Method for removing sulfur ions in water by coupling piezoelectric catalytic fuel cell with oxygen oxidation

Abstract

The invention provides a method for removing sulfur ions in water by coupling a piezoelectric catalytic fuel cell with oxygen oxidation, and belongs to the technical field of wastewater treatment. The method is characterized in that a Fe-coated MoS2 / CFC piezoelectric catalytic electrode is prepared by a one-step hydrothermal method, and a piezoelectric catalytic fuel cell enhanced air oxidation system is constructed based on the electrode. The method has the advantages that 91% (-14.7 mg) of sulfur ions (S < 2->) can be removed within 1.5 h by utilizing the piezoelectric catalytic fuel cell and only aerating, and the system has excellent piezoelectric catalytic activity, has the characteristics of high efficiency and greenness in sulfur ion removal, and has a good application prospect in the fields of catalytic fuel cells and advanced oxidation treatment of wastewater.

Description

Technical Field

[0001] The present invention provides a construction and application method of a piezoelectrically enhanced oxygen oxidation desulfurization fuel cell, which belongs to the technical field of wastewater treatment and relates to the construction of a piezoelectric fuel cell, and in particular to a method of enhancing the oxidation of sulfide in water by oxygen exposed to air by the piezoelectric effect. Background Art

[0002] In recent years, with the rapid development of science and technology, the discharge of industrial wastewater, domestic sewage, and agricultural wastewater has led to excessive sulfide in groundwater. Soluble sulfides are corrosive and can easily damage steel, concrete, etc., causing economic losses and leaving safety hazards. At the same time, sulfides are easily converted into hydrogen sulfide (H2S) in water, producing odors, harming the human respiratory and nervous systems, increasing the incidence and mortality of fish, and complexes with heavy metals, which will inhibit the growth of plant roots. In order to improve water quality, ensure drinking water safety, and extend the life of equipment and pipelines, effective measures must be taken to remove sulfides from groundwater. Traditional treatment methods include filtration, chemical precipitation, and biological methods. However, the filtration method has high cost and low selectivity; the addition of reagents in the chemical precipitation method is prone to secondary pollution; the biological method has strict requirements on temperature and pH, and the reaction rate is also slow.

[0003] The chemical oxidation method is to pass an oxidizing gas, such as oxygen (O2), chlorine (Cl2), ozone (O3), etc., into the sulfur-containing wastewater to oxidize the sulfide into elemental sulfur or sulfate. Using oxygen in the air to treat sulfides, no additional chemical agents are added, the cost is low, and the harm to the environment is also less. However, at normal temperature and pressure, the oxidizing ability of oxygen is low, the reaction with sulfides is not strong, and the removal efficiency is low. Improving the ability of oxygen oxidation desulfurization is of practical significance.

[0004] Piezoelectric catalysis is a phenomenon in which, when a semiconductor material with a non-centrosymmetric structure undergoes mechanical deformation, the positive and negative charges in the material migrate in the opposite direction to the surface of the material, and undergo redox reactions with pollutants in the water. Since it can be stimulated by mechanical energy generated by green energy, such as wind, water flow, or footsteps, it is environmentally friendly. Since powdered catalysts are difficult to recycle, the catalysts are synthesized in situ on a conductive substrate to prepare piezoelectric catalytic electrodes, which can not only fully expose the active sites, but also fix the catalysts.

[0005] To further improve the piezoelectric performance, the present invention constructs a piezoelectric catalytic fuel cell for the first time. Through the bias voltage between the electrodes, the electrons generated by the piezoelectric anode are transmitted to the cathode through an external circuit, promoting the separation of positive and negative charges in the material, and using aeration to provide the system with dissolved oxygen and mechanical force generated by water flow / bubbles. This system can be used not only for desulfurization, but also for the removal of refractory organic pollutants. There are currently no reports on the construction of piezoelectric catalytic fuel cells and the use of piezoelectric effect to enhance oxygen oxidation desulfurization. Summary of the invention

[0006] In view of the difficulty in treating sulfide pollution in wastewater and the low efficiency of oxygen oxidation desulfurization, the present invention constructs a piezoelectric catalytic fuel cell system that can desulfurize only through aeration, that is, a method of enhancing oxygen oxidation desulfurization by using piezoelectric catalytic effect.

