Low energy consumption electrochemical water treatment process based on waste string cathode

Abstract

The application discloses a kind of low-energy-consumption electrochemical water treatment processes based on waste string cathode, belong to electrochemical oxidation and wastewater treatment technical field. On the one hand, waste string is high-temperature heat treated, and waste string cathode material is obtained;On the other hand, Sb-SnO2 precursor solution is prepared by hydrothermal method, and further Sb-SnO2 nano powder is obtained, then Sb-SnO2 nano powder is loaded on carbon felt, and CF / Sb-SnO2 composite anode material is obtained. The prepared cathode and anode material form a bipolar electrochemical synergistic degradation system, which can efficiently degrade rhodamine B under a low current of 0.001 A. The process is simple, low in cost, and high in removal efficiency, solving the problems of single catalytic activity and poor mechanical strength of traditional electrodes, and having a wide application prospect in the field of refractory wastewater treatment and resource recovery.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical oxidation and wastewater treatment technology, specifically relating to a low-energy electrochemical water treatment process based on waste string cathodes. Background Technology

[0002] With the development of the dye industry, wastewater discharge from textile printing and dyeing industries has continued to rise. Textile wastewater accounts for approximately one-tenth of the total industrial wastewater annually, with dye wastewater accounting for up to 80% of that. Rhodamine B, a typical water-soluble synthetic dye, is widely used in textile printing and dyeing due to its bright color and high stability. However, it is structurally stable, difficult to biodegrade, and possesses strong irritant properties, reproductive and neurotoxic effects, and potential carcinogenic risks. Therefore, developing efficient and stable technologies for degrading Rhodamine B is of great significance for controlling dye wastewater pollution.

[0003] Due to the recalcitrant, highly toxic, and easily accumulated nature of Rhodamine B, traditional physical adsorption (phase transfer only) and biological methods (low efficiency) are insufficient to achieve its complete mineralization. In contrast, electrochemical oxidation technology utilizes active free radicals (such as ·OH) generated on the electrode surface to directly break down the Rhodamine B molecular chain and mineralize it into CO2 and H2O. This technology offers advantages such as mild reaction conditions, no need for added chemical reagents, and no secondary pollution, demonstrating significant potential for treating high-concentration, recalcitrant dye wastewater.

[0004] In electrocatalytic oxidation technology, the anode and cathode materials are the core determinants of the reaction pathway and energy efficiency. The anode directly regulates the generation of active species such as ·OH, which dominates the mineralization of pollutants; the cathode reduces energy loss by suppressing hydrogen evolution side reactions and improves the system's current efficiency and oxidation performance by utilizing in-situ generation of media such as H2O2. Given the high cost and insufficient long-term stability of traditional electrode materials, the development of electrode materials that combine high activity and low cost is extremely crucial.

[0005] Traditional cathode materials (such as carbon-based and precious metal materials) generally suffer from limitations such as high manufacturing costs, complex processes, and insufficient mechanical strength. Meanwhile, the guzheng, a traditional Chinese musical instrument with a wide audience, generates a large quantity of discarded strings from playing and aging, which are then considered waste with no effective means of resource recovery. Against this backdrop, utilizing these discarded strings to prepare water treatment cathodes shows significant advantages. These strings originate from solid waste generated after use, are widely available, low in cost, and contain metallic components, possessing excellent conductivity and mechanical strength. They hold promise for yielding highly promising electrocatalytic cathode materials through simple processing.

[0006] Furthermore, while carbon felt is widely used in anodic degradation systems due to its large specific surface area and good conductivity, its inherent defects severely limit its long-term stability: strong hydrophobicity makes loading difficult, it is prone to electrochemical corrosion and surface oxidation at high anodic potentials, and its low mechanical strength leads to wear and powdering. Therefore, its degradation capacity is often limited in actual wastewater treatment. Sb-SnO2, with its high oxygen evolution overpotential and chemical stability, is an ideal anodic material for efficiently generating ·OH radicals and achieving deep mineralization of Rhodamine B, but when used alone, it suffers from poor conductivity and easy deactivation and shedding. Therefore, there is still a lack of stable, low-cost, and highly efficient materials for treating highly recalcitrant dye wastewater. Summary of the Invention

