Browsing by Author "Mwakalesi, Alinanuswe J."

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Anthropogenic activities along the lake nyasa catchments alter the habitat and genetic diversity of a lake salmon, opsaridium microlepis
(Heliyon, 2024) Nehemia, Alex; Mwakalesi, Alinanuswe J.
The Lake Salmon, Opsaridium microlepis is an economically important fish along the Lake Nyasa. However, the species is under threat of extinction due to anthropogenic activities such as agri culture, mining, urbanization, and deforestation. Consequently, the fish species is currently regarded as a threatened species, and the International Union for Conservation of Nature (IUCN) has red-listed the species due to an apparent decline in abundance. The current study assesses the potential impact of human activities on the genetic diversity of O. microlepis using partial mito chondrial cytochrome oxidase subunit I (COI) sequences and microsatellite loci. The results indicate that genetic diversity is lower in the areas affected by human activities compared to relatively pristine areas. The results from this study may suggest that human activities taking place in the catchments are likely to contribute to the alteration of the genetic diversity of O. microlepis species. Thus, immediate measure is required to control anthropogenic activities in the areas to protect the species and other aquatic organisms from possible threats of extinction.
Corrosion inhibition of Amino Pentadecylphenols (APPs) derived from Cashew Nut shell liquid on mild steel in Acidic medium
(Scientific Research Publishing Inc.) Philip, Joseph Yoeza Naimani; Buchweshaija, Joseph; Mwakalesi, Alinanuswe J.
Corrosion inhibition of mild steel in sulphuric acid solution with tetradenia riparia leaves aqueous extract: kinetics and thermodynamics
(ResearchGate) Mwakalesi, Alinanuswe J.
Corrosion inhibition of mild steel in sulphuric acid solution with tetradenia riparia leaves aqueous extract: kinetics and thermodynamics
(ResearchGate, 2022-01-23) Mwakalesi, Alinanuswe J.
One of the most successful ways for maximizing profit and lowering costs is to use mild steel over other corrosion-resistant alloys. As a result, mild steel is the most commonly used metallic material in many industries, and its corrosion resistance has received a lot of attention. The mild steel corrosion inhibition using compounds derived from plants is the most practicable and preferable technique because of their linked low cost and green chemistry credentials. This study reports on the kinetics and thermodynamics of mild steel corrosion inhibition in sulphuric acid media utilizing Tetradenia riparia leaves aqueous extract as a potential green inhibitor. The investigations were carried out using the gasometric technique. The findings indicated that the corrosion inhibition efficiency (IE) increased with increasing inhibitor concentration with an optimal value of 90.6% at 500-ppm. The increase in temperature 298 to 338 K lowered the corrosion inhibition efficiency by only 4%. The adsorption kinetics of the extract on the mild steel fit into Langmuir, Temkin, EL-awady, and Freundlich models, but the Langmuir was the best. The results of this investigation show that adsorption of the extracted chemicals on mild steel in a sulphuric acid solution is feasible and most likely involves a combination of physical and chemical adsorption.
Effective corrosion inhibition of mild steel in an acidic environment using an aqueous extract of Macadamia Nut Green Peel biowaste
(MDPI, 2022-12) Mwakalesi, Alinanuswe J.; Nyangi, Magori
Improving the corrosion resistance of mild steel in an acidic aqueous environment is an important industrial consideration due to the use of acids for descaling and cleaning. The application of corrosion inhibitors is one of the most effective and economical means of protecting metals against corrosion. Plant-derived compounds have recently gained attention due to their low cost, non-toxic, and environmentally friendly properties. Biowastes are recognized as a potential cheap source of green corrosion inhibitors, and their use can help to lower the costs associated with corrosion inhibitors. Green peel biowaste (GPBW) generated from macadamia nut processing is typically dumped into the environment, posing a disposal concern. The use of the waste as a potential source of organic compounds with green chemistry attributes for mild steel corrosion inhibition in an acidic solution was proposed in this study. The gasometric and optical methods were used to carry out the investigations. Results showed that mild steel corrosion rates decreased as extract concentrations increased. As a result, mild steel corrosion inhibition increased with increasing inhibitor concentration and reached a peak value of 81% at 0.5 g/L extract concentration. The optical images showed that the inhibitor molecules adsorbed on the metal surface to form a protective film that isolated the mild steel from the corrosive solution. The adsorption of inhibitor molecules on the mild steel surface followed the Langmuir adsorption isotherm, indicating the formation of a monolayer film with a homogeneous distribution of adsorbed molecules. A Gibbs free energy (G◦ ads) of 24 kJ/mol indicated the inhibition process was mainly characterized by physical adsorption. The results of this study suggest that aqueous GPBW extract could serve as an inexpensive, non-toxic, and renewable corrosion inhibitor of mild steel in acidic solutions.
Green synthesis of silver nanoparticles using aqueous extract of vachellia xanthophloea and their potential use for antibacterial and sensing of mercury ions
(Springer, 2023-07-06) Mwakalesi, Alinanuswe J.
