KR100944779B1 - Water quality sensor detecting heavy metal and method of manufacturing the same - Google Patents

Abstract

The present invention provides a base member, a conductive layer formed on a portion of one surface of the base member, the conductive layer made of a conductive material, an insulating layer formed on the conductive layer to expose a portion of the conductive layer, and the exposed conductive layer. Provided is a water quality sensor for detecting heavy metals having a bismuth layer formed on one region and including bismuth (Bi) powder. The water quality sensor for heavy metal detection is excellent in heavy metal detection performance, high reliability of the sensor and excellent in manufacturing efficiency and cost.

Description

Water quality sensor detecting heavy metal and method of manufacturing the same

The present invention relates to a water quality sensor for detecting heavy metals and a method for manufacturing the same, and more particularly, to a water quality sensor for detecting heavy metals and a method for producing the same, which are excellent in reliability, excellent in manufacturing competitiveness, and environmentally friendly.

In general, stripping voltammetry is a kind of electrochemical analysis, in which heavy metals present in water are concentrated on the surface of an electrode using the properties of redox potential of heavy metals, and then released into water. It is a method of quantitative analysis of heavy metals in solution by analyzing specific current changes (voltage and current curves).

Since the stripping voltammetry concentrates the reactants on the electrode surface in advance, the sensitivity is very high, so that even a small amount of the substance can be quantified, and the electrolytic concentration process is performed at a specific potential, thereby increasing the selectivity of the analysis. Currently, as a working electrode for stripping voltammetry, a hanging mercury drop electrode and a mercury thin film electrode using mercury are widely used. However, due to the problem of toxic mercury treatment after analysis, surface treatment for reproducibility of analytical results, and properties that easily change when exposed to air, the development of non-toxic, environmentally friendly alternative electrodes that do not contain mercury Many efforts are being made.

Currently, research has been focused on thin bismuth film electrodes based on glassy carbon electrodes as an alternative electrode material for such stripping voltammetry. However, when it is used as a working electrode, several steps of surface cleaning and treatment are required for each measurement for reproducibility of sensitivity and analysis result, and the surface process at this time greatly affects the resilience and functionality of the working electrode. This is related to the accuracy and reliability of the analysis results and may limit their use as field portable equipment as well as on-line measurement analysis in automated systems.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a water-soluble sensor for detecting heavy metals, which is eco-friendly, simple to manufacture, and inexpensive in applying stripping voltammetry.

In addition, an object of the present invention is to provide a method for producing a heavy metal detection water quality sensor that can efficiently produce the above-described water quality sensor for heavy metal detection.

Technical problems to be achieved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

The water quality sensor for heavy metal detection according to an aspect of the present invention is formed on a base member, a partial region of one surface of the base member, a conductive layer made of a conductive material, and formed on the conductive layer so that a partial region of the conductive layer is exposed. An insulating layer and a bismuth layer formed on one region of the exposed conductive layer and including bismuth (Bi) powder.

Conductive carbon ink and the like may be used as the conductive material.

The base member may have a rod shape, and the conductive layer may be formed on the surface of the base member in parallel with the long side of the base member to have a stripe shape.

The insulating layer may be formed on the conductive layer so that both ends of the conductive layer are exposed.

The bismuth layer is formed on either end of the both ends.

It is preferable that the thickness of the said conductive layer is 20-100 micrometers, and it contains 2-5 micrograms of bismuth powders per unit area (1 cm <^2> ). In addition, the total weight of the bismuth powder contained in the bismuth layer is preferably 0.2 to 0.5 μg.

The bismuth layer comprises bismuth powder having a particle size of 6 to 300 nm. In addition, the bismuth layer may further include an ion permeable polymer binder.

According to an aspect of the present invention, there is provided a method of manufacturing a water quality sensor for detecting a heavy metal, forming a conductive layer by printing a conductive material on a portion of one surface of a base member, and exposing one region of the conductive layer to be exposed. Forming an insulating layer by printing an insulating material on a base member, preparing a bismuth dispersion by dispersing bismuth powder in a dispersion solvent, and drying the bismuth dispersion by dropping it on one region of the exposed conductive layer It includes.

