Browsing by Author "Dodoo-Arhin, D."

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Activated cashew carbon-manganese oxide based electrodes for supercapacitor applications
(Scientific African, 2023) Boamah, R.; Agyei-Tuffour, B.; Dodoo-Arhin, D.; Nyankson, E.; Brobbey, K.J.; et al.
The current global energy challenge which affects most developing countries in particular, is of major source of concern today. The availability of less expensive techniques of storing excess generated energy is critical to the success of the renewable energy roadmaps implementation. In this study, hydrothermal and chemical leaching methods have been used to synthesize MnO2 nanoparticles using KMnO4 and MnSO4 as precursors at 140 °C and from natural local manganese ore. Activated Carbon (ACF) have also been produced from agricultural Cashew biomass waste, through a physical carbonization and KOH activation process using temperatures of 700 °C – 900 °C for periods between 1 and 2 h. The as-prepared materials have been characterized via XRD, Raman, FTIR, SEM. Electrochemical performance measurements (CV, EIS and GCD) were carried out on the prepared electrodes. The specific capacitance values obtained were in the range of 2.8 F/g - 6.5 F/g at different scan rates of 20 mV -50 mV respectively in a potential range of -0.4 to +0.4 V and -0.4 to +0.6 V for the various types of electrodes
Assessment of fluoride removal in a batch electrocoagulation process: A case study in the Mount Meru Enclave.
(Scientific African, 2021) Mureth, R.; Machunda, R.; Njau, K.N.; Dodoo-Arhin, D.
The presence of excessive amounts of fluoride than prescribed standards has been reported in various sources of domestic water supply around the slopes of Mount Meru and other parts in Tanzania. Efforts to remove the excessive fluoride have been carried out using various technologies. In this study, electrocoagulation experiments were carried out to as- sess its efficiency on fluoride removal. The fluoride concentration tested ranged from 1.37 to 48 mg/L in both synthetic and natural waters. The voltage applied in the electrocoag- ulation (EC) process ranged from 0 to 50 V while maintaining pH values of 4 to 9. The representative experimental results for the Ngarenanyuki river water with initial fluoride concentration of 29.5 mg/L accomplished a removal efficiency of 90% at an optimal elec- trolysis time of 30 min, an applied voltage of 30 V and an optimal pH of 6. The method showed efficient fluoride removal in water to allowable limits by World Health Organiza- tion (WHO) and Tanzania Bureau of Standards (TBS) (1.5 mg/L). Despite the voltage applied (30 V), the pH at neutrality remained unchanged thus making the process more efficient. At this voltage (30 V) the process has been reported previously also to have the capability of disinfecting the water and hence rendering such water safe for use.
Awaso bauxite red mud-cement based composites: Characterisation for pavement applications
(Case Studies in Construction Materials, 2017-12) Dodoo-Arhin, D.; Nuamah, R.A.; Agyei-Tuffour, B.; Obada, D.O.; Yaya, A.
This paper presents the development of Bauxite residue (red mud) based cement composite mortar blocks for applications in pavement construction. The experimental techniques considered include the structural, thermal, morphological and microscopy analysis of the raw bauxite and red mud samples calcined at 800 °C. Composite mortar blocks of different batch formulations were produced and their physicochemical properties were investigated. The results show that the compressive strength of the as-prepared composite mortar blocks increased by ∼40% compared to the type M mortar strength of ∼2500 N/mm2. The load bearing applications of the composites are discussed to influence the adoption of the calcined red mud as supplement in the production of low-cost Portland cement based composite mortar blocks for the construction industry. © 2017
Catalytic abatement of CO species from incomplete combustion of solid fuels used in domestic cooking
(Heliyon, 2018-08) Obada, D.O.; Peter, M.; Kulla, D.M.; Omisanya, N.O.; Atta, A.Y.; Dodoo-Arhin, D.
