JPH03119190A - Treatment of water of paper-making process - Google Patents

Abstract

PURPOSE:To provide a process for the treatment of water of paper-making process, exhibiting remarkable adsorptivity to suspending material and effective in neutral or higher pH range by adding a cationic surfactant having ammonium group and a specific composite particle to the water of paper-making process. CONSTITUTION:Composite particles consisting of (A) a cationic surfactant having quaternary ammonium group and (B) a mineral composed mainly of montmorillonite are added to water of paper-making process to effect the adsorption and separation of pollutant. Preferably, the component A is a quaternary ammonium surfactant having one or more 8-20C aliphatic chains and the component B is a mineral carrying positive electric charge in water.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for removing pollutants in papermaking process water. The present invention relates to a method of adsorption and separation using an adsorbent.

[Conventional technology]

In the present invention, papermaking process water refers to water used in the papermaking process or discharged during that process.In addition to fibrous substances, the papermaking process water contains minerals, coating agents, and Contains pollutants from raw material processing processes such as agents, inks, pigments, wood resins, and adhesives. In recent years, closed-system raw material processing processes that actively recycle water have become the most popular method to reduce water consumption, but in this case, the accumulation of pollutants in the process water is the most problematic. Become. These substances may cause problems such as valve contamination, scale, slime, pitch, and sticky substances, and corrosion of equipment, as well as reducing the effectiveness of chemicals used, especially P-water agents and yield improvers. be.

Traditionally, such pollutants are removed by treatment with flocculants such as aluminum sulfate (alum) and polymer electrolytes, and adsorbents such as fine talc and bentonite, which are uniformly fixed on the pulp. It is removed outside the system, or in circulating water, it is actively removed by coagulation-sedimentation separation or flotation separation treatment.

[Problem to be solved by the invention]

Alum is commonly used for these measures, but the usable pH is
The disadvantage is that the range is narrow and it cannot be used above neutrality. Polymer electrolytes are used for this purpose, but they are generally ineffective when used alone, so they are used in combination. However, it is complicated and requires strict control of optimal usage conditions, especially the amount used.

The use of adsorbents such as talc and bentonite is preferred because of its ease of operation, but the disadvantage is that it is less effective. One reason for this is that the pollutants in the papermaking process water are usually strongly negatively charged, and adsorbent particles such as talc and bentonite are also negatively charged, so the electrostatic repulsion between the two causes them to become adsorbent. This is because it falls. In particular, at pH levels above neutrality, the degree of negative charge increases, and therefore adsorption of pollutants tends to become more difficult.

Therefore, it seems that an adsorbent that is positively charged over a wide pH range can efficiently adsorb these pollutants.

In view of the above, the main purpose of the present invention is to develop these adsorbents.

[Means to solve the problem]

That is, the present invention provides a paper manufacturing process characterized in that composite particles of a cationic surfactant having a quaternary ammonium group and a mineral mainly composed of montmorillonite are added to paper manufacturing process water to adsorb and separate pollutants. The present invention provides a method for treating process water. By using particles that are a composite of a cationic surfactant with a quaternary ammonium group and a clay mineral mainly composed of montmorillonite, it is possible to adjust to a wide range of pH levels.
The present invention has been completed based on the discovery that the material is positively charged and has a remarkable effect on adsorbing pollutants in the papermaking process water.

The surfactant having a quaternary ammonium group used in the present invention is an ammonium salt having one or two direct or branched long chain hydrocarbon groups, and is generally represented by the following chemical formula. As expected.

R"R-N"-R" ・X- 11 or RI+ RN"-R' ・X- R" Here, R and Ro represent the same or different long-chain hydrocarbon groups, and the number of carbon atoms is 8 to 20 is preferred. For example, octyl, decyl, dodecyl, cetyl, stearyl, etc. are usually used. Groups other than the long chain hydrocarbon group bonded to the nitrogen represented by R'' include lower hydrocarbon groups, e.g. It may be a group such as methyl, ethyl, propyl or butyl. X is a counter ion of quaternary ammonium, such as halogen (F-C1-, Br-, I-), NO.

ct(, COO-H3O,-, etc.).

Other ammonium salts include the above R or Ro
Pyridinium salts having a long-chain hydrocarbon represented by the above, benzalkonium salts having a benzyl group, and the like can also be mentioned.

