Optimization of Espresso Spent Ground Coffee Waste Extract Preparation and the Influence of its Chemical Composition as an Eco-friendly Corrosion Inhibitor for Carbon Steel in Acid Medium

• Published in: Materials research (São Carlos, São Paulo, Brazil) Vol. 23; no. 5; p. 1
• Main Authors: Costa, Marina A. J. L. da, Gois, Jefferson S. de, Toaldo, Isabela M., Bauerfeldt, Ana Clara Favilla, Batista, Diego B., Bordignon-Luiz, Marilde T., Lago, Dalva C. B. do, Luna, Aderval S., Senna, Lilian F. de
• Format: Journal Article
• Language: English
• Published: Sao Carlos Universidade Federal do Sao Carlos, Departamento de Engenharia de Materiais 01-01-2020; ABM, ABC, ABPol; Associação Brasileira de Metalurgia e Materiais (ABM); Associação Brasileira de Cerâmica (ABC); Associação Brasileira de Polímeros (ABPol)
• Subjects: Acids; Carbon steel; Carbon steels; Catechin; Chemical Characterization of Food; Chemical composition; Correlation coefficients; Corrosion; Corrosion effects; Corrosion Inhibitor; Corrosion inhibitors; Corrosion prevention; Design optimization; ENGINEERING, CHEMICAL; Ferulic acid; Gallic acid; Green Chemistry; MATERIALS SCIENCE, MULTIDISCIPLINARY; METALLURGY & METALLURGICAL ENGINEERING; Pearson correlation; Phenols; Spent ground coffee; Waste Management; Green Chemistry; Waste Management; Corrosion Inhibitor; Spent ground coffee; Chemical Characterization of Food; Pearson correlation
• ISSN: 1516-1439; 1980-5373; 1980-5373
• DOI: 10.1590/1980-5373-mr-2019-0591

This work proposes the reuse of spent ground coffee waste (SCG) extracts as eco-friendly corrosion inhibitors for carbon steel in acid medium, and the correlation between their anticorrosive efficiency and chemical composition. The extraction method was optimized using a central composite design, and the chemical composition of the extracts was accessed using UV-Vis spectrometry, HPLC, and ICP-OES. EIS and Potentiodynamic Polarization (PP) tests evaluated the anticorrosive properties of the extracts. Total phenol content ranged from 93 mg L-1 to 219 mg L-1 Gallic Acid Equivalent. The highest concentration of phenolic compounds was observed for syringic acid (78.67 mg L-1), while the lowest concentration was verified for (-)-epigallocatechin-3-O-gallate (0.01 mg L-1). The Pearson correlation coefficient showed no correlation between the Rct and the total phenol content, although, positive correlations with the Rct was observed for caffeic acid, (+)-catechin, ferulic acid, and protocatechuic acid. EIS analysis revealed that all of the extracts could act as corrosion inhibitors. The best performance was verified for C3 extract (IE % = 94.83%). PP tests showed that this extract acted as a mixed inhibitor, with a predominant cathodic effect. Therefore, the valorization of the extracts as corrosion inhibitors was successfully achieved.