Olawale Ajala
Verified @unilorin.edu.ng
Department of Chemical Engineering, University of Ilorin, Ilorin, Nigeria
RESEARCH, TEACHING, or OTHER INTERESTS
Chemical Engineering, Bioengineering, Catalysis, Fluid Flow and Transfer Processes
Scopus Publications
Scopus Publications
E. O. Ajala, M. O. Aliyu, M. A. Ajala, G. Mamba, A. M. Ndana, and T. S. Olatunde
Springer Science and Business Media LLC
AbstractWaste beneficiation is key to environmental protection and the realisation of a circular economy. Herein, amorphous alumina (a-Al2O3) derived from aluminium waste cans (AWC) was used to modify plantain stalk as an adsorbent for sequestration of lead (II) and chromium (VI) ions from electroplating wastewater. Raw plantain-stalk (RPS) and amorphous-alumina modified plantain stalk (APS) developed as adsorbents were characterised using various equipment such as x-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and Brunauer–Emmett–Teller (BET). The FTIR revealed that the adsorbents are rich in functional groups that could promote the adsorption process which includes carboxyl, hydroxyl, and aliphatic groups. Also, the BET analysis showed a substantial increase in the surface area of APS (174.448 m2/g) compared to that of RPS (40.531 m2/g) which could be due to the effect of modification by the a-Al2O3. The batch adsorption studies revealed that the APS achieved 99.38% and 98.33% removal of Cr(VI) and Pb(II), respectively, which is superior to RPS adsorption efficiency. Also, the estimated and experimental data for the APS compared well under all the kinetic models studied with R2 > 0.88. This suggested that chemisorption is the most plausible adsorption mechanism of Cr(VI) and Pb(II) onto the APS. Further analysis showed that the Cr(VI) and Pb(II) adsorption followed the Langmuir model with the RL value of 0.038 and 0.999, respectively, which indicated that the two metal ions were effectively adsorbed onto the APS. Therefore, this work demonstrated that the modification of plantain-stalk with amorphous-alumina derived from AWC enhanced the characteristics of the APS and favoured its adsorption of the selected heavy metals.
E. O. Ajala, M. A. Ajala, O. D. Abiola, G. S. Akinpelu, and A. M. Ayanshola
Springer Science and Business Media LLC
Mary Adejoke Ajala, Ambali Saka Abdulkareem, Abdulsalami Sanni Kovo, Jimoh Oladejo Tijani, and Elijah Olawale Ajala
Springer Science and Business Media LLC
E.O. Ajala, A.M. Ayanshola, C.I. Obodo, M.A. Ajala, and O.J. Ajala
Elsevier BV
E.O. Ajala, A.B. Ehinmowo, M.A. Ajala, O.A. Ohiro, F.A. Aderibigbe, and A.O. Ajao
Elsevier BV
E. O. Ajala, J. O. Ighalo, M. A. Ajala, A. G. Adeniyi, and A. M. Ayanshola
Springer Science and Business Media LLC
AbstractSugarcane (Saccharum officinarum) bagasse (SCB) is a biomass of agricultural waste obtained from sugarcane processing that has been found in abundance globally. Due to its abundance in nature, researchers have been harnessing this biomass for numerous applications such as in energy and environmental sustainability. However, before it could be optimally utilised, it has to be pre-treated using available methods. Different pre-treatment methods were reviewed for SCB, both alkaline and alkali–acid process reveal efficient and successful approaches for obtaining higher glucose production from hydrolysis. Procedures for hydrolysis were evaluated, and results indicate that pre-treated SCB was susceptible to acid and enzymatic hydrolysis as > 80% glucose yield was obtained in both cases. The SCB could achieve a bio-ethanol (a biofuel) yield of > 0.2 g/g at optimal conditions and xylitol (a bio-product) yield at > 0.4 g/g in most cases. Thermochemical processing of SCB also gave excellent biofuel yields. The plethora of products obtained in this regard have been catalogued and elucidated extensively. As found in this study, the SCB could be used in diverse applications such as adsorbent, ion exchange resin, briquettes, ceramics, concrete, cement and polymer composites. Consequently, the SCB is a biomass with great potential to meet global energy demand and encourage environmental sustainability.
