Research Outputs (Chemical and Metallurgical Engineering)

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For information on accessing Research Articles content please contact Salome Potgieter by email : salome.potgieter@wits.ac.za or Tel : 011 717 1961

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2018 - 20192

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Start date: 2010End date: 2019

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    Lignocellulosic Bioethanol Production from Grasses Pre-treated with Acid Mine Drainage: Modeling and Comparison of SHF and SSF
    (Elsevier, 2019-09-01) Burman, N.W.; Sheridan, C.M.; Harding, K.G.
    Acid mine drainage (AMD) was used for the pre-treatment of indigenous South African grass (Eragrostis curvula), and compared to H2SO4 (1 wt%) pre-treatment. The optimal pre-treatment duration were investigated and found to be 1 day for H2SO4 and 3 days for AMD pre-treatment. The optimal biomass solid loadings were found to be 20 wt% for both pre-treatment methods. Additionally, enzymatic hydrolysis and fermentation to produce ethanol were investigated for both separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF). In both SHF and SSF, the H2SO4 pre-treatment obtained higher concentrations of glucose/ethanol compared to AMD pre-treatment. The concentration of glucose/ethanol obtained using AMD pre-treatment was 70–80% of that achieved using H2SO4 pre-treatment. Empirical equations modeling the glucose/ethanol concentration in all processes were determined using a least squares method. Concentrations predicted by the models were found to have a high correlation (r2 = 0.87–0.99) to concentrations determined experimentally
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    Modelling of Low Temperature Dilute Sulfuric Acid Pre-treatment of South African Grass
    (Elsevier, 2018-12-01) Burman, N.W.; Sheridan, C.; van Dyk, L.; Harding, K.G.
    Dilute acid hydrolysis is an effective method of pre-treatment of lignocellulosic biomass. Although there are many studies modelling this pre-treatment at high temperature (120–210 °C), no studies were found modelling this reaction at low temperature. In this study, a long grass species was pre-treated with dilute sulfuric acid (pH 1, 2 & 3) at low temperatures (35 °C, 65 °C, 90 °C). The hydrolysis of xylan was found to obey a bi-phasic model in which there are two fractions of xylan, with significantly different hydrolysis rates. The rates of hydrolysis of the fast reacting fraction was found to obey Arrhenius type temperature dependence (Ea = 155.06 kJ/mol, A0 = 1.65 × 1019/min), which agrees with findings of similar studies at higher temperatures. A negligible rate of hydrolysis was determined for the slow fraction which differs from previous studies. The proportion of the slow reacting fraction (50%) which is lower than previously determined (55%–100%).