[0007] The technical solution of the present invention:

[0008] A method for removing sulfur ions from water by coupling a piezoelectric catalytic fuel cell with oxygen oxidation, comprising the following steps:

[0009] The piezoelectric anode and cathode are connected through an external circuit and placed in an insulating material reactor, with the pollutant solution to be treated as the electrolyte. The aeration head is inserted into the bottom of the reactor as a provider of dissolved oxygen and mechanical force. The reaction begins when the aeration pump is turned on. The power generation and sulfur ion (S) generation are adjusted by adjusting the aeration intensity, the temperature of the pollutant solution to be treated, and the external resistance value of the external circuit. 2- ) removal effect.

[0010] Further, preparation of Fe@MoS2 / CFC piezoelectric anode:

[0011] After the clean carbon fiber cloth CFC was removed by anhydrous ethanol, it was immersed in a seed solution containing Na2MoO4·2H2O and CH4N2S, and then dried in a vacuum drying oven after soaking for a period of time to obtain a seed layer CFC. FeSO4·xH2O, Na2MoO4·2H2O and CH4N2S were added to deionized water, stirred evenly, and the mixed solution was poured into a reactor. The seed layer CFC was placed in a reactor containing the mixed solution for hydrothermal reaction. After the reaction was completed, the reactor was cooled naturally to room temperature, the CFC loaded with Fe@MoS2 was taken out, repeatedly rinsed with deionized water, and fully dried in a vacuum drying oven to obtain a Fe@MoS2 / CFC piezoelectric catalytic electrode.

[0012] Furthermore, the molar concentration of S in the seed solution is 0.01M-0.03M, which is 2-3 times that of Mo.

[0013] Furthermore, the clean CFC is immersed in the seed solution for 0.5 h to 2 h.

[0014] Furthermore, in the mixed solution of FeSO4·xH2O, Na2MoO4·2H2O and CH4N2S, the molar concentration ratio of Fe and Mo is less than or equal to 1:1, and the molar concentration of S is 0.15M-0.25M, which is 2-3 times the sum of the molar concentrations of Fe and Mo.

[0015] Furthermore, the addition ratio of seed layer CFC to mixed solution is 1 cm2 :70mL-1cm 2 :0.9mL.

[0016] Furthermore, the hydrothermal reaction temperature is 180°C-220°C, and the time is 15h-25h.

[0017] Furthermore, the vacuum drying temperature is 60°C-80°C, and the drying time is 4h-6h.

[0018] Furthermore, the external circuit includes a wire and an external resistor, and the connection method is: wires are led out from the piezoelectric anode and cathode respectively, and the two ends of the external resistor are connected to form a loop. Furthermore, the resistance range of the external resistor is 10Ω-2000Ω; the flow rate of the exposed air is 0.8L min -1 -3.5L min -1 ; The temperature of the pollutant solution to be treated is 20℃-30℃;

[0019] Furthermore, the material of the cathode is a conductive substrate, such as carbon fiber cloth, and the cathode material may also be a piezoelectric catalytic cathode or an electrocatalytic cathode in which a piezoelectric catalyst or an electrocatalyst is loaded on a conductive substrate.

[0020] By using the above method, sulfur ions, difficult-to-degrade organic pollutants, or sterilization can be efficiently removed from water through aeration coupled with the piezoelectric effect.

[0021] Beneficial effects of the invention: The invention provides a method for constructing and applying a piezoelectric catalytic fuel cell system. Under normal temperature and pressure, the piezoelectric effect and redox reaction can be induced only by aeration, thereby enhancing the effect of oxygen oxidation desulfurization and realizing the resource utilization of wastewater. The operation is simple, the reaction conditions are mild, safe, and the energy consumption is low. Compared with the biological method, it is less affected by environmental factors, has a faster reaction rate, and has practical application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a diagram showing the effect of Fe@MoS2 / CFC||CFC system removing sulfur ions after reacting for 1.5 hours under air exposure conditions.

[0023] Figure 2 This is a diagram showing the effect of the CFC||CFC system removing sulfide ions after reacting for 1.5 hours under air exposure conditions.

