An MIL-53(Fe, Al, Cr) photocatalyst prepared from chromite slag, and its preparation method and application

Abstract

The present invention discloses a MIL-53(Fe, Al, Cr) photocatalyst prepared from chromium slag, its preparation method and application. The acid leaching method is used to leach the metal elements in the chromium slag into the solution, and the iron, aluminum and chromium in the chromium slag are effectively recovered by the hydrothermal synthesis method to prepare a MIL-53(Fe, Al, Cr) photocatalyst with a specific surface area as high as 706.12 cm 2 / g, and it is applied to the treatment of organic wastewater, with a wastewater degradation rate as high as 94.14%, realizing the resource utilization of potential metals in chromium slag.

Description

Technical Field

[0001] The present invention belongs to the technical field of photocatalysts, and particularly relates to a MIL-53(Fe, Al, Cr) photocatalyst prepared from chromium slag, a preparation method thereof, and an application thereof. Background Art

[0002] Deeply implementing the concepts of green and low-carbon development, promoting the resource utilization of hazardous solid waste in China has become a major trend of sustainable development. Chromium slag is a heavy metal carcinogenic hazardous waste with strong toxicity, and it has been listed as the top of hazardous solid waste in various countries. If the chromium slag is not properly disposed of, it will cause serious environmental pollution and endanger human life safety.

[0003] In recent years, it has been found that metal-organic framework materials (MOFs) have received extensive attention from researchers in the fields of adsorption and catalysis due to their high specific surface area and porosity. Among them, the Laves framework materials (MIL series) have shown excellent photocatalytic performance due to their excellent stability and adjustable pore structure. At the same time, MIL-53(Fe) has characteristics such as high efficiency, low toxicity, and visible light response, and is often used as a photocatalyst for photocatalytic treatment of wastewater. Therefore, how to effectively treat chromium slag solid waste and its resource utilization is the fundamental requirement for solving environmental pollution problems, saving resources, and maintaining the sustainable development of the chromium salt industry. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: to provide a MIL-53(Fe, Al, Cr) photocatalyst prepared from chromium slag, a preparation method thereof, and an application thereof, so as to solve the technical problem of waste of chromium slag resources.

[0005] To achieve the above object, the technical solution adopted by the present invention is: to provide a preparation method of a MIL-53(Fe, Al, Cr) photocatalyst prepared from chromium slag, comprising the following steps:

[0006] S1: Wash the chromium slag with water, and then filter and dry it to obtain a washed slag; the composition of the chromium slag includes 40-50 wt% Fe2O3, 20-30 wt% Al2O3, 10-20 wt% Cr2O3, and 0-10 wt% impurities;

[0007] S2: Dissolve the washed slag in an acidic solvent, filter after reaction to obtain an acid leaching solution;

[0008] S3: Dissolve phthalic acid in an organic solvent, then add the acid leaching solution and continue to react, and obtain the MIL-53(Fe, Al, Cr) photocatalyst after suction filtration and drying.

[0009] Based on the above technical solution, the present invention can also be improved as follows:

[0010] Furthermore, step S1 also includes screening the chromium slag to obtain chromium slag particles before water washing, and the diameter of the chromium slag particles is 35 - 150 μm.

[0011] Furthermore, in step S1, the solid-liquid ratio of chromium slag to water is 1 g: 10 - 20 mL, the water washing temperature is 60 - 80 °C, and the water washing time is 20 - 40 min.

[0012] Furthermore, in step S2, the acidic solvent is concentrated hydrochloric acid or concentrated sulfuric acid with a concentration of 36 - 38 wt%, the solid-liquid ratio of the water-washed slag to the acidic solvent is 1 g: 2 - 5 mL, the reaction temperature is 110 - 130 °C, and the reaction time is 5 - 8 h.

