DD301106A7 - FLOCKING AGENT AND METHOD FOR PRIMA FLOCKING OF CATIONIC DYES - Google Patents

Abstract

The invention relates to a flocculant and to a process for the primary flocculation of cationic dyes in the aqueous phase by a temperature-induced flocculation using a flocculant mixture of partially acylated linear polyethyleneimine and alkali polyphosphates.

Description

characterized in that the flocculant consists of a prepared at 338 K <T <358 K mixture of aqueous solution of polyethylenimine and water-soluble alkali metal salts of polyphosphoric acid in a molar ratio χ of phosphate to imino 0.4 <χ <0 9.

2. flocculant according to claim 1, characterized in that the alkali salt of the polyphosphoric acid is sodium polyphosphate.

3. A process for the primary flocculation of cationic dyes from aqueous media by an aqueous solution of a linear teilacylierten Polyethylenimjns of general formula I,

CH;

N - O η C = R

:; - CH ₃ - N

wherein the ratio n / m 0 <n / m <1 and R = CH ₃ or C ₆ H ₆ , characterized in that a mixture of aqueous polyethylenimine solution and water-soluble alkali metal salts of the polyphosphoric acid in the molar ratio χ of phosphate to imino 0 , 4 <x <0.9, at temperatures of 338 K <T <358 K, the mixture is introduced into the dye-containing aqueous medium to be flocculated at a temperature TS308K and a pH = 7 with thorough mixing, with 10 to ⁶ g of dye solution 5 20Og flocculant solids are used, after which the flocculation is worked up in the usual way. 4. The method according to claim 3, characterized in that the water-soluble alkali salt of the polyphosphoric acid is sodium polyphosphate.

Field of application of the invention

The invention relates to a flocculant and a process for the primary flocculation of cationic dyes from aqueous media.

Characteristic of the known state of the art

In addition to inorganic primary flocculants such as ferric chloride and aluminum sulfate, an organic primary flocculant based on polyacrylonitrile and dicyandiamide has also been known for some time (DD-PS 217197), in which the polyampholyte used as flocculant becomes water-insoluble and in the form of very large, voluminous Flakes of water ingredients wrapped and segmented.

As unfavorable here proves the need for the dissolution of the flocculant in aggressive media (acids or bases) and the necessary pH change during the flocculation process.

Under environmentally friendly, gentle conditions, however, a temperature-induced Primärt.'ockung by means of linear teilacyliertem and / or linear non-acylated Polyethyienimin, which has also proved to be suitable for flocculation of dissolved water constituents.

A disadvantage here is the high flocculant metering with about BOOppm a 4-6% solution of the precipitating component.

Also known is the use of a flocculant mixture of polyethyleneimine with low molecular weight phosphates for use in normal temperatures (Japanese Patent Laid-Open No. 60-102993). The disadvantage here are the necessary higher amounts used or the lower efficiency of the agent in the Flcckungsverfahren in terms of quantity dor separation of the substances to be flocculated and the speed of flocculation.

Object of the invention

The aim of the invention is to develop a flocculant and a process for the primary flocculation of dyestuffs, which is easier to carry out and more economical to use.

Explanation of the essence of the invention

The object of the invention is to develop an improved in effect and technically easy to handle flocculant and method for temperature-induced primary flocculation of cationic dyes by means of aqueous polymer blends of linear teilacyliertem polyethyleneimine. It has been found that a mixture of linear partially acylated polyethyleneimine of general formula I,

CH. - CHh - IM

C --- O

CH = - N

Il

in which R = CH ₃ or C ₆ Hf ₁ and the ratio n / m 0 <n / m <1, surprisingly with the alkali metal salts of the polyphosphoric acid at temperatures> 338K, preferably 338K <T <35K & K dissolved and by temperature variation as primary flocculant cationic dyes fails, woboi the flocculant in amounts of 5-20Og solid per 10 ⁶ g in the dye-containing aqueous liquids with pH 7 and a temperature <308K with mixing to bring

The advantage of the invention is an almost complete decolorization of cationic dyes despite reduced flocculant use.

embodiments

example 1

In 10 ml of a methylene blue solution (1 g of cationic dye / 1000 ml of water) was introduced a mixture of a linear PEI solution (formula I) (10 g / 1000 ml of water) with an inadequate ratio / m = 0.1 and R = CH ₃ with sodium polyphosphate, the molar ratio being χ from phosphate to imino groups from the following experimental examples.

Flocculant addition: 5μΙ Temperature: 293K Separated fraction: 67.5%

Flocculant addition: 10μΙ Temperature: 293K

Severed share: 73%,

Flocculant addition: 25μΙ Temperature: 293 K Separated fraction: 98%

Flocculant addition: 10μΙ Temperature: 274K Separated fraction: 83%

Example 2

In 10 ml of a methylene blue solution (1 g of cationic dye / 1000 ml of water), a mixture of a linear polyethyleneimine solution (formula I) (10 g / 1000 ml of water) with a ratio n / m = 0.1 and R = C ₆ H ₆ with sodium polyphosphate was introduced the molar ratio χ of phosphate to imino groups can be seen from the examples below.

Flocculant addition: 203 μΙ Temperature: 293K Separated fraction: 20%

Flocculant addition: 200 μΙ Temperature: 293K Separator percentage: 70%

Example 3

In 10 ml of a methylene blue solution (1 g of cationic dye / 1000 ml of water) was introduced a mixture of a linear polyethyleneimine solution (formula I) (10 g / 1000 ml of water) with a ratio n / m = 0.7 and R = C ₆ H ₆ with sodium polyphosphate, the molar ratio χ of phosphate to imino groups being evident from the following experimental examples.

Flocculant addition: 200 μΙ Temperature: 293K Separated fraction: 30%

Flocculant addition: 200 μΙ Temperature: 293K Separate fraction: 45%

Claims (1)

Claim: 1. flocculants for primary flocculation of cationic dyes for use in aqueous media, using linearly teilacyliertem Polyethyl6nimin the general formula I, wherein the ratio n / m 0 <n / m <1 and R = CH ₃ or C ₆ H ₆ means CH ₂ --CH ₃ --N C = O CH ₃ - CH = - N