Maliger V.R.,Sugar Research and Innovation |
Doherty W.O.S.,Sugar Research and Innovation |
Frost R.L.,Queensland University of Technology |
Mousavioun P.,Sugar Research and Innovation
Industrial and Engineering Chemistry Research | Year: 2011
Sugar cane fiber (i.e., bagasse) is the residue from sugar cane milling during sugar manufacture. This study uses chemical analysis, thermogravimetry analysis (TG), derivative thermogravimetry (DTG), X-ray powder diffraction (XRD), and energy-dispersive spectroscopy to investigate the composition and thermal decomposition of bagasse from various origins. The results indicate that bagasse from different varieties of sugar cane have different proportions of carbohydrates, lignin, and ash contents and different degrees of crystallinity. TG thermograms show four distinct stages of mass losses instead of three stages reported for bagasse decomposition. This is due to the presence of residual sucrose. The thermal decomposition profile of bagasse is independent of origin, though minor differences exist in the temperatures at the maximum rate of weight losses for the hemicellulose and cellulose components of bagasse as well as on the residue yield. The main phases in ashes of the bagasse chars are quartz, acranite, and langbeinite, with slight shifts in the d values among the samples probably related to differences in the concentrations of inorganic ions in the crystal lattices. The results are further discussed in terms of the activation energy of the devolatilization process obtained using Friedman's method. © 2010 American Chemical Society.
Nguyen D.M.T.,Sugar Research and Innovation |
Zhang Z.,Queensland University of Technology |
Doherty W.O.S.,Sugar Research and Innovation
Journal of Agricultural and Food Chemistry | Year: 2015
The degradation efficiencies and behaviors of caffeic acid (CaA), p-coumaric acid (pCoA), and ferulic acid (FeA) in aqueous sucrose solutions containing the mixture of these hydroxycinnamic acids (HCAs) were studied by the Fenton oxidation process. Central composite design and multiresponse surface methodology were used to evaluate and optimize the interactive effects of process parameters. Four quadratic polynomial models were developed for the degradation of each individual acid in the mixture and the total HCAs degraded. Sucrose was the most influential parameter that significantly affected the total amount of HCA degraded. Under the conditions studied there was a <0.01% loss of sucrose in all reactions. The optimal values of the process parameters for a 200 mg/L HCA mixture in water (pH 4.73, 25.15 °C) and sucrose solution (13 mass %, pH 5.39, 35.98°C) were 77% and 57%, respectively. Regression analysis showed goodness of fit between the experimental results and the predicted values. The degradation behavior of CaA differed from those of pCoA and FeA, where further CaA degradation is observed at increasing sucrose and decreasing solution pH. The differences (established using UV/vis and ATR-FTIR spectroscopy) were because, unlike the other acids, CaA formed a complex with Fe(III) or with Fe(III) hydrogen-bonded to sucrose and coprecipitated with lepidocrocite, an iron oxyhydroxide. © 2015 American Chemical Society.