KR20220116798A - Hydroxyapatite-Zeolite Composite Using Industrial Products And Method for Manufacturing the Same - Google Patents

Abstract

The present invention relates to a hydroxyapatite-zeolite composite in which a phosphoric acid solution, cetyltrimethylammonium bromide (CTAB), and an alkali activator are mixed with industrial by-products such as fly ash and fine slag powder and hydroxyapatite capable of adsorbing anions and zeolite capable of adsorbing cations are simultaneously synthesized so that large amounts of cations and anions can be absorbed.

Description

Hydroxyapatite-Zeolite Composite Using Industrial Products And Method for Manufacturing the Same

The present invention relates to a zeolite composite and a method for producing the same, and more particularly, by mixing a phosphoric acid solution, cetyl trimethylammonium bromide (CTAB; Cetyl trimethylammonium bromide) and an alkali activator with industrial by-products such as fly ash and fine slag powder to anion The present invention relates to a hydroxyapatite-zeolite complex capable of adsorbing a large amount of cations and anions by simultaneously synthesizing hydroxyapatite capable of adsorption and a zeolite capable of cation adsorption, and a method for preparing the same.

As road construction spreads along with the explosive increase in urban transportation demand, the urban air and water quality environment of rivers is rapidly deteriorating. For the continuous growth of the construction sector in the 21st century, the demand for functional materials that actively mitigate pollution sources in the surrounding environment is increasing.

Recently, for the purpose of water purification of urban rivers or lakes, river blocks manufactured by mixing natural or synthetic zeolite with concrete are used for water purification. For example, in Patent Registration No. 10-0961564, blast furnace slag cement, fly ash cement, and ordinary Portland cement are used as binders, and in order to maximize environmental pollution and water purification, natural zeolite, synthetic zeolite, Ca-type artificial zeolite and active Carbon is mixed in a predetermined ratio with respect to 100 parts by weight of the binder, and as an admixture, a fluidizing agent and a high-performance AE water reducing agent, and a hydrophilic polyamide fiber with a length of 3 to 30 mm to improve the structural performance and durability of concrete, polyvinyl Manufacturing method of high-functional eco-friendly concrete with excellent water and environmental purification and soil stabilization functions with excellent water and environmental purification performance and excellent physico-mechanical functions by mixing polyvinyl alcohol fibers, deformable steel fibers and rust-preventing mesh as reinforcing materials This is disclosed.

In addition, Patent Registration No. 10-1984862 discloses a high-strength zeolite having excellent adsorption performance by forming a number of nanopores by manufacturing high-strength zeolite from a geopolymer slurry mixed with fly ash, slag and alkali activator using hydrothermal synthesis reaction. and a manufacturing method thereof are disclosed.

However, these conventional zeolite composites have excellent cation adsorption performance, but do not adsorb anions, so there is a limitation in heavy metal removal ability, and there is a problem in that it is difficult to effectively use the calcium component contained in industrial by-products such as slag.

Republic of Korea Patent Registration No. 10-0961564 (Registered on May 27, 2010) Republic of Korea Patent No. 10-1984862 (registered on May 27, 2019)

The present invention is to solve the above problems, and an object of the present invention is to simultaneously synthesize hydroxyapatite having excellent anion adsorption performance and zeolite having excellent cation adsorption performance to adsorb a large amount of cations and anions, and to determine hydroxyapatite An object of the present invention is to provide a hydroxyapatite-zeolite composite capable of further improving adsorption performance by suppressing aggregation, and a method for manufacturing the same.

The hydroxyapatite-zeolite composite according to the present invention for achieving the above object is prepared by mixing fine industrial by-product powder, phosphoric acid solution, cetyl trimethylammonium bromide (CTAB), and alkaline metal hydroxide solution to form hydroxyapatite. and zeolite are synthesized.

The fine powder of industrial by-products may be made by using either one of fine fly ash powder and fine slag powder alone, or by mixing fine fly ash powder and fine slag powder.

The molar ratio of calcium (Ca)/phosphorus (P) of the hydroxyapatite-zeolite composite is preferably 1.3 to 1.7.

