Cleaning of a stainless steel surface fouled with protein using a UV-H₂O₂ technique

The UV-H₂O₂ technique, which is commonly known as a method of decomposing organic substances from wastewater, was applied into cleaning of a stainless steel surface fouled with protein. On a stainless steel surface fouled with bovine β-lactoglobulin (β-Lg), H₂O₂ solution was made to flow, and UV rays were irradiated over the flowing liquid. The amounts of β-Lg adsorbed before and during the UV-H₂O₂ cleaning were measured by a reflection absorption technique using Fourier transform infrared spectroscopy (RA-IR). The adsorbed amount approximately decreased linearly with time during the UV-H₂O₂ cleaning. There was an optimum H₂O₂ concentration for the removal rate. The H₂O₂ concentration dependency of the removal rate could be explained by considering the formation and disappearance rates of hydroxyl radicals (•OH), the decay of UV illuminance along the depth of the flow, and the rate of reaction between adsorbed β-Lg and •OH.