KR101465841B1 - Synthesis of poly-N-phenylglycine nanofibers and application thereof - Google Patents

Abstract

The present invention relates to the synthesis of poly-N-phenylglycine nanofibers, their application as metal adsorbents, and the synthesis of poly-N-phenylglycine nanofibers / metal oxide nanoparticles complexes and their application as metal adsorbents.

Description

Synthesis of poly-N-phenylglycine nanofibers and application thereof < RTI ID = 0.0 >

The present invention relates to the synthesis of poly-N-phenylglycine nanofibers and their applications, and more particularly to the synthesis of poly-N-phenylglycine nanofibers, their application as metal adsorbents, Fiber / metal oxide nanoparticles and their application as metal adsorbents.

One of the most important challenges in the current generation is the disposal of waste from industrial processes. In particular, water is an essential liquid for all life forms. Special attention should be paid to the heavy metals contained in the contaminated water, because they are highly toxic to humans and the environment despite very dilute concentrations.

As a technique for removing water pollutants, adsorption, precipitation, membrane separation, and ion exchange are mainly used. Among them, removal by adsorption is known to economically and effectively remove pollutants in water as compared with other methods, wherein the removal efficiency depends on the affinity of the target contaminant and the adsorbent.

Carbon is one of the adsorbents widely used to remove various pollutants such as heavy metals in water. Many previous studies have investigated that various types of carbon and carbon composites have adsorption effects. Graphene is the most recently known carbon isotope and has a large surface area. Particularly graphene oxide is considered as an attractive adsorbent candidate for water purification due to functional groups such as epoxy groups, hydroxyl groups and carboxyl groups present on the surface. However, it is difficult to synthesize graphene oxide, and there is a problem in the practical application of the solution such as sulfuric acid used in the synthesis process.

On the other hand, materials such as iron oxide can be used for adsorption of heavy metals in water, however, when they are manufactured with a small particle size in order to widen the surface area, they easily disappear from the water.

Korean Patent No. 10-1040293

Disclosure of the Invention The present invention has been conceived to solve the above-mentioned problems, and it is an object of the present invention to provide a method of synthesizing a poly-N-phenylglycine nanofiber and a composite of poly- N-phenylglycine nanofiber and metal oxide nanoparticles by a simple method, And as a useful water purification material.

According to an aspect of the present invention, there is provided a metal adsorbent.

The adsorbent comprises poly-N-phenylglycine nanofibers. In addition, the adsorbent may have a nano-web structure in which the nanofibers are entangled with each other.

According to another aspect of the present invention, there is provided an organic-inorganic hybrid material.

Wherein said complex comprises poly-N-phenylglycine nanofibers; And metal oxide nanoparticles bonded to the nanofibers.

The metal of the metal oxide nanoparticles may be at least one selected from the group consisting of iron, aluminum, manganese, and two or more alloys thereof.

In addition, the composite may have a nano-web structure in which the nanofibers are entangled with each other.

The above-mentioned organic-inorganic hybrid substance can be used as a metal adsorbent.

According to another aspect of the present invention, there is provided a method for manufacturing a nonaqueous-based composite material.

The method comprises: preparing a mixture of an N-phenylglycine monomer, an amine-based reaction promoter and metal oxide nanoparticles; Adding the mixture to an acid solution containing an oxidizing agent to form a polymerization reaction product; And polymerizing the N-phenylglycine monomer of the polymerization reaction to form poly-N-phenylglycine nanofiber and metal oxide nanoparticles bound to the nanofiber.

The metal of the metal oxide nanoparticles may be at least one selected from the group consisting of iron, aluminum, manganese, and two or more alloys thereof.

In addition, the method for preparing the organic-inorganic hybrid material may further include a step of treating the obtained composite with a basic solution to dedoping the poly-N-phenylglycine nanofiber.

According to the present invention, it is possible to produce a composite of poly-N-phenylglycine nanofiber and poly-N-phenylglycine nanofibers / metal oxide nanoparticles by a simple and economical method. In addition, since the material produced in the present invention contains a high specific surface area and a large number of carboxyl groups, it can be usefully used as a metal adsorbent in contaminated water such as wastewater. Particularly, the composite of poly-N-phenylglycine nanofibers and metal oxide nanoparticles can be easily recovered by using a magnet after adsorption of metal in water, and thus the recovery efficiency is also excellent.

However, the effects of the present invention are not limited to the above-mentioned effects, and other effects not mentioned can be clearly understood by those skilled in the art from the following description.

