KR101285121B1 - Composite membrane supported bimetallic nanoparticles for the degradation of halogenated hydrocabons in water and manufacturing method thereof - Google Patents

Abstract

The present invention is a composite membrane comprising a nano-size valent iron contained in the polymer membrane and the polymer membrane; Or it provides a composite membrane comprising a polymer membrane, and a bimetal of the nano-size valent iron and metal catalyst contained in the polymer membrane. In addition, the present invention comprises the steps of providing an iron ion solution, performing the ion exchange reaction of the iron ion solution and the polymer membrane to include iron ions in the polymer membrane, and reducing the iron ions nano-sized zero valent iron contained in the polymer membrane A method of manufacturing a composite film comprising the step of forming; Or providing an iron ion solution, performing an ion exchange reaction between the iron ion solution and the polymer membrane to include iron ions in the polymer membrane, reducing iron ions to form nano-sized zero valent iron included in the polymer membrane, and Forming a metal catalyst on the nano-sized zero-valent iron provides a method for producing a composite membrane comprising the step of forming a bi-metal of the nano-sized zero-valent iron and metal catalyst contained in the polymer membrane. According to the present invention, it is possible to remarkably improve the decomposition rate of halogenated hydrocarbons contained in waste water and the like, to maximize the dehalogenation activity, to solve the problem of coagulation of nanoparticles, to improve mechanical stability, and to improve the ease and efficiency of the process. The halogen hydrocarbon in the aqueous system can be removed easily and efficiently.

Description

Composite Membrane Impregnated with Double Metals for Halogen Hydrocarbon Removal in Aqueous System and Manufacturing Method Thereof

The present invention relates to a reactive membrane for the removal of halogen hydrocarbons contained in wastewater, and more particularly, to a composite membrane consisting of a cationic membrane impregnated with nanoscale zero-valent iron or nanosize zero-valent iron-containing bimetallic nanoparticles, and a method of manufacturing the same. It is about.

Waste water and the like contain various contaminants. In particular, halogenated hydrocarbons such as trichloroethylene (TCE) (hereinafter referred to as "HHCs") are representative examples.

Recently, many studies have been conducted on the use of nanoscale zerovalent iron (hereinafter referred to as "ZVI") for the decomposition and removal of contaminants such as halogenated hydrocarbons in the water system.

Nano-size ferrous iron is one of the nanomaterials well known for its high reactivity due to its high surface area and small size, which can be used for contaminant treatment. In particular, it is known that nano-size ferrous iron can be effectively used for the removal of halogen hydrocarbons such as TCE.

However, nanosized zero valent iron has a very high reactivity in water, resulting in the formation of an unreacted iron oxide layer which results in passivation of the nanosized zero valent iron surface, resulting in a slower rate of contaminant degradation and a lower degradation activity.

In addition, the nano-sized zero valent iron is easily aggregated due to the thermodynamic properties to be present in a stable state, there is a problem that the reaction efficiency is lowered and has almost no mobility.

Therefore, the development of a halogen hydrocarbon removal technology that can quickly and effectively decompose contaminants such as halogen hydrocarbons contained in the water system using nano-sized zero valent iron and further solve the problems caused by nanoparticle aggregation.

The present invention exhibits high halogenated hydrocarbon decomposition rate, extended dehalogenation activity and improved mechanical stability by impregnating the nano-sized zero valent iron or the bimetallic nanoparticles including the same into the polymer membrane, and solves the coagulation problem of the nanoparticles. It is an object of the present invention to provide a composite membrane and a method for manufacturing the same that can be easily and efficiently removed.

Composite membrane according to an embodiment of the present invention is a polymer membrane; And nano-sized zero valent iron contained in the polymer membrane.

Composite membrane according to another embodiment of the present invention is a polymer membrane; And a bimetal of the nano-sized zero valent iron and the metal catalyst included in the polymer membrane.

Method for producing a composite membrane according to another embodiment of the present invention comprises the steps of providing an iron ion solution; Incorporating iron ions into the polymer membrane by performing an ion exchange reaction between the iron ion solution and the polymer membrane; And reducing the iron ions to form the nano-sized zero valent iron contained in the polymer membrane.

