CN116446200A - Direct electrochemical reduction-based cotton fabric indigo dyeing method - Google Patents

Abstract

The invention provides a cotton fabric indigo dyeing method based on direct electrochemical reduction, which comprises the following steps: s1, directly performing electrochemical reduction on indigo dye by adopting a flow plate-frame electrolysis device; s2, delivering the reduced dye to a dyeing device to dye the cotton fabric; s3, conveying the dyed dye liquor to a flowing plate frame electrolysis device, and repeating the steps S1-S2 for a plurality of times. The invention makes the indigo directly contact with the electrode to obtain electrons through the flowing plate-frame electrolysis device, thereby reducing the indigo, being a direct electrochemical reduction process, not introducing any metal ions, having no pollution to reaction products, being clean and environment-friendly, having good application prospect, being superior to the traditional process in energy consumption, cost and the like, and having better dyeing effect than the traditional dyeing, being capable of recycling dye liquor for multiple times and having little fluctuation of K/S apparent color depth.

Description

A method for indigo dyeing of cotton fabrics based on direct electrochemical reduction

technical field

The invention relates to a method for dyeing cotton fabrics, in particular to an indigo dyeing method for cotton fabrics based on direct electrochemical reduction.

Background technique

Indigo is commonly used in the denim dyeing process, but indigo is insoluble in water and has no affinity for cotton fabrics. It needs to be reduced to a leuco body by a reducing agent under alkaline conditions to complete the dyeing. In the traditional dyeing process, sodium dithionite (commonly known as sodium hydrosulfite) is used as a reducing agent to reduce indigo to leucosome for dyeing. However, hydrosulfite is non-renewable and produces sulfur-containing compounds after decomposition, which pollutes the environment.

In recent years, the heat of indirect electrochemical reduction of indigo has been high. The system uses iron ion complex as a bridge to obtain electrons from the cathode, and then transfer the electrons to the dye to reduce it. But the disadvantage is that this process introduces metal ions such as iron ions, which not only has a certain impact on the fabric, but also causes a certain degree of pollution to the environment. Therefore, it is necessary to design a method for direct electrochemical reduction of indigo without introducing any metal ions to overcome the above-mentioned problems.

Contents of the invention

The purpose of the present invention is to provide a method for indigo dyeing of cotton fabrics based on direct electrochemical reduction for the problems of high pollution, high energy consumption and high emission of traditional processes, and the introduction of a large number of metal ions in existing indirect electrochemical reduction methods.

The present invention is achieved like this:

The invention provides a kind of cotton fabric indigo dyeing method based on direct electrochemical reduction, comprising steps:

S1. Direct electrochemical reduction of indigo dye by using a flow plate and frame electrolysis device;

S2, sending the reduced dyestuff to the dyeing device to dye the cotton fabric;

S3. Send the dyed solution to the flow plate frame electrolysis device, and repeat steps S1-S2 for several times.

The invention uses a flow plate and frame electrolysis device to directly contact the indigo with the electrode to obtain electrons, thereby reducing the indigo. It is a direct electrochemical reduction process without introducing any metal ions. The reaction product is pollution-free, clean and environmentally friendly, and has good applications. Foreground, it is better than the traditional process in terms of energy consumption and cost, and the dyeing effect is better than the traditional dyeing, and the dyeing liquor can be recycled for many times, and the K/S apparent color depth has little fluctuation.

Further, the flow plate and frame electrolysis device includes a plate and frame electrolyzer, a cathode liquid storage tank and an anode liquid storage tank, the cathode liquid storage tank and the anode liquid storage tank are all provided with a feed inlet, a discharge port and an air outlet, and the cathode The liquid storage tank and the anode liquid storage tank respectively send the catholyte and the anolyte to the cathode and anode of the plate and frame electrolytic cell through the discharge port, and the cathode liquid storage tank is also equipped with a discharge hole to send the reduced dye to the dyeing device.

Further, the air outlets of the cathode liquid storage tank and the anode liquid storage tank are connected with cold hydrazine to prevent excessive pressure in the tanks.

Further, a water stop valve is connected to the discharge hole of the cathode liquid storage tank, and after the indigo is completely reduced, the water stop valve is opened to send the reduced dye to the dyeing device.

Further, the catholyte is indigo and an alkaline solution, the ratio of the indigo to the alkaline solution is 2:1, and the anolyte is an alkaline solution.

Further, in step S1, the indigo dye is completely reduced at a voltage of 10-15V, a temperature of 40-60°C, a flow rate of 10-20ml/min, and ultrasonication for 1-2 hours.

