Ozone gas was discovered by a German Physician and Chemist named Christian Schonebein at University of Basel in 1840. All through his experiments, he determined a completely unique smell that was being emitted by his electrifier.The word ozone is derived from a Greek Ozein that means Scent.
The very first ozone generator was made by German Scientist and Inventor Ernst Werner Von Siemens. Studies and researches approximately Ozone endured in Europe, and later, by early 1900s,first ever large scale application of ozone was made in France. Ozone was firstly used to purify drinking water in 1906, in France.
Many countries are using ozone for purification of water supply throughout the 20th century,discovery of Chlorine played an important role in usage of ozone. We can call chlorine as a suitable alternative to ozone, but due to the production/ discovery of potential side effects, forced people to move back to use ozone as a disinfectant. We know that oxidation potential of ozone is 2.07eV which represents that ozone is an excellent oxidizer in water or air, which can be converted back to oxygen as well as an ideal for chemical synthesis and ozonolysis reactions, while on the other hand, oxidation potential of chlorine is 1.36eV, which shows that it is very toxic and poisonous.
Ozone is a powerful oxidant, as well as an unstable gas, which represents that a part of residual ozone that has not treated, breaks down quickly and then converted back to oxygen again.
Ozone is considered as one of the most basic element of nature, that can be referred to as oxidizing force. As ozone generators have been discovered, we can use ozone as a best purifier that can benefit our lives. As we are familiar that hundreds of thousands of disease are being caused by indoor pollution every year. so it is necessary to have a clean air and water for best possible survival. Ozone has achieved a tremendous popularity as a natural purifier due to its flexibility of solving many problems. Ozone is 15 times more powerful than chlorine and works 3000 times faster. Ozone is used for destroying bacteria, spores and other harmful particles, that make it sure that water is now suitable for reuse. For removing the suspended solid particles and by-products, excellent filtration method is needed. Ozone if found in earths stratosphere and formed through photochemical decomposition. It has a wide pH range and reacts with bacteria and viruses a swell as it has a short reaction time. On the other hand, it can also be used to remove a variety of organic, inorganic as well as odor problems.
Ozone that is present in stratosphere is beneficial for earth due to its quality of absorbing hazardous short ultraviolet light. However, many harmful secondary pollutants and fine particles are produced by the reaction of ozone with active volatile organic compounds. Now a days, ozone is finding its extreme increase due to its quality of pollution free oxidant including deodourization, decolourization, disinfection bleaching processes as well as gas treatment and chemical synthesis. All these processes require less energy than in alternative chlorination process.
Due to increase in population year by year, demand of water resources is increasing in urbanization, industrialization and for agricultural usage. By implementing the concept of sustainabilityand water conservation, can help to reduce the globally water shortage. As we are familiar that rainfall is a great blessing and important element of countrys natural resources. We can boost the economy of a country by using the maximum natural resources. On the other hand, it has a severe effect on sustainability of environment. By taking into account the facts of green building concepts, it brings away a vast array of practices and techniques to minimize and eliminate the impacts of buildings on environment as well as human health. We can also implement the concept of green building to overcome the problem of water shortage through rain water harvesting system. Depending upon the geographic location of area, quality and quantity of collected rain water varies with respect to area. And has a huge potential as an alternative water source.
Rainfall is considered to be as a primary source for drinking all water as it unlimited source on planet. Malaysia is one of those countries that are located at equator zone, that received maximum of rain in an year and suits to build a rainwater harvesting system that is a practice to collect the water before it run off into a river and become groundwater. However, with the introduction of green building concept, has opened the opportunity towards harvesting the rainwater. It is a common observation, that rainwater gets polluted due to many environmental factors and without treatment, it is not suitable for usage purpose. Rainwater that is harvested from roofs can contain animal and birds faces as well as mosses. It also contain dust that originates from urban pollution, pesticides and inorganic ions from sea that may include calcium, magnesium, potassium, sodium and chlorine as well as dissolved gases that includes oxides of carbon, nitrogen and sulphur. Ozone treatment method for rainwater is considered environmentally friendly because it does not require addition of chemicals or heating energy.
