Publications and Abstract of Research

Chemical Engineering Department (2017-2018)

List of 2017-2018 Publications and Abstract of Research from Chemical Engineering Department

School of Engineering and Engineering Technology

S/NAuthor's Name & year of publicationTitle of workAbstractJournal NameJournal Vol./Number
The electrochemical oxidation of glycerol has been studied and known to be a source of several chemicals of premium industrial value and has also been utilized in the concept of direct glycerol fuel cells to produce electrical energy additionally[1]. In the current study however, this concept is extended to cover both electrochemical oxidation and reduction of glycerol as a substitute for the hydrogen ion in redox flow battery with a Fe2+/Fe3+ couple as cathode [2]. A predictive thermodynamic analysis has been developed and applied to the study and proof of this conceptual glycerol redox flow battery. Reactions toward electrochemical formation of several partial oxidation and reduction products of glycerol in acidic media under discharge and charging conditions of the proposed glycerol flow battery are presented. Free energy values of the reaction species as estimated by the Group Additivity Value (GAV) method were used to determine the feasibility of these proposed reaction towards cogeneration of electricity and commodity chemicals. The equilibrium voltages representing the maximum electrical work under these conditions are also computed. Experimental validation of this theoretical concept has also been investigated using electrochemical methods to study the electro-catalytic activity of electrolessly deposited NiCuSnP supported on carbon towards glycerol oxidation in acidic medium as anode in a proton exchange membrane-glycerol redox flow battery.
-2018 Key words: Self-discharge, charge and energy loss, mechanisms, redox species, electric double layer instability, asymmetric capacitors
Key words: Electrode thickness Current density Effective conductivity Modelling and simulation Electrode utilization Potential drop.
1 I.S. Ike, I. Sigalas, and S. E. Iyuke. (2017) The Effects of Self-Discharge on the Performance of Symmetric Electric Double Layer Capacitors and Active Electrolyte Enhanced Supercapacitors: Insights from Modelling and Simulation. The effects of self-discharge on the performance of symmetric electric double-layer capacitors (EDLCs) and active electrolyte-enhanced supercapacitors were examined by incorporating self-discharge into electrochemical capacitor models during charging and discharging. The sources of self-discharge in capacitors were side reactions or redox reactions and several impurities and electric double-layer (EDL) instability. The effects of self-discharge during capacitor storage was negligible since it took a fully charged capacitor a minimum of 14.0 days to be entirely discharged by self-discharge in all conditions studied, hence self-discharge in storage condition can be ignored. The first and second charge–discharge cycle energy efficiencies and of a capacitor of electrode effective conductivity = 0.05 S/cm with only EDL instability self-discharge with current density JVR = 1.25 9 10-3 A/cm2 were 72.33% and 72.34%, respectively. Also, energy efficiencies and of a similar capacitor with both side reactions and redox reactions and EDL instability self-discharges with current densities JVR = 0.00125 A/cm2 and JVR1 = 0.0032 A/cm2 were 38.13% and 38.14% respectively, compared with 84.24% and 84.25% in a similar capacitor without self-discharge. A capacitor with only EDL instability self-discharge and that with both side reactions and redox reactions and EDL instability self-discharge lost 9.73Wh and 28.38Wh of energy, respectively, through self-discharge during charging and discharging. Hence, EDLCs charging and discharging time is significantly dependent on the self-discharge rate which are too large to be ignored. Key words: Self-discharge, charge and energy loss, mechanisms, electric double-layer, symmetric, active electrolyte-enhanced supercapacitors. Journal of Electronic Materials. Vol. 46 number 2
2I.S. Ike, I. Sigalas, and S. E. Iyuke. (2017) Optimization of design parameters and operating conditions of electrochemical capacitors for high energy and power performances. Theoretical expressions for performance parameters of different electrochemical capacitors (ECs) have been optimized by solving them using MATLAB scripts as well as via the MATLAB R2014a optimization toolbox. The performance of the different kinds of ECs under given conditions was compared using theoretical equations and simulations of various models based on the conditions of device components, using optimal values for the coefficient associated with the battery-kind material (KBMopt) and the constant associated with the electrolyte material (KEopt), as well as our symmetric electric double-layer capacitor (EDLC) experimental data. Estimation of performance parameters was possible based on values for the mass ratio of electrodes, operating potential range ratio, and specific capacitance of electrolyte. The performance of asymmetric ECs with suitable electrode mass and operating potential range ratios using aqueous or organic electrolyte at appropriate operating potential range and specific capacitance was 2.2 and 5.56 times greater, respectively, than for the symmetric EDLC and asymmetric EC using the same aqueous electrolyte, respectively. This enhancement was accompanied by reduced cell mass and volume. Also, the storable and deliverable energies of the asymmetric EC with suitable electrode mass and operating potential range ratios using the proper organic electrolyte were 12.9 times greater than those of the symmetric EDLC using aqueous electrolyte, again with reduced cell mass and volume. The storable energy, energy density, and power density of the asymmetric EDLC with suitable electrode mass and operating potential range ratios using the proper organic electrolyte were 5.56 times higher than for a similar symmetric EDLC using aqueous electrolyte, with cell mass and volume reduced by a factor of 1.77. Also, the asymmetric EDLC with the same type of electrode and suitable electrode mass ratio, working potential range ratio, and proper organic electrolyte showed enhanced performance compared with the conventional symmetric EDLC using aqueous electrolyte, with reduced cell mass and volume. These results can obviously reduce the number of experiments required to determine the optimum manufacturing design for ECs and also demonstrate that use of an asymmetric electrode and organic electrolyte was very successful for improving the performance of the EC, with reduced cell mass and volume. These results can also act as guidelines for design, fabrication, and operation of electrochemical capacitors with outstanding storable energy, energy density, and power density. Journal of Electronic Materials. Vol.46, N0. 3
