Ecotoxicological evaluation of nanotechnological corrosion inhibitors on benthic organisms.

• Grant number: 24/08793-4
• Support Opportunities: Scholarships in Brazil - Master
• Start date: November 01, 2024
• End date: October 31, 2026
• Field of knowledge: Biological Sciences - Ecology
• Principal Investigator: Denis Moledo de Souza Abessa
• Grantee: Vitória Nogueira Soares
• Host Institution: Instituto de Biociências (IB-CLP). Universidade Estadual Paulista (UNESP). Campus Experimental do Litoral Paulista. São Vicente , SP, Brazil

Abstract

Corrosion is a natural process that results in the gradual degradation of metallic surfaces due to their reaction with the surrounding environment. The marine environment favors the progression of this process, making marine corrosion one of the greatest current challenges from both economic and environmental aspects, thus demanding strategies for its control. Corrosion inhibitors (CI) consist of chemical substances used in protective coatings on ships, oil platforms and rigs, and pipelines, demanding high-cost strategies aimed to mitigate their impacts. 2-mercaptobenzothiazole (2-MBT) is one of the most used CIs, while nitrite (NO2) is a promising anticorrosive molecule considered less toxic than other CIs. Marine sediments are the final and main destination for most contaminants released into water bodies, including CIs, but the impacts of sediment contaminated by them to benthic organisms are poorly studied. The immobilization of CIs in nanomaterials (NM), such as layered double hydroxides (LDH), has been proposed as a promising alternative to reduce the toxic potential of CIs on aquatic organisms. This research aims to evaluate whether the immobilization of two CIs, namely 2-MBT and nitrite (NO2), in LDH will be effective in reducing their toxicity to benthic microcrustaceans, considering the reproduction rate of the copepod Nitokra sp. and the mortality of the tanaid Monokalliapseudes schubarti and the amphipod Tiburonella viscana. Ecotoxicological assays will be performed to estimate the toxicity of 2-MBT and NO2 in their free forms as well as their respective nanostructured forms, MgAl-LDH-MBT and MgAl-LDH-NO2, in addition to the empty nanomaterial (MgAl-LDH). The sediment will be spiked with the compounds following the method proposed by USEPA, and the ecotoxicological assays will follow the respective standard protocols for all three species. Preliminary tests will be conducted to determine the concentration ranges of effect and no-effect for each test species, followed by the definitive tests. The data will be checked for normality using the Shapiro-Wilk test and for homoscedasticity using the Levene test. The lethal concentration to 50% of organisms (LC50-10d) for T. viscana and M. schubartii will be calculated using the Trimmed-Spearman-Karber or the Probit method. In the test with Nitokra sp., the effective concentration to 50% of organisms (EC50-7d) will be calculated by the Probit method. For all tests, the data will also be analyzed by one-way analysis of variance (ANOVA) followed by Dunnett's test to compare mortalities (or fecundity) at each concentration with their respective controls, aiming to estimate the no observed effect concentration (NOEC) and the lowest observed effect concentration (LOEC). The results of these experiments will be used, within a broader project, to assess the potential environmental impacts of these new innovative nanomaterials before their release to the market.