Method for producing a composite membrane according to another embodiment of the present invention comprises the steps of providing an iron ion solution; Incorporating iron ions into the polymer membrane by performing an ion exchange reaction between the iron ion solution and the polymer membrane; Reducing the iron ions to form nano-sized zero valent iron contained in the polymer membrane; And forming a metal catalyst on the nano-sized zero valent iron to form a bimetal of the nano-sized zero valent iron and the metal catalyst included in the polymer membrane.

According to the present invention, by using the composite membrane impregnated with nano-size zero-valent iron or bimetallic nanoparticles including the same in the polymer membrane, it is possible to remarkably improve the decomposition rate of halogenated hydrocarbons contained in waste water and the like and maximize the dehalogenation activity.

In addition, by using the composite membrane according to the present invention, it is possible to solve the agglomeration problem of the nanoparticles, improve the mechanical stability, ensure the ease and efficiency of the process, and can easily and efficiently remove halogen hydrocarbons in the water system.

1 is a schematic diagram showing the dehalogenation reaction of ZVI / Pd double metal nanoparticles for halogenated hydrocarbon treatment.
2 is a chemical structure of Nafion (a) and a photograph of a commercially available Nafion 117 membrane (b).
3 is a schematic diagram showing immobilization of ZVI in a Nafion membrane.
Figure 4 is an optical image of a Nafion 117 (a), ZVI ( c) formed on the ion-exchanged Fe ^{2 +} (b) Nafion 117 and Nafion 117 on.
5 is a field emission scanning electron microscope (FE-SEM) image (bottom) and an energy dispersive X-ray spectroscopy (EDAX spectral mapping) profile (top right) of Fe ⁰ / Nafion 117.
6 is imageJ analysis and histogram of Fe nanoparticles in Nafion 117.
7 is a graph showing average nanoparticle size according to Fe ion concentration in ZVI / Nafion 117.
8 is a high-resolution transmission electron microscope (HR-TEM) image (a, b), limited field electron diffraction (SAED) profile (c) and energy dispersive X-ray spectroscopy profile of Fe ⁰ / Nafion 117.
FIG. 9 shows HR-TEM analysis of HAADF images of Fe ⁰ / Nafion membranes and EDS mapping results of Fe in selected regions of samples.
10 is FE-SEM image and EDS spectral data of the Fe ⁰ -Pd / Nafion composite membrane.
FIG. 11 is a graph showing the TCE concentration profile during contact with Fe ⁰ / Nafion with various amounts of Pd.
12 is a graph showing the TCE removal efficiency after contact with Fe ⁰ / Nafion having various amounts of Pd for 150 minutes.
Fig. 13 is an FE-SEM image of a composite film having a Pd addition amount of 8.72 wt% with respect to Fe content.
14 is a linear approximation result for the TCE K _m values shown in Table 1. FIG.
FIG. 15 shows possible TCE degradation pathways by Nafion with bimetallic Fe / Pd nanoparticles.
FIG. 16 is a graph showing the concentration profile of chlorine ions released during TCE dechlorination.

Hereinafter, the most preferred embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art may easily implement the technical idea of the present invention. do.

Composite membrane according to an embodiment of the present invention is a polymer membrane; And nano-sized zero valent iron contained in the polymer membrane.

Composite membrane according to another embodiment of the present invention is a polymer membrane; And a bimetal of the nano-sized zero valent iron and the metal catalyst included in the polymer membrane.

As such, the present invention impregnates the nano-sized zero-valent iron or nano-sized zero-valent iron-containing bimetallic nanoparticles into the polymer membrane, thereby solving the aggregation problem of nanoparticles, improving mechanical stability, further increasing the decomposition rate of halogen hydrocarbons Dehalogen activity can be extended.

The polymer membrane included in the composite membrane of the present invention serves as a support for fixing nano-sized valent iron or nano-sized valent iron-containing bimetallic nanoparticles. This prevents agglomeration of the nanoparticles in the suspension, thereby maximizing the specific surface area of the nanoparticles and allowing easy handling of the nanoparticles.

Polymeric membranes that can be used in the composite membrane of the present invention are various, and examples thereof include a cationic ion exchange membrane having a negative charge in an aqueous environment.

The cationic ion exchange membrane are -SO ₃ ^- groups may include one or more kinds selected from the group consisting of ^-, -COOH, and -OPO _3.

In addition, specific examples of the polymer membrane may include Nafion or functionalized polysulfone.

