Facilitation of Cleaning of Alumina Surfaces Fouled with Heat-Treated Bovine Serum Albumin by Ozone Treatment

Facilitation of cleaning of alumina (Al2O3) particles fouled with heat-treated bovine serum albumin (BSA), which contains sulfhydryl groups on the molecule, by gaseous ozone was studied. With increasing temperature of heat treatment, the amount of adsorbed BSA onto Al2O3 surfaces increased, whereas the rate of BSA desorption during alkali cleaning decreased markedly, resulting in the larger amounts of BSA remaining on Al2O3 surfaces. No significant amounts of BSA were removed from Al2O3 surfaces by alkali cleaning alone when treated at temperatures above 120°C. Before alkali cleaning, the heat-treated, BSA-fouled Al2O3 at 150°C were treated with 0.05 to 0.30% (vol/vol) gaseous ozone at room temperature. Ozone pretreatment markedly accelerated the rate of BSA desorption during subsequent alkali cleaning. The effect of ozone pretreatment on BSA removal depended on the concentration of ozone and treatment time and hence on the total amount of ozone supplied. The molecular weight (MW) of desorbed BSA during alkali cleaning without ozone pretreatment coincided with the MW of the native BSA, whereas the MW of desorbed BSA during the combined ozone-alkali cleaning was lower than the MW of the native BSA. This indicated that the heat-treated BSA molecules adsorbed on Al2O3 were partially decomposed into some fragments by ozone pretreatment, resulting in the facilitation of the removal of BSA during alkali cleaning.