Shalerite-based photocatalytic material as well as preparation method and application thereof

A kind of sphalerite-based photocatalytic material and its preparation method and application technical field

[0001] The present invention relates to the technical field of wastewater treatment, in particular to the field of photocatalytic degradation of organic wastewater.

Background technique

In modernization, more and more are demanded to nonferrous metals, and the metallurgical industry develops rapidly. The metallurgical industry has a wide range of products, and the production process is divided into series, which discharges a large amount of waste water, which is one of the main waste water that pollutes the environment. In 2010, the national non-ferrous metallurgical wastewater discharge was 730 million tons, of which the wastewater discharged during the development and utilization of non-ferrous metal mineral resources accounted for about 3% of the total industrial wastewater discharge in the country. Due to the use of a large amount of concentrated acid, strong alkali and extractant in the hydrometallurgical process, the resulting metallurgical wastewater contains high content of inorganic salts, heavy metals and refractory organic matter, making the treatment difficult. Common metallurgical wastewater treatment methods include coagulation sedimentation, adsorption, and membrane separation. The removal effect of organic matter by coagulation precipitation method is not ideal; the removal effect of organic matter by adsorption method is good, but the cost is high, and the adsorbent is not easy to regenerate; the membrane method has poor acid and alkali resistance and is easy to block. Therefore, the development of efficient and economical non-ferrous metallurgical wastewater treatment technology has become a top priority.

Because of its high degradation efficiency, simple operation and low cost, photocatalytic technology has shown huge advantages in wastewater treatment, and it mainly utilizes semiconductor catalytic material to absorb light to generate electron-hole pairs to induce oxidation and reduction reaction to achieve the degradation of organic pollutants. Among them, the activity of photocatalysts plays a vital role in the degradation of pollutants, so the synthesis and composite modification of green catalysts with stable performance have always been a research hotspot. However, the photocatalytic degradation of high-salt organic wastewater in non-ferrous metallurgy usually exhibits extremely low activity, because these synthetic catalysts are extremely unstable in high-salt environments and are prone to agglomeration and deactivation. Therefore, the application of photocatalytic technology to treat non-ferrous metallurgical wastewater has not been reported so far.

Contents of the invention

The object of the present invention is to provide a kind of preparation method of sphalerite-based photocatalytic material, aiming at utilizing natural minerals to prepare high-performance photocatalyst.

[0005] The second purpose of the present invention is to provide the natural mineral type sphalerite-based photocatalytic material prepared by the preparation method.

[0006] The third object of the present invention is to provide the application of the zinc blende-based photocatalytic material prepared by the preparation method for the photocatalytic degradation of organic wastewater, especially organic extraction wastewater.

A kind of preparation method of sphalerite-based photocatalytic material, sphalerite (the present invention is also called sphalerite mineral) is pretreated through hydrofluoric acid in advance, and pretreated sphalerite and cationic polymer Roasting at 500-900°C after mixing to obtain the sphalerite-based photocatalytic material;

The mass ratio of described sphalerite and cationic polymer is 1:1.5~1:4.

The present invention research finds, sphalerite mineral is different from analytical pure material, and its composition is complicated, although it has certain photocatalytic beneficial element, also there is no lack of a large amount of photocatalytic useless and catalytic poisoning element, in addition, described The components of natural minerals are tightly embedded, the active sites are covered, and the photocatalytic activity is low. Therefore, in order to successfully prepare high-performance photocatalysts using sphalerite minerals, it is necessary to solve technical difficulties such as the selectivity of catalytic components and the exposure of active sites. Aiming at this technical difficulty, the inventor found through in-depth research that the original ore of sphalerite was pretreated in HF innovatively, and further cationic polymerization

The joint control of the parameters of object assembly modification, roasting treatment and treatment process can unexpectedly achieve synergy, highly selectively control the hybridization of beneficial components, and achieve surface modification treatment to expose more active sites. The study found that the photocatalytic performance of the prepared mineral-based photocatalyst can be effectively improved through the combination of the process and parameters.

[0010] In the present invention, described sphalerite is a natural mineral.