[0007] To address the aforementioned deficiencies in existing technologies, this invention provides a low-energy electrochemical water treatment process based on waste string cathodes. The prepared anode and cathode materials are combined to form a bipolar electrochemical synergistic degradation system, which can achieve the degradation of Rhodamine B under low current conditions. This process has advantages such as low cost, high removal efficiency, and good stability.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A low-energy electrochemical water treatment process based on waste guitar string cathodes includes the following steps:

[0010] Step a: Perform high-temperature heat treatment on the waste strings to obtain the waste string cathode material;

[0011] Step b: Prepare Sb-SnO2 precursor solution by hydrothermal method, disperse and load the obtained Sb-SnO2 nanoparticles on carbon felt (CF), and dry to obtain CF / Sb-SnO2 composite anode material;

[0012] Step c: The CF / Sb-SnO2 composite anode material and the waste string cathode material are used as the anode and cathode electrodes, respectively, and placed in a bipolar electrochemical synergistic degradation system under a DC electrode system to electrocatalytically degrade organic pollutant wastewater.

[0013] As a preferred technical solution of the present invention, step a is specifically as follows:

[0014] a1: Place the waste guitar strings in a muffle furnace, heat them to 500 ℃ at a heating rate of 10 ℃ / min, and hold them at that temperature for 1 h. After natural cooling, the waste guitar string cathode material can be obtained.

[0015] As a preferred embodiment of the present invention, step b specifically involves the following steps:

[0016] b1: Add 45 mmol SnCl4·5H2O and 2 mmol SbCl3 to 100 mL of isopropanol, stir until the solution is clear;

[0017] b2: Transfer the solution to a reaction vessel and react at 200 °C for 24 h. After the reaction is complete, cool to room temperature to obtain Sb-SnO2 suspension.

[0018] b3: The Sb-SnO2 suspension was centrifuged and washed, and the washed product was dried in an oven at 80 ℃ for 2 h and then ground to obtain Sb-SnO2 nanopowder.

[0019] b4: The Sb-SnO2 nanoparticles obtained in step b3 are dispersed in anhydrous ethanol, uniformly drop-coated onto carbon felt (CF), and dried at 80 °C to obtain the CF / Sb-SnO2 composite anode material, wherein the Sb-SnO2 loading is 0.7 ~ 0.9 mg / cm³. 2 .

[0020] As a preferred embodiment of the present invention, the organic pollutant electrocatalytically degraded in step c is Rhodamine B, the electrolyte used in the electrocatalytic degradation is 0.1 mol / L Na₂SO₄, and the anode-cathode distance is 4 cm. The current during electrocatalytic degradation is 0.001 A.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] 1. The carbon felt used in this invention, as a three-dimensional porous conductive carrier, not only provides excellent electron transport channels but also significantly increases the loading of Sb-SnO2 and the exposure of active sites due to its huge specific surface area, while enhancing the overall mechanical strength and corrosion resistance of the electrode. By loading Sb-SnO2 onto the carbon felt and synergistically integrating the advantages of the two materials, the limitations of a single electrode can be overcome, significantly improving the treatment efficiency and stability of the electrochemical system for recalcitrant dye wastewater.

[0023] 2. This invention processes waste musical instruments strings into cathode materials, which not only enables the resource utilization of difficult-to-recycle solid waste, but also significantly reduces the cost of electrode preparation and environmental burden, providing a new approach for developing efficient and low-cost environmental functional materials. Compared with traditional carbon-based or precious metal cathodes, it can also provide excellent oxygen reduction catalytic activity to efficiently generate H2O2 due to its metal alloy composition.

[0024] 3. The bipolar-controlled CF / Sb-SnO2 waste string composite electrode material prepared by this invention can achieve efficient degradation of Rhodamine B under low current, with high removal rate, short time and low energy consumption. Attached Figure Description

[0025] Figure 1 The image shows the X-ray diffraction pattern of the synthesized waste string cathode material.

[0026] Figure 2 The image shows the X-ray diffraction pattern of the synthesized Sb-SnO2 nanoparticles.

