CN111020661B

CN111020661B - Electrolytic system for indirect electrochemical dyeing and electrochemical dyeing process

Info

Publication number: CN111020661B
Application number: CN201911327364.XA
Authority: CN
Inventors: 姚继明; 张维; 李晓燕; 汪康康; 魏赛男
Original assignee: Hebei University of Science and Technology
Current assignee: Hebei University of Science and Technology
Priority date: 2019-12-20
Filing date: 2019-12-20
Publication date: 2021-06-08
Anticipated expiration: 2039-12-20
Also published as: CN111020661A

Abstract

The invention relates to the technical field of textile chemistry, and particularly discloses an electrolytic system for indirect electrochemical dyeing and an electrochemical dyeing process. The solute of the catholyte of the electrolysis system comprises soluble ferric salt, polyhydroxy ligand, soluble aluminum salt and sodium hydroxide. According to the invention, aluminum salt is added into the catholyte, and aluminum ions and iron ions form an iron-hydroxyl-aluminum binuclear complex system through a polyhydroxy ligand, and the electrostatic attraction between the complex system and the cathode is improved due to positive charges carried by the aluminum ions, so that higher conduction current can be obtained, and further the mass transfer rate of the system is accelerated through the synergistic effect between iron salt and aluminum salt, the reduction potential of the dye solution and the conduction current of the electrolyte are obviously improved, the dye reduction time is shortened, and the problems of low reduction potential, long reduction time and poor dyeing effect under the previous complex system are solved.

Description

Electrolytic system for indirect electrochemical dyeing and electrochemical dyeing process

Technical Field

The invention relates to the technical field of textile chemistry, in particular to an electrolytic system for indirect electrochemical dyeing and an electrochemical dyeing process.

Background

The vat dye is insoluble in water and has no affinity to cellulose fiber, and during dyeing, carbonyl in dye molecules needs to be reduced under the conditions of strong reducing agent and alkali to form soluble leuco bodies, so that the fiber can be dyed. The reducing agent used for reducing the dye is mainly sodium hydrosulfite (sodium hydrosulfite) traditionally, the method has large consumption of the reducing agent, complex dyeing process and large amount of sulfur-containing wastewater generated in production, and the wastewater has dark color, high alkalinity and more difficultly degraded substances and causes inconvenience for subsequent sewage treatment.

The electrochemical dyeing method is a dyeing method which replaces the traditional reducing agent with electrons to reduce the dye, thereby generating no harmful by-products and having no wastewater discharge. The indirect electrochemical dyeing takes trivalent iron ions with electrochemical activity as a medium, takes triethanolamine for stabilizing the iron ions as a ligand, and Fe (III) -TEA obtains electrons on the surface of an electrode in a cathode area and is reduced into Fe (II) -TEA; then, Fe (II) -TEA transfers electrons to the vat dye to reduce it to leuco form, while Fe (II) -TEA is oxidized to Fe (III) -TEA itself; finally, the Fe (III) -TEA generated obtains electrons on the cathode, and the dyeing method has the problems of long reduction time, low conduction current, poor dyeing effect and the like although the reduction efficiency is greatly improved compared with that of the direct electrochemical method. The reason for these problems is that the electrode material is an important factor in addition to the catholyte system, the composition of the anolyte, and the like.

Disclosure of Invention

Aiming at the problems of longer time required for dye reduction, low conduction current and poor dyeing effect in the existing indirect electrochemical dyeing system, the invention provides an electrolytic system for indirect electrochemical dyeing.

And, an electrochemical dyeing process.

In order to achieve the purpose of the invention, the embodiment of the invention adopts the following technical scheme:

an electrolytic system for indirect electrochemical dyeing having catholyte solutes comprising a soluble iron salt, a polyhydroxy ligand, a soluble aluminum salt and sodium hydroxide.

Compared with the prior art, the electrolytic system for indirect electrochemical dyeing provided by the invention has the following advantages:

according to the invention, aluminum salt is added into the catholyte, and aluminum ions and iron ions form an iron-hydroxyl-aluminum binuclear complex system through a polyhydroxy ligand, and the electrostatic attraction between the complex system and the cathode is improved due to positive charges carried by the aluminum ions, so that higher conduction current can be obtained, and further the mass transfer rate of the system is accelerated through the synergistic effect between iron salt and aluminum salt, the reduction potential of the dye solution and the conduction current of the electrolyte are obviously improved, the dye reduction time is shortened, and the problems of low reduction potential, long reduction time and poor dyeing effect under the previous complex system are solved.