[0024] Figure 3 This is a diagram showing the effect of removing sulfur ions by the Fe@MoS2 / CFC||CFC system under argon aeration for 1.5 hours. DETAILED DESCRIPTION

[0025] The specific implementation of the present invention is described in detail below in conjunction with the technical scheme and the accompanying drawings.

[0026] Example 1: Preparation of catalytic electrodes and construction of piezoelectric catalytic fuel cells and their coupling systems

[0027] Step 1: Preparation of catalytic electrode:

[0028] (1) Cut 6×10cm 2 The carbon fiber cloth was soaked in anhydrous ethanol for 24 h and then repeatedly rinsed with deionized water to remove surface impurities. The cloth was placed in a vacuum drying oven and dried at 60° C. for 6 h to obtain a clean carbon fiber cloth for use.

[0029] (2) 1.2 g Na2MoO4·2H2O and 0.76 g CH4N2S were dissolved in 500 mL deionized water and stirred for 30 min to obtain a seed solution. A clean carbon fiber cloth was soaked in the seed solution for 1 h, taken out and placed in a vacuum drying oven at 60°C for 6 h to obtain a pretreated carbon fiber cloth.

[0030] (3) Add 0.56g FeSO4·xH2O, 1.36g Na2MoO4·2H2O and 1.06g CH4N2S to 60mL deionized water, stir for 30min, and obtain a precursor solution. Place the pretreated carbon fiber cloth close to the inner wall of the reactor, pour the precursor solution, and place it in the reactor for hydrothermal reaction at 200℃ for 20h. After the reaction, cool the reactor naturally to room temperature, take out the Fe@MoS2-loaded carbon fiber cloth, rinse it repeatedly with deionized water, place it in a vacuum drying oven at 60℃ for 6h, and cut it into 3×3cm 2 , and Fe@MoS2 / CFC piezoelectric catalytic electrode was obtained. The CFC cathode was made of a 3×3 cm 2 The clean carbon fiber cloth obtained by the method of step (1).

[0031] Step 2: Construction of piezoelectric catalytic fuel cell and its coupling system: Select a cylindrical glass reactor with a volume of 100 mL. Put Fe@MoS2 / CFC as the piezoelectric catalytic electrode and CFC as the counter electrode into the reactor, connect them with a wire and a 300Ω external resistor, and use S 2- The concentration is 180 mg L -1 Sodium sulfide (Na2S·9H2O) solution was used as the electrolyte. 90 mL was poured into the reactor. The aeration head was inserted into the bottom of the reactor. The aeration rate was 3 L min -1 , as a provider of dissolved oxygen and mechanical force. The reaction was carried out at 25°C for 1.5 hours. After the reaction started, samples were taken every 15 minutes and the S content in the solution was determined by methylene blue spectrophotometry. 2- The concentration of S in the system is calculated. 2- Concentration changes and removal efficiency.

[0032] like Figure 1The Fe@MoS2 / CFC||CFC piezoelectric catalytic fuel cell system reacts for 1.5h to generate S under aeration conditions. 2- The removal effect diagram of S. As can be seen from the figure, after 1.5h of reaction, the system 2- The removal efficiency is 91% and the removal rate is 10.05 mg h -1 This indicates that the piezoelectric catalytic fuel cell coupled with the aeration system can effectively remove S from the solution. 2- .

[0033] Comparative Example 1: CFC||CFC oxidizes S under aeration conditions 2-

[0034] The system construction method is the same as that of Example 1, except that the piezoelectric catalytic electrode is replaced by a CFC electrode.

[0035] like Figure 2 The CFC||CFC system reacts for 1.5h under aeration conditions to react with S 2- The removal effect diagram of S. As can be seen from the figure, after 1.5h of reaction, the system 2- The removal efficiency was 34% and the removal rate was 3.87 mg h -1 Compared with Example 2, it is shown that the piezoelectric catalytic activity of the Fe@MoS2 / CFC electrode has a positive effect on removing sulfides from water and improves the desulfurization capacity.

[0036] Comparative Example 2: Fe@MoS2 / CFC||CFC oxidizes S under argon exposure 2-

[0037] The method for constructing a piezoelectric catalytic fuel cell is the same as that in Example 1, except that the air exposed to the system is replaced with argon gas at the same flow rate.

