Crystal violet degradation method

Abstract

The invention discloses a crystal violet degradation method. The method comprises the following steps: 1) forming a Fenton system with H2O2 and visible light by using ferrocene Schiff base as a catalyst; (2) degrading the crystal violet through a Fenton system.The degradation method is high in treatment efficiency, low in energy consumption and not prone to secondary pollution, and environment-friendly organic pollutant treatment is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental protection, and in particular to a method for degrading crystal violet. Background Art

[0002] Crystal violet is a common organic dye widely used in the textile, printing and other industries. Its residue in wastewater not only affects the beauty of the water body, but also poses potential hazards to the ecosystem and human health. Traditional methods for treating organic dye wastewater include physical, chemical and biological methods, but these methods have problems such as low treatment efficiency, high cost, and easy to produce secondary pollution. Ultraviolet advanced oxidation technology has received widespread attention in the printing and dyeing wastewater industry due to its advantages such as high degradation rate, no secondary pollution, and simple reaction equipment. In particular, the photon energy emitted by the UV185 ultraviolet lamp reaches 6.70eV, and its oxidative degradation ability is significant. However, the use of ultraviolet light consumes a lot of energy and has certain hazards to the human body and the environment.

[0003] Ferrocene, due to its unique chemical structure and properties, is insoluble in water and has certain catalytic activity, making it a Fenton reagent for the degradation of organic pollutants. At the same time, bis(5-sulfosalicylaldehyde)-o-phenylenediamine Schiff base (SSPA iron) complex (FeSSPA) and some chain-like Schiff base ketone complexes have been reported to be highly efficient photo-Fenton reagents. In the existing research and application of Fenton reagents for the treatment of organic pollutants, although homogeneous catalysts have shown certain catalytic activity, they have obvious drawbacks. After the reaction is completed, it is difficult to effectively separate and recover it from the reaction system, which not only wastes catalyst resources and increases processing costs, but the residual catalyst may also cause secondary pollution to the environment. Summary of the Invention

[0004] In view of the above-mentioned defects or deficiencies in the prior art, it is desired to provide a crystal violet degradation method with high treatment efficiency, low energy consumption, and low risk of secondary pollution, thereby achieving environmentally friendly treatment of organic pollutants.

[0005] The present invention provides a method for degrading crystal violet, comprising the following steps: 1) Preparation of ferrocenium Schiff base; 2) Ferrocene Schiff base as catalyst, H2O2 and visible light form a Fenton system; 3) Degradation of crystal violet by Fenton system in neutral aqueous solution; The ferrocenium Schiff base is insoluble in water and serves as a heterogeneous catalyst, and its structural formula is: .

[0006] Furthermore, in step 1), the preparation of ferrocenium Schiff base comprises the following steps: 11) Add ferrocene carboxaldehyde containing ethanol dropwise to a p-phenylenediamine solution containing ethanol, and then add an appropriate amount of glacial acetic acid to obtain a mixed solution; 12) reflux stirring the mixed solution for 10-12 hours; 13) subjecting the mixed solution to a deep cooling treatment for 40-48 hours; 14) filtering the mixed solution and repeatedly washing the filtered solid with icy ethanol to obtain a preliminary product; 15) The preliminary product is dried and dissolved in lukewarm ethanol to remove unreacted soluble ferrocene formaldehyde, and then separated and purified to obtain a ferrocene Schiff base.

[0007] Furthermore, in step 3), the specific operation of degradation is: adding crystal violet to the aqueous solution, then adding ferrocenium Schiff base and H2O2, and reacting under visible light irradiation.

[0008] Furthermore, the visible light source is a xenon lamp, an LED visible light source or a halogen lamp.

[0009] Compared with the prior art, the present invention has the following beneficial effects: (1) The degradation method of the present invention utilizes a Fenton system composed of ferrocene Schiff base, H2O2 and visible light to achieve efficient degradation of crystal violet in a neutral aqueous solution without the need for complex pH adjustment of the reaction system, thus simplifying the operation process; (2) Ferrocene Schiff base is used as a heterogeneous catalyst, which is insoluble in water and easy to separate and reuse, reducing the processing cost and avoiding the secondary pollution to the environment caused by the loss of catalyst; (3) Visible light is used as the light source, which is more environmentally friendly than ultraviolet light, has a wide range of sources, and consumes less energy, thus meeting the requirements of sustainable development.