Preferably, the concentration of the soluble iron salt is 0.01-0.1mol/L, the concentration of the polyhydroxy ligand is 0.02-0.5mol/L, the concentration of the soluble aluminum salt is 0.0025-0.02mol/L, and the concentration of the sodium hydroxide is 0.03-0.5 mol/L.

Preferably, the molar ratio of the polyhydroxy ligand to the soluble iron salt is 2-5: 1.

The preferable concentration and concentration ratio of iron ions, aluminum ions and polyhydroxy ligand can ensure that the K/S value of dyeing is higher; when the concentration of the three substances is too low, the concentration of the formed iron-hydroxyl-aluminum binuclear complex system is too low, so that the iron ion quantity with redox capability in the electrolytic process is less, the reduced dye quantity is less, and the dyed K/S value is lower; if the concentration of the three components is too high, the solubility of the dye is reduced, so that the vat dye is difficult to be oxidized and reduced, and the K/S value of dyeing is reduced.

Preferably, the soluble aluminium salt is aluminium sulphate, aluminium chloride or aluminium nitrate.

Preferably, the soluble ferric salt is ferric sulfate, ferric nitrate, ferric chloride, ferrous sulfate, ferrous nitrate or ferrous chloride.

Preferably, the polyhydroxy ligand is at least one of sodium gluconate, sodium oxalate, sodium citrate, lactic acid, triethanolamine or tartaric acid.

Preferably, the cathode electrode is an aluminum electrode.

The method takes an aluminum electrode as a cathode electrode, and aluminum and sodium hydroxide react in the cathode electrolyte to obtain aluminum ions which can form an iron-hydroxyl-aluminum binuclear complex system with iron ions in the electrolyte, so that the reduction potential of the dye solution and the conduction current of the electrolyte are improved; because the aluminum loses the electrons of the outermost layer, the surface of the aluminum can form active sites which can adsorb hydrogen formed in a cathode electrolyte system, and meanwhile, the active sites can activate highly conjugated carbonyl in vat dye molecules, so that the reduction of the carbonyl by the hydrogen is promoted, the reduction rate of the system dye is improved, and the K/S value of dyeing is improved.

Preferably, the anode electrode is graphite, nickel, copper, magnesium, zinc, aluminum or iron electrode.

Preferably, the electrolyte of the anolyte is sulfuric acid, sodium hydroxide, sodium sulfate or sodium metabisulfite, and the concentration of the electrolyte is 1-2 mol/L.

The invention also provides an electrochemical dyeing process, which is used for dyeing the fabric by carrying out electrochemical reduction on the vat dye under the conditions of constant voltage and protective gas.

The electrochemical dyeing process provided by the invention can realize no wastewater discharge, can obviously improve the conduction current efficiency and shorten the dye reduction time compared with the prior art, and has excellent dyeing effect.

Preferably, the voltage is 1-15V.

Preferably, the time of the electrochemical reduction is 20-180 min.

The optimal electrolytic voltage and electrochemical reduction time can enable iron ions, aluminum ions and hydroxyl groups to form a stable binuclear complex system, reduce the reduction time of the dye and improve the K/S value.

Preferably, the protective gas is nitrogen or argon.

Preferably, the concentration of the vat dye is 0.005-0.2 mol/L.