1 is an SEM image of a product according to Preparation Example 1. Fig.
2 is the UV-Vis spectrum of the product according to Preparation Example 1.
3 is an infrared spectrum (IR) of the product according to Preparation Example 1. Fig.
4 is a TEM image (a) and a SEM image (b) of a product according to Production Example 2. Fig.
Fig. 5 is a photograph of the state of the product obtained in Production Example 2, taken in water and taken with a magnet. Fig.
6 is an SEM image (a) and a TEM image (b) of copper particles adsorbed on poly-N-phenylglycine nanofibers.
7A and 7B are UV-Vis spectra measured after removal of copper according to Experimental Examples 1 and 2. FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It is to be understood, however, that the present invention is not limited to the embodiments described herein but may be embodied in other forms and includes all equivalents and alternatives falling within the spirit and scope of the present invention.

The singular expressions herein include plural expressions unless the context clearly dictates otherwise. It is also to be understood that the terms such as " comprises "or" having "are intended to specify the presence of stated features, integers, Or < / RTI > combinations thereof.

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

Example  One

According to one embodiment of the present invention, there is provided a metal adsorbent comprising poly-N-phenylglycine nanofibers.

The poly-N-phenylglycine is a polymer having a structure represented by the following formula (1), and can be formed by polymerization of an N-phenylglycine monomer.

≪ Formula 1 >

Specifically, the poly-N-phenylglycine nanofiber may be prepared by reacting an N-phenylglycine monomer with an oxidizing agent in an acid solution. In order to lower the oxidation potential and accelerate the reaction during the reaction, an amine-based reaction promoter may be added. The reaction promoter may be, for example, a diamine such as N-phenyl-1,4-phenylenediamine or p-phenylenediamine.

The oxidizing agent is selected from the group consisting of ammonium persulfate (NH ₄ ) ₂ S ₂ O ₈ , potassium dichromate (K ₂ Cr ₂ O ₇ ), chloroauric acid (HAuCl ₄ ), iron chloride (III) chloride (FeCl ₃ ), copper (Ⅱ) perchlorate, Cu (ClO ₄ ) ₂ ) and ferric perchlorate (Fe (ClO ₄ ) ₃ ) And preferably ammonium persulfate can be used. The oxidizing agent may be used in an amount of 0.1 to 0.5 mol based on 1 mol of N-phenylglycine.

The acid can be used various inorganic or organic acid, such as hydrochloric acid (HCl), sulfuric acid (H ₂ SO _4), nitric acid (HNO _3), perchloric acid (HClO _4), phosphoric acid (H ₃ PO _4), phosphonic acids ( H ₃ PO ₃ , CSA (camphosulfonic acid), p-toluenesulfonic acid, trichloroacetic acid and trifluoroacetic acid.

As shown in Formula 1, the poly-N-phenylglycine includes a carboxyl group per unit of the N-phenylglycine monomer. The oxygen of the carboxyl group can be bonded to the metal ion by an electrostatic approach by means of a non-covalent electron pair, through which various metal ions including heavy metals in the wastewater can be adsorbed and removed. The poly-N-phenylglycine can be produced in the form of a nanofiber having a one-dimensional structure and has a high specific surface area, so that the contact with the metal is very advantageous. Thus, the poly-N-phenylglycine nanofibers have characteristics very suitable for use as a metal adsorbent.

On the other hand, the metal adsorbent containing poly-N-phenylglycine nanofibers may have a nano-web structure in which the nanofibers are entangled with each other. Such a structure can be formed by aggregating nanofibers in a process of separating and drying polymerized poly-N-phenylglycine nanofibers. Since the web structure of nanofibers has many pores and high non - target, it can be useful for adsorption of heavy metals in heavy water.

Example  2

According to another embodiment of the present invention, there is provided an organic-inorganic hybrid material comprising poly-N-phenylglycine nanofiber and metal oxide nanoparticles bonded to the nanofiber.

Wherein the organic / inorganic hybrid material is prepared by preparing a mixture of an N-phenylglycine monomer, an amine-based reaction promoter and metal oxide nanoparticles; Adding the mixture to an acid solution containing an oxidizing agent to form a polymerization reaction product; And polymerizing the N-phenylglycine monomer of the polymerization reaction to form poly-N-phenylglycine nanofibers and metal oxide nanoparticles bound to the nanofibers.