This study reveals a first time approach to catalytic based interventions primarily on indoor air pollution emanating from commercial and household solid fuel burning in a region in Nigeria. An intensive survey of the temperatures at different locations in the common stoves used for cooking was conducted so as to ascertain temperatures suitable for catalyst efficiency and stability. Furthermore, cobalt and iron based catalysts were prepared using ultra stable Y type zeolite as supports. The synthesized catalysts were characterized for its physico-chemical properties. The catalytic efficiency of the supported catalysts was tested using simulated exhaust gases in a fix bed reactor. The study further explored real time testing of the catalyzed ceramic monolith using two different wood species. First, the best catalyst in terms of simulated exhaust testing was selected. Consequently, a small layer of zeolite Y was deposited at 3% of the monolith weight to enhance the subsequent adhesion of the best catalyst powder to the structured monolith. Then to catalyze the zeolite Y wash-coated monolith with the cobalt precursor, the dip coating technique was used. From the results, the average values of temperatures observed from the surveyed cook stoves using wood and plant residue as fuel were confirmed to be in the range of 203–425 °C which is considered suitable for catalysts activity. The Co/ZY catalyst showed approximately 100% CO conversion (T 100 ) at 250 °C for initial CO concentration of 1000 ppm, making it the most effective, while T 100 was increased to 275 °C and 325 °C for Fe/ZY and Co-Fe/ZY catalyst respectively at an exhaust residence time of 20000 h −1 . The catalytic converter in real time testing for CO abatement performed well for both wood species. Only minor differences have been noticed. © 2018 The Authors
Characterizing Teline Monspessulana as a Green Sustainable Source of Biofibers
(BioResources, 2018-01) Pesenti, H.; Zumelzu, E.; Gacitua, W.; Torres, M.; Castillo, J.; Sanchez, A.; Leoni, M.; Dodoo-Arhin, D.
Invasive Teline monspessulana can be an important source of biomass to supply fibers for the rising demand of cellulose bioproducts, especially for the development of advanced materials. Its fibers can be extracted via a thermo-alkaline process at 170 °C with 40 g/L of sodium hydroxide (NaOH) and characterized by crystallographic, thermo-analytical, and mechanical techniques. The cellulose proportion in the wood of this species is approximately 47.6 wt.% ± 1.05 wt.%. However, its fibers are relatively small, and they have a wide range of aspect ratios from 25 to 287, with an average diameter of 9.3 μm ± 2.5 μm. These characteristics and mechanical properties make the fibers unattractive for the textile and paper industries. Meanwhile, crystalline cellulose was prevalent in the monoclinic phase, with a crystalline index and crystalline portion of 78 and 41%, respectively, observing crystal domains of c.a. 3.2 nm. Nanoindentation tests revealed favorable values of elastic modulus and hardness of c.a. 16 GPa and 0.28 GPa, respectively. Thus, this bioresource is expected to see promising applications in materials engineering, such as reinforcement in material composites, in drug delivery carrier, and electronic devices, among other biomultifunctional components.
Comparative analyses of rice husk cellulose fiber and kaolin particulate reinforced thermoplastic cassava starch biocomposites using the solution casting technique
(Wiley, 2021) Agyei-Tuffour, B.; Asante, J.T.; Nyankson, E.; Dodoo-Arhin, D.; Oteng-Peprah, M.; Azeko, S.T.; Azeko, A.S.; Oyewole, O.K.; Yaya, A.
he potential of biodegradable packaging materials from thermoplastic cassava starch (TPS) reinforced with rice husk cellulose fibers (RHCF) and kaolin particulates (KP) using the solution casting method has been presented. This involved the blending of TPS and RHCF/KP in a plasticizer of ~4 ml of glycerol and ~45 ml of distilled water at 125°C and stirred at 60 rpm until a gel was formed. The gel was cast into sheets and bone-shaped tensile specimens and allowed to dry for 5 days and characterized. The results show a semicrystalline structure for TPS with an ~36% increase in crystallinity after reinforcement. The O-H bond stretching and the C-H bending bonds due to starch–glycerol reactions were the common functional groups in TPS–RHCF biocomposites, and Si-O-C bonds were characteristics of the silica phase in the kaolin. The water vapor transmission rate (WVTR) reduced to ~34% with KP reinforcements from ~238 g/m.day to 177 g/m.day and to ~74 g/m.day and ~164% for TPS–RHCF. The strength increased with up to 50 wt% kaolin content; ~0.96 MPa yield strength and ~2.60 MPa ultimate tensile strength (UTS) were recorded. For the RHCF reinforced composites, TPS-50 wt% also showed high strengths of ~0.96 MPa yield strength and ~3.50 MPa UTS. The WVTR reduced as content of kaolin was increased. Typically, from 0 to 30 wt% volume fraction of kaolin, the WVTR was reduced by ~34% to 177 g/m.day for TPS–kaolin and by ~164% to ~74 g/m.day in TPS–RHCF. The as-prepared biocomposites have potential as good packaging materials.
