Howard D. Mettee

Purification of carbohydrate-containing substrates from plant biomass hydrolysates

Carbohydrate-containing substrates are produced in Russia by means of dilute acid hydrolysis of wood and vegetable residues. Hydrolysates contain 3 to 4% monosaccharides and nearly 1% impurities. The common schemes used to prepare the hydrolysate for fermentation include cooling by self-evaporation; inversion of oligosaccharides; neutralization of sulfuric (and organic) acids; addition of mineral food substances containing nutrient N, P, and K salts; aeration to coagulate colloidal substances; and sedimentation of residues. Our work led to the suggestion that a flocculation step using cationic polyelectrolytes be added to purify more completely the substrates from lignin-huminic substances (LHS). This method permits the transfer of a part of the dissolved and colloidal LHS into a suspended state and the removal of more than 90% of the suspended materials, thereby increasing the yield and quality of ethanol and fodder yeast. Three industrial plants have reported successful results using this method in the past few years. Flocculation has also proven itself capable of clearing waste culture liquids of their dispersed phases by extents of 30–60%, as measured by chemical oxygen demand, color depth, or lignin content parameters, prior to consideration of such wastewater for recycling.

A guided inquiry experiment for the measurement of activation energies in the biophysical chemistry laboratory: Decarboxylation of pyrrole‐2‐carboxylate

A laboratory experiment for undergraduate biophysical chemistry is described, in which the acid concentration and temperature dependences of the decarboxylation of pyrrole‐2‐carboxylate are measured using a continuous ultraviolet (UV) spectrophotometric assay. Data collection and analysis are structured using principles of guided inquiry. Data leading to the calculation of multiple rate constants at varying temperatures and acid concentrations can be collected within one laboratory period, using inexpensive reagents and standard instrumentation. These experiments permit determination of activation energies that are lower at high acid concentration, indicative of a subtle change in the reaction mechanism with decreasing pH. The reaction is readily observable by students as they collect UV spectrophotometry data, and the decarboxylation reaction is related to biologically relevant enzymatic reactions.

ESTABLISHMENT OF CORRELATION BETWEEN CALORIFIC VALUE AND IR-SPECTRA CHARACTERISTICS OF WOOD PYROLYTIC TARS BY MULTIDIMENTIONAL ANALYSIS METHOD

It is demonstrated that multidimentional analysis method could reveal a good correlation between calorific value and IR-spectra characteristics of wood pyrolytic tars. Application of this method to a large-scale production of wood pyrolytic biofuels could serve as a new analytic method for fuel calorific value determination.