material mixture and quaternary ammonium salt into an aqueous solution according to the mass ratio of 100: 3-10, and stirring, filtering, washing and drying to obtain the heavy metal and organic matter composite sewage purifying agent. The purifying agent prepared by the invention has the advantages of easily available raw materials and low cost, has excellent treatment capacity on heavy metals and organic pollutants, and can effectively meet the purification requirement of heavy metal and organic compound polluted wastewater.

Description

Preparation method and application of heavy metal and organic matter composite sewage purifying agent

Technical Field

The invention belongs to the technical field of sewage purification treatment, and particularly relates to a preparation method and application of a heavy metal and organic matter composite sewage purifying agent.

Background

At the present stage, a large amount of water body resources which are compositely polluted by heavy metals and organic matters exist in China. With the acceleration of the urbanization process and the adjustment of the industrial structure, a large number of pollution enterprises such as steel, petrifaction, pesticides, printing and dyeing, electroplating and the like are moved, reformed and shut down, so that a large number of pollution sites appear in cities and surrounding areas, and further diffusion of pollution sources can have obvious influence on surrounding underground water. The landfill leachate overflows due to stratum deformation or impervious barrier damage of part of old landfill sites, and can also pollute surrounding water bodies, thus seriously threatening the life health and safety of surrounding residents.

The pollution source in the composite polluted water body comprises various heavy metal ions (such as arsenic, chromium, cadmium, lead, mercury and the like) and organic pollutants (such as benzene series, chlorohydrocarbon, phenols and the like). Most of various water purifying agents developed at the present stage can only realize independent high-efficiency treatment on a certain specific type of heavy metal or organic pollutant, and cannot meet the complex actual polluted environment in the environmental protection field, so that the underground water pollution treatment process is complex and the period is long. In addition, the existing water body purifying agent in the sewage treatment industry generally adopts various industrial produced flocculating agents, and the problem that the cost of the existing sewage treatment system is higher is caused.

In view of this, it is a technical problem that researchers need to solve to improve the existing sewage purifying agent, improve the comprehensive purifying efficiency of the purifying agent for heavy metals and organic pollutants, and reduce the production and manufacturing costs of the purifying agent.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides the preparation method of the heavy metal and organic matter composite sewage purifying agent, and the preparation method can simultaneously improve the purifying treatment capacity of the prepared purifying agent on heavy metal ions and organic pollutants in a water body and obviously reduce the production and manufacturing cost of the purifying agent. The invention also provides application of the purifying agent prepared by the preparation method in purifying underground water compositely polluted by heavy metals and organic matters.

In order to solve the technical problems, the invention adopts the following technical scheme:

in a first aspect, the invention provides a preparation method of a heavy metal and organic matter composite sewage purifying agent, which comprises the following steps:

s1, mixing the pyrite tailing and the soil sample according to the mass ratio of 1: 10-12 to obtain a raw material mixture;

s2, grinding the raw material mixture to a particle size of less than 15 microns;

s3, firstly pressing and molding the ground raw material mixture, and then calcining, wherein the calcining temperature is not lower than 1200 ℃, and the calcining time is 6-8 h;

s4, adding the calcined raw material mixture and quaternary ammonium salt into an aqueous solution according to the mass ratio of 100: 3-10, and stirring, filtering, washing and drying to obtain the heavy metal and organic matter composite sewage purifying agent.

On the basis of the technical scheme, the particle size of the pyrite tailing is 30-40 mu m.

On the basis of the technical scheme, the particle size of the soil sample is smaller than 75 mu m, and the content of active substances in the soil sample is not lower than 70%.

On the basis of the above technical solution, the active substance comprises at least illite, montmorillonite and chlorite.

On the basis of the technical scheme, in the step S3, the ground raw material mixture is pressed to obtain the raw material mixture with the density of 1.8-2.0 g/cm³Spherical raw material mixture with a diameter of 2 cm.

On the basis of the above technical solution, in step S4, the quaternary ammonium salt is one of cetyltrimethylammonium bromide, dodecyltrimethylammonium bromide, octadecyldimethylbenzylammonium chloride, and octadecyltrimethylammonium chloride.

On the basis of the technical scheme, the quaternary ammonium salt is hexadecyl trimethyl ammonium bromide, and the mass ratio of the calcined raw material mixture to the hexadecyl trimethyl ammonium bromide is 100: 5.

On the basis of the technical scheme, in the step S4, the stirring temperature is 60 ℃, the stirring time is 2 hours, the drying temperature is 80 ℃, and the drying time is 3-4 hours.