[0011] In the present invention, any existing content of sphalerite minerals can adopt the inventive method to prepare high-performance photocatalyst.

In the present invention, in described sphalerite mineral, ZnS 92~95wt.%, iron element is 1~5wt.%; Surplus is silicon dioxide.

In the present invention, before pretreatment, sphalerite can be carried out earlier crushing and ore grinding process;

Preferably, the particle diameter of sphalerite is controlled to be less than 38um;

Preferably, sphalerite is carried out liquid phase pretreatment as in hydrofluoric acid solution, then through solid-liquid separation process, obtains the sphalerite of pretreatment;

Preferably, the concentration of hydrofluoric acid solution is 1~3M;

Preferably, the time of pretreatment is 30~60min;

In the present invention, under described HF surface treatment, further coordinate the surface assembly of cationic polymer and the control of ratio, contribute to synergistically improving the photocatalytic performance of mineral-based photocatalyst.

As preferably, described cationic polymer is at least one in polyethylene imine, polydiallyl dimethyl ammonium chloride, cationic polyacrylamide;

The molecular weight of cationic polymer does not have special requirement, for example can be 1~12 million;

Preferably, the mass ratio of described sphalerite and cationic polymer is 1:2~1:3.5. The research found that under this preferred ratio, it can be further coordinated with other operations and parameters, and the catalytic performance of the prepared photocatalyst can be further improved.

[0022] In the present invention, pretreated sphalerite and cationic polymer can be mixed based on existing means. For example, the pretreated sphalerite and the cationic polymer are mixed in a liquid phase, followed by solid-liquid separation, and the obtained mixture is subsequently roasted.

Preferably, the solvent of liquid phase mixing process is the mixed solvent of water, water-organic solvent; Described organic solvent is preferably at least one in the alcohol of C1~C4, acetone;

Preferably, in described solvent, the volume content of water is 20%~40%.

Described liquid phase mixing can be carried out at room temperature, for example, its temperature can be 10~45 °C.

In the present invention, under the joint surface treatment of described HF and cationic polymer, further coordinate the joint control of roasting and temperature, can further synergistically improve the performance of the sphalerite-based photocatalyst that makes.

As preferably, the temperature of roasting process is 650~750 °C. The study found that under the preferred calcination, it can be further coordinated with other operations and parameters, and the catalytic performance of the prepared photocatalyst can be further improved.

[0028] The atmosphere in the firing stage may be a protective atmosphere, such as at least one of nitrogen and an inert gas.

The time of roasting can be adjusted as required, for example, the roasting time is preferably 2~6h.

[0030] The present invention also provides the zinc blende-based photocatalytic material prepared by the preparation method.

In the present invention, described innovative preparation method can give the special microscopic physics of described product and chemical structure, can obtain special photocatalyst, more importantly, the photocatalyst that this preparation method makes possesses excellent Photocatalytic performance.

[0032] The present invention also provides the application of the sphalerite-based photocatalytic material prepared by the preparation method as a photocatalyst for photocatalytic degradation of organic pollutants in organic wastewater.

Preferred application, described organic waste water is organic extraction waste water, wherein dissolves organic extractant; Described organic extractant is for example P204, P507 etc.

Preferably, the initial TOC 400~450mg/L of described organic waste water.

[0035] The scheme of the present invention still has an excellent effect on the high-salinity body, for example, in the organic waste water, the salt content can be greater than or equal to 30g/L; preferably 30~100g/L.

Preferred application, the consumption of photocatalyst is 1~4g/L;

Preferably, the illumination intensity 52.19~123.29mW/cm of photocatalytic stage²；

Preferably, the solution initial pH=2~4 of photocatalytic stage.

In the present invention, photocatalysis time can be adjusted based on treatment effect, for example, the time of photocatalysis is such as 120~

180min.

Beneficial effect

(1) through the combined control of HF ionic polymer and its ratio-roasting and temperature, synergy can be realized, sphalerite mineral surface can be processed, and selective regulation and control phase and composition can synergistically improve the manufacturing process The photocatalytic performance of the obtained photocatalyst.