A comparative study of DFT/LDA with higher levels of theory on π-π interactions: A typical case for the benzene dimer
(Journal of Computational Modeling, 2014) Yaya, A.; Tiburu, E.K.; Onwona-Agyeman, B.; Dodoo-Arhin, D.; Efavi, J.K.
A real challenge to theory. The problem arises from the kind of theoretical approaches employed to describe the nature of the non-covalent interactions. Various workers have described the interactions purely as Van der Walls whilst others consider it as a competition between many other forces. Present approaches describing these interaction effects are computationally expensive. We report a pseudo potential-base density functional theory (DFT) calculations within the local density approximation (LDA) and compared our results with other higher theories describing the - interactions. By using benzene dimer as a prototype species, we find that DFT/LDA compares favorably well with other descriptions as a reliable alternative method.
A comparative study of the mechanical integrity of natural hydroxyapatite scaffolds prepared from two biogenic sources using a low compaction pressure method
(Results in Physics, 2020-06) Dodoo-Arhin, D.; Akpan, E.S.; Dauda, M.; Kuburi, L.S.; Obada, D.O.
With a view to enhancing laboratory and application-based pedagogical approaches in bioengineering, a comparison of the physical, chemical and mechanical properties of natural hydroxyapatite produced from nonseparated animal bones (NB) and catfish bones (CB) obtained by thermal treatment and a low compaction pressure method has been reported in this study. The structure, morphology and surface chemistry of the processed biomaterials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and infrared spectroscopy, respectively. Uniaxial compaction using a pressure of 1 MPa was used on circular shaped hydroxyapatite scaffolds to measure the mechanical properties of the produced scaffolds. From XRD analysis, both samples showed prominent reflections of the hydroxyapatite phase, suggesting high crystallinity and phase stability. The morphology of the powders showed irregular shapes with large agglomerates for non-separated animal bones-derived hydroxyapatite as compared to more open pores in the catfish bones-derived hydroxyapatite. Hydroxyapatite produced from catfish bones revealed a microstructure with open pores which is useful in terms of cell adhesion. The hydroxyapatite products revealed Ca/P ratios of 1.58 and 1.63 for catfish bones (CB) and non-separated animal bones-derived hydroxyapatite, respectively. Improvements in the fracture toughness were observed for CB in comparison with NB. Calculated fracture toughness values were 5.72 MPa. m1/2 and 2.35 MPa. m1/2 for catfish bones and non-separated animal bones-derived scaffold respectively. These results are useful in terms of the production and biomedical applications of natural hydroxyapatite.
A comparative study of the mechanical integrity of natural hydroxyapatite scaffolds prepared from two biogenic sources using a low compaction pressure method
(Results in Physics, 2020) Akpan, E.S.; Dauda, M.; Kuburi, L.S.; Obada, D.O.; Dodoo-Arhin, D.
With a view to enhancing laboratory and application-based pedagogical approaches in bioengineering, a comparison of the physical, chemical and mechanical properties of natural hydroxyapatite produced from nonseparated animal bones (NB) and catfish bones (CB) obtained by thermal treatment and a low compaction pressure method has been reported in this study. The structure, morphology and surface chemistry of the processed biomaterials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and infrared spectroscopy, respectively. Uniaxial compaction using a pressure of 1 MPa was used on circular shaped hydroxyapatite scaffolds to measure the mechanical properties of the produced scaffolds. From XRD analysis, both samples showed prominent reflections of the hydroxyapatite phase, suggesting high crystallinity and phase stability. The morphology of the powders showed irregular shapes with large agglomerates for non-separated animal bones-derived hydroxyapatite as compared to more open pores in the catfish bones-derived hydroxyapatite. Hydroxyapatite produced from catfish bones revealed a microstructure with open pores which is useful in terms of cell adhesion. The hydroxyapatite products revealed Ca/P ratios of 1.58 and 1.63 for catfish bones (CB) and non-separated animal bones-derived hydroxyapatite, respectively. Improvements in the fracture toughness were observed for CB in comparison with NB. Calculated fracture toughness values were 5.72 MPa. m1/2 and 2.35 MPa. m1/2 for catfish bones and non-separated animal bones-derived scaffold respectively. These results are useful in terms of the production and biomedical applications of natural hydroxyapatite.
