US20140076724A1

US20140076724A1 - Cell module, ozone generator thereof and methods for generating ozone using the same

Info

Publication number: US20140076724A1
Application number: US13/617,921
Authority: US
Inventors: Liang-Chien Cheng; Tai-Fang Hung; I-Chiao Lin; Chun-Lung Chiu; Xin-Ying Han; Ru-Shi Liu; Shih-Chang Chen; Chien-Min Sung
Original assignee: Cashido Corp
Current assignee: Cashido Corp
Priority date: 2012-09-14
Filing date: 2012-09-14
Publication date: 2014-03-20

Abstract

A cell module includes an anode, a cathode and a proton exchange membrane. The anode adheres to one side of the proton exchange membrane while the cathode adheres to the opposite side thereof. The anode comprises a substrate and at least one diamond-like carbon layer covering the substrate. The present disclosure further provides an ozone generator and a method using the same.

Description

BACKGROUND

1. Technical Field
The present disclosure relates to a cell module; in particular, the cell module utilizes a diamond-like carbon anode in an ozone generator to produce ozone.
2. Description of Related Art
The conventional way to sanitize an object is by boiling the object in the water to destroy the bacteria. Another commonly used way is adding sanitizer, which comprises chlorides or the like, in the washing water. Due to extensive pollution, the number of microorganisms in the tap water has increased every year so the concentration of chlorides in the sanitizer increases altogether. High concentration chlorides cause a peculiar odor and may result in secondary pollution to the environment like detergent does.
Like chlorides, fluorides and ozone are strong oxidants which are prone to gain electrons. However, fluorides are highly toxic to human, thus cannot be used in the drinking or washing water. In the contrary, ozone is less toxic compared to fluorides meanwhile a potent oxidizing agent, which is 3000 times more effective than chlorides, and therefore in the water ozone can significantly reduce the bacterial number and decompose chemical remains. The ozone not reacted will automatically decompose to oxygen without secondary contamination to the environment.
Nevertheless, ozone production is a costly process which prevents the public implementation of ozone. The conventional ozone generators are ultraviolet (UV) light ozone generator, corona discharge method and electrolysis of water. The UV light ozone generator employs a lamp emitting UV light at approximately 185 nanometers (nm) to energize oxygen molecules (O₂). The energized, highly reactive oxygen free radicals combine with other oxygen molecules to form ozone (O₃). However the ozone concentration produced is usually low and higher wavelength UV light tends to decay ozone.
The corona discharge method uses high voltage currents to ionize gas oxygen and form ozone molecules, which is in relation to the UV light ozone generator. The corona discharge method requires considerable preparation in advance because the yield of ozone is in directly proportional to the air dryness and oxygen concentration. In moist air, yields of oxides and other particles increase, which are not easy to separate from ozone. The high voltage current is mostly converted to heat in the process so cooling devices are essential. Therefore the entry requirement of corona discharge method is high because of the need of complex instrument and regular maintenance.
The conventional electrolysis of water for ozone is by adding water to appropriate electrolytes and supplying DC power to the device. The metallic electrodes are easily corroded because in the production of ozone many highly reactive molecules are formed as well, thus quickening the electrodes decaying. One way is to replace the metallic electrodes by conductive diamond which is hard, resistant to corrosion and chemically inert yet the cost is considerably high so that diamond electrodes are not widely, commercially implemented.

SUMMARY

The object of the present disclosure is to provide a cell module with a diamond-like carbon electrode and ozone generator using the same, which is highly efficient, low in cost and having physical properties in accordance with diamond.
One aspect of the present disclosure is to provide a cell module, which includes a proton exchange membrane (PEM), an anode and a corresponding cathode. The anode comprises a substrate and at least one diamond-like carbon (DLC) layer formed on the substrate. The DLC layer is doped with nitrogen to form the nitride diamond-like carbon (DLC/N). The anode adheres to one side of lateral faces of the PEM and the cathode adheres to the other thereof.
Another aspect of the present disclosure is to provide an ozone generator, which includes a tank, a cell module disposed in the tank and at least two conduction plates. The tank has a plurality of water inlets and a plurality of water outlets. The cell module has a proton exchange membrane, an anode and a corresponding cathode. The anode comprises a substrate and at least one diamond-like carbon (DLC) layer formed on the substrate. The anode adheres to one side of lateral faces of the PEM and the cathode adheres to the other thereof. The cell module is flanked by the two conduction plates at either side respectively.
Still another aspect of the present disclosure is to provide a method for ozone production.
In summary, the anode covered by the DLC layer, which is highly conductive and inexpensive, requires lower voltage current and less power, thus significantly reducing energy consumption. The cell module is also suitable for long period operation because of the stability contributed by the DLC layer. Additionally, the cell module has simplified layout with high sterilizing rate.
In order to further understand the present disclosure, the following embodiments are provided along with illustrations to facilitate the appreciation of the present disclosure; however, the appended drawings are merely provided for reference and illustration, without any intention to be used for limiting present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an embodiment of a cell module in accordance with the present disclosure.