3I.S. Ike, I. Sigalas, and S. E. Iyuke. (2017) Modelling and Optimization of Electrodes Utilization for high Energy and Power in Symmetric Electrochemical Capacitors. Expressions and guidelines for determination of electrode's effective thickness, optimum charging current density and electrode utilization in device with certain electrode's and electrolyte's effective conductivity were developed, and systematically used to study the performance of electrochemical capacitors (ECs). Effective thickness of electrode increases along with increase in effective conductivity of electrolyte and decreases as charging current density is increase. It was seen that every current density applied to device of specific electrode's and electrolyte's effective conductivity has corresponding effective thickness of electrode, and when charged at current density higher than its maximum current density, materials (electrodes) utilization was less than 100%. Also, when device with electrode's thickness higher than the effective thickness was charged at its maximum current density, materials (electrodes) utilization reduced below 100%. Materials utilization decreases along with increase in charging current density and electrode thickness, but increases as effective conductivity of electrode and electrolyte are increase. Therefore, optimum/effective thickness of electrode and optimum current density must be employed in charging device of given electrode's and electrolyte's effective conductivity for maximum materials utilization and performance (with minimum or no potential drop). Optimum current density beyond which energy density decays increases along with increase in electrode's and electrolyte's effective conductivity and decrease in electrode thickness. Use of optimum current density and effective electrode's thickness to maximize energy and power densities is inevitable, because increase in current density results in increase in power density and decrease in energy density. Journal of Energy Storage Vol.12 , pp 261–275
4I.S. Ike, I. Sigalas, and S. E Iyuke The Effects of Self-Discharge on the Performance of Asymmetric/Hybrid Electrochemical Capacitors with Redox-Active Electrolytes: Insights from Modeling and Simulation. Self-discharge effects on the performance of an asymmetric electrochemical capacitors (ECs) was studied by incorporating a combination of different applicable self-discharge mechanisms into the capacitors mass transfer and charge conservation equations during charging and discharging. Key self-discharge parameters are the concentration of impurity ions and oxidized species, and the separator and the total thickness of the anode. The storable and deliverable energies of ECs with self-discharge were higher than those of a similar device without self-discharge and redox electrolyte when an insoluble redox product was used and the key self-discharge parameters were tuned. When the asymmetric ECs were charged and discharged rapidly, the rate of self-discharge was reduced, compared with when they were charged and discharged slowly. The shuttle self-discharge contributed the majority of the self-discharges in the asymmetric ECs. The charging and discharging time of the ECs was significantly dependent on the self-discharge rate, and this model gives a more practical evaluation of potential/energy decay exhibited during self-discharge. A theoretical explanation for a unique redox electrolyte that is convertible into insoluble species during the device charging to suppress self-discharge, as reported in the literature, was obtained. Journal of Electronic Materials. Issue 47 volume 1
5I. S. Ike, S. A. Melchior, K. Raju, R. M. Erasmus, G. Kabongo, I. Sigalas, S. E. Iyuke, and K. I. Ozoemena High-Voltage Symmetric Supercapacitor Based on 2D Titanium Carbide (MXene,Ti2CTx)/Carbon Nanosphere Composites in a Neutral Aqueous Electrolyte. The energy storage performance of one of the lightest-known MXenes, Ti2CTx (MX) combined with carbon nanospheres (CNS) has been investigated as a symmetric electrode system in an aqueous electrolyte (1 M Li2SO4). The energy storage properties were interrogated using cyclic voltammetry (CV), galvanostatic cycling with potential limitation (GCPL), electrochemical impedance spectroscopy (EIS) and voltage-holding tests. The combined material (MX/CNS) demonstrated a higher specific capacity compared to each of the individual components. The material was fabricated with relatively high and low mass loadings, assembled into a symmetric device and performance compared. Specific capacitance, specific power and specific energy for the lower electrode mass loading of 180 Fg−1, 37.6 kWkg−1 and 14.1 Whkg−1 were all higher than 86 Fg−1, 20.1 kWkg−1 and 6.7 Whkg−1 for the higher mass loading. A wide voltage window of 1.5 V was obtained, but with limited long-term cycling behavior, suggesting the need for future improvement. Mathematical modeling and simulation of the supercapacitor showed good correlation with the experimental results, validating the model. The results reveal the potential of the Ti2CTx to be employed as a viable energy storage system for lightweight applications. Journal of The Electrochemical Society, Issue 165 volume 3
6Issue 165 volume 3
A Group Additivity Based-Thermodynamic Analysis of a Conceptual Glycerol/Ferric Redox Flow Battery ECS Transactions Vol. 77 Issue 11, 2005 – 2010
7S. Anderson, M. Nilsson, C. Clark, E. E. Kalu (2017) Micelle Mediated Extraction of Neodymium and Electrochemical Characterization of AOT Reverse Micelles The surfactant bis(2-ethylhexyl) sulfosuccinate (AOT) effects on neodymium (Nd) extraction from aqueous phase in electric field-imposed extraction processes were studied. With the application of an external electric field (0 – 1.4 kV m-1) and gentle stirring, a slight to moderate increase in the extraction of Nd was observed relative to the Nd extracted without applied field for AOT, HDEHP and AOT+HDEHP. Electrochemical impedance spectroscopy technique showed that as the reverse micelles molar water content (Wo), increased, conductivity increase. Addition of HDEHP caused a significant drop in solution conductivity. Temperature had a mild effect on increasing the conductivity. ECS Transactions Vol. 77 Issue 11, 989 – 996
