Depolymerization of Post-Consumer Polylactic Acid Products

Presented in this study is a novel recycling strategy for poly(lactic acid) (PLA) in which the depolymerization is rapidly promoted by the base–catalyzed hydrol–/alcohol–ysis of the terminal ester bonds under mild conditions. Post–consumer PLA water bottles were cut into approximately 6 × 2 mm plastic chips and heated to 50–60×C in water, ethanol, or methanol as the depolymerization medium. A variety of carbonate salts and alkaline metal oxides were screened as potential catalysts. High–power ultrasound was also investigated as a means to accelerate the PLA decomposition. Both mass loss and HPLC analysis of the treated suspensions showed that the conversion of PLA to lactic acid/lactic esters was achieved with yields over 90% utilizing either ultrasonics or a hot bath. It was found that the most rapid decomposition occurred in solution of sodium hydroxide in methanol at 50oC, in which maximum depolymerization was complete in 5 min. It was also seen that the degree of crystallinity affected the rate of depolymerization

Novel Characterization Method of Biodiesel Produced from Soybean Oil using Thermogravimetric Analysis

The aim of this study was to demonstrate thermogravimetric analysis (TGA) as a potential method for monitoring biodiesel production. Soybean oil and commercial biodiesel were mixed in different proportions by weight. Mixtures of different biodiesel/soybean oil ratios were also created by interrupting a base-catalyzed transesterification process for producing biodiesel at various times. The mixtures produced by both approaches were analyzed with TGA. The results were then compared with data obtained by proton nuclear magnetic resonance spectroscopy ( 1HNMR spectroscopy). The relative weight losses in both sets of mixtures we generated correlated well to the proportion of biodiesel present in the sample. The results from both analytical methods were in good agreement and within a deviation of 5%. Thus, TGA is a simple, convenient and economical method for monitoring biodiesel production

Purification and Quality Enhancement of Fuel Ethanol to Produce Industrial Alcohols with Ozonation and Activated Carbon: Method Developments for Quantification of Impurities and their Removal Mechanisms

The total ethanol production in the United States became over 9 billion gallons/year in 2007. Only about 3% of this is used in producing food-grade alcohol, but this represents a higher value product. The ethanol production process includes corn milling, cooking, saccharification, fermentation, and separation by distillation. To achieve industrial and food-grade quality, additional purification is required. Impurities in ethanol could threaten human health and cause unpleasant flavors. This purification is currently achieved by further distillation. Further distillation is costly and not totally effective in removing all impurities. We have tested an advanced approach to purify ethanol by using ozone, activated carbon, and carbon dioxide. In previous research, we have shown that ozone can remove several undesirable compounds that remain in ethanol after distillation. Also, additional treatment with activated carbon can adsorb ozonolysis byproducts and some non-oxidizable compounds. In this study, we have focused on method development for analysis of volatile by-products using solid phase microextraction (SPME) of headspace volatiles and gas chromatography-mass spectrometry (GC-MS). We have also determined which of the mechanisms (ozonation, gas stripping, and activated carbon treatment) is responsible for removal of impurities. To date, we have confirmed up to 100% reduction of particular impurities by ozonation alone, but additional removal of some compounds occurs through gas stripping and GAC adsorption. The cost of the proposed treatment process is expected to be below 0.02 dollars per gallon. It is much lower than the cost of additional distillation, ca. 0.30 dollars per gallon

Novel bio-based composites of polyhydroxyalkanoate (PHA)/distillers dried grains with solubles (DDGS)

The PHA/DDGS composite is a promising low-cost, bio-based material for use in crop containers for the horticulture industry. This research effort has quantified the effects on mechanical and thermal properties of adding different amounts of DDGS to a PHA matrix. PHA and DDGS were mixed using a twin-screw microcompounder. Fracture surface morphology and thermal and rheological properties were evaluated using scanning electron microscopy (SEM), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and rheometer measurements. The adhesion between PHA and DDGS decreased with an increase in DDGS content from 10% to 30%. Melting temperature and crystalline temperature decreased with the increasing content of DDGS filler, indicating that PHA and DDGS interacted favorably. The complex viscosity and elastic shear modulus of the blends were increased by the increasing DDGS content. The storage modulus and glass transition temperature showed little change across the different ratios of DDGS, indicating that DDGS should be a useful filler that can decrease the cost of PHA-based materials significantly while preserving the dynamic mechanical properties and glass transition temperature