Preferably, the dyeing bath ratio of the dyeing is 1: 5-50.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Example 1

The embodiment provides an electrochemical dyeing process, which comprises the following steps:

step a, sequentially adding 0.02mol/L ferrous sulfate, 0.04mol/L sodium gluconate, 0.005mol/L aluminum sulfate and 0.0095mol/L indigo into 0.2mol/L sodium hydroxide aqueous solution, and fully stirring to obtain a cathode electrolyte; the anolyte is 2mol/L sodium hydroxide aqueous solution; taking an aluminum electrode as a cathode and a graphite electrode as an anode;

b, adding the cathode electrolyte and the anode electrolyte into an electrolytic cell respectively, carrying out electrochemical reduction on the indigo for 60min under the conditions of 15V of electrolytic voltage and nitrogen protection, putting a reduction potentiometer into the dye solution at 25 ℃ after the reduction is finished, and reading the reduction potential value after the value is stable;

and c, putting the reduced dye liquor obtained in the step b into pure white half-bleaching coarse grain inclined cloth which is wetted by distilled water in advance for dyeing for 1min, wherein the dyeing bath ratio is 1:20, ventilating and oxidizing after dyeing is finished, then finishing dyeing post-treatment by soap boiling and water washing, and testing the color depth K/S value of the finally obtained fabric.

Example 2

step a, sequentially adding 0.01mol/L ferric sulfate, 0.04mol/L sodium oxalate, 0.0025mol/L aluminum sulfate and 0.005mol/L indigo into 0.15mol/L sodium hydroxide aqueous solution, and fully stirring to obtain a cathode electrolyte; the anolyte is 1mol/L sulfuric acid aqueous solution; taking an aluminum electrode as a cathode and a copper electrode as an anode;

b, adding the cathode electrolyte and the anode electrolyte into an electrolytic cell respectively, carrying out electrochemical reduction on the indigo for 100min under the conditions of 10V of electrolytic voltage and nitrogen protection, putting a reduction potentiometer into a dye solution at 25 ℃ after the reduction is finished, and reading a reduction potential value after the value is stable;

and c, putting the reduced dye liquor obtained in the step b into pure white half-bleaching coarse grain inclined cloth which is wetted by distilled water in advance for dyeing for 1min, wherein the dyeing bath ratio is 1:40, ventilating and oxidizing after dyeing is finished, then finishing dyeing post-treatment by soap boiling and water washing, and testing the color depth K/S value of the finally obtained fabric.

Example 3

step a, sequentially adding 0.01mol/L ferrous chloride, 0.03mol/L sodium citrate, 0.0075mol/L aluminum chloride and 0.0095mol/L indigo into 0.3mol/L sodium hydroxide aqueous solution, and fully stirring to obtain a cathode electrolyte; the anolyte is 2mol/L sodium metabisulfite aqueous solution; using an aluminum electrode as a cathode and an aluminum electrode as an anode;

b, adding the cathode electrolyte and the anode electrolyte into an electrolytic cell respectively, carrying out electrochemical reduction on the indigo for 130min under the conditions of 8V of electrolytic voltage and nitrogen protection, placing a reduction potentiometer into a dye solution at 25 ℃ after the reduction is finished, and reading a reduction potential value after the value is stable;

and c, putting the reduced dye liquor obtained in the step b into pure white half-bleaching coarse grain inclined cloth which is wetted by distilled water in advance for dyeing for 1min, wherein the dyeing bath ratio is 1:25, ventilating and oxidizing after dyeing is finished, then carrying out soap boiling and water washing to finish dyeing post-treatment, and testing the color depth K/S value of the finally obtained fabric.

Example 4

step a, sequentially adding 0.05mol/L ferric chloride, 0.1mol/L triethanolamine, 0.2mol/L sodium gluconate, 0.01mol/L aluminum nitrate and 0.2mol/L indigo blue into 0.5mol/L sodium hydroxide aqueous solution, and fully stirring to obtain a cathode electrolyte; the anolyte is 2mol/L sodium sulfate aqueous solution; taking an aluminum electrode as a cathode and a nickel electrode as an anode;

b, adding the cathode electrolyte and the anode electrolyte into an electrolytic cell respectively, carrying out electrochemical reduction on the indigo for 120min under the conditions of 15V of electrolytic voltage and nitrogen protection, putting a reduction potentiometer into a dye solution at 25 ℃ after the reduction is finished, and reading a reduction potential value after the value is stable;

and c, putting the reduced dye liquor obtained in the step b into pure white half-bleaching coarse grain inclined cloth which is wetted by distilled water in advance for dyeing for 1min, wherein the dyeing bath ratio is 1:5, ventilating and oxidizing after dyeing is finished, then finishing dyeing post-treatment by soap boiling and water washing, and testing the color depth K/S value of the finally obtained fabric.