(2) photocatalyst of the present invention has excellent photocatalytic activity to the high-salt wastewater of metallurgy aspect. In addition, it also has excellent photocatalytic stability.

(3) The present invention realizes the high-value utilization of minerals, and the treatment process is mild, simple to operate, and easy to industrial scale-up.

Description of drawings:

Fig. 1 is scanning electron micrograph after modification of sphalerite (a) before (a) modification that embodiment 1 makes

Fig. 2 is the XRD figure before and after the sphalerite modification that embodiment 1 makes.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the embodiments of the present invention are described in detail below, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby the present invention The scope of protection is more clearly defined.

Following case, except special statement, the parameter characteristic of the polymer adopted is as follows:

Polyethyleneimine, molecular formula (C₂h₅N)_no, molecular weight 10,000, 99%, purchased from McLean reagent;

Polydiallyl dimethyl ammonium chloride, molecular formula: (C₈h₁₆cIN)_no, molecular weight 200,000-350,000, 20wt.%, purchased from McLean's reagent;

Cationic polyacrylamide, molecular formula: (C₃h₅NO)_no, with a molecular weight of 12 million, purchased from Tianjin Zhiyuan Chemical Reagent Co., Ltd.;

Anionic polyacrylamide, molecular formula: (C₃h₅NO)_no, Molecular weight 12 million, purchased from McLean reagent.

The organic matter concentration in the water sample adopts total organic carbon (TOC) analyzer to measure, according to national standard GB13193-91 water quality non-dispersive infrared absorption method.

Embodiment 1

The present embodiment provides a kind of method utilizing modified natural sphalerite photocatalytic degradation organic extraction waste water, specifically

Proceed as follows:

(1) sphalerite modification. Take a natural sphalerite from a certain place for crushing, grinding, and screening to obtain particles with a particle size smaller than

38um natural sphalerite powder. The composition of sphalerite here is shown in Table 1 by semi-quantitative detection and analysis.

The main component element ZnSFeSi of table 1 sphalerite

Mass fraction/% 63.52 30.74 4.37 0.95

Mineral sample is placed in the hydrofluoric acid solution of 3M and soaks 30min, then solid-liquid separation, vacuum drying. Take 1g of the pretreated ore sample, add 501nL water/ethanol (volume ratio: 1/4), and then add 2g polyethyleneimine. The mixed solution is ultrasonicated for 30min, then stirred and reacted at room temperature for 3h, followed by solid-liquid separation and vacuum drying. An organic/inorganic surface hybrid composite is obtained. The composite was placed in a tube furnace in a gas atmosphere, and calcined at a calcining temperature of 650 °C for 5 hours to obtain a catalyst.

(2) modified sphalerite photocatalytic degradation organic extraction wastewater. Take 100mL of organic extraction wastewater produced during the wet recovery and extraction process of a lithium-ion battery in a certain factory and add it to a double-layer beaker, adjust the pH of the wastewater to 3 with a solution of HC1 with a concentration of 1mol/L, then weigh 2g/L of catalyst into the In the reactor, after 30 minutes of adsorption and desorption equilibrium under dark conditions, the photocatalytic reaction was carried out for 180 minutes under visible light irradiation with an illumination intensity of 90.5 mW/cm2, and samples were taken every 30 minutes to measure the TOC value. The organic extraction waste water of this plant, wherein the extraction related components are P204/P507 and kerosene, etc., TOC = 430mg/L, in addition, in the waste water, the concentration of sodium sulfate is 40~45g/L, and the unmodified sphalerite is under the same conditions The photocatalytic wastewater treatment experiment was carried out.

Fig. 1 is scanning electron micrograph before and after modification of sphalerite that embodiment 1 makes, as can be seen from Fig. 1, obtains porous sphalerite after cationic polymer assembly modification, roasting treatment, this is for catalyst specific surface area There is a significant improvement, the active sites are fully exposed, and the photocatalytic activity is improved. Figure 2 is the XRD pattern of sphalerite before and after modification obtained in Example 1. It can be seen that the mineral phase and composition can be effectively controlled, and at the same time the ZnFeO4 diffraction peak appears, indicating that the beneficial element components of sphalerite form ZnS/ZnFeO after roasting , heterostructure, which facilitates the efficient separation of photogenerated electrons and holes in the catalyst. It can be seen that the photocatalytic performance of sphalerite has been significantly improved by surface pore creation and component regulation.

