The impact of MgCO3 and Al2O3 additives on the thermal behavior of Spirulina platensis (SP) biomass during combustion in a thermal analyzer was evaluated to understand their catalytic effect in the decomposition process. The samples were pure SP and a mixture of SP and additives at mass fractions of 3, 6, and 9 (wt,%). Each sample of around 8.5 mg was mounted in a thermobalance and subjected to a furnace on a heating program of 10 o C/min. The 100 ml/min air atmosphere was kept continuously flowing during the combustion process from 30-1200 o C. The thermal behavior of the sample was then characterized from the thermogravimetric (TG) and derivative thermogravimetric (DTG) curves, those were recorded by a computer during the experiment. The Horowitz-Metzger method was used to evaluate the impact of additives on the kinetic parameters of the samples. The results indicated that the presence of additives shifted the main decomposition stage toward a lesser temperature. The rate of mass loss (ML) in the main decomposition zone decreased in the 1 st peak and increased in the 2 nd , in accordance with the increase in the fraction of additives. This indicates that additives play different roles during the decomposition process. The mass mean activation energy (Em) increased at the additive fraction of 3% for both MgCO3 and Al2O3, as well as at 6% MgCO3 compared to combustion with no additives. Conversely, the presence of greater additives promoted a shift in Em toward smaller values. These results confirm that both additives significantly influenced the thermal behavior and kinetics of the SP combustion.

The catalytic effect of TiO2 during the pyrolysis of Tetraselmis chuii (T.chuii) microalgae was studied using a thermal analyzer. Pyrolysis experiment was occupied on the sample that was a mixture of 10 mg microalgae and 5% TiO2 and the result was compared with microalgae and microalgae with 3% TiO2. The presence of 5% TiO2 into the microalgae affected decreasing the initial and final temperatures of degradation by approximately 17 °C (at Stage 2) and 35 °C (at Stage 3) respectively. The activation energy that was evaluated using the Coats-Redfern method for Stage 2 indicated the decreasing value of around 18.39 kJ/mol and increases in Stage 3 by 3.27 kJ/mol. The overall results indicated that addition of TiO2 has significantly influenced the conversion process of T. chuii microalgae.

Thermogravimetric analyzer had been occupied to investigate the behavior of co-combustion between microalgae Spirulina platensis and synthetic waste. The powder of microalgae and synthetic waste were mixed in the same ratio of 50/50. Around 10 mg of the sample was heated up in the chamber under air atmosphere flowrate of 100 ml/min at a heating rate of 10 0 C/min. The results showed that the sample blend is undergoing thermal degradation in the three stages. The most massive reaction occurred in the second stage in which around 74% of the mass degraded and combusted. The activation energy in the main combustion reaction zone according to the method of Horowitz-Metzger was 57.77 kJ/mol.

Utilizing waste biomass as a reserve energy source can play an essential role in reducing expanding fossil fuel’s environmental impact. This paper presented an analysis of physical, chemical, morphological, calorific values and porosity of biomass from coconut shell waste (CSW) as an alternative for biofuel feedstock. The physical properties of CSW biomass were dominated by volatile matter and fixed carbon content of 73.8 and 22.7 (wt.%, DB), respectively. The calorific value is 20.39 MJ/kg, giving a significant energy effect when the biomass is burned. The chemical properties of CSW biomass were dominated by C and O content of 41.04 and 57.47 (wt.%), respectively, contributing most of the oxygen to the thermal process. However, most elements of chemical properties contributed to the formation of ash in the combustor, including minor and major elements (S, K, Si, Al, P, Cl, Ca, Mg, and Fe). Besides, they had a negative effect in the form of slagging in the combustion residue. The porosity analysis of CSW biomass was 67.30 – 72.92%, which was able to increase the size of char particles during the thermal process. The analysis of physicochemical properties and porosity of CSW biomass confirmed that this material could be beneficial as an alternative energy reserve in the future.

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