Browsing by Author "Ncube, S."

Now showing 1 - 5 of 5
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    Analysis of the properties of a glass/sisal/polyester composite
    (Springer Nature, 2021-01-11) Baloyi, R.B.; Ncube, S.; Moyo, M.; Nkiwane, L.; Dzingai, P.
    Composites are gradually becoming an integral material for structural and manufacturing processes. Sisal fibre has the potential to be one of the leading reinforcement natural fibres, not only in Zimbabwe, but the world over for use in glass composites. This is mainly due to it being inexpensive, exhibiting a low density, high specifc strength, a high stiffness to weight ratio, non-toxicity, its abundance in Zimbabwe and its renewability. With an aim of coming up with a composite for partition board applications in the construction industry, five samples of sisal-glass composite were prepared with varying sisal fibre content and diferent layering techniques. Sisal fbres were pre-treated with 20% NaOH to enhance their crosslinking with the resin and reduce the chemical impurities such as lignin and waxes. Mechanical (fexural test, hardness, and tensile strength) and physical tests (density and water absorption) were conducted to analyse the properties of the composite. The results showed that treated sisal fibres had a higher breaking tenacity of 33.11 g/tex which is higher than untreated fibres with a breaking tenacity of 25.72 g/tex. The best properties were obtained in the sample with 4 layers of glass and 9 layers of sisal fibres using 200 ml of resin. The composite had a tensile strength of 57.60 MPa, fexural strength of 36 N/mm2, moisture absorption of 10% and a burning rate of 9.82 mm/ min. These results were then compared with those of the current partition boards in the market. It was noted that the composite was suitable for use in partition boards. Again, regarding cost, these composites are cheaper to produce at a rate of $11.33/m2 compared to the timber costing at $16/m2.
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    Application of amine-modified tannins gels as coagulants in wastewater treatment
    (Research Square, 2024-08-28) Thelmmer, M.; Ncube, S.; Moyo, L.B.; Mamvura, T.A.; Danha, G.; Simate, G.S.; Tshuma, N.
    Tannin (T) is an organic substance that may potentially be used as an inexpensive, environmentally friendly, and effective bio-coagulant to remove impurities from residential and commercial wastewater. In this study, bio-coagulants were prepared using tannins obtained from the wattle tree (Acacia mearnsii). The bio-coagulants were modified using formalin and optionally, ethanolamine (ETA) and ammonium chloride (NH 4 Cl) as amine sources through the Mannich Reaction scheme. Three coagulants were prepared, T-ETA modified tannin, T-NH 4 Cl modified tannin and a mixture of T-ETA: T-NH 4 Cl in molar ratio 1: 1. Aluminium sulphate [Al 2 (SO 4) 3], a metal-coagulant was also used as the standard for comparison. The three coagulants were tested at varied concentrations (500–1250 mg/L) using jar tests on laundry wastewater to see their effect on remediation of wastewater. A mixture of bio-coagulant T-NH 4 Cl and T-ETA was most effective with highest removal efficiencies for turbidity (94%), COD (85%), Total solids (87%) and nitrates (99%). For colour removal T-NH 4 Cl modified tannin showed the highest removal efficiency of 92%. The results support the use of cheaper and environmentally friendly amine modified tannin-based flocculants in laundry wastewater treatment as they showed less toxicity on the treated water.
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    Exploring digital competences in Zimbabwean secondary schools using a multimodal view: a hermeneutical phenomenography study
    (Cogent Education, 2024-07-30) Dabengwa, I.M.; Moyo, S.; Ncube, S.; Gashirai, T.B.; Makaza, D; Makoni, P.; Pasipamire, N.; Chademana, G.K.; Mafoti, M.; Mapfumo, S.; Mandaza, D.
    This paper presents a study that investigates digital competencies within the Zimbabwean secondary education system. Limited research has focused on Zimbabwe’s secondary schoolteachers’ digital literacy in online learning. The study utilised DigComp 2.2 as the framework, and employed a multi-method participative approach to collect data from secondary schools across the 10 provinces of the country. Thirty nine interviews were conducted across Zimbabwe’s 10 provinces, including 15 FGDs with learners, 21 in-depth interviews with teachers, and three key informant interviews with education directors, resulting in 215 participants. The results of a 3-dimensional modal analysis revealed a multifaceted situation in five key areas: problem-solving, safety and security, digital content creation, communication and collaboration, and information and data literacy. The study found that both teachers and learners were proficient in using applications such as WhatsApp, MS Word, Excel, and PowerPoint. Computer Science students demonstrated specialised skills, particularly in programming. Although teachers aim to improve digital literacy by teaching critical evaluations of online content, challenges persist in rural regions because of limited access to ICT tools and infrastructure. Collaboration is facilitated through platforms such as WhatsApp; however, ensuring inclusive participation remains a challenge. Digital safety and security have been identified as the major concerns. While progress has been made in areas such as Communication and Collaboration and Information Literacy, challenges still exist in digital content creation, problem-solving, and safety and security. These findings offer policymakers insights into maximising the impact of integrating ICTs in education.