In the composite membrane according to an embodiment of the present invention, by including a metal catalyst in the nano-sized zero valent iron, it is possible to improve the decomposition rate of contaminants such as halogenated hydrocarbons.

The metal catalyst may be present on the nano-sized zero valent iron surface included in the polymer membrane. In one example, a metal catalyst may be present in the form of an island on the nanoscale zero valent iron surface.

The metal catalyst that may be included in the composite membrane of the present invention may include palladium (Pd).

Palladium islands deposited on nanoscale zero valent iron can be faster in decomposition and prolonged dehalogenation activity compared to monometallic nanosize zero valent iron.

The decomposition mechanism of ZVI / Pd bimetallic nanoparticles is shown in FIG. 1. The stoichiometric reactions shown in FIG. 1 are shown in Schemes 1-3.

[Reaction Scheme 1]

Fe ⁰ + 2H ⁺ → Fe ^{2 +} + H ₂

[Reaction Scheme 2]

RX + H ⁺ → ⁰ + Fe Fe ^{+ 2} + RH + Cl ^-

Scheme 3

_{^{RX + 2Pd 0 + H 2 →}} H + + RH + 2Pd + Cl -

As shown in Scheme 1, in an acid environment, ZVI is easily oxidized by ferrous ions (Fe ^{+ 2)} to produce hydrogen (H _2). In addition, as shown in Scheme 2, ZVI can also reduce halogen hydrocarbon (RX) alone. In particular, the Pd-mediated dehalogenation reaction shown in Scheme 3 is faster than Scheme 2. In Pd islands, dehalogenation of halogenated hydrocarbons (RX → RH) occurs as a result of a transition complex between H ₂ and RX.

As shown in FIG. 1 and Schemes 1 to 3, the composite membrane of the present invention can efficiently decompose halogenated hydrocarbons such as trichloroethylene (TCE) contained in waste water and the like at high speed.

On the other hand, the method of manufacturing a composite membrane according to an embodiment of the present invention comprises the steps of providing an iron ion solution; Incorporating iron ions into the polymer membrane by performing an ion exchange reaction between the iron ion solution and the polymer membrane; And reducing the iron ions to form the nano-sized zero valent iron contained in the polymer membrane.

Method for producing a composite membrane according to another embodiment of the present invention comprises the steps of providing an iron ion solution; Incorporating iron ions into the polymer membrane by performing an ion exchange reaction between the iron ion solution and the polymer membrane; Reducing the iron ions to form nano-sized zero valent iron contained in the polymer membrane; And forming a metal catalyst on the nano-sized zero valent iron to form a bimetal of the nano-sized zero valent iron and the metal catalyst included in the polymer membrane.

Ferrous ion solution which can be used in the composite film production method of the present invention includes a metal salt solution of a Fe ^{2 +} ions or Fe ^{3 +} ions in deoxygenated deionized water.

As a precursor for forming the iron ion solution, a hydrated form of FeCl ₂ or an anhydride form of FeCl ₃ may be used.

Since iron starts to form as the solubility in water decreases at a pH of 7 or more, the iron ion solution is preferably acidic to prevent Fe precipitation.

In addition, since the size of the nano-sized zero-valent iron is related to the concentration of iron ions, the concentration of the iron ion solution should be such that it does not oversaturate the ion exchange capacity of the polymer membrane in order to prevent the aggregation of the nano-sized zero-valent iron in the subsequent reduction step. desirable.

The ion exchange reaction between the iron ion solution and the polymer membrane is preferably performed in an oxygen free atmosphere.

In one example, the ion exchange reaction can be accomplished by immersing the polymer membrane in an iron ion solution. Immersion time is selected such that the ion exchange reaction can be carried out completely, for example, may be 1 hour or more.

In the composite membrane manufacturing method according to an embodiment of the present invention, after the step of including iron ions in the polymer membrane by the ion exchange reaction, the first step of washing the polymer membrane containing iron ions with acidic deoxygenated deionized water and deoxygenation It may further comprise the step of second washing with deionized water. By this washing, residues contained in the polymer membrane can be completely removed to prevent their precipitation.

Next, iron ions are reduced to form nano-sized zero valent iron contained in the polymer membrane.

The reducing agent used for the reduction of the iron ions is not particularly limited, but sodium borohydrite (NaBH ₄ ) is preferably used.

