Chemical Engineering Publications

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    Synthesis of glass-based catalysts for biodiesel production from a blend of beef tallow and waste cooking oil
    (ELSEVIER, 2025-01-16) Mashamba, M.; Tshuma, L.; Moyo, L. B.; Tshuma, N.; Simate, G. S.
    The perennial disparity between supply and demand of energy as a result of burgeoning populations, expeditious urbanisation and industrialisation has driven the need for alternative energy sources. Biodiesel has emerged as a promising vehicular fuel due to its similar physiochemical properties to mineral diesel and its potential to minimise environmental impact. However, the commercialisation of biodiesel production faces challenges, particularly related to feedstock and catalyst selection. This study explored the utilisation of waste laboratory glass to synthesize heterogeneous catalyst for producing biodiesel from a blend of beef tallow and waste cooking oil. Heterogeneous catalysts are crucial for achieving high conversion efficiency, reusability, ease of separation and minimal environmental degradation. The particle size distribution of the catalysts was heterogeneous, with 23.33 % of particles passing 710 μm, 30.83 % passing 500 μm, and 45.83 % passing 350 μm. XRF analysis revealed that silica was the primary elemental constituent, comprising over 70 % of the total sample composition, and successful incorporation of Na, Mg, and Zn in the respective treated catalysts was observed. FTIR analysis of the calcined and uncalcined catalysts showed a sharp decrease in hydroxyl functional groups, indicating successful calcination. All glass-based catalyst samples exhibited strong Si-O-Si vibration stretches around 1100cm− 1, confirming the presence of silicon as the glass precursor. The FTIR results of the crude biodiesel samples produced by the catalysts at 15 min intervals showed that the NaOH treated glass-based catalyst exhibited the fastest transesterification reaction.. The results showed that the NaOH treated, MgO treated, Zncl2 treated, and control glass-based catalysts achieved catalyst yields of 80.63 %, 86.13 %, 91.38 %, and 94.25 % respectively, upon calcination. Furthermore, the produced biodiesel was characterised to evaluate its fuel properties: the tested parameters kinematic viscosity, density, flash point and acid value were within the desirable limits for biodiesel according to American and European standards . Moreover, the catalyst showed that it can be reused as after six cycles of reuse a biodiesel yield above 89 % was realised.
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    Effect of ball and feed particle size distribution on the milling efficiency of a ball mill: An attainable region approach
    (2018) Hlabangana, N.; Danha, G.; Muzenda, E.
    In this article, alternative forms of optimizing the milling efficiency of a laboratory scale ball mill by varying the grinding media size distribution and the feed material particle size distribution were investigated. Silica ore was used as the test material. The experimental parameters that were kept constant in this investigation was the grinding media filling, powder filling and the mill rotational speed. The data obtained from these batch tests was then analyzed using a model free technique called the Attainable Region method. This analysis technique showed that the required product fineness is a function of grinding media and feed material size distributions. It was also observed from the experimental results that in order to increase the milling efficiency of a ball mill, towards optimum production of material in the desired size class, there is a need to correlate the ball size and the feed size distributions.
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    An attainable region approach for the recovery of iron and zinc from electric arc furnace dust
    (2019) Siame, M.C.; Kaoma, J.; Hlabangana, N.; Danha, G.
    This study investigated the application of the attainable region optimization technique to establish the optimum hybrid hydrometallurgical and pyro-metallurgical process conditions required to treat the electric arc furnace dust. The analysis of the results obtained showed that a combination of an agitation speed of 800 rpm, sodium hydroxide concentration of 8.0 mol/L and a leaching temperature of 80 °C were the optimum conditions for the hydrometallurgical process, while a roasting temperature of 1200 °C, carbon content of 35.27% and a roasting period of 36 h were the optimum conditions for the pyro-metallurgical process. The iron recovered from the dust was recycled in order to upgrade the iron content of the electric arc furnace charge, thereby reducing both process loses and process wastes.
