Koyejo Oduola | University of Port Harcourt (original) (raw)

Papers by Koyejo Oduola

Advanced Materials Research, 2007

Journal of Applied Polymer Science, 2000

ABSTRACT Anhydride-containing polyperoxides were synthesized by copolymerization of 5−tert−butylp... more ABSTRACT Anhydride-containing polyperoxides were synthesized by copolymerization of 5−tert−butylperoxy−5−methyl−1−hexen−3−yne with either maleic anhydride or its blends with styrene. The integral composition of the polyperoxides was theoretically calculated as the copolymerization process proceeded and its direct experimental evidence was obtained. In macrochain-formation behavior, the process was found to be consistent with the generally accepted regularities of binary and ternary copolymerization. By employing their polymerizational transformations, water-soluble polyperoxides exhibiting surface activity and initiating properties were obtained. In aqueous solutions, such polyperoxide surfactants form micellelike colloidal structures. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1217–1227, 2000

Local cassava starches and an imported starch were characterized and evaluated for their performa... more Local cassava starches and an imported starch were characterized and evaluated for their performance as drilling fluid additives. Two local cassava cultivars, TMS 98/0581 and TMS 96/1632, starches and an imported starch were characterized by using X-ray diffraction techniques. Bentonite mud beneficiated with the starches were subjected to API viscosity and filtration tests. The local and imported starches were classified as B type crystal structure. The starches average particle sizeswere 51.63nm, 23.57nm and 57.94nm for TMS 98/0581, TMS 96/1632 and imported starches respectively. The crystalline indices were between 22 and 35, while average specific surface areas were 151.65, 361.28 and 142.04 m 2 /g for TMS 98/0581, TMS 96/1632 and imported starches respectively. The morphology indices, ranges were from 0.5 to 0.7485. The structural properties of TMS 98/0581 starch were found to be significantly close to that of the imported starch and were observed to be closer in performance as drilling fluid additive than TMS 96/1632. Local cassava starches with structural properties as TMS 98/0581, could serve asgood substitute for drilling operation. The viscosity and fluid loss control results of the local samples compared favourably with the imported one.

The reaction rate constant of bentonite polymer drilling mud was expressed in terms of apparent v... more The reaction rate constant of bentonite polymer drilling mud was expressed in terms of apparent viscosity and used to evaluate the thermal stability and effectiveness of aged muds. The muds were formulated from two local cassava starches and two imported polymers. The rheological performances of the muds were determined. Model equation was developed to relate the apparent viscosity of bentonite muds before and after 16 hours aging. Model rateconstants were determined for the bentonite-polymer muds at 80 o F, 120 o F, 150 o F and 190 o

Rheological model parameters were determined for bentonite muds treated with two local cassava st... more Rheological model parameters were determined for bentonite muds treated with two local cassava starches (TMS 98/0581 and M98/0068) and an imported starch. The parameters were that of Power Law, Casson and Herschel-Bulkley models which predict the shear stress-shear strain rate relationships. Physicochemical properties were determined for the starches. Herschel-Bulkley model provided the best correlation with experimental data, while Casson model was next. Correlation between Casson and Herschel models yield stresses was good. The yield stress was found to increase with increase in temperature and behaved differently with the starches. It was found to be highest at 1.0 percent of M98/0068 starch concentration in the bentonite mud system. However, the yield stress did not differ significantly for the mud system with TMS 98/0581 starch concentrations. For the imported starch, the yield stress was highest at 2.0 percent concentration at 80 o F and 120 o F, while it was highest at 0.5 percent at 150 o F and 190 o F. The yield stresses ranged between 3 and 30 Pa for the bentonite starch mud systems investigated. The model parameters predicted the shear stress-shear rate relationships for bentonite-local polymer drilling mud system and supported the utilization of the local cassava starches as drilling fluid additives.