In one example, the reduction of iron ions may be accomplished by immersing the polymer membrane containing iron ions in a NaBH ₄ solution in deoxygenated deionized water. Formation of Fe nanoparticles using NaBH ₄ is represented by Scheme 4 below.

[Reaction Scheme 4]

_{^{Fe 2 + + 2BH 4 - +}} 6H 2 O → Fe 0 ↓ + 2B (OH) ₃ + 7H ₂ ↑

Reduction of iron ions is preferably performed in an oxygen free atmosphere.

Such a reduction reaction may take place for at least 8 hours or more, preferably overnight.

In the composite membrane manufacturing method according to an embodiment of the present invention, after the step of reducing the iron ions to form the nano-sized zero valent iron contained in the polymer membrane, further comprising the step of washing the polymer membrane containing the nano-sized zero valent iron with deoxygenated deionized water It may include. By this washing, residual reducing agents can be removed.

Forming a metal catalyst on the nano-sized zero valent iron to form a bimetal of the nano-sized zero valent iron and the metal catalyst included in the polymer membrane may be performed using a metal salt solution of palladium in a mixed solvent of alcohol and deoxygenated deionized water. .

In one example, palladium may be formed in an island form on nanosize zero valent iron by immersing the polymer membrane containing nano size zero valent iron in a metal salt solution of palladium in a mixed solvent of alcohol and deoxygenated deionized water. The formation of Pd islands is represented by Scheme 5 below.

Scheme 5

Fe ⁰ + Pd ^{2 +} → Fe ^{2 +} + Pd ⁰

In the composite membrane manufacturing method according to an embodiment of the present invention, after forming a metal catalyst on the nano-sized zero valent iron to form a double metal of the nano-sized zero valent iron and the metal catalyst included in the polymer membrane, the double metal is included The method may further include washing the polymer membrane with anhydrous ethanol.

The composite membrane thus prepared can significantly improve the decomposition rate of halogenated hydrocarbons contained in waste water and the like and maximize the dehalogenation activity. In addition, it is possible to solve the problem of aggregation of nanoparticles, to improve mechanical stability, to ensure the ease and efficiency of the process, it is possible to easily and efficiently remove halogen hydrocarbons in the water system.

Hereinafter, the present invention will be described in more detail by way of examples. However, the following examples are illustrative of the present invention, and the scope of the present invention is not limited to the following examples.

[ Example ]

1. Composite Membrane Manufacturing

A Nafion 117 membrane, ZVI precursor FeCl ₂ -4H ₂ O and K ₂ Pd precursor Cl Pd ₄ was purchased from Sigma-Aldrich (USA). Preparation of all reagent solutions and reactions were carried out in an oxygen free atmosphere to prevent oxidation of ZVI in air. An oxygen-free atmosphere was achieved by using high purity compressed inert gases such as argon (Ar) and nitrogen (N ₂ ).

Nafion 117 membrane was used as the cationic membrane. Figure 2 shows the chemical structure of Nafion and pictures of commercially available Nafion 117 membranes. The polymer backbone and side chains of Nafion consist of fluorocarbons, and the side chains are functionalized with SO ₃ ⁻ groups.

Deoxygenating deionized water using a 25 ㎎ to 250 ㎎ Fe ^{2 +} / ℓ concentration of FeCl ₂ The solution was prepared. Deoxygenation of deionized water can be achieved by sparging high purity compressed inert gas such as argon (Ar) and nitrogen (N ₂ ) through a stainless steel or stone diffuser for a suitable time. FeCl ₂ The solution was kept acidic to prevent Fe precipitation.

Prepared FeCl ₂ The Nafion 117 membrane was immersed in the solution for 1 to 3 hours and ion exchange was performed. Ion exchange is most preferably done in an oxygen free chamber purged with Ar or N ₂ , and may be done in a fumehood with an available gas sparger. Or purge the container with a high purity compressed inert gas such as argon (Ar) and nitrogen (N ₂ ). Properly purging the top of the reactor allows the container to be sealed with paraffin after the gas source is turned off. This is an economical technique where no anaerobic glove boxes are available.