[0013] Furthermore, in step S3, the organic solvent is N,N-dimethylformamide; the mixing ratio of phthalic acid, organic solvent and acid leaching solution is 1 g: 200 - 300 mL: 1 mL, the reaction temperature is 130 - 170 °C, and the reaction time is 12 - 18 h.

[0014] Furthermore, the mixing ratio of phthalic acid, organic solvent and acid leaching solution is 1 g: 280 mL: 1 mL, the reaction temperature is 150 °C, and the reaction time is 15 h.

[0015] The present invention also discloses a MIL-53(Fe,Al,Cr) photocatalyst prepared by the preparation method of the MIL-53(Fe,Al,Cr) photocatalyst prepared from chromium slag.

[0016] The present invention also discloses the application of the MIL-53(Fe,Al,Cr) photocatalyst in the treatment of organic wastewater.

[0017] Based on the above technical solutions, the present invention can also be improved as follows:

[0018] Furthermore, the application includes the following steps: mixing the MIL-53(Fe,Al,Cr) photocatalyst with organic wastewater according to a mass ratio of 1: 50 - 200, first performing a dark reaction, and then adding 0 - 10 mM hydrogen peroxide for degradation reaction by light irradiation.

[0019] Furthermore, the concentration of the organic wastewater is 10 - 40 mg / L, the dark reaction time is 20 - 40 min, the light irradiation intensity is 300 - 350 W, and the light irradiation time is 50 - 70 min.

[0020] The present invention has the following beneficial effects:

[0021] (1) The present invention uses an acid leaching method to leach metal elements in chromium slag into the solution, and prepares a specific surface area as high as 706.12 cm 2The MIL-53(Fe, Al, Cr) photocatalyst of / g provides a new development direction for the resource utilization of chromium slag, achieving the goal of "treating waste with waste".

[0022] (2) The MIL-53(Fe, Al, Cr) photocatalyst prepared by the present invention can effectively treat organic wastewater with a concentration of 10 - 40 mg / L, and the degradation rate is as high as 94.14%.

[0023] (3) The present invention uses chromium slag, a heavy metal hazardous waste, as a raw material, which not only solves the traditional way of stacking and disposing of chromium slag, but also effectively utilizes its potential metal resources, reduces the treatment cost, provides a new idea for photocatalytic treatment of dye wastewater, and has the characteristics of environmental protection, low cost, and high efficiency. Description of the Drawings

[0024] Figure 1 It is the N2 adsorption - desorption isotherm curve of the photocatalyst prepared in Example 1.

[0025] Figure 2 It is the kinetic fitting curve of the photocatalyst for different initial concentrations of RhB solution.

[0026] Figure 3 It is the kinetic fitting curve of different photocatalyst concentrations for RhB solution.

[0027] Figure 4 It is the photocatalytic degradation curve of the photocatalyst for different initial concentrations of RhB solution.

[0028] Figure 5 It is the photocatalytic degradation curve of different photocatalyst concentrations for RhB solution. Detailed Embodiments

[0029] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention. For those not specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are followed. For the reagents or instruments not specified for the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0030] Example 1:

[0031] A preparation method of a MIL-53(Fe, Al, Cr) photocatalyst prepared using chromium slag includes the following steps:

[0032] S1: First, screen the chromium slag to obtain chromium slag particles with a diameter of 200 μm. The composition of the chromium slag includes 40 wt% Fe2O3, 30 wt% Al2O3, 20 wt% Cr2O3, and 10 wt% impurities. Wash the chromium slag with water at 70 °C for 30 min, then filter and dry it to obtain the washed slag. The solid-liquid ratio of the chromium slag to water is 1 g: 15 mL.

[0033] S2: Dissolve the washed slag in concentrated hydrochloric acid with a concentration of 36 wt%, then place it in a homogeneous reactor for reaction, and filter to obtain the acid leaching solution. The solid-liquid ratio of the washed slag to concentrated hydrochloric acid is 1 g: 3 mL, the reaction temperature is 120 °C, and the reaction time is 6 h.