Crack behaviour and mechanical properties of thermally treated kaolin based ceramics: The influence of pore generating agents
(Applied Clay Science, 2020-06-05) Dodoo-Arhin, D.; Obada, D.O.; Dauda, M.; Anafi, F.O.; Ahmed, A.S.; Ajayi, O.A.; Csaki, S.; Bansod, N.D.; Kirim, I.I.; Momoh, O.J.
In this study, the crack behaviour of porous kaolin based ceramics was experimentally investigated. The samples (ceramic bodies) were fabricated with the inclusion of pore formers in determined proportions and subjected to heat treatment. Next, the apparent porosity of the samples was measured using the water immersion method. The values confirmed the increased porosity (up to 47%) for the samples with embedded pores. We speculated that the open pores on the surface of the samples which were quite evident, especially with styrofoam as pore formers, may also have penetrated through, hence the enhanced porosity values for the samples. Acoustic emission (AE) activity which reveals the formation of microcracks in the ceramics due to the different thermal expansion coefficients in the cooling stage was recorded for the samples. The first signals of AE counts appeared at 800 °C, where the compressive stresses between the different phases (particles with different coefficients of thermal expansion) led to an appearance of microcracks. By introducing porosity to the samples, the AE signals were less pronounced. This was evident for the samples with sawdust as pore formers, and it was inferred that in this sample, microcracking was suppressed. As a validation protocol for AE measurements, mechanical measurements on the produced samples were conducted through the indentation technique to obtain the fracture toughness of the samples. The results conformed to the observation made during AE measurements. The samples embedded with sawdust as porogens produced the highest fracture toughness of 4.77 MPa.m1/2 by reason of the suppression of microcracking after heat treatment.
Dataset on the comparison of synthesized and commercial zeolites for potential solar adsorption refrigerating system
(Data in Brief, 2018) Sowunmi, A.R.; Folayan, C.O.; Anafi, F.O.; Ajayi, O.A.; Omisanya, N.O.; Obada, D.O.; Dodoo-Arhin, D.
The purpose of this dataset is to provide a comparison between synthesized and commercial 4A and 13X type zeolites. Metakaolin produced from the calcination of beneficiated kaolin at 750 °C for 4 h was dealuminated using sulphuric acid to get the required silica to alumina ratio for the zeolite synthesis. Zeolite 4A and 13X samples were characterized along-side with the commercial variants using X-ray fluorescence (XRF), X-ray diffraction (XRD), Brunauer, Emmett and Teller (BET) and scanning electron microscopy (SEM) techniques. These analyses revealed that, the zeolites synthesized are of comparatively acceptable quality. The pore size of 120.859 nm, pore volume of 0.0065 cm3/g and surface area of 22 m2/g were obtained from BET analyses for zeolite 4A synthesized from kaolin, while the commercial zeolite 4A used as control gave pore size of 58.143 nm, pore volume of 0.2462 cm3/g and surface area of 559.13 m2/g. In the same vein, the pore size of 10.5059 nm, pore volume of 0.135847 cm3/g and surface area of 324.584 m2/g were obtained from BET analyses for zeolite 13X synthesized from kaolin, while the commercial zeolite 13X gave pore size of 7.2752 nm, pore volume of 0.135951 cm3/g and surface area of 310.0906 m2/g
Dataset on the comparison of synthesized and commercial zeolites for potential solar adsorption refrigerating system
(Data in Brief, 2018-10) Sowunmi, A.R.; Folayan, C.O.; Anafi, F.O.; Ajayi, O.A.; Omisanya, N.O.; Obada, D.O.; Dodoo-Arhin, D.
