Toxicity of corrosion inhibitors compounds on a neotropical mussel (Perna perna)

Abstract

Metallic corrosion is an economic, technical-scientific and environmental problem that consumes more than 3% of the world's GDP particularly severe and critical concerning civil security of infrastructures immersed in the sea. Current technologies to combat marine corrosion include the application of Corrosion Inhibitors (CI) in protective/primer paints. One of the problems is that most of these CIs (eg. 2-mercaptobenzothiazole) are highly toxic to aquatic organisms, so it has recently been proposed to replace them with bio-based molecules (eg sodium gluconate, glutamic acid), supposedly of low environmental risk. In addition, the use of these substances in a nanostructured form has been suggested aiming at (a) improving the efficiency in the anti-corrosive action, due to the controlled release of the CIs to the surrounding environment only when the corrosion phenomenon appears; (b) decreasing the of incompatibility between paint ingredients and; (c) decreasing the environmental impact of CIs on marine biota. Bio-based technology therefore favors paint companies (the need for a minimal amount of this type of additives and the improvement of the environmental sustainability indicators of the business) and the owners of marine infrastructures (more spaced maintenance represents massive economic savings). In this sense, the immobilization of CIs in low-toxic nanomaterials, such as nano-clay (double-layer hydroxides; LDH), or in mesoporous silica nanocapsules (SiNC) represents a potential and valuable technological advance. However, most of these materials are still under development and there are, naturally, no previous studies reporting the ecotoxicological effects of these substances, both in their free and nanostructured forms, to marine organisms, at individual, physiological, cellular or biochemical levels. This project aims to determine the toxicity of Sodium Gluconate (SG) and Glutamic Acid (GA) ICs, in their free and nanostructured forms, in the Perna perna species, using short and long-term ecotoxicological experiments. Thus, both SG and GA, as well as their respective anti-corrosive nanomaterials (i.e., LDH-SG and LDH-GA, and/or SiNC-SG and SiNC-GA), developed by the University of Aveiro (UA) and supplied under the NANOGREEN project, will be tested as part of an ongoing research involving staff from UA, UNESP and USP. In controlled laboratory conditions, individuals of Perna perna will be exposed to a concentration gradient of these substances and the responses at different levels of biological organization; i.e., biochemical, cellular, physiological and tissue levels, will be evaluated after two exposure times (96h and 14 days), together with the potential bioaccumulation. The results obtained will allow to elucidate the main mechanisms of action of these substances, in order to provide data on the ecological risks related to these compounds, for which there are no studies on neotropical and subtropical species. In addition, they will provide important information for the development and/or adjustment of the design of new anti-corrosive nanomaterials, in order to reduce the environmental impacts of the use of these compounds, their biomonitoring, in addition to generating subsidies for future environmental legislation. (AU)