Abstract In the present work, the effect of the different variables involved in the process of aluminum anodizing on the total surface acidity of the samples obtained was studied. Aluminum foils were treated by the electro-chemical process of anodic anodizing within the following variable ranges: concentration = 1.5-2.5 M; temperature = 303-323 K; voltage = 10-20 V; time = 30-90 min. The total acidity of the samples was characterized by two different methods: acid-base titration using Hammett indicators and potentiometric titration. The results showed that anodizing time, temperature and concentration were the main variables that determined the surface acid properties of the samples, and to a lesser extent voltage. Acidity increased with increasing concentration of the electrolytic bath, whereas the rest of the variables had the opposite effect. The results obtained provide a novel tool for variable selection in order to use synthetized materials as catalytic supports, adding to previous research based on the morphology of alumina layers.

Pilot-scale treatments of sunflower oil similar to deodorization were carried out by applying steam stripping at different temperatures ranging from 179 to 282°C for 5 h. Samples were taken every half hour, and fatty acid composition was determined by gas chromatography. The results showed an increase in the relative percentage of trans linoleic acid with an increase in either time or temperature. The formation of trans linoleic acid isomers followed a zero-order reaction and the kinetic constants varied according to the Arrhenius' law. The activation energies for the formation of the acids C18:2ct, C18:2tc and C18:2tt were calculated as 147.4, 147.8 and 146.6 kJ/mol, respectively.