[0027] Figure 3 This is a scanning electron microscope image of the synthesized Sb-SnO2 nanoparticles.

[0028] Figure 4 The degradation effects of different cathode materials on Rhodamine B were compared under the same carbon felt anode conditions with a current of 0.001 A; the concentration of Rhodamine B was 30 mg / L and the concentration of sodium sulfate was 0.1 mol / L.

[0029] Figure 5 The degradation effects of empty carbon felt and carbon felt loaded with Sb-SnO2 were compared under the same cathode conditions of waste string with a current of 0.001 A applied; the concentration of Rhodamine B was 30 mg / L and the concentration of sodium sulfate was 0.1 mol / L.

[0030] Figure 6 Cyclic stability experiments were conducted on the removal of 30 mg / L Rhodamine B using a CF / Sb-SnO2 waste string composite electrode under an applied current of 0.001 A. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings.

[0032] Example 1

[0033] Preparation of CF / Sb-SnO2 waste string composite electrode:

[0034] The discarded strings were selected from discarded guzheng strings that had been played or broken due to aging. The brand and model were Dunhuang A-type guzheng strings, made of nylon steel wire with a steel core and an outer layer of nylon wire. First, the discarded strings were placed in a muffle furnace and heated to 500 ℃ at a rate of 10 ℃ / min, held at that temperature for 1 hour, and then allowed to cool naturally to obtain the cathode material from the discarded strings.

[0035] In a dry 250 mL wide-mouth bottle, 100 mL of isopropanol, 45 mmol of SnCl4·5H2O, and 2 mmol of SbCl3 were added sequentially and stirred until the solution became clear. The solution was transferred to a polytetrafluoroethylene reactor and reacted at 200 °C for 24 h. After the reaction was completed, the mixture was cooled to room temperature to obtain an Sb-SnO2 suspension. This suspension was then centrifuged and washed (three times with distilled water and twice with anhydrous ethanol). The washed product was then dried in an oven at 80 °C for 2 h and ground to obtain Sb-SnO2 nanoparticles. The obtained Sb-SnO2 nanoparticles were dispersed in anhydrous ethanol and uniformly drop-coated onto a carbon felt (1.5 cm wide, 8 cm long, and 0.3 cm thick). The mixture was then dried in an oven at 80 °C to obtain the CF / Sb-SnO2 composite anode material. The Sb-SnO2 loading on the carbon felt was 0.8 mg / cm³. 2 .

[0036] Figure 1 , 2 The images show X-ray diffraction patterns of the waste string cathode material and Sb-SnO2 nanoparticles synthesized by the method described in this embodiment. Figure 3 This is a scanning electron microscope image of the Sb-SnO2 nanoparticles synthesized by the method described in this embodiment. The image shows that the obtained Sb-SnO2 consists of aggregates of loosely packed nanoparticles.

[0037] Example 2

[0038] Application of comparative experiments on the degradation of Rhodamine B by different cathode materials:

[0039] Carbon felt was used as the anode, and carbon felt, graphite rod, stainless steel wire, titanium wire, platinum wire, and waste string cathode material prepared in Example 1 were used as cathodes, respectively.

[0040] The prepared cathode and anode were placed in an electrochemical degradation system with a DC electrode system. The electrocatalytic degradation of 30 mg / L Rhodamine B was performed using 0.1 mol / L Na₂SO₄ as the electrolyte, with a current of 0.001 A and an electrode spacing of 4 cm for 20 min. Figure 4 As shown, the waste string cathode material achieved a 100% removal rate of Rhodamine B within 20 minutes, outperforming all other cathode comparison materials (including the superior precious metal: platinum wire). It exhibited the highest first-order reaction kinetic constant and the strongest oxidation efficiency. Therefore, under the same conditions using carbon felt as the anode, the waste string cathode material demonstrated the fastest Rhodamine B degradation performance.

