Method for simultaneous treatment of a mixture of sulfur-containing and nitrogen-containing oxides
By constructing a three-electrode photoelectrochemical cell with a MoS2/Fe2O3 photoanode and a copper nanowire-modified foamed copper cathode, the problem of simultaneously processing sulfur- and nitrogen-containing oxides was solved, achieving low-cost and efficient resource recovery.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANGHAI JIAOTONG UNIV
- Filing Date
- 2023-03-03
- Publication Date
- 2026-05-12
AI Technical Summary
Existing technologies are insufficient for efficiently and simultaneously treating mixed pollutants containing sulfur and nitrogen oxides in the air, and existing methods suffer from high costs or inapplicability.
采用MoS2/Fe2O3光阳极、铜纳米线修饰的泡沫铜阴极、Ag/AgCl参比电极构成三电极体系，利用光电化学池在模拟太阳光下通过负偏电压处理含硫和含氮氧化物混合物，生成亚硫酸根和硝酸根溶液，利用铜纳米线还原氨氮，MoS2/Fe2O3光阳极活化亚硫酸根为硫酸根自由基，实现同步处理。
It achieves low-cost and high-efficiency reduction of nitrogen oxides to nitrogen gas and oxidation of sulfur oxides to sulfate, simultaneously treating sulfur- and nitrogen-containing oxides, with high resource utilization rate and energy-saving advantages.
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Figure CN116422136B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a technology in the field of environmental pollution control, specifically a method for simultaneously treating a mixture of sulfur-containing and nitrogen-containing oxides. Background Technology
[0002] Sulfur and nitrogen oxides, as mixed pollutants, are widely present in the air and have many adverse effects on ecosystems and human health. Various methods have been studied to treat mixtures of sulfur and nitrogen oxides, such as selective catalytic reduction (SCR) and limestone wet treatment. SCR involves adding ammonia gas and catalytically reducing nitrogen oxides on the catalyst surface; however, the high gas temperature makes the catalyst highly susceptible to poisoning. Limestone wet treatment involves spraying a high-concentration calcium hydroxide solution to absorb sulfur and nitrogen oxide gases, requiring high investment and generating large amounts of sludge, resulting in high operating costs. Existing free radical oxidation technologies can treat sulfur oxides or ammonia nitrogen compounds individually; for example, ammonia nitrogen pollutants can be treated by photoanodic oxidation of sulfite to form free radicals. However, because nitrogen oxides are high-valence oxides, free radical oxidation technology is not suitable for treating nitrogen oxides or mixtures of sulfur and nitrogen oxides. Summary of the Invention
[0003] To address the aforementioned shortcomings of existing technologies, this invention proposes a method for simultaneously processing mixtures of sulfur- and nitrogen-containing oxides. This method can selectively, rapidly, and efficiently reduce nitrogen oxides to nitrogen gas and oxidize sulfur oxides to sulfates, thereby achieving simultaneous processing of sulfur oxides and nitrogen oxides.
[0004] This invention is achieved through the following technical solution:
[0005] This invention relates to a method for simultaneously processing a mixture of sulfur- and nitrogen-containing oxides, using MoS2 / Fe2O3 as the photoanode, copper nanowire-modified copper foam as the cathode, and Ag / AgCl as the reference electrode, while absorbing SO2 and NO with sodium hydroxide solution. x The mixture of sulfite and nitrate forms an electrolyte and constitutes a photoelectrochemical cell with a three-electrode system. By applying a negative bias voltage between the cathode and the reference electrode and simulating sunlight, the reaction proceeds fully. The copper nanowire-modified foamed copper cathode reduces nitrate to ammonia nitrogen, and the MoS2 / Fe2O3 photoanode activates sulfite in situ to sulfite radicals and then to sulfate radicals. The generated ammonia nitrogen is selectively oxidized to nitrogen gas by the sulfate radicals, thereby achieving the simultaneous treatment of a mixture of sulfur-containing and nitrogen-containing oxides.