Elijah Olawale Ajala, Mary Adejoke Ajala, Temitope Elizabeth Odetoye, Fatai Alade Aderibigbe, Hammed Olalekan Osanyinpeju, and Mufutau Ayanniyi Ayanshola
Springer Science and Business Media LLC
T.E. Odetoye, J.O. Agu, and E.O. Ajala
Elsevier BV
E. Olawale Ajala, Mary A. Ajala, Oluwatobi O. Onoriemu, Sunday G. Akinpelu, and Saka H. Bamidele
Wiley
The prospect of utilizing yam peel hydrolysate (YPH) as a carbon source for lactic acid (LA) production using Rhizopus orysae was investigated in batch surface and submerged fermentation processes. The kinetics of biomass growth, substrate utilization and LA production were studied using models of modified Luedeking–Piret, logistic and simple Luedeking–Piret equations, respectively, for the surface and submerged processes. The YPH containing 80 g L−1 of reducing sugars (glucose, xylose, ribose and others) was obtained by acid hydrolysis (H2SO4) of 100 g L−1 of yam peel and used for fermentation. The LA yield from the YPH was 80.03% and 75.63% for the surface and submerged fermentation, respectively. These values were higher than those of synthetic glucose syrup (SGS), which were 77.36% and 38.96% for surface and submerged fermentation, respectively. The models were satisfactory for the fermentation processes with high accuracy of R2 ((0.89 to 0.96), (0.95 to 0.99) and (0.86 to 0.99)) for biomass growth, substrate (SGS/YPH) utilization and LA production, respectively. The models also elucidated that the fermentation process was growth associated (α) instead of non‐growth associated (β) because the value of α/β was greater than 1. This justified the other kinetic parameters obtained for the growth phase. Therefore, Rhizopus oryzae effectively converted YPH to LA with a high yield and purity. © 2021 Society of Industrial Chemistry and John Wiley & Sons Ltd
Elijah Olawale Ajala, Mary Adejoke Ajala, and Harvis Bamidele Saka
Wiley
E.O. Ajala, M.A. Ajala, G.S. Akinpelu, and V.C. Akubude
African Journals Online (AJOL)
Microalgae are becoming sustainable alternative feedstocks to food crops for biodiesel production which can also solve the problems associated with the use of fossil fuels. However, several challenges about microalgae’s cultivation, harvesting, pre-treatment and extraction processes as well as the technology of biodiesel production affect its sustainability. This study proffers solutions to these challenges and recommended that hybrid culture systems with genetically engineered microalgal species would overcome the challenges of cultivation. The coagulation/flocculation method was adjudged the best harvesting process of the microalgae for its sustainability for biodiesel production. The pre-treatment by ultrasound coupled with enzymatic extraction was suggested best, due to their numerous advantages over other methods. A novel integrated ultrasound-enzyme-enzyme in-situ pre-treatment-extraction-transesterification design is considered a sustainable approach to utilising microalgae biomass for biodiesel production. The study concludes that the microalgae biomass is more than sufficient to meet the global energy demand and can be economically harnessed as a sustainable feedstock for biodiesel production.
 HIGHLIGHTS
 •Microalgae contain sufficient characteristics for their sustainability for biodiesel production.• Implementation of genetic strategies of microalgal species by cultivating in a hybrid system is the key to microalgae sustainability.• Harvesting of microalgae by coagulation/flocculation method would promote its efficient lipid recovery.• Microalgae are novel feedstocks with a rigid cell wall, its lipid extraction requires the use of effective and efficient pre-treatment.• The ultrasound-enzymatic extraction and enzymatic transesterification in an in-situ process can sustainably utilise microalgae biomass for biodiesel production.
