Avaliação ecotoxicológica dos inibidores de corrosão biológicos: Gluconato de Sódio (SG) e Nitrito de Sódio (NO2), em suas formas livres e nanoencapsuladas, sobre embriões de ouriço-do-mar (Echinometra lucunter)
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Data
2023-01-27
Autores
Beverari, Isabella
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Universidade Estadual Paulista (Unesp)
Resumo
O processo de corrosão é um dos grandes desafios da atualidade, principalmente em estruturas e equipamentos no ambiente marinho, sendo uma questão econômica, social e ambiental. Esse problema tem sido minimizado pela aplicação de revestimentos que retardam o processo de corrosão. No entanto, devido a toxicidade investigada de inibidores de corrosão (IC) e regulamentações ambientais mais rigorosas, há a necessidade de novas alternativas eficazes e menos tóxicas. Recentemente, os inibidores orgânicos, gluconato de sódio e nitrito de sódio, já estudados como inibidores de corrosão, tornaram-se opções ambientalmente amigáveis. O uso de nanomateriais, formados de hidróxidos de dupla camada (LDH) para imobilização/encapsulamento dos ICs, visa aumentar a eficiência anticorrosiva dessas substâncias e reduzir sua toxicidade, já que sua liberação é controlada pelas características físico-químicas da água do mar. Neste projeto foi feita avaliação ecotoxicológica do SG e NO2, nas formas livres e nanoestruturadas (Zn-Al LDH SG e Zn-Al LDH NO2), através de ensaios de desenvolvimento embriolarval de ouriço-do-mar Echinometra lucunter. Para isso, organismos adultos de E. lucunter foram coletados e em laboratório foi feita a obtenção dos gametas. Os embriões de ouriços foram expostos a concentrações que variaram de 0,0136 a 100 mg/L, bem como no controle contendo 4 réplicas por concentração. Após cerca de 36 h, os embriões foram fixados e posteriormente contados em microscópio, visando analisar a taxa de desenvolvimento normal da larva em estágio plúteo. Os resultados foram analisados por meio de análise de variância, seguida do teste de Dunnett e determinação da CE50. A taxa de desenvolvimento embriolarval para ouriços-do-mar E. lucunter apresentou os seguintes níveis de toxicidade: Zn-Al LDH NO2 > Zn-Al LDH SG > SG > Zn-Al LDH > NO2, com as respectivas CE50: 0.41; 0.67; 1.21; 6.24 mg/L. Não foi possível calcular a CE50 do NO2. Dentre os compostos testados, NO2 livre apresentou menor toxicidade e sua forma nanoencapsulada maior toxicidade. Portanto, os resultados indicaram a toxicidade dos compostos livres e nanoencapsulados e evidenciam que o uso de inibidores de corrosão necessitam de mais estudos acerca da sua toxicidade, destacando a relevância desse estudo.
The corrosion process is one of today's great challenges, especially in structures and equipment in the marine environment, being an economic, social and environmental issue. This problem has been minimized by the application of coatings that slow down the corrosion process. However, due to the investigated toxicity of corrosion inhibitors (CI) and stricter environmental regulations, there is a need for new effective and less toxic alternatives. Recently, organic inhibitors, sodium gluconate and sodium nitrite, already studied as corrosion inhibitors, have become environmentally friendly options. The use of nanomaterials, formed of double layer hydroxides (LDH) for immobilization/encapsulation of the ICs, aims to increase the anticorrosion efficiency of these substances and reduce their toxicity, since their release is controlled by the physicochemical characteristics of the seawater. In this project, an ecotoxicological evaluation of SG and NO2, in free and nanostructured forms (Zn-Al LDH SG and Zn-Al LDH NO2), was performed using embryolarval development assays with the sea urchin Echinometra lucunter. Adult organisms of E.lucunter were collected and gametes were obtained in the laboratory. The urchin embryos were exposed to concentrations ranging from 0.0136 to 100 mg/L, as well as the negative control (clean sea water). 4 replicates were used for each concentration. After about 36 h, the embryos were fixed and counted under a microscope, in order to quantify the normal development rate. The results were analyzed by analysis of variance, followed by Dunnett's test and determination of the EC50. The embryolarval development rate for E. lucunter showed the following toxicity levels: Zn-Al LDH NO2 > Zn-Al LDH SG > SG > Zn-Al LDH > NO2, with the EC50: 0.41; 0.67; 1.21; 6.24 mg/L. It was not possible to calculate the EC50 for the NO2. Among the tested compounds free NO2 showed lower toxicity and its nanoencapsulated form higher toxicity. The toxicity of the nanoengineered materials (empty or containing the ICs) was higher that the free compounds, possibly due the metals release. Thus, the development of new corrosion inhinitors requires further studies on the environmental risks.
The corrosion process is one of today's great challenges, especially in structures and equipment in the marine environment, being an economic, social and environmental issue. This problem has been minimized by the application of coatings that slow down the corrosion process. However, due to the investigated toxicity of corrosion inhibitors (CI) and stricter environmental regulations, there is a need for new effective and less toxic alternatives. Recently, organic inhibitors, sodium gluconate and sodium nitrite, already studied as corrosion inhibitors, have become environmentally friendly options. The use of nanomaterials, formed of double layer hydroxides (LDH) for immobilization/encapsulation of the ICs, aims to increase the anticorrosion efficiency of these substances and reduce their toxicity, since their release is controlled by the physicochemical characteristics of the seawater. In this project, an ecotoxicological evaluation of SG and NO2, in free and nanostructured forms (Zn-Al LDH SG and Zn-Al LDH NO2), was performed using embryolarval development assays with the sea urchin Echinometra lucunter. Adult organisms of E.lucunter were collected and gametes were obtained in the laboratory. The urchin embryos were exposed to concentrations ranging from 0.0136 to 100 mg/L, as well as the negative control (clean sea water). 4 replicates were used for each concentration. After about 36 h, the embryos were fixed and counted under a microscope, in order to quantify the normal development rate. The results were analyzed by analysis of variance, followed by Dunnett's test and determination of the EC50. The embryolarval development rate for E. lucunter showed the following toxicity levels: Zn-Al LDH NO2 > Zn-Al LDH SG > SG > Zn-Al LDH > NO2, with the EC50: 0.41; 0.67; 1.21; 6.24 mg/L. It was not possible to calculate the EC50 for the NO2. Among the tested compounds free NO2 showed lower toxicity and its nanoencapsulated form higher toxicity. The toxicity of the nanoengineered materials (empty or containing the ICs) was higher that the free compounds, possibly due the metals release. Thus, the development of new corrosion inhinitors requires further studies on the environmental risks.
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Toxicologia ambiental, Toxicidade, Corrosão e anticorrosivos, Nanomateriais