Further, the dyeing device includes a osmosis tank, a dye vat and a washing tank arranged side by side in sequence, and rollers connected to each other are arranged on the osmosis tank, the dyeing vat and the washing tank.

Further, in step S2, the cotton fabric is infiltrated through the permeation tank, dyed in the dyeing vat, washed to remove the floating color in the water washing tank, and finally oxidized and air-dried to complete the dyeing of the cotton fabric.

Further, the cotton fabric is yarn or twill cotton.

The present invention has the following beneficial effects:

1. The reaction product in the present invention is non-polluting, clean and environmentally friendly, and is far superior to the existing hydrosulfite system and indirect electrochemical reduction system from a technological point of view. The apparent color depth of S is better, and it is also superior to traditional crafts in terms of energy consumption and cost.

2. The dye solution produced in the present invention can be recycled, and the K/S apparent color depth does not fluctuate much after cyclic dyeing.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is the structural representation of the device used in the production in the embodiment of the present invention;

Fig. 2 is the structural representation of the functional plate in the plate and frame electrolyzer in the embodiment of the present invention;

Fig. 3 is the K/S curve comparison chart of multiple dyeing of yarn and traditional yarn multiple dyeing in the embodiment of the present invention;

Fig. 4 is a K/S curve comparison chart of multiple dyeing of three-up and one-down cotton twill and multiple dyeing of traditional three-up and one-down twill in the embodiment of the present invention;

Fig. 5 is the K/S curve diagram of dyeing of yarn in multiple electrolysis once in Example 5 of the present invention;

Fig. 6 is a K/S curve diagram of three-up-down-down twill cotton cloth electrolyzed for multiple times and dyed once in Example 6 of the present invention.

In the figure: 1. Plate and frame electrolyzer; 2. Cathode liquid storage tank; 3. Anode liquid storage tank; 4. Peristaltic pump; 5. Cold hydrazine; 6. Anode; 7. Cathode; 8. Water stop valve; 9. Permeation tank; 10. Dyeing vat; 11. Washing tank; 12-Function board; 13-Pipeline; 14-Groove.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Referring to FIG. 1 , the device used in the embodiment of the present invention includes a flow plate and frame electrolysis device and a dyeing device. The flow plate and frame electrolysis device includes a plate and frame electrolysis cell 1 , a cathode liquid storage tank 2 and an anode liquid storage tank 3 .

Both the cathode liquid storage tank 2 and the anode liquid storage tank 3 are provided with a feed inlet, a discharge port and an air outlet. Tank 3 sends catholyte and anolyte to cathode 7 and anode 6 of plate and frame electrolytic cell 1 respectively through the discharge port, and cathode 7 and anode 6 are connected to DC power supply on both sides of plate and frame electrolytic cell 1, and catholyte is indigo and alkali The anolyte is an alkaline solution, and the catholyte and anolyte are returned to the cathode liquid storage tank 2 and the anode liquid storage tank 3 from the feed port after electrolysis, and the indigo directly contacts with the electrode to obtain electrons, and the reduction is completed, and the cathode storage tank The liquid tank 2 is also provided with a discharge hole, which is connected with a water stop valve 8 to prevent backflow, and the reduced indigo is sent to the dyeing device from the discharge hole.

The dyeing device includes an infiltration pool 9, a dye vat 10, and a washing pool 11 arranged side by side in sequence. Interconnected rollers are arranged on the osmosis pool 9, the dyeing vat 10, and the water washing pool 11. 1. Washing tank 11 washes away floating colors, and finally oxidizes and air-dries to complete the dyeing of cotton fabrics.

The dyed solution after dyeing can be recycled. By turning the 4 directions of the peristaltic pump, the dyed solution is pumped to the cathode tank for repeated electrolysis.

As shown in Figure 2, the core component of the plate and frame electrolyzer 1 is a functional board 12 (divided into a cathode functional board and an anode functional board). Groove 14, groove 14 and other components cooperate to form a cathode chamber or an anode chamber. According to the specific reaction conditions, the cathode chamber can be filled with RVC porous glassy carbon, etc. to form a three-dimensional electrode system, further increase the contact area between the dye and the electrode, and enhance the reduction. Effect.

Therefore, the indigo dyeing method of cotton fabric based on direct electrochemical reduction of the present invention comprises steps:

S1. Direct electrochemical reduction of indigo dye by using a flow plate and frame electrolysis device;

S2, sending the reduced dyestuff to the dyeing device to dye the cotton fabric;

S3. Send the dyed solution to the flow plate frame electrolysis device, and repeat steps S1-S2 for several times.