E. O. Ajala, M. A. Ajala, O. B. Okedere, F. Aberuagba, and V. Awoyemi
Informa UK Limited
Abstract A highly-active catalyst for biodiesel production was developed from calcite rock by calcination at different temperatures of 800°C (CCT800) and 900°C (CCT900). The calcination was to transform the metal carbonate in the calcite to metal oxides. The catalyst performance was evaluated through transesterification of palm kernel oil to palm kernel biodiesel (PKB), in an optimization study using a definitive screening design (DSD). The process conditions for the DSD were Methanol: oil molar ratio, reaction temperature, catalyst quantity, reaction time and calcite calcined temperature (CCT). Catalyst’s extent of reusability was investigated. The elemental composition for calcite catalyst calcined at 800°C (CCC800) and 900°C (CCC900) showed percentage composition of carbon, 21.11 and 22.84, oxygen, 40.37 and 38.78, magnesium, 15.17 and 13.34, silicon, 3.61 and 3.23, and calcium, 17.39 and 21.48, respectively which is an indication that the calcination temperature might not have affected the composition of the catalyst. The results showed that the catalyst is rich in essential ingredients (CaO and MgO) for biodiesel production. Its performance for biodiesel production gave an optimum yield of 97% PKB at optimal conditions of 6:1 (w/w) Methanol: oil molar ratio, reaction temperature 55°C, catalyst quantity 8% (w/w), reaction time 2 hours and CCT800. The catalyst was reused for eight cycles with greater activity of not <5% for PKB production. The PKB showed high-quality biodiesel as compared with the standard. Therefore, the calcite is a potential rock as a catalyst for biodiesel production.
E.O. Ajala, M.A. Ajala, A.O. Ajao, H.B. Saka, and A.C. Oladipo
Elsevier BV
E. O. Ajala, M. A. Ajala, I. K. Ayinla, A. D. Sonusi, and S. E. Fanodun
Springer Science and Business Media LLC
AbstractWaste-iron-filling (WIF) served as a precursor to synthesize α-$${\\text{Fe}}_{2} {\\text{O}}_{3}$$ Fe 2 O 3 through the co-precipitation process. The α-$${\\text{Fe}}_{2} {\\text{O}}_{3}$$ Fe 2 O 3 was converted to solid acid catalysts of RBC500, RBC700, and RBC900 by calcination with temperatures of 500, 700 and 900 °C respectively and afterwards sulfonated. Among the various techniques employed to characterize the catalysts is Fourier transforms infrared spectrometer (FT-IR), X-ray diffraction (XRD and Scanning electron microscopy (SEM). Performance of the catalysts was also investigated for biodiesel production using waste cooking oil (WCO) of 6.1% free fatty acid. The XRD reveals that each of the catalysts composed of Al–$${\\text{Fe}}_{2} {\\text{O}}_{3} /{\\text{SO}}_{4}$$ Fe 2 O 3 / SO 4 . While the FT-IR confirmed acid loading by the presence of $${\\text{SO}}_{4}^{2 - }$$ SO 4 2 - groups. The RBC500, RBC700, and RBC900 possessed suitable morphology with an average particle size of 259.6, 169.5 and 95.62 nm respectively. The RBC500, RBC700, and RBC900 achieved biodiesel yield of 87, 90 and 92% respectively, at the process conditions of 3 h reaction time, 12:1 MeOH: WCO molar ratio, 6 wt% catalyst loading and 80 °C temperature. The catalysts showed the effectiveness and relative stability for WCO trans-esterification over 3 cycles. The novelty, therefore, is the synthesis of nano-solid acid catalyst from WIF, which is cheaper and could serve as an alternative source for the ferric compound.