The amine-based reaction accelerator, the oxidizing agent and the acid are as described in Example 1. [

The metal of the metal oxide nanoparticles may include at least one selected from the group consisting of iron, aluminum, manganese, and two or more alloys thereof.

The metal oxide nanoparticles present in the polymerization reaction may be bound to the nanofibers in the form of being introduced or adhered to the poly-N-phenylglycine nanofibers produced in the polymerization of the N-phenylglycine monomer. These metal oxide nanoparticles have their own metal adsorption ability and can also enhance the electronegative property of the oxygen functional group contained in the carboxyl group of poly-N-phenylglycine. Accordingly, the organic-inorganic hybrid material including the poly-N-phenylglycine nanofiber and the metal oxide nanoparticles bonded thereto can have a further improved metal adsorption ability.

Particularly, when iron oxide is used as the metal oxide, the organic / inorganic hybrid material can be magnetized. When the organic-inorganic hybrid material to which magnetism is imparted is used as a metal adsorbent, the adsorbent can be easily recovered using a magnet after adsorption of the metal in the water. Also, if the adsorbed metal is removed and reused through proper aftertreatment of the recovered adsorbent, economical efficiency can be improved.

Meanwhile, the method for preparing the organic-inorganic hybrid material may further include a step of treating the obtained composite with a basic solution to dedoping the poly-N-phenylglycine nanofiber. In this case, hydrogen of the carboxyl group in the poly-N-phenylglycine can be removed to form the carboxyl anion, so that the adsorption ability to the metal can be improved.

Hereinafter, preferred examples for the understanding of the present invention will be described. It should be understood, however, that the following examples are intended to aid in the understanding of the present invention and are not intended to limit the scope of the present invention.

<Production Example 1: poly - N - phenylglycine (PPG) producing a nanofiber>

1 mmol of N - polyglycine ( N - PG) and N - phenyl - 1, 4 - phenylene - diamine corresponding to 5 mol% thereof were dissolved in 10 ml of 2 - propanol. 0.25 mmol ammonium persulfate (APS) was dissolved in 10 ml of 1 M HCl and the two solutions were mixed. The reaction was carried out at room temperature for 2 days and then centrifuged at 3000 rpm for 30 minutes to obtain poly- N -phenylglycine (PPG) nanofiber. The product was separated, dedoped with 1M KOH and dried in an oven at 60 ° C to form a powder.

Preparation Example 2: Preparation of poly- N -phenylglycine (PPG) nanofiber / iron oxide (IO)

First, iron oxide (Fe ₃ O ₄ ) was synthesized by the following procedure. 0.99 g of FeCl ₂ .H ₂ O (5 mmol) and 1.63 g of FeCl ₃ .H ₂ O (6 mmol) were dissolved in 5 ml of H ₂ O, respectively, and the two solutions were mixed. 200 ml of a 0.6M ammonium solution was slowly added dropwise to the mixture for 20 minutes while stirring. Ammonium hydroxide solution was added thereto to adjust the pH to 11-12. The product was separated by centrifugation at 2800 rpm for 10 minutes, washed three times each with H ₂ O and tetrahydrofuran (THF), and dried in air.

A diamine, and N -PG weight and 10ml 0.1M HCl gave after this change with the iron oxide of the same weight for the 1mmol - N -PG 1mmol and N corresponding to its 5% mol - phenyl-1,4-phenylene Melted. 0.25 mmol of APS was dissolved in 0.1 M HCl, and the two solutions were mixed and reacted at room temperature for 2 days. The product was separated by centrifugation at 3000 rpm for 30 minutes and then washed with 0.1 M HCl and H ₂ O to obtain a PPG / IO complex. The complex was dried in an oven at 60 ° C to form a powder.

& Lt; Analysis Example 1: Confirmation of morphology of PPG nanofibers >

As the reaction proceeds in Production Example 1 to produce PPG nanofibers, the solution turned green.

Further, the morphology of the product according to Production Example 1 was confirmed using a scanning electron microscope (SEM). As shown in the SEM image of FIG. 1, it was confirmed that a nanofiber web structure in which PPG nanofibers having a diameter of about 50 to 100 nm was intertwined in a net shape was formed.

<Analysis Example 2: Spectroscopic Analysis of PPG Nanofibers>

2 shows the UV-Vis spectrum of the PPG nanofibers prepared in Production Example 1. FIG. The absorption bands of the doped PPG nanofibers appeared at 310 nm, 380 nm and 750 nm. The peak at 310 nm corresponds to? -Π * electron transition, and the peak at 380 nm and 750 nm is expected to be a polaron band. The absorption bands of dedoping PPG nanofibers appeared at 325 nm and 620 nm.

