KR101027139B1 - Polyphenol-coated nano-scale zero valent iron for restoring soil and underground water and a method for preparing the same - Google Patents

Abstract

PURPOSE: A polyphenol-coated nano-scale zero valent iron(P-nZVI) for restoring soil and underground water and a method for preparing the same are provided to expand the effective radius of the P-nZVI by including the superior dispersibility and the mobility. CONSTITUTION: A method for preparing P-nZVI includes the following: polyphenol is added to an iron-contained solution to obtain a polyphenol-Fe solution. A reducing agent is added to the polyphenol-Fe solution. A reaction is implemented to synthesize the P-nZVI. The adding amount of the polyphenol is 10 to 50 parts by weight with respect to 100 parts by weight of iron.

Description

Poly-Coated Nano-scale Zero Valent Iron for Restoring Soil and Underground Water and a Method for Preparing the Same}

The present invention relates to an environmentally friendly polyphenol-coated nano-scale zero valent iron (P-nZVI) and a method for manufacturing the same for restoring soil and groundwater, and more specifically, a polyphenol containing Fe ⁰ and a natural material. The present invention relates to a P-nZVI coated with and a method of manufacturing the same.

      The use of iron in the environmental field can be divided into the following cases. As a method of utilizing iron that has been applied to the water treatment field for the past 20 years, there are Fenton and Fenton-like oxidation using radical hydroxide generated by the reaction of divalent or zero-valent iron with hydrogen peroxide. In addition, the ZVI research is being actively commercialized, the heavy metal immobilization and desalination reaction using the oxidation / reduction reaction of iron, which has recently been commercialized.

Various materials can be used to treat pollutants by oxidation / reduction reactions as long as they have reducing power as transition metals. In particular, zero-valent metal iron (Fe ⁰ , Zero Valent Iron, ZVI) is the most widely used. Reactive metals include Ca (-2.87), Mg (-2.70), etc., and the reducing power is also higher than iron, but metal iron is relatively high in reactivity and readily available and can produce particles of desired size. have. In addition, it is inexpensive and very economical because it is possible to use recycled materials such as metal scrap. Although iron is included in heavy metals, its toxicity is so low that even a small amount of iron in groundwater does not have a significant adverse effect on humans or ecosystems.

In order to cause the dechlorination reduction reaction using the transition metal, electron transfer is required, and three models have been proposed according to the contact method of iron and contaminants. (Scherer et al . 1999). The first model is the cathode and anode domains caused by the oxidation of the iron surface, and contaminants directly contact the cathode. In this case, the reactive site on the iron surface is extremely small, explaining all reactions that occur on the iron surface. Can not. Thus, the second model presented is a model in which the oxide film formed on the iron surface acts as a semi-conductor, and the reduction reaction of organic matter is carried out through the reduction potential reduced by the oxide film thickness. In this case, we can supplement the first direct contact model, but still only account for the surface response. In the third case, the model shows that the reaction can proceed by coordination of Fe-H and Fe-OH bonds in the oxide film on the iron surface. In this case, the reduction potential is the lowest.

It is reported that zero iron has a reduction potential of -0.3 to 0.7 V depending on the type thereof, and a reduction reaction having a lower potential than that of iron can be theoretically treated. Research on the removal of contaminants by using such ferric iron is ongoing. Chlorinated organic pollutants that can be treated by desalination reaction with iron are halogenated ethylenes (TCE, PCE), halogenated alkanes (TCM, DCM, etc.) and halogenated compounds. Aromatics (phenol chlorides, PCBs, dioxins, PBDEs), etc., vary in processing speed, but most of them can be desalted. Nitrogen compounds such as nitrate, nitrite, and nitro-aromatics are reduced to nitrogen gas at very fast reaction rates and can be applied to water treatment. In addition, it has been reported that heavy metals such as Cr, As, Pb, Zn, and Ni and radioactive materials such as uranium can be treated by adsorption reaction by oxidation / reduction.

Such reactive iron can be prepared by various methods depending on the purpose of use.