The quest for techniques to recover the remaining 60–80% of the original oil in place (OOIP) left... more The quest for techniques to recover the remaining 60–80% of the original oil in place (OOIP) left upon conventional oil recovery methods has become imperative. Alkaline–surfactant–polymer (ASP) flooding has emerged as one of the most promising and widely applicable techniques due to its significant improvement on the displacement and sweep efficiency. A number of the attempts has been devoted to investigating the combination of up to three substances to form the appropriate ASP system for a given application, which has been without a number of technical challenges. This paper reviews the possibility of employing an appropriately engineered synthesis of an ASP substance which incorporates all the three components in one. Research has been conducted into the suitability of an ASP system formulated using locally available and thus economically viable raw materials (Ogbonor seeds, Irvingia gabonensis, potash, and salt). The study shows the best level of salinity needed for the retention of the polymer gel viscosity is 30g/l and the maximum viscosity of the polymer solution is 1.086, in the absence of additives. This brought to a conclusion that the chosen additive (potash) does not have a significant effect on the polymer solution that will result in highest viscosity which enhances a good percentage of oil recovery. Polynomial models relating the resulting polymer viscosity with concentration and salinity have been developed, applicable for predicting polymer viscosity at different concentrations of salt and additive.

Selected local cassava (Manihot esculenta Crantz) starches were investigated as additives for wat... more Selected local cassava (Manihot esculenta Crantz) starches were investigated as additives for water-based drilling mud. Cassava cultivars, TMS 30572, TMS 98/0505, TMS 98/0581, M98/0068, TMS 92/0057, TMS 96/1632, NR8082, TME 419, TMS 97/4779 and TMS 01/1412 were processed to starches and used for drilling mud treatment at 0.5, 1.0 and 2.0 percent. Polyanionic cellulose (PAC), xanthan gum (XG) and industrial starch-modified drilling muds served as controls. Physicochemical analysis of the starches showed significant differences in their properties. Viscosity and fluid loss profiles revealed that some of the local cassava starches had comparable performance with the commercial polymers. The optimal concentration of the industrial starch in the mud system was 0.5 percent, while that of the local starches were between 0.5 and 1.0 percent. PAC and XG performed best at 1.0 and 2.0 percent respectively. The highest viscosities were shown by muds treated with TMS 98/0581, XG, TMS 96/1632, M98/0068, TMS 92/0057 and PAC, arranged in decreasing order. And the lowest fluid losses were exhibited by muds with PAC, industrial starch, XG, TMS 98/0581 and M98/0068 in increasing order. Viscosity and fluid loss models as functions of cassava starch physicochemical properties were developed. Increase in starch content, amylose content, solubility index would readily increase viscosity, while high starch content, amylopectin content, solubility index and pH would reduce the fluid loss. Local starches from TMS 98/0581, TMS 96/1632 and M98/0068 and TMS 92/0057 could be used as a substitute in drilling mud as viscosity enhancers and fluid loss control agents in Nigeria.

The influence of filler size and content on the mechanical and rheological properties (thermal co... more The influence of filler size and content on the mechanical and rheological properties (thermal conductivity, impact strength, hardness and melt flow index (MFI) of Al 2 O 3 /high-density polyethylene (HDPE) composites have been studied. Concentration of alumina was varied up to 30% by weight. The composites were prepared using a two-roll mill and then test specimens were prepared by injection molding. Thermal conductivity, hardness, impact strength and melt flow rate of the composites increased with decreased particle sizes and increased particle content with exceptions at certain concentrations due to non-uniform distributions of particles and agglomerates formed by the particles. As an example, the best integrated thermal conductivity was shown by a 75 micron-Al 2 O 3 /HDPE composite at 15% wt. alumina content, while the 212 micron-Al 2 O 3 /HDPE composite at 20 wt.% alumina content. For the same alumina content of 15% concentration by weight out of the three particle sizes. 75, 212 and 850 microns, the 75 micron-Al 2 O 3 /HDPE composite gave the highest thermal conductivity, which was nearly 50% higher than that of pure HDPE. Enhancement in impact strength and Hardness Rockwell were up to 300% and 400% as compared to the pure HDPE respectively. The Al 2 O 3 with small particle size is generally more efficient for the enhancement of the impact strength.

