KR100754610B1 - Preparation of Concrete Dispersant Using Wastes of Aromatic Oxidation Process - Google Patents

Abstract

The present invention relates to a method for preparing a dispersant from various unreacted products and by-products of wastes produced in the production of aromatic carboxylic acids by oxidation of aromatic compounds. Specifically, the method neutralizes and oxidizes the waste, and then mixes the concrete dispersant, other admixtures or additives with existing concrete at a ratio to increase the dispersibility, the air entraining effect, the fluidity improvement, and the concrete with the characteristics with little change over time. It is a method designed to prepare dispersants.

Aromatic Carboxylic Acid, Waste, Concrete Dispersant

Description

Preparation of Concrete Dispersant from Wastes Generated from Aromatic Carboxylic Acids by Oxidation of Aromatic Compounds {Preparation of Concrete Dispersant Using Wastes of Aromatic Oxidation Process}

The present invention relates to a process for the preparation of dispersants from various unreacted products and by-products in the wastes produced in the production of aromatic carboxylic acids by oxidation of the corresponding aromatic compounds having two or three oxidative ring substituents. Specifically, the present invention relates to the preparation of a dispersant having neutralizing and oxidizing treatment and mixing it with an existing concrete dispersant at a predetermined ratio, thereby improving air entraining effect, improving fluidity, and changing the flowability over time.

The process for producing aromatic carboxylic acids by oxidation of aromatic compounds includes the process of oxidizing o-xylene to produce phthalic acid, the process of oxidizing m-xylene to produce isophthalic acid, and 2,6-dimethylnaphthalene. There are various processes such as a process of oxidizing 2, 6-naphthalene dicarboxylic acid and a process of oxidizing pseudo cumene to prepare trimellitic acid.

Wastes generated during the process of producing terephthalic acid, which is a raw material of polyester, have a large amount of waste, and incinerators are mainly used to treat them.

Wastes generated during the process of oxidizing p-xylene (xylene) to produce terephthalic acid include various organic impurities in addition to the main product, terephthalic acid, which can be summarized as follows.

The primary route is the production of phthalic acid, isophthalic acid, trimellitic acid and benzoic acid by oxidation of p-xylene impurities o-xylene, m-xylene, pseudo cumene and toluene. .

The second pathway produces reactive intermediates such as p-tolualdehyde, p-toluic acid and 4-carboxybenzaldehyde by incomplete oxidation of p-xylene. .

Finally, 4-hydroxymethyl benzoic acid is produced as a side reaction during p-xylene oxidation.

In order to produce high purity terephthalic acid, the treatment of the impurities is essential. At this time, the waste sludge contains a large amount of acetic acid and impurity salts, and its viscosity is very high.

Among other ingredients, benzoic acid is the mainstream except for water. Since these wastes are mainly sent to incinerators for incineration, they have an adverse effect on production costs, and there are also concerns about secondary environmental pollution due to incomplete combustion products generated during incineration of wastes containing a large amount of water. to be. In order to solve this realistic problem, many studies have been conducted for the recovery of benzoic acid containing the highest amount.

TABLE 1

As far as is known, instead of using a strong reducing catalyst in the purification process of terephthalic acid, a mild catalyst with selective reducing properties reduces the production of 4-carboxybenzaldehyde and generates para-toluic acid. To recover the benzoic acid through a distillation column (Korean Patent Publication No. 91-3973), which is characterized by recovering ultra-high purity benzoic acid from the waste. There is a method of recovering benzoic acid by reacting with a compound, followed by sublimation, followed by treatment with sodium hydroxide (US Pat. No. 4,092,353), and a method of recovering benzoic acid by distillation in an alkali salt state using an aqueous alkaline solution (US Pat. 3,259,651), and a method of extraction using water at 100 ° C. or lower has been reported. (Japanese Patent Laid-Open Nos. 48-966541, 61-106535). However, these methods are difficult to put to practical use due to problems such as recovery rate and purity of recovered materials besides the disadvantage that new facility investment is required.

However, as an example of producing concrete dispersant using petroleum industry waste, petroleum sulfonate (PS), which is similar to the standard dispersant in terms of performance and is inexpensive, is being researched and released at home and abroad. Korean Patent 181010, Russian Patent, 97102303, US Patent 5,112,363, 5,100,438, 5,082,469, 5,100,438, UK Patent 2,230,207A, 2,099,451A, International Patent 92/0351, US Patent 5,186,846). However, the preparation of dispersant using conventional petrochemical wastes requires radical reaction conditions for sulfonation reactions, and the removal of salts generated by an excessive amount of sulfated agent causes difficulties in handling and operation of the process. However, the oxidation process of the present invention has the advantage of proceeding in a mild reaction condition for a short time within the atmospheric pressure, 100 ℃. In addition, the material produced by the present invention is expected to be used in the manufacture of high-strength concrete with less air mass entrainment or delayed cement hydration even when using an excess amount of the conventional concrete dispersant.