Representatively, the recent development of nano-ferrous iron as a manufacturing technology can be largely divided into physical synthesis and chemical synthesis. Physical synthesis includes 1) Inert Gas condensation, 2) Severe plastic deformation, 3) High-energy ball billing, and 4) Ultrasound shot peening, and chemical synthesis includes 1) Reverse Micelle (or Microemulsion), 2) Controlled chemical coprecipitation 3) Chemical vapor condensation, 4) pulse electrodeposition 5) Liquid flame spray 6) Liquid-phase reduction and 7) Gas-phase reduction. Synthesis methods used for dual environmental purification are mainly by boll-milling, liquid-phase reduction (wet reduction), and gas-phase reduction (gas-phase reduction). Initially, micro size ZVI, which is used for reactive iron (PRB), which has been used for iron, has been produced by boll-milling, and recently, nano size ZVI (FeBH) is produced by a wet reduction method synthesized using a reducing agent such as NaBH ₄ . In order to increase the specific surface area, increase the reactivity, and reduce the particle size, research is being actively conducted to synthesize nZVI which can move the soil pores more easily. In addition, RNIP (Fe ^H2 , Reactive Nano Iron Particle), which is manufactured and applied to the environmental purification by injecting and reducing H ₂ under high temperature and high pressure, is used.

Nanoporous iron prepared by the hydrogen reduction (Fe ^H2 ) method and the electro-reduction method of the existing nano-ferrous iron synthesis method is excellent in purity, but expensive and easily oxidized, it takes effort and cost for additional oxidation prevention. Recently, the wet reduction method-Fe ^BH has been spotlighted as the most suitable synthesis method for treating environmental pollutants by enabling the synthesis and application of relatively simple catalysts.

However, this wet synthesis also results in a strong tendency of the particles to agglomerate with each other, rapid sedimentation, and consequent mobility restrictions and reduced applicability in the field application of the particles. Nano sized ferric iron particles are ferromagnetic materials, so each particle acts like a magnet, forming a rod or chain, and when the uniting force becomes stronger, it looks like a net. The gas itself acts as a single particle, and negative charges accumulate on the surface, making it difficult to separate each particle even with strong physical forces, and require additives to reduce aggregation.

Until now, various experiments have been conducted in the laboratory using nano-ferrous iron, and have been studied on DNAPL (Dense Non-Aqueous Phase Liquid) treatment and heavy metal immobilization. However, in order to apply to the field, the rapid reactivity of nZVI and the reaction of oxygen in soil before reacting with pollutants in soil by Aggregation, oxidized and lost reactivity, and the aggregated nano-iron iron moves through soil pores. It is not possible to form a small impact radius, and the injection of additional nano-ferrous iron, finally to solve the problem of increased purification costs.

Accordingly, the present inventors have made efforts to solve the problems of the prior art, and to strive for environmentally friendly nano-ferrous iron with excellent pollutant removal ability, but to produce nZVI by the wet reduction method using NaBH ₄ as a reducing agent, The addition of phenol (polyphenol) to prepare a P-ZVI containing Fe ⁰ coated with a polyphenol (polyphenol), the P-ZVI not only has excellent reactivity retention, dispersibility and mobility in soil, The present invention was completed by confirming that no secondary pollution was caused.

An object of the present invention to provide an environmentally friendly P-nZVI and a method for manufacturing the soil and ground water restoration.

The present invention to achieve the above object, (a) adding a polyphenol (polyphenol) to the Fe-containing solution to prepare a Polyphenol-Fe solution; And (b) adding a reducing agent to the polyphenol-Fe solution to obtain a synthesized P-nZVI.

The present invention also provides P-nZVI containing Fe ⁰ coated with polyphenols.

P-nZVI according to the present invention has excellent reaction stability due to the surface coating structure of polyphenol (polyphenol), excellent reaction stability, dispersibility and mobility in the contaminant medium, and can expand the radius of impact, economical and environmentally friendly to be.

The present invention in one aspect, (a) adding a polyphenol (polyphenol) to the Fe-containing solution to prepare a Polyphenol-Fe solution; And (b) adding a reducing agent to the polyphenol-Fe solution to obtain a synthesized P-nZVI.