Typical clay minerals include montmorillonite clay minerals, kaolinite clay minerals, seviolite, allophane, etc. The clay mineral used in the present invention has montmorillonite as its main component and has the chemical formula Al2O*4SiOz.
・A mineral represented by H2 (this H2 is exchangeable with Na, KCa, Mg), specifically montmorillonite, bentonite (exchange ions are mainly Na and Ca), acid clay (exchange ions are mainly Na and Ca), and acid clay (exchange ions are mainly Na and Ca). (part of which is H).

To produce the composite particles used in the present invention, these cationic surfactants are composited with clay minerals mainly composed of montmorillonite. As a composite method, it can be obtained by adding an aqueous solution of a surfactant to an aqueous suspension of clay minerals of appropriate particle size, stirring, filtering, drying, and pulverizing as appropriate. In addition, it can also be produced by absorbing and drying an aqueous solution or an organic solvent solution of a cationic surfactant into a clay mineral.

The mixing ratio of cationic surfactant and clay mineral is permissible within a wide range, but as a rough guide, 1 part by weight is acceptable.
/100/~100/100, preferably 10/10o
~40/100.

Montmorillonite clay minerals have a strong cation exchange ability and have been used as adsorbents since ancient times. Due to its ion exchange ability, various methods have been studied to create clay-organic substances or clay-metal composites by infiltrating organic molecules or metal complexes between the layers of montmorillonite clay minerals. Although some attempts have been made to use these composites as adsorbents, such as composites of hydrated aluminum, hydroxylammonium, laurylamine hydrochloride, etc., there are currently very few attempts. (For example, see 1989, Vol. 15, No. 2, pp. 45-53).

In the present invention, composite particles produced by combining a cationic surfactant having a quaternary ammonium group with a clay mineral whose main component is montmorillonite are added to papermaking process water to adsorb pollutants. After that, the pollutants in the papermaking process water can be removed by adsorbing them onto the pulp and removing them from the system, or by removing the resulting composite particles after adsorbing the pollutants through separation operations such as coagulation sedimentation, centrifugation, and flotation. This is an attempt to remove foreign matter.

The removal of pollutants by the method of the present invention is very effective over a wide pH range.

Although the removal of pollutants of the present invention is not specified by any theory, as can be seen from the following examples, the zeta potential (a value measured in place of the surface potential) of the complex in water. An indicator of the charge of particles.Unit: mV
For details, see Paper Valve Technology Times May 1986 issue 49~
It is recognized that the removal rate is greatly improved when the relationship (see page 54) is positive, and it can be seen that this relationship contributes to the removal rate.

Below, the present invention will be explained in more detail with reference to Examples.

〔Example〕

(Week 9311 - ↓ The quaternary ammonium surfactants used here were tetrabutylammonium chloride (T13AC), tetrabutylammonium bromide (TBAB), octyltribromide, methylammonium (OTM8B, Lauryl 1-limethylammonium bromide (to LTM8B, cetyltrimethylammonium chloride (CTM80), cetyltrimethylammonium bromide (to CTM8B, stearyltrimethylammonium bromide (to STM8B, dioctyl dimethyl bromide) Ammonium (DODM8B) to dilauryldimethylammonium bromide (DCDMAB), dicetyldimethylammonium bromide (DCDMAB), distearyldimethylammonium bromide (DSDM8B) to octylstearyldimethylammonium bromide (OSDH8B) Laurylstearyldimethylammonium hebromide (LSD
M8B) to cetylpyridinium bromide (CPB), stearylpyridinium bromide (SPB), benzalkonium chloride (Bzc), etc.

Bentonite, a typical clay mineral whose main component is montmorillonite, was used.

The amount of quaternary ammonium salt added was equivalent to 0.9 milliequivalents/g of cation exchange capacity of 1~ bentonite.

For example, for STM 8B, add 26 parts to 100 parts of bentonite, and for OTM 8B, add 1 part of bentonite.
19 parts were added to 00 parts.

These aqueous solutions of quaternary ammonium salts were added to the bentonite aqueous suspension with vigorous stirring, and after being left for a while, the product was filtered and dried (by blow drying at 60° C.).

The dry solid was pulverized using a pulverizer, and the particles that passed through a sieve with a predetermined mesh size were used as samples. In most cases a 100 mesh sieve was used.

For comparison, samples in which various amines or amine hydrochlorides were composited were also synthesized according to Synthesis Example 1.

The composite of aqueous phase aluminum and bentonite used in the comparative example described below was prepared according to the method of Hayashi et al. (Clay Science, Vol. 19, No. 1, 22-32, 1979).

This composite particle is said to have high performance as an adsorbent.

