ABSTRACT
Rigid polyurethane foams were synthesized using a renewable polyol from the simple physical mixture of castor oil and crude glycerol. The effect of the catalyst (DBTDL) content and blowing agents in the foams' properties were evaluated. The use of physical blowing agents (cyclopentane and n-pentane) allowed foams with smaller cells to be obtained in comparison with the foams produced with a chemical blowing agent (water). The increase of the water content caused a decrease in density, thermal conductivity, compressive strength, and Young's modulus, which indicates that the increment of CO2 production contributes to the formation of larger cells. Higher amounts of catalyst in the foam formulations caused a slight density decrease and a small increase of thermal conductivity, compressive strength, and Young's modulus values. These green foams presented properties that indicate a great potential to be used as thermal insulation: density (23-41 kg·m-3), thermal conductivity (0.0128-0.0207 W·m-1·K-1), compressive strength (45-188 kPa), and Young's modulus (3-28 kPa). These biofoams are also environmentally friendly polymers and can aggregate revenue to the biodiesel industry, contributing to a reduction in fuel prices.
Subject(s)
Castor Oil/chemistry , Glycerol/chemistry , Polyurethanes/chemistry , Catalysis , Complex Mixtures/chemistry , Elastic Modulus , Thermal ConductivityABSTRACT
This study aimed to evaluate the effect of medium composition and culture conditions on lipid content, fatty acid profile and biomass production by the yeast Yarrowia lipolytica QU21. Lipid production by the yeast growing on glycerol/(NH4)2SO4 (10%/0.1%) reached 1.48g/L (30.1% according to total cell dry weight). When glycerol was replaced by crude glycerol (industrial waste), the lipid yield was 1.27g/L, with no significant difference. Some particular fatty acids were found when crude glycerol was combined with fresh yeast extract (FYE, brewery waste), as linolenic acid (C18:3n3), eicosadienoic acid (C20:2), eicosatrienoic acid (C20:3n3) and eicosapentaenoic acid (C20:5n3). In addition, the FYE promoted an increase of more than 300% on polyunsaturated fatty acid content (PUFA), which is an undesirable feature for biodiesel production. The fatty acid composition of the oil produced by Y. lipolytica QU21 growing on crude glycerol/(NH4)2SO4 presented a potential use as biodiesel feedstock, with low PUFA content.
Subject(s)
Biofuels , Fatty Acids/biosynthesis , Glycerol/metabolism , Yarrowia/metabolism , Biomass , Glucose/metabolism , Industrial Waste , Lipid Metabolism , Nitrogen Compounds/metabolism , Yarrowia/growth & developmentABSTRACT
Multivariate calibration (PLS), principal components analysis (PCA) and linear discriminant analysis (LDA), associated to synchronous spectrofluorimetry, were used to identify and quantify non-transesterified residual vegetable oil in diesel oil with the addition of 2% of biodiesel (B2). The addition of residual oil, one of the easiest ways of adultering fuel, damages engines and leads to tax evasion. Using this method, the samples of diesel oil, B2, and B2 contaminated with residual oil were classified correctly and separated into three well-defined groups. The quantification of residual oil in B2 was carried out in the 0-25% (w/w) band, RMSEC and RMSEP values ranging from 0.26 to 0.48% (w/w) and 1.6-2.6% (w/w), respectively. The method is highly sensitive and efficient to identify and quantify this type of adulterant in which 100% of the samples were correctly classified and the average relative error was approximately 4% in the range 0.5-25% (w/w).
