Zero-valent iron boron nitride composite material as well as preparation method and application thereof

Abstract

The invention discloses a zero-valent iron boron nitride composite material as well as a preparation method and application thereof, and belongs to the technical field of water treatment. The method comprises the following steps: dissolving urea, ferric trichloride hexahydrate and boric acid in water, carrying out ultrasonic dispersion, evaporating the solvent, and pyrolyzing the evaporated solid in a tubular furnace to obtain the zero-valent iron boron nitride composite material. The invention solves the problems of high environmental pH requirement, easy oxidation and agglomeration and unstable carrier combination of zero-valent iron in Fenton reaction, and provides a green and sustainable Fenton oxidation new process for treatment of sewage and wastewater containing bisphenol A (BPA) and other organic matters.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment, and in particular relates to a zero-valent iron boron nitride composite material and a preparation method and application thereof. Background Art

[0002] In recent years, with the advancement of science and technology and the rapid development of industrialization, new chemicals have been produced in large quantities to meet the needs of various application fields. However, everything has two sides. Some organic pollutants, such as pharmaceuticals and personal care products, microplastics, endocrine disrupting chemicals, perfluorinated and polyfluorinated chemicals, etc., are often detected in different water environments due to their non-biodegradability, persistence and ecotoxicity, posing potential risks to life, health and the ecological environment. Studies have shown that organically contaminated wastewater has problems such as high pollutant concentration, complex water matrix, and high treatment cost, which brings huge challenges to its pollution reduction and emission reduction. Therefore, it is very important to develop efficient and deep water treatment technology for organic wastewater.

[0003] Advanced oxidation processes (AOPs) refer to the in-situ generation of reactive oxygen species (ROSs) with strong oxidizing power, which can decompose organic compounds in water and mineralize them into harmless products. The Fenton process is an economical and efficient advanced oxidation technology. In the Fenton process, peroxides and ferrous ions react to produce highly oxidizing hydroxyl radicals, which are widely used worldwide to eliminate organic pollutants in water. Persulfate (PMS) usually requires catalysis such as transition metals, light, and heat to produce ROSs. Among them, nano-zero-valent iron has the advantages of large specific surface area, high reaction activity, and strong reducing ability. It can promote the reaction for a long time and effectively reduce the need for frequent addition of reagents. It is becoming a potential Fenton-like catalyst. However, the catalyst is subject to certain limitations in practical applications: First, the pH application range of the Fenton method is narrow. When the environmental pH is higher than 4, iron salts are prone to precipitation, which hinders the iron cycle. In this low pH environment, it may also cause corrosion to the equipment. Second, nano-zero-valent iron is easy to oxidize, and excessive corrosion products will cover the active sites, eventually passivating the zero-valent iron and affecting the catalytic efficiency. Third, affected by the nano effect and its own magnetism, zero-valent iron is easy to aggregate, which reduces its surface activity. Therefore, zero-valent iron is usually loaded on a carrier to improve its stability. However, nano zero-valent iron and inorganic mineral carrier materials rely on the single mechanical support of layered inorganic minerals, and the structure is unstable and easy to be dispersed, which eventually leads to the shedding or re-aggregation of zero-valent iron. Summary of the invention

[0004] Technical problems solved: In response to the above technical problems, the present invention provides a zero-valent iron boron nitride composite material and its preparation method and application, which solves the problems of high environmental pH requirements, easy oxidation, agglomeration and unstable binding with the carrier of zero-valent iron in the Fenton reaction, and provides a green and sustainable new Fenton oxidation process for the treatment of wastewater containing organic matter such as bisphenol A (BPA).

[0005] Technical solution: A method for preparing a zero-valent iron boron nitride composite material, specifically: dissolving urea, ferric chloride hexahydrate and boric acid in water, evaporating the solvent after ultrasonic dispersion, and placing the evaporated solid in a tubular furnace for pyrolysis to obtain the zero-valent iron boron nitride composite material.

[0006] Preferably, the molar ratio of boric acid to urea is 1:(2-10).

[0007] Preferably, the molar ratio of the ferric chloride hexahydrate to urea is 1:(20-40).

