Simple preparation and efficient recovery method based on polymethylene blue in composite printing and dyeing wastewater

Abstract

The invention discloses a simple preparation and high-efficiency recovery method of polymethylene blue based on composite printing and dyeing wastewater, which realizes high-efficiency recovery of polymethylene blue in composite printing and dyeing wastewater through a multi-stage grid, an adjusting tank, a reaction tank, a sedimentation tank and a dehydration room. Adjusting the composite printing and dyeing wastewater in the adjusting tank to be acidic, reacting the composite printing and dyeing wastewater with peroxydisulfate in a reaction tank, performing high-speed stirring, low-speed stirring and standing separation, decolorizing liquid-phase methylene blue, and depositing solid-phase polymethylene blue; under the action of the sedimentation tank, solid-phase polymethylene blue forms a filter cake, and the filter cake can be stored in the shade for later use after being subjected to vacuum drying. Compared with other dye recovery methods, the method has the advantages of simplicity in operation, low cost, safety, high efficiency, no secondary pollution, wide applicable concentration range and the like, realizes specific recovery of polymethylene blue in the composite printing and dyeing wastewater, and has wide engineering application prospects.

Description

Technical Field

[0001] This invention relates to the field of dyeing and printing wastewater treatment, specifically to a highly efficient method for recovering polymethylene blue from composite dyeing and printing wastewater. Background Technology

[0002] Dyes are among the most critical pollutants generated in various industries, including textiles, papermaking, printing, food, rubber, plastics, and cosmetics. Statistics show that as many as 10,000 types of dyes are used in various industrial processes. Currently, the annual production of dyes ranges from 10,000 to 770,000 tons, with Asia accounting for over 50% of global dye consumption. The resulting water pollution is particularly significant. Taking the textile dyeing and finishing industry as an example, approximately 30 tons of water are needed for each ton of textile dyeing, while 200 tons of water are needed for each ton of dye production. About 10% of this industrial wastewater is directly discharged. In recent years, water scarcity has become a limiting factor restricting the further development of my country's textile, papermaking, and printing industries. To achieve sustainable development and alleviate the growing shortage of healthy freshwater, the research and development of related industrial wastewater treatment and reuse technologies has received widespread attention. Among these, the degradation and reuse of dyes is one of the key technological challenges.

[0003] Methylene blue (C 16 H 18 Methylene blue (N3ClS) is a phenothiazine salt with a planar structure. It is highly stable in air, alkaline in aqueous solution, highly biotoxic, and difficult to degrade. As a typical water-soluble aromatic heterocyclic cationic dye, its dyeing technology on materials such as paper, wool, silk, and cotton is well-established. Meanwhile, methylene blue is also widely used in medical, aquaculture, and analytical identification fields. However, the environmental release of methylene blue seriously threatens the balance of ecosystems and poses health risks. Therefore, the research and development of efficient degradation and recycling processes for methylene blue is of great significance.

[0004] Currently, the main technologies for treating methylene blue include physical, biological, and chemical methods, all of which demonstrate significant degradation effects and whose underlying mechanisms have been thoroughly analyzed. However, research and development on methylene blue recycling and reuse processes are relatively scarce. Most of these methods require energy-intensive steps such as aeration or distillation purification, are complex to operate, and cannot recover methylene blue from composite dye systems independently. Therefore, this invention proposes a simple, low-cost, green, low-energy-consumption, and pollution-free method for the efficient recovery of polymethylene blue from composite dyeing and printing wastewater. Summary of the Invention

[0005] The purpose of this invention is to address the difficulties and high costs associated with treating dyeing and printing wastewater, as well as the immature and complex nature of dye recovery processes. This invention proposes a highly efficient method for recovering polymethylene blue from composite dye systems using persulfate, thereby achieving resource recycling. The persulfate preparation technology used in this method is mature, readily available, and poses no environmental risk during use. It offers numerous advantages, including safety, high efficiency, simple operation, low cost, and no secondary pollution.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A highly efficient method for recovering polymethylene blue from composite dyeing and printing wastewater, comprising the following specific steps:

[0008] Step 1: The composite dyeing and printing wastewater passes through coarse and fine screens to intercept suspended particulate matter of various sizes before entering the equalization tank;

[0009] Step 2: Adjust the pH value of the composite dyeing and printing wastewater entering the equalization tank to 3.0-5.0 and mix it evenly;

[0010] Step 3: Add persulfate to the acidic composite dyeing and printing wastewater after adjusting the pH value, so that the molar concentration ratio of persulfate to methylene blue in the wastewater is (4-100):1. Use a stirrer to stir at high speed for 2-5 minutes and then at low speed for 10 minutes before stopping.

[0011] Step 4: The reacted composite dyeing and printing wastewater is allowed to stand in a sedimentation tank for 30-120 minutes to complete the decolorization of liquid methylene blue and the deposition of solid polymethylene blue.

