Croton lechleri Extracts as Green Corrosion Inhibitors of Admiralty Brass in Hydrochloric Acid.

Carlos Cevallos-Morillo,Miguel Angel Meneses,Pablo Cisneros-Pérez,Roxana Llive,Maria Del Cisne Guamán,Marvin Ricaurte,Alex Palma-Cando,Carlos Reinoso

doi:10.3390/molecules26247417

Abstract

Croton lechleri, commonly known as Dragon’s blood, is a tree cultivated in the northwest Amazon rainforest of Ecuador and Peru. This tree produces a deep red latex which is composed of different natural products such as phenolic compounds, alkaloids, and others. The chemical structures of these natural products found in C. lechleri latex are promising corrosion inhibitors of admiralty brass (AB), due to the number of heteroatoms and π structures. In this work, three different extracts of C. lechleri latex were obtained, characterized phytochemically, and employed as novel green corrosion inhibitors of AB. The corrosion inhibition efficiency (IE%) was determined in an aqueous 0.5 M HCl solution by potentiodynamic polarization (Tafel plots) and electrochemical impedance spectroscopy, measuring current density and charge transfer resistance, respectively. In addition, surface characterization of AB was performed by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy techniques. Chloroform alkaloid-rich extracts resulted in IE% of 57% at 50 ppm, attributed to the formation of a layer of organic compounds on the AB surface that hindered the dezincification process. The formulation of corrosion inhibitors from C. lechleri latex allows for the valorization of non-edible natural sources and the diversification of the offer of green corrosion inhibitors for the chemical treatment of heat exchangers.

Highlights

Corrosion is the destructive electrochemical attack of a metal by the working environment [1]
Extract CL1 showed both kinds of natural products, while extracts CL2 and CL3 were intentionally enriched in alkaloids and phenolic compounds, respectively
The sample of the latex of C. lechleri was pretreated with ethanol to obtain CL3, which favored the extraction of phenolic compounds [28]

Summary

Introduction

Corrosion is the destructive electrochemical attack of a metal by the working environment [1]. The cost of prevention, maintenance, and replacement of damaged infrastructure associated with corrosive processes have been estimated as 5% of an industrialized nation’s gross domestic product (GDP) per year [2]. The design of heat exchangers, which are devices that transfer thermal energy (enthalpy) between two or more fluids [3], requires material with high thermal conductivity and a low coefficient of thermal expansion (CTA). Copper and its alloys are widely used materials for the construction of heat exchangers [4]. Admiralty brass (AB) shows excellent thermal properties 110 W/m K and CTA of 2.02 × 10−5 ◦ C−1 ) with a nominal chemical composition of 0.04%. The negative effects that fouling and corrosion products might have on the copper-based heat exchangers are well-document [6]

Methods

Results

Conclusion