Rational design of polymer-based absorbents: application to the fermentation inhibitor furfural

BACKGROUND: Reducing the amount of water-soluble fermentation inhibitors like furfural is critical for downstream bio-processing steps to biofuels. A theoretical approach for tailoring absorption polymers to reduce these pretreatment contaminants would be useful for optimal bioprocess design. RESULTS: Experiments were performed to measure aqueous furfural partitioning into polymer resins of 5 bisphenol A diglycidyl ether (epoxy) and polydimethylsiloxane (PDMS). Experimentally measured partitioning of furfural between water and PDMS, the more hydrophobic polymer, showed poor performance, with the logarithm of PDMS-to-water partition coefficient falling between −0.62 and −0.24 (95% confidence). In contrast, the fast setting epoxy was found to effectively partition furfural with the logarithm of the epoxy-to-water partition coefficient falling between 0.41 and 0.81 (95% confidence). Flory-Huggins theory is used to predict the partitioning of furfural into diverse polymer absorbents and is useful for predicting these results. CONCLUSION: We show that Flory-Huggins theory can be adapted to guide the selection of polymer adsorbents for the separation of low molecular weight organic species from aqueous solutions. This work lays the groundwork for the general design of polymers for the separation of a wide range of inhibitory compounds in biomass pretreatment streams

Towards the Synthesis of (NAPY1): A Potential Metal-Peroxide Binding Ligand

We report the design and the first synthetic step towards the synthesis of a potential metal-peroxide binding ligand containing N,N-naphthyridone groups. We propose that these groups will be effective at coordinating to metals as well as also potentially binding\ud and activating O2 because of the two possible sites on each pyridine ring for metal coordination and hydrogen bonding. The synthesis of the naphthyridine group is still in working progress, although the first intermidiate molecule was successfully synthesized\ud and characterized. Studies of possible tautomers, using PC Spartan Pro, were performed to elucidate the most energetically favorable tautomer of the 7-methyl-1, 8-\ud naphthyridine-2-one molecule. Our Semi-Empirical AM1 data showed the A, B, and C\ud tautomers of the molecule having energies of 131.41 kJ/mol, 42.08 kJ/mol, and 79.15 kJ/mol respectively. Tautomer B being the molecule with the lowest conformational energy makes it the most enegetically favorable and stable tautomer of the three. Data from Hartree Fock 3-21G calculations also support this trend with energy differences of a least 10 kJ/mol for the A and C tautomers when compared the the tautomer B. Since, tautomer B is the desired molecule for the proposed ligand system, we have more\ud inspiration to complete the synthesis of the naphthyridine group

Tailoring Polymer Micro-extraction Phases to Enhance the Sensitivity and Selectivity of Raman Spectroscopy

Thesis (Ph.D.)--University of Washington, 2013Raman Spectroscopy (RS) systems are evolving toward portable, affordable, and highly versatile analytical chemistry platforms, though sensitivity, selectivity, and fluorescence in many complex multi-component real-world samples remains challenging. We investigated the combination of solid phase micro-extraction (SPME) with Raman spectroscopy as a strategy to address some of these limitations. SPME is best known as a technique in chromatography that uses hydrophobic polymer phases like polydimethylsiloxane (PDMS) to extract and preconcentrate non-polar target analyte in headspace analysis. SPME not only enhances detection by pre-concentration of analytes, but when combined with Raman spectroscopy, offers an opportunity to reduce interference from the background by tailoring the polymer phase to specific classes of analytes in complex mixtures. Here we establish SPME/Raman as a quantitative technique that is capable of enhancing the measurement of organic contaminates in water, anesthetic compounds in serum, and inhibitory molecules in the multi-phase and multi-component broths produced by pretreatment of biomass. Flory-Huggins theory is used to describe the predicted trends in the thermodynamic partitioning of dilute analytes into polymer phases. We show experimentally and theoretically that the equilibrium partitioning, denoted by the partition coefficient K, can enhance the Raman signal by 2 orders of magnitude or more when the analyte is detected in the polymer phase rather than the solvent phase. Specifically, we find that SPME/Raman measurements of aqueous benzene and toluene partitioning into PDMS phases have log (K) values of 2.35 and 1.90, respectively, matching literature values determined with other methods. We also examine the use of SPME/Raman for enhanced detection of general anesthetics (halothane, isofluorane, propofol), quinoline, and fermentation inhibitors (furfural, HMF) into either PDMS or epoxy polymer phases. We then demonstrate the utility of Flory-Huggins theory in understanding and optimizing the selection of polymer-analyte pairs to enhance the sensitivity and selectivity of SPME/RS

Rational design of polymer-based absorbents: application to the fermentation inhibitor furfural

Reducing the amount of water-soluble fermentation inhibitors like furfural is critical for downstream bio-processing steps to biofuels. A theoretical approach for tailoring absorption polymers to reduce these pretreatment contaminants would be useful for optimal bioprocess design

Environmental assessment of mild bisulfite pretreatment of forest residues into fermentable sugars for biofuel production

Sugar production via pretreatment and enzymatic hydrolysis of cellulosic feedstock, in this case softwood harvest residues, is a critical step in the biochemical conversion pathway towards drop-in biofuels. Mild bisulfite (MBS) pretreatment is an emerging option for the breakdown and subsequent processing of biomass towards fermentable sugars. An environmental assessment of this process is critical to discern its future sustainability in the ever-changing biofuels landscape. This work discusses some of the environmental impacts of designing and operating a sugar production facility that uses MBS as a method of treating cellulosic forest residuals. The impacts of each unit process in the proposed facility are highlighted. A comparison to other sugar-making process is detailed and will inform the growing biofuels literature

Life Cycle Analysis of Residual Woody Biomass-Based Biofuel

This report describes the environmental implications of feedstock recovery, production, and utilization of residual woody biomass based biojet fuel