Gasoline is a highly flammable liquid derived mainly from crude oil that is used primarily as an ... more Gasoline is a highly flammable liquid derived mainly from crude oil that is used primarily as an energy source for internal combustion engines. To be competitive, gasoline must meet certain standards of high quality such as Octane number, Ried Vapor Pressure (RVP), and minimal environmental pollutions. This work aims at optimizing the production of a high-quality gasoline blend that meets the Octane number, RVP, Economic and Environmental standards, using varying oxygenates. The gasoline blending was executed by employing the linear programming solver application in Microsoft excel using four blending components namely the Fluid catalytic cracking gasoline (FCCG), Straight run naphtha (SRN), Straight run gasoline (SRG), Butane, and varying Oxygenates. The Blending process was simulated in ASPEN HYSYS simulation software, and the output product was tested for pollutant emissions in the same software. The selected blend was further optimized to minimize emission using the Response Surface Methodology in MINITAB version 18. Upon gasoline blending optimization and emissions testing, four blends met our specifications namely, the MTBE blend, the ETBE-blend, the Ethanol-blend, 1-Butanol blend. After a simple weighting method, the Ethanol was selected as the optimal blend having a net savings of 67.09 tons/ year and 476tons/year of NOx and TVOC emissions respectively, a net increase of 16.35 tons/year of TTC emissions. The Blend was further optimized using RSM. The optimization results showed that SRG was the main contributor to NOx emissions, ethanol was a significant contributor to the TTC emissions while Butane had no effect of both emissions. The new optimized ethanol-blend gave a further 90.42% reduction in NOx emissions, and 67.85% reduction in TTC emissions, but with an increased amount of ethanol in the blend. The economics of a gasoline blending plant was evaluated, giving a pay-back period of 2.46 year, NPV @ 10 th year of $177.6 million, an internal rate of return of 57.36%, and a profitability index of 3.04. This showed that the process would be highly profitable.

This research was focused on the selection of the appropriate thin-layer models that best describ... more This research was focused on the selection of the appropriate thin-layer models that best described the drying characteristics of the French horn plantain used in the experiment. The drying of the 5mm thickness size plantain samples occurred at 40 o C, 50 o C, 60 o C and 70 o C temperatures until the equilibrium condition was attained. The experimental moisture ratio values at each temperature were fitted to Lewis, Page and Modified-page thin-layer models. The Lewis model has average chi square and average coefficient of determination of 0.0012 and 0.9802 respectively while Modified Page has 0.0009 and 0.9879 respectively. The results show that Page model has the least average chi-square (Χ 2) value and highest coefficient of determination (R 2) value of 0.0008 and 0.9922 respectively. Therefore, Page model best described the drying characteristics of the plantain sample within 40 o C-70 o C temperature range.

The thin-layer drying characteristics of plantain was analysed at different temperatures. The pla... more The thin-layer drying characteristics of plantain was analysed at different temperatures. The plantain sample was sliced to 5mm thickness size and dried at 40 o C, 50 o C, 60 o C and 70 o C. The moisture content (dry basis), moisture ratio, effective diffusivity and activation energy were determined within the temperature range. The moisture content of cooking plantain on dry basis was found to be 1.70g moisture/g dry sample at the beginning of the drying. The highest moisture removal of 1.58g/g dry sample occurred at the 70 o C drying temperature. The effective diffusivity obtained from the experimental data is within the range 2.85x10-10-6.65x10-10 m 2 /s while the activation energy is 476.54J/smol. The rate of moisture removal, moisture ratio slope, effective diffusivity and activation energy values obtained from the experimental values increase with the drying temperature.