The present invention is characterized in that the production of nano-iron iron coated with the polyphenol (polyphenol) by adding a polyphenol (polyphenol) as a natural material in the process of manufacturing nano-iron iron by a wet reduction method of a synthetic method using a reducing agent. do.

Polyphenol (hydrolyzable tannin) is a natural substance having two or more hydroxyl groups, also called polyhydric phenol, and is mainly present in the fruits and leaves of plants.

According to the present invention, the nano-ferrous iron coated with polyphenols exhibits excellent reaction stability, dispersibility and mobility in water-soluble contamination media due to the polyphenol coating membrane, and is environmentally friendly when used as a purifying agent. It will not cause secondary pollution. The stability of the reaction in such a water-soluble medium enables the affinity with water to be enhanced due to the formation of hydrogen bonds with hydroxyphenyl groups formed on the nZVI surface and water, and the effect of inhibiting aggregation between nZVI particles can be obtained.

The term "P-nZVI" as used herein refers to nano-ferrous iron coated with the polyphenol, and the notation varies depending on the type of polyphenol used in the manufacturing process of the nano-ferrous iron. can do. For example, in the present application, when a tannic acid is used as a polyphenol, it is referred to as T-nZVI (Tannic Acid-coated Nano-scale Zero Valent Iron).

As used herein, the term “nZVI” refers to nanoferrous iron commonly used.

As used herein, the term "Fe-containing solution" means a solution in which Fe is ionized and contained. For example, Fe may be FeCl ₃ · 6H ₂ O aqueous solution containing Fe ^{3+ in} the state.

As used herein, the term "polyphenol-Fe solution" means a solution in which the Fe-containing solution and polyphenol (polyphenol) is mixed.

As used herein, the term "pollution medium" refers to groundwater, soil, and the like contaminated with heavy metals, nitrates, sulfates, organic halogen contaminants, DNAPL, and the like.

In the present invention, the amount of the polyphenol added is 10 to 50 parts by weight, preferably 12 to 25 parts by weight, more preferably 0.16 part by weight based on 100 parts by weight of Fe contained in the Fe-containing solution. It may be characterized by a denial. When the concentration of the polyphenol (polyphenol) is 10 to 50 parts by weight, the dispersibility of P-nZVI, the removal efficiency of heavy metals and organic halogen contaminants are excellent.

In the present invention, the addition amount of the reducing agent may be characterized in that 100 to 200 parts by weight based on 100 parts by weight of Fe contained in the Fe-containing solution. When the amount of the reducing agent added is 100 to 200 parts by weight, the efficiency of P-nZVI is excellent.

In the present invention, the Fe-containing solution may be characterized in that the FeCl ₃ · 6H ₂ O aqueous solution. The FeCl ₃ · 6H ₂ O aqueous solution can be prepared by dissolving FeCl ₃ · 6H ₂ O in secondary distilled water of 0 <DO concentration <0.3 mg / L.

In the present invention, the addition of the polyphenol (polyphenol) is composed of tannic acid (Ganlic acid), gallic acid (Gallic acid), catechin (Catechin), Camperol (Kaempferol), Luteolin (Quecetin) and Quecetin (Quercetin) It is characterized by adding a natural polyphenol (polyphenol) selected from the group or a natural extract of the plant containing the natural polyphenol (polyphenol). At this time, the natural extract may be extracted with water or 70% ethanol as a solvent, the plant containing the natural polyphenol (polyphenol) may be fruit peel or seeds, such as grapes, peaches, apples.

In the present invention, the reducing agent may be characterized in that NaBH ₄ .

On the other hand, the reducing agent is preferably added in a slow dropwise manner, the dropping rate may be 1.0 ~ 5.0ml / min.

In the present invention, the steps (a) and (b) may be performed under anaerobic conditions. Specifically, the steps (a) and (b) is preferably carried out while maintaining the anaerobic conditions by continuously purging the N ₂ gas in a closed state.

