0000000000306534
AUTHOR
D. Pupillo
Effect of E. coli biofilm formation and removal on passive films on AISI 316L during fermentation processes
Abstract 316L coupons were sanitized in hot water vapour inducing iron enrichment in passive films. Coupons were then immersed in a pilot fed-batch fermenter in presence of E. coli. Sanitization causes iron enrichment in passive films. Fermentation causes the growth of biofilm on the SS, constituted by bacteria embedded in an extracellular polymeric substance. During fermentation SS open circuit potential is very negative due to low oxygen concentration on its surface, while the chelating action of siderophores induces chromium enrichment in the passive film. Disinfection in NaClO for 30 min allows removal of biofilm and formation of a protective passive film.
The Effect of Electronic Properties of Anodized and Hard Anodized Ti and Ti6Al4V on Their Reactivity in Simulated Body Fluid
The electronic properties of barrier and porous layers on Ti and Ti6Al4V were studied. Barrier anodic oxides grown to 40 V on Ti and on Ti6Al4V are both n-type semiconductors with a band gap of 3.3 eV and 3.4 eV respectively, in agreement with the formation of amorphous TiO2. Anodizing to 200 V at 20 mA cm−2 in calcium acetate and β-glycerol phosphate disodium pentahydrate leads to the formation of Ca and P containing porous films with a photoelectrochemical behaviour dependent on the metallic substrate. A band gap of 3.2 eV and the flat band potential of −0.5 V vs Ag/AgCl were measured for the porous oxide on Ti, while optical transitions at 2.15 eV and a significantly more positive flat b…