[0008] Preferably, the reaction temperature of the pyrolysis is 700-1100°C.

[0009] Preferably, the pyrolysis reaction time is 2 to 5 hours.

[0010] The zero-valent iron boron nitride composite material is prepared by the above method.

[0011] Application of the above zero-valent iron boron nitride composite material in the treatment of organic wastewater.

[0012] Beneficial effects: Compared with traditional iron-based supported catalysts, the degradation efficiency of organic pollutants by zero-valent iron-boron nitride composite materials is increased by about 880% in a very short time (5 minutes).

[0013] The zero-valent iron boron nitride composite material prepared by the present invention can efficiently degrade a variety of organic pollutants in water, such as 2,4-DCP up to 99.0%, BPA up to 95.7%, and phenol up to 82.9%. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a high-resolution transmission electron microscopic image of the zero-valent iron / boron nitride composite material prepared by the present invention; Figure 2 This is the effect diagram of BN / PMS and Fe / PMS in degrading BPA; Figures 3 to 6 This is the effect diagram of different zero-valent iron / boron nitride composite materials degrading BPA: Figure 3 This is a diagram showing the effect of Fe / BN prepared under different Fe / urea ratios on the degradation of BPA; Figure 4This is a diagram showing the effect of Fe / BN prepared under different urea and boric acid ratios on the degradation of BPA; Figure 5 This is a diagram showing the effect of zero-valent iron / boron nitride composite materials prepared at different pyrolysis temperatures on the degradation of BPA; Figure 6 This is a diagram showing the effect of zero-valent iron / boron nitride composite materials prepared at different pyrolysis times on the degradation of BPA; Figure 7 This is a diagram showing the effect of zero-valent iron / boron nitride composite materials on degrading other pollutants. DETAILED DESCRIPTION

[0015] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments.

[0016] Example 1

[0017] A method for preparing a zero-valent iron / boron nitride composite material comprises the following steps: Step 1, weigh 3.6 g of urea and dissolve it in 30 mL of deionized water, then add 0.62 g of boric acid and mix by ultrasonication to obtain a clear solution; Step 2: 0.5 g FeCl 3 •6H 2 O is dissolved in the solution obtained in step 1, and ultrasonically dispersed uniformly to obtain a precursor solution; Step 3, evaporating the precursor solution obtained in step 2 in a 65° C. water bath to dry the solvent; Step 4: transfer the solid obtained after evaporation in step 3 into a crucible and place it in a tube furnace at 5% H 2 The precipitate was calcined at 900 °C for 3 h in a / Ar atmosphere to achieve high temperature pyrolysis. After the pyrolysis was completed, the temperature was naturally lowered to room temperature to obtain the zero-valent iron / boron nitride composite material, which was named Fe / BN.

[0018] Comparative Example 1 A method for preparing a zero-valent iron / boron nitride composite material comprises the following steps: Step 1, weigh 1.2 g of urea and dissolve it in 30 mL of deionized water, then add 0.62 g of boric acid and mix by ultrasonication to obtain a clear solution; Step 2: 0.5 g FeCl 3 •6H 2 O is dissolved in the solution obtained in step 1, and ultrasonically dispersed uniformly to obtain a precursor solution; Step 3, evaporating the precursor solution obtained in step 2 in a 65° C. water bath to dry the solvent; Step 4: transfer the solid obtained after evaporation in step 3 into a crucible and place it in a tube furnace at 5% H 2The precipitate was calcined at 900 °C for 3 h in a / Ar atmosphere to achieve high temperature pyrolysis. After the pyrolysis was completed, the temperature was naturally lowered to room temperature to obtain the zero-valent iron / boron nitride composite material, which was named Fe / BN-1.

[0019] Comparative Example 2 A method for preparing a zero-valent iron / boron nitride composite material comprises the following steps: Step 1, weigh 6.01 g of urea and dissolve it in 30 mL of deionized water, then add 0.62 g of boric acid and mix by ultrasonication to obtain a clear solution; Step 2: 0.5 g FeCl 3 •6H 2 O is dissolved in the solution obtained in step 1, and ultrasonically dispersed uniformly to obtain a precursor solution; Step 3, evaporating the precursor solution obtained in step 2 in a 65° C. water bath to dry the solvent; Step 4: transfer the solid obtained after evaporation in step 3 into a crucible and place it in a tube furnace at 5% H 2 The precipitate was calcined at 900 °C for 3 h in a / Ar atmosphere to achieve high temperature pyrolysis. After the pyrolysis was completed, the temperature was naturally lowered to room temperature to obtain the zero-valent iron / boron nitride composite material, which was named Fe / BN-2.