The purpose of this dataset is to provide a comparison between synthesized and commercial 4A and 13X type zeolites. Metakaolin produced from the calcination of beneficiated kaolin at 750 °C for 4 h was dealuminated using sulphuric acid to get the required silica to alumina ratio for the zeolite synthesis. Zeolite 4A and 13X samples were characterized along-side with the commercial variants using X-ray fluorescence (XRF), X-ray diffraction (XRD), Brunauer, Emmett and Teller (BET) and scanning electron microscopy (SEM) techniques. These analyses revealed that, the zeolites synthesized are of comparatively acceptable quality. The pore size of 120.859 nm, pore volume of 0.0065 cm3/g and surface area of 22 m2/g were obtained from BET analyses for zeolite 4A synthesized from kaolin, while the commercial zeolite 4A used as control gave pore size of 58.143 nm, pore volume of 0.2462 cm3/g and surface area of 559.13 m2/g. In the same vein, the pore size of 10.5059 nm, pore volume of 0.135847 cm3/g and surface area of 324.584 m2/g were obtained from BET analyses for zeolite 13X synthesized from kaolin, while the commercial zeolite 13X gave pore size of 7.2752 nm, pore volume of 0.135951 cm3/g and surface area of 310.0906 m2/g.
Datasets on the elastic and mechanical properties of hydroxyapatite: A first principle investigation, experiments, and pedagogical perspective
(Data in Brief, 2023) Osuchukwu, O.A.; Salihi, A.; Dodoo-Arhin, D.; et al.
The purpose of this data article is to report the quantum mechanical analysis by generalized gradient approximation (GGA) exchange-correlation functional using density functional theory (DFT). The predictions were based on the elastic constants and mechanical properties of stoichiometric hydroxyapatite (HAp) crystal. The elastic stiffness constants in hexagonal symmetry were obtained by fitting the Hookes’ law for the energy-strain and stress-stain relations. Some of the theoretical datasets were compared to measured mechanical properties of produced HAp pellets obtained through micro and nanoindentation experiments. The datasets show considerable anisotropy in the stress-strain behaviour and are discussed in the context of the mechanical properties of HAp which are useful for tissue engineering. We also provide a pedagogical snapshot on the use of the datasets herein to teach and interpret DFT based atomistic simulations in a typical blended online teaching set-up for engineering students using a new pedagogy, CACPLA (Communicate, Active, Collaborate, Practice, Learning and Assessment).
DNA hybridisation sensors for product authentication and tracing: State of the art and challenges
(South African Journal of Chemical Engineering, 2019-01) Hlongwane, G.N.; Dodoo-Arhin, D.; Wamwangi, D.; Daramola, M.O.; Moothi, K.; Iyuke, S.E.
The wide use of biotechnology applications in bioprocesses such as the food and beverages industry, pharmaceuticals, and medical diagnostics has led to not only the invention of innovative products but also resulted in consumer and environmental concerns over the safety of biotechnology-derived products. Controlling and monitoring the quality and reliability of biotechnology-derived products is a challenge. Current tracking and tracing systems such as barcode labels and radio frequency identification systems track the location of products from primary manufactures and/or producers throughout globalised distribution channels. However, when it comes to product authentication and tracing, simply knowing the location of the product in the supply chain is not sufficient. DNA hybridisation sensors allows for a holistic approach into product authentication and tracing in that they enable the attribution of active ingredients in biotechnology-derived products to their source. In this article, the state-of-the-art of DNA hybridisation sensors, with a focus on the application of graphene as the backbone, for product authentication and tracing is reviewed. Candidate DNA biocompatible materials, properties and transduction schemes that enable detection of DNA are covered in the discussion. Limitations and challenges of the use of DNA biosensing technologies in real-life environmental, biomedical and industrial fields as opposed to clean-cut laboratory conditions are also enumerated. By considering experimental research versus reality, this article outlines and highlights research needed to overcome commercialisation barriers faced by DNA biosensing technologies. In addition, the content is thought-provoking to facilitate development of cutting edge research activities in the field.
Effect of Ball Milling Time on the Physical, Thermal and Fracture Behaviour of 2MgO.2Al2O3.5SiO2 Precursors
(Silicon, 2019-08-06) Dodoo-Arhin, D.; Amlabu, B.A.; Umaru, S.; Dauda, M.; Obada, D.O.; Csaki, S.; Bansod, N.D.; Fasanya, O.O.