Example 5

step a, sequentially adding 0.1mol/L ferrous nitrate, 0.2mol/L sodium oxalate, 0.3mol/L sodium gluconate, 0.015mol/L aluminum nitrate and 0.1mol/L indigo blue into a 0.03mol/L sodium hydroxide aqueous solution, and fully stirring to obtain a cathode electrolyte; the anolyte is 2mol/L sodium hydroxide aqueous solution; taking an aluminum electrode as a cathode and a magnesium electrode as an anode;

b, adding the cathode electrolyte and the anode electrolyte into an electrolytic cell respectively, carrying out electrochemical reduction on the indigo for 80min under the conditions of 15V of electrolytic voltage and nitrogen protection, putting a reduction potentiometer into a dye solution at 25 ℃ after the reduction is finished, and reading a reduction potential value after the value is stable;

and c, putting the reduced dye liquor obtained in the step b into pure white half-bleaching coarse grain inclined cloth which is wetted by distilled water in advance for dyeing for 1min, wherein the dyeing bath ratio is 1:50, ventilating and oxidizing after dyeing is finished, then carrying out soap boiling and water washing to finish dyeing post-treatment, and testing the color depth K/S value of the finally obtained fabric.

Example 6

step a, sequentially adding 0.02mol/L ferric nitrate, 0.1mol/L sodium citrate, 0.02mol/L aluminum chloride and 0.005mol/L indigo into 0.25mol/L sodium hydroxide aqueous solution, and fully stirring to obtain a cathode electrolyte; the anolyte is 2mol/L sodium sulfate aqueous solution; taking an aluminum electrode as a cathode and a graphite electrode as an anode;

In order to better illustrate the technical solution of the present invention, further comparison is made below by means of a comparative example and an example of the present invention.

Comparative example 1

step a, sequentially adding 0.02mol/L ferric nitrate, 0.1mol/L sodium citrate, 0.02mol/L aluminum chloride and 0.005mol/L indigo into 0.25mol/L sodium hydroxide aqueous solution, and fully stirring to obtain a cathode electrolyte; the anolyte is 2mol/L sodium sulfate aqueous solution; taking a nickel electrode as a cathode and a graphite electrode as an anode;

Comparative example 2

step a, sequentially adding 0.02mol/L ferrous sulfate, 0.04mol/L sodium gluconate, 0.005mol/L aluminum sulfate and 0.0095mol/L indigo into 0.2mol/L sodium hydroxide aqueous solution, and fully stirring to obtain a cathode electrolyte; the anolyte is 2mol/L sodium hydroxide aqueous solution; taking a graphite electrode as a cathode and taking the graphite electrode as an anode;

Comparative example 3

step a, sequentially adding 0.02mol/L ferrous sulfate, 0.04mol/L sodium gluconate and 0.0095mol/L indigo in 0.2mol/L sodium hydroxide aqueous solution, and fully stirring to obtain a cathode electrolyte; the anolyte is 2mol/L sodium hydroxide aqueous solution; taking an aluminum electrode as a cathode and a graphite electrode as an anode;

Comparative example 4

step a, sequentially adding 0.02mol/L ferrous sulfate, 0.04mol/L sodium gluconate, 0.005mol/L aluminum sulfate and 0.0095mol/L indigo blue into water, and fully stirring to obtain a cathode electrolyte; the anolyte is 2mol/L sodium hydroxide aqueous solution; taking an aluminum electrode as a cathode and a graphite electrode as an anode;

The data tested for examples 1-6 and comparative examples 1-4 are tabulated below:

TABLE 1 test results

	Dyed fabric K/S	Reduction potential/-mV	Electrolytic Current/mA
				Example 1	32.78	953	295
Example 2	30.34	913	225
				Example 3	32.34	907	241
Example 4	31.15	925	276
				Example 5	30.97	908	239
Example 6	32.08	916	251
				Comparative example 1	15.78	713	175
Comparative example 2	17.22	785	188
				Example 3	10.59	645	167
Comparative example 4	4.23	572	196

The method for measuring the reduction potential comprises the following steps: according to the method for measuring the oxidation-reduction potential of the industrial standard SL94-1994, an oxidation-reduction potentiometer is utilized, the reduction potentiometer is placed into the dye solution at normal temperature, and after the value is stabilized, the reduction potential value is read. The larger the absolute value of the reduction potential, the stronger the reducing power of the system to the dye.

