Richard Hendrickson

Industrial scale-up of pH-controlled liquid hot water pretreatment of corn fiber for fuel ethanol production

The pretreatment of cellulose in corn fiber by liquid hot water at 160°C and a pH above 4.0 dissolved 50% of the fiber in 20 min. The pretreatment also enabled the subsequent complete enzymatic hydrolysis of the remaining polysaccharides to monosaccharides. The carbohydrates dissolved by the pretreatment were 80% soluble oligosaccharides and 20% monosaccharides with º1% of the carbohydrates lost to degradation products. Only a minimal amount of protein was dissolved, thus enriching the protein content of the un dissolved material. Replication of laboratory results in an industrial trial at 43 gallons per minute (163 L/min) of fiber slurry with a residence time of 20 min illustrates the utility and practicality of this approach for pretreating corn fiber. The added costs owing to pretreatment, fiber, and hydrolysis are equivalent to less than

Continuous pH Monitoring During Pretreatment of Yellow Poplar Wood Sawdust by Pressure Cooking in Water

0.84/gal of ethanol produced from the fiber. Minimizing monosaccharide formation during pretreatment minimized the formation of degradation products; hence, the resulting sugars were readily fermentable to ethanol by the recombinant hexose and by pentose-fermenting Saccharomyces cerevisiae 424A (LNH-ST) and ethanologenic Escherichia coli at yields >90% of theoretical based on the starting fiber. this cooperative effort and first successful trial opens the door for examining the robustness of the pretreatment system under extended run conditions as well as pretreatment of other cellulose-containing materials using water at controlled pH.

Optimal Packing Characteristics of Rolled, Continuous Stationary-Phase Columns

Yellow poplar wood sawdust consists of 41% cellulose and 19% hemicellulose. The goal of pressure cooking this material in water is to hydrate the more chemically resistive regions of cellulose in order to enhance enzymatic conversion to glucose. Pretreatment can generate organic acids through acid-catalyzed degradation of monosaccharides formed because of acids released from the biomass material or the inherent acidity of the water at temperatures above 160°C The resulting acids will further promote the acid-catalyzed degradation of monomers that cause both a reduction in the yield and the formation of fermentation inhibitors such as hydroxymethyl furfural and furfural. A continuous pH-monitoring system was developed to help characterize the trends in pH during pretreatment and to assist in the development of a base (2.0 M KOH) addition profile to help keep the pH within a specified range in order to reduce any catalytic degradation and the formation of any monosac-charide degradation products during pretreatment. The results of this work are discussed.

Bioprocessing in space

Rolled, continuous stationary phases were constructed by tightly rolling and inserting a whole textile fabric into a chromatography column. This work reports the column performance, in terms of plate height, void fraction, and resolution, of 10 cellulose‐based fabrics. The relation between fabric structural properties of yarn diameter, fabric count, fabric compressibility, and column performance are quantitated. General requirements, including reproducibility of packing, for choosing fabrics to make a good SEC column are identified. This research showed that the packed columns have an optimal mass of fabric that minimizes plate height and maximizes resolution, in a manner that is consistent with chromatography theory. Mass of material packed is then an important column parameter to consider when optimizing columns for the rapid desalting of proteins. Proteins were completely separated from salt and glucose in less than 8 min at a pressure drop less than 500 psi on the rolled, continuous stationary‐phase columns. These results, together with stability and reproducibility, suggest potential industrial applications for cellulose‐based rolled, continuous stationary‐phase columns where speed is a key parameter in the production process.

Analytical- and preparative-scale chromatographic separation of phenylalanine from aspartame using a new polymeric sorbent

Two approaches for biomass processing in Controlled Ecological Life Support Systems are compared in a literature survey. The approaches are based on (1) total oxidation of plant matter and (2) the potential of bioregenerative recovery.

Optimization of pH controlled liquid hot water pretreatment of corn stover

Abstract A new, large-pore, cross-linked, polymethacrylate stationary phase separates Phe from Aspartame in 10% aqueous ethanol by reversed-phase chromatography. Batch equilibrium data at 30, 50 and 70°C, obtained with 165-μm particle size material showed linear sorption at loadings of up to 140 mg/g stationary phase, and corresponded to a mobile phase adsorbate concentration approaching the solubility limits. Column runs with 40-, 60-, 117-, and 165-μm particle size materials at 30–70°C showed retention behavior that was predictable from batch equilibrium data, and was independent of particle size at sample volumes as high as 80% of the column void volume and at outlet concentrations of 5–10 mg/ml. The relatively large pores (250 A) of the stationary phase allowed free access of small molecules, with the methacrylate structure promoting strong sorption of aromatic amino acids. These characteristics permitted the ready calculation of column retention times, and facilitated extrapolation of analytical-scale results obtained with small particle size material to preparative-scale separations carried out under volume overload conditions with a larger particle size stationary phase.