Preparation and application of self-assembled systems containing dodecylammonium bromide and chloride as corrosion inhibitors of carbon-steel

The application of surfactant systems as inhibitors of corrosion on metallic surfaces is discussed in this work. The focus is now driven to the influence of cationic surfactants’ counterions on the adsorption mechanism at carbon-steel surfaces. The surfactants dodecylammonium bromide (DDAB) and dodecylammonium chloride (DDAC) have been synthesized and used to prepare micellar and microemulsion formulations. The surfactants were dissolved in aqueous hydrochloric acid as micellar solutions, and in microemulsions containing n-hexane as oil phase and butan-1-ol as cosurfactant. After characterization by phase behavior studies, a number of these formulations with varying surfactant concentration have been tested against acidic corrosion on carbon-steel surfaces. Potentiometry assays were carried out to determine the extent of coverage on the metallic surface, and the adsorption mechanism was modeled with the Frumkin isotherm. Efficiencies of corrosion inhibition as high as 98% were obtained for the DDAC systems, and 96% for the DDAB systems. The results suggest that the protective surfactant film could resist changes in pH, salinity and temperature that might occur during typical applications involving metallic equipment or ducts under a broad range of experimental conditions. This is particularly interesting for industrial applications of microemulsions and other self-assembled systems, which could be used as templates for novel formulations of corrosion inhibitors

Evaluation of Lubricating Properties of Diesel Based Fuels Micro Emulsified With Glycerin

<div><p>The mineral diesel oil sold in Brazil, due to environmental reasons; presents sulfur concentration of 10 ppm, which causes a deficiency of lubricity, since sulfur is one of the chemical species that gives a good lubricating characteristic. Poor lubricity affects performance and causes failure of engine parts. This study aimed to evaluate the use of glycerin as an antiwear additive by means of tribological tests of the mineral diesel S10 B7 and 10 formulations of diesel based fuels, microemulsified with 0% (distilled water), 7.5% and 15% of glycerin solution. The formulations were subjected to lubricity tests on HFRR (Hight Frequency Reciprocating Rig) under hydrodynamic lubrication conditions, according to the ASTM D-6079 standard. The results showed that the increased concentration of glycerin added to diesel S10 B7 contributes to improved lubricity and wear reduction.</p></div