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ABSTRACT: Dewatering of the green algae Neochloris oleoabundans by flocculation was investigated for chitosan biopolymer, ferric sulfate, and alum. Chitosan was found to be most effective flocculant, with an optimum dose of 100mg/L algae broth. Zeta potential measurements suggest the mechanism involves both adsorption and charge neutralization processes. Life cycle assessment (LCA) was used to compare the chitosan method to other flocculation methods as well as centrifugation and filtration/chamber press processes. LCA showed that among these techniques, flocculation by chitosan is the least energy intensive and had the lowest impacts across all other categories of environmental impacts. The results are discussed in the overall context of biofuel production from algal biomass.
Bioresource technology 06/2012; 121:445-9. · 4.25 Impact Factor
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ABSTRACT: This critical review focuses on the origins and preparation of bio-based surfactants, defined here as non-soap, amphiphilic molecules in which the carbon atoms are derived from annually renewable feedstocks. Environmental concerns and market pressures have led to greater relevance of these chemicals in commercial applications in recent years and extensive research has gone into exploring new classes of surfactants. Highlighted here are examples of bio-based surfactants that are produced on an industrial scale and/or are based on abundant starting materials. The trend of increasing use of renewable resources as starting materials for surfactants is introduced, followed by extensive discussion of the major classes of bio-derived hydrophobes and hydrophiles. Also discussed is the status of research and development with regard to biosynthetically produced surfactants. Finally, concluding remarks address the potential for new surfactant molecular structures as a result of ongoing development in the chemistry of biorefineries, i.e., that the transformation of lignocellulose into fuels is likely to support the manufacturing of new bio-based coproducts (238 references).
Chemical Society Reviews 02/2012; 41(4):1499-518. · 28.76 Impact Factor
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ABSTRACT: Green chemistry and engineering seek to maximize efficiency and minimize health and environmental hazards throughout the chemical production process. This review demonstrates how green chemistry principles and metrics can influence the entire life cycle of a chemical from design through disposal. After reviewing essential metrics and recent advances in the field within this context, we consider the case of nanotechnology. As an emerging field, nanotechnology provides an instructive framework to consider the influence and application of green chemistry. Interdisciplinary innovation guides both fields, and both seek to transform the nature of technology. The applications and implications of emerging green technology are discussed, and future opportunities for interdisciplinary collaborations are highlighted.
ERN: Technology (Topic). 11/2011;
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Green Chemistry Letters and Reviews 03/2011; 4(1):35-40. · 0.98 Impact Factor
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ABSTRACT: Lignin from candlenut shells was isolated using an ethanol-water accelerated solvent extraction method. Yields (based on Klason lignin) increased from about 14 to 33% as temperature increased from 100 to 195 °C and were also influenced by the amount of aqueous acid used to precipitate lignin from the extraction liquor. These yields were higher than could be obtained using a conventional dioxane-water acidolysis method. The resulting lignin was characterized by IR, 31P NMR, and 1H-13C HMQC NMR spectroscopic techniques. The lignin contained predominantly guaiacyl units, and both the total hydroxyl group content and phenolic hydroxyl group content were high.
Journal of Agricultural and Food Chemistry 09/2010; 58(18):10045-8. · 2.82 Impact Factor
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ABSTRACT: We present a detailed study of the structure and properties of a supramolecular complex formed via hydrogen bond association between poly(acrylic acid) chains and an imidazole-terminated biphenyl mesogen. The system exhibits a rich phase behavior as a function of temperature and stoichiometry, expressed as the molar ratio S between the number of mesogens and binding sites present. Smectic mesophases are formed for all S ≥ 0.033, a surprisingly small number. The dependence of the characteristic length scale of the mesophase on stoichiometry does not follow the expected 1-D swelling law. At low stoichiometries, S ≤ 0.2, the system exhibits little or no change in structure up to temperatures as high as 200 °C, beyond which changes become temperature irreversible. In contrast, at higher S, the system features complex thermally driven transitions among tilted monolayer and bilayer arrangements and complete, reversible isotropization of the system at elevated temperatures. Over a limited range of temperatures and compositions, a supramolecular length scale emerges that is well beyond the upper limit imposed by a bilayer construct and thus cannot be accounted for within the conventional paradigm. Binding isotherms reveal that the polymer has a limited capacity for the ligand with saturation occurring for S ≥ 0.33. These results suggest that the common assumption of homogeneously distributed tightly bound ligands with layer-like phase separation from the polymer backbone do not apply in this system over all compositions. The anomalous phase display is consistent with demixing between polymer rich and polymer poor domains due to the presence of excess unassociated mesogen, which can act as a solvent for the system.
07/2010;
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Green Chemistry Letters and Reviews 03/2007; 1(1):9-24. · 0.98 Impact Factor
