Adsorption lignin

In the study of nitrosamine adsorption, lignin suspensions were stored at 4 C for less than 15 days. Samples were exposed to 1 M CaCl2, NaCl, LiCl, or water for 30 min or to 0.1 M EDTA for 1 week. Suspensions were centrifuged and supernatants were discarded. 

At low relative humidities, adsorption is due to interaction of water with accessible hydroxyl groups. These are present on the lignin and on the carbohydrates ia the noncrystalline or poorly crystalline regions. The high differential heat of adsorption by dry wood, - 1.09 kJ/g (469 Btu/lb) water. 

At high relative humidities, adsorption is befleved to occur in response to a tendency for cellulose chains and lignin to disperse (solution tendency). Complete dispersion (dissolution) is prevented because of the strong interchain or interpolymer bonding at certain sites or regions. The differential heats of adsorption are much smaller than at low relative humidities. 

To elucidate some enzymatic characteristics of the isolated laccases I, II, and III, substrate specificities for several simple phenols, electrophoresis patterns, ultraviolet spectra, electron spin resonance spectra, copper content, and immunological similarities were investigated. Tyrosine, tannic acid, g c acid, hydroquinone, catechol, pyrogallol, p-cresol, homocatechol, a-naphthol, -naphthol, p-phenylenediamine, and p-benzoquinone as substrates. No differences in the specificities of these substrates was found. The UV spectra for the laccases under stucfy are shown in Figure 4. Laccase III displays three adsorption bands (280, 405, and 600nm), laccase II shows one band 280nm), and laccase I shows two bands (280 and 405 nm). These data appear to indicate differences in chemical structure. The results of the copper content analysis (10) and two-dimensional electrophoresis also indicate that these fractions are completely different proteins (10), Therefore, we may expect differences in substrate specificities between the three laccase fractions for more lignin-like substrates, yet no difference for some simple phenolic substrates. 

As a result of the dependence of universal calibration on column elution behavior (i.e., anomalous behavior due to adsorption or exclusion), the contribution of the polymer core and shell components (33,34) to hydrodynamic behavior must be fully understood if competent analysis of block copolymers and branched heteropolymers is to be made. It is hoped that with the advent of appropriate MW, composition, and branched polymer standards, the limits of fit of universal calibration to biopolymers such as lignin can be judged. 

One disadvantage of using salt solution as eluent is that the lignin sulfonates tend to adsorb onto the gel matrix, resulting in a resolution inferior to that obtained by elution with water. On the other hand, elution behavior with water is adversely affected by the polyelectrolyte properties of the lignin sulfonates. Adsorption, which is caused by the phenolic hydroxyl... 

Palonen, H., Tjemeld, F., Zacchi, G., and Tenkanen, M., 2004, Adsorption of Trichoderma reesei CBH I and EG II and their catalytic domains on steam pretreated softwood and isolated lignin, J. Biotechnol. 107 65-72. 

Figure 2. The effect of PEG-modification on the lignin model compound, dehydro-diisoeugenol (dimer). Solvent = acetonitrile, t =0 is the brightness recorded immediately after adsorption of compound on filter paper. The brightness of untreated filter paper is 80.1%. (Cole, B.J.W. Huth, S.P. Runnels, P.S., /. Wood Chem. Technol., in press.)...

The water retention of cellulose fibers at a given relative humidity varies depending on whether the equilibration has taken place by desorption or adsorption. (hysteresis). The water uptake also continuously decreases after repeated drying and moistening of the fibers. Additional factors influencing the ability of pulp fibers to swell are their chemical composition, such as their hemicellulose and lignin content. 

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