Topic : Electron Beam Radiation Processing

 By Name : Oladipo Elegbeleye Ayodamope

Outline

IntroductionTypes of RadiationElectron Beam Processing systemSources of Electron BeamApplications of Electron BeamElectron Beam Treatment of Organic

PollutantsBenefits Associated with Electron Beam

ProcessingConclusionsReferences

Introduction Electron beam is the ability of high energy of electrons to alter the chemical

structures of the molecules and its used to either modify or destroy hazardous

organic molecules.

The electron beam radiation processing is a chemical reaction caused in a material

by radiation irradiation. In the radiation processing, electron beam and gamma rays

(-rays) are mainly used.

Types of Radiation

There are two major types of radiation. • The first is the electromagnetic radiation like the -ray and X-ray, and• The other is the corpuscular ray like the α-ray and electron beam.• Presently, electron beam is most commonly used in radiation

chemistry. The -ray, which is discharged when its radioisotope (60Co) decays, is also used as it has high penetration.

Electron Beam Processing System

This is a system in which the electron beam is irradiated to the material

and a certain reaction, such as the chemical reaction, is called

“Electron beam Processing System (EPS)”

Electron beam (EB) means the flow of electrons with energy, and the

energy is obtained as kinetic energy when the electron moves in a high

electric field.

Sources of Electron Beam

Electrons are emitted from solids, liquids and gases. Sources of electron beam include

Thermionic EmissionsPhoto EmissionsField EmissionsPlasma Emissions

Sources of Electron Beam cont’d

Thermionic emissions deals with emissions in the solid state where by electrons are emitted from solids e.g. metals as a result of gaining energy from outside in form of heat. Electrons overcome the barrier and leave the metal if an amount of kinetic energy is equal to the work function of the metal

Sources of Electron Beam cont’d

Photo EmissionsPhoto emissions however is a process in which electrons are emitted from solids (metals) through an interaction with photons. Photons must have energy equal or greater than the work function of the metal.

Field EmissionsField emission, contrary to thermionic, is a cold emission. High amount of acceleration voltage (normally greater than 50KV) is applied to the fine tip of cathode.

Sources of Electron Beam cont’d

Plasma EmissionsIn plasma emissions, a gas discharge under low pressure generates plasma and electrons are emitted in vacuum. These electrons are extracted and accelerated by high voltage through a narrow emission channel, making them align to form a beam. Very high magnetic field is used to focus this beam at the target.

Applications of Electron Beam

Electron beam can be applied in different fields this includes

MedicalElectron beams are able to penetrate medical devices in their final shipping containers. As electrons are scanned through the product, they reduce the microbial population directly breaking the microbial DNA chains as electrons are separated from atoms in the DNA

Specialist (industrial) Applications Electron Beam process achieves a range of different effects via its action as an ionizing radiation source.  The electrons emitted from the source interact with molecules, thus modifying the polymers

Electron Beam Treatment of Organic Pollutants

This are done mainly in the laboratory using electron beam generated non-thermal plasma and they are of two types this include

Flow system and Batch system.

Flow system contains one step which is preparation and irradiation of the gas mixture which contains organic pollutants and are carried out in on-line system.

Batch system contains two steps: first step is to prepare gas mixture which contains organic pollutants into a sealed container and The second step is to put this sealed container under electron beam accelerator for irradiation

Benefits Associated with Electron Beam Processing

Wire and CableAbrasion resistance, high temperature resistance and chemical resistance

Shrink TubingGives shrink back memory to the tubing, but also improves abrasion resistance, chemical resistance, high temperature resistance, tensile strength and flame retardant properties.

FoamAllows the material to expand in thickness and in width. It also improves abrasion resistance and material weight properties.

Benefits Associated with Electron Beam Processing

Waste WaterBreaks down numerous chemicals that contaminate water, such as trichloroethylene, PCB’s and

destroys bacteria.

Curing of CoatingsElimination of solvents and

instant curing.

Food ProcessingEliminates salmonella and

e-coli from meat.

Sterilization of Medical Products Kill microbes.

De-infestatationDestroys bugs and microbes in wheat

rice and spices.

Conclusion

Electron beam technology to treat organic compounds has been

studied for many years. Based on experiments of lab scale in batch

system and flow system and experiments of pilot scale, it was shown

that aliphatic organic compounds are easily decomposed by

electron beam technology and the energy necessary to decompose

aliphatic hydrocarbons is in the order of lower to higher: chlorinated

unsaturated hydrocarbons, chlorinated saturated hydrocarbons,

hydrocarbons.

For aromatic hydrocarbons decomposition in gas phase, energy is

much higher than that used to decompose aliphatic hydrocarbons.

Reference

Atkinson, R.(1987). Kinetics of the Gas-Phase Reactions of Cl Atoms with

Chloro-ethenes at 298.72K and Atmosphere Pressure. International Journal of

Chemical Kinetics, Vol.19, No.12, pp.1097–1105.

Atkinson, R. (1987b). A Structure–Activity Relationship for the Estimation of

Rate Constants for the Gas-Phase Reactions of OH Radicals with Organic

Compounds . International Journal of Chemical Kinetics, Vol.19, No.9, pp.799–

828.

“Current state and Future of Electron beam Processing System,” The Nissin

Electric Review, Vol.31, No.4 (1986)