Electrolysis: processes – compositions used therein – and methods – Electrolytic analysis or testing – For sulfur or sulfur containing compound
Reexamination Certificate
1999-12-17
2003-09-23
Nguyen, Nam (Department: 1753)
Electrolysis: processes, compositions used therein, and methods
Electrolytic analysis or testing
For sulfur or sulfur containing compound
C204S426000
Reexamination Certificate
active
06623620
ABSTRACT:
TECHNICAL FIELD
The present invention is directed to an electrochemical micro-sensor device for detecting or monitoring sulfur dioxide. More particularly, the invention is directed to a thick film electrochemical micro-sensor device capable of detecting and monitoring sulfur dioxide emissions.
BACKGROUND OF THE INVENTION
Acidic deposition, which includes acid rain, acid snow, and even acidic dusts, is currently a major environmental issue. It is not only a critical threat to the natural world but also to the world of man. In recent years, acidic deposition has increased greatly which, in turn, amplifies its effects. It has depleted the fisheries in various lakes around the world. It has also caused the destruction of great forests around the world, especially in Germany. Moreover, acidic deposition is, in itself, damaging human health in various locations. Finally, acidic deposition poses a great threat to the preservation of human history. All these problems will be discussed more thoroughly in the following paragraphs.
First of all, acidic deposition is a main factor behind the depletion of aquatic life in various lakes whether natural or man-made. When acidic deposition occurs, the acidic chemicals mix with the water in the lakes, gradually increasing the acidity of the lakes. Because all species of aquatic life forms can only reproduce and certain eggs can only hatch at certain acidic levels, these species are unable to reproduce regularly if they can reproduce at all. This is a major concern for various fish species as well as certain small shrimps and mollusks. Furthermore, the acidic chemicals from repeated acidic deposition leaches dangerous metals, such as mercury and lead, from the soil at the lake bottoms and into the lake waters. Eventually, the concentration of these toxic-metal substances in the lake reach a certain level where the organisms living within the lake waters start dying off specie by specie. After a certain time, these acidified lakes will look crystal clear, but that will be because there will be nothing living in the lakes except maybe a couple of algae species.
Acidic deposition is also a main cause behind the devastation of major forests around the world, especially in Germany. The acidic deposition descends into the forests and permeates through the soil. Similar to its effects on the lakes, the acidic chemicals once again release dangerous chemicals, such as aluminum, except this time from the soil. These metals instigate a slow process which kills the trees. Another effect of acidic deposition is that the acidic chemicals, once in the soil, displace the nutrients, such as calcium, which are important to trees and other plant life, from the ground. Because of this displacement, the plant life in such forests is unable to absorb the nutrients necessary for its survival from the soil at forest bottoms.
Acidic deposition is not only an environmental problem but also a problem for humans because it is damaging to human health as well. First of all, the acidic chemicals from acidic deposition, especially from acid rain and acid snow, have the ability to leach toxic metals, such as copper and lead, into drinking water for humans. The presence of these metals in everyday drinking water would obviously harm the health of humans who intake this water. Moreover, the acidic chemicals have been found to be the main sources behind the outbreaks of gastroenteritis in places such as the Adirondack Mountains. Furthermore, when in high concentrations, the acids are capable of irritating the human respiratory system causing problems in everyday functions such as breathing. Finally, medical institutions have also suspected that the acidic content of rain, snow, and dust may be the cause of some types of chronic bronchitis and emphysema which would eventually lead to chronic heart disease.
Lastly, another major problem initiated by acid rain is the destruction of human history by the deterioration of man-made historical architectures. History buildings, such as the magnificent Acropolis in Greece and the stunning Pantheon in Rome, have survived the weathering from rain and snow and wind for hundreds of centuries. However, in recent years, with the rapid increase in acidity in rain, snow, and even dust, these famous buildings representing the progress and history of mankind have deteriorated at higher and higher rates. This deterioration is an obvious effect of the corrosive acidic content of the rain. Because these structures are made mostly in limestone and marble which are basic, the acid reacts with the stones and corrodes the surfaces. However, the deterioration not only occurs with stone monuments and buildings, but also affects the metal structures by increasing the rate of oxidation or rust of the metal. Therefore, acid deposition not only plays a significant part in the destruction of the environment but it also affects humans through damaging human health and deteriorating the traces of stepping stones in human history.
There are three main types of acidic deposition. Acidic dust or ashes are acidic chemicals that descend from the sky in the form of dry flaky solids. Another type of acidic deposition is acidic snow or sleet. This type of acidic deposition occurs with the freezing or crystallization of the acid rain while or before it precipitates from the atmosphere. Finally, most importantly, there is acid rain. Acid rain occurs when the acidic compounds released in gaseous form make contact with the moisture in the atmosphere. Then, when the moisture reaches a certain level and descends from the sky, the acidic compounds have already combined with the rain droplets making the rain acidic.
There are two main groups of gases that contribute to the formation of acidic deposition. The first group includes the group of nitrogen oxides. Its main contributors are automobiles. Another, which is the major contributor to acidic deposition, is sulfur dioxide which is released mainly from the smokestacks of industrial buildings. Outside of these two groups, there are some other minor groups of gases that also contribute to acidic deposition, such as carbon dioxide. When these various acidic gases are released into the atmosphere, they come in contact with the moisture in the atmosphere. Then, with the water, the gases form acidic solutions which fall to the ground in the form of acid rain, acid snow, or acidic dust as described in the previous paragraph.
As mentioned previously, the main contributor to acidic deposition is sulfur dioxide. Sulfur dioxide is usually produced as a result of burning coal and oil. It is also often produced as a superfluous product by the processes in refineries, pulp and paper mills, as well as metal smelters. When released into the atmosphere, sulfur dioxide and other oxides of sulfur have the ability to form sulfates with the oxygen as well as aerosols of sulfurous and sulfuric acids with water vapor. All these chemicals eventually come down to the ground in various forms of acidic deposition. Therefore, sulfur dioxide harms the environment as well as people in the form of acidic deposition. However, in high concentrations, the sulfur dioxide, by itself, is also a problem. It, by itself, possesses the ability to aggravate already present respiratory and cardiovascular diseases including asthma, bronchitis, and emphysema.
Therefore, in order to help in reducing acid rain, the amount of sulfur dioxide released needs to be reduced. Although there are currently processes such as the use of scrubbers or calcium carbonate released into the sulfur dioxide emissions to neutralize the gas, the processes are expensive, and they also cannot monitor the sulfur dioxide levels. Therefore, it is believed that the most effective way to reduce sulfur dioxide would be through monitoring the sulfur dioxide released from industrial smokestacks. This could lead to a more effective way to regulate sulfur dioxide emission levels. There are many ways to measure sulfur dioxide, and one of these ways is through using our newly developed micro-sensor and senso
Dudik Laurie A.
Lai Ann
Liu Chung-Chiun
Hathaway Brown School
Nguyen Nam
Noguerola Alex
Renner Kenner Greive Bobak Taylor & Weber
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