The dispersion solvent is an ion permeable polymer binder aqueous solution having a concentration of 0.1 to 10%, or preferably pure distilled water.

The bismuth powder is preferably prepared by gas condensation (gas condensation).

Hereinafter, a water quality sensor for detecting heavy metals according to an embodiment of the present invention will be described with reference to the accompanying drawings.

1 is a plan view showing a water quality sensor for heavy metal detection according to an embodiment of the present invention.

Referring to FIG. 1, the water quality sensor 100 for detecting a heavy metal includes a base member 110, a conductive layer 120, an insulating layer 130, and a bismuth layer 140.

As the base member 110, various materials having a smooth surface and excellent adhesive performance may be used. In the present embodiment, a polymer film is used as the base member 110. The kind of polymer film is not particularly limited.

On the other hand, the shape of the base member 110 is not particularly limited, the base member 110 of the present embodiment is a thin film of a rod shape.

The conductive layer 120 may be formed by, for example, screen printing conductive carbon ink on a portion of one surface of the base member 110. As the material forming the conductive layer 120, a conductive polymer may be used in addition to the conductive carbon ink. In particular, the conductive material preferably contains carbon.

The conductive carbon ink is dried under a predetermined temperature after screen printing, thereby forming the conductive layer 120.

The conductive layer 120 has a stripe shape extending along the long side of the base member 110.

The thickness of the conductive layer 120 affects the reliability of the water quality sensor 100 for detecting the heavy metal to be manufactured. If the thickness of the conductive layer 120 is too thin, a problem of electrical disconnection may occur. The conductive layer 120 preferably has a thickness of 20 to 100 μm, more preferably 80 μm.

The insulating layer 130 is formed by screen printing using an insulating ink or the like on the conductive layer 120. In order to form the insulating layer 130, as described above, it must be dried to a predetermined temperature after screen printing.

The insulating layer 130 is formed on the conductive layer 120 to expose a portion of the conductive layer 120. Referring back to FIG. 1, the insulating layer 130 is formed on an intermediate region of the band-shaped conductive layer 120 to expose the first conductive layer region 122 and the second conductive layer region 124. .

In FIG. 1, the length of the first conductive layer region 122 is relatively longer than the length of the second conductive layer region 124. The first conductive layer region 122 serves as a connection part for receiving external electricity, and the bismuth layer 140 is formed on one region of the second conductive layer 124.

The bismuth layer 140 is formed on one region of the exposed conductive layer 120, that is, one region of the second conductive layer 124.

The bismuth layer 140 is formed by dropping a bismuth dispersion prepared in advance on one region of the second conductive layer 124 and drying it.

The bismuth dispersion is prepared by uniformly dispersing bismuth powder in a dispersion solvent. On the other hand, the bismuth powder is preferably prepared by gas condensation (gas condensation) in order to effectively exclude impurities.

When the bismuth powder includes particles exceeding 300 nm, the performance of the heavy metal sensor 100 may be drastically degraded. Therefore, the bismuth powder is composed of crystal particles having a particle size of 300 nm or less, preferably made of crystal particles having a particle size of 6 to 75 nm.

Distilled water, ethanol, or the like may be used as the dispersion solvent used in the preparation of the bismuth dispersion. Moreover, as said dispersion solvent, it is preferable that it is the ion permeable polymer binder aqueous solution containing 0.1-10% of an ion permeable polymer binder.

As the ion permeable polymer binder, Nafion ™ may be used, and any known resin may be used as long as the ion permeable resin has high chemical and physical strength and high hydrogen ion conductivity.

The Nafion is a trade name of a polymer electrolyte developed by Du Pont (Nafion ™). The Nafion is basically a sulfonic acid group attached to a long chain made of a perfluorinated group in a Teflon (-CF ₂ -CF _2- ) polymer. In addition, the Nafion exhibits high hydrogen ion conductivity (0.08 S / cm at 30 ° C.) and excellent chemical and physical strength.

