KR20190027661A - Chitosan-Gelatin Hydrogels for heavy metal adsorption and chitosan-gelatin hydrogels manufactured by the same method - Google Patents

Abstract

The present invention relates to a production method of a chitosan-gelatin hydrogel for heavy metal adsorption, and the hydrogel produced thereby. The production method can efficiently remove heavy metals harmful to the human body such as lead, cadmium, mercury, chromium and the like contained in contaminated wastewater by crosslinking chitosan and gelatin using a crosslinking agent. The production method of the present invention comprises: a first step of preparing a chitosan solution by adding chitosan with a weight average molecular weight of 100,000 to 200,000 to an acidic aqueous solution, and dispersing the chitosan in the acidic aqueous solution at room temperature for 1 to 24 hours; a second step of preparing a gelatin solution by adding gelatin with a weight average molecular weight of 100,000 to 200,000 to water, and dispersing the gelatin in water at the temperature of 20 to 50°C for 1 to 5 hours; a third step of mixing the chitosan solution with the gelatin solution to obtain a mixed solution; a fourth step of adding a crosslinking agent to the mixed solution to cross-link the chitosan and the gelatin; a fifth step of, after performing the fourth step, producing a hydrogel by separating a chitosan-gelatin complex prepared by cross-linking the mixed solution, and grinding the separated chitosan-gelatin complex; and a sixth step of washing the ground chitosan-gelatin complex so that the hydrogel has a pH value of 6 to 7.5, and freeze-drying the washed chitosan-gelatin complex for 24 to 72 hours in order to solidify the chitosan-gelatin complex.

Description

[0001] The present invention relates to a method for producing a chitosan-gelatin hydrogel for heavy metal adsorption and a hydrogel prepared thereby,

The present invention relates to a process for producing a chitosan-gelatin hydrogel for adsorbing heavy metals, and a hydrogel produced thereby, and more particularly, to a process for crosslinking chitosan and gelatin using a crosslinking agent to produce lead, cadmium, Gelatin hydrogel for heavy metal adsorption capable of efficiently removing heavy metals harmful to human body such as chromium, and a hydrogel produced by the method.

Generally used adsorbents for wastewater treatment are based on synthetic polymers and have excellent properties in terms of adsorption, economic efficiency, workability, etc. However, since they cause secondary pollution in the natural world without biodegradation, they cause toxicity to the living body especially cancer and mutation, Have a tendency to regulate their use.

Effective removal of toxic heavy metals from wastewater is very important. Heavy metal ions, even in trace amounts, are toxic and do not decompose, causing serious environmental problems. Numerous studies have been conducted to remove these toxic heavy metals. Examples are filtration, chemical precipitation, membrane separation, ion exchange, and adsorption. Filtration is inexpensive and is effective in partially removing heavy metal ions, and chemical precipitation can also remove large amounts of metal ions at low cost, but this method can remove trace levels of heavy metal ions none. Membrane separation can remove very low concentrations of heavy metal ions, but the system is complex, costly, and requires specialized handling techniques. Ion exchange can separate extremely low metal ions, but it is very inefficient because it can contain large amounts of monovalent or divalent ions such as sodium and calcium.

Therefore, it is necessary to develop a new solid adsorbent using natural materials which can efficiently remove low concentration heavy metal ions from wastewater.

KR 10-2006-0126081 A KR 10-2007-0076742 A KR 10-2013-0055847 A

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a method for efficiently removing heavy metals harmful to human bodies such as lead, cadmium, A method for producing a chitosan-gelatin hydrogel for adsorbing heavy metals excellent in adsorption performance, and a hydrogel prepared thereby.

Meanwhile, the object of the present invention is not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood from the following description.

