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Thermochemistry of Co(II) Porphyrin-Catalysed Oxidation of Methanol to Formaldehyde
Issue:
Volume 10, Issue 6, December 2022
Pages:
186-201
Received:
29 October 2022
Accepted:
14 November 2022
Published:
22 November 2022
DOI:
10.11648/j.sjc.20221006.11
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Abstract: In recent years, much attention has been focused on cobalt catalysis because of its abundance on Earth, low toxicity, and low cost. A lot of work has been focused on catalysis with cobalt porphyrin. A very interesting chemical reaction catalysed by cobalt(II) porphyrin is the Oxidation of methanol to formaldehyde. The formaldehyde formed in this reaction can be used in the synthesis of 1,5-diketones. Herein in this work, A density functional theory calculations at the APFD/SDD level were performed to study the optimised geometry of the intermediate cobalt porphyrin complexes formed in this oxidation reaction, and the thermochemistry parameters for the relevant steps were calculated. The reactions between cobalt(II) porphyrin and methanol, methoxide, and methoxy radical yield complexes Copor(CH3OH), [Copor(CH3O)]-, Copor(CH3O), respectively; all of these are exothermic reactions. These complexes produce formaldehyde and complexes in which one hydrogen attaches cobalt porphyrin either to nitrogen or to cobalt to form natural or anion complexes, such as [Copor(NH)]-, [Copor(H)]-, Copor(NH), Copor(H). Of these complexes, the formation of Copor(H) (one hydrogen atom forms a bond with a cobalt atom) is the least endothermic. Complexes where hydrogen atoms form bonds with cobalt atoms are more stable than complexes where hydrogen atoms form bonds with nitrogen porphyrin. Hydrogen molecules may be produced from the reaction between Copor(NH) and Copor(H). Finally, Copor(H) can be used as a catalyst in the oxidation reaction of methanol to formaldehyde.
Abstract: In recent years, much attention has been focused on cobalt catalysis because of its abundance on Earth, low toxicity, and low cost. A lot of work has been focused on catalysis with cobalt porphyrin. A very interesting chemical reaction catalysed by cobalt(II) porphyrin is the Oxidation of methanol to formaldehyde. The formaldehyde formed in this re...
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Analysis of Local Samples of Paracetamol at Bamako by Reflectance Near-Infrared Spectroscopy
Aminata Sow,
Issiaka Traore,
Tidiane Diallo,
Abdramane Ba
Issue:
Volume 10, Issue 6, December 2022
Pages:
202-210
Received:
26 October 2022
Accepted:
11 November 2022
Published:
30 November 2022
DOI:
10.11648/j.sjc.20221006.12
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Abstract: The approach of Near-Infrared Spectroscopy (NIRS) together with Chemometric techniques are used in order to analyze sixty (60) tablets of paracetamol of different batch numbers in the local markets in Bamako. The primary objective is to model these samples by doing multivariate regression computation. Prior to this, various statistical pretreatment methods such as second derivative (SD) correction, first derivative correction (FD), multiple scattering correction (MSC), smoothing the spectra (smooth), the standard variate normalization (SNV) correction and some combinations are performed. The Partial least square (PLS) regression on the SNV data preprocessing resulted in the detection of two outliers. Additionally, the presence of nonlinear effects is conducted. Its presence compels one to consider nonlinear regression such as the artificial neural network ANN or relevance vector machine RVM. A supporting fact of the use of these types of regressions is that ANN regression applied to the spectra under consideration significantly improves the RMSEP and the relative standard error of prediction RSEP. To further analyze the samples, the selection of wavelengths based on the p-value approach proved its usefulness in this investigation. The best calibration of the PLS multivariate regression model is obtained with the MSC combined with FD correction, and its statistical values for the fourteen wavelengths, having the smallest individual p-value, are R2= 85.26%, RMSEP= 2.38×10-4 and finally RSEP=1.45%.
Abstract: The approach of Near-Infrared Spectroscopy (NIRS) together with Chemometric techniques are used in order to analyze sixty (60) tablets of paracetamol of different batch numbers in the local markets in Bamako. The primary objective is to model these samples by doing multivariate regression computation. Prior to this, various statistical pretreatment...
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Calibration and ISO GUM Based Uncertainty of Conductivity and TDS Meters for Better Water Quality Monitoring
Adel Bassuoni Shehata,
Abdulrahman Rashed AlAskar,
Rashed Abdallah Al Dosari,
Fahd Refaei Al Mutairi
Issue:
Volume 10, Issue 6, December 2022
Pages:
211-218
Received:
9 November 2022
Accepted:
24 November 2022
Published:
30 November 2022
DOI:
10.11648/j.sjc.20221006.13
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Abstract: Water quality monitoring is of fundamental importance for health and environmental protection. Conductivity and the total dissolved substance (TDS) are two important water quality parameters. Their monitoring requires good calibration of the measuring equipment and correct assessment of the measurement uncertainty so that the water quality limits can be well judged. Though many published research articles include conductivity and TDS measurement results, there is no published ISO GUM approach for estimation of the uncertainty in the calibration measurement results. In this work, the linearity of a conductivity meter was established using three certified reference materials (CRMs) of 100, 500 and 1410.7μS/cm and then a one-point calibration using CRM of 1410.7μS/cm was carried out. The calibration method was validated by studying its accuracy, precision and bias. The method was found fit-for-the purpose and the uncertainty sources of calibration were identified and estimated based on ISO GUM. Then a standard solution of concentration 0.01M was prepared from high purity KCl to provide conductivity of 1411μS/cm. The corresponding TDS value of this solution was found 745 mg/L and its traceability to the SI units was achieved by weighing the mass of KCl using a calibrated balance and by measuring the volume of water using a calibrated measuring flak. This solution was used to perform a one-point calibration of a TDS meter then the meter was allowed to read the TDS 10 times and the uncertainty of the measurement results was estimated based on ISO GUM. The results obtained proved a very good calibration of both meters. An overall approach for estimation of the calibration uncertainty was developed, which will be very useful in water quality monitoring measurements.
