Electrochemical and ellipsometric study of the oxide films formed on copper in borax solution: Part II: Effect of ozone

The influence of O3 on the passive behaviour of copper was analysed in the potential region –0.32 to 0.70V vs RHE in borax solutions (pH9.2) through voltammetric techniques and ellipsometry. Oxide formation can be explained as a sequence of Cu2O growth, Cu(ii) chemisorption, and dissolution precipitation steps similar to those corresponding to copper electrodes in deaerated solutions. The role of Cu(ii) chemisorption is discussed in this paper. The progressive accumulation of hydrated layers hinders the reaction between O3 and the metal. O2 and O3 promote growth and dissolution processes (both at open circuit and in controlled potential experiments) but O3 has a stronger effect.     

Kinetics of sunflower oil contamination with polycyclic aromatic hydrocarbons from contaminated recycled low density polyethylene film

The possibility of food contamination with polycyclic aromatic hydrocarbons (PAHs) by rediffusion from polyethylene film made of contaminated recycled polyethylene (PE) was tested. PE was contaminated with PAHs by diffusion from water medium spiked with fluoranthene (FI), pyrene (Py), and benzo(a)pyrene (BaP). The PE was recycled by heating at 150°C for 10 min. The recycling process did not affect the PAH concentration in PE. From the recycled PE, a PE film was made and rediffusion of PAHs from the PE film into a sunflower oil was followed for 600 h at 24°C. Diffusion of PAHs into the oil demonstrated the potential of PAH-contaminated PE as a source of contamination of food. The PAH concentration in vegetable oil was linearly dependent on the square root of the storage time. A kinetic equation for PAH rediffusion from PE film into the oil is proposed.