KR20160088501A - nanoscale zero-valent iron for purification of infested soil or pollutants in groundwater and the manufacturing method thereof - Google Patents

Abstract

The present invention relates to a nanoscale zero-valent iron and a method for producing the nanoscale zero-valent iron, and more specifically, to a nanoscale zero-valent iron for treating soil and groundwater contaminants comprising dissimilar metals, and a method for producing the nanoscale zero-valent iron for treating soil and groundwater contaminants. One purpose of the present invention is to provide a nanoscale zero-valent iron comprising new dissimilar metals which is effective in the treatment of soil and water. Another purpose of the present invention is to provide a method for producing a nanoscale zero-valent iron comprising new dissimilar metals which is effective in the treatment of soil and water. The other purpose of the present invention is to provide a method for effectively treating contaminated soil and water using the method for producing the nanoscale zero-valent iron comprising the new dissimilar metals. An agent for treating soil and/or water according to the present invention comprises nanoscale zero-valent iron doped with bismuth, and exhibits a maximally threefold improved treatment efficiency compared to existing nZVI at aerobic/anaerobic conditions in the purification treatment of environmental pollutants such as RDX and others.

Description

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to nanofiltration iron for the treatment of soil and groundwater pollutants,

The present invention relates to a nano-zirconium-containing iron and a method for producing the same, and more particularly, to a nano-zirconium-containing iron for treating soil and groundwater contaminants containing different metals and a method for producing the same.

Removal of pollutants in soil / groundwater using nZVI is one of the representative nanotechnologies applied in the environmental field. In order to improve this, a method of doping a dissimilar metal is being developed.

Korean Patent No. 1190283 issued to the Korea Advanced Institute of Science and Technology (KOKAI) discloses a method for treating contaminants in soil and groundwater using heterogeneous metal nano-zirconium iron doped with copper or palladium.

Korean Patent No. 1076765 issued to Kwangju Institute of Science and Technology discloses a method for treating nitrate nitrogen using dissimilar metal nanospherites doped with copper, nickel, or palladium.

However, there is a continuing need for effective nanosilver iron and its manufacturing method.

A problem to be solved by the present invention is to provide a novel heterogeneous metal nano-zirconiferrous which is effective for soil and water treatment.

Another problem to be solved by the present invention is to provide a new method for producing heterometallic nano-sagittal iron effective for soil and water treatment.

Another problem to be solved by the present invention is to provide a method for effectively treating contaminated soil and water by using the method for producing new heterogeneous metal nano-sagittal iron.

In order to solve the above-mentioned problems, the nano- And is doped with bismuth.

Although it is not theoretically limited, Bi-nZVI can be decomposed more efficiently than conventional nano-scale zero-valent iron due to additional electron transfer and fast electron generation rate due to oxidation of bismuth (Bi ⁰ → Bi ^{3 +} ) under anaerobic conditions Unlike the conventional nano-zirconium ferrite, which has a reduced reactivity due to oxidation of iron even under the aerobic conditions in which dissolved oxygen exists, Bi-nZVI has a higher amount of Fe ^{2 +} , H ₂ O ₂ (see equation below) and form OH radicals through their Fenton reaction to promote oxidative degradation of contaminants.

Fe ⁰ + O ₂ + 2H ^{+ -} & gt ^; Fe ^{2 +} + H ₂ O ₂

Fe ⁰ + H ₂ O ₂ + 2H ^{+ -} & gt ^; Fe ^{2 +} + 2H ₂ O

Fe ⁰ + 2Bi ^{3 + -} > Fe ^{2 +} + 2Bi ^{2 +}

Fe ^{2 +} + H ₂ O ₂ → Fe ^{3 +} + · OH + OH ^- (Fenton reaction)

In the present invention, the bismuth is doped to the surface of the nano-zirconium iron with a metal classified as metal on the periodic table. The doped bismuth is preferably bismuth, which is zero valence. The bismuth is doped in a total amount of 0.01 to 10 wt%, preferably 0.1 to 9 wt%, and most preferably 0.5 to 5 wt%.

In the present invention, the method for producing bismuth-doped nano-

Preparing a mixed solution of Fe ^{2 +} -Bi ^{3 +} by dissolving FeSO ₄ · 7H ₂ O and Bi (NO ₃ ) ₃ · 5H ₂ O in water;

NaBH ₄ is dissolved in water to prepare a solution, and NaBH ₄ aqueous solution is added dropwise to the Fe ^{2 +} -Bi ^{3 +} mixed solution to prepare Bi-nZVI doped with bismuth on the surface; And

The Bi-nZVI thus prepared is washed with distilled water purged with nitrogen (N ₂ ) to remove impurities on the surface, and then dried in a vacuum drier at 60 ° C for 6 hours.

