The TiO2 catalytic combustion of microalgae spirulina platensis-synthetic waste blend: Thermal characteristics, kinetic and thermodynamic investigation

Abstract. This paper evaluates the catalytic impact of TiO2 addition on the combustion behavior of the microalgae Spirulina platensis (SP) and synthetic waste (SW) blend using a thermogravimetric analyzer. The blend ratio of 30SP/70SW, 50SP/50SW, and 70SP/30SW (wt,%) with 5%TiO2 were used for each experiment. The results show that the blended fuels with and without 5%TiO2 decomposed in three stages, with the main combustion reaction taking place in the second stage. Assessment of the second stage revealed that the decomposition could be divided into two zones. Zone I started at 166-191 oC and finished at around 360-395 oC. Zone II started at the end temperature of Zone I and finished at around 490-507 oC. The presence of 5% TiO2 forced the mass loss rate of the samples in Zone II toward a higher rate, except for the 30SP/70SW. The kinetic evaluation performed by using the Coats-Redfern method was implemented on the six selected models, i.e., three diffusion models (parabolic law (D1), valensi equation (D2), Ginstling-Broushtein equation (D3)), two-phase interfacial reaction model (shrinkage geometrical column (S1) and shrinkage geometrical spherical (S2)) and power-law model (P). The results showed that 5% of TiO2 in the samples significantly reduced the activation energies.