CS249611B1 - Method of preparation of auxiliary chemicals for leather industry - Google Patents

Abstract

The method of preparing auxiliary agents for the leather industry consists in treating waste aqueous solutions containing acrylic or methacrylic acid or their salts, or containing inorganic salts, with a basified solution of chromium or aluminum salts and adjusting the pH of the resulting product to pH 2.5 to 7.

Description

The invention relates to a process for the preparation of chemical auxiliaries for the leather industry from waste wash water.

The use of chromium and aluminum salts of various organic acids as chemical auxiliaries in the leather industry is described in the literature. These compounds are made from pure raw materials, relatively expensive. It has now been found that waste waters from the production of various esters of aliphatic unsaturated acids, for example acrylic, methacrylic, have a relatively high initial acid content, according to the process cell free or often in the form of sodium or potassium salt. sodium sulfate and the like or free inorganic acids such as sulfuric acid.

Example of composition of waste wash water (alkaline) used for preparation of auxiliary agents:

% acrylic sodium ropes 10.7 to 29.7 wt.

sodium sulfate 0.1 to 4.6 wt.

sodium bicarbonate 0 to 4.6 wt.

1.13 to 1.17 g / cm 2

PH 5 5.2 to 10 Example of acid wastewater composition: • 0.9 g / c 5 5 pH = 4.5 acrylic acid 9 9.6 wt.

Isolation of unsaturated aliphatic acrylic or methacrylic acid or their salts, for example sodium, from waste wash water is expensive, and the quality of the product obtained is not satisfactory.

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The presence of inorganic salts also makes problems. Also, the dark color of the product is undesirable for many purposes. The disposal of these waters is problematic. Due to the content of organic substances and inorganic salts, these waters cannot be discharged into watercourses for ecological reasons, despite the economic losses, due to the relatively high content of valuable aliphatic unsaturated acid.

The aforementioned drawbacks are eliminated by the process for the preparation of chemical auxiliaries for the leather industry according to the invention, which consists in treating waste aqueous solutions containing acrylic or methacrylic acid or their salts or inorganic salts with a basic solution of chromium or aluminum salts and The pH of the resulting solution was adjusted to pH 2.5 to 7 with acid.

The reaction rate of the formation of complex compounds resulting from the reaction of Cr + 3 and / or Al ^{+ 4} salts with acrylic acid and / or methacrylic acid or a salt thereof is so great that the length of the reaction time does not substantially affect the progress and yield of the reaction.

The reaction proceeds in the liquid phase over a very wide range from + 4 ° C to the boiling point of the reaction mixture. For the composition of the reaction mixture, it is necessary that the molar ratio of metal to acrylic acid and / or methacrylic acid or salts thereof be at least equimolecular, preferably in excess over a wide range, for example up to 20 times mol. surplus.

It has been found that waste waters of this composition can be used advantageously to produce chromium or aluminum or mixed chromium-aluminum acrylic or methacrylic acid complex compounds, which can be advantageously used as a leather aid. The addition of inorganic salts which are contained in the final product is not a problem for this application.

The alkaline reaction of the waste water is advantageously used, since the auxiliaries prepared for leather purposes need to be basified.

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The reaction products are produced in a high yield, in a satisfactory purity and practically destroy the organic waste water component.

The products obtained show very good application properties. They are formed in the form of an aqueous suspension with a high content of the desired product. For the resulting product, it is advantageous to adjust the pH to an pH of 2.5 to 7 with an organic acid such as oxalic acid or an inorganic acid such as dilute sulfuric acid.

Example 1

In 125 g of water was dissolved 120.5 g of Crg (SO 2) 3 with HgO.

To this solution at 50 ° C was added a solution containing 20 g of Na 2 CO 5, 30 g of NaOH in 65 g of water and waste water containing 29.7% of sodium acrylate in an amount corresponding to 15 g of sodium acylate.

The composition of the corresponding wash water was 29.7 wt. % sodium acrylate, 2.7 wt. sodium sulfate, density = 1.15 g / cm 2, pH = 5.2. 410 g of the product were prepared in the form of a suspension. The dry matter content was 44.6%. The product was used for tanning bovine ground split at a thickness of 3 to 3.5 mm. 15 wt. on the weight of the clearing. The leather thus treated had a shrinkage temperature of 78 ° C.