8Shellikeri, V. G. Watson, D. L. Adams, E. E. Kalu, J. R. Read, T. R. Jow, J. P. Zheng, (2017) Pre-Lithiation of Carbon Anodes Using Different Lithium-Sources Energy storage devices like batteries and supercapacitors have become indispensable in portable devices and electric vehicles. But the carbon anodes, which exhibit a significant loss in their initial capacity due to consumption of Li ions from electrolyte during SEI layer formation, have the potential to diminish this advantage, if unaddressed. Pre-lithiation treatment of carbon anodes can mitigate this loss, apart from improving the cell working potential, hence enhancing cell energy density and cyclability. We investigate in this report a direct-contact lithiation process in different carbon anodes using various lithium source structures. The results of this study reveal that the type of Li-source structure can have a major impact on the electrode physical properties, pre-lithiation times and the pre-lithiation capacities achieved, effecting the properties of the SEI formed and the electrode processing costs. Vol. 77 Issue 11, 293 – 303
9S. Anderson, M. Nilsson, E. E. Kalu, (2017) Electrochemical Impedance Spectroscopy (EIS) Characterization of Water/Sodium Bis(2-Ethylhexyl)Sulfosuccinate-HDEHP/n-Dodecane Reverse Micelles for Extraction of Neodymium The extraction and separation of metal ions in the lanthanide series using the liquid-liquid extraction (LLX) technique poses a major challenge due to the chemical similarities of the metals and hence interest exists in devising a technique to improve the separation factor. In this work, sodium bis(2-ethylhexyl) sulfosuccinate (AOT) is explored for improved organic phase conductivity to aid the use of an imposed external field to improve the LLX. The electrochemical impedance spectroscopy (EIS) technique was used to determine the effect of molar water content, AOT and HDEHP (bis(2-ethylhexyl) phosphoric acid) concentration, and the temperature on the reverse micelle solution conductivity. Results showed that as AOT concentration and water content increases, conductivity increases until the reverse micelles collapse. The addition of HDEHP caused a significant drop in solution conductivity. For a mixed AOT and HDEHP system and at a small applied external field range of 0–1.4 kV m−1 and 60 rpm stir rate, a significant improvement in Nd extraction was observed relative to the traditional LLX using HDEHP only. With AOT only, a 40% improvement in extraction was observed with applied field relative to the absence of field. Cost consideration favors the use of mixed AOT and HDEHP at a slow stir rate for improved Nd extraction. ChemEngineering Vol. 1, Issue 1, pp. 3
10J. Sankar, E. N. Onyeozili, E. E. Kalu, (2017) Oxidation of Glycerol with Unactivated Electroless CuNiMoP Catalyst. Unannealed CuNiMoP electrocatalyst was found active in electrochemical oxidation of glycerol, providing over 60% conversion without optimization. Prompted by this result, the same catalyst was investigated for the thermochemical oxidation of glycerol. For the thermochemical oxidation of glycerol using the as-deposited electroless CuNiMoP catalyst, a 23 full factorial design of experiments (two level factorial experiment design with three factors) to assess the influence of temperature (A), reaction time (B) and pressure (C). The major reaction products detected by high performance liquid chromatography (HPLC) were glyceric, hydroxypyruvic, tartronic, oxalic and formic acids. The factors found to be most significant for the production of glyceric and tartronic acids were A, B, C, AB and BC. The highest percent conversion obtained for 30-min and 60-min catalysts was 10.6% and 9.4%, respectively. The presence of lactic acid was observed only for the 60-min as-deposited electroless CuNiMoP/Al2O3 catalyst. The results suggest the feasibility of an inexpensive catalyst based on non-noble metals for the thermochemical oxidation of glycerol through the electroless deposition technique. Some differences exist between the thermochemical and electrochemical product selectivity of the CuNiMoP catalyst, and reasons are suggested for the observed differences. ChemEngineering Vol. 1 Issue 2
11Shellikeri, V. Watson, D. Adams, E. E. Kalu, J. R. Read, T. R. Jow, J. S. Zheng, J. P. Zheng, (2017) Investigation of Pre-Lithiation in Graphite and Hard Carbon Anodes Using Different Lithium Source Structures. Energy storage devices like batteries and supercapacitors, have become indispensable in portable devices and electric vehicles. But, the carbon anodes used in these devices, exhibit a significant loss in their initial capacity (graphite: 6.6% and hard carbon: 29.8%) due to the consumption of Li ions from electrolyte during solid electrolyte interface layer formation and other non-reversible reactions, and if unaddressed, can potentially diminish this advantage. Pre-lithiation treatment of carbon anodes can mitigate this loss, apart from improving the cell working potential, hence enhancing cell energy density and cyclability. We investigate in this report a direct-contact lithiation process in graphite and hard carbon anodes using four distinct lithium source structures. The results show that the type of Li-source structure employed for anode pre-lithiation can have a major impact on the electrode physical properties, pre-lithiation times and the pre-lithiation anode potentials achieved, potentially effecting the SEI properties, cycle life, and the electrode processing costs. J. Electrochem. Soc. Vlo. 164 Issue 14, pp. A3914 – A3924