Bentonite composites containing different amounts of cetyltrimethylammonium bromide (CTM8B) were prepared, and their zeta potentials were measured. The results are shown in Table 1.

Table 1 0.1% of the composite particles prepared in Reference Example 1 were added to the circulating water of the paper manufacturing process (waste paper processing process water, suspended suspended solids Ji 100 ppm), and the pH was adjusted to 4.5. After adjustment, the mixture was centrifuged and the absorbance of the supernatant to ultraviolet light at 280 nm was measured. The absorbance of the original circulating water was set as 100, and the rate of decrease in absorbance was defined as the adsorption removal rate (%). The results are shown in Table 2.

The total amount of 25% of CTM88 is approximately equivalent to the cation exchange capacity of bentonite. When the amount added to CTM8B exceeds 15%, the zeta potential of the composite particles becomes positive.

It maintains a positive charge even in an alkaline state of pH 10.

It is clear that the reduction rate increases rapidly at a blending amount of 15% or more at which the zeta potential becomes positive, and the adsorptivity increases dramatically.

11 Add 0.5% of all the composite particles prepared in Synthesis Example 1 to the circulating water used in Example 1, adjust the pH to 4.5, and measure the absorbance of the supernatant after centrifugation in the same manner as in Example 2. The 6 results of measuring the reduction rate are: TBAC: 35.2, TBAB
: 3B, 7, OTM^B:59.1, LTM^B=
82.7, CTM8C to 90.9, CTM^B:
94.0, STMΔB: 95.7, DOD
M^B: 88.2, DLDNA [l: 95.9, [
lCDM^B: 96.0, DSDM^B near 8.1
．． 0SDH8B: 96.2, LSDM^B: 93.
4, CI'B: 93.0, SPB: 93.1,
Bzc: 90.6%.

Bentonite composited with TBAC and TBAB has a lower effect than other particles, and those with four butyl groups are not preferred; other composite particles have high removal effects, but OTM^B, LT14AB, and CTM^ B,S
When comparing TM^B, there is a tendency that the longer the alkyl chain, the higher the effect.

0.5% of particles composited with bentonite were added to the circulating water used in Example 1 to adjust the pH to 4, 5, 7,
An experiment similar to Example 1 was conducted by adjusting the values to 0, 10, and 0. As a result, the removal rates were 94.0% and 96.0%, respectively.
, 91.0%. It exhibits high removal efficiency over an extremely wide pH range.

After adding 0.5% of finely divided talc, bentonite or acid-treated kaolin to the circulating water used in Example 1 to adjust the pH to 4.5, the same experiment as in Example 1 was conducted. The results were 58.4 for fine talc and 47.5 for bentonite.
For acid-treated kaolin, the removal rate was 26.7%. Although the above-mentioned particles are commonly used for removing pollutants from paper manufacturing process water, they are far less effective than the composite particles of the present invention.

[11 Example 1 A sample prepared by complexing diethylenetriamine, ocdylamine, I-lioctylamine, laurylamine, and stearylamine hydrochloride with bentonite 1~ according to Synthesis Example 1 at an addition rate of 0.5%. A similar experiment was conducted.

The respective reduction rates are 51.5, 41.5°34.6, 4
They were 4.5 and 27.6%. With amines, particles composited with quaternary ammonium salts generally do not provide any effect.

As a result of carrying out the same experiment as in Example 1 using a sample in which aluminum hydrate was composited with bentonite at an addition rate of 0.5%, a high removal rate of 90.7% was obtained at pH 4.5. However, the effect decreases at pH above neutral, and at pH 10,
0, the effect was 17.5% and could not be obtained.

〔Effect of the invention〕

As explained above, composite particles made by combining a surfactant with a quaternary ammonium group and a clay mineral mainly composed of montmorillonite have a positive charge in a wide pH range, and are effective against pollutants in papermaking process water. These composite particles were found to have a remarkable adsorption capacity, and it became possible to easily treat alcoholic substances with these composite particles.

In addition, it has become possible to process at pH levels above neutral, which was previously difficult.

Claims (1)

[Scope of Claims] Composite particles of a cationic surfactant having primary and quaternary ammonium groups and a mineral whose main component is montmorillonite are added to papermaking process water to adsorb and separate pollutants. A method for treating papermaking process water. 2. The method according to claim 1, wherein the cationic surfactant is a quaternary ammonium surfactant having at least one fatty chain having 8 to 20 carbon atoms. 3. The method according to claim 1, wherein the composite particles have a positive charge in water.