The present embodiment adopts modified sphalerite photocatalytic treatment waste water, and during 180 μm, 1'00 removal rate can reach 70.14%. Unmodified sphalerite removal rate only has 34.81%.

Embodiment 2

The present embodiment provides a kind of method utilizing modified natural sphalerite photocatalytic degradation organic extraction waste water, concrete steps are as follows:

(1) sphalerite modification. Take a natural sphalerite from a certain place for crushing, grinding, and screening to obtain particles with a particle size smaller than

38um natural sphalerite powder. After semi-quantitative detection and analysis, the composition of sphalerite here is shown in Table 2.

The main component element ZnSFeSi of table 2 sphalerite

Mass fraction/% 62.84 29.91 3.58 1.09

Mineral sample is placed in 2M hydrofluoric acid solution and soaks 50min, then solid-liquid separation, vacuum drying. Take 1g of the pretreated mineral sample, add 501nL water/ethanol (volume ratio is 1/4), then add 3g polyethyleneimine, the mixed solution is ultrasonicated for 30min, stirred and reacted at room temperature for 3h, followed by solid-liquid separation and vacuum drying. An organic/inorganic surface hybrid composite is obtained. The composite was placed in a tube furnace in a gas atmosphere and calcined at a calcination temperature of 750 °C for 4 hours to obtain a catalyst.

(2) modified sphalerite photocatalytic degradation organic extraction wastewater. With embodiment 1.

The present embodiment adopts modified sphalerite photocatalytic treatment waste water, and during 180 μm, 1'00 removal rate can reach 71.35%.

Embodiment 3

The present embodiment provides a kind of method utilizing modified natural sphalerite photocatalytic degradation organic extraction waste water, concrete steps are as follows:

(1) sphalerite modification. Take a natural sphalerite from a certain place for crushing, grinding, and screening to obtain particles with a particle size smaller than

38um natural sphalerite powder. After semi-quantitative detection and analysis, the composition of sphalerite here is shown in Table 3.

The main component of table 3 sphalerite

Zn S Si

[0°74] mass fraction/% 63.34 30.42 2.79 1.12

Ore sample is placed in hydrofluoric acid solution and soaks 60min, then solid-liquid separation, vacuum drying. Take 1g of pretreated ore sample, add 501nL water/ethanol (volume ratio: 1/4), then add 3.5g polyethyleneimine, the mixed solution is ultrasonicated for 30min, then stirred and reacted at room temperature for 3h, followed by solid-liquid separation and vacuum drying , to obtain organic/inorganic surface hybrid composites. The composite was placed in a tube furnace in a gas atmosphere and calcined at a calcination temperature of 700 °C for 4 hours to obtain the catalyst.

(2) modified sphalerite photocatalytic degradation organic extraction wastewater. Same as Example 1

The present embodiment adopts modified sphalerite photocatalytic treatment waste water, and during 180min, TOC removal rate can reach 72.65%.

Embodiment 4

Compared with Example 1, the only difference is that step (1) adds 1.5g polyethyleneimine by the mass ratio of sphalerite and cationic polymer at 1:1.5. Using the modified sphalerite obtained in this example to photocatalytically treat wastewater, the TOC removal rate was 64.19% in 180 minutes.

Embodiment 5

[0081] Compared with Example 1, the only difference is that step (1) adds 4g polyethyleneimine to 1:4 by the mass ratio of sphalerite and cationic polymer. Using the modified sphalerite obtained in this example to photocatalytically treat wastewater, the TOC removal rate was 66.80% in 180 minutes.

Embodiment 6

Compared with Example 1, the only difference is that the calcination temperature of step (1) is 500°C. Using the modified sphalerite obtained in this example to photocatalytically treat wastewater, the removal rate of 1'0(3 was 65.53% at 180111 m.

