Effect of ozone on the surface charge and cleanability of stainless steel

Abstract

The effect of ozone on the surface charge and cleanability of stainless steel was studied, using nonporous stainless steel particles. Stainless steel particles were treated with gaseous ozone generated from a pure oxygen-fed ozonizer at concentrations of 0.05 to 1.0% (v/v). X-ray photoelectron spectroscopic analysis showed no significant differences in the binding energies of elements and composition of the outermost surfaces of stainless steel after ozone treatment. Adsorption isotherms of water vapor showed slightly lower affinities for ozone-treated stainless steel particles than for non-ozone-treated particles. In addition, the apparent points of zero charge (pzcapp) of ozone-treated stainless steel particles were situated at points corresponding to more acidic pH values compared with the pzcapp of non-ozone-treated particles. The effects of ozone on the surface properties of stainless steel particles depended on the ozone concentration. These results indicated that the degree of hydroxylation of stainless steel surfaces was reduced by ozone treatment. As a result of ozone treatment, the amount of bovine serum albumin (BSA) adsorbed on stainless steel particles decreased, and the rate of BSA desorption during alkali cleaning increased, probably due to the lower surface charge densities of ozone-treated stainless steel particles.