Fenton's reagent, which is a mixture of hydrogen peroxide and iron salt as an oxidant used as a chemical reactant of the present invention, has been studied in recent years, and its use has been actively studied in various industrial wastewater treatment fields. Fenton's reagent converts biologically degradable materials into biodegradable materials.The purpose of application of these materials is to reduce the toxicity of wastewater that contains toxic substances and thus adversely affect the microorganisms and to treat substances that have not been treated by the microorganisms. The trend is diversifying (Chemosphere, Vol. 39, No. 12, 1999, p. 1997-2006, Journal of the Korean Society for Environmental Engineering, Vol. 13, No. 2 1991, p. 123-132, Journal of Korean Society for Environmental Engineering, Vol. 25, No. 1 2003, p. 87-93 ).

The reaction mechanism of such a fenton reagent with an organic substance can be expressed as follows.

^{_{Fe 2+ + H 2 O 2 →}} Fe 3+ + OH - + · OH ... … … … … … … … (One)

OH + RH → R · + H 2 O ... … … … … … … … (2)

R + + OH → ROH... … … … … … … … (3)

R + H ₂ O ₂ → ROH + .OH. … … … … … … … (4)

ROH + 1 / 2O ₂ → ROOH. … … … … … … … (5)

Therefore, in the present invention, by using the waste which may raise the production cost and secondary environmental pollution problems, the material is converted into a material exhibiting the properties of the concrete dispersant, and can be used as the concrete dispersant, thereby effectively treating the environment and recycling. At the same time, it is to provide a dispersant and a method for producing the same dispersant is given a characteristic such as air entrainment effect, improved fluidity and reduced change over time flow by mixing a predetermined amount with the existing dispersant.

In order to achieve the above object, the present invention uses wastes generated in terephthalic acid manufacturing process as starting materials among various aromatic carboxylic acid manufacturing process wastes. As the oxidizing agent, there are various other phentone reagents, such as Fenton reagent, H ₂ O ₂ , KMnO ₄ , K ₂ Cr ₂ O ₇ , O ₃ , and K ₂ S ₂ O ₈ . After that, by mixing a predetermined amount with the existing dispersant, it is characterized in that it improves the characteristics such as air entrainment effect, improved fluidity and reduced fluidity change over time.

The oxidation reaction of typical aromatic organics using Fenton reagent is expected as follows.

Representative theories explaining dispersibility of unconsolidated concrete according to the amount of concrete dispersant are: DLVO (Derjagunin Landau Verway Over-beek) theory that achieves dispersion stability by electrical repulsive force between particles, dispersant structure, adsorption type and adsorption layer The three-dimensional effect theory explains that the dispersion stability of the particles is maintained by the three-dimensional repulsive force due to the thickness and the like.

That is, NSF-based and melamine-based dispersants are adsorbed on the surface of cement particles in the form of rods, and the cement particles are dispersed by the strong electrostatic repulsion force indicated by the negative ions of sulfonic acid groups bonded in the chemical structure. However, the most expensive and excellent polycarboxylic acid-based dispersant recently marketed has a synergistic effect due to the hydrogen bonding and the steric effect of the main chain or the side chain, together with the electrostatic repulsion by the negative ions of the carboxyl groups bound in the chemical structure. This is to obtain an excellent effect of dispersing the cement particles compared to the conventional dispersant.

The initial loss of fluidity of the flowing concrete is very detrimental to its workability, and the loss of fluidity over time and the addition of excess water eventually leads to poor strength concrete structures. Therefore, various types of admixtures are applied in the manufacture of the flow concrete to reduce the fluidity decrease (time-dependent change) according to the transfer time to the casting site of the initial flow concrete. At present, the most prominent effect is the carboxylic acid system, which is characterized by including a large amount of carboxyl groups and hydroxyl groups capable of hydrogen bonding in the molecular structure as described above. These functional groups are known to enable the maintenance of fluidity by retarding the hydration reaction in three dimensions by obstructing the direct contact of water and cement particles (C ₃ A and C ₃ S), which causes initial fluidity loss of the flow concrete.

In addition, these functional groups have the effect of remarkably improving the separation of aggregate and water in the flow-concrete compound, thereby imparting the necessary properties in the production of high-performance concrete. Therefore, since the concrete exhibits a higher strength after solidification, it is an essential element for structures requiring high flexural strength such as high-strength concrete or bridges required for recent frequent earthquakes and high-rises.

Accordingly, in the present invention, by oxidizing the waste generated during the production process of terephthalic acid using the Fenton reagent as in Schemes 6 and 7, the functional groups capable of hydrogen bonding such as carboxyl groups or hydroxyl groups existing in the structure of the existing compound are greatly increased. Theoretical characteristics of the present invention are to obtain an effect of improving dispersibility and stability of cement particles in the material by synergistically imparting electrostatic repulsion force by negative (-) ions and steric effect by main or side chains.