Fig. 3 shows an infrared spectrum (IR) of the PPG nanofiber prepared in Production Example 1. Fig. A main peak 1558cm ^- the stretching vibration caused by the quinoid (quinoid) and benje cannabinoid (benzenoid) observed at ¹ and 1492cm ^-1 is, the stretching vibration of secondary aromatic amine (secondary aromatic amine) 1248cm ^-1 are observed in the. The 813 cm ^-1 peak corresponds to the absorption band in the para-benzene ring. On the other hand, PPG has a weak peak at 1674 cm ^-1 derived from a carbonyl group, and a peak widely distributed around 3000 cm ^-1 is derived from a hydroxyl group. Two peaks at 1674 cm ^-1 and 3000 cm ^-1 indicate the presence of a carboxyl group.

&Lt; Analysis Example 3: Morphology Analysis and Magnetic Characterization of PPG / IO Complex >

The morphology of the PPG nanofiber / IO nanoparticle composite prepared in Preparation Example 2 was confirmed by using a transmission electron microscope (TEM) and a scanning electron microscope (SEM).

4 is a TEM image (a) and a SEM image (b) of a product according to Production Example 2. Fig.

As shown in FIG. 4, iron oxide nanoparticles are bonded to PPG nanofibers and synthesized. The size of the iron oxide nanoparticles is about 12 nm, which is the most efficient for adsorbing metals.

5 is a photograph of a state when a magnet is taken in a PPG / IO complex contained in water. You can see that the PPG / IO complex is pulled towards the magnet, which means that the PPG / IO complex is magnetic. Therefore, even when the environment in which the PPG / IO composite is used is a liquid phase, the PPG / IO complex can be easily separated and recovered using only the magnet as shown in Fig.

EXPERIMENTAL EXAMPLE 1: Removal of Copper Using PPG &gt;

Chloride, copper (Ⅱ) aqueous solution of ^{2.5 × 10 -2, 5.0 × 10} -2, 1.0 × 10 -1, 3.0 × 10 ^-1, and was placed in a 5.0 × 10 ^-1 mM concentration. PPG of 0.02 wt% of the total solution weight was added thereto, and the mixture was stirred at room temperature for 12 hours. Each sample was centrifuged and the supernatant was collected and filtered using a 0.45 μm syringe filter. The absorbance of the solution was measured by UV-Vis spectroscopy to calculate the residual copper concentration after copper removal. Acetaldehyde-bis (cyclohexanone) oxaldihydrazone (BCO) method was used to measure the absorbance of copper on the UV-Vis spectrum.

The BCO method involves the addition of 0.7 ml triammonium citrate solution (solution in which 10 g triammonium citrate is dissolved in 50 ml H ₂ O), 0.5 ml NH ₃ -NH ₄ Cl buffer (2 ml NH ₃ and 2 g NH ₄ Cl, dissolved in 50ml H ₂ O), 40% acetaldehyde solution of 0.1ml, 1.1ml BCO solution (after mixing a solution prepared by dissolving a 0.1g BCO in 25ml H ₂ O and 25ml of methanol) and 2.1ml H ₂ O, 0.5 ml of a copper aqueous solution was added, and the absorbance at 542 nm was measured after 10 minutes.

Experimental Example 2: Removal of copper using PPG / IO complex [

Except that PPG / IO complex was used as a copper removal material when copper (II) chloride aqueous solution was prepared at concentrations of 2.5 × 10 ^-2 , 5.0 × 10 ^-2 , 1.0 × 10 ^-1 , 5.0 × 10 ^-1 and 1.0 mM The same procedure as in Experimental Example 1 was carried out.

<Analysis Example 4: PPG / Cu morphology analysis>

The oxygen functional groups can adsorb metals through electrostatic attraction with various metals. PPG can predict the adsorption of excellent metals because it has one carboxyl group containing oxygen per monomer.

6 is an SEM image (a) and a TEM image (b) of copper particles (PPG / Cu) adsorbed on PPG nanofibers. As shown in Fig. 6, it can be confirmed that the copper particles are adsorbed on the PPG nanofibers.