The method for measuring the electrolytic current comprises the following steps: and (3) reading a current value and a voltage value after the RXN-1503 type direct current stabilized power supply is electrified and the values are stabilized. Under the same voltage condition, the higher the current value, the better the conduction efficiency of the current of the system is shown.

The method for measuring the dyeing depth of the fabric comprises the following steps: the dyed sample is folded into 3 layers (opaque) by adopting a Color-i5 computer Color measuring and matching instrument for testing, a 10-degree visual field and a D65 light source, a K/S value is tested, 3 different positions of each piece of fabric are measured, and an average value is obtained. Higher K/S values indicate darker colors of the dyed fabric, better dyeing.

As can be seen from Table 1, in the case of using the catholyte containing aluminum salt and iron salt and using the aluminum electrode as the cathode electrolytic system, the conductive current and the reduction potential of the electrolyte (dye solution) are significantly better than those of the iron salt-aluminum electrode system or the aluminum salt-iron salt-non-aluminum electrode system, the reduction time is shortened, and the dyeing depth is increased. Compared with the traditional dyeing process, the reduction time is also shortened, the dyeing effect is slightly good, the indirect electrochemical dyeing cathode electrolysis system and the electrochemical dyeing process provided by the invention are suitable for indigo dyes and other vat dyes, can obviously shorten the reduction time, and obviously improve the reduction potential of the dye solution and the conduction current of the electrolyte.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents or improvements made within the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. An electrolytic system for indirect electrochemical dyeing characterized by: the solute of the cathode electrolyte comprises soluble iron salt, polyhydroxy ligand, soluble aluminum salt and sodium hydroxide; the cathode electrode is an aluminum electrode.

2. Electrolytic system for indirect electrochemical dyeing according to claim 1, characterized in that: the concentration of the soluble ferric salt is 0.01-0.1mol/L, the concentration of the polyhydroxy ligand is 0.02-0.5mol/L, the concentration of the soluble aluminum salt is 0.0025-0.02mol/L, and the concentration of the sodium hydroxide is 0.03-0.5 mol/L.

3. Electrolytic system for indirect electrochemical dyeing according to claim 2, characterized in that: the molar ratio of the polyhydroxy ligand to the soluble iron salt is 2-5: 1.

4. Electrolytic system for indirect electrochemical dyeing according to claim 1, characterized in that: the soluble aluminum salt is aluminum sulfate, aluminum chloride or aluminum nitrate; and/or

The soluble ferric salt is ferric sulfate, ferric nitrate, ferric chloride, ferrous sulfate, ferrous nitrate or ferrous chloride; and/or

The polyhydroxy ligand is at least one of sodium gluconate, sodium oxalate, sodium citrate, lactic acid, triethanolamine or tartaric acid.

5. Electrolytic system for indirect electrochemical dyeing according to claim 1, characterized in that: the anode electrode is graphite, nickel, copper, magnesium, zinc, aluminum or iron electrode.

6. Electrolytic system for indirect electrochemical dyeing according to claim 1, characterized in that: the electrolyte of the anolyte is sulfuric acid, sodium hydroxide, sodium sulfate or sodium metabisulfite, and the concentration of the electrolyte is 1-2 mol/L.

7. An electrochemical dyeing process characterized in that fabrics are dyed by electrochemical reduction of vat dyes in the presence of a protective gas at constant voltage using an electrolytic system for indirect electrochemical dyeing according to any one of claims 1 to 6.

8. Electrochemical dyeing process according to claim 7, characterized in that: the voltage is 1-15V; and/or

The time of the electrochemical reduction is 20-180 min; and/or

The protective gas is nitrogen or argon.

9. Electrochemical dyeing process according to claim 7, characterized in that: the concentration of the vat dye is 0.005-0.2 mol/L; and/or

The dyeing bath ratio of the dyeing is 1: 5-50.