[0038] like Figure 3 Fe@MoS2 / CFC||CFC reacts for 1.5h to S under argon atmosphere 2- The removal effect diagram of S. As can be seen from the figure, after 1.5h of reaction, the system 2- The removal efficiency was 24% and the removal rate was 2.66 mg h -1 Compared with Example 1, it shows that oxygen is more effective in removing S from water. 2- The catalytic electrode plays an important role in the desulfurization process. It has the best desulfurization effect when it is coupled with air exposure.

[0039] Example 2: Construction of piezoelectric catalytic fuel cell and its coupling system

[0040] The preparation method of the catalytic electrode and the sulfur ion test method are the same as those in Example 1. However, in the construction of the piezoelectric catalytic fuel cell and its coupling system: In this example, a cylindrical insulating material reactor with a volume of 100 mL is selected. Fe@MoS2 / CFC is a piezoelectric catalytic electrode, and CFC is a counter electrode. The reactor is placed and connected with a wire and a 10Ω external resistor. 2- Concentration is 200mgL -1 Sodium sulfide (Na2S·9H2O) solution was used as the electrolyte. 90 mL was poured into the reactor. The aeration head was inserted into the bottom of the reactor. The aeration rate was 3.5 L min -1 , as a provider of dissolved oxygen and mechanical force. At 20℃, the reaction lasted for 1.5h.

[0041] Example 3: Construction of piezoelectric catalytic fuel cell and its coupling system

[0042] The preparation method of the catalytic electrode and the sulfur ion test method are the same as those in Example 1. However, in the construction of the piezoelectric catalytic fuel cell and its coupling system: In this example, a cylindrical insulating material reactor with a volume of 100 mL is selected. Fe@MoS2 / CFC is a piezoelectric catalytic electrode, and CFC is a counter electrode. The reactor is placed and connected with a wire and a 2000Ω external resistor. 2- Concentration is 150mgL -1 Sodium sulfide (Na2S·9H2O) solution was used as the electrolyte. 90 mL was poured into the reactor. The aeration head was inserted into the bottom of the reactor. The aeration rate was 0.8 L min -1 , as a provider of dissolved oxygen and mechanical force. At 30℃, the reaction lasted for 1.5h.

[0043] Example 4: Preparation of catalytic electrodes and construction of piezoelectric catalytic fuel cells and their coupling systems

[0044] Step 1: Preparation of catalytic electrode:

[0045] (1) Cut into 5×9cm 2 The carbon fiber cloth was soaked in anhydrous ethanol for 8 h and then repeatedly rinsed with deionized water to remove surface impurities. The cloth was placed in a vacuum drying oven and dried at 80°C for 4 h to obtain a clean carbon fiber cloth for use.

[0046] (2) 1.2 g Na2MoO4·2H2O and 0.76 g CH4N2S were dissolved in 500 mL deionized water and stirred for 30 min to obtain a seed solution. A clean carbon fiber cloth was soaked in the seed solution for 1.5 h, taken out and placed in a vacuum drying oven at 80 ° C for 4 h to obtain a pretreated carbon fiber cloth.

[0047] (3) Add 0.56g FeSO4·xH2O, 1.36g Na2MoO4·2H2O and 1.06g CH4N2S to 60mL deionized water respectively and stir for 30min to obtain a precursor solution. Place the pretreated carbon fiber cloth close to the inner wall of the reactor, pour the precursor solution, and place it in the reactor for hydrothermal reaction at 200℃ for 20h. After the reaction, cool the reactor naturally to room temperature, take out the Fe@MoS2-loaded carbon fiber cloth, rinse it repeatedly with deionized water, place it in a vacuum drying oven at 80℃ for 4h, and cut it into 3×3cm 2 , and Fe@MoS2 / CFC piezoelectric catalytic electrode was obtained. The CFC cathode was made of a 3×3 cm 2 The clean carbon fiber cloth obtained by the method of step (1).

[0048] Step 2: The construction method of the piezoelectric catalytic fuel cell and the sulfur ion testing method are the same as those in Example 1.

