Carbohydrates as Corrosion Inhibitors of API 5L X70 Steel Immersed in Acid Medium

摘要

Commercially available carbohydrates D(+)-glucose (1), D(+)galactose (2) and lactose (3), along withsome synthesized derivatives Methyl-4,6-O-Benzylidene-α-D-glucopyranosae (4), Methyl 4,6-O-benzylidene-2-O-p-toluenesulfonyl-a-D-glucopyranose (5), Methyl 4,6-O-benzylidene-2,3-di-O-p-toluenesulfonyl-a-D-glucopyranose (6), Methyl 2,3-anhydro-4,6-O-benzylidene-a-D-mannopyranose(7) and 6-methoxy-2-phenyl-7- (prop-2-yn-1-yloxy) hexahydropyran [3,2-d] [1,3] dioxin-8-ol (8), havebeen evaluated as corrosion inhibitors for API 5L X70 steel immersed in HCl 1M, with stationaryconditions. The best corrosion inhibition was achieved by Methyl-4,6-O-Benzylidene-α-D-glucopyranose (4), with 87% efficiency at 50 ppm. Worth noting, D(+)-glucose (1) performed better asa corrosion inhibitor than D(+)galactose (2). Langmuir isotherm studies showed that all the compoundsfollowed a combined chemical-physical adsorption process (according to the Gibbs energy dataanalysis). SEM-EDS studies confirmed the decrease of the corrosion process on the steel surface in thepresence of the corrosion inhibitors.