12V. Watson, W. Telama, Y. Yeboah, J. Zheng,E. E. Kalu, (2018) Conductive and Porous SnCu-Coated Carbon Cloth Network for Binder-free Li-Ion Storage Anodes Large volume change occurs during lithiation/delithiation of Sn anodes and result in pulverization, poor cycling, capacity loss and anode degradation that impedes the general use of Li-ion batteries. This study proposes a time-controlled synthesis approach for 1-D SnCu nanoparticles on three-dimensional anode by electrolessly adhering Cu to C cloth and subsequently Sn on the Cu. After annealing at 200 oC, electrically conductive, porous, flexible and mechanically stable CuSn alloy anode results. The CuSn anodes exhibited high conductivity due to copper deposit, accommodated volume changes and stress due to both 1-D-deposit and porosity and have high electrochemical activity due to large surface area. After 100 cycles, the sample deposited for the shortest time (1.5 min) interval and close to 1-D SnCu deposit has a specific discharge capacity of ~605 mAh g-1 which contrasts to the ~400 mAh g-1 obtained for the sample deposited for 6 min. The specific electrode surface area of the 1.5 min sample was 169 m2 g -1 in contrast to 6.4 m2 g -1 obtained for the 6 min sample. A rate capability of 520 mAh g-1 at a current density of 583 mA g-1 was achieved for the thinnest deposit. The porous Sn anode materials demonstrated low resistance during electrochemical impedance analysis and showed high reversible redox reactions during cyclic voltammetry tests. The achievement of high capacity anode (comprising of Sn-SnO2-Cu6Sn5) with good reversible capacity retention through electroless coating method indicates that electroless deposition on flexible free-standing and porous substrate is an effective Sn anode fabrication technique. Int.J. Electrochem. Sci. Vol.14, Issue 2 pp. 2004-2026
13V. G. Watson, Z. D. Haynes, W. Telama, Y. D. Yeboah, M. H. Weatherspoon,J. P. Zheng, E. E. Kalu, (2018) Electrochemical Performance of Heat Treated SnO2-SnCu@C-Felt Anode Materials for LithiumIon Batteries. Standalone, self-supported SnO2–Cu6Sn5@C-Cloth/C-Felt anodes have been successfully synthesized through electroless metallization of the surface of C-Felt by Cu and Sn and subsequent heating at respective temperatures of 200 °C and 400 °C. X-ray diffraction (XRD), scanning electron miscroscopy (SEM), and the nitrogen (N2) adsorption/desorption isotherms were used to obtain the composition, structure and morphology of the electrode. The electrochemical characteristics were assessed using a two-electrode cell arrangement versus lithium metal. Results presented show that SnO2–Cu6Sn5nanoparticles or thin film uniformly coated the C-Felt tubular network (matrix) establishing a binder-free anode. Galvanostatic charge/discharge cycling of the SnO2–Cu6Sn5@C-Cloth/C-Felt anode exhibited a reversible discharge capacity of 641 mAh/g and 681 mAh/g after 140 cycles at the current density of 150 mA/g, for the samples heated at the respective temperatures of 200 °C and 400 °C. We attributed the high capacity performances of the synthesized 400 °C anode to the higher content of SnO2, smaller particle sizes, higher Li ion diffusion coefficient and higher surface area. The outstanding cycle and rate capacity performances indicated that the heat-treated electrodes might be potentially applicable in lithium ion batteries. Surfaces and Interfaces Vol. 3, pp. 224-232
14V. Watson, Y. Yeboah, M. Weatherspoon, J. Zheng, E. E. Kalu, (2018) Preparation of Encapsulated Sn-Cu@graphite Composite Anode Materials for Lithium-Ion Batteries. Electroless encapsulation of graphite particles with copper-tin alloy (Sn-Cu@graphite) is demonstrated as a feasible anode preparation method that is cost effective and provides both high cyclability and reversible capacity. Heat treatment of the electroless composites at 200 oC yielded Sn-Cu@graphite anode composites with a 20 wt.% Sn loading, specific surface area of 22.5 m2 /g and a 1st discharge capacity of 1074 mAh/g at 0.2C rate. In contrast, the graphite substrate particles used for the encapsulation has a surface area of 2.34 m2 /g) and a 1st cycle discharge capacity of 327 mAh/g at 0.2 C rate. At the 300th cycle, these capacities decreased to ~400 mAh/g and 208 mAh/g for the SnCu@graphite and graphite substrate, respectively. Above 300 cycles, the electroless encapsulated SnCu@graphite anode maintained a capacity higher than that determined experimentally and theoretically for graphite. The electrochemical impedance and cyclic voltammetric results demonstrate that the electroless encapsulated Sn-Cu@graphite anode has very low resistance and high reversible redox reactions. The higher capacity and long term cycling (> 300 cycles) achieved with the electroless composite anodes are attributed to the buffering effect of the electroless Cu in the Sn-Cu alloy encapsulating graphite particles, Sn-Cu@graphite’s higher surface area (22.5 m2 /g), and curvature of the graphite particles. The electroless encapsulated Sn-Cu graphite composite anode materials with extended cycling have potential application for the anode of Li-ion battery. Int. J. Electrochem. Sci. Vol. 13, Issue 8, pp. 7968–7988
15O.C.N. Ndukwe and T.F. Eze (2017) Effect of temperature on the bioleaching of Iron from silica sand with Aspergillus niger correlated with Shrinking Core and Mixed kinetic models The influence of temperature on the bioleaching of iron from silica sand with Aspergillus niger has been studied with three size fractions of silica sand: +120-212µm, +212-300µm, and +300-425µm over the temperature range 40 to 800C for several hours. The experimental data were fitted to the shrinking core model (ash layer diffusion control and chemical reaction control) and a mixed kinetic model that incorporates a multiplying factor, b. Optimal temperature for bioleaching was found to be 700C and the amount of iron leached increased with decreasing particle size, with +120- 212µm being the most effective particle size fraction. The shrinking core model with chemical reaction control and ash layer diffusion control failed to explain the effect of temperature on the kinetics of bioleaching. The mixed kinetic model with the multiplying factor b=0.2 gave a perfect fit to the experimental data after the second hour of bioleaching. At the early part of the bioleaching process where the mixed kinetic model failed, ash layer diffusion seemed to be in control. Based on our work, a staged bioreactor design that relies on the ash layer and mixed kinetics models may be required for the process.Keywords: Silica sand, Aspergillus niger, Bioleaching, Iron, Shrinking core, Mixed Kinetics, Model, Temperature. Saudi Journ. of Engrg. And Technol. Vol. 2, Issue 5, pp. 197-204.