FIG. 2 is an electronic microscope diagram of a diamond-like layer on a substrate in accordance with the present disclosure.

FIG. 3 is a schematic diagram of an embodiment of an ozone generator in accordance with the present disclosure.

FIG. 4 is a graph showing a relationship between the current (A) and potential (V) of nitride diamond-like carbon and platinum.

FIG. 5 is a graph showing ozone concentration (ppm) versus time (min) of a first embodiment in accordance with the present disclosure.

FIG. 6 is a graph showing E. coli cell count (%) versus time (min) of a first embodiment in accordance with the present disclosure.

FIG. 7 is a graph showing a relationship between the redox potential (mV) and time (min) of a second embodiment in accordance with the present disclosure.

FIG. 8 is a graph showing a relationship between the redox potential (mV) and time (min) of a third embodiment in accordance with the present disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The aforementioned illustrations and following detailed descriptions are exemplary for the purpose of further explaining the scope of the present disclosure. Other objectives and advantages related to the present disclosure will be illustrated in the subsequent descriptions and appended drawings.
FIG. 1 shows an embodiment of a cell module 10 in accordance with the instant disclosure. The cell module 10 includes an anode 11, cathode 12 and a proton exchanger membrane (PEM) 13. The anode 11 has a substrate 111 and at least one diamond-like carbon layer (DLC) 112 formed on the substrate. The cathode 12 connects to the other side of the PEM 13 opposite to the anode 11. The anode 11 adheres to one side of lateral faces of the PEM 13 and the cathode 12 adheres to the other thereof.
The substrate 111 is made from carbon cloth, carbon paper, other carbon materials and the combination thereof. At least one DLC layer 112 is formed on the surface of substrate 111 by chemical vapor deposition (CVD). The substrate 111 and DLC layer 112 together form the anode 11. In this embodiment, the substrate 111 is made from carbon paper. As shown in FIG. 2 a, the carbon paper of the substrate 111 is constructed by alternatively woven carbon fabric. In addition, as shown in FIG. 2 b, the substrate 111 is completely covered by the DLC layer 112 after CVD. The preferred thickness of the DLC layer 112 ranges from 2 to 1000 μm. Furthermore, the properties of the DLC layer 112 can be modified by adding trace of different dopants; for example, to increase the conductivity of the anode 11, boron and nitrogen are used. When hydrogen and fluoride are doped, the DLC layer 112 becomes more hydrophobic. The mass percentage of the dopant is preferably between 10 to 30 percentages of the DLC layer 112 mass.
The cathode 12 is made of conductive materials, selected from platinum (Pt), copper (Cu), silicon dioxide (SiO₂), carbon dioxide (CO₂), carbon cloth, carbon paper, carbon materials and the combination thereof. In this embodiment, the cathode 12 is made from carbon paper. The size of the anode and cathode is about 3 by 3 cm². The PEM 13 is made of Nafion, which is a sulfonated tetrafluoroethylene based synthetic polymer. The preferred thickness of the PEM 13 ranges from 2 to 1000 μm. The cell module 10 is assembled by hot pressing (temperature: 130° C.) the anode 11 and cathode 12 to tightly adhere on either side of the PEM 13 separately and using CVD to accumulate DLC layer 112 over the anode 11.
The present disclosure also provides an ozone generator 1 based on the aforementioned cell module 10. The ozone generator 1 includes the cell module 10, a tank unit 20 and at least two conduction plates 30. The tank unit 20 has a plurality of water inlet 23 and a plurality of water outlet 24. The ozone module 10 is fixed and flanked by the conduction plates 30 over anode 11 and cathode 12 respectively.
FIG. 3 shows an embodiment of the ozone generator in accordance with the present disclosure. The tank unit 20 is made of anti-oxidized materials; for example, poly(methyl methacrylate) (PMMA). The tank unit 20 includes a anode water tank 21 and a cathode water tank 22. The first and cathode water tank 21, 22 have a plurality of corresponding fastening holes respectively (not shown in the diagram). The water inlets 23 are arranged on one side of the first and cathode water tank 21, 22 over the lower halves thereof. On the other hand, the water outlets 24 are arranged opposite to the water inlets 23 over the same side of the first and cathode water tank 21, 22.
The conduction plates 30 are made of metallic materials; for example, stainless steel and aluminum. The conduction plates 30 have a frame portion 31 and a connection portion 32 extending from the frame portion 31. In this embodiment, the frame portion 31 is a rectangle slab. Suitable material for the frame portion 31 includes stainless steel and aluminum. The connection portion 32 is preferably a rod made of the same material. The detail regarding the cell module 10 can be referred to the foregoing description.