The total weight of the bismuth powder contained in the bismuth layer 140 is preferably 0.2 to 0.5 μg. On the other hand, the bismuth layer 140 preferably includes 2 to 5 μg of bismuth powder per unit area (1 cm ² ).

Hereinafter, various sensor sensitivity measurement results performed to evaluate the performance of the heavy metal detection water quality sensor 100 according to the present embodiment will be described. However, the technical idea of the present invention is not limited by the following experiments.

[Experiment]

1. Sensor for experiment

The water quality sensor for heavy metal detection used in the experiment was prepared by dispersing bismuth powder having a particle distribution of 6 to 75 nm in distilled water containing 0.24% of Nafion to make 0.02 g / L bismuth powder aqueous solution, and then 10 µl was added dropwise onto one region of the conductive layer, dried and immobilized.

2. Experimental method

Ag / AgCl (3 M KCl) was used as the reference electrode and included 0.1 M acetic-chloride buffer (pH 4.7) and 20 ppb of zinc (Zn), cadmium (Cd), and lead (Pb) ions. In the prepared solution, a voltage was applied at −1.4 V for 120 seconds to electroprecipitate these ions, and then stripping voltammetry was performed while linearly increasing the voltage at a rate of 1.0 V / s.

Conductive layer  Sensor sensitivity according to thickness

In order to investigate the analytical and chemical performance of the bismuth powder-labeled heavy metal sensor according to the present invention according to the thickness of the conductive layer, stripping voltammetry was performed on zinc, cadmium, and lead ions that can be analyzed simultaneously.

Table 1 below shows the results of the reproducibility (R) test on the stripping oxidation current (I) value measured using sensors having different thicknesses of the conductive layer and the initial oxidation current value after 5 repeated measurements. .

Conductive layer thickness (μm) Zn CD Pb R (%) I (μA) R (%) I (μA) R (%) I (μA) 40 127 12.2 80 11.2 81 6.9 80 97 9.8 103 10.5 99 5.9

As shown in Table 1 above, when the thickness of the conductive layer was 40 μm, higher current values were observed for each metal ion, but the reproducibility result of the current value was more accurate for a sensor having a thickness of 80 μm conductive layer. It can be seen that the value.

Therefore, in the following experiments, stripping voltammetry was performed with all conductive layer thicknesses of the sensor as 80 μm.

Bismuth  Sensor sensitivity by content

In manufacturing the heavy metal detection sensor, five kinds of sensors were fabricated by varying the amount of bismuth powder having a particle size distribution of 6-75 nm in order to select an appropriate content of the bismuth powder labeled on the conductive layer. Stripping voltammetry was performed on Cd and Pb ions.

Figure 2 is a graph showing the results of the oxidation stripping voltammetry according to the content of bismuth powder.

Referring to FIG. 2, when the bismuth content is 0.125 μg for all metal ions, the lowest stripping oxidation current value is shown. As the bismuth content gradually increases, the current value also increases and then shows a maximum value at 0.5 μg. In the above content, it decreased again.

Table 2 below shows the reproducibility test results of the oxidation current value of the sensor according to the content of the labeled bismuth powder.

Bi weight (μg) R (%) Zn CD Pb 0.125 162 42 65 0.2 97 103 98 0.5 105 99 110 1.0 88 120 116 2.0 58 96 97

As shown in Table 2, the oxidation current value of the sensor having a bismuth content of 0.2 to 0.5 μg shows excellent reproducibility even after five repeated measurements, while the sensor having a bismuth content of less than 0.2 μg and more than 0.5 μg In Esau, much deviation from the initial value was observed.

Accordingly, it can be seen from the results shown in FIG. 2 and Table 2 that the best sensor sensitivity is obtained when the bismuth powder is labeled on the conductive layer with a content of 0.2 μg or more and 0.5 μg or less.

Bismuth  Sensor sensitivity according to particle size distribution of powder

In order to investigate the analytical and chemical performance of the sensor according to the particle size distribution of the bismuth powder labeled on the conductive layer when manufacturing the heavy metal detection sensor, Zn, Cd, Pb by forming a group of bismuth powder having a different particle size distribution Stripping voltammetry was performed on the ions.

