Influencia de los mucilagos de las plantas Linum usitatissimum y Chondracanthus chamissoi sobre la inhibición de la corrosión del acero ASTM-A 335 grado P11 en una solución de HCl 1M con rango de temperaturas de 25°C a 65°C

ABSTRACT The influence of the mucilage of the plants Linum usitatissimum and Chondracanthus chamissoi on the corrosion inhibition of steel ASTM -A335 grade P11 in a solution of HCl 1M in a temperature range of 25 ° C to 65 ° C was studied using weight loss techniques, extrapolation of Tafel, electrochemical frequency modulation, resistance to linear polarization and electrochemical impedance spectroscopy. Two-factor design was used for both cases with six levels of mucilage dosage (0.00, 0.05, 0.10, 0.50, 1.00 and 1.50 g / l) and three temperature levels of the corrosive medium (25 ° C, 45 ° C and 65 ° C), three replicas of the experiment were made, obtaining 54 experimental runs, according to randomized design of tests for each technique used. The mucilages were extracted from the seeds of Linum usitatissimum and the alga Chondracanthus chamissoi, whose components were characterized by infrared spectrometry with Fourier transform. The test pieces for weight loss tests were sheets of P11 steel with an exposed area of 12 cm2, according to ASTM G1 and ASTM G31 standards and the test pieces for electrochemical tests were cylinders of 3.5 cm2 of exposed area. Both mucilages showed optimal corrosion inhibition efficiency, for the five techniques used, the mucilage of Linum usitatissimum obtained with 0.5 g / l, average efficiencies of 77.3%; 81.2% and 88.6% for 25 ° C, 45 ° C and 65 ° C respectively, while mucilage of Chondracanthus chamissoi obtained average efficiencies of 79.5%; 84.4 and 91.2 with 1.0 g / l. In both cases the mucilage dosage increases only generated a slight increase in the inhibition efficiency. The efficiency of inhibition and adsorption of the mucilage of Linum usitatissimum increased with the increase in temperature, indicating that the adsorption occurs by chemisorsion. For Chondracanthus chamissoi depends on the concentration, for 1g / l, increases it, this indicates mixed desorption. The results of the calculated thermodynamic parameters, about the type of adsorsion of both mucilages and for each electrochemical technique used showed high concordance.The five techniques used to evaluate the inhibitory effect of mucilages showed good concordance of results, the behavior of both mucilages in this case are adjusted to the isotherm of Langmuir's adsorption.