The ozone generator 1 is assembled in the following order in a stacked configuration: the anode water tank 21, one of the conduction plates 30, the cell module 10, another one of the conduction plates 30 and the cathode water tank 22. After the initial assembly, the first and cathode water tank 21, 22 are bolted together via the corresponding fastening holes. Inside the tank unit 20 the cell module 10 is sandwiched between the conduction plates 30. In other words, the frame portion 31 of one of the conduction plates 30 contacts the DLC layer 112 of the anode 11; the frame portion 31 of another one of the conduction plates 30 contacts the cathode. The connection portion 32 of the conduction plates 30 protrudes out of the tank unit 20, and is configured to establish electrical connection from a power source to the ozone generator 1.
The present disclosure further provides a method for ozone production by the aforementioned ozone generator 1, which includes steps of adding tap water to the tank unit 20 at a rate of 1 L/min via the water inlets 23 and supplying DC power to the anode 11 and the cathode 12 through the connection portion 32 respectively. The preferred voltage level of the DC power ranges between 3 to 15 volts.
FIG. 4 shows a graph of the current versus electrical potential of Pt and the nitride DLC (DLC/N) layer 112. The redox potential of the DLC/N layer (2.7V) is higher than the redox potential of Pt (1.7V). A full reaction potential of electrolysis of water to generate oxygen and hydrogen is 1.23V while a higher potential, 1.51V, is needed to generate oxygen, hydrogen and ozone. Furthermore, a half reaction potential of the molecular oxygen reacting with oxygen free radicals to form ozone is 2.07V. That is to say Pt can act as an electro-catalyst for electrolysis of water to produce hydrogen and oxygen yet the DLC/N layer can sustain higher potential to produce hydrogen, oxygen and ozone altogether.
FIG. 5 shows a graph of ozone concentration in the tank unit 20 versus time. As voltage is applied to the cell module 10, ozone and hydrogen ions are formed over the anode 11. The generated ozone dissolves in the water, which can be used for washing purposes, and the hydrogen ions pass through the PEM 13 to the cathode 12 to form hydrogen and complete the full reaction. The ozone concentration may be determined by measuring the corresponding redox potential in the tank unit 20.
FIG. 6 shows a graph of E. coli cell count in a solution. The solution is mixed with the water containing ozone. After 10 minutes, the E. coli cell count reduced 15%, showing that the ozone in the water is potent to sterilize in a solution. In addition, using the water containing ozone to wash vegetables with pesticides can greatly reduce the pesticides concentration to a level substantially close to none.
A second embodiment of the present disclosure is shown in FIG. 7, which is a graph showing redox potential versus time. This embodiment shows ozone production rate with different numbers of the DLC/N layer 112. In FIG. 7, a line with square data points has a single layer of the DLC/N layer 112 on the substrate 111, a line with round data points has two layers of the DLC/N layer 112 and a line with triangle data points has six layers of DLC/N layer 112.
The result shows that when multiple layers of DLC/N layer 112 are formed on the substrate 111, the anode 11 has higher redox potential. The preferred number of layers is between 2 to 6 so the ozone generator 1 can produce high concentration ozone and prolong the lifespan of anode 11 because of the stability of the plurality DLC/N layers 112.
A third embodiment is shown in FIG. 8, which shows a graph of another redox potential versus time. In this embodiment, the anode 11 has 6 layers of the DLC/N layer 112, but the cell module 10 has different sizes of reaction area. The reaction area is equivalent to the area combination of the anode 11 and cathode 12. In FIG. 8, a line joined by round data point represents the reaction area of 64 cm²; a line joined by square data points represents the reaction area of 9 cm². The result shows that as the reaction area increases, the redox potential increases as well. That is to say the ozone concentration produced by the ozone generator 1 is in directly proportional to the reaction area.
In summary, the instant disclosure provides the cell module 10 and the ozone generator 1 using the same is simple in structure, lower in manufacturing cost, and stable. The materials used for the ozone generator 1 also have the feature of low environmental impact. The anode 11 is inexpensive yet having higher conductivity compared to the conventional metallic or conductive boron diamond anodes. The physical properties of the DLC layer 112 are in accordance with the diamond, which is resistant to corrosion and strong solutes so to prolong the lifespan of the ozone generator 1. Also, the ozone generator 1 is suitable for long period operation because the voltage and power required thereof are lower. Additionally, the method for ozone production yields higher concentration ozone without toxic side products.
The descriptions illustrated supra set forth simply the preferred embodiments of the present disclosure; however, the characteristics of the present disclosure are by no means restricted thereto. All changes, alternations, or modifications conveniently considered by those skilled in the art are deemed to be encompassed within the scope of the present disclosure delineated by the following claims.