Example 1

Prepare catholyte with indigo concentration of 80-120g/L (indigo:sodium hydroxide=2:1), and prepare anolyte with sodium hydroxide concentration of 20-40g/L.

In the flow plate and frame electrolysis device, under the optimal process conditions: voltage 10-15V, temperature 40-60°C, liquid inlet flow rate 10-20ml/min, ultrasonic 1-2h, the indigo can be completely reduced. Then take 30cm yarn, carry out dyeing, oxidation, air-dry, measure its K/S value.

Comparative example 1

Prepare a dye solution with an indigo concentration of 80--120g/L (indigo: sodium hydroxide = 2:1), and add the same concentration of sodium hydrochloride for reduction. After complete reduction, then take 30cm of yarn, dye, oxidize, air-dry, and measure its K/S value.

Example 2

Prepare catholyte with indigo concentration of 80-120g/L (indigo:sodium hydroxide=2:1), and prepare anolyte with sodium hydroxide concentration of 20-40g/L.

In the flow plate and frame electrolysis device, under the optimal process conditions: voltage 10-15V, temperature 40-60°C, liquid inlet flow rate 10-20ml/min, ultrasonic 1-2h, the indigo can be completely reduced. Then take 30cm yarn, carry out dyeing, oxidation, air-drying, repeat many times and measure its K/S value.

Comparative example 2

Prepare a dye solution with an indigo concentration of 80--120g/L (indigo: sodium hydroxide = 2:1), and add the same concentration of sodium hydrochloride for reduction. After complete reduction, then take 30cm of yarn, dye, oxidize, and air-dry, repeat it several times, and measure its K/S value.

Example 3

Prepare catholyte with indigo concentration of 80-120g/L (indigo:sodium hydroxide=2:1), and prepare anolyte with sodium hydroxide concentration of 20-40g/L.

In the flow plate and frame electrolysis device, under the optimal process conditions: voltage 10-15V, temperature 40-60°C, liquid inlet flow rate 10-20ml/min, ultrasonic 1-2h, the indigo can be completely reduced. Then take a 5cm*5cm three-up and one-down twill cotton cloth, and measure its K/S value after being dyed, oxidized, and air-dried.

Comparative example 3

Prepare a dye solution with an indigo concentration of 80--120g/L (indigo: sodium hydroxide = 2:1), and add the same concentration of sodium hydrochloride for reduction. After complete reduction, take a 5cm*5cm three-up and one-down twill cotton cloth, and measure its K/S value after dyeing, oxidation, and air-drying.

Example 4

Prepare catholyte with indigo concentration of 80-120g/L (indigo:sodium hydroxide=2:1), and prepare anolyte with sodium hydroxide concentration of 20-40g/L.

In the flow plate and frame electrolysis device, under the optimal process conditions: voltage 10-15V, temperature 40-60°C, liquid inlet flow rate 10-20ml/min, ultrasonic 1-2h, the indigo can be completely reduced. Then take a 5cm*5cm three-up and one-down twill cotton cloth, dye, oxidize, air-dry, and repeat it several times to measure its K/S value.

Comparative example 4

Prepare a dye solution with an indigo concentration of 80--120g/L (indigo: sodium hydroxide = 2:1), and add the same concentration of sodium hydrochloride for reduction. After complete reduction, take a 5cm*5cm three-up and one-down twill cotton cloth, dye, oxidize, air-dry, and repeat it several times to measure its K/S value.

Example 5

Prepare catholyte with indigo concentration of 80-120g/L (indigo:sodium hydroxide=2:1), and prepare anolyte with sodium hydroxide concentration of 20-40g/L.

In the flow plate and frame electrolysis device, under the optimal process conditions: voltage 10-15V, temperature 40-60°C, liquid inlet flow rate 10-20ml/min, ultrasonic 1-2h, the indigo can be completely reduced. Then take the pure cotton yarn of 30cm yarn, through dyeing, oxidation, air-dry, measure its K/S value.

Repeat the electrolysis of the dye solution every other day, then take 30cm pure cotton yarn, dye, oxidize and air-dry, and measure its K/S value. The results are shown in Figure 4.

Example 6

Prepare catholyte with indigo concentration of 80-120g/L (indigo:sodium hydroxide=2:1), and prepare anolyte with sodium hydroxide concentration of 20-40g/L.

