Browsing by Author "Mudono, S."

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    Adsorption of Chromium (VI) Using Nano-ZnO Doped Scrap Tire-Derived Activated Carbon
    (Scientific Research Publication, 2022-09-27) Chigova, J. T.; Mudono, S.
    Nowadays, nano mineral modified biochars show a promising adsorption capacity for pollutants removals by combining the advantages of porous structure of biochar and unique property of nano minerals. In this work, nanozinc oxide doped scrap tire derived activated carbon (nZnO-STAC) was synthesized by wetness impregnation method. Equilibrium data were analyzed using Langmuir and Freundlich isotherm models while the kinetics of the process were examined using Lagergren Pseudo-first and second order, intraparticle diffusion and Elovich kinetic models. Characterization of the activated carbon by Powder X-ray Diffraction (PXRD). The surface groups present on the activated carbon surface were determined using the Fourier Transform Infra-Red Spectroscopy (FTIR) analysis. Optimization studies were carried out to determine the effects of pH, initial metal concentration, adsorbent dosage, contact time and adsorbent particle size on the Cr (VI) removal efficiency. The results showed optimum Cr (VI) removal at pH 3, 10 mg/L concentration, 120 minutes of contact using 1000 - 1400 µm adsorbent particle size at a dosage of 2.5 g/L. The adsorbent structure was found to be predominantly amorphous. The chromium removal efficiency of the adsorbent was around 81.6%. Of the tested kinetic models, the pseudo-second order model exhibited the best fit with the experimental data with an R2 value of 0.9744. This study clearly demonstrates the feasibility of using the nano-ZnO doped scrap tyre derived activated carbon adsorbent for the remediation of chromium (VI) polluted industrial wastewaters.
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    Investigation on the Potential Production of Diesel from Waste Tires
    (Scientific Research Publishing, 2022-10-24) Mudono, S.; Jim, N.; Chigova, J.T.
    An alternative fuel production was performed by catalytic-pyrolysis of waste tires under a nitrogen (N2) environment and with a zeolite catalyst. Pyrolysis of scrap tires has been pointed out as an alternative to the incorrect disposal of tire wastes. Pyrolysis processes can produce tire-derived oils that may be used as fuel or added to conventional fuels, producing fuel blends with improved properties and reduced cost. The pyrolysis process can contribute to removing tire residues from inadequate sites and it can be a sustainable process to produce alternative fuels. The project investigated the conversion of the waste tires into diesel as one way of waste management and also as a viable process which in turn helps to meet the fuel demand. Uses of the diesel and the by-products from the process were also outlined. Experiments were conducted on the pyrolysis process in order to find the optimum conditions for producing the diesel through pyrolysis; the temperature and residence time were optimized in order to get maximum output from the process. The optimum temperature of the reaction was found to be 520˚C and the optimum residence time was 92.5 minutes. Quality tests of the product were then conducted on the obtained product and most of the properties were found to meet the required standard specifications. The most critical properties which are density, final boiling point, flash point and kinematic viscosity, were found to be 0.8495 g/cm3 , 370˚C, 50.5˚C and 3.681 cSt, respectively, and they were within the required specifications. Quality analysis showed that a quality product that is suitable for automobiles could be obtained from the process. The process also produces useful by- products such as char, which can aid in the purification process of the diesel after conversion to activated carbon. The process is environmentally friendly if the appropriate pollution prevention methods like gas absorption are thoroughly implemented. Waste tires are an alternative source of diesel and hence the feasibility of implementing the project on a large scale.
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    On the efficacy of a proposed unsteady state heat loading protocol
    (NetJournals, 2020) Bepete, S.; Dlodlo, T.S.; Mudono, S.; Marwizi, T.
    The paper relates to the thermodynamics of heat transfer processes in which the source of heat is a hot gaseous fluid. The effect of systematically introducing alternating conditions of compression and decompression inside a heat exchanger is investigated. The said alternating conditions are actuated by introducing two periodic valves at the heat exchanger inlet and outlet. This unsteady state mode of operation is shown to result in enhanced heat exchange under certain conditions. This method of heat exchange has been termed ‘Unsteady State Heat Loading Protocol (USHLP).’ Experiments were carried out to compare steady state and USHLP based heat transfer in the context of steam providing heat to a water evaporation process. In the experiments, heat was transferred from steam to an evaporation process through a jacket type heat exchanger. An increase in efficiency of around 42% was observed from replacing steady state heat transfer with USHLP under the same operating conditions and geometric configuration. The results of the experiments are discussed in the concluding sections of the paper. It was noted that consistently less steam was used per unit amount of water evaporated in experiments where USHLP was used as compared to steady state heat transfer