Kinetic evaluation of Pachira aquatica Aubl biomass slow pyrolysis towards to biochar production

Abstract

The abrupt climate change, caused by the anthropogenic activities in the environment, intensified the search for sustainable sources of energy aiming reduce the dependence on fossil fuels. In this study, a multivariate study design was applied within a batch reactor system to determine the influence of process variables and kinetic parameters of slow pyrolysis of Pachira aquatica Aubl fruit peel towards biochar generation. The statistical evaluation of Box Behnken planning model was applied and showed good adjustment to the model establishing the model that describes the significant effect of variables behavior. The maximum biochar yield (41.22%) was observed were temperature (T) = 406 °C, heating rate β = 2 °C min⁻¹, and residence time t_R = 60 min, under nitrogen atmosphere. It is also observed that temperature was the most substantial influence on the process, followed by heating rate and the remaining process variables did not exhibit significant individual effects. The empirical model obtained was applied into mass change equation aiming calculate the activation energy (Ea)=77.10 kJ mol⁻¹ and frequency factor (A₀)= 6.28 × 10¹⁰ s⁻¹. The low activation energy in maximum biochar yield region showed a great potential of Pachira aquatica Aubl fruit peel thermoconversion towards to biochar.

Keywords:

• Biochar
• slow pyrolysis
• kinetics
• biomass
• activation energy

Acknowledgments

The authors would like to thank Fundação de Amparo à Pesquisa do Estado da Bahia (FAPESB) for financing of the experimental pyrolysis unit (PLANT π/DCET-UNEB) through the agreement CNV.0076/2013, and Coordenação de aperfeicoamento de pessoal de nivel superior (CAPES) for financial support.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

The data that support the findings of this study are available from the corresponding author, Virgens, C.F., upon reasonable request.

Additional information

Funding

Fapesb and Capes are prominent Brazilian fomentation agencies. Fapesb provided financial support through infrastructure grant CNV.0076/2013 (Project 10.13039/501100006181), while Capes generously awarded master’s scholarships to Juraci Nascimento and Mateus Carvalho.