[0034] S3: Dissolve phthalic acid in N,N-dimethylformamide, then add the acid leaching solution and continue the reaction. After suction filtration and drying, obtain the MIL-53(Fe,Al,Cr) photocatalyst. The ratio of phthalic acid, N,N-dimethylformamide, and the acid leaching solution is 1 g: 260 mL: 1 mL, the reaction temperature is 150 °C, and the reaction time is 16 h.

[0035] This example also provides the application of the MIL-53(Fe,Al,Cr) photocatalyst in the treatment of organic wastewater, including the following steps: Mix the MIL-53(Fe,Al,Cr) photocatalyst with a RhB solution with a concentration of 30 mg / L according to a mass ratio of 1:50, first carry out a dark reaction for 30 min, then add 10 mM hydrogen peroxide, and carry out a degradation reaction through light irradiation. The light intensity is 300 W, and the light irradiation time is 60 min.

[0036] Example 2:

[0037] A preparation method of a MIL-53(Fe,Al,Cr) photocatalyst prepared using chromium slag, including the following steps:

[0038] S1: First, screen the chromium slag to obtain chromium slag particles with a diameter of 150 μm. The composition of the chromium slag includes 50 wt% Fe2O3, 30 wt% Al2O3, and 20 wt% Cr2O3. Wash the chromium slag with water at 60 °C for 40 min, then filter and dry it to obtain the washed slag. The solid-liquid ratio of the chromium slag to water is 1 g: 20 mL.

[0039] S2: Dissolve the washed slag in concentrated sulfuric acid with a concentration of 38 wt%, then place it in a homogeneous reactor for reaction, and filter to obtain the acid leaching solution. The solid-liquid ratio of the washed slag to concentrated hydrochloric acid is 1 g: 2 mL, the reaction temperature is 130 °C, and the reaction time is 8 h.

[0040] S3: Dissolve phthalic acid in N,N-dimethylformamide, then add the acid leaching solution and continue the reaction. After suction filtration and drying, obtain the MIL-53(Fe,Al,Cr) photocatalyst; the ratio of phthalic acid, N,N-dimethylformamide, and the acid leaching solution is 1 g: 300 mL: 1 mL, the reaction temperature is 170 °C, and the reaction time is 12 h.

[0041] This example also provides the application of the MIL-53(Fe,Al,Cr) photocatalyst in the treatment of organic wastewater, including the following steps: Mix the MIL-53(Fe,Al,Cr) photocatalyst with a RhB solution with a concentration of 10 mg / L according to a mass ratio of 1:100, first carry out a dark reaction for 20 min, and then carry out a degradation reaction through light irradiation; the light intensity is 350 W, and the light irradiation time is 70 min.

[0042] Example 3:

[0043] A preparation method of a MIL-53(Fe,Al,Cr) photocatalyst prepared from chromite slag includes the following steps:

[0044] S1: First screen the chromite slag to obtain chromite slag particles with a diameter of 220 μm. The composition of the chromite slag includes 50 wt% Fe2O3, 20 wt% Al2O3, 10 wt% Cr2O3, and 10 wt% impurities; wash the chromite slag with water at 80 °C for 20 min, and then filter and dry to obtain the washed slag. The solid-liquid ratio of the chromite slag to water is 1 g: 20 mL;

[0045] S2: Dissolve the washed slag in 37 wt% concentrated hydrochloric acid, then place it in a homogeneous reactor for reaction, and filter to obtain the acid leaching solution; the solid-liquid ratio of the washed slag to concentrated hydrochloric acid is 1 g: 5 mL, the reaction temperature is 130 °C, and the reaction time is 8 h;

[0046] S3: Dissolve phthalic acid in N,N-dimethylformamide, then add the acid leaching solution and continue the reaction. After suction filtration and drying, obtain the MIL-53(Fe,Al,Cr) photocatalyst; the ratio of phthalic acid, N,N-dimethylformamide, and the acid leaching solution is 1 g: 300 mL: 1 mL, the reaction temperature is 130 °C, and the reaction time is 8 h.