In the present invention, after the step (b) may be characterized in that it further comprises the ultrasonic drying and washing step. Through the ultrasonic drying and washing step, residues and impurities of the reducing agent remaining on the surface of P-nZVI may be removed. The ultrasonic drying and washing step is also preferably performed under anaerobic conditions as in the step (a) and (b).

In another aspect, the invention relates to P-nZVI containing Fe ⁰ and coated with polyphenol. That is, the P-nZVI has a core-shell shape, in which Fe ⁰ is positioned at the center, and Fe ⁰ is surrounded by polyphenol.

In the present invention, the content of Fe ⁰ in the P-nZVI may be characterized in that 42 to 50% by weight. When the Fe ⁰ content is within the numerical range, the dispersibility, heavy metal removal ability and reducing power of P-nZVI are excellent, as compared with when the Fe ⁰ content is less than 42% or more than 50%.

In the present invention, the polyphenol (polyphenol) may be characterized in that it is coated with a thickness of 3 ~ 5nm. The polyphenol coating film prevents rapid oxidation of P-nZVI to maintain reactivity in the contaminant medium for a long time, and facilitates electron transfer, and the van der of the particles by the negative charge charged on the nano-ferrous iron surface. The dispersion of particles can be improved by reducing the Waals forces and the magnetic interaction. At this time, when the thickness of the polyphenol (polyphenol) coating film is less than 3nm, effects such as maintaining the reactivity of the P-nZVI, electron transfer power, dispersibility, etc. as described above is reduced, if the thickness exceeds 5nm of the P-nZVI particles There is a problem that the size increases.

In the present invention, the particle size of the P-nZVI may be characterized in that 40 ~ 80nm, due to the particle size of the numerical range, can move between the soil pores to ensure a sufficient radius of influence contaminated soil For example, the P-nZVI can be directly injected into a contaminant such as groundwater to treat contaminants.

In the present invention, the P-nZVI are heavy metals, nitrate (NO ₃ ^-), sulfate (SO ₄ ^2-), organohalogen pollutants, DNAPL (Dense Non-Aqeous Phase Liquid) and selected from the group consisting of a mixture thereof It may be characterized in that it is used for the purification of the contaminating medium containing the material.

Specifically, the heavy metal may be selected from the group consisting of Cr ⁶⁺ , As, Hg, Cu, Pb, Ni, Cd, and mixtures thereof. The organochlorine pollutants may be PCE (perhloroethylene), TCE (trichloroethylene), It may be selected from the group consisting of polychlorinated biphenyls (PCBs) and mixtures thereof.

P-nZVI Cr ⁶⁺ according to the present invention shows a heavy metal removal capacity of 0.1 ~ 0.2g / g Fe ⁰ .

Recently, the development of technology for manufacturing nano-ferrous iron that can be applied to the actual field has been actively made. According to the present invention, P-nZVI has a stable protective film by polyphenol (polyphenol) on the surface. Therefore, polyphenol (charge) on the surface of the iron acupuncture by (-) Charge to prevent agglomeration between particles, resulting in a stable dispersing effect, which can lead to nano-ferrous iron particles in the soil voids There is an advantage to prevent precipitation, to move far enough to secure a sufficient impact radius.

This advantage enables sufficient responsiveness and a wide range of influences, which are becoming important for applications in the field recently using nano-ferrous iron. As a result, when the contaminated area is to be restored using the P-nZVI of the present invention, the amount of P-nZVI injection can be minimized, and the P-nZVI injection well can be directly injected without minimizing the installation of the contaminated area and soil. Dense non-aqeous phase liquid (DNAPL) and heavy metal contaminants in groundwater can be economically restored by applying environmentally friendly and simple methods.

Hereinafter, the present invention will be described in more detail by way of examples. These examples are intended to illustrate the present invention in more detail, and it will be apparent to those skilled in the art that the scope of the present invention is not limited to these examples.