In one aspect, the present invention is characterized in that the bismuth-doped nanospharous iron is added with a bismuth salt during the production of the nanospherite.

In the present invention, the nano-zirconium iron may be prepared by reducing an Fe solution to NaBH ₄ , and the bismuth-doped nano-zirconium iron may be prepared by mixing bismuth salts with iron salts in the course of synthesizing nano- have.

In the practice of the present invention, the bismuth-doped nanocrystalline iron may be prepared by adding a bismuth salt to an Fe solution and then reducing it to NaBH ₄ . The bismuth salt may be bismuth nitrate. The bismuth nitrate can be doped to the surface by adjusting the addition concentration to 0.17 g / L to 0.68 g / L.

In one aspect, the present invention provides a method for oxidation / reduction treatment of contaminated soil and water using bismuth-doped nanospheresulfite.

In the present invention, the soil and water treatment process can be run under anaerobic or aerobic conditions, and can be carried out under neutral anaerobic conditions to improve the rate of oxidation / reduction of the nano- .

In the present invention, the contaminants are selected from the group consisting of hexahydro-1,3,5-trinitro-1,3,5-triazine, trinitrotoluene (TNT), nitrotoluene, nitrobenzene, dinitrobenzene, (PBDEs), Trichlorethylene (TCE), Tetrachloroethylenel (PCE), trichloroethane (PCE), trichlorethylene Trichoroethane (TCA), tetrachloroethane (PCA), chloroform, chlorinated methane, or a mixture of two or more thereof.

In the present invention, the bismuth-doped nano-zirconium iron may have an epoch-making processing speed of up to three times higher than that of the conventional nZVI under the aerobic / anaerobic conditions in the purification treatment of environmental pollutants such as RDX.

According to the present invention, it is possible to synthesize Bi-nZVI, which is a novel nano-zirconium oxide having a bismuth-doped surface, by a simple method. In the treatment of environmental pollutants such as RDX, There is an epoch-making effect that the ship has improved processing efficiency.

1 shows HRTEM / EDX and XPS analysis results of Bi-nZVI according to the present invention.
2 shows HRTEM and XRD analysis results of Bi-nZVI according to the present invention.
3 is a comparative graph of decomposition of RDX according to the addition amount of Bismuth ions.
Fig. 4 is a table showing the degree of decomposition of Bi-nZVI and nZVI in various conditions.
Figure 5 shows the RDX decomposition HPLC spectrum of Bi-nZVI and Au, Co, and Pd-nZVI under reducing conditions.

Hereinafter, the present invention will be described in more detail by way of examples. It is to be understood by those skilled in the art that these embodiments are for further illustrating the present invention and that the scope of the present invention is not limited to these embodiments.

Example  One

Preparation of experimental material

RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) was prepared as an environmental pollutant and MNX (hexahydro-1-nitroso-3,5- dinitro- 5-triazine) and TNX (hexahydro-1,3,5-trinitroso-1,3,5-triazine). In addition, bismuth nitrate (Bi (NO ₃ ) ₃ .5H ₂ O), ferrous sulfate (FeSO ₄ .7H ₂ O) and sodium borohydride (NaBH ₄ ) were used for the production of nanosilver iron.

Example  2

Preparation of Bi-nZVI

The distilled water was purged with N ₂ for 1 hour, and the following 2-1 and 2-2 steps proceeded in N ₂ purging state.

2-1. Preparation of Bi ^{3 +} -Fe ^{2 +} solution

2.0 g of FeSO ₄ .7H ₂ O and 0.14 g of Bi (NO ₃ ) ₃ .5H ₂ O (4% of Fe) were dissolved in 200 ml of distilled water to prepare a mixed solution of Fe ^{2 +} and Bi ^{3 +} .

2-2. Reducing agent addition

0.0032 g of NaBH ₄ was dissolved in 10 ml of distilled water to prepare a 0.32 g / L NaBH ₄ solution. Bi-nZVI was prepared by dropping a 2-2 NaBH ₄ aqueous solution at a uniform rate of 1 ml / min into the Bi-Fe mixed solution prepared in 2-1. (See Reaction Scheme (1)).

_{2FeSO 4 + 2Bi (NO 3)} 3 + 10NaBH 4 + 30H 2 O → 2Fe-Bi (s) + 35H 2 (g) + 10B (OH) 3 + 2Na 2 SO 4 + 6NaNO 3 (1)

2-3. Washing and drying

Bi-nZVI prepared in 2-2 was washed three times with distilled water purged with N ₂ to remove impurities on the surface, and then dried in a vacuum oven at 60 ° C or higher for 6 hours.

