A study of the permeability of a dilute xylan solution passing through NKP and LKP beds was carried out. A dilute beech wood xylan or corn cob xylan solution had the characteristic permeability through the pulp beds than that of water or a xylan solution treated by heating over 60°C. The fluent flow of the dilute xylan solutions passing through the pulp beds was proved to be unexplainable with Darcy's law. The characteristic permeability was suggested to be mainly caused by the interaction between xylan molecule in an aqueous solution and the surface of capillary wall in pulp bed.
The changes in viscosity, transmitance and specific rotation of 1% xylan solution or in the absorption of xylan-acridine orange system were examined in detail with measurements in the range of 20 to 90°C. The changes were sigmoidal, and were remarkable by heating over about 50°C. An extrinsic optical activity was induced in the wavelength region corresponding to the absorption bands of acridine orange only when the dye combined with the ordered structure of xylan in an aqueous solution. The results indicated that the transition of the ordered structure of xylan to randam-coil one occures by heating treatment, and the transition is reversible.
From the facts described above, it was assumed that the permeability of a dilute xylan solution passing through wood pulp beds reduces remarkably with the transition of the ordered structure of xylan to randam-coil one.
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