The method for preparing the hydroxyapatite-zeolite composite according to the present invention comprises:

(S1) mixing and stirring the industrial by-product fine powder and phosphoric acid solution;

(S2) adding cetyltrimethylammonium bromide (CTAB) and an alkaline metal hydroxide solution to the mixture made in step S1, and stirring while heating to a predetermined temperature; and,

(S3) curing the mixture of step S2 by heating it for a predetermined time without stirring;

includes

In the step S1, the elution of calcium ions is induced by stirring for 1 to 2 hours.

In step S1, the amount of phosphoric acid solution is adjusted and mixed so that the molar ratio of calcium (Ca)/phosphorus (P) is 1.3 to 1.7.

In addition, the step S2 may be carried out at a temperature of 90 ~ 120 ℃.

According to the present invention, hydroxyapatite with excellent anion adsorption performance and zeolite with excellent cation adsorption performance are synthesized simultaneously by mixing a phosphoric acid solution and an alkaline metal hydroxide solution with fine industrial by-product slag powder and fly ash fine powder, which can be used for water purification or air purification. can

In particular, cetyl trimethylammonium bromide (CTAB) is added to disperse the crystal nuclei of hydroxyapatite to inhibit crystal aggregation of hydroxyapatite, thereby increasing the specific surface area and further improving the adsorption performance.

1 is a graph showing the results of X-ray diffraction analysis of a hydroxyapatite-zeolite composite specimen.

Hereinafter, examples of the hydroxyapatite-zeolite composite and method for preparing the same according to the present invention will be described in detail.

The hydroxyapatite-zeolite composite according to the present invention is a fine powder of industrial by-products, including fine slag powder, fine fly ash powder, phosphoric acid solution, cetyl trimethylammonium bromide (CTAB), and alkaline metal hydroxide solution. It is a complex in the form of a powder in which hydroxyapatite and zeolite having excellent cation adsorption performance are simultaneously synthesized, and is a complex in which crystal aggregation of hydroxyapatite is minimized due to the addition of cetyltrimethylammonium bromide (CTAB).

The fine powder of the industrial by-product is a fine fly ash powder and a fine slag powder, and the fine fly ash powder and the fine slag powder may be used alone or in combination.

The fine slag powder is mainly composed of SiO ₂ , Al ₂ O ₃ , Fe ₂ O ₃ and CaO, and various other metal oxides such as K ₂ O, Na ₂ O, MgO, TiO ₂ and the like may be contained in small amounts. The calcium component of the slag reacts with phosphorus of phosphoric acid to synthesize hydroxyapatite [Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ ], and zeolite is synthesized from the excess component.

The fly ash fine powder includes SiO ₂ , Al ₂ O ₃ and Fe ₂ O ₃ , and some may have a crystalline structure or an amorphous structure. The fly ash is to synthesize zeolite. The fine fly ash powder is added to sufficiently increase the amount of zeolite synthesis, but as the amount increases, the synthesis of hydroxyapatite is hindered, so 30 wt% or less of the total weight of the composite is preferable.

The phosphoric acid solution increases the elution amount of the calcium component due to the acidity of phosphoric acid, and provides the phosphorus component necessary for the synthesis of hydroxyapatite. As shown in Table 1 below, it was confirmed that hydroxyapatite [Ca ₁₀ (PO ₄ ) ₆ (OH) ₂ ] has the highest specific surface area when the molar ratio of calcium (Ca) / phosphorus (P) is 1.33 to 1.67. Therefore, it is preferable to limit the molar ratio of calcium / phosphorus to 1.3 to 1.7.

Ca/P A (m2/g) 1.00 180.2 1.33 198.5 1.67 227.2 2.00 181.6

In addition, if too little phosphorus (P) is added, the synthesis rate of FAU zeolite will be lowered. Conversely, if too much phosphorus is added, the synthesis rate of Na-P1 (Na _5.92 Al ₆ Si _10O43.28 ) zeolite will be lowered, and either side will interfere with the synthesis of hydroxyapatite. becomes In addition, the phosphoric acid solution is acidic and induces calcium (Ca) ion elution, but if phosphoric acid is added too much, the pH becomes too low, which interferes with the synthesis of zeolite and hydroxyapatite.