By taking into account the Malaysian scenario, ozone rain water treatment is considered as a new and best approach in Malaysia. Due to surrounding of Malaysia in islands, source water comes mostly from ground water.
Ozone generator Technologies
Ozone generators are classified into two categories:
Air fed ozone generators
High performance ozone generators
Air fed ozone generators:
These generators are in use since early 2000s. Clean air supply is supplied to these generators from ventilation. These generators have low cleaning capacity and are used in strret food establishment, cafes and smaller restaurants. Ozone generators are used in the applications that are defined by EU standard EN 16282-8. This standard specifies requirements including design, construction and operation of installations for treating aerosol in kitchens that includes technical safety and hygienic features.
High performance ozone generators
Restaurants and commercial kitchens consisting of deep fryer and grill require a high functional air cleaning system. A high purification capacity is required to get rid of grease and cooking odors in the exhaust air. Central high performance ozone system distributes ozone by means of ozone resistant hoses to several injection points. The RENA Kitchen solutions becomes cost effective due to its high cleaning capacity of upto 12000I/S.
Ozone Formation and Decomposition
Formation of ozone from molecular oxygen can be represented by the equation that represents that if both oxygen molecules are in their fundamental energy states requiring an energy input of 142.3kJ per mole of ozone produced. We are familiar with the mass of ozone that is 48g and for the formation of complete ozone, required theoretical energy is 1220g of ozone per kilowatthour. Most commonly used process for ozone generation is passage of an oxygen bearing gas through an electrical discharge. In this process, initial dissociation reaction requires an energy of 5.1eV per molecule of oxygen that is provided by the bombarding electron. As the temperature increases, half life of ozone goes on decreasing. By the bombardment of electrons, ozone molecules are separated and they can recombine each other as well as with oxygen atoms and oxygen molecules.
Review of ozone generators:
Methods for production of Ozone:
For the production of ozone, a lot of researches and methods have been applied and implemented for the past several years. There are four recognized methods that we are most familiar with:
Any of the above mentioned methods for the generation of ozone, relies on upon the energy applied to break the bonds that holds the oxygen atoms in a molecular form and allows them to dissociate and then reform as ozone.
It is defined as when a stable partial discharge occurs at free electrodes in a gaseous dielectrics, it is referred to as corona. In corona discharge ozone generator, electrical discharge will take place in air gap within corona cell designed specifically to split oxygen molecule and produce ozone. In this method, dielectric is used the distribute the flow of electron across the air gap to spread the flow of electron to a maximum possible flow of oxygen. A dielectric discharge is used to create corona because a single formation of spark from anode to cathode will find new oxygen molecules in between and will produce some ozone. By using a dielectric, this spark is spread over a greater area and will create true corona.
While the production of ozone by corona discharge method, high voltage energy is transferredto break oxygen molecules, allowing the formation of three atom oxygen, ozone. This method is most commonly these days.
We are much familiar that formation of ozone from oxygen requires an energy means it is an endothermic reaction. Oxygen molecule will absorb the energy in ground state and will dissociate to degree dependent energy and will particular wavelength of the absorbed light, when it is exposed to light. Each wavelength of light experiences a different reaction. Breaking of oxygen molecules requires a higher yield at wavelengths less than 200nm. For an effective ozone production, it is necessary to utilize short wavelength ~185nm.
We can use 185nm ultraviolet lamp to produce ozone from either air or by oxygen gas.
A process in which an electric current is passed through a liquid, that will cause a chemical reaction, further resulting in evolution of gases. While producing ozone, water is used as an electrolyte that will lead to direct diffusion. One can determine the concentration of ozone production by the current density.
High energy irradiation of oxygen by radioactive rays can lead to formation of ozone. This method is independent of temperature and pressure. Thermodynamic characteristics of generation of ozone are very favorable. This method is usually used for practice only due to complicated application as well as danger of radioactive elements.