Example 2 g of KCr (SO4). 12 HgO was dissolved in 200 g of water at 30 ° C. An aqueous solution of sodium acrylate in the form of waste water was added with stirring. The amount of water added was 84.6 g sodium acrylate. Then a solution of 53 g of ββ θθ in 100 g of water was added. The reaction mixture was stirred for 2 hours. 700 g of product were obtained in the form of a red-violet suspension with a dry matter content of 22.5%, and the pH of the product was adjusted to 5.8 by the addition of 50% H2SO4. Composition of waste water used:

content - sodium acrylate 17,7% wt.

Na ₂ SO ₄ 0.05% wt.

NaHCO 3 0.51 wt.

= 1.13 g / cm? pH = 9.0.

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The resulting product was used for tanning cowhide cleaved at a thickness of 3 to 3.5 mm in an amount of 15% by weight. on the weight of the clearing. The leather thus treated had a shrinkage temperature of 80 ° C.

Example 3

In 250 g of water, 184 g of CH 2 SO 4 were dissolved. 5 H2O and 70 g Al2 / SO4 / 3. 18 H2O. To this solution was added 69 g Na 2 CO 5 and 12 g NaOH in 160 g water with stirring. The reaction mixture was stirred for one hour. Then 15 g NaOH in 125 g water was added. 25 g of sodium acrylate were added as waste wash water. Composition of washing water: 25.3% wt. sodium acrylate, 4.6 wt. Na 2 SO 4 = 1.17 g / cm 2, pH = 5.6.

910 g of a dark green suspension were prepared. The dry matter content is

34.8%, the pH of the product was adjusted to 4.2 with oxalic acid. This slurry was used for tanning bovine soil split at a thickness of 3 to 3.5 mm in an amount of 15% by weight. The weight of the leather thus treated had a shrinkage temperature of 84 ° C.

Example 4

204 g of AlCl 3 · 6 H 2 O was dissolved in 150 g of water. By adding 68 g of NaOH in 120 g, the basicity of the aluminum chloride was adjusted to 66% Sch. To this solution was added, with stirring, a solution of sodium acrylate in the form of waste water containing 47 g of sodium acrylate. The reaction mixture was stirred for 120 minutes. 490 g of a light brown suspension of 24.7% were obtained. The pH of the product was adjusted to 4.7 with dilute formic acid.

Composition of waste water used: sodium acrylate 10.7 wt%, Na 2 SO 4 0.1 wt%, NaHCO 4 5.25 wt%, = 1.15 g / cm 2, pH = 10. This treated product was used at tanning of cowhide cleaved at a thickness of 3 to 3.5 mm in an amount of 15% by weight; on the weight of the clearing. Thus, the treated leather had a shrinkage temperature of 73 ° C. The sample can be used for tanning or fur production.

Example 5

241 g of Crg (SO4) were dissolved in 250 g of water. 5 H ₂ 0. With stirring, to this solution was added at 50 ° C a solution comprising a C 40 g Na2C03 30 g of NaOH and 13.5 g of methacrylic acid in forms 5249611 me aqueous solution / wastewater containing: methacrylic acid 18.6 wt.%, Sulfuric acid 1.2 wt.%, PH = 2.3. The reaction mixture was stirred for 80 minutes. Product dark green suspension, dry matter 42.7%. The product in the form of a 10% solution has a pH = 3.7. The product was used for tanning cowhide cleaved at a strength of 3 to

3.5 mm in an amount of 15 wt. on the weight of the clearing. The leather thus treated had a shrinkage temperature of 83 ° C.

All samples prepared according to the method of the invention are useful for tanning or furry production.

Claims (1)

SUBJECT OF THE INVENTION Process for the preparation of chemical auxiliaries for the leather industry * characterized in that waste aqueous solutions containing acrylic or methacrylic acid or their salts or inorganic salts are treated with a basic solution of chromium or aluminum salts at temperatures in the range of 4 ° C to boiling the reaction mixture in a metal to acrylic or methacrylic acid molar ratio or salts thereof of 1 to 20: 1 and the pH of the resulting product is adjusted to a pH of 2.5 to 7.