[0006] The simulated sunlight has a light intensity of 100 mW / cm². -2 .
[0007] The negative voltage refers to applying a bias voltage of -1.0 to -1.6V to the copper nanowire-modified foamed copper cathode.
[0008] The concentration of the sodium hydroxide solution is 0.1–5 mol / L.
[0009] The concentration of the nitrate solution is 20–30 mg / L.
[0010] The concentration of the sulfite solution is 350–750 mg / L.
[0011] The photoanode is formed on the cleaned FTO surface using a hydrothermal method to create a Fe2O3 film; then the Fe2O3 / FTO modified with the Fe2O3 film is reacted with 30 mmol / L (NH4)6Mo7O 24 A mixed solution of 1 mol / L thiourea was placed in a stainless steel autoclave lined with polytetrafluoroethylene and heated at 160–200 °C for 60–120 minutes, and then allowed to cool naturally to obtain a MoS2 / Fe2O3 photoanode.
[0012] The cathode is prepared by immersing a cleaned copper foam sheet in a mixed aqueous solution containing 2-3 mol / L sodium hydroxide and 0.1-0.2 mol / L ammonium persulfate for 6 minutes, thereby growing Cu(OH)₂ nanowires in situ on the surface of the copper foam sheet. After rinsing with water, the Cu(OH)₂ nanowire-modified copper foam electrode is placed in a muffle furnace and heated at 180°C for 180 minutes to obtain CuO nanowires. The CuO nanowire-modified copper foam electrode is used as the cathode and Pt as the counter electrode. It is placed in a sodium sulfate solution containing 1 mol / L and subjected to an electroreduction reaction with an applied bias voltage of -1.0V for 20-40 minutes to obtain copper nanowire-modified copper foam.
[0013] Technical effect
[0014] Compared with existing technologies, this invention uses sodium hydroxide solution as an absorbent to simultaneously absorb SO2 and NO from mixed gases such as flue gas. xThis invention directly converts a mixed gas into a mixed solution of sulfite and nitrate ions, using this solution as an electrolyte for photoelectrochemical resource recovery. Therefore, this method offers advantages such as low cost, high resource utilization rate, and energy saving. Secondly, a MoS2 / Fe2O3 photoanode is used to efficiently activate sulfite ions in situ into sulfite and sulfate radicals. Nitrate formed from nitrogen oxides is reduced to ammonia nitrogen on a copper nanowire-modified foamed copper cathode. Through highly selective oxidation with sulfate radicals, nitrogen gas and sulfate are formed. The entire process requires no additional sulfite addition, achieving simultaneous and efficient treatment of nitrogen oxides and sulfur oxides. The MoS2 / Fe2O3 catalyst prepared in this invention exhibits excellent alkali corrosion resistance and significant visible light absorption characteristics, enabling prolonged activation of sulfite ions to sulfate radicals in alkaline solutions under visible light. Simultaneously, the copper nanowire-modified foamed copper cathode efficiently reduces nitrates to ammonia nitrogen. These features collectively achieve the simultaneous treatment of mixtures containing sulfur and nitrogen oxides. Attached Figure Description
[0015] Figure 1 A three-electrode photoelectric system was constructed for Example 1;
[0016] Figure 2 This is a diagram showing the results of simultaneous processing of sulfur oxides and nitrogen oxides using a three-electrode photoelectric system in Example 1;
[0017] Figure 3 This is a comparison diagram of different catalytic systems in Example 1;
[0018] In the figure: a shows the change trend of nitrogen oxides over time under different catalytic systems; b shows the change trend of sulfides over time under different catalytic systems.
[0019] Figure 4 This is a graph showing the changes in sulfate free radicals in the three-electrode photoelectric system of Example 1. Detailed Implementation
[0020] Example 1
[0021] This embodiment relates to a method for simultaneously processing a mixture of sulfur- and nitrogen-containing oxides, employing a MoS2 / Fe2O3 photoanode, a copper nanowire-modified foamed copper cathode, an Ag / AgCl reference electrode, and a 1 mol / L sodium hydroxide solution to absorb SO2 and NO. x The sulfite and nitrate solutions formed by the mixture act as electrolytes in a three-electrode photoelectrochemical cell with a light intensity of 90 mW / cm². -2 The simulated sunlight intensity was used to apply a bias voltage of -1.2V to a copper nanowire-modified foamed copper cathode, and the reaction was carried out for 120 minutes.
