A non-metallic piezoelectric photocatalytic repair method and experimental method applied to an acidic arsenic-containing water body

Abstract

This invention provides a non-metallic piezoelectric photocatalytic remediation method for acidic arsenic-containing water bodies, specifically comprising the following steps: Step 1: Under ultrasonic irradiation, a certain amount of a piezoelectric material is added to the acidic arsenic-containing wastewater as a catalyst, and stirred for a period of time to achieve adsorption-desorption equilibrium of the system; Step 2: Under light and ultrasonic irradiation, the reaction is carried out at a certain temperature for a period of time. During the reaction, the surface of the piezoelectric catalyst generates charges, forming a piezoelectric effect, which promotes the effective separation and migration of photogenerated electron-hole pairs and promotes the oxygen reduction reaction to generate hydroxyl radicals ·OH; Step 3: The hydroxyl radicals ·OH undergo a redox reaction with arsenic (As) in the acidic arsenic-containing wastewater, converting As(III) in the wastewater into As(V).

Description

Technical Field

[0001] This invention relates to the field of environmental remediation, and in particular to a non-metallic piezoelectric photocatalytic remediation method and experimental method for acidic arsenic-containing water bodies. Background Technology

[0002] Arsenic pollution is a major global environmental problem, especially arsenic pollution in mining areas, which has attracted much attention due to its wide impact, long duration, and severe harm. Statistics show that China produces over 3.5 billion tons of acidic mine wastewater annually, and arsenic is a common heavy metal in it. The common As in acidic mine water are inorganic As(V) and As(III), with As(III) exhibiting significantly higher toxicity and mobility than As(V), making its remediation urgent. Traditional methods for treating arsenic-containing acidic mine wastewater include coagulation, adsorption, and membrane methods; however, all suffer from secondary pollution, poor sustainability, and high costs, and are ineffective at removing As(III). In recent years, advanced oxidation technologies have gained significant attention in wastewater treatment. Reactive oxygen species (ROS) possess redox activity and, upon being excited by photons, form higher energy states, creating a series of reactive oxygen species, including singlet oxygen (ROS). 1 O2), superoxide radicals (O2) •- Arsenic-containing wastewater contains hydroxyl radicals (•OH), etc. However, traditional methods such as ozone oxidation, Fenton oxidation, electrocatalysis, and photocatalysis still have many limitations, such as poor acid resistance, the need for external oxidants or electrical energy input, low utilization of photogenerated carriers, and high recombination rates. Therefore, it is essential to find new, effective, and environmentally friendly methods for the remediation of acidic arsenic-containing wastewater.

[0003] Currently, the application of piezoelectric photocatalysis in the treatment of arsenic pollution in acidic water remains unclear. Piezoelectric-photocatalytic synergistic technology can utilize the widely available mechanical and light energy in the environment without relying on exogenous oxidants. Under the synergistic effect of piezoelectricity and photocatalysis, the system can not only promote the effective separation and utilization of photogenerated electron-hole pairs, but also modulate the band structure of materials, enhancing their redox capabilities. In this coupled system, more electrons and holes can participate in the process of converting water molecules and dissolved oxygen into reactive free radicals, thereby significantly improving the degradation efficiency of pollutants.

[0004] Catalyst selection is a crucial step in piezoelectric photocatalysis, as its properties directly determine the effective synergy between the piezoelectric and photocatalytic effects, thus influencing the generation efficiency of active species and the final catalytic performance. The strong acidity and complex metallic composition of acidic mine wastewater pose severe challenges to catalytic materials. Traditional metal-based photocatalysts are not only prone to deactivation in this environment but also pose a risk of secondary pollution due to metal leaching. In contrast, non-metallic catalysts, with their superior acid resistance and low operating costs, offer a more economically feasible and environmentally friendly solution for large-scale acidic mine wastewater treatment. Covalent triazine frameworks (CTFs), as a novel type of crystalline non-metallic polymer, differ from traditional covalent organic frameworks in their metal-free nature, high stability, and customizable atomic-level structure, demonstrating significant application potential in both photocatalysis and piezoelectric catalysis. The catalyst CTF-1 selected in this invention combines excellent photocatalytic activity and piezoelectric responsiveness, facilitating the efficient utilization of light and dissolved oxygen. Furthermore, its porous environment may be key to arsenic adsorption and removal. Although CTFs have broad application prospects in wastewater treatment, research on their specific application for the removal of heavy metal pollutants in acidic water is still extremely limited and has not yet been fully explored. Summary of the Invention

[0005] The main objective of this invention is to provide a non-metallic piezoelectric photocatalytic remediation method for acidic arsenic-containing water bodies. This method combines piezoelectric catalysis and photocatalysis systems and is applied to the removal of arsenic pollution from acidic water.