[0020] Comparative Example 3 A method for preparing a zero-valent iron / boron nitride composite material comprises the following steps: Step 1 is the same as step 1 in Example 1; Step 2: 0.81 g FeCl 3 •6H 2 O is dissolved in the solution obtained in step 1, and ultrasonically dispersed uniformly to obtain a precursor solution; Step 3, evaporating the precursor solution obtained in step 2 in a 65° C. water bath to dry the solvent; Step 4: transfer the solid obtained after evaporation in step 3 into a crucible and place it in a tube furnace at 5% H 2 The precipitate was calcined at 900 °C for 3 h in a / Ar atmosphere to achieve high temperature pyrolysis. After the pyrolysis was completed, the temperature was naturally lowered to room temperature to obtain the zero-valent iron / boron nitride composite material, which was named Fe / BN-3.

[0021] Comparative Example 4 A method for preparing a zero-valent iron / boron nitride composite material comprises the following steps: Step 1 is the same as step 1 in Example 1; Step 2: 0.41 g FeCl 3 •6H 2 O is dissolved in the solution obtained in step 1, and ultrasonically dispersed uniformly to obtain a precursor solution; Step 3, evaporating the precursor solution obtained in step 2 in a 65° C. water bath to dry the solvent; Step 4: transfer the solid obtained after evaporation in step 3 into a crucible and place it in a tube furnace at 5% H 2 The precipitate was calcined at 900 °C for 3 h in a / Ar atmosphere to achieve high temperature pyrolysis. After the pyrolysis was completed, the temperature was naturally lowered to room temperature to obtain the zero-valent iron / boron nitride composite material, which was named Fe / BN-4.

[0022] Comparative Example 5 A method for preparing a zero-valent iron / boron nitride composite material comprises the following steps: Step 1 is the same as step 1 in Example 1; Step 2: 0.5 g FeCl 3 •6H 2 O is dissolved in the solution obtained in step 1, and ultrasonically dispersed uniformly to obtain a precursor solution; Step 3, evaporating the precursor solution obtained in step 2 in a 65° C. water bath to dry the solvent; Step 4: transfer the solid obtained after evaporation in step 3 into a crucible and place it in a tube furnace at 5% H 2 The precipitate was calcined at 700 °C for 3 h in a / Ar atmosphere to achieve high temperature pyrolysis. After the pyrolysis was completed, the temperature was naturally cooled to room temperature to obtain the zero-valent iron / boron nitride composite material, which was named Fe / BN-5.

[0023] Comparative Example 6 A method for preparing a zero-valent iron / boron nitride composite material comprises the following steps: Step 1 is the same as step 1 in Example 1; Step 2: 0.5 g FeCl 3 •6H 2 O is dissolved in the solution obtained in step 1, and ultrasonically dispersed uniformly to obtain a precursor solution; Step 3, evaporating the precursor solution obtained in step 2 in a 65° C. water bath to dry the solvent; Step 4: transfer the solid obtained after evaporation in step 3 into a crucible and place it in a tube furnace at 5% H 2 The precipitate was calcined at 100 °C for 3 h in a / Ar atmosphere to achieve high temperature pyrolysis. After the pyrolysis was completed, the temperature was naturally lowered to room temperature to obtain the zero-valent iron / boron nitride composite material, which was named Fe / BN-6.

