Abstract

The purpose of this study was to evaluate a practical model in teaching double indicator titration in chemistry in the senior high schools in Ghana Research design for the study was Action research. The population was made up of chemistry teachers and students. in four senior high schools with two schools located in the Kwaebibirim District and two senior high schools located in the Denkyembuo District of the Eastern Region of Ghana. Purposive and simple random sampling techniques were used to select the respondents for the study. The sample comprised of twenty-five (25) chemistry teachers and one hundred and fifty (150) students in the four Senior High schools. The study indicated that Chemistry teachers would improve upon the academic performance of chemistry students in double indicator titration when they use the developed practical teaching model (DEPTEM) more. The main instruments used in this study were classroom observational checklists and questionnaires. Descriptive statistics (frequency, percentage, mean and standard deviation) were used to analyze the data gathered. Coding schemes were developed using Statistical Package for Social Sciences (SPSS) (version 21) to organize the data into meaningful and manageable categories. The study also revealed that the outcome of the post-test indicated that, the DEPTEM impact differently on the academic performance of SHS male and female chemistry students in the Kwaebibirim and Denkyembuo Districts of the Eastern Region. It is recommended that the government and non-governmental organizations should collaborate with the Ministry of Education to sponsor in production of more of the developed practical model (DEPTEM) for teaching chemistry lessons. This in a way would help improve the academic performance of chemistry students in the Kwaebibirim and Denkyembuo Districts of the Eastern Region and the nation at large. It is also recommended that chemistry teachers should consider teaching methods that would equally cater to both male and female chemistry students during chemistry lessons.

Abstract

The purpose of this study was to examine chemistry teachers' teaching and learning strategies in double indicator titration in Senior High Schools in Ghana. Action research design using a quantitative approach was used for the study. Purposive and simple random sampling procedures were employed to select one hundred and seventy-five (175) participants (teachers and students) for the study. The classroom observational checklist and questionnaire were the instruments used to collect data in the study. Descriptive statistics tools (frequency, percentage, mean and standard deviation) were used to analyse the quantitative data. The study revealed that Chemistry teachers in the Kwaebibirim and Denkyembuo Districts of the Eastern Region used the lecture method in teaching double indicator titration lessons instead of practical activities and this had negative effects on their academic performance. The study also indicated that the effective model that can be used to improve teaching and learning of double indicator titration is the developed practical teaching model (DEPTEM) as compared to the teachers’ method. It is recommended that in-service training should be organized for chemistry teachers who were already in the field of work to use more of the developed practical model (DEPTEM) in relation to the lecture method. It is also recommended that chemistry teachers should use teaching methods that would allow chemistry students to participate and manipulate equipment/materials using their five senses and other skills instead of teaching in abstract or allowing them to remain less active in their class.

Abstract

The plant leaves used as adsorbent in this study were Guava plant leaves (GPL) and Cashew plant leaves (CPL). The samples were collected within Gombe State. Batch adsorption method was used in determining the adsorption process. Fourier Transform Spectroscopy (FT-IR), Scan-ning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) were used for the characterization. The results show promising signs as they were in agreement with most literatures; various per-centage removals were obtained from Pb²⁺ and Cd²⁺ (GPL and CPL) at optimum conditions. The equilibrium data fitted well with both Langmuir and Freundlich isotherm models. Langmuir mod-el fitted well for Pb²⁺ (CPL) with R² value (0.9855) and Cd²⁺ for (GPL and CPL) with R²values (0.9945 and 0.9948) while Pb²⁺ (GPL) with correlation coefficient at 0.9116 best fits well with Freundlich isotherm model. Pseudo first order and second order were used in testing the kinetics study from which pseudo second order best fitted better than that of the first order kinetics. The thermodynamic study shows that ΔG is negative in most cases except for Cd²⁺ (GPL) where ΔG is positive. Whereas ΔH and ΔS are positive in some cases showing an endothermic and spontane-ous adsorption processes respectively, as well as negative in some. Based on this study, GPL and CPL could be used as a natural adsorbent to remove Pb²⁺ and Cd²⁺ heavy metals from wastewater and environment due to their high removal efficiencies.