[0006] To achieve the above objectives, the technical solution adopted by this invention is as follows: a non-metallic piezoelectric photocatalytic remediation method for acidic arsenic-containing water bodies, specifically including the following steps: Step 1: Under the action of ultrasound, a certain amount of piezoelectric material is added to the acidic arsenic-containing wastewater as a catalyst, and the mixture is stirred for a period of time to reach the adsorption and desorption equilibrium of the system. Step 2: The system is subjected to light and ultrasound for a period of time. The reaction formula is as follows: , in, Produced by light and ultrasound, Provided by an acidic environment; During the reaction, the catalyst surface generates charges and forms a piezoelectric effect, which promotes the effective separation and migration of photogenerated electron-hole pairs and promotes the efficient generation of hydroxyl radicals (·OH) in the oxygen reduction reaction. Step 3: The hydroxyl radical ·OH reacts with the arsenic in the acidic arsenic-containing wastewater in a redox reaction, converting As(III) in the wastewater into solid As(V); Step 4: The As(V) obtained in Step 3 is adsorbed by the catalyst, and the As(V) is separated from the wastewater by precipitation and filtration to achieve the remediation of arsenic pollution.

[0007] Preferably, in step one, the stirring rod rotates at 400 rpm during stirring.

[0008] Preferably, the stirring rod is made of polytetrafluoroethylene.

[0009] Preferably, the illumination originates from the full spectrum of xenon lamp illumination.

[0010] Preferably, the catalyst is a covalent triazine skeleton CTF-1.

[0011] This invention also provides an experimental method for the remediation of arsenic pollution in acidic water based on non-metallic piezoelectric photocatalysis, specifically including the following steps: Step S1: Prepare a pure water system; Step S2: Prepare an acidic arsenic-containing system; Step S3: Treat the pure water system and the arsenic-containing system respectively according to the above-mentioned arsenic pollution remediation method, and obtain the effects of piezoelectric photosynergy, catalyst, and pH on the amount of hydroxyl radicals generated based on the treatment results.

[0012] Preferably, step S3 specifically includes the following steps: Step 31: Take a certain amount of ultrapure water, adjust it to the predetermined pH, and divide it into several portions; Step 32: Add different amounts of catalyst CTF-1 to the products obtained in step 11; Step 33: Add the same amount of BA probe to the integral product obtained in step 12 to obtain the super-water system.

[0013] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a mechanism for treating acidic arsenic-containing wastewater using piezoelectric-photosynergistic effects. Through piezoelectric-photosynergistic effects, more electrons and holes can participate in the process of converting water molecules and dissolved oxygen into active free radicals. Hydroxyl free radicals can efficiently oxidize arsenic in wastewater, converting it into a more easily removable form. Simultaneously, the use of the piezoelectric material CTF-1 can improve the efficiency of this process, thereby achieving more effective wastewater treatment. In terms of As(III) oxidation capacity, it is significantly improved compared to methods using only ultrasound or phototherapy. This method can not only be efficiently applied to remove arsenic from wastewater under acidic water conditions, but also reduces energy consumption and the use of exogenous oxidants during the treatment process, while effectively avoiding secondary pollution problems caused by metal-based catalysts, thus possessing both environmental and economic advantages. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the repair method of the present invention; Figure 2 This is a comparison chart of the generation of •OH under different catalytic conditions in a pure water system; Figure 3 This is a comparison chart of •OH generated at different pH levels in a pure water system; Figure 4 This is a comparison chart of the generation of •OH under different dosages of CTF-1 in a pure water system; Figure 5 The graph shows the efficient oxidation of As(III) by the CTF-1 piezoelectric-photonic system within 1 hour. Figure 6 The graph shows the efficient oxidation of As(III) by the CTF-1 piezoelectric-photon system within 10 minutes. Figure 7 This is a graph showing the adsorption effect of the CTF-1 piezoelectric-photonic system on arsenic within 1 hour; Figure 8 This is a graph showing the arsenic removal of actual acidic mine wastewater by the CTF-1 piezoelectric photoelectric system within 1 hour. Detailed Implementation

[0015] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art.