[0022] The photoanode MoS2 / Fe2O3 described in this embodiment is prepared by: forming a Fe2O3 film on a cleaned FTO surface using a hydrothermal method; then mixing the Fe2O3 / FTO modified with the Fe2O3 film with 30 mmol / L (NH4)6Mo7O 24 A mixed solution of 1 mol / L thiourea was placed in a stainless steel autoclave lined with polytetrafluoroethylene and heated at 180°C for 90 minutes, then allowed to cool naturally to obtain a MoS2 / Fe2O3 photoanode.
[0023] The copper nanowire-modified foamed copper cathode described in this embodiment is prepared as follows: a cleaned foamed copper sheet is immersed in a mixed aqueous solution containing 2.5 mol / L sodium hydroxide and 0.125 mol / L ammonium persulfate for 6 minutes, and Cu(OH)2 nanowires are grown in situ on the surface of the foamed copper sheet. After rinsing with water, the Cu(OH)2 nanowire-modified foamed copper electrode is placed in a muffle furnace and heated at 180°C for 180 minutes to obtain CuO nanowires. The CuO nanowire-modified foamed copper electrode is used as the cathode and Pt is used as the counter electrode. The electrode is placed in a sodium sulfate solution containing 1 mol / L and an external bias voltage of -1.0V is applied to carry out an electroreduction reaction for 30 minutes to obtain copper nanowires on the surface of the foamed copper.
[0024] The nitrate solution concentration is 30 mg / L, the sulfite solution concentration is 650 mg / L, and nitrogen oxides and sulfur compounds are removed by 99.9% and 99.9%, respectively.
[0025] The following uses a comparative example to illustrate the effect of Example 1:
[0026] As a control, under the same conditions as in Example 1, two control groups were set up: one for the electrocatalytic system constructed with light-shielding treatment and the other for the photocatalytic system constructed without bias voltage treatment, as shown in Table 1. Example 1 of the photocatalytic system exhibited good performance in the simultaneous application of sulfur- and nitrogen-containing oxide mixtures.
[0027] Table 1. Comparison of parameters between Example 1, the control group, and the prior art.
[0028] project Example 1 Control group 1 Control group 2 Catalysis type Photoelectrocatalytic system Electrocatalytic system Photocatalytic system reaction time 120min 120min 120min Nitrogen oxide removal rate 99.9％ 28.7％ 8.7％ sulfur oxide removal rate 99.9％ 79.2％ 39.0％
[0029] like Figure 1 The diagram shown is a schematic of the three-electrode photoelectrocatalytic system device constructed in this embodiment.
[0030] like Figure 2 As shown, the three-electrode photoelectrocatalytic system constructed in this embodiment can achieve rapid and efficient simultaneous removal of sulfur-containing and nitrogen-containing oxide mixtures.
[0031] like Figure 3As shown, the three-electrode photoelectrocatalytic system constructed in this embodiment significantly improves the simultaneous removal capacity of sulfur-containing and nitrogen-containing oxide mixtures.
[0032] like Figure 4 As shown, the three-electrode photoelectrocatalytic system constructed in this embodiment can effectively activate sulfite ions in situ into sulfate radicals.
[0033] Example 2
[0034] This embodiment relates to a method for simultaneously processing a mixture of sulfur- and nitrogen-containing oxides. It employs a MoS2 / Fe2O3 photoanode, a copper nanowire-modified foamed copper cathode, an Ag / AgCl reference electrode, and a 0.1 mol / L sodium hydroxide solution to absorb SO2 and NO. x The mixture forms a sulfite solution and a nitrate solution, which serve as electrolytes in a three-electrode photoelectrochemical cell. The photoelectrochemical cell operates with a light intensity of 100 mW / cm². -2 To simulate sunlight intensity, a bias voltage of -1.6V was applied to a copper nanowire-modified foamed copper cathode, and the reaction was allowed to proceed for 120 minutes.