Bismuth powder groups having different particle size distributions were dispersed in distilled water to make 0.02 g / L of bismuth powder aqueous solution, and 10 μL of the aqueous solution was dropped on the surface of the conductive layer to prepare a working electrode.

3 and 4 are graphs showing the results of analysis obtained by performing linear scanning current voltammetry by increasing the concentration of each metal ion to 0, 20 and 40 ppb using a sensor labeled with bismuth powder having different particle size distributions. . FIG. 3 is a graph of a bismuth powder having a particle size distribution of 6 to 75 nm, and FIG. 4 is a graph of a bismuth powder having a particle size distribution of 300 nm or more.

As shown in FIG. 3, when the concentration of each metal ion is increased by 20 ppb, the sensor having a particle size distribution of 6 to 75 nm shows that the oxidative peak current for all metal ions increases proportionally. It can be seen that the voltage-current curve of the defined peak shape is shown. However, as shown in FIG. 4, the band-width widening phenomenon of the sensor having a distribution of 300 nm or more was found to be inferior in proportionality of peak current.

Table 3 below shows stripping oxidation current (I) values and reproducibility test results measured for a solution containing 20 ppb of Zn, Cd, and Pb ions using a sensor labeled with bismuth powder groups having different particle size distributions. .

Particle Size Distribution (nm) Zn CD Pb R (%) I (μA) R (%) I (μA) R (%) I (μA) 6-75 97 9.8 103 10.5 99 5.9 6-130 103 10.6 112 10.6 96 5.4 6-300 95 9.6 103 10.0 105 5.9 Wide distribution 96 4.6 62 0.9 95 6.8

As shown in Table 3, when the labeled bismuth powder has a size distribution of 6 to 75 nm to 6 to 300 nm, the reproducibility of the oxidation current value for all metal ions is relatively excellent, whereas 300 nm In the case of having the above wide size distribution, in particular, it was measured with a very large difference for the Cd ion. Therefore, it was found that the bismuth powder should have a particle size distribution of at least 6-300 nm for simultaneous analysis.

Bismuth  Sensor sensitivity according to disperse solvent for powder labeling

In manufacturing the heavy metal detection sensor, in order to investigate the analytical and chemical performance of the sensor according to the dispersion solvent for the bismuth powder label on the conductive layer, after labeling the bismuth powder using a different solvent on the conductive layer, Zn, Stripping voltammetry was performed on Cd and Pb ions.

A bismuth powder having a particle size distribution of 6 to 75 nm was dispersed in different solvents to prepare a 0.02 g / L bismuth powder solution, and then 10 μL of the solution was dropped on the conductive layer to prepare a sensor.

 Table 4 shows stripping oxidation current (I) values and reproducibility test results according to the types of solvents.

Dispersing solvent Zn CD Pb R (%) I (μA) R (%) I (μA) R (%) I (μA) H ₂ O 97 9.8 103 10.5 99 5.9 H ₂ O + 0.24% Nafion 110 26.5 97 25.3 105 12.5 H ₂ O + 0.45% Nafion 110 28.8 93 26.3 106 15.9 Ethanol 92 7.3 40 7.8 36 4.9 Ethanol + 0.24% Nafion - - 63 6.1 74 1.1 Ethanol + 0.45% Nafion - - 75 6.6 79 2.2 Chlororoform 305 1.7 87 7.2 78 5.5

As shown in Table 4, when ethanol and chloroform were used as the dispersion solvent, the analytical and chemical performance of the sensor was much lower, whereas when distilled water was used as the dispersion solvent, the reaction sensitivity was very good. You can see that.

In particular, when distilled water containing a small amount of ion-permeable polymer binder was used as a dispersion solvent, it was confirmed that the stripping oxidation current value for all metal ions was very high in the ion-permeable polymer binder aqueous solution, and the sensor sensitivity was further improved. .