In this study, an evaluation has been made into the influence of milling time on the thermo-physical and fracture properties of a MgO-Al2O3-SiO2 system. The powdery and compacted formulation of the raw materials was studied using scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), Brunauer-Emmett-Teller (BET), thermogravimetric analysis (TGA), particle size distribution (PSD), Fourier Transform Infrared (FTIR), and acoustic emission technique (AE). The milling mechanism comprised of essentially three stages of milling time viz.; 120, 240, and 360 min respectively, with no milling (0 min) serving as the control batch. During the first stage of milling (120 min), it was observed that the greatest deformation occurred for the powdery formulation with increasing surface area, control batch inclusive, from 26.4 to 41.1 m2 g−1. It was also noticed that the density of the samples increased with progressive ball milling time. The mean crystallite sizes of un-milled and milled powders were calculated as 36.61, 48.82, 34.27 and 52.13 μm for control batch and powders milled at 120, 240, and 360 min, and denoted as MT0, MT120, MT240, and MT360, respectively. The mean crystallite sizes further reduced with increasing milling time up to 240 min and increased with milling time up to 360 min. These results were in line with the SEM findings. The acoustic emission (AE) intensity increased reaching a maximum at MT240, and a noticeable decline in the case of MT360 was observed. This indicated a gradual crack growth behavior because of the highly stressed powders used for the compacts.
The effect of decahydronaphthalin on the mechanical properties of montmorillonite reinforced polypropylene nanocomposites
(ARPN Journal of Engineering and Applied Sciences, 2012-10) Yaya, A.; Dodoo-Arhin, D.; Efavi, J.K.; Konadu, D.S.
The exceptional property exhibited by nanoparticles such as carbon nanotubes and silicate layers has been the major drive for research into advanced nanocomposites. The solution method is used to prepare polypropylene/clay nanocomposites with loadings of 2% and 5%. Decahydronaphthalin was used to disperse the clay and dissolution of the polypropylene matrix. The intercalation of macromolecular chains into the organoclay was evident from XRD and confirmed by SEM studies. Decahydronaphthalin was observed to have a considerable effect on the polymer matrix properties and the tensile moduli of the nanocomposites compared to the pristine polypropylene. Tensile moduli of nanocomposite treated with decahydronaphthalin have been observed to be lower than those of pristine polypropylene. The moduli of both the 2% and 5% PP/clay nanocomposite was 528 MPa and 547 MPa respectively. The pristine PP had a modulus of 794 MPa and that of the PP dissolved in decahydronaphthalin alone was found to be 639 MPa. © 2006-2012 Asian Research Publishing Network (ARPN).
Effect of mechanical activation on mullite formation in an alumina-silica ceramics system at lower temperature
(Emerald Group Publishing Ltd., 2016) Obada, D.O.; Dodoo-Arhin, D.; Dauda, M.; Anafi, F.O.; Ahmed, A.S.; Ajayi, O.A.; Samotu, I.A.
Purpose-This work aims to analyze the effect of mechanical activation on structural disordering (amorphization) in an alumina-silica ceramics system and formation of mullite most notably at a lower temperature using X-ray diffraction (XRD). Also, an objective of this work is to focus on a low-temperature fabrication route for the production of mullite powders. Design/methodology/approach-A batch composition of kaolin, alumina and silica was manually pre-milled and then mechanically activated in a ball mill for 30 and 60 min. The activated samples were sintered at 1,150°C for a soaking period of 2 h. Mullite formation was characterized by XRD and scanning electron microscopy (SEM). Findings-It was determined that the mechanical activation increased the quantity of the mullite phase. SEM results revealed that short milling times only helped in mixing of the precursor powders and caused partial agglomeration, while longer milling times, however, resulted in greater agglomeration. Originality/value-It is noted that, a manual pre-milling of approximately 20 min and a ball milling approach of 60 min milling time can be suggested as the optimum milling time for the temperature decrease succeeded for the production of mullite from the specific stoichiometric batch formed. © Emerald Group Publishing Limited.
The effect of NaOH catalyst concentration and extraction time on the yield and properties of Citrullus vulgaris seed oil as a potential biodiesel feed stock
(South African Journal of Chemical Engineering, 2018-03) Efavi, J.K.; Kanbogtah, D.; Apalangya, V.; Nyankson, E.; Tiburu, E.K.; Dodoo-Arhin, D.; Onwona-Agyeman, B.; Yaya, A.