Abstract: Water quality monitoring is of fundamental importance for health and environmental protection. Conductivity and the total dissolved substance (TDS) are two important water quality parameters. Their monitoring requires good calibration of the measuring equipment and correct assessment of the measurement uncertainty so that the water quality limits c...
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Preliminary Study of Short-Lived Climate Pollutants (SLCPs) Emissions from Waste Management in the Commune of Lomé Golfe 3 in Togo
Lassissi Baba Tounde Balogun,
Kokou Sabi,
Kokou Alexis Mawuko Awutey,
Hezouwe Sonla
Issue:
Volume 10, Issue 6, December 2022
Pages:
219-224
Received:
15 November 2022
Accepted:
5 December 2022
Published:
15 December 2022
DOI:
10.11648/j.sjc.20221006.14
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Abstract: Short-lived climate pollutants (SLCPs) are air pollutants and Greenhouse Gas (GHG) responsible for air pollution and climate change. They have a costly impact on health and the environment. Waste management activities are one of the sources of emissions of these pollutants. This Master's thesis falls within this theme. The categorization of sources of SLCPs in the municipality of Lomé Golfe 3 is carried out in accordance with the methodology based on the 2006 IPCC guidelines. This study shows that the main SLCPs emitted by the waste sector are methane (CH4) and black carbon (BC). These pollutants in the municipality come from three subcategories, the most important of which is ''the incineration and open burning of waste'' with an emission of 12.792 Gg CO2-eq in 2019 to 13.848 Gg CO2-eq in 2021. Then comes ''the treatment and discharge of wastewater'' with an emission of 4.76 Gg CO2-eq in 2019 to 5.88 Gg CO2-eq in 2021; and finally, the sub-category ''Solid waste disposal'' with an emission of 3.136 Gg CO2-eq in 2019 to 6.664 Gg CO2-eq in 2021. From these results we deduce that the emissions of SLCPs increase during years and it depends on the population growth and the amount of waste it generates per year. To finish, the solution approaches such as: the prohibition of burning waste, the capture of landfill gas, the diversion of waste via composting, are suggested in order to reduce the emissions of these pollutants.
Abstract: Short-lived climate pollutants (SLCPs) are air pollutants and Greenhouse Gas (GHG) responsible for air pollution and climate change. They have a costly impact on health and the environment. Waste management activities are one of the sources of emissions of these pollutants. This Master's thesis falls within this theme. The categorization of sources...
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Treatment of Faecal Sludge by Two Biochemical Processes
Ogouvide Akpaki,
Nitale M’Balikine Krou,
Sassou Megnassan
Issue:
Volume 10, Issue 6, December 2022
Pages:
225-231
Received:
17 September 2022
Accepted:
10 October 2022
Published:
23 December 2022
DOI:
10.11648/j.sjc.20221006.15
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Abstract: Untreated raw faecal sludge is generally reused as fertilizer by some farmers and market gardeners to improve their production areas. However, untreated sludge contains pathogenic germs which, via the faecal-oral route, can present a microbial risk for consumers of fertilized products. To reduce this risk, the objective of this work was to evaluate the effectiveness of their hygienization by two chemical processes: the use of urea (H2CONH2) and ammonium sulphate ((NH4)2SO4). The results obtained showed that the addition of 2% (w/w) of urea in the sludge increased the pH around 9 and was sufficient to increase the inactivation of the pathogenic germs sought (Thermotolerant coliforms, Escherichia coli, Fecal streptococci, Sulphite-reducer anaerobes). The ammonium sulphate amendment had no appreciable effect on the reduction of the concentrations of these microbiological germs. However, treatment with these two additives reduced the levels of metallic trace elements (Zn, Cu, Ni, Pb, Cd and Cr) in the treated sludge. Then, the settling test made it possible to optimize the drying time of the sludge treated with sludge index values less than 100 mLg-1. Urea treatment is therefore a simple and reliable approach to obtain hygienic and agronomically ready sludge. Subsequent work will concern agronomic trials of treated sludge.
Abstract: Untreated raw faecal sludge is generally reused as fertilizer by some farmers and market gardeners to improve their production areas. However, untreated sludge contains pathogenic germs which, via the faecal-oral route, can present a microbial risk for consumers of fertilized products. To reduce this risk, the objective of this work was to evaluate...
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