In order to accomplish the above object, the present invention provides a method for preparing a chitosan-gelatin hydrogel for adsorbing heavy metals, which comprises adding chitosan having a weight average molecular weight of 100,000 to 200,000 to an acidic aqueous solution and dispersing at room temperature for 1 to 24 hours to prepare a chitosan solution ; A second step of adding a gelatin having a weight average molecular weight of 100,000 to 200,000 to water and dispersing at 20 to 50 ° C for 1 to 5 hours to prepare a gelatin solution; A third step of mixing the chitosan solution and the gelatin solution; A fourth step of cross-linking the chitosan and gelatin by adding a cross-linking agent to the mixed solution; Separating and pulverizing the cross-linked chitosan-gelatin complex from the mixed solution after the fourth step to produce a hydrogel; And a sixth step of washing the hydrogel such that the pH of the hydrogel is 6 to 7.5 and lyophilizing for 24 to 72 hours to solidify the solution.

The chitosan-gelatin hydrogel for adsorbing heavy metals according to the present invention is prepared by adding chitosan having a weight average molecular weight of 100,000 to 200,000 to an acidic aqueous solution and then dispersing the mixture at room temperature for 1 to 24 hours to prepare a chitosan solution having a weight average molecular weight of 100,000 to 200,000 Gelatin is dispersed in a hydrophilic solvent at 20 to 50 DEG C for 1 to 5 hours to prepare a gelatin solution, the chitosan solution and the gelatin solution are mixed, and the cross-linking agent is added to the mixed solution to form the chitosan and gelatin Gelatin complex is separated from the mixed solution and is pulverized to prepare a hydrogel. After the hydrogel is washed to a pH of 6 to 7.5, the hydrogel is washed for 24 to 72 hours, ≪ / RTI > for a period of time.

According to the solution of the above problems, the process for producing a chitosan-gelatin hydrogel for adsorbing heavy metals of the present invention and the hydrogel produced by using the chitosan and gelatin enriched in nature are excellent in the binding stability between chitosan and gelatin, There is an effect that it can be used as a natural adsorbent having excellent heavy metal adsorption performance in wastewater.

In addition, since the chitosan-gelatin hydrogel can swell adequately in water, heavy metals in the wastewater can be adsorbed, thereby effectively removing heavy metal ions in the wastewater.

1 is a schematic view illustrating a method for producing a chitosan-gelatin hydrogel for heavy metal adsorption according to an embodiment of the present invention.
FIG. 2 is a schematic view illustrating swelling of a chitosan-gelatin hydrogel prepared according to an embodiment of the present invention in water.
3 is an electron micrograph of a chitosan-gelatin hydrogel prepared according to an embodiment of the present invention.
FIG. 4 is a schematic view illustrating a method for testing heavy metals adsorption capacity of a chitosan-gelatin hydrogel prepared according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments described below, but may be embodied in various different forms, and these embodiments are not intended to be exhaustive or to limit the scope of the present invention to the precise form disclosed, It is provided to inform the person completely of the scope of the invention. And the terminology used herein is for the purpose of illustrating embodiments and is not intended to be limiting of the present invention. The singular forms herein include plural forms unless the context clearly dictates otherwise.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Brief Description of Drawings FIG. 1 is a block diagram of a computer system according to an embodiment of the present invention; FIG. 2 is a block diagram of a computer system according to an embodiment of the present invention; FIG.

1 is a schematic view illustrating a method for producing a chitosan-gelatin hydrogel for heavy metal adsorption according to an embodiment of the present invention.

1, a method for producing a chitosan-gelatin hydrogel for adsorbing heavy metals according to the present invention will be described below.

The method for preparing a chitosan-gelatin hydrogel for adsorbing heavy metals according to the present invention comprises a first step of preparing a chitosan solution, a second step of preparing a gelatin solution, a third step of mixing the solutions, a fourth step of adding a crosslinking agent , A fifth step of preparing a hydrogel, and a sixth step of solidifying the same.

In the first step, chitosan having a weight average molecular weight of 100,000 to 200,000 is added to an acidic aqueous solution and dispersed at room temperature for 1 to 24 hours to prepare a chitosan solution.