In this work, oil was extracted from Citrullus vulgaris (watermelon) seeds for potential feedstock in biodiesel production. The results showed that, the oil content from Citrullus vulgaris seeds oil during extraction reached an average yield of 50%. Biodiesel was produced via transesterification using NaOH as catalyst. The effect of NaOH on the yield of the biodiesel was investigated at three different concentrations; 0.13, 0.15 and 0.18 g and oil to methanol ratio of 5:1 under different reaction times; 90, 120 and 150 min at 60 °C. The yield of biodiesel from NaOH concentration of 0.13 g was found to be 70% as compared to those of concentrations, 0.15 g and 0.18 g which were 53% and 49% respectively. Gas chromatography was used to identify the methyl ester groups present in the biodiesel and the results revealed both concentration and time-dependent increase in oil yield. The physicochemical properties of the watermelon seed oil such as flash point (141.3 ± 0.4–143.4 ± 0.2), density (0.86 ± 0.04–0.91 ± 0.01 g/cm3), kinematic viscosity (30.50 ± 0.1–31.20 ± 0.04 mm2/s) and acid value (mg KOH/g) are similar to conventional vegetable oils. This work therefore, highlights the potential utility of water melon seeds for biodiesel production. © 2018 The Authors
The effect of titanium dioxide synthesis technique and its photocatalytic degradation of organic dye pollutants
(Heliyon, 2018-07) Dodoo-Arhin, D.; Buabeng, F.P.; Mwabora, J.M.; Amaniampong, P.N.; Agbe, H.; Nyankson, E.; Obada, D.O.; Asiedu, N.Y.
Nanostructured mesoporous titanium dioxide (TiO2) particles with high specific surface area and average crystallite domain sizes within 2 nm and 30 nm have been prepared via the sol-gel and hydrothermal procedures. The characteristics of produced nanoparticles have been tested using X-Ray Diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area analysis, Scanning Electron Microscopy (SEM), Fourier Transform Infra-Red (FTIR), and Raman Spectroscopy as a function of temperature for their microstructural, porosity, morphological, structural and absorption properties. The as-synthesized TiO2 nanostructures were attempted as catalysts in Rhodamine B and Sudan III dyes' photocatalytic decomposition in a batch reactor with the assistance of Ultra Violet (UV) light. The results show that for catalysts calcined at 300 °C, ∼100 % decomposition of Sudan III dye was observed when Hydrothermal based catalyst was used whiles ∼94 % decomposition of Rhodamine B dye was observed using the sol-gel based catalysts. These synthesized TiO2 nanoparticles have promising potential applications in the light aided decomposition of a wide range of dye pollutants.
Effect of variation in frequencies on the viscoelastic properties of coir and coconut husk powder reinforced polymer composites
(Journal of King Saud University - Engineering Sciences, 2018-10) Obada, D.O.; Kuburi, L.S.; Dauda, M.; Umaru, S.; Dodoo-Arhin, D.; Balogun, M.B.; Iliyasu, I.; Iorpenda, M.J.
This study describes an investigation into the physical, mechanical and dynamic mechanical properties of coir (coconut fiber) and coconut husk particulates reinforced polymer composites which were prepared by the hot press method. The impact of coir loading on the physical and mechanical properties of the composites was examined in more detail. It was observed that the values of rigidity, flexural strength and hardness were raised up to 7.1 MN/m2, 17.0 MPa and 92.5 MN/m2, with increase in coir length. Impact energy reduced proportionately with increment in fiber length (from 0.78 J at no fiber inclusions to 0.42 J at 30 mm fiber length). With the increment of fiber length from zero to 10 mm, a reduction in density and increment in water absorption properties was observed. These properties (density and water absorption) remained with increase in fiber length for a given structure of matrix/filler. The surface morphology of composite with longest fiber length (30 mm) was investigated. Fiber pullout and little voids on composite surfaces were seen. Fundamentally, these regions can encourage the matrix impregnation onto the fiber. At the highest fiber loading and at highest frequency (10 Hz) used during the dynamic mechanical examination, the tan δ peak gets widened, underlining the enhanced fiber/matrix grip. Also, extra and noticeable peaks were seen at higher frequency conditions in the tan δ curves, because of the interlayer phenomenon.