RESUMO
The pectin from tomato peel waste (TPP) was employed as tin corrosion inhibitor with the aim to enhance the knowledge regarding the application of natural inhibitors, instead synthetic, and reducing the waste disposal for value-added biopolymers production. To evaluate the TPP anticorrosion activity the commercial apple pectin (CAP) was also utilised. The gravimetric tests show that the highest inhibitive impact (η) of 75.9 % (CAP) and 73.9 % (TPP) are gained at concentration of 20 g L-1. By electrochemical, potentiodynamic polarization and impedance spectroscopy measurements, the maximum η (60.05-65.5 %) are reached at lower concentration (4 g L-1), due to tendency of pectins to form viscous solution. The prominent decreases in current density with the shifts of potential in the cathodic direction revealed that pectins provided cathodic protection of tin surface. Similar inhibition impact of pectins, and fine agreement between applied methods confirmed their suitability against tin corrosion.
RESUMO
BACKGROUND: The innovative titanium-magnesium composite (Ti-Mg) was produced by powder metallurgy (P/M) method and is characterized in terms of corrosion behavior. MATERIAL AND METHODS: Two groups of experimental material, 1 mass% (Ti-1Mg) and 2 mass% (Ti-2Mg) of magnesium in titanium matrix, were tested and compared to commercially pure titanium (CP Ti). Immersion test and chemical analysis of four solutions: artificial saliva; artificial saliva pH 4; artificial saliva with fluoride and Hank balanced salt solution were performed after 42 days of immersion, using inductively coupled plasma mass spectrometry (ICP-MS) to detect the amount of released titanium ions (Ti). SEM and EDS analysis were used for surface characterization. RESULTS: The difference between the results from different test solutions was assessed by ANOVA and Newman-Keuls test at p<0.05. The influence of predictor variables was found by multiple regression analysis. The results of the present study revealed a low corrosion rate of titanium from the experimental Ti-Mg group. Up to 46 and 23 times lower dissolution of Ti from Ti-1Mg and Ti-2Mg, respectively was observed compared to the control group. Among the tested solutions, artificial saliva with fluorides exhibited the highest corrosion effect on all specimens tested. SEM micrographs showed preserved dual phase surface structure and EDS analysis suggested a favorable surface bioactivity. CONCLUSION: In conclusion, Ti-Mg produced by P/M as a material with better corrosion properties when compared to CP Ti is suggested.
RESUMO
Over past decades ionic liquids, a promising alternative to traditional organic solvents, have been dramatically expanding in popularity as a new generation of chemicals with potential uses in various areas in industry. In the literature these compounds have often been referred to as environmentally friendly; however, in recent years the perception of their greenness dramatically changed as the scientific community began to proactively assess the risk of their application based on the entire life-cycle. This review gives a brief overview of the current knowledge regarding the potential risks linked to the application of ionic liquids - from preparation to their disposal, with special emphasis on their potential environmental impacts and future directions in designing inherently safer ionic liquids.