16O.C.N. Ndukwe and T.F. Eze (2017) Effect of particle size on bioleaching of Iron from Silica sand fitted to Shrinking Core and Mixed kinetic models. The effects of particle size on the bioleaching of iron from naturally occurring silica sand with Aspergillus niger have been studied. Bioleaching tests were carried out with five different particle size fractions of silica sand, +120-212µm, +212-300µm, +300-425µm, +425-650µm and +650-1000µm at room temperature of 30±20C. It was only with the particle size, +120-212µm was the iron content of sand reduced to 0.11% which met the British standard for production of F and G grades of glass products. The experimental data were correlated with the chemical reaction model and ash layer diffusion equations of the Shrinking core model and a mixed kinetic model, which is a combination of both. The chemical reaction equation failed to represent the data; ash layer diffusion accounted for bioleaching of iron between day 21 to day 30. The mixed model largely represented the bioleaching process for the 30 days. Keywords: Silica Sand, Aspergillus niger, Bioleaching, Iron, Particle Size, Kinetic Models, Shrinking core. Int. Journ. Of Engrg Res and Revs. Vol. 5, Issue 2, pp. 1-8.
17O.C.N. Ndukwe and N Igboko (2019) Comparative analysis of the adsorptive capabilities of empty palm fruit bunch and sugar cane bagasse. The adsorption capacity of activated carbon prepared from empty palm fruit bunch and that from sugar cane bagasse was evaluated using sample from waste oil from Camela vegetable oil mill as test sample, the adsorption capacity for sugarcane bagasse as obtained was 0.000081625g/g relative to a contact time of 30minutes with adsorption efficiency of 91.8% while that for empty palm fruit bunch stood at 0.000073625g/g for 40minutes of contact time and adsorption efficiency of 74.3%.Therefore, sugar cane bagasse is a better adsorbent because the contact time is less than that for empty palm fruit bunch yet more effective since its adsorption capacity and efficiency is higher. Keywords: Adsorption, Empty palm fruit bunch, Sugar cane bagasse, Optimum Int Journ of Sci and Engrg Inves. Vol.8, Issue 84, pp 47-51.
18Kamen, F. L; Nnamchi, S. N; Ike, I. S; Orga, A. C and Nkwocha, A. C (2018) Comparative Study of the Production of Biogas from Cow, Pig and Poultry Dung. A laboratory-scale production of biogas by anaerobic digestion was studied using cow, pig and poultry dung. The research was carried out at the temperature of 300C by dissolving 150g of dung in 150ml of water in corked flask. The gas from the flask was channeled into a calibrated glass cylinder in inverse position in water and the volume of gas generated recorded on daily basis for 20days. The results showed that cow dung had the highest biogas yield of 107cm3/150g dry dung, followed by the poultry dung with the yield of 83.1cm3/150g and lastly pig dung having the yield of 79cm3/150g dry dung. Most of the biogas produced was obtained in the second week of the digestion for all the three samples. Conversion of the animal dung to biogas provides added value to the wastes as energy resources and reduces environmental problems associated with animal wastes, hence it is a waste-to-wealth technology. Journal of Multidisciplinary Engineering Science and Technology (JMEST) Vol. 5, Issue 10.