The hydroxyapatite-zeolite composite causes crystal aggregation of hydroxyapatite due to its high alkalinity, which may cause a decrease in adsorption performance. By doing so, it is possible to increase the adsorption performance for anions and at the same time improve the performance of the zeolite. Cetyltrimethylammonium bromide (CTAB) is a cationic surfactant, and acts to increase the specific surface area by dispersing the crystal nuclei of hydroxyapatite so that the crystals of hydroxyapatite are distributed and formed small without agglomeration. In addition, cetyltrimethylammonium bromide (CTAB) is used as a structure indicator or template when forming zeolite to help form zeolite, and can also increase specific surface area. Cetyltrimethylammonium bromide (CTAB) is preferably used at a concentration of 10 to 100 mM.

When the alkaline metal hydroxide solution is mixed with fine slag powder and fine fly ash powder, a _geopolymer slurry is created. ₆ Si _10O43.28 ) zeolite or FAU zeolite. Since hydroxyapatite and zeolite change in the degree and type of synthesis depending on the pH, the pH is adjusted through an alkaline metal hydroxide solution. That is, in a low concentration alkaline solution (2 to 3M), Na-P1 (Na _5.92 Al ₆ Si _10O43.28 ) and FAU zeolite can be obtained, and in a high concentration alkaline solution (5M or more), a zeolite such as Sodalite zeolite can be obtained, A concentration of 2-3M to produce FAU zeolite and Na-P1 zeolite, which are evaluated to have the best adsorption capacity, is preferred. In addition, it was confirmed that 3M alkaline metal hydroxide solution was preferable to suppress the aggregation of hydroxyapatite and the formation of hydroxysodalite.

As the alkaline metal hydroxide solution, a sodium hydroxide solution or the like can be used. When potassium hydroxide is used as the alkaline metal hydroxide solution, it is preferable not to use a metal salt containing potassium ions because the ionization degree of potassium is higher than that of calcium, which interferes with the synthesis of hydroxyapatite.

Meanwhile, in synthesizing hydroxyapatite and zeolite, temperature and pressure conditions also have an important influence. The hydrothermal synthesis reaction temperature may be approximately 50 ~ 500 ℃, preferably 25 ~ 150 ℃. In addition, in order to increase the crystallinity of the synthetic material and to prevent evaporation of water, it is preferable to put it in a heat-resistant and pressure-resistant chamber such as an autoclave to cure it. In particular, at a temperature of 100°C or higher, it is essential to put it in a heat-resistant and pressure-resistant chamber to prevent water evaporation.

Next, a method for preparing the above-described hydroxyapatite-zeolite composite will be described in detail.

The method for preparing the hydroxyapatite-zeolite composite of the present invention includes the following steps.

(S1) mixing and stirring the slag fine powder and fly ash fine powder with the phosphoric acid solution

(S2) mixing cetyltrimethylammonium bromide (CTAB) and an alkaline metal hydroxide solution with the mixture made in step S1, and stirring while heating to a predetermined temperature

(S3) curing the mixture of step S2 by heating it for a certain period of time without stirring

In the step S1, the fine slag powder, the fine fly ash powder, and the phosphoric acid solution are stirred for 1 to 2 hours without heating to induce the elution of calcium ions. At this time, when stirring for more than 2 hours, the solution becomes jelly, so it is preferable that the stirring time does not exceed 2 hours.

In step S2, an alkaline metal hydroxide solution such as sodium hydroxide solution and cetyltrimethylammonium bromide (CTAB) are mixed with the mixture made in step S1, followed by stirring at a temperature of 90 to 120° C. for about 2 hours. At this time, the temperature must be maintained at 90 ~ 120 ℃ to manufacture a composite having a large specific surface area.