[0041] Example 3

[0042] Application of CF / Sb-SnO2 waste string composite electrode material in the removal of Rhodamine B from water:

[0043] The waste string cathode material obtained in Example 1 (cut to a length of 8 cm, with an electrode submerged part of about 4 cm) and the CF / Sb-SnO2 composite anode material (width 1.5 cm, length 8 cm, thickness 0.3 cm, with an electrode submerged part of about 4 cm) were placed in an electrochemical degradation system under a DC electrode system. The electrocatalytic degradation of 30 mg / L Rhodamine B was carried out with 0.1 mol / L Na2SO4 as the electrolyte, a current of 0.001 A, an electrode spacing of 4 cm, and an electrochemical degradation period of 20 min.

[0044] Meanwhile, the anode was replaced with an empty carbon felt of the same size, while the cathode remained unchanged. Rhodamine B was degraded under the same parameters and experimental conditions for comparison.

[0045] Within 5 minutes, the removal rate of Rhodamine B by CF / Sb-SnO2 reached nearly 90%, while the removal rate of Rhodamine B by empty carbon felt under the same conditions was only about 70%. Figure 5 (As shown).

[0046] Example 4

[0047] Application of CF / Sb-SnO2 waste string composite electrode material after multiple cycles in the removal of Rhodamine B from water:

[0048] The waste string cathode material and CF / Sb-SnO2 composite anode material obtained in Example 1 were used to repeat the steps in Example 3 for cycle stability testing. After 10 min of degradation, and 15 min of activation with 0.1 mol / L sodium sulfate per cycle, the removal rate of Rhodamine B remained as high as 100% after 5 repeated electrocatalytic degradation experiments. Figure 6 As shown in the figure, this demonstrates that the CF / Sb-SnO2 waste string composite electrode has excellent electrocatalytic stability.

Claims

1. A low-energy electrochemical water treatment process based on waste guitar string cathodes, characterized in that, Includes the following steps: Step a: Perform high-temperature heat treatment on the waste strings to obtain the waste string cathode material; Step b: Prepare Sb-SnO2 precursor solution by hydrothermal method, disperse and load the obtained Sb-SnO2 nanoparticles on carbon felt (CF), and dry to obtain CF / Sb-SnO2 composite anode material; Step c: The CF / Sb-SnO2 composite anode material and the waste string cathode material are used as the anode and cathode electrodes, respectively, and placed in a bipolar electrochemical synergistic degradation system under a DC electrode system to electrocatalytically degrade organic pollutant wastewater.

2. The low-energy electrochemical water treatment process based on waste string cathodes as described in claim 1, characterized in that, The specific steps for step a are as follows: a1: Place the waste guitar strings in a muffle furnace, heat them to 500 ℃ at a heating rate of 10 ℃ / min, and hold them at that temperature for 1 h. After natural cooling, the waste guitar string cathode material can be obtained.

3. The low-energy electrochemical water treatment process based on waste string cathodes as described in claim 1, characterized in that, Step b involves the following steps: b1: Add 45 mmol SnCl4·5H2O and 2 mmol SbCl3 to 100 mL of isopropanol, stir until the solution is clear; b2: Transfer the solution to a reaction vessel and react at 200 °C for 24 h. After the reaction is complete, cool to room temperature to obtain Sb-SnO2 suspension. b3: The Sb-SnO2 suspension was centrifuged and washed, and the washed product was dried in an oven at 80 ℃ for 2 h and then ground to obtain Sb-SnO2 nanopowder. b4: The Sb-SnO2 nanoparticles obtained in step b3 are dispersed in anhydrous ethanol, uniformly drop-coated onto carbon felt (CF), and dried at 80 °C to obtain the CF / Sb-SnO2 composite anode material, wherein the Sb-SnO2 loading is 0.7 ~ 0.9 mg / cm³. 2 .

4. The low-energy electrochemical water treatment process based on waste string cathodes as described in claim 1, characterized in that, In step c, the organic pollutant electrocatalytically degraded is Rhodamine B, the electrolyte used in the electrocatalytic degradation is 0.1 mol / L Na2SO4, and the anode-cathode distance is 4 cm.

5. The low-energy electrochemical water treatment process based on waste string cathodes as described in claim 1, characterized in that, The current during electrocatalytic degradation is 0.001 A.

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