Prolonged Immersion Time Research Articles

Corrosion Inhibition on Iron with Propargylic Alcohol in Acid Solutions.

The corrosion inhibition of iron by propargylic alcohol (PA) in sulphuric acid was discussed by correlating the corrosion kinetics obtained by DC polarization measurements with surface structure obtained from AC impedance spectroscopy and IR spectroscopy. Both anodic and cathodic reactions were affected primarily by the addition of the inhibitor. Therefore PA can be appreciated as a mixed type inhibitor. The inhibition process was recognized as the substitution adsorption process. The number of water molecules replaced by one molecule of PA was 3. Standard free energy of adsorption, calculated at the corrosion potential Ecorr on the basis of Langmuir type isotherm, was –31.2 kJ mol-1. Impedance spectroscopy revealed that the inhibitor adsorption was nonuniform and led to decreased surface heterogeneity and formation of the protective surface film. IR-spectra of PA-inhibited specimens suggested that the inhibiting film formed after prolonged immersion time at Ecorr was composed of mainly fully saturated hydrocarbons. The stable species of iron carboxylate and alcoxide contributed to strong adhesion of the film to the iron surface as well as to the protective properties of the film.

Texture Modification of ‘Van’ Sweet Cherries by Postharvest Calcium Treatments1

Abstract Calcium (Ca) moved rapidly into sweet cherry fruit (Prunus avium L.) flesh and reached a maximum in 7 days after a postharvest calcium chloride (CaCl2) dip. Flesh Ca content was increased by increasing the CaCl2 or thickener concentration or by prolonged immersion time in the dipping solution. After 21 days of 0°C storage, texture attributes of fruit firmness and bioyield were positively correlated with fresh Ca levels.

Scanning Electron Microscope Study of Stannous Fluoride-Treated Enamel Surfaces

Scanning electron micrographs showed that the reaction products formed on enamel surfaces increased with prolonged immersion time. Sn3F3PO4 crystals and other amorphous and platelike reaction products were present. These findings corroborate the data obtained from similar samples by electron microprobe analyses.