According to the above, the water quality sensor for heavy metal detection according to the present invention is excellent in accuracy and reliability of the sensor, and excellent in manufacturing process efficiency. On the other hand, it is suitable for single use.

In addition, the water quality sensor for detecting heavy metals includes harmless bismuth powder, so that it is possible to replace conventional mercury electrodes and the like.

As described above, the present invention has been described by way of limited embodiments and drawings, but the present invention is not limited to the above embodiments, and those skilled in the art to which the present invention pertains various modifications and variations from such descriptions. This is possible. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the claims below but also by the equivalents of the claims.

1 is a plan view showing a water quality sensor for heavy metal detection according to an embodiment of the present invention.

Figure 2 is a graph showing the results of the oxidation stripping voltammetry according to the content of bismuth powder.

Figure 3 shows the analysis results obtained by performing a linear scanning current voltage method to increase the concentration of each metal ion to 0, 20 and 40 ppb using a sensor labeled bismuth powder having a particle size distribution of 6 ~ 75 nm, respectively It is a graph.

4 is a graph showing an analysis result obtained by performing a linear scanning current voltage method to increase the concentration of each metal ion to 0, 20 and 40 ppb, respectively, using a sensor labeled with bismuth powder having a particle size distribution of 300 nm or more. .

[Description of Major Symbols in Drawing]

100: Water quality sensor for heavy metal detection

110: base member 120: conductive layer

122: first conductive layer region 124: second conductive layer region

130: insulating layer 140: bismuth layer

Claims (16)

A base member; A conductive layer formed on a portion of one surface of the base member and made of a conductive material; An insulating layer formed on the conductive layer to expose a portion of the conductive layer; And A water quality sensor for detecting heavy metals having a bismuth layer formed on one region of the exposed conductive layer and including bismuth (Bi) powder. The method of claim 1, The base member is a water quality sensor for heavy metal detection, characterized in that the polymer film. The method of claim 1, The conductive material is a heavy metal sensor, characterized in that the conductive carbon ink. The method of claim 1, The base member has a rod shape and the conductive layer is formed on the surface of the base member in parallel with the long side of the base member having a stripe shape, the water quality sensor for heavy metal detection. The method of claim 4, wherein And the insulating layer is formed on the conductive layer so that both ends of the conductive layer are exposed. The method of claim 5, The water quality sensor for heavy metal detection, characterized in that the bismuth layer is formed on either end of the both ends. The method of claim 1, The thickness of the conductive layer is a water quality sensor for heavy metal detection, characterized in that 20 to 100 ㎛. The method of claim 1, The bismuth layer is heavy metal detection water sensor, characterized in that it comprises 2 to 5 μg of bismuth powder per unit area (1 cm ² ). The method of claim 1, The total weight of the bismuth powder contained in the bismuth layer is a water detection sensor for heavy metals, characterized in that 0.2 to 0.5 ㎍. The method of claim 1, The bismuth layer is heavy metal sensing water quality sensor, characterized in that it comprises a bismuth powder having a particle size of 6 to 300 nm. The method of claim 1, The bismuth layer is heavy metal detection water sensor, characterized in that further comprises an ion-permeable polymer binder. The method of claim 11, The ion permeable polymer binder is Nafion, the water quality sensor for heavy metal detection. Printing a conductive material on a portion of one surface of the base member to form a conductive layer; Forming an insulating layer by printing an insulating material on the base member to expose one region of the conductive layer; Dispersing bismuth powder in a dispersion solvent to prepare a bismuth dispersion; And And dropping the bismuth dispersion onto a region of the exposed conductive layer to dry the bismuth dispersion. The method of claim 13, The dispersion solvent is a method for producing a heavy metal detection water quality sensor, characterized in that the aqueous ion-permeable polymer binder aqueous solution having a concentration of 0.1 to 10%. The method of claim 13, The dispersion solvent is a method of manufacturing a water quality sensor for heavy metal detection, characterized in that the distilled water. The method of claim 13, The bismuth powder is a manufacturing method of the water quality sensor for heavy metal detection, characterized in that produced by gas condensation (gas condensation).

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