In step S3, stirring is stopped, and the mixture is sealed using an autoclave, etc., and cured at a temperature of 25 to 150° C. or less for 24 to 48 hours in a state where evaporation is maximally suppressed.

Example

25 g of fine slag powder, 5 g of fly ash, and a phosphoric acid solution (1.5 M, 100 ml) are mixed and stirred for 2 hours. At this time, the molar ratio of calcium/phosphorus is adjusted to 1.7 (step S1).

Then, 350 ml of a solution of sodium hydroxide (3M) and cetyltrimethylammonium bromide (CTAB) (0-100 mM) was mixed with the mixture of the slag fine powder and the phosphoric acid solution, and stirred at 100 ° C. for 2 hours to prepare a mixture ( step S2). At this time, five types of mixtures were prepared by varying the concentrations of cetyltrimethylammonium bromide (CTAB) to 0 mM, 30 mM, 50 mM, 70 mM, and 100 mM, respectively.

When stirring is complete, a mixture of the fine slag powder, fine fly ash powder, phosphoric acid solution, cetyltrimethylammonium bromide (CTAB), and sodium hydroxide solution is placed in an auto-clave chamber, and then 48 A hydrothermal synthesis reaction was performed by heating for a period of time (step S3).

after that, The prepared material was sufficiently washed and then filtered to obtain a hydroxyapatite-zeolite composite specimen.

As a result of performing X-ray diffraction analysis on the five composite specimens prepared in this way (see FIG. 1), hydroxyapatite and FAU zeolite were simultaneously synthesized, and as the concentration of cetyltrimethylammonium bromide (CTAB) increased, the crystallinity of hydroxyapatite increased. It can be seen that the decrease is due to the small dispersion of the crystals.

As described above, according to the present invention, hydroxyapatite with excellent anion adsorption performance and zeolite with excellent cation adsorption performance can be simultaneously synthesized by mixing a phosphoric acid solution and an alkaline metal hydroxide solution with fine industrial by-product slag powder and fly ash fine powder, Here, cetyltrimethylammonium bromide (CTAB) is mixed to disperse crystal nuclei of hydroxyapatite to inhibit crystal aggregation of hydroxyapatite, thereby increasing specific surface area to improve adsorption performance.

In the above, the present invention has been described in detail with reference to the embodiments, but those of ordinary skill in the art to which the present invention pertains may make various substitutions, additions and modifications within the scope not departing from the technical spirit described above. Of course, it will be understood that such modified embodiments also fall within the protection scope of the present invention as defined by the appended claims below.

Claims (7)

A hydroxyapatite-zeolite complex in which hydroxyapatite and zeolite are synthesized by mixing fine industrial by-product powder, phosphoric acid solution, cetyl trimethylammonium bromide (CTAB), and alkaline metal hydroxide solution. The hydroxyapatite-zeolite composite according to claim 1, wherein the fine powder of industrial by-products is made by using either fine fly ash powder or fine slag powder alone or by mixing fine fly ash powder and fine slag powder. The hydroxyapatite-zeolite composite according to claim 1, wherein the molar ratio of calcium (Ca)/phosphorus (P) is 1.3 to 1.7. A method for preparing the hydroxyapatite-zeolite composite according to any one of claims 1 to 3, comprising:
(S1) mixing and stirring the industrial by-product fine powder and phosphoric acid solution;
(S2) adding cetyltrimethylammonium bromide (CTAB) and an alkaline metal hydroxide solution to the mixture made in step S1, and stirring while heating to a predetermined temperature; and,
(S3) curing the mixture of step S2 by heating it for a predetermined time without stirring;
A method for producing a hydroxyapatite-zeolite composite comprising a. [Claim 5] The method of claim 4, wherein in step S1, elution of calcium ions is induced by stirring for 1 to 2 hours. [Claim 5] The method of claim 4, wherein the amount of the phosphoric acid solution is adjusted and mixed so that the molar ratio of calcium (Ca)/phosphorus (P) is 1.3 to 1.7 in step S1. The method of claim 6, wherein in step S2, the hydroxyapatite-zeolite composite is performed at a temperature of 90 to 120°C.

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