[0016] Example A non-metallic piezoelectric photocatalytic remediation method for acidic arsenic-containing water bodies includes the following steps: Step 1: Add a certain amount of non-metallic material with piezoelectric effect as a catalyst to the acidic arsenic-containing wastewater and stir for 20 minutes to reach the adsorption and desorption equilibrium of the system. During stirring, the stirring rod speed is 400 rpm and the stirring rod is a polytetrafluoroethylene rod; the catalyst is covalent triazine framework CTF-1.

[0017] Step 2: The system is subjected to light and ultrasound for 60 minutes. The reaction formula is as follows: , in, Produced by light and ultrasound, Provided by an acidic environment; The temperature was maintained at 25±5℃ during the reaction, and the ice pack was replaced every half hour. The light source was full-spectrum xenon lamp illumination, and the ultrasound source was a liquid crystal ultrasonic cleaner (100W KS-2200DE). Step 3: During the reaction, the CTF-1 surface generates charges and forms a piezoelectric effect, which promotes the effective separation and migration of photogenerated electron-hole pairs and promotes the efficient generation of hydroxyl radicals (·OH) by the oxygen reduction reaction. Step 4: Hydroxyl radicals (·OH) react with arsenic (As) in acidic arsenic-containing wastewater in a redox reaction, converting As(III) in the wastewater into solid As(V). As(V) has low toxicity and is easy to remove. In step five, the As(V) obtained in step four is adsorbed by CTF-1, and the As(V) is separated from the wastewater through precipitation and filtration, thereby achieving the remediation of arsenic pollution.

[0018] Experimental Example This experimental example is mainly used to verify the methods in the embodiments.

[0019] 1) Configure a pure water system: First, add 36 mL of ultrapure water to a 250 mL beaker and adjust the pH to 3. Then, add material CTF-1, and finally add 4 mL of BA probe. The CTF-1 addition amounts are 0, 0.05, and 0.1 g / L, respectively. The BA probe is a sodium benzoate (BA) solution. Before the experiment, a 100 mM sodium benzoate (BA) solution needs to be prepared: dissolve 1.44 g of sodium benzoate in water and bring the volume to 100 mL.

[0020] After configuring the pure water system, the obtained pure water was used as the step in the wastewater execution example. Different dosages, different pH values, and different catalytic conditions were set to investigate their effects on the generation of H2O2 and ·OH.

[0021] 2) Configure an arsenic-containing system: First, add 32 mL of ultrapure water and 4 mL of 1 mg / L As(III) / As(V) solution to a 250 mL beaker. Then, add 4 mL of BA probe and adjust the pH to 3. Finally, add material CTF-1 (0.05 g / L). During the experiment, the stirring speed is 400 rpm, and a polytetrafluoroethylene rod is used as the stirring rod. Samples are taken every 10 min for testing.

[0022] After configuring the arsenic-containing system, the resulting acidic arsenic-containing system was used as a step in the wastewater implementation example. Under different pH and catalytic conditions, its effect on arsenic oxidation was investigated.

[0023] 3) Determine the cumulative •OH flux in the pure water system and the acidic arsenic-containing system during the steps in the examples: During the process, the BA probe is oxidized to p-HBA upon reaction with •OH. The generated p-HBA is determined using an Agilent 1260 HPLC system with an Agilent 588905-902 HC-C18 column. Test conditions: mobile phase was acetonitrile and 0.1% trifluoroacetic acid solution (30:70, v / v), flow rate was 1 mL / min, detection wavelength was 255 nm, and the detection limit for p-HBA was 0.1 μM. The accumulated •OH generated during the reaction was determined using the formula [•OH] = [p-HBA] x 5.87.

[0024] from Figure 2 It can be seen that in the pure water system, compared with the single light irradiation or single ultrasound conditions, the amount of hydroxyl radicals generated under the synergistic effect of light irradiation and ultrasound is significantly increased. The results show that the piezoelectric-photosynergistic effect can effectively promote the generation of hydroxyl radicals.

[0025] from Figure 4 It can be seen that with the increase of CTF-1 dosage, the amount of hydroxyl radical generated increases significantly. This is because the addition of the catalyst promotes the effective separation and utilization of photogenerated electron-hole pairs, and more electrons and holes can participate in the process of converting water molecules and dissolved oxygen into active free radicals. Therefore, it can be concluded that CTF-1 can significantly promote the generation of hydroxyl radicals in this system.