3 shows the immobilization of ZVI in the Nafion membrane. SO ₃ present in the ^{Nafion-groups} to facilitate the capture of Fe ions (Fe ^{+ 2} or Fe ^{+ 3).}

The ion exchanged membrane was washed with acidic deoxygenated deionized water (pH = 4) to remove Fe ions remaining on the membrane surface and prevent precipitation. Next, it was washed with deoxygenated deionized water for complete removal of the residue.

The ion exchanged membrane was then immersed in a 1 wt% NaBH ₄ solution in deoxygenated deionized water overnight to reduce Fe ions to nanoparticles. NaBH ₄ generates hydrogen gas reactively in water but is stable at low concentrations. Therefore, it is not preferable to make the concentration of the NaBH ₄ solution higher than 1 wt%, and the solution is preferably prepared a few minutes before the reaction so as to exhibit maximum efficiency as a reducing agent.

Nafion 117 in FIG. 4 (a), shows an optical image of a ZVI (c) formed on the ion Fe ^{2 +} (b) Nafion 117 and Nafion 117 exchanged.

After the reduction reaction, the composite membrane containing Fe nanoparticles was washed thoroughly with deoxygenated deionized water to remove residual reducing agent.

Next, the composite membrane prepared with K ₂ Cl ₄ Pd was immersed in a Pd solution, and post-coating of Pd islands was performed on the composite membrane. The solvent is preferably a combination of alcohol and deoxygenated deionized water. After the Pd reagent was dissolved in water, alcohol was added.

The prepared composite membrane was completely washed with anhydrous ethanol and then stored.

2. Optimization of Nanoparticle Size

(One) Fe  For nanoparticle formation pH Effect

To determine the effect of FeCl ² solution pH on the ZVI form at Nafion 117, prior to Pd deposition, experiments were performed at nearly neutral and acidic conditions (pH = 4) of pH-7.

Figure 5 Field Emission Scanning Electron Microscope (FE-SEM) image of the Fe ⁰ / Nafion 117 surface (bottom) and Energy Dispersive X-ray Spectroscpy (EDAX spectral mapping) ) Results (top right).

As shown in the results of the energy dispersive X-ray spectroscopy of FIG. 5, it was confirmed that the fine particles on the Nafion membrane were Fe nanoparticles produced by Fe signals at 0.8, 6.5, and 7.1 keV.

In addition, when the Nafion membrane was immersed in the Fe solution of pH ~ 7 without adjusting the pH, the nanoparticles were produced in a non-uniform distribution, it was found that intensive aggregates were formed (Fig. 5 (a), acidic conditions of pH = 4) When the Nafion membrane was immersed in the Fe solution of the nanoparticles were uniformly distributed, it was confirmed that the aggregate was not formed (Fig. 5 (b)).

(2) Fe  Effect of precursor concentration

The ZVI / Nafion 117 membrane ZVI particle size distribution produced using a solution (pH = 4) of various Fe ^{2 +} concentration was determined through the analysis imageJ. FIG. 6 shows imageJ analysis and histogram of Fe nanoparticles in Nafion 117. FIG. 7 is a graph showing average nanoparticle size according to Fe ion concentration.

6 and 7, it was confirmed that ZVI size is directly related to the Fe ^{2 +} concentration. FIG. 7 shows that in order to prevent intensive ZVI aggregates during the reduction process, it is preferable to immerse Nafion 117 in a Fe solution that does not supersaturate the ion exchange capacity of the membrane.

3. HR - TEM Using Fe ⁰ Of Nafion Characterization

Low Fe ^{2 +} nano-particles in the prepared membrane at a concentration (100 ㎎ Fe / ℓ) was not clearly observed by using a FE-SEM because of the small particle size. Thus, the nanoparticles were observed using a high-resolution transmission electron microscope (HR-TEM), the results are shown in FIG. FIG. 8 is a High Resolution Transmission Electron Microscpoy (HR-TEM) image (a, b) of Fe ⁰ / Nafion 117, a Selected Area Electron Diffraction (“SAED”) profile (c). ) And energy dispersive x-ray spectroscopic profile (d). Membrane samples were prepared using a focused ion beam ("FIB").

The HR-TEM analysis of FIG. 8 (a) shows the bright field image of the sample, and it can be seen that the nanoparticles are about 10 nm in size at a larger magnification of FIG. 8 (b). The SAED profile of FIG. 8 (c) shows the polycrystallinity of Fe nanoparticles. The energy dispersive x-ray spectroscopy profile of FIG. 8 (d) is consistent with the results obtained from the FE-SEM shown in FIG. 5.