19Ikhazuangbe, P.M.O; Kamen, F. L; Opebiyi, S.O; Nwakaudu, M. S; and Onyelucheya, O. E (2017) Equilibriun Isotherm, Kinetic and Thermodynamic Studies of the Adsorption of Erythrosine Dye onto Activated Carbon from Coconut Fibre Equilibrium isotherm, kinetic and thermodynamic studies of the adsorption of erythrosine dye onto activated carbon from coconut fibre was carriedout. The coconut fibre obtain from Elele, Rivers State Nigeria, was washed, dried, carbonized at 4000C, crushed, sieved and activated at 8000C, before it was washed and dried at 1100C. Variable influencing factors, such as contact time, temperature and initial concentration were studied through single-factor experiment, while other factors are kept constant (at 30min, 300C and 50mg/L) in each adsorption experiment. The Freundlich isotherm fits adsorption compare to others used, the adsorption kinetic followed pseudo-second order reaction, while the thermodynamic parameters, (∆H) = 28.73KJ/mol, (∆G) = 94.45 J/mol.K and (∆S) = -0.10, -0.27, -0.82, - 1.05, - 1.77, -2.49KJ/mol. From the results obtained, activated carbon from coconut fibre, will be an excellent low-cost adsorbent for the removal of Erythrosine from industrial waste water. International Journal of Advanced Engineering Research and Science (IJAERS) Vol. 4, Issue 5
20Ikhazuangbe, P.M.O; Kamen, F. L; Okwara, C. A;Oghome, P. I; and Opebiyi, S.O (2017) Adsorption of Malachite green oxalate dye onto activated carbon from coconut fibre. The study of the adsorption of Malachite green oxalate from aqueous solution was carried out with activated carbon prepared from coconut fibre. The coconut fibre was washed , dried , carbonized , crushed , sieved and eventually activated at 8000C with 0.1M HCl. Adsorption experiment was carried out with various concentrations of the adsorbate at constant time, temperature, volume and dosage . It was repeated at varying temperature while other influencing factors were kept constant. The adsorption process fits the Freundlish isotherm with correlation coefficient of 0.8940. The adsorption also followed the second order kinetic with rate constant of 0.1433, 0.1568, and 0.1570 (g/mg.min) at 30, 40, and 500C, respectively. The activation energy under this condition is 3.80KJ/mol and the thermodynamic parameters: ∆H0 = 20.45KJ/mol, ∆S0 = 74.34J/mol.K and ∆G0 = -1.49, - 2.93, - 3.11, - 3.37, - 3.48 and - 3.63J/mol for the various temperatures used. These results affirm the fact that activated carbon from Coconut fibre has the efficacy of a good adsorbent.Key words: Adsorption, Coconut fibre, kinetic, Malachite green oxalate and thermodynamic. International Refereed Journal of Scientific Research in Engineering (IRJSRE) Vol. 2, Issue 4 . pp.07 - 12
21Nkwocha A.C., Ekeke I.C., Kamalu C.I.O., Kamen F.L., Uzondu F.N., Dadet W.P., Olele Environmental Assessment of Vehicular Emission Port Harcourt is a coastal city located in the Niger Delta region of Nigeria, with very short dry season and long heavy rainy season periods. The objective of this study was to assess air pollution level from vehicular emission during the rainy season period. Three locations in the city noted for high traffic congestion were selected for the study. Air sampling in these locations were carried out for 11 days, covering peak and off peak periods. The following air pollutants were measured namely; nitrogen oxides (NOx), sulphur oxides (SOx), carbon monoxide (CO) and unburnt hydrocarbons (CxHy), as well as climatic elements – ambient temperature and relative humidity. The air pollutant levels obtained were compared with local and international standards. CO complied with international standard, but exceeded local standard. There is need for effective air pollution monitoring and control, this will go a long way to reduce the health risk associated with air pollution in the city. International Journal of Environment, Agriculture and Biotechnology (IJEAB) Vol. 2, Issue 2.
22M.C. Menkiti C.M. Agu, P.M. Ejikeme, O.E. Onyelucheya (2017) Chemically improved Terminalia catappa L. oil: A possible renewable substitute for conventional mineral transformer oil. This work focuses on the chemical modification and characterization of Terminalia catappa kernel oil (TCKO) for possible use as substitute for mineral transformer oil. The TCKO was extracted by solvent extraction method. Direct purification and transesterification methods were individually applied for the modification of the kernel oil. Modified Terminalia catappa kernel oil (MTCKO) and TCKO characteristics were determined using standard methods. Fourier transform infrared (FTIR) spectrometry was used to determine the prevalent functional groups in the MTCKO samples. At process conditions of 550C, 150 min and 0.5 mm particle size, kernel oil yield was 60.45% (by weight). For MTCKO blended with antioxidant (Acetic acid AA, Citric acid CA), dielectric strength of 46.36 kV and 48.55 kV were obtained when direct purification and transesterification methods were, respectively, used. The ANOVA and the Tukey’s post hoc analyses indicated that time and particle size effects were significant while temperature was not. Physicochemical properties of TCKO and MTCKO indicated its potential for use as transformer fluid. Journal of Environmental Chemical Engineering Vol. 5, Issue 1., pp. 1107 - 1118