[0026] from Figure 3 , 5 It can be seen that after adding CTF-1, the amount of hydroxyl radicals generated increased significantly under pH=3 conditions and the oxidation effect of As(III) was optimal. This is because the energy barrier required to drive the reaction is lower under acidic conditions, thus achieving a more efficient redox reaction. Therefore, it can be concluded that under acidic conditions, CTF-1 can significantly promote the generation of hydroxyl radicals and achieve efficient oxidation of As(III).

[0027] from Figure 5 , 6 It can be seen that the system completely oxidizes As(III) to As(V) within 10 minutes. This is because the sufficient amount of hydroxyl radicals continuously generated in the reaction have extremely strong oxidizing properties, and under the action of CTF-1, the activation energy of the reaction is significantly reduced, which greatly accelerates the oxidation reaction process. Therefore, it can be concluded that the reaction system can achieve efficient oxidation of arsenic within 10 minutes and rapidly reduce the toxicity of water.

[0028] 4) Prepare aqueous solutions containing 1 mg / L As(III) and 1 mg / L As(V) respectively for dark adsorption experiments to investigate the adsorption effect of CTF-1 on arsenic.

[0029] from Figure 7It can be seen that after 3 hours of dark adsorption experiment, arsenic was effectively adsorbed, with an adsorption rate of 19% for As(III) and 36% for As(V).

[0030] 5) Applied to arsenic-containing acidic mine wastewater: First, add 40 mL of arsenic-containing acidic mine wastewater to a 250 mL beaker. The arsenic concentration in the solution is 46.87 μg / L, and the pH is 2.8. Add material CTF-1 (0.05 g / L). During the experiment, the stirring speed is 400 rpm, and a polytetrafluoroethylene rod is used as the stirring rod. Samples are taken every 10 min for testing.

[0031] from Figure 8 It can be seen that the system completely oxidizes As(III) to As(V) within 60 minutes. Therefore, it can be concluded that the reaction system can be applied to actual acidic arsenic-containing wastewater, and can achieve efficient oxidation of arsenic and rapidly reduce the toxicity of water.

[0032] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. A non-metallic piezoelectric photocatalytic remediation method for acidic arsenic-containing water, characterized in that, Specifically, the steps include the following: Step 1: Under the action of ultrasound, a certain amount of piezoelectric material is added to the acidic arsenic-containing wastewater as a catalyst, and the mixture is stirred for a period of time to reach the adsorption and desorption equilibrium of the system. Step 2: The system is subjected to light and ultrasound for a period of time. The reaction formula is as follows: ， in, Produced by light and ultrasound, Provided by an acidic environment; During the reaction, the catalyst surface generates charges and forms a piezoelectric effect, which promotes the effective separation and migration of photogenerated electron-hole pairs and promotes the efficient generation of hydroxyl radicals (·OH) in the oxygen reduction reaction. Step 3: The hydroxyl radical ·OH reacts with the arsenic in the acidic arsenic-containing wastewater in a redox reaction, converting As(III) in the wastewater into solid As(V); Step 4: The As(V) obtained in Step 3 is adsorbed by the catalyst, and the As(V) is separated from the wastewater by precipitation and filtration to achieve the remediation of arsenic pollution.

2. In the arsenic pollution remediation method according to claim 1, in step one, the stirring rod rotates at 400 rpm during stirring.

3. In the arsenic pollution remediation method according to claim 1, the stirring rod is a polytetrafluoroethylene rod.

4. The arsenic pollution remediation method according to claim 1, wherein the illumination originates from xenon lamp full-spectrum illumination.

5. The arsenic pollution remediation method according to claim 1, wherein the catalyst is a covalent triazine framework CTF-1.

6. A non-metallic piezoelectric photocatalytic remediation method for acidic arsenic-containing water bodies, specifically comprising the following steps: Step S1: Prepare a pure water system; Step S2: Prepare an acidic arsenic-containing system; Step S3: Treat the pure water system and the arsenic-containing system respectively according to the arsenic pollution remediation method described in any one of claims 1-5, and obtain the effects of piezoelectric photosynergy, catalyst, and pH on the amount of hydroxyl radicals generated based on the treatment results.

7. The experimental method according to claim 6, characterized in that, Step S3 specifically includes the following steps: Step 31: Take a certain amount of ultrapure water, adjust it to the predetermined pH, and divide it into several portions; Step 32: Add different amounts of catalyst CTF-1 to the products obtained in step 31; Step 33: Add the same amount of BA probe to several samples of the product obtained in step 32 for quantitative detection of hydroxyl radicals ·OH in the system.

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