The location of Fe nanoparticles in the Nafion membrane is visualized through HR-TEM EDS mapping and shown in FIG. 9. Green indicates a Fe signal, from which it was confirmed that Fe nanoparticles were well distributed in the polymer matrix of Nafion.

4. FE - SEM Using Fe ⁰ - Pd Of Nafion Characterization

The presence of Pd was confirmed through FE-SEM, and the results are shown in FIG. 10. As shown in the FE-SEM image of the Fe ⁰ -Pd / Nafion composite membrane of FIGS. 10 (a) and 10 (b), the nanoparticles are seen at the surface and in the cross section, respectively. In addition, as shown in Figs. 10 (c) and 10 (d), the EDS spectrum showed the peak intensity of Pd at 2.9 keV, indicating the presence of Pd in the Nafion film.

5. Fe ⁰ - Pd Of Nafion Trichloroethylene by TCE )of Dechlorination

The effect of the amount of Pd addition on the reaction rate of Fe ⁰ -Pd / Nafion composite membrane for TCE decomposition was examined by varying the concentration of Pd solution used for post-coating Fe ⁰ / Nafion membrane. 11 shows the TCE concentration profiles during contact with Fe ⁰ / Nafion with various amounts of Pd. The initial concentration (C ₀ ) was 10 mg / l and the experiment was in batch mode with stirring at room temperature.

11, the Fe ⁰ / Nafion membrane without Pd had a low TCE decomposition rate, whereas the Fe ⁰ -Pd / Nafion composite membrane with Pd added 1.5 to 1.75 wt% (wt% relative to Fe) was 150 minutes in contact. It can be seen that after time, the TCE concentration in the solution was significantly reduced.

FIG. 12 shows the TCE removal efficiency after contact with Fe ⁰ / Nafion having various amounts of Pd for 150 minutes. The initial concentration (C ₀ ) was 10 mg / l and the experiment was in batch mode with stirring at room temperature.

12, it can be seen that 10 mg / L TCE was almost completely removed when 1.74 wt% of Pd was added. Also, when the amount of Pd added exceeded 1.74 wt%, the TCE removal efficiency was lowered, which is thought to be due to excessive loss of Fe ⁰ by membrane damage and decomposition into Fe ²⁺ as mentioned in Scheme 5. Therefore, it is preferable that Pd is not excessively added in order to prevent the loss of activity of the composite film due to the loss of Fe ⁰ . This can also be confirmed through the FE-SEM analysis shown in FIG. 13.

FIG. 13 shows an FE-SEM image of a composite film having a Pd addition amount of 8.72 wt% with respect to Fe content. As shown by the circle in FIG. 13, it can be seen that the Fe nanoparticles disappeared with the physical structure modification of the membrane matrix.

The TCE reaction rate in Nafion membranes with bimetallic nanoparticles was determined through a first-order rate model, as shown in Equation 1, where C is the TCE concentration at time t, C ₀ is the initial TCE concentration, and k _m is a decomposition rate constant (min-1). The half-life of the TCE was calculated using Equation 7.

[Equation 1]

Ln (C / C ₀ ) = k _m t

&Quot; (2) "

_{t 1/2 = Ln2 / k} m

Table 1 shows the rate constants of TCE decomposition according to the amount of Pd added, and FIG. 14 shows the linear approximation results by the least square method for the K _m values shown in Table 1.

Pd amount added (wt%) K _m (min ^-1 ) t _1/2 (min) 0 -0.0015 462 0.34 -0.016 43 1.74 -0.049 14 3.5 -0.010 69 8.72 -0.0023 301

Tables 11 and from Fig. 14, Fe ⁰ / Nafion The Pd is added, it was confirmed that compared with the Fe ⁰ / Nafion Pd is not added the faster the reaction rate TCE. This indicates that the dechlorination of TCE is promoted by the presence of Pd.

6. Available TCE  Decomposition Path

15 shows possible TCE degradation pathways by Nafion with bimetallic Fe / Pd nanoparticles. It is known that 3 moles of chlorine ions (Cl ⁻ ) are present per mole of TCE. The release of Cl ⁻ is the strongest indicator of dehalogenation. The presence of chlorine ions in the solution after the reaction indicates that the TCE removal is due to decomposition and not due to volatilization of TCE.