23Udoye M.C, Okpala K.O, Osoka E.C, Obijiaku J.C, Ogah A.O, Chukwu M.M. (2017) Modeling a Bioremediation Process of a Petroleum Contaminated Soil Enhanced With NPK Fertilizer and Animal/Plant Derived Organic Manure In this study, the potential effects of animal derived organic manure (cow dung, poultry droppings), saw dust and NPK fertilizer on the bioremediation of petroleum hydrocarbon contaminated soil was investigated. The rate of biodegradation was studied for the period of 10 weeks under laboratory conditions. The biodegradation data were fitted to eight models, four of which are based on microbial growth rate and the other four based on order of reaction. Results obtained show that bioremediation with NPK fertilizer and poultry manure followed the logistic growth curve with a constant yield. While treatment with blend of poultry droppings+cow dung+saw dust, occurred with the logistic growth curve with varying yield. It was observed that at optimum addition of NPK fertilizer and poultry manure, the process obeyed same trend as observed when a combination of poultry droppings+cow dung+saw dust was applied. It also revealed bioremediation as basically a first order process at low and moderate addition of biostimulants. NPK fertilizer and poultry manure obeyed first order rate model with ultimate contaminant greater than zero. Again, it was observed that application of NPK fertilizer and animal manure at an increased quantity without combinations offer similar effect with poultry droppings+cow dung+saw dust. Consequently, the result of the percentage degradation of hydrocarbon for the soil sample studied revealed that the rate of hydrocarbon biodegradation was in the following order (83.5%) > (72.6%) > (68.31%) for biotreatment with blend of poultry droppings+cow dung+saw dust, poultry manure and NPK fertilizer respectively. The observations from the mathematical models, graphical and numerical fit results show that the proposed models employed in this work rather than the usual first order rate model were effective in predicting the bioremediation process. International Research Journal of Advanced Engineering and Science Vol. 2, Issue 4, pp. 87-97,
24Okere P.C., Kamalu C.I.O, Onyelucheya O.E., Nwakaudu M.S, Obijiaku J.C 2017 Curve Fitting Of Cumulative Discovery and Production of Nigerian Petroleum Resources Using Composite Underground Reservoir. In this work, models were first developed from material balance of Nigerian petroleum around a composite reserve. Process control concepts were introduced to obtain the transfer functions so that as input functions are varied, new models are obtained, to note which input have the best impact. Hubbert oil depletion concept was employed for the peak determination. The Nigerian Petroleum Data were obtained from the Department of Petroleum Resources (DPR) of the Ministry of Petroleum and Minerals Resources, 7 Kofo Abayomi Street, Victoria Island, Lagos, as the experimental data for 57 years giving 57 data points. MatLab Package 7.9 version was employed in the mathematical computations and curve-fittings. From the curve-fitted plots, It is found that the Nigerian oil reserve will finish in the year 2682AD and the gas will follow sooth in the year 3151AD. International Journal of Emerging Technologies in Engineering Research (IJETER) Volume 5, Issue 8, pp. 1 - 9
25Kamalu, C.I.O, Okere, P.C., Orga, A.C., Opebiyi, S.O, Onu, C and Obijiaku, J.C 2017 Modeling the Axial Temperature Distribution of a Tongue of Oxyacetylene Flame In this piece of work, two models (I and II) relating temperature distribution to the axial length in the flame are developed and compared. Experimental data from other researchers work on the internet were employed to validate the models through curve fitting using MATLAB toolbox 7.9. The result showed that model 15 is far better than model 11 as seen from their R2 of 0.9998 and 0.93254 respectively. Model 15 is also less cumbersome in derivation and development than model 11. It has a single equation as compared to a pair of equations of models 11,so that, its declared peak length is adjudged better than that of model 11 i.e. 2.262cm and 2.00014cm respectively all at the same peak temperature of 35000C. Model 13 fairly agrees with the so called Kamalu’s hypothesis in terms of peak length. The knowledge of the result of this work can be applied in the welding industry or wherever flame length is being determined. International Journal of current Innovation Research Vol. 3, Issue 11, pp. 867- 872
26Oli, S.C., Kamalu, C.I.O., Obijiaku, J.C., Opebiyi, S.O., Oghome, P., Nkwocha, A.C. A Study on the Bleaching Properties of Locally Sourced Clay (Upkor Clay) For the Processing of Palm Oil. The bleaching properties of Ukpor Clay (a locally sourced clay) were studied and compared with that of imported bleaching earth for use in the bleaching of Crude Palm Oil. The effect of using the different bleaching earths on Free Fatty Acid and Peroxide value was evaluated. One factor at a time experiment was also used to determine the effect of Bleaching Temperature, Time and Adsorbent-to-Oil ratio and finally response surface methodology was used to study the effect of the three variables on bleaching on Palm Oil and determination of optimal bleaching conditions. It was observed that bleaching of Palm Oil increased the Free Fatty Acid content but reduced the Peroxide. It was also observed that FFA for the bleached palm oil reduces with increase in bleaching temperature, for both the imported bleaching earth and Ukpor clay, with the imported bleaching earth having a lower FFA value, about 1% below that of Ukpor clay, in all cases. The Bleaching efficiency increases with increase in temperature for both imported bleaching earth and Ukpor clay with the bleaching efficiencies of the imported bleaching earth and that of Ukpor clay being approximately equal at temperatures above 120OC. The bleaching efficiency also increases with increase in bleaching time or adsorbent-to-oil ratio for both imported bleaching earth and Ukpor clay. The three variables significantly affect bleaching efficiency at 95% confidence, with a good interaction among the variables. The optimum conditions for bleaching of crude palm oil using Ukpor clay are a temperature of 180OC for a time of 135mins and at an Adsorbent-to-Oil ratio of 0.05, at which it has a bleaching efficiency 80.50%. These results can be used to effectively exploit our locally sourced bleaching earth, especially in view of the contributions in this work and under the observed optimum conditions, for the processing or bleaching of palm oil. Key Words: Ukpor clay, imported bleaching earth, crude palm oil, bleaching properties, optimum conditions. International Journal of Modern Research in Engineering and Technology (IJMRET). Vol. 2, Issue 5, pp. 14 - 29