[0010] It should be understood that the contents described in the summary of the invention are not intended to limit the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments made with reference to the following drawings: Figure 1 is the synthetic reaction formula of ferrocenium Schiff base in Example 1; Figure 2 is the H NMR spectrum of the ferrocenium Schiff base in Example 1; Figure 3is the ultraviolet absorption spectrum of crystal violet under Fc-Schiff / H2O2 / hv conditions in Example 2; Figure 4 is the degradation rate curve of crystal violet under Fc-Schiff / H2O2 / hv conditions in Example 2; Figure 5 is the ultraviolet absorption spectrum of crystal violet in Comparative Example 1 under Fc-Schiff / hv conditions; Figure 6 is the degradation rate curve of crystal violet in Comparative Example 1 under Fc-Schiff / hv conditions; Figure 7 The UV absorption spectrum of crystal violet in Comparative Example 2 under the conditions of FC / H2O2 / hv and pH=7; Figure 8 This is the degradation rate curve of crystal violet in Comparative Example 2 under FC / H2O2 / hv, pH=7 conditions. DETAILED DESCRIPTION

[0012] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are intended only to illustrate the relevant invention and are not intended to limit the invention. It should also be noted that, for ease of description, only portions relevant to the invention are shown in the accompanying drawings.

[0013] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments. Example 1

[0014] Preparation of ferrocenium Schiff base (Fc-Schiff) Ferrocene Schiff base is synthesized using p-phenylenediamine and ferrocene formaldehyde as raw materials. The synthetic reaction formula is as follows: Figure 1 The specific synthesis steps are as follows: 11) Add ferrocene carboxaldehyde containing ethanol dropwise to a p-phenylenediamine solution containing ethanol, and then add an appropriate amount of glacial acetic acid to obtain a mixed solution; 12) Place the mixed solution in a stirring device and reflux and stir for 12 hours; 13) After stirring and refluxing, the mixed solution is subjected to a deep cooling treatment for 48 hours; 14) After cooling, the mixed solution is filtered, and the filtered solid is repeatedly washed with icy ethanol to obtain a preliminary product; 15) Finally, the preliminary product is dried and dissolved in lukewarm ethanol to remove any remaining unreacted soluble ferrocene carboxaldehyde. After separation and purification, the desired pure ferrocene Schiff base is obtained.

[0015] like Figure 2 As shown, the structure of the compound ferrocenium Schiff base was characterized by NMR analysis, and the NMR hydrogen spectrum data was: 1 HNMR (400 MHz, CDC l3 ) δ 8.38 (s, 2H), 7.18 (s, 4H), 4.81 (s, 4H), 4.50 (s, 4H), 4.27 (s, 10H). Example 2

[0016] Degradation of crystal violet (CV) catalyzed by ferrocene-Schiff base (Fc-Schiff) and H2O2 Prepare 2×10 -4 Prepare 50 mL of a 7.0 mol / L, pH 7 aqueous solution of crystal violet (CV). Use deionized water for preparation and dilution, using deionized water as a reference cell. Accurately weigh 0.0040 g of crystal violet (CV) and add it to the deionized water. Stir thoroughly until completely dissolved to obtain the desired crystal violet solution.

[0017] Add the prepared 2×10 -4 0.05 g of the ferrocenium Schiff base prepared in Example 1 was added to a 4 mol / L, pH=7 aqueous solution of crystal violet. After the addition, the stirring device was started and the stirring was continued for about 15 minutes to allow the ferrocenium Schiff base to reach adsorption saturation in the crystal violet solution.

[0018] After adsorption saturation, stop stirring and allow the solution to settle. Then, remove 0.5 mL of the solution for later use. Add 3 mL of 30% H₂O₂ to the solution. After addition, start stirring and stir thoroughly to mix the H₂O₂ with the solution. Once mixed, turn off stirring and allow the solution to settle. Remove 0.5 mL of the solution.

[0019] At the beginning of the photodegradation process (t=0s), the above solution was taken, diluted and its absorbance was measured, which was recorded as A0. The solution was then irradiated with visible light (hv) for 60s, 120s, 240s, 480s, 720s and 960s respectively. After each irradiation, 0.5mL of the solution was taken and diluted according to the same dilution factor as when measuring A0, and its absorbance was measured and recorded as A0. t .

[0020] The degradation effects of ferrocenium Schiff base (Fc-Schiff) and H2O2 on crystal violet (CV) under visible light (HV) conditions were analyzed by comparing the absorbance changes of the solutions at different irradiation times before and after adding H2O2.

