THERMOGRAVIMETRIC KINETIC ANALYSIS OF NANNOCHLOROPSIS OCULATA COMBUSTION IN AIR ATMOSPHERE

The use of fossil fuels, in the long term faces problems due to the limited amount of resources and their greenhouse effect caused by CO2 emissions from combustion processes (Khan et al., 2009; Tabatabaei et al., 2011). Fossil fuels have the greatest contribution to greenhouse gas emissions (Ugarte et al., 2000; Tabatabaei et al., 2011). In 2006, fossil fuels CO2 emissions accounted for nearly 29 billion tons (Banerjee et al., 2002) and became a serious threat for environment and human life due to their global warming impact (Sawayama et al., 1999). Hence, exploring alternative renewable fuels whose sustainability are assured and friendly environment suppressing the greenhouse effect is urgent to replace fossil fuels.

Microalgae is a potential source of alternative fuels for fossil fuels substitution, due to their fast growth rate (Ross et al., 2010) that will continuously ensure the availability and their ability to absorb large amounts of CO2 in the photosynthesis process which will neutralize the CO2 generated from their combustion process. Microalgal biomasses are generally doubled within 24 hours. The times required for the doubling of biomass during the exponential growth are commonly as short as 3.5 hours (Chisti, 2007). Commercial cultivation of microalgae is able to achieve productivity of 15 g dry biomass per cm2 per day or 54 ton/hectare/year (Metting, 1996). Microalgae produce 30-100 times more energy per hectare than the terrestrial crops (Demirbas, 2010). Their biomass contains about 50% carbon by dry weight and all carbon is usually derived from carbon dioxide (Mirón et al., 2003). To produce 100 tons of algal biomass requires about 183 tons of CO2 (Chisti, 2007), thereby producing of microalgal biomass is essential...

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...rature profile in the radiation part of furnace. Therefore a number of experiments are performed and generally uses thermogravimetric analysis (TGA). TGA is useful in finding out the thermal behavior of biomass fuels. The mass loss rate as a function of temperature and time is used to estimate the kinetic parameters of thermal decomposition reaction (Wongsiriamnuay and Tippayawong, 2010). However, the kinetics of N. oculata combustion in air atmosphere has not been found in the literature.

In this work, the thermal decomposition behavior of the N. oculata during the combustion process in air atmosphere is investigated by thermogravimetric technique. Mass loss, the mass loss rate and differential thermal are analyzed at varying heating rates to predict the thermal behavior of the material. Decomposition kinetic parameters are evaluated by Kissinger and Ozawa methods.