Embodiment 7

Compared with Example 1, the only difference is that the calcination temperature of step (1) is 900°C. Using the modified sphalerite obtained in this example to photocatalytically treat wastewater, the removal rate of 1'0(3 was 64.79% at 180111 m.

Embodiment 8

[0087] Compared with Example 1, the only difference is that cationic polyacrylamide is used to replace the PEI. Other operations and parameters are the same as in Example 1.

The result finds that the removal rate of TOC is 69.73%.

Embodiment 9

Compared with Example 1, the difference only lies in the condition of regulating and controlling photocatalysis, and the step (2) of difference is: the pH of waste water is adjusted to be 4 with the solution of the HCl of 1mol/L with concentration, then takes by weighing 3g/L Catalysts were placed in the reactor under dark conditions

After 30 minutes of adsorption and desorption equilibrium, the light intensity is 123.29mW/cm²The photocatalytic reaction was carried out under visible light irradiation for 180 minutes, and samples were taken every 30 minutes to measure the TOC value. At 180 minutes, the removal rate of TOC was 71.23%. [0091] Comparative Example 1: [0092] Compared with Example 1, the difference is only that HF pretreatment is not carried out, and other parameters and tests are the same as Example 1.

It was found that the removal rate of TOC was 51.84%. [0094] Comparative Example 2 [0095] Compared with Example 1, the only difference is that analytically pure ZnS is used to replace the sphalerite mineral. Using the modified sphalerite obtained in this example to photocatalytically treat wastewater, the removal rate of TOC was 45.67% in 180 minutes. Compared with the photocatalyst prepared by modification of natural sphalerite containing heteroelement iron, its photocatalytic activity is significantly lower, and the removal rate of TOC in wastewater is reduced. Comparative example 3

Compared with Example 1, the only difference is that step (1) adds 1g polyethyleneimine by the mass ratio of sphalerite and cationic polymer at 1:1. Using the modified sphalerite obtained in this example to photocatalytically treat wastewater, the removal rate of TOC was 52.10% in 180 minutes. Compared with Example 1, the effect of this comparative case becomes significantly worse. Comparative example 4

[0099] Compared with Example 1, the only difference is that step (1) adds 4.5g polyethyleneimine to the mass ratio of sphalerite and cationic polymer at 1:4.5. Using the modified sphalerite obtained in this example to photocatalytically treat wastewater, the removal rate of TOC was 57.54% in 180 minutes. Compared with Example 1, the effect of this comparative case becomes significantly worse. Comparative example 5

[0101] Compared with Example 1, the only difference is that the calcination temperature of step (1) is 400°C. Using the modified sphalerite obtained in this example to photocatalytically treat wastewater, the TOC removal rate was 47.32% in 180 minutes. Compared with Example 1, the effect of this comparative case becomes significantly worse.

Comparative example 6

[0103] Compared with Example 1, the only difference is that the calcination temperature of step (1) is 1000°C. Using the modified sphalerite obtained in this example to photocatalytically treat wastewater, the removal rate of TOC was 39.87% in 180 minutes. Compared with Example 1, the effect of this comparative case becomes significantly worse.

Comparative example 7

[0105] Compared with Example 1, the only difference is that the anionic polymer polyacrylamide is used to replace the PEI. Other operations and parameters are the same as in Example 1. The removal rate of TOC is 40.83%. Comparative example 8

[0107] Compared with Example 1, the only difference is that other acids are used for pretreatment, specifically 3M HCl to replace the HF. Other operations and parameters are the same as in Example 1. The removal rate of TOC is 39.57%. Embodiment 9

Compared with Example 1, the difference is that the sphalerite after the reaction is reclaimed three times and reused, and the change of the TOC concentration in the water body before and after the reaction is measured each time. It was found that the removal rate of TOC decreased from 34.81 to 10.47 % after the unmodified sphalerite photocatalyst was reused three times. After repeated use of the modified sphalerite three times, the TOC removal rate can still reach 68.75%, and the catalyst itself still maintains a relatively good activity and has better cycle stability.

[0110] The above descriptions are only some specific embodiments of the present invention, and do not limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.