[0012] Step 5: The decolorized liquid phase enters the wastewater pipeline network, and the solid phase enters the dehydration room for dehydration;

[0013] Step 6: After dehydration, filter cake polymethylene blue is obtained, wherein:

[0014] The dyes in the composite dyeing and printing wastewater include, but are not limited to, methylene blue, phenolic red, acid yellow 17, and rhodamine B. The filter cake polymethylene blue obtained after filtration is a polymer of persulfate and methylene blue, and exhibits the properties of methylene blue under ultraviolet spectroscopy.

[0015] Preferably, the agents that can be used to adjust the pH value in step 2 include, but are not limited to, sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, etc.

[0016] Preferably, the high-speed stirring in step 3 can be 600 r / min, and the low-speed stirring can be 100 r / min.

[0017] Preferably, the persulfate includes potassium persulfate, sodium persulfate, and ammonium persulfate.

[0018] Preferably, the filter cake described in step 6, after vacuum drying or baking, can be stored in a cool place for a long time or dissolved and reused.

[0019] Preferably, the common coexisting ions in the composite dyeing and printing wastewater have little interference with the recovery efficiency, including but not limited to sodium ions, potassium ions, calcium ions, ammonium ions, nitrate ions, sulfate ions, carbonate ions, chloride ions, phosphate ions, etc.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) The method of the present invention is simple to operate and efficient to recover. It can be completed with the help of common stirring devices, sedimentation devices, etc., which is convenient and quick, and can realize the separate recovery of polymethylene blue.

[0022] (2) The persulfate used in this invention is safe and reliable, with no environmental risk. It can recover polymethylene blue while oxidizing and decolorizing, and there is no secondary pollution during the reaction process. It is highly environmentally friendly.

[0023] (3) The method of the present invention is applicable to the recovery of polymethylene blue in a wide concentration range (25μM~10mM), and has broad prospects for practical engineering applications. Attached Figure Description

[0024] Figure 1 This is a flowchart illustrating the operation of achieving the objective of this invention.

[0025] Figure 2 This is an experimental diagram of polymethylene blue solid-phase deposition provided by the present invention;

[0026] Figure 3 This is a photograph of the polymethylene blue filter cake recovery provided by the present invention;

[0027] Figure 4 This is a diagram illustrating the polymethylene blue recovery effect in Example 1 provided by the present invention;

[0028] Figure 5 This is a diagram illustrating the polymethylene blue recovery effect in Example 2 provided by the present invention;

[0029] Figure 6 This is a diagram illustrating the polymethylene blue recovery effect in Example 3 provided by the present invention;

[0030] Figure 7 This is a diagram showing the polymethylene blue recovery effect in Example 4 provided by the present invention. Detailed Implementation

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

[0032] Example 1

[0033] This embodiment focuses on methylene blue dye wastewater. The efficient polymethylene blue recovery method based on composite dyeing wastewater includes the following steps:

[0034] Step 1: Methylene blue dye wastewater passes through coarse and fine screens to intercept suspended particulate matter of various sizes before entering the equalization tank;

[0035] Step 2: Adjust the pH of the composite dyeing and printing wastewater entering the equalization tank to 3.0 and mix it evenly;

[0036] Step 3: Add persulfate to the acidic methylene blue dye wastewater after adjusting the pH value, so that the molar concentration ratio of persulfate to methylene blue in the wastewater is 8:1. Stir at 600 r / min for 2 min, then reduce the speed to 100 r / min and stir for 10 min before stopping.

[0037] Step 4: The reacted composite dyeing and printing wastewater was allowed to stand in a sedimentation tank for 50 minutes, and the methylene blue liquid phase decolorization rate was 77.57%.

[0038] Step 5: The decolorized methylene blue dye wastewater enters the wastewater pipeline network, and the solid phase enters the dewatering room for dewatering;

[0039] Step 6: After dehydration, filter cake polymethylene blue is obtained with a recovery rate of 96.05%.

[0040] Example 2

[0041] This embodiment focuses on methylene blue-acid yellow 17 dye wastewater. The efficient polymethylene blue recovery method based on composite dyeing and printing wastewater includes the following steps:

[0042] Step 1: Methylene blue-acid yellow 17 dye wastewater is passed through coarse and fine screens to intercept suspended particulate matter of various sizes before entering the equalization tank;

[0043] Step 2: Adjust the pH of the composite dyeing and printing wastewater entering the equalization tank to 3.0 and mix it evenly;

[0044] Step 3: Add persulfate to the acidic composite dyeing and printing wastewater after adjusting the pH value, so that the molar concentration ratio of persulfate to methylene blue in the wastewater is 15:1. Stir at 600 r / min for 2 min, then reduce the speed to 100 r / min and stir for 10 min before stopping.

[0045] Step 4: The reacted composite dyeing and printing wastewater was allowed to stand in a sedimentation tank for 50 minutes. The decolorization rate of methylene blue in liquid phase was 78.79%, and the decolorization rate of acid yellow 17 was 16.40%.

[0046] Step 5: The decolorized methylene blue-acid yellow 17 dye wastewater enters the wastewater pipeline network, and the solid phase enters the dewatering room for dewatering.

[0047] Step 6: After dehydration, filter cake polymethylene blue is obtained with a recovery rate of 86.27%.

