Tag: air pollution and its control

Antiknocking agents are the chemical derivatives that are added to petrol. These agents increase the octane number of petrol due to which the pressure and temperature of petrol increases and so these protect petrol from detonation at low pressure. This is done to maintain the quality of the engines. Tetramethyl or tetraethyl lead, dibromoethane, benzole toluene are used as the antiknocking agents.

Unleaded petrol is not doped with lead so it has a high knocking ability. It means it can be ignited before the actual ignition spark occurs. This is harmful to the engines. Lead is not used because it has shown severe adverse effects on the environment. Instead, methyl tertiary butyl ether is added which is easily miscible with petrol. However, it also has shown the carcinogenic properties.

Incineration is also called as a thermal process, it involves combustion of organic substances contained in waste material. It converts the waste material into ash, gases, particles and heat which are then put into the application for generation of electricity. The incinerator is the device where waste is burnt e.g. furnace. Now incinerators are equipped with systems to reduce the emission of highly toxic gases during the process. The output of incinerator is gases, particles and heat thus for controlling particulate pollutant filtration and precipitators are installed to clean out the gases as a result of incineration. These do not have any control over particulate pollutants.

Gaseous pollutants include dust, aerosols, suspended particulate matter etc. that are removed by the principle of adsorption. Electrostatic precipitators, cyclones, scrubbers etc. are some devices that can control the gaseous pollutants. These are either made to be retained by the electrostatic field or by pressure. Pyrolisis and incineration are performed for solid pollutants. Arrestors are used to protect the types of equipment from the damaging effect of lightning.

Electrostatic precipitators (ESP)  is a device that removes suspended dust particles from a gas or exhaust by applying a high-voltage electrostatic charge and collecting the particles on charged plates. Electrostatic precipitator, also called electrostatic air cleaner, a device that uses an electric charge to remove certain impurities—either solid particles or liquid droplets—from the air or other gases.

A pyrogallol is also called as 1,2,3-trihydroxybenzene. It is a benzenetriol. It is a reducing agent. It is used as a developer in photography. It is also used as a coupling agent in printing. It undergoes rapid autooxidation in alkaline solution. Hence, its alkaline solution is used in the gas analysis because it absorbs oxygen.