Abstract:
Due to the rapid growth of vehicle usage in Sri Lanka, the waste tire generation is increasing
exponentially and has become a serious environmental and social issue. Landfilling and burning
of tires in open environment are not sustainable waste management solutions for the disposal of
waste tires. The burning of tires produce air pollutants such as carbon monoxide (CO), sulphur
oxides (SOx), nitrogen oxides (NOx), poly-aromatic hydrocarbons (PAH) and other toxic
congers. These pollutants affect the human health causing skin rashes, eye irritation, respiratory
problems and even cancers. As a sustainable waste management solution, pyrolysis can be
recognized to dispose waste tires. Pyrolysis is a process of thermochemical decomposition of
organic as well as inorganic material at elevated temperature in the absence of oxygen. The
mechanism of pyrolysis process involves the molecular breakdown of larger molecules into
smaller molecules. In the pyrolysis process, waste tires are used as a feedstock and heated up to
400-450° C in a closed reactor in absence of oxygen. During pyrolysis, waste tires are broken
down in to smaller molecules such as pyrolysis oil (45-55%), pyrolysis gas (8-10%), carbon
black (30-35%) and steel (10-15%). Pyrolytic gas can be used as a fuel source for domestic
cooking purposes pyrolytic oil is suitable as an alternative fuel for various industrial applications
due to its high net calorific value. Liquid fraction consists of xylene, toluene, styrene, and
limonene. Pyrolytic char can be converted into carbon black by chemical and physical treatments
Purified Carbon black can be used as a heating material or as a pigment in tire and plastic
industry. Gaseous fraction mainly consists of a mixture of short chain hydrocarbons, and carbon
monoxides/hydrogen mixture which is known as “syn gas”. Syngas is widely used a starting
materials to produce gasoline. Syngas fraction consists of 11.21% of carbon dioxide, 26.82% of
hydrogen 24.5% of methane 12.12% of ethane. CHNS analysis was completed using Perkin
Elmer 2400 serious. CHNS analyses results confirmed that purified carbon black sample contain
78.31% of C, 1.36% of H, 0.55% of N and 2.57% of S. Metal oxides analysis was completed
using Horiba scientific XGT 5200 X-ray analytical microscope. This confirmed that purified
carbon black consist trace amount of Silica, Sulphur and Zinc. Particle size distribution was
conducted using Malvern instruments master sizer 3000 particle size analyser. Particle size
varies between 20 to 800 micrometers.