Since degradation of TCE may be a continuous separation of Cl ⁻ in the TCE molecule, two or three Cl ⁻ may be directly and simultaneously removed in one TCE molecule. FIG. 16 shows the concentration profile of chlorine ions released during TCE dechlorination. In the TCE dechlorination reaction, a Nafion membrane having double metal Fe / Pd nanoparticles added with 1.74 wt% Pd based on Fe was used, and the initial TCE concentration (C ₀ ) was 12 mg / l. Figure 16 shows, Cl for the one, two or three simultaneous removal of chloride ion ^- the theoretical value of the / TCE ratio is shown by a broken line. The measurement results shown in FIG. 16 showed that the chlorine ion concentration during the reaction was very consistent with the removal of one Cl ⁻ ion (dotted line 1) in one TCE molecule. However, later in the reaction, a gradual increase in Cl ⁻ concentration was observed, indicating a final decomposition of dichloroethane to vinyl chloride (2Cl ⁻ ) and possibly ethylene.

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 or constructions. Various changes, substitutions and alterations can be made hereto without departing from the spirit and scope of the invention. It will be clear to those who have knowledge.

Claims (21)

delete Polymer membranes; And
Including the nano-sized zero-valent iron and a metal catalyst of the double metal contained in the polymer membrane,
The metal catalyst includes palladium (Pd),
For halogen hydrocarbon decomposition
Composite membrane.
The method of claim 2,
The polymer membrane includes a cationic ion exchange membrane
Composite membrane.
The method of claim 3,
The cationic ion exchange membranes is -SO ₃ ^-, characterized in that it comprises at least one group selected from the group consisting of ^-, -COOH, and -OPO ₃
Composite membrane.
The method of claim 3,
The polymer membrane includes Nafion or functionalized polysulfone
Composite membrane.
delete The method of claim 2,
The metal catalyst is characterized in that present on the nano-sized zero valent iron surface
Composite membrane.
delete delete As a method of manufacturing a composite film for halogen hydrocarbon decomposition,
Providing an iron ion solution;
Incorporating iron ions into the polymer membrane by performing an ion exchange reaction between the iron ion solution and the polymer membrane;
Reducing the iron ions to form nano-sized zero valent iron contained in the polymer membrane; And
Forming a metal catalyst on the nano-sized zero valent iron to form a bimetal of the nano-sized zero valent iron and the metal catalyst included in the polymer membrane,
The metal catalyst is formed using a metal salt solution of palladium in a mixed solvent of alcohol and deoxygenated deionized water.
Method for producing a composite membrane.
The method of claim 10,
The iron ion solution comprises a metal salt solution of Fe ²⁺ ions or Fe ³⁺ ions in deoxygenated deionized water.
Method for producing a composite membrane.
The method of claim 10,
The iron ion solution is characterized in that the acid
Method for producing a composite membrane.
The method of claim 10,
The concentration of the iron ion solution is characterized in that it does not oversaturate the ion exchange capacity of the polymer membrane
Method for producing a composite membrane.
The method of claim 10,
The ion exchange reaction is characterized in that it is made in an oxygen-free atmosphere
Method for producing a composite membrane.
The method of claim 10,
Reduction of the iron ion is characterized in that using NaBH ₄ as a reducing agent
Method for producing a composite membrane.
The method of claim 10,
Reduction of the iron ions is characterized in that in an oxygen-free atmosphere
Method for producing a composite membrane.
delete The method of claim 10,
After performing the ion exchange reaction of the iron ion solution and the polymer membrane to include iron ions in the polymer membrane,
First washing the polymer membrane containing iron ions with acidic deoxygenated deionized water; And
Further comprising the second step of washing with deoxygenated deionized water
Method for producing a composite membrane.
The method of claim 10,
After the step of reducing the iron ions to form a nano-sized zero valent iron contained in the polymer film,
Further comprising the step of washing the polymer membrane containing nano-sized zero valent iron with deoxygenated deionized water
Method for producing a composite membrane.
The method of claim 10,
After the step of forming a metal catalyst on the nano-sized zero-valent iron to form a bimetal of the nano-sized zero-valent iron and metal catalyst contained in the polymer film,
Further comprising the step of washing the polymer film containing a double metal with anhydrous ethanol
Method for producing a composite membrane.
delete

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