Abstract

In this Research work, Silver Nanoparticles were green synthesized from Psidium guajava leaves<b> </b>and different Characterization techniques including UV-Visible, FT-IR, SEM and XRD were all employed to ascertain the absorption peaks, functional group, surface morphology and crystalline size of the nanoparticles respectively. These nanoparticles green synthesized were applied against four different pathogens namely, S. aureus (gram- positive bacteria), E. coli (gram- negative bacteria), C. albicans (gram- positive fungus) and Aspergillus niger and the investigation showed that the Silver nanoparticles synthesized were potent against the selected pathogens. From the UV-Vis spectral analysis, it was observed that highest absorption peaks appeared at 400nm and 500nm reflecting the surface plasmon resonance of silver Nanoparticles from guava leaves which is characteristic of Silver Nanoparticles. From the FT-IR spectrum of the sample under studied, the peaks 3416.85 cm^-1, 2923.51 cm^-1, 1618.95 cm^-1, 1384.49 cm^-1 and 1033.63 cm^-1 were observed where the absorption band at 3416.85 cm^-1corresponds to the stretching due to N-H, while the band at 2923.51 cm^-1 is associated with C-H stretch of alkane and O-H stretching. The peak at 1618.95 cm^-1 shows C=C stretching, 1384.49 cm^-1reveals the existence of C-H bending and 1033.63 cm^-1 depicted C-O stretching. The SEM analysis revealed the shape of the nanoparticles as being spherical while XRD result admits that the average size of the green synthesized Ag NPs was 45.5 nm using the Scherer’s formula. Augmentin was used as control at concentration of 300μg/L throughout antimicrobial studies. Different concentrations of 100, 200, 300, 400 and 500μg/L of Silver Nanoparticles were tested against each pathogen. It was discovered that with increase in concentrations of Silver Nanoparticles of all the pathogens, there generally appeared to be increase in inhibition zone. At higher concentration of 500μg/L, the zones of inhibition were in the following order; 22.50 mm, 17.00mm, 15.44mm, and 13.23mm for E. Coli, S. aureus, C. albicans and Aspergillus niger respectively. For each concentration investigated, E. coli, demonstrated higher zone of inhibition as opposed to all other pathogens investigated in this research.

Abstract

During the past few decades, many of the synthetic chemicals are able to produce nanoparticles and nanoclusters, although these chemicals primarily act as reducing and capping agents, they are very toxic and hazardous and make the nanoparticles biologically incompatible. Thus there is need for green chemistry that includes a clean, non-toxic and environmental friendly method of nanoparticles synthesis. Cobalt, iron and copper nanoparticles were synthesized using the stem-bark extract of khayasenegalensis (mahogany) where cobalt chloride (CoCl₂ 6H₂O), ferric chloride (FeCl₂), and copper sulphate (CuSO₄ H₂O) were used as the metal precursor respectively. The change in color from light brown to dark brown indicates the formation of cobalt nanoparticles, from light brown to dark green indicates the formation of copper nanoparticles and also the change in color from light brown to a dark color indicates formation of iron nanoparticles. The nanoparticles were further characterized using UV visible spectroscopy, FTIR, and SEM. The UV result for CoNPs showed the highest peak at 500nm and both FeNPs and CuNPs showed the highest peak at 300nm. The FTIR results for all the nanoparticles showed the presence of Alkaloids and triterpenes. Also the SEM result showed spherical granular, partially dispersed and monodispersed morphology for CoNPs, FeNPs and CuNPs respectively. Moreover, the antibacterial activity of the synthesized NPs when tested against two gram positive bacteria and two gram negative bacteria was evaluated and good results were obtained. The antifungal activity when tested against two fungi showed a very good result.

