ABSTRACT
Six polyalcohols derived from lignocellulosic carbohydrates were investigated as carbon sources for electricity generation in single-chamber mediator-less microbial fuel cells (MFCs) for the first time. Electricity was directly generated from all polyalcohols tested, including pentitols (xylitol, arabitol, and ribitol) and hexitols (galactitol, mannitol, and sorbitol). Bacterial cultures initially enriched using acetate could be adapted to these substrates with varied adaptation times. The resultant maximum power density ranged from 1490+/-160 mW/m(2) to 2650+/-10 mW/m(2) at current densities between 0.58 mA/cm(2) and 0.78 mA/cm(2). Galactitol generated the highest maximum power density, while mannitol resulted in the lowest one. The estimated maximum voltage output at an external resistance of 120 Omega ranged between 0.24 V and 0.34 V with half saturation kinetic constants varied from 298 mg/L to 753 mg/L. The removal of chemical oxygen demand (COD) was above 91% for all polyalcohols except sorbitol (71%). Denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S rRNA gene segments of the anode biofilms showed the influence of substrates (polyalcohols) on the anode microbial populations.
Subject(s)
Alcohols/chemistry , Alcohols/metabolism , Bacterial Physiological Phenomena , Bioelectric Energy Sources , Bioreactors/microbiology , Equipment Design , Equipment Failure AnalysisABSTRACT
Chitosan-phenolics systems were investigated as wood adhesives. Adhesion between two pieces of wood veneer developed only when all three components-chitosan, a phenolic compound, and laccase-were present. For the adhesive systems containing a phenolic compound with only one phenolic hydroxyl group, adhesive strengths were highly dependent upon the chemical structures of phenolic compounds used in the system and the relative oxidation rates of the phenolic compounds by laccase. The adhesive strengths were also directly related to the viscosity of the adhesive systems. However, for the adhesive systems containing a phenolic compound with two or three phenolic hydroxyl groups adjacent to each other, no correlations among adhesive strengths, relative oxidation rates of the phenolic compounds by laccase, and viscosities were observed. The adhesion mechanisms of these chitosan-phenolics systems were proposed to be similar to those of mussel adhesive proteins.
Subject(s)
Adhesives/chemistry , Biomimetic Materials/chemistry , Cementation/methods , Chitin/analogs & derivatives , Chitin/chemistry , Laccase/chemistry , Phenols/chemistry , Wood , Acer/chemistry , Chitosan , Materials Testing , Plant Shoots/chemistry , Shear Strength , Tensile Strength , Viscosity , Water/chemistryABSTRACT
In order to enhance the bleaching effect of manganese peroxidase (MnP), unsaturated fatty acids, thiol-containing compounds and various other organic compounds were applied in pulp bleaching experiments with MnP. Thiol-containing compounds did not improve the pulp bleaching effect by MnP. Some unsaturated fatty acids, linoleic acid and linolenic acid provided a better pulp bleaching effect than Tween 80. The correlation between the number of C=C bonds in a fatty acid and its pulp bleaching effect was also investigated. The MnP pulp bleaching capability was shown to depend on the carboxylic acid used. A combination of Tween 80 and a carboxylic acid resulted in higher pulp brightness than that obtained with Tween 80 alone. A laccase mediator, 3-hydroxy-1,2,3-benzotriazin-4(3H)-one, could also enhance the MnP pulp bleaching effect.