In a second aspect, the invention provides an application of the heavy metal and organic matter composite sewage purifying agent prepared by the preparation method in the first aspect in purifying underground water compositely polluted by heavy metals and organic matters.

On the basis of the technical scheme, the addition amount of the heavy metal and organic matter composite sewage purifying agent is 20-30 g/L.

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

(1) the main raw materials selected by the preparation method of the purifying agent are a soil sample and pyrite tailing. Among them, the soil sample exists in various natural environments, and the clay mineral (illite, montmorillonite, chlorite, etc.) is rich in clay mineral which is an active substance with certain adsorption capacity; the pyrite is a common mineral of metal mines, is often taken as a non-ferrous metal byproduct, even is taken as waste, and has the advantages of easy acquisition of two raw materials and low cost.

(2) The soil sample adopted by the invention contains more than 70% of active substances (clay minerals such as illite, montmorillonite and chlorite), and the layered clay minerals have various performances such as large surface area, more gaps, strong cation exchange and adsorption capacity and the like. S generated by slightly dissolving pyrite tailing in water adopted by the invention₂ ^2-、S^2-、Fe²⁺The ions have strong reducibility and can reduce Cr in polluted water⁶⁺The toxicity is reduced, brand-new insoluble sulfide is generated, and in addition, the iron compound in the pyrite tailing has a good adsorption and passivation effect on As.

(3) In the preparation method, the final particle size of the mixture of the soil sample and the pyrite tailing is controlled to be below 15 mu m through the grinding modification step. The step can obviously increase the specific surface area of the mixture, create lattice dislocation, lattice defects and the like on the surface of the mineral, and further improve the adsorption capacity of the clay mineral on the heavy metal.

(4) In the preparation method, the mixture after grinding and modification is subjected to high-temperature calcination treatment at the temperature of not less than 1200 ℃, so that various kinds of molten pyrite are fully loaded on the surface of the clay mineral, and the passivation effect of the clay mineral on various heavy metal ions can be obviously improved.

(5) According to the preparation method, after grinding modification and high-temperature calcination treatment, an organic matter modification step is added, the lattice spacing of the clay mineral (001) surface is improved by using quaternary ammonium salt ions, the adsorption capacity of the clay mineral to macromolecular organic pollutants is improved, and when the addition amount of quaternary ammonium salt (cetyl trimethylammonium bromide) is 5% of the mass of the mixture, the clay mineral has excellent modification effect and cost advantage.

(6) When the purifying agent prepared by the preparation method is used as a sewage purifying agent, the highest passivation efficiency of heavy metals in the simulated wastewater can reach 95% when the adding amount of the purifying agent is 30g/L, the highest purification efficiency of organic pollutants can reach 93%, the purifying agent has excellent treatment capacity for the heavy metals and the organic pollutants, and can effectively meet the purification requirement of the heavy metal and organic compound polluted wastewater.

Drawings

FIG. 1 is a flow chart of a preparation method of a heavy metal and organic matter composite sewage purifying agent according to an embodiment of the present invention.

Detailed Description

The technical solutions in the present invention will be described clearly and completely with reference to the following embodiments, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

(1) Selection and pretreatment of raw materials

Grinding and crushing the collected soil sample, sieving with a 200-mesh sieve, and separating to remove large-particle useless mineral debris in the sample, so that the final particle size of the soil sample is less than 75 mu m; and (3) placing the pyrite tailing (with the particle size of 30-40 mu m) and the soil sample in a stirrer according to the mass ratio of 1:10, and stirring for 5-10 minutes to fully mix the pyrite tailing and the soil sample to obtain a raw material mixture.

(2) Grinding modification

And (3) placing the raw material mixture into a ball mill, and fully grinding to ensure that the final particle size of the mixture is less than 15 mu m.

(3) Press forming and calcining treatment

Putting the mixture after grinding modification into an iron spherical model with the diameter of 2cm, and pressing to form the mixture with the density of 1.8-2.0 g/cm³The spherical mixture of (1). Placing the pressed spherical mixture into a muffle furnace, and calcining at the high temperature of 1200 ℃ for 6-8 hours;

(4) modification of organic substances

The spherical mixture after calcination was immersed in an aqueous solution (mass ratio of mineral mixture to water 1:10), and 5% of cetyltrimethylammonium bromide and 2% of absolute ethanol, which were equivalent to the weight of the mineral, were added to the aqueous solution. And heating the mixed solution in a water bath at 60 ℃ for 2 hours, slowly stirring, filtering, fishing out, washing with deionized water for three times, drying in an oven at 80 ℃ for 3-4 hours, and taking out to obtain the heavy metal and organic matter composite sewage purifying agent.

