Dr. Ayokunle O. Balogun | Elizade University, Ilara-Mokin, Ondo State, Nigeria (original) (raw)

Papers by Dr. Ayokunle O. Balogun

Torrefaction experiments were carried out on some Nigerian woody (Albizia pedicellaris (AP), 9

8 Devolatilisation kinetics and pyrolytic analyses were carried out on Tectona grandis (teak) usi... more 8 Devolatilisation kinetics and pyrolytic analyses were carried out on Tectona grandis (teak) using 9 iso-conversional methods (Flynn-Wall-Ozawa and Starink) and analytical Py-GC/MS technique 10

Two woody species of different origins were subjected to Fourier Transform Infrared (FTIR) spectr... more Two woody species of different origins were subjected to Fourier Transform Infrared (FTIR) spectroscopy, thermogravimetric analysis and analytical Py-GC/MS. Flynn-Wall-Ozawa, a model-free technique, was adopted for the decomposition kinetic study of Isoberlinia doka (ID) and Pinus ponderosa (PP). FTIR spectroscopy was employed to determine the level of cellulose crystallinity in the samples under investigation using the total crystallinity and lateral order indices methods. The apparent activation energy appeared as a function of conversion with significant influence from biomass diversity. The apparent activation energy recorded values of 202 to 365 kJ/mol for ID and 205 to 583 kJ/mol for PP. Thus biomass decomposition kinetics is better modeled as a multi-step reaction mechanism. The analytical Py-GC/MS showed the presence of acids, sugars and phenolic compounds in significant proportions for the two biomass samples. There were marked distinctions in both the quantity and the individual compounds detected in the biomass samples that were investigated.

Biomass Conversion and Biorefinery, 2015

Journal of Analytical and Applied Pyrolysis, 2014

ABSTRACT Torrefaction experiments were carried out on some Nigerian woody (Albizia pedicellaris (... more ABSTRACT Torrefaction experiments were carried out on some Nigerian woody (Albizia pedicellaris (AP), Tectona grandis (TK), Terminalia ivorensis (TI)) and non-woody (Sorghum bicolour glume (SBG) and stalk (SBS)) biomass resources. The influence of process conditions and consequent change in the elemental configuration of the biomass samples were observed. Biomass type played a dominant role in the solid yield recording 71% for woody and 58% for non-woody samples at 270 °C, while temperature showed the greatest influence with solid yield dropping from an average of 80% (at 240 °C) to 50% (at 300 °C). Both volatile matter and fixed carbon contents experienced significant changes after torrefaction and a decline in O/C ratio from 0.6 to 0.3 was noted. Among the woody biomass, TI experienced the highest increase in higher heating value (HHV) of approximately 38% as compared to AP (32%) and TK (32%), and was subsequently selected for decomposition kinetic study. The decomposition kinetics showed that activation energy (E(α)) for the hemicellulose degradation stage ranged between 137 and 197 kJ mol−1 for conversion (α) between 0.1 and 0.24 implying that biomass kinetics within this decomposition region is a multi-step reaction. The GC/MS analytical technique revealed that the presence of levoglucosan was highest (7.1%) in woody biomass, while phenolic compounds made up more than one-third of the group of compounds identified.

Waste and Biomass Valorization, 2014

ABSTRACT An investigation into the thermal decomposition kinetics, by thermogravimetric analysis,... more ABSTRACT An investigation into the thermal decomposition kinetics, by thermogravimetric analysis, of an agricultural and a forestry residue was carried out using distributed activation energy model (DAEM) and Friedman’s differential technique. Preliminarily, Fourier transform infrared spectroscopy alongside proximate, ultimate and heating value was used in the characterisation of the biomass resources. The characterisation experiment showed differences between Sorghum bicolour glume (SBG) and Albizia pedicellaris (AP). The activation energy (E) showed a significant variation as conversion progresses; recording E using DAEM for AP (169–291 kJ mol-1) and for SBG (212–283 kJ mol-1), while E (Friedman’s model) for AP (188–314 kJ mol-1) and SBG (163–280 kJ mol-1). The correlation coefficients obtained for both models (DAEM; R2 C 0.976, Friedman; R2 C 0.971) were high; attesting to the suitability of the models. The reaction order n was also evaluated as a function of temperature based on Avrami’s theory. The average values (0.209 and 0.195) of n obtained for AP and SBG, respectively were found to be lower than those from literature. This places emphasis on the probable effect of biomass complex structure on the reaction order in biomass thermochemical conversion process.

