2006 年 57 巻 4 号 p. 290
The effect of gaseous ozone on the cleanability of 316 L stainless steel was studied using its nonporous particles pretreated with heat-drying at 150°C, heating at 400°C, and immersion in 10% nitric acid. Bovine serum albumin (BSA) was used as the model fouling material. Dried, heated, and HNO3-treated particles showed largely different surface chemical composition and the surface charge density (σapp). Treatment of the above pretreated particles with 0.2% gaseous ozone resulted in decreases in the positive σapp values of the particles, with only slight variations in their surface chemical composition. The saturation amounts of BSA adsorbed (Γsat) on dried particles decreased significantly (P<0.05) after ozone treatment, whereas those on heated and HNO3-treated particles were not changed. These phenomena were correlated with the degree of a decrease in the positive σapp of the particles after ozone treatment. In continuous cleaning in a plug-flow column fed by a 0.1 M NaOH solution, it was indicated that the rate and efficiency of BSA desorption from all the particles increased as a result of ozone treatment. Kinetic analysis showed that significantly smaller proportions of a slower-desorbing BSA molecule and significantly higher values of first-order desorption rate constants were obtained for the ozone-modified particles than for their non-ozone-modified particles (P<0.05). It was indicated that the cleanability of stainless steel particles could be improved by gaseous ozone treatment irrespective of the surface chemical composition of the original particles.