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    Optimisation of using a blend of plant based natural and synthetic coagulants for water treatment: ( Moringa Oleifera-Cactus Opuntia-Alum Blend)
    (2020) Gandiwa, B.I.; Moyo, L.B.; Ncube, S.; Mamvura, T.A.; Hlabangana, N.
    The research presents a comparative study on the effectiveness of blending plant based natural coagulants (Cactus Opuntia and Moringa Oleifera extracts) and a synthetic coagulant (aluminium sulphate or alum) in treatment of raw water. The low production rates of natural coagulants has derailed their commercialization this has driven the idea of blending synthetic coagulants which is envisaged to be the more appropriate means of application in this study. To measure the effectiveness of the coagulant, the following parameters were measured; turbidity, pH, conductivity and total alkalinity. The simplex lattice experimental design was applied using Minitab Software to obtain the optimal coagulant blend. The models were validated by statistical analysis which showed that the model was sufficient and no further modeling was required. The optimization results showed that a combination of alum, Moringa Oleifera and Cactus Opuntia in proportions of 13%, 42.6% and 44.4%, respectively with a total coagulant dosage of 45mg/L gave the best overall results with the resultant water having a turbidity, pH, conductivity and total alkalinity of 2.7 NTU, 6.99, 308 µS/cm and 137.7mg/L respectively. These physiochemical parameters are within required limits for potable water as per WHO guidelines. From the results, it was concluded that aluminum sulphate (alum) can be successfully blended with natural plantbased coagulants for raw water treatment.
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    Treatment of efuent from a malting processing plant using bio‑coagulants
    (Discover Civil Engineering, 2024-07-05) Murisa, V.; Murisa, V.,; Ncube, S.; Moyo, L.B.; Danha, G.; Mamvura, T.A.
    Stringent measures by water authorities worldwide on water clarification has resulted in the use of chemical-based coagulants to be a formidable challenge. This has driven the need to find alternative sustainable coagulants such as plant-based bio coagulants which are readily available, abundant and cost effective in developing countries such as Zimbabwe. In this regard, the effectiveness of treating effluent from a brewery malting processing plant using bio-coagulants (Aloe Vera, Cactus opuntia and Okra seeds) was investigated compared to that of a chemical coagulant (Alum). The water pollution parameters that were investigated include turbidity, total dissolved solids, electrical conductivity, temperature and pH. The results showed that Alum was the most effective coagulant as it reduced the turbidity from 734 NTU to 68.3 NTU and Total Dissolved Solids (TDS) from 19,800 ppm to 880 ppm at a dosage of 40 mg/L. Okra seeds had an optimum dosage of 35 mg/L with a turbidity and TDS removal of 88.83% and 95.25% respectively. Aloe Vera had an optimum dosage of 40 mg/L with a turbidity and TDS removal of 74.25% and 95.40% respectively. For Cactus opuntia it was 50 mg/L obtaining turbidity and TDS removal of 74.66% and 95% respectively. The best blend of the bio coagulants had a ratio of (0.17, 0.17, and 0.67) for Aloe Vera, Cactus opuntia and Okra seeds respectively. At a dosage of 40 mg/L the turbidity removal was 83.92% and TDS removal was 95.12%. The results indicated that blending the plant-based coagulants had a positive synergistic effect. Highlights Aluminum sulphate (Alum) is more effective in reduction of suspended solids and dissolved solids compared to Aloe Vera, Cactus and Okra seeds. The effectiveness of Aloe Vera, Cactus and Okra seeds as plant-based coagulants indicates that they have active compounds effective as coagulation agents. There were positive synergistic effects upon blending Aloe Vera, Cactus and Okra seeds this was observed in the reduction of turbidity this was higher than when Aloe Vera and Cactus were used individually as coagulants.