Claims

1. A method for removing sulfur ions from water by coupling piezoelectric catalytic fuel cells with oxygen oxidation, characterized in that: Here are the steps: The piezoelectric anode and cathode are connected through an external circuit and placed in an insulating material reactor, with the pollutant solution to be treated as the electrolyte; the aeration head is extended to the bottom of the reactor as a provider of dissolved oxygen and mechanical external force; the reaction begins when the aeration pump is turned on, and the power generation and sulfur ion removal effects are adjusted by adjusting the aeration intensity, the temperature of the pollutant solution to be treated and the external resistance value of the external circuit.

2. The method for removing sulfur ions from water by coupling piezoelectric catalytic fuel cells with oxygen oxidation according to claim 1, characterized in that: Preparation of piezoelectric anode: The clean carbon fiber cloth CFC after impurities removal by anhydrous ethanol is immersed in a seed solution containing Na2MoO4·2H2O and CH4N2S, and then placed in a vacuum drying oven for a period of time to obtain a seed layer CFC; FeSO4·xH2O, Na2MoO4·2H2O and CH4N2S are added to deionized water, stirred evenly, and the mixed solution is poured into a reactor; the seed layer CFC is placed in the reactor containing the mixed solution to perform a hydrothermal reaction; after the reaction is completed, the reactor is naturally cooled to room temperature, the CFC loaded with Fe@MoS2 is taken out, repeatedly rinsed with deionized water, and fully dried in a vacuum drying oven to obtain a Fe@MoS2 / CFC piezoelectric catalytic electrode.

3. The method for removing sulfur ions from water by coupling piezoelectric catalytic fuel cells with oxygen oxidation according to claim 2, characterized in that: The molar concentration of S in the seed solution is 0.01M-0.03M, which is 2-3 times that of Mo; the soaking time of clean CFC in the seed solution is 0.5h-2h.

4. The method for removing sulfur ions from water by coupling piezoelectric catalytic fuel cells with oxygen oxidation according to claim 2, characterized in that: In the mixed solution of FeSO4·xH2O, Na2MoO4·2H2O and CH4N2S, the molar concentration ratio of Fe and Mo is less than or equal to 1:1, and the molar concentration of S is 0.15M-0.25M, which is 2-3 times the sum of the molar concentrations of Fe and Mo.

5. The method for removing sulfur ions from water by coupling piezoelectric catalytic fuel cells with oxygen oxidation according to claim 2, characterized in that: The addition ratio of seed layer CFC to mixed solution is 1cm 2 :70mL-1cm 2 :0.9mL.

6. The method for removing sulfur ions from water by coupling piezoelectric catalytic fuel cells with oxygen oxidation according to claim 2, characterized in that: The temperature of the hydrothermal reaction is 180°C-220°C, and the time is 15h-25h.

7. The method for removing sulfur ions from water by coupling piezoelectric catalytic fuel cells with oxygen oxidation according to claim 2, characterized in that: The vacuum drying temperature is 60°C-80°C, and the drying time is 4h-6h.

8. The method for removing sulfur ions from water by coupling piezoelectric catalytic fuel cells with oxygen oxidation according to claim 1, characterized in that: The external circuit includes a wire and an external resistor, and the connection method is: wires are led out from the piezoelectric anode and cathode respectively, and the two ends of the external resistor are connected to form a loop; further, the resistance range of the external resistor is 10Ω-2000Ω; the flow rate of the exposed air is 0.8L min -1 -3.5L min -1 ; The temperature of the pollutant solution to be treated is 20°C-30°C.

9. The method for removing sulfur ions from water by coupling piezoelectric catalytic fuel cells with oxygen oxidation according to claim 1, characterized in that: The material of the cathode is a conductive substrate, such as carbon fiber cloth. The cathode material may also be a piezoelectric catalytic cathode or an electrocatalytic cathode in which a piezoelectric catalyst or an electrocatalyst is loaded on a conductive substrate.

10. The method for removing sulfur ions from water by coupling piezoelectric catalytic fuel cells with oxygen oxidation according to claim 1, characterized in that: Through aeration coupled with piezoelectric effect, sulfur ions in water, difficult-to-degrade organic pollutants, or sterilization can be efficiently removed.

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