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    An attainable region approach for the recovery of iron and zinc from electric arc furnace dust
    (2019) M.C. Siamea, M. C.; Kaomab, J.; Hlabanganac, N; Danhad, G.
    This study investigated the application of the attainable region optimization technique to establish the optimum hybrid hydrometallurgical and pyro-metallurgical process conditions required to treat the electric arc furnace dust. The analysis of the results obtained showed that a combination of an agitation speed of 800 rpm, sodium hydroxide concentration of 8.0 mol/L and a leaching temperature of 80 °C were the optimum conditions for the hydrometallurgical process, while a roasting temperature of 1200 °C, carbon content of 35.27% and a roasting period of 36 h were the optimum conditions for the pyro-metallurgical process. The iron recovered from the dust was recycled in order to upgrade the iron content of the electric arc furnace charge, thereby reducing both process loses and process wastes.
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    The effect of a sulphate-reducing bacteria on the rate of corrosion of steel alloys
    (2019) L. Shakua, L.; G. Danha, G.; Hlabanganac, N.; Bhero, S.
    three analytical techniques we will employ in measuring the rate of corrosion are the electrochemical impedance spectroscopy, cyclic polarization and the mass loss method. The test material used is the 316L stainless steel and the mild steel coupons. The microorganism we are going to use for this investigation is the sulphate-reducing bacteria (SRB). The scope of the study will cover the cultivation of the micro-organism, cell count, electrochemical testing, cyclic polarization testing, analysis of corrosion product, mass loss and the pitting morphology consistent with the microbiologically induced corrosion mechanism. Our results show that the chemical composition of the mild steel and stainless steel test material conformed to SAE1020 and Type 316L stainless steel respectively. We also found that the corrosion rate of mild steel in both biotic and abiotic systems was significantly higher than that of the 316L stainless steel. The biotic system was more corrosive for both the mild steel and the 316L stainless steel. The biotic system showed a substantial corrosion effect in two days while the abiotic system showed the same effect after seven days. The cell count procedure confirmed the presence of sulphate-reducing bacteria throughout the test. Keywords: Type your keywords here, separated by semicolons ; Available online at www.sciencedirect.com ScienceDirect Procedia Manufacturing 00 (2019) 000–000 www.elsevier.com/locate/procedia 2351-9789 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the organizing committee of SMPM 2019. *Corresponding Author Email: danhag@biust.ac.bw 2nd International Conference on Sustainable Materials Processing and Manufacturing (SMPM 2019) The effect of a sulphate-reducing bacteria on the rate of corrosion of steel alloys L. Shakua , G. Danha*b , N. Hlabanganac , S. Bherob a Department of Metallurgy, P.O Box 16, Johannesburg, South Africa b Department of Chemical Engineering, National University of Science & Technology, Box A.C 939 Ascot, Bulawayo, Zimbabwe c Department of Chemical, Materials and Metallurgical Engineering, Faculty of Engineering and Technology, Botswana International University of Science and Technology, Plot 10071 Boseja Ward, Private Bag 16 Palapye, Botswana Abstract In this article, we investigate the effect of micro-organisms on the rate of corrosion of stainless steel and mild steel alloys. The three analytical techniques we will employ in measuring the rate of corrosion are the electrochemical impedance spectroscopy, cyclic polarization and the mass loss method. The test material used is the 316L stainless steel and the mild steel coupons. The microorganism we are going to use for this investigation is the sulphate-reducing bacteria (SRB). The scope of the study will cover the cultivation of the micro-organism, cell count, electrochemical testing, cyclic polarization testing, analysis of corrosion product, mass loss and the pitting morphology consistent with the microbiologically induced corrosion mechanism. Our results show that the chemical composition of the mild steel and stainless steel test material conformed to SAE1020 and Type 316L stainless steel respectively. We also found that the corrosion rate of mild steel in both biotic and abiotic systems was significantly higher than that of the 316L stainless steel. The biotic system was more corrosive for both the mild steel and