Chitosan is a natural polymer substance deacetylated by treatment of chitin, which exists in shells of crabs and shrimps, with high temperature and strong alkali, and has free amino groups in the molecule. Therefore, chemical, medical and food industries And so on. Chitosan has a much higher separation than synthetic chelate resins and has a high adsorption capacity and is expected to be a very heavy metal adsorbent in aqueous solution. Chitosan is known as an excellent natural chelating polymer in itself, but it can be used as an effective heavy metal adsorbent with a stable structure by making polymer matrix that is more structurally stable than chemical agent, acid or high temperature condition.

Specifically, in the first step, 1 to 5 parts by weight of chitosan is mixed with 100 parts by weight of 0.1 to 1.0 moles of acetic acid solution as an acidic aqueous solution, and stirring the mixed solution of chitosan at room temperature for 1 to 24 hours . ≪ / RTI >

In the second step, gelatin having a weight average molecular weight of 100,000 to 200,000 is added to water and dispersed at 20 to 50 ° C for 1 to 5 hours to prepare a gelatin solution. Here, the water which can be used in the present invention means deionized water, distilled water or purified water, preferably distilled water.

Gelatin is a natural polymer in which the triple helical structure of collagen is transformed into a single helical form. Gelatin is classified into two types, gelatin A and gelatin B, depending on the treatment method. Gelatin A is prepared by acid treatment and gelatin B is prepared by base treatment. Because of its biocompatibility and ease of processing, gelatin has been used in various fields such as cosmetics, biotissues, adsorbents and the like. The gelatin-processed workpiece has advantages such as absorbency and adhesion, but has a weak mechanical strength. In the present invention, the disadvantages of gelatin having weak mechanical strength are solved by reacting chitosan with gelatin.

Specifically, gelatin is preferably added in an amount of 5 to 15 parts by weight based on 100 parts by weight of water.

In the third step, the chitosan solution and the gelatin solution are mixed.

At this time, the chitosan and the gelatin are basic polymers for retaining the skeleton of the hydrogel according to the present invention, and the chitosan solution and the gelatin solution are mixed at a weight ratio of 1: 9 to 5: 5, preferably 1: 3 .

Then, the mixture is stirred for 1 to 5 hours to sufficiently mix the chitosan solution and the gelatin solution.

In the fourth step, the cross-linking agent is added to the mixed solution to cross-link the chitosan and the gelatin.

Specifically, in the fourth step, the chitosan and gelatin of the mixed solution are crosslinked at a temperature of 20 to 60 DEG C at a rate of 100 to 500 rpm. The crosslinking agent is preferably added in an amount of 0.01 to 0.1 part by weight based on 100 parts by weight of the mixed solution, and is preferably sufficiently reacted for 1 to 24 hours.

The crosslinking agent according to one embodiment of the present invention may be selected from the group consisting of epichlorohydrine, glutaraldehyde, chloromethyl oxirane, acrylic acid, Methacrylamide, a mixture thereof, and the like.

In the fifth step, after the fourth step, the cross-linked chitosan-gelatin complex is separated from the mixed solution and pulverized to prepare a hydrogel.

The fifth step is a step of adjusting the size of the hydrogel according to the use environment, and the hydrogel may be pulverized to a diameter of 5 to 100 탆, and preferably 20 to 45 탆.

In the sixth step, the hydrogel is washed to a pH of 6 to 7.5, and lyophilized for 24 to 72 hours to solidify.

Meanwhile, the chitosan-gelatin hydrogel for adsorbing heavy metals according to the present invention is prepared by adding chitosan having a weight average molecular weight of 100,000 to 200,000 to an acidic aqueous solution and dispersing at room temperature for 1 to 24 hours to prepare a chitosan solution, 200,000 gelatin is added to a hydrophilic solvent and dispersed at a temperature of 20 to 50 ° C for 1 to 5 hours to prepare a gelatin solution. The chitosan solution and the gelatin solution are mixed, and the cross-linking agent is added to the mixed solution, After the fourth step, the cross-linked chitosan-gelatin complex is separated and pulverized to prepare a hydrogel. The hydrogel is washed to a pH of 6 to 7.5, And lyophilized and solidified for 72 hours.