Claims

What is claimed is:

1. A cell module comprising:

a proton exchange membrane;

an anode, including a substrate and at least one diamond-like carbon layer formed on a surface thereof, adhered to one side of the proton exchange membrane;

a cathode, corresponding to the anode, adhered the opposite side of the proton exchange membrane.

2. The cell module according to claim 1, wherein the proton exchange membrane material is formed by a sulfonated tetrafluoroethylene based material.

3. The cell module according to claim 1, wherein the substrate is made of a material selected from the group consisting of carbon cloth, carbon paper and the combination thereof, and the anode is made of a material selected from the groups consisting of platinum, copper, silicon dioxide, carbon dioxide, carbon cloth, carbon paper, carbon materials and the combination thereof.

4. The cell module according to claim 1, wherein the diamond-like carbon layer further comprises a dopant.

5. The cell module according to claim 4, wherein the dopant is nitrogen and the mass fraction is between 10 to 30 percentages of the diamond-like carbon layer.

6. The cell module according to claim 1, wherein the diamond-like carbon layer is multi-layered.

7. The cell module according to claim 1, wherein the diamond-like carbon layer has two to six layers.

8. An ozone generator, including:

a tank with a plurality of water inlets and a plurality of water outlets;

a cell module disposed in the tank, including a proton exchange membrane, an anode and a corresponding cathode, wherein the anode adheres to one side of the proton exchange membrane, the anode includes a substrate and at least one diamond-like carbon layer, the cathode adheres to the other side of the proton exchange membrane, and at least two conduction plates disposed on either side of the cell module.

9. The ozone generator according to claim 8, wherein the diamond-like carbon layer further comprises a dopant.

10. The ozone generator according to claim 8, wherein the dopant is nitrogen and the mass fraction is between 10 to 30 percentages of the diamond-like carbon layer.

11. The ozone generator according to claim 8, wherein the diamond-like carbon layer is a multi-layered.

12. The ozone generator according to claim 8, wherein the diamond-like carbon layer has two to six layers.

13. The ozone generator according to claim 8, wherein the tank is made of anti-oxidized materials and the tank includes a anode water tank and a cathode water tank, wherein the first and cathode water tank have a plurality of corresponding fastening holes.

14. The ozone generator according to claim 8, wherein the plurality of water inlets open at lower halves on one side of the first and cathode water tank and the plurality of water outlets open at upper halves, opposite to the water inlets, of the first and cathode water tank.

15. The ozone generator according to claim 8, wherein the proton exchange membrane is formed by a material based on sulfonated tetrafluoroethylene.

16. The ozone generator according to claim 8, wherein the substrate is made of a material selected from the group consisting of carbon cloth, carbon paper and the combination thereof, and the anode is made of a material selected from the groups consisting of platinum, copper, silicon dioxide, carbon dioxide, carbon cloth, carbon paper, carbon materials and the combination thereof.

17. The ozone generator according to claim 8, wherein each of the conduction plates includes a frame portion and a connection portion formed by an extension from the frame portion.