[0021] Depend on Figure 3It can be seen that the characteristic absorption peak of the CV dye solution under the Fc-Schiff / H2O2 / hv conditions appears at 580nm. The absorption peak of the CV dye solution gradually decreases with the increase of reaction time. At 3 minutes, the absorption peak shows a significant decrease, indicating that the dye has fully reacted at this time. At 25 minutes, the absorption peak of the CV dye solution at 580nm is close to stable, and its absorbance is also very low. Figure 3 It can be seen that the Fenton system composed of Fc-Schiff / H2O2 / hv under these conditions has a better degradation effect on the CV dye solution and the overall degradation rate is faster. Comparative Example 1

[0022] The steps of Example 2 were followed, except that H2O2 was not added and other conditions remained unchanged. At the beginning of the photodegradation process (t=0), 0.5 mL of the solution was taken, diluted, and its absorbance was measured, which was recorded as A0. The solution was then irradiated with visible light (hv) for 60 s, 120 s, 240 s, 480 s, 720 s, and 960 s, respectively. After each irradiation, 0.5 mL of the solution was taken and diluted according to the same dilution factor as when measuring A0, and its absorbance was measured, which was recorded as A0. t ,like Figure 5 The experimental results show that the Fenton system composed of Fc-Schiff / hv under these conditions also has a certain degradation effect on CV dye. Comparative Example 2

[0023] The steps of Example 2 were followed, except that 0.05 g of ferrocene Schiff base was replaced with 0.1 g of ferrocene (FC), and other conditions remained unchanged. At the beginning of the photodegradation process (t = 0), 0.5 mL was taken from the above solution, diluted and its absorbance was measured, which was recorded as A0. The solution was then irradiated with visible light (hv) for 60 s, 120 s, 240 s, 480 s, 720 s, and 960 s, respectively. After each irradiation, 0.5 mL of the solution was taken and diluted according to the same dilution factor as when measuring A0, and its absorbance was measured, which was recorded as A0. t ,like Figure 7 As shown. Figure 3 In comparison, it can be seen that the degradation rate of CV dye by the Fenton system composed of FC / H2O2 / hv at pH=7 is slower than that of the Fenton system under Fc-Schiff / H2O2 / hv conditions, and the degradation effect is poor.

[0024] In summary, the degradation method of the present application utilizes a Fenton system composed of ferrocenium Schiff base, H2O2 and visible light, which can achieve efficient degradation of crystal violet in a neutral aqueous solution without the need for complex pH adjustment of the reaction system, thereby simplifying the operation process; ferrocenium Schiff base is used as a heterogeneous catalyst, which is insoluble in water and easy to separate and reuse, reducing processing costs and avoiding secondary pollution to the environment caused by catalyst loss; visible light is used as a light source, which is more environmentally friendly than ultraviolet light, has a wide range of sources, low energy consumption, and meets the requirements of sustainable development.

[0025] Throughout this specification, terms such as "one embodiment" or "some embodiments" mean that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0026] The above are merely preferred embodiments of the present application and are not intended to limit the present application. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for degrading crystal violet, characterized in that: The steps include: 1) Preparation of ferrocenium Schiff base; 2) Ferrocene Schiff base as catalyst, H2O2 and visible light form a Fenton system; 3) Degradation of crystal violet by Fenton system in neutral aqueous solution; The ferrocenium Schiff base is insoluble in water and serves as a heterogeneous catalyst, and its structural formula is: 。 2. The crystal violet degradation method according to claim 1, wherein In the step 1), the preparation of the ferrocenium Schiff base comprises the following steps: 11) Add ferrocene carboxaldehyde containing ethanol dropwise to a p-phenylenediamine solution containing ethanol, and then add an appropriate amount of glacial acetic acid to obtain a mixed solution; 12) reflux stirring the mixed solution for 10-12 hours; 13) subjecting the mixed solution to a deep cooling treatment for 40-48 hours; 14) filtering the mixed solution and repeatedly washing the filtered solid with icy ethanol to obtain a preliminary product; 15) The preliminary product is dried and dissolved in lukewarm ethanol to remove unreacted soluble ferrocene formaldehyde, and then separated and purified to obtain a ferrocene Schiff base.

3. The crystal violet degradation method according to claim 1, wherein In the step 3), the specific operation of degradation is: adding crystal violet to the aqueous solution, then adding ferrocenium Schiff base and H2O2, and reacting under visible light irradiation.

4. The crystal violet degradation method according to claim 1, wherein The visible light source is a xenon lamp, an LED visible light source or a halogen lamp.

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