E. O. Ajala, A. M. Olaniyan, F. Aberuagba, M. A. Ajala, and M. M. Odewole
Informa UK Limited
ABSTRACT Optimisation of biodiesel production from high free fatty acids (FFA) of 6.86% shea butter (SB) using a base catalyst, potassium hydroxide, was studied. Response surface methodology (RSM) was employed as a model for the optimisation of the process by varying temperature, agitation speed, mole ratio and catalyst loading in the range of 40–60°C, 200–1400 rpm, 8:1–12:1 (w/w) and 1–2% (w/w) respectively. The significance of the variables in both linear and nonlinear forms of the model was analysed by analysis of variance (ANOVA). The ANOVA results showed that the temperature, agitation speed, mole ratio and catalyst loading had a significant effect on the shea biodiesel yield with a p-value of < 0.0001 for each of the variables, adjusted R2 of 0.9517 and predicted R2 of 0.8625. The maximum %yield of shea biodiesel obtained was 90.83% at optimal operating temperature of 50°C, agitation speed of 800 rpm, mole ratio of 12:1 (w/w) and catalyst loading of 1% (w/w). This showed that the RSM optimised the one-pot synthesis of biodiesel from high FFA SB, an indication that it can be adopted successfully in the industry to maximise the yield of biodiesel from high FFA SB.
E.O. Ajala, M.A. Ajala, I.A. Tijani, A.A. Adebisi, and I. Suru
Elsevier BV
Elijah Olawale Ajala, Yusuf Olanrewaju Olonade, Mary Adejoke Ajala, and Gbolagade Sunday Akinpelu
Wiley
The industrial application of lactic acid is very broad; hence, the high demand is forecasted to mul-tiply in the future. This review presented the major problems for the efficient production of lactic acid from lignocellulose biomass using lactic acid bacteria (LAB) and further proposes three promising solutions to solve these problems, exposing their poten-tials and future research needs. Recombinant cellulolytic strategy in LAB promises a significant reduction of lactic acid production costs, however, extensive research on genetic engineering is still needed. Microwave-assisted deep eutectic solvent pretreatment is extremely fast and produces little to no harmful by-products, but it has not been investigated for lactic acid production yet. Continuous simultaneous saccharification and fermentation with enzyme and cell recycle is newly proposed by the authors as a process set up that can solve the problems of feedback-, substrate- and end-product inhibition while resulting in higher lactic acid productivities, yield, and concentration.
Elijah O. Ajala, Mary A. Ajala, Temitope E. Odetoye, and Anuoluwapo T. Okunlola
FapUNIFESP (SciELO)
A solid catalyst for biodiesel production was synthesized from dolomite by calcination at different temperatures of 800 and 900oC for 2 h. The catalyst was characterized by scanning electron microscopy (SEM) and Brunauer Emmett Teller (BET). Its performance in the production of palm kernel biodiesel (PKB) using palm kernel oil in an optimization study was carried out by a definitive screening design. The varying process parameters for the optimization were methanol:oil molar ratio, reaction temperature, catalyst quantity, reaction time and dolomite calcination temperature. Tendency and extent of the catalyst reusability were also studied. The catalysts were found to contain calcium and magnesium oxides with morphological structures of: surface areas 507 and 560 m2/g, pore volumes 0.180 and 0.199 cm3/g, and pore sizes 27.07 and 31.48 Ȃ for Dolomite Catalyst Calcined (DCC) at 800oC (DCC800) and DCC at 900oC (DCC900), respectively. The optimal parameters of methanol:oil molar ratio 12:1, temperature 65oC, catalyst quantity 8% (w/w), time 4 h and DCC800 gave an optimum yield of 98.69% biodiesel. The catalyst was reused for the 8th cycle after which the %yield of PKB decreased by <4%. It can be concluded that the dolomite catalyst has a great activity and potential as a viable catalyst for quality biodiesel production.
