The influence of dissolved substances on resin adsorption to TMP fine material

The adsorption of dissolved hemicelluloses and colloidal resin (extractives) to TMP fines fractions was studied. This was done by adding the colloidal resin to suspensions of fines while changing the extent of steric stabilization (i.e., the adsorption of hemicellulose) of the colloids and the ionic strength of the solution. The fines were produced by repeated refining of mechanical pulp, collecting and characterizing the fines from the consequtive refining stages. Colloidal wood resin adsorbed on flake-like fines independently of ionic strength and the presence of dissolved hemicelluloses. Sterically stabilized colloids did not adsorb on fibrillar fines at high ionic strength. The relative amounts of cellulose, lignin and extractives in the surfaces of the fines were investigated by x-ray photoelectron spectroscopy (ESCA/XPS). Adsorption of dissolved hemicelluloses to model surfaces of cellulose, lignin and extractive was studied with a quartz crystal microbalance. This was done in order to reveal the reason for the selectivity of colloidal resin adsorption to flake-like fines. Galactoglucomannan and mixture of dissolved substances from unbleached TMP both adsorbed on the extractive and cellulose surfaces. Only small amounts of dissolved hemicelluloses adsorbed on the lignin surface. Adsorption increased if the ionic strength was increased during the adsorption process. The extractive surface remained hydrophobic after adsorption of dissolved hemicelluloses. It was concluded that the adsorption of resin to flake-like fines at all ionic strengths probably occurred because the amount of extractives in the surface of the flakes was higher than in that of the fibrils.