다른 결정성을 갖는 Cellulose에 대한 Cellulase의 비이온성 계면활성제 용액에서의 흡착거동

Adsorption Behaviors of Cellulose on Cellulose with Different Crystallinities in Nonionic Surfactant Solution

The adsorption of cellulase on celluloses with different crystallinities was carried out In nonionic surfactant(Tween 20) solution. Highly crystallized celluloses were prepared by enzymatic prehydrolyzation. From the experiments, the Langmuir isotherm parameters, maximum adsorption amount (Amax) and adsorption equilibrium constant(Kad) for the adsorption, were obtained in the presence and absence of nonionic surfactant. It was found that the Kad values were decreased by adding Tween 20. This indicates that the adsorption affinity is reduced by nonionic surfactant, and Amax decreased with increasing crystallinity under conditions accompanying in both the presence and absence of surfactant. The thermodynamic parameters such as <TEX>$Delta$</TEX>Ha, <TEX>$Delta$</TEX>Ga, and <TEX>$Delta$</TEX>Sa for the adsorption were calculated by using the experimental data. From these results, it was found that the adsorption processes are exothermic reactions in both the presence and absence of surfactant. The heats of adsorption in surfactant solution(-4.68∼-3.62KJmol-1) are smaller than that of the adsorption in the absence of surfactant(-15.60∼-12.10KJmol-1). These results indicated that the tightness of adsorption was reduced by the addition of surfactant. The <TEX>$Delta$</TEX>Sa values were estimated to be positive. This may suggest that the water and solute are released from cellulose on adsorption. The <TEX>$Delta$</TEX>Sa values in surfactant solution are larger than that of the adsorption in the absence of surfactant. This may suggest that the binding of surfactant on hydrophobic region of cellulase cause dispersion of water and solute molecule orienting around the enzyme molecule. The surfactant played an important role in the desorption of enzyme from cellulose functional groups, and enhance the saccharification of the cellulose.