Oyetunji Babatunde Okedere, Bamidele Sunday Fakinle, and Olawale Elijah Ajala
Wiley
E. O. Ajala, M. A. Ajala, D. S. Ogunniyi, and M. O. Sunmonu
Wiley
The kinetics of gluconic acid production by Aspergillus niger (A. niger) using breadfruit hydrolysate was studied in a batch bioreactor. A simple model of Luedeking–Piret, logistic, and Luedeking–Piret-like equations were proposed for gluconic acid production, cell growth, and breadfruit hydrolysate consumption respectively. The maximum gluconic acid concentration (Pt) of 109.95 g/L with 0.967 g/g process yield (88.70%) was obtained for the medium containing 120 g/l breadfruit hydrolysate at 2 vvm aeration rate. For the same conditions, the biomass concentration and maximum specific growth were obtained as 24.3 g/L and 0.018 hr−1 respectively. The models proposed for the gluconic acid production was sufficiently satisfactory, since the theoretical values of Pt (100.94 g/L) and biomass concentration (23.43 g/L) obtained from the models were almost the same with the experimental values. The model for the breadfruit hydrolysate utilization gave R2 and Adj. R2 of above 0.840 and 0.660 respectively; an indication that the model is suitable for the production of gluconic acid. Therefore, the concentration of initial breadfruit hydrolysate as substrate and aeration rate have shown significant effect on gluconic acid production and A. niger accumulation. The evaluation of the models showed that the gluconic acid production was growth-associated.
Practical applications
Breadfruits, a perishable fruit has been abundantly found in Ile-Ife, Nigeria where 50% of it perishes due to its short shelf-life. This study therefore provides alternative use for breadfruit, in order to reduce its wastage. Furthermore, the growing demand of gluconic acid can be met through the use of this cheap and available breadfruit. The findings in this study can be employed to develop a bioreactor for fermentation of breadfruit hydrolysate to produce gluconic acid.
E.O. Ajala, F. Aberuagba, A.M. Olaniyan, and K.R. Onifade
Wiley
Enzymatic extraction of shea butter (SB) from its kernel was undertaken and characterized using standard methods. Fourier transform infrared spectroscopy (FTIR) was used to determine the functional group of the extracted SB. In a preliminary study, SB was extracted using a mixture of enzymes, which had in equal proportion pectinase, α-amylase, cellulase, glucoamylase and xylanase. The operating parameters of extraction temperature (50°C), time (180 min), water/seed ratio (6:1, w/w) and pH (5) were used for the study, which yielded 32.71% SB. However, using each of the enzymes for the extraction under the same operating parameters, pectinase yielded 31.40%, which was higher compared to the yield of other enzymes. Hence, pectinase was used to optimize the operating parameters using response surface methodology. A box behnken design was adopted to evaluate the effect of each of the parameters on percentage yield of SB. The result indicated that the parameters had significant effect on the yield of SB with R2, F and p value of 0.9994, 1,375.24 and 0.0001 respectively. The interactions of water/seed ratio with other parameters showed a significant effect at p < 0.0001. Based on this model, maximum yield of 42.95% SB was obtained at 50°C, 180 min and 7:1 water/seed ratio (w/w). The physico-chemical properties of the extracted SB compared favorably well with SB extracted using other methods. The FTIR result indicated that the enzymatic treatment did not affect the chemical composition of the butter. Accordingly, enzymatic extraction can serve as a suitable method for SB extraction.
Practical Applications
The study investigated the effect of temperature, extraction time and water/seed ratio on yield of shea butter (SB) using enzymatic extraction method. The possible effect of the method on the quality of the SB was carried out. The study gave the optima operating conditions under which the optimum yield of SB can be obtained. This research finding revealed that the enzymatic extraction can replace solvent and traditional extraction of SB. The potential of this method of extraction is in term of high yield and maintenance of the physico-chemical properties of the butter. The process therefore, can be employed in an industrial scale production of SB.