Browsing by Author "Dube, Donatus"

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    “Appropriate Technology for the 21st Century: Technological Innovation to Empower Africa”
    (2014-11-25) Dube, Donatus; Parekh, Champaklal T.; Siangwata, Sherpherd; Nyathi, Makhosazana
    Low-income earners in Zimbabwe’s rural areas currently depend, to a very large extent, on water from rivers, wells, dams and boreholes. Water from all these sources is contaminated in one form or the other by the anthropogenic as well as natural pollutants and in many cases is unsuitable for human consumption. Over the past decade, an increasing number of field-based studies have been undertaken to determine the success of point – of – use (POU) treatment measures in reducing waterborne diseases. However for poor communities in rural areas of Zimbabwe such interventions have remained largely ineffective due to availability and application challenges, lack of support, resistance due to cultural stigmas and mere ignorance. The aim of this research was to provide a simple POU solution to water quality problems in the rural communities of Zimbabwe. Thermally converted magnetite particle material with nanoporosity was used to construct rudimentary filters for use by villagers. Both laboratory and village scale tests were conducted. Results revealed that filters constructed using nano-porous magnetite material were very effective for microbiological and chemical pollution control in water and can be used successfully and sustainably by poor communities in the rural areas.
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    Effectiveness of Biopolymer-Bentonite Clay Composites in Wastewater Treatment
    (2018) Mupasi, N.M; Dube, Donatus; Chiririwa, H; Naidoo, E.B
    The feasibility of employing wood-bentonite clay composite material as a low-cost and effective adsorbent for removal of cations from wastewater has been investigated. The wood-bentonite clay composites were prepared by a solution intercalation method. Results showed that the percentage adsorption of Pb 2+ , Mg 2+ and Ca 2+ from the effluent water was 88.46, 81.12 and 95.76 % respectively, using 10 g/L of the adsorbent. The desorbed wood-bentonite clay composites could be reused for adsorption of the cations.
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    Removal of Chromium and Nickel from Electroplating Wastewater using Magnetite Particulate Adsorbent: (1) Effect of pH, Contact Time and Dosage, (2) Adsorption Isotherms and Kinetics
    (Canadian Center of Science and Education, 2016-02-06) Dube, Donatus; Champaklal, Parekh T.; Nyoni, Bothwell
    Wastewater discharged into municipal sewer systems from electroplating process plants contains a heavy load of metal ions and often requires pre-discharge treatment. Treatment of wastewater to reduce the concentration of metal ions employing an adsorption process has been studied using a wide range of adsorbents. In this work, the concentrations of chromium and nickel ions in wastewater samples from a local electroplating shop were found to be above the limits set out by the Bulawayo City Council, and the Environmental Management Agency, a statutory agency under the Ministry of Environment and Tourism, Government of Zimbabwe. Furthermore, the removal of chromium and nickel ions from the wastewater using magnetite as an adsorbent is studied. Magnetite particulate adsorbent used in this experiment has demonstrated to be an effective adsorbent material. At the optimum process operating pH of 4 – 7 the absorbent was able to achieve removal rates of up to 99% for chromium and 98% for nickel. The adsorption processes for chromium and nickel have been proven to be physical in nature using the Dubinin-Radushkevich isotherm model. Also, the adsorption kinetics data fit well with pseudo second-order kinetic model.
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    Removal of Heavy Metal Ions from Household Drinking Water Using Acacia Galpinii Seeds and Seed Pods
    (2018) Dube, Donatus; Chingoma, Candyce
    Contamination of drinking water with heavy metals poses a human health threat, particularly in low-income countries where point-of-use water purification systems are beyond the reach of a majority of households. The study was undertaken to evaluate the efficacy of Acacia galpinii (monkey thorn tree) biomass in removing Pb (ll), Cd (ll), Ca (ll) and Mg (ll) ions from drinking water. A. galpinii biomass from seed and seed pods was processed by pulverizing, Soxhlet oil extraction and particle size grading. The material was analysed by X-ray fluorescence (XRF) and Fourier Transform Infrared (FTIR) spectrophotometry. Influence of the physiochemical parameters (contact time, initial concentration, adsorbent dosage, pH) on the effectiveness of the biomass in removing Pb (ll), Cd (ll), Ca (ll) and Mg (ll) ions was evaluated and the best fit adsorption isotherm model (Langmuir vs. Freundlich) was also determined. Particle size, dose, contact time and pH all played significant roles in the effectiveness of metal removal for both seed and seed pod biomass. At biomass particle size <90 microns, 98% removal rates of Pb (II) ions were achieved for seed pods (AGK) compared with 65% for plain seeds (AGS). The same trend was observed for Cd, Ca and Mg. Contact time for effective removal of metal ions by AGK and AGS were 90min and 120min, respectively. Maximum adsorption was achieved at solution pH 6-8 for all metals. Lead adsorption followed a Langmuir isotherm with maximum adsorption capacities of 10.8932 for AGK and 3.4412 for AGS. Adsorption of Ca and Mg followed a Freundlich model, with adsorption capacity of 1.1789 for Ca and 1.4521for Mg. Acacia galpinii seeds and seed pods are inexpensive, readily available and may serve as a cost effective means for treatment of drinking water for domestic users in the lower end of the income spectrum.