In the flow plate and frame electrolysis device, under the optimal process conditions: voltage 10-15V, temperature 40-60°C, liquid inlet flow rate 10-20ml/min, ultrasonic 1-2h, the indigo can be completely reduced. Then take a 5cm*5cm three-up and one-down twill cotton cloth, dye, oxidize, and air-dry to measure its K/S value.

Repeat the electrolysis of the dye solution every other day, and then take a 5cm*5cm three-up and one-down twill cotton fabric, which is dyed, oxidized, and air-dried, and its K/S value is measured. The results are shown in Figure 5.

According to Examples 1 to 4 and Comparative Examples 1 to 4, the yarn and the three upper and one lower twill cottons are dyed one or more times respectively, and the data obtained are shown in Table 1, and the K/S curve comparison diagrams are shown in Figure 2 and Figure 3 Shown:

Table 1 K/S values of traditional and direct electrochemical methods dyeing fabrics once or more times

It can be seen that through the flow plate and frame electrolysis device, the indigo is directly contacted with the electrode to obtain electrons, and the effect of dyeing yarn and twill cloth after direct electrochemical reduction is better than that of traditional dyeing.

The invention does not introduce metal ions, the reaction product is pollution-free, clean and environmentally friendly, and is far superior to the existing hydrosulfite system and indirect electrochemical reduction system from the perspective of technology. The apparent color depth of K/S is better, and it is also superior to traditional crafts in terms of energy consumption and cost.

Simultaneously, through embodiment 5 and embodiment 6, as can be seen from Fig. 4, Fig. 5, the dye liquor produced in the present invention can be recycled, and after cycle dyeing, K/S apparent color depth fluctuation is little.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims (9)

1. a cotton fabric indigo dyeing method based on direct electrochemical reduction, is characterized in that, comprises steps: S1. Direct electrochemical reduction of indigo dye by using a flow plate and frame electrolysis device; S2, sending the reduced dyestuff to the dyeing device to dye the cotton fabric; S3. Send the dyed solution to the flow plate frame electrolysis device, and repeat steps S1-S2 for several times. 2. the cotton fabric indigo dyeing method based on direct electrochemical reduction as claimed in claim 1, is characterized in that: said flow plate and frame electrolysis device comprises plate and frame electrolyzer, cathode liquid storage tank and anode liquid storage tank, cathode storage tank Both the liquid tank and the anode liquid storage tank are equipped with a feed inlet, a feed outlet and an air outlet. The cathode liquid storage tank and the anode liquid storage tank respectively send the catholyte and anolyte to the cathode and anode of the plate and frame electrolytic cell through the outlet. The anode and cathode liquid storage tanks are also equipped with discharge holes to send the reduced dyes to the dyeing device. 3. the cotton fabric indigo dyeing method based on direct electrochemical reduction as claimed in claim 2, is characterized in that: the air outlet of cathode liquid storage tank and anode liquid storage tank are all connected with cold hydrazine. 4. The indigo dyeing method of cotton fabric based on direct electrochemical reduction as claimed in claim 2, characterized in that: the discharge hole of the cathode liquid storage tank is connected with a water stop valve. 5. the cotton fabric indigo dyeing method based on direct electrochemical reduction as claimed in claim 2, is characterized in that: described catholyte is indigo and alkaline solution, and the ratio of described indigo and described alkaline solution is 2: 1. The anolyte is an alkaline solution. 6. The indigo dyeing method of cotton fabric based on direct electrochemical reduction as claimed in claim 1, characterized in that: in step S1, at a voltage of 10--15V, a temperature of 40--60°C, and a flow rate of 10--20ml /min, the indigo dye is completely reduced under ultrasonication for 1--2h. 7. the indigo dyeing method of cotton fabric based on direct electrochemical reduction as claimed in claim 1, is characterized in that: described dyeing device comprises the osmosis pool, dyeing vat and washing pool that arrange side by side successively, arranges on osmosis pool, dyeing vat and washing pool There are interconnected rollers. 8. The indigo dyeing method for cotton fabrics based on direct electrochemical reduction as claimed in claim 1, characterized in that: in step S2, the cotton fabrics are respectively infiltrated through the infiltration tank, dyed in the dye vat, washed off the floating color in the washing tank, and finally oxidized Air drying completes the dyeing of cotton fabrics. 9. the indigo dyeing method of cotton fabric based on direct electrochemical reduction as claimed in claim 1, characterized in that: said cotton fabric is yarn or twill cotton.