[0035] The photoanode MoS2 / Fe2O3 described in this embodiment is prepared by: forming a Fe2O3 film on a cleaned FTO surface using a hydrothermal method; then mixing the Fe2O3 / FTO modified with the Fe2O3 film with 30 mmol / L (NH4)6Mo7O 24 A mixed solution of 1 mol / L thiourea was placed in a stainless steel autoclave lined with polytetrafluoroethylene and heated at 200°C for 120 minutes, then allowed to cool naturally to obtain a MoS2 / Fe2O3 photoanode.
[0036] The copper nanowire-modified foamed copper cathode described in this embodiment is prepared as follows: a cleaned foamed copper sheet is immersed in a mixed aqueous solution containing 3 mol / L sodium hydroxide and 0.15 mol / L ammonium persulfate for 6 minutes, and Cu(OH)2 nanowires are grown in situ on the surface of the foamed copper sheet. After rinsing with water, the Cu(OH)2 nanowire-modified foamed copper electrode is placed in a muffle furnace and heated at 180°C for 180 minutes to obtain CuO nanowires. The CuO nanowire-modified foamed copper electrode is used as the cathode and Pt is used as the counter electrode. The electrode is placed in a sodium sulfate solution containing 1 mol / L and an external bias voltage of -1.0V is applied to carry out an electroreduction reaction for 20 minutes to obtain copper nanowires on the surface of the foamed copper.
[0037] The nitrate solution concentration was 30 mg / L, the sulfite solution concentration was 500 mg / L, and nitrogen oxides and sulfur compounds were removed by 93.1% and 99.9%, respectively.
[0038] Example 3
[0039] This embodiment relates to a method for simultaneously processing a mixture of sulfur- and nitrogen-containing oxides, employing a MoS2 / Fe2O3 photoanode, a copper nanowire-modified foamed copper cathode, an Ag / AgCl reference electrode, and a 5 mol / L sodium hydroxide solution to absorb SO2 and NO. x The mixture forms a sulfite solution and a nitrate solution, which serve as electrolytes in a three-electrode photoelectrochemical cell. The photoelectrochemical cell operates with a light intensity of 80 mW / cm². -2 To simulate sunlight intensity, a bias voltage of -1.0V was applied to a copper nanowire-modified foamed copper cathode, and the reaction was allowed to proceed for 120 minutes.
[0040] The photoanode MoS2 / Fe2O3 described in this embodiment is prepared by: forming a Fe2O3 film on a cleaned FTO surface using a hydrothermal method; then mixing the Fe2O3 / FTO modified with the Fe2O3 film with 30 mmol / L (NH4)6Mo7O 24 A mixed solution of 1 mol / L thiourea was placed in a stainless steel autoclave lined with polytetrafluoroethylene and heated at 180°C for 120 minutes, then allowed to cool naturally to obtain a MoS2 / Fe2O3 photoanode.
[0041] The copper nanowire-modified foamed copper cathode described in this embodiment is prepared as follows: a cleaned foamed copper sheet is immersed in a mixed aqueous solution containing 3 mol / L sodium hydroxide and 0.2 mol / L ammonium persulfate for 6 minutes, and Cu(OH)2 nanowires are grown in situ on the surface of the foamed copper sheet. After rinsing with water, the Cu(OH)2 nanowire-modified foamed copper electrode is placed in a muffle furnace and heated at 180°C for 180 minutes to obtain CuO nanowires. The CuO nanowire-modified foamed copper electrode is used as the cathode and Pt is used as the counter electrode. The electrode is placed in a sodium sulfate solution containing 1 mol / L and an external bias voltage of -1.0V is applied to carry out an electroreduction reaction for 20 minutes to obtain copper nanowires on the surface of the foamed copper.