In the above-described embodiment, in order to ensure the activity of the soil sample, it is preferable that the soil sample be collected in an area under 30cm underground, considering that the surface soil has too low activity through long-term weathering and solarization. Clay minerals such as illite, montmorillonite and chlorite in soil samples are active substances with certain adsorption capacity. Preferably, when the content of the active substances in the soil sample accounts for more than 70% of the total mass of the soil sample, better adsorption and purification effects can be obtained.

The pyrite tailing in the raw material can be selected from pyrite, chalcopyrite, pyrrhotite, bornite and the like. When the content of pyrite mineral in the tailings exceeds 15%, the required sulfur ions and iron ions can be provided. In order to achieve a better mixing effect of the pyrite tailing and the soil sample, the particle size of the pyrite tailing adopted by the invention is preferably 30-40 μm.

Other shapes, such as cubes, cuboids, tetrahedrons, rods and the like, can also be selected for the pressing and shaping in the step (3). Preferably, the pressing density is 1.8-2.0 g/cm³When spherical, the specific surface area is larger, and a better adsorption effect can be provided. Considering that the melting point of the pyrite is 1171 ℃ at most, the calcining temperature is set to be not lower than 1200 ℃, so that various types of molten pyrite can be fully loaded on the surface of the clay mineral, and the passivation effect of the clay mineral on various types of heavy metal ions can be obviously improved.

The quaternary ammonium salt in the step (4) may be cetyltrimethylammonium bromide, dodecyltrimethylammonium bromide, octadecyldimethylbenzylammonium chloride, octadecyltrimethylammonium chloride, etc. Preferably, the cetyltrimethylammonium bromide is selected as an organic modification raw material, and when the addition amount of the cetyltrimethylammonium bromide is 5% of the total mass of the mixture, the modification effect is obvious and more economical and practical.

Comparative example 1

(1) Selection and pretreatment of raw materials

Grinding and crushing the collected soil sample, sieving with a 200-mesh sieve, and separating to remove large-particle useless mineral debris in the sample, so that the final particle size of the soil sample is less than 75 mu m; and (3) placing the pyrite tailing (with the particle size of 30-40 mu m) and the active soil sample in a stirrer according to the mass ratio of 1:10, and stirring for 5-10 minutes to fully mix the pyrite tailing and the active soil sample to obtain a raw material mixture.

(2) Press forming and calcining treatment

Putting the raw material mixture into an iron spherical model with the diameter of 2cm, and pressing to form the raw material mixture with the density of 1.8-2.0 g/cm³The spherical mixture of (1). And (3) placing the pressed spherical mixture in a muffle furnace for high-temperature calcination at 1200 ℃ for 6-8 hours.

(3) Modification of organic substances

The spherical mixture after calcination was immersed in an aqueous solution (mass ratio of mineral mixture to water 1:10), and 5% of cetyltrimethylammonium bromide and 2% of absolute ethanol, which were equivalent to the weight of the mineral, were added to the aqueous solution. And heating the mixed solution in a water bath at 60 ℃ for 2 hours, slowly stirring, filtering, fishing out, washing with deionized water for three times, drying in an oven at 80 ℃ for 3-4 hours, and taking out to obtain the sewage purifying agent.

Comparative example 2

(1) Selection and pretreatment of raw materials

(2) Grinding modification

(3) Pressing and molding, namely putting the mixture after grinding modification into an iron spherical model with the diameter of 2cm, and pressing and molding the mixture with the density of 1.8-2.0 g/cm³The spherical mixture of (1).

(4) Modification of organic substances

The spherical mixture obtained by compression molding was immersed in an aqueous solution (mass ratio of mineral mixture to water 1:10), and 5% by weight of cetyltrimethylammonium bromide and 2% by weight of anhydrous ethanol were added to the aqueous solution. And heating the mixed solution in a water bath at 60 ℃ for 2 hours, slowly stirring, filtering, fishing out, washing with deionized water for three times, drying in an oven at 80 ℃ for 3-4 hours, and taking out to obtain the sewage purifying agent.

Comparative example 3

(1) Selection and pretreatment of raw materials

(2) Grinding modification

(3) Press forming and calcining treatment

Putting the mixture after grinding modification into an iron spherical model with the diameter of 2cm, and pressing and forming the mixture with the density of 1.8-2.0 g/cm³. And (3) placing the pressed spherical mixture in a muffle furnace for high-temperature calcination at 1200 ℃ for 6-8 hours to obtain the sewage purifying agent.