[0047] This example also provides the application of the MIL-53(Fe,Al,Cr) photocatalyst in the treatment of organic wastewater, including the following steps: Mix the MIL-53(Fe,Al,Cr) photocatalyst with a RhB solution with a concentration of 40 mg / L according to a mass ratio of 1:200, first carry out a dark reaction for 40 min, then add 10 mM hydrogen peroxide, and carry out a degradation reaction through light irradiation; the light intensity is 330 W, and the light irradiation time is 50 min.

[0048] Experimental example:

[0049] Taking Example 1 as the experimental example.

[0050] 1. Specific surface area detection

[0051] The specific surface area, pore volume and average pore diameter data of the MIL-53(Fe,Al,Cr) photocatalyst are shown in Table 1. The specific surface area and pore size of the photocatalyst determine that more active sites are exposed on its surface during the reaction, thereby accelerating the mass transfer ability of the reaction. Therefore, the N2 adsorption-desorption isotherm experiment was used for analysis, and the results are as Figure 1 shown. It was observed from the figure that the N2 adsorption-desorption isotherm of the MIL-53(Fe,Al,Cr) photocatalyst is similar to the properties of the type-IV isotherm, showing a hysteresis loop in the higher range of p / p o , indicating that the MIL-53(Fe,Al,Cr) photocatalyst has the properties of a mesoporous structure.

[0052] Table 1 Specific surface area, pore volume and average pore diameter data of the photocatalyst in Example 1

[0053] <![CDATA[Specific surface area (cm 2 / g)]]> 706.12 <![CDATA[Total pore volume (cm 3 / g)]]> 0.63 Average pore diameter (nm) 11.93

[0054] 2. Degradation rate

[0055] During the process of the MIL-53(Fe,Al,Cr) photocatalyst catalyzing the decomposition of the RhB solution, 3 mL of the sample solution was taken every 10 min, centrifuged for 5 min at a centrifuge speed of 8000 rpm, then filtered using a 0.22 μm nylon syringe filter, and finally the absorbance of the sample was scanned with a UV-visible spectrophotometer, and the maximum absorption peak was selected at 664 nm, and the change in the RhB concentration was recorded. The degradation rate of RhB was calculated, and the calculation formula is as follows:

[0056]

[0057] In the formula, C0 (mg / L) is the initial concentration of RhB when adsorption equilibrium is reached, C t (mg / L) is the RhB concentration at t min of the reaction, and D represents the degradation rate of RhB; the calculation results are shown in Table 2.

[0058] Table 2 RhB degradation rate data in Example 1

[0059]

[0060] The MIL-53(Fe,Al,Cr) photocatalyst can effectively treat organic wastewater, and the degradation rate is as high as 94.14%, realizing resource reuse.

[0061] 3. Fitting of Pseudo-First-Order Kinetics Model Data

[0062] The pseudo-first-order kinetics model (-ln(C t / C0) = kt) was used to fit the photocatalytic reaction data. As Figure 2 and Figure 3 shown, when the concentration of RhB was 10 mg / L, 20 mg / L, 30 mg / L, and 40 mg / L, the degradation rates were 0.036 mg / (L·min), 0.046 mg / (L·min), 0.048 mg / (L·min), and 0.046 mg / (L·min), respectively. The results showed that as the initial concentration of RhB increased, the degradation rate showed an upward trend. The reason for this phenomenon may be that the higher the initial concentration of RhB, the faster the reaction rate between the hydroxyl radicals formed by electron-hole pairs and RhB, and the results also conform to the principle of the pseudo-first-order kinetics model.