[0042] The nitrate solution concentration is 20 mg / L, the sulfite solution concentration is 750 mg / L, and nitrogen oxides and sulfur compounds are removed by 99.9% and 99.8%, respectively.
[0043] The above-described specific implementations can be partially adjusted by those skilled in the art in different ways without departing from the principles and purpose of the present invention. The scope of protection of the present invention is defined by the claims and is not limited to the above-described specific implementations. All implementation schemes within the scope of the claims are bound by the present invention.
Claims
1. A method for simultaneously processing a mixture of sulfur-containing and nitrogen-containing oxides, characterized in that, MoS2 / Fe2O3 was used as the photoanode, copper nanowire-modified copper foam as the cathode, and Ag / AgCl as the reference electrode. Sodium hydroxide solution was used to absorb SO2 and NO. x The mixture of sulfite and nitrate forms an electrolyte and constitutes a photoelectrochemical cell with a three-electrode system. By applying a negative bias voltage between the cathode and the reference electrode and simulating sunlight, the reaction proceeds fully. The copper nanowire-modified foamed copper cathode reduces nitrate to ammonia nitrogen, and the MoS2 / Fe2O3 photoanode activates sulfite in situ to sulfite radicals and then to sulfate radicals. The generated ammonia nitrogen is selectively oxidized to nitrogen gas by the sulfate radicals, thereby achieving the simultaneous treatment of a mixture of sulfur-containing and nitrogen-containing oxides.
2. The method for simultaneously processing a mixture of sulfur-containing and nitrogen-containing oxides according to claim 1, characterized in that, The simulated sunlight has a light intensity of 100 mW / cm². -2 .
3. The method for simultaneously processing a mixture of sulfur-containing and nitrogen-containing oxides according to claim 1, characterized in that, The negative bias voltage refers to the bias voltage of -1.0 to -1.6 V applied to the copper nanowire-modified foamed copper cathode.
4. The method for simultaneously processing a mixture of sulfur-containing and nitrogen-containing oxides according to claim 1, characterized in that, The concentration of the sodium hydroxide solution is 0.1~5 mol / L.
5. The method for simultaneously processing a mixture of sulfur-containing and nitrogen-containing oxides according to claim 1, characterized in that, The concentration of the nitrate solution is 20~30 mg / L.
6. The method for simultaneously processing a mixture of sulfur-containing and nitrogen-containing oxides according to claim 1, characterized in that, The concentration of the sulfite solution is 350~750 mg / L.
7. The method for simultaneously processing a mixture of sulfur-containing and nitrogen-containing oxides according to claim 1, characterized in that, The photoanode is formed on the cleaned FTO surface using a hydrothermal method to create a Fe2O3 film; then the Fe2O3 / FTO modified with the Fe2O3 film is reacted with 30 mmol / L (NH4)6Mo7O 24 A mixed solution of 1 mol / L thiourea was placed in a stainless steel autoclave lined with polytetrafluoroethylene and heated at 160-200 °C for 60-120 minutes, and then allowed to cool naturally to obtain a MoS2 / Fe2O3 photoanode.
8. The method for simultaneously processing a mixture of sulfur-containing and nitrogen-containing oxides according to claim 1 or 3, characterized in that, The cathode is prepared by immersing a cleaned copper foam sheet in a mixed aqueous solution containing 2-3 mol / L sodium hydroxide and 0.1-0.2 mol / L ammonium persulfate for 6 minutes, thereby growing Cu(OH)2 nanowires in situ on the surface of the copper foam sheet. After rinsing with water, the copper foam electrode modified with Cu(OH)2 nanowires is placed in a muffle furnace and heated at 180°C for 180 minutes to obtain CuO nanowires. The CuO nanowire-modified copper foam electrode is used as the cathode and Pt is used as the counter electrode. The electrode is placed in a sodium sulfate solution containing 1 mol / L and an external bias voltage of -1.0 V is applied to carry out an electroreduction reaction for 20-40 minutes to obtain copper nanowire-modified copper foam.