— The re-refining of waste lubricating oil using activated Ukpor clay as an adsorbent was investi... more — The re-refining of waste lubricating oil using activated Ukpor clay as an adsorbent was investigated. Clay activation was performed using sulphuric acid (H 2 SO 4) with equivalent concentrations varying between 0.5 – 2 mol/L at a constant temperature of 90 o C for 3.5 hours. The adsorption process was studied over a fixed amount of adsorbent at ambient conditions. Adsorbent performance was determined by its effectiveness in enhancing the properties of the waste oil and in removing trace metal ions contained in them. Furthermore, the effect of contact time and the adsorption performance of the adsorbent in the recycling treatment of the lubricating oil were evaluated. The kinetic data were modelled using the Pseudo-first order, the Pseudo-second order, the intra particle diffusion and the Elovich kinetic models. Analysis carried out on the lubricating oil showed the presence of many heavy metal ions and trace elements. Ca, Pb and Zn had the highest concentrations of 804, 398 and 222 mg/L respectively, while Ba had the least concentration of 0.1 mg/L. However, with treatment using this adsorbent, the concentrations of Ca, Pb and Zn were found to considerably reduce to 3.6, 5.6 and 0.01 mg/L respectively. The concentration of Ba was equally found to reduce to 0.01 mg/L, wherein the clay sample treated with 2 mol/L H 2 SO 4 gave the best result in terms of improvement in the properties of the lubricating oil as well as on the percentage removal of these heavy metals and trace elements. For best describing the process within the adsorbent and with a high correlation coefficient (R 2 value > 0.999), kinetic data were best fitted by the Pseudo-second order kinetic model and this result indicates that this adsorbent provides a good medium for the re-refining of waste lubricating oil.

Journal of Applied Polymer Science, 2000

The polymer peroxide surfactants obtained by copolymerization of a peroxide monomer with maleic a... more The polymer peroxide surfactants obtained by copolymerization of a peroxide monomer with maleic anhydride were either physically or chemically sorbed on the dispersed-phase surfaces, for example, on mineral fillers and latex particles. Subsequent initiation of graft copolymerization from the surface resulted in the formation of interfacial compatibilizing polymer layers in water emulsions and dispersed-filled polyethylene. The morphology of the resulting filled polymer was characterized by scanning electron microscopy.

Introduction of Microbial fuel cells (MFCs) technology has shown metabolic degradation of wide ra... more Introduction of Microbial fuel cells (MFCs) technology has shown metabolic degradation of wide range organic
substrates in wastewater and sludge. Intensified studies are geared towards elucidation behavior of bacteria in the
process. This review presents the fundamentals of MFC technology and its application as power source for subsea
and biomedical devices as well as biotreatment of wastewater. A wide variety of industrial, agro/agro allied and
domestic wastewater as sources of organic and inorganic substrate is effectively converted to electricity with about
40-90% COD and BOD reduction, while achieving applicable power generation and Columbic efficiency. A good
knowledge of the MFC is required for sustainable improvement of the MFC application.

Limitations often encountered in the polymer molecular weight MW and molecular weight distributio... more Limitations often encountered in the polymer molecular weight MW and molecular weight distribution MWD
has promoted research into unconvectional free radical initiators. A traditional free radical macromolecular
initiator has recently been investigated for peroxide modification of the surface of disperse fillers and pigments
with the objective to enabling their participation in the elementary reactions of polymerization: initiation, chain
propagation and termination, resulting in the formation of an interfacial polymer layer with macromolecules
grafted to the surface. Polymerization kinetics of vinyl monomers initiated by this amine-containing initiator
under homophase and heterophase conditions has been examined with respect to the effect on the resulting
polymer MW by means of dilatometric and viscosimetric measurements. Poly(methyl methacrylate) formed
under corresponding conditions is characterized by about 2-3 times higher values of MW as compared to
polystyrene. In particular, significant deceleration of the termination reactions upon interaction of growing
macroradicals due to diffusion complications has been observed. High polymerization rate with the production
of high-MW products resulting from the application of high-MW initiator, as compared to convectional low-MW
peroxides has been attributed to the polymerization – polyrecombination mechanism of the formation of
macromolecule

Immobilization of an amine-containing peroxide macroinitiator APM onto solid mineral surfaces has... more Immobilization of an amine-containing peroxide macroinitiator APM onto solid mineral surfaces has been achieved via physical/chemical adsorption of its macromolecules from solution. A systematic variation of reaction parameters upon graft polymerization initiated by surface attached APM including nature of monomer and solvent has been conducted. The effect of solvent and nature of monomer on the overall constant of polymerization, effective activation energy,
initiation efficiency as well as other parameters of elementary stages of the process has been established. It has been revealed that the involvement of TiO2 particles with the surface-attached radicals in the heterogeneous polymerization process profoundly influenced all the elementary stages, particularly chain transfer and termination.

Advanced Materials Research, 2007

Journal of Applied Polymer Science, 2000