Abstract

Magnetic iron nanoparticles (Fe<SUB>3</SUB>O<SUB>4</SUB>) were synthesized and characterized using Fourier Transformed Infrared ((FT-IR), UV-Visible spectrophotometer, Scanned Electron Microscopy (SEM) equipped with an Energy Dispersive X-ray spectrometer (EDX), and X-ray Diffraction (XRD). The synthesized nano catalyst was used in the transesterification of mahogany seed oil with methanol. The optimized reaction conditions gave a reaction yield of 88% at a catalyst concentration of 1.5% wt., a volume ratio of methanol to oil of 5:1, a reaction temperature of 60 °C, and a reaction time of 120 minutes. The Fe<SUB>3</SUB>O<SUB>4</SUB> nanoparticles was regenerated from the mixture and reused for various circles by applying the optimum conditions obtained during the present study. The results showed that the biodiesel yield decreased by increasing the number of cycles when the regenerated catalyst was used. However, good conversion (81.9%) was obtained up to the 5th cycles. The elemental analysis of the synthesized magnetic iron nanoparticles Fe<SUB>3</SUB>O<SUB>4</SUB>) revealed the highest proportion of iron with 64.37 and 74.40% for atomic and weight concentration respectively, followed by oxygen with 34.27 and 24.50% for atomic and weight concentrations respectively. It could be concluded that the synthesized nano catalyst would serve as an excellent catalyst for the transesterification of vegetable oils.

Abstract

Like electricity, hydrogen is an excellent energy carrier, as it can be produced from many different and abundant precursors, such as natural gas, coal, water, and renewable energy. The use of hydrogen in fuel cells, particularly in the transport sector, will make it possible to diversify the energy supply, take advantage of domestic resources, and reduce oil imports dependence. Unlike other fuels, hydrogen (H<SUB>2</SUB>) can be generated and consumed without emitting carbon dioxide (CO<SUB>2</SUB>). This results in great ecological benefits and fundamental challenges. Hydrogen can operate in a closed and inexhaustible cycle based on the cleanest, most abundant, and elemental substances: water, oxygen, and hydrogen. If hydrogen is generated using light, heat, and electricity produced from solar, wind, or nuclear energy, hydrogen becomes a versatile and universal means of storing and transporting energy and a necessary element for future energy systems that operate without environmental pollution, CO<SUB>2</SUB>, and other gases that contribute to the greenhouse effect. Hydrogen is necessary to eliminate environmental pollution and stabilize the composition of the planet’s atmosphere and climate. This paper investigates different methods of hydrogen production in the term of their technological and economic aspects. This paper shows that thermochemical methods dominate the hydrogen market while emerging electroreduction methods are developing fast, which might turn the tide in the future.

Abstract

Essentiality of water sustain life, and a satisfactory supply must be readily available to promote health, prolong life expectancy and prevent diseases. This study assesses the sources and quality of drinking water in Piwoyi community of Federal Capital Territory, Abuja, Nigeria. Thirty-five (35) Boreholes and Two (2) Sachet water were identified sources of drinking water in Piwoyi Community. Six Samples (5 Boreholes and 1Sachet water) were selected at random and analyzed in the laboratory. The Physicochemical parameters examined include electrical conductivity (EC), pH, temperature, turbidity, dissolve oxygen (DO), chloride, total hardness, alkalinity, nitrate, calcium, magnesium, phosphate, phosphorous, sulphate, sodium, potassium, fluoride, bicarbonate, nitrate-nitrogen, nitrite, copper, iron and zinc; and Microbiological parameters include Coliforms, E-coli and Faecal Strep. The results of analysis shows significant concentration of physicochemical and microbiological parameters in the samples of water analyzed according to Nigerian Standard for Drinking Water Quality thereby makes the water unsafe for drinking. Drinking from these sources of water will pose serious health risk to the people of Piwoyi Community. Therefore, the study helps to identify the contaminated locations as well as assist to follow emerging remedial measures toward controlling the contamination source in the community. It also recommends continuous monitoring and enforcement of environmental violations, aggressive sensitization on water sanitation and hygiene; adequate purification of water at domestic level; and government support on potable water supply and establish reasonable management strategies for sustainable water quality protection toward protecting public health.

