Browsing by Author "Nkomo, N.Z."

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    Enhanced technique for removal of methylene blue dye from water using Luffa microcrystalline cellulose
    (South African Journal of Chemistry, 2024-02-11) Ngwenya, V.; Ndebele, N.R.; Ncube, L.K.; Nkomo, N.Z.; Gadlula, S. and Ndlovu, L.N.; Ndlovu, L.N.
    Methylene blue, a toxic and carcinogenic azo dye, is being discharged as industrial effluent to the environment posing a threat to human health and marine life. Different methods have been developed to alleviate these problems associated with methylene blue. In this work, the adsorption of methylene blue dye was studied using Luffa microcrystalline cellulose (Luffa MCC) under different physicochemical conditions. Luffa MCC was synthesized through a hydrolysis process which entails the extraction of alpha-cellulose from Luffa cylindrica fibers followed by acid treatment for microcrystallisation. The α cellulose extraction was achieved through a pretreatment process of Luffa fibers in NaOH followed by bleaching with H 2 O 2 and finally hydrolysis of α-cellulose using HCl. Different methods were used to characterize the properties of Luffa fibers and Luffa MCC. The morphological structure was studied through the use of Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM), Energy Dispersive X-ray spectroscopy (EDS), and Thermogravimetric Analyzer (TGA). Adsorptive removal of methylene blue was studied at different pH, initial dye concentration, adsorbent dosage, temperature and contact time. Maximum adsorption efficiency of 99.69%. of methylene blue was achieved at pH 10 in 180 min. The adsorption kinetics suggests a chemisorption process since it was favoring the pseudo-second-order reaction while the isotherm was best described by Langmuir model which suggests that it was monolayer sorption at a homogenous surface. It can be concluded that adsorption properties were significantly improved after the modification of Luffa fibers.
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    Extraction and characterisation of the mechanical properties of cotton stalk bastfibres.
    (2016) Nkomo, N.Z.; Nkiwane, L.C.; Njuguna, D.; Oyondi, E.
    Cotton stalks are a waste by-product of cotton farming and a problem to dispose of as they tend to harbour parasites such as pink bollworm. The stalks are normally disposed of by burning, which contributes to the emission of harmful greenhouse gases which pollute the environment. Cotton stalks were collected from Umguza region in Zimbabwe which is located 53km from Bulawayo town. The stalks were subjected to retting for 3 weeks and there after fibre extraction carried out by means of manual decortication. The fibres were then subjected to a number of tests such as tensile strength, moisture regain, linear density, density and fibre length measurement test. The fibres were characterised according to their position relative to the cotton stalk and segmented as fibres from the top section, middle section and bottom section. The test results from characterisation of the fibres were analysed using SPSS statistical software. The cotton stalk fibres have a light brownish colour and the fibre length was approximately 8.18 cm. The moisture regain of the fibres was highest with fibres extracted from the root area having regain of 11.14%, fibres from the top half had moisture regain of 10.68% and fibres from the bottom half of 10.20%. The diameter of the cotton stalk fibres is 0.23mm which is similar to the diameter found in sisal fibres. The fibres have an elongation of 1.5%. The fibre yield from the cotton stalks is 23%. The cotton stalk fibres have density of approximately 1.45g/cm3.These fibres have possibility in various application which include fibreboards, for wall partitions, furniture applications and ceiling boards to replace solid wood materials.
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    Statistical analysis of the significance of variation in properties of cotton stalk fibres extracted from different sections of the cotton stalk.
    (International organization of Scientific Research, 2017-05) Nkomo, N.Z.; Nkiwane, L.C
    Abstract:-Cotton is cultivated primarily for its boll fibre and little use is made of the cotton stalk. The cotton stalks are breeding ground for pests therefore the stalks are normally burnt in the field creating air pollution. Cotton stalks were collected from farms through random sampling and subjected to natural water retting and there after mechanical decortication and categorised according to their location relative to the stalk as top section, middle section and bottom section fibres. The physical properties of the cotton stalk fibres was characterised by tensile strength, moisture regain, linear density, diameter and fibre length tests. These results were analysed using one way multivariate analysis (MANOVA) in SPSS with three levels being one for each section of the stalks to test the statistical significance of the differences of the fibre properties from different sections of the cotton stalk. Pillais trace test showed that there was statistical significant difference between fibres from different locations when considered jointly on the variables tensile strength, elongation, fibre density, fibre diameter, fibre length, linear density and moisture regain. This test was followed up by Tuskey’s HSD post hoc test which showed which parameters varied between which sections of the stalk.