Example 1 Preparation of P-nZVI

Reagents used to prepare P-nZVI include FeCl ₃ · 6H ₂ O (Aldrich Chemical, USA), Tannic acid as polyphenol (Aldrich Chemical, USA) and NaBH ₄ as reducing agent to prepare Fe-containing solutions. (Aldrich Chemical, USA) was used. In addition, secondary distilled water was used as distilled water, but secondary distilled water having 0 <DO concentration <0.3 mg / L was purged with N ₂ . The following steps 1-1 and 1-2 were all purged with N ₂ and carried out in an anaerobic state.

1-1. Polyphenol-Fe Solution Preparation

13.52 g of FeCl ₃ · 6H ₂ O was dissolved in 100 ml of distilled water to prepare a 0.5 M Fe ³⁺ solution. Polyphenol-Fe aqueous solution was prepared by adding 0.46 g of tannic acid to 100 ml of the 0.5 M Fe ³⁺ solution.

1-2. Reducing agent added

0.9 g of NaBH ₄ was dissolved in 30 ml of distilled water to prepare a 0.8 M NaBH ₄ solution. The solution was added dropwise to 10 ml of an aqueous polyphenol-Fe solution prepared in 1-1, and added dropwise while appropriately changing at a rate of 0.1 to 0.6 ml / min. -nZVI was prepared (see Scheme (1)).

4Fe ³⁺ + 3BH ^4- + 9H ₂ O-> 4Fe ⁰ + 3H ₂ BO ^3- + 12H ⁺ + 6H ₂ (1)

1-3. Ultrasonic Drying and Washing

After ultrasonication was applied to P-nZVI prepared in 1-2 for 20 minutes to dry, and then washed three times with distilled water purged with N ₂ to remove B (Boron) and impurities remaining on the surface (Fig. One).

Example 2: P-nZVI Particle Characterization

The properties of P-nZVI prepared in Example 1 were analyzed.

2-1. Size and Shape of P-nZVI Particles

Transmission electron microscopy (TEM) (JEM-2100F, JEOL, USA) was used to analyze the size and shape of the P-nZVI particles.

As a result, as shown in Fig. 2 (a), it was confirmed that the P-nZVI particles have a size of 40 ~ 80nm in average diameter.

In addition, as shown in (b) of FIG. 2, the P-nZVI particles were confirmed to have a polyphenol (polyphenol) film having a thickness of 5nm on the surface has a coated shape.

2-2. P-nZVI Component Analysis

X-ray diffraction (XRD) analysis (Max-2500V, RIGAKU, JP) confirmed that the major component of P-nZVI was Fe ⁰ .

The content of Fe ⁰ contained in P-nZVI was quantified using the H ₂ value quantified by GC-TCD (Thermal Conductivity Detector, HP-6890, USA). The amount of Fe ⁰ was quantified by quantifying H ₂ generated after (37%) injection.

As a result of quantification, it was confirmed that the Fe ⁰ content contained in P-nZVI was 47.3%. Since the Fe ⁰ content in the existing nZVI is 51.29% (Yueqiang Liu and Gregory V. Lowry., Environ. Sci. Technol. 39: 1338-1345, 2005), the Fe ⁰ content in the P-nZVI and nZVI Could see no big difference.

Fe ⁰ + 2H ⁺ -> Fe ²⁺ + H ₂ ↑ (2)

2-3. P-nZVI Specific Surface Area Measurement

BET analysis of P-nZVI was performed using ASAP 2010 Analyzer BET (Micromeritics, USA). As a result, it was confirmed that the average specific surface area (SSA) value was about 17.27 m ² / g. The reason why the specific surface area of the P-nZVI is measured is that when the polymer material such as polyphenol is coated on the surface, the Soild-Gas attractivity between nitrogen gas and adsorbent (P-nZVI) is lowered. It can be said that the specific surface area value is low.

Experimental Example 1 Analysis of Proper Addition of Polyphenol in Preparation of P-nZVI

In the preparation of P-nZVI according to Example 1, an experiment was carried out to calculate the optimum amount of polyphenol (polyphenol).

Preparation of P-nZVI according to the method of Example 1, 5 P-nZVI was added by adding the amount of polyphenol in the ratio of 0.5Fe, 0.25Fe, 0.167Fe, 0.125Fe and 0.01Fe to the mass of Fe, respectively Prepared. Thereafter, 5 mg of Cr ^{6+ was} injected into each of the five P-nZVI, and the amount of Cr ⁶⁺ removed was compared to determine the optimum amount of polyphenol.