Abstract

Three novel coordination polymers {[Cu<SUB>2</SUB>(bitbu-OMe)<SUB>4</SUB>(SO<SUB>4</SUB>)<SUB>2</SUB>]·6MeOH}<SUB>n</SUB> (<b>1</b>), {[Co<SUB>2</SUB>(bitbu-OMe)<SUB>4</SUB>(NCS)<SUB>4</SUB>]<SUB>0.5</SUB>·2DMF}<SUB>n</SUB> (<b>2</b>), {[Co(bitbu-OMe)<SUB>2</SUB>(NCS)<SUB>2</SUB>]·2MeOH}<SUB>n</SUB> (<b>3</b>) (bitbu-OMe = 1,1’-[(5-tert-butyl-2-methoxybenzene-1,3-diyl)dimethanediyl]bis(<i>1H</i>-imidazole)) are synthesized through a slow evaporation method using solvothermal technique of CuSO<SUB>4</SUB>·5H<SUB>2</SUB>O or Co(SCN)<SUB>2 </SUB>with bitbu-OMe. X-ray diffraction analysis results reveal that <b>1</b>, <b>2</b>, and <b>3</b> have similar two-dimensional layer networks. The study of the effect of the methoxy group in bitbu-OMe towards the stability of ligand conformation in obtained coordination polymers becomes necessary to be conducted in the future to unveil the reason for conformation similarity of ligand in coordination polymers.

Abstract

We reported here the microwave assisted synthesis of 3,5-disubstituted 1,2,4-triazole based piperazine amide and urea derivatives with very good yield under mild reaction conditions.

Abstract

The present work describes the geometry and electronic structures of liquid crystals of azoxybenzene group and their reactivity with respect to molecular properties: total energy, ionization potential, electron affinity, HOMO energy, LUMO energy, electronegativity, hardness and dipole moment. Literature shows that mesomorphism depends particularly on the nature of terminal groups and their linkages with parent molecule. And thus, substitution of terminal groups can help to fine tune the liquid crystal behavior and also their applications. In this work the effect of four terminal groups of same and diverse nature has been studied. For the study, the molecular modeling and geometry optimization of the compounds have been performed on workspace program of CAChe Pro 5.04 software of Fujitsu using DFT method.

Abstract

Polychlorinated biphenyls (PCBs) are important class of persist organic pollutants that were used as a component of paints especially in printings, as plastificator of plastics and insulating materials in transformers and capacitors, heat transfer fluids, additives in hydraulic fluids in vacuum and turbine pumps. There is always a need to establish reliable procedures for predicting the bioconcentration potential of chemicals from the knowledge of their molecular structure, or from readily measurable properties of the substance. Hence, correlation and prediction of biococentration factors (BCFs) based on λ<SUB>max</SUB> and vibration frequencies of various bonds viz υ(C-H) and υ(C=C) of biphenyl and its fifty-seven derivatives have been made. For the study, the molecular modeling and geometry optimization of the PCBs have been performed on workspace program of CAChe Pro 5.04 software of Fujitsu using DFT method. UV-visible spectra for each compound were created by electron transition between molecular orbitals as electromagnetic radiation in the visible and ultraviolet (UV-visible) region is absorbed by the molecule. The energies of excited electronic states were computed quantum mechanically. IR spectra of transitions for each compound were created by coordinated motions of the atoms as electromagnetic radiation in the infrared region is absorbed by the molecule. The force necessary to distort the molecule was computed quantum mechanically from its equilibrium geometry and thus frequency of vibrational transitions was predicted. Project Leader Program associated with CAChe has been used for multiple linear regression (MLR) analysis using above spectroscopic data as independent variables and BCFs of PCBs as dependent variables. The reliability of correlation and predicting ability of the MLR equations (models) are judged by R<SUP>2</SUP>, R<SUP>2</SUP><SUB>adj</SUB>, se, q<SUP>2</SUP><SUB>L10O</SUB> and F values. This study reflected clearly that UV and IR spectroscopic data can be used to predict BCFs of a large number of related compounds within limited time without any difficulty.