Applied Chemistry

The valorization of minerals requires physicochemical and thermal treatments, using various materials such as crucibles. They are refractory ceramics mainly based on clays. Crucibles must be resistant to chemical aggression by molten slag and metals at high temperature during repeated thermal cycles, to ensure the durability in use. Fire-assaying is extensively used in gold mining in Burkina Faso, needing a huge quantity of ceramic crucibles imported per year. In this study, we have characterized different clays to manufacture refractory ceramics for crucibles. Physical characteristics of laboratory made crucibles were compared to that of industrial crucibles. The behavior of an optimized composition with 25wt% of clay and 75wt% of chamotte (fired clay) was experimented to optimize the properties in use. Particularly, the adequate adjustment of all process parameters, as the paste plasticity, leads the control of the density and porosity of the fired ceramic. Fusion tests with copper and aluminum at temperature between 600°C and 1100°C proved the small penetration depth of the molten metal into the ceramic that reduce the corrosion phenomenon. Our work evidences the existence of both a scientific and a technological knowledge in the use of silico-aluminate mineral resources from Burkina Faso, for manufacturing refractory crucibles for the melting of both slag and precious metals.

Deinking is an important step in recycling of waste paper and flotation is commonly used in this process. Conventional laboratory-scale flotation cell was used to study ink removal from waste printed papers. Different type of surfactants such as, cationic, anionic or non-ionic, were employed in pulping and flotation processes. Two surfactants of each type were used in this comparative study. The effect of concentration and type of surfactant, consistency, pH and temperature on the deinking was investigated. The efficiency of deinking process was determined by measuring of the brightness of hand sheets formed of deinked fibers. The highest brightness was achieved by using 2-octanol alcohol (as a non-ionic surfactant) in pulping and flotation stages. Under optimum conditions for this surfactant, a brightness of 86% is obtained from a feed of 44%.

The present work is an attempt to identify key structural features that govern the anti-malarial activity of Pyrido[1,2-a]benzimidazoles using pharmacophoric analysis. The work is based on a dataset of fifty-six molecules comprising diverse derivatives of Pyrido[1,2-a]benzimidazole. The structures were drawn, optimized and aligned using standard protocol. The final model was developed using aligned molecules. The analysis reveals that the anti-malarial activity of Pyrido[1,2-a]benzimidazoles is related with features. The analysis points out that in future modifications these features should be retained.

A simple, highly sensitive, accurate and selective method for determination of trace amounts of Pb(II) in water samples is presented. a novel ethylenediamine-functionalized multi-walled carbon nanotubes(E-MWCNTs) solid-phase extraction adsorbent was synthesized by covalently O-(7-azabenzotriazol-1-yl)-N,N,N´,N´-tetramethyluronium hexafluorophosphate onto the surfaces of multi-walled carbon nanotubes (MWCNTs). The stability of a chemically ethylenediamine-functionalized multi-walled carbon nanotubes(E-MWCNTs) especially in concentrated hydrochloric acid was studied which used as a recycling and pre-concentration reagent for further uses of (E-MWCNTs). The method is based on (E-MWCNTs) of Pb(II) on surfactant coated C18, modified with a ethylenediamine-functionalized multi-walled carbon nanotubes(E- MWCNTs). The retained ions were then eluted with 4 ml of 4 M nitric acid and determined by flame atomic absorption spectrometry (FAAS) at 283.3 nm for Pb. The influence of flow rates of sample and eluent solutions, pH, breakthrough volume, effect of foreign ions on chelation and recovery were investigated. 1.5 g of surfactant coated C18 adsorbs 40 mg of the Schiff’s base which in turn can retain 15.2±0.8mg of each of the two ions. The limit of detection(3?) for Pb(II) was found to be 3.20 ng l -1. The enrichment factor for both ions is 100. The mentioned method was successfully applied on determination of lead in different water samples. The ions were also speciated by means of three columns system.

The voltammetry methods have revealed in the water of the Cotonou channel, the presence of organic and inorganic complexes of metals, such as: Zn-Carbonate, Zn2+, ZnSO4, Zn-OM, Cu-Carbonate, Cu2+, Cu(OH)2, Cu-OM, Pb-Carbonate, Pb2 +, Pb-OM, Cd-Carbonate, Cd2+, and Cd-OM. Their concentrations were variable with the water pH and depended on the season. At pH values ranging 6.5 - 7.2, metals were complexed by carbonate ions present in the water. Zinc is predominantly present as Zn2+ in the rainy season and Cu2+ levels were decreasing when pH was increasing. 80% of the total lead appeared to be complexed as Organic matter complex lead (Pb-OM), and cadmium (Cd-OM) which, unlike other metals, was mainly present in free Cd2+ form.