As a result of comparing the residual amount of Cr ⁶⁺ before and after the experiment, it was confirmed that all the Cr ⁶⁺ was removed after the experiment in the case of 0.25Fe, 0.167Fe and 0.125Fe addition amount of polyphenol (polyphenol) as shown in FIG. . As a result, when the addition amount of polyphenol (0.25Fe, 0.167Fe and 0.125Fe), it was found that the removal efficiency of P-nZVI for Cr ⁶⁺ is excellent.

In addition, as a result of further experiments, the amount of addition of the polyphenol (polyphenol) if reacted for 0.25Fe, 0.167Fe 0.125Fe and, after increasing the concentration of Cr ⁶⁺ injection ssikeul Cr ⁶⁺ 10mg 2.5hr, of Cr ⁶⁺ It was confirmed that the residual amounts were 1.0 mg, 0.89 mg, and 2.21 mg, respectively. When the amount of polyphenol added was 0.167Fe, it was found that the removal efficiency of P-nZVI for Cr ⁶⁺ was the best.

Experimental Example 2: Dispersibility Test of P-nZVI

In order to confirm the dispersibility of P-nZVI, sedimentation experiments were performed.

P-nZVI was prepared according to Example 1, but P-nZVI was prepared using the optimal amount of polyphenol derived from Experimental Example 1, and the amount of tannic acid used as polyphenol was 0.167Fe. Prepared. At this time, the concentration of Fe ⁰ to 40mg / L, 80mg / L and 160mg / L by increasing the precipitation rate according to Fe ⁰ concentration was analyzed using a UV-visible spectrometer (Varian, Cary-3bio, USA).

In addition, a general nZVI was prepared for a comparative experiment with P-nZVI, and the precipitation rate according to the Fe ⁰ concentration was analyzed using UV as described above. At this time, nZVI was prepared by synthesizing 0.8M NaBH ₄ and 0.5M FeCl ₃ .6H ₂ O in a 1: 1.6 ratio.

As a result, as shown in FIG. 4, in the case of nZVI, as the concentration of Fe ⁰ increased, the precipitation rate increased, and nZVI precipitated after 30 minutes when the concentration of Fe ⁰ was 160 mg / L. On the other hand, in the case of P-nZVI, when the concentration of Fe ⁰ is 40mg / L, 80mg / L and 160mg / L, all of the precipitation rate is less than 10%, it can be seen that it can represent a stable dispersibility.

Experimental Example 3: Heavy Metal Removal Ability Test of P-nZVI

3-1: Cr of P-nZVI ⁶⁺  Removal experiment

In order to confirm the heavy metal removal ability of P-nZVI, Cr ⁶⁺ removal experiment of P-nZVI was performed.

Prepare P-nZVI according to Example 1, but utilizing the optimal amount of polyphenol derived from Experimental Example 1, the amount of tannic acid used as polyphenol (Pannic acid) is 0.167Fe -nZVI was prepared.

Cr ⁶⁺ (Kanto, 1000ppm Cr ⁶⁺ standard solution) was injected into 55.84mg of the prepared P-nZVI, but the experiment was removed by increasing the concentration of Cr ⁶⁺ to 2, 10, 20, 40 and 60ppm. Was performed.

After the experiment, the Cr ⁶⁺ content of the supernatant was quantified by analyzing by diphenylcarbazide method using a UV-Visible Spectrometer (CARY 3Bio, Varian, USA). The total-Cr content of the supernatant was analyzed using AA (Specra AA, Varian, USA), and the total-Cr content adsorbed / precipitated on P-nZVI was dried by Cr ⁶ + -injected P-nZVI sample and then ICP ( ICP Spectrometer EOP, Spectro Co., DE) to analyze the mass balance of the total-Cr of the sample.

As a result, Cr ⁶⁺ and Total-Cr of the supernatant were not measured. In addition, as a result of analysis of the P-nZVI sample injected with Cr ⁶⁺ , as shown in Table 1, the total-Cr mass balance of the sample was 63.3 ~ 111.68%, indicating that all of the adsorption / precipitated on the P-nZVI surface was observed. there was.

ppm Solution Vol. (Ml) Cr ⁶⁺ mass (mg) Fe mass
(mg) T-Cr
weight% Adsorption
Cr ⁶⁺ (mg) Cr Mass Balance 5 20 0.1 55.84 0.2 0.112 111.68 10 20 0.2 55.84 0.36 0.201 100.51 20 20 0.4 55.84 0.68 0.380 94.93 40 20 0.8 55.84 1.38 0.771 96.32 60 20 1.2 55.84 1.36 0.759 63.29

3-2: Cr of P-nZVI with Polyphenol Content ⁶⁺  Removal experiment

Preparation of P-nZVI according to the method of Example 1, 5 P-nZVI was added by adding the amount of polyphenol in the ratio of 0.5Fe, 0.25Fe, 0.167Fe, 0.125Fe and 0.01Fe to the mass of Fe, respectively Prepared. Thereafter, ⁶ mg of Cr ^{6+ was} injected into the five P-nZVIs, and the amount of Cr ⁶⁺ removal in each case was analyzed. At this time, the analysis method is injected Cr ⁶⁺ , after 2min, 5min, 15min, 30min, 60min and 120min, the Cr ⁶⁺ content of the supernatant was diphenyl using a UV-Visible Spectrometer (CARY 3Bio, Varian, USA) It was analyzed by the carbazide method.

As a result, as shown in Figure 5, when the addition amount of polyphenol (polyphenol) is 0.167Fe Cr ⁶⁺ content of the supernatant was confirmed that the Cr ⁶⁺ removal efficiency is excellent.

3-3: Cr of P-nZVI using natural extract of grape seed ⁶⁺  Removal experiment

Cr ⁶⁺ removal was performed by preparing P-nZVI using a natural extract polyphenol, a natural extract. Grape seed (Vitis vinifera, Campbell-Early variety) was dried, and then crushed with a grinder to quantify 1g. 1 g of grape seed powder and 10 ml of ethanol (70%) were mixed and vortexed for 10 minutes, and then the supernatant was extracted using a centrifuge. Nitrogen purging was performed for 10 minutes to remove ethanol from the extracted supernatant.

2 ml of an aqueous Fe (0.5M) solution to which 500 μl of the grape seed extract was added was reacted with 6 ml of NaBH ₄ (0.8 M) to prepare 55.85 mg of P-nZVI coated with the natural extract of grape seed.

55.85mg of Grape Seed P-nZVI prepared above and 50ppm, 100ppm, 150ppm, and 200ppm of Cr ⁶⁺ (Kanto, Cr ⁶⁺ Standard 1000ppm) aqueous solution were each reacted to perform a batch test to determine the removal amount. Constant over time (2 min, 5 min, 10 min, 20 min, 40 min, 60 min, 120 min.) At a sampling (Disposal Syringe (1ml)) by UV- the Cr ⁶⁺ content after filtration as 0.22㎛ filter (Millipore) Quantitative analysis was performed using a diphenylcarbazide method using a Visible Spectrometer (CARY 3Bio, Varian, USA).

As a result, as shown in Figure 6, both 50ppm and 100ppm Cr ^{6 +} aqueous solution was removed in two minutes, 150ppm 99.71%, 200ppm showed 75.73% efficiency. After 120 min, the final removal efficiencies were 50 ppm, 100 ppm, 150 ppm at 100% and 200 ppm at 83.91%. The removal ability of P-nZVI Cr ⁶⁺ coated with the natural extract of grape seed using this result was calculated as 90.2 mg [Cr ⁶⁺ ] / 1g [Grape Seed P-nZVI].

Experimental Example 4: Reduction Capability Test of P-nZVI

In order to examine the reduction potential of P-nZVI, an organic halogen TCE (trichloroethylene) decomposition experiment was performed using P-nZVI. In addition, the decomposition of TCE (trichloroethylene) which is an organic halogen material using nZVI as a comparison target of P-nZVI was also conducted.

0.056 g of P-nZVI ([Fe] = 0.5 M. 2 ml) prepared in Example 1 and 25 ml of 15 mg / L TCE aqueous solution were added to a 40 ml amber vial and reacted for 24 hr. After the reaction was started, the concentration of TCE was measured by sampling at 0, 1, 3, 6, 9, 12, and 24hr, and the TCE removal rate of P-nZVI was analyzed. For nZVI, the TCE removal rate was analyzed in the same manner as the P-nZVI. As a control, 25 ml of 15 mg / L TCE aqueous solution was kept in a 40 ml amber vial for 24 hr and analyzed for TCE removal rate. At this time, the analyzer was analyzed using a headspace sampler (HSS) (Agilent Technologies, USA) and gas chromatograph electron capture detector (GC-ECD) (Agilent Technologies, USA).

As a result of HSS and GC-ECD analysis, as shown in FIG. 7, the TCE concentration of the control group was 12.6-15 g / L for 24 hr, and there was no significant change from the initial concentration. When nZVI was used, the TCE concentration was 5.35 g / 24 hr after 24 hr. When P-nZVI was used, it was confirmed that TCE was not detected after 24hr when P-nZVI was used, and TCE was all degraded by P-nZVI, and no by-products such as cis-DCE, trans-DCE, and VC were detected. .

As a result, P-nZVI showed better TCE removal ability than nZVI, indicating that the reducing ability was improved.

While the present invention has been particularly shown and described with reference to specific embodiments thereof, those skilled in the art will appreciate that such specific embodiments are merely preferred embodiments and that the scope of the present invention is not limited thereby. something to do. Thus, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

1 is a manufacturing process diagram of P-nZVI according to the present invention.

2 is a TEM photograph of P-nZVI according to the present invention.

3 is a graph showing the Cr ⁶⁺ removal amount of P-nZVI according to the amount of polyphenol (polyphenol) added.

4 is a graph showing precipitation rates of nZVI and P-nZVI according to the concentration of Fe ⁰ .

5 is a graph showing the amount of polyphenol (polyphenol) and Cr ⁶⁺ removal of P-nZVI over time.

Figure 6 is a graph showing the removal amount of Cr ⁶⁺ over time using P-nZVI coated with polyphenol (polyphenol) extracted from the natural extract Grape Seed.

7 is a graph showing the amount of TCE degradation over time of the control group, nZVI and P-nZVI.

Claims (6)

Process for preparing Polyphenol-coated Nano-scale Zero Valent Iron (P-nZVI) containing Fe ⁰ and coated with Polyphenol, comprising the following steps: (a) adding a polyphenol to the Fe-containing solution to prepare a Polyphenol-Fe solution; And (b) adding a reducing agent to the polyphenol-Fe solution and reacting to synthesize P-nZVI. The method of claim 1, wherein the polyphenol is added in an amount of 10 to 50 parts by weight based on 100 parts by weight of Fe contained in the Fe-containing solution. The method of claim 1, wherein the polyphenol is added to tannic acid, gallic acid, catechin, kaempferol, luteolin, and quercetin. Natural polyphenol (Polyphenol) selected from the group consisting of or a method for producing P-nZVI, characterized in that the natural extract of the plant containing the polyphenol (Polyphenol) is added. P-nZVI containing Fe ⁰ and coated with Polyphenol. The method of claim 4, wherein the content of Fe ⁰ is 42 to 50% by weight, the thickness of the coated polyphenol (Polyphenol) is 3 ~ 5nm, the particle size of the P-nZVI is characterized in that 40 ~ 80nm P-nZVI. The method of claim 4, wherein the P-nZVI are heavy metals, nitrate (NO ₃ ^-), sulfate (SO ₄ ^2-), organohalogen pollutants, DNAPL (Dense Non-Aqeous Phase Liquid) and from mixtures thereof P-nZVI, characterized in that it is used for the purification of contaminants containing the selected substance.

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