Torrefaction experiments were carried out on some Nigerian woody (Albizia pedicellaris (AP), 9

8 Devolatilisation kinetics and pyrolytic analyses were carried out on Tectona grandis (teak) usi... more 8 Devolatilisation kinetics and pyrolytic analyses were carried out on Tectona grandis (teak) using 9 iso-conversional methods (Flynn-Wall-Ozawa and Starink) and analytical Py-GC/MS technique 10

Two woody species of different origins were subjected to Fourier Transform Infrared (FTIR) spectr... more Two woody species of different origins were subjected to Fourier Transform Infrared (FTIR) spectroscopy, thermogravimetric analysis and analytical Py-GC/MS. Flynn-Wall-Ozawa, a model-free technique, was adopted for the decomposition kinetic study of Isoberlinia doka (ID) and Pinus ponderosa (PP). FTIR spectroscopy was employed to determine the level of cellulose crystallinity in the samples under investigation using the total crystallinity and lateral order indices methods. The apparent activation energy appeared as a function of conversion with significant influence from biomass diversity. The apparent activation energy recorded values of 202 to 365 kJ/mol for ID and 205 to 583 kJ/mol for PP. Thus biomass decomposition kinetics is better modeled as a multi-step reaction mechanism. The analytical Py-GC/MS showed the presence of acids, sugars and phenolic compounds in significant proportions for the two biomass samples. There were marked distinctions in both the quantity and the individual compounds detected in the biomass samples that were investigated.

Biomass Conversion and Biorefinery, 2015

Journal of Analytical and Applied Pyrolysis, 2014

ABSTRACT Torrefaction experiments were carried out on some Nigerian woody (Albizia pedicellaris (... more ABSTRACT Torrefaction experiments were carried out on some Nigerian woody (Albizia pedicellaris (AP), Tectona grandis (TK), Terminalia ivorensis (TI)) and non-woody (Sorghum bicolour glume (SBG) and stalk (SBS)) biomass resources. The influence of process conditions and consequent change in the elemental configuration of the biomass samples were observed. Biomass type played a dominant role in the solid yield recording 71% for woody and 58% for non-woody samples at 270 °C, while temperature showed the greatest influence with solid yield dropping from an average of 80% (at 240 °C) to 50% (at 300 °C). Both volatile matter and fixed carbon contents experienced significant changes after torrefaction and a decline in O/C ratio from 0.6 to 0.3 was noted. Among the woody biomass, TI experienced the highest increase in higher heating value (HHV) of approximately 38% as compared to AP (32%) and TK (32%), and was subsequently selected for decomposition kinetic study. The decomposition kinetics showed that activation energy (E(α)) for the hemicellulose degradation stage ranged between 137 and 197 kJ mol−1 for conversion (α) between 0.1 and 0.24 implying that biomass kinetics within this decomposition region is a multi-step reaction. The GC/MS analytical technique revealed that the presence of levoglucosan was highest (7.1%) in woody biomass, while phenolic compounds made up more than one-third of the group of compounds identified.

Waste and Biomass Valorization, 2014

ABSTRACT An investigation into the thermal decomposition kinetics, by thermogravimetric analysis,... more ABSTRACT An investigation into the thermal decomposition kinetics, by thermogravimetric analysis, of an agricultural and a forestry residue was carried out using distributed activation energy model (DAEM) and Friedman’s differential technique. Preliminarily, Fourier transform infrared spectroscopy alongside proximate, ultimate and heating value was used in the characterisation of the biomass resources. The characterisation experiment showed differences between Sorghum bicolour glume (SBG) and Albizia pedicellaris (AP). The activation energy (E) showed a significant variation as conversion progresses; recording E using DAEM for AP (169–291 kJ mol-1) and for SBG (212–283 kJ mol-1), while E (Friedman’s model) for AP (188–314 kJ mol-1) and SBG (163–280 kJ mol-1). The correlation coefficients obtained for both models (DAEM; R2 C 0.976, Friedman; R2 C 0.971) were high; attesting to the suitability of the models. The reaction order n was also evaluated as a function of temperature based on Avrami’s theory. The average values (0.209 and 0.195) of n obtained for AP and SBG, respectively were found to be lower than those from literature. This places emphasis on the probable effect of biomass complex structure on the reaction order in biomass thermochemical conversion process.