&Lt; Analysis Example 5: Spectroscopic analysis and removal rate analysis after copper removal >

The UV-Vis spectra after removal of copper according to Experimental Examples 1 and 2 are shown in FIGS. 7a and 7b. The concentration of copper remaining in the solution was calculated on the basis of the Beer-Lambert law (Equation 1) through the absorbance in the UV-Vis spectrum.

A = epsilon &lt; RTI ID = 0.0 &gt;

(ε: molar extinction coefficient, c: concentration of sample, ℓ: optical path length)

The calculation results are shown in Tables 1 and 2 below. Table 1 shows the post-removal concentration and removal rate for the initial concentration of copper by PPG, and Table 2 shows the post-removal concentration and removal rate for the initial copper concentration by PPG / IO.

Copper
Initial concentration (mM) Copper
Concentration after removal (mM) Removal rate (%) Q _e (mmol / g) K _d 2.5 x 10 ^-2 2.92 × 10 ^-4 98.83 0.12 422.71 5.0 x 10 ^-2 8.03 × 10 ^-4 98.39 0.25 306.45 1.0 x 10 ^-1 1.89 x 10 ^-3 98.11 0.49 260.21 3.0 x 10 ^-1 1.49 x 10 ^-2 95.02 1.43 95.46 5.0 x 10 ^-1 3.37 x 10 ^-2 93.26 2.33 69.22

Copper
Initial concentration (mM) Copper
Concentration after removal (mM) Removal rate (%) Q _e (mmol / g) K _d 2.5 x 10 ^-2 1.66 x 10 ^-4 99.34 0.12 746.97 5.0 x 10 ^-2 8.55 × 10 ^-4 98.29 0.25 286.98 1.0 x 10 ^-1 3.16 x 10 ^-3 96.84 0.48 152.87 5.0 x 10 ^-1 2.81 × 10 ^-2 94.39 2.36 83.84 1.0 6.16 x 10 ^-2 93.80 4.69 76.03

Referring to Tables 1 and 2, it can be seen that when copper is removed using PPG and PPG / IO as an adsorbent at a low concentration, the removal rate is about 99%. As a result of the calculation of the K _d (distribution coefficient) indicating the degree of adsorption per g of the adsorbent (Equation 2, 3), the result was as high as 422.71 when using PPG and 746.97 when using PPG / IO.

(C ₀ : concentration of initial copper before removal, C _e : concentration of copper remaining after removal, V: volume of aqueous solution, m: weight of adsorbent (PPG, PPG / IO)

The removal rate of copper in PPG / IO is higher than the removal rate of PPG because the iron oxide (IO) binds to PPG, resulting in stronger electronegative property of the oxygen group contained in the carboxyl group, It is expected to be the result.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, Change is possible.

Claims (10)

Poly-N-phenylglycine nanofiber,
Wherein the poly-N-phenylglycine has a carboxyl anion,
Wherein the carboxyl anion electrostatically adsorbs metal cations. The method according to claim 1,
Wherein the adsorbent has a nano-web structure in which the nanofibers are entangled with each other. Poly-N-phenylglycine nanofibers; And
And metal oxide nanoparticles bonded to the nanofibers,
Wherein the poly-N-phenylglycine has a carboxyl anion,
Wherein the carboxyl anion electrostatically adsorbs metal cations. The method of claim 3,
Wherein the metal of the metal oxide nanoparticles comprises at least one selected from the group consisting of iron, aluminum, manganese, and two or more of these alloys. The method of claim 3,
Wherein the composite has a nano-web structure in which the nanofibers are entangled with each other. Preparing a mixture of N-phenylglycine monomer, amine-based reaction accelerator and metal oxide nanoparticles;
Adding the mixture to an acid solution containing an oxidizing agent to form a polymerization reaction product;
Polymerizing the N-phenylglycine monomer of the polymerization reaction product to form poly-N-phenylglycine nanofibers and metal nanoparticles bound to the nanofibers; And
The poly-N-phenylglycine nanofiber composite having the metal oxide nanoparticles bound thereto is treated with a basic solution to dedoped the poly-N-phenylglycine nanofiber to form a carboxyl anion in the poly-N-phenylglycine nanofiber &Lt; / RTI &gt; The method according to claim 6,
Wherein the metal of the metal oxide nanoparticles comprises at least one selected from the group consisting of iron, aluminum, manganese, and two or more alloys thereof. delete A metal adsorbent comprising the organic-inorganic hybrid material according to any one of claims 3 to 5. The method of claim 3,
Wherein some of the metal oxide nanoparticles are drawn into the nanofiber.

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