2 is an electron micrograph of a chitosan-gelatin hydrogel prepared according to an embodiment of the present invention, wherein a is 30 times and b is 50 times magnification.

2, according to an embodiment of the present invention, gelatin and chitosan are cross-linked by a cross-linking agent and chitosan-gelatin hydrogel having good binding stability between chitosan and gelatin is produced.

A specific description of the chitosan-gelatin hydrogel is the same as that described in the above-described method for producing a chitosan-gelatin hydrogel.

Hereinafter, the present invention will be described in more detail by way of examples, but the scope of the present invention is not limited by the practice.

< Example >

1. Chitosan-Gelatin Hydrogel  Produce

Example  One

3 parts by weight of chitosan was added to 0.1 M acetic acid aqueous solution and stirred at room temperature for 24 hours to prepare a yellow chitosan solution. 10 parts by weight of gelatin was added to distilled water at 40 캜 and stirred to prepare a gelatin solution.

The chitosan solution and the gelatin solution were mixed and stirred for 2 hours, and then 1 part by weight of glutaraldehyde as a cross-linking agent was added. After the chitosan and gelatin were sufficiently crosslinked, the crosslinked chitosan-gelatin complex was separated from the mixture and pulverized by a pulverizer to prepare a chitosan-gelatin hydrogel.

Then, the solution was washed with distilled water until the pH of the chitosan-gelatin hydrogel reached 7 to remove acetic acid and excess glutaraldehyde, lyophilized for 72 hours, and further polished to obtain chitosan-gelatin hydrogel particles having a diameter of 45 μm .

Comparative Example  One

The chitosan-gelatin hydrogel was prepared in the same manner as in Example 1, except that it was vacuum-dried at 40 占 폚 for 24 hours.

< Experimental Example >

1. Results of swelling test

The degree of swelling of the chitosan-gelatin hydrogel prepared according to Example 1 and Comparative Example 1 was calculated and compared.

FIG. 3 is a schematic view showing swelling of a chitosan-gelatin hydrogel prepared according to an embodiment of the present invention in water.

Referring to FIG. 3, when the chitosan-gelatin hydrogel is immersed in water, a volume change occurs. The functional groups of the chitosan-gelatin hydrogel absorb water by the capillary force and induce expansion pressure to the outside, thereby inducing volume increase.

The degree of swelling (DS) can be calculated from the following equation.

In the above formula, DS means the degree of swelling, W _w the mass (g) of the chitosan-gelatin hydrogel in the hydrated state, and W _d the mass (g) of the dry chitosan-gelatin hydrogel.

In Comparative Example 1, the DS was 500 to 700%, and the shape memory property maintaining the original shape even after repeating 25 cycles of rapid expansion / dehydration was exhibited. In Example 1, More than 8,000% were observed.

2. Chitosan-Gelatin The hydrogel  Experimental results of heavy metals adsorption

FIG. 4 is a schematic view illustrating a method for testing heavy metals adsorption capacity of a chitosan-gelatin hydrogel prepared according to an embodiment of the present invention.

4, an aqueous solution containing heavy metal ions and a chitosan-gelatin hydrogel prepared according to Example 1 were put into a round bottom flask and stirred at a rate of 30 to 100 rpm at room temperature for 24 hours , And the mixture was filtered through a syringe-type cellulose membrane having a pore size of 0.2 mu m (ASTM D4646). At this time, the aqueous solution containing heavy metal ions was prepared by using heavy metal salts of HgCl ₂ , PbCl ₂ , CdCl ₂ and CrCl ₃ .

The filtered solution was analyzed using an inductively coupled plasma-optical emission spectrometer (ICP-OES) for metal ion detection (ASTM D1971-11). The concentration of the solute remaining in the solution is measured and the amount of solute adsorbed is known by the partition coefficient. The partition coefficient represents the ratio of the concentration of solute adsorbed on the chitosan-gelatin hydrogel divided by the concentration of the solution, which is useful in determining the 24 hour K _d value for the non-volatile organic component. This method is not suitable for volatile components, and the limit of the adsorption time for 24 hours in Experimental Example 1 was sufficient to reach the steady state K _d .