Application example

7 parts of the same wastewater sample are prepared, and each wastewater sample contains the following main pollution components: 25mg/L of benzene, 20mg/L of p-xylene and 15mg/L, Pb 15mg/L, Cr 10mg/L, As 10mg/L, Cd 10mg/L, Hg 2mg/L of chloroform.

The heavy metal and organic matter composite sewage purifying agent prepared in example 1 was added to one wastewater sample at 5g/L, 20g/L and 30g/L, respectively, to obtain application examples 1 to 3. The sewage purifying agents prepared in comparative examples 1 to 3 were added to one wastewater sample at a mixing amount of 30g/L, respectively, to obtain application examples 4 to 6. A sample of the wastewater without any added scavenger was used as a blank control.

After continuously stirring application examples 1-6 at room temperature for 2 hours, the residual amounts of organic contaminants and heavy metal ions in the solution were measured, and the measurement results are shown in the following table:

table 1: the residual amount (mg/L) and removal rate (%) -of heavy metals and organic pollutants in wastewater were simulated in each example

The experimental results of application examples 1-3 show that the removal rate of heavy metal ions and the removal rate of various organic pollutants in sewage are obviously improved along with the increase of the doping amount of the heavy metal and organic matter composite sewage purifying agent, and when the adding amount of the purifying agent is 30g/L, the removal rate of various organic pollutants is 87.8-93.67%, and the removal rate of heavy metal ions is 91.2-96.4%. And in consideration of comprehensive economy, the total purification effect is better when the adding amount of the mineral purifying agent in the simulated wastewater is 20-30 g/L.

The comparison experiment results of the application examples 4-6 and the application example 1 show that under the condition of no grinding treatment, the purification effect of the organic matter is reduced to 71.4-84.13%, and the purification effect of the heavy metal ions is reduced to 59.9-75%; under the condition of no molten pyrite load, the purification effect of clay minerals on heavy metals is weakened, the removal rate is reduced to 50.3-88.5%, and the influence on Cr (50.3%) and As (63.5%) is most obvious; under the condition of no organic matter modification, the capability of clay minerals for purifying organic pollutants is also obviously reduced, and the processing capability of various organic matters is reduced to 6.4-11.5%.

The experimental results show that in the preparation method provided by the invention, the steps of grinding treatment, high-temperature calcination and organic matter modification are absent, and the three steps are mutually matched to generate a synergistic effect, so that the comprehensive treatment capacity of the purifying agent on heavy metals and organic pollutants is improved.

While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.

Claims

1. A preparation method of a heavy metal and organic matter composite sewage purifying agent comprises the following steps:

s4, adding the calcined raw material mixture and quaternary ammonium salt into an aqueous solution according to the mass ratio of 100: 3-10, stirring, filtering, washing and drying to obtain the heavy metal and organic matter composite sewage purifying agent.

2. The preparation method according to claim 1, wherein the particle size of the pyrite tailing is 30-40 μm.

3. The method according to claim 1, wherein the soil sample has a particle size of less than 75 μm and the content of active material in the soil sample is not less than 70%.

4. The method according to claim 3, wherein the active substance comprises at least illite, montmorillonite and chlorite.

5. The method according to claim 1, wherein in step S3, the ground raw material mixture is pressed to have a density of 1.8 to 2.0g/cm³Spherical raw material mixture with a diameter of 2 cm.

6. The method according to claim 1, wherein in step S4, the quaternary ammonium salt is one of cetyltrimethylammonium bromide, dodecyltrimethylammonium bromide, octadecyldimethylbenzylammonium chloride, and octadecyltrimethylammonium chloride.

7. The method according to claim 6, wherein the quaternary ammonium salt is cetyltrimethylammonium bromide, and a mass ratio of the calcined raw material mixture to cetyltrimethylammonium bromide is 100: 5.

8. The method according to claim 1, wherein in step S4, the stirring temperature is 60 ℃, the stirring time is 2 hours, the drying temperature is 80 ℃, and the drying time is 3-4 hours.

9. The application of the heavy metal and organic matter composite sewage purifying agent prepared by the preparation method of any one of claims 1 to 8 in purifying underground water compositely polluted by heavy metals and organic matters.

10. The application of the heavy metal and organic matter composite sewage purifying agent as claimed in claim 9, wherein the addition amount of the heavy metal and organic matter composite sewage purifying agent is 20-30 g/L.