27Igwe, I.K.1, Obijiaku, J.C and Ogah, A.O. 2017 Enhancing The Performance Of Ubakala Clay For Use As Drilling Mud. Drilling mud. A sample of Nigerian clay (Ubakala clay) was used for the project. The clay sample was collected in a raw state, processed and experiments conducted on viscosity which is a very important property of drilling mud. Various concentrations of sodium carbonate were mixed with the clay sample and experiments were conducted to determine the viscosities of the control and the clay-sodium carbonate mixture at periodic time intervals and various speeds of agitation. Response Surface Methodology was used, and with the aid of a MATLAB programming, to study the data obtained from the experiment. The results showed that sodium carbonate concentration, speed of agitation and their various interactions terms and quadratic terms are the significant variables in the statistical model with time being the least significant of the three factors studied. Furthermore, on analysis of the kinetics of the process, a Gaussian model, having the highest values of R2 (50% for Gaussian model, and 25% each for Exponential and Exponential Power models) and the lines of best fit, effectively describes the kinetics of the process and the viscosity of the clay samples in relation to time, concentration of sodium carbonate and speed of agitation. Further work on the Gaussian model gave rise to a new model that can be used to determine the values of the kinetic constants. This new model showed that a speed of agitation between 300rpm and 600rpm gave the best result for the process. International Journal of Engineering Sciences &Management Research Vol. 4, Issue 10,. pp 37 -53
28Kamalu, C.I.O., Okere P.C., Nwakaudu M.S., Onyelucheya O.E., Obijiaku J.C., Anyanwu E.E. Predictive Modeling and Analysis of Nigerian Petroleum Depletion Using a Composite Underground Reservoir In this work, models were developed from material balance of Nigerian petroleum around a composite reserve. Process control concepts were introduced to obtain the transfer functions so that as input functions are varied, new models are obtained, to note which input have the best impact. Hubbert oil depletion concept was employed for the peak determination and dumbbell intersection. The Nigerian Petroleum Data were obtained from the Department of Petroleum Resources (DPR) of the Ministry of Petroleum and Minerals Resources, 7 Kofo Abayomi Street, Victoria Island, Lagos, as the experimental data for 57 years giving 57 data points. MatLab Package 7.9 version was employed in the mathematical computations and plotting of graphs. It is found that the Nigerian oil reserve will finish in the year 2682AD and the gas will follow sooth in the year 3151AD. This result is accurate to an R2 of 0.9955 - 0.9963 for oil and 0.9979 - 0.9983 for gas, as shown in model 5 (table 4.2). This result can be used by Nigerian government for planning, diversification of the economy and international bargaining and positioning in OPEC. Keywords: Nigerian petroleum depletion, composite underground reservoir, predictive modeling and analysis, transfer and input functions, intersection of dumbbell profiles. International Journal of Innovative Engineering and Emerging Technology (IJIEET) Vol. 3, Issue 4., pp No. 01-13
29Kamalu, C.I.O; Iwot, O.A; Okere, P.C; Ogah, A.O; Obijiaku J.C (2017) Modeling and Analysis of the Relationship of Octane, Cetane and Ignition Delay Usage This work successfully modeled and validated the relationship between octane number and cetane number for conversion from diesel to petrol engine and vice versa. The Ignition Quality Tester (IQT) was used to carry out combustion experimental work on diesel fuel involving Ignition delay - temperature relationship as well as ignition delay - pressure relationship. The same was used to determine cetane number - ignition delay, %volume additive - increase in cetane number and octane number - cetane number relationships. Tests were conducted at constant pressure and temperatures of 145psi and 828K respectively. Experimental data were curve-fitted at R2 of 0.9982%, 0.9952%, 0.9954%, 0.9937% and 0.9991% for ignition delay - pressure, %volume 2-EHN additive - increase in cetane number, cetane number - ignition delay, ignition delay - temperature, and octane number -cetane number experiments respectively. The experimental data agree very well with derived models and in real life. Model validation accuracy for the combustion relating to octane-cetane relationship gives R2 value of 0.9991 which affirms that experimental data agree well with the derived model. The work can be utilized in automobile industry to ascertain the equivalence of converting from one fuel to the other vis-à-vis octane and cetanes based fuels and also correlate variable parameters in fuel combustion as the case may be. International Journal of Emerging Technologies in Engineering Research (IJETER) Volume 5, Issue 7, pp. 98 - 107
30Kamalu C.I.O., Dairo, M., Egbufor, U.C., Chukwu, M.M., Onu, C., Obijiaku, J.C.2018 Statistical Optimization of the Total Reducing Sugars Yield From the Dilute Acid Hydrolysis of Corn Stover. The dilute acid hydrolysis of corn stoverusing sulphuric acid at different concentrations (2.32-5.68% w/w), hydrolysis times (18-52 min) and hydrolysis temperatures (76-144°C) were studied. The total reducing sugar present in the hydrolysate was quantified using DNS Method. A five level Central Composite Design (CCD) was used to develop a statistical model for the optimization of process variables which are acid concentration, hydrolysis time and hydrolysis temperature. Response Surface Methodology (RSM) was employed for the optimization of the dilute acid hydrolysis conditions. The optimal hydrolysis conditions that resulted in the maximum total reducing sugar concentration were acid concentration of 4.99% (w/w), hydrolysis temperature of 90.09°C and hydrolysis time of 44.99 minutes. Under these conditions, the total reducing sugar concentration was obtained to be 20.9575 g/L. Quadratic model selected for the analysis was then validated. International Journal of Engineering Sciences & Management Research Vol. 5, Issue 9., pp. 1- 12

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