[0024] Comparative Example 7 A method for preparing a zero-valent iron / boron nitride composite material comprises the following steps: Step 1 is the same as step 1 in Example 1; Step 2: 0.5 g FeCl 3 •6H 2 O is dissolved in the solution obtained in step 1, and ultrasonically dispersed uniformly to obtain a precursor solution; Step 3, evaporating the precursor solution obtained in step 2 in a 65° C. water bath to dry the solvent; Step 4: transfer the solid obtained after evaporation in step 3 into a crucible and place it in a tube furnace at 5% H 2 The precipitate was calcined at 900 °C for 2 h in a / Ar atmosphere to achieve high temperature pyrolysis. After the pyrolysis was completed, the temperature was naturally lowered to room temperature to obtain the zero-valent iron / boron nitride composite material, which was named Fe / BN-7.

[0025] Comparative Example 8 A method for preparing a zero-valent iron / boron nitride composite material comprises the following steps: Step 1 is the same as step 1 in Example 1; Step 2: 0.5 g FeCl 3 •6H 2 O is dissolved in the solution obtained in step 1, and ultrasonically dispersed uniformly to obtain a precursor solution; Step 3, evaporating the precursor solution obtained in step 2 in a 65° C. water bath to dry the solvent; Step 4: transfer the solid obtained after evaporation in step 3 into a crucible and place it in a tube furnace at 5% H 2 The precipitate was calcined at 900 °C for 5 h in a / Ar atmosphere to achieve high temperature pyrolysis. After the pyrolysis was completed, the temperature was naturally cooled to room temperature to obtain the zero-valent iron / boron nitride composite material, which was named Fe / BN-8.

[0026] Combination Figure 2 It can be seen that the activation performance of BN prepared alone on PMS is very weak, and the Fe-activated PMS prepared alone only degrades 10.8% of BPA. However, when Fe / BN is used as a catalyst to activate PMS, 95.7% of BPA can be degraded in 5 minutes. It can be observed that the catalytic performance of the composite material has been greatly improved.

[0027] Combination Figure 3 It can be seen that the zero-valent iron / boron nitride composite material prepared by adjusting the molar ratio of boric acid and urea has a different degradation effect on BPA as the urea content in the material changes. The best degradation effect is achieved when the molar ratio of boric acid to urea is 1:6, which can reach 95.7%. Figure 4 It can be seen that when the molar ratio of metal Fe to urea is 1:30, the zero-valent iron / boron nitride composite material has the best catalytic degradation performance.

[0028] Combination Figure 5 and Figure 6It can be seen that the degradation effect of BPA by zero-valent iron / boron nitride composites prepared at different high-temperature pyrolysis reaction temperatures and times is also different. The degradation effect is best when the high-temperature pyrolysis temperature and time are 900 ℃ and 3 h, respectively. It can be seen that the optimal conditions for preparing zero-valent iron / boron nitride composites are to control the molar ratio of boric acid and urea to 1:6, the molar ratio of metal species Fe and urea to 1:30, and pyrolysis at 900 ℃ for 3 h.

[0029] Combination Figure 7 It can be seen that the prepared zero-valent iron / boron nitride composite material not only has a good degradation effect on BPA, but can also effectively remove 2,4-DCP and phenol. This shows that the zero-valent iron / boron nitride composite material can efficiently degrade a variety of organic pollutants in water.

Claims

1. A method for preparing a zero-valent iron boron nitride composite material, characterized in that: The method comprises the following steps: dissolving urea, ferric chloride hexahydrate and boric acid in water, evaporating the solvent after ultrasonic dispersion, placing the evaporated solid in a tube furnace for pyrolysis, and obtaining the zero-valent iron boron nitride composite material.

2. The method for preparing a zero-valent iron boron nitride composite material according to claim 1, characterized in that: The molar ratio of the boric acid to the urea is 1:(2-10).

3. The method for preparing a zero-valent iron boron nitride composite material according to claim 1, characterized in that: The molar ratio of the ferric chloride hexahydrate to urea is 1:(20-40).

4. The method for preparing a zero-valent iron boron nitride composite material according to claim 1, characterized in that: The reaction temperature of the pyrolysis is 700-1100°C.

5. The method for preparing a zero-valent iron boron nitride composite material according to claim 1, characterized in that: The reaction time of the pyrolysis is 2 to 5 hours.

6. The zero-valent iron boron nitride composite material prepared by the method according to claim 1.

7. Use of the zero-valent iron boron nitride composite material according to claim 6 in the treatment of organic wastewater.

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