The use of silver nanoparticles (Ag-NPs) in different fields such as agriculture, medicine, and environment has recently increased. As a result, studies on their synthesis and applications have gained attention. In the present study, the synthesis of Ag-NPs using cheap, renewable, and environmentally friendly phytochemicals extracted from Vachellia xanthophloea leaves is reported. Additionally, potential uses of the nanoparticles against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria and for sensing of mercury ions from aqueous solutions were investigated. The findings showed that the formation of nanoparticles was associated with a color change from green to brown with a UV–Vis maximal absorbance peak at 420 nm due to surface plasmon resonance on Ag-NPs. The synthesized Ag-NPs showed effec- tive antibacterial effects against both gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria. The antibacterial effectiveness as indicated by the minimum inhibitory concentration (MIC) was higher for Staphylococcus aureus (0.04 mg/mL) compared to E. coli (0.33 mg/mL). Similarly, the minimum bactericidal concentration (MBC) values were 0.04 and 0.66 mg/mL for S. aureus and E. coli, respectively. The nanoparticles were also sensitive to metal ions ( Hg2+, Ba2+, Mg2+, Zn2+, Cu2+, Ni2+, Co2+, and Fe2+) and showed a remarkable selectivity to mercury. The potential use of the nanoparticles for sensing of mercury ions from real water samples of ground and tap waters produced satisfactory results. The limit of detection (LOD) and limit of quantification (LQD) for sensing of Hg2+ were determined to be 22.2 µM and 73.9 µM, respectively. The findings from the current study indicate that Ag-NPs prepared using Vachellia xanthophloea leaves aqueous extract could serve as effective an antibacterial agent and a sensor of mercury ions for aqueous samples.
Population Genetic Structure and Demographic History of Opsaridium microcephulum along Lake Nyasa
(University of Dar es Salaam, 2023) Nehemia, Alex; Mwakalesi, Alinanuswe J.
The Sanjika, Opsaridium microcephalum is among the fish species that serve as a major source of proteins and income to people along Lake Nyasa. However, the information on its genetic diversity and structure particularly in the Tanzania part of the Lake is limited. Therefore, the assessment of the genetic diversity and structure of O.microcephalum along the Lake Nyasa part of Tanzania was conducted in the current study using a fragment of the mitochondrial COI gene from 92 individuals of O. microcephalum. The findings showed that an average haplotype diversity and average nucleotide diversity were 0.8065 ± 0.0314 and 0.002380 ± 0.001640, respectively. The molecular Variance (AMOVA) indicated significant genetic variations among the subpopulations studied (Overall Φst = 0.31560, p < 0.001). The lowest haplotype diversity was recorded at Manda and the highest haplotype diversity was recorded at Buloma. The lowest nucleotide diversity was recorded at Manda and the highest was recorded at Lupingu. The differences in genetic diversity can be a possible indicator of different localised evolutionary forces that require attention to conservationists for the sustainable management of O. microcephalum.
Removal of picloram herbicide from an aqueous environment using polymer inclusion membranes
(Elsevier Ltd) Mwakalesi, Alinanuswe J.; Potter, Ian D.
Targeting of cationic organic pesticide residues using polymer inclusion membranes containing anacardic acid from cashew nut shell liquid as a green carrier
(Elsevier Ltd) Mwakalesi, Alinanuswe J.; Potter, Ian D.
Targeting of cationic organic pesticide residues using polymer inclusion membranes containing anacardic acid from cashew nut shell liquid as a green carrier
(Elsevier Ltd, 2021-07-21) Mwakalesi, Alinanuswe J.; Potter, Ian D.
Many emerging organic pollutants exist as cationic residues at environmentally relevant pH. This indicates a need to develop economically viable and robust methods to remove such residues from environmental waters. In this paper, we report using polymer inclusion membranes (PIMs) containing anacardic acid (AA), sourced from cashew nut shells, as an acidic carrier for the extraction and transport of 4-amino-2-chloropyridine (ACP), paraquat and diquat as representative target solutes of organic pesticide residues in aqueous solutions. Amounts of cellulose triacetate (CTA) as polymer, 2–nitrophenyl octyl ether (NPOE) as plasticiser, AA as carrier, and 1- dodecanol as modifier were used to prepare membranes. An optimal composition of 30 wt% CTA, 40 wt% NPOE, 10 wt% AA and 20 wt% dodecanol produced an initial flux of 364 (± 16) × 10 − 8 mol m − 2 s − 1 for transport of ACP. The extraction performance of AA was comparable to bis-(2-ethylhexyl) phosphoric acid, a widely used acidic carrier, in PIMs of similar composition. PIMs utilizing AA were also successfully applied to a sample of environmental water for the competitive recovery of ACP, paraquat and diquat, each at 500 μ g/L. Using chemicals from plants as active reagents was shown to be an effective strategy to enhance the green chemistry credentials associated with methods for water remediation.