The partition coefficient can be calculated by the following equation.

In the above equation, K _d is the partition coefficient (mL / g), A is the initial concentration of solute (/ / mL) defined as the mean concentration of the blank, B is the final concentration of the solute after 24 hours in contact with the hydrogel ㎍ / mL), V is the volume of the used solution (mL), M _s denotes the mass (g) of the hydrogel represented by the oven drying.

The performance of each heavy metal salt for heavy metal ion adsorption is shown in Table 1 below.

division Heavy metal salt Heavy metal solution (mg / L) Metal ion
Adsorption (mg / g) K _d (mL / g) One PbCl ₂ 802 27.2 51.3 2 HgCl ₂ 824 81.1 6240 3 CdCl ₂ 497 10.1 25.5 4 CrCl ₃ 184 3.0 19.5 5
mix Pb (II) 327
Hg (II) 349
Cd (II) 254
Cr (III) 88 Pb (II) 3.9
Hg (II) 33.8
Cd (II) 0.5
Cr (III) 2.1 Pb (II) 13.5
Hg (II) 3070
Cd (II) 2.01
Cr (III) 31.3

(II), 81.1 mg / g of Hg (II), 10.1 mg / g of Cd (II) and 3.0 mg / g of Cr (III) were added to the chitosan-gelatin hydrogel Adsorption performance can be confirmed.

The K _d values obtained by assuming the 24 hour adsorption equilibrium showed the highest values of Hg (Ⅱ) ion and the highest selectivity in heavy metal mixed solution.

The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the claims of the invention to be described below may be better understood. It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the foregoing detailed description, and all changes or modifications derived from the appended claims and their equivalents should be construed as being included within the scope of the present invention.

Claims (5)

A first step of adding chitosan having a weight average molecular weight of 100,000 to 200,000 to an acidic aqueous solution and dispersing at room temperature for 1 to 24 hours to prepare a chitosan solution;
A second step of adding a gelatin having a weight average molecular weight of 100,000 to 200,000 to water and dispersing at 20 to 50 ° C for 1 to 5 hours to prepare a gelatin solution;
A third step of mixing the chitosan solution and the gelatin solution;
A fourth step of cross-linking the chitosan and gelatin by adding a cross-linking agent to the mixed solution;
Separating and pulverizing the cross-linked chitosan-gelatin complex from the mixed solution after the fourth step to produce a hydrogel; And
Washing the hydrogel to a pH of 6 to 7.5, and lyophilizing it for 24 to 72 hours to solidify the solution;
Wherein the chitosan-gelatin hydrogel is adsorbed on the surface of the chitosan-gelatin hydrogel. The method according to claim 1,
In the third step
Wherein the chitosan solution and the gelatin solution are mixed at a weight ratio of 1: 9 to 5: 5. The method according to claim 1,
Wherein the chitosan and gelatin of the mixed solution are crosslinked at 20 to 60 ° C at a rate of 100 to 500 rpm in the fourth step. The method according to claim 1,
Wherein the hydrogel is pulverized to a diameter of 5 to 100 mu m in the fifth step. Chitosan having a weight average molecular weight of 100,000 to 200,000 is added to an acidic aqueous solution and dispersed at room temperature for 1 to 24 hours to prepare a chitosan solution,
Gelatin having a weight average molecular weight of 100,000 to 200,000 is added to a hydrophilic solvent and dispersed at 20 to 50 ° C for 1 to 5 hours to prepare a gelatin solution,
The chitosan solution and the gelatin solution were mixed,
A crosslinking agent is added to the mixed solution to cross-link the chitosan and the gelatin,
After the fourth step, the cross-linked chitosan-gelatin complex is separated from the mixed solution and pulverized to prepare a hydrogel,
The hydrogel is washed at a pH of 6 to 7.5, and then lyophilized for 24 to 72 hours to solidify the chitosan-gelatin hydrogel.

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