[0063] As Figure 4 and Figure 5 shown, through kinetic analysis, it can be obtained that when the dosage of photocatalyst was 0.05 g / L, 0.1 g / L, 0.15 g / L, 0.2 g / L, and 0.025 g / L, the degradation rates were 0.014 mg / (L·min), 0.028 mg / (L·min), 0.040 mg / (L·min), 0.048 mg / (L·min), and 0.045 mg / (L·min), respectively. The results indicated that as the dosage of photocatalyst gradually increased, more hydroxyl radicals were generated in the photo-Fenton reaction system, which contributed to the further degradation of RhB.

[0064] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of an MIL-53(Fe,Al,Cr) photocatalyst prepared by using chromium slag, characterized in that, It includes the following steps: S1: Wash the chromium slag with water, and then filter and dry it to obtain the washed slag; the composition of the chromium slag includes 40 - 50 wt% Fe2O3, 20 - 30 wt% Al2O3, 10 - 20 wt% Cr2O3, and 0 - 10 wt% impurities; S2: Dissolve the washed slag in an acidic solvent, filter after reaction to obtain the acid leaching solution; S3: Dissolve phthalic acid in an organic solvent, then add the acid leaching solution and continue the reaction. After suction filtration and drying, obtain the MIL-53(Fe,Al,Cr) photocatalyst; the organic solvent is N,N-dimethylformamide; the ratio of phthalic acid, organic solvent, and acid leaching solution is 1 g : 200 - 300 mL : 1 mL, the reaction temperature is 130 - 170 °C, and the reaction time is 12 - 18 h.

2. The preparation method of the MIL-53(Fe, Al, Cr) photocatalyst prepared using chrome slag according to claim 1, characterized in that: Step S1 further includes screening the chromium slag before washing to obtain chromium slag particles, and the diameter of the chromium slag particles is 35 - 150 μm.

3. The preparation method of the MIL-53(Fe, Al, Cr) photocatalyst prepared from chromite slag according to claim 1, characterized in that: In step S1, the solid-liquid ratio of chromium slag to water is 1 g : 10 - 20 mL, the washing temperature is 60 - 80 °C, and the washing time is 20 - 40 min.

4. The preparation method of the MIL-53(Fe, Al, Cr) photocatalyst prepared using chromite slag according to claim 1, characterized in that: In step S2, the acidic solvent is 36 - 38 wt% concentrated hydrochloric acid or concentrated sulfuric acid, the solid-liquid ratio of the washed slag to the acidic solvent is 1 g : 2 - 5 mL, the reaction temperature is 110 - 130 °C, and the reaction time is 5 - 8 h.

5. The preparation method of the MIL-53(Fe,Al,Cr) photocatalyst prepared from chromite slag according to claim 1, characterized in that: The ratio of phthalic acid, organic solvent, and acid leaching solution is 1 g : 280 mL : 1 mL, the reaction temperature is 150 °C, and the reaction time is 15 h.

6. The MIL-53(Fe,Al,Cr) photocatalyst prepared by the preparation method of the MIL-53(Fe,Al,Cr) photocatalyst prepared from chromium slag according to any one of claims 1 - 5.

7. The application of the MIL-53(Fe,Al,Cr) photocatalyst according to claim 6 in the treatment of organic wastewater.

8. Use of the MIL-53(Fe, Al, Cr) photocatalyst according to claim 7 in the treatment of organic wastewater, characterized in that, It includes the following steps: Mix the MIL-53(Fe,Al,Cr) photocatalyst and organic wastewater in a mass ratio of 1 : 50 - 200, first carry out a dark reaction, and then add 0 - 10 mM hydrogen peroxide and carry out a degradation reaction by light irradiation.

9. Use of the MIL-53(Fe, Al, Cr) photocatalyst according to claim 8 in the treatment of organic wastewater, characterized in that, The concentration of the organic wastewater is 10 - 40 mg / L, the dark reaction time is 20 - 40 min, the light intensity is 300 - 350 W, and the light irradiation time is 50 - 70 min.

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