[0048] Example 3

[0049] This embodiment focuses on methylene blue-phenol saffron dye wastewater. The efficient polymethylene blue recovery method based on composite dyeing wastewater includes the following steps:

[0050] Step 1: Methylene blue-phenol saffron dye wastewater is passed through coarse and fine screens to intercept suspended particulate matter of various sizes before entering the equalization tank;

[0051] Step 2: Adjust the pH of the composite dyeing and printing wastewater entering the equalization tank to 3.0 and mix it evenly;

[0052] Step 3: Add persulfate to the acidic composite dyeing and printing wastewater after adjusting the pH value, so that the molar concentration ratio of persulfate to methylene blue in the wastewater is 15:1. Stir at 600 r / min for 2 min, then reduce the speed to 100 r / min and stir for 10 min before stopping.

[0053] Step 4: The reacted composite dyeing and printing wastewater was allowed to stand in a sedimentation tank for 50 minutes. The decolorization rate of methylene blue in the liquid phase was 71.25%, and the decolorization rate of phenolic red was 32.70%.

[0054] Step 5: The decolorized methylene blue-phenol red dye wastewater enters the wastewater pipeline network, and the solid phase enters the dewatering room for dewatering;

[0055] Step 6: After dehydration, filter cake polymethylene blue is obtained with a recovery rate of 86.10%.

[0056] Example 4

[0057] This embodiment focuses on methylene blue-rhodamine B dye wastewater. The efficient polymethylene blue recovery method based on composite dyeing wastewater includes the following steps:

[0058] Step 1: Methylene blue-rhodamine B dye wastewater is passed through coarse and fine screens to intercept suspended particulate matter of various sizes before entering the equalization tank;

[0059] Step 2: Adjust the pH of the composite dyeing and printing wastewater entering the equalization tank to 3.0 and mix it evenly;

[0060] Step 3: Add persulfate to the acidic composite dyeing and printing wastewater after pH adjustment, so that the molar ratio of persulfate to methylene blue in the wastewater is 10:1. Stir at 600 r / min for 2 min, then reduce the speed to 100 r / min and stir for 10 min before stopping. Let stand for 50 min. The decolorization rate of methylene blue in liquid phase is 71.64%, and the decolorization rate of rhodamine B is 45.98%.

[0061] Step 4: The reacted composite dyeing and printing wastewater was allowed to stand in a sedimentation tank for 50 minutes. The decolorization rate of methylene blue in the liquid phase was 71.64%, and the decolorization rate of rhodamine B was 45.98%.

[0062] Step 5: The decolorized methylene blue-rhodamine B dye wastewater enters the wastewater pipeline network, and the solid phase enters the dewatering room for dewatering.

[0063] Step 6: After dehydration, filter cake polymethylene blue is obtained with a recovery rate of 88.68%.

[0064] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for efficient recovery of polymethylene blue from composite dyeing and printing wastewater, characterized in that, The method includes the following specific steps: Step 1: The composite dyeing and printing wastewater passes through coarse and fine screens to intercept suspended particulate matter of various sizes before entering the equalization tank; Step 2: Adjust the pH value of the composite dyeing and printing wastewater entering the equalization tank to 3.0~5.0, and mix it evenly; Step 3: Add persulfate to the acidic composite dyeing and printing wastewater after adjusting the pH value, so that the molar concentration ratio of persulfate to methylene blue in the wastewater is (4 ~ 100):

1. Use a stirrer to stir at high speed for 2 ~ 5 minutes and then at low speed for 10 minutes before stopping. Step 4: The reacted composite dyeing and printing wastewater is allowed to stand in a sedimentation tank for 30 to 120 minutes to complete the decolorization of liquid methylene blue and the deposition of solid polymethylene blue. Step 5: The decolorized liquid phase enters the wastewater pipeline network, and the solid phase enters the dehydration room for dehydration; Step 6: After dehydration, filter cake polymethylene blue is obtained, wherein: The dyes in the composite dyeing and printing wastewater include, but are not limited to, methylene blue, phenolic red, acid yellow 17, and rhodamine B. The filter cake polymethylene blue obtained after filtration is a polymer of persulfate and methylene blue, and exhibits the properties of methylene blue under ultraviolet spectroscopy.

2. The method according to claim 1, characterized in that, The agents that can be used to adjust the pH value include, but are not limited to, sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid.

3. The method according to claim 1, characterized in that, The high-speed stirring can be set at 600 r / min, and the low-speed stirring can be set at 100 r / min.

4. The method according to claim 1, characterized in that, The persulfate includes potassium persulfate, sodium persulfate, and ammonium persulfate.

5. The method according to claim 1, characterized in that, The filter cake, after vacuum drying or baking, can be stored in a cool place for a long time or dissolved and reused.

6. The method according to claim 1, characterized in that, The coexisting ions commonly found in the composite dyeing and printing wastewater have minimal impact on recovery efficiency, including but not limited to sodium ions, potassium ions, calcium ions, ammonium ions, nitrate ions, sulfate ions, carbonate ions, chloride ions, and phosphate ions.

Images