Hereinafter, the present invention will be described in detail through production examples and examples.

Preparation Example 1.

200g of waste produced during terephthalic acid was prepared with a solution of pH 6.0 ± 1.0 with NaOH (50%) solution and stirred for 30 minutes, and then the above solution was added to a reactor equipped with a thermometer, agitator, dropping device and reflux and sulfuric acid. 1 g of ferrous iron (FeSO ₄ ) is mixed and stirred for 30 minutes. After 30 minutes, 5 ml of hydrogen peroxide (15%) was slowly added dropwise and stirred for 30 minutes. After slowly heating to 80 ℃ and maintained at 80 ℃ for 1 hour to completely react the unreacted product to obtain the final product.

Preparation Example 2.

The sample was prepared under the same conditions as in Preparation Example 1, except that 10 ml of hydrogen peroxide and 2 g of ferrous sulfate (FeSO ₄ ) were used to obtain a product.

Preparation Example 3.

The preparation was carried out under the same conditions as in Example 1, except that 20 ml of water peroxide and 4 g of ferrous sulfate (FeSO ₄ ) were used to obtain a product.

Preparation Example 4.

The same procedure as in Preparation Example 1 was carried out under the same conditions, but the reaction temperature was 90 ° C. for 2 hours to obtain a product.

Preparation Example 5.

The same procedure as in Preparation Example 1 was carried out under the same conditions, but the reaction temperature was 70 ℃ for 2 hours to obtain a product.

The above method is not limited to wastes having the composition of Table 1 produced during the production of terephthalic acid, and is similar to the above for wastes produced during the production of aromatic carboxylic acids by oxidation of a corresponding aromatic compound having two or three oxidative ring substituents. Do.

For example, the process of oxidizing o-xylene to produce phthalic acid is a waste, the process of oxidizing m-xylene to produce isophthalic acid, and 2, 6-dimethylnaphthalene to oxidize 2,6-naphthalene dica This includes wastes from the process of preparing carboxylic acid and wastes from the process of producing trimellitic acid by oxidizing pseudo cumene.

Example 1 Concrete Preparation and Property Comparison

Samples prepared by mixing the preparations prepared in Preparation Examples 1 to 5 with a lignin sulfonate-based (LS) dispersant, which is mainly used as a general reducing agent in a concrete dispersant, in a weight ratio of 1: 1 (the preparation 1: LS 1). One concrete mixture (Preparation 1-5 in Table 2), a concrete mixture with added naphthalene sulfonic acid formaldehyde condensate (NSF) known as a representative high performance sensitizer (NSF in Table 2) and a concrete mixture without added concrete dispersant (Table In order to compare the effects on the strength of slump, air volume, and solidified coke concrete, the performances were added and tested for the performance of the plain concretes. The test results are shown in Table 2. .

The mix of materials and concrete used in the test is 370kg of Hanil Cement Co., Ltd. Portland cement, 805kg of Yeoju Instructor, 1021kg of coarse aggregate and 182kg of water including cement dispersant. The addition amount of each cement dispersant is an experiment result when it is 0.3 weight% with respect to cement solid content.

From the results shown in Table 2 below. The concrete mixture added with the concrete dispersant prepared in Preparation Example 3-5 showed the same 17.5% in the susceptibility as the NSF-added concrete mixture, and, unlike the case of NSF added with the air entrainer, 4.3 The air entraining effect was -4.7%, and concrete with excellent mechanical strength was obtained in the case of using NSF dispersant, which is a high performance sensitizer, and plain without the dispersant.

[Table 2] Performance characteristics of concrete containing the dispersant of the present invention

As mentioned above, according to the method of the present invention, the results of the characteristic test of the dispersant prepared by using the waste generated from terephthalic acid in the aromatic carboxylic acid manufacturing wastes are similar to those of the conventional dispersants. Prove that it has stability.

In addition, the present invention considers a problem that the production cost of the aromatic carboxylic acid production process is increased due to incineration, which is a waste treatment method generated in the conventional aromatic carboxylic acid production process, thereby causing a secondary environmental pollution problem. The production of high value-added dispersants using the waste from the above process is very meaningful from an environmental and economic point of view.

Claims (4)

i) adding a basic solution to the wastes generated during the production of terephthalic acid to neutralize the solution to pH 5.0 to 7.0 and ii) fenton reagent, H ₂ O ₂ , KMnO ₄ , K ₂ Cr ₂ O ₇ , O ₃ and K ₂ S ₂ O ₈ Method of producing a dispersant for concrete comprising the step of oxidizing the waste by adding and stirring an oxidizing agent selected from the group consisting of. delete The process of claim 1 wherein the waste comprises at least 5% by weight of the total dispersant. The method of claim 1, further comprising, after step ii), adding at least one material selected from the group consisting of an air entrainer, a slump holding agent, an antifoaming agent, a fastening agent, a retarding agent, a bleeding inhibitor, and a fireproofing agent. Manufacturing method.