Éter-aminas: agentes de flotação na indústria de mineração. Degradação após exposição à radiação UVC em meio aquoso

Abstract

Brazil's mining industry relies heavily on applying ether-amines as flotation agents to separate quartz from iron ore. However, the disposal of these compounds in tailings dams poses potential risks of contamination to nearby water bodies and soil. Studies have shown the toxicological effects of ether-amines on the body, such as reduced white blood cells. Moreover, one of their degradation products, ammonia, can cause eye and skin irritation. Despite these risks, there has been no research on the by-products resulting from the natural degradation of ether-amines in water. This study uses liquid chromatography coupled with high-resolution mass spectrometry to monitor the natural degradation of ether-amines in an aqueous medium and identify the resulting by-products. First, commercially available ether-amine mixtures (Flotigam EDA 3B® and Flotigam 2835®) were analyzed to determine their chemical composition. The results revealed that Flotigam EDA 3B® primarily consists of ether monoamines with the general formula R-O(CH2)3NH2, where R represents a linear alkyl chain composed of 10 (mainly) to 13 carbon atoms. Flotigam 2835® is a mixture of ether diamines with the general formula R-O(CH2)3NH(CH2)3NH2, where R represents a linear alkyl chain with 10 to 14 carbon atoms. Degradation studies were conducted with the only commercially available ether-amine standard, i.e., CH3-(CH2)11-O-(CH2)3-NH2 (3-dodecyl-oxy-propylamine), The results indicated a decrease in concentration over time, suggesting degradation. Tentative structures for the degradation products were proposed using the Compound Discoverer® software, being verified that they are formed via oxidation processes.