Lanthanum Derivative from “Tara” Tannin for Steel Temporary Protection

D'ALESSANDRO, ORIANA; SELMI, GONZALO J.; DEYÁ, CECILIA; DI SARLI, ALEJANDRO; ROMAGNOLI, ROBERTO

INDUSTRIAL & ENGINEERING CHEMICAL RESEARCH

AMER CHEMICAL SOC

Año: 2018

0888-5885

Tannins are extracted from certain plants andcontain numerous phenol groups. They may be employed,together with their derivatives, to formulate protective coatingsdue to their inhibitive properties. The objective of this researchwas to synthesize lanthanum ?tannates?, to formulate washprimers.Two ?Tara? (Caesalpinia spinosa) tannins and 0.1 MLa(NO3)3 were employed to obtain the correspondingtannates. The inhibitive action of the tannates was evaluatedby linear polarization and corrosion potential measurementsemploying a SAE 1010 electrode. Lanthanum tannates wereused to formulate wash-primers whose anticorrosion performancewas evaluated by corrosion potential and ionic resistancemeasurements. The primers were incorporated in alkyd paint systems and their anticorrosion performance was tested in the saltspray chamber and by electrochemical impedance spectroscopy. Lanthanum tannate primers protected steel and behaved in asimilar way to that formulated with zinc tetroxychromate.