This present work aims to investigate dyeing performance of some new azo disperse dyes belonging to diazotization of 1, 4-bis (2-amino-1, 3, 4-thiadiazolyl) benzene and coupling with different amines as to comparing and contrasting depth obtained of shade and levelness. Some new dyes, such, has been examined, and assessed. The study was concerned mainly with dye uptake, behavior and efficiency. Color measurements, kinetics and thermodynamic parameters were involved. Conventional dyeing, was considered as control for obtained results.

Chemical analysis of the leaf of Bryophyllym pinnanun was carried out. The moisture content and the ash content were found to be 83.91% ± 0.21 and 13.30% ± 0.41. The leave of the plant was found to contain Na, Ca, K, Mn, Mg, Fe, Cu, Cr and Zn. The level of these mineral in mg/ l00g sample were found to be 0.13% ±0.3, 599.97%, ± 24.54; 5.51% ± 0.08; 4.71% ±0.27; 247.11% ± 33.11; 6.62% ± 1.72; 82.96% ± 6.96: 60.%% ± 8.01 and 0.10% ± 0.01 respectively. The elemental analysis using sodium fusion test shows that the leave contain nitrogen, chlorine, and bromine. The present of these mineral elements in the plant could be part of the contributing factors which suggest the use of the plant for various therapeutic applications.

Heavy organic deposition in the production and processing of crude oil has been a problem in the oil and gas sector. Although, some efforts have been made to minimise it such as changes in composition, pressure and/or temperature; this study attempts to address the Nigerian situation. The article investigated the onset of heavy organic precipitation by transmitting microscopy study of the precipitant volumes reported for single nC5; nC6; nC7 and nC8 alkane precipitants as 5.02ml, 5.05ml, 6.00ml and 7.10ml respectively to start precipitation in 1:1 (v/v) precipitant: toluene solution to 2±0.5g crude oil. Their varied binary mixtures nC5:nC6; nC5: nC7; nC5: nC8; nC6: nC7; nC7: nC8 showed onset of HO precipitation with ratios of 7:3, 1:1, 4:1, 3:2 and 9:1 respectively with no onset volume detected for nC6: nC8 within the ratio range being investigated. Hence, the outcome of these results of the precipitant volumes at onset of HO precipitation for single n-alkanes and volume ratios of binary mixture n-alkane solvents should not be altered or exceeded during injection of fluids for enhanced oil recovery or as diluents into Afiesere heavy crude oil to improve flow properties.

Rice bran, one of the most abundant and valuable byproducts produced during the rice milling process, is of steadily growing interest in recent years due to its potential health benefits. Herein, we investigate and report the physicochemical properties of rice bran obtained from Mubi, Adamawa State, Nigeria. The rice bran was initially combusted and soil samples of the baked, unbaked soil and surrounding particular area where we carried out the combustion were collected and analyzed for its physicochemical properties. The results revealed that the baked soil has a higher concentration of calcium, magnesium, potassium and sodium than the unbaked soil. Furthermore, retention of water (tension) and the ability to absorb water (infiltration) was discovered to be higher in the baked soil sample. This shows that the heat of combustion of rice bran affects the physical, chemical and mechanical properties of soil in a peculiar way.

The employability skills are regarded as valuable in employment success. The application of employability skills in the present and future workplaces also facilitates employees’ job performance. Explanatory correlational research design was used in the study which was aimed at determining the relationship between the practice of employability skills and contextual performance of employees. Drawn from The Conference Board of Canada’s Employability Skills 2000+ and Borman and Motowidlo’s Taxonomy of Contextual Performance, two sets of survey questionnaires were adopted to collect data from 220 sampled respondents representing employers and employees of 25 government institutions in Central Mindanao region of the Philippines. Results showed that government employees practiced fundamental, personal management and teamwork skills to some extent. Also, these employees demonstrated satisfactory contextual performance as perceived by the two groups of respondents. Moreover, inferential analysis revealed that practice of employability skills had significant moderate positive relationship to contextual performance. The use of employability skills, therefore, needs to be sustained to pave way to improved extra-role behaviors that help meet the requirements and demands of public institutions