Example  3

Characterization of Bi-nZVI Particles

3-1. Particle shape of Bi-nZVI

Particle formation and elemental structure of the Bi-nZVI were analyzed using HRTEM / EDX (JEM-2200FS, JEOL, Japan) using high resolution transmission electron microscopy.

As a result, as shown in FIG. 2 (a), the Bi-nZVI particles can be confirmed to have a chain structure of spherical iron particles as in the previously reported nZVI. In addition, in the surface EDX analysis (Fig. 1 (a)), bismuth (Bi) signals were observed in addition to iron (Fe) and oxygen (O), and bismuth was uniformly distributed on the surface of iron particles.

3-2. Analysis of components of Bi-nZVI

From the analysis of X-ray diffraction (XRD) (MAC Science Co., Japan), peaks of iron and bismuth were observed in Bi-nZVI, and oxide peaks were not detected (FIG.

3-3. Analysis of surface characteristics of Bi-nZVI

X-ray photoelectron spectroscopy (ESCALAB 220iXL, VG scientific, USA) using Mg Ka (1253.6 eV) was used to measure the chemical bonding state of the elements present in Bi-nZVI.

Further, the bismuth component may be represented by Bi ⁰ (Fig. 1 (c)).

Thus, when both the results of Figures 1 and 2 are combined, Bi-nZVI indicates a new type of nano-zirconium iron doped with zero valence bismuth metal on the iron surface.

Example  4. Representative environmental pollutant purification treatment experiment

4-1. RDX decomposition experiment according to the amount of bismuth added

The reactivity of the Bi-nZVI was measured by RDX degradation, one of the explosive contaminants. The RDX degradation experiments were carried out under relatively neutral conditions of pH 5.85 and acidic conditions of pH 3, respectively. To 40 ml of RDX 10 ppm solution, 0.04 g of Bi-nZVI was mixed at room temperature and stirred in a rolling mixer (15 rpm) Respectively. Quantification of RDX by time was performed using liquid chromatography (High Performance Liquid Chromatography, Agilent 1100).

The decomposition experiments for RDX were carried out as described above, and the experimental results were compared by varying the concentration of Bi (NO ₃ ) ₃ .5H ₂ O added in the synthesis process from 0.17 g / L to 1.19 g / L. As a result, as shown in FIG. 3, it was confirmed that as the concentration of bismuth increases in the range of 0.17 to 0.68 g / L, the rate of RDX degradation becomes faster, but the rate decreases at a higher concentration. Based on the above results, it can be seen that it is preferable to use a bismuth nitrate concentration of 0.68 g / L to obtain Bi-nZVI having the best decomposition efficiency of RDX.

4-2. Comparison of RDX degradation rate with different types of nano-zero iron and niobium metal

The Bi-nZI exhibits better decomposing activity than conventional nano-zirconium iron (nZVI) under various conditions (aerobic and anaerobic conditions at neutral and acid pH) (Fig. 4).

In addition, it was confirmed that the decomposition of RDX was faster than that of nano-zero iron doped with Au, Co, and Pd under neutral anaerobic conditions (FIG. 5). This indicates that the newly synthesized Bi-nZI has a high reactivity to RDX.

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. Accordingly, the actual scope of the present invention will be defined by the appended claims and their equivalents.

Claims (12)

Characterized in that it is doped with bismuth. The nano-Zero-iron as set forth in claim 1, wherein the bismuth is zero spirit. The nano-zirconium iron according to claim 1, wherein the bismuth is 0.01 to 10 wt%. Wherein the bismuth salt is added. The method according to claim 4, wherein the nano-zirconium iron is prepared by adding a bismuth salt to an Fe solution and reducing it to NaBH ₄ . The method according to claim 4 or 5, wherein the bismuth salt is bismuth nitrate. 7. The method of claim 6, wherein the bismuth nitrate has an added concentration of 0.17 g / L to 0.68 g / L. A method for treating contaminated soil and water by oxidation / reduction reaction using bismuth-doped nano-zirconium iron. The method of claim 8, wherein the contaminant is selected from the group consisting of hexahydro-1,3,5-trinitro-1,3,5-triazine, trinitrotoluene (TNT), nitrotoluene, nitrobenzene, dinitrobenzene (PBDEs), Trichlorethylene (TCE), Tetrachloroethylenel (PCE), Trichloroethylene (PCE), and the like. Characterized in that it is selected from the group consisting of trichoroethane (TCA), tetrachloroethane (PCA), chloroform, chlorinated methane. 9. The method of claim 8, wherein the treatment is performed in a neutral anaerobic condition. Lt; RTI ID = 0.0 